JPH09131775A - Injection device of injection molder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the molten resin metered ahead a plunger from flowing backwards to the direction of a screw at injection in the injection device, which has the screw rotatably inserted in a heating cylinder and the plunger axially slidably fitted to a cylindrical part formed at the axis part of the screw, of an injection molder. SOLUTION: A collar or a one-way clutch provided between the tip of a screw 12 and a cylinder head 18 mounted at the tip of a heating cylinder 11 is slidably moved or engaged by means of both the pressure of the resin transferred by the screw during plasticizing and the pressure of the rein in a resin chamber 20 formed ahead a plunger 14 at injection so as to make-and-break control a clearance between the tip of the screw 12 and the cylinder head 18. Thus, the resin can be prevented from flowing backwards or from a resin chamber to the screw side at injection with a simple structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection having a screw rotatably inserted in a heating cylinder and a plunger fitted in a cylindrical portion formed on a shaft portion of the screw so as to be axially slidable. The present invention relates to an injection device of a molding machine, and more particularly, to an injection device of an injection molding machine having a backflow prevention device that prevents a molten resin measured in front of a plunger during injection from flowing backward in a screw direction.

[0002]

2. Description of the Related Art An in-line screw type injection cylinder is long, and a short and small injection molding machine, which eliminates the drawback of increasing size, rotates in a heating cylinder 1 as shown in FIGS. A plunger 3 fitted in a cylindrical portion formed on the shaft portion of a screw 2 freely inserted in the axial direction so as to be slidable in the axial direction, and a sleeve 4 slidably slidable outside the plunger 3 are provided in advance at the time of injection. The sleeve 4 is moved forward (to the left in the drawing) and brought into contact with the inner surface 5 on the front end side of the heating cylinder 1 as shown in FIG. 4, so that the molten resin 7 measured in front of the plunger 3 toward the screw 2 is screwed. A device is known in which, after preventing backflow in two directions, the plunger 3 is advanced and the molten resin 7 measured in front of the plunger 3 is injected from a nozzle 6 into a mold cavity (not shown). is there.

[0003]

However, in the conventional device, not only is a plunger movable in the axial direction movable inside the screw, but also a sleeve movable in the axial direction is provided on the outer periphery of the plunger. Above was very complicated. An object of the present invention is to provide an injection device of an injection molding machine having a backflow preventive device which does not use the complicated structure as described above and prevents the molten resin measured in front of the plunger from flowing backward in the screw direction during injection. To do.

[0004]

In order to achieve the above-mentioned object, the present invention axially slides a screw rotatably inserted in a heating cylinder and a cylindrical portion formed on the shaft portion of the screw. In an injection device of an injection molding machine having a freely fitted plunger, one end is slidably fitted to the nozzle-side tip of the screw and the other end is a groove provided in a cylinder head attached to the tip of the heating cylinder. And a chamber formed by the cylindrical portion formed on the shaft portion of the screw and the plunger tip and a groove formed in the cylinder head. The injection device was an injection molding machine.

In addition, in the injection device of the above injection molding machine, a one-way clutch piece is provided at the screw tip, and a spring or the like from the nozzle side is attached to the screw facing surface of the cylinder head that is separated from the screw tip attached to the heating cylinder tip by a predetermined distance. The injection device of the injection molding machine is characterized in that a one-way clutch other piece that meshes with the one-way clutch piece with respect to the reverse rotation of the screw to which the resisting force is applied by the biasing member is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, one embodiment of the present invention will be described with reference to FIG. Reference numeral 10 denotes an injection device, and a screw 12 is rotatably inserted into an inner diameter surface of a heating cylinder 11.
A cylindrical portion 13 is provided on the shaft portion of the screw 12, and a plunger 14 that is slidable in the axial direction is mounted on the shaft portion. A heater 15 is provided on the outer peripheral surface of the heating cylinder 11,
The resin material fed from the hopper 16 is heated and melted.

Further, a nozzle 19 is provided at the tip of the heating cylinder 11 via a cylinder head 18 mounted at a slight distance 17 from the tip of the screw 12, and the nozzle 19 is carried by the screw 12 and placed in front of the plunger 14. Room 2
The molten resin measured at 0 is injected into a mold cavity (not shown). One end of a ring-shaped collar 21 is slidably fitted to the tip of the screw 12, and the other end of the collar 21 is slidably fitted into a groove 22 formed on the side of the heating cylinder of the cylinder head 18. Have been combined.

A resin passage 23 communicating with the resin chamber 20 is provided in the groove 22, and when the plunger 14 moves forward (moves leftward in the drawing) during injection, the resin pressure in the resin chamber 20 causes The other end of the collar 21 is pushed, and the collar 2
1 moves to the screw 12 side and closes the gap 17 so that the resin in the resin chamber 20 does not leak to the screw 12 side.

The structure as described above is explained. Next, the operation will be described. The resin material charged from the hopper 16 is transferred forward by the rotation of the screw 12 while the screw is rotated and the heat insulation and the heater are performed. It is melted by heating by 15, and pushes the collar 21 to the left side in the drawing, and is accumulated in the resin chamber 20 in front of the plunger 14 via the space 17. Due to the accumulated molten resin, the plunger 14 retracts,
When retracted to a predetermined position, that is, when a predetermined amount of resin is measured, the rotation of the screw 12 is stopped and the plasticization is completed.

