JP2001205414A - Injection device for metal injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection device for a metal injection molding machine which relieves the collision of a piston with an injection housing, reduces noise and improves the durability of the device. SOLUTION: An elastic member 23 on which the front end of the injection piston 7 is brought into abutment before the injection piston 7 arrives at the most forward position is installed to the inside surface of the injection housing 1. As a result, the front end of the injection piston 7 abuts on the elastic member 23, by which the advance of the injection piston 7, etc., is decelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device of a metal injection molding machine for injection-molding a metal such as magnesium or aluminum and an alloy containing the same as a main component (hereinafter referred to as a metal material).

[0002]

2. Description of the Related Art An example of an injection device of a conventional metal injection molding machine will be described with reference to FIGS.

As shown in FIG. 8, a heating cylinder 2 is fixed to a front portion of an injection housing 1 of an injection device 17 by mounting bolts 28, and a rotary motor 3 is fixed to a rear portion. A heating heater 4 is attached to the outer periphery of the heating cylinder 2, and a material hopper 5 is attached to a rear portion of the heating cylinder 2. A screw 6 is inserted inside the heating cylinder 2 so as to be rotatable and axially movable.

The injection piston 7 built in the injection housing 1 constitutes an injection cylinder together with the injection housing 1, and is provided between the forward oil chamber 8 of the injection piston 7 and the wall surface 21 of the injection piston 7 and the wall surface 22 of the injection housing 1. A retraction oil chamber is formed at the bottom. A rear portion of the screw 6 is inserted into a front portion of the output shaft 10 which is inserted into the injection piston 7 and held rotatably by bearings 25 and 26, and a rear end face 30 of the screw 6 is formed in a front hole 29 of the output shaft 10. It is in contact with the bottom. The rear part of the output shaft 10 is fitted to the front part of the drive shaft 11 connected to the rotary motor 3 so as to be movable in the axial direction.

As shown in FIGS. 9 and 10, which are sectional views taken along the line DD in FIGS. 8 and 8, the outer peripheral groove 13 at the rear of the screw and the outer peripheral groove 14 at the front of the output shaft are divided into two disks. The coupling 12 is fitted and is integrally fixed by a tightening bolt 15.

Next, the operation will be described.

[0007] First, in the measuring step, granular, cut pieces,
Metal materials such as crushed pieces (hereinafter referred to as metal material chips)
Is supplied to the material hopper 5. When the rotation of the rotary motor 3 is transmitted to the screw 6 via the drive shaft 11 and the output shaft 10, the metal material chip dropped from the material hopper 5 into the heating cylinder 2 is heated along the spiral groove on the surface of the screw 6. It is heated and kneaded while being sent to the front of the cylinder 2, and is in a molten or semi-molten state (hereinafter, referred to as a molten metal material) and stored in the front chamber 16 of the heating cylinder 2.

In the next injection step, the entire injection device 17 is advanced, and the nozzle 18 at the tip of the heating cylinder 2 is brought into contact with a sprue bush of a mold (not shown). When the injection piston 7 is driven in the forward direction by supplying the pressure oil, and the screw 6 is advanced through the output shaft 10, the molten metal material stored in the front chamber 16 of the heating cylinder 2 passes through the nozzle 18 into the mold. And filled into the cavity in the mold.

After the molten metal material filled in the cavity in the mold is cooled and solidified, the mold is opened to take out the metal molded product formed in the cavity shape.

[0010] By repeating the above operation, it is possible to efficiently produce a metal molded product having the same shape.

When the screw 6 is pulled out from the output shaft 10 for the purpose of cleaning the surface of the screw 6, the inner surface of the heating cylinder 2, and the like, the coupling 12 can be seen from the working window 19 provided in the injection housing 1. The injection piston 7 is retracted to the position, the transparent cover 20 is removed, and the work window 1 is removed.
Output shaft 1 from 9 to the angle at which the head of tightening bolt 15 can be seen
0, the fastening bolt 15 is loosened and removed, and the coupling 12 is removed.

