JPS6234747Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to an extruder crosshead pressure reducing device for reducing the pressure inside the nipple holder of an extruder crosshead.

(Prior art) When extruding rubber or plastic to coat the outer periphery of a filament such as a cable core, the gap inside the cable core or its surface is vacuumed before the rubber or plastic is extruded and coated. This is done to ensure that there are no air bubbles between or within the cable core. In order to do this, it is necessary to evacuate the inside of the nipple holder cylinder of the extruder crosshead to reduce the pressure.

An example of a conventional extruder crosshead pressure reduction device will be described with reference to FIG. The extruder crosshead 1 has a structure in which a die and a nipple 5 are arranged concentrically at the outlet of an extrusion passage 3 in a crosshead main body 2 with a predetermined gap, and the nipple 5 is supported at the tip of a nipple holder cylinder 6. Extrusion passage 3
The rubber/plastic coated strand 7 is extruded and coated on the outer periphery of a strand 8 such as a cable core positioned by the nipple 5 to obtain a rubber/plastic coated strand 9. In the pressure reducing device 10, the outlet of the pressure reducing cylinder 11 is fixed to the crosshead 1 so as to communicate with the nipple holder cylinder 6, and a packing 12 is fixed to the linear body inlet of the pressure reducing cylinder 11 with a holder 13 as a sealing means. The structure is such that the pressure inside the pressure reduction cylinder 12 is reduced by evacuation from the pressure reduction hole 14. In addition, 15 is a pressure reduction gauge connected to the pressure reduction cylinder 11.

In such a pressure reducing device 10, in order to increase the pressure reducing effect, the clearance between the hole diameter of the packing 12 and the filament 8 should be made as small as possible, and the clearance between the packing 12 and the filament 8 should be minimized.
It is necessary to make the holes 2 and the surface of the filament 8 contact each other, but in this case, if the packing 12 is made of rubber, for example, there is a drawback that the packing 12 may be dragged due to frictional resistance. There is a drawback that the pressure reduction effect deteriorates due to wear. Furthermore, when the filament 8 is a twisted body, there is a drawback that the pressure reduction effect is reduced. In addition, in such a structure, when a separator is longitudinally attached to the outer periphery of the filament body 8 and rubber/plastic is extruded and coated on top of the separator, if a packing is used as a sealing means, the separator's longitudinally attached coating is There were some drawbacks that made it difficult to deal with.

(Purpose of the invention) The purpose of the invention is to prevent the shearing movement and wear of the sealing means, to ensure the necessary depressurizing effect even when the filament is a twisted body, and to easily cover the separator vertically. The purpose of the present invention is to provide an extruder crosshead pressure reduction device.

(Structure of the invention) A vacuum cylinder is airtightly connected to a nipple holder cylinder in an extruder crosshead that penetrates the filament and extrudes rubber or plastic to cover the outer periphery of the filament. is sealed by a sealing means, and in an extruder crosshead pressure reducing device for reducing pressure by evacuating the inside of the pressure reducing cylinder and the nipple holder cylinder through a pressure reducing hole, a seal having a filament passageway along the axis as the sealing means. A cylinder is used, and the seal cylinder is inserted into the vacuum cylinder, and the outer periphery of the outer end thereof is airtightly supported at the linear body inlet of the vacuum cylinder.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 2 and 3. Note that parts corresponding to those in FIG. 1 are designated by the same reference numerals. In this embodiment, a metal seal cylinder 16 is used as a sealing means for the linear body inlet of the decompression cylinder 11.
is inserted into the vacuum tube 11 from its filament body inlet, and the flange portion 16A at the outer end of this seal tube 16 is brought into contact with the outer periphery of the filament body inlet of the pressure vacuum tube 11 to close the holder 1.
3, the structure is airtightly supported. The seal cylinder 16 is provided with a filament passage 16B for passing the filament body 8 along its axis. This striatal pathway 1
6B is formed to be slightly larger than the outer diameter of the filament body 8.

In such an extruder crosshead pressure reducing device, the seal cylinder 16 is used as a sealing means, so even if the filament passage 16B is provided in the center, when the filament body 8 is passed through, due to its length, Air resistance increases and the necessary sealing effect can be obtained.

Experimental example: The end of a vacuum tube is airtightly connected to the inlet of the nipple holder tube of the crosshead, and a seal tube with an inner diameter of 3.5 mmφ and a length of 40 mm is inserted and set into the linear body inlet of the vacuum tube. A filament with an outer diameter of 3 mmφ was passed through the cylinder, and the inside of the cylinder was evacuated by a vacuum pump from the decompression port to reduce the pressure, and a depressurization effect of more than 70 cm/Hg was obtained. In order to obtain a greater pressure reduction effect, the length of the seal cylinder may be increased.

(Effects of the invention) As explained above, in the extruder crosshead pressure reducing device according to the present invention, the sealing cylinder is used as a sealing means for the linear body inlet of the pressure reducing cylinder. becomes large, and the necessary sealing effect can be obtained. Furthermore, since this sealing means is cylindrical, it can also solve the problem of shearing movement and the problem of decompression effect due to wear, which are disadvantages when using a rubber gasket. Furthermore, if the seal tube is used as the sealing means, it can also be used as a facing tube, and the separator can be easily covered vertically.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a conventional extruder crosshead pressure reducing device, Fig. 2 is a longitudinal sectional view of an embodiment of the extruder crosshead pressure reducing device according to the present invention, and Fig. 3 is a longitudinal sectional view showing an example of a seal cylinder. It is a diagram. 1...Extruder crosshead, 2...Crosshead main body, 3...Extrusion passage, 4...Dice, 5...
Nipple, 6...Nipple holder tube, 7...Rubber/plastic, 8...Striatal body, 9...Rubber/plastic
Plastic-coated filamentary body, 10... pressure reduction device, 1
1... pressure reduction tube, 14... pressure reduction hole, 16... seal tube, 16B... striatal body passage.

Claims (1)

[Scope of utility model registration request] A vacuum cylinder is airtightly connected to a nipple holder cylinder in an extruder crosshead that penetrates the filament and coats its outer periphery with rubber/plastic, and the inlet of the filament body of the vacuum cylinder is sealed with a sealing means. In the extruder crosshead depressurization device that vacuums the inside of the decompression cylinder and the nipple holder cylinder to reduce the pressure from the decompression hole, a seal cylinder having a filament passageway along the axis is used as the sealing means. 2. An extruder crosshead pressure reducing device, characterized in that the seal cylinder is inserted into the pressure reducing cylinder, and the outer periphery of the outer end thereof is airtightly supported by the linear body inlet of the pressure reducing cylinder.