JP4076568B2 - Vacuum casting method, casting system and vacuum casting apparatus - Google Patents

Description

The present invention relates to generalization, high accuracy, and high productivity of a vacuum casting method.

  The present invention relates to a casting method in which a gas-permeable mold is depressurized by a depressurization apparatus, and gravity pouring is performed from the upper part or side of the mold. Hereinafter, this casting method is referred to as a reduced pressure casting method in the present specification.

  Here, as the air-permeable mold, a mold formed using sand particles is the most general, but a mold formed using ceramic particles or metal particles is also widely used. Further, even a mold that is hardly breathable, such as plaster, can be regarded as a breathable mold if mixed with a breathable material or partially used to impart breathability. Further, even in the case of a mold having no air permeability, a mold provided with air permeability by providing a plurality of air holes and vent holes can be regarded as a gas permeable mold. The breathable mold in the present invention includes these breathable molds described above.

  The vacuum casting method is a casting method in which molten metal is poured with the mold cavity in a negative pressure lower than atmospheric pressure. The purpose of depressurization is, in part, to suck in air that exists in the cavity during pouring, and gas bodies such as gas generated from the mold and core (in the present invention, the collective term for air and generated gas). This is to prevent the generation of back pressure that impedes the filling of the molten metal into the cavity details. Another is to prevent the gas body from getting caught in the molten metal by sucking and discharging the gas body. The purpose of these is to prevent poor hot water and gas defects.

In general, the vacuum casting method requires an airtight container that accommodates the mold and special airtight means, so it is more expensive than the non-depressurized casting method. It is applied to thin-walled products and complex products. Of course, it is important to reduce the back pressure and prevent the gas body from getting caught in the molten metal even in general products, and the vacuum casting method is an excellent casting method applicable to all castings.

  The vacuum casting method is roughly classified by the decompression method, and the whole mold decompression method in which the entire mold is enclosed in some airtight container and decompressed, and the semi-total decompression method in which almost the entire surface is enclosed in some kind of airtight container excluding a part of the mold and decompressed. The most part of the mold can be classified into a partial decompression method in which a part of the mold is opened and decompressed from a part. In the following, since these are explained, the whole decompression method is classified with the symbol W, the semi-total decompression method with S, and the partial decompression method with P.

In addition, although it is a kind of vacuum casting method, there is also a method for discharging a gas body from a mold with little consideration on the pressure reduction of the cavity. This is a classification symbol G.

  Next, features of each decompression method will be described.

  First, in the overall decompression method, as the most general method, decompression is performed by storing a mold in an airtight container communicated with a decompression device. Therefore, basically, the inside of the mold cavity is in a uniform reduced pressure state. And from this state, pouring is performed through the gate. (Classification symbol W1)

Such an overall pressure reduction method using an airtight container requires an airtight container connected to a pressure reducing device, or requires a process of accommodating the mold in the airtight container and taking out the mold from the airtight container after completion of casting. There are production restrictions.

  As another example of the whole decompression method, there is a method in which decompression is performed by covering the entire mold with a flexible resin material such as vinyl. In this decompression method, there is a restriction that vinyl becomes a consumable material, and a process of covering and removing vinyl is required. (Classification symbol W2)

  As another example of the whole decompression method, there is a method of performing decompression while maintaining airtightness by combining an airtight container with an open top and vinyl or the like. This method is an intermediate feature of the two methods. (Classification symbol W3)

  In the semi-wide pressure reduction method, a mold is accommodated in a vacuum container having an open surface, and the pressure is reduced by surrounding the mold with sand. (Classification symbol S)

  Since this method is open on one side, the degree of decompression of the cavity is low, but the entire cavity has a uniform decompression to some extent. The main purpose is to discharge the generated gas from the mold. This method requires a decompression vessel connected to the decompression device, as in the overall decompression method, and a production restriction such as requiring a process of storing the mold in the decompression container and taking out the mold after completion of casting. There is.

  In the partial decompression method, the pressure is reduced from a part of the mold, and basically the other mold parts are open to the atmosphere. Therefore, air flows into the cavity from the open portion. The feature of this method is that the molten metal is filled under a reduced pressure so as to create a one-way air flow or a reduced pressure gradient in the cavity at a low degree of vacuum.

  The specific decompression method of the partial decompression method is classified as follows. (1) A method in which a vent hole is provided in the upper and lower mold mating surfaces of the mold, and suction is reduced from there (classification symbol P1). (2) A method in which a suction hole is provided from the outside of the mold at a place where suction and pressure reduction is desired and the pressure is reduced from there (classification symbol P2). (3) A method in which a suction guide is arranged from the outside of the mold at a place where suction and pressure reduction is desired and the pressure is reduced from there (classification symbol P3). (4) A method (classification symbol P4) in which a material having better air permeability than the mold is placed in a part of the mold and suction is reduced therefrom. These will be described in detail in the prior art disclosed in the patent literature, but there are problems in terms of restrictions on the molds used and compatibility with a plurality of molds.

  Based on the above classification of the vacuum casting method, the prior art will be described with respect to the vacuum casting method disclosed in the patent literature, its apparatus, and mold.

  In Patent Document 1 (Japanese Patent Application Laid-Open No. 61-180642), an air-permeable mold is placed in a chamber, and a pouring hole is closed with a material that can be melted, and then the chamber is decompressed to a predetermined pressure. A vacuum casting method is disclosed. This corresponds to the classification symbol W1. This method requires a chamber that can be depressurized and has a long process time.

  Patent Document 2 (Japanese Patent Laid-Open No. 7-265998) discloses a vacuum casting mold in which the thickness of the mold of the product and the design cavity is changed in a room temperature curing mold that is vacuum cast. This corresponds to W1 of the classification. This method is possible only under the condition that the mold is a room temperature curing mold.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2003-170226) discloses a reduced pressure casting method in which a sensor is arranged in a mold for performing a total pressure reduction, and a pressure reducing operation is started after detecting that a molten metal has flowed in. . This corresponds to W1 of the classification. In this method, if the pressure is reduced before pouring, the molten metal is disturbed. Therefore, as a countermeasure, the pressure is reduced after detecting the inflow of the molten metal to obtain a good hot water flow. In this case, there are restrictions that some kind of airtight means is necessary and expensive sensors are arranged so that it cannot be applied to many molds.

  In Patent Document 4 (Japanese Patent Laid-Open No. 3-216258), the entire surface around the mold is airtightly covered with a sand-type cover made of a resin film, and an exhaust port is provided at a position sufficiently away from the gate, and the pressure is reduced from there. An apparatus is disclosed. This corresponds to W2 of the classification. This device does not require an airtight container, but requires a consumable such as vinyl, and a process of covering and removing the vinyl.

  In Patent Document 5 (Japanese Patent Laid-Open No. 60-124438), a gypsum mold made without a frame is placed on a suction box having a vent hole, and the gypsum mold is covered with a film sheet, and the pressure is reduced from the suction box. A vacuum casting method in which pouring is then performed is disclosed. This corresponds to W2 of the classification. This method still requires a consumable such as vinyl, and also requires a vinyl coating and removal process.

  In Patent Document 6 (Japanese Patent Publication No. 7-115119), in the disappearance model casting method, a suction mechanism is provided on the side wall of the upper and lower open cast frames, and an airtight sheet is closely attached to the upper and lower sides of the cast frame to reduce the suction pressure. A casting method is disclosed. This corresponds to W3 of the classification. In this method, a special casting frame provided with a suction mechanism on the side wall is necessary, the upper and lower airtight sheets are consumables, and a process for coating and removing the airtight sheet is necessary.

  In Patent Document 7 (Japanese Patent Application Laid-Open No. 6-122060), an organic binder mold is molded into a casting frame having a vent hole, and this is set in a steel-steel chamber having an open top and is in a reduced pressure state. Discloses a vacuum casting method in which hot water is poured. This corresponds to S in the classification. This method has a limitation that a steel-steel vacuum chamber is necessary and an organic caking mold.

  Patent Document 8 (Japanese Patent Laid-Open No. 8-103861) discloses a vacuum casting method in which a sand mold is embedded in foundry sand in a top-open type vacuum container and molten metal is poured under a suction pressure reduction state. This corresponds to S in the classification. This method requires a vacuum container. The purpose is to prevent molten metal from blowing up during pouring.

  Patent Document 9 (Japanese Patent Application Laid-Open No. 57-31463) discloses a method for manufacturing a thin-walled casting in which the inside of a cavity is sucked and poured through a vent hole provided at a position farthest from the pouring gate position of a mold. Has been. This corresponds to P1 of the classification. In this method, since a vent hole is provided on the mold mating surface, it is difficult to accommodate a plurality of molds. In addition, there is a problem in equipment because a suction hole is provided in the casting frame.

  In Patent Document 10 (Japanese Patent Laid-Open No. 6-55255), a hot water supply or a skein is provided at a position separated from the weir part of the mold, a hole part communicating with the outside is provided nearby, and the pressure is reduced from the hole part. A method of manufacturing a steel casting that is cast while being disclosed is disclosed. This corresponds to P2 of the above classification.

  In this method, since the decompression is a local decompression of the open mold, the degree of decompression is low, and the molten metal is sucked and filled by a decompression that causes an air flow in one direction. However, there is a restriction that a feeder or a skein must be provided at a position separated from the weir portion of the mold.

Similarly, Patent Document 10 is provided with a pressure reduction rate control means for reducing the pressure so that the molten metal injection rate is constant, or by providing a molten metal level detection sensor in the dam and starting pressure reduction immediately after detecting the molten metal. Methods and the like are also disclosed. In this case, a decompression speed control means, a hot water level detection sensor, and the like are required.

  In Patent Document 11 (Japanese Patent Laid-Open No. 6-226423), a suction member having the same configuration as that of Patent Document 10 and having a larger air permeability than the mold is provided between the vacuum suction port and the feeder or the skein. A method for producing a thin casting in which the pressure in the side cavity is greater than that of the gate side cavity is disclosed. This corresponds to P2 of the above classification. In this method, a suction member is further required in addition to the limitations of Patent Document 10.

  Patent Document 12 (Japanese Patent Application Laid-Open No. 9-85421) discloses a reduced pressure casting method in which a core baseboard set in a mold is provided with a hole portion communicating with the outside and decompressed. This corresponds to P2 of the above classification. This method is applicable only to castings with a core.

  Patent Document 13 (Japanese Patent Application Laid-Open No. 4-147760) discloses a suction casting mold provided with a suction guide that forms a suction passage between a portion where pressure reduction is required in the mold space and the outside of the mold. This corresponds to P3 of the above classification. This method requires a step of providing a suction guide on the mold.

  Patent Document 14 (Japanese Patent Application Laid-Open No. 60-56439) discloses a gypsum mold for reduced pressure casting provided with a filter made of a refractory material having better air permeability than gypsum from the vicinity of the final filling portion of the gypsum mold to the outer surface. ing. This corresponds to P4 in the above classification. In the method using the mold, man-hours are required for producing the gypsum mold, and the productivity is low.

  Patent Document 15 (Japanese Patent Publication No. 7-41400) discloses a suction casting method in which the gas generated from the green mold and the gas generated from the core are individually sucked and the suction pressure is individually adjustable. Has been. This corresponds to G of the classification. This is for the purpose of sucking and discharging gas.

  The following is a summary of the conventional techniques such as the reduced pressure casting method, the apparatus, the mold and the like disclosed in the above patent documents.

  First, in the overall vacuum casting method, in the method (W1) in which the mold is housed in an airtight container that can be decompressed and the pressure is reduced, a special airtight container is required, and the mold is housed in or taken out from the airtight container. Since a process is required, there is a problem that the casting tact is long, and it is difficult to construct a continuous line capable of high-efficiency production.

Also, in the method of covering the mold with a non-breathable cover member such as vinyl (W2), casting is necessary because vinyl is used as a consumable material every time and a process of covering and removing vinyl is necessary. There is a problem that the tact is long, and it is difficult to construct a continuous line capable of high-efficiency production as with W1.

  Furthermore, the method (W3) of using the airtight container and the non-breathable cover member in combination is the same as W1 and W2.

  As a result of the above, the overall reduced pressure casting method has the feature that the entire mold can be uniformly decompressed, but (1) a special airtight device or member is required for airtightness of the mold, and man-hours are also required. It is difficult to configure a continuous line capable of automated, high-efficiency production. For this reason, the manufacturing cost is high, and it is generally applied to castings with high added value.

  Next, the semi-total reduced pressure casting method (S) is almost the same as the entire reduced pressure casting method.

  Next, the partial reduced pressure casting method (P) is characterized in that the melt is sucked and filled by creating a one-way air flow in the cavity in a state where the overall degree of decompression is low. However, (2) partial pressure reduction is provided by providing vent holes, suction holes, suction guides, highly breathable materials, etc. in the mold. Sometimes it is not possible.

  Next, problems common to the conventional whole vacuum casting method, semi-total vacuum casting method, and partial vacuum casting method will be described.

  First, (3) in any vacuum casting method, the entire vacuum is reduced to create a uniform vacuum distribution, or a vacuum is created from one part of the mold to create a simple one-way vacuum gradient. The hot water is poured in either reduced pressure state. That is, the molten metal cannot be poured in a reduced pressure state in which the reduced pressure distribution in the cavity is controlled with high accuracy to create a predetermined reduced pressure distribution appropriate for the target casting.

  In addition, the fact that a highly accurate predetermined decompression distribution has not been created in the cavity means that each casting in a plurality of castings in which a plurality of castings can be put in one frame that is most commonly performed. This means that the molten metal has not been poured in a state where an appropriate reduced pressure distribution is created for the cavity. For this reason, it is insufficient in terms of measures against poor hot water and gas defects.

  In addition, since a highly accurate predetermined reduced pressure distribution cannot be created in the cavity, the characteristic that the molten metal flow property originally possessed by the reduced pressure casting method is good is not utilized. Therefore, a significant cost reduction factor is overlooked.

  Next, (4) in any of the reduced pressure casting methods, since all the cavities of the mold are filled when pouring, the injection yield is low. That is, the mold cavity is generally composed of cavity parts such as a product part, a feeder part, a runner part, a gate part, etc. Of these, only the product part is finally required after casting. The other parts are only necessary in the pouring process or the solidification process and are essentially unnecessary parts. However, all of this is filled when pouring. Therefore, the injection yield is low, and post-processes such as unpacking and finishing are complicated, and a large cost reduction factor is overlooked.

Next, (5) in any of the reduced pressure casting methods, the control from the completion of the pouring to the solidification, cooling, and demolition is not performed. That is, the pressure reduction state is controlled until the pouring is completed, but after the pouring is completed, a method of whether to stop the decompression or simply continue the decompression is performed. That is, after completion of pouring, (a) directional solidification is not controlled. (B) The coagulated tissue is not adjusted. (C) The heat energy of the molten metal has not been recovered. For this reason, the elements of cost reduction and high accuracy in casting production are overlooked.

  As described above, although the conventional vacuum casting method has excellent characteristics, there are problems (1) to (5), and the characteristics are not fully utilized.

For the reasons described above, the conventional vacuum casting method is currently used as a special casting method for special materials, thin-walled products, and complex products. As a result, the production volume by the vacuum casting method using the air-permeable mold is less than 1% of the entire casting production volume. If a method that can make full use of the features of the vacuum casting method can be invented, it will be possible to innovate the casting technology and make the casting an extremely superior manufacturing method over other methods. The present invention has been made from such a viewpoint.

JP 61-180642 A JP-A-7-265998 Japanese Patent Laid-Open No. 2003-170226 Japanese Patent Laid-Open No. 3-216258 JP-A-60-124438 Japanese Patent Publication No.7-115119 JP-A-6-122060 JP-A-8-103861 JP-A-57-31463 JP-A-6-55255 JP-A-6-226423 JP-A-9-85421 JP-A-4-147760 JP 60-56439 A JP 7-41400 A

  The present invention is to solve the following problems in view of the above problems of the prior art.

(1) Provided is a vacuum casting method capable of forming a continuous line capable of high-efficiency production using a normal air-permeable mold. (2) To provide a reduced pressure casting method that can easily cope with individual casting products and support for a plurality of casting products. (3) To provide a reduced pressure casting method in which a predetermined highly accurate reduced pressure distribution is created in a mold cavity. (4) Provided is a vacuum casting method in which a molten metal is filled only in a desired cavity which is a part of a mold cavity. (5) To provide a high-efficiency, high-accuracy vacuum casting method and casting system that controls the process from pouring to solidification, cooling, and frame removal.

The effects of solving the above problems are as follows. (1) makes it possible to generalize the reduced-pressure casting method, and it is possible to improve the accuracy of the entire casting production. By (2) and (3), a highly accurate reduced pressure casting method that can be applied to a high-efficiency continuous line with multiple varieties and a plurality of packages can be established, and casting of thin-walled products and complex products is further facilitated. (4) makes it possible to establish a vacuum casting method with an extremely high yield, and to greatly simplify the post-process after the frame opening. According to (5), the heat energy of the molten metal can be used and recovered to greatly improve the casting cost. It also contributes greatly to environmental aspects such as CO ₂ reduction.

  In the conventional general vacuum casting method using a general air-permeable mold, the mold or the vanishing model is accommodated in an airtight container that can be decompressed, or the whole is covered with a non-air-permeable member such as vinyl, and the molten metal is decompressed. Done. Therefore, it is superior to the normal casting method without decompression in terms of hot water circulation and gas defect countermeasures.

However, in terms of productivity, a special airtight container and a non-breathable member such as a consumable material such as vinyl are required. Therefore, the process is complicated, the time is long, and the manufacturing cost is high. For this reason, the overall vacuum casting method has been adopted for special materials, thin-walled products, and complex products. FIG. 40 shows an example of an overall reduced pressure casting method using the most common hermetic container of the prior art.

  In this means, first, an air seal member for preventing the inflow of air is provided on the upper surface and / or the lower surface of a normal casting frame. Then, a breathable mold is formed on the casting frame with a mold material made of a granular material, and the upper and lower molds are matched and placed on a surface plate. A cart or the like may be used instead of the surface plate. In short, it is only necessary that the air seal member can be kept in contact with the air seal member of the casting frame.

  Next, an airtight member made of a non-breathable material that prevents the inflow of air is also placed on the upper surface of the upper frame of the airtight mold, and the pressure is reduced through a suction hole provided in at least one location of the airtight member. It is for pouring hot water.

In this means, a normal cast frame, an air seal member, and an airtight member constitute the same function as the airtight container in the conventional general vacuum casting method.

  That is, the lower surface of the lower frame is in contact with the surface plate, but this portion is kept airtight by an air seal member provided on the lower surface of the lower frame. The mating surfaces of the upper and lower cast frames are also kept airtight by the air seal member. The upper surface of the upper frame is in contact with the airtight member, but this portion is also kept airtight by an air seal member provided on the upper frame. That is, the airtightness between the casting frames, the surface plate and the airtight member is maintained by the air seal member of the casting frame.

  And it is only the suction hole provided in the airtight member that the air-permeable mold communicates with the outside atmosphere, and this is communicated with a general decompression device to perform decompression. Of course, a hole for pouring is provided in the airtight member, but this is kept airtight by sealing with an appropriate non-breathable member at the time of decompression, preferably a non-breathable member that disappears or melts by the heat of the molten metal. be able to.

  As the air seal member, a non-breathable member such as a heat resistant packing is used. Alternatively, a member with low air permeability can be used if a slight air inflow can be allowed.

  Any material can be used as long as the airtight member is non-breathable and can be provided with a suction hole. For example, a metal decompression hood or an iron that is also used as a mold weight can be used. A resin material such as flexible vinyl can also be used.

If at least one suction hole is provided in the hermetic member, the entire mold can be decompressed. In addition, two or more locations can be provided to quickly bring the entire mold into a uniform reduced pressure state.

  As described above, this means is a conventional special airtight container by applying an air seal member and an airtight member in a gas-permeable mold with a casting frame that is generally used in a continuous line capable of high-efficiency production. The same operation and effect as the vacuum casting method using That is, the present invention provides a vacuum casting method that can be easily applied to a continuous line capable of high-efficiency production. Details will be described in Examples 1 to 3.

(Means 1)
A plurality of ventilation holes having different diameters and / or depths from the outer surface to the inside of the mold are provided on at least one outer surface of the breathable mold, and the plurality of ventilation holes in the mold are decompressed from the outer surface of the breathable mold. This is a reduced pressure casting method characterized in that a partial reduced pressure zone is formed around each hole, and a predetermined reduced pressure distribution is created in the cavity of the air-permeable mold to pour molten metal.

  The present means provides a reduced pressure casting method in which a predetermined reduced pressure distribution is created with high accuracy in the mold cavity in the overall reduced pressure method.

  In this means, first, a plurality of vent holes having different diameters and / or depths from the outer surface to the inside are provided on at least one outer surface of the breathable mold. In the case of a mold with a cast frame, the at least one outer surface is the upper surface and / or the lower surface of the mold. In the case of a mold without a casting frame, a vent hole is provided in at least one surface of the outer surface of the mold, and the other surface is covered with an appropriate air-impermeable member so as to keep airtightness. The vent hole may be drilled with a drill or the like, or may be molded by molding. Considering the response to general multi-product production, the perforation is more efficient. Therefore, in the present invention, the description will be made assuming that the vent hole is perforated.

  The plurality of vent holes with different diameters and / or depths provided from the outer surface of the mold toward the inside increase the air permeability of the mold and form different partial decompression zones in the mold around the vent hole. In order to create a predetermined reduced pressure distribution in the mold cavity as the composite. In the present invention, the periphery means the outer periphery of the vent hole and the vicinity of the tip. Hereinafter, it will be simply referred to as surroundings. The partial decompression zone is a kind of partial decompression in which a plurality of vent holes are provided so that the decompression from the outer surface of the mold, that is, the entire decompression is preferentially decompressed around the vent holes. Thus, the region where the partial pressure reduction acts is referred to as a partial pressure reduction zone.

  The action of a plurality of vent holes having different diameters and / or depths will be described in detail. One of the effects is that the air permeability of the entire mold is improved by providing a plurality of ventilation holes, so that the degree of decompression of the cavity can be quickly increased. That is, speeding-up action is accelerated.

  Another effect is that a partial decompression zone is formed around each of the plurality of vent holes. Since the mold thickness between the tip of the vent hole and the cavity in the vicinity thereof is thin, the degree of decompression reflecting the decompression action of the partial decompression zone is obtained at the cavity part. As a result, a predetermined decompression distribution is created as a composite of the degree of decompression of the cavity portion corresponding to each vent hole in the entire cavity. That is, partial decompression action is obtained at a plurality of locations by a plurality of vent holes having different diameters and / or depths. Therefore, it can be said that this means is a vacuum casting method in which total decompression and partial decompression are combined.

  Thus, the diameter, depth, and location of the vents are critical to creating a predetermined reduced pressure distribution. In the first place, position is most important. That is, a large amount is provided in the vicinity of the portion where the degree of decompression is desired to be increased.

  Next, as the diameter of the vent hole is larger, a larger amount of air is sucked from the periphery thereof, so that a strong partial decompression zone is formed, and a high degree of decompression can be obtained around the vent hole.

  Further, the depth of the vent hole is as deep as possible, and the pressure reducing action of the vent hole can be strongly reflected in the cavity by drilling to a place close to the cavity. Normally, the vent hole is made not to communicate with the cavity, but the core baseboard part and the part where the hot water does not directly enter, such as the mold mating surface, may be communicated.

