JPH0824991A - Casting method and core used to this method - Google Patents

Abstract

PURPOSE:To omit a process for plugging an opening part in the case of trying the leakage test of a product after casting and to use an auxiliary core as a supporting material for carrying a product and to reduce the cost by pulling out a main core while remaining the auxiliary core. CONSTITUTION:The strength at a part except a first core print part 22h at the main core 22 is lowered by the heat of molten metal so as to be capable of the plastic deformation and at the same time, a reciprocal binding force, in which the other end can be pulled out by pulling out the one end, is produced. As the same way, the auxiliary core 24 has high strength at a second core print part 24h and the neighborhood thereof but lowers the strength at the other part by the heat of the molten metal so as to be capable of the plastic deformation, and at the same time, the reciprocal binding force, in which the other end can be pulled out by pulling out the one end, is provided. By this method, the fitting part between the recessed part 22m of the main core 22 and the projecting part 24m of the auxiliary core 24 can be removed by applying the force in the separating direction to both parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method for casting a product by press-fitting a molten metal into a cavity into which a core is inserted, and a core used in the method.

[0002]

2. Description of the Related Art A conventional technique related to this is disclosed in Japanese Laid-Open Patent Publication No. 61-61.
No. 293646. This casting method is a method of casting using a core molded of a flexible material such as rubber. According to this method, since the core has flexibility, it is possible to easily pull out the entire core from the product after casting, even if the product has an undercut portion. . Therefore, unlike the conventional sand core, part of the sand does not remain in the undercut portion of the product when the core is removed.

[0003]

According to the above-mentioned conventional casting method, since the core is made of a flexible material such as rubber, the molten metal is pressed into the cavity, so that the molten metal is melted. There is a problem in that the parts colliding with each other are deformed. Therefore, when using a core such as rubber, it is necessary to reduce the casting pressure to a pressure at which the core is not deformed. Further, since the core has low strength, it is difficult to use a plurality of cores in combination in the cavity because the strength is further reduced. For this reason,
For example, when pulling out the core, leave a part of the core and block the opening of the product with a part of the core, or use a part of the core as a support material for transporting the product. It is also impossible. The technical problem of the present invention is that, until the molten metal is solidified, it has a large strength so that it is not deformed by the high pressure of the molten metal, and after the molten metal is solidified, the core is made of a resin that is plasticized by the heat of the molten metal. By making it possible to perform high-precision casting with high precision and facilitate extraction of the core after casting, further, by combining a plurality of cores to manufacture a core of a predetermined shape,
When the core is pulled out, a part of the core can be left in a necessary portion of the product to improve work efficiency in a post process.

[0004]

[Means, actions, and effects for solving the problems]

[Means according to Claim 1 for Solving the Problem] The above-mentioned problem is solved by a casting method having the following features. That is, the casting method according to claim 1 is a casting method for casting a product by press-fitting a molten metal into a cavity into which a core is inserted, and a portion which is in contact with the core after the molten metal is pressed into the cavity. When the time until the solidification is T1 and the time longer than the T1 by a predetermined time is T2, the amount of deformation is against the high pressure of the molten metal while it is in contact with the molten metal for T1 hours. The strength that satisfies the required shape accuracy is maintained, and during the above T1 time and below T2 time, the strength decreases due to the heat of the molten metal and plastic deformation is possible, and at the same time the other end is pulled out. A step of selecting a resin having mutual bonding force that can also be pulled out, a step of manufacturing a main core for molding a hollow portion in the product by the resin selected in the step, and a step of contacting with molten metal Melting A step of manufacturing an auxiliary core that is used in combination with the main core by a resin that maintains the strength that the amount of deformation against the high pressure of satisfies the shape accuracy required for the product, and the main core Step of setting the skirting board part and the skirting board part of the auxiliary core in the mold, and positioning both cores at a predetermined position in the cavity; And a step of pulling out the main core while leaving the auxiliary core at the timing. [Operation of the invention described in claim 1] According to the present invention,
The resin used as the material for the main core and the auxiliary core maintains a predetermined strength from the time when the molten metal is pressed into the cavity until the portion in contact with those cores is solidified, that is, for T1 hour. ing. Therefore, the main core and the auxiliary core do not deform beyond the shape accuracy required for the product even when the high pressure of the molten metal is applied. In addition, the resin used as the material of the main core has a decrease in average strength due to the heat of the molten metal after the molten metal has solidified (after the lapse of T1 time) to the lapse of T2 time, and thus plastic deformation is caused. It has a mutual coupling force that enables it and also pulls out the other end by pulling out one end. Therefore, the combined portion of the main core and the auxiliary core comes off when a force in the direction of separating them is applied. On the other hand, since the skirting part of the auxiliary core and its vicinity are cooled by the mold, they are not plasticized by the heat of the molten metal, and are retained substantially at their original strength and firmly fixed to the product. Therefore, if the pull-out force is applied to the skirting part of the main core at an appropriate timing from T1 time to T2 time, the combination of the main core and the auxiliary core is disconnected, and only the main core is removed. Can be easily pulled out of the product. That is, as for the opening of the product, only the opening of the portion where the main core is pulled out is opened, and the opening formed by the auxiliary core is kept closed by the auxiliary core. [Effect of the invention described in claim 1] According to the present invention,
Since the main core and the auxiliary core have sufficient strength to withstand the high pressure of the molten metal until the molten metal in contact with these cores solidifies, it is necessary to lower the casting pressure as in the past. It becomes difficult to cause defective product shape. Further, in order to pull out the main core while leaving the auxiliary core, the opening formed by the auxiliary core is kept closed by the auxiliary core. Therefore, when performing a leak test or the like of the product after casting, a step of closing some openings can be omitted. Furthermore, since the auxiliary core that closes the opening of the product retains a large strength, it becomes possible to use this auxiliary core as a support material for transporting the product.

