JP3110109B2 - Air removal device for twin screw extruder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air bleeding device in a feed section for supplying a powdery raw material of a twin screw extruder.

[0002]

2. Description of the Related Art As shown in FIG. 10, a conventional powder material supply apparatus supplies powder material A to a plastic molding machine main body 2 by natural fall from a hopper 1 or a hopper with a force feed hopper shown in FIG. The powder raw material A in 1 was fed into the plastic molding machine main body screw 9 by using the hopper motor 3 and rotating the screw 5 via the speed reducer 4.

[0003]

However, in the above-mentioned conventional apparatus, since the powder raw material A is carried in by entraining the air between the powder raw materials, the powder raw material A is supplied from the compression section (plasticizing section) of the plastic molding machine body to the raw material supply side. There has been a problem that the air intermittently flows backward, so that the supply of the raw material becomes unstable, and the supply amount is reduced so that a large amount of the raw material cannot be supplied. As a conventional means for solving the above-mentioned problems, a method of keeping the inside of the hopper 1 in a vacuum state so as to prevent air from being brought into the molding machine body has also been implemented. However, this method requires expensive equipment. There were disadvantages. The present invention applies a pressure to the flowing raw material by adding some resistance to the flowing raw material in the middle of the raw material feeding screw near the raw material supply port where the compression of the plastic raw material has not yet been sufficiently performed. It is an object of the present invention to provide an air venting device for a twin-screw extruder which can release the air from a passage provided in a cylinder barrel to a supply port to increase and stabilize a supply amount of a powder raw material.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides, in a co-rotating twin-screw extruder, a supply port for a powder raw material having a width and a length corresponding to the width dimension of two engaged extruding screws; The kneading screw is opened in the wall of the supply port and has a tapered groove space with a length of 2 to 3 screw pitches created in the screw feeding direction, and a further 2 to 3 screw pitches from the end point of the groove space. An extruding screw integrally mounted , wherein the kneading screw is a powder material.
Is stirred and transferred to the full-scale pressurized and heated plasticizing stage.
In both cases, the resistance becomes the flow resistance of the powder raw material , which is used as a means for solving the problem.

[0005]

According to the present invention, in order to reliably feed a powdery raw material containing a large amount of air, the raw material supply port is first set to the width of a barrel full of two screws, and the front and rear lengths of the same size are set. Of the extruder for conventional pellet raw materials
A kneading screw is provided at a position 4 to 6 screw pitches in the extrusion direction from the raw material supply port of the raw material delivery screw with an opening area twice or more, and an opening is formed on the wall of the raw material supply port with the cylinder barrel. By providing a tapered groove space with a length of 2 to 3 screw pitches in the barrel feed direction, the powder raw material containing a large amount of air has an increased apparent volume. Expansion can prevent shortage of supply. Also, before the raw material reaches the compression part of the screw, the flow of the powder raw material is given resistance by the kneading screw at a position near the raw material supply port, and a gentle compression force is applied to the raw material before the kneading screw, The air contained in the powder material is pushed out,
Attempts to escape toward the supply port. If the air escape groove is provided in the cylinder barrel, the air pushed out from the powder raw material can easily escape to the raw material supply port.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an embodiment of the present invention; FIG. First, FIG. 1 to FIG. 3 show a first embodiment of the present invention, FIG. 1 is a plan sectional view of a main part near an extruder raw material inlet, FIG. 2 is a BB sectional view of FIG.
FIG. 3 is a cross-sectional view taken along the line CC of FIG. In the figure, reference numeral 11 denotes a cylinder barrel of a twin screw 12 which is fed in the direction of the screw 12 (4 to 6 in the extrusion direction from the raw material supply port 11a).
The kneading screw 13 is integrally attached to the screw pitch position). Further, a groove space 11c opening in the vertical wall 11b in the traveling direction of the raw material supply port 11a of the cylinder barrel 11 (having the same width as the cylinder barrel and having the same length) has a groove space 11c facing the screw feeding direction. And is tapered. The sectional shape of the groove space 11c is a shape surrounded by an arc having the same radius as the inner diameter of the cylinder barrel 11, as shown in FIG. The extrusion direction of the raw material is indicated by a large white arrow Y, the rotation direction of the screw 12 is indicated by X, and the raw material is indicated by A.