  Therefore, in order to obtain a desired reduced pressure distribution, it is important to provide a deep vent hole having a diameter as large as possible at an appropriate position. And in the part which wants to make pressure reduction low, a small shallow vent hole is provided or it is made not to provide at all.

  In this way, by providing a plurality of vent holes with different positions, diameters, and depths, it is possible to clearly separate the part with a high degree of decompression from the part with a low degree of decompression. An accurate decompression distribution can be created.

  The plurality of vent holes may have different diameters or different depths. Considering the workability of drilling a plurality of ventilation holes, it is desirable to keep the diameter constant and change the depth and number. Further, it is effective to provide the vent hole as close as possible to the cavity portion where the degree of decompression is desired to be increased. Usually, it is preferable from the viewpoint of the stability of pouring that a large number of ventilation holes are provided in the vicinity of the product portion cavity, and the decompression distribution is such that the degree of decompression of the cavity portion is higher than other portions.

  Further, in the method in which the hot water and the skein are provided prior to the product part as viewed from the gate side, since it is desired to increase the pressure reduction degree of the sewage and the skein part, many ventilation holes are provided deeply in the vicinity thereof. Ventilation holes may also be provided near the product part, but they are provided so that the degree of decompression is slightly lower than that of the feeder or skeiner part.

  It should be noted that, in order to drill a vent hole in an actual production line, it is necessary to be able to cope with the production of various types of castings. Therefore, a vent hole drilling device is generally configured to include one or more drilling tools such as a drill. Install on top of mold. A method of perforating the vent holes by moving the perforating tools to the optimum position as much as possible so as to obtain the appropriate reduced pressure distribution as described above is desirable. That is, the drilling device has some means that can be positioned at a desired position. Of course, when the product type is limited, the perforating apparatus may be fixed.

  Here, the reduced pressure state of the cavity in the vacuum casting method will be considered, and the difference between this means and the conventional whole vacuum casting method will be described.

  In the case of a generally used mold, the outer surface of the mold is a substantially flat surface, and the thickness of each part of the mold varies depending on the mold cavity determined by the product shape and casting method. When this mold is depressurized from the outer surface, the thin part of the mold has low ventilation resistance, so the cavity part of that part is easy to be depressurized. Conversely, the thick part of the mold has high ventilation resistance, so the cavity part of that part is depressurized. The phenomenon that it is hard to be done occurs. That is, a difference occurs in the degree of decompression at each part of the mold cavity. Moreover, the reduced pressure distribution is determined by the product shape, casting method, etc., and a reduced pressure distribution appropriate for filling the molten metal is not always obtained. An example in which an improvement measure for this phenomenon is disclosed is Patent Document 2.

  Here, if the airtightness is complete, the entire cavity quickly reaches a uniform degree of decompression, but since there is usually a certain amount of air inflow, the decompression action proceeds in a balanced manner. In addition, when the amount of inflow of air is large, the degree of decompression is not uniform, and a portion with a low degree of decompression occurs in the air inflow portion and the portion along the air flow.

In addition, it has not been clarified in the studies so far whether or not the uniform decompression degree in the cavity is really the best when pouring. For example, even if a uniform degree of pressure reduction is obtained, the degree of pressure reduction changes greatly because the airtightness breaks in the vicinity of the pouring gate with the start of pouring, and this is said to be the cause of turbulence in the hot water flow.

  In addition, a uniform degree of decompression can be obtained only in the overall decompression casting method, but on the other hand, as described in the above-mentioned prior art, partial decompression casting that does not require a uniform degree of decompression and performs decompression in one direction from the local part. The law is also actively studied. Moreover, it allows air to flow into the mold. This means that a uniform decompression across the cavity is not always optimal. Which is better depends on the type of target casting, but it can not be said unconditionally, but when casting thinner and more complex castings in the future, the reduced pressure distribution in the cavity will be controlled with high precision, and the target casting It is necessary to create a predetermined reduced pressure distribution suitable for the above.

  According to the idea of this partial decompression casting method, it is better to create a directional decompression distribution or decompression gradient even if air inflow is allowed to some extent.

  Considering this means from this point of view, in this means, by providing a plurality of vent holes having different diameters and / or depths from the outer surface of the mold to the inside as described above, the present means is provided in the mold around the vent holes. A plurality of partial decompression zones are formed, and a decompression distribution of the entire cavity is created as a composite thereof. Therefore, this reduced pressure distribution is a more accurate reduced pressure distribution created by a plurality of partial reduced pressure zones, unlike a simple one-way reduced pressure distribution disclosed in the prior art patent document, that is, a reduced pressure gradient. is there. Then, by appropriately selecting the position, diameter, and / or depth of the vent hole, it is possible to easily create a reduced pressure distribution that makes a specific part have a high degree of reduced pressure.

  The effect of this means is to provide a plurality of vent holes with different diameters and / or depths, and create a predetermined reduced pressure distribution in the mold cavity with high pressure by reducing the pressure from the outer surface of the breathable mold. It is possible to create a smooth hot water flow without turbulence. Details will be described below.

  In the conventional overall vacuum casting method, even if a uniform reduced pressure distribution is obtained before pouring as described above, the degree of decompression changes greatly with the start of pouring, and the fluctuation acts on the molten metal and the turbulence of the molten metal flow is disturbed. It is thought to occur. If the pressure reduction degree of the mold cavity changes in this way, the pressure reduction works in the direction of uniforming the pressure reduction distribution in the whole pressure reduction, so that a pressure reduction distribution appropriate for filling the cavity portion of the product part is always obtained. Is not limited.

  Even in this means, a change in the degree of decompression after the start of pouring is unavoidable. However, this means can create a reduced pressure distribution in which the desired cavity part such as the product part has a high degree of vacuum before the start of pouring, and a low degree of vacuum in the vicinity of the pouring gate part. This is clearly superior to the casting method in terms of the action of maintaining or recovering a predetermined reduced pressure distribution.

  By this means, even in the case of overall decompression, a predetermined decompression distribution can be created before pouring by forming a partial decompression zone around a plurality of vent holes having different diameters and / or depths. For example, there is a function to cope with a pressure change after the start of pouring, there is little disturbance of hot water, and there is an effect of reducing poor hot water and gas defects.

  By the way, as shown in FIG. 41, Patent Document 10 discloses a casting method in which a hole portion having a function similar to that of the present means is provided and suction suction is reduced. However, in this method, there is a restriction that a hot water supply or a skein must be provided at a position separated from the weir portion of the mold, and a hole portion must be provided in the vicinity thereof. This means does not have such a restriction at all, and can cope with any layout of the mold cavity.

Moreover, in patent document 10, it is one with respect to the product cavity of one void | hole part. However, this means is different in that a plurality of vent holes are arranged in the entire mold, and the diameter and depth thereof are changed so as to obtain a predetermined reduced pressure distribution. Further, Patent Document 10 tries to create a unidirectional decompression gradient with one vent hole, but in this means, partial decompression is performed through a plurality of vent holes having different diameters and / or depths, and the entire mold is formed as a composite. It is fundamentally different in that it creates a highly accurate decompression distribution.

  This means can easily create a predetermined reduced pressure distribution even if a plurality of molds are provided by appropriately providing ventilation holes over the entire mold. This is also a feature not found in the prior art.

  Further, when this means is expanded and expanded, it is possible to provide a reduced pressure casting method that creates a reduced pressure distribution with higher accuracy by using not only reduced pressure by suction but also partially supplying air by compressed air. This will be described in means 3.

The decompression distribution means the distribution of the degree of decompression at each location in the entire mold cavity, and the decompression gradient simply means the difference in the degree of decompression between the two locations. Therefore, the reduced pressure distribution described in the present invention represents the pressure distribution of the mold cavity with higher accuracy than the reduced pressure gradient. Note that the prior art only describes the reduced pressure gradient of the mold cavity, and there is no disclosure document describing the reduced pressure distribution.

  As described above, in the overall decompression, a vacuum casting method that creates a highly accurate decompression distribution by utilizing the partial decompression action formed by decompressing by providing a plurality of appropriate ventilation holes corresponding to the mold cavities. Provided. Details will be described in Example 4.

(Means 2 )
A plurality of ventilation holes from the outer surface to the inside of the mold are provided on at least one outer surface of the breathable mold, and the plurality of ventilation holes are individually sucked or supplied to the periphery of the plurality of ventilation holes in the mold. And forming a predetermined reduced pressure distribution in the cavity of the air-permeable mold, and pouring the molten metal.

This means provides a reduced pressure casting method in which a predetermined reduced pressure distribution is created in the mold cavity with higher accuracy than means 1 .

  In this means, a plurality of ventilation holes are provided in the same manner as in means 1, and a plurality of ventilation holes are individually suctioned or supplied to create a predetermined reduced pressure gradient and poured. It is.

  That is, in the means 1, a plurality of vent holes having different diameters and / or depths are provided and a predetermined reduced pressure distribution is obtained from the outer surface of the mold by the entire reduced pressure. By supplying air, the partial pressure reduction was performed more clearly, and a predetermined pressure reduction distribution was obtained with higher accuracy. In this means, since the pressure reduction is controlled by individually sucking or sending air to each vent hole, the diameter and depth of the plurality of vent holes may be the same or different.

  As for the use of air in addition to suction, the main means of this means is pressure reduction, so suction is mainly used. However, the degree of pressure reduction among a plurality of vent holes is desired to be lowered (to be weakened) near the cavity. Compressed air or atmospheric pressure level air is sent to the vent hole to actively lower the degree of decompression. Of course, it is not necessary to perform suction or air supply to the site where the degree of decompression is to be reduced, but the effect of the partial decompression zone around the vent hole that is performing suction also appears around other vent holes. The part also has a certain degree of decompression. As a countermeasure against this, the degree of decompression is actively lowered by supplying air to the part.

  As a result, the cavity near the vent hole performing strong suction has a high degree of decompression, and the cavity part near the vent hole delivering air has a lower (weak) decompression degree, both of these cavity parts. The pressure reduction gradient in between can be made larger. That is, the degree of decompression corresponding to the partial decompression zone around each vent hole is formed in each part of the mold cavity according to the suction or air flow rate of each vent hole, and the decompression distribution of the entire cavity is created as a composite. It is done. As a result, a predetermined reduced pressure distribution can be created with higher accuracy than the means 1, and smooth pouring can be performed in a state where there is little disturbance of the hot water flow.

  As a method of individually sucking or supplying air from the vent hole, a plurality of decompression boxes are brought into contact with the plurality of vent holes on the outer surface of the mold, and a suction port and an air supply port are provided in the decompression box. Can be communicated with the decompression device via the flow rate control means, and the air supply port can be communicated with the air compression device via the flow rate control means. Details will be described in Examples 5 and 6. In this means, since the plurality of decompression boxes which are suction / air supply devices are used in contact with the plurality of vent holes provided, some positioning means for adjusting the position of the vent holes is provided.

  By this means, a predetermined reduced pressure distribution can be created by acting more quickly on fluctuations in the reduced pressure distribution associated with the start of pouring, and hot water can be poured in a state where there is little turbulence in the hot water flow.

  As described above, a vacuum casting method having a clear partial pressure reducing action is provided by providing a plurality of ventilation holes and individually sucking or feeding air to the ventilation holes. Details will be described in Examples 5 and 6.

(Means 3)
A plurality of ventilation holes from the outer surface to the inside of the mold are provided on at least one outer surface of the breathable mold, and the whole or a part of the outer surface of the breathable mold is virtually divided into a plurality of mold segments. The plurality of mold segments are individually sucked or supplied to form partial decompression zones around the plurality of vent holes, and a predetermined decompression distribution is created in the cavities of the breathable mold to melt the molten metal. A vacuum casting method characterized by gravity pouring.

  This means is also provided with a plurality of vent holes, individually sucked or supplied to form partial decompression zones around each of the plurality of vent holes, creating a predetermined reduced pressure distribution in the cavity of the breathable mold, and the molten metal It is the same as means 2 to pour hot water. Further, the diameters and / or depths of the plurality of vent holes are not necessarily different as in the case of the means 2. The difference from the means 2 is a method of determining a position where the vent hole is provided and a method of determining a position where suction or air feeding is performed individually.

  In the means 2, the plurality of vent holes are provided at appropriate arbitrary positions where a predetermined reduced pressure distribution can be easily obtained according to the mold cavity. Further, a plurality of decompression boxes which are suction / air supply devices for individually sucking or supplying air are used in contact with the mold surface corresponding to the positions of the plurality of vent holes. Therefore, in order to support casting of a wide variety of products in an actual production line, a punching device for punching a vent hole requires some means that can be positioned at an arbitrary position. Further, the plurality of decompression boxes that are suction / air supply devices also require some means that can be positioned at arbitrary positions. In other words, the means 2 requires some positioning means for both the vent hole drilling device and the plurality of decompression boxes, and the device may be complicated, or it may take time for positioning and the response to the production tact may not be sufficient. is there.

  In this means, this point is taken into consideration as follows. First, as to how to determine the position where the vent holes are provided, the whole or part of the outer surface of the mold is virtually divided into a plurality of mold segments, and a plurality of vent holes are provided at selected positions of the plurality of mold segments. Here, virtually dividing into a plurality of mold segments is a segment delimited by dividing the outer surface of the mold into, for example, a plurality of vertical and horizontal straight lines at appropriate intervals, as shown in FIG. Is temporarily set. The selected position is an appropriate position as much as possible in order to obtain a predetermined reduced pressure distribution corresponding to the mold cavity. In this case, the punching device of the venting hole punching device can be arranged at all positions of each mold segment, and the venting hole of a desired depth can be provided by the punching device at the selected position. As a result, the perforating apparatus can be fixed. Further, since it is not necessary to position the drilling device, it is easy to cope with production tact.

  Since the position of this vent hole by this means is determined by selecting from a plurality of predetermined mold segments, it does not become an arbitrary optimum position as in the case of means 2, and therefore corresponds to the mold cavity. It is slightly inferior to the means 2 in that a predetermined reduced pressure distribution is obtained. However, this point can be brought close to the means 2 by dividing the size of the mold segment to be divided into as small a size as possible corresponding to the mold size. Further, since all the mold segments are individually sucked or supplied, it is possible to obtain a predetermined reduced pressure distribution with an accuracy equal to or higher than that of the means 2 by controlling the suction amount and the air supply amount with high accuracy. it can.

  Next, a description will be given of how to determine the position of the apparatus for individually sucking and supplying air. In this means, a plurality of decompression boxes, which are devices for individually sucking and supplying air, are arranged at all the same positions as the mold segment set when the vent hole is drilled. When sucking and supplying air, all of the plurality of decompression boxes are brought into contact with the outer surface of the mold regardless of whether or not there is a vent hole at a position corresponding to each decompression box. Of course, a plurality of decompression boxes may be connected to form an integrated apparatus, and the entire apparatus may be contacted. Alternatively, the plurality of decompression boxes may be moved up and down separately, and only the decompression box at the position where the vent hole is located may be in contact. The suction or air supply for decompression is performed not only for the segment with the vent hole but also for the segment without the vent hole, if necessary. Therefore, in addition to suction or air supply through the vent hole, a predetermined reduced pressure distribution can be obtained with higher accuracy by suctioning or air-feeding a flat mold portion having no vent hole.

  By providing a plurality of decompression boxes corresponding to the virtually divided mold segments in this way, the device for individually sucking or feeding each mold segment does not need a positioning operation to fit each vent hole, The device becomes simple. Moreover, since positioning time is not required, it is easy to cope with production tact.

The reason why the mold segment is set on the whole or a part of one outer surface of the mold is preferably that the whole can cover the entire outer surface of the mold and facilitate airtightness. However, if it is not possible to set the whole according to the position of the pouring gate or the like, the mold segment is set to a part of the mold excluding that part. In that case, a portion where the mold segment cannot be set is covered with an appropriate air-impermeable member to ensure airtightness. Alternatively, when a slight amount of air can be allowed in, the portion may be opened.

  Further, in this means, the vent holes are perforated by using a perforating device that can be positioned at the optimum position as in the means 2, while the suction / air feeding devices for individually sucking or feeding air are only a plurality of decompression boxes. Can be fixedly arranged on a plurality of mold segments as described above. In this case, regardless of where the multiple vent holes are located on the outer surface of the mold, it corresponds to one of the set multiple mold segments, and the multiple decompression boxes are arranged corresponding to the same mold segment. Therefore, the plurality of vent holes communicate with any one of the plurality of decompression boxes, and decompression by suction or air supply is possible through the vent holes.

  As described above, the outer surface of the mold is virtually divided into mold segments, a plurality of vent holes are provided corresponding to the mold segments, and a plurality of decompression boxes that are individually sucked or fed are provided. Providing corresponding to the mold segments can provide the above remarkable effects. That is, the vent hole drilling device and the individual suction or air feeding device can be fixed and do not require positioning, and are greatly simplified. Further, since no positioning operation is required, it is possible to easily cope with production tact. These effects are important in terms of practicality when applied to actual production lines where high speed is strongly required.

Further, similar actions and effects can be obtained even if suction or air supply is performed from the lower part or side part of the mold. Of course, if the pressure is reduced from a plurality of surfaces, a desired pressure reduction gradient can be obtained with higher accuracy. However, since the process and the apparatus are complicated accordingly, one surface is sufficient.

  As an example of a specific suction or air feeding method, a plurality of decompression boxes are connected to each other on the side surface and placed on the outer surface of the mold, and suction ports and air feeding ports are provided in the plurality of decompression boxes. This can be done by communicating with the decompression device via the flow rate control means and by communicating the air supply port with the air compression device via the flow rate control means.

  Further, in this means, almost the same operation and effect can be obtained even when the mold is not necessarily provided with a vent hole as a special case. The reason is that in the means 2, the vacuum box is brought into contact with only the position having the vent hole for suction or air supply, and the other part of the outer surface of the mold is surrounded by a chamber or the like that can be opened or totally sealed. This is a reduced pressure state. That is, creation of the reduced pressure distribution of the mold cavity is performed only at the position of the vent hole. On the other hand, in this means, since a plurality of decompression boxes are arranged on all the mold segments, these decompression boxes cover almost the entire outer surface of the mold, and the entire outer surface of the mold is divided to increase the height. Suction or air can be accurately delivered. Therefore, even when there is no vent hole, it is possible to create a mold cavity having a predetermined reduced pressure distribution.

  As described above, this means greatly simplifies the vent hole punching device and the multiple decompression box devices for individually sucking and feeding air, and also eliminates positioning, making it easy to handle production tacts. become. Therefore, it becomes extremely easy to apply the present invention to a continuous line capable of actual high-efficiency production. In addition, since a plurality of decompression boxes corresponding to each segment cover the whole or part of one outer surface of the mold and individually suck or feed, the creation of the decompression distribution of the mold cavity should be performed with extremely high accuracy. Can do. Details will be described in Examples 7 and 8.

(Means 4)
In a casting method in which a molten metal having a specific weight γ is gravity poured into a gas-permeable mold, the degree of vacuum at a desired cavity portion to be filled with at least the molten metal that is a part of the cavity of the gas-permeable mold is set to the desired value. A negative pressure state having a value equal to or greater than the absolute value of the molten metal static pressure γH determined by the height H from the melt inlet to the uppermost portion of the desired cavity portion, and the desired cavity portion approximately equal volume of the molten metal and the volume and gravity pouring, the gravity poured been melt is filled with the desired molten metal, from the inlet of the melt into the desired cavity portion of the cavity portion of said desired top It is a reduced pressure casting method characterized by solidifying while maintaining a height H up to the top .

  This means provides a reduced pressure casting method in which only a desired mold cavity portion is filled with molten metal.

  A normal mold cavity is generally composed of a product part, a feeder part, a runner part and a gate part. In addition, a skein part for discharging unnecessary molten metal from the product part may be provided as necessary, but here, for the sake of simplicity, the basic product part, the hot water part, the runway are provided. Suppose that it is comprised from the part and the gate part.

  The pouring is completed by filling these four cavity portions not only in the vacuum casting method but also in the general casting method without decompression. After the solidification is completed, only the necessary product parts of these four parts are separated and taken out, and finished to obtain a final product.

  In other words, the feeder part, the runner part and the sprue part excluding the product part are finally separated from the product as unnecessary parts, and again used as a return material for remelting. Of these unnecessary parts, the hot water part is necessary in the solidification process to compensate for the soundness of the product part, but the runner and sprue are necessary only for filling the cavity during pouring. It is.

  Also, in cast iron castings etc., graphite crystallizes during the solidification process and volume expansion occurs, so it compensates for part of the shrinkage of the molten metal. ing. In other words, there may be no need for a hot water.

  As described above, in any of the conventional casting methods, in order to produce a product that is originally intended, a pouring process in which molten metal is finally filled in unnecessary sprue portions, runners, and feeders. Have taken. This is extremely irrational. On the other hand, if the molten metal can be filled only in the desired cavity part such as the product part or the product part and the feeder part by some method that makes use of the characteristics of the vacuum casting method, the injection yield will be greatly improved. In addition, it is possible to greatly simplify post-processes such as unwinding and finishing.

  In view of this, the present means provides a method of filling only the desired cavity portion, for example, the product portion and the feeder portion, or only the product portion, by taking advantage of the features of the reduced pressure casting method.

  In this means, when pouring a molten metal having a specific weight γ, first, at least the desired cavity portion to be filled with the molten metal, for example, the degree of pressure reduction of the product portion and the feeder portion is determined by the flow of the molten metal to the desired cavity portion. A negative pressure state having a value equal to or greater than the absolute value of the molten metal static pressure γH determined by the height H from the inlet to the top is set.

  Then, a molten metal having a volume substantially equal to the volume of the desired cavity portion to be filled is poured. In the present invention, the substantially equal volume means a volume that is equal to or slightly larger than the volume of the desired cavity portion. This is because the volume of the desired cavity part changes depending on the adhesion of the upper and lower molds due to changes in the properties of the mold material, for example, the amount of moisture, and the extent to which the cavity expands as the molten metal fills. It means that it should be decided in consideration of what to do. It is desirable to pour a slightly larger volume of molten metal to compensate for the fluctuations.

  Then, since at least the desired cavity portion has a degree of pressure reduction that is equal to or greater than the absolute value of the molten metal static pressure γH, the molten metal can be sucked up to the top of the desired cavity portion to fill the desired cavity portion. Since the molten metal has only a volume that fills the cavity portion, the other portion of the gate and the runner portion are not filled.

  In this state, if the degree of decompression is lowered from γH, naturally the molten product in the desired cavity part and the hot metal part will flow out to the other cavity parts, and all the cavities will be partially filled at a certain height level. The purpose cannot be achieved.

However, by maintaining the degree of vacuum at γH or higher while the desired cavity portion is filled, the molten metal is fixed to the desired cavity portion from the molten metal inlet to the desired cavity portion. Solidification proceeds while maintaining the height H up to the top of the part . Then, if the reduced pressure is maintained until at least the vicinity of the boundary between the desired cavity portion and the other cavity portion, that is, the end portion on the side of the molten metal that has been filled is solidified and does not flow, the desired cavity is finally obtained. Casting can be completed with only a portion filled with the molten metal. In this means, solidification does not mean that 100% of the tissue becomes a solid phase, but means that the molten metal does not flow out even if the decompression is stopped due to the appearance of a certain ratio of the solid phase. ing.

