JPH03270922A - Fish tail type head of extruder - Google Patents

Abstract

PURPOSE:To eliminate the excess or short feeding of rubber, and realize nearly uniform extrusion of rubber through an efflux port by a method wherein truncated quadrangular pyramid-like projections are provided in a fish tail type head, the ratio of widths of the suction of the efflux port and of an upstream side section and the ratio of their heights of which are specified under the condition that the width of each projection becomes gradually wider towards the efflux port and the flat vertical faces are set to be nearly parallel to each other. CONSTITUTION:Since rubber flow path is formed by providing truncated quadrangular pyramid- like projections 38 and 39, the shape of the base of each of which is a trapezoid gradually wider toward the efflux port 27, in a fish tail type head, the ratio of widths of the section of an efflux port and of an upstream side section of which lies with the range of 1-2 and the ratio of their heights of which lies with the range of 0.5-1, these projections 38 and 39 give whole rubber nearly uniform components of force directing to both sides of each projection, resulting in distributing rubber uniformly widthwise in the rubber flow path 25. Further, since the top faces 44 and 45 of the projections 38 and 39 are nearly parallel to each other, no abrupt enlargement of the space in the flow direction of the rubber flow path 26 is present, resulting in developing neither starvation of rubber nor stagnation of air in any position of the rubber flow path 26. Accordingly, easy extrusion of uniform rubber from the efflux port 27 results.

Description

[Detailed description of the invention] This invention relates to a fishtail head for a rubber extruder.

Conventionally, as a fishtail-shaped head of an extruder, the one described in, for example, Japanese Patent Application Laid-open No. 1156/1983 has been known. As shown in Fig. 4.5, this rubber channel 2 has a rubber channel 2 with a flat circular longitudinal section, and this rubber channel 2 has a width A at an outlet 3 and an inlet 4. and B ratio (A/B) is 2 or more, and the outlet 3
and the ratio of the heights C and D at the inlet (C/D
) is in the range of 0 to 0.5, that is, the longitudinal cross-sectional shape changes rapidly to become flat. Also, each of the large curvature regions 5 and 6 of the rubber flow path 2 has triangular pyramid-shaped protrusions. , 8 are provided, each protrusion? , 8 has a triangular shape that becomes wider as it goes from the inlet 4 to the outlet 3, and the triangular slopes 8.10 of the protrusions 7 and 8 near the outlet 3 are approximately parallel to each other. . When the rubber flows from the inflow port 4 toward the outflow port 3, the rubber receives force from these protrusions 7 and 8 in both directions, and is distributed into the rubber flow path 2. This results in
There is no excess or deficiency of rubber in each part of the outlet 3, and the cross-sectional shape of the rubber extruded from the outlet 3 becomes almost uniform.

By the way, as shown in Fig. 6.7, the rubber channel through which the rubber flows has radiuses A and B in a cross section at the outlet 12 and a position 13 upstream from the outlet 12, here, at the inlet. The ratio of the heights C and D in the cross-section at the outlet 12 and in the cross-section at the upstream position 13 may range from 0.5 to 1, with the ratio ranging from 1 to 2. In such a case, the above-mentioned triangular pyramid-shaped protrusion may be used to distribute the rubber within the rubber flow path 14. , 8, we get
protrusion? , 8 is too low, sufficient distribution is not achieved, resulting in a shortage of rubber at both ends. For this reason, it is conceivable to increase the height of the protrusion 15.1B as shown in the drawing, and to apply a large component of force distributed to both sides of the rubber.

However, if you do this, the triangular slope17.18
As the angle of inclination increases, the space rapidly expands from the top of the protrusion 15. There is a problem in that a recess extending in the longitudinal direction occurs at the center of the width direction.

An object of the present invention is to provide a fishtail head of an extruder that can easily extrude substantially uniform rubber with no excess or deficiency of rubber at any position from an outlet.

Such a purpose is such that the width ratio in the cross section of the outlet and the upstream cross section upstream of the outlet is in the range of 1 to 2,
The ratio of the heights in the outlet cross section and the upstream cross section is 0.
. A truncated quadrangular pyramid-shaped protrusion is provided, and the bottom shape of the protrusion is made into a trapezoid that becomes wider toward the outlet, and the flat top surface of the protrusion is replaced by the flat top surface of the other protrusion or the large curvature area of the other protrusion. This can be achieved by making it substantially parallel to.

Suppose that the rubber is now flowing in the rubber channel toward the outlet. Here, the rubber channel has a width ratio of 1 to 2 at the outlet cross section and the upstream side cross section, and a height ratio of 0.5 to 1 at the outlet cross section and the upstream side cross section.
In this invention, the protrusion has a trapezoidal truncated pyramid shape whose bottom surface becomes wider toward the outlet, and the protrusion extends from the protrusion to the entire rubber on both sides. In addition to distributing the rubber uniformly in the width direction within the rubber channel by applying an almost uniform component force toward the direction, the flat top surface of the protrusion is connected to the flat top surface of the other protrusion or the large curvature area of the other protrusion. The shapes are shaped like truncated pyramids so that they are substantially parallel, and the space in the rubber flow path does not expand rapidly in the flow direction to prevent insufficient filling of rubber and air pockets at any position within the rubber flow path. There is. As a result, there is no excess or deficiency of rubber at each part of the outlet, and substantially uniform rubber is easily extruded from the outlet.

Length”L example Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Fig. 1.2, 21 is an introduction block provided at the front end of the extruder and has an introduction passage 22 formed therein, and this introduction blow 2 21 is a cylinder housing an extrusion screw (not shown). It is connected to the front end,
As a result, when the extrusion screw rotates, rubber is extruded from the cylinder into the introduction passage 22. A fishtail-shaped head 25 is fixed to the front end of the introduction block 21, and within the fishtail-shaped head 25 is a rubber channel 2B that communicates with the introduction passage 22 and is supplied with the rubber that has passed through the introduction passage 22.
is formed. The rubber flow path 28 has a vertical cross-sectional shape, that is, a cross-sectional shape when broken in a plane perpendicular to the rubber flow direction, is an oblate circular shape, such as an ellipse or an oval shape, and has an outlet 27 and an upstream side of the outlet 27. , where the ratio of radius A and B (A/B) at the inlet 28 is in the range of 1 to 2, and the outlet 27 and the inlet 28
The ratio of heights C and D (C/D) in is from 0.5 to
1, that is, the cross-sectional shape changes to become gently flat along the flow direction of the rubber. and,
The inner peripheral surface of the rubber flow path 2B includes a pair of large curvature regions 31.32 with a large radius of curvature, and a pair of small curvature regions 33.3 with a small radius of curvature arranged between these large curvature regions 31.32.
4, and the large curvature regions 31 and 32 are respectively provided with quadrangular pyramid-shaped projections 38 and 39. The bottom shape of each protrusion 38, 39 is a trapezoid that becomes wider toward the outlet 27, and in this embodiment, the front and rear sides of the bottom are parallel to the outlet 27 and the inlet 2B, and Both sides extend parallel to both ends of the rubber flow path 26 in the width direction. Here, the length (depth) of the rubber flow path 26 is L,
If the length of the front side 46 at the top surface 44.45 of the protrusion 38.39 is F, the length of the rear side 47 is G, and the length of the top surface 44.45 in the longitudinal direction is J, then the value of G/H is The value of F/A is in the range of 0.2 to 0.8, and the value of F/A is in the range of 0.6 to 0.8.
The value of L ranges from 0.4 to 0.9, and the value of G/F ranges from 0.
A range of 1 to 0.7 is preferable, and the flat top surface 44 of the projection 38 is substantially parallel to the flat top surface 45 of the other projection 3S. Here, when the distance between the front sides 46 of the protrusions 38 and 39 is K, and the distance between the rear sides 47 is M, (M-
The value of K)/J must be -0.03 or more in order to prevent the rubber from peeling off from the top surface 44.45 when the rubber passes through, and is preferably 0 or more.
The value of /C is preferably in the range of 0.8 to 0.98, and the value of M/D is preferably in the range of 0.2 to 0.8. Note that the front end of the fishtail head 25 is not shown. A mouthpiece is attached, and the rubber extruded from the rubber flow path 2B passes through the mouthpiece and is acid-formed into a predetermined cross-sectional shape.