[0012]

Generally, metallic materials are:
Since the specific heat is small and the heat conductivity is good, the molten metal injected into the mold is immediately solidified, and the defective filling is likely to occur. For this reason, in injection molding of a metal material, it is necessary to inject a molten metal material into a mold at a high speed, and a forward speed of an injection piston in a metal injection molding machine is 10 times or more that of a plastic injection molding machine. That is, a high speed of 2 to 4 m per second is required.

When the injection piston and an output shaft connected to the injection piston, a screw and the like (hereinafter referred to as an injection piston and the like) are integrally moved forward at a high speed, a large impact force is generated when the injection piston is stopped rapidly. . Actually, the brake is applied by shutting off the pressure oil flowing into the forward oil chamber of the injection cylinder or by shutting off the pressure oil flowing out of the reverse oil chamber. Since it ends before and after, it overcomes the inertial force of the injection piston etc. having a large mass, and the high-speed forward operation of the injection piston etc.
It is very difficult to suddenly decelerate and stop by hydraulic control.

Therefore, at the final stage of the injection operation, the wall surface 21 of the injection piston 7 constituting the forward oil chamber 8 shown in FIG. At that time, a loud collision sound is generated, or the impact reduces the durability of related parts.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art described above, and alleviates the collision of the injection piston with the injection housing to reduce noise and improve the durability of the apparatus. It is an object of the present invention to provide an injection device for a metal injection molding machine.

[0016]

The present invention has solved the above-mentioned problems as follows. That is, in the injection device of the metal injection molding machine according to the present invention, an elastic member that abuts the front end of the injection piston before the injection piston reaches the most advanced position is installed on the inner surface of the injection housing. Thus, the forward end of the injection piston or the like is decelerated by the front end of the injection piston contacting the elastic member.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings.

FIG. 1 is a structural view of an injection device of a metal injection molding machine according to one embodiment of the present invention. FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. It is a line sectional view.

As shown in FIG. 1, a heating cylinder 2 is fixed to a front portion of an injection housing 1 of an injection device 17 by a mounting bolt 28, and a rotary motor 3 such as a hydraulic motor or an electric motor is fixed to a rear portion. I have. A heater 4 is attached to the outer periphery of the heating cylinder 2, and a material hopper 5
Is attached. Screw 6 inside heating tube 2
Are rotatably and axially movable.

The injection piston 7 built in the injection housing 1 forms an injection cylinder together with the injection housing 1 and forms a forward oil chamber 8 and a backward oil chamber 9 of the injection piston 7. Bearings 25 and 26 inserted into injection piston 7
Front hole 29 of output shaft 10 rotatably held by
The rear end of the screw 6 is inserted into the shaft 6 in such a manner that mutual rotation is restricted by a spline or the like, and the rear end face 30 of the screw 6 is in contact with the bottom surface of the front hole 29 of the output shaft 10. The rear part of the output shaft 10 is fitted to the front part of the drive shaft 11 connected to the rotary motor 3 so as to be movable in the axial direction.

As shown in FIGS. 1 to 3, a coupling disk 12 is fitted into an outer peripheral groove 13 at the rear of the screw and an outer peripheral groove 14 at the front of the output shaft. It is fixed to.

An annular elastic body 23 is attached to the inner surface of the injection housing 1 so that the front end of the injection piston 7 abuts before the injection piston 7 reaches the most advanced position. Is held in. The state before the injection piston 7 reaches the most advanced position means before the wall surface 21 of the injection piston 7 forming the retreat oil chamber 9 collides with the wall surface 22 of the injection housing 1.

The elastic body 23 is made of oil-resistant hard rubber such as chloroprene rubber or nitrile rubber, having a hardness of about HS90 or plastic. Also,
Although the size of the elastic body 23 varies depending on the size of the machine, the elastic body 23 having a thickness of 10 to 50 mm is selected so that the deformation by the injection piston 7 falls within the range of 1 to 10 mm.
Next, the operation will be described.

