JP3025775B1 - Screw type plastic injection machine - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To facilitate material change and color change of a screw type pre-plastic injection machine. SOLUTION: A plunger 2 is rotatably arranged and connected to a rotation drive device, and a spiral groove 21 is formed on an outer peripheral surface. A plunger outer cylinder 1 has a maximum retreat position of a tip of the plunger 2. Discharge hole 11
Has been established. When the material is changed or the color is changed, the plunger 2 is rotated to scrape off the material attached to the inner surface of the heating injection cylinder 1 with the edge of the spiral groove 21 and discharge the material from the discharge hole 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw type pre-plastic injection machine.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional screw-type pre-plasticizer (pre-plastizer) type injection machine is composed of a heating injection cylinder (1) containing a plunger (2) and a screw (4). Communicates with the end of the heated outer cylinder (3)
The resin material melted in the heating outer cylinder (3) is filled at the tip of the heating injection cylinder (1), and the molten resin material is injected by advancing the plunger (2).

In the above screw type pre-plasticizer injection machine, the flow of the resin material which is charged from the hopper (31) into the heating outer cylinder (3) and is heated and melted is caused by the rotation of the screw (4). Since the materials are moved in order from the materials, the material change and the color change in the heating outer cylinder (3) can be performed very easily and quickly. Injection by the plunger (2) can guarantee an accurate extrusion pressure.

[0004]

The clearance between the plunger (2) and the heating injection cylinder (1) is about 0.03-0.05 mm, but the resin material adheres to the inner surface of the heating injection cylinder (1). This causes a problem when changing materials or changing colors. The present invention clarifies a screw-type pre-plasticizer injection machine that can remove a resin that is thinly attached to the inner surface of a heating injection cylinder and remains.

[0005]

According to the present invention, there is provided a screw type pre-plasticity injection machine comprising a heated injection cylinder (1) accommodating a plunger (2).
And the tip of the heated outer cylinder (3) containing the screw (4), and the resin material melted in the heated outer cylinder (3) is filled at the tip of the heated injection cylinder (1). , Plunger
In the screw type pre-plasticizer injection machine for injecting the molten resin material by the advance of (2), the plunger (2) is rotatably arranged and connected to the rotary drive device (6), and has a spiral groove (21) on the outer peripheral surface. The heating injection cylinder (1) has a discharge hole (11) penetrating the cylinder wall behind the maximum retreat position of the tip of the plunger (2).

[0006]

[Operation and Effect] During the molding operation, the plunger (2) is not rotated, but only reciprocates back and forth. The resin material supplied from the hopper (31) to the heating barrel (3) is sent to the heating injection barrel (1) side by rotation of the screw (4) while being heated by the heating barrel (3). The plunger (2) is retracted by the pressure of the molten resin material filling the tip of the heating injection cylinder (1).

When a predetermined amount of the molten resin material is filled in the heating injection cylinder (1), the plunger (2) is advanced to move the nozzle (1).
From 0), the molten resin material is injected into the mold cavity. The plunger (2) in the advanced position is retreated again by the supply of the molten resin from the heating outer cylinder (3) to the tip of the heating injection cylinder (1).

The above operation is repeated to perform injection molding.
While the plunger (2) is retracted, the mold is opened and the molded product is taken out.

At the time of changing the material or color of the resin, the plunger (2) is rotated in the direction in which the thrust is generated backward by the spiral groove (21). The resin material flowing out from the clearance between the plunger (2) and the heating injection cylinder (1) to the rear and remaining on the inner surface of the heating injection cylinder (1) is scraped off by the edge of the spiral groove (21), (21) By thrust by rotation,
It gradually moves backward and is discharged from the discharge hole (11).

If the plunger (2) is reciprocated back and forth with a short stroke during the rotation of the plunger (2), the effect of writing down the remaining resin material is improved.

[0011]

FIG. 1 shows only the main part of an injection machine of an injection molding apparatus. A connecting block (9) connects a tip of a heating injection cylinder (1) in which a plunger (2) is reciprocally movable and rotatable in an axial direction and a tip of a heating outer cylinder (3) in which a screw (4) is incorporated. ).

The heating injection cylinder (1) and the heating outer cylinder (3) are provided with a heater (not shown) for heating the resin material in the cylinder. A heating injection cylinder is provided in the communication channel (51) of the connection block (9).
A backflow prevention valve (51) for preventing backflow of the resin material from (1) to the heating outer cylinder (3) side is provided.

A screw (4) is rotatably housed in the heating outer cylinder (3), and the screw (4) has a rotary driving device (8).
Are linked. A hopper (3) for feeding a pellet-shaped resin material into the heating outer cylinder (3) is provided in the heating outer cylinder (3).
1) is provided.

A plunger (2) is reciprocally accommodated in the heating injection cylinder (1), and a reciprocating drive (7) such as a hydraulic cylinder drive and a servomotor drive is connected to the reciprocating drive (7). Have been. The connection block (9) has a heated injection cylinder
A nozzle (10) protrudes concentrically with (1).

The injection device having the above construction is the same as the conventional screw type pre-plastic injection machine shown in FIG. 3, and the feature of the present invention is that the plunger (2) is not only reciprocated but also rotatably heated and injected. A spiral groove is provided at the point which is housed in the cylinder (1) and is connected to the rotary drive device (6), and at the outer periphery of the plunger (2).
(21) is established.

The rotary driving device (6) is provided on a slide base (61) that slides integrally with the plunger (2), and its structure is well known in a conventional in-line injection machine, and a description thereof will be omitted. I do.

The spiral groove (21) on the outer periphery of the plunger (2) is formed shallow except for both ends of the plunger (2).
The groove bottom diameter C of (21) is larger than the diameter of the plunger (2) by one.
And the diameter C of the plunger (2) is 0.01 to 0.02 mm smaller than the inner diameter of the heating injection cylinder (1).

When the plunger (2) is advanced to the nozzle (10) side at the maximum, the heating injection cylinder (1) has a cylindrical wall corresponding to the end position of the spiral groove (21) of the plunger (2). A discharge hole (11) is opened through the hole. The position of the discharge hole (11) is located rearward of the tip of the plunger (2) on the nozzle (10) side when the plunger (2) is retracted to the maximum. A known split mold device (not shown) and the like are provided in front of the nozzle (10).

However, at the time of molding operation, the plunger (2)
Is stopped, and only reciprocating movement is performed. Hopper (31)
The resin material charged into the heating barrel (3) from the heating barrel
While being heated by (3), it is sent to the heated injection cylinder (1) side by the rotation of the screw (4). Plunger by the pressure of the molten resin material filling the tip of the heated injection cylinder (1)
(2) retreats.

When a predetermined amount of the molten resin material is filled in the heating injection cylinder (1), the rotation of the screw (4) is stopped, and the plunger (2) is advanced to move the nozzle (10) into the mold cavity. Inject molten resin. Nozzle of plunger (2)
The spiral groove (21) is not provided at the tip on the (10) side, and the molten resin does not escape backward through the spiral groove (21).

The screw (4) rotates again and the heated injection cylinder
(1) The molten resin is supplied to the plunger at the forward position.
(2) retreats. The above operation is repeated to perform injection molding. While the plunger (2) is retracted, the mold is opened and the molded product is taken out.

When the material or color of the resin is changed, the plunger (2) is rotated in the direction in which the thrust is generated backward by the spiral groove (21). The resin material flowing out from the clearance between the plunger (2) and the heating injection cylinder (1) to the rear and remaining on the inner surface of the heating injection cylinder (1) is scraped off by the edge of the spiral groove (21), Due to the thrust of (21), it gradually moves backward and is discharged from the discharge hole (11). Plunger
When the plunger (2) is reciprocated back and forth with a small stroke during the rotation of (2), the effect of writing off the remaining material is increased.

The present invention is not limited to the configuration of the above embodiment, and various modifications can be made within the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a sectional view of an injection machine.

FIG. 2 is a sectional view of a main part inside a heating injection cylinder.

FIG. 3 is a sectional view of a main part of a conventional injection machine.

[Explanation of symbols]

 (1) Heated injection cylinder (2) Plunger (21) Spiral groove (3) Heated outer cylinder (4) Screw

Claims (1)

(57) [Claims] 1. A heated injection cylinder containing a plunger (2).
Heated outer cylinder containing the tip of (1) and screw (4)
The resin material melted in the heating outer cylinder (3) is filled with the tip of the heating injection cylinder (1) by communicating with the tip of (3), and the molten resin material is injected by advancing the plunger (2). In the screw-type pre-plastic injection machine, the plunger (2) is rotatably arranged and connected to the rotation driving device (6), and a spiral groove (21) is formed on the outer peripheral surface. And a screw-type prepra injection machine having a discharge hole (11) which penetrates the cylinder wall behind the maximum retreat position of the tip of the plunger (2).