JP3454769B2 - Injection equipment for metal injection molding machine - Google Patents

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 them as a main component (hereinafter referred to as a metal material).

[0002]

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

As shown in FIG. 8, the heating cylinder 2 is fixed to the front part of the injection housing 1 of the injection device 17 by mounting bolts 28, and the rotary motor 3 is fixed to the rear part. A heater 4 is attached to the outer circumference of the heating cylinder 2, and a material hopper 5 is attached to the rear part of the heating cylinder 2. A screw 6 is inserted into 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 arranged between the oil chamber 8 for advancing the injection piston 7 and the wall surface 21 of the injection piston 7 and the wall surface 22 of the injection housing 1. The oil chamber for retreat is formed in. The rear part of the screw 6 is inserted into the front part of the output shaft 10 which is inserted into the injection piston 7 and is rotatably held by the bearings 25 and 26, and the rear end face 30 of the screw 6 is located in the 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 D-D of 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 parts. The coupling 12 is fitted and fixed integrally with a tightening bolt 15.

Next, the operation will be described.

First, in the weighing process, granular particles, cutting pieces,
Metal materials such as crushed pieces (hereinafter referred to as metal material chips)
Is put into 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 chips dropped from the material hopper 5 into the heating cylinder 2 are heated along the spiral groove on the surface of the screw 6. While being sent to the front of the tube 2, the material is heated and kneaded to be 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 tube 2.

In the next injection step, the entire injection device 17 is moved forward, and the nozzle 18 at the end of the heating cylinder 2 is brought into contact with the sprue bush of a mold (not shown), and is moved into the forward movement oil chamber 8 of the injection cylinder. When pressure oil is supplied to drive the injection piston 7 in the forward direction 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 and the mold. It is injected into the mold and filled in 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 and the metal molded product formed in the cavity shape is taken out.

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 or the inner surface of the heating cylinder 2, the coupling 12 can be seen through the work 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
Output shaft 1 from 9 to the angle at which the head of tightening bolt 15 can be seen
0 is rotated, the tightening bolt 15 is loosened and removed, and the coupling 12 is removed.

[0012]

Generally, metal materials are
Since the specific heat is small and the thermal conductivity is good, the molten metal injected into the mold is immediately solidified, and filling failure is likely to occur. Therefore, in injection molding of a metal material, it is necessary to inject the molten metal material into the mold at a high speed, and the forward speed of the injection piston in the metal injection molding machine is 10 times or more that of the plastic injection molding machine. That is, a high speed of 2 to 4 m / s is required.

When the injection piston, the output shaft connected to the injection piston, the screw, etc. (hereinafter referred to as the injection piston, etc.) are united and advanced at a high speed, a large impact force is generated when the injection piston is stopped rapidly. . Actually, the brake is applied by cutting off the pressure oil flowing into the forward movement oil chamber of the injection cylinder or by cutting off the pressure oil flowing out of the reverse movement oil chamber. Since it ends in front and back, it overcomes the inertial force of the injection piston with a large mass and the high speed forward movement 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 forming the forward oil chamber 8 shown in FIG. 8 collides with the wall surface 22 of the injection housing 1. At that time, a large collision sound is generated, and the impact thereof deteriorates the durability of related parts.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and reduces the collision of the injection piston with the injection housing to reduce noise and improve the durability of the apparatus. An object of the present invention is 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, the elastic member that abuts the front end of the injection piston on the inner surface of the injection housing before the injection piston reaches the most advanced position. As a result, the front end of the injection piston comes into contact with the elastic member, whereby the forward movement of the injection piston and the like is decelerated.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to 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, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a line BB of 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 with a mounting bolt 28, and a rotary motor 3 such as a hydraulic motor or an electric motor is fixed to a rear portion thereof. There is. A heater 4 is attached to the outer periphery of the heating cylinder 2, and a material hopper 5 is provided at the rear of the heating cylinder 2.
Is attached. A screw 6 is placed inside the heating cylinder 2.
Is rotatably and axially movable.

The injection piston 7 built in the injection housing 1 constitutes an injection cylinder together with the injection housing 1, and forms an advancing oil chamber 8 and a retreating oil chamber 9 of the injection piston 7. Bearings 25 and 26 inserted into the injection piston 7
Front hole 29 of the output shaft 10 rotatably held by
The rear portion of the screw 6 is inserted into the rear end of the screw 6 such that the mutual rotation is restricted by a spline or the like, and the rear end surface 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 12 which is a disc in half is fitted in an outer peripheral groove 13 at the rear of the screw and an outer peripheral groove 14 at the front of the output shaft, and they are integrated by a tightening bolt 15. It is fixed to.

An annular elastic body 23 is attached to the inner surface of the injection housing 1 for abutting the front end of the injection piston 7 before the injection piston 7 reaches the most advanced position, and it can be expanded and contracted in the axial direction by a plurality of pins 27. Held in. In addition, before the injection piston 7 reaches the most advanced position, it 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.

As the elastic body 23, hard rubber or plastic having oil resistance such as chloroprene rubber and nitrile rubber and having a hardness of HS90 is used. Also,
The size of the elastic body 23 varies depending on the size of the machine, but 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, in the weighing step, the metal material chips are put into 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 chips dropped from the material hopper 5 into the heating cylinder 2 are heated along the spiral groove on the surface of the screw to the heating cylinder 2. 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 moved forward, and the nozzle 18 at the tip of the heating cylinder 2 is brought into contact with the sprue bush of a mold (not shown), and is moved to the advance oil chamber 8 of the injection cylinder. Pressure oil is supplied to drive the injection piston 7 in the forward direction, and its operation is transmitted to the screw 6 via the output shaft 10. As a result, when the screw 6 advances, 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 is 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 before the most advanced position and is decelerated, and a large impact force is blocked in cooperation with the hydraulically controlled brake.

