JP2015024442A - Casting product manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a casting product by gravity-pouring molten metal into a permeable mold, in which a sound casting product is manufactured with a high pouring yield rate and less generation of non-filling part and gas entrainment.SOLUTION: A casting product manufacturing method is a method in which a casting product is manufactured by gravity-pouring molten metal into a permeable mold, and includes a pouring step in which molten metal of a volume smaller than a whole of a cavity constituted of a molten metal supply passage and a product part is poured, and a filling step in which the poured molten metal is filled to a desired cavity part by gas pressure supplied from a sprue part. In the filling step, the molten metal remaining at the molten metal supply passage has a shape satisfying Equation 1. Equation 1: (D-(H/tanθ)/2)/H≥H, where D is a cross section area of the molten metal in the longitudinal direction, H is a height of the molten metal supply passage, and θ is a crossing angle (°) between the edge surface of the molten metal and the bottom surface of the molten metal supply passage.

Description

  The present invention relates to a casting article manufacturing method in which a molten metal is gravity poured into a breathable mold to manufacture a casting article.

  For the production of cast articles in gravity pouring, a mold formed using sand particles, which is a breathable mold, that is, a so-called sand mold is most commonly used. When such a breathable mold is used, when the molten metal is filled into the cavity of a specific shape, the remaining gas (generally air) will be pushed out from the cavity surface, and the molten metal (hereinafter, It is also called molten metal), and a casting that is substantially the same as the cavity can be obtained. The mold cavity generally has a sprue part, a runner part, a feeder part, and a product part. The molten metal is supplied in this order, and a melt head height sufficient to fill the product part is formed in the spout part. The pouring is finished.

  The cast article thus solidified has a form in which the gate, runner, feeder, and product are connected as a casting. Here, the feeder part is a cavity that is set for the health of the product and is not an unnecessary part, but the sprue part and the runner part are only the route of the molten metal to the product part and are essentially unnecessary. It is an important part. Therefore, the injection yield cannot be significantly improved as long as the molten metal is solidified in the gate or runner. In addition, if the casting is formed by connecting unnecessary parts, a considerable man-hour is required for sorting the product part and the unnecessary part in the separation process of the product part, which is a subsequent process, and the production efficiency is lowered. Therefore, in gravity pouring, the presence of a sprue part or a runner part as a casting is a big problem.

  In order to solve the above problems, Japanese Patent No. 4150764 (Patent Document 1) fills only a desired cavity portion, which is a part of a cavity of a gas-permeable mold, with a molten metal, and thus the entire volume of the mold cavity. A molten metal having a volume substantially equal to a smaller desired cavity portion is poured, and before the poured molten metal is filled into the desired cavity portion, compressed gas is supplied from the gate to the desired cavity portion. Disclosed is a method for producing a cast article that is filled and solidified with a molten metal, and this method reduces the supply of molten metal to the sprue part and runner part unnecessary for the cast article as a product, and achieves a high injection yield. It describes that it is possible to establish a casting method and to greatly simplify the post-process after dismantling. This method will be described in detail below.

  The method described in Patent Document 1 is a 1 m pouring process of a molten metal (hereinafter sometimes simply referred to as a molten metal) 10 into a gas-permeable mold (hereinafter sometimes referred to as a mold) 10 (see FIG. 1). ), And a filling step (see FIGS. 2 and 3) in a desired cavity portion of the molten metal 1 m poured into the mold 10. The air-permeable mold 10 is, for example, a sand mold, and as shown in FIG. 1, an upper mold 1d formed in the upper frame 1a and a lower mold 1e formed in the lower frame 1b are formed on the surface plate 1c. The molds are placed after being matched. The air-permeable mold 10 has a mold cavity 1f (hereinafter sometimes simply referred to as a cavity 1f) composed of a sprue part 1g, a molten metal supply passage (runner part) 1h, and a product part 1j. (See Figures 1-3).