Next, the plunger 14 moves forward (to the left in the drawing) to inject the measured resin, and the resin chamber 20
As described above, the collar 21 is pushed toward the screw 12 side by the increase of the internal pressure and closes the open space 17, so that the resin in the resin chamber 20 does not flow back to the screw 12 side at the time of injection.

Next, another embodiment of the present invention will be described with reference to FIG. Reference numeral 30 denotes an injection device, and a screw 32 is rotatably inserted into the inner diameter surface of the heating cylinder 31. A cylindrical portion 33 is provided on the shaft portion of the screw 32, and a plunger 34 that is slidable in the axial direction is attached. A heater 35 is provided on the outer peripheral surface of the heating cylinder 31, and the resin material fed from the hopper 36 is melted by the shear heat insulation by the rotation of the screw 32 and the heating by the heater 35.

A nozzle 39 is provided at the tip of the heating cylinder 31 via a cylinder head 38 mounted at a slight interval 37 from the tip of the screw 32, and is carried by the screw 32, and a plunger is provided at an interval 37. 34
The molten resin measured in the resin chamber 40 in front of is injected into a mold cavity (not shown).

A one-way clutch piece 41 is fixedly attached to the tip of the screw 32, and a one-way clutch other piece 42 that meshes with the one-way clutch piece 41 is provided opposite to the heating cylinder side surface of the cylinder head 38. The one-way clutch other piece 42 is pushed from the nozzle side to the screw side by the spring 43, and when the screw 32 rotates in the reverse direction, the one-way clutch pieces 41 and 42 are
Are engaged with each other, the gap 37 is closed, and the resin chamber 40 in front of the plunger 34 and the nozzle 39 communicate with each other.

The operation of the hopper 3 will be described below.
The resin material charged from 6 is transferred to the front by the rotation of the screw 32, and the shearing heat insulation and the heater 35 are generated by the rotation.
However, since the screw 32 is rotating in the normal direction, the molten resin transferred in sequence overcomes the pressing force of the spring 43 provided on the other piece 42 of the one-way clutch, and the molten resin passes through the gap 37. Resin chamber 4 in front of the plunger 34
It is accumulated and measured at 0. At this time, the one-way clutch piece 41 and the other piece 42 do not mesh with each other because the screw 32 is rotating normally, the gap 37 is secured, and the molten resin can pass through the gap 37 too much. On the other hand, when the plunger 34 retracts to the predetermined position, the rotation of the screw 32 stops,
Plasticization is complete.

At the time of injection, first, when the screw 32 is reversely rotated at a low speed, the one-way clutch other piece 42 is projected forward (to the right in the drawing) due to the decrease of the resin pressure and the pressing force of the spring 43, and the one-way clutch piece 41. Since the other piece 42 and the other piece 42 mesh with each other and the gap 37 is closed, even if the plunger 34 moves forward to inject the resin that has accumulated and measured in the resin chamber 40, the resin in the resin chamber 40 remains in the screw 32.
There is no backflow to the side.

[0016]

As described above, in the present invention,
With a simple structure, resin backflow from the resin chamber to the screw side during injection can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is an explanatory view of a conventional device, showing a state in which a sleeve opens a resin path.

FIG. 4 is a view showing a state in which a sleeve of a conventional device closes a resin passage.

[Explanation of symbols]

 1 Heating Cylinder 2 Screw 3 Plunger 4 Sleeve 5 Heating Cylinder Tip Side Inner Surface 6 Nozzle 7 Molten Resin 10 Injection Device 11 Heating Cylinder 12 Screw 13 Cylindrical Part 14 Plunger 15 Heater 16 Hopper 17 Gap 18 Cylinder Head 19 Nozzle 20 Resin Chamber 21 Color 22 Groove 23 Resin passage 30 Injection device 31 Heating cylinder 32 Screw 33 Cylindrical part 34 Plunger 35 Heater 36 Hopper 37 Gap 38 Cylinder head 39 Nozzle 40 Resin chamber 41 One-way clutch piece 42 One-way clutch other piece 43 Spring

Claims (2)

[Claims] 1. An injection device for an injection molding machine having a screw rotatably inserted in a heating cylinder and a plunger fitted in a cylindrical portion formed on a shaft portion of the screw so as to be axially slidable. , One end is slidably fitted to the nozzle side tip of the screw and the other end is attached to the heating cylinder tip and slidably fitted into a groove provided in the cylinder head at a predetermined distance from the screw tip. Color and
An injection device for an injection molding machine, characterized in that a passage is provided which connects a chamber formed by a shaft portion of the screw, a chamber formed by a tip of a plunger, and a groove provided in the cylinder head. 2. An injection device of an injection molding machine having a screw rotatably inserted into a heating cylinder and a plunger fitted to a cylindrical portion formed on a shaft portion of the screw so as to be axially slidable. In addition, a one-way clutch piece is provided at the screw tip, and the reverse of the screw applied with a biasing member such as a spring from the nozzle side to the screw facing surface of the cylinder head that is separated from the screw tip attached to the heating cylinder tip by a predetermined distance. An injection device of an injection molding machine, comprising: a one-way clutch other piece that meshes with the one-way clutch piece with respect to rotation.