JPH04339632A - Multi-spindle extruding machine - Google Patents

Abstract

PURPOSE:To prevent an extrusion molding material in a screw head part from dwelling. CONSTITUTION:In a biaxial extruding machine where a conduit 4 is joined to an outlet of an extrusion molding material of a barrel 1 through a meeting adapter 7 having a guide hole 7a where the more it goes to the outlet, the more its diameter is contracted, a rectification adapter 5 into which a large number of through holes 5b are formed is provided between a screw head 2a and the meeting adapter 7 and a screw head 2a side inflow surface 5c of the rectification adapter 5 is formed into a recessed facial state along an end surface of the screw head 2a at fixed gaps.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-screw extruder for extrusion molding resins and the like.

0002

2. Description of the Related Art Conventionally, for example, in a twin-screw extruder, as shown in FIG. A merging adapter 23 in which a guide hole 23a is formed is attached. A conduit 24 for sending extrusion molding material, such as resin, from an extruder to a mold is connected to this merging adapter 23, and a back pressure of the molten resin propelled by the screw 22 is provided between the merging adapter 23 and the conduit 24. A breaker 25 or ring in which a large number of through holes 25a are formed is provided to increase the pressure and block pulsation.

0003

However, in the above structure, when the resin sent by the propulsive force of the screw 22 reaches the screw head 22a, the resin flows through the guide hole 23.
Dead space 2 in front between screw heads 22a of a
The resin that remained at 3b deteriorated the extrusion performance of the extruder. In particular, thermosetting resins sometimes harden due to temperature changes due to stagnation, making operation difficult. Furthermore, it caused burns in the case of polyvinyl chloride and excessive foaming in the case of resin containing a foaming agent, making it impossible to operate for a long time. Further, during resin replacement work or color change work, molten resin adhered to the periphery of the screw head 22a, and this cleaning work required a great deal of labor.

[0004] The present invention solves the above-mentioned problems and prevents the extrusion molding material from stagnation in the screw head, allowing good operation for a long time even with thermosetting resins and resins containing foaming agents. It is an object of the present invention to provide a multi-screw extruder that does not cause thermal decomposition and can easily perform raw material exchange operations.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention connects a conduit to the extruded material outlet of the screw casing via a merging adapter having a guide hole whose diameter decreases toward the outlet side. In a multi-screw extruder, a rectifying adapter with a large number of through holes is provided between the screw head and the merging adapter, and the screw head side inflow surface of this rectifying adapter is a curved surface with a certain gap left along the end surface of the screw head. It is formed into a shape.

[0006]

[Operation] According to the above structure, the extruded molding material extruded by the screw is extruded from the screw head through the gap into the through hole of the rectifying adapter, and is introduced from the through hole of the rectifying adapter into the guide hole of the merging adapter. and then sent out into the conduit. Therefore, this rectifier adapter can increase the back pressure inside the screw casing and suppress the pulsation of the extruded material, and in addition, there is only a certain gap in the part where the flow from the screw head to the rectifier adapter occurs. Therefore, the extrusion molding material does not stagnate, which prevents the extrusion molding material from stagnation, and enables good operation for a long time even with thermosetting resins or resins containing foaming agents. Moreover, since there is less molten raw material in the screw head when replacing raw materials, the work can be done easily.

[0007]

[Embodiment] An embodiment of a twin-screw extruder according to the present invention will be described below with reference to FIGS. 1 to 5. In Fig. 1, 1 indicates two screws 2 that mesh with each other and rotate in the same direction.
. . Inside the adapter case 3, from the screw head 2a side, a rectifying adapter 5,
A breaker plate 6 and a merging adapter 7 are attached.

As shown in FIG. 2, the barrel 1 has a kneading hole 1a formed in a figure-8 cross section for accommodating two screws 2, 2. Further, in the rectifying adapter 5, a large number of through holes 5b each having a diameter of 3 to 6 mm are formed in the axial direction of the screw in an 8-shaped hole forming range 5a that is smaller than the kneading hole 1a of the barrel 1. The inflow surface 5c on the screw head 2a side has two recesses 5d corresponding to the screw head 2a, with a constant gap d in the normal direction to the conical end surface of the screw head 2a. .

According to experiments, this gap d is 2 mm or more.
It is set to be constant within a range of mm or less. If this is less than 2 mm, burning will occur due to shear heat generation of the resin in the gap d, and in the case of a resin containing a foaming agent, over-foaming will easily occur. On the other hand, if it exceeds 10 mm, the rectifying effect will be reduced and flow marks will easily occur, and if it becomes even larger, stagnation will occur. This rectifies the resin extruded from the screw 2 and prevents the resin from staying in the kneading hole 1.
It is possible to increase the back pressure of the molten resin in a and suppress the pulsation of the molten resin. Note that this rectifying adapter 5 is not provided with a screen (wire mesh).