First, a metal material chip is put into the material hopper 5 in a measuring step. When the rotation of the rotary motor 3 is transmitted to the screw 6 via the drive shaft 11 and the output shaft 10, the metal material chips dropped from the material hopper 5 into the heating cylinder 2 are moved along the spiral groove on the screw surface. Is heated and kneaded while being sent to the front of the heating cylinder 2, becomes a molten metal material, and is stored in the front chamber 16 of the heating cylinder 2.

In the next injection step, the entire injection device 17 is advanced, and the nozzle 18 at the tip of the heating cylinder 2 is brought into contact with a sprue bush of a mold (not shown), and is then moved to the oil chamber 8 for advance of the injection cylinder. Pressure oil is supplied to drive the injection piston 7 in the forward direction, and the operation is transmitted to the screw 6 via the output shaft 10. When the screw 6 moves forward, the molten metal material stored in the front chamber 16 of the heating cylinder 2 is injected into the mold through the nozzle 18 and filled in the cavity in the mold.

When the injection piston 7 moves forward at a high speed, it collides with the annular elastic body 23 just before the most advanced position and is decelerated, and a large impact force is prevented in cooperation with the brake by hydraulic control.

After the molten metal material filled in the cavity in the mold is cooled and solidified, the mold is opened to take out the metal molded product formed in the cavity shape.

By repeating the above operations, it is possible to efficiently produce a metal molded product having the same shape.

When the screw 6 is pulled out from the output shaft 10 for the purpose of cleaning the surface of the screw 6 or the inner surface of the heating cylinder 2, etc., the coupling 12 can be seen from the working window 19 provided in the injection housing 1. The injection piston 7 is retracted to the position, the transparent cover 20 is removed, the output shaft 10 is rotated by the rotary motor 3 to an angle at which the fastening bolt 15 can be removed, the fastening bolt 15 is loosened and removed, and the coupling 12 is removed. . Thereby, the screw 6 can be pulled out from the output shaft 10 and pulled out in front of the heating cylinder 2.

Next, an injection apparatus according to a second embodiment will be described with reference to FIG. 4 and FIG. 5 which is a cross-sectional view taken along line CC of FIG.

In this embodiment, the elastic member 23 of the injection device 17 is used.
a is formed in a partially annular shape, and the wall of the injection housing 1 facing the outside of the portion without the elastic body 23a is also removed.
9a is enlarged. Thereby, even at the position where the injection piston 7 is most advanced, the working window 19a larger than the outer diameter of the coupling 12 is secured. Note that the partial annular elastic body 23a may have a shape in which only one portion of the annular body is removed, but in order to receive the impact force of the injection piston 7 and the like evenly, the plurality of elastic bodies 23a must It is preferable to arrange them evenly. For convenience of illustration, screw 6
Since the outer diameter of the coupling 12 is exaggerated, the elastic body 23a has a half-moon shape. However, in practice, the elastic body 23a often has a shape obtained by cutting a part of a ring.

According to this embodiment, even when the injection piston 7 is at the most advanced position, the coupling 12a can be removed by removing the cover 20a and removing the fastening bolt 15.
And the screw 6 can be pulled out.

When the tightening bolt 15 is at an angle that cannot be seen from the working window 20a, the rotary motor 3 is operated, and the coupling 12 together with the output shaft 10 is moved until the tightening bolt 15 is seen from the working window 20a. After rotating, perform the removal work.

When the screw 6 is firmly fixed to the heating cylinder 2 and cannot be rotated by the rotary motor 3, the material hopper 5 is removed, and the mounting bolt 28 of the heating cylinder 2 is removed. The coupling 12 can be removed by rotating the entire heating cylinder 2 with respect to the injection housing 1 together with the screw 6 so that the tightening bolt 15 can be seen from the working window 20a.