  As shown in FIG. 1, from the pouring ladle 1L, molten metal having a volume substantially equal to a desired cavity portion 1k (corresponding to the product portion 1j) to be filled with molten metal is poured into the mold 10. Since the molten molten metal 1m has almost the same volume as the cavity of the product part 1j, all of the cavities 1f cannot be filled, and a part of the molten metal stays at the bottom of the product part 1j and a part of the molten metal stays in the molten metal supply passage 1h ( Pouring process). Next, as shown in FIG. 2, the gas 1p compressed by the compression device (not shown) is supplied from the upper part of the gate 1g through the air supply means 1q, and is stagnated in the molten metal supply passage 1h by the pressure. 1m of molten metal is filled into the product part 1j (filling process). Since the amount of molten metal poured in the pouring step is substantially equal to the volume of the product part 1j, the molten metal 1m is finally filled only with the product part 1j which is the desired cavity part 1k. Thereafter, in this state, the molten metal 1m filled in the product part 1j is solidified.

  According to Patent Document 1, in the conventional casting method, all the mold cavities are filled with the molten metal. By using this method, only the desired cavity portion can be filled with the molten metal and solidified. Therefore, the injection yield (product part weight / total injection weight) is greatly improved, and it is only necessary to take out the product part filled with the molten metal when releasing the frame after solidification. Yes.

  However, although the method for manufacturing a cast article described in Patent Document 1 can achieve a high pouring yield, as shown in FIG. 3, non-casting that causes surface defects in the obtained cast product. It has been found that there is a case where a sound casting product may not be obtained due to the filling part F and gas entrainment I causing internal defects. Therefore, development of a pouring method and a filling method for molten metal that does not cause the above-described defects is desired.

Japanese Patent No. 4150764

  Therefore, an object of the present invention is to achieve a casting article manufacturing method in which a molten metal is poured into a gas-permeable mold by gravity to produce a casting article, while achieving a high injection yield as high as that of the method described in Patent Document 1. An object of the present invention is to provide a method for producing a cast article that can obtain a sounder cast product in which the occurrence of a filling portion and gas entrainment is suppressed.

  As a result of diligent research in view of the above object, the present inventors poured a molten metal having a volume smaller than the whole cavity of the breathable mold into the breathable mold, and then poured the gas by injecting gas. In a method for manufacturing a cast article by filling a desired cavity portion, which is a part of a cavity of the breathable mold, with a molten metal, the shape of the molten metal remaining in the molten metal supply passage after filling is regulated to a specific range. As a result, it was found that a cast product in which the occurrence of unfilled portions and gas entrainment was suppressed was obtained, and the present invention was conceived.

That is, the method of the present invention for producing a cast article is a method for producing a cast article in which a molten metal is gravity poured into a breathable mold to produce a cast article,
The cavity of the breathable mold has at least a molten metal supply passage that opens to the outside of the breathable mold, and a product portion that is connected to the molten metal supply passage,
A pouring step of pouring a molten metal having a volume smaller than the entire cavity of the breathable mold in order to fill the desired cavity portion including the product portion with the molten metal,
After the start of the pouring process, before the poured molten metal is filled into the desired cavity portion, filling is performed by supplying gas from the pouring portion and filling the desired cavity portion with the molten metal by the gas pressure. A process,
The molten metal remaining in the molten metal supply passage in the filling step is
Formula 1: (D- (H ² / tanθ) / 2) / H ≧ H
[However, D is the longitudinal sectional area of the molten metal remaining in the molten metal supply passage in the filling step, H is the height of the molten metal supply passage, θ is the end surface of the molten metal remaining in the molten metal supply passage and the molten metal supply in the filling step. This is the angle of intersection (°) with the bottom of the passage, and 10 ° ≦ θ ≦ 80 °. ]
It has the shape which satisfies these.

  According to the present invention, it is possible to obtain a more healthy casting product in which a high injection yield equivalent to that of Patent Document 1 can be realized and generation of unfilled portions and gas entrainment is suppressed.

In the manufacturing method of the casting article of patent document 1, it is a schematic cross section which shows the state immediately after pouring a molten metal into a casting_mold | template. In the manufacturing method of the casting article of patent document 1, it is a schematic cross section which shows the state which filled the molten metal into the desired cavity part with the gas pressure. FIG. 3 is a schematic cross-sectional view showing an enlarged portion A of FIG. In embodiment of the manufacturing method of this invention, it is a schematic cross section which shows the state immediately after pouring a molten metal into a casting_mold | template. In embodiment of the manufacturing method of this invention, it is a schematic cross section which shows the state which filled the molten metal into the desired cavity part with the gas pressure. FIG. 6 is a schematic cross-sectional view showing an E portion in FIG. 5 in an enlarged manner. FIG. 7 is a schematic cross-sectional view showing an enlarged M part in FIG. FIG. 8 is a cross-sectional view taken along the line O-O in FIG. FIG. 9 is a cross-sectional view of a molten metal supply passage having a different form from FIG. 8 (a). FIG. 9 is a cross-sectional view of a molten metal supply passage having a different form from FIG. 8 (a). FIG. 7 is a perspective view showing the molten metal remaining in the molten metal supply passage of part M in FIG. 6 as seen through the molten metal supply passage.

