JP2005177834A - Die casting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an aluminum die-cast product with which the partial variations of the characteristic can widely be realized and the sticking force between the partial parts is excellent and the escalation of production cost is not developed. <P>SOLUTION: A die casting method is provided with a first process for inserting a metal-made insert member M1 into a cavity C; a second process for applying the pressure to molten metal while pouring the molten metal M2 having different component to the insert member M1 and aluminum as the principle component into the cavity C; and a third process for obtaining the aluminum die-cast product P by solidifying the molten metal M2 in the cavity C. In the second process, the insert member M1 is induction-heated with a high frequency coil 2a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a die casting method.

  A general aluminum die-cast product consists of a base material formed by a molten metal obtained by melting a single type of aluminum alloy. Such an aluminum die-cast product is manufactured as follows (see, for example, Non-Patent Document 1). That is, first, a die casting die for forming a cavity communicating with the pressure inlet is prepared. Next, pressure is applied to the molten metal while pouring the molten metal into the cavity. Then, the molten metal is solidified in the cavity to form a base material. The aluminum die-cast product obtained in this way is used for many parts such as a compressor housing and a piston, which have a certain degree of strength and require light weight.

  Also known is an aluminum die-cast product in which a base material having a component different from that of a base material made of molten metal is inserted as an insert member. Such an aluminum die-cast product is manufactured as follows (see, for example, Non-Patent Document 2). Also in this case, first, a die casting mold for forming a cavity communicating with the pressure inlet is prepared. Next, after inserting an insert member into the cavity, pressure is applied to the molten metal while pouring the molten metal into the cavity. Then, the molten metal is solidified in the cavity to form a base material. Aluminum die cast products obtained in this way are also used for many parts.

Tomonobu Kanno and Yuzo Uehara “Introduction to Die Casting Technology-Second Edition”, Nikkan Kogyo Shimbun, December 18, 1997, P.I. 1-4 Takahashi Kiyoshi, Arai Kazuyoshi, Miyata Kiyozo and Yanagida Hiroaki “Industrial Materials Dictionary” Industrial Research Committee, October 20, 1997 105

  However, in general aluminum die-cast products formed only from a single type of molten metal, the base material formed by that molten metal is a single type, so the strength, wear resistance, thermal conductivity, wire, Physical or mechanical properties such as thermal expansion coefficient and workability are limited, and partially different physical or mechanical properties cannot be exhibited. When such partial characteristic changes are to be made, it is necessary to join members made of other components to the aluminum die-cast product, or to perform surface treatment such as plating or coating. In some cases, there is concern about the adhesion between the base material and these materials. In this case, an increase in manufacturing process is inevitable, resulting in an increase in manufacturing cost.

  In this regard, if an aluminum die-cast product with an insert member having a different component from that of the molten base material, the physical or mechanical characteristics partially differ depending on the base material made of the molten metal and the base material made of the insert member. Will be demonstrated. In this case, although there is a trouble of providing the insert member in the cavity, the manufacturing process is not increased so much and the manufacturing cost is not increased so much. However, according to the test results of the inventors, the aluminum die cast product thus obtained does not necessarily have sufficient adhesion between the base material and the insert member.

  Japanese Patent Laid-Open No. 2000-280277 discloses a mold and a method for forming two layers integrally with, for example, a molten magnesium and an unsolidified resin. However, this technique uses a different material having different main components such as magnesium and resin as a base material, and only uses a greatly different characteristic difference between different materials. For this reason, when manufacturing aluminum die-cast products that use the same type of material, the main component of which is aluminum, as the base material, the difference in characteristics between the same type of materials is not as great as that between different types of materials, and this technology is used as is. Can not do it.

  Moreover, as described in Japanese Utility Model Publication No. 61-55188, the first base material formed by the first mixed powder and the first base material are integrally formed. It is also conceivable to use a sintered product composed of a second base material formed of different second mixed powders. In this sintered product, a first green compact made of a first mixed powder and a second green compact made of a second mixed powder are integrally molded by a cold isostatic pressure (CIP) molding method to form a composite green compact. After the body is obtained, the composite green compact is obtained by hot extrusion using a die having a die straddling the first green compact and the second green compact. Since the sintered product obtained in this manner is formed integrally while the components of the first base material and the second base material are different, there is no separation between the first base material and the second base material. , Partial property changes can be realized. However, such a sintered product is difficult to be formed into a complicated shape and needs to be made into a powder at the time of manufacture, which is disadvantageous in terms of manufacturing cost as compared with a cast product such as an aluminum die-cast product.

