JP2007181842A - Molten metal pressurizing mechanism in electromotive type die casting and plunger tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of pressurizing molten metal at just finishing time of injection, in an electromotive type die casting for injecting the molten metal with an electric motor. <P>SOLUTION: A plunger tip driving shaft 2 for driving to the straight line with the electric motor and a plunger tip 1, are connected through a spring 4 or liquid 5, and even after filling up the molten metal into a cavity, the molten metal is pressurized by advancing the plunger tip driving shaft 2 through the deformation of the spring or the flowing-out of the liquid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a molten metal pressurizing mechanism and a plunger tip in an electric die casting machine used mainly for the manufacture of Al alloy and Mg alloy castings.

  Due to diversification of demand, shortening of product life and catching up with developing countries, die casting method suitable for low-cost, high-mix low-volume production is desired. In order to reduce the weight of automobiles, etc., technology for manufacturing large 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, the molten metal is injected at a high pressure by a hydraulically driven plunger. For this reason, a high-pressure and large-capacity hydraulic system is necessary, resulting in a large-scale device, high device cost, and large energy consumption.

In order to solve these problems, electric motor drive die casting methods as shown in Patent Documents 1 and 2 have been proposed. However, in the method of Patent Document 1, excessive current flows because the load on the electric motor increases rapidly at the end of molten metal injection. For this reason, the motor current is cut off at the end of the molten metal injection, and the plunger tip cannot be continuously pushed, and the molten metal pressure is not applied at the end of the injection, so that the surface properties of the product and the hot water defects in the thin wall portion are likely to appear.
Die Casting Technician Handbook, National Die Casting Industrial Cooperative Federation, (Showa 56), 9 Raw material, Vol. 44 (2003) 1, 6 Material Center Japanese Patent Application 2000-024767 Japanese Patent Application No. 2004-317147

  A method is provided to pressurize the molten metal at the end of molten metal injection by an electric motor.

  In the electric die casting, the rotary motion of the electric motor is converted into a linear motion with a ball screw or the like, and the plunger tip is driven by this linear motion to inject the molten metal. Alternatively, the plunger tip is directly driven by a linear motor. In the present invention, a shaft that linearly moves by an electric motor (hereinafter referred to as a “plunger tip drive shaft”) and a plunger tip are not directly connected, but a liquid or gas such as a spring or oil, or these, as shown in FIG. The plunger tip is driven through the combined mechanism, and the plunger tip drive shaft is moved forward to pressurize the molten metal even after the cavity is filled by deformation of the spring, outflow of liquid, compression of gas, or a combination of these.

  The sudden load on the electric motor at the end of molten metal injection is because the plunger tip cannot move because the molten metal is almost incompressible. Therefore, even if the plunger tip cannot move after the molten metal injection, if the plunger tip drive shaft can move, the electric motor will not stop rotating, so the molten metal can be pressurized during this time.

  In order to move the plunger tip drive shaft with the plunger tip fixed, a spring is installed between the plunger tip and the plunger tip drive shaft as shown in FIG. Alternatively, as shown in Figs. 1 and 2, the liquid corresponding to the volume change can be moved by flowing out the enclosed liquid. Alternatively, gas can be enclosed instead of liquid and moved by compressing the gas. Alternatively, all deformation mechanisms can be used by combining both spring and liquid, or combining spring, liquid and gas. Such a deformation mechanism may be incorporated in the plunger tip as shown in FIGS. 1 and 2, or in the middle of the plunger drive shaft as shown in FIG.

  As shown in Fig. 4, when only the spring is used, the applied pressure rises linearly. When a liquid pool is provided, the amount of deformation (movement amount) can be controlled depending on how the liquid flows out, but a hydraulic circuit is required. Combining the spring and liquid outflow, the displacement is controlled by the liquid outflow speed in the initial stage, and the fluid pressure circuit is simplified by using the deformation of the spring after a certain period of time. Also, as shown in Fig. 2, the liquid can flow out into the plunger sleeve to provide a lubricating action. In the case of gas, it is possible to achieve more uniform lubrication by mixing liquid and gas and injecting them as mist into the plunger sleeve.

