JPS61141512A - 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 the height of a dam, parallel to a main flight and blockading an outflow side groove, carrying the molten portion of material, and an inflow side groove, carrying the solid portion of the material, is formed lower than the height of the main flight, among the screw grooves divided by a sub flight. CONSTITUTION:The depth of inflow side groove 4 of screw groove, divided by the sub flight 3, is decreased gradually toward downstream side from the starting point of the sub flight 3 or an arbitary position at the downstream of the starting point while the height of the sub flight 3 is increased gradually toward the downstream side thereof. A space, formed between the inner surface of a barrel 6 and the sub flight 3, is formed so that the gap delta1 at the starting point is larger than the gap delta2 at the ending point thereof, therefore, the unmolten portion of the solid portion of the material resin becomes hard to flow into the outflow side groove 5 and whereby the dispersion of the resin may be effected well.

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 metering backward movement of the screw. Therefore, in general, the temperature of the resin measured at the nozzle side tends to be relatively high among the resins measured, and the temperature of the resin measured at the rear tends to be low.

When the resin temperature decreases in this way, insufficient kneading generally tends to occur. These problems are caused by the fact that a melt pool and a 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, Japanese Unexamined Patent Publication No. 48-59159) has 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.

[Purpose of the invention]

In view of the above points, the present invention manufactures the auxiliary flight with the same zero lead angle as the main flight.
The object of the present invention is to provide a screw for plastic molding that can improve uniform plasticization performance, uniform crosstalk performance, plasticization ability, etc. of resin while facilitating the above.

[Summary of the invention]

In order to achieve the above object, the present invention provides a screw having a main flight constituting a full-fried screw and a sub-flight formed parallel to this flight, wherein the sub-flight is a portion parallel to the main flight. and a weir that is connected to the start and end points of the main flight and closes the outflow side groove that carries the melt part of the material and the inflow side groove that carries the solid part of the material among the screw grooves divided by the sub-flight, Moreover, the height thereof is characterized in that the portion parallel to the main flight is formed lower than the main flight.

[Embodiments 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 formed parallel to the main flight 2.
The secondary flight 3 is connected to a portion 3A parallel to the main flight 2, and the starting point and ending point of this main flight 2, respectively,
Among the screw grooves formed by the main flight 2 and the sub-flight 3, the back surface a of the main flight 2 with respect to the screw head side
It is composed of a weir 3B that closes an inflow side groove 4 that carries the solid part of the material that is in contact with the main flight 2, and an outflow side groove 5 that carries the melt part that is in contact with the front surface of the main flight 2 on the screw head side.

As shown in the enlarged view of cross section I-I in FIG. 2 or FIG. The radius of the grinding wheel) is rounded up and rounded down, which not only facilitates processing of the part 3B, but also prevents resin from accumulating and improves color change and resin change performance. There is.

Note that the groove depth of the inflow side groove 4 of the screw groove divided by the sub-flight 3 is gradually reduced toward the downstream side from the starting point of the sub-flight 3 or any position downstream from this,
Depending on the type of resin material, the height may match that of the weir 3B at the weir 3B portion, as shown in the cross-sectional view (■--■) in FIG.

Further, the height of the secondary flight 3 is gradually increased toward the downstream side as shown in FIG. The gap δ at the starting point is set so that δ > δ2 with respect to the gap δ at the end point, and as the solid portion of the material resin goes downstream, the material that does not melt flows into the outflow groove 5 and is well dispersed. I'm trying to get it done.

Further, the sub-flight 3 may be provided in one or more of the metering zone, compression zone, and feed zone of the screw 1 by approximately one lead.

(Effects of the Invention) As explained above, the present invention provides full flight screen 1
In a plastic molding screw having a main flight constituting a main flight and a sub-flight along this main flight,
Since the sub-flights are formed parallel to the main flight, the screw can be manufactured using an automatic flight grinder, and the screw can be manufactured efficiently and at low cost. In addition, the sub-flight has a part that runs almost perpendicularly to the main flight, and the height of the part of the sub-flight that is parallel to the main flight is lower than that of the main flight, which improves resin crosstalk performance and ensures uniform resin temperature. It has a variety of effects, such as excellent pigment dispersibility, and does not impair color changeability or resin changeability even if it has secondary flights.

[Brief explanation of drawings]

Fig. 1 is a partial front view showing one of the basic embodiments of the screw for plastic molding according to the present invention, Fig. 2 is an enlarged sectional view taken along line I-I in Fig. 1, and Fig. 3 is an embodiment of the present invention. Fig. 4 is a developed view of Fig. 1, Fig. 5 is an enlarged cross-sectional view along the line ■-■ of Fig. 4, and Fig. FIG. 6 shows still another embodiment, and is an illustrative diagram in which the height of the sub-flight increases from the starting point to the ending point. 1...Screw, 2...Main flight, 3 river sub-flights, 3A...Parallel portion, 3B...Weir, 4...Inlet side groove, 5...Outlet side groove. Applicant's agent Kiyoshi Inomata ff Subfigure 20 Figure 3

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, the sub-flight having a portion parallel to the main flight, The screw groove is connected to the starting point and the terminal end of the main flight, and is composed of an outflow side groove that carries the melt part of the material and a weir that blocks the inflow side groove that carries the solid part of the material among the screw grooves divided by the sub-flight. A plastic molding screw characterized in that the height of the part parallel to the main flight is lower than the main flight. 2. The screw for plastic molding according to claim 1, wherein the inflow side groove depth gradually decreases toward the downstream side from the starting point of the sub-flight or any position downstream from this. 3. The screw for plastic molding according to claim 2, characterized in that the depth of the inlet groove matches the height of the weir portion of the sub-flight. 4. The shape of the bottom surface of the groove adjacent to the weir of the secondary flight is
Claim 1 or 2, wherein the straight line passes through one end of the top surface of the sub-flight on at least one of its upstream side and downstream side and is in contact with the outer diameter circle of the bottom surface of the screw groove. Screw for plastic molding. 5. The shape of the bottom surface of the groove adjacent to the weir 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. A screw for plastic molding according to claim 1 or 2. 6. The screw for plastic molding according to any one of claims 1 to 5, wherein the height of the sub-flight gradually increases toward the downstream side. 7. Claims 1 to 6, characterized in that a sub-flight having a length of at least one lead is provided in at least one of the metering zone, compression zone, and feed zone of the screw. The plastic molding screw according to any one of the above.