WO2017017863A1

WO2017017863A1 - Cast-iron casting, method for manufacturing cast-iron casting, and equipment for manufacturing cast-iron casting

Info

Publication number: WO2017017863A1
Application number: PCT/JP2015/083213
Authority: WO
Inventors: 大羽　崇文
Original assignee: 新東工業株式会社
Priority date: 2015-07-24
Filing date: 2015-11-26
Publication date: 2017-02-02
Also published as: CN106559990B; RU2710612C2; JP6586994B2; JPWO2017017863A1; US20180369900A1; EP3326733B1; RU2018103953A3; EP3326733A1; EP3326733A4; KR20180034470A; RU2018103953A; CN106559990A

Abstract

[Problem] To provide a cast-iron casting, a method for manufacturing a cast-iron casting, and equipment for manufacturing a cast-iron casting that can implement plating treatment or enameling treatment without defects on the surface of the cast-iron casting regardless of the specifications thereof and without inviting a decrease in productivity and an increase in costs. [Solution] In a method for manufacturing a cast-iron casting, a mold is made by applying a vacuum to mold sand, and a melt is poured into the mold. A vacuum is applied to the inside of the mold until the temperature of a casting formed by this melt falls to or below the A1 transformation temperature. Equipment for manufacturing a cast-iron casting is provided with: at least one mold; a frame feed device that moves the mold; at least one fixed suction device that applies a vacuum to the inside of the mold when the mold is stopped; at least one movable suction device that moves while applying a vacuum to the inside of the mold instead of the fixed suction device when the mold is moved; and a temperature sensor that measures the surface temperature of the casting product.

Description

Cast iron casting, cast iron casting manufacturing method, and cast iron casting manufacturing equipment

The present invention relates to a cast iron casting, a cast iron casting manufacturing method, and a cast iron casting manufacturing facility.

As a technique for imparting corrosion resistance, wear resistance, heat resistance or the like to the surface of a metal product, there are plating treatment and wrinkle treatment. In addition, when plating and glazing are performed on the surface of a cast iron casting, there is a known problem that the presence of graphite and free cementite on the casting surface adversely affects these treatments. Technology or research has been conducted for some time.

Patent Document 1 discloses that after the surface of a steel product is cleaned and activated, plating is performed by applying a catalyst that promotes a reduction reaction.

In Patent Document 2, a pure Fe thin plate is attached to the surface of a mold in contact with a casting, molten spherical graphite cast iron is cast into the mold, and the pure Fe thin plate on the mold surface is melted to form graphite on the surface of the casting. It is disclosed that after forming a hindering surface layer, galvanization is performed.

In Patent Document 3, ultrasonic vibration is applied in a state in which the cast iron material is immersed in the plating solution, the surface of the cast iron material is washed, the graphite existing on the surface is crushed, and dispersed in the plating solution. It is disclosed to form a plating film containing graphite dispersed on its surface.

Non-Patent Document 1 suggests that carbon monoxide and carbon dioxide generated by oxidation of graphite in the vicinity of the casting surface in the glazing treatment on cast iron are the cause of bubble defects.

In Non-Patent Document 2, the metal structure in which defects are generated is graphite that is gradually cooled and enlarged, and conversely, that is rapidly cooled to prevent the growth of graphite. To improve these structures, It is disclosed that it is effective to perform a degassing heat treatment before the soot treatment.

In Non-Patent Document 3, there are many defects in places of coarse graphite structure, places where redebrite is crystallized, places where cementite is decomposed due to temperature rise during the soot treatment and temper carbon is crystallized, To improve this, low carbon saturation prevents the coarsening of graphite and increases the phosphorus content to prevent crystallization of redebrite and suppress the decomposition of cementite during the soot treatment. It is disclosed that by performing a degassing heat treatment on the cast material before the slag treatment, bubble defects are significantly suppressed.

In

Patent Documents

4 and 5, in the production of enameled cast iron, the one in which a graphite-free layer is formed on the cast iron surface structure has few bubble defects, and the cast iron of flake graphite cast iron having a low carbon and high silicon composition has bubble defects. It is disclosed that the occurrence of bubble defects can be reduced by adding titanium even when the composition is low, and the composition is high carbon and low silicon.

