JPH0742685Y2 - Injection molding machine screw check valve - Google Patents

Description

The present invention relates to an injection molding machine, and more particularly to a check valve for a screw of an injection molding machine.

(Prior Art) Conventionally, as shown in FIG. 4, a raw material in a hopper 2 is received in a cylinder 3 and melted, and the molten raw material is fed by a screw 4 rotatably provided in the cylinder 3. An injection molding machine in which a nozzle 5 is injected into a mold 6 to produce a molded product is known. In the figure, 7 is a screw driving unit, and 8 is a heater.

Although not shown in this figure, in such an injection molding machine, a check valve is provided between the tip of the screw and the main body, and the molten raw material is discharged from the nozzle 5 by the pressure in the mold 6. It is designed to prevent backflow into the cylinder 3.

(Problems to be solved by the invention) Generally, in a check valve having a large shaft diameter, the screw 13 is provided separately from the tip portion 14 as shown in FIG. The screw 14a is screwed into the screw hole 13a provided on the screw 13 side so as to be tightened, and the cylindrical check valve 12 and the check valve 12 are provided between the screw 13 and the tip portion 14 before the screwing. I was inserting a washer 15 to prevent it from wearing.

However, as shown in FIG. 6 (a), in the screw 16 having a small shaft diameter, the main body 16a and the tip portion 16b cannot be formed separately, so they are integrated, and in the concave portion between the main body 16a and the tip portion 16b,
As shown in the sectional view taken along the line AA in FIG.

With such a structure, the pin 17 is screwed during use.
There was a problem with durability as it could fall out of 16 or break.

In view of this, the present invention provides a non-return valve for an injection molding machine screw, which can be fitted to a screw whose tip is integrally formed without using a pin or the like. It was made with the purpose of solving the problem.

(Means for Solving the Problems) In order to achieve the above object, the present invention is designed to inject the molten raw material in the cylinder 3 into the mold 6 from the nozzle 5 at the tip.
The nozzle 5 side tip 4b of the screw 4 rotatably provided in the cylinder 3, a recess 4c axially adjacent to the tip 4b and having a diameter smaller than the outer diameter of the tip 4b, and the tip 4b opposite On the side, the front portion of the screw 4 consisting of the recess 4c and the screw main body 4a adjacent to the recess 4c, and the cylindrical valve body 1 axially moving in the recess 4c, the cylindrical valve body 1
In the check valve of the injection molding machine screw, which prevents the molten raw material from flowing back from the nozzle 5 by the screw body 4a and the screw body 4a, the front portion of the screw 4 has a tip 4b and a recess 4c integrated with the screw body 4a. As well as forming
The outer diameter of the screw body 4a is formed larger than the outer diameter of the tip portion 4b, and the cylindrical valve body 1 has an outer diameter that fits into the cylinder 3 and is eccentric with respect to the outer diameter. It is characterized by having a hole 9 larger than the outer diameter of the tip portion 4b.

(Operation) Since the valve body 1 is inserted and mounted in the concave portion 4c between the tip portion 4b of the screw 4 and the screw body 4a according to the above configuration, the end face of the thick portion between the shaft portion 10 and the hole 9 is the tip portion 4b. End face of 4f
To prevent the valve body 1 from coming off from the tip 4b side. Further, the molten raw material passes through the nozzle 5 and the screw 4
Even if an attempt is made to backflow to the side, the seat surface 11 of the valve body 1 contacts the end surface 4e of the screw body 4a and closes the gap, so that backflow of the molten raw material to the screw 4 side is prevented.

(Embodiment) Hereinafter, the present invention will be described with reference to an embodiment shown in FIGS.

It should be noted that parts common to the conventional example are denoted by the same reference numerals and description thereof is omitted, and only different parts will be described.

The valve body 1 of the screw of the injection molding machine according to the present invention is the fourth
The raw material in the hopper 2 shown in the figure is received in the cylinder 3, and by the screw 4 rotatably provided in the cylinder 3,
In an injection molding machine for injecting a molten raw material into a mold 6 from a nozzle 5 at the tip, the injection molding machine is provided between a main body 4a of the screw 4 and a conical tip 4b as shown in FIG. The valve body 1 for preventing the molten raw material flowing back from the nozzle 5 side is provided in the concave portion 4c, and the valve body 1 has a hole 9 of a size that allows the outer diameter 4d of the tip portion 4b to pass through and the inner diameter of the cylinder 3 described above. It has a shaft portion 10 that can fit into the screw 4 and can contact the screw 4, and the hole 9 and the shaft portion 10 are eccentrically formed.

