JPS6345017A - Injection molding machine - Google Patents

Abstract

PURPOSE:To make an apparatus smaller to avoid an energy loss and to improve productivity, by making an injection nozzle slide when a material is injected, and making a pressure holding possible without being dependent on the injection nozzle after injection. CONSTITUTION:When an injection piston 56 is elevated while a value 72 is closed, an injection nozzle 51 is elevated and its apex presses a piston nozzle 31. While the valve 72 is opened, a material is poured and applied in a cavity 21. After injection movement, the valve 72 is closed and an oil pressure piston 57 is lowered. The injection nozzle 51 is returned to an original position by means of a returning spring 73. A liquid pressure is added onto the piston nozzle 31 by a liquid pressure from a dwelling apparatus 37, and a mold apparatus 20 is kept in a dwelling state. In this case, when the area ratio of the liquid pressure side and the dwelling chamber side of the piston nozzle 31 is made roughly the same as the area ratio of the liquid pressure piston 57 and the injection piston 56, a pressing force applied the material in the dwelling chamber 29 is kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection molding machine used for injection molding of plaster-like ceramics and plastics.

(Conventional technology) 7 and 8 show the prior art.

Part 7 is a conventional example of a plastic injection molding machine.
1 is a mold device, and 2 is an injection nozzle device.

The mold device 1 includes a mold 4 having a cavity 3 therein, which can be pressed, clamped and opened by a cylinder 5, etc., and is provided with a spool 6 having a nozzle for one of the molds 4.

In the injection nozzle device 2, an injection nozzle 9 is attached to the tip of a cylinder 8 which has a material input hopper 7 at one end in the longitudinal direction, and the cylinder 8 including the injection nozzle 9 is moved forward and backward by a moving drive means (not shown). ing. A screw 10 is inserted into the cylinder 8 and can be rotated about its axis by a motor 11.

Therefore, in this conventional example, the cylinder 8 and the screw 10
The material 12 is kneaded and melted in cooperation with the
A predetermined injection molding is performed by injecting material into the cavity 3 via the spool 6 while the nozzle 9 is pressed against the die nozzle by advancing the injection nozzle device 2.

FIG. 8 shows an injection molding machine for molding plaster-like ceramics, which comprises a mold device 1 having a cavity 3 and a plunger-shaped injection nozzle device 2 having a piston 14 interlocked with a hydraulic cylinder 13. The device 2 can be raised and lowered by each plunger, and the material in the cylinder 8 is delivered to the cavity 3 through the injection nozzle 9 and the die nozzle 6A.
It is said that it can be supplied (injected) within the body. In addition, when using this slurry-like ceramic, a mold having a porous structure is used.

(Problems to be Solved by the Invention) Incidentally, in all of the above conventional examples, since the entire injection nozzle device 2 is movable forward and backward with respect to the mold device 1, the entire device becomes large and , requiring large amounts of energy and complex control.

In addition, during molding, it is necessary to cool the material after pressurizing and injecting it into the cavity 3, and in order to obtain a molded product of good quality without cavities, the mold must be clamped and the injection pressure must be maintained for a long time. There must be. However, in the past, the pressure was maintained by the clamping force of the hydraulic cylinder 5 and by continuing to inject the material from the injection nozzle 9. Therefore, after the injection operation is completed, the material is immediately injected into the next mold device 1. However, there was a drawback that productivity was lacking, and energy loss was extremely large.

In view of the above-mentioned conventional problems, the present invention allows the injection nozzle to slide when injecting the material, maintains pressure without relying on the injection nozzle after injection, and furthermore maintains the pressure from the completion of injection. The same pressure as after injection is ensured even when transitioning to
The purpose is to prevent energy loss, improve productivity, and simplify control.

(Means for Solving the Problems) As specific means for achieving the above object, the present invention includes a mold device 20 having a cavity 21 inside, and an injection nozzle 51 for injecting material into the cavity 21. In an injection molding machine comprising an injection nozzle device 52, the mold device 20 has a pressure holding chamber 29 communicating with the cavity 21, and injects material from the injection nozzle 51 into the cavity 21 through the pressure holding chamber 29. A piston nozzle 31 having a material passage 33 and slidably inserted into a pressure holding chamber 29 is provided, and a pressure holding device 37 is provided which applies fluid pressure to the piston nozzle 31 in the holding pressure direction after injection is completed. The injection nozzle device 22 is provided with a plunger device 52 having an injection piston 56 and a hydraulic piston 57 for generating injection pressure thereon, and a piston nozzle is provided on the injection piston 56 side of the plunger device 52 during material injection. 31 and is slidably moved away from the piston nozzle 31 when the plunger device 52 is depressurized.
The area ratio with respect to the 9 side is made approximately the same as the area ratio between the fluid pressure piston 57 and the injection piston 56 in the plunger device 52.

(Function) When the injection piston 56 is raised by the hydraulic cylinder 57 of the plunger device 52 with the valve 72 closed,
Thrust is applied to the injection nozzle 51 . When this thrust becomes larger than the return spring 73, the injection nozzle 51
6 and its tip is pressed against the piston nozzle 31.

Further, when the injection piston 56 is raised, a predetermined pressure is generated in the material, and a contact force that can seal the injection pressure between both nozzles 3L51 is applied.

When the valve 72 is opened in this state, the injection cylinder 54
and the cavity 21 are communicated through the injection passage 67 of the nozzle 51, etc., and a predetermined material is injected and filled into the cavity 21 to perform injection molding.

When the required injection operation is completed, the valve 72 is closed and the hydraulic piston 57 is lowered to open the injection cylinder 5.
4, the injection nozzle 51 is returned to its original position by the return spring 73, fluid pressure is applied to the piston nozzle 31 by the fluid pressure from the pressure holding device 37, and the mold device 20 is brought into a pressure holding state. At this time, since the area ratio between the fluid pressure side of the piston nozzle 31 and the pressure holding chamber side and the area ratio between the fluid pressure piston 57 and the injection piston 56 of the plunger device 52 are the same, the injection is performed after the injection operation is completed. Even when the nozzle 51 descends, the material pressing force in the pressure holding chamber 29 is maintained at the same pressure as after the completion of injection.

(Embodiment) FIGS. 1 to 6 show a first embodiment of the present invention,
This is applied to a clay ceramic injection molding machine.

Here, the slurry-like ceramic used as the raw material (material) is made of fine ceramic particles with an average particle size of about 0.4 to 2.5 μm, to which water is added to give them viscosity.
A minimum amount of binder is added to provide fluidity.

In FIG. 1, 20 is a mold device having a cavity 21 therein, and 22 is an injection nozzle device.

The mold device 20 connects the upper plate 23 and the lower plate 24 with mold clamping bolts 2.
5, an upper mold 26 is attached to the upper plate 23, and a lower mold 27 is attached to the lower plate 24, each having a cavity 21 communicating with the spool 28 inside.

Note that this cavity 21 is formed of a porous type, and can be closed and opened.

A pressure holding chamber 29 communicating with the spool 28 is formed in the lower plate 24, and a piston chamber 30 having a larger diameter than the liquid chamber 29 is formed at the lower end of this pressure holding chamber 29.
The piston nozzles 31 are slidably fitted to each other. A check valve 3 is provided at the axis of the piston nozzle 31.
2, a material passage 33 is formed with a piston nozzle 3
The lower end of 1 is a spherical portion 34.

Further, a piston nozzle holder 35 is attached to the lower plate 24, and a hole 36 communicating with the piston chamber 30 is formed in the holder 35, and a pressure holding device 37 and a hydraulic pressure generating device 38 are installed in this hole 36. It is connected.

The pressure holding device 37 includes an accumulator 391, a manual switching valve 40, and a check valve 41. The hydraulic pressure generator 38 includes an oil tank 42, a motor 43, a hydraulic pump 44, a check valve 4S, a relief valve 46, a pressure reducing valve 47, and an electromagnetic switching valve 4.
Consists of 8th grade. 49 is a quick joint, and 50 is a flexible hose.

The injection nozzle device 22 includes an injection nozzle 51, a plunger device 52, a material supply device 53, and the like.

The plunger device 52 includes an injection cylinder 54 and a hydraulic cylinder 55 that are provided on the same axis above and below, and these cylinders 5
4, an injection piston 56 which is slidably provided within 55;
and hydraulic (fluid pressure) piston 57, both pistons 56.5
The injection cylinder 54 is provided with a piston loft 58 that vertically connects the cylinders 7 to 7, and the material in the injection cylinder 54 is injected or depressurized by the injection piston 56 by vertical movement of the hydraulic piston 57.

The hydraulic cylinder 55 is connected to the electromagnetic switching valve 48 above and below the hydraulic piston 57. The area ratio Do"/Do" between the hydraulic pressure side and the pressure holding chamber side of the piston nozzle 31 and the area ratio Dc"/dc" between the hydraulic piston 57 and the injection piston 56 of the plunger device 52 are made to be approximately the same. It is configured.

A material supply device 53 is connected to the piston chamber of the injection cylinder 54 via a material supply hole 59 . The material supply device 53 includes a cylinder 61 with a hopper 60, a screw 62 rotatably provided in the cylinder 61, a motor 63 for driving the screw 62, and a check valve 64.
The material introduced from the pumper 60 is supplied into the injection cylinder 54 through the check valve 64 by the rotation of the screw 62.

An adapter 66 having a vertical nozzle mounting hole 65 is attached to the upper end of the plunger device 52. The injection nozzle 51 has an axial injection passage 67, and
It has a collar 68 in the middle of the outer periphery, and the nozzle mounting hole 6
5 so as to be slidable up and down. Injection nozzle 5
The end surface of the nozzle head 69 at the upper end of the nozzle head 69 can freely approach and separate from the spherical surface section 34, and has a seal 70 that prevents material leakage when the nozzle head 69 is pressed against and in contact with the piston nozzle 31.

Here, the material passage 33 and the injection passage 65 are aligned on the same vertical line in this example, and material can be supplied to the cavity 21.

Furthermore, in the middle of the injection passage 42, there is a manual switching passage 71.
In this example, the valve 72 has a two-way ball shape and can freely open and close the material passage 33 and the injection passage 67.

Further, the injection nozzle 51 has a coil-shaped return spring 73 between its collar 68 and the inside of the adapter 66, and this spring 73 allows the injection nozzle 51 to be retracted into the injection cylinder 54 side.

During injection molding, it operates as follows.

FIG. 2 shows the state before injection, with the valve 72 closed and the piston nozzle 31 and nozzle head 69 facing each other vertically.

In this state, the plunger device 52 is
At the same time, the electromagnetic switching valve 48 is switched to the injection side. Then, pressure oil is supplied to the lower side of the hydraulic cylinder 55 via the pump 44, the pressure reducing valve 47, and the electromagnetic switching valve 48, the hydraulic piston 57 is pushed up, and the injection piston 56 pressurizes the material. At this time, since the passage 67 of the injection nozzle 51 is closed by the valve 72, the nozzle 51 rises against the spring 73 as shown in FIG. is pressed and both are sealed,
The piston nozzle 31 will be raised (see FIG. 3).

When the valve 72 is opened in this state, the injection cylinder 54
The material inside is injected into the cavity 21 by pushing open the check valve 32 through the injection passage 67, the runner 28, etc., and also fills the pressure holding chamber 29 (see FIG. 4).

Furthermore, since the area of the piston nozzle 31 on the pressure holding chamber 29 side and the area of the injection nozzle 51 are larger, due to the area difference, the piston nozzle 31 and the injection nozzle 51 descend while remaining in contact with each other, and the piston Nozzle 31 is presser foot 3
5 (see Figure 5).

At this time, the supply pressure to the mold device 20 after completion of injection is:
The pressure is increased to the multiplicative product of the control Il pressure of the pressure reducing valve 47 of the hydraulic pressure generator 38 and the ratio of the hydraulic piston area to the injection piston area.

Next, when the valve 72 is closed and the electromagnetic switching valve 48 is switched to the pressure reducing side, the hydraulic piston 57 of the plunger device 52 is lowered, and the injection piston 56 is lowered, so that the pressure inside the injection cylinder 54 is reduced, and the injection nozzle 51 is returned to the old position by the spring 73.

On the other hand, the pressure oil line on the supply side to the pressure holding device 37 is connected to the secondary side of the pressure reducing valve 47 through piping and a quick joint. After the injection operation is completed, if the switching valve 40 and manual lever of the pressure holding device 37 are turned to the left, the pressure oil discharged from the pump 44 of the hydraulic pressure generating device 38 and regulated by the pressure reducing valve 47 is transferred to the accumulator 3.
9 and the hydraulic side of the piston nozzle 31 of the mold device 20.

The pressure on the hydraulic side of the piston nozzle 31 of the mold device 20 and the pressure on the hydraulic piston side of the plunger device 52 are both regulated by the same pressure reducing valve 47, and are built in the mold device 20. . Since the area ratio between the hydraulic pressure side and the pressure holding chamber side of the piston nozzle 31 and the area ratio between the hydraulic piston 57 and the injection piston 56 of the plunger device 52 are the same, after the injection operation is completed, the injection nozzle 51 descends. Even if the connection with the lower end of the piston nozzle 31 is opened, the pressure holding chamber 2
The material pressing force in step 9 is maintained at the same pressure as after injection is completed (
(See Figure 6). This prevents the holding pressure from decreasing due to water and solvent contained in the material coming out of the cavity 21 of the mold device 20.

The switching valve 40 of the pressure holding device 37 is manually operated on the concave side, but it is also possible to automate the process from the end of injection to the completion of pressure holding operation to the mold device 20 by using an electromagnetic switching valve. be.

Furthermore, although the pressure reducing valve 42 is used on the concave side to regulate the injection pressure, it is also possible to use other means, such as a relief valve.

(Effects of the Invention) According to the present invention, since the injection nozzle is configured to slide and be pressed against the piston nozzle when injecting the material, there is no need to move the entire injection nozzle device as in the conventional case. The entire structure can be made smaller, no large amount of energy is required for movement, and control is easy. Moreover,
After material is injected into the cavity of the mold device, fluid pressure is applied to the piston nozzle by a pressure holding device to maintain the pressure. Therefore, after the material injection operation is completed, it is immediately injected into another mold device. It is possible to shift to injection operation, improving productivity. In addition, since the area ratio between the fluid pressure side of the piston nozzle and the pressure holding chamber side is approximately the same as the area ratio between the fluid pressure piston and the injection piston of the plunger device, the injection nozzle separates from the piston nozzle after the injection operation is completed. However, the pressure applied to the material can be maintained at the same level, and the pressure can be easily controlled.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIGS. 2 to 6 are process explanatory diagrams, and FIGS. 7 and 8 are sectional views showing a conventional example. 20-molding mold device, 21-cavity, 22--injection nozzle device, 29--pressure holding chamber, 31-piston nozzle, 37--pressure holding device, 38--hydraulic pressure generator, 51-
Injection nozzle, 52--plunger device, 53--material supply device, 56--injection piston, 57--hydraulic piston.

Claims (1)

[Claims] (1) In an injection molding machine comprising a mold device 20 having a cavity 21 inside and an injection nozzle device 52 having an injection nozzle 51 for injecting material into the cavity 21, the mold device 20 communicates with the cavity 21. The piston nozzle 3 has a pressure holding chamber 29 and a material passage 33 for injecting the material from the injection nozzle 51 into the cavity 21 through the pressure holding chamber 29, and is slidably fitted into the pressure holding chamber 29.
1, and a pressure holding device 37 that applies fluid pressure to the piston nozzle 31 in the holding pressure direction after injection is completed, and the injection nozzle device 22 has an injection piston 56 and a pressure holding device 37 that applies fluid pressure to the piston nozzle 31 in the holding pressure direction. A plunger device 52 having a piston 57 is provided on the injection piston 56 side of the plunger device 52, and is slidable so as to be pressed against the piston nozzle 31 during material injection and to be moved away from the piston nozzle 31 when the plunger device 52 is depressurized. Injection nozzle 5
1, and the area ratio between the fluid pressure side of the piston nozzle 31 and the pressure holding chamber 29 side is made approximately the same as the area ratio of the fluid pressure piston 57 and the injection piston 56 in the plunger device 52. Machine.