  In order to achieve the above object, the present inventors have studied various things, and the phenomenon that occurs in the manufacturing method of the cast article of Patent Document 1 described in the section of the background art, that is, the unfilled portion and the gas entrainment are as follows. Estimated to be caused by a point. Hereinafter, the presumed cause will be described with reference to FIG. In the following description, the case where the desired cavity portion 1k is the product portion 1j will be described as an example. However, the above phenomenon similarly occurs even when the desired cavity portion includes a molten metal supply passage or a feeder portion. In the case where a non-filling part or gas entrainment occurs in the feeder part or the molten metal supply passage, for example, there is little possibility of hindering the flow of the molten metal.

  The first presumed cause will be described. In the pouring process, a molten metal having a volume approximately equal to the desired cavity portion 1k is poured into the mold 10 as the target pouring amount. For example, the measurement error of the molten metal weight in the pouring device or the error in the operation amount of the pouring ladle As a result, the actual pouring amount varies between positive and negative with respect to the target pouring amount. When the actual pouring amount is negative with respect to the target pouring amount, the product portion 1j (equivalent to the desired cavity portion 1k here) should be filled with 1 m of molten metal (hereinafter, this time is referred to as `` filling process In some cases, it may be referred to as “the end”.) In some cases, the molten metal 1 m may not completely fill the product portion 1 j. For this reason, a non-filling portion F is formed in a concave shape on the left side (product part 1j side) of the connecting end 1w with the product part 1j of the molten metal supply passage 1h, and the cast article in which the molten metal 1m can be solidified. It is presumed that a defect remains on the surface. In addition, the compressed gas (indicated by arrow B) supplied to the molten metal supply passage 1h in a pressurized state partially flows out of the molten metal supply passage 1h through the breathable mold 10 (flow indicated by arrow C). The compressed gas in the molten metal supply passage 1h is always flowing. This flowing compressed gas disturbs the surface of the non-filled part F and causes gas entrainment in the non-filled part F. As a result, gas entrainment I occurs in the molten metal 1m filled in the product part 1j. It is estimated that voids remain in the cast article obtained by solidifying 1 m.

  The second presumed cause will be described. At the end of the filling process, the present inventors set the end face 1x on the right side (in the direction of the pouring gate) of the remaining molten metal 10n remaining in the molten metal supply passage 1h to a vertical plane as indicated by a broken line D shown in Patent Document 1. It was found that the surface was not parallel to the surface but was inclined to the lower right as shown in FIG. As described above, the compressed gas that pressurizes the molten metal in the molten metal supply passage is in a flowing state as described above, and the head pressure from the molten metal 1 m filled in the product portion 1j acts on the molten metal. It is estimated that this is because Since the end surface 1x of the remaining molten metal 10n is an inclined surface as described above, even if the amount of molten metal 1m poured into the mold 10 in the pouring process is equal to the target amount of molten metal, the end surface 1x In the case of an inclined surface, as shown in FIG. 3, the connecting end 1w of the molten metal supply passage 1h is not blocked by the molten metal 1m, and is not on the left side of the connecting end 1w with the product portion 1j of the molten metal supply passage 1h. It is presumed that the filling portion F is formed, and further, the gas entrainment I is generated as described above due to the generation of the non-filling portion F.

  The present invention has been made in earnest to suppress the generation of unfilled portions and gas entrainment based on the above estimated cause, and states that the state of the molten metal remaining in the molten metal supply passage at the end of the filling process is defined. It is based on knowledge.

  The present invention will be described below based on specific embodiments with reference to the drawings. In addition, the component of embodiment described below can also be suitably changed and implemented in the range which does not deviate from the meaning of this invention. Furthermore, this embodiment is a specific example of the present invention, and does not limit the present invention.

[Embodiment]
A manufacturing method according to an embodiment of the present invention will be described with reference to FIGS.

