JPH0576726U - Extruder crosshead - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an extruder crosshead capable of easily preventing uneven thickness of extrusion coating without changing the distance between the rotary die 4 and the nipple 2. [Structure] On the outer periphery of the nipple holder 3 near the nipple joint portion, a resistance sleeve 6 having an uneven thickness is inserted so as to project with respect to the material flow passage 5. With the resistance of the thick portion 6a of the resistance sleeve,
The amount of molten insulating material flowing therethrough is small, and the amount coated on the cable core is small. On the other hand, since the thin portion 6b of the resistance sleeve does not project so much into the material flow passage 5, the resistance to the molten insulating material is small and the amount of insulating material coated on the cable core is relatively large. This effect is used to prevent uneven thickness of the extrusion coating.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an extruder crosshead having a rotary die.

[0002]

[Prior Art]

 For example, when a spiral ridge is provided on a rubber or plastic insulator of a cable, a rotary die having a longitudinal groove on the inner surface is used for the crosshead of an extruder. While the rotary die is being rotated, the molten insulating material is extrusion-coated on the cable core, so that the spiral ridge is extrusion-molded integrally with the insulator.

[0003]

[Problems to be solved by the device]

 By the way, in general, when the cable insulation is extruded, the molten insulating material flowing from the extruder body into the crosshead circulates around the nipple holder in the material flow passage existing between the head body and the nipple holder. Since the flow resistance of the molten insulating material is different from that of the lower portion of the nipple holder, the flow path of the molten insulating material is difficult to be determined, and uneven thickness is likely to occur in the molded insulator.

In order to prevent uneven thickness of the extrusion coating when using a commonly used fixed die for the crosshead of the extruder, the position of the fixed die with respect to the nipple is appropriately changed in the radial direction. The distance between the die and the nipple is adjusted.

However, when the rotary die as described above is used, the distance between the rotary die and the nipple constantly changes. Therefore, the adjustment method of changing the die position like the fixed die is not possible. Cannot be adopted.

The present invention has been made in view of such a point, and provides an extruder crosshead capable of easily preventing uneven thickness of the extrusion coating without changing the distance between the rotary die and the nipple. With the goal.

[0007]

[Means for Solving the Problems]

 The crosshead of the extruder of the present invention comprises a nipple and a nipple holder in the head body, and a crossing head of the extruder in which a rotary die is provided coaxially with the nipple. It is characterized in that a resistance sleeve having an uneven thickness is inserted on the outer periphery so as to project to the material flow passage.

[0008]

[Action]

 The amount of molten insulating material flowing in the material flow passage between the head body and the nipple holder is reduced due to the resistance of the thick part of the sleeve, so the amount covered by the cable core at the tip of the nipple is reduced. .. On the other hand, in the thin portion of the resistance sleeve, the resistance to the molten insulating material is small because it does not protrude so much into the material flow passage, and the amount of insulating material coated on the cable core increases at the tip of the nipple. This effect is used to prevent uneven thickness of the extrusion coating.

Since the distance between the die and the nipple can be changed by appropriately changing the length of the resistance sleeve, it is possible to adjust the coating thickness of the molded insulator.

[0010]

【Example】

 Hereinafter, the crosshead of the present invention will be described according to the embodiment shown in the drawings.

1 and 2 are views showing an embodiment of the present invention. In FIG. 1, a regular nipple 2 and a nipple holder 3 for holding this nipple are arranged in a cylindrical head body 1. The nipple 2 is detachably joined to the nipple holder 3 by screwing. A rotary die 4 is provided at the end of the head body 1 so as to be coaxial with the nipple 2 and rotatable. Although not shown, the rotary die 4 is driven to rotate by an electric motor.

A material flow passage 5 is provided between the head body 1 and the nipple holder 3 and between the rotary die 4 and the nipple 2, respectively. A resistance sleeve 6 is fitted on the outer periphery of the nipple holder 3 near the nipple contact portion, and projects into the material flow passage 5. The resistance sleeve has an uneven thickness as shown in FIG. 2, and a thick portion 6 a thereof is located above the nipple holder 3. The resistance sleeve is pressed and fixed by the end surface of the nipple 2 screwed into the nipple holder 3.

The crosshead of the extruder of the present invention is configured as described above, and the molten insulating material flowing into the crosshead from the extruder main body (not shown) at the time of extrusion molding is used to separate the head main body and the nipple holder. In the material flow passage 5, the flow amount is adjusted by the resistances of the thick portion 6a and the thin portion 6b of the resistance sleeve. By utilizing this, it is possible to prevent uneven thickness of the extrusion coating.

That is, since the molten insulating material flows in the material flow passage 5 due to the resistance of the thick portion 6a of the resistance sleeve located at the upper portion of the nipple holder 3, the amount of the molten insulating material is reduced. The amount coated on (not shown) is reduced. On the other hand, since the resistance sleeve thin-walled portion 6b below the nipple holder 3 does not protrude so much into the material flow passage, the resistance to the molten insulating material is small and the amount of the insulating material coated on the cable core at the lower portion of the nipple tip is Many compared to the top.

By appropriately changing the length of the resistance sleeve 6, the screwing amount of the rotary die 4 with respect to the nipple holder 3 is changed, so that the distance from the nipple 2 can be changed, so that the insulation to be formed can be changed. The body coating thickness can be adjusted.

[0016]

[Effect of the device]

 As described above, according to the present invention, even in the crosshead of the extruder having the rotary die, by using the resistance sleeve having an appropriate thickness, the extrusion can be performed without changing the distance between the rotary die and the nipple. Uneven thickness of the coating can be easily prevented.

Further, by appropriately changing the length of the resistance sleeve, the coating thickness of the molded insulator can be adjusted. In addition, the resistance sleeve is easy to install because it is simply fitted into the nipple holder and fixed with a rotating die.

[Brief description of drawings]

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

FIG. 2 is a front view showing a resistance ring used in the embodiment.

[Explanation of symbols]

 1 ... Head body 2 ... Nipple 3 ... Nipple holder 4 ... Rotating die 5 ... Material flow path 6 ... Resistance sleeve

Claims (1)

[Scope of utility model registration request] 1. A crosshead of an extruder in which a nipple and a nipple holder are provided in a head main body and a rotary die is provided coaxially with the nipple, and a bias is provided on an outer periphery of the nipple holder near the nipple joint portion. A crosshead of an extruder, wherein a fleshed resistance sleeve is inserted so as to project into a material flow passage.