JPH065143Y2 - In-line screw type injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an in-line screw type injection molding machine, and more specifically, a belt-shaped material is supplied from a material supply section provided at the rear of an injection cylinder to perform molding. The present invention relates to an in-line screw type injection molding machine.

(Prior Art) Normally, an in-line screw type injection molding machine has
As is well known in JP-A-31719 and JP-A-62-50484, it has the structure shown in FIG.

That is, the injection cylinder 2 provided with the hopper 1 at the rear part
In addition, a measuring part 6 for measuring the molten resin, a supplying part 3 having a root diameter smaller than that of the measuring part 6, and the measuring part 6 and the supplying part 3.
A screw S composed of a compression unit 4 that connects and is inserted. The compression portion 4 is formed in a tapered shape whose diameter is expanded in the moving direction of the molding material.

When the screw S is inserted into the injection cylinder 2, sliding contact flight parts 5 ', 5' ... that rotate and move forward and backward while sliding a part of the outer surface of the screw S onto the inner wall surface of the injection cylinder 2 are screw S. Are spirally provided in the feeding direction of the molding material over the entire length thereof.

In an injection molding machine in which such a screw S is inserted in the injection cylinder 2, the molding material supplied from the hopper 1 is moved by the spiral sliding contact flight part 5 ′ provided in the supply part 3 of the screw S. While being heated, it is preheated by a heater (not shown) provided in the injection cylinder 2 and sent to the compression unit 4. In the compression section 4, the molding material is melted by the shearing action and the heater, and a resin pressure is generated and sent to the measuring section 6. In the measuring unit 6, the fed molten resin is completely kneaded to make it uniform.

By the way, as a molding material used for injection molding, various forms are used, and a band-shaped material is also used.

However, when a strip-shaped material is used, in the above-described conventional in-line screw type injection molding machine, the strip-shaped material supplied from the material supply unit slides on the screw S when the screw S advances in the injection process. The strip-shaped material cut at the flight portion 5'and wound around the screw S is separated from the strip-shaped material in the material supply portion.

Therefore, injection molding cannot be performed until the strip-shaped material is wound around the screw S again, and continuous injection molding is difficult.

One of the inventors of the present invention has proposed an in-line screw type injection molding machine shown in FIG. 2 in Japanese Patent Application No. 59-256679 so that continuous injection molding can be performed even if a band-shaped material is used.

This injection molding machine is formed in a spiral shape on a rear part 3a of a supply part, which is provided on the rear side of a supply part 3 of a screw S inserted in an injection cylinder 2, and to which a band-shaped material W is supplied from a material supply part 4. The flight portion 5 having the outer diameter Df, which has a fixed outer diameter Df, has a spiral outer diameter Ds of at least the stroke length Zr of the screw S. The diameter is smaller than that of the sliding contact flight portion 5 '. Therefore, when the screw S advances, there is formed a gap G in which the strip material W can intervene between the outer surface of the flight part 5 and the inner wall surface of the injection cylinder 2.

(Problems to be Solved by the Invention) According to the in-line screw type injection molding machine shown in FIG. 2, when the screw advances, the strip-shaped material is not cut into the gap G and is continuously cut without being cut. Can be supplied and continuous injection molding can be performed.

However, the screw S of the injection molding machine shown in FIG.
As shown in FIG. 3, is a screw in which a stepped portion is formed in the flight portion that constitutes the supply portion, and it was found that a crack is generated in the stepped portion during use.

Therefore, an object of the present invention is to provide an in-line screw type injection molding machine that can perform injection molding using a band-shaped material and can eliminate the concern that a screw may crack.

(Means for Solving the Problem) The present inventors have made it possible to prevent cracks occurring in the stepped portion of the screw supply portion by making the stepped portion as smooth as possible, and to advance the screw forward. At this time, it was thought that continuous molding is possible if a part of the band-shaped material is connected without being cut, and as a result of repeated studies, the present invention was reached.

That is, according to the present invention, a screw is provided in which a supply portion for feeding the molding material to the compression portion is continuously provided on the rear side of the tapered compression portion whose root diameter increases in the feeding direction of the molding material. In an in-line screw injection molding machine that inserts into a cylinder rotatably and reciprocally, and supplies a band-shaped material from a material supply unit provided at the rear of the injection cylinder to a screw supply unit to supply the screw. The part includes a front part of a supply part in which a sliding contact flight part is formed in a spiral shape in which the inner wall surface of the injection cylinder and a part of the outer surface are in sliding contact with each other to rotate / advance, and a rear part of the supply part to which the strip-shaped material is supplied. In the rear portion of the supply portion, a flight portion that is smaller in diameter than the outer diameter of the sliding contact flight portion and that is formed in a tapered shape that reduces in diameter in the rear end direction of the screw from the boundary with the sliding contact flight is provided,
An in-line screw injection molding machine is characterized in that, when the screw advances, a gap is formed between the outer surface of the flight part having the smallest outer diameter and the inner wall surface of the injection cylinder, in which a band-shaped material can intervene.

(Operation) When the fracture surface of the crack generated in the stepped portion formed in the screw supply portion shown in FIG. 3 is observed with a microscope, the crack fracture surface shows a fine striped pattern, a so-called shell-like fracture surface. Met.

From such knowledge, it is presumed that the crack generated in the stepped portion of the screw supply portion is caused by the repeated stress concentration of the stepped portion of the screw during injection molding or the like.

In this regard, the screw used in the in-line screw type injection molding machine of the present invention is such that the flight part at the rear of the supply part constituting the screw supply part is formed to have a small diameter so that the belt-shaped material can intervene, and the injection cylinder. The stepped portion is eliminated by forming a taper between the sliding contact flight portion of the front portion of the supply portion that rotates and moves forward / backward in sliding contact with the inner wall surface.

Further, since a gap in which the strip-shaped material can intervene is formed between the outer surface of the flight section at the rear of the supply section and the inner wall surface of the injection cylinder, when the screw advances, a part of the strip-shaped material is connected without being cut. And continuous molding is possible.

Therefore, the injection molding machine of the present invention can perform continuous molding using a band-shaped material, and can eliminate the concern that a screw will crack.

(Example) The present invention will be further described with reference to the drawings.

FIG. 1 is an embodiment of a screw used in the injection molding machine of the present invention, and is a partial side view of a supply part 3 provided at the rear part of the screw S shown in FIG. 3 shows the vicinity of the supply unit 3a provided on the rear side of the unit 3.

The supply portion rear portion 3a (hereinafter, sometimes referred to as screw rear portion 3a) has a length substantially equal to the stroke length Zr of the screw S, and the material is supplied to the screw rear portion 3a as shown in FIG. The strip-shaped material W is supplied from the part 4.

The spiral flight part 5 formed on the screw rear part 3a is spirally formed on the front part of the supply part which is continuously provided on the front side of the screw rear part 3a and is slidably contacted with the inner wall surface of the injection cylinder. The diameter is smaller than the outer diameter Ds of the flight part 5'which moves and retreats (see Fig. 2).

In the present embodiment, the flight portion 5 of the screw rear portion 3a
The outer diameter of is formed in a taper shape in which the diameter is reduced from the boundary of the screw rear portion 3a to the sliding contact flight portion 5'to the rear side.

Therefore, the outer diameter of the frontmost flight portion 5 of the screw rear portion 3a becomes equal to the outer diameter Ds of the sliding contact flight portion 5 '.

On the other hand, on the rear end side of the screw rear portion 3a, the minimum diameter Df
Is formed, and a gap G is formed between the outer surface of the flight portion 5 having the minimum diameter Df and the inner wall surface of the injection cylinder 2 so that the strip material W can be interposed. The size of the gap G depends on the outer diameter of the screw S, the thickness of the strip material W, the material (elasticity, etc.), but is usually 1 to 2 mm.
It is a degree.

In the screw S used in this embodiment, the length of the taper portion Tp of the screw rear portion 3a may be shorter than the stroke length Zr of the screw S, as shown in FIG. 1 (a).
As shown in Fig. 2 (b), the stroke length Zr of the screw S
May be equal to.

Also in the screw S of this embodiment including the supply section 3 having the screw rear portion 3a shown in FIG. 1 as described above, as in FIG. 4 showing the conventional injection molding machine, the screw S has a tip end portion. The measuring section 6 having a larger diameter than the provided supply section 3 and the supply section 3 are connected by a tapered compression section 4.