  Further, as described in JP-A-10-288079 and JP-A-10-323747, hard particles in the molten metal are partially aggregated by a filter medium while using a single molten metal. It is also possible to use an aluminum die-cast product. Partial changes in characteristics can also be realized by the aluminum die-cast product thus obtained. However, this aluminum die-cast product can realize only partial improvement in wear resistance due to aggregation of hard particles, and cannot realize partial changes in other characteristics.

  The present invention has been made in view of the above-described conventional situation, and is capable of realizing a wide range of partial changes in characteristics, having excellent adhesion between the portions, and not causing an increase in manufacturing cost. Obtaining die-cast products is an issue to be solved.

  The inventors have intensively studied to solve the above problems. As a result, it was confirmed that an aluminum die-cast product having an insert member is effective for realizing a partial change in characteristics widely. However, aluminum die-cast products with conventional insert members use insert members that have been molded and cooled to room temperature, and the molten metal is poured while the insert members in the cavities remain at about room temperature. It was confirmed that the adhesion between the base material and the insert member was not always sufficient. One of the causes is that a strong oxide film exists on the surface of the insert member cooled to room temperature, and another reason is that the molten metal is poured while the insert member in the cavity remains at room temperature. However, they discovered that such an oxide film cannot be destroyed. Thus, the present invention has been completed.

The die casting method of the present invention includes a first step of inserting a metal insert member in the cavity,
A second step of applying pressure to the molten metal while pouring a molten metal whose main component is aluminum, different from the insert member in the cavity;
And a third step of solidifying the molten metal in the cavity to obtain an aluminum die cast product, wherein the insert member is heated in the first step and / or the second step.

  In this die casting method, first, in a first step, a metal insert member is inserted into the cavity. And in a 2nd process, a component differs from an insert member in a cavity, and pressure is applied to a molten metal, pouring the molten metal whose main component is aluminum. In the first step and / or the second step, since the insert member is heated, the oxide film once formed is easily broken by the molten metal. Thereafter, in the third step, the molten metal is solidified in the cavity to obtain an aluminum die cast product.

  In the aluminum die cast product thus obtained, the first base material is formed by the insert member, and the second base material is formed by the molten metal. This aluminum die-cast product has different characteristics such as partial strength, wear resistance, thermal conductivity, linear thermal expansion coefficient, change of workability, etc., because the components of the first base material and the second base material are different. Partial changes can be realized. Further, in this aluminum die-cast product, the metal structure becomes the same by forming the second base material by the molten metal whose main component is aluminum, and the boundary between the first base material and the second base material is the metal structure This means that there is a portion where there is no oxide film. For this reason, in this aluminum die-cast product, the first base material and the second base material having different metal structures exist under excellent adhesion. In this aluminum die-cast product, there are a case where there is no oxide film at the boundary and a case where the oxide film remains but the oxide film is not continuous and is partially broken. Of course, there is no brazing material or welding material at the boundary. Furthermore, this aluminum die-cast product does not cause a significant increase in the manufacturing process, and there is no shape limitation compared to the sintered product, and it is not necessary to powder the material at the time of production as in the sintered product, This is advantageous in terms of manufacturing cost.

Therefore, with this die casting method, it is possible to produce an aluminum die cast product that can realize a wide range of partial changes in characteristics, has excellent adhesion between the portions, and does not cause an increase in production cost. The aluminum die-cast product obtained in this way is used for, for example, a housing of a CO ₂ compressor, a piston, etc. that require more local strength improvement, ease of machining, etc., thereby reducing the weight of the CO ₂ compressor, Miniaturization and cost reduction can be realized.

  In this die casting method, in order to assume that the insert member is heated in the first step, the means for inserting the pre-heated insert member into the cavity or the insert member cooled to room temperature is heated in the cavity. Means to do this can be employed. Of these, it is preferable to heat the insert member in the cavity. In this case, there is no concern about the durability of the apparatus for gripping the insert member, and the insert member can be efficiently heated without being cooled by being exposed to the air in the middle of the insert. It is. In particular, it is preferable to heat the insert member by induction heating. This is because the insert member can be heated relatively easily by the high frequency coil.