From the above contents, it is clear that graphite and free cementite in the vicinity of the casting surface adversely affect the surface of the cast iron casting. And in order to suppress the negative effects of graphite and free cementite, is it possible to remove the graphite by chemically, physically and thermally treating the casting, or to form a coating that does not contain graphite near the casting surface after casting? The casting surface is formed by pouring with a pure Fe thin plate attached to the mold surface in contact with the molten metal to form a graphite-free layer near the casting surface, or by adding an alloy by controlling the chemical composition of the casting. There are methods such as forming a graphite-free layer in the vicinity.

Each method of chemically, physically, and thermally treating a casting to remove graphite and the like requires a separate step of removing the graphite and the like near the casting surface after casting. Moreover, it is necessary to set processing conditions finely according to each casting product. For this reason, productivity is reduced and manufacturing costs are increased. In the method of forming a film that does not contain graphite in the vicinity of the casting surface after casting, the graphite present on the surface of the cast iron material directly under the film exists without being removed. For this reason, the adhesion between the graphite and the plating film is impaired, corrosion occurs from that portion, and the plating film in the vicinity thereof may swell or peel off.

The method of forming a graphite-free layer in the vicinity of the casting surface by pouring with a pure Fe thin plate attached to the mold surface in contact with the molten metal is formed in advance according to the shape of the thin plate, It will be necessary to paste it on. For this reason, the applicable shapes are limited to simple ones, and there is a problem that productivity is reduced by operations such as attaching a thin plate. The method of forming a graphite-free layer near the casting surface by controlling the chemical composition of the casting and adding an alloy limits the application range of the product. Therefore, this method is adopted depending on the required specifications. It is impossible.

On the other hand, in the mold making method in which pouring is performed in a state where the inside of the mold is depressurized using mold sand that does not contain a binder, the metal structure and mechanical properties of the casting produced by creating an air flow near the casting There are known techniques for improving the above. For example, in Patent Document 6, the shielding member is closely attached to the shielding surface of the original shape member, the inside or outside of the shielding member is filled with the heat-resistant particulate matter, and the shielding member is made with a negative pressure on the heat-resistant particulate matter side. In a casting method that adsorbs to the heat-resistant particle material side, then molds the original member to form a cavity, and pours the molten metal into the cavity, the surface layer of the molten metal after the pouring of the molten metal is completed. A casting method is disclosed in which air is introduced into the heat-resistant particles when the solidification starts.

Further, in Patent Document 7, the molten metal is poured into a mold made using dry silica sand, and after the injected molten metal has solidified, air is passed through the dry silica sand surrounding the casting material formed by solidification of the molten metal. A casting method characterized by cooling the casting material is disclosed.

These technologies are intended to solve the problem that heat transfer via air is not performed well in molds that are kept in a reduced pressure state after pouring, and the cooling rate of the molds is significantly slower than other molding methods. Thus, the effect of increasing the cooling rate is obtained by releasing the reduced pressure state around 1200 ° C., which is the solidification temperature of cast iron, and introducing air or compressed air instead. However, all of these methods are intended to prevent crystallization of graphite and crystallize cementite instead, and are not intended for decarburization near the casting surface. Therefore, since there is free cementite that adversely affects the plating process or the glazing process in the vicinity of the casting surface manufactured by such a method, it is good even if the plating process or the glazing process is applied to these casting surfaces. It is clear from the contents of Patent Documents 1 to 5 and Non-Patent Documents 1 to 3 that a film cannot be obtained.

JP-A-8-170178 JP 2001-200350 A JP 2004-143552 A JP 2015-42774 A JP 2015-42775 A JP 58-2224066 A JP-A-63-10062

For the above reasons, all the conventional techniques have various problems. Accordingly, the present invention has been made in view of the above-mentioned problems, and without subjecting the productivity and cost to increase, a plating process or a glazing process having no defects on the surface thereof regardless of the specifications of the cast iron casting. It is an object of the present invention to provide a cast iron casting, a cast iron casting manufacturing method, and a cast iron casting manufacturing facility that can be applied.

In order to solve the above-described problems and achieve the object, the present invention is formed by depressurizing mold sand to form a mold, pouring molten metal into the mold, and the molten metal. comprise the step of temperature of the casting is to reduce the pressure within the mold until the following a ₁ transformation point, and characterized.

The present invention also provides at least one mold, a frame feed device for moving the mold, a mold, in a cast iron casting production facility for producing cast iron casting by pouring molten metal into a mold formed by depressurizing the mold sand. At least one fixed suction device that depressurizes the inside of the mold when stopped, and at least one movable suction device that moves while depressurizing the inside of the mold instead of the fixed suction device when the mold moves. Note until the casting temperature in the mold after the hot water is below the a ₁ transformation point, repeating the stopping and movement by the frame feeder, and wherein.

Further, the present invention provides a casting mold making method involving pouring into the mold the molding sand is molding in vacuo, Note casting temperature in the hot water after the mold continues to reduce the pressure in the mold until the following A ₁ transformation point It is manufactured by this.

According to the present invention, it is possible to oxidize graphite in the vicinity of the casting surface that adversely affects the plating treatment or the glazing treatment and to prevent the generation of free cementite, thereby suppressing defects during the plating treatment or glazing treatment easily and inexpensively. It becomes possible.

Further, according to the present invention, since it is not necessary to control the chemical composition of the casting or add an alloy, it can be applied regardless of the thickness of the casting or the required quality.

It is a schematic diagram which shows the structure of the cast iron casting manufacturing equipment concerning 1st Embodiment. It is a schematic diagram which shows the state after a movable suction apparatus moved following the casting_mold | template sent with a frame feeding apparatus. It is a schematic diagram which shows the state of the fixed suction device and movable suction device immediately after returning to an original position. It is a schematic sectional drawing around the casting_mold | template concerning 2nd Embodiment. It is a schematic sectional drawing around the casting_mold | template concerning 3rd Embodiment.

Exemplary embodiments of a cast iron casting, a cast iron casting production method, and a cast iron casting production facility according to the present invention will be explained below in detail with reference to the accompanying drawings. Method for producing cast iron of the present invention is to molding and vacuum the mold using a molding sand containing no Nebayuizai, after pouring, to a temperature of the casting to be built into the mold falls below the A ₁ transformation point The inside of the mold is continuously decompressed.

The present invention oxidizes graphite and free cementite, which have an adverse effect on plating treatment or flaw treatment, by creating a state in which the inside of the mold continues to be depressurized and air continues to flow on the casting surface. The purpose is to create a layer. For this purpose, it is necessary to keep the state until the eutectoid reaction is completed, that is, the temperature of the A _cm transformation point in the metastable system or the temperature below the A ₁ transformation point in the stable system. In the present invention, the target material is cast iron, and no operation that results in a metastable solidification reaction in the Fe—C binary alloy phase diagram, such as forced quenching, is performed. continue to reduce the pressure in the mold until the following a ₁ transformation point is the reaction completion temperature.

Incidentally, A ₂ transformation point is a magnetic transformation point of Fe, A ₃ transformation point of the crystal structure changes to face-centered cubic lattice from the body-centered cubic lattice, and crystal structure again body-centered cubic lattice of a face-centered cubic lattice the varying a ₄ transformation point, each lower temperatures graphite or eutectic or eutectoid reaction of cementite occurs at. For this reason, it is not sufficient to release the reduced pressure state after the inside of the mold is continuously decompressed until the temperature becomes lower than the respective transformation point.