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 a plunger tip 1 according to the first embodiment. The plunger tip 1 is a tip of a plunger tip drive shaft 2 that moves horizontally using a ball screw and an electric motor. 5 is connected. When only the displacement of the spring 4 is used, the liquid 5, the liquid pipe 6, the valve 7, etc. are unnecessary. In this case, when the molten metal is injected, a force corresponding to the flow resistance and dynamic pressure of the molten metal and the movement resistance of the plunger tip acts on the spring 4. When the molten metal is filled, the plunger tip 1 does not move, but the plunger tip drive shaft 2 can move forward as long as the deformation of the spring 4 allows, so that the molten metal is pressurized during this time.

  When only the spring 4 is used, the pressurization time after filling the molten metal cannot be taken very long. When a longer pressurization time is required, the liquid 5 is put into the space where the spring 4 is further installed, and the flow amount of the liquid is controlled by opening and closing the valve 7 connected via the liquid pipe 6. Move the plunger tip drive shaft by an appropriate amount. In this case, there is no need for a spring. However, by using a spring together, for example, the movement of the plunger tip drive shaft is controlled initially by the amount of outflow of liquid, and the control mechanism is controlled by moving the spring from a certain point. Is simplified. When liquid is used, it can be used to lubricate the plunger sleeve by allowing the liquid to flow out of the gap between the plunger tip and the plunger drive shaft. At this time, it is necessary to increase the flow resistance in the gap, and it is necessary to devise measures such as increasing the flow length by making the groove in the gap spiral.

  FIG. 2 shows another embodiment in which oil is used as a liquid, and the oil is caused to flow out into a liquid (oil) pool 10 through a valve controlled by a spring, and the oil is allowed to flow between the plunger tip drive shaft and the plunger tip and the plunger tip. Oil is used for lubrication by flowing into the gap between the plunger sleeve and the plunger sleeve.

  FIG. 3 shows another embodiment in which a component 16 similar to the plunger tip shown in FIGS. 1 and 2 is installed between the conventional plunger tip 17 and the plunger tip drive shaft 2.

  In addition, when the pressurizing plunger described in Patent Document 2 is electrified, it can be used in the same manner as in FIGS.

  Can be used to manufacture die-cast products.

It is a side view of Example 1. FIG. It is a side view of Example 2. FIG. It is a side view of Example 3. The relationship between the pressure change acting on the molten metal and time is shown.

Explanation of symbols

1 Plunger Tip 2 Plunger Tip Drive Shaft 3 Pressurizing Piston 4 Plunger Tip Pressurizing Spring 5 Liquid 6 Liquid Pipe 7 Valve 8 Plunger Sleeve 9 Piston Ring 10 Liquid Pool 11 Liquid Outlet 12 Liquid Outflow Control Valve 13 Liquid Outflow Control Valve Spring 14 Plunger tip drive shaft lubrication groove 15 Plunger tip lubrication groove 16 Deformation mechanism 17 similar to the plunger tip portion shown in FIGS. 1 and 2 Conventional plunger tip 18 Electric motor 19 Fixed plate 20 Fixed type

Claims (3)

  Plunger tip drive shaft in an electric die casting where the plunger tip is driven by converting the rotary motion of the electric motor into a linear motion of the plunger tip drive shaft with a ball screw or the like, or the plunger tip is directly driven by a linear motor to inject molten metal. The plunger tip is driven directly via a spring, liquid (especially oil), gas, or a combination of these without connecting the plunger tip directly to the plunger tip. Die casting method and die casting apparatus characterized in that the molten metal is pressurized by advancing the plunger tip drive shaft by pressurizing or a combination thereof   A mechanism that enables movement of the plunger tip drive shaft even after the movement of the plunger tip is stopped by the spring, liquid, gas, or combination thereof shown in claim 1, or a plunger tip incorporating this mechanism   A method of lubricating oil using oil as a liquid according to claim 1 and flowing out between a plunger tip and a plunger sleeve and between a plunger tip drive shaft and a plunger tip.

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