JPH0857937A - Cross head - Google Patents

Abstract

PURPOSE: To reduce the variation and stagnation of a resin discharge rate and also reduce the frequency of occurrence of foreign matters by providing a conical raised part at the resin outflow side of a breaker plate, and allowing the conical raised part to enter the funnel-shaped resin inflow part at the die side. CONSTITUTION: A conical raised part 31 is provided at the resin outflow side of a breaker plate 30, and the conical raised part 31 of the breaker plate is allowed to enter the funnel-shaped resin inflow part 5 within a cross head. Then, the resin discharged from the screw 2 is passed through the circular hole of the breaker plate 30 and then flows in the side of the cross head main body 4. In the course thereof, although the resin flows in a manner to be merged In the funnel-shaped resin inflow part 5 at the resin outflow side of the breaker plate, the cross section for resin flowing part to the funnel-shaped resin inflow part becomes small at the conical raised part 31 of the breaker plate, moreover, thereby resulting in the prevention of a rapid decrease of pressure in the flow of resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a crosshead in a resin extruder for extrusion-coating a linear member such as an electric wire with a resin.

[0002]

2. Description of the Related Art FIG. 3 shows a cross-sectional structure of a conventional example of a crosshead in a resin extruder.
The resin discharged in a molten state by the rotation of the screw 2 inside passes through the lotus stump-shaped breaker plate 3 and then gathers into the mortar-shaped resin inflow portion 5 on the crosshead body 4 side, and continuously. It flows into the passage 6 in the crosshead body, and is further extruded in an annular shape from the outlets 10 through the narrow passage 9 between the cored bar 7 and the base 8 of the head main body 4 and passes through the cored bar 7 from the direction of the arrow. It is coated on the moved conductor. The breaker plate 3 has a large number of circular holes 3a as a group, and is provided between the extruder main body 1 and the crosshead main body 4 so that the resin flows in a fixed direction. Further, by providing a mesh, foreign matter in the molten resin is removed.

[0003]

In the crosshead structure as described above, the cross-sectional area ratio of the screw 2 to the outlet 10 of the crosshead body is 10: 1 to 1 due to the influence of the mechanical strength of the screw 2 and the like. It becomes 100 to 1. Therefore, on the resin outflow side of the breaker plate 3, the mortar-shaped resin inflow part 5
The inside portion becomes a portion where the pressure drops sharply, which causes a problem such as fluctuation of the resin discharge amount, that is, generation of foreign matter due to stagnation of the resin.

Therefore, an object of the present invention is to provide a crosshead for resin extrusion coating in which a sudden pressure drop does not occur in the resin flow in the crosshead.

[0005]

The crosshead provided by the present invention has a conical ridge on the resin outflow side of the breaker plate, and the conical ridge enters into the mortar-shaped resin inflow part on the die side. Therefore, the pressure drop at the resin outflow side of the breaker plate in the crosshead is alleviated and the resin flow is smoothed.

It is better to make the taper angle of the conical ridge and the taper angle of the mortar-shaped resin inflow portion equal to or equal to each other.

[0007]

FIG. 1 shows a preferred embodiment of a crosshead according to the present invention, and FIG. 2 shows an embodiment of a breaker plate in the same crosshead.
Since the same parts as those in FIG. 3 are denoted by the same reference numerals, the above description regarding FIG. 3 should also be referred to.

In this embodiment, the breaker plate 30 has a conical ridge 31 on the resin outflow side. Then, the conical protrusion 31 of the breaker plate is made to enter the mortar-shaped resin inflow portion 5 in the crosshead. In addition, 30a is a circular hole for resin passage formed in the breaker plate itself.

In the crosshead as in this embodiment,
The resin discharged in a molten state from the screw 2 passes through the circular hole 30a of the breaker plate 30 and passes through the crosshead body 4
It flows into the mortar-shaped resin inflow part, but when it tries to flow into the mortar-shaped resin inflow part 5 on the resin outflow side of the breaker plate so as to gather in the mortar-shaped resin inflow part, That is, the cross-sectional area of the resin flowing portion is reduced, which prevents a sudden pressure drop in the resin flow.

By making the taper angle of the conical ridge 31 of the breaker plate equal to or equal to the taper angle in the mortar-shaped resin inflow portion on the crosshead side, there is no factor that disturbs the flow of the resin, and the smoothness of the resin is eliminated. Allow flow.

[0011]

According to the crosshead of the present invention as described above, the breaker plate has a conical ridge on the resin outflow side, and the conical ridge is placed in the mortar-shaped resin inflow part on the crosshead side. Since the resin is allowed to enter, fluctuations in the discharge amount of the resin continuously supplied are reduced. The flow of the resin becomes smooth, the stagnation of the resin is reduced, and the frequency of generation of foreign matters is reduced. The crosshead cleaning time is shortened because the stagnation of the resin in the mortar-shaped resin inflow portion in the crosshead is eliminated and foreign matter is less likely to be generated. It is possible to make the resin flow even smoother by making the taper angle of the conical ridge on the breaker plate side match or equal to the taper angle, especially in the mortar-shaped resin inflow part in the crosshead body. is there. It is also possible to reduce the purge material and the purge time when changing the type or hue of the resin. And so on.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a crosshead according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a breaker plate used in the crosshead according to the present invention.

FIG. 3 is a cross-sectional view showing a conventional crosshead example.

FIG. 4 is a cross-sectional view showing an example of a breaker plate used for a conventional crosshead.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder main body 2 Screw 4 Crosshead main body 5 Mortar-shaped resin inflow part 6 Resin flow passage 7 Core metal 8 Base 9 Resin flow passage 10 Exit 30 Breaker plate 30a Circular hole 31 Conical protrusion

Claims (2)

[Claims] 1. A crosshead comprising a breaker plate having a conical ridge on the resin outflow side, and the conical ridge entering into a mortar-shaped resin inflow part on the die side. 2. The crosshead according to claim 1, wherein a taper angle of the conical ridge and a taper angle of the mortar-shaped resin inflow portion are made equal to or equal to each other.