JPS6337468B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a seal against a fluid, which is a pressurizing medium, in a heat and pressure mold used for forming a heat and pressure mold type joint for, for example, a cross-linked polyethylene insulated vinyl sheathed cable (hereinafter referred to as a CV cable). It's about structure.

CV cables are used for important lines on 154Kv to 275Kv class lines, but joints are required for long distance lines. The joint is a heat-pressure molded joint that uses polyolefin insulator, which is the same material as the cable insulator, from the viewpoint of electrical performance and reliability. Incidentally, such joints are made using a mold (generally, a split mold is used in consideration of on-site workability), and the inside of the mold is filled with, for example, nitrogen gas, dry air, It is formed by applying a pressurizing medium such as molten plastic resin or silicone oil to heat and pressurize the mold joint, and sealing the fluid that is the pressurizing medium is very important here.

FIG. 1 schematically shows a conventional fluid seal structure for this type of mold. In FIG. 1, a CV cable 1 is arranged between upper and lower split molds 7 and 8, and an annular packing member 5 having an inner diameter smaller than the outer diameter of the CV cable 1 is used for fluid sealing. 5 are placed on appropriate shoulders provided on the upper and lower molds 7 and 8. Furthermore, since this member 5 may fall off from the shoulder part due to the outward force applied along the CV cable 1 due to the pressurization by the pressurizing medium 9 in the mold, The molds 7, 8 are held by a suitable presser arm 4 directly fixed to the molds 7, 8
8 is supported from the outside, and is configured to prevent this falling off.

However, in such a conventional seal structure, since the presser arm 4 is directly fixed with bolts, it is not possible to follow the deformation of each part due to heating and pressurization of the mold, and the pressurizing medium cannot be used. It is relatively difficult to maintain a sufficient sealing effect for a certain fluid at all times.

An object of the present invention is to solve the drawbacks of the fluid seal structure in conventional heating and pressurizing molds and to provide a seal structure that can always exhibit a good fluid seal effect.

Hereinafter, the present invention will be explained in detail based on an embodiment shown in the drawings.

In Fig. 2, the conductors (not shown) of the CV cables 1 (only one CV cable is shown) to be connected to each other are electrically and mechanically connected to each other by conventionally known means, and a semiconducting conductor is placed on the circumference. An internal semiconductive layer (not shown) is arranged using a heat-shrinkable rubber/plastic tube, a semiconductive rubber/plastic molding unit, etc., and a polyolefin insulator is extruded and a polyolefin insulator tape is placed on the periphery of the inner semiconductive layer (not shown). Alternatively, an insulating layer (not shown) is arranged by winding a sheet or incorporating blocks of polyolefin insulator, and furthermore, a semiconductive rubber/plastic heat shrink tube, semiconductive polyolefin tape or sheet, etc. is placed on the periphery of the insulating layer (not shown). For example, a split annular metal collar 12 is placed on the circumference of the CV cable 1 near both ends of the joint portion (not shown) in which an external semiconductive layer (not shown) is arranged.
A heat-resistant diaphragm layer 13 such as a heat-shrink tube made of Teflon, a heat-shrink tube made of polyethylene, or a heat-shrink tube made of silicone rubber is provided so as to cover both collars 12 and the entire joint portion. Then, the entire joint portion prepared in this manner is placed between the molds 7 and 8.
Then, the annular packing member 5 is placed on the shoulders of the molds 7 and 8, and the presser arm 4 supports this member 5 from the side. In the present invention, the presser arm 4 is not directly fixed to the molds 7 and 8 with bolts, but is elastically fixed with bolts via a coil spring 6. By doing this, a uniform pressing force can be obtained whether the molds 7 and 8 are heated or cooled, and leakage of the pressurized medium 9 in the molds 7 and 8 can be stabilized. It can be prevented by doing so. That is, in addition to preventing leakage of the pressurized medium 9 by pressing the diaphragm layer 13 against the collar 12 by pressurization within the molds 7 and 8, the presser arm 4 provides an elastic presser force. An excellent effect can always be obtained in preventing leakage of the pressurized medium 9 regardless of temperature changes.

The sealing structure for the fluid that is the pressurized medium of the present invention is extremely simple, and therefore has extremely good workability and is highly reliable. This seal structure allows sealing under high temperature (250℃) and high pressure (approx. 20Kg/cm ² ), which was previously difficult, and can be easily applied even if the mold shape is complex. It is.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing a fluid seal structure of a conventional mold die, and FIG. 2 is a similar view showing a fluid seal structure of a mold die of the present invention. 1: cable, 4: presser arm, 5: annular packing member, 6: coil spring, 7, 8: mold,
9: Pressure medium, 12: Annular metal collar, 13: Heat-resistant diaphragm layer.

Claims (1)

[Claims] 1. An annular metal collar 12 provided at a position corresponding to the ends of the molds 7 and 8 of the cable connection portion, and a heat-resistant diaphragm layer 13 that covers the cable connection portion in the molds 7 and 8 including these metal collars 12. , for forming a cable connection part consisting of an annular packing member 5 disposed at the ends of the molds 7 and 8, and a presser arm 4 that elastically presses these packing members 5 toward the connection part side along the cable 1. Fluid seal structure of the mold.