JP2014117729A - Die casting production method and die-casting die for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die-casting die provided with a pressure pin carrying out secondary pressure application of a molten metal which reduces the cost of a bush holding the pressure pin and facilitates replacement work.SOLUTION: A bush holding hole 20 formed near a shaped surface 13 of a movable mold 12 is opened to the shaped surface 13. A bush 30 is tapered, with its front end outside diameter as the smallest diameter corresponding to the opening of the bush holding hole, and provided with a flange at its rear end and has a through hole 36 through which a pressure pin 5 is slidable. The inner peripheral surface of the bush holding hole is tapered so as to correspond to the outer shape of the bush and has a flange housing part receiving the flange. The bush 30 is diameter-reduced elastically and inserted from the opening of the bush holding hole to make held in the bush holding hole. Compared with a bush attached from the outside wall 14 of the movable mold 12, the bush is small-sized, achieves cost reduction and facilitates replacement work because of being removable from the opening of the shaped surface 13 on the parting surface side with e.g. a pench.

Description

  The present invention relates to a method for manufacturing a die-cast product and a die-casting die used for die casting.

Die-cast products such as aluminum are manufactured by pressurizing molten metal into the cavity formed between the movable mold and fixed mold of the opposing mold, but if the die-cast product has a thick part such as a boss, In order to suppress the formation of nests caused by air, a squeeze method is used in which a pressurizing pin is inserted into the thick-walled portion forming portion of the cavity after the molten metal is filled to perform secondary pressurization.
In carrying out this construction method, for example, as disclosed in Japanese Patent Application Laid-Open No. 2009-148806, when the pressure pin is reciprocated with respect to the mold (movable mold), the sliding portions wear out. In general, a bush is attached to the pressure pin and the pressure pin reciprocates in the hole of the bush.

In the one disclosed in Japanese Patent Application Laid-Open No. 2009-148806, as shown in FIG. 7, the bush holding hole 20 ′ penetrates from the outer wall 14 of the movable mold 12 ′ to the shape surface 13 facing the cavity 17. The opening end on the outer wall 14 side of 20 ′ is a large-diameter flange accommodating portion 24 ′.
The bush 30 ′ has a small diameter portion 32 ′ having an outer diameter aligned with the bush holding hole 20 ′, and a large diameter portion 34 ′ (flange) corresponding to the flange accommodating portion 24 ′ at the outer end thereof. There is a through hole 36 ′ through which the pressure pin 5 can reciprocate through the portion 32 ′ and the large diameter portion 34 ′.
With the small diameter portion 32 ′ of the bush 30 ′ inserted into the bush holding hole 20 ′ and the large diameter portion 34 ′ seated on the stepped portion of the bush holding hole 20 ′, the tip of the bush 30 ′ (small diameter portion 32 ′) is It is set so as to be flush with the shape surface 13 of the thick part forming portion of the movable mold 12 ′. The bush 30 ′ maintains this state in which the large-diameter portion 34 ′ is seated on the stepped portion by a fixing member (not shown).

When manufacturing the die-cast product, after the molten metal is filled into the cavity 17 including the thick portion forming portion, the pressure pin 5 held in the through hole 36 ′ of the bush 30 ′ is set at a predetermined timing in the cooling process of the molten metal. In FIG. 2, a secondary pressurization is performed by causing the hydraulic cylinder (not shown) to slide from the retracted position indicated by the solid line to the advanced position indicated by the phantom line of the thick portion forming portion.
After cooling, the pressure pin 5 is retracted, the movable mold 12 ′ is separated from the fixed mold 11, and the product is taken out from the movable mold 12 ′ by pushing out with a push pin (not shown).

JP 2009-148806 A

By providing the bush 30 ′ as described above, wear on the mold side of the sliding portion of the pressure pin 5 is prevented, but the bush 30 ′ in direct contact with the pressure pin 5 is particularly molten metal flowing into the cavity 17. Since the inner end side (the shape surface 13 side) that is susceptible to the impact is worn out, the bush 30 'needs to be replaced.
Here, since the conventional bush 30 ′ is inserted and attached from the outer wall 14 side of the movable mold 12 ′, it is a large size having a length extending from the shape surface 13 to the outer wall 14 of the movable mold 12 ′, and is a consumable part. It has become a high thing. Similarly, the bush 30 ′ is configured to be inserted and extracted from the outer wall 14 side of the movable mold 12 ′, and each time replacement is performed, the fixing member and the like holding the bush 30 ′ must be removed and reattached. It takes a lot of man-hours to replace 30 '.

  Therefore, in view of the above-described problems, an object of the present invention is to provide a method of manufacturing a die-cast product in which a bush for squeeze is lower in cost and easy to replace, and a die-casting die used therefor.