In the mold making method in which the casting is performed in a state where the inside of the mold using the molding sand containing no binder in the present invention is decompressed, a shielding member adhesion process for closely adhering the shielding member to the surface of the original model board is in close contact. A step of placing the molding frame on the shielding member and filling the molding frame with mold sand not containing a binder, and sealing the upper surface of the molding sand to make the molding frame negative pressure, thereby A process of forming a shielding member by adsorbing to the mold sand side, a process of forming a half mold having a molding surface by releasing the original model board from the shielding member, and molding in the same manner as the half mold The process of forming a casting cavity by matching with one half mold, the process of pouring molten metal (molten metal) into the casting cavity (pouring process), and then releasing the negative pressure state in the molding frame Mold casting and pouring having a process of taking out the casting A process vacuum mold formation method (hereinafter, referred to as "V Process") it is. In addition, a model made of a resin foam is embedded in mold sand that does not contain a binder, and the molded foam is melted while the resin foam is melted in a molded mold by reducing the pressure inside. Also included is the disappearance model casting method.

In the present invention, in order to form a decarburized layer, it is necessary to create a state where air always flows on the casting surface. However, if the reduced pressure of the mold is extremely close to atmospheric pressure, the mold sand falls on the casting surface, so that it is impossible to create a state where air always flows on the casting surface. On the other hand, when the reduced pressure is made extremely close to vacuum, it is possible to create a state in which air always flows on the casting surface, but the molten metal penetrates into the voids between the mold sand grains and causes a significant insertion defect. For this reason, the reduced pressure is preferably between −10 kPa and −70 kPa.

Further, the mold sand in the present invention may be any kind such as dredged sand, olivine sand, chromite sand, zircon sand, and ceramic artificial sand. However, in order to decarburize the vicinity of the casting surface in a reduced pressure state, a material having high air permeability when filled as a mold is suitable, and therefore, a material having a small proportion of particles having a diameter of less than 53 μm in the mold sand is suitable. It is. When the ratio of particles having a diameter of less than 53 μm in the mold sand is excessive, the mold does not have sufficient air permeability, and sufficient air flow does not occur in the vicinity of the casting surface, so that a decarburized layer cannot be formed. Therefore, the ratio of particles having a diameter of less than 53 μm is desirably 10% or less.

After pouring, the time that the temperature of the casting to be built in the mold required until below the A ₁ transformation point, it differs by the mass and thickness of the product. After pouring, the temperature of the casting to be incorporated in the mold in the manufacturing facility of cast iron with a fixed suction device and a movable suction device frame number of required to perform until the following A ₁ transformation point, in the mold can not directly measure the surface temperature of the casting C, for it takes until the temperature of the casting is less than the a ₁ transformation point, it performs casting either or experimentally confirmed by casting simulation on set in advance casting conditions, actually measure the time required until the following a ₁ transformation point, it is necessary to know.

(First embodiment)
Drawing 1 is a mimetic diagram showing the composition of the cast iron casting manufacturing equipment concerning a 1st embodiment.
The cast iron casting manufacturing facility 1 is a facility that manufactures cast iron castings using the V process, and includes a mold 2 that uses mold sand that does not contain a binder, a mold surface plate 3, a frame feeding device 4, and a fixed suction. A device 5 and a movable suction device 6 are provided. Note that the mold 2 is a mold in which a mold is formed from mold sand in a molding frame. Here, FIG. 1 shows the state of the fixed suction device 5 and the movable suction device 6 immediately before the mold 2 moves. While the mold 2 is stopped, the fixed suction device 5 sucks each mold 2 to decompress the inside of the mold 2, and when the mold 2 moves, the fixed suction device 5 is detached, and instead the movable suction device 6 is attached to the mold 2. The mold 2 is suctioned and the inside of the mold 2 is depressurized. Thereafter, the movable suction device 6 moves following the mold 2, and after the movement is completed, the movable suction device 6 is detached. Instead, the fixed suction device 5 comes into close contact with the mold 2 and sucks the mold 2, thereby moving the mold 2 into the mold 2. The pressure is reduced. These operations, after pouring, the temperature of the casting to be built into the mold only a fraction number frame required to perform until the following A ₁ transformation point, has at least fixed suction device 5 and the movable suction unit 6 .

