JP2008284555A - Die for die casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die for die casting, which die can improve its cooling performance without lowering its safety performance. <P>SOLUTION: The die 1 for die casting comprises a cooling portion 100 composed of an outer member 101 having a surface 107 to be brought into contact with molten metal, and an inner member 103 which is formed such that its one surface side is buried in the outer member 101 on the opposite side of the surface 107 of the outer member 101 to be brought into contact with molten metal, and is composed of a copper member provided with a cooling water flowing portion 102 on the opposite surface side of the outer member 101. The cooling portion 100 comprises an interface layer portion 104 between the outer member 101 and the inner member 103, wherein interface layer portion 104 has the heat conductivity higher than that of the outer member 101, and has particles. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a die-casting mold, and in particular, has improved cooling performance without deteriorating safety performance.

  The conventional die casting mold is provided with a cooling water passage for passing cooling water through the mold in order to solidify the molten metal injected into the cavity. It is necessary to increase the thickness of the mold so that the molten metal (hereinafter referred to as “molten metal”) injected at high speed by the plunger tip and collided with high pressure can withstand this pressing. is there. For this reason, the conventional die casting mold has a problem that even if the cooling water is passed through the cooling water passage, the distance from the cooling water to the molten metal contact surface is long and a desired cooling effect cannot be obtained. . Therefore, in Patent Document 1, as a technique for solving such a problem, the thickness of the mold at the portion where the molten metal comes into contact is relatively thin (5 to 15 mm). By installing a member that supports the inside from the inside, the strength of the die casting mold is ensured and the cooling performance is compatible.

Japanese Patent Laying-Open No. 2005-74445 (page 4, lines 37 to 44, FIG. 3)

  Since the conventional die casting mold is composed of a thin single member between the cooling water and the molten metal contact surface, when a crack is generated or progresses in the die casting mold, the cooling water passage and the molten metal are not formed. There was a problem that the injected cavity communicated with each other, and cooling water was ejected into the cavity, making it impossible to die-cast. Further, there has been a problem that a steam explosion may occur due to contact between the jetted water and the molten metal.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a die casting mold that can improve cooling performance without deteriorating safety performance.

According to the present invention, an outer member having a surface with which the molten metal comes into contact, and a surface through which the molten metal of the outer member is opposed to the surface with which the molten metal comes into contact are embedded, and a cooling water passage portion is formed on the side opposite to the outer member. In a die-casting die provided with a cooling part constituted by an inner member constituted by provided copper or copper alloy,
The cooling part includes an interface layer part having a thermal conductivity higher than that of the outer member and having particles between the outer member and the inner member.

The die casting mold according to the present invention includes an outer member having a surface in contact with the molten metal, and a cooling water on a surface side opposite to the outer member formed by embedding one surface side on the surface side opposite to the surface in contact with the molten metal of the outer member. In a die-casting die having a cooling part constituted by an inner member constituted by copper or a copper alloy provided with a water passage part,
The cooling part has a higher thermal conductivity than that of the outer member between the outer member and the inner member, and has an interface layer part having particles, so that the cooling performance is improved without deteriorating the safety performance. .

Embodiment 1 FIG.
Embodiments of the present invention will be described below. 1 is a cross-sectional view showing the configuration of a cooling unit of a die-casting die according to Embodiment 1 of the present invention, FIG. 2 is a diagram showing a table for showing the effectiveness of the die-casting die shown in FIG. 3 and 4 are cross-sectional views showing the installation positions of the die casting molds of the cooling section shown in FIG. In this example, a diverter mold that is a part of a die casting mold having a clamping force of 350 tons will be described as an example. (Note that the “flow diverter mold” refers to the molten metal injected by the plunger tip from the sleeve to the cavity. This is a mold part that serves to diverge into a plurality of communicating runners.) In the figure, the cooling part 100 of the die-casting die 1 is formed by embedding one side of the outer member 101 having a surface 107 in contact with the molten metal and the surface of the outer member 101 opposite to the surface 107 in contact with the molten metal. An inner member 103, a cooling water passage portion 102 for passing cooling water on a surface side opposite to the outer member 101 of the inner member 103, and an outer side between the outer member 101 and the inner member 103. The thermal conductivity of the member 103 is higher than that of the member 103, and the interface layer portion 104 includes particles.