The present invention is a method for producing a cast article in which a molten metal is gravity poured into a breathable mold to produce a cast article,
The cavity of the breathable mold has at least a molten metal supply passage that opens to the outside of the breathable mold, and a product portion that is connected to the molten metal supply passage,
A pouring step of pouring a molten metal having a volume smaller than the entire cavity of the breathable mold in order to fill the desired cavity portion including the product portion with the molten metal,
After the start of the pouring process, before the poured molten metal is filled into the desired cavity portion, filling is performed by supplying gas from the pouring portion and filling the desired cavity portion with the molten metal by the gas pressure. A process,
The molten metal remaining in the molten metal supply passage in the filling step is
Formula 1: (D- (H ² / tanθ) / 2) / H ≧ H
[However, D is the longitudinal sectional area of the molten metal remaining in the molten metal supply passage in the filling step, H is the height of the molten metal supply passage, θ is the end surface of the molten metal remaining in the molten metal supply passage and the molten metal supply in the filling step. The angle of intersection (°) with the bottom of the passage, and 10 ° ≦ θ ≦ 80 °. ]
It has the shape which satisfies these.

(A) Structure of breathable mold The breathable mold 1 (hereinafter also simply referred to as the mold 1) is mainly composed of, for example, sand particles mainly composed of silica sand and caking materials such as bentonite as shown in FIG. The sand mold with air permeability is configured as follows: the upper mold 1d formed in the upper frame 1a and the lower mold 1e formed in the lower frame 1b are aligned on the parting surface and placed on the surface plate 1c. It is. The cavity 1f of the mold 1 is composed of a gate portion 1g, a molten metal supply passage 1h, and a product portion 1j. In FIGS. 4 to 6, the gate 1g, the molten metal supply passage 1h and the product portion 1j constituting the cavity 1f are formed by combinations of recesses formed on the parting surfaces of the upper mold 1d and the lower mold 1e, respectively. However, the cavity 1f of the present invention is not limited to this.

  Here, the air-permeable mold is configured so that when the desired cavity portion 1k is filled with molten metal, the gas existing in the desired cavity portion 1k can be vented to the outside of the system, that is, the ventilation It refers to a mold having the property. As such a mold, a mold formed using sand particles is most common. However, it may be a mold made of ceramic particles or metal particles, and even with a material that is hardly air permeable, such as gypsum, it is possible to mix air permeable materials or partially use air permeable materials. What is molded so as to have properties is a breathable mold. In addition, even in the case of, for example, a mold having no air permeability, an air-permeable mold is provided with air holes and vent holes to provide air permeability.

  In the narrow sense, the molten metal supply passage refers to a runway portion, a feeder portion, a dam portion, and the like that are formed in the horizontal direction, but in a broad sense, a gate portion that is formed in the vertical direction (e.g., a gate tap or a gate tap). included. Note that the mold 1 shown in FIGS. 4 to 6 is a case where the mold 1 is composed of a molten metal supply passage 1h configured only by a runner without a feeder and a weir. The desired cavity portion 1k of the cavity 1f of the mold 1 is the product portion 1j, and the other portion including the molten metal supply passage 1h is the other cavity portion 1o.

(B) Hot water pouring step As shown in FIG. 4, in order to fill the molten metal 1m into the product portion 1j which is a part of the cavity 1f of the mold 1 and smaller than the entire volume of the cavity 1f, A 1 m molten metal having a volume smaller than the entire cavity 1f is poured. Specifically, as described in detail below, a predetermined molten metal 1m stored in a pouring ladle (pouring means) 1L is poured from the pouring ladle 1L into the cavity 1f through the gate 1g. The molten metal 1m poured from the gate 1g flows through the molten metal supply passage 1h, and as shown in FIG. 4, a part thereof fills the bottom (part) of the product part 1j, and the other part is the molten metal supply passage 1h and It stagnates at the bottom of the gate 1g. Note that the pouring means for pouring 1 m of molten metal into the cavity 1 f is not limited to the pouring ladle described above, for example, using pouring means that stores an amount of molten metal 1 m necessary for pouring a mold for a plurality of frames. May be.