As shown in FIG. 1, the breaker plate 6 is provided with a recess 6c for attaching a screen mesh on the side of the rectifier adapter 5, and in this recess 6c, it is connected to the through-hole forming area 5a of the rectifier adapter 5. A large number of through holes 6b are formed in the axial direction of the screw in a figure 8-shaped through hole forming range 6a having a congruent shape or a small similar shape. By forming this through hole 6c at a position shifted from the through hole 5b of the rectifying adapter 5, the back pressure of the molten resin in the kneading hole 1a is further increased to perform stronger kneading, and further suppress the pulsation of the molten resin. can do. Further, by providing a screen in the recess 6c for attaching the screen mesh, dust in the resin can be removed.

The merging adapter 7 is formed with a guide hole 7a whose diameter is gradually reduced from an 8-shaped cross section corresponding to the through-hole forming range 6a of the breaker plate 6 to the same shape as the circular passage 4a of the conduit 4.

According to the above structure, the molten resin pushed out from the kneading hole 1a by the screw 2 is rectified by the rectifying adapter 5 at the screw head 2a portion and introduced from the through hole 5b into the through hole 6b of the breaker plate 6. and further from the guide hole 7a of the merging adapter 7 to the conduit 4.
sent to. At this time, since the resin is introduced into the through hole 5b through a certain gap d in the screw head 2a portion, there is no dead space generated and the resin stagnates as in the conventional case. Moreover, this rectifying adapter 5 together with the breaker plate 6 can more effectively increase back pressure and block pulsation.

[0013] In the above embodiment, the through hole forming range 5a,
Although 6a has a figure 8 shape, it may be oval as shown in FIG. 6, or may be cocoon-shaped as shown in FIG.

FIG. 8 shows an embodiment in which the breaker plate 6 is omitted in the case of a resin material in which sufficient back pressure and pulsation suppression can be obtained with the rectifier adapter 5 alone. In this embodiment, the same adapter case 3 as in the above embodiment is used, the breaker plate 6 is removed, the merging adapter 7 is moved to the mounting part of the breaker plate 6, and the spacer ring 11 is attached to the mounting part of the merging adapter 7. are doing. Thereby, even if the resin raw material is changed, the extrusion work can be performed using the same member.

[0015]

As described above, according to the present invention, the extrusion molding material extruded by the screw is extruded from the screw head through the gap into the through hole of the rectifying adapter, and merges from the through hole of the rectifying adapter. It is introduced into the guide hole of the adapter and sent out into the conduit. Therefore, this rectifier adapter can increase the back pressure inside the screw casing and suppress the pulsation of the extruded material, and in addition, there is only a certain gap in the part where the flow from the screw head to the rectifier adapter occurs. Therefore, the extrusion molding material does not stagnate, which prevents the extrusion molding material from stagnation, and enables good operation for a long time even with thermosetting resins or resins containing foaming agents. Moreover, since there is less molten raw material in the screw head when replacing raw materials, the work can be done easily.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a barrel tip showing an example of a twin-screw extruder according to the present invention.

FIG. 2 is a sectional view taken along line AA shown in FIG. 1;

FIG. 3 is a cross-sectional view taken along line BB shown in FIG. 1;

FIG. 4 is a sectional view taken along the line CC shown in FIG. 1.

FIG. 5 is a sectional view taken along line DD shown in FIG. 1;

FIG. 6 is a front view showing another embodiment of the rectifying adapter.

FIG. 7 is a front view showing still another embodiment of the rectifying adapter.

FIG. 8 is a longitudinal cross-sectional view showing the barrel tip of a twin-screw extruder according to another example.

FIG. 9 is a longitudinal sectional view showing the barrel tip of a conventional twin-screw extruder.

[Explanation of symbols]

1 Barrel 2 Screw 2a Screw head 3 Adapter case 4 Conduit 5 Rectifier adapter 5a　　　Through hole formation range 5b Through hole 6 Breaker plate 6a　　　Through hole formation range 6b Through hole 7 Merging adapter 7a Guide hole d Gap

Claims (1)

[Claims] Claim 1. A multi-screw extruder in which a conduit is connected to an extrusion material outlet of a screw casing via a merging adapter having a guide hole whose diameter decreases toward the outlet side,
A rectifying adapter with a large number of through holes is provided between the screw head and the merging adapter, and the inflow surface on the screw head side of this rectifying adapter is formed into a curved shape with a constant gap along the end surface of the screw head. Features a multi-screw extruder.