JP2006102809A - Die casting method and die casting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die casting method and a die casting apparatus which can correspond to a small type, energy-saving, high quality and also, many kinds-small quantity in comparison with the conventional die casting apparatus. <P>SOLUTION: In addition to molten metal injection plunger tip for injecting the molten metal, a molten metal pressurizing plunger for pressurizing the molten metal is set at the front of a gate and the molten metal is injected at injection pressure not higher than the ordinary injection pressure of the die casting machine by the molten metal injection plunger and thereafter, the molten metal is pressurized by the molten metal pressurizing plunger. Further, the molten metal injection plunger tip is driven by electric-motor and furthermore, if necessary, the die temperature is controlled and the directive solidification toward the gate is attained when possible and also, the die manufactured with a die material or rapid prototyping easily machined, is used. Alternatively, the variation of the molten metal filling up ratio is prevented by setting the plurality of molten metal pouring holes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention mainly relates to a die casting method and a die casting apparatus for an Al alloy or Mg alloy casting.

  Due to diversification of demand, shortening of product life, catching up with developing countries, etc., a die casting method suitable for low-cost, high-mix low-volume production is desired. In addition, in order to reduce the weight of automobiles and the like, a technology for manufacturing large-sized die cast products with high quality and low cost is also desired.

  On the other hand, in the conventional die casting method, as shown in Non-Patent Documents 1 and 2, etc., molten metal injection and pressurization are performed by one hydraulically driven plunger.

Therefore, since the plunger tip has a long moving distance and is pressurized at a high pressure, a high-pressure and large-capacity hydraulic system is required, resulting in a large-sized device, high device cost, and large energy consumption. This is particularly a problem when manufacturing large products. Furthermore, even if high pressure is applied to the complete liquid phase part, the quality is not improved, the mold life is shortened, and an inexpensive mold material cannot be used. Pressurization is to prevent shrinkage due to coagulation shrinkage. For this purpose, the solid-liquid coexistence area should be pressurized, but since the coagulation layer exists quickly around the plunger tip, the plunger tip The movement resistance is large and requires high pressure. That is, energy is wasted. Furthermore, since the cavity and the plunger sleeve are connected, it is difficult to decompress only the cavity.
Die Casting Technician Handbook, National Die Casting Industrial Cooperative Federation, (Showa 56), 9 Raw material, Vol. 44 (2003) 1, 6 Material Center

  Provided is a die casting method and a die casting apparatus that are smaller, save energy, have higher quality, and can cope with small-lot production of various products than conventional die casting apparatuses.

  In addition to the molten metal injection plunger tip for injecting the molten metal, a molten metal pressure plunger tip for pressurizing the molten metal is installed in front of the gate, and the molten metal is injected with the molten metal injection plunger tip below the normal die casting injection pressure. After injection, the molten metal is pressurized with a molten metal pressure plunger tip. Further, the molten metal injection plunger tip is driven by an electric motor or a linear motor. Furthermore, the temperature of the mold is controlled to achieve directional solidification toward the gate as much as possible, and a mold material that is easy to process and a mold manufactured by rapid prototyping are used. If necessary, the gate is sealed with a molten metal pressure plunger tip before the molten metal is injected so that the cavity and the plunger sleeve can be decompressed independently.

  By dividing the plunger tip that has two functions of molten metal injection and pressurization into the molten metal injection plunger tip and the molten metal pressure plunger tip, it is possible to efficiently operate the low pressure during molten metal injection and the high pressure during pressurization. Become.

  That is, since the molten metal injection plunger does not need to be at a high pressure, it can be driven by an electric motor or a linear motor, thereby reducing the size and energy of the apparatus. In addition, fine control of the injection speed is possible. The molten metal pressure plunger tip is driven by hydraulic pressure, but the moving distance is short, so a small hydraulic device is sufficient. In addition, since the force is not applied to the solidified portion around the plunger sleeve but the hottest portion can be pressurized, the pressure can be efficiently applied and the burden on the mold is reduced. For this reason, it is not necessary to use expensive mold materials as in the past, and molds produced by high-speed cutting of metal materials with good workability and various rapid prototyping can be used. Can also be used for production.

  When the gate is sealed with the molten metal pressure plunger tip, the effect described in the patent pending (reference number DC0001-1, applicant: Ikuo Ohnaka) is obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

  Next, an embodiment for carrying out the present invention will be described with reference to FIGS.

  FIG. 1 is a side view of the vicinity of the gate in the first embodiment. After injecting the molten metal 7 with the molten metal injection plunger tip 2, the molten metal pressure plunger tip 5 is pushed out to a position indicated by a one-dot chain line. There is a solidified layer on the plunger sleeve 3 and the fixed-type molten metal contact surface, and the molten metal injection plunger tip 2 is ejected while being partially pushed out to the front surface, so that it cannot move unless a considerable pressure is applied near the end of the injection. However, the position of the molten metal pressure plunger tip 5 is in the high temperature portion and can be easily moved as compared with the molten metal injection plunger tip 2. In addition, this moving distance is such that it compensates for the suspicious shrinkage in the cavity 4 (several tens of mm or less), and is much shorter than the moving distance of the molten metal injection plunger tip 2.