  As a result, there is no molten metal in the unnecessary sprue part and runner part, and it is possible to obtain a cast product in which the molten metal is filled only in the product part and the hot metal part filled as necessary parts.

  In addition, since cast iron castings may not require a hot water supply depending on the conditions as described above, in this case there is no hot water supply as a matter of course, and it is set as a desired cavity part to be filled only with the product part. Can do.

  As described above, the sprue part, runner part, and in some cases the feeder part, which is considered to be indispensable for obtaining a cast product, may have a cavity part but the molten metal is not filled. Alternatively, it is possible to obtain a cast product in which only the product portion is filled with the molten metal.

  As a result, the injection yield indicating the ratio of the product weight to the total pouring weight is greatly improved. If this is estimated at a general level, it is estimated that about 50 to 60% of the casting method not using this means is 80% or more in the casting method of this means, or 90% or more in the case of only the product part. And can produce tremendous effects.

  Furthermore, since there is no unnecessary portion even in the unpacking process after the solidification and cooling are completed, it is very easy to separate and take out the product, which greatly reduces man-hours or omits the process.

In addition, although it means the degree of decompression having a value equal to or higher than γH, γ is a specific weight, so it has a unit of kgf / cm ³ , and H is a height, so the unit is cm. That is, γH means pressure in the unit of kgf / cm ² . That is, γH is a pressure corresponding to the static pressure of the molten metal from the inlet of the molten metal to the desired cavity portion to the top. If the desired cavity portion is maintained at a negative pressure higher than this, that is, the degree of decompression, the molten metal can be maintained at a height H state.

  The configuration of this means will be described in more detail. First, at least the degree of decompression of the desired cavity should be set to a value equal to or greater than the absolute value of the molten metal static pressure γH. However, it should be noted that even if this decompressed state is created before pouring, pouring starts. At the same time, since the degree of decompression changes at the gate, the influence also has some influence on the desired cavity portion, and the degree of decompression of the part also changes. Therefore, it is necessary to predict this change and to make the degree of decompression of the desired cavity portion equal to or higher than γH both during and after pouring. Actually, the desired cavity portion is filled with molten metal after pouring, so the pressure in the mold around the desired cavity portion is precisely the pressure in the mold around the desired cavity portion. means.

  Next, this means can be applied to both the total decompression and the partial decompression. First, in the case of applying to the whole decompression, the mold can be used both of the mold having the vent hole of the present invention and the normal mold not having the vent hole. In any case, as described in the means 1, it is necessary to keep at least a desired cavity portion at a degree of decompression equal to or higher than γH in consideration of a change in decompression accompanying the start of pouring. In this respect, the mold provided with the vent holes is easier to deal with because the pressure distribution in the mold cavity is created with higher accuracy. In a mold without a vent hole, it is desirable to perform additional pressure reduction control such as using partial pressure reduction in order to cope with pressure change.

  Next, partial depressurization that intensively depressurizes the desired cavity portion can be applied to this means. In that case, it is desirable to cover the other parts with a non-breathable member to increase the degree of vacuum. With respect to filling the melt only in the desired cavity portion, partial decompression is more stable than overall decompression.

  In addition, this means can be realized by creating a predetermined reduced pressure distribution in the cavity portion of each product by applying means 1 to 3 in casting with a plurality of pieces. In this case, when pouring, the total volume of a plurality of desired cavity portions is poured, but in the case of multiple pouring, the pouring from the pouring gate into the plural runners will allow the molten metal to be distributed evenly. It is necessary to devise a runner system. When the accuracy of the uniform distribution is insufficient, this means can be implemented by pouring a molten metal having a larger volume with a margin than the total volume of the desired cavity portion.

  In this means, the time to wait for solidification after the completion of pouring is a loss time in terms of process tact, so it is a factor to be reduced as much as possible. This will be described later in the means 12 to 14.

  Summarizing the above, this means can provide a very high injection yield and greatly simplify the unpacking process. Further, the feature of this means is as follows as compared with the conventional vacuum casting method. (1) The degree of decompression of the desired cavity portion was defined as an appropriate γH or higher. (2) A molten metal having a volume substantially equal to the desired cavity portion is poured. (3) After pouring, keep the vacuum until solidification. Details will be described in Example 10.

(Means 5)
In the reduced pressure casting method according to means 4, the degree of pressure reduction in the desired cavity portion to be filled with the molten metal is a negative pressure state having a value equal to or greater than the absolute value of the molten metal static pressure γH, and the pressure reduction degree in the other cavity portions. This is a vacuum casting method characterized by being high.

  This means has substantially the same structure as that of means 4, and the degree of pressure reduction in the desired cavity portion is a negative pressure state equal to or higher than the absolute value of the molten metal static pressure γH and higher than the other cavity portions.

  As described in the means 4, the change in the degree of decompression that occurs in the vicinity of the pouring gate with the start of pouring also appears as a change in the degree of decompression in the desired cavity portion. Therefore, in this means, even if a change in the degree of pressure reduction accompanying the start of pouring occurs, the degree of pressure reduction in the desired cavity portion is set in advance higher than that in the other portions so that the pressure reduction degree in the desired cavity portion can be maintained at γH or higher. It is a high one.

  This means that the degree of pressure reduction in the desired cavity is high and the pressure distribution near the pouring gate is low, so that the pressure change due to pouring is small and the recovery action is large, so that more stable pouring is possible. Is possible. Details will be described in Example 9.

(Means 6)
In a casting method in which a molten metal having a specific weight γ is gravity poured into a gas-permeable mold , a molten metal having a volume substantially equal to the volume of a desired cavity portion to be filled with the molten metal that is a part of the cavity of the gas-permeable mold. After the start of pouring, at least the degree of decompression of the desired cavity part to be filled with the molten metal in the cavity of the air-permeable mold is adjusted from the inlet of the molten metal to the desired cavity part. a negative pressure state of absolute value than the value of the melt static pressure γH determined by the height H up to the top, is filled with molten metal only at substantially said desired cavity portion of the gravity poured been melt, the desired cavity A vacuum casting method characterized in that solidification is performed while maintaining a height H from the inlet of the molten metal to the tee portion to the uppermost portion of the desired cavity portion .

  This means is similar to means 4 and 5, but in this means, a molten metal having a volume approximately equal to the volume of the desired cavity part is first poured, and then the pressure is reduced to only the molten metal part in the desired cavity part. A reduced pressure casting method is provided.

  In this means, the molten metal having a volume approximately equal to or slightly larger than the volume of the desired cavity portion is first started without reducing the pressure before starting the pouring. Thereafter, the pressure is reduced at an appropriate timing, and at least the desired cavity part is set to a negative pressure equal to or higher than the molten metal static pressure γH, thereby sucking the molten metal filled in the part other than the desired cavity part to obtain the desired cavity. The part is filled.

Then, like the means 4 and 5, the degree of decompression is maintained until the boundary portion is solidified and the molten metal does not flow. Thus, in the same manner as in the means 4 and 5 according to the present means, the desired cavity portion is maintained with the height H from the molten metal inlet to the desired cavity portion to the top of the desired cavity portion. Only the molten metal can be filled.

  This means provides an improvement measure against a pressure reduction change caused by the start of pouring caused by the pressure reduction before the pouring in means 4 and 5. That is, the feature of this means is that gravity is poured without reducing pressure before pouring, and decompression is started after the molten metal enters the cavity.

As a result, there is no significant change in the degree of pressure reduction of the mold cavity at the start of pouring, pouring gently, and then sucking in the molten metal that has been decompressed and poured into the desired cavity. Only the molten metal is filled.

  The fact that the molten metal can be filled in the cavity without undergoing a pressure change at the start of pouring means that the risk of turbulence of the molten metal that easily occurs at the beginning of pouring and entrainment of gas can be greatly reduced. ing. Therefore, the conditions that can prevent defects peculiar to the vacuum casting method are easily prepared.

  In this means, the timing for starting decompression and the rate of increase in the degree of decompression are important. Depressurization is started as soon as possible after pouring, and filling of a desired cavity portion is completed at a rate of ascending pressure as slow as possible. It is not always necessary to wait for the molten metal to stop at the timing of starting the pressure reduction. Depressurization can be started at an appropriate timing according to the product shape and cavity shape. When conditions such as mold conditions, molten metal temperature, and oxidation resistance are good, it is possible to make the molten metal stand still after pouring and then reduce the pressure to fill only the desired cavity portion.

  Filling only the desired cavity portion with the molten metal is possible with this means or means 4 and 5, but which is appropriate depends on the material of the molten metal, whether the molten metal is easily oxidized, or the degree of superheat of the molten metal. Judgment should be made based on the above. Details will be described in Example 15.

(Means 7)
In the vacuum casting method according to any one of means 4 to 6, a plurality of ventilation holes having different diameters and / or depths from the outer surface toward the inside of the mold are provided on at least one outer surface of the breathable mold, Depressurizing from the outer surface of the mold to form partial decompression zones around the plurality of vent holes in the mold, creating a predetermined decompression distribution in the cavity of the breathable mold, and pouring the molten metal This is a reduced pressure casting method.

  This means is the reduced pressure casting method according to any one of the means 4 to 6, in which the reduced pressure method using the plurality of vent holes of the means 1 is applied in filling only the desired cavity portion with the molten metal. Since a plurality of partial decompression zones are formed by a plurality of vent holes to create a highly accurate predetermined decompression distribution, it is easier to fill the melt only in a desired cavity portion. Details will be described in Examples 9, 13 and 14.

(Means 8)
7. The reduced pressure casting method according to any one of means 4 to 6, wherein a plurality of vent holes from the outer surface toward the inside of the mold are provided on at least one outer surface of the breathable mold, and the plurality of vent holes are individually provided. A partial decompression zone is formed around each of a plurality of vent holes in the mold by suction or air supply, and a predetermined decompression distribution is created in the cavity of the breathable mold to pour molten metal. This is a vacuum casting method.

  This means applies a reduced pressure method in which a plurality of vent holes of means 2 are individually sucked or supplied to fill the melt with only a desired cavity in the reduced pressure casting method according to any of means 4 to 6. Is. As a result, a highly accurate decompression distribution is created, and it is easy to fill the melt only in the desired cavity portion. Details will be described in Example 11.

(Means 9)
In the vacuum casting method according to any one of means 4 to 6, in the at least one outer surface of the gas permeable mold, a plurality of air holes extending from the outer surface to the inside of the mold are provided, and the entire outer surface of the gas permeable mold or A portion is virtually divided into a plurality of mold segments, and the plurality of mold segments are individually sucked or supplied to form partial decompression zones around the plurality of vent holes, respectively. A vacuum casting method characterized by creating a predetermined reduced pressure distribution in a cavity and pouring molten metal.

  In the vacuum casting method according to any one of the means 4 to 6, this means individually fills only a desired cavity portion with the molten metal by using a plurality of vent holes and the virtually provided mold segments of the means 3. A vacuum method that is sucked or supplied is applied. As a result, a highly accurate reduced pressure distribution can be created by a plurality of mold segments, and only a desired cavity portion can be easily filled with molten metal. Details will be described in Example 12.

(Means 10)
In the vacuum casting method according to any one of means 4 to 9, non-breathability or lower air permeability than the mold air permeability is provided in the vicinity of a boundary portion between a desired cavity portion to be filled with a molten metal and other cavity portions. The vacuum casting method is characterized in that a molten metal is poured while depressurizing a gas-permeable mold by installing a gas-permeable sealing member that has and disappears or melts by the heat of the molten metal.

  In this means, in the vacuum casting method according to any one of means 4 to 9, in order to stably increase the degree of decompression of a desired cavity portion, non-breathability or lower breathability than the mold is provided near the boundary portion, and the molten metal An air-permeable sealing member that disappears or melts by heat is installed to reduce the pressure of the mold.

  For the ventilation sealing member, for example, a non-breathable material such as a resin material or a metal material and a material that disappears or melts by the heat of the molten metal is used. Further, a material having a lower air permeability than the mold, such as cloth or paper, may be used.

  Although the position where the ventilation sealing member is arranged is in the vicinity of the boundary portion, the position may be appropriately changed to the gate side or the product side. The point is that the desired cavity portion and other cavity portions are pressure-separated at the time of decompression by the ventilation sealing member.

  Disappearing or melting means having a melting point lower than the molten metal temperature. Any material may be used as long as it does not generate harmful gas or the like, and the dissolved residue hardly remains.

  The function and effect of the ventilation sealing member of this means are to keep the pressure reduction degree of the desired cavity part before pouring quickly and stably, and to the other, the pressure change near the pouring gate when pouring starts. However, at least until the molten metal reaches the ventilation sealing member, the degree of decompression of the desired cavity portion is not affected. As a result, the degree of decompression of the desired cavity portion can be stably maintained at γH or higher. Details will be described in Example 16.

(Means 11)
In the vacuum casting method according to means 10, the vacuum sealing method is characterized in that the ventilation sealing member has a time from disappearance or melting to 2 seconds or more and 5 seconds or less after contacting the molten metal.

  In this means, a member having a time from disappearance or melting to 2 seconds or more and 5 seconds or less after the ventilation sealing member used in the means 10 comes into contact with the molten metal is used.

  This means that, as described above, when pouring is started from a reduced pressure state, the degree of depressurization changes greatly, so in order to prevent the influence, The molten metal was stopped once for 2 to 5 seconds in a filled state, and then the flow was sealed and flowed into the desired cavity portion that was gently decompressed to γH after the disappearance or melting of the vent sealing member. It is.

  As a result, even if the molten metal is poured into the mold that has been depressurized from the beginning, the effect of the reduced pressure applied to the molten metal at the beginning of pouring is restored to the static pressure state by once stopping the molten metal, and the desired cavity is gently One action is to be able to fill the part. Another action is to float and separate inclusions and gas in the molten metal by making the molten metal stationary. The reason why the time until the ventilation sealing member disappears is set to 2 seconds or more is to take time for the recovery of the static pressure state and the rise of inclusions and gas. Also, the reason for setting it to 5 seconds or less is that if the length is longer than this, the hot-rolling property deteriorates due to the temperature drop of the molten metal, and oxides are generated due to oxidation of the molten metal. Details will be described in Example 17.

(Means 12)
In the vacuum casting method according to any one of means 4 to 11, a molten metal blocking member made of a refractory material having a specific gravity smaller than that of the molten metal is provided in the vicinity of the boundary between the desired cavity portion to be filled with the molten metal and other cavity portions. It is a reduced pressure casting method characterized in that it is installed in a recess provided in the cavity lower part in the vicinity of the boundary part, and after the pouring is completed, the molten metal blocking member floats by buoyancy to block the molten metal in the vicinity of the boundary part.

  In this means, a molten metal blocking member made of a refractory material having a specific gravity smaller than that of the molten metal is installed in a recess provided in the lower part of the cavity near the boundary portion, and after the pouring is completed, the molten metal blocking member floats by buoyancy, and the boundary portion Try to block nearby molten metal.

  The molten metal blocking member is provided to shorten the decompression holding time until the vicinity of the boundary is solidified and does not flow out after the molten metal is completely filled in the desired cavity.

  That is, the molten metal blocking member is installed in the recess at the lower part of the cavity so as not to disturb the flow of the molten metal during pouring, and floats by buoyancy after the pouring is completed and blocks that portion. As a result, even when the decompression is lowered or stopped after filling the desired cavity portion with the molten metal, the molten metal static pressure of γH pushes the molten metal blocking member into close contact with the mold to prevent the molten metal from flowing out.

  Even if it is not possible to completely stop the pressure reduction immediately after the pouring is completed by the molten metal blocking member, the molten metal quickly solidifies by forming contact with the molten metal blocking member, thereby forming a skin and greatly reducing the reduced pressure holding time. .

  It is possible to increase the solidification rate by using a material having as large a heat capacity as possible for the molten metal blocking member. For example, the use of zircon sand, which has a larger specific gravity than ordinary silica sand, can increase the solidification rate by about twice.

  As described above, by installing the molten metal blocking member, it is possible to shorten the decompression holding time of the molten metal filled in a desired cavity portion. Details will be described in Example 18.

(Means 13)
In the vacuum casting method according to any one of means 4 to 9, in a recess provided in a lower part of the cavity in the vicinity of a boundary part between a desired cavity part to be filled with a molten metal and another cavity part, non-breathable or mold A mold having a sealing blocking member in which a ventilation sealing member having an air permeability lower than the air permeability and disappearing or melting by the heat of the molten metal and a molten metal blocking member made of a refractory material having a specific gravity smaller than that of the molten metal are installed. The vacuum casting method is characterized in that the molten metal is poured while the pressure is reduced.

  In this means, in the vacuum casting method of means 4 to 9, the air-sealing member in the casting method of means 10 and 11 used for efficiently increasing the degree of vacuum of the desired cavity portion, and the vacuum casting of means 12 are used. A sealing blocking member integrated with the molten metal blocking member used in the method was installed near the boundary.

  That is, for example, the upper part is used as a ventilation sealing member and the lower part is used as a molten metal blocking member in a recess near the boundary. The ventilation sealing member seals ventilation during decompression to stably increase the decompression of a desired cavity, and the molten metal blocking member acts to float after pouring and block the vicinity of the boundary.

  As described above, since both the members are integrated, it is possible to perform both the air sealing and the runoff blocking only by installing the member having two functions in the recess. This facilitates the installation of members necessary for vent sealing and runner blocking. Details will be described in Example 19.

(Means 14)
14. The vacuum casting method according to any one of means 4 to 13, wherein a vent hole and / or cooling is performed from the outer surface of the gas-permeable mold toward a boundary portion between a desired cavity portion to be filled with the molten metal and another cavity portion. A vacuum casting method characterized in that solidification in the vicinity of the boundary portion is promoted by providing a hole and sucking or feeding air from the ventilation hole and / or the cooling hole after pouring is completed.

  In this means, in order to quickly solidify the molten metal filled in a desired cavity portion for the same purpose as the means 12, a vent hole and / or a cooling hole is provided in the vicinity of the boundary portion. A vacuum casting process is provided that promotes solidification near the boundary by suction or insufflation through cooling holes.

  The ventilation holes and / or cooling holes are provided from the outer surface of the mold toward the vicinity of the boundary portion or in the vicinity of the vicinity of the boundary portion. The vent hole is used for decompression, and the cooling hole is used for cooling. The ventilation hole and the cooling hole may be provided separately or may be shared. The diameter of the vent hole and the cooling hole is as large as possible, and the depth is set as deep as possible so as not to penetrate the cavity near the boundary.

  Although cooling is performed by suction or air supply, if possible, it is possible to supply a large amount of air per unit time by supplying compressed air, so that the time until solidification can be shortened.

  Further, when used together with the molten metal blocking member of the means 12, solidification near the boundary can be completed more rapidly than the individual means.

  After the pouring is completed by this means and means 12, it becomes possible to quickly solidify the vicinity of the boundary, the decompression holding time can be shortened, and the production efficiency of the decompression casting method in which the molten metal is filled only in a desired cavity portion is improved. Can do. Details will be described in Example 20.

(Means 15)
In the vacuum casting method according to any one of means 1 to 14, an air supply hole communicating from an outer surface of the air-permeable mold to a core baseboard portion set in the mold and / or a mating surface of the mold is provided. In this method, the molten metal is poured while compressed air is supplied to the air supply hole.

  Generally, in the vacuum casting method, there is a problem that when the cavity is depressurized, the molten metal enters the gaps between the core baseboard portion and the upper and lower mold mating surfaces, and burrs are likely to occur. In particular, the baseboard part of the core is likely to occur when the baseboard clearance is large or the core set is offset. This means provides a reduced pressure casting method provided with countermeasures against burrs generated in the mold gap.

  In this means, an air supply hole is provided from the outer surface of the air-permeable mold to the core base and / or the upper and lower mold mating surfaces set in the mold, and compressed air is supplied through the air supply hole. This prevents the molten metal from entering the gap.

  The operation will be described. In the normal vacuum casting method, since all the parts of the cavity are in a reduced pressure state, the molten metal is sucked into the gap between the core baseboard part and the mold mating surface and easily enters. In contrast, the compressed air is sent to this part so that the gap does not become negative pressure, and the compressed air is blown out from the gap into the cavity to positively stop the intrusion of the molten metal as a slightly positive pressure state. It is what you want to do.

  The driving force of the molten metal that enters the gap is obtained by adding the pressure due to the static pressure of the molten metal and the degree of pressure reduction. Therefore, the intrusion of the molten metal can be prevented by supplying a positive pressure higher than this and applying an intrusion preventing force. Further, the molten metal tip is cooled by the cooling action of the compressed air, the fluidity of the molten metal is lowered, and it becomes difficult to enter the gap.

  If the pressure of the compressed air is too large, air is entrained in the molten metal in the cavity and causes casting defects. Therefore, the suction by the reduced pressure is eliminated and the pressure is set to an appropriate positive pressure that overcomes the molten metal static pressure.

  By this means, it is possible to prevent the generation of burrs in the vacuum casting method. As a result, in combination with the cast product having only the desired cavity portion obtained by the means 4 to 9, a cast product with few or no burrs can be obtained, and finishing work in the subsequent process is greatly reduced. Is. Details will be described in Example 18.

(Means 16)
16. The reduced pressure casting method according to any one of means 1 to 15, wherein when pouring a cast iron melt, a pouring temperature is set to 1300 ° C. or lower.

  The present means provides a reduced pressure casting method that ensures casting without hot metal when pouring a cast iron melt that may be able to cast a sound casting without hot metal due to graphitization expansion during solidification.

  In general, the vacuum casting method has good molten metal flow, so it should be possible to fill the mold cavity sufficiently by pouring at a lower temperature than the normal no-decompression casting method. The current situation is that pouring is performed at a certain temperature. Therefore, a significant cost reduction factor is overlooked.

  Therefore, since the stable casting flow without turbulence of the molten metal was obtained by the reduced pressure casting method of means 1 to 13, the molten metal was kept in a state where there was little risk of poor hot water and gas defects even when the pouring temperature was lowered. Since it became possible to fill the hot water, the pouring temperature was lowered. That is, in the case of cast iron casting, the pouring temperature is generally 1400 to 1450 ° C., but in the reduced pressure casting method of this means, it is set to 1300 ° C. or less.

  The effect of this low pouring temperature becomes clear by the following calculation of the shrinkage and expansion balance during solidification. In the case of a spheroidal graphite cast iron melt having a CE value of about 4.5, the liquid contracts (shown as a negative value) from the melt state at the pouring temperature to about 1150 ° C., which is the eutectic solidification point. Its value is about -1.5% per 100 ° C. That is, in the case of pouring at 1400 ° C., (1400-1150) × (−1.5) /100=−3.75%. In the pouring at 1300 ° C., (1300-1150) × (−1.5) /100=−2.25%. That is, the liquid shrinkage can be reduced by 1.5% by lowering the pouring temperature by 100 ° C.

  On the other hand, in cast iron, expansion of about 6.00% due to graphite crystallization and contraction of about 3.30% due to austenite crystallization occur with eutectic solidification.

  When all the above shrinkage and expansion are added up, it is −3.75% + 6.00% −3.30% = − 1.05% in the case of 1400 ° C. pouring. That is, the shrinkage is 1.05%. In other words, the cast product part means that the shrinkage cavity defect remains unless some molten metal is supplied. As described above, a hot water supply for compensating for the shrinkage is required at a normal pouring temperature.

