JPH074041B2 - Molding method for oil-tight mold such as cable end connection - Google Patents

Description

TECHNICAL FIELD The present invention relates to a molding method for an oil-tight molded portion of a terminal portion such as a crosslinked polyethylene insulated vinyl sheath cable (hereinafter referred to as a CV cable).

[Problems to be solved by conventional technology and invention]

Molding of the oil-tight insulation such as the terminal part of the conventional ultra-high voltage CV cable is performed by winding the tape-shaped molding material 2 around the step-stripped part of the CV cable 4 as shown in Fig. When the oil-tight fitting 1 is fixed, the oil-