JPH0418890B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high kneading molding machine that is effective when applied to injection molding machines, extrusion molding machines, and the like.

In general, in an injection molding machine, the screw moves backwards during plasticization and advances during injection, so the effective length of the screw changes and the mechanical energy and heat transfer energy applied to the resin change, causing Temperature differences were unavoidable.

The present invention aims to solve the above-mentioned conventional problems, and includes a plurality of mixing parts each having a polygonal cross section at the tip of the screw, and the polyhedron of the mixing part and the inner wall surface of the cylinder have the same number of broken circles as the polyhedron. It is an object of the present invention to provide a high-kneading molding machine that can obtain a high-kneading effect by forming a space and providing a barrier (weir) with a part cut out in the same circular space.

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 show embodiments of the present invention, and FIG. 1 shows a mixing section b and a backflow prevention This is an injection molding screw having part c. The mixing part b is composed of a combination of a plurality of polyhedrons 2, 2', 2'', and downstream of the polyhedrons 2, 2', 2'' there are partially cut-out barriers (weirs) 3, 3', 3". The cutout grooves 4, 4' of the barriers 3, 3' are open to the next polygon 2', 2".

The backflow prevention part c includes a seat 5, a check ring 6,
It is composed of a retainer sheet 7 and a ring 8.
And these mixing part b and backflow prevention part c
is screwed into the screw 1 and the screw tip 12 via the threaded parts 10 and 11 of the coupling ring 9,
It has an integrated structure. Further, the relative positions of the polyhedrons 2, 2', 2'' are determined by a key 13 fitted in the coupling ring 9. Also, 14 is a distance.

The cylinder inner wall surface 15 and the notched slopes 16 of the polyhedrons 2, 2', 2'' constitute the same number of truncated circular spaces 17 as the polyhedrons 2, 2', 2''. The omitted circular space 17 has a structure in which a portion of it is dammed downstream by barriers 3, 3', 3''.

Next, to explain the operation, the molten state in the phase transition period (transition period from solid phase to liquid phase) during the resin melting process in the screw cylinder is explained by the molten body model shown in Figure 5. . In the figure, d is a solid bed, e is a melt film, and f is a melt pool. As the melting progresses due to the shearing action of the melt film e, the solid bed d breaks up, and in the metering part a of the screw 1, the sixth As shown in the figure, a lump h of unmelted pellets shown in the melt g is suspended.

In this state, the shearing force due to the screw rotation acts on the melt g and raises its temperature, but the effect on the unmelted pellets h is small, and the progress of melting is mostly due to heat transfer energy, so the melting efficiency is low. bad. The mixing action of the present invention is based on melt film e.
A shearing force equivalent to that applied to the unmolten pellets h is applied to the unmolten pellets h, and by providing a plurality of mixers and a barrier, a stronger kneading effect can be obtained. Gansho 55-
This is a step up from No. 147625.

Now, the flow of the molten material in the mixing section is in the direction of the arrow in FIG. 4, and the unmolten pellets h also move along the flow. On the other hand, the cylinder inner wall surface 15 has a wedge structure that tapers in the direction of flow of the molten material, and the unmolten pellets h are caught in the corner portions 18 of the polyhedrons 2, 2', 2''.
18', 18''.

In addition, the aggregated unmelted pellets h are strongly pushed to the cylinder inner wall surface 15 by the wedge action of the notch slope 16.
be forced to. At this time, a melt film i similar to the melt film e of the melting model shown in Fig. 5 is formed, and the mechanical energy due to the rotation of the screw becomes strong shear energy, and the unmelted pellet h
As a result, melting progresses rapidly.

At this time, as shown in FIG. 3, the barrier 3 captures the unmelted pellets h to promote melting. The unmelted pellets h' overflowing from the notched groove 4 of the first stage mixing block are captured by the barrier 3' and the corner portion 18' of the second stage mixing block 2' and are subjected to a strong shearing action. In addition, the unmelted pellets h'' that overflowed the notch groove 4' in the second stage are captured by the corner portion 18'' of the polyhedron 2'' in the third stage and the barrier 3'', and are subjected to strong shearing energy and suddenly melt.

Further, the resin melted by the mixing head having the polyhedron 2 passes through the gap 19 of the backflow prevention mechanism c,
A certain amount is pooled in a space (not shown) at the tip of the screw chip 12. A certain amount of pooled molten resin is injected into a mold (not shown) in the next cycle, but at this time, the tip of the torpedo is under extremely high pressure, so the molten resin tries to flow backwards, but the tip pressure causes the check ring 6 is pushed back and comes into close contact with the sheet surface of the sheet 5 to prevent backflow of molten resin due to injection pressure.

As explained in detail above, the present invention provides a plurality of mixing parts each having a polygonal cross section at the tip of the screw, and the polyhedron of the mixing part and the inner wall surface of the cylinder constitute the same number of truncated circular spaces as the polyhedron. During mixing, unmelted resin is captured by being rolled into the corners of the polyhedron, and by providing a partially cut-out barrier downstream of the mixing, unmelted resin in the flow direction is captured in multiple stages, making it highly effective. The material is rapidly melted by applying a large amount of shearing force, and the closer it gets to the corner, the smaller the gap becomes, so the shearing force becomes stronger, and the kneading action and cleaning action increase dramatically, promoting melting.

[Brief explanation of drawings]

FIG. 1 is a partially sectional side view showing the tip of a screw in an injection molding machine according to an embodiment of the present invention, and FIG.
The figure is a cross-sectional view from A to A in Figure 1, Figure 3 is an expanded enlarged view of the mixing section in Figure 1, Figure 4 is a detailed view showing the melting process at part B in Figure 2, Figures 5 and 3 are FIG. 6 is an explanatory diagram showing the melting process of resin within the screw cylinder. Explanation of the main parts of the diagram 1...Skuriyu, 2,
2', 2''... Polyhedron, 3, 3', 3''... Barrier, 4... Notch groove, a... Metering part, b
...Mixing part, 15...Cylinder inner wall surface, 1
7...Closed circle space.

Claims (1)

[Claims] 1. A plurality of mixing parts each having a polygonal cross section are provided at the tip of the screw, and the polyhedron of the mixing part and the inner wall surface of the cylinder constitute the same number of omitted circular spaces as the polyhedron,
A high-kneading molding machine characterized by having a barrier partially cut out on the downstream side of the circular space.