Next, the case of 1300 ° C. pouring by this means will be calculated. In this case, -2.25% + 6.00% -3.30% = + 0.45%. That is, the expansion is 0.45%. In other words, the cast product does not generate shrinkage even if it does not receive any molten metal replenishment, which means that it is possible to perform casting in which a sound casting can be obtained without using a feeder.

  The above calculation of shrinkage and expansion is simply calculated based on the shrinkage and expansion of only the molten metal, and in actual casting, it does not become the above calculation due to the expansion of the mold and the shape of the cast product. However, the fact that reducing the normal pouring temperature of 1400 to 1450 ° C. to 1300 ° C. or less has the same effect as replenishing liquid shrinkage of 1.5 to 2.25% or more is the shrinkage nest It is extremely important for the production of sound castings without any problems. The lower limit of the pouring temperature depends on the material, casting shape and size, but can be up to about 1250 ° C.

As described above, by creating an appropriate reduced pressure distribution and realizing a stable hot water flow, the casting temperature can be reduced to 1300 ° C. or less from the normal 1400 to 1450 ° C., thereby producing a healthy casting without hot water. Therefore, only the product portion needs to be filled with the molten metal as the desired desired cavity portion, and the molten metal can be saved greatly. Moreover, the fact that there is no need for the hot water means that an extra product can be put in the space where the hot water was present, and a higher injection yield can be obtained. In addition, the fact that the pouring temperature can be lowered as compared with the prior art means that the melting temperature is lowered by the corresponding temperature, so that the cost can be greatly reduced in terms of the melting cost. Details will be described in Example 22.

(Means 17)
In the vacuum casting method according to any one of the means 2, 3 and 8 to 16, suction is performed through each part such as a plurality of vent holes, cooling holes and mold segments provided from the outer surface to the inside of the breathable mold after pouring. Alternatively, the reduced-pressure casting method is characterized in that solidification proceeds sequentially from a desired portion of the filled molten metal by controlling the flow rate of the gas body to be fed.

  This means provides a reduced pressure casting method in which the pressure reducing means used at the time of pouring is used as it is, and cooling is controlled after pouring.

  In a normal vacuum casting method, after the pouring is completed, the pressure reduction is stopped or the suction is simply continued. That is, the cooling control after pouring is not performed at all. This means uses the vent holes, cooling holes, and mold mold segments (hereinafter referred to as vent holes) used for decompression to positively suction or supply air to control cooling and sequentially solidify from the desired site. To be progressed.

  That is, strong suction or air supply is performed to a vent hole or the like in a portion to be quickly solidified, and solidification proceeds faster than other portions. Further, weak suction or air supply is performed on a vent hole or the like of a portion to be solidified later, or neither suction nor air supply is performed. Thereby, the solidification order of each part can be controlled.

  In this case, the strength of suction or air supply of each vent hole is determined in consideration of the position, size, and depth of the vent hole. This is another reason why the position, size, and depth were changed when drilling holes.

  The flow rate of suction or air supply from each vent hole or the like in the cooling process after pouring is different from the suction or air supply for decompression during decompression. That is, a vent hole or the like that has performed strong suction or air supply during decompression does not necessarily perform strong suction or air supply after pouring. Since the purpose of suction or air supply after pouring is to create a desired solidification sequence by cooling, strong suction or air supply is performed to the vent hole or the like of the portion to be quickly solidified.

  In addition, when the mold is drilled, a vent hole used for decompression and a vent hole and / or cooling hole used for cooling are separately drilled. The decompression vent hole is used during decompression, and the cooling vent hole and the cooling hole are used during cooling. If the cooling holes are used, decompression and cooling can be performed very efficiently.

  In suction and air supply, a large amount of air can be supplied by using compressed air that is higher in air supply, so that cooling can be performed faster than intake air.

  By this means, it becomes possible to proceed with the solidification of the desired cavity portion to be solidified quickly. For example, it is possible to reduce the shrinkage nest by preferentially solidifying the isolated thick part where the shrinkage nest is likely to remain. it can.

  Further, so-called directional solidification is also possible, in which solidification is sequentially performed from one end of the product to the feeder side or the gate side. Due to this directional solidification, the shortage of shrinkage is sequentially replenished, and it is possible to obtain a condition that the soundness of the product can be easily secured even with little or no hot water supply from the feeder.

  As a method of solidifying sequentially from such a desired site, conventionally, it is only a local cooling with a chiller (cooling gold), and sufficient directional solidification has not been obtained.

  By this means, solidification can be sequentially performed from a desired portion while being controlled with high accuracy, and the soundness of the casting is greatly improved. Moreover, the possibility that a healthy casting can be cast without a feeder can be greatly increased. This is an effect of providing a plurality of ventilation holes having different diameters and depths at arbitrary positions and performing suction or air supply from each ventilation hole. Details will be described in Example 23.

(Means 18)
In the vacuum casting method according to any one of the means 2, 3 and the means 8 to 16, the temperature of each gas body sucked and discharged from each part such as a plurality of vent holes, cooling holes and mold segments of the breathable mold after pouring Alternatively, based on the temperature and flow rate data, the cooling state of the molten metal filled in the gas permeable mold is estimated, and the suction flow rate and / or the air flow rate to each part of the gas permeable mold are controlled to control the molten metal. A vacuum casting method characterized by controlling a cooling state.

  In this means, following the means 17, a reduced-pressure casting method for performing more accurate solidification control is provided. That is, the temperature of the gas body sucked and discharged from each vent hole or the like of the mold, or the cooling state of the molten metal filled based on the temperature and flow rate data is estimated, and the suction or air supply to each vent hole or the like is based on the result. This is a reduced pressure casting method in which the flow rate of the molten metal is controlled to control the cooling state of the molten metal.

The gas bodies used for this means are both those sucked during decompression and those sucked during the cooling process after pouring. It is possible to estimate the solidification state of each part with a certain degree of accuracy only by the temperature of these gas bodies. If the flow rate data is added to this, more accurate estimation is possible.

  In a mold without vent holes or the like in the conventional vacuum casting method, since suction is performed from the entire mold, the temperature distribution or cooling state of each part of the cavity cannot be estimated even if the average temperature as a whole is known.

  In this means, by providing a plurality of ventilation holes or the like in the mold, or by dividing the outer surface of the mold into segments and performing individual suction, it is possible to obtain data on the temperature and flow rate of the gas bodies in each part. The vacuum casting method using the cooling control method was made possible. Such a vacuum casting method is completely new. As a result, in the prior art, after the pouring, the decompression was stopped or simply suctioned and the mold was cooled in an uncontrolled manner. Is made. Details will be described in Example 24.

(Means 19)
In the vacuum casting method according to any one of the means 2, 3 and means 8 to 17, each gas body sucked and discharged from each part such as a plurality of vent holes, cooling holes and mold segments of the breathable mold after pouring By estimating the cooling state of the molten metal filled in the air-permeable mold on the basis of temperature, or temperature and flow rate data, and controlling the suction flow rate and / or the air flow rate to each part of the air-permeable mold The reduced pressure casting method is characterized in that a final solidification structure of the molten metal is adjusted by controlling a cooling state of the molten metal.

  In this means, since the pressure reduction casting method in which high-precision cooling control is applied by means of the temperature or the data of the temperature and the flow rate by means 18, the solidification region and the subsequent systematic transformation region can be cooled using this method. A vacuum casting method for controlling the final solidified structure is provided.

  For example, in cast iron, the number of graphite grains and austenite crystal grains change depending on the eutectic solidification rate, and the pearlite structural change and the pearlite / ferrite content ratio change occur due to cooling control of the eutectoid transformation region.

  Conventionally, such a structure adjustment has been performed by changing the chemical composition of the molten metal, or once solidifying the casting, reheating it and holding it at a predetermined temperature, and then cooling it at a predetermined cooling rate.

  In this means, cooling control is performed by sucking or feeding the eutectic solidification region and / or the eutectoid transformation region using cast holes in the cooling process in the mold after pouring is completed, for example, in cast iron. Thus, a structure similar to that obtained by adjusting the chemical components and heat treatment is obtained.

  As a result, even if molten metal having the same chemical composition is poured, castings having different desired metal structures can be obtained by controlling the cooling rate by this means. That is, various grades of material can be produced with a small number of kinds of raw hot water components, which brings about a great effect in operation. In addition, heat treatment becomes unnecessary, and energy costs can be reduced and processes can be omitted. Details will be described in Example 25.

(Means 20)
In the vacuum casting method according to any one of means 1 to 19, after pouring, the pouring gate or the pouring gate portion is closed with a non-breathable member or a member having a lower air permeability than the mold, and the pressure is reduced until the molten metal is solidified. This is a reduced pressure casting method.

  In the vacuum casting method, it is important to keep the degree of vacuum stable from the state before pouring until the molten metal is filled after pouring. However, as described above, the pouring gate or the pouring gate portion is opened to the atmosphere along with pouring, so the degree of decompression at that portion is greatly reduced, and the degree of decompression of the mold cavity is also susceptible to change.

  The present means provides a casting method to which the improved method is added. That is, after pouring, the pouring gate or the pouring gate portion is closed with a non-breathable member or a member having lower air permeability than the mold, and the pressure is reduced until the molten metal is solidified. As a result, the mold cavity is again in the same sealed state as before the pouring, and as a result, the degree of decompression can be kept stable. In addition, the capacity of the decompression device can be reduced.

  In particular, in the reduced pressure casting method according to any one of means 4 to 14 in which only a desired cavity is filled with molten metal, it is necessary to maintain the degree of vacuum of the desired cavity at or above γH even after pouring. It is valid. Details will be described in Example 26.

(Means 21)
In the vacuum casting method according to any one of means 1 to 20, the heat of the molten metal is recovered by heat-exchanging the gas body sucked and discharged from the air-permeable mold with a heat exchanger and / or preheating the molten material. This is a casting system.

  This means provides a casting system that recovers and uses the heat of the gas body sucked and discharged through the cooling process from the pouring.

  In this means, the gas body sucked and discharged from the mold is led to a heat exchanger to be recovered by exchanging heat with another fluid and / or recovered by directly using the gas body for preheating the dissolved raw material. Like that.

  Conventionally, in both cases of a general no-pressure reduction casting method and a pressure reduction casting method, most of the heat of the poured molten metal is applied to the mold material. For this reason, the mold material becomes high temperature, and in order to reuse it, a process of cooling with water or air is required. Also, high temperature castings need to be cooled. That is, the heat given to the molten metal in the melting process is not recovered at all and is finally dissipated in the air. In other words, the heat recovery rate of the molten metal is almost zero in any current casting method.

  In the vacuum casting method of the present invention, the suction and discharge of the gas body is continued in order to control the cooling even after the pouring is completed, so that a considerable part of the heat of the molten metal is discharged as the heat of the gas body. Thus, this heat can be utilized through a heat exchanger and / or directly to preheat the melted raw material so that a portion of the heat previously dissipated in the air can be recovered.

As described above, this means can make the entire foundry factory into an energy-efficient production form, and has a great effect both in terms of production cost and CO ₂ reduction, which has become a problem in recent years. It is what brings. Details will be described in Example 27.

(Means 22)
A device for reducing pressure by placing on the outer surface of a mold and attaching a plurality of decompression boxes having open ends to be brought into contact with the outer surface of the mold to a means for vertically moving with respect to the outer surface of the mold. A gas flowing through the suction port or the suction port and the air supply port is provided in each of the plurality of decompression boxes, or a suction port communicating with the decompression device or an air supply port communicating with the air compression device. A reduced-pressure casting apparatus comprising flow control means for individually controlling a flow rate of a body, and creating a predetermined reduced pressure distribution by the flow control means.

  This means provides a vacuum casting apparatus from the outer surface of the mold used in means 1 to 20.

  First, the configuration of this apparatus will be described. This apparatus communicates with a plurality of decompression boxes having an open end abutting on the outer surface of the mold, means for raising and lowering them, a suction port communicating with the decompression apparatus provided in each of the plurality of decompression boxes and / or an air compression apparatus. And a flow rate control means for individually controlling the flow rate of the gas body flowing through the suction port and the air supply port.

  Next, aspects of the constituent elements will be described. The plurality of decompression boxes are attached to lifting means that opens at one end and moves up and down in a direction perpendicular to the mold. A plurality of decompression boxes are placed on the outer surface of the mold by lifting means, and their open ends are used in contact with the outer surface of the mold. At this time, the presence or absence of a vent hole on the outer surface of the mold is not a problem, but it is desirable to have a vent hole in order to easily obtain a preferable reduced pressure distribution.

  The plurality of decompression boxes may be separated from each other or connected to each other. When separated, it is applied to the vacuum casting method described in the means 1 and 2, and when connected, it is applied to the vacuum casting method described in the means 3.

  Each of the decompression boxes is provided with a suction port communicating with the decompression device and / or an air supply port communicating with the air compression device. And the flow control means which controls individually the flow volume of the gas body which flows through the suction port and the air supply port is provided.

  Next, the operation of this apparatus will be described. This device is a device that mainly performs pressure reduction from before pouring to completion of pouring by suction, and is a device that performs cooling control of the molten metal filled by suction and / or air supply after pouring is completed.

  First, when depressurizing, a plurality of depressurization boxes are placed on the outer surface of the mold by the lifting and lowering means, and their open ends are brought into contact with the outer surface of the mold. Then, the mold is depressurized by performing suction and / or air supply from the suction port and / or the air supply port of the desired decompression box. Since the purpose of this step is to reduce the pressure, suction is mainly used. The air supply is performed by suction mainly to the extent that it is performed on the portion where the pressure reduction is desired to obtain a more preferable decompression distribution.

  After the pouring is completed, it can be placed on the mold as it is and contacted to be used for cooling control. That is, a desired coagulation sequence can be obtained by increasing the suction and / or air supply at a site to be quickly coagulated and weakening the other sites or without suction / air supply. This enables so-called directional solidification.

  In addition, after the solidification is completed, suction and / or air supply can be performed to adjust the metal structure to a temperature that passes through at least the metallographic transformation region. That is, the cooling is advanced at an appropriate cooling rate by controlling the flow rate of the suction air supply particularly in the temperature region where the transformation of the metal structure occurs. For example, in the case of cast iron casting, it is important to control the cooling in the range of 830 to 700 ° C. in which eutectoid transformation occurs, and this makes it possible to adjust the structure of pearlite and ferrite.

  In the cooling control after the pouring is completed, the cooling effect can be increased by the air supply rather than the suction. This is because compressed air can easily supply a large amount of air into the mold at a high pressure. Therefore, a desired cooling pattern can be easily obtained by mainly using air supply in the cooling process and using suction as an auxiliary tool.

  The flow rates flowing through the suction port and the air supply port are controlled by flow rate control devices provided respectively. At this time, the control method can be simply performed according to the suction / air supply amount of each decompression box determined in advance. Further, when it is desired to control with higher accuracy, the cooling control method described in the means 18 can also be controlled based on the temperature of the gas body from each decompression box or the value of the temperature and the flow rate.

  The gas body sucked and discharged by this apparatus is used in a casting system that effectively uses the heat of the molten metal described in the means 21.

  As described above, this apparatus is an apparatus that can perform suction and / or air supply from a selected part of the mold, creates a predetermined reduced pressure distribution in the cavity during pouring, and in the cooling process. A desired cooling pattern can be obtained. As a result, the conventional vacuum casting method was a casting method in which the molten metal was simply decompressed and poured, but by using this device and each of the above means, the casting method that can control the pressure reduction and cooling is greatly revolutionized. Can do it. Details will be described in Example 28.

(Means 23)
The reduced pressure casting apparatus according to means 22 is characterized in that the positions of the plurality of reduced pressure boxes can be freely changed in a plane parallel to the outer surface of the mold.

  In this means, the positions of the plurality of decompression boxes of the suction / air supply device of means 21 can be freely changed in a plane parallel to the outer surface of the mold. That is, a plurality of decompression boxes can be freely moved in three directions XYZ with respect to the outer surface of the mold.

  In the device of means 21, the plurality of decompression boxes can be moved up and down only in the vertical direction with respect to the outer surface of the mold, and the flexibility in the plane parallel to the outer surface of the mold is not defined. That is, it was applied when the vent hole was provided at a fixed position on the outer surface of the mold.

By this means, the plurality of decompression boxes can come into contact with an arbitrary position on the outer surface of the mold, so that the vent hole provided on the outer surface of the mold can be provided at an arbitrary position.

  By this means, the degree of freedom of the position where the vent hole on the outer surface of the mold is provided is increased, and it is convenient to obtain a desired reduced pressure gradient. However, in terms of the device, it is more complicated than the device of the means 22, and when mounting a plurality of decompression boxes on the outer surface of the mold, it is necessary to match a plurality of vent holes provided at arbitrary positions. It should be used in consideration of the disadvantage of requiring a long operating time.

  In that respect, the suction / air supply apparatus described in the means 21 is simple because it is provided with a plurality of decompression boxes at fixed positions and is used in contact with the vent holes provided at the corresponding positions. Which should be better should be determined by conditions such as the size, shape, material and quantity of the castings to be produced. Details will be described in Example 26.

  The following effects were obtained by the present invention.

  A vacuum casting method has been provided in which a continuous line that can be easily produced with high efficiency using a normal air-permeable mold can be constructed. As a result, the vacuum casting method can be used for general purposes, and it is possible to improve the accuracy of the entire casting production.

By means 1 to 3 and means 7 to 9, ( 1 ) a reduced pressure casting method that can easily cope with individual products and accommodate a plurality of products and can be applied to a highly efficient continuous line is provided.

  By means 1 to 3, (2) a reduced pressure casting method in which a highly accurate predetermined reduced pressure distribution was created in the mold cavity was provided. As a result, a high-precision decompression casting method was established, making it easier to cast thin-walled products and complex products. In addition, it has become possible to easily accommodate multiple items.

By means of changing means 4 to 14 and means 20, (3) a reduced pressure casting method in which only a desired cavity among the mold cavities is filled with molten metal was provided. As a result, a vacuum casting method with an extremely high yield was established, and the post-process after the unraveling was greatly simplified.

By means of changing means 16 to 19 and means 21, (4) a high-efficiency and high-accuracy vacuum casting method was provided by controlling the process from pouring to solidification, cooling, and demolition. As a result, the thermal energy of the molten metal was fully recovered, greatly contributing to the reduction of casting costs. In addition, a significant improvement in the environment was achieved.

  Further, the means 15 and 16 provided (5) a vacuum casting method capable of preventing burrs and a vacuum casting method for pouring at low temperature. As a result, a vacuum casting method that does not generate burrs or does not require a feeder is established.

  Moreover, the means 22 and 23 provided the apparatus used for the (6) reduced pressure casting method of this invention. As a result, the reduced pressure casting method of the present invention can be easily implemented.

  As a result, the vacuum casting method, which has been applied only to special materials, thin-walled products, and complex products as a special casting method, can be easily applied to general products. In addition, the conventional vacuum casting method is a casting method in which the molten metal is simply decompressed and poured, but by using the present invention, the casting method is greatly reduced to a casting method in which the molten metal can be decompressed and poured, and solidification and cooling can be controlled. I was able to innovate.

  Further, according to the present invention, casting can be widely used as a manufacturing method superior in cost and quality as compared with other methods. In addition, the castability, which has been a concern for the past, has been overcome, and consistent control from pouring to cooling to open frame has made it possible to produce highly efficient and high quality castings.

In the best mode for carrying out the invention, a breathable mold formed on a casting frame provided with an air seal member on the upper surface and / or the lower surface of the casting frame as described in the means 1 is placed on a surface plate, and the means 4 is described. The whole or part of at least one outer surface of the breathable mold is virtually divided into a plurality of segments, and the diameter is directed from the outer surface of the mold to the inside at a selected position of the plurality of segments. And / or a plurality of vent holes having different depths, and a plurality of partial pressure-reducing zones around the plurality of vent holes by individually suctioning or feeding the plurality of segments by the suction / air supply device according to the means 23 And a predetermined reduced pressure distribution is created in the cavity of the air-permeable mold, and the molten metal is poured into only the desired cavity at a low temperature as described in the means 17 and as described in the means 5 to 10. And then, means 18 20 directional solidification, as described, cooling control, solidification structure adjustment, and a vacuum casting method in which recovering a melt of heat.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

  Example 1 is shown in FIG. In this embodiment, a vacuum casting method using a vacuum hood as an air seal member and an airtight member will be described.

  The best mode for carrying out the invention is to place a breathable mold formed on a casting frame provided with an air seal member on the upper surface and / or lower surface of the casting frame on a surface plate, and The whole or part of at least one outer surface of the breathable mold is virtually divided into a plurality of segments, and the diameter and / or depth from the outer surface of the mold to the inside is selected at a selected position of the plurality of segments. A plurality of vent holes of different thicknesses, and a plurality of partial vacuum zones are formed around the plurality of vent holes by individually suctioning or feeding air to the plurality of segments by the vacuum casting apparatus according to means 22; A predetermined reduced pressure distribution is created in the cavity of the breathable mold, and the molten metal is poured into only the desired cavity at a low temperature as described in the means 16 and as described in the means 4 to 9, and then the means Fingers as described in 17-19 Sex solidification, cooling control, solidification structure adjustment, and a vacuum casting method in which recovering a melt of heat.

  The cavity 11 of the mold 4 includes a product part 12, a feeder part 13, a runner part 14, and a gate part 15.

  A decompression hood 16 is placed as an airtight member made of a non-breathable material on the upper surface of the upper frame 2 of the mold 4 that has been matched. The decompression hood 16 is provided with a suction hole 17 at one location, and a suction pipe 18 communicated with the decompression device 69 is inserted therein by an elevating means 19 to perform decompression. It is desirable to provide an appropriate filter (not shown) in the middle of the suction pipe in order to prevent the mold sand from being sucked.

  In addition, a heat resistant packing 20 is attached to maintain airtightness between the suction hole 17 and the suction pipe 18. A portion corresponding to the pouring port 21 of the decompression hood 16 is also opened, and is covered with a foamed resin 22 to maintain airtightness.

  Next, the operation and effect of this configuration will be described. First, regarding the airtightness of the entire mold, the airtight surface 9 maintains the contact surface between the surface plate 10 and the lower frame 3. The mating surfaces of the upper and lower molds 5 and 6 are kept airtight by the air seal member 8. Further, the contact surface between the upper frame 2 and the decompression hood 16 is also kept airtight by the air seal member 7.

  The space between the suction hole 17 and the suction pipe 18 is kept airtight by the packing 20. In addition, the pouring port 21, which is another open portion of the decompression hood 16, is closed with a foamed resin 22 to maintain airtightness.

  Therefore, the entire mold is composed of the upper and lower casting frames 2 and 3, the surface plate 10, the decompression hood 16 and the air seal members 7, 8 and 9 on the contact surface thereof, and the packing 20 and the pouring port 21 on the contact surface between the suction hole 17 and the suction pipe 18. Airtightness is maintained by the foamed resin 22. That is, those components having the same hermetic function as the hermetic container used in the conventional general vacuum casting method are obtained. The packing 20 and the foamed resin 22 are general sealing members, and are not indispensable components of the present invention.

Therefore, if the pressure is reduced through the suction hole 17 in this state, the cavity 11 in the mold can have a predetermined pressure reduction. When the molten metal 23 is poured from the pouring port 21 in the reduced pressure state, the foamed resin 22 disappears, and the molten metal 23 sequentially fills the cavity 11 from the pouring portion 15.