  For this reason, the method for producing a die-cast product according to the present invention includes a bush holding a through hole in which a pressurizing pin for secondary pressurization of a molten metal is slidable and formed near the shape surface of the mold and opened to the shape surface. The bush holding hole has a flange accommodating portion having a diameter larger than that of the opening, and the bush has a flange received in the flange accommodating portion, and the bush is elastically reduced in diameter so that the bush is opened from the opening. The bush was inserted into the holding hole, and then the bush was elastically expanded in the flange housing portion to prevent the bush from coming off from the bush holding hole.

  In addition, the die-cast mold is formed by elastically reducing the diameter of a bush having a through-hole through which a pressure pin can slide in a bush holding hole formed near the shape surface of the mold and having an opening in the shape surface. The bush holding hole has a flange accommodating portion having a diameter larger than that of the opening, and the bush has a flange received in the flange accommodating portion, and is prevented from being detached from the bush holding hole. It was supposed to be.

  According to the manufacturing method and the die-casting mold of the present invention, the bush is reduced in size and reduced in cost compared to the one that is mounted from the outer wall side of the mold, and the mounting is also possible from the opening of the shape surface on the parting surface side and the removal is This makes it easy to replace.

It is a fragmentary sectional view of the metal mold | die which shows the structure of embodiment. It is an enlarged view which shows a bush. It is an expanded sectional view which shows the bush holding hole in a movable type. It is a figure which shows the diameter reduction point at the time of inserting a bush into a bush holding hole. It is explanatory drawing which shows the relationship between the hole formed in a die-cast article, and the opening diameter of a bush holding hole. It is a figure which shows the extraction point at the time of bush replacement | exchange. It is a figure which shows a prior art example.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a partial cross-sectional view of a mold according to an embodiment.
The mold 10 is composed of a fixed mold 11 and a movable mold 12 which are arranged opposite to each other to form a cavity 17, and the figure shows a portion around a boss portion 42 (see FIG. 5) as a thick portion. It is assumed that a hole 44 (see FIG. 5) is formed at the center of the portion 42.
The movable die 12 is formed with a guide hole 15 extending from the outer wall 14 side toward the center of the boss portion 42 forming portion and penetrating the pressurizing pin 5, and a predetermined range is expanded from the shape surface 13 facing the cavity 17. Bush holding hole 20 is formed. The bush 30 held in the bush holding hole 20 has a through hole 36 concentric with the guide hole 15 and holds the pressure pin 5 so as to be slidable.

2 is an enlarged view of the bush 30, (a) is a front view, (b) is a cross-sectional view taken along the line AA in (a), and (c) is a rear view.
The bush 30 is formed of a heat resistant spring material made of alloy tool steel or stainless steel, and has high elasticity.
The outer shape of the bush 30 has a tapered shape with a front end at the minimum diameter Da, a conical surface that increases in diameter toward the rear, and a large diameter portion 34 having a predetermined axial width W at the rear end. Hereinafter, the front side of the large diameter portion 34 is referred to as a tapered small diameter portion 32.
For example, the overall length L of the bush 30 is 12 mm, the diameter Db of the through hole 36 is 8 mm corresponding to the pressure pin 5, the outer diameter (Da) of the front end is 9 mm, the length of the tapered small diameter portion 32 is 10 mm, The inclination is 5 °, the width W of the large diameter portion 34 is 2 mm, and the outer diameter Dc is 11.76 mm. The height in the radial direction of the step portion 33 between the tapered small diameter portion 32 and the large diameter portion 34 is 0.5 mm, and the large diameter portion 34 is a flange with respect to the tapered small diameter portion 32.
The bush 30 is provided with a slit 38 having a width S over the entire length at one circumferential direction.

FIG. 3 is an enlarged cross-sectional view of the bush holding hole 20 portion of the movable mold 12.
The bush holding hole 20 corresponds to the outer shape of the bush 30, and accommodates the tapered portion 22 that opens at the shape surface 13 with the minimum diameter Da of the bush 30 and aligns with the tapered small diameter portion 32, and the large diameter portion 34 of the bush 30. In the axial direction, the flange housing portion 24 is longer than the width W of the large diameter portion 34 by a predetermined amount.
The bush 30 disposed in the flange accommodating portion 24 has a front end edge that is flush with the shape surface 13 when the large diameter portion 34 (flange) is seated on the step portion 23 between the flange accommodating portion 24 and the tapered portion 22. .

