JPS603456Y2 - Die of extruder for wire coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a die for an extruder for covering electric wires in which no resin particles are deposited around the tip of the die hole during the coating of electric wires.

When electrical wires are coated with polyethylene, problems that do not occur with vinyl chloride coatings arise, for example with respect to tackiness when melted.

The problem is that when an extruder coats polyethylene around the core wire and extrudes it from the tip of a rad die into a cloth, a small amount of polyethylene resin builds up concentrically around the die hole. .

If such resin sludge is allowed to accumulate, the resin sludge will peel off from the tip of the tie during extrusion and adhere to the surface of the coated wire, resulting in a total loss of commercial value of the wire.

For this reason, in conventional polyethylene coating processing, a gas burner is installed near the tip of the die hole facing upward, and the resin residue is burned or burnt off by the gas burner.

However, if the resin scum is not completely burned off, there remains the problem that the remaining resin scum will adhere to the coated wire.

In particular, when wires are coated with a silane crosslinking compound, which is a combination of polyethylene and a silane crosslinking agent, the resin residue around the die hole cannot be burned off with a gas burner because the silane crosslinked polyethylene has good heat resistance.

Therefore, in the process of coating electric wires using silane-crosslinked polyethylene, it is an urgent problem to prevent resin particles from adhering around the goo holes.

The extruder die according to this invention solves the above-mentioned problems regarding wire coating with polyethylene resin by a relatively simple method.

Therefore, an object of this invention is to provide a die for an extruder for wire coating that prevents resin scum from being deposited around the tip of the die hole by attaching a pin around the tip.

Next, an embodiment of this invention will be described in detail based on the drawings.

FIG. 1 schematically shows the tip portion of a crosshead of an extruder for coating electric wires.

A die 3 is detachably fixed to the tip of the crosshead main body 1 by a die holder 2a and an annular holding fitting 2b.

The die 3 is a crosshead die, which is generally made of iron.

The die hole 4 is provided at the center of the die 3, and the diameter of the hole gradually increases from the tip of the die toward the rear, and expands into a conical shape at the rear of the die.

As a result, when the die 3 is installed at the tip of the crosshead body 1, the diameter of the rear end of the die hole 4 matches and communicates with the diameter of the center hole of the crosshead body 1.

Further, a cylindrical nipple holder 5 is coaxially installed in the center hole of the crosshead body 1, and a conical nipple 6 attached to the tip of the nipple holder has its tip connected to the die hole 4.
It is located near the upper end of the rear enlarged part of.

With this configuration, a cylindrical resin passage 7 is formed between the outer periphery of the nipple holder 5 and the inner wall of the center hole of the crosshead body 1, and the conical outer periphery of the nipple 6 and the rear enlargement of the die hole 4 are formed. A resin conical passage 8 is formed between the inner wall of the part and the inner wall of the part.

The nipple holder 5 and the nipple 6 have a small diameter central hole 9 through which the core wire passes, and the hole becomes smaller in diameter at the tip of the nipple 6.

The pin 10.10 for removing resin residue is attached to the tip surface 3 of the die 3.
Attach around the die hole 4 at point a.

The pin 10.10 is generally arranged parallel to the axis of the die hole 4 and is cylindrical, for example as shown in FIG.

The two pins 10.10 are preferably arranged diametrically opposite to each other with respect to the center of the die hole 4, and preferably arranged so that they coincide in the vertical direction.

Although it is advantageous in manufacturing that the pin 10 has a cylindrical shape as illustrated in FIG. 2, it is also possible to use a prismatic pin 11 as illustrated in FIG. 3, or a pin of any other desired shape. It's okay.

In addition, the number of pins 10 is three in addition to the two shown in FIG.
As shown in the figure, one pin may be installed above the die hole 4, or three or more pins may be arranged at equal intervals, but as the number of pins increases, it becomes difficult to align the core wires at startup. Work may become difficult.

It is preferable to attach the pin 10 as close as possible to the periphery of the die hole 4 for manufacturing reasons.This attachment may be done integrally with the die 3 itself, or by providing a desired hole in the die tip surface 3a and placing it inside the hole. It is also possible to fix it by driving a pin of a corresponding shape into it.

For example, in the case of the die 3 having an outer diameter of 19 mm, the outer diameter of the die step 12 is 10 groups, the length from the rear end of the step to the rear end of the die 3 is 39rIrIn, and the diameter is 10 mm. 2.2mm
The height of the pin 10 is set as 5771771, and the distance between the outer circumference of the pin and the inner wall of the die hole 4 with a diameter of 2.2rrrm is 0.
．． It is 5Wn.

When the wire coating extruder is operated, the preheated core wire is sent forward through the center hole 9 of the nipple holder 5 and nipple 6, while the molten and kneaded polyethylene resin passes through the resin passage 7 and is shaped into a conical shape. It leads to passage 8.

The core wire and the molten resin meet at the die hole 4, and the covered wire comes out from the tip of the die hole 4, so that the core wires are aligned at the time of starting.

The coated wire is wound up after cooling. As the wire coating process continues, around the tip of the die hole 4 where the molten polyethylene resin comes out, a small amount of the resin tends to adhere and expand in concentric circles.

However, when the outer peripheral edge of the resin scum and each outer peripheral wall of the pin 10. Peel off from 3a.

Part of the resin scum breaks and falls downward, and the other part adheres around the pins 10 and 10, so that the resin scum does not adhere to the coated wire.

When the die according to this invention is used, no resin particles will be deposited around the tip of the die hole during the wire coating process with polyethylene resin.

Therefore, there is no need to burn off the resin scum using a gas burner during extrusion of polyethylene, which facilitates the polyethylene coating process, and also solves problems caused by incomplete burning off of the resin scum.

In particular, when a silane-crosslinked polyethylene compound is used, burn-off itself, which was previously impossible, becomes unnecessary, so the die of this invention is particularly useful in the process of coating electric wires with silane-crosslinked polyethylene.

Therefore, the die according to this invention has many advantages in that it reduces the work involved in coating wires with polyethylene resin and increases the commercial value of wires coated with polyethylene resin.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view showing the tip of a crosshead of an extruder for wire coating using a die according to this invention, FIG. 2 is a front view showing an embodiment of the die according to this invention, and FIG. The figure is a front view of a die that is a modification of this invention. 1...Crosshead body, 3...Die, 4...Die hole, 5...Nipple holder, 6...Nipple, 10 ,10...
Pin for removing resin scum.

Claims (1)

[Scope of utility model registration request] In order to remove resin scum that adheres concentrically around the tip of the die hole by destroying it due to internal strain, two cylindrical pins are placed at the tip of the die so that their outer peripheral walls are slightly separated from the periphery of the die hole. A die for an extruder for electrical wire coating, characterized in that both pins are arranged diametrically opposite to each other with respect to the center of the die hole and coincident in the vertical direction.