Next, the operation of one embodiment of the present invention will be explained.

Assume now that the extrusion screw rotates and rubber is supplied from the introduction passage 22 to the rubber flow path 28, thereby causing the rubber to flow in the rubber flow path 2B from the inlet 2B toward the outlet 27. At this time, since the rubber channel 26 is provided with projections 38 and 39 in the shape of a trapezoidal truncated pyramid whose bottom surface becomes wider toward the outlet 27, these projections 38 and 39 are provided.
39 applies a substantially uniform component force to both sides of the entire rubber, and distributes the rubber uniformly in the width direction within the rubber flow path 2B. These protrusions 38 and 39 are also formed on the top surface 44.
Since the 45 spaces are substantially parallel, there is no sudden expansion of the space in the flow direction of the rubber flow path 26, and as a result, insufficient filling of rubber and air pockets occur at any position within the rubber flow path 26. As a result, there is no excess or deficiency of rubber at each part of the outlet 27, and the outlet 2
From No. 7, a substantially uniform rubber can be easily extruded. and,
The rubber extruded from the outlet 27 passes through a die and is acid-formed into a predetermined cross-sectional shape.

In addition, in the above-mentioned embodiment, the large curvature region 31.32
In the present invention, as shown in FIG. 3, the protrusions 51 and 38 are provided on either the large curvature area 31 or 32, here only on the large curvature area 31. In this case, the flat top surface 52 of the protrusion 51 is substantially parallel to the other large curvature region 32. Furthermore, in the above embodiment,
Although the introduction block 21 and the fishtail head 25 are separate bodies, in the present invention, they may be integrated to form a fishtail head. In this case, the ratio of the width and height is , is the ratio of the cross section at the outflow port and the cross section at the position where the protrusion starts as viewed from the inflow port which is upstream from the outflow port and downstream from the inflow port.

Wataru Yomitate 1 As explained above, according to the present invention, it is possible to easily extrude almost uniform rubber with no excess or deficiency of rubber at any position.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention. FIG. 2 is a conceptual perspective view of a rubber flow path, FIG. 3 is a sectional view showing another embodiment of the present invention, FIG. 4 is a conceptual perspective view of a rubber flow path showing an example of a conventional fishtail head, and FIG. FIG. 5 is a sectional view thereof, FIG. 1116 is a conceptual perspective view of a rubber flow path showing another example of a conventional fishtail head, and FIG. 7 is a sectional view thereof. 25... Fishtail head 27... Outlet ports 31, 32... Large curvature regions 44, 45... Top surface

Claims (1)

[Claims] The flat surface has a width ratio of 1 to 2 in the outlet cross section and an upstream cross section upstream of the outlet, and a height ratio of 0.5 to 1 in the outlet cross section and the upstream cross section. A fishtail-shaped head of an extruder having a rubber flow passage whose longitudinal cross-sectional shape gradually changes in a circular shape,
A truncated quadrangular pyramid-shaped protrusion is provided on at least one of the large curvature regions of the rubber channel, the bottom shape of the protrusion is made into a trapezoid that becomes wider toward the outlet, and the flat top surface of the protrusion is formed on the other protrusion. A fishtail-shaped head of an extruder, characterized by having a flat top surface or substantially parallel to the other large curvature region.