[Means according to Claim 2 for Solving the Problems] This core is a core used in a method for casting a product by press-fitting the molten metal into the cavity at a high pressure. Let T1 be the time from the time of press-fitting into the core until the part in contact with the core is solidified, and let T2 be a time longer than T1 by a predetermined time, while the pressure of the molten metal is high during the contact with the molten metal for T1 hours. Against the above, the amount of deformation maintains the strength that satisfies the shape accuracy required for the product, and during the period of T1 time or more and T2 hours or less, the strength decreases due to the heat of the molten metal and plastic deformation is possible It is made of a resin that has a mutual coupling force that allows one end to be pulled out and the other end to be pulled out at the same time. Kibe Main core provided with, while being in contact with the molten metal is manufactured by a resin that maintains the strength that the deformation amount against the high pressure of the molten metal satisfies the shape accuracy required for the product, A second fitting portion that fits with the first fitting portion is formed, and an auxiliary core having a second skirting portion supported by the mold is provided. [Operation of the invention described in claim 2] The core according to the present invention is assembled as a core by fitting the main core and the auxiliary core in the first fitting portion and the second fitting portion. And is set in the mold by the first skirting board and the second skirting board. Furthermore, the resin used as the material for the main and auxiliary cores is
A predetermined strength is maintained from the time when the molten metal is pressed into the cavity until the portions contacting the cores solidify. In addition, the resin used as the material of the main core has a decrease in average strength due to the heat of the molten metal after the molten metal has solidified (after the lapse of T1 time) to the lapse of T2 time, and thus plastic deformation is caused. It has a mutual coupling force that enables it and also pulls out the other end by pulling out one end. Therefore, the casting method described in claim 1 can be performed by using the core. [Effect of the invention described in claim 2] According to the present invention, the same effect as the invention described in claim 1 can be obtained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A casting method according to an embodiment of the present invention and a core used in the method will be described below with reference to FIGS. The casting method according to the present embodiment is a technique for molding an aluminum product x (hereinafter referred to as a product x) having a hollow portion by a die casting method, and the die casting used in this embodiment is shown in FIG. A longitudinal cross-sectional view of the main part of the machine, FIG. 1 (B)
FIG. 3 shows a vertical cross-sectional view of the core 20 according to this embodiment.
The core 20 is formed by combining a main core 22 and an auxiliary core 24. The main core 22 is a core for molding a hollow portion and a main opening xk (see FIG. 2) inside the product x, and recesses 22m are formed on the upper surface and the lower surface of the main core 22, respectively. . And this recess 2
The core 20 is assembled by fitting the convex portion 24m of the auxiliary core 24 to 4 m. The auxiliary core 24 is a core for forming an opening xh (see FIG. 2) in the product x, and is formed into a substantially columnar shape according to the opening shape of the product x. The core 20 includes a first baseboard portion 22h formed on the main core 22 and a second baseboard portion 24 formed on the auxiliary core 24.
As shown in FIG. 1 (A), h and mold 10
Is set to That is, the concave portion 22m of the main core 22 corresponds to the first fitting portion of the present invention, and the convex portion 24m of the auxiliary core 24 corresponds to the second fitting portion of the present invention.