  The molten metal is not limited to a single component, and molten metals of different components can be poured into the cavity sequentially. In this case, it is also possible to enlarge the cavity sequentially.

  In the second step, it is preferable to remelt at least the surface of the insert member with molten metal. Thereby, the oxide film of the insert member is destroyed.

  This die casting method is effective when the insert member is made of a first aluminum alloy containing silicon and the molten metal is a second aluminum alloy having a lower silicon content than the first aluminum alloy. In the aluminum die-cast product thus obtained, the first base material is a first aluminum alloy containing a large amount of silicon, and the second base material is a second aluminum alloy containing a small amount of silicon. The characteristics of hardness and low linear thermal expansion coefficient are exhibited, and the second base material exhibits characteristics of low hardness and high linear thermal expansion coefficient.

  In this die casting method, for example, the first aluminum alloy contains 16.0 to 18.0% by mass of silicon, and the second aluminum alloy contains 9.6 to 12.0% by mass of silicon. The inventors carried out this die casting method to produce an aluminum die cast product, and confirmed its effect. According to this aluminum die-cast product, high wear resistance is achieved with the first base material while easy machining is achieved with the second base material, realizing high performance, light weight, downsizing and cost reduction. Can do.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

  First, the die casting mold shown in FIGS. 1 and 2 is prepared. In this die casting mold, the fixed mold 1 and the movable mold 2 are provided so as to be movable in the horizontal direction away from each other. The first mold 3 is fixed to the left surface of the fixed mold 1 in the figure, and the movable mold 1 The second mold body 4 is fixed to the right side in FIG. By the horizontal movement of the fixed mold 1 and the movable mold 2, the first mold 3 and the second mold body 4 are configured to be openable in the horizontal direction.

  A cavity C is formed in the second mold 4. A fixing pin 3 a protruding into the cavity C is fixed to the first mold 3. The movable mold 2 is provided with a high-frequency coil 2a located in the vicinity of the fixed pin 3a. The movable mold 2, the first mold 3 and the second mold 4 are made of a Ni—Cr—Mo alloy.

  The first mold 3 is formed with a pressure inlet 3b communicating with the lower end of the cavity C. An injection 10 is provided in the pressure inlet 3b. The injection 10 includes an injection sleeve 10a that communicates with the pressure inlet 3b, a plunger 10b that slides within the injection sleeve 10a, and a cylinder 10c that moves the plunger 10b forward and backward by a rod.

  Using the above die casting mold, first, in the first step, the insert member M1 molded in advance and cooled to room temperature is held by a robot (not shown), and the insert member M1 is held by the fixing pin 3a. The insert member M1 is inserted into. In this insert member M1, Cu is 4.0 to 5.0 mass%, Si is 16.0 to 18.0 mass%, Mg is 0.45 to 0.65 mass%, and Zn is 1.5 mass% or less. Fe is 1.3 mass% or less, Mn is 0.5 mass% or less, Ni is 0.3 mass% or less, Sn is 0.3 mass% or less, and Al is the balance ADC14 (first aluminum alloy). .

  In the second step, the insert member M1 is heated to about 500 ° C. by the high frequency coil 2a. In this state, a fixed amount of molten metal M2 is put into the injection sleeve 10a of the injection 10, and the plunger 10b is advanced by the cylinder 10c. In the molten metal M2, Cu is 1.5 to 3.5% by mass, Si is 9.6 to 12.0% by mass, Mg is 0.3% by mass or less, Zn is 1.0% by mass or less, and Fe is 1.% by mass. 3 mass% or less, Mn is 0.5 mass% or less, Ni is 0.5 mass% or less, Sn is 0.2 mass% or less, Al is the remaining ADC12 (second aluminum alloy), 650 to 700 ° Melted in C. In this way, pressure is applied to the molten metal M2 while pouring the molten metal M2 into the cavity C. At this time, since the insert member M1 is heated by the high frequency coil 2a, the oxide film once formed is remelted by the molten metal M2 and effectively destroyed.

  Thereafter, in the third step, the insert member M1 and the molten metal M2 are solidified in the cavity C to obtain an aluminum die cast product P. In this aluminum die-cast product P, as shown in FIG. 3B, the first base material M1 made of the insert member M1 and the first base material M1 are integrally formed by a boundary where there is no oxide film. And the second base material M2 made of the molten metal M2.

Since this aluminum die cast product P has different components from the first base material M1 and the second base material M2, the partial strength, wear resistance, thermal conductivity, linear thermal expansion coefficient, change of workability, etc. A partial change in characteristics can be realized widely. More specifically, the first base material M1 made of ADC14 has a tensile strength of 320 MPa, a 0.2% yield strength of 250 MPa, an elongation of less than 1%, a hardness of 108 HB (10/500), and an impact strength of 3.8 kJ / m. ² , Young's modulus 81.2 GPa, density 2.73 g / cm ² , thermal conductivity 134 W / m · K, linear thermal expansion coefficient 18 × 10 ₋₆ / K, conductivity 37% (IACS), etc. . On the other hand, the second base material M2 made of ADC12 has a tensile strength of 310 MPa, a 0.2% proof stress of 150 MPa, an elongation of 3.5%, a hardness of 86 HB (10/500), an impact strength of 8.1 kJ / m ² , and a density. 2.68 g / cm ² , thermal conductivity 96 W / m · K, linear thermal expansion coefficient 21 × 10 ₋₆ / K, electrical conductivity 23% (IACS), etc. are exhibited.

  Moreover, in this aluminum die-cast product P, since the 1st base material M1 is formed of the insert member M1, it becomes the same metal structure based on the component, and the 2nd base material M2 is formed of the molten metal M2. Therefore, the same metal structure is formed on the basis of the components, and the boundary between the first base material M1 and the second base material M2 has a portion where the metal structure is different but no oxide film exists. For this reason, in this aluminum die-cast product P, the first base material M1 and the second base material M2 having different metal structures exist under excellent adhesion. For this reason, this aluminum die-cast product P can exhibit excellent durability.

  Furthermore, this aluminum die-cast product P does not increase the number of manufacturing steps so much, and there is no restriction on the shape as compared with a sintered product, and it is not necessary to use a powdered material at the time of manufacturing as in the case of a sintered product. This is advantageous in terms of manufacturing cost.

Therefore, according to this die casting method, it is possible to manufacture a die-cast P product that can realize a partial change in characteristics widely, has excellent adhesion between the portions, and does not cause an increase in manufacturing cost. The aluminum die cast product P is, CO ₂ compressor housing, by use in a piston or the like, weight reduction of the CO ₂ compressor, it is possible to realize downsizing and cost reduction.

  It is also possible to manufacture the vane of the vane type compressor by the same die casting method as in the above embodiment. In this case, the tip portion of the vane is a high hardness base material, and the other portion is a low hardness base material.

  Moreover, it is also possible to manufacture a cylinder block on which the piston of the piston compressor slides by the same die casting method as in the above embodiment. In this case, the sliding part of the cylinder block is a high hardness base material, and the other part is a low hardness base material.

  Furthermore, it is also possible to manufacture a heat sink component by the same die casting method as in the above embodiment. In this case, the heat receiving portion is a high thermal conductivity base material.

  It is also possible to manufacture various compressor bearing parts by the same die casting method as in the above embodiment. In this case, the rotating portion is a base material having a linear thermal expansion coefficient close to the drive shaft made of an iron-based material.

It is sectional drawing of the metal mold | die for die-casting concerning an Example. It is sectional drawing of the metal mold | die for die-casting concerning an Example. FIG. 1A is a cross-sectional view and FIG.

Explanation of symbols

M1 ... insert member, first base material M2 ... molten metal, second base material C ... cavity P ... aluminum die-cast product

Claims (6)

A first step of inserting a metal insert member into the cavity;
A second step of applying pressure to the molten metal while pouring a molten metal whose component is different from that of the insert member and the main component is aluminum;
And a third step of solidifying the molten metal in the cavity to obtain an aluminum die cast product, wherein the insert member is heated in the first step and / or the second step. .   The die casting method according to claim 1, wherein the insert member is heated in the cavity.   3. The die casting method according to claim 2, wherein the insert member is heated by induction heating.   The die casting method according to any one of claims 1 to 3, wherein in the second step, at least a surface of the insert member is remelted by the molten metal.   5. The insert member according to claim 1, wherein the insert member is made of a first aluminum alloy containing silicon, and the molten metal is a second aluminum alloy having a lower silicon content than the first aluminum alloy. The die-casting method of any one of Claims.   6. The first aluminum alloy contains 16.0 to 18.0% by mass of silicon, and the second aluminum alloy contains 9.6 to 12.0% by mass of silicon. Die casting method.

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