  In the present embodiment, the suction tube 18 and the decompression hood 16 are separated, but the suction tube 18 and the decompression hood 16 may be moved up and down as an integrated structure.

  As described above, air seal members are provided on the upper and lower surfaces of a normal casting frame, a decompression hood is placed on the upper frame, and pressure is reduced through the suction hole to pour hot water so that no special airtight container is used. It became possible to perform the whole vacuum casting method.

  In this example, an air-tight container is constructed by combining an air seal member and a pressure reducing hood with a normal casting frame that is most commonly used for high-efficiency continuous lines for mass production. It has the characteristic that it can be applied to the line. Of course, it can be applied to a new line. That is, according to the vacuum casting method of the present embodiment, since a dedicated airtight container has been conventionally used, the vacuum casting method applied to special materials, thin-walled products, complex products, etc. as a special casting method is a general casting. It can be easily applied to continuous lines that can produce products with high efficiency.

  Example 2 is shown in FIG. In this embodiment, a description will be given of a vacuum casting method using a weight having almost the same configuration as that of the first embodiment and used as an airtight member for preventing the mold from rising.

  In general, the weight 24 is placed on the upper mold 5 or the upper frame 2 in order to prevent the upper mold 5 and the upper frame 2 from floating due to the expansion of the mold after pouring. In this embodiment, the weight 24 is placed on the upper frame 2 as an airtight member. The weight 24 is provided with a suction hole 17 and a pouring port 21, and the airtight method for this portion is the same as in the first embodiment.

  Only the weight 24 is used instead of the decompression hood 16 in the first embodiment, and the airtightness of the entire mold is exactly the same. In this configuration, if the pressure is reduced from the suction hole 17 and poured, the same reduced pressure casting method as in the first embodiment can be performed.

  In this example, the vacuum casting method could be easily performed by using a weight generally used in casting as an airtight member. The function and effect are the same as in the first embodiment.

  Example 3 is shown in FIG. In the present embodiment, a description will be given of a vacuum casting method in which rubbing vinyl is used as an airtight member with substantially the same configuration as in the first and second embodiments.

  In the present embodiment, the mold 4 is hermetically sealed by covering the upper mold 5 with a thin flexible vinyl 25 as an airtight member. The suction pipe 18 is brought into contact with the outer surface of the upper mold 5 through the suction hole 17 of the vinyl 25.

When the pressure is reduced from this state, the vinyl 25 is adsorbed by the upper mold 5 and the entire mold is kept airtight. Then, after a predetermined reduced pressure is obtained, pouring is performed. Also according to this example, the vacuum casting method could be easily performed.

In this embodiment, unlike the first embodiment and the second embodiment, a decompression hood and a weight are not used, so that components for decompression are simplified. However, since vinyl is used as a consumable material, it is inferior to the first and second embodiments in terms of economy.

  In addition, the vacuum casting method using vinyl is disclosed as a vacuum casting method of vanishing model in Patent Document 6 and others, but in that case, the vanishing model is accommodated in a decompression container opened on one side, and vinyl is placed in the opening. The pressure is reduced from the inside of the covering mold or the side wall of the casting frame. The present embodiment is different in that a vacuum container for containing a mold is not used at all and suction and pressure reduction is performed from the outside of the mold through the suction hole 17 of the vinyl 25.

  As described above, also in this example, the vacuum casting method of the present invention could be performed by using vinyl as an airtight member. By using an air seal member and an airtight member in each of Example 1, Example 2, and Example 3, a reduced pressure casting method applicable to a continuous line capable of high-efficiency production was provided.

  Thus, the fact that the vacuum casting method can be easily applied to a continuous line capable of high-efficiency production according to Examples 1 to 3 is based on this, in combination with the examples described later. The vacuum casting method of the present invention is widely applied to general products, including technologies such as a casting method in which a reduced pressure distribution is created, a casting method in which only a desired cavity portion is filled with molten metal, and a casting method in which cooling control is performed. The significance is great because it can.

  Example 4 is shown in FIG. In the present embodiment, means 1 is used to provide a plurality of vent holes having different diameters and / or depths from the outer surface of the mold to the inside, and create a predetermined reduced pressure distribution by sucking and reducing pressure from the outer surface of the mold. A vacuum casting method for pouring molten metal will be described.

  First, four vent holes 27 were provided in the upper part of the product part 12 of the cavity 11, the feeder part 13, and the runner part 14 toward the inside from the outer surface 26 of the mold. The diameter and depth of each vent hole are large or deep so that the product part 12 and the hot water supply part 13 have a high degree of decompression. In addition, the two vent holes at the top of the runner 14 are shallow so that the degree of decompression on the side of the gate 15 is low.

  Next, with the same configuration as in Example 1, the decompression hood 16 was placed on the upper surface of the upper frame 2, and the decompression was performed by the suction tube 18 through the suction hole 17 provided in the decompression hood 16.

  The operation and effect of this configuration will be described. When a predetermined pressure reduction is performed by the pressure reducing device 69, the pressure reduction works from the outer surface 26 of the mold through the mold particles to the inside, and the cavity 11 has a predetermined pressure reduction degree. Therefore, the cavity portion under the portion where the mold thickness between the mold outer surface 26 and the cavity 11 is thick has a high resistance to air flow of the mold particles, so that the pressure reducing action is difficult to reach, and the cavity portion where the mold thickness is thin is Since the ventilation resistance is small, the pressure reducing action is easy to reach. That is, a difference occurs in the degree of decompression of each part of the cavity due to a difference in mold thickness of each part of the mold.

  Of course, if the entire mold is kept completely airtight, the entire cavity has a uniform degree of decompression after a certain time. However, if complete airtightness is to be achieved, the air seal of each part requires a large amount of money, and therefore pressure reduction is generally performed with a certain degree of airtightness. That is, vacuum casting is performed while allowing a certain amount of air to flow into the mold.

  Therefore, in the actual reduced pressure casting, a certain amount of air inflow and suction by the reduced pressure are balanced to reduce the pressure. If it does so, a difference will arise in the pressure reduction of each cavity part by the difference in the mold thickness of each site | part mentioned above.

  In this embodiment, by utilizing this principle, a large and deep vent hole is provided toward the cavity portion where the degree of decompression is to be increased, and the mold thickness at that portion is locally reduced but the ventilation resistance is lowered. The degree of vacuum was increased.

  That is, the reduced pressure in this embodiment is basically the entire reduced pressure, but by reducing the pressure through the plurality of ventilation holes 27, the surroundings of each ventilation hole 27 are selectively reduced to the same state as the partial reduced pressure. Yes. That is, the decompression method of this embodiment can be regarded as a combination of total decompression and partial decompression.

  More specifically, a partial decompression zone is formed around each vent hole 27 by a partial decompression action, and a decompression distribution of the entire cavity 11 is created as a composite thereof. Therefore, a predetermined reduced pressure distribution can be created in the cavity 11 by changing the size, depth and position of each vent hole 27. Based on this idea, the vent holes 27 provided in the present embodiment are provided so that the product part 12 and the hot water supply part 13 have a high pressure reduction degree and the pressure reduction degree on the side of the gate part 15 is low.

  Next, after performing predetermined pressure reduction, pouring is started. What should be noted here is that the airtightness of the mold depressurized along with pouring is broken in the vicinity of the spout 15 and the degree of depressurization in the mold changes greatly. As a result, the reduced pressure distribution of the cavity 11 changes. This is one of the problems of overall decompression.

However, in the present embodiment, the pressure reduction degree is low on the side of the gate portion 15 from the beginning and a high pressure distribution is created in the product portion 12 and the hot water portion 13 due to the plurality of vent holes 27. Is small. In addition, since a plurality of vent holes 27 are provided so that a reduced pressure distribution is created from the beginning toward the product portion 12 from the gate portion 15 side, the reduced pressure generated in the vicinity of the gate portion 15 is provided. The change acts to restore the original reduced pressure distribution even if the change is quickly eliminated.

  As a result, the cavity 11 is maintained in a state close to the initial reduced pressure distribution, and the poured molten metal is less affected by a large change in reduced pressure. Therefore, the flow of the molten metal is less disturbed, and the product portion can be smoothly filled by being sucked and induced by the created reduced pressure distribution.

  Here, what kind of pouring situation will be described in the conventional general reduced pressure casting method using a normal mold in which a plurality of vent holes 27 are not provided. In this case, the object is to pour hot water in a state where the whole has a substantially uniform reduced pressure distribution. However, since the reduced pressure distribution changes greatly in the vicinity of the gate 15 as described above with the start of pouring, the initial purpose cannot be achieved by this alone. In addition, since the degree of decompression is uniform throughout the cavity 11, the degree of decompression near the gate 15 is higher than in the case of the present embodiment, so the change in decompression is large. Therefore, the molten metal is affected by a large change in pressure reduction, and the flow is likely to be disturbed.

Furthermore, the reduced pressure distribution generated again in the pouring process is almost uniform because the reduced pressure acts in the direction of uniformization in the conventional overall reduced pressure casting method against the generated reduced pressure change. That is, the distribution of pressure reduction is not such that the molten metal is smoothly sucked into the product part. The filling of the molten metal is only performed while being pushed by the atmospheric pressure and the static pressure of the molten metal (partly converted into dynamic pressure).

  In this state, the pressure in the cavity is merely low, and there is no effect of smoothly sucking and guiding the molten metal to the target product part. In addition, since the pouring proceeds while a large change in pressure reduction remains, there may be a case where the molten metal cannot be completely filled when casting a thin product having a complicated shape.

  The present embodiment is also effective in the so-called multiple-fill casting where a plurality of products can be placed in one frame. That is, it is possible to easily create a predetermined reduced pressure distribution by providing a deep and large ventilation hole in the vicinity of each product part or the product part and the cavity part of the hot water supply part where the degree of decompression is to be increased.

On the other hand, some of the above-mentioned patent documents disclose various casting methods for creating a decompression gradient using partial decompression, but they all create a simple one-way decompression gradient by decompressing from one end. It is a living thing. In addition, regarding the number of products to be targeted, most of them are intended for one product. Even if multiple packing is possible, it is necessary to provide some auxiliary member for partial decompression at the required site, which requires a lot of man-hours and cost, and lacks practicality for casting with multiple packing. .

In this embodiment, the decompression hood is placed on the upper part of the mold. However, the decompression hood can be provided on the lower part of the mold and decompressed. In this case, an airtight member is placed on the upper part of the mold so as to keep the airtightness. Further, depending on the type of the mold, the operation and effect are the same even if the pressure is reduced by contacting the side surface of the mold.

  In addition, although the present Example showed the example implemented with the structure of the same cast frame and mold as Example 1, the cast frame and mold of this invention are not limited to this. That is, a vacuum casting method similar to that of the present embodiment can be performed by providing a plurality of ventilation holes in a frameless mold and a mold formed in a casting chamber having an open top. Moreover, although the decompression method using a decompression hood was shown in the present Example, it is not limited to this, The effect | action and effect will be the same if it is the method of decompressing from the outer surface of a casting_mold | template.

  As described above, in this embodiment, a plurality of vent holes having different diameters and / or depths are provided and decompressed to form partial decompression zones around the plurality of vent holes, respectively, and as a composite thereof, in the cavity In addition, a predetermined pressure distribution was created and smooth pouring with less turbulence of the molten metal became possible.

  In this embodiment, a highly accurate reduced pressure casting method that can be said to be a kind of a combined reduced pressure method that combines a total reduced pressure and a partial reduced pressure by providing a plurality of vent holes with different diameters and / or depths from the outer surface of the mold to reduce the pressure. Provided.

  FIG. 5 shows a fifth embodiment. In the present embodiment, a vacuum casting method will be described in which the means 2 is used to perform suction by individually sucking a plurality of vent holes.

  First, the structures of the casting frame and the mold are the same as those in the fourth embodiment. A plurality of vent holes 27 are also provided from the outer surface 26 of the mold.

  In order to suck and depressurize individually from the plurality of vent holes 27, a plurality of decompression boxes 28 having open ends in contact with the mold were placed in contact with the vent holes 27 by the lifting means 19. The plurality of decompression boxes 28 communicate with the decompression device 69 via the suction flow rate control means 29. Further, in order to keep the outer surface 26 of the mold airtight, an airtight hood 30 is connected to the outside of the decompression box 28, and the airtight hood 30 is placed on the upper frame 2.

The operation and effect of this configuration will be described. The plurality of vent holes 27 provided on the outer surface 26 of the mold are provided so that the product part 12 has a high degree of reduced pressure and the gate part 15 side has a low degree of reduced pressure as in the fourth embodiment. In the fourth embodiment, the entire pressure reduction hood 16 that covers the entire upper surface of the mold is used to reduce the overall pressure. However, in this embodiment, the suction flow rate is individually controlled through the plurality of pressure reduction boxes 28 to reduce the pressure. .

  That is, by increasing the suction flow rate of the decompression box corresponding to the vent hole at the site where the decompression is to be increased, the partial decompression zone formed around the vent hole can be strengthened. Conversely, by reducing the suction flow rate of the decompression box corresponding to the site where the degree of decompression is desired to be reduced (weakened), the partial decompression zone formed around the vent hole can be weakened. That is, the strength of the partial decompression zones around each vent hole 27 can be controlled by individually controlling the suction flow rate of each decompression box 28.

  That is, in this embodiment, a plurality of individually controlled partial pressure reductions are performed. That is, in this embodiment, in addition to the kind of partial pressure reduction action obtained by changing the diameter and depth of each vent hole 27 described in the fourth embodiment, the suction flow rate is individually controlled from each vent hole 27 to reduce the pressure. In this way, a clearer partial pressure reduction can be performed. As a result, the present embodiment was a more accurate reduced pressure casting method having two kinds of partial pressure reducing actions, that is, a plurality of vent holes 27 provided in the mold and a plurality of pressure reducing boxes 28.

  As a result of the above, this embodiment can create a predetermined reduced pressure distribution in the cavity 11 with higher accuracy, and more quickly with respect to a reduced pressure change during pouring by the principle described in the fourth embodiment. This has made it possible to achieve smoother pouring of water.

  The same action and effect can be obtained by a method of controlling the suction flow rates of the plurality of decompression boxes 28 by setting the diameter and depth of each vent hole 27 to be the same. In this case, there is an advantage that the punching device for the vent hole 27 can be simplified.

  The airtight hood 30 is provided to maintain the airtightness of the entire mold. However, when the number of the decompression boxes 28 can be increased to cover one mold outer surface 26, a certain amount of air flows into the mold. If it can be tolerated, substantially the same operation and effect can be obtained even if the airtight hood 30 is decompressed without being installed.

  As described above, a reduced pressure casting method has been provided in which a plurality of reduced pressure boxes with individually controlled suction flow rates are combined to create a highly accurate predetermined reduced pressure distribution.

  A sixth embodiment is shown in FIG. In this embodiment, a reduced pressure casting method in which the pressure is reduced by suction or air supply to a plurality of ventilation holes using the means 2 will be described.

  In this embodiment, the structure of the casting frame and the mold is the same as that of the fifth embodiment. A plurality of vent holes 27 are also provided from the outer surface 26 of the mold.

  In order to suck or supply air individually from the plurality of vent holes 27, a plurality of decompression boxes 28 having open ends in contact with the mold were placed in contact with the vent holes 27 by the lifting means 19. In this embodiment, the plurality of decompression boxes 28 are each provided with a suction port 31 and an air supply port 32. Each suction port 31 communicates with the decompression device 69 via the suction flow rate control means 29, and each air supply port 32 communicates with the air compression device 70 via the air supply flow rate control means 33.

Further, in order to keep the outer surface 26 of the mold airtight, an airtight hood 30 is provided connected to the outside of the plurality of decompression boxes 28, and the airtight hood 30 is placed on the upper frame 2.

The operation and effect of this configuration will be described. The action of the plurality of vent holes 27 provided on the outer surface 26 of the mold is exactly the same as that of the fifth embodiment. In this embodiment, in addition to the pressure reduction by only suction performed in the fifth embodiment, air can be supplied from each pressure reduction box 28.

The purpose of supplying air in addition to suction is to obtain a desired reduced pressure distribution with higher accuracy. That is, the degree of decompression can be positively lowered by supplying a small amount of compressed air from the decompression box 28 communicating with the vent hole at the site where the degree of decompression is desired to be lowered.

This is because the partial decompression zone in the surrounding area due to suction from one vent hole extends to each part of the mold, so that the part where the decompression is to be reduced is also decompressed. Therefore, a small amount of compressed air is supplied so that the degree of decompression at that portion can be actively reduced. In addition, when supplying air, if the flow rate is too high, air will be involved in the molten metal and cause gas defects, so an appropriate flow rate is set.

  In this embodiment, the three vent holes provided in the upper part of the product section 12 and the hot water feeder section 13 are sucked to increase the degree of decompression, and the vent hole close to the spout section 15 is fed to lower the decompression degree. It was. The state of suction and air supply is indicated by the direction and size of the arrow in the decompression box 28. As a result, the reduced pressure distribution of the mold cavity 11 can be created with higher accuracy.

  As described above, since suction and air supply can be performed individually for a plurality of vent holes, a predetermined reduced pressure distribution can be created with higher accuracy than in the fifth embodiment, and pouring can be performed. A vacuum casting method was provided.

  FIG. 7 shows a seventh embodiment. In this embodiment, the means 3 is used to provide a plurality of vent holes, virtually divide one of the outer surfaces of the mold into a plurality of mold segments, and individually suck or feed the plurality of mold segments. A vacuum casting method that performs partial pressure reduction and gravity pouring will be described.

  In this embodiment, the structure of the casting frame and the mold is the same as that of the sixth embodiment. A plurality of vent holes 27 are provided in the outer mold surface 26. The plurality of vent holes 27 virtually divide the mold outer surface 26 into mold segments and are provided at selected positions therein.

  Also in this embodiment, a plurality of decompression boxes 28 having open ends in contact with the mold are used. However, the plurality of decompression boxes 28 are connected at the side surfaces so as to cover almost one mold outer surface 26 as a whole. . That is, one mold outer surface 26 is virtually divided into mold segments of a predetermined size, and a plurality of decompression boxes 28 are connected and arranged at all positions corresponding to each mold segment. . That is, the plurality of vent holes 27 and the plurality of decompression boxes 28 are drilled and installed at positions corresponding to the same mold segment, and the plurality of vent holes 27 and the plurality of decompression boxes 28 are communicated with each other.

  An airtight hood 30 is attached around the plurality of decompression boxes 28 in order to keep the entire mold airtight. The plurality of decompression boxes 28 are placed in contact with the outer surface 26 of the mold by the lifting means 19. In the configuration of this embodiment, since the plurality of decompression boxes 28 cover almost the entire outer surface 26 of the mold, the airtight hood 30 may not necessarily be required.

  The plurality of decompression boxes 28 are respectively provided with suction ports 31 and air supply ports 32 as in the sixth embodiment. Each suction port 31 communicates with the decompression device 69 via the suction flow rate control means 29, and each air supply port 32 communicates with the air compression device 70 via the air supply flow rate control means 33.

  The operation and effect of this configuration will be described. Since the plurality of decompression boxes 28 cover substantially the entire outer surface 26 of the mold, partial decompression can be performed on each mold segment by sucking or supplying air from each decompression box 28 individually. Then, a reduced pressure distribution of the entire mold, that is, a reduced pressure distribution of the cavity 11 is created as a composite of the plurality of partial reduced pressures.

  The plurality of decompression boxes 28 are arranged on the mold segment provided with the vent hole 27 and on the mold segment not provided with the vent hole, and are suctioned by all the decompression boxes 28 regardless of the presence or absence of the vent hole. Insufflation is possible. Therefore, almost the entire outer surface 26 of the mold is divided into segments and partially decompressed individually, so that the decompression distribution of the entire cavity 11 can be created with extremely high accuracy.

  The arrangement, diameter, and depth of the plurality of vent holes 27 are set to appropriate configurations that can obtain a predetermined reduced pressure distribution as in the fifth and sixth embodiments. The portion where the vent hole 27 is provided forms a strong partial decompression zone around the vent hole 27 by depressurization, and naturally has a strong influence on the depressurization distribution of the cavity 11. Therefore, it is possible to perform partial decompression with high accuracy by controlling the suction and / or flow rate of each decompression box 28 in consideration of the presence / absence of the vent hole 27, the arrangement, the shape of the cavity 11, and the like. As a result, a highly accurate predetermined reduced pressure distribution can be created in the mold cavity 11. This is one of the major features of this embodiment.

Another major feature of the present embodiment is that, when the entire outer surface of one mold is virtually divided into mold segments, the present invention is actually applied to a continuous line capable of high-efficiency production. The vent hole drilling device and the multiple vacuum box devices are greatly simplified.

First, regarding the drilling of the vent holes, the punching tool can be placed at all positions corresponding to each mold segment, and a desired site can be selected and drilled. As a result, in the fifth and sixth embodiments, means for moving and positioning the punching tool of the punching device to the position of the selected vent hole are required. Therefore, the adaptability to the tact of the continuous line capable of actual high-efficiency production has been improved.

  In addition, in the fifth and sixth embodiments, the decompression box device requires means for moving the plurality of decompression boxes to the position of the vent hole provided and positioning means, but in this embodiment, the plurality of decompression boxes are Since it is provided so as to correspond to the mold segments and covers the outer surface of one mold, there is no need to move and position to match the vent hole. It is only mounted on. Also in this respect, it can be said that the present embodiment is highly compatible with the tact of a continuous line capable of highly efficient production.

Further, another feature of the present embodiment is that it is easy even in a mold with a plurality of cavities arranged as shown in FIG. 8 by virtually dividing the mold into mold segments and performing suction or air supply. The present embodiment can be applied to a predetermined pressure distribution.

That is, in FIG. 8, the outer surface of the mold is divided into 4 × 4 × 16 virtual mold segments 34 to be sucked or supplied, and each product part and its end face side are sucked strongly. (Indicated by symbol S), the hot water portion is sucked moderately (indicated by symbol M), and the vicinity of the pouring portion is weakly sucked (indicated by symbol W), so that each product block has a reduced pressure pouring portion. It is possible to easily create a decompression distribution from the product part to the highly decompressed product part. Such a highly accurate reduced pressure distribution as in the present embodiment for a mold containing a plurality of molds cannot be realized at all by the conventional reduced pressure casting method. In addition, although it is possible to deal with a mold containing a plurality of molds in Examples 5 and 6, as described above, this example can cope with a continuous line capable of high-efficiency production. high.

  As described above, one of the outer surfaces of the mold is virtually divided into a plurality of mold segments, and vent holes are selected and provided at positions corresponding to the respective mold segments. Corresponding to a continuous line that can create a highly accurate reduced pressure distribution and enable actual high-efficiency production by connecting the pressure-reducing boxes and pouring while suctioning or feeding and reducing pressure. A vacuum casting method with high performance was provided.

  FIG. 9 shows an eighth embodiment. In this embodiment, when the vent hole is not provided on the outer surface of the mold using the means 3, one of the outer surfaces of the mold is virtually divided into a plurality of mold segments, and the plurality of mold segments are individually separated. A vacuum casting method in which gravity is poured by suction or air supply to reduce pressure will be described.