The mold 10 includes a movable mold 12 and a fixed mold 1.
4, and a cavity 16 which is a product molding portion is formed inside in a mold clamped state. Then, the first baseboard portion 22 of the core 20 is positioned so that the core 20 is positioned at the specified position within the cavity 16.
h, the second skirting board portion 24h is engaged with the mold 10. As a material for the core 20, a synthetic resin such as polycarbonate having a high glass transition point and high impact strength and ductility is preferably used. Here, the core 20 has a deformation amount against the high pressure of the melt during the period from the time when the melt is pressed into the cavity 16 until the portion contacting the core 20 is solidified (for T1 time). The strength that satisfies the shape accuracy required for x can be maintained. On the other hand, during the period from T1 time to T2 time, the strength of the molten metal is lowered by the heat of the molten metal and plastic deformation is possible, and at the same time, one end is pulled out and the other end is pulled out. Further, after T2 hours or more, the heat of the molten metal almost entirely plasticizes and softens.

However, the first baseboard portion 22 of the main core 22
Since the h and the second skirting part 22h of the auxiliary core 24 are engaged with the mold 10 and cooled by the mold 10, the heat of the molten metal is not directly received. Further, since the resin such as polycarbonate has a low thermal conductivity, the heat of the molten metal is not transmitted from the inside of the core 20 to the baseboard portions 22h and 24h. Therefore, the first skirting board portion 22h and the second skirting board portion 22h are hardly heated during casting and are maintained in the initial state in which both impact strength and ductility are high. It should be noted that the strength of the auxiliary core 24 can be ensured by covering it with a heat insulating material such as silicon rubber under the condition that it is easily affected by the heat of the molten metal.

Next, the casting method according to this embodiment will be described. As shown in the process diagram of FIG.
When the mold is set in the mold 10 and the mold is clamped, the molten metal is pressed into the cavity 16 from an injection sleeve (not shown) and casting is performed (step 100). During casting, the core 20 has a shape accuracy required for the product x until the molten metal in contact with the core 20 is solidified, that is, until the time T1 elapses from the press-fitting of the molten metal against the high pressure of the molten metal. It is possible to maintain the strength that satisfies. For this reason, unlike the conventional resin core, it is not necessary to lower the casting pressure, and the defective shape of the product x is less likely to occur. However, after a lapse of T1 time from the press-fitting of the molten metal, the core 20 receives heat from the molten metal and is gradually plasticized from the surface side, and the average strength decreases with the passage of time. On the other hand, the molten metal in the cavity 16 is cooled by the mold 10 and the core 20 over time, and solidification proceeds. Then, when the molten metal in the cavity 16 is wholly solidified, as shown in step 111, the mold is opened and the product x is taken out from the mold 10.

Here, the timing for opening the mold is T
It is set after 1 hour has passed and before T2 has passed,
Simultaneously with the mold opening or immediately after the mold opening, the pulling-out force is applied to the first skirting part 22h of the main core 22 constituting the core 20. As described above, the first skirting portion 22h of the main core 22 retains high strength because it is not directly heated by the molten metal during casting, and is deformed even if pulling force is applied. There is nothing to do. On the other hand, the parts of the main core 22 other than the first skirting part 22h are reduced in strength by the heat of the molten metal and can be plastically deformed, and at the same time, the other end can be drawn out. It has a mutual coupling force. Similarly, while the auxiliary core 24 has high strength in the second skirting part 24h and its vicinity, the strength of other parts decreases due to the heat of the molten metal and plastic deformation is possible. At the same time, the mutual coupling force is provided so that the other end can be pulled out by pulling out one end.
For this reason, the fitting portion between the concave portion 22m of the main core 22 and the convex portion 24m of the auxiliary core 24 is disengaged when a force in the direction of separating the two is applied. As described above, the auxiliary core 24 has high strength in the second skirting portion 24h and the vicinity thereof, and the vicinity of the second skirting portion 24h is cast and wrapped in aluminum to produce the product x. It is firmly fixed to. Therefore, if the pulling-out force is applied to the first skirting portion 22h of the main core 22 between after the lapse of T1 time and before the lapse of T2 time, the fitting of the main core 22 and the auxiliary core 24 with each other. The connection of the mating portion is released, and only the main core 22 is pulled out from the product x. That is, in the opening of the product x, only the main opening xk of the portion where the main core is pulled out is opened, and the opening xh formed by the auxiliary core 24 remains closed by the auxiliary core 24. Held in. In addition, in order to remove the auxiliary core 24 from the opening xh of the product x, a method is adopted in which the auxiliary core 24 is heated to be softened and then pulled out.