Next, the operation of the first embodiment shown in FIGS. 1 to 3 will be described. The powder raw material A is supplied to a raw material supply port 11a which is largely opened as shown by an arrow, and is sent to the left by a screw 12 in the drawing. . A kneading screw 13 is integrally attached to the left side of the screw 12. In the kneading screw 13, the powder raw material A is stirred and sent to the left, and the kneading screw 13 is fed to the right. Since the feeding capacity is smaller than that of the screw 12, the kneading screw 13 becomes a resistance to the flow of the raw material. Therefore, pressure is generated in the raw material in the feed screw 12 immediately to the right of the kneading screw 13, and the air contained in the powder raw material is pushed out of the raw material and tries to return to the inlet side, and the air is supplied through the groove space 11c to supply the raw material. Get out of the mouth 11a.
As described above, most of the air contained in the powder raw material A can be removed from the raw material before moving to full-scale pressurization and heating plasticization.

Next, a second embodiment shown in FIGS. 4 to 6 will be described. FIG. 4 is a plan sectional view of a main part near a raw material inlet, FIG. 5 is a sectional view taken along line DD in FIG. 4, and FIG. It is E to E sectional drawing of. The second embodiment differs from the first embodiment only in the groove shape formed in the cylinder barrel. That is, the groove spaces 14c, 14c are provided in the vertical walls 14b directly above the screws 12, 12, respectively, 14 is a cylinder barrel, and 14a is a raw material supply port. In the embodiment of FIGS. 4 to 6, the air vent groove space 14c has a slit shape, and the sectional shape of the air vent groove space 14c is as shown in FIG. 6, but the operation is the first embodiment. It is exactly the same as in the example. Processing the slit-shaped groove space 14c in the cylinder barrel 14 requires less man-hour than the arc-shaped groove space of the first embodiment. Next, FIGS. 7 to 9 show a third embodiment in which the groove space 15c is a tapered slit shape provided on the upper vertical wall between the screws 12, 12, but the operation is the first and second. This is exactly the same as the embodiment.

[0009]

As described above in detail, according to the present invention, most of the air contained in the powdery raw material containing a large amount of air can be removed at the delivery screw portion close to the raw material supply port. Problems such as fluctuations in the supply of raw materials due to intermittent backflow of air from the plasticizing section (heating and compression section) and a decrease in the supply amount are eliminated, and stable extrusion can be performed.

[Brief description of the drawings]

FIG. 1 is a plan sectional view of a main part of a twin-screw extruder according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG. 1;

FIG. 3 is a sectional view taken along the line CC of FIG. 2;

FIG. 4 is a plan sectional view of a main part of a twin-screw extruder according to a second embodiment of the present invention.

FIG. 5 is a sectional view taken along line D-D of FIG. 4;

FIG. 6 is a sectional view taken along line E-E of FIG. 5;

FIG. 7 is a plan sectional view of a main part of a twin-screw extruder according to a third embodiment of the present invention.

8 is a sectional view taken along line FF of FIG. 7;

FIG. 9 is a sectional view taken along line GG of FIG. 8;

FIG. 10 is a front sectional view of a raw material supply section in a conventional twin-screw extruder.

11 is a partial cross-sectional side view of FIG.

[Explanation of symbols]

 Reference Signs List 11 cylinder barrel 11a material supply port 11b supply port wall 11c groove space 12 screw 13 kneading screw 14 cylinder barrel 14a material supply port 14b supply port wall 14c groove space A material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI B29C 47/66 B29C 47/66 (58) Investigated field (Int.Cl. ⁷ , DB name) B29C 47/00-47/96 B29B 7/00-7/94

Claims (1)

(57) [Claims] In a co-rotating twin-screw extruder, a supply port for a powder raw material having a width and a length of two engaged extruded screws, an opening in a wall of the supply port, and a screw. two consisting of a groove chamber tapered length 2-3 screw pitch made in the unwinding direction, the extrusion screw mounted integrally kneading screw further ahead 2-3 screw pitch from the end of the groove chamber This is the air bleeding device of the screw extruder.
The kneading screw stirs the powder material
Transfer to the plasticizing stage of pressure and heating
An air bleeding device for a twin-screw extruder, characterized by a flow resistance of a raw material .