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

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 or the inner surface of the heating cylinder 2, the coupling 12 can be seen through the work 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 tightening bolt 15 can be removed, the tightening bolt 15 is loosened and removed, and the coupling 12 is removed. . As a result, the screw 6 can be pulled out from the output shaft 10 and pulled out in front of the heating cylinder 2.

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

In this embodiment, the elastic body 23 of the injection device 17 is used.
a has a partial annular shape, and the wall of the injection housing 1 facing the outside of the portion where the elastic body 23a does not exist is also removed, so that the work window 1
9a is enlarged. This ensures a working window 19a larger than the outer diameter of the coupling 12 even when the injection piston 7 is in the most advanced position. The partially annular elastic body 23a may have a shape in which only one portion of the annular ring is removed. However, in order to receive the impact force of the injection piston 7 or the like evenly, the plurality of elastic bodies 23a are arranged on the circumference. It is preferable to arrange them evenly. Further, for convenience of illustration, the screw 6
Also, since the outer diameter of the coupling 12 is exaggerated, the elastic body 23a has a half-moon shape, but in reality, it has a shape in which a part of the ring is cut out.

According to this embodiment, even when the injection piston 7 is in the most advanced position, the cover 20a is removed and the tightening bolt 15 is removed, whereby the coupling 12 is removed.
Can be removed 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 to move the coupling 12 together with the output shaft 10 until the tightening bolt 15 is seen from the working window 20a. After rotating, remove it.

If 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. By rotating the heating cylinder 2 as a whole together with the screw 6 with respect to the injection housing 1 and setting the tightening bolt 15 at an angle visible from the work window 20a, the coupling 12 can be removed.

Next, the injection apparatus of the third embodiment will be described with reference to FIGS. 6 and 7. 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, but the coupling 12a of the present embodiment does not include the tightening bolt. Even when the screw 15 is tightened, the screw 6 and the output shaft 10 are loosely fitted in the axial direction and the radial direction so that the screw 6 and the output shaft 10 can rotate.
It is designed to be blocked by tightening the fixing bolt 24 screwed to a.

For this reason, the tightening bolts 15 are attached to the work window 20a.
If the angle is not visible, the fixing bolt 24 is loosened, and the coupling 12a is manually rotated so that the tightening bolt 15 is visible from the working window 20a.
Can be removed.

[0037]

Since the present invention is constructed as described above, the following effects can be obtained. (A) By providing the buffer 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 apparatus. (B) When the screw is kept at the most advanced position due to the inertial force of the injection piston or the like, the mold is partially spread by the molten metal material filled in the cavity, which causes a large flash in the molded product. According to the invention, at the moment when the high pressure of the pressure oil supplied to the advancing oil chamber is removed, the repulsive force of the elastic body overcomes the inertial force of the injection piston or the like to retract the injection piston and retract the screw. It is possible to reduce the flash generated on the molded product. (C) According to the invention of claim 4, even when the injection piston cannot be retracted at the most advanced position, the tightening bolt can be loosened to remove the coupling. (D) According to the invention of 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 work window, The coupling can be taken out by removing the tightening bolt.

[Brief description of 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, and is a view showing a state in which an injection piston is finally retracted.

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

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

FIG. 4 is a sectional view of an essential part of an injection device according to a second embodiment,
It is a figure which shows the state which the injection piston advanced most.

5 is a cross-sectional view taken along line CC of FIG.

FIG. 6 is a sectional view of an essential part of an injection device according to a third embodiment,
It is a figure which shows the state which the injection piston retracted last.

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

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

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

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

[Explanation of symbols]

1 injection housing 6 screws 7 injection piston 10 Output shaft 12,12a coupling 13, 14 outer peripheral groove 15 Tightening bolt 19, 19a Work window 20, 20a cover 21 and 22 wall 23, 23a Elastic body (elastic member) 24 fixing bolt 27 pin

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-112474 (JP, A) JP-A-6-582 (JP, A) JP-A-2001-105119 (JP, A) Actual development Sho-59-165289 (JP, U) Actually open 1-11-1616 (JP, U) Actually open 57-32757 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B22D 17/20

Claims (5)

(57) [Claims] 1. An elastic member (23) for abutting a front end of the injection piston (7) on the inner surface of the injection housing (1) before the injection piston (7) reaches the most advanced position. Injection device for metal injection molding machine. 2. The injection device for a metal injection molding machine according to claim 1, wherein the elastic member (23) is made of hard rubber or plastic. 3. The injection device for a metal injection molding machine according to claim 1, wherein the elastic member (23) has 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 a partial annular shape. The injection device of the metal injection molding machine according to claim 1 or 2. 5. The output shaft (10) rotatably inserted into the injection piston (7) and the fitting of the coupling (12a) to the screw (6) inserted into the output shaft (10) are tightened. The coupling (12a) is loosely fitted so that the coupling (12a) can be rotated even when the coupling (12a) is tightened with the attached bolt (15).
0) or a screw (6) fixed with a fixing bolt (24). The injection device of the metal injection molding machine according to any one of claims 1 to 4, wherein: