JPS5848114Y2 - Injection molding machine - Google Patents

Description

[Detailed description of the invention] This invention is a Puno plastic method in which raw materials are plasticized by a rotating screw inside a heating cylinder, the plasticized raw materials are stored in an injection cylinder, and a predetermined amount of raw materials is injected by a plunger. This relates to injection molding.

In this type of pre-plastic injection molding machine, it is necessary to prevent the raw material from flowing back into the screw in the heating cylinder during injection.

For this reason, in conventional apparatuses, a ring-type check valve is provided at the tip of the squeegee, or a shutoff valve is provided in the passage for feeding the plasticized raw material to the injection cylinder.

Ring-type check valves have problems with material accumulation and sealing surface wear, and shut-off valves are complicated to operate.

This invention prevents the raw material from flowing back into the screw when the plasticized raw material is injected from the injection tube into the mold cavity in a pre-plastic injection molding machine by changing the shape of the tip of the screw. It is.

Next, the apparatus of the present invention will be explained according to the drawings.

Reference numeral 1 indicates a heating cylinder, and reference numeral 2 indicates a screw inserted into the heating cylinder 1, which rotates within the heating cylinder 1.

The outer diameter of the screw 2 is such that the tip has a large diameter and the other parts have a small diameter.

2a indicates a large diameter portion, and 2b indicates a small diameter portion. 2C is a connection portion between the screw groove of the small diameter portion 2b and the screw groove of the large diameter portion 2a of the screw 2, and has a tapered shape.

The inner diameter of the heating cylinder 1 also has two stages to match the shape of the screw, and 1C is a connecting part between the large diameter part 1a and the small diameter part 1b.
It has a tapered shape.

The screw 2 is rotated by the drive of a motor 3.

4 is a screw operating hydraulic cylinder that reciprocates the screw; the screw 2 is a screw operating hydraulic cylinder 4;
It is connected to the rod 5 of the piston inserted into the piston.

6 is an injection cylinder, 7 is a plunger inserted into the injection cylinder, and 8 is a hydraulic cylinder for actuating the plunger for actuating the injection plunger.

Piston 9 inserted into hydraulic cylinder 8 for plunger operation
The rod 10 is connected to the injection plunger 7.

The tip of the heating cylinder 1 is connected to the injection cylinder 7 in a perpendicular direction.

Reference numeral 11 denotes a nozzle, which is provided in the injection tube 6.

12 is a fixed plate, 13 is a movable plate, and 14 is a stay.

15 is a mold. The movable platen 13 reciprocates with respect to the fixed platen 12.

16 is a speed reducer that reduces the rotation of the motor 3 and transmits it to the screw 2.

17 is a machine frame.

Reference numeral 18 denotes a hopper for storing raw materials so as to supply them into the heating cylinder 1.

Reference numeral 19 denotes a switching valve that supplies oil to the two ports 20 and 21 of the screw operating hydraulic cylinder 4, and releases oil from each of the ports to the tank.

Reference numeral 22 supplies oil to the ports 23 and 24 of the plunger operating hydraulic cylinder 8, and releases oil from each of the ports to the tank.

Next, the operation will be explained.

When the motor 3 is driven and the screw 2 is rotated, the raw material falls from the hopper onto the screw 2, and the raw material is sent to the tip of the screw 2 while being plasticized by the heating of the heating cylinder 1.

At this time, the screw 2 moves backward due to the force of the forward movement of the raw material, so the solenoid a of the switching valve 19 is energized to supply high-pressure oil to the port 20 of the screw operating hydraulic cylinder 4 to prevent the screw 2 from moving backward. Tapered part 2C
Make sure that the tapered portion 1C of the inner diameter of the heating cylinder 1 does not come into close contact with each other.

The raw material plasticized by the screw 2 enters the injection cylinder 6.

At this time, the switching valve 22 is kept at the neutral position and the injection plunger 7 is pushed up by the raw material pressure.

When a predetermined amount of raw material is accumulated in the injection cylinder 6, the rotation of the screw 2 is stopped.

At the same time, the solenoid b of the switching valve 22 is energized, high-pressure oil is caused to flow into the port 23 of the hydraulic cylinder 8 for plunger operation, the injection plunger is lowered, and the plasticized raw material stored in the injection cylinder is transferred to the mold cavity 25. eject into.

Also, at the same time as stopping the rotation of the screw 2, the solenoid a of the switching valve 19 is demagnetized, and when the injection plunger descends, the screw 2 retreats to the right in the figure due to the pressure inside the injection cylinder, and the screw 2 The tapered portion 2C and the tapered portion 1C of the inner diameter of the heating cylinder 1 are in close contact with each other, and the plasticizing raw material does not flow back into the heating cylinder 1.

After the plasticizing raw material is injected into the mold cavity and cooled, the mold is opened and the molded product is taken out.

As explained above, the present invention eliminates the use of a ring valve check valve or shutoff valve on the screw in a pre-plastic type injection molding machine, and allows the raw material to flow into the heating cylinder 1 during raw material injection by a slight movement of the screw. We were able to prevent backflow.

[Brief explanation of drawings]

FIG. 1 is a front view including a cross section of the present invention. 1: heating cylinder, 1C: heating cylinder inner diameter connection part, 2: screw,
2C: Screw groove connection part, 6: Injection tube, 7: Injection plunger, 15: Mold.

Claims (1)

[Scope of utility model registration request] A mold clamping device that opens and closes the mold 15 and a screw rotating in a heating cylinder plasticize the raw material, store the plasticized raw material in an injection cylinder 6, and insert an injection plunger 7 into the injection cylinder 6. A screw 2 for plasticizing the raw material in a pre-plastic injection molding machine that injects the plasticized raw material stored in the injection cylinder 6 into the mold cavity 25 by hydraulically operating the injection plunger 7. The shape of the screw is made into a two-stage shape having a screw outer diameter large diameter part 2a and a screw outer diameter small diameter part 2b, and the screw groove connecting part 2C between the screw outer diameter large diameter part 2a and the screw outer diameter small diameter part 2b is made into a tapered shape and heated. A heating cylinder inner diameter large diameter part 1a and a heating cylinder inner diameter small diameter part 1b are provided so that the screw 2 can be inserted into the inner diameter of the cylinder 1, and the heating cylinder inner diameter between the heating cylinder inner diameter large diameter part 1a and the heating cylinder inner diameter small diameter part 1b is The connecting portion 1C has a tapered shape, and the injection plunger 7
When injecting plasticized resin by the operation of the screw 2
is retracted, and the tapered connecting portion 2e of the screw 2 and the tapered connecting portion 1C of the inner diameter of the heating cylinder come into close contact, thereby preventing the plasticizing raw material from flowing back into the small diameter inner diameter portion 1C of the heating cylinder 1, and An injection molding machine characterized by applying back pressure to the screw 2 during rotation.