In order to arrange the bush 30 in the bush holding hole 20, as shown in FIG. 4, one end in the circumferential direction facing the cut portion 38 of the bush 30 is rounded inside the other end to open the bush holding hole 20 in the shape surface 13. The diameter is reduced to the diameter (Da), and the large-diameter portion 34 is first inserted through the opening 21 of the shape surface 13 and incorporated. That is, it is attached from the parting surface side opposite to the outer wall 14 of the movable mold 12.
The inserted bush 30 expands due to elasticity and returns to the initial shape, the tapered small diameter portion 32 is positioned at the tapered portion 22 of the bush holding hole 20, and the large diameter portion 34 is received by the flange accommodating portion 24.
Accordingly, the pressure pin 5 from the outer wall 14 side of the movable mold 12 extends into the through hole 36 of the bush 30 through the guide hole 15. (See Figure 1)

In the mold 10 having the above-described configuration, when the pressure pin 5 enters the molten metal filled in the cavity 17 at the boss portion 42 formation portion from the shape surface 13, the bush 30 is attached to the shape surface 13 side by friction. Be forced. For this reason, even if the large-diameter portion 34 of the bush 30 is located closer to the outer wall 14 in the flange accommodating portion 24, the flange (large-diameter portion 34) is directed toward the shape surface 13 until the flange (large-diameter portion 34) is engaged with the step portion 23. Moving. (See Figure 1)
During this time, the taper small diameter portion 32 receives a compressive force in the direction of diameter reduction due to the wedge effect with the taper portion 22 of the bush holding hole 20, and the inner peripheral surface of the taper portion 22 and the outer peripheral surface of the taper small diameter portion 32 are in close contact with each other. The inner peripheral surface of the through hole 36 and the outer peripheral surface of the pressure pin 5 are also in close contact. Thereby, in the shape surface 13, the clearance gap between each surface of the movable mold | type 12 (bush holding hole 20), the bush 30, and the pressurization pin 5 becomes zero or very small, and generation | occurrence | production of a burr | flash can be prevented.

Note that the minimum outer diameter of the tapered small diameter portion 32 of the bush 30, and hence the opening diameter (Da) of the bush holding hole 20 in the shape surface 13, is a chamfered portion formed in the boss portion 42 of the die cast product 40 as shown in FIG. 5. 45 is set to be smaller than the maximum diameter Dd of the hole 44 including 45. In FIG. 5, the movable mold 12, the bush 30, and the pressure pin 5 are indicated by phantom lines.
As a result, even if burrs are generated due to gaps between the surfaces of the movable die 12, the bush 30 and the pressure pin 5 on the shape surface 13, the burrs enter the cutting range when the hole 44 is processed and simultaneously with the processing. Since it is cut off, it is not necessary to separately cut the end face of the boss portion 42 only for removing burrs.

Next, when the bush 30 is replaced in accordance with wear of the through-hole 36 or the like, first, as shown in FIG. 6A, from the opening 21 of the bush holding hole 20 in the shape surface 13 of the movable mold 12. Insert a flathead screwdriver 7 or the like between the tapered small diameter portion 32 (the outer peripheral surface) of the bush 30 and the tapered portion 22 (the inner peripheral surface) of the bush holding hole 20, and one end of the cut 38 portion is inserted into the bush holding hole 20. Float from the inner surface. Then, the lifted portion is gripped with pliers 8.
Then, as shown in (b), the bush 30 is wound around the pliers 8 to have a reduced diameter, and extracted from the opening 21 of the bush holding hole 20. Since the worn bush 30 is already unusable, there is no problem even if the bush 30 is broken by winding or winding.

  In the present embodiment, the large diameter portion 34 corresponds to the flange in the invention. Moreover, the boss | hub part 42 corresponds to a thick part.

The embodiment is configured as described above, the bush holding hole 20 is formed near the shape surface 13 in the movable mold 12 and is opened in the shape surface 13, and the pressure pin 5 for secondary pressurization of the molten metal is slidable. The bush 30 having the through hole 36 is elastically reduced in diameter, inserted from the opening, and held in the bush holding hole 20. The bush holding hole 20 has a flange accommodating portion 24 having a diameter larger than that of the opening. Since the large-diameter portion 34 is received in the flange accommodating portion 24, the bush 30 inserted into the bush holding hole 20 is elastically expanded in diameter and is prevented from coming off.
As a result, the bush 30 is smaller in size than the one attached from the outer wall 14 side of the movable mold 12 and the cost is reduced, and the replacement work is also easy because it can be extracted from the opening of the shape surface 13 on the parting surface side with pliers or the like. It becomes.
(Effects corresponding to claims 1 and 4)

  Since the bush 30 has a slit 38 extending over the entire length at one place in the circumferential direction, when inserted into the bush holding hole 20, it is possible to easily reduce the diameter by winding one end opposed to the other inside the slit 38. it can. (Effects corresponding to claims 2 and 6)