The outer member 101 is made of, for example, a hot-work tool steel SKD61 material (thermal conductivity 27 W / (m · K)), which is generally used as the die casting mold 1. Further, the inner member 103 uses, for example, pure copper having high thermal conductivity (“pure copper” is, for example, industrial pure copper “tough pitch copper (JIS C1100)”, and has a thermal conductivity of 390 W / (m · K). ). In addition, it can also be comprised with a copper alloy. Then, in the first embodiment, the portion where the molten metal of the outer member 101 contacts the wall thickness t ₁ has about 5 mm, also the cooling water passage of water 102 of the inner member 103 distal the outer member 101 thick _{t 2} of the opposing surface of the surface 107 of molten metal is in contact has approximately 10 mm. For example, a spot-type cooling pipe 108 is inserted into the cooling water passage portion 102 of the inner member 103, and the heat input from the molten metal is exhausted by the circulating cooling water. Further, the thickness of the interface layer portion 104 is about 0.1 mm ± 0.05 mm because of the clearance when the inner member 103 of the outer member 101 is inserted.

Next, a method for manufacturing cooling unit 100 according to Embodiment 1 configured as described above will be described. A recess for embedding the inner member 103 is formed on the side of the outer member 101 opposite to the surface 107 with which the molten metal contacts. Then, for example, boron nitride (BN), graphite (C), or molybdenum disulfide (MoS ₂ ) having an average particle diameter of about 10 μm is spray-applied to the recess. At this time, for example, when particles of boron nitride, graphite, molybdenum disulfide, etc. are sprayed in a state dispersed in butyl acetate, the butyl acetate is vaporized without remaining, boron nitride, graphite, molybdenum disulfide, etc. Only the remaining particles remain. Next, the inner member 103 was inserted so as to be embedded in the outer member 101, and the interface layer portion 104 was filled between the outer member 101 and the inner member 103. Here, in the case of a member having particles, the member having particles is dispersed in a solvent such as butyl acetate as described above, and spraying by spray coating can be easily performed. There is very little possibility of solvent remaining after spraying. Compared to this, in the case of a dissolving member in a state dissolved in a solvent, there is a high possibility that the solvent will remain after application, and the solvent is likely to cause a problem in heat conduction. For this reason, it is considered that a member having particles is suitable.

Note that the interface layer portion 104 (lamination thickness of the particles) has a thickness of about 0.15 mm in actual measurement. In the above description, the example in which the inner member 103 is inserted into the recess of the outer member 101 is shown. However, the inner member 103 is caulked by deforming the end of the inner member 103 with a press machine or the like. It is also possible to manufacture the fixing of the member 103 to the outer member 101 more reliably. Here, an example in which the interface layer portion 104 is made of boron nitride (BN), graphite (C), or molybdenum disulfide (MoS ₂ ) is shown, but the present invention is not limited to this, and the outer member 101 is not limited thereto. The same effect can be obtained if the thermal conductivity is higher than the thermal conductivity of and the interface layer portion 104 having particles can be formed.

  Next, with respect to the cooling unit 100 and the comparative example in the first embodiment configured as described above, a constant heat input 300 W is applied from the surface 107 with which the molten metal contacts using a heater, and the thermal resistance value (heat The resistance value is a temperature rise value when a heat amount of 1 W is applied). As a result, measured values as shown in FIG. 2 were obtained. That is, since the interface layer portion 104 is made of boron nitride (Example 1), graphite (Example 2), or molybdenum disulfide (Example 3), compared with the case of a void (Comparative Example), the thermal resistance is reduced. It was confirmed that it was greatly reduced. As a result, the cooling performance of the cooling unit 100 is greatly improved.