In FIG. 1, it is assumed that the mold 2 moves from the right side to the left side of the drawing, the right end mold 2 is in a state immediately after pouring, and the left end mold 2 has a temperature of a casting incorporated in the mold after pouring. A It is in the state where it was decompressed until it became below ₁ transformation point. In order to move the mold 2 to the right end mold 2 after pouring, the frame feeding device 4 is first brought into close contact with the mold surface plate 3 on which both ends of the mold 2 are placed, and the mold surface plate 3 is fixed from both sides. . Further, the mold 2 is kept in a reduced pressure state when the fixed suction device 5 communicating with the pipe 7 is in close contact with a suction source (not shown). Further, the movable suction device 6 communicating with the hose 8 that freely moves to a suction source (not shown) is brought into close contact with the mold 2 to depressurize the mold 2 and at the same time, the fixed suction device 5 is detached.

Next, the frame feeding device 4 operates to move the mold 2 (molding frame) placed on the mold surface plate 3. FIG. 2 is a schematic diagram showing a state after the movable suction device 6 has moved following the mold 2 fed by the frame feeding device 4. Since the movable suction device 6 is connected to the frame feeding device 4 by a connection mechanism (not shown), the movable suction device 6 moves following the operation of the frame feeding device 4. Thus, the mold 2 is kept in a reduced pressure state by the movable suction device 6 even during movement.

Next, when the movement for one frame is completed, the leftmost mold 2 is transported to a secondary cooling step or a frame opening step, which is the next step, by a transport device not shown. In addition, a new non-poured frame is conveyed from the molding step, which is a previous step, to the right end by a conveying device having a suction device (not shown). Further, the fixed suction device 5 is brought into close contact with the mold 2 to depressurize the mold 2 and at the same time, the movable suction device 6 is detached. In this way, the reduced pressure state of the mold 2 is maintained by the fixed suction device 5. After that, the close contact of the mold surface plate 3 by the frame feeding device 4 is released, and the movable suction device 6 also moves and returns to the original position following the return of the frame feeding device 4 to the original position. FIG. 3 is a schematic diagram showing the state of the fixed suction device 5 and the movable suction device 6 immediately after returning to the original position.

When returning to the original position, the number of the molds 2 placed on the series of mold surface plates 3 closely fixed by the frame feeding device 4 is determined by the cycle time, which is the time required to mold the mold, temperature of the casting to be incorporated in the mold is determined by the time until the following a ₁ transformation point. For example, in a cycle time of 3 minutes / frame, after pouring obtained do cast to or trial was confirmed by casting the simulation, the time until the temperature of the casting to be built into the mold falls below the A ₁ transformation point 15 if assumed to be minute, after pouring, the number of mold 2 in which the temperature of the casting to be built in the mold should be kept in a reduced pressure state until the following a ₁ transformation point, that 15 ÷ 3 = 5 frame become.

In FIG. 3, the mold 2 placed on a series of mold surface plates 3 tightly fixed by the frame feeding device 4 is cooled while being kept in a reduced pressure state by the fixed suction device 5 and the movable suction device 6. Not limited to this. For example, after pouring, as described above, when the temperature of the casting to be built in the mold number of the mold 2 that must be kept in a reduced pressure state until the following A ₁ transformation point to a 5 frame, 6 frame onwards As a secondary cooling step, the mold may be moved by the frame feeding device 5 without being sucked.

(Second Embodiment)
2nd Embodiment is related with the structure around the casting_mold | template 2 in the cast iron casting manufacturing equipment 1 of 1st Embodiment. A second embodiment will be described with reference to the accompanying drawings. Of the configuration of the cast iron casting manufacturing facility according to the present embodiment, a portion different from the first embodiment will be described. The other parts are the same as those in the first embodiment, so the description is omitted with reference to the above description.