Next, an injection apparatus according to a third embodiment will be described with reference to FIGS. When the tightening bolt 15 is tightened, the coupling 12 of the first and second embodiments is fixed to the screw 6 or the output shaft 10 and rotates together. Even when the screw 15 is tightened, the fitting is formed so as to be loose in the axial and radial directions to the extent that it can be rotated with respect to the screw 6 and the output shaft 10.
This is prevented by tightening the fixing bolts 24 screwed into a.

For this reason, the tightening bolt 15 is connected to the working window 20a.
If the angle is not visible from the angle, the fixing bolt 24 is loosened, and the coupling 12a is manually rotated so that the tightening bolt 15 is at an angle visible from the work window 20a.
Removal work can be performed.

[0037]

Since the present invention is configured as described above, the following effects can be obtained. (A) By providing the shock absorbing member at the forward limit position of the injection piston, it is possible to reduce the impact of the injection piston on the injection housing, reduce the collision and improve the durability of the device. (B) If the screw keeps the most advanced position due to the inertia force of the injection piston or the like, the mold is partially expanded by the molten metal material filled in the cavity, and large burrs are generated in the molded product. According to the present invention, at the moment when the high pressure of the pressure oil supplied to the forward oil chamber is removed, the repulsive force of the elastic body overcomes the inertia force of the injection piston or the like, retreats the injection piston, and retreats the screw. In addition, it is possible to reduce the flash generated in the molded product. (C) According to the invention according to claim 4, even when the injection piston becomes unable to retreat at the most advanced position, the coupling bolt can be removed by loosening the tightening bolt. (D) According to the invention according to claim 5, even when the screw is fixed to the heating cylinder and cannot rotate and slide, after rotating the coupling to a position where the head of the tightening bolt can be seen from the working window, The coupling can be taken out by removing the fastening bolt.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an injection device of a metal injection molding machine according to an embodiment of the present invention, showing a state in which an injection piston is retracted most.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view of a main part of an injection device according to a second embodiment;
It is a figure showing the state where the injection piston advanced most.

FIG. 5 is a sectional view taken along line CC of FIG. 4;

FIG. 6 is a sectional view of a main part of an injection device according to a third embodiment;
It is a figure showing the state where the injection piston retreated most.

FIG. 7 is a perspective view of a coupling used in an injection device according to a third embodiment.

FIG. 8 is a configuration diagram of an injection device of a conventional metal injection molding machine, showing a state in which an injection piston is most advanced.

FIG. 9 is a sectional view taken along line DD of FIG. 8;

FIG. 10 is a perspective view of a coupling used in a conventional injection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection housing 6 Screw 7 Injection piston 10 Output shaft 12, 12a Coupling 13, 14 Outer peripheral groove 15 Tightening bolt 19, 19a Working window 20, 20a Cover 21, 22 Wall surface 23, 23a Elastic body (elastic member) 24 Fixing bolt 27 pin

Claims (5)

[Claims] 1. An elastic member (23) for abutting a front end of an injection piston (7) before the injection piston (7) reaches a most advanced position is installed on an inner surface of the injection housing (1). Equipment for metal injection molding machines. 2. The injection apparatus according to claim 1, wherein said elastic member is made of hard rubber or plastic. 3. The injection device of a metal injection molding machine according to claim 1, wherein said elastic member (23) is formed in an annular shape. 4. A work window (19a) is formed in a wall of the injection housing (1) facing the outside of a portion where the elastic member (23a) is not installed, wherein the elastic member is formed in a partially annular shape. 3. The injection device of a metal injection molding machine according to claim 1, wherein: 5. An engagement between the output shaft (10) rotatably inserted into the injection piston (7) and the screw (6) inserted into the output shaft (10) by the coupling (12a). Even when the coupling (12a) is tightened with the attached bolt (15), the coupling (12a) is loosely fitted so that the coupling (12a) can rotate, and the coupling (12a) is connected to the output shaft (1).
5. The injection device of a metal injection molding machine according to claim 1, wherein the screw is fixed to the screw (6) by a fixing bolt (24).