  Also, by controlling the mold temperature, optimizing the thermal design, and designing the thickness of the product so that directional solidification occurs in the cavity, the molten metal pressure can be reduced, and cast iron with good workability in the mold, etc. Can be used, or can be used for rapid prototyping and relatively low mechanical strength, and can be used for low-volume production.

  In this method, since the molten metal injection pressure is low, it is not necessary to increase the rigidity of the plunger sleeve as much as in the prior art. For example, as shown in FIG. 1, a plurality of pouring ports 1a and 1b are installed, and for large products, the pouring port 1a is not provided. For small products, by using the pouring port 1b, the change in the molten metal filling rate in the plunger sleeve 3 can be minimized, and the quality can be stabilized.

  FIG. 2 is a side view of the vicinity of the gate of Example 2, in which the molten metal pressure plunger tip is doubled and the gate 6 can be sealed, and the molten metal is supplied to the plunger sleeve. FIG. 3 shows the situation at the final stage of molten metal pressurization.

  During operation, during or after decompression of the cavity, the molten metal is supplied, the molten metal injection plunger tip 2 is moved to the left to close the pouring port, and the molten metal pressure plunger tips 5a and 5b are moved backward to the left to open the gate. The molten metal injection plunger tip 2 injects the molten metal. Thereafter, the molten metal pressurizing plunger tips 5a and 5b are first moved rightward to pressurize the molten metal. Finally, as shown in FIG. 3, the molten metal pressurizing plunger tip 5b is moved further to the right to pressurize the high temperature part. However, since the pressure is not transmitted to the cavity when the gate portion is solidified, it is necessary to pay attention to the dimensions and cooling so that the gate portion does not proceed excessively.

  4 and 5 are side views of the third embodiment, and show an example in which the molten metal injection plunger tip 2 is driven by the servo motor 14.

  That is, FIG. 4 shows a state before the molten metal is injected. The rotation of the servo motor 14 is transmitted to the ball screw 15 and converted into a linear motion of the molten metal injection plunger, and the molten metal is injected. Thereafter, in the molten metal pressurization stage, the stopper 16 is lowered to prevent the molten metal injection plunger from moving to the right even if the output of the servo motor is not so large. By using the servo motor 14, the injection speed can be changed over time according to the product structure and dimensions, and a product with few defects can be obtained.

  In addition, the method of converting the rotational motion of the motor into a linear motion may be other methods such as a combination of a rack and a gear other than the ball screw. In addition to the servo motor, another method using an electromagnetic force such as a linear motor may be used.

  It can be used to manufacture high quality die casting products.

2 is a side view of the vicinity of a gate in Embodiment 1. FIG. In the side view of the gate vicinity in Example 2, the state before melt injection is shown. In the side view of the gate vicinity in Example 2, the state of the molten metal pressurization final stage is shown. The side view of Example 3 shows the state before molten metal injection. The molten metal pressurization state is shown in the side view of the third embodiment.

Explanation of symbols

1, 1a, 1b Pouring port 2 Molten injection plunger tip 3 Plunger sleeve 4 Cavity 5 Molten pressure plunger tip 5a Inner pressure plunger tip 5b Outer pressure plunger tip 6 Gate 7 Molten metal 8 Fixed plate 9 Fixed type 10 Movable type 11 Seal 12 Insertion of sliding surface of molten metal pressure plunger tip (plunger sleeve side)
13 Insertion of sliding surface of molten metal pressure plunger tip (movable side)
14 Electric motor 15 Ball screw 16 Stopper

Claims (9)

  In addition to the molten metal injection plunger tip for injecting the molten metal, a molten metal pressure plunger tip for pressurizing the molten metal is installed in front of the gate, and the molten metal injection plunger tip injects the molten metal below the normal die casting injection pressure. , And then pressurizing the molten metal with a molten metal pressurizing plunger tip and a die casting apparatus,   2. A die casting method and a die casting apparatus according to claim 1, wherein the molten metal pressure plunger has a double structure of the inner side and the outer side, the molten metal is first pressurized simultaneously in both, and the high temperature portion is pressurized by the inner plunger later.   2. A die casting method and a die casting apparatus according to claim 1, wherein the molten metal injection plunger tip is driven by an electric motor or a linear motor.   4. A die casting method and a die casting apparatus according to claim 1, wherein the gate portion is sealed with a molten metal pressure plunger tip to depressurize the cavity or the plunger sleeve.   5. A die casting method and a die casting apparatus according to claim 1, wherein a stopper is provided on the molten metal injection plunger to prevent movement of the molten metal injection plunger due to molten metal pressurization.   6. A die casting method and a die casting apparatus according to claim 1, wherein the temperature is controlled so that the die is directionally solidified toward the gate as in the low pressure casting.   5. A die casting method and a die casting apparatus according to claim 4, wherein the sliding surface of the molten metal pressure plunger tip has a nested structure.   9. The method according to claim 1, wherein the insert mold that constitutes the cavity is made of a material having good cutting properties such as cast iron or a mold produced by rapid prototyping. Die casting method and die casting equipment   Die casting method and die casting apparatus characterized in that a plurality of hot water outlets are provided in the above

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