The bush 30 has a tapered shape with the outer diameter of the front end corresponding to the minimum diameter corresponding to the opening 21 of the bush holding hole 20, and has a large diameter portion 34 at the rear end, while the bush holding hole 20 is connected to the opening 21. Since the peripheral surface is tapered corresponding to the bush 30, if the bush 30 is inserted into the bush holding hole 20 from its rear end, the large diameter portion 34 is received in the flange accommodating portion 24 and at the same time, the bush 30 expands in diameter. The tapered outer peripheral surface is aligned with the tapered inner peripheral surface of the flange accommodating portion 24.
For this reason, when the bush 30 is urged and moved by the pressure pin 5 entering the molten metal in the cavity 17, it receives a compressive force in the direction of diameter reduction due to the wedge effect due to the taper. As a result, the bush holding hole 20, the bush 30 and the pressure pin 5 in the shape surface 13 are in close contact with each other, and the gap between each surface becomes zero or very small, thereby preventing the occurrence of burrs.
(Effects corresponding to claims 3 and 5)

  The shape surface 13 of the movable mold 12 is a surface corresponding to the end surface of the boss portion 42 in which the hole 44 is processed in the end surface of the die cast product 40, and the opening 21 of the bush holding hole 20 is smaller in diameter than the maximum diameter of the hole 44. Since it is set, even if a gap is generated between the bush holding hole 20 and the bush 30 and a burr is generated, it is cut off simultaneously with the processing of the hole 44. End face cutting is not required. (Effect corresponding to claim 7)

  In the embodiment, the pressure pin 5 is made to enter the cavity 17 from the movable mold 12 and the bush 30 is held by the movable mold 12. However, the present invention is not limited to this, and the present invention is not limited to this. 11 is also applied to the configuration in which the pressure pin 5 is moved into the cavity 17 from the fixed mold 11 while being held by the wire 11.

DESCRIPTION OF SYMBOLS 5 Pressure pin 7 Negative driver 8 Plier 10 Mold 11 Fixed type 12 Movable type 13 Shape surface 14 Outer wall 15 Guide hole 17 Cavity 20 Bush holding hole 21 Opening 22 Taper part 23 Step part 24 Flange accommodating part 30 Bushing 32 Tapered small diameter part 33 Stepped portion 34 Large diameter portion 36 Through hole 38 Cutting 40 Die-cast product 42 Boss portion 44 Hole 45 Chamfered portion

Claims (7)

In the method of manufacturing a die-cast product in which the molten metal is secondarily pressed with a pressure pin and cast,
A bush having a through-hole through which the pressure pin can slide is held in a bush holding hole formed near the shape surface of the mold and opened in the shape surface,
The bush holding hole has a flange accommodating portion having a larger diameter than the opening,
The bush has a flange received in the flange receiving portion,
The bush is elastically reduced in diameter and inserted from the opening into the bush holding hole, and then the flange is elastically expanded in the flange housing portion to prevent the bush from coming off from the bush holding hole. A method for producing a die-cast product, characterized in that: 2. The method for producing a die-cast product according to claim 1, wherein the bush is provided with a cut extending over the entire length, and one end opposed to the cut is wound inside the other end to reduce the diameter. The bush is tapered so that the outer diameter of the front end corresponds to the minimum diameter corresponding to the opening of the bush holding hole, and the flange is provided at the rear end.
The bush holding hole has an inner peripheral surface connected to the opening having a tapered shape corresponding to the bush,
3. The method for manufacturing a die-cast product according to claim 1, wherein the bush is inserted into the bush holding hole from the rear end. A die-casting die having a pressure pin for secondary pressurization of molten metal,
A bush having a through hole through which the pressure pin can slide is inserted into the bush holding hole formed near the shape surface of the mold and having an opening in the shape surface, and inserted through the opening. Hold
The bush holding hole has a flange accommodating portion having a larger diameter than the opening,
The die casting mold according to claim 1, wherein the bush has a flange received in the flange housing portion and is prevented from being detached from the bush holding hole. The bush is tapered so that the outer diameter of the front end corresponds to the minimum diameter corresponding to the opening of the bush holding hole, and the flange is provided at the rear end.
The die-casting die according to claim 4, wherein the bush holding hole has an inner peripheral surface continuous with the opening having a tapered shape corresponding to the bush. The die-casting die according to claim 4 or 5, wherein the bush has a slit extending over the entire length in one circumferential direction. The shape surface is a surface corresponding to the end surface of the thick portion where a hole is processed in the end surface of the die-cast product,
The die casting mold according to any one of claims 4 to 6, wherein the opening of the bush holding hole has a smaller diameter than the maximum diameter of the hole.

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