In this way, when the product x is taken out of the mold 10 and the main core 22 is pulled out, the post-treatment of the product x (see step 112 in FIG. 4) is performed. Then, after the post-processing is completed, a leak inspection of the product x is performed in step 113. FIG. 2 is a schematic diagram showing how the product x is inspected for leaks. The main opening xk used when pulling out the main core 22 is held in the product x in an open state, and the pressurizing device P for pressurizing compressed air into the main opening xk is connected to the product x. It Here, the main opening xk
Since the openings xh other than those are surely closed by the auxiliary core 24, it is not necessary to perform the leak inspection after closing those openings xh as in the conventional case, and the work efficiency is improved. In addition, since the auxiliary core 24 that closes the opening xh of the product x is made of a resin having a strength that can withstand the high pressure of the molten metal as described above, in the product shipping and transportation steps after the leak inspection ( Step 114), as shown in FIG. 3, by using the auxiliary core 24 as a support material for the product x, it is possible to prevent the product x from being damaged. The auxiliary core 24 is heated and removed when it is no longer needed.

As described above, according to the present embodiment, the opening xh formed by the auxiliary core 24 is closed by the auxiliary core 24 in order to pull out the main core 22 leaving the auxiliary core 24. It is kept as it is. Therefore, the step of closing the opening xh can be omitted when performing a leak test or the like of the product x after casting. Furthermore, since the auxiliary core 24 can also be used as a support material for product transportation, it is not necessary to specially manufacture a support material for product transportation, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part and a longitudinal sectional view of a core of a die casting machine used in a casting method according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a state of a product leak inspection.

FIG. 3 is a vertical cross-sectional view showing how products are shipped and transported.

FIG. 4 is a process drawing showing the overall process.

[Explanation of symbols]

 10 Mold 20 Core 22 Main Core 22m Recessed Part (First Fitting Part) 22h First Baseboard Part 24 Auxiliary Core 24m Convex Part (Second Fitting Part) 24h Second Baseboard Part

Front Page Continuation (72) Inventor Shuichi Tomitaka 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (2)

[Claims] 1. A casting method for casting a product by press-fitting a molten metal into a cavity into which a core is inserted, the time from when the molten metal is pressed into the cavity until a portion contacting the core is solidified. Is T1 and a time longer than the T1 by a predetermined time is T2, the amount of deformation against the high pressure of the molten metal during the contact with the molten metal for T1 hours is the shape accuracy required for the product. Mutual strength can be maintained while maintaining a satisfactory strength, and plastic deformation is possible due to the decrease in strength due to the heat of the molten metal during the time T1 or more and the time T2 or less, while at the same time pulling out one end A step of selecting a resin having a binding force, a step of manufacturing a main core for forming a hollow portion in the product by the resin selected in the step, and a step of resisting a high pressure of the molten metal while in contact with the molten metal. Strange A step of manufacturing an auxiliary core that is used in combination with the main core by a resin that maintains the strength that the shape amount satisfies the shape accuracy required for the product, and a skirting part and an auxiliary of the main core. The step of setting the core skirting part and the core in a mold and positioning both cores at a predetermined position in the cavity, and after the molten metal is pressed in, at the timing of T1 or more and T2 or less And a step of pulling out the main core while leaving the core. 2. A core used in a method for casting a product by press-fitting a melt into a cavity at a high pressure, the time from when the melt is press-fit into the cavity until a portion contacting the core is solidified. When T1 is set and a time longer than the T1 by a predetermined time is set to T2, the deformation amount against the high pressure of the molten metal satisfies the shape accuracy required for the product while being in contact with the molten metal for T1 hours. Mutual coupling that maintains the strength that is maintained and that plastic deformation is possible due to the decrease in strength due to the heat of the molten metal during the time T1 or more and the time T2 or less, and at the same time, the other end can be pulled out by pulling out one end. Manufactured from a resin having strength, a first fitting part is formed at a predetermined part, and a main core having a first skirting part supported by a mold and High pressure of molten metal By contrast, the amount of deformation is made of resin that maintains the strength that satisfies the shape accuracy required for the product, and the second fitting portion that fits with the first fitting portion of the main core is formed. And an auxiliary core having a second skirting part supported by the mold.