JP4655869B2 - Die casting method - Google Patents

Description

  The present invention relates to a die casting method.

  2. Description of the Related Art In recent years, cylinder blocks, cylinder heads, pistons, and the like constituting an engine are formed of aluminum alloys that are lightweight and easy to recycle. As a method for manufacturing a mechanical structural part formed of such an aluminum alloy, a die casting method in which a molten metal is injected into a product mold at a high pressure is used (see, for example, Patent Document 1).

In this die casting method, a runner that is a gas suction passage is connected to a cavity of a mold. A suction device for sucking gas is connected to the end portion of the runner, and the gas in the cavity can be sucked through the runner by this device. The gas remaining in the molten metal can be reduced by sucking the gas in the cavity and pressurizing and injecting the molten metal into the mold. As a result, the occurrence of blow holes in the cast product can be suppressed.
JP 2002-361387 A

By the way, in the die-casting method, since the portion corresponding to the runner of the cast product is not a product, the mold is designed so that the volume of the runner becomes as small as possible.
However, when the volume of the runner is reduced in this way, the strength of the portion corresponding to the runner of the molded product cast is also lowered. Due to such a decrease in strength, when a molded product cast from the mold is taken out, the portion corresponding to the runner of the molded product may be broken and remain in the mold.

  The present invention has been made in view of such circumstances, and an object thereof is a die casting method in which a gas in a mold is discharged through a runner of the mold and a molten metal is pressurized and injected into the mold. When taking out the molded product cast from the mold, it is intended to prevent the portion corresponding to the runner of the molded product from remaining in the mold.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is the die casting method in which the gas in the mold is discharged through the runner of the mold and the molten metal is pressurized and injected into the mold, and the reinforcing member extending along the extending direction of the runner is the same. The gist is to inject the molten metal into the mold after being placed in the runner.

  According to this configuration, the reinforcing member extending along the extending direction of the runner is disposed in the runner, and then the molten metal is injected into the mold under pressure, so the portion corresponding to the runner of the molded product cast by the reinforcing member The strength of can be improved. As a result, when the product is taken out from the mold, the runner portion is not easily broken, so that the portion corresponding to the runner of the molded product can be prevented from remaining in the mold.

In addition, after discharging the gas in the mold, the molten metal may be pressure-injected into the mold, or the gas in the mold may be continuously discharged during the pressure injection of the molten metal into the mold. Good.
The gist of a second aspect of the present invention is that, in the die casting method according to the first aspect, the reinforcing member is formed of a material having higher toughness than the molten metal material.

  According to this configuration, since the reinforcing member is formed of a material having higher toughness than the molten metal material, even if a portion corresponding to the runner of the molded product that is cast is broken, the reinforcing member is not easily cut. . As a result, it is possible to further suppress the portion corresponding to the runner of the molded product remaining in the mold.

The toughness is a physical property indicating the magnitude of energy that can be absorbed before breaking, and the higher the toughness material, the slower the speed until breaking.
The gist of the invention described in claim 3 is that, in the die-casting method according to claim 1 or 2, the reinforcing member is disposed at least in a curved portion of the runner.

According to this configuration, since the reinforcing member is disposed at least in the curved portion of the runner, it is possible to reinforce a portion where stress tends to concentrate when taking out a molded product cast from the mold.
The gist of the invention described in claim 4 is the die casting method according to claim 1 or 2, wherein the reinforcing member is disposed over the entire runner.

According to this configuration, since the reinforcing member is disposed on the entire runner, it is possible to suppress a part of the portion corresponding to the runner of the cast product from being left in the mold.
The gist of a fifth aspect of the present invention is that, in the die casting method according to the first or second aspect, the reinforcing member is disposed in a portion where the cross-sectional area of the runner is minimized.

  According to this configuration, since the reinforcing member is disposed in the portion where the cross-sectional area of the runner is minimized, it is possible to effectively reinforce the portion that easily breaks in the portion corresponding to the runner of the cast product.

The gist of the invention described in claim 6 is the die casting method according to any one of claims 1 to 5, wherein the reinforcing member is a single member.
According to this configuration, it is possible to suppress the portion corresponding to the runner of the cast molded product from being broken between the reinforcing members as compared with the case where a plurality of reinforcing members are arranged in combination.

The invention described in claim 7 is the die casting method according to any one of claims 1 to 6, that you place the reinforcing member to the runner while elastically deformed according to the shape of the runner It is a summary.

In this structure, by which to place the runner while elastically deforming the combined reinforcing member in the shape of runners, since the reinforcing member comes into pressure contact against the inner wall of the runner due to its elastic force, this mold Can be prevented from coming off.

Hereinafter, an embodiment in which the present invention is embodied as a cylinder block die casting method will be described with reference to FIGS. 1 to 4.
First, the structure of the movable mold 10 and the fixed mold 20 used in the die casting method of the cylinder block according to this embodiment will be described with reference to FIGS.

  As shown in FIG. 1, a cavity 30 having irregularities corresponding to the product shape of the cylinder block is formed at the center of the movable mold 10. Decompressing runners 40 and 41 that extend obliquely and are recessed are connected to both corners on the upper side of the cavity 30, respectively. The decompression runners 40 and 41 are bifurcated at a connection portion with the cavity 30 and are connected to the upper surface and the side surface of the cavity 30, respectively. The decompression runners 40 and 41 have a plurality of curved portions and are formed symmetrically with respect to the central axis C of the cavity 30. The decompression runners 40 and 41 are formed with a uniform depth, and their cross-sectional areas (minimum cross-sectional areas perpendicular to the flow direction of the molten metal) are substantially uniform over the entire length. Here, the decompression runners 40 and 41 are formed only on the movable mold 10, and are not formed on the fixed mold corresponding to the movable mold 10. Therefore, the cross-sectional areas of the decompression runners 40 and 41 in the movable mold 10 coincide with the flow path cross-sectional area of the molten material. The upper end portions of the decompression runners 40 and 41 are connected to gas gates 50 and 51 having a substantially circular cross section extending in a direction perpendicular to the contact surface 11 of the movable die 10 (direction perpendicular to the paper surface), The gas in the cavity 30 is sucked by a suction device (not shown) through the gas gates 50 and 51.

  As shown in FIG. 2, a sprue 60 having a substantially circular cross section extending in a direction perpendicular to the contact surface 21 of the fixed mold 20 (a direction perpendicular to the paper surface) is formed in the lower part of the fixed mold 20. A main runner 61 composed of two recessed runners is connected to the sprue 60. A cavity 31 having irregularities corresponding to the product shape of the cylinder block is formed in a portion sandwiched between the main runners 61 in the fixed mold 20. The cavity 31 is connected to the main runner 61. The fixed mold 20 has both upper corners cut, and suction devices 70 and 71 are fixed to the cut parts. In the vicinity of the center of each of the suction devices 70 and 71, suction holes 70a and 71a connected to the gas gates 50 and 51 in a state where the movable mold 10 and the fixed mold 20 are in contact with each other are formed. .

  Next, a process of casting a cylinder block using the movable mold 10 and the fixed mold 20 will be described with reference to FIG. 3A to 3C show the first to third steps in the cylinder block die casting method. FIG. 3 (a ') shows only the movable mold 10 of FIG. 3 (a).

  In the first step, the movable mold 10 is brought into contact with the fixed mold 20 as shown in FIG. At this time, the contact surface 11 of the movable mold 10 and the contact surface 21 of the fixed mold 20 are in close contact with each other so as not to leak the molten material, and are formed on the gas gates 50 and 51 and the suction devices 71 and 70 of the movable mold 10. The suction holes 71a and 70a thus connected are connected.

  In the second step, as shown in FIG. 3 (b), the gas in the cavities 30 and 31 is discharged by the suction devices 70 and 71, and an aluminum alloy as a molten material is pressurized and injected from the sprue 60. Here, the gas in the cavities 30 and 31 is continuously discharged during the pressure injection of the molten material into the mold. Thereafter, the movable mold 10 and the fixed mold 20 are cooled to mold the cylinder block. After the molding, the movable die 10 is removed from the fixed die 20 in a state where the cylinder block as a molded product is stuck to the movable die 10, and the state shown in FIG.

