JPS61141513A - Screw for molding plastic - Google Patents

Abstract

PURPOSE:To improve the uniformly plasticatable performance, uniformly kneaded performance, plasticating capability or the like of resin by a method wherein either one of starting or ending end of a sub flight is not contacted with a main flight and the height of the sub flight at a part parallel to the main flight is formed lower than the height of the main flight. CONSTITUTION:The sub flight 3 is constituted of a plurality of parts 3A, parallel to the main flight 2, and parts 3B, connecting the terminal end and the starting end of neighboring parts 3A and parallel to the axis of a screw shaft, while a screw groove 4, formed by the main flight 2, is divided into an inflow side groove 5 and an outflow side groove 6. The height of the sub flight 3 is formed so as to be lower than the same of the main flight 2 by the value of delta. The value of delta is constant and a taper, reducing gradually from the upstream side to the downstream side, is formed whereby the uniformly plasticatable, uniformly kneading and uniformly dispersing performances may be improved and the plasticating capability may be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a plastic molding screw used in an injection molding machine, an extruder, etc.

[Technical background of the invention and its problems]

The effective screw length of a screw for a plastic injection molding machine is shortened due to the planned backward movement of the screw. Therefore, in general, resin measured at the nozzle side tends to have a relatively high temperature, and resin measured at the rear tends to have a low temperature.

When the resin temperature decreases in this way, insufficient kneading generally tends to occur. These problems occur because the melt boule and solid bed coexist and are discharged from the feed zone of the screw, where the solid phase is transferred while being preheated, to the compression zone, where the molten phase is formed, and the metering zone. In order to solve this problem, the solid bed is separated from the melt pool,
As a means of heating and melting at an early stage, screws with various sub-flights (Utility Model Publication No. 53-96070, Utility Model Publication No. 53-96070)
5-18180 and Japanese Patent Application Laid-Open No. 159159/1983) have been proposed.

The above-mentioned conventional sub-flight screws all have a structure in which the sub-flight is formed with a different lead angle from the main flight. Therefore, it is difficult to automate manufacturing, requiring manual processing, and automatic processing using a flight grinder is difficult. It was extremely difficult.

[Object of the Invention] In view of the above-mentioned points, the present invention aims to facilitate manufacturing of the screw by making the lead angle of the sub-flight the same as that of the main flight, and to make the lead angle of the screw groove divided by the sub-flight into the screw head. On the other hand, an inflow side groove that carries the solid part of the material in contact with the back side of the main flight and an outflow side groove that carries the molten part of the material in contact with the front side of the main flight are provided, and the solid material and the molten material are conveyed separately, resulting in uniform plasticization of the resin. The object of this invention is to provide a screw for plastic molding that can improve uniform kneading performance, plasticizing ability, etc.

(Summary of the Invention) To achieve the above object, the present invention provides a screw having a main flight constituting a full-flight screw and a sub-fly l- formed in parallel to the main flight, wherein the sub-flight is , consisting of a plurality of sections parallel to the main flight, and a section parallel to the screw axis connecting the terminal and starting ends of this section, and the overall structure is stepped, and the starting and terminal ends of the sub-flights are parallel to each other. At least one of the sub-flights is not in contact with the main flight, and the height of the sub-flight is such that a portion parallel to the main flight is lower than that of the main flight.

(Example of the invention) The present invention will be described below with reference to embodiments shown in the drawings.

The plastic molding screw 1 according to the present invention has a main flight 2 constituting a full-flight screw, and a sub-flight 3 that is not formed parallel to the main flight 2. It consists of a part 3A parallel to the flight 2, and a part 3B parallel to the screw shaft connecting the adjacent terminal ends and starting ends of the above main flight 2, and a developed view is shown in Fig. 2. The screw groove 4 formed by the main flight 2 is divided into an inlet groove 5 and an outlet groove 6, as shown in FIG. In the portion 3B parallel to the screw axis, as shown in an enlarged cross section in FIG. The part 3B is formed into a rounded-up or rounded-down shape with a straight line a that is in contact with the bottom outside diameter circle of the screw groove or a large curvature R (R is the radius of the grinding wheel) that is circumscribed with the bottom outside diameter circle of the screw groove, making it easy to process the part 3B. In addition to sex,
At the same time, efforts are being made to prevent resin from accumulating and to improve color change and resin change performance.

The height of the sub-flight 3 is set lower than the main flight 2 by δ, as shown in FIG.

Note that this δ is not only constant as shown in the fifth figure, but also constant as shown in the sixth figure.
By creating a tapered shape that gradually decreases from the upstream side to the downstream side as shown in the figure, it is possible to improve uniform plasticization, uniform kneading, uniform dispersion performance, and plasticization ability.

According to this embodiment, the melt boule flows smoothly from the screw groove 4 and the inflow side groove 5 to the outflow side groove 6, and the solid bed and the melt boule can be smoothly separated as they melt, resulting in more uniform plasticization, uniform kneading, and uniform The dispersion performance can be improved, and at the same time, the plasticizing ability can be further improved.

In the embodiment shown in FIG. 7, the inflow side of the sub-flight 3 is closed and the outflow side is open, and the portion 3B parallel to the screw axis is in front of the main flight 2, that is, the outflow side groove 6 is upstream. This is a closed example, and the bottom shape, flight height, etc. can be changed as in the above-mentioned embodiment.

The embodiment shown in FIG. 8 is a case where both the inflow side and the outflow side of the sub-flight 3 are open.

In the above embodiment, the melt boule flows smoothly from the inflow side to the outflow side, the sub flight 3 smoothly separates the solid bed and the melt boule as they melt, and since the outflow side of the melt boule is open, it is easy to flow out. This improves the plasticizing ability and improves uniform plasticization, uniform kneading, and uniform dispersion performance.

In any of the above embodiments, the sub-flight 3 is provided in one or more of the metering zone, compression zone, and feed zone of the screw 1.

〔Effect of the invention〕

As explained above, the present invention provides a plastic molding screw having a main flight constituting a full flight and a sub-flight along the main flight, in which the sub-flight is formed parallel to the main flight. ,
The screw can be manufactured using an automatic flight grinder, and can be manufactured efficiently and inexpensively. In addition, the sub-flight has a part parallel to the screw axis, and the height of the part of the sub-flight parallel to the screw axis is lower than the main flight, so resin kneading performance and resin temperature are uniform, and the pigment It has excellent dispersibility and does not impair color changeability or resin changeability even if it has secondary flights. Furthermore, since at least one of the starting end or the ending end of the sub-flight does not come into contact with the main flight, the flow of the melt boule is smoothed, which significantly improves the uniform plasticization, uniform kneading, and uniform dispersion performance of the resin, and the plasticization ability. Can be made with a high screw.

[Brief explanation of drawings]

FIG. 1 is a front view of a part of an embodiment of a plastic deck molding screw according to the present invention, FIG. 2 is an exploded view of the same, FIG. 3 is a view equivalent to FIG. 3 showing a modification, FIG. 5 is a sectional view taken along the line ■-m of FIG. 2, FIG. 6 is a view equivalent to FIG. FIG. 8 is a front view of a part showing an example, and FIG. 8 is a front view of a part showing still another embodiment. 1...Screw, 2...Main flight, 3...Sub-flight, 3A...Part parallel to the main flight, 3B...
・Part parallel to the screw axis. Applicant's agent Kiyoshi Inomata 5 IPJ1 Figure 2 Figure 3 Figure 4 Social Figure 5 Punishment Figure 6 Figure 7 [21 Figure 8

Claims (1)

[Claims] 1. A screw having a main flight constituting a full-flight screw and a sub-flight formed parallel to the main flight, wherein a plurality of the sub-flights are provided and the sub-flight is parallel to the main flight. and a part that connects the end and start of this part and is parallel to the screw axis, and has a step-like structure as a whole, and at least one of the start and end of this sub-flight is the main flight. A screw for plastic molding that is non-contact and characterized in that the height of the sub-flight is formed so that the part parallel to the main flight is lower than the main flight. 2. The groove depth of the inflow side portion of the screw groove divided by the sub-flights gradually decreases toward the downstream side from the problem point of the sub-flights or any arbitrary position downstream from this point. A screw for plastic molding according to item 1. 3. The groove depth of the inflow side portion of the screw groove divided by the sub-flights is the same as the height of the sub-flight at a portion parallel to the screw axis. Screw for plastic molding as described. 4. A patent claim characterized in that in the entire width of the gap between the secondary flight and the main flight or in a part thereof in a region parallel to the main flight, the groove depth is constant from the starting end to the terminal end of the secondary flight. The plastic molding screw according to any one of items 1 to 3. 5. The shape of the bottom surface of the groove adjacent to the portion parallel to the screw axis is a straight line that passes through one end of the top surface of the sub-flight on at least one of its upstream and downstream sides and is in contact with the outer diameter circle of the bottom surface of the screw groove. A screw for plastic molding according to any one of claims 1 to 4, characterized in that: 6. The shape of the groove bottom surface adjacent to the portion parallel to the screw axis is an arc that passes through one end of the top surface of the sub-flight on at least one of its upstream and downstream sides and circumscribes the outer diameter circle of the bottom surface of the screw groove. The screw for plastic molding according to any one of claims 1 to 4, characterized in that: 7. The screw for plastic molding according to any one of claims 1 to 6, wherein the height of the sub-flight gradually increases toward the downstream side. 8. Claims 1 to 7, characterized in that at least one of the metering zone, compression zone, and feed zone of the screw is provided with an auxiliary flight whose length is at least one lead. The plastic molding screw according to any one of the above.