JPH024408B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a kneading screw for single-screw extrusion, suitable for kneading thermoplastic plastics, composite materials of thermoplastic plastics and fillers, ceramics, and foods. This invention relates to a kneading screw for single-screw extrusion.

[Conventional technology]

Generally, in the kneading screw for extrusion, a shearing action acts on the melt as the kneading screw rotates, whereby the melt is homogenized by the kneading action and is extruded.

Conventionally, in order to improve the kneading action of the kneading screw, a so-called barrier type screw, in which a narrow gap is provided in a part of the flow path, has been frequently used.

This barrier-type screw forces the melt to pass through a narrow gap to exert a strong shearing action on the melt, thereby improving the kneading effect.

In addition, as another conventional means for improving the kneading action, a so-called mixing screw, in which protrusions are installed in the screw groove of the kneading screw, is also frequently used.

This mixing type screw uniformizes the melt by forcibly separating and merging the melt using protrusions.

[Problem that the invention seeks to solve]

Conventionally used barrier type screws and mixing type screws are constructed and operate as described above, but each has the following problems.

First, in the barrier type screw, the barrier part acts as a flow path resistance, which causes problems such as generation of high pressure, rise in temperature of the melt, and decrease in extrusion rate, which reduces the kneading effect. There was a limit to the improvement.

In addition, in the mixing type screw, the melt is divided in the flow direction, but there are problems in that the number of divisions is small and the positions cannot be expected to be exchanged at all between the front and rear flow paths. Therefore, the kneading effect cannot be improved beyond a certain level. Incidentally, in order to improve the kneading effect, it is necessary to repeatedly exchange the position of the melt.

This invention was made in order to solve the above-mentioned problems, and it is possible to improve the kneading effect by changing the position without causing excessive pressure generation, temperature rise, or reduction in extrusion rate. The object of the present invention is to obtain a kneading screw for extrusion that can extrude a good extrudate with high efficiency.

[Means for solving problems]

The kneading screw for single-screw extrusion according to the present invention is a single-screw in which a supply section, a melting section, and a metering section are arranged from the base side, and a forward multi-layered screw formed discontinuously in the forward direction of forwardly transporting the kneaded material. The row flights and the reverse multi-flight flights formed discontinuously in the opposite direction for transporting the kneaded material rearward are arranged facing each other on both sides of the plane including the axis of the screw, and the bidirectional multi-flight flights are At least one kneading section is provided in the portion constituting the melting section and the measuring section, the ends of which are arranged so as to correspond to the grooves between the multiple flights.

[Effect]

Since the kneading screw for single-screw extrusion according to the present invention is configured as described above, by the rotation of the screw, for example, the kneaded material that has been kneaded and extruded between the forward multi-flights and reached the end can be At this point, it is divided into two parts by the reverse multi-flight flight, enters the grooves on both sides of the reverse multi-flight flight, and is fed back and kneaded. In this case, the kneaded material that was in the adjacent grooves of the forward multi-flight flight is divided into two parts and one of them enters each groove, so the positions are exchanged, and the kneaded material is divided into two parts. This is done every half turn for each row, resulting in extremely large positional changes.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings showing one embodiment thereof.

In FIG. 1, the extrusion kneading screw 1 is
A feeding section A, a melting section B, and a measuring section C are configured from the root side, and the kneading section D is arranged in the measuring section C. The details of the kneading section D are shown in FIG.
8, 9, and reverse multi-filament flights 10, 11, 12, 1 formed in the opposite direction to transport the melt backwards.
3, 14, and 15. Each of the forward and reverse multi-flight flights 4 to 15 is discontinuous, and the forward multi-flight flights 4 to 9 and the reverse multi-flight flights 10 to 15 are arranged in a plane E- containing the axis of the kneading screw 1. The starting points and end points of the forward multi-flight flights 4 to 9 correspond to the screw grooves formed between each of the adjacent reverse multi-flight flights 10 to 15. It is arranged so that Similarly, the starting and ending points of the backward multi-flight flights 10 to 15 are arranged to correspond to the screw grooves formed between adjacent forward multi-flight flights 4 to 9, respectively. Note that the leads of the forward multi-strip flights 4 to 9 and the leads of the reverse multi-strip flights 10 to 15 are formed uniformly. In addition, the code|symbol 2 shows a flight, and 3 shows a screw groove.

This embodiment is constructed as described above, and its operation will be explained next.

The solid raw material supplied to the cylinder is transferred while being preheated by the supply section A and reaches the melting section B, where it is melted, then sent to the measuring section C and then entering the kneading section D.