(C) Filling process Before the molten metal 1m poured in the pouring process is filled into the product part 1j, the gas 1p is fed from the pouring part 1g to fill the product part 1j while pushing the molten metal 1m. In the pouring process, 1 m of molten metal having a volume smaller than the entire cavity 1f of the mold 1, specifically, 1 m of molten metal having a volume sufficient to fill the product part 1j as described below is poured into the mold 1. The molten metal 1m fills the product portion 1j, which is the desired cavity portion 1k, but does not fill the entire cavity 1f of the mold 1. As a result, the molten metal 1m filled in the product portion 1j can be solidified to obtain a desired cast article, while only the molten metal 1m having a volume smaller than the whole is poured into the cavity 1f. Therefore, unnecessary parts other than the cast article required as a product are not formed, and the cast article can be manufactured with a high injection yield.

  Here, the above-mentioned solidification means that the entire product portion 1j which is the desired cavity portion 1k is solidified. However, before such total solidification, the boundary between the desired cavity portion 1k and the other cavity portion 1o, that is, the connection end 1w with the product portion 1j of the molten metal supply passage 1h (toward the gate portion 1g). The ends of the molten metal (hereinafter, sometimes referred to as residual molten metal 1n) were partially solidified (hereinafter, this partial solidification may be referred to as end solidification) and filled. It is desirable if 1 m of molten metal does not flow out toward the gate 1 g. More precisely, the solidification of the end portion means that a solid phase is crystallized to some extent at the end portion of the remaining molten metal 1n remaining on the right side from the connecting end 1w of the molten metal supply passage 1h when the filling process is completed. It means that 1m of molten metal stops flowing to the right. That is, in the present invention, the object is to fill a desired cavity portion 1k with 1 m of molten metal and finally solidify the whole to obtain a cast article, but various means for filling and solidification are at least It is preferable to continue until the end of the remaining molten metal 1n is solidified.

  The end solidification of the remaining molten metal 1n may be performed in accordance with, for example, the means described in Patent Document 1, and means for cooling the end of the remaining molten metal 1n, means for mechanically shutting off, etc. can be used as appropriate. . Further, at the start, during or after completion of the filling step, the refrigerant may be included in the gas to cool the end of the remaining molten metal 1n, or only the refrigerant may be directly brought into contact with the remaining molten metal 1n.

  Various gases can be used as the gas 1p, which is a medium for pushing the molten metal 1m mainly by the force of dynamic pressure. For example, air may be used from the viewpoint of cost, and argon, nitrogen, carbon dioxide, etc., which are non-oxidizing gases, may be used from the viewpoint of preventing oxidation of the molten metal 1 m. In addition, the gas is, for example, a gas compressed by a compressor or the like (hereinafter sometimes referred to as a compressed gas), which is preferable from the point of uniformly pressing the molten metal 1 m with a constant applied pressure (dynamic pressure). .

  As shown in FIG. 5, the gas 1p air supply means is arranged in such a manner that one end is disposed so as to close the upper opening of the gate 1g and the other end is connected to a gas generation means (not shown). The air supply means 1q can be used. At this time, in order to suppress gas leakage from the gate 1g and effectively push the molten metal 1m poured into the cavity 1f, the upper opening of the gate 1g may be closed with a sealing member such as a flange. . Further, if the air permeability is lowered by applying a resin coating or the like to the surface of the other cavity portion 1o, it is preferable because the escape of the gas 1p from the other cavity portion 1o is suppressed and the force pushing the molten metal 1m is stabilized.

  The flow rate, pressure, and the like of the gas 1p may be set such that the molten metal 1m can be pushed with an appropriate force in consideration of gas escape from the mold 1 having air permeability. The flow rate, pressure, and the like of the gas 1p may be constant throughout the filling process, or may be changed in a predetermined pattern. Furthermore, in order to reduce the amount of molten metal corresponding to the volume of the hot metal part, after the filling process is completed and the product part 1j is filled with 1m of molten metal, the molten metal 1m filled in the product part 1j is solidified to a desired level. Until then, the gas 1p may be continuously supplied and the molten metal 1m may be continuously pressed.

  The start timing of the gas 1p supply is not particularly limited as long as it is before the poured molten metal 1m is filled in the product part 1j, and may be set at an appropriate time. However, when the molten metal 1m poured into the cavity 1f is not pushed for a long time, oxidation of the molten metal 1m stagnating in the molten metal supply passage 1h proceeds, so-called Noro, which is an oxide, enters the product portion 1j, There is a possibility that a hot water boundary or non-rotation may occur due to a temperature drop of 1m. For this reason, it is desirable to immediately start supplying the gas 1p immediately after a predetermined amount of the molten metal 1m has been poured into the cavity 1f.