  In the third step, the molded product attached to the movable mold 10 is removed from the movable mold 10. At this time, by pulling a plurality of parts of the molded product that has been cast, an equal force is applied to each part, that is, a large force is not applied locally to prevent damage to the molded product. .

  In the present embodiment, the reinforcing member 80 is disposed on the decompression runners 40 and 41 of the movable mold 10 as shown in FIG. Details of the structure of the reinforcing member 80 will be described in detail with reference to FIG.

  As shown in FIG. 4A, the decompression runner 40 is formed with bent portions 40 a and 40 b and a “U” -shaped folded portion 40 c. A reinforcing member 80 made of a single member is disposed over the bent portions 40a and 40b and the folded portion 40c, that is, the entire decompression runner 40. The reinforcing member 80 is formed to be bent along the extending direction of the decompression runner 40, that is, bent at the bent portions 40a and 40b, and folded back into a U-shape at the folded portion 40c. The reinforcing member 80 is a rod-like member having a circular cross section, and is formed slightly narrower than the depth and width of the decompression runner so as to be accommodated in the decompression runner 40. The reinforcing member 80 is made of stainless steel, which is a material having higher toughness than the molten aluminum alloy. A Charpy impact test can be adopted as an evaluation method for toughness.

Then, with reference to FIG.4 (b), the structure of the reinforcement member 80 before arrange | positioning at the decompression runner 40 is demonstrated. In FIG. 4B, the broken line indicates the structure of the decompression runner 40.
As shown in FIG. 4B, the reinforcing member 80 is bent at an angle smaller than each angle of the bent portions 40a and 40b and the folded portion 40c of the decompression runner 40 before being disposed on the decompression runner 40. is doing. That is, when the reinforcing member 80 is disposed on the decompression runner 40, the reinforcing member 80 is disposed by being elastically deformed according to the shape of the decompression runner 40. For this reason, in a state where the reinforcing member 80 is disposed on the decompression runner 40, the reinforcing member 80 sandwiches the bent portions 40a and 40b and the folded portion 40c of the decompression runner 40.

It should be noted that the decompression runner 41 is provided with a reinforcing member 80 so that the front and back sides of the decompression runner 40 are reversed.
As described above in detail, according to the present embodiment, the following effects can be obtained.

  (1) Since the molten member is pressurized and injected into the movable mold 10 and the fixed mold 20 after the reinforcing member 80 is disposed on the decompression runners 40 and 41, portions corresponding to the decompressed runners 40 and 41 after casting by the reinforcement member 80 ( Hereinafter, the strength of the reduced-pressure runner molded product) can be improved. As a result, when the molded product cast from the movable mold 10 is taken out, the reduced-pressure runner molded product is not easily broken, so that the reduced-pressure runner molded product remains in the movable mold 10.

  (2) Since the reinforcing member 80 is made of a material having higher toughness than the molten metal material, even if the reduced-pressure runner molded product is broken, the reinforcing member 80 is hardly cut. As a result, it is possible to further suppress the reduced pressure runner molded product from remaining in the movable mold 10.

(3) Since the reinforcing member 80 is also arranged at the curved portions of the decompression runners 40 and 41, it is possible to reinforce a portion where stress tends to concentrate when taking out the product from the movable mold 10.
(4) Since the reinforcing member 80 is configured and arranged by a single member extending along the shape of the decompression runners 40 and 41, the decompression runner is compared with a case where a plurality of reinforcing members are arranged in combination. It can suppress that a molded article bends between each reinforcement member.

(5) Since the reinforcing member 80 is disposed so as to sandwich a part of the movable mold 10, the reinforcing member 80 can be prevented from coming off the movable mold 10.
In addition, the said embodiment can also be implemented as the following forms which changed this suitably, for example.

