JPH05245906A - Plastic extruder - Google Patents

Abstract

PURPOSE:To reduce abrasion loss of a mesh by decreasing a passing quantity of a material per unit area of the mesh by a method wherein a diameters of a material passing parts of a screen mesh and a breaker plate which are arranged in front of a screw are made larger than an inner diameter of a cylinder of an extruder. CONSTITUTION:For a plastic extruder, a screw 2 which extrudes a plastic material to a metal mold 5 or the like exists inside an extruder cylinder 1, and a screen mesh 3 for screening a foreign substance in extrusion materials and a breaker plate 4 for holding the mesh 3 are arranged at a material outlet in front of the screw 2. In such an extruder, an inner diameter (d) of the extruder cylinder 1 is enlarged at an extruding outlet, and the screen mesh 3 and the breaker plate 2 of which a material passing part diameter D is made larger than the inner diameter (d) are arranged at that position. Thereby, a material passing quantity per unit area of the mesh 3 is decreased and reduction of abrasion loss of the mesh is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic extruder for extruding a plastic composition such as polyethylene or vinyl chloride.

When a plastic composition is extruded using a plastic extruder, a screen mesh (wire mesh) and a breaker plate for mechanically holding the screen mesh are arranged in front of the screw in order to screen for foreign substances in the extruded material. Has been done. FIG. 2 is a vertical cross-sectional view of a main part of a conventional plastic extruder. As shown in the drawing, inside the extruder cylinder 1, there is a screw 2 for extruding a plastic material into a mold 5 connected to the extruder, and the material outlet on the front face of the screw 2 is the screw for extruding the extruded material. The screen mesh 3'for screening foreign matter and the breaker plate 4'which mechanically holds the mesh 3'are arranged. In the conventional plastic extruder, the diameter of the material passage portion of the screen mesh 3 and the breaker plate 4 is the same as the extruder cylinder 1
Was less than or equal to the inner diameter of

[0003]

In the above-mentioned conventional plastic extruder, when the plastic material to be extruded contains carbon, a filler, etc., the cumulative extrusion time and the material passing amount increase, and the mesh size of the mesh increases. There is a problem that the wire wears. Therefore, there is a problem in that a mesh having a small wire diameter for removing finer foreign matter cannot be used and a mesh with a small opening cannot be used, or the extruder is stopped at a constant amount and the mesh is replaced.

[0004]

The present invention solves the above problems and provides a plastic extruder in which the abrasion of the screen mesh is reduced, which is characterized by a screen mesh and a breaker arranged in front of the screw. The diameter of the material passage portion of the plate is made larger than the inner diameter of the extruder cylinder.

[0005]

[Function] The plastic material extruded from the extruder passes through the screen mesh and enters the mold, but foreign matter in the material is captured by the screen mesh, and the material with the foreign matter removed is injected into the mold. It However, when carbon or filler is blended in this extruded material, these blending agents abrade the strands of the screen mesh, and extruding for a long time increases the amount of material passing through. If you go, you will get a wire break.

Since the amount of abrasion of this wire depends on the amount of material passing per unit area, the material passing portion diameter of the screen mesh and breaker plate is made larger than the inner diameter of the extruder cylinder to make the unit area of the screen mesh portion. The amount of mesh wear can be reduced by reducing the amount of material passing per hit. In particular, when the diameter of the material passage portion of the breaker plate is increased by 20% or more, the above effect can be remarkably obtained.

By the way, when the plastic material mixed with the filler is extruded by an extruder in which the material passage portion diameter of the breaker plate is increased by 75% with respect to the cylinder inner diameter, the screen mesh equivalent wear time (material passage amount) is I was able to make it about 5 times.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a longitudinal sectional view of the essential parts of a concrete example of a plastic extruder according to the present invention. In the drawings, the same symbols as those in FIG. 2 represent the same parts. As shown in the drawing, an inner diameter d of an extruder cylinder 1 in which a screw 2 for extruding a plastic material is arranged is expanded at an extrusion outlet, and a screen mesh 3 and a breaker for holding the screen mesh 3 are provided at the position. The plate 4 is arranged. The material passage portion diameter D of the screen mesh 3 and the breaker plate 4 is formed larger than the inner diameter d of the extruder cylinder 1. This makes the screen mesh 3
The amount of material passing per unit area can be reduced, and the amount of mesh wear can be reduced.

[0009]

As described above, according to the plastic extruder of the present invention, the diameter of the material passing portion of the screen mesh and the breaker plate is made larger than the inner diameter of the extruder cylinder, so that the unit area of the screen mesh is reduced. It is possible to reduce the amount of material passing and the amount of mesh wear. As a result, it is possible to use a mesh having a small wire diameter and a small opening, and fine foreign matter can be removed. Further, since the amount of wear of the mesh is reduced, the frequency of mesh replacement is reduced and the productivity is improved. Therefore, when it is used as an extruder for a plastic material containing carbon or a filler, its effect is great.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a specific example of a plastic extruder of the present invention.

FIG. 2 is a vertical sectional view of a main part of a conventional plastic extruder.

[Explanation of symbols]

 1 Extruder Cylinder 2 Screw 3 Screen Mesh 4 Breaker Plate 5 Mold

Claims (1)

[Claims] 1. A plastic extruder, characterized in that the diameter of the material passing portion of the screen mesh and the breaker plate arranged in front of the screw is made larger than the inner diameter of the extruder cylinder.