  In this embodiment, the structure of the casting frame, the mold, the plurality of decompression boxes, and the airtight box is the same as that of the fourth embodiment. However, the outer surface 26 of the mold is not provided with a vent hole. In other words, this is a special embodiment of the means 3.

  The operation and effect of this configuration will be described. In this embodiment, no vent hole is provided, but the entire mold outer surface 26 is covered by a plurality of decompression boxes 28. On the other hand, partial decompression can be performed. In this case, a plurality of partial depressurization zones corresponding to the suction flow rate or the air flow rate of each depressurization box 28 are formed in the mold below each depressurization box 28.

  As a result, a reduced pressure distribution is created in the cavity 11 as a composite of the plurality of partial reduced pressure zones. Since no vent holes are provided in the present embodiment, the thickness of each part of the upper mold 5 is not in a form in which a predetermined reduced pressure distribution is easily obtained. However, since almost the entire mold is covered with a plurality of decompression boxes 28, the suction flow rate of the decompression box at the site where the degree of decompression is to be increased is increased, and the suction flow rate of the site at which the intermediate degree of decompression is desired is reduced. A predetermined reduced pressure distribution can be obtained by appropriately adjusting the suction and the air supply, for example, by supplying a small amount of air to the part where the degree is desired to be lowered.

  Since no vent holes are provided in this embodiment, obtaining the predetermined decompression distribution as described above depends on the control of the suction flow rate and the air supply flow rate of each decompression box. Therefore, there is an advantage that the mold can be easily manufactured. That is, a normal template can be used as it is.

  As described above, even in a mold without a vent hole, the outer surface of the mold is virtually divided into a plurality of mold segments, and a plurality of decompression boxes connected to the respective mold segments are brought into contact with each other for suction or air supply. The pressure was reduced, and a predetermined reduced pressure distribution could be obtained with high accuracy. Hot water was poured in this reduced pressure state, and it became possible to fill the cavity smoothly with less disturbance of the hot water flow.

  The effect of the present embodiment is that a highly accurate reduced pressure distribution can be obtained by suctioning or feeding air to a completely normal mold by a plurality of segmented reduced pressure boxes without providing any vent holes in the mold. As a result, the generalization of the reduced pressure casting method has become easier.

  A ninth embodiment is shown in FIGS. FIG. 10 shows a state during pouring, and FIG. 11 shows a state after pouring. In this embodiment, a vacuum casting method in which means 5 is used to fill and melt the molten metal only in the desired cavity portion of the mold cavity to be filled with the product portion and the feeder portion will be described.

  The configurations of the casting frame, the mold, and the decompression method are the same as those in the fourth embodiment. In this embodiment, a plurality of vent holes 27 are provided so that the degree of pressure reduction of the desired cavity portion 35 is higher than that of the other cavity portions 38. The cast frame and mold of the present invention are not limited to the cast frame and mold of the present embodiment. The same applies to the following embodiments.

  First, the degree of pressure reduction of the cavity 11 is a pressure lower than the absolute value of the molten metal static pressure γH determined by the height H from the molten metal inlet 36 to the desired cavity part 35 to be filled to the uppermost part 37 of the cavity part. To a negative pressure state. Here, γ is the specific weight of the molten metal. The degree of decompression may be at least only the desired cavity portion 35 to be filled, but in this embodiment, since the whole decompression is performed, the entire cavity is substantially above the degree of decompression.

For example, in the case of a cast iron melt having a specific weight γ = 0.007 kgf / cm ³ , if the height from the inlet 36 to the uppermost portion 37 to the desired cavity portion is H = 10 cm, for example, γH = 0 The degree of decompression is 0.007 × 10 = 0.07 kgf / cm ² = 6865 Pa = 52.5 mmHg. Therefore, if the pressure is further reduced, only the desired cavity portion 35 can be filled with the molten metal. In actual operation, the degree of pressure reduction is multiplied by an appropriate safety factor in consideration of various conditions such as changes in pressure reduction due to pouring, cavity shape and molten metal material.

  Next, when a molten metal 23 having a volume approximately equal to or slightly larger than the volume of the desired cavity portion 35 is poured, the molten metal 23 flows from the gate portion 15 through the runner portion 14 and is the desired cavity portion 35. The part 12 and the feeder part 13 are filled. Since at least the product part 12 and the hot metal part 13 have a reduced pressure of γH or more, the molten metal 23 is filled up to the uppermost part 37 of the desired cavity part 35. Since the amount of molten metal poured is only the volume of the product part 12 and the hot water supply part 13, naturally only this part is filled, and there is no molten metal in the runner part 14 and the spout part 15. In this embodiment, a small ladle that weighed one frame was used for pouring, but it is also possible to measure and pour the desired amount with a large ladle containing several frames of molten metal. is there. The same applies to the following embodiments.

  Thereafter, this reduced pressure is maintained until the filled molten metal 23 is solidified, and a cast product having only the product portion 12 and the hot metal portion 13 which are desired cavity portions 35 can be obtained. Until the molten metal 23 is solidified, the filled molten metal 23 does not necessarily have to be completely solidified. Even if the molten metal near the boundary portion 39 between the desired cavity portion 35 and the other portion 38 stops the pressure reduction, What is necessary is just to hold | maintain pressure reduction until it solidifies to such an extent that it does not flow out to the part 15 side.

  Here, the meaning of the degree of decompression γH is the melt pressure at which the molten metal 23 filled in the product part 12 and the hot metal part 13 tends to flow out from the vicinity of the boundary part 39 described above. Therefore, the molten metal 23 will not flow out if the degree of decompression is kept higher than this.

  By the way, although the degree of decompression γH, even if the degree of decompression is maintained at or above the degree of decompression before pouring, the decompression in the mold is broken near the pouring gate 15 and the degree of decompression of the cavity 11 also changes with the start of pouring. become. Therefore, in order to keep the degree of decompression at γH or higher, it is necessary to perform decompression in consideration of this change in decompression.

  In general, in a general casting method with a total reduced pressure, after the reduced pressure changes with the pouring, the reduced pressure acts to make the entire pressure uniform, so the molten metal is actively sucked into the desired cavity. No induced decompression distribution is created. Therefore, it is necessary to control the pressure reduction in consideration of this point.

  However, in the present embodiment, although the overall pressure is reduced, the degree of pressure reduction of the product portion 12 and the hot water supply portion 13 which are desired cavity portions 35 to be filled with the molten metal through the plurality of vent holes 27 is high, and the pressure on the side of the gate portion 15 is low. Since the distribution is created, it is possible to cope with changes in pressure reduction caused by pouring. In addition, since the present Example changes the diameter and the depth of the some ventilation hole 27 as shown in FIG.

  As described above, at least the desired degree of vacuum of the cavity portion is set to γH or more, a molten metal having a volume almost equal to that of the desired cavity portion is poured, and the reduced pressure is maintained until solidification. A casting with only a part could be obtained.

  As a result, the injection yield indicated by product weight / injection weight is greatly improved. Further, since the sprue portion and the runner portion have cavities but are not filled with molten metal, they do not exist at the time of unraveling, and the unraveling process and the treatment of the return material are greatly simplified.

As described above, the present embodiment provides a reduced pressure casting method that can provide an innovative improvement effect in terms of the injection yield and the post-process as compared with the conventional casting method, and can greatly reduce the manufacturing cost.

  A tenth embodiment is shown in FIGS. 12 shows a state during pouring, and FIG. 13 shows a state after pouring. In this embodiment, for the case of a mold not provided with a vent hole, means 4 is used, and the product portion and the hot metal portion of the cavities are used as desired cavity portions, and the molten metal is filled only in those portions and solidified. The casting method will be described.

  The configurations of the casting frame, the mold, and the decompression method are the same as those in the first embodiment. In this embodiment, no vent hole is provided.

  In this embodiment, the pressure reducing method is exactly the same as that in the ninth embodiment. First, the degree of pressure reduction of the cavity 11 is a pressure lower than the absolute value of the molten metal static pressure γH determined by the height H from the molten metal inlet 36 to the desired cavity part 35 to be filled to the uppermost part 37 of the cavity part. To a negative pressure state. Next, when the molten metal 23 having a volume substantially equal to the volume of the desired cavity portion 35 is poured, the molten metal 23 flows from the gate portion 15 through the runner portion 14 and the product portion 12 and the feeder portion that are the desired cavity portions 35. 13 is filled. Then, by maintaining the reduced pressure until the vicinity of the boundary 39 between the desired cavity portion 35 and the other cavity portion 38 is solidified, a cast product in which only the desired cavity portion 35 is filled with molten metal is obtained. Can do.

  Thus, in the present embodiment as well, in the same manner as in the ninth embodiment, only the desired cavity portion 35 can be filled with the molten metal. However, there is a slight difference in the stability of the pouring between Example 9 and this example. That is, as described above, in such total decompression, there is a difference in the response to the fact that decompression is broken in the vicinity of the sprue portion 15 with the start of pouring and the decompression distribution changes greatly. In the ninth embodiment, a plurality of vent holes are provided so that the degree of pressure reduction of the desired cavity portion 35 is higher than that of the other cavity portions 38, so that this is corrected even for pressure change due to the start of pouring. Thus, it is easy to recover an appropriate reduced pressure distribution.

Since no vent holes are provided in the present embodiment, the entire mold cavity is created with a uniform decompression distribution, and the action of recovering the decompression distribution appropriate for filling the molten metal with respect to the decompression change is weak. However, it is possible to fill only the desired cavity portion by appropriately adjusting the reduced pressure. A feature of the present embodiment is that a normal mold without a vent hole can be applied. In this respect, the versatility is higher than that of the ninth embodiment.

  Moreover, the stability problem at the time of pouring of a present Example can be improved as follows as an example. For example, it is effective to provide another suction pressure reducing means in the vicinity of a desired cavity portion in addition to the overall pressure reduction. In other words, when the degree of decompression changes with pouring, the other suction decompression means keeps at least the decompression distribution near the desired cavity portion. This greatly improves the stability of the pouring.

  As described above, the feature of the present embodiment is that, without providing any vent hole in the mold, that is, using a normal mold, at least the degree of decompression of a desired cavity portion is stably maintained at a value higher than γH, and desired By casting a molten metal having a volume substantially equal to that of the cavity portion, it is possible to obtain a cast product in which the molten metal is filled only in a desired cavity portion.

  Example 11 is shown in FIGS. FIG. 14 shows a state during pouring, and FIG. 15 shows a state after pouring. In this embodiment, a vacuum casting method in which the means 8 is used to pour only a desired cavity portion with the same configuration as that of the embodiment 6 will be described.

  In this embodiment, a plurality of ventilation holes 27 are provided, and the ventilation holes in the parts are large and deeply drilled so as to increase the degree of decompression of the product part 12 and the hot water supply part 13 which are desired cavity parts 35. Has been. Each vent hole 27 communicates with a plurality of decompression boxes 28 capable of suction or air supply, and the suction flow rate and the air supply flow rate are individually controlled. Can be controlled.

  In other words, each part is decompressed by two kinds of adjusting means: adjustment of the degree of decompression of each part depending on the size and depth of each vent hole 27, and adjustment of the degree of decompression by controlling the suction flow rate and the air supply flow rate of each decompression box 28. The degree can be adjusted.

First, using the above-described decompression means, the degree of decompression of the product part 12 and the feeder part 13 is set to γH or more, and the degree of decompression of the gate part 15 is lower than this, and the degree of decompression is as close to atmospheric pressure as possible. In order to reduce the degree of decompression of the gate 15, a small amount of compressed air is supplied to the vent hole of the portion. That is, a reduced pressure distribution is created such that the degree of reduced pressure increases from the gate portion 15 side toward the product portion 12.

  Then, a molten metal 23 having a volume substantially equal to the volume of the product section 12 and the feeder section 13 is poured. The molten metal 23 is sucked and induced in the reduced pressure distribution of the cavity 11 and is filled in the product portion 12 and the hot metal portion 13. Of course, the runner 14 and the spout 15 are not filled with molten metal. That is, a cast product having only the product part 12 and the feeder part 13 is obtained.

  Here, the pouring process is considered. With the start of pouring, the reduced pressure in the initial state is broken in the vicinity of the spout 15 and the degree of decompression of the cavity 11 also changes. However, in the present embodiment, since the pressure reduction degree near the gate 15 is reduced from the initial state to a pressure reduction degree close to the atmospheric pressure, the change in the pressure reduction degree of the cavity 11 is small.

This point is different from the previous tenth embodiment. That is, in Example 10, since the whole pressure reduction was used, the change of the pressure reduction degree with the start of pouring was slightly large. However, in this embodiment, since the degree of decompression near the gate 15 is set low from the beginning, the change in the degree of decompression is small.

  As a result, in this embodiment, the change in pressure reduction received by the molten metal is small, there is little disturbance of the molten metal flow, and a quieter and smoother filling is possible.

  As described above, the two kinds of pressure reduction adjustments using a plurality of vent holes and a plurality of pressure reduction boxes adjust the pressure reduction degree of a desired cavity portion, and provide a pressure reduction distribution that lowers the vicinity of the pouring gate portion to pour hot water. Thus, it was possible to easily fill the molten metal only with a desired cavity portion.

  In this embodiment, the degree of decompression adjustment using a plurality of vent holes and a plurality of decompression boxes is used together. However, if a decompression distribution can be created so as to increase the degree of decompression of a desired cavity portion and lower the other portions, The same action and effect can be obtained.

  For example, a combination of a mold with a vent hole and an overall decompression, a combination of a mold without a vent hole and a segmented decompression box used in Example 7, a combination of a partial decompression and an overall decompression with a mold without a vent hole, etc. If the decompression method can create a distribution, almost the same operation and effect can be obtained.

  A twelfth embodiment is shown in FIGS. FIG. 16 shows a state during pouring, and FIG. 17 shows a state after pouring. In the present embodiment, a vacuum casting method in which means 9 is used to reduce pressure from a plurality of mold segments virtually provided in the same configuration as in Embodiment 4 to pour only a desired cavity portion will be described.

  In the present embodiment, the structure of the casting frame and the mold is the same as in the seventh embodiment. Further, a plurality of vent holes 27 are provided so that the desired degree of decompression of the cavity portion 35 is increased. In the present embodiment, only a desired cavity portion 35 is decompressed while being suctioned or fed by a plurality of decompression boxes 28 placed on a plurality of virtually divided mold segments 34 used in the seventh embodiment. The hot water was poured into.

  In the present embodiment, as described in the seventh embodiment, one mold outer surface 26 is covered with the plurality of decompression boxes 28, so that each segment of the mold can be divided and partial decompression can be performed. In addition, the decompression distribution of the cavity can be created. Therefore, pouring of water into only the desired cavity portion 35 is further ensured.

  Example 13 is shown in FIGS. 18 shows a state during pouring, and FIG. 19 shows a state after pouring. In the present embodiment, a reduced pressure casting method in which the melt is filled only in a desired cavity portion in so-called vertical casting using a mold having a vertical die-matching surface will be described.

  First, the configuration of the mold 4 of this embodiment will be described. The mold cavity is composed of four product parts 12, four feeder parts 13 provided on each of them, and a pouring part 15 and a runner part 14 for filling the molten metal. Then, two product parts 12 are arranged in the upper and lower stages. Here, the point different from the normal vertical casting is that the runner portion 14 and the spout portion 15 are arranged independently for the upper stage and the lower stage.

  Next, the arrangement of the vent holes for reducing the pressure will be described. The vent hole 27 is provided from the upper surface 42 of the mold toward the upper part of each feeder 13 with respect to the upper stage. Further, the lower stage communicates with the mold upper surface 42 by a vent hole 40 extending horizontally from an upper portion of each feeder 13 and a vent hole 41 extending vertically. In the vertical mold, these vent holes can be formed by molding.

  In addition, a decompression box 28 communicating with the decompression device 69 is placed in contact with each vent hole so that the decompression can be performed through each vent hole.

  The state of the outer surface of the mold will be described. In general, the mold 4 used for vertical casting has an upper surface open and a lower surface provided with a mold conveying tool 43, and there is a certain gap. Also, a mold clamping member 44 is provided on the side surface, which also has a certain gap.

In this embodiment, the product portion 12 and the feeder portion 13 which are desired cavity portions are made to have a predetermined degree of decompression γH or more while allowing a certain amount of air inflow from the gap between these peripheral members on the lower surface and the side surface. . Here, γ is the specific weight of the molten metal to be poured, and H is the height from the molten metal inlet 36 to the product part 12 to the uppermost part 37 of the feeder part 13.

  An effect is demonstrated by this structure. First, the pressure is reduced by the pressure reducing box 28, and the degree of pressure reduction of the product part 12 and the hot water supply part 13 is set to γH or more. Then, when molten metal having a volume substantially equal to that of the two sets of the product part 12 and the feeder part 13 in the lower stage is poured first, the product part 12 and the feeder part 13 are maintained at a reduced pressure of γH or more. Only the product part 12 and the hot water supply part 13 are filled from the gate part 15 through the runner part 14. Next, in the same manner, the two sets of product parts 12 and the hot water supply part 13 in the upper stage are filled with the molten metal from the other pouring part 15.

Thus, it was possible to fill the molten metal only in the two sets of the upper and lower product parts 12 and the feeder part 13 which are the desired cavity portions 35. In addition, an effect | action is the same regardless of the order which pours up and down hot water.

  After the filling of the molten metal is completed, by maintaining the reduced pressure until the molten metal inlet 36 to the product part 12 is solidified, it is possible to obtain a cast product in which only the product part 12 and the feeder part 13 are filled with the molten metal.

  In this embodiment, the lower pressure is also reduced from the upper surface 42 of the mold. However, it is also possible to reduce the pressure by arranging the pressure reducing box 28 at the side of the clamp member 44 on the side surface.

  As described above, not only in the horizontal split mold but also in the vertical mold, it was possible to fill the melt only in a desired cavity portion by using the vent hole and the vacuum box. Note that if the gap between the lower surface and the side surface of the mold is eliminated to increase the airtightness, the pressure reduction can be facilitated, and this embodiment can be more easily performed.

  A fourteenth embodiment is shown in FIGS. FIG. 20 shows a state during pouring, and FIG. 21 shows a state after pouring. In the present embodiment, a reduced pressure casting method will be described in which the means 7 is also used to provide a vent hole when the mold is a mold and fill the molten metal only in a desired cavity portion.

  First, vent holes 27 are provided from the upper surface of the upper mold in the vicinity of the product portion 12 and the feeder portion 13 which are desired cavity portions 35 of the mold 45. The vent hole 27 is composed of a perforation hole 46 perforated from the outer surface of the mold and a vent 47 having a clearance that does not allow the molten metal provided at the tip of the vent hole 27 to pass therethrough. Therefore, the mold body is not breathable, but the cavity 11 can be decompressed through the vent hole 27.

  Further, air seal members 8 are arranged on the upper and lower mating surfaces of the mold so that airtightness can be maintained.

  The mold is accommodated in an airtight container 48. Further, the airtight container 48 is provided with a suction hole 17 at one place, and the suction pipe 18 connected to the decompression device 69 is inserted from the suction hole 17, and the decompression box 28 attached to the tip of the suction pipe 18 is inserted into the ventilation hole 27. The suction pressure can be reduced by abutting against.

  The operation and effect of this configuration will be described. First, the decompression device 69 is operated, and the degree of decompression of at least the desired cavity portion 35 of the product portion 12 and the feeder portion 13 is set to γH or more. In this embodiment, since the pressure is reduced from the product part 12 and the hot water supply part 13, a reduced pressure distribution is created in which the degree of pressure reduction in the part is high and the side of the gate part 15 is low.

  In this state, when a molten metal having substantially the same volume as the desired cavity portion 35 is poured, the molten metal is sucked and guided by the reduced pressure distribution, and fills the product portion 12 and the hot water portion 13. Naturally, there is no molten metal in the runway portion 14 and the gate portion 15. That is, only the desired cavity portion 35 was filled with the molten metal. Thereafter, the reduced pressure is maintained until at least the vicinity of the boundary 39 of the molten metal is solidified.

  In this embodiment, the pressure is reduced using an airtight container covering the entire mold, but the present invention is not limited to this. Even if the pressure is reduced using a pressure reducing hood as in the first embodiment, the operation and effect are almost the same. is there.

  As described above, even in the mold, it is possible to fill the melt only in a desired cavity portion by using a combination of the vent hole and an appropriate pressure reduction method.

  The meaning of this example is that a reduced pressure in which only a desired cavity portion of the present invention is filled with molten metal by providing a plurality of vent holes as appropriate in any mold. The casting method can be applied.

  A fifteenth embodiment is shown in FIGS. FIG. 22 shows a state during pouring, and FIG. 23 shows a state after pouring. In the present embodiment, a vacuum casting method will be described in which means 6 is used to reduce the pressure after the start of pouring and pour only the desired cavity portion.

  The configurations of the cast frame and the mold are the same as those in the fifth embodiment. The decompression was performed by placing a plurality of decompression boxes 28 communicated with the decompression device 69 on the upper mold 5.

  In the examples so far, the molten metal was poured after the pressure was reduced to a predetermined degree of pressure reduction, but in this example, the order was reversed. That is, initially, the molten metal 23 having the same volume as the desired cavity portion 35 is poured without reducing the pressure. Then, the molten metal 23 is distributed and filled throughout the cavity 11 as shown in FIG.

  Next, when decompression is started and the degree of decompression of the desired cavity portion 35 is increased to γH or more, the molten metal 23 is sucked and filled in the product portion 12 and the feeder portion 13 which are the desired cavity portion 35. The If the degree of vacuum is maintained at γH or more until solidification in this state, a cast product having only the product part 12 and the feeder part 13 can be obtained.

  Note that FIG. 22 shows a state in which the molten metal 22 is stationary for the sake of explanation, but it is not always necessary to wait for the molten metal 23 to stop, and the decompression can be started at an appropriate timing after the start of pouring. .

  In this way, even if the pressure is reduced after pouring, it is possible to fill only the desired cavity portion as in Examples 9 to 14 where the pressure is reduced before pouring. Next, the difference will be described.

  First, when pouring after depressurizing, the depressurization is broken in the vicinity of the spout 15 as the pouring starts, and a depressurization change occurs. Due to this action, the molten metal flow tends to be disturbed. Next, when the pressure is reduced after pouring, there is no change in pressure accompanying the pouring, so the molten metal is not affected by any pressure change. That is to say, with regard to a change in pressure reduction due to pouring, it is preferable to reduce the pressure after pouring because there is less disturbance in the flow of the molten metal.

  However, in the method of depressurizing after pouring, since the initial depressurization is not performed, the pouring rate is lower than the method of pouring after depressurization. Moreover, if the timing for starting the pressure reduction is delayed, oxidation of the molten metal and a decrease in temperature occur, causing casting defects. Therefore, it may be difficult to apply in the case of molten metal that easily oxidizes or low-temperature pouring, or depending on conditions such as the shape, thickness, and cavity layout of the product.

  As described above, it is possible to fill only the desired cavity portion by either the method of pouring with reduced pressure or the method of reducing the pressure after the start of pouring. It is desirable to use which one is applied in consideration of various conditions of the molten metal and the mold as described above.

  Example 16 is shown in FIG. In this embodiment, in the casting method in which the pressure is reduced and the molten metal is poured into the desired cavity portion using the means 10, the desired cavity portion and other cavities are stably increased in order to stably increase the degree of decompression of the desired cavity portion. Described below is a vacuum casting method in which an air-permeable sealing member that is non-breathable or has an air permeability lower than that of the mold near the boundary of the tee portion and that disappears or melts due to the heat of the molten metal is installed.

