JPS5829734B2 - bent extruder - Google Patents

Description

[Detailed description of the invention] Conventionally, in extrusion molding or injection molding of plastic materials such as plastics and rubber, the quality of the product is improved by removing air, moisture, volatile substances, etc. contained in the raw material plastic material. For this reason, a vent extruder in which a degassing chamber is provided at one or several locations in the cylinder of an extruder or injection molding machine has been put into practical use as shown in FIG.

In FIG. 1, 1 is a cylinder, and 2 is a degassing chamber, and the degassing chamber 2 is generally maintained at a low pressure by a separately provided vacuum device.

Here, the raw material supplied from the raw material supply port 3 is fed to the screw 4
While being transported through part A (supply melting part), the cylinder is heated by a heating device (not shown) from outside the cylinder, and is melted and plasticized by internal heat generation due to its own friction and shear deformation, and reaches part B (degassing part). .

In part B, gasified components contained in the raw materials are removed,
In order to prevent the gasified components from overflowing from the degassing chamber 2, the screw groove of part B is formed so as not to be filled with plastic material.

In other words, the transport capacity in part C (metering part) where the screw groove is filled with plastic material again exceeds the melting and transport capacity in part A, and furthermore, in part B, the plastic material is It is constructed so that its transport capacity is equal to the capacity of section A even when it is not full.

However, in the extruder or injection molding machine shown in Fig. 1, the plastic material is extruded from an extrusion mold (not shown), so a considerably high pressure is required for the plastic material 5 at the tip of the screw. In order to provide the zero part with a high transport capacity, the length of the zero part is generally increased.

However, when the capacity of section A becomes extremely high, it is no longer possible to obtain a transport capacity greater than section A simply by lengthening section C, and it becomes impossible to prevent the molten material from overflowing from the degassing chamber 2. .

That is, the conventionally proposed vent extruder using the kneading mechanism of a high-performance extruder had the above-mentioned drawbacks because the capacity of the A part was dramatically increased.

The present invention was proposed in order to solve the above-mentioned conventional drawbacks, and the cylinder inner diameter and screw outer diameter of the degassing section and its downstream side in the flow direction are made smaller than those of the front part of the degassing section including the polygonal part. It is an object of the present invention to provide a vent extruder that can increase the transport capacity of the front part of the degassing section by increasing the size of the vent extruder, and can also maximize the high capacity of this part, thereby improving the performance of the extruder. It is.

Embodiments of the present invention will be explained below with reference to the drawings. In the first embodiment shown in FIG. 2, a third As shown in FIG. 4, there is a portion 7 in which at least one of the cylinder screws has a cross-sectional shape perpendicular to the axis of a polygon or a shape similar to the polygon.

FIG. 5 shows a state in which the screw 6 has been slightly rotated from the state shown in FIG. 4.

The cylinder 8 corresponding to the 87th part (deaeration part) and the C/ part (metering part) of the screw 6 has an inner diameter larger than that of the cylinder 9 corresponding to the A' part of the screw.
The outer diameter of the screw crest 10 at the 87th section and C/ section is slightly smaller than the inner diameter of the cylinder 8, and the outer diameter of the screw at the 87th section and C7 section is also larger than the screw outer diameter at the A' section. .

In addition, a choke part 11 is provided at the boundary between parts A' and B' of the screw 6, which makes the plastic material flowing into the degassing chamber 12 thin, and by moving the screw 6 back and forth, It is also possible to adjust the capacity of the A' section by changing the degree of choke.

In the figure, 13 is a raw material supply port, and 14 is a screw groove in the degassing section.

Next, to explain the operation, the raw material supplied from the raw material supply port 13 is transported through the A' section of the screw 6, and between the cylinders 9 is heated by a heating device (not shown) from outside, and is subjected to self-friction and shear deformation. The raw material is melted and plasticized by internal heat generation to reach 87 parts, and the gasified components contained in the raw material are removed in the same part B/part.

In FIG. 4, which shows the cross section taken along line DD in FIG. join.

Since this deformation is applied by the number of polygonal angles per revolution, the plastic material passing through the polygonal cross section 7, which is the kneading part of the screw 6, is subjected to the renewal force of the resin surface, and rapidly becomes molten plastic. be converted into

Therefore, extremely high extrusion performance can be imparted to the A' section of the screw having this kneading section, that is, the section A' in front of the degassing chamber 12 (raw material supply side) including the polygonal cross section 7.

In addition, the cylinder inner diameter and screw outer diameter of the degassing section and the downstream side in the flow direction behind it, that is, sections B' and C7, are larger than those of the A/ section in front of the degassing section, so the transport capacity is Even if the length is about the same as the conventional one, it is sufficiently large.

As a result, the transport capacity of 87 parts and C7 parts can exceed that of A/part, which has dramatically improved extrusion performance.
The degassing section B/ can be operated in a state where the screw groove 14 is not filled with plastic materials.

Next, FIG. 6 shows another embodiment, in which the screw located in the cylinder 8 of the B1 section (deaeration section) in FIG. ) is a screw with a polygonal cross section,
The shape of this polygon may be any other shape than the quadrangle or hexagon shown in FIG. 3 or 4, or may be a combination of cylinders and screws with different numbers of angles.

Furthermore, the present invention is not limited to single screw extruders, but can be similarly applied to multi-screw extruders with three or more wheels.

As explained in detail above, the present invention provides a vent extruder in which one part of the cylinder and the screw has a polygonal or similar cross-sectional shape perpendicular to the axis. The inner diameter of the cylinder and the outer diameter of the screw on the side are made larger than those of the front part of the degassing part, which includes the part where the cross-sectional shape perpendicular to the axis is polygonal.
The transport capacity of the resin in the degassing section and the downstream side in the flow direction behind it is sufficiently large even if the length of the screw is about the same as that of conventional screws. The resin transport capacity of the raw material supply side section in front of the degassing section has been dramatically increased due to the provision of the degassing section, so the degassing section can be operated without plastics filling the screw groove.

Therefore, the plastic material does not overflow from the degassing chamber, and degassing can be carried out effectively.

The present invention can be applied to plastic extruders, rubber extruders, injection molding machines, etc.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing the screw part of a conventional extrusion molding machine or injection molding machine, Fig. 2 is a side sectional view of a vent extruder showing an embodiment of the present invention, and Fig. 3 is D of Fig. 2. -D sectional view, Figure 4 is a DD sectional view of Figure 2 with a different cross-sectional shape from Figure 3, Figure 5 is a sectional view showing a state in which the screw has rotated a little more than in Figure 4, and Figure 6 This figure is a side sectional view showing an embodiment different from that in FIG. 2. Explanation of the main parts of the diagram, 6... Screw, I...
. . . A portion whose cross-sectional shape perpendicular to the axis is a polygon or a similar shape, 8 . . . A vent section and a cylinder behind it, 9 . . . A cylinder in front of a vent section, 12... Degassing chamber.

Claims (1)

[Claims] 1. In a vent extruder which has a part in front of the degassing part of the cylinder and screw that has a polygonal or similar cross-sectional shape perpendicular to the axis, A vent extruder characterized in that the inner diameter of the cylinder and the outer diameter of the screw are larger than those of the raw material supply side portion in front of the degassing section including the polygonal portion.