JPS60234820A - Extruder screw - Google Patents

Abstract

PURPOSE:To obtain excellent kneading effect by a method wherein a kneading section having both lateral curved edges in each crest of a screw and several concave sections or screw grooves with both lateral curved edges is provided in the middle of the rotary screw inserted into a heated cylinder. CONSTITUTION:The kneading section 9 connected in one body with the 2nd vent hole 7 at the position on the side of the hopper 2 on the rotary screw 5 is made zigzag so that the crest section 10 of the screw and the trough section 11 between the crest section 10, 10 are composed respectively of wide sections alpha and narrow ones beta alternately in the circumferential direction. Several concave sections 12, 12... are provided respectively on the trough sections 11, 11... in the circumferential direction at suitable intervals. Not only axial pulsation due to the curved crest sections 10 of the screw but radial compression and expansion in the concave sections 12 are repeated. Therefore, turbulent flows occur in the melted resin material and kneading effect is improved remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a screw for an extruder, which is provided with a crosstalk part in the middle of the rotating screw to enhance the crosstalk effect.

(Conventional technology) In order to specifically increase the crosstalk effect in a part of the conventional screw,
There was a system that was configured with a crosstalk section.

For example, as shown in Japanese Patent Application Laid-Open No. 52-856, the cylinder and screw of the cross-conducting part are made square and a plurality of protrusions are provided on the outer surface of the screw, or
There are some, such as No. 1-127157, in which a portion is provided in which the screw axis and the center of the cross section of the cylinder are relatively displaced or positioned.

However, with these conventional structures, the former requires only the cylinder and the kneading part of the screw to be processed into a rectangular shape, which takes time and effort to manufacture.In addition, since multiple protrusions are provided on the circumference of the cylinder, unexpected protrusions may occur. It has the disadvantage that it can break, and since the latter method simply displaces the screw axis and cylinder axis relative to each other, it has the disadvantage that a very high wiring crosstalk effect cannot be expected.

(Objective of the Invention) The object of the present invention is to provide a screw for an extruder that has a simple structure that has not existed in the past, is extremely easy to manufacture, and can be expected to have an excellent crosstalk effect.

(Structure of the Invention) The screw for an extruder according to the present invention is rotatably inserted into a cylindrical heating cylinder having a raw material input port at one end and an extrusion port at the other end, and In the middle of the screw, both edges of the crest of the screw are curved, and the trough is also provided with a cross section formed by providing a plurality of recesses or spiral grooves with curved both edges.

(Effects of the Invention) According to the present invention, the molten resin that has reached the cross-wire section in the middle of the screw not only receives pulsation in the axial direction of the screw by the spiral groove that curves in the cross-wire section, but also receives
The crosstalk effect is significantly improved due to the radial pulsation due to the multiple concave portions provided in the valley, or the double axial pulsation due to the spiral grooves curved on both sides of the valley. Even if the resin raw material is kneaded with additives, such as hard vinyl chloride, a sufficient crosstalk effect can be expected.

(Embodiment) An embodiment of the present invention having such characteristics will be described in detail below based on the drawings.

In FIG. 1, the extruder 111 has a heating cylinder 4 having a resin raw material input port 2 at the right end and an extrusion port 3 at the other end;
It is comprised of a rotating screw 5 inserted into the heating cylinder 4 for transferring the resin raw material from the input port 2 to the extrusion port 3.

The heating cylinder 4 has a first vent hole 6 and a second vent hole 7.
It has a band heater 8 on its outer periphery.

A cross-wire section 9 is integrally connected to the second vent hole 7 of the rotary screw 5 at a position on the input port 2 side.

As shown in FIGS. 2 and 3, the cross-contact portion 9 includes portions α where the intervals between the troughs 11 between the screw crests 10 and 10 that cover the ridges 10 of the screw adjacent to each other are alternately widened in the circumferential direction. It is constructed in a meandering manner so that a narrowed portion β is formed.

Each of the valleys 11, 11... has a plurality of recesses 1.
2, 12... are formed at appropriate intervals in the circumferential direction.

The recesses 12, 12, . . . may be formed in alternating sizes, or may be arranged in a staggered manner.

FIG. 3 shows a valley 12 instead of a recess 12, and both side edges 13 of the trough 12.
A spiral groove 1 curved in a direction in which a and 13a move toward and away from each other
3, and the depth is deep in the wide part and shallow in the narrow part.

FIG. 4 shows the cross-conducting portion 9 of another embodiment. In this case, the crest 10 of the screw is formed so that the wide part and the middle part are alternately formed in the circumferential direction. Both side edges 10a, 10a of the portion 10 are curved, and as a result, the width of the spiral groove 11 is alternately formed into widened portions α and narrowed portions β, and the valley portion 11 also has a recessed portion 12 or a narrowed portion β. Said third
A spiral groove 13 as shown in the figure is provided (the large and small recesses 12 are arranged in a staggered manner in the figure).

In the extruder configured as described above, when a resin raw material is input into the input port 2, this resin raw material is transferred to the extrusion port 3 side by the transfer action of the rotating screw 5 rotating in the direction of arrow Y. After being heated and melted by the heating cylinder 4 while being evacuated through the first vent hole 6, each trough is 11.1'1... are formed with alternately wide portions α and intermediate portions β, and in addition, a plurality of recesses 12 or spiral grooves 13 with curved both sides are formed in the valley portion 11. Therefore, not only the pulsation in the axial direction due to the curved crest 10 of the screw but also the pulsation in the recess 1
In the case of 2, the groove is repeatedly compressed and expanded in the radial direction, and in the case of the spiral groove 13, it is subjected to double pulsation in the axial direction.

For this reason, turbulence occurs in the flow of the molten resin raw material, and the crosstalk effect is significantly improved. A more sufficient kneading action than that of an extruder with a single shaft screw can be obtained.

[Brief explanation of the drawing]

The drawings show one embodiment of this invention, and FIG. 1 is a longitudinal sectional view of an extruder. FIG. 2 is a perspective view of the kneading section. FIGS. 3 and 4 are front views of crosstalk sections showing other embodiments of the present invention. 9...Kneading section 10...Screw crest 11...
Screw trough 12...Concave portion 13...Spiral groove Fig. 2 Fig. 4

Claims (1)

[Claims] 1. A screw is rotatably inserted into a cylindrical heating cylinder having a raw material input port at one end and an extrusion port at the other end, and a screw thread is provided in the middle of the rotating screw. A screw for extrusion, in which both side edges of the part are curved, and a cross section is formed by providing a plurality of recesses or a spiral groove with curved both side edges in the valley part.