  The configurations of the mold, the casting frame, and the decompression means are the same as those in the fifth embodiment. That is, a plurality of vent holes 27 were provided from the outer surface 26 of the mold, and the pressure was reduced by a plurality of decompression boxes 28 corresponding thereto. In this configuration, a reduced pressure distribution is created in which the degree of pressure reduction of the product portion 12 and the hot water supply portion 13 which are the desired cavity portions 35 is high.

  Then, a concave portion 49 is formed above and below the mold near the boundary 39 between the desired cavity portion 35 and the other cavity portion 38, and a foamed resin 50 of 50 mm × 50 mm × thickness 15 mm is installed there as a ventilation sealing member. did.

  When decompression is started in this state, the cavity 11 is divided into the desired cavity portion 35 and the other cavity portion 38 by the foamed resin 50, so that the degree of decompression of the desired cavity portion 35 is set to the other cavity. It can be quickly and stably increased with little influence of the portion 38. This is one function of the ventilation sealing member.

  Next, after the desired cavity portion 35 reaches a predetermined degree of decompression γH or more, when a molten metal 23 having a volume substantially equal to the desired cavity portion 35 is poured, the molten metal 23 reaches the foamed resin 50 and instantly reaches this. And the desired cavity portion 35 is filled.

  Although the pressure change occurs on the side of the spout 15 with the pouring, the influence of the pressure change does not appear in the desired cavity portion 35 at least until the molten metal reaches the foamed resin 50. Therefore, during this time, the desired cavity portion 35 can stably maintain a predetermined degree of decompression. This is another function of the ventilation sealing member.

  As described above, the ventilation sealing member has an action of stabilizing the degree of decompression of a desired cavity portion before and after pouring. As a result, the filling of the molten metal into the desired cavity portion can be performed more stably in addition to the preferable reduced pressure distribution by the plurality of vent holes and the reduced pressure box.

  In the present embodiment, a plurality of decompression boxes are used for decompression. However, the ventilation sealing member works in the same way even in the case of partial decompression with respect to a desired cavity portion and the entire decompression.

  In addition, since the vent sealing member has a function of separating a desired cavity portion from the side of the gate and keeping its degree of decompression stable, the vent sealing member is more breathable than a non-breathable member such as a metal piece or a plate material or a mold. If it is a low member, the same effect | action and effect can be acquired.

  Example 17 is shown in FIG. In this embodiment, in the reduced pressure casting method in which the pressure is reduced and poured into a desired cavity using the means 11, the vent sealing member provided near the boundary as described in the embodiment 16 is used. A vacuum casting method in which the time from contact to disappearance or melting is 2 to 5 seconds will be described.

The configurations of the mold, the casting frame, and the decompression means are the same as those in the sixteenth embodiment. That is, a plurality of vent holes 27 were provided from the outer surface 26 of the mold, and the pressure was reduced by a plurality of decompression boxes 28 corresponding thereto. And the steel plate 51 of 50 mm x 50 mm x thickness 4mm was installed in the recessed part 49 as a ventilation sealing member.

  The operation and effect of this configuration will be described. This steel plate 51 has exactly the same action as the foamed resin of Example 11 in terms of stabilization of reduced pressure. However, in this embodiment, after the molten metal reaches the steel plate 51, it takes about 3 seconds until the steel plate 51 melts and the molten metal begins to flow into the desired cavity portion 35.

  A state in which the molten metal has reached the steel plate 51 is shown in FIG. That is, for about 3 seconds, the molten metal fills the portion excluding the desired cavity portion 35 as shown in the figure and is stationary. Therefore, even if the molten metal flow is disturbed along with the pouring, the molten metal is stopped once in this state, so that the molten metal flow is almost completely eliminated. That is, the dynamic pressure of the molten metal accompanying the pouring is converted into a static pressure. This is one function of the steel plate 51 which is the ventilation sealing member.

When the molten steel can flow into the desired cavity portion 35 by melting the steel plate 51, the molten metal flow is less disturbed by the reduced pressure of the desired cavity portion 35 and the static pressure of the molten metal, and the filling is performed smoothly. is there.

  In addition, another action of the molten metal once stopped in this way is the time for inclusions and air entrained in the molten metal to float and separate due to the specific gravity difference with the molten metal. Is to be given. This can improve the soundness of the cast product. In this embodiment, the time for the molten metal to stand still is about 3 seconds, but 2 seconds or more and 5 seconds or less is appropriate. The lower limit of 2 seconds is the minimum time required for recovering the static pressure of the molten metal and floating the inclusions. The upper limit of 5 seconds is set to prevent a temperature drop and oxidation of the molten metal.

  As described above, the vent sealing member of the present embodiment enables filling in a static pressure state by temporarily suspending the molten metal, and floats inclusions or the like mixed in the molten metal in the initial stage of pouring. It has an action to decrease. As a result, the desired cavity portion can be filled more stably.

  Embodiment 18 is shown in FIGS. FIG. 26 shows a state before pouring, and FIG. 27 shows a state after pouring. In the present embodiment, in the vacuum casting method in which the pressure is reduced and poured into the desired cavity using the means 12, the cavity in the vicinity of the boundary portion is solidified so that the molten metal filled in the desired cavity portion solidifies quickly. A vacuum casting method in which a molten metal blocking member is installed in the recess will be described.

  The configurations of the mold, the casting frame, and the decompression means are the same as those in the fifth embodiment. That is, a plurality of ventilation holes 27 were provided from the outer surface 26 of the mold, and the pressure was reduced by a plurality of pressure reduction boxes 28 corresponding thereto.

  In this embodiment, a concave portion 49 is provided near and above the boundary portion 39 between the desired cavity portion 35 and the other cavity portion 38, and a shell of 50 mm × 50 mm × thickness 15 mm molded with shell sand as a molten metal blocking member. The piece 52 was placed so as to fit in the recess 49 at the bottom of the cavity.

  The operation and effect of this configuration will be described. After performing a predetermined pressure reduction, when a molten metal 23 having a volume substantially equal to the desired cavity portion 35 is poured, the molten metal 23 fills the desired cavity portion 35 as shown in the above embodiment. During the pouring, the shell piece 52 installed in the concave portion 49 at the bottom of the cavity remains in the concave portion 49 without obstructing the flow of the molten metal. After the pouring is completed, the shell piece 52 ascends to the concave portion at the upper part of the cavity by buoyancy as shown in FIG.

  When the reduced pressure is maintained in this state, the solidification of the molten metal proceeds. However, since the molten metal in contact with the shell piece 52 is deprived of heat by the shell piece 52, the solidification proceeds more rapidly than the case without the shell piece 52. Therefore, it is possible to shorten the time for maintaining the reduced pressure.

  In addition, even after the pouring is completed and the shell piece 52 floats up, the shell piece 52 is pressed against the pouring gate 15 side in the concave portion 49 above and below the cavity by the static pressure of the molten metal even when the pressure decreases to γH or less. And acts to prevent the molten metal from flowing out. This pressing force cannot completely stop the outflow of the molten metal, but the outflow can be prevented if the pressure is slightly reduced.

  In addition, if this molten metal interruption | blocking member has a specific gravity smaller than a molten metal and is fireproof, the effect | action and effect are the same. The shapes of the molten metal blocking member and the concave portion are not limited to the present embodiment, and the same action and effect can be obtained by a combination of appropriate shapes.

As described above, by installing the molten metal blocking member in the concave portion of the cavity in the vicinity of the boundary portion, the decompression holding time after pouring can be shortened, and the production efficiency can be improved. According to the present embodiment, in the reduced pressure casting method of the present invention in which only a desired cavity portion is filled with molten metal, one of the problems is to solve the problem of requiring a certain reduced pressure holding time until pouring after pouring. It was possible to reduce.

  FIG. 28 shows Example 19. In the present embodiment, in the reduced pressure casting method in which the pressure is reduced and poured into a desired cavity using the means 13, the pressure is stably reduced and the molten metal filled in the desired cavity portion is solidified quickly. Described below is a vacuum casting method in which a sealing blocking member in which a ventilation sealing member and a molten metal blocking member used in Examples 16 and 18 are integrated is provided near the boundary between a desired cavity portion and other cavity portions. To do.

  The configurations of the mold, the casting frame, and the decompression means are the same as those in the sixteenth embodiment. That is, a plurality of vent holes 27 were provided from the outer surface 26 of the mold, and the pressure was reduced by a plurality of decompression boxes 28 corresponding thereto.

In this embodiment, the foamed resin 50 is used as the ventilation sealing member, the shell piece 52 is used as the molten metal blocking member, and the sealing blocking member 53 integrated with the foamed resin 50 at the top and the shell piece 52 at the bottom is desired. The cavity portion 35 and the other cavity portion 38 were installed in a cavity recess 49 near the boundary 39.

  The action and effect of the sealing blocking member 53 is a combination of the effects of the two members of the ventilation sealing member and the molten metal blocking member shown in Examples 16 and 18. That is, when the pressure is reduced, the foamed resin 50 stabilizes the pressure reduction of the cavity, and after pouring, the shell piece 52 rises and promotes solidification near the boundary 39. In addition, even if it uses the steel plate 51 of Example 17 instead of the foamed resin 50, an effect | action and an effect are the same.

  As a result, members having two actions can be installed as one body, and workability is improved. In addition, the turbulence of the molten metal flow during pouring can be reduced, and the decompression holding time after pouring can be shortened to increase production efficiency.

  Example 20 is shown in FIG. In the present embodiment, in the reduced pressure casting method in which the pressure is reduced and poured into a desired cavity using the means 14, the vent hole and the vicinity of the boundary portion are set so that the molten metal filled in the desired cavity portion solidifies quickly. A decompression casting method in which strong air is supplied from the cooling hole and then rapidly cooled will be described.

  The configurations of the mold, the casting frame, and the decompression means are the same as in the sixth embodiment. That is, a plurality of vent holes 27 were provided from the outer surface 26 of the mold, and the pressure was reduced by a plurality of decompression boxes 28 corresponding thereto.

In the present embodiment, a deep cooling hole 54 is provided that is larger than the other part and near the boundary 39 between the desired cavity part 35 and the other cavity part 38 to be filled with the molten metal from the outer surface 26 of the mold. .

  After a predetermined pressure reduction, when a molten metal having a volume substantially equal to the desired cavity portion 35 is poured, the molten metal fills the desired cavity portion 35 as shown in the above embodiment. Thereafter, the air can be cooled by suction or air supply through the respective vent holes 27. At that time, a large amount of compressed air is supplied to the large and deep cooling holes 54 provided in the vicinity of the boundary portion 39 to supply the boundary portion. The vicinity of 39 was quickly cooled. In addition, although strong suction can be performed on the cooling hole 54 to increase the cooling rate, generally the cooling rate can be increased by supplying compressed air.

  Thus, by providing a large and deep cooling hole 54 in the vicinity of the boundary portion 39 and supplying a large amount of air from the decompression box 28, the vicinity of the boundary portion 39 can be quickly solidified and the decompression holding time can be shortened. .

  Note that the cooling hole provided near the boundary is not necessarily large and deep if there is a restriction on the cavity shape, etc., and has an appropriate size and depth. It can also be adjusted by qi flow. In addition, when no cooling hole is provided, cooling can be performed by suction or air supply from a vent hole near the boundary.

  As described above, one of the vacuum casting methods in which the molten metal is filled only in a desired cavity portion by cooling from the melt blocking member of Example 18 and the vent hole and / or the cooling hole in the vicinity of the boundary of the present example. The reduced pressure retention time, which was an issue of, was significantly shortened.

  A twenty-first embodiment is shown in FIG. In the present embodiment, a vacuum casting method that uses means 15 to prevent burrs that are likely to occur in the mold gap in the vacuum casting method will be described.

  The basic configuration of the mold and the cast frame is the same as that of the first embodiment. In the present embodiment, the case where the decompression hood 16 is placed on the upper part of the mold and the entire mold is decompressed will be described so that the principle of the burr prevention method can be easily understood.

  The mold is provided with an air supply hole 57 that communicates with the core base plate 55 and an air supply hole 58 that communicates with the mating surface 56 of the upper and lower molds. Then, the air supply pipe 60 is communicated with the air supply holes 57 and 58 through the air supply holes 59 provided in two places of the decompression hood 16 so as to supply compressed air.

  The operation and effect of this configuration will be described. In general, when the mold is depressurized in the vacuum casting method, the gaps such as the core baseboard 55 and the mating surface 56 of the upper and lower molds are also in a depressurized state, so that the molten metal is likely to enter and burrs are likely to occur.

  Therefore, in the present embodiment, as described above, compressed air is supplied from the two air supply holes 57 and 58 to these gaps to stop the molten metal entering. That is, by supplying compressed air, the pressure in these gaps is maintained at a positive pressure instead of a negative pressure due to the reduced pressure, so that an action of preventing the molten metal from entering can be exerted. Moreover, since the molten metal in which compressed air permeates is cooled to lower the fluidity, the molten metal is further less likely to enter the gap.

  As described above, even in the reduced pressure casting method in which burrs are likely to occur, burrs can be prevented by providing air supply holes in portions where burrs are likely to be generated and supplying compressed air thereto. The disappearance of burrs eliminates the burrs removal work in the post-process that is generally performed in the past, and brings about the effect of significant cost reduction and process shortening.

In this embodiment, the case where one product is cast is shown. However, in the case where a plurality of products are cast as well, similarly, a burr is formed by providing air supply holes communicating with the outer surface in necessary portions to supply compressed air. Can be prevented.
In that case, it is most effective to perform air supply using a plurality of segmented decompression boxes as used in the seventh embodiment.

  A twenty-second embodiment is shown in FIG. In this example, when pouring spheroidal graphite cast iron in the reduced pressure casting method using means 16, a reduced pressure casting method in which a highly accurate predetermined reduced pressure distribution was created in the cavity was obtained by Examples 1 to 21. Therefore, the vacuum casting method in which the pouring temperature is 1300 ° C. or lower will be described.

  The basic configuration of the mold and the cast frame is the same as that of the fifteenth embodiment. In this example, in order to clarify the effect of the pouring temperature on the shrinkage nest, two molds, A and B, were prepared, and both molds were poured without a feeder. A was poured in a normal casting without decompression, and B was poured in a reduced pressure by the decompression casting method according to the present invention. In addition, the pouring temperature was set to 1300 ° C. because A is a general temperature of 1400 ° C. and B is 1300 ° C. because a highly accurate reduced pressure distribution can be created by the present invention and a stable hot water can be obtained.

The molten metal is spheroidal graphite cast iron, and the chemical components are C 3.70%, Si 2.62%, Mn 0.30%, Cu 0.05%, P 0.032%, S 0.008% and Mg 0.045%. Spheroidization was performed using a FeSiMg alloy. The product weight is 5.2 kg.

After casting, the product was cut, and the area of the shrinkage nest was measured by the penetrant flaw detection method. As a result, A was 785 mm ² and B was 52 mm ² . That is, the shrinkage nest could be reduced to about 1/15 by lowering the pouring temperature from 1400 ° C. to 1300 ° C. by 100 ° C. B is not completely defect-free, but is almost equivalent to a defect-free product in practical strength.

  Consider this result. In spheroidal graphite cast iron, liquid shrinkage, expansion due to graphitization, and shrinkage due to austenite crystallization occur after solidification at the eutectic temperature of 1150 ° C. after pouring. Although the detailed calculation is as described in the above-mentioned means 14, the sum of the expansion and contraction is −1.05% for the 1400 ° C. pouring of A and + 0.45% for the 1300 ° C. pouring of B. It is.

Therefore, in A, the total shrinks and a shrinkage nest remains, which means that a hot water is necessary to eliminate the shrinkage nest. On the other hand, in B, the sum is expanded, meaning that no shrinkage is generated even if there is no feeder.

However, this is a judgment based on simple calculations of the expansion and contraction of the molten metal. In addition, the generation of shrinkage nests is affected by the expansion of the mold, the speed of formation of the solidified skin, and the generated gas. These factors are considered to be added to the above-described total value of the expansion and contraction of the molten metal, resulting in such a result.

However, lowering the pouring temperature by 100 ° C. corresponds to a difference of 1.5% in shrinkage, and if this is simply calculated, the difference in shrinkage volume between A and B in the 5.2 kg product is the molten metal If the specific gravity of 7.0 is 7.0, then 5200 / 7.0 × 1.5 / 100 = 11.1 cm ³ . That is, for example, the difference between the shrinkage nests becomes so large as to correspond to about 11 in a 1 cm ³ cube. The effect of lowering the pouring temperature by 100 ° C. is so great.

  As a result of this example, the shrinkage nest was not completely eliminated by the 1300 ° C. pouring in the vacuum casting method of B, but the area of the shrinkage nest was about 1 in comparison with the 1400 ° C. pouring of A at no depressurization. / 15, and a near-zero shrinkage was obtained. This is due to the fact that the hot water circulation is improved by the reduced pressure casting method of the present invention, and the pouring temperature can be lowered by 100 ° C. In the experiment of the present inventor, it has been confirmed that pouring can be carried out even at 1250 ° C. with no poor hot water if the pressure is properly reduced by a pressure reducing method using a plurality of pressure reducing boxes. Such low temperature pouring can further reduce shrinkage defects.

  In addition to this embodiment, a casting method with fewer shrinkage defects can be obtained by using cooling control in Examples 23 and 24, which will be described later, in combination.

  As described above, by combining the reduced-pressure casting method of the present invention and the low-temperature pouring, it was possible to obtain a cast product that is nearly defect-free with no sprinkler in spheroidal graphite cast iron. This can be applied to general cast iron including normal cast iron (gray cast iron) and special cast iron. In particular, in the case of ordinary cast iron, since the solidification form is a skin generation type solidification as compared with the massey type solidification of spheroidal graphite cast iron, the occurrence of shrinkage cavities is further reduced, and this embodiment can be applied more easily.

  Thus, if a casting can be manufactured without a feeder, first, the direct effect that the amount of molten metal required can be reduced is acquired. Furthermore, since the place where the hot water was in the original cavity becomes a space, it is possible to store additional products and improve the production efficiency. In addition, since there is no feeder, the process after the release of the frame is only the product part, and the effect of being simplified can be obtained.

  As described above, the reduced pressure casting method of the cast iron of this embodiment can greatly increase the production efficiency of cast iron parts that are produced about 50 million tons per year in the fields of automobiles, construction, machinery, etc. in the world. is there.

  FIG. 32 shows Example 23. In the present embodiment, the means 17 is used to control the flow rate of the gas body sucked or fed through the plurality of vent holes, cooling holes and mold segments after pouring in the vacuum casting method, so that the desired molten metal is filled. A vacuum casting method in which solidification progresses sequentially from the site will be described.

  The basic configuration of the mold, the casting frame, and the decompression means is the same as that of the seventh embodiment. In the present embodiment, a plurality of vent holes 27 are provided at a selected portion of the segment, and suction or air feeding is performed by a plurality of decompression boxes 28 placed on the mold to cool during and after pouring. went.

  First, the decompression before pouring was set to a decompression distribution in which the decompression degree of the product part 12 and the hot water supply part 13 was high and the decompression degree on the side of the pouring part 15 was low, as described in the above embodiment. After a predetermined pressure reduction, a molten metal having a volume substantially equal to the desired cavity portion 35 was poured to fill only the desired cavity portion 35.

  By the way, in general, as one method for preventing shrinkage in casting, the cooling of the product portion 12 is sequentially cooled from the portion far from the feeder portion 13 toward the feeder, so-called directional solidification. The position, size and number of chillers are devised. However, these methods are limited by the product shape, and the desired directional solidification is not always obtained.

  In this embodiment, in order to enable highly accurate directional solidification after pouring is completed, a plurality of vent holes 27 are provided from the outer surface 26 of the mold, and after pouring, a portion farthest from the hot water portion 13 of the product portion 12. A large amount of compressed air was supplied to the product section, and the compressed air with the flow rate lowered was sequentially supplied to the product section 12 and the hot water supply section 13. And the suction part 15 vicinity performed weak suction. In addition, a large amount of compressed air was supplied at the initial stage of cooling so as to solidify quickly in order to shorten the decompression holding time in the vicinity of the boundary portion 39 between the desired cavity portion 35 to be filled with the molten metal and the other cavity portion 38. .

  As a result, the cooling rate of each part became as shown in the lowermost stage of FIG. 32, and the directional solidification that solidifies sequentially from the portion farthest from the feeder 12 could be performed. As a result, the product part 12 was solidified from the end face side, and the contraction was sequentially supplied from the adjacent part, and the soundness was improved. In some cases, it is possible to reduce or remove the feeder.

In addition, since the cooling rate of the vicinity of the boundary portion 39 between the desired cavity portion 35 to be filled with the molten metal and the other cavity portion 38 is increased by the initial rapid cooling, the rapid cooling of the boundary portion 39 increases the cooling rate of the feeder 13. The minimum time until the vicinity of the boundary 39 is solidified is set so as not to be present.

  In this embodiment, the same vent hole is used for decompression and air supply. However, if possible, the vent hole is used to obtain a desired decompression distribution and to obtain directional solidification as shown in the present embodiment. It is desirable to provide both a cooling hole for this purpose. In addition, the flow rate of suction or air supply from each ventilation hole and cooling hole is determined in consideration of the thickness of each part of the product and its positional relationship.

The highly accurate directional solidification as described above is possible because the position, size, depth, etc. of the ventilation holes and cooling holes are appropriately set according to the layout of the cavity, and it is suitable with multiple decompression boxes This is because the suction or the air supply is performed. It can never be obtained by countermeasures using ordinary hot water or cold metal.

  Note that this embodiment also has a great effect even in the case where a plurality of embodiments are included. In other words, in the case where a plurality of slags are contained, if an attempt is made to obtain directional solidification with a normal hot water or cooling metal, a large amount of hot water or cooling metal is used, which tends to increase the amount of molten metal and the number of steps. However, if the present embodiment is used, as shown in FIG. 8 of the seventh embodiment, a ventilation hole and / or a cooling hole as in the present embodiment is provided for each of a plurality of product blocks in the cavity, and suction is performed by a decompression box. Alternatively, directional coagulation can be easily obtained because air supply is performed.

  As described above, the vacuum casting method of the present invention can control the cooling process with high accuracy as well as the pouring process, and can easily perform the most desirable directional solidification of casting. As a result, it is possible to provide a great effect that the defects can be reduced and the hot water can be reduced or omitted.

  FIG. 33 shows Example 24. In this embodiment, the temperature of each gas body sucked and discharged from each part such as a plurality of vent holes, cooling holes and mold segments of the breathable mold after pouring in the reduced pressure casting method using the means 18 or the temperature and flow rate. Based on this data, the reduced pressure casting method for controlling the cooling state of the molten metal will be described.

The basic configuration of the mold, the casting frame, and the decompression means is the same as that of the twenty-third embodiment. In this embodiment, the gas body flow 79 sucked and discharged from each part of the mold ML, the compressed air flow 80 to be sent, the control signal flow 81 and the data signal flow 91 are configured as shown in FIG. . In the figure, one decompression box VB is shown.