(D) Pouring amount The pouring amount of 1 m of molten metal poured into the cavity 1f of the mold 1 in the pouring step will be described. In the manufacturing method of the embodiment, as shown in FIG. 6, the product portion 1j (desired cavity portion 1k) is filled with the molten metal 1m at the end of the filling step, and the desired portion of the molten metal supply passage 1h is described in detail below. In the pouring step, 1 m of molten metal having a volume sufficient to fill the remaining molten metal 1n with the passage end G, which is a predetermined range from the coupling end 1w with the cavity portion 1k, is poured. That is, at the end of the filling process, by setting the passage end G of the molten metal supply passage 1h to be filled with the remaining molten metal 1n, generation of non-filled portions in the product portion 1j and gas entrainment resulting therefrom are suppressed, As a result, a healthy cast article can be obtained. The above-mentioned passage end G refers to the range filled with the remaining molten metal 1n in the molten metal supply passage 1h, and when the end surface 1x of the remaining molten metal 1n is an inclined surface as shown in FIG. The range where the surface exists is not included in the passage end G. The remaining molten metal 1n filled in the passage end G may have, for example, air bubbles in the central portion thereof, and needs to be completely filled with molten metal 1m as long as it does not affect the product portion 1j. No

  Hereinafter, in order to realize a state in which the passage end G of the molten metal supply passage 1h is filled with the remaining molten metal 1n at the end of the filling process, the amount of molten metal 1m to be poured in the molten metal process is shown in FIGS. This will be described in detail with reference to FIG. 7 and FIGS. 8 (a) to 8 (c). Here, in FIG. 7 (M portion enlarged view of FIG. 6), the molten metal 1m existing in the range K of the product portion 1j, the passage end G, and the end surface (inclined surface) 1x is connected integrally. For the sake of understanding, they are shown with different hatchings.

In order to realize a state in which the remaining molten metal 1n is filled in the passage end G of the molten metal supply passage 1h, the volume of the molten metal to be poured in the pouring step is (Q + q) [where Q is a desired value. The volume of the cavity portion, q is the volume of the molten metal (residual molten metal 1n) remaining in the molten metal supply passage 1h in the filling step. ] (Q + q) / Q is greater than 1 and the molten metal remaining in the molten metal supply passage 1h in the filling step (residual molten metal 1n)
Formula 1: (D- (H ² / tanθ) / 2) / H ≧ H
[However, D is the longitudinal sectional area of the molten metal remaining in the molten metal supply passage 1h in the filling process (residual molten metal 1n), H is the height of the molten metal supply passage 1h, and θ is remaining in the molten metal supply passage 1h in the filling process. The angle of intersection (°) between the end surface of the molten metal (residual molten metal 1n) and the bottom surface of the molten metal supply passage 1h, and 10 ° ≦ θ ≦ 80 °. It is necessary to pour 1 m of molten metal having a shape satisfying the above in the pouring step.

  The ratio (Q + q) / Q of the volume (Q + q) of the molten metal to be poured and the volume Q of the desired cavity part is the size of the desired cavity (particularly the product part) and the length of the molten metal supply passage Since the optimum range varies depending on the direction cross-sectional area and the like, it cannot be determined uniquely. Therefore, the volume of the molten metal to be poured in the pouring step is set so that the molten metal remaining in the molten metal supply passage 1h in the filling step (residual molten metal 1n) (corresponding to q) has a shape satisfying Equation 1.

Note that the left side of Equation 1 is the length of the passage end G in the longitudinal direction, indicated by the symbol L in FIGS. That is, satisfying Equation 1 indicates that the length L of the remaining molten metal 1n existing in the region of the passage end G is equal to or greater than the height H of the molten metal supply passage 1h. [(D- (H ² / tan θ) / 2) / H] is preferably 3.0 × H or less.

Here, the meaning of each symbol in Formula 1 and other symbols is defined as follows.
(1) Volume Q of product section
Q is the volume of the product part (desired cavity part) 1j to be filled with the molten metal 1m shown in FIG. 6, and is the volume that constitutes a part of the amount of molten metal 1m to be poured in the pouring step.