  The specific arrangement | positioning location to the die-casting die 1 of the cooling unit 100 comprised in this way is demonstrated. First, as shown in FIG. 3, the molten metal injected at high speed by the plunger tip 201 is disposed at a position where it is branched into a runner communicating with the cavity 202. In actual casting, this is called biscuit 203 after casting (in the case of a 350-ton die casting machine). A method of taking out from the die casting mold 1 is generally employed. Usually, this biscuit 203 is the place where the heat capacity is the largest in the product, and the place where the time to complete solidification is the longest. If the product is taken out before this part is completely solidified, the robot cannot grasp the surplus portion and the product cannot be taken out from the mold. Therefore, it is necessary to take out the product from the mold after waiting for the solidification of the surplus portion. That is, this part becomes the rate-determining part of the cycle time.

  Therefore, the cooling unit 100 is disposed in this portion in the first embodiment, and as described above, the cooling capacity is higher than that of the conventional shunt 61 composed of a single SKD61 material. Solidification of the biscuits 203 having a large heat capacity can be promoted as compared with the conventional case. As a result, the cycle time can be shortened. Thereby, the productivity can be greatly improved, and the unit price per product can be reduced.

  As another example, for example, as shown in FIG. 4, it is possible to apply the cooling unit 100 to a part constituting a mold cavity 102 (“product part cavity”) that forms a product part. Although the shape of the cooling unit 100 is slightly different from that in FIG. 1, it goes without saying that the same reference numerals are formed in the same manner. Thus, by applying the cooling part 100 of the die casting mold 1 to the mold cavity 102, it becomes possible to shorten the solidification time (chill time) of the product part. The reduction effect is great.

  In the die-casting die according to the first embodiment configured as described above, even when a clearance gap remains between the outer member and the inner member in the cooling portion, an interface layer portion is formed in the gap. Therefore, a desired cooling performance can be obtained. In addition, since the interface layer portion is filled between the outer member and the inner member, the processing accuracy of the outer member and the inner member can be reduced, so that the processing cost of the mold can be reduced. Further, the inner member provided with the cooling water passage portion has a large elongation of pure copper or a copper alloy and is made of a material having better corrosion resistance than the steel material. Therefore, compared with the conventional SKD61 material, the cooling water passage portion is provided. There is also an advantage that cracks are difficult to enter in the part. In addition, even if a crack occurs in the outer member, the cooling water water passing portion is covered with the inner member, so that the cooling water does not spout onto the surface that contacts the molten metal, thereby improving the safety of the casting operation. be able to. Further, since the cooling water does not come into contact with the outer member, stress corrosion cracking of the outer member can be suppressed, and a long life of the die casting mold can be expected.

It is sectional drawing which shows the structure of the cooling part of the die-casting die by Embodiment 1 of this invention. It is the figure which showed the table | surface for showing the effectiveness of the die-casting die shown in FIG. It is sectional drawing which shows the installation position of the die-casting die of the cooling unit shown in FIG. It is sectional drawing which shows the installation position of the die-casting die of the cooling unit shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die-cast metal mold | die, 100 cooling part, 101 outer member, 102 cooling water water flow part,
103 Inner member, 104 Interface layer part, 107 Surface where molten metal contacts.

Claims (2)

An outer member having a surface in contact with the molten metal, and a surface of the outer member opposite to the surface in contact with the molten metal is formed by embedding one surface side, and a cooling water passage portion is provided on the surface opposite to the outer member. In a die-casting die provided with a cooling part composed of an inner member composed of copper or a copper alloy,
The die casting mold, wherein the cooling part includes an interface layer part having a higher thermal conductivity than the outer member and having particles between the outer member and the inner member. 2. The die casting mold according to claim 1, wherein the interface layer portion includes particles of at least one of boron nitride, graphite, or molybdenum disulfide.

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