The screw S is inserted into the injection cylinder shown in FIG. 2, that is, the injection cylinder provided with the material supply unit 4 in which the supply hole 25 is formed, and injection molding is performed.

The state shown in FIG. 2 is a state in which the injection process is completed, and the molten molding material that has been measured and accumulated in a predetermined amount in front of the measuring portion 6 of the screw S is advanced by the stroke length Zr of the screw S. Inject into the mold cavity.

When the screw S moves forward, the strip-shaped material W wound around the screw rear portion 3a together with the screw S is drawn into the injection cylinder 2.

However, in this embodiment, since the strip material W is interposed in the gap G formed on the rear end side of the screw rear portion 3a, the strip material W wound around the screw rear portion 3a and the strip material in the supply hole 25 are provided. It is connected with W without being cut.

After such an injection process, the screw S is rotated and retracted to perform a measuring process in which a predetermined amount of the molten molding material is accumulated in front of the screw S.

At this time, since the strip-shaped material W supplied from the supply hole 25 and the strip-shaped material W wound around the screw rear portion 3a are connected without being cut, the strip-shaped material W is wound into the groove portion of the screw rear portion 3a as the screw S rotates. Go.

The rolled-in strip material W is melted in the injection cylinder 2 and accumulated in front of the screw 3.

Then, after a predetermined amount of the molten molding material is accumulated in front of the screw 3, the injection process is started.

In this way, the screw 3 repeats rotation and reciprocation during injection molding, but if there is a stepped portion as shown in FIG. 3, the stress at the time of rotation and reciprocation of the screw 3 concentrates on the stepped portion, so cracking occurs. Is likely to occur.

In this respect, the screw 3 employed in the present embodiment has a tapered portion between the sliding contact flight portion 5'and the flight portion having the minimum diameter Df, thereby eliminating the stepped portion.

Therefore, it is possible to eliminate the risk of cracks in the screw 3 caused by repeated stress concentration during injection molding.

(Effect of the Invention) According to the present invention, it is possible to perform continuous molding using a band-shaped material in an in-line screw type injection molding machine, and eliminate the concern that a screw may crack during injection molding. Therefore, the reliability of the injection molding machine can be improved.

[Brief description of drawings]

1 is a partial side view showing an embodiment of the present invention, FIG. 2 is a partial sectional view of an injection molding machine showing a conventional example, and FIG. 3 is a screw used in the injection molding machine shown in FIG. Partial cross section,
4 and FIG. 4 are partial cross-sectional views of a general injection molding machine. In the figure, S ... Screw, Zr ... Stroke length of screw S, G ... Gap, Tp ... Tapered portion, 3 ... Supply portion of screw S, 3a ... Supply portion that constitutes supply portion 3 of screw S Rear part (screw rear part), 5 ... flight part of supply part rear part 3a, 5 '... sliding contact flight part, Ds ... sliding contact flight part 5'diameter, Df ... minimum diameter flight part diameter.

Claims (1)

[Scope of utility model registration request] 1. An injection cylinder comprising a screw having a taper-shaped compression section whose root diameter increases in the feeding direction of the molding material, and a supply section for feeding the molding material to the compression section, which is continuously provided on the rear side of the compression section. In an in-line screw type injection molding machine, which is inserted into a screw so as to be rotatable and forward / backward, and which supplies a band-shaped material from a material supply unit provided at a rear portion of the injection cylinder to a screw supply unit to perform molding. The injection cylinder inner wall surface and a part of the outer surface is a sliding contact flight part that rotates and advances and retreats in sliding contact, and comprises a supply part front part formed in a spiral shape, and a supply part rear part to which the band-shaped material is supplied, At the rear part of the supply part, there is provided a flight part which is smaller in diameter than the outer diameter of the sliding contact flight part and which is formed in a tapered shape so as to reduce in diameter toward the rear end direction of the screw from the boundary with the sliding contact flight, and the screw advances. Do In this case, an inline screw type injection molding machine is characterized in that a gap in which a band-shaped material can be interposed is formed between the outer surface of the flight part having the smallest outer diameter and the inner wall surface of the injection cylinder.