The cast iron casting manufacturing facility 1 includes a mold 2, a mold surface plate 3, a frame feeding device 4, a fixed suction device 5, and a movable suction device 6. FIG. 4 is a schematic cross-sectional view around the mold 2 according to the second embodiment. FIG. 4 includes a mold 2 that uses a molding sand 9 that does not contain a binder, a fixed suction device 5, a temperature sensor 10, and a control device 11, and the temperature sensor 10 is a casting C in the mold 2. The V process mold in a state of being inserted into and contacted with the thickest portion of is shown. The temperature sensor 10 is waiting in advance immediately above the thickest portion of the casting C outside the mold 2. Since the standby position of the temperature sensor 10 varies depending on the product, the horizontal position and the height from the reference plane of each thickest portion are stored in a storage device (not shown) in advance, and the information is stored in the information. Based on this, the control device 11 moves the temperature sensor 10. Further, the mold 2 communicates with a suction source (not shown) through a fixed suction device 5 and a pipe 7.

When information indicating that pouring has been completed is input to the control device 11, the temperature sensor 10 is inserted into contact with the thickest portion of the casting C in the mold 2 by an insertion / removal device (not shown). . Thereby, the temperature information of the casting C surface is input to the control device 11.

When the control unit 11 with information from the temperature sensor 10 is the product surface temperature of the casting C senses that it has reached below the A ₁ transformation point, the control unit 11 a stationary suction device 5 is detached from the mold 2, a reduced pressure To release. Next, the temperature sensor 10 is removed by an insertion / removal device (not shown).

In addition, there is no restriction | limiting in particular in the means to input the information that pouring was completed to the control apparatus 11, for example, the operator pushed the pushbutton connected to the control apparatus 11 after pouring completion, and pouring was completed. Note that the temperature of the upper surface of the frying is measured with a non-contact thermometer, the temperature information of the upper surface of the frying is monitored by the control device 11, and the temperature of the upper surface of the frying has risen to the molten metal temperature. The temperature sensor 10 may be inserted and contacted when it is determined that the hot water is completed.

(Third embodiment)
3rd Embodiment is related with the structure around the casting_mold | template 2 in the cast iron casting manufacturing equipment 1 of 1st Embodiment similarly to 2nd Embodiment. A third embodiment will be described with reference to the accompanying drawings. Of the configuration of the cast iron casting manufacturing facility according to the present embodiment, a portion different from the second embodiment will be described. The other parts are the same as those in the second embodiment, so the description is omitted with reference to the above description.

The cast iron casting manufacturing facility 1 includes a mold 2, a mold surface plate 3, a frame feeding device 4, a fixed suction device 5, and a movable suction device 6. FIG. 5 is a schematic cross-sectional view around the mold 2 according to the third embodiment. FIG. 5 is composed of a mold 2 using a molding sand 9 that does not contain a binder, a temperature sensor 10, a control device 11, a warning light 12, and a two-way valve 13, and the temperature sensor 10 is used as a mold. 2 shows a V process mold in a state where it is inserted into and contacted with the thickest portion of the casting C in 2. FIG. Similar to the second embodiment, the temperature sensor 10 is waiting in advance immediately above the thickest portion of the casting C outside the mold 2. Since the standby position of the temperature sensor 10 varies depending on the product, the horizontal position and the height from the reference plane of each thickest portion are stored in a storage device (not shown) in advance, and the information is stored in the information. Based on this, the control device 11 moves the temperature sensor 10. The mold 2 is connected to a two-way valve 13 by an easily detachable hose 8, and the two-way valve 13 communicates with a suction source (not shown) via a pipe 7.

As in the second embodiment, when information indicating that pouring has been completed is input to the control device 11, temperature detection is performed at the thickest portion of the casting C in the mold by an insertion / removal device (not shown). The container 10 is brought into contact with insertion. Thereby, the temperature information of the casting C surface is input to the control device 11.

When the control unit 11 with information from the temperature sensor 10 is the product surface temperature of the casting C senses that it has reached below the A ₁ transformation point, the controller 11 lights the warning lamp 12. When the operator confirms that the warning lamp 12 is turned on, the two-way valve 13 is manually closed, and the hose 8 is removed from the mold 2 to release the reduced pressure state. Next, the temperature sensor 10 is removed by an insertion / removal device (not shown).

The means for inputting information that pouring is completed to the control device 11 is not particularly limited as in the second embodiment. For example, a push button that is connected to the control device 11 by the operator after pouring is completed. It is possible to input information that the pouring has been completed by pressing, measure the temperature of the upper surface of the frying with a non-contact thermometer, monitor the temperature information of the upper surface of the frying with the control device 11, and the upper surface of the frying is molten. The temperature sensor 10 may be inserted and contacted by determining that pouring has been completed when the temperature has risen.

In each of the first to third embodiments, an example in the V process has been shown. However, the configuration and operation of the equipment are the same even in the disappearance model casting method.

In the first to third embodiments, the molding sand containing no binder is used. However, as long as it is possible to create a state in which the air continues to flow on the casting surface in a state where the inside of the mold is decompressed, A trace amount of binder may be contained in the mold sand.

As is apparent from the above description, the present invention is a method for producing a cast iron casting in which the surface of the casting is subjected to plating treatment or glazing treatment after casting, in which the molding sand containing no binder is used and the inside of the casting mold is decompressed. in using the casting mold making method involving pouring, after pouring, the temperature of the casting to be built into the mold continues to reduce the pressure in the mold until the following a ₁ transformation point, always casting surface state through which air flows Become. Therefore, in the casting in a high temperature state, graphite existing near the surface is quickly oxidized, so that a decarburized layer is formed near the casting surface. On the other hand, since the mold is in a depressurized state, free cementite produced by rapid cooling does not occur. Therefore, an abnormal structure in the vicinity of the casting surface that adversely affects the plating process and the wrinkle process is not formed, and it is clear that the effect of the present invention is very large for those skilled in the art.

DESCRIPTION OF SYMBOLS 1 Cast iron casting production equipment 2 Mold 3 Mold surface plate 4 Frame feeder 5 Fixed suction device 6 Movable suction device 7 Piping 8 Hose 9 Mold sand 10 Temperature sensor 11 Controller 12 Warning light 13 Two-way valve

Claims

A step of molding the mold by depressurizing the mold sand;
A process of pouring molten metal into the mold,
Method for producing cast iron, characterized in, that including a step of depressurizing the inside mold to a temperature of the casting formed by the molten metal is below the A 1 transformation point.
2. The method for producing a cast iron casting according to claim 1, wherein the molding sand does not contain a binder.
The method for producing a cast iron casting according to claim 1 or 2, wherein the pressure in the mold is maintained between -10 kPa and -70 kPa.
The method for producing a cast iron casting according to any one of claims 1 to 3, wherein a ratio of particles having a diameter of less than 53 µm in the mold sand not including the binder is 10% or less.
In a cast iron casting production facility for producing cast iron castings by pouring molten metal into a mold formed by reducing the pressure of the mold sand,
At least one mold;
A frame feeder for moving the mold;
At least one fixed suction device for decompressing the inside of the mold when the mold is stopped;
At least one movable suction device that moves while reducing the pressure inside the mold instead of the fixed suction device when the mold is moved,
The mold, cast until casting temperature in the mold after the hot water is below the A 1 transformation point, repeating the stopping and movement by the frame feeder, iron casting manufacturing facility according to claim.
There are a plurality of the molds,
The frame feeder moves a plurality of the molds simultaneously,
6. The cast iron casting manufacturing facility according to claim 5, wherein the fixed suction device and the movable suction device are provided in at least the same number as the mold.
A temperature sensor for measuring the product surface temperature of the casting,
When the product surface temperature of the casting has reached below the A 1 transformation point, wherein, further, comprising a control device, the controlling to the fixed suction device releases the vacuum state is disengaged from the mold The cast iron casting manufacturing facility according to claim 5 or 6.
8. The cast iron casting manufacturing facility according to claim 7, wherein the temperature sensor is inserted into the mold so as to come into contact with the thickest portion of the casting in the mold.
The cast iron casting manufacturing facility according to claim 7 or 8, further comprising a warning light that is turned on according to an instruction from the control device.
In casting mold making method involving pouring into the mold the molding sand is molding under reduced pressure, the casting temperature inside the mold after pouring is produced by reducing the pressure within the mold until the following A 1 transformation point Cast iron casting.