Here, the melt transferred to the starting end of the kneading section D is
In the forward direction screw grooves 16, 17, 18, 19, 20 formed between the forward direction multi-thread flights 4 to 9, the kneading screws are transported forward by the traction flow caused by the traction force accompanying the rotation of the kneading screw 1. Kneaded. Similarly, in the reverse direction screw grooves 21, 22, 23, 24, 25 formed between the subsequent reverse direction multi-flight flights 10 to 15, the traction flow caused by the rotation of the kneading screw 1 causes a backward movement. While being transported, it is also kneaded. Note that the length of this kneading section D is set depending on the required degree of kneading.

Next, the flow of molten resin between the forward multi-strip flights 4 to 9 and the reverse multi-strip flights 10 to 15 will be explained using some flights as examples.

For example, the melt in the forward screw groove 16 is sent forward by the rotation of the kneading screw 1;
It is divided into two parts by the reverse multi-thread flight 11 and transferred into the reverse direction screw grooves 21 and 22.
Similarly, the melt in the forward screw groove 17 is also divided into two by the reverse multi-flight flight 12 and transferred into the backward screw grooves 22 and 23. Therefore, the melt in the reverse screw groove 22 is a mixture of the melt transferred from the forward screw groove 16 and the melt transferred from the forward screw groove 17. Note that the uniformity of the melt is achieved by circulating flow due to traction force. Similarly, the melt in the reverse screw groove 23 is a mixture of melts transferred from the reverse screw grooves 17 and 18.

On the other hand, the molten material in the reverse direction screw groove 22 is divided into two by the forward direction multi-flight flight 5 and transferred to the forward direction screw grooves 16 and 17, and similarly, the molten material in the reverse direction screw groove 23 is It is divided into the forward direction screw grooves 17 and 18 and transferred.

Thus, for example, the forward screw groove 17
The melt inside is a mixture of the melt transferred from the reverse screw grooves 22 and 23, that is, the melt transferred from the forward screw grooves 16, 17, and 18, respectively.

Although the above description has been made with respect to one row of forward screw grooves, a similar operation is performed for all of the forward screw grooves and reverse screw grooves.

In this way, in the kneading section D, the melt is mixed in one screw groove with the melt in the front and rear screw grooves.
It is transferred forward while being repeatedly kneaded several times.

The molten material sufficiently kneaded in this manner is finally homogenized and extruded through the screw groove 3 formed by the flight 2 formed at the tip of the measuring section.

In addition, in the above embodiment, one kneading section D was provided, but the invention is not limited to this.
They may be provided at several locations on the kneading screw, in which case they have the effect of further strengthening the kneading action.

〔Effect of the invention〕

According to the kneading screw of the present invention, the forward multi-flight flight and the reverse multi-flight flight are arranged opposite to each other with respect to a plane including the screw axis, and the end of one flight is connected to the other flight by the other flight. Since the arrangement corresponds to the screw groove to be formed, the melt in the screw groove is repeatedly kneaded while exchanging positions with the melt in the previous and succeeding screw grooves, thereby preventing excessive pressure generation, temperature rise, and extrusion. The kneading effect is improved without causing a decrease in the amount,
As a result, it is possible to obtain a kneading screw for single-screw extrusion that can extrude a good extrudate with high efficiency.

[Brief explanation of drawings]

FIG. 1 is an external view of a kneading screw according to an embodiment of the present invention, and FIG. 2 is a partially enlarged detailed view of FIG. 1. 1...kneading screw, 2...flight, 3...
...Screw groove, 4-9...Forward multi-strip flight, 10-15...Reverse multi-strip flight, 16-
20... Forward screw groove, 21-25... Reverse screw groove, A... Supply section, B... Melting section, C... Measuring section, D... Kneading section.

Claims (1)

[Claims] 1. In a single-screw extrusion kneading screw in which a supply section, a melting section, and a measuring section are arranged from the root side, there are forward multi-flight flights formed discontinuously in the forward direction that transport the kneaded material forward, and kneading. A discontinuously formed reverse direction multi-flight flight in the opposite direction to which the material is transferred rearward is disposed opposite to both sides of a plane including the axis of the kneading screw, and both ends of the bidirectional multi-flight flight are A kneading screw for single-screw extrusion, characterized in that at least one kneading section is provided in a portion of the melting section and the measuring section, the kneading section being arranged so as to correspond to the screw groove between the other multi-flight flights.