  In the above embodiment, the reinforcing member 80 is disposed over the entire decompression runners 40 and 41. However, the reinforcement member 80 may be disposed only in the bent portion of the decompression runner. As shown in FIG. 5, reinforcing members 81 and 82 are disposed in the bent portions 40 a and 40 b and the folded portion 40 c of the decompression runner 40. As described above, since the reinforcing members 81 and 82 are disposed at least in the bent portions 40a and 40b and the folded portion 40c of the decompression runner 40, a portion where stress tends to concentrate when taking out a molded product cast from the movable mold 10 is provided. Can be reinforced.

  -In above-mentioned embodiment, although the reinforcement member 80 was comprised with the single member, you may comprise combining several members. In this case, for example, it can arrange | position so that some reinforcement members formed thinner than the said embodiment may overlap in the linear part of a decompression runner.

  In the above embodiment, the reinforcing member 80 is arranged on a part of the decompression runners 40, 41. However, the reinforcing member 80 may be arranged on the entire decompression runners 40, 41. In this case, it is possible to prevent a part of the reduced-pressure runner molded product from remaining in the movable mold 10.

  In the above embodiment, the decompression runners 40 and 41 are formed with a substantially uniform cross-sectional area. However, when the cross-sectional area of the decompression runner is not uniform, the reinforcing member is disposed in a portion where the cross-sectional area is minimum. You may do it. By disposing the reinforcing member in the portion where the cross-sectional area of the decompression runners 40 and 41 is minimized, it is possible to effectively reinforce the portion where the decompression runner molded product is easily broken.

  In the above embodiment, the reinforcing member 80 is formed of a stainless material that is tougher than an aluminum alloy that is a molten material, but may be formed of a brittle material or other materials. In short, any material that can reinforce the decompression runner portion of the product may be used.

  In the above embodiment, in a state where the reinforcing member 80 is disposed on the decompression runner 40, the reinforcing member 80 sandwiches the bent portions 40a, 40b and the folded portion 40c, but the reinforcing member 80 is not necessarily sandwiched in this way. It does not have to be formed.

  In the above-described embodiment, the reinforcing member 80 is a rod-shaped member having a circular cross section. However, the reinforcing member 80 is a member having another shape, for example, a rod-shaped member having a rectangular cross section, a plate-shaped member, or a hollow cylindrical member. There may be.

The front view which shows the structure of the movable mold | type used for the die-casting method concerning this invention. The front view which shows the structure of the fixed mold | type which the movable mold | type of FIG. 1 contacts. The perspective view which shows the process of the die-casting method. The front view which shows the structure of a reinforcement member. The front view which shows the modification of a reinforcement member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Movable type | mold, 11 ... Contact surface, 20 ... Fixed type | mold, 30, 31 ... Cavity, 40, 41 ... Decompression runner, 40a, 40b ... Bending part, 40c ... Folded part, 50, 51 ... Gas gate, 60 ... Sprue 61 ... master runner, 70, 71 ... suction device, 70a, 71a ... suction hole, 80, 81, 82 ... reinforcing member.

Claims (7)

In the die casting method in which the gas in the mold is exhausted through the mold runner and the molten metal is pressurized and injected into the mold.
A die-casting method, wherein a reinforcing member extending along the extending direction of the runner is disposed in the runner, and then the molten metal is injected under pressure into the mold. In the die casting method according to claim 1,
The die-casting method, wherein the reinforcing member is formed of a material having higher toughness than the molten metal material. In the die-casting method according to claim 1 or 2,
The die casting method, wherein the reinforcing member is disposed at least in a curved portion of the runner. In the die-casting method according to claim 1 or 2,
The die casting method, wherein the reinforcing member is disposed on the entire runner. In the die-casting method according to claim 1 or 2,
The die casting method, wherein the reinforcing member is disposed in a portion where the cross-sectional area of the runner is minimized. In the die casting method according to any one of claims 1 to 5,
The die-casting method, wherein the reinforcing member is a single member. In the die casting method according to any one of claims 1 to 6,
Die casting method characterized by that be placed on the runners of the reinforcing member while elastically deforming in accordance with the shape of the runner.

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