That is, the gas body sucked and discharged from each part of the mold ML is guided to the suction flow rate / temperature measurement means VM through each decompression box VB, the flow rate and temperature are measured, and the data signal 91 is sent to the calculation means CL. And the cooling state of each part is estimated by the calculating means CL.

On the other hand, the flow rate and temperature of the compressed air to be supplied are measured by the air supply flow rate / temperature measurement means CM, and the data signal 91 is sent to the calculation means CL. And it becomes auxiliary data for estimation of the cooling state of each part by the calculating means CL.

In this way, the solidification state of each part is estimated by the calculation means CL based on the data of the temperature and flow rate of the gas bodies and compressed air from the plurality of decompression boxes VB. According to the result, a control signal 81 for approaching a desired cooling state is sent to the suction flow rate control means VC and the air supply flow rate control means CC. The flow rate is controlled by each control means, and suction or air supply is performed.

  In this way, by measuring the temperature and flow rate of the gas body and compressed air passing through the plurality of vent holes and the decompression box VB, the cooling state of each part of the mold can be estimated, and further suction and / or air supply can be performed according to the result. The desired cooling state could be obtained by controlling the flow rate.

  The fact that such a cooling-controlled decompression casting method has become possible is basically the effect of a plurality of vent holes provided in the mold and a plurality of decompression boxes corresponding thereto. Although this embodiment can be achieved by using a plurality of decompression boxes, a method using a segmented decompression box as in the seventh embodiment is particularly optimal. That is, in this case, the entire surface of the mold is divided and sucked or supplied, and a lot of data can be obtained from each part. Therefore, the cooling state can be estimated with high accuracy, and as a result, the cooling control can be performed with high accuracy. I can do it now.

  In this embodiment, the data of both the temperature and flow rate of the gas body and compressed air are measured, but almost the same operation and effect can be obtained only by the temperature.

  As described above, according to the present invention, it is possible to perform a reduced pressure casting method in which cooling control after pouring which has not been performed at all in the past is applied with high accuracy and ease. This means that, in the conventional casting industry, a technology has been provided that enables free cooling control for blank areas of the casting technology that have relied on natural cooling after pouring. And its significance is great.

  A twenty-fifth embodiment is shown in FIGS. In this embodiment, a vacuum casting method for adjusting the final solidification structure of the molten metal filled in the vacuum casting method to which the cooling control method shown in the embodiment 24 is applied by means 19 will be described.

The basic configuration of the mold, the casting frame, and the decompression means is the same as that of the twenty-third embodiment. In this example, after reducing the pressure and pouring the spheroidal graphite cast iron, the cooling of the important solidified region or transformation region is controlled in the process up to the de-frame, so as to obtain a desired final solidified structure. The molten metal is spheroidal graphite cast iron having the same components as in Example 22, and a material equivalent to FCD500 can be obtained by ordinary natural cooling.

  In this embodiment, after pouring, based on the data of the temperature and flow rate of the gas bodies and compressed air from the plurality of vent holes and the plurality of decompression boxes corresponding thereto, the cooling control method shown in the embodiment 24 is used as usual. Even fast cooling.

  FIG. 34 shows the cooling curve of this example. The figure shows a natural cooling curve 84 when the above cast iron molten metal is subjected to normal non-depressurized casting and naturally cooled in the mold, and a control cooling curve 85 when the controlled cooling according to this embodiment is performed. In the case of cast iron, the cooling rate of the region until the entire solidification is completed at the eutectic temperature and the eutectoid transformation region 83 where austenite is transformed into pearlite and ferrite is an important factor that determines the final solidification structure.

  As can be seen from FIG. 34, the cooling rate in the eutectic temperature region and the eutectoid transformation region 83 is higher in the controlled cooling of this embodiment than in the normal cooling.

  The final solidified structure and mechanical properties of both cooling are shown in FIG. The metal structure 87 when controlled cooling has a structure with more pearlite and less ferrite than the metal structure 86 when naturally cooled. In addition, the mechanical property is equivalent to FCD500 for natural cooling, whereas it is equivalent to FCD700 for controlled cooling, and has high tensile strength and proof stress, and elongation is the same value as natural cooling. In general, when the tensile strength increases, the elongation decreases. However, since the pearlite becomes dense by controlled cooling, such elongation is obtained.

  That is, a material having higher strength and toughness than ordinary casting could be obtained by pouring the same molten metal and controlling the cooling until the frame was opened.

Table 1

In general, the casting material is divided by changing the molten metal components or heat-treating the solidified casting. However, in the former, the number of types of molten metal to be prepared is increased, and the work is complicated. In the latter case, a large amount of heat energy for reheating is consumed, and an extra step of heat treatment is required, which causes a significant increase in cost.

  As shown in the present example, a casting method for adjusting a final solidified structure to obtain a desired material by controlling cooling in the mold from pouring to unraveling has not been performed at all. Therefore, the present embodiment solves the problems of the number of types of molten metal prepared in the current technology and the heat treatment process.

  A twenty-sixth embodiment is shown in FIG. In the present embodiment, there will be described a reduced pressure casting method in which means 20 is used to close the pouring gate or the pouring gate portion with a non-breathable member or a member having a lower air permeability than the mold and reduce the pressure until the molten metal is solidified. .

  The configurations of the casting frame, the mold, and the pressure reducing method are the same as those in the ninth embodiment. The state before pouring is the same as FIG. FIG. 36 shows a state after pouring. In this embodiment, as a desired cavity part to be filled with the product part and the hot metal part in the mold cavity, when the molten metal is filled and solidified only in that part, the effect of stably maintaining the degree of pressure reduction after pouring A vacuum casting method with a large value will be described.

As described in Example 9, after the pouring, the desired purpose can be achieved if the degree of pressure reduction in the desired cavity portion to be filled with the molten metal is maintained at γH or higher. However, since the pouring gate or the pouring gate portion is opened to the atmosphere along with pouring, the degree of decompression at that portion is greatly reduced, and the degree of decompression of the mold cavity is easily changed.

Therefore, in this embodiment, after pouring, the pouring port 21 is closed with the non-breathable member 92 and the pressure is reduced until the molten metal is solidified. As a result, the mold cavity is in the same sealed state as before the pouring, and as a result, the degree of decompression can be kept stable. In addition, the capacity of the decompression device can be reduced. The place closed by the non-breathable member 92 may be the pouring gate 21 as in this embodiment, or the pouring portion 15 has the same effect.

As the non-breathable member, metal, resin, rubber, plate and the like are suitable. In addition, when a certain amount of air can be allowed to flow in, a certain effect can be obtained even with a member having a lower air permeability than the mold, such as a cloth or a fine grain mold.

  As described above, in the reduced pressure casting method, a stable reduced pressure state can be maintained by closing the pouring gate or the pouring gate with a suitable non-breathable member or a member having a lower air permeability than the mold after pouring to create a sealed state. It became so. This casting method is effective in general for the reduced pressure casting method, but is particularly effective for the reduced pressure casting method in which only a desired cavity portion is filled with a molten metal and solidified.

  FIG. 37 shows Example 27. In this embodiment, the gas body sucked and discharged from the mold is heat-exchanged by the heat exchanging device 72 and / or supplied to the raw material preheating device 71 using the means 21 to effectively recover the heat of the molten metal. A casting system to be used will be described. The basic configuration of the mold, the casting frame, and the decompression means is the same as that of the twenty-third embodiment.

Conventionally, in the casting method in general, the poured molten metal gives the heat to the mold to solidify, and finally the heat remaining in the molten metal and the heat of the mold are cooled by air or water. Therefore, the amount of heat required for dissolution is dissipated in the air without being recovered at all. In other words, the energy recovery rate in casting is almost zero.

  In the present embodiment, as shown in FIG. 37, the gas body sucked and discharged by the suction / air supply means 61 placed on the upper part of the mold is subjected to heat exchange by the heat exchange device 72 and / or supplied to the raw material preheating device 71. Piping was done to do. As a result, the heat of the molten metal poured into the cavity can be used effectively.

  Conventionally, the vacuum casting method was rarely applied to a high-efficiency continuous line, and the suction vacuum was stopped after pouring even if the vacuum casting method was adopted. Most of the heat recovery was unthinkable. According to the present invention, the reduced-pressure casting method can be easily applied to a high-efficiency continuous line, and cooling control after pouring can be performed. Through this, the heat of the molten metal can be recovered.

As described above, the casting system of the present invention, combined with the above-described high-accuracy decompression control and cooling control, provides a great effect in terms of recovering the heat energy of the molten metal. A vacuum casting method was provided.

The ability to recover the heat of the molten metal is one of the major innovations for a foundry in the 21st century, where energy saving and CO ₂ reduction are required on a global scale.

  A twenty-eighth embodiment is shown in FIG. In the present embodiment, a decompression casting apparatus for decompression during pouring and cooling after pouring will be described using means 22.

  In this embodiment, first, a plurality of decompression boxes 28 having open ends 62 that are brought into contact with the mold outer surface 26 are attached to the lifting means 19 that moves up and down in a direction perpendicular to the mold outer surface 26. The plurality of decompression boxes 28 are connected to each other on the side surface so as to cover the entire surface of the single mold outer surface 26 except the gate portion 15. That is, one mold outer surface 26 is virtually divided into a plurality of mold segments so that suction or air supply can be performed from each part.

  Next, the plurality of decompression boxes 28 are provided with a suction port 31 and an air supply port 32 on the opposite side of the opening end 62, and these serve as a suction chamber 63 provided at the upper part of the plurality of decompression boxes 28 and an air supply port. Each chamber communicates with each other. The suction port 31 communicates directly with the suction chamber 63, but the air supply port 32 communicates with the air supply chamber 64 through a communication pipe 65 that passes through the suction chamber 63.

  Further, in the suction chamber 63 and the air supply chamber 64, a suction flow rate control means 29 and an air supply flow rate control means 33 for individually controlling the suction amount and the air supply amount are provided in the freely raising and lowering means 66 by the mechanism of the pressing valve. ing. The suction chamber 63 communicates with the decompression device, and the air supply chamber 64 communicates with the air compression device. The suction flow rate control means 29 and the air supply flow rate control means 33 are not necessarily limited to those of the pressing valve mechanism shown in the present embodiment, and any control means has the same operation and effect.

  The operation and effect of the apparatus will be described with this configuration. The plurality of decompression boxes 28 are arranged so as to cover one mold outer surface 26 and are placed in contact with the mold outer surface 26 to perform decompression. At that time, a plurality of ventilation holes 27 are provided at selected positions in the mold, and the flow rate control means 29 and 33 control the suction flow rate and the air flow rate of each pressure reduction box 28 so as to obtain a predetermined pressure reduction distribution. Control.

  Some of the plurality of decompression boxes 28 are brought into contact with a portion having no vent hole, but suction or air supply can be performed on the portion as necessary. This is an effect of connecting the plurality of decompression boxes 28 to cover the outer surface 26 of the mold.

  In the case of decompression at the time of pouring, suction is mainly used, and air supply is supplementarily used for a site where the degree of decompression is to be lowered. Also, in cooling after pouring, a combination of intake air and air supply is used. The cooling effect is greater when air is supplied to a portion where particularly strong cooling is desired.

  A configuration similar to that of this apparatus has already been shown in the seventh embodiment. In the seventh embodiment, the suction and air flow control means are not provided with the suction chamber 63 and the air supply chamber 64 as in this embodiment, but are directly provided in the suction port and the air supply hole of each decompression box. The operation and effect of the suction / air supply device of the seventh embodiment are exactly the same as those of the present embodiment. Further, as in the fifth embodiment, the suction pressure can be reduced only by the intake port without providing the air supply port.

  Further, in this embodiment, a plurality of decompression boxes are connected on the side surface so as to cover the outer surface of the mold. However, as shown in the embodiment 11, they can be used as a plurality of decompression boxes separated without being connected. In this case, a plurality of decompression boxes are brought into contact with a plurality of vent holes provided on the outer surface of the mold to perform suction or air supply.

In this case, since the number of decompression boxes for suction or air supply is small, the overall control accuracy of the suction or air supply is slightly inferior to the present embodiment, but the position, size, depth, etc. of the vent holes are appropriate. Thus, substantially the same pressure reduction and cooling effects can be obtained.

  As described above, highly accurate pressure reduction control and cooling control can be performed by the suction / air supply device of the present embodiment. This apparatus is one of the basic elements of the highly accurate vacuum casting method of the present invention.

  FIG. 39 shows Example 29. In the present embodiment, description will be given of a reduced pressure casting apparatus using the means 23, in which the positions of a plurality of reduced pressure boxes can be freely changed in a plane parallel to the outer surface of the mold in the reduced pressure casting apparatus shown in the embodiment 28. .

  In this embodiment, a plurality of decompression boxes are used separately, and a plane parallel to the outer surface of the mold so that the position of each decompression box can abut against a plurality of vent holes provided in the mold. Can be changed freely.

  That is, as shown in FIG. 39, four vertical beams 67 are placed on two horizontal beams 66, and each vertical beam 67 can move freely in the X direction 88 on the horizontal beam 66. did. Further, the four decompression boxes 28 are mounted on the stringer 67 and are configured to be freely movable in the Y direction 89 along the stringer 67.

As a result, the four decompression boxes 28 can be positioned freely in the X and Y directions, and can easily be placed in contact with each other regardless of the position of the plurality of vent holes provided in the mold. However, the means for moving the decompression box is not limited to the means using the horizontal and vertical girders shown in this embodiment, and the operation and effect are the same as long as the means can move freely in the XY directions. .

It is a figure which shows Example 1 of this invention. It is a figure which shows Example 2 of this invention. It is a figure which shows Example 3 of this invention. It is a figure which shows Example 4 of this invention. It is a figure which shows Example 5 of this invention. It is a figure which shows Example 6 of this invention. It is a figure which shows Example 7 of this invention. It is a figure which shows the segment of multiple inclusions of Example 7 of this invention. It is a figure which shows Example 8 of this invention. It is a figure which shows the state in the pouring of Example 9 of this invention. It is a figure which shows the state after pouring of Example 9 of this invention. It is a figure which shows the state in the pouring of Example 10 of this invention. It is a figure which shows the state after the pouring of Example 10 of this invention. It is a figure which shows the state in the pouring of Example 11 of this invention. It is a figure which shows the state after the pouring of Example 11 of this invention. It is a figure which shows the state in the pouring of Example 12 of this invention. It is a figure which shows the state after the pouring of Example 12 of this invention. It is a figure which shows the state in the pouring of Example 13 of this invention. It is a figure which shows the state after the pouring of Example 13 of this invention. It is a figure which shows the state in the pouring of Example 14 of this invention. It is a figure which shows the state after the pouring of Example 14 of this invention. It is a figure which shows the state in the pouring of Example 15 of this invention. It is a figure which shows the state after the pouring of Example 15 of this invention. It is a figure which shows Example 16 of this invention. It is a figure which shows Example 17 of this invention. It is a figure which shows the state in the pouring of Example 18 of this invention. It is a figure which shows the state after the pouring of Example 18 of this invention. It is a figure which shows Example 19 of this invention. It is a figure which shows Example 20 of this invention. It is a figure which shows Example 21 of this invention. It is a figure which shows Example 22 of this invention. It is a figure which shows Example 23 of this invention. It is a figure which shows Example 24 of this invention. It is a figure which shows the cooling curve of Example 25 of this invention. It is a figure which shows the solidification structure | tissue of Example 25 of this invention. It is a figure which shows Example 26 of this invention. It is a figure which shows Example 27 of this invention. It is a figure which shows Example 28 of this invention. It is a figure which shows Example 29 of this invention. It is a figure which shows the whole vacuum casting method using the airtight container of a prior art. It is a figure which shows the partial pressure reduction casting method using the void | hole part of a prior art.

Explanation of symbols

1 Casting frame 2 Upper frame 3 Lower frame 4 Mold 5 Upper mold 6 Lower mold 7 Air seal member (upper)
8 Air seal member (middle)
9 Air seal member (top)
DESCRIPTION OF SYMBOLS 10 Surface plate 11 Cavity 12 Product part 13 Feeding part 14 Runway part 15 Pouring part 16 Depressurizing hood 17 Suction hole 18 Suction pipe 19 Lifting means 20 Packing 21 Pouring port 22 Foamed resin 23 Molten metal 24 Weight 25 Vinyl 26 Outside mold Surface 27 Ventilation hole 28 Decompression box 29 Suction flow control means 30 Airtight hood 31 Suction port 32 Air supply port 33 Air supply flow control means 34 Mold segment 35 Desired cavity portion 36 Inlet port to desired cavity portion 37 Desired Uppermost part of cavity part 38 Other cavity part 39 Boundary part 40 Horizontally extending ventilation hole 41 Vertically extending ventilation hole 42 Mold upper surface 43 Mold transfer tool 44 Clamp member 45 Mold 46 Perforated hole 47 Vent 48 Airtight container 49 Recessed part 50 Foamed resin as ventilation sealing member 51 Steel plate as a sealing member 52 Shell piece as a runner blocking member 53 Sealing blocking member 54 Cooling hole 55 Core baseboard 56 Mold mating surface 57 Air supply hole communicating with the baseboard 58 Communication with mating surface Air supply hole 59 Air supply hole 60 Air supply pipe 61 Suction / air supply means 62 Open end 63 Suction chamber 64 Air supply chamber 65 Communication pipe 66 Elevating / lowering means 67 Horizontal girder 68 Vertical girder 69 Pressure reducing device 70 Air compression device 71 Raw material preheating device 72 Heat Exchanger 73 Hermetic Cover Material 74 Hot Water or Spout 75 Hole Part 76 Core 77 Filter 78 Virtual Mold Dividing Line 79 Flow of Suctioned and Discharged Gas Body 80 Flow of Compressed Air 81 Flow of Control Signal 82 Crystalline temperature line 83 Eutectoid transformation region 84 Natural cooling curve 85 Control cooling curve 86 Metal structure when natural cooling 87 Metal structure when controlled cooling 88 X direction 8 Y direction 90 Lifting direction of lifting means 91 Data signal flow 92 Non-breathable member S Segment with strong decompression M Segment with moderate decompression W Segment with weak decompression E Cooling rate F Distance from inner surface of mold frame ML Mold VB decompression box CM air supply flow rate / temperature measurement means CC air supply flow rate control means CE air compressor VM suction flow rate / temperature control means VC suction flow control means VE pressure reduction device CL calculation means TP temperature (° C.)
TM Time X1, X2, X3, X4 X direction division of mold Y1, Y2, Y3, Y4 Y direction division of mold

Claims (11)

  In a casting method in which a molten metal having a specific weight γ is gravity poured into a gas-permeable mold, the degree of vacuum at a desired cavity portion to be filled with at least the molten metal that is a part of the cavity of the gas-permeable mold is set to the desired value. A negative pressure state having a value equal to or greater than the absolute value of the molten metal static pressure γH determined by the height H from the melt inlet to the uppermost portion of the desired cavity portion, and the desired cavity portion A molten metal having a volume substantially equal to the volume is poured by gravity, the molten metal poured by gravity is filled only in the desired cavity portion, and the desired cavity is introduced from an inlet of the molten metal to the desired cavity portion. A vacuum casting method characterized in that solidification is performed while maintaining a height H up to the top of the part.   2. The vacuum casting method according to claim 1, wherein the degree of pressure reduction of a desired cavity portion to be filled with the molten metal is a negative pressure state having a value equal to or larger than an absolute value of the molten metal static pressure γH, and pressure reduction of other cavity portions. A vacuum casting method characterized by a higher temperature.   In a casting method in which a molten metal having a specific weight γ is gravity poured into a gas-permeable mold, a molten metal having a volume substantially equal to the volume of a desired cavity portion to be filled with the molten metal that is a part of the cavity of the gas-permeable mold. After the start of pouring, the degree of vacuum of the desired cavity portion to be filled with at least the molten metal among the cavities of the breathable mold is set from the inlet of the melt to the desired cavity portion. A negative pressure state equal to or higher than the absolute value of the molten metal static pressure γH determined by the height H up to the uppermost part is filled, and the molten metal poured into the gravity is filled only in the desired cavity portion, and the desired cavity portion A vacuum casting method characterized in that solidification is performed while maintaining a height H from the inlet of the molten metal to the uppermost part of the desired cavity portion.   In the vacuum casting method according to any one of claims 1 to 3, a plurality of vent holes having different diameters and / or depths from the outer surface toward the inside of the mold are provided on at least one outer surface of the breathable mold. Depressurization from the outer surface of the breathable mold to form partial decompression zones around the plurality of vent holes in the mold, and create a predetermined decompression distribution in the cavity of the breathable mold to inject molten metal. A vacuum casting method characterized by hot water.   The reduced pressure casting method according to any one of claims 1 to 3, wherein a plurality of ventilation holes from the outer surface toward the inside of the mold are provided on at least one outer surface of the breathable mold, and the plurality of ventilation holes are individually provided. A partial decompression zone is formed around each of the plurality of appropriate air holes in the mold by suction or air supply to the mold, and a predetermined decompression distribution is created in the cavity of the air-permeable mold to pour the molten metal. This is the Shosho casting method.   The reduced pressure casting method according to any one of claims 1 to 3, wherein a plurality of ventilation holes from the outer surface toward the inside of the mold are provided in at least one outer surface of the breathable mold, and the entire outer surface of the breathable mold is formed. Alternatively, a part is virtually divided into a plurality of mold segments, and the plurality of mold segments are individually sucked or supplied to form partial decompression zones around the plurality of vent holes, respectively, and the breathable mold A vacuum casting method characterized by creating a predetermined reduced pressure distribution in the cavity of the metal and pouring the molten metal.   7. The reduced-pressure casting method according to claim 1, wherein an air permeability that is non-breathable or lower than a mold air permeability is provided in the vicinity of a boundary portion between a desired cavity portion to be filled with the molten metal and another cavity portion. A vacuum casting method characterized in that a molten metal is poured while depressurizing a mold by installing a vent sealing member that has a degree and disappears or melts by the heat of the molten metal.   8. The vacuum casting method according to claim 7, wherein after the air sealing member is in contact with the molten metal, the time until disappearance or melting is 2 seconds or more and 5 seconds or less.   9. The vacuum casting method according to claim 1, wherein the molten metal is made of a refractory material having a specific gravity smaller than that of the molten metal in a vicinity of a boundary portion between the desired cavity portion to be filled with the molten metal and another cavity portion. A pressure reducing device characterized in that a member is installed in a concave portion provided in a cavity lower part near the boundary part, and the molten metal blocking member floats by buoyancy after pouring is completed, and the molten metal near the boundary part of the early period is blocked. Casting method.   7. The vacuum casting method according to claim 1, wherein a desired cavity portion to be filled with the molten metal and a recess provided in a cavity lower portion near a boundary portion of the other cavity portion are not vented. A sealing barrier member comprising a gas-permeable sealing member having a permeability lower than that of the mold or the mold and disappearing or melting by the heat of the molten metal and a molten metal blocking member made of a refractory material having a specific gravity smaller than that of the molten metal The Shosho casting method is characterized in that the molten metal is poured while depressurizing the mold by setting up the mold.   The reduced pressure casting method according to any one of claims 1 to 10, wherein a vent hole is formed from an outer surface of the breathable mold toward a boundary portion between a desired cavity portion to be filled with the molten metal and another cavity portion. And / or a cooling hole is provided, and after the pouring is completed, solidification in the vicinity of the boundary portion is promoted by sucking or feeding air from the ventilation hole and / or the cooling hole. Law.