FIG. 1 shows a state before the valve body 1 of the present invention is inserted into the concave portion 4c, and the hole 9 and the shaft portion 10 are machined with their centers eccentric by a length δ.

A bearing surface 11 is provided on one end surface of the shaft portion 10 so that the end surface having a constant width contacts the end surface of the screw 4.

2 and 3 show a state in which the valve body 1 of the present invention is inserted into the recess 4c, and the hole 9 is larger than the diameter 4d of the tip 4b, so that the hole 9 can be attached to the recess 4c without any problem in insertion.

In this case, as shown by the diagonal lines in FIG.
The side surface on the side contacts at the position of the maximum wall thickness portion (the lowermost portion in the figure) formed between the shaft portion 10 of the valve body 1 and the hole 9, and the contact area becomes the largest, The contact area decreases as it decreases (to the upper side in the figure), and the thick portion becomes minimum (the uppermost position in the figure) and becomes in the non-contact state in the vicinity thereof.

However, since the shaft portion 10 is fitted into the inner diameter of the cylinder 3, it is guided from the outside and will not tilt or come off even if the hole 9 is eccentric.

Further, even if the molten raw material tries to flow back to the screw 4 side through the nozzle 5 due to the pressure from the mold 6 side, the seat surface 11 of the valve body 1 comes into contact with the end surface 4e of the screw body 4a to close the gap. From entering into the screw 4 side.

In the present embodiment, the case where the hole 9 has a circular diameter has been described,
The holes are not necessarily circular, but may be elliptical or any other shape.

(Effect of the Invention) As described above, the present invention receives the raw material in the hopper into the cylinder, and injects the molten raw material into the mold from the nozzle at the tip by the screw rotatably provided in the cylinder. In the injection molding machine for molding by forming a valve body for preventing molten material flowing back from the nozzle in the recess between the tip of the screw and the main body, the valve body has a hole of a size that allows the tip to pass through. Since the shaft portion having a size that fits into the cylinder is formed so that the hole and the shaft portion are eccentric, the shaft portion can be attached to the recess by using the hole when the tip portion is passed through. It is possible to prevent contact with the side surface on the tip end side of the recess centering around the maximum thickness portion of the concave part to prevent the recess from coming off, and to prevent backflow of the molten raw material to the screw side by the seat surface of the valve body.

Therefore, the effect obtained with the simple structure is large.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state before assembly of an embodiment of a check valve of an injection molding machine screw according to the present invention, FIGS. 2 and 3 show an assembled state of FIG. 1, and FIG. Is a front view, FIG. 3 is a side sectional view thereof, FIG. 4 is a sectional view showing a general structure of a conventional injection molding machine, and FIG. 5 is a screw of the injection molding machine of FIG. 6 is a sectional view showing the structure of the valve body, FIG. 6 shows the mounting relationship of the valve body when the screw of FIG. 5 has a small diameter, (a) is a side sectional view, (b) is A of (a) FIG. 1 ... Valve body, 2 ... Hopper, 3 ... Cylinder, 4 ... Screw, 4a ... Main body, 4b ... Tip part, 4c ... Recessed part, 4d
…… Outer diameter, 5 …… Nozzle, 6 …… Mold, 9 …… Hole, 10…
… Shaft, 11 …… seat surface.

Claims (1)

[Scope of utility model registration request] 1. A nozzle 5 at the tip of the molten raw material in a cylinder 3.
From the nozzle 5 side tip of the screw 4 rotatably provided in the cylinder 3 in order to inject it into the mold 6 from the outer diameter of the tip 4b axially adjacent to the tip 4b. And a front portion of the screw 4 including a recess 4c and a screw body 4a adjacent to the recess 4c on the side opposite to the tip 4b, and a cylindrical valve body 1 axially moving in the recess 4c. In the check valve of the injection molding machine screw, which comprises the cylindrical valve body 1 and the screw body 4a to prevent the molten raw material from flowing backward from the nozzle 5, the front portion of the screw 4 is the tip portion 4b thereof. The recess 4c is formed integrally with the screw body 4a, the outer diameter of the screw body 4a is formed larger than the outer diameter of the tip portion 4b, and the cylindrical valve element 1 has an outer diameter that fits into the cylinder 3. Has an eccentricity with respect to its outer diameter, and A check valve for an injection molding machine screw, which has a hole 9 larger than the outer diameter of the tip portion 4b.