(2) Volume of remaining molten metal q
q is the volume of the remaining molten metal 1n remaining in the molten metal supply passage 1h at the end of the filling process shown in FIG. 7 and FIG. 9, and the volume constituting the remainder of the molten metal 1m poured in the molten metal pouring process It is. Note that the remaining molten metal 1n is a range in which there is an inclined surface that is the end surface 1x of the remaining molten metal 1n in the molten metal supply passage 1h (hereinafter, this range may be referred to as an inclined portion K). The sum of the amounts of molten metal present in both of them is q.

(3) Longitudinal cross-sectional area D of residual molten metal
D is a cross-sectional area in the longitudinal direction of the remaining molten metal 1n remaining in the molten metal supply passage 1h at the end of the filling step shown in FIG. Here, the longitudinal direction of the molten metal supply passage 1h refers to the left-right direction of the paper, that is, the direction from the gate (not shown) toward the product portion (desired cavity portion) 1j. The short direction of the molten metal supply passage 1h indicates a direction orthogonal to the longitudinal direction (in FIG. 7, a direction orthogonal to the paper surface). Note that, as shown in FIG. 9, the end surface 1x of the remaining molten metal 1n pushed by the flowing gas is not a plane parallel to the short direction, and the surface shape is often wavy. For this reason, the cross-sectional areas of the cross-sections at different positions of the remaining molten metal 1n may be different in the short direction. Therefore, in the present invention, the average value of the cross-sectional area in the longitudinal direction of the remaining molten metal 1n obtained in each of a plurality of cross-sections at different positions of the remaining molten metal 1n in the short direction, the value of the cross-sectional area D to be substituted into the above equation 1 It is defined as

(4) Height H of molten metal supply passage
H is the height of the molten metal supply passage 1h shown in FIGS. Here, the molten metal supply passage 1h of the embodiment has a height H of the right side surface H1 and the left side surface H2 as shown in the OO cross section shown in FIG. 8 (a) which is a cross section in the short direction of the molten metal supply passage 1h. The width T is the same as the upper surface T2 and the lower surface T1, and the cross-sectional shape in the longitudinal direction does not change and is almost the same. On the other hand, as the molten metal supply passage, for example, as shown in FIG. 8 (b), a molten metal supply passage 2h having a cross-sectional shape in which the width T2 of the upper surface and the width T1 of the lower surface are different, as shown in FIG. In some cases, the molten metal supply passages 8h having different cross-sectional shapes are arranged on the right side surface h1 and the left side surface h2. In such cases, the height H of the molten metal supply passage to be substituted into Equation 1 is defined as follows. For example, in the case of a cross-sectional shape as shown in FIG. 8 (b), a straight line U drawn horizontally so as to divide the cross-sectional area of the molten metal supply passage 2h into two equal parts up and down is between two points intersecting both side surfaces of the cross-section. The distance Tave is calculated, and the height of the molten metal supply passage having the same cross sectional area as that of the molten metal supply passage shown in FIG. Defined as H. Also, in the case of a cross-sectional shape as shown in FIG. 8 (c), the height H of the molten metal supply passage is defined from Tave obtained in the same manner.

(5) Intersection angle θ
θ is an intersection angle between the end surface 1x of the molten metal (residual molten metal 1n) remaining in the molten metal supply passage 1h and the lower surface of the molten metal supply passage 1h at the end of the filling step shown in FIGS. Here, as explained in the presumed cause section, the end surface 1x of the remaining molten metal 1n in the filling process is inclined, and the value of the crossing angle θ varies depending on various conditions such as gas supply conditions and specifications of the molten metal 1m. However, in order to achieve a higher casting yield and to obtain a more healthy casting product in which the occurrence of unfilled parts and gas entrainment is suppressed, the crossing angle θ should be in the range of 10 ° to 80 °. It is necessary to set the various conditions. When the crossing angle θ is smaller than 10 °, the portion of the remaining molten metal 1n becomes sharp. For example, when the cast article is taken out from the mold 1 after casting and transported to the next process, the transport device such as a conveyor belt is easily damaged. This is not preferable. In order to make the crossing angle θ exceed 80 °, for example, it is necessary to remarkably increase the gas supply amount and pressure, which is not practical. A preferable range of the crossing angle θ is 20 ° to 80 °.

