JPH11197812A - Injecting method in die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the development of sticking of a biscuit by retreating a plunger tip after completing the injecting action of the plunger tip, separating it from the biscuit and advancing the plunger tip while following to the opening of dies. SOLUTION: After completing the injecting action of the plunger tip 2, this plunger tip 2 is retreated by a small distance and separated from the biscuit (b), and after executing a curing, the plunger tip 2 is again advanced while following to the opening of the dies 3a, 3b, so as to push out the biscuit (b) from the fixed die 3b side to the movable die 3a side. At this time, as this timing with which the plunger 2 is separated from the biscuit (b), when the biscuit (b) almost solidifies, concretely, it is desirable to separated the plunger a few sec after completing the injecting action of the plunger 2. As a result, the biscuit (b) can be freely shrunk at the time of solidifying and smoothly pushed out from the fixed die side of the movable die side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of casting a molten metal injected into an injection sleeve in a die casting process.
The present invention relates to an injection method of injecting with a plunger tip and filling the cavity of a mold with pressure.

[0002]

2. Description of the Related Art Normally, even after a metal melt in an injection sleeve is injected with a plunger tip and filled into a cavity of a mold under pressure, pressure is applied to the plunger tip as it is to perform curing (waiting for solidification of the molten metal). The reason is that by pressing the biscuit portion formed between the shunt of the mold and the plunger tip with the plunger tip, a so-called hot-water effect with no cavities is expected. Since the runner portion solidifies before solidification, it is a reality that the plunger tip can hardly expect the hot water effect.

On the other hand, if pressure is applied to the plunger tip as it is even after the molten metal is pressurized and filled into the mold cavity, the biscuit solidifies and shrinks, preventing shrinkage in the radial direction. The outer peripheral surface firmly adheres to the inner peripheral surface of the injection sleeve, so that the biscuit is left on the fixed mold side when the mold is opened. There were problems such as easy insertion of burrs between them.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide an injection method in die casting in which there is no possibility of so-called biscuit removal.

[0005]

According to a first aspect of the present invention, there is provided an injection method for die casting in which the plunger tip is retracted and separated from the biscuit after the injection operation of the plunger tip is completed. The plunger tip is moved forward by following the mold opening. Further, in the injection method in die casting according to claim 2 of the present invention, after the injection operation of the plunger tip is completed, the injection pressure is reduced to zero or almost zero while the plunger tip is kept in contact with the biscuit, and It is characterized in that the plunger tip is made to move forward following the mold opening.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a cross section of a part of a die casting machine. In a series of die casting steps, a molten metal injected into an injection sleeve 1 is injected with a plunger tip 2 to form dies 3a, 3b.
Of the cavity 4 is pressurized and filled. In the figure, a is a cast product part, and b is a biscuit.

The injection method according to the present invention provides an injection sleeve 1
Up to the point where the molten metal injected into the inside is injected by the plunger tip 2 and pressure-filled into the cavities 4 of the molds 3a and 3b, the behavior of the plunger tip 2 thereafter is the same. Completely different.

That is, after the injection operation of the plunger tip 2 is completed (after the plunger tip 2 reaches the advance limit), the plunger tip 2 is slightly retracted and separated from the biscuit a, and after curing (waiting for solidification of the molten metal) has elapsed. The plunger tip 2 is made to follow the opening of the molds 3a and 3b.
Is moved forward again to push the biscuit a from the fixed mold 3a side to the movable mold 3b side. At this time, it is preferable that the plunger tip 2 is separated from the biscuit a when the biscuit a is substantially solidified, specifically, several seconds after the plunger tip 2 completes the injection operation.

As another method different from the injection method described above, after the injection operation of the plunger tip 2 is completed, that is, after the plunger tip 2 reaches the forward limit, the front surface of the plunger tip 2 is brought into contact with the biscuit. In this state, the injection pressure of the plunger tip 2 is reduced to zero or almost zero, and after the lapse of curing (waiting for solidification of the molten metal), the plunger tip 2 is moved forward again by following the opening of the molds 3a and 3b. Alternatively, the biscuit a may be pushed from the fixed mold 3a side to the movable mold 3b side.

[0010]

According to the injection method in die casting according to the present invention, after the injection operation of the plunger chip is completed, the plunger chip is retracted and separated from the biscuit, or the injection is performed while the plunger chip is kept in contact with the biscuit. Since the pressure was zero or almost zero,
When the biscuit solidifies, it can freely shrink. Therefore, the biscuit shrinks in the radial direction, so that there is a margin between the biscuit and the inner peripheral surface of the injection sleeve. As a result, the plunger tip moves forward following the opening of the mold, and the Is smoothly pushed out from the fixed mold side to the movable mold side, so that there is no danger that the biscuit will remain on the fixed mold side when the mold is opened, that is, the so-called biscuit is removed. In addition, burrs are less likely to be inserted between the plunger tip and the inner peripheral surface of the injection sleeve.

Further, according to the injection method for die casting according to the first aspect of the present invention, the plunger tip is retracted and separated from the biscuit after the injection operation of the plunger tip is completed. The generated burrs can be automatically discharged when the plunger tip is moved forward by following the opening of the mold again.

According to the injection method in die casting according to the second aspect of the present invention, after the injection operation of the plunger tip is completed, the injection pressure is reduced to zero or almost zero while the plunger tip is kept in contact with the biscuit. As a result, the biscuit can be rapidly solidified through the portion in contact with the plunger tip.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example for explaining an injection method of the present invention.

[Explanation of symbols]

1: injection sleeve 2: plunger tip 3a: movable mold 3b: fixed mold 4: cavity a: cast product part b: biscuit

Claims (2)

[Claims] 1. The injection in die casting, wherein after the injection operation of the plunger tip is completed, the plunger tip is retracted and separated from the biscuit, and the plunger tip is moved forward by following the mold opening. Method. 2. After the injection operation of the plunger tip is completed, the injection pressure is reduced to zero or almost zero while the plunger tip is kept in contact with the biscuit, and the plunger tip is moved forward by following the mold opening. An injection method in die casting, characterized in that: