JPS62103122A - High-kneading screw - Google Patents

Abstract

PURPOSE:To obtain such a high-kneading screw for molding plastics that possesses a sufficient kneading function even at high-cycle molding and no unmolten resin and generates neither a fish eye nor a foam, by providing weirs, over which a material is made to get, on a starting and terminal ends of an auxiliary flight having a larger lead angle than that of a main flight. CONSTITUTION:A screw 11 is provided with an auxiliary flight 13 whose height is a little lower than that of a main flight 12 and lead angle is larger than that of the main flight 12, and weirs 14, which are in parallel with an axial direction at a starting end and terminal end of the auxiliary flight 13, are connected with the main flight 12. The titled screw is not constituted that a material gets over the weir and fused when it gets over the weir without fail so that a problem that the material passes through as it is unfused as seen on an open style screw as before does not occur. The weir 14 is in parallel with a screw axis, with a length of 1/10-3/3D (D is a screw diameter) each at the starting end part and terminal end part, moreover, it is slightly lower than the weir 14 and it is connected with the main flight. The titled screw is so constituted that the material does not stay on the same and, moreover, the same posses intermediate properties between an open type and closed style so that fusion is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a screw for a plastic injection molding machine.

<Prior art and its drawbacks> In high-cycle molding, PP, PE, PA, etc. tend to cause fish eyes due to insufficient melting, color dispersion of masterbatches and dry colors, and poor kneading. Although physics eyes, color dispersion, insufficient kneading, etc. can be resolved by applying high back pressure, a new problem arises in which the plasticizing ability is reduced due to high back pressure, resulting in a decrease in productivity.

In order to prevent this decline in plasticizing ability, screws have been proposed that have a closed or open barrier in the screw groove, but in the case of an open barrier, unmelted material may not pass through the barrier. However, it is difficult to completely eliminate fish eyes and bubbles. In addition, in the case of a closed type barrier, it is difficult to process it, and the process must be done manually each time, which not only makes the work difficult but also requires an excessive number of man-hours. In addition, as shown in Figure 3, main flight 1 and barrier 2
In addition to the disadvantage that material resin, color change material, dust, etc. 3 tend to stay in the R part formed by the R part, the groove depth of the R part is the same as other groove parts, so heat is not transferred to the retained material. , it gets over the barrier without receiving enough heat, causing frictional heat and torque over.

<Object of the invention> The present invention eliminates the above-mentioned drawbacks, and provides a plastic molding method that has sufficient kneading function even in no-cycle molding, has no unmelted resin, and does not generate fish eyes or air bubbles. The purpose is to provide a high-kneading screw for use.

<Summary of the Invention> In order to achieve the above-mentioned object, the inventors have developed an injection molding screw consisting of a feed zone, a compression zone, and a metering zone from the material supply side to the tip, which are the same as the main flight of a full flight. It has a secondary flight with a larger lead angle than the main flight and a slightly lower height than the main flight, and has a screw diameter of D at the starting end and the terminal end of the secondary flight in at least 1 zone of the 3 zones. , the length is 1/~2
/ A high-kneading screw for plastic injection molding is connected to the main flight as a weir parallel to the axial direction of D.

In addition, the weir is continuously and smoothly connected to the bottom of the screw groove on the downstream and upstream sides in a straight line or curve, and the height of the weir is slightly lower than the sub-flight. It was made into a high kneading screw.

<Embodiment> Next, an embodiment of the present invention will be explained with reference to Figs. A weir 14 parallel to the axial direction is connected to the main flight 2 at its starting and ending ends to prevent unmelted material from passing through, as was the case with conventional oven systems. , so that the unmelted material that crosses the weir is melted when it completely crosses the weir 14.

The weir]4 is parallel to the screw axis, and has a length of 1/~2/D (D is the diameter of the spaghetti) at the start and end of the weir 14, respectively, and is slightly lower than the main flight 12. It is designed to have properties between an open type and a closed type so that the material does not stagnate and melts. Furthermore, the upstream side of the weir 14,
As shown in FIG. 2, the scree grooves and the downstream side are continuously and smoothly connected in a straight line or a curved line so that the depth of the scree groove becomes gradually shallower.

As explained above, since weirs are provided at the starting and ending ends of the sub-flights that have larger lead angles than the main flights, the sub-flights as a whole become longer by the weirs, and the melting of the material is reduced. It works more advantageously than the other way around, eliminating the drawbacks listed above, and melting is carried out well, eliminating the occurrence of fish eyes, bubbles, etc.

[Brief explanation of drawings]

l@1 Figure 1 and Figure 2 are diagrams showing one embodiment of the present invention,
FIG. 2 is a cross-sectional view taken along line II in FIG. FIG. 3 is a diagram showing a part of a conventional screw.

Claims (1)

[Scope of Claims] 1. An injection molding screw consisting of a feed zone, a compression zone, and a metering zone from the material supply side to the tip, including a full-flight main flight and a lead angle larger than that of the main flight in height. It has a secondary flight slightly lower than the main flight, and when the screw diameter is D at the starting end and the terminal end of the secondary flight in at least one of the three zones, the length thereof is ~2/3) A high-kneading screw for plastic injection molding that is connected to the main flight as a weir parallel to the axial direction of D, 2. The weir is connected to the bottom of the screw groove on the downstream and upstream sides. The screw according to claim 1, characterized in that the screws are continuously and smoothly connected in a straight line or a curved line. 3. The screw according to claims 1 and 2, wherein the height of the weir is slightly lower than that of the sub-flight.