  As described above, since the end surface 1x of the remaining molten metal 1n is often wavy, in the present invention, as shown in FIGS. 7 and 9, the end surface 1x of the remaining molten metal 1n and the molten metal supply passage 1h The intersection with the lower surface is P1, the intersection with the upper surface is P2, and the virtual straight line 1y connecting the points P1 and P2 is the inclined surface, and the intersection angle θ is the virtual inclined surface 1y and the molten metal supply passage 1h. It is defined as the angle of intersection with the lower surface of Further, as shown in FIG. 9, there are cases in which the inclined angles 1 and θ2 are different between the inclined surface 1y and the inclined surface 1z at different positions in the short direction. In such a case, the crossing angles of the inclined surfaces of the remaining molten metal 1n are obtained at a plurality of different positions in the short side direction, and the average value thereof is set as the value of the crossing angle θ that is substituted into Equation 1.

  According to the present invention, the molten metal remaining in the molten metal supply passage is poured into the molten metal supply passage 1h in a product portion (desired cavity) by pouring in an amount of molten metal 1m that satisfies the above formula 1 The passage end G in a predetermined range (more than the height H of the molten metal supply passage 1h) from the connection end 1w with the portion 1j is filled with the remaining molten metal 1n. A passage end G always lies between the connecting end 1w and the inclined portion K, and the inclined portion K is separated from the connecting end 1w by a distance L. When the distance L is equal to or higher than the height H of the molten metal supply passage 1h, the end portion of the remaining molten metal 1n having the inclined end surface 1x existing in the inclined portion K does not reach the product portion 1j. Generation | occurrence | production of the non-filling part and gas entrainment resulting from it were suppressed, and it was able to obtain a sound casting article. Furthermore, by setting various conditions such as gas supply conditions and molten metal specifications so that the crossing angle θ is in the range of 10 ° to 80 °, a high injection yield could be realized.

  The value obtained from the modulus of the remaining molten metal 1n, that is, the volume / surface area (excluding the area of the connecting end 1w) is preferably 0.5 or more. By setting the residual molten metal 1n to have a modulus of 0.5 or more, the residual molten metal 1n functions as a feeder in the solidification process of the molten metal 1m of the product part 1j performed during or after the filling process. It is possible to omit or reduce the hot water section. Further, in order to increase the inclination angle θ of the end surface 1x of the remaining molten metal 1n existing in the inclined portion K and suppress the unfilled portion and gas entrainment, the molten metal supply passage has a (height H / width T). 1 or less is desirable. Values determined by the method described with reference to FIGS. 8A to 8C are substituted into H (height) and T (width) of this equation.

1,10 ・ ・ ・ Breathable mold
1a ・ ・ ・ Upper frame
1b ... Bottom frame
1c ... Surface plate
1d ・ ・ ・ Upper mold
1e ・ ・ ・ Lower mold
1f ・ ・ ・ Mold cavity
1g ...
1h ・ ・ ・ melt supply passage
1j ・ ・ ・ Product Department
1k ... Desired cavity part
1L ... Pour hot water ladle
1m ... molten metal
1n, 10n ・ ・ ・ Remaining molten metal
1o ・ ・ ・ Other cavity parts
1p ・ ・ ・ Gas
1q ・ ・ ・ Air supply means
1w ・ ・ ・ Connection end
F: Unfilled part
G ・ ・ ・ End of passage
K ・ ・ ・ Inclined part
I ... Gas entrainment

Claims (1)

A method for producing a cast article in which a molten metal is gravity poured into a breathable mold to produce a cast article,
The cavity of the breathable mold has at least a molten metal supply passage that opens to the outside of the breathable mold, and a product portion that is connected to the molten metal supply passage,
A pouring step of pouring a molten metal having a volume smaller than the entire cavity of the breathable mold in order to fill the desired cavity portion including the product portion with the molten metal,
After the start of the pouring process, before the poured molten metal is filled into the desired cavity portion, filling is performed by supplying gas from the pouring portion and filling the desired cavity portion with the molten metal by the gas pressure. A process,
The molten metal remaining in the molten metal supply passage in the filling step is
Formula 1: (D- (H ² / tanθ) / 2) / H ≧ H
[However, D is the longitudinal sectional area of the molten metal remaining in the molten metal supply passage in the filling step, H is the height of the molten metal supply passage, θ is the end surface of the molten metal remaining in the molten metal supply passage and the molten metal supply in the filling step. The angle of intersection (°) with the bottom of the passage, and 10 ° ≦ θ ≦ 80 °. ]
A method for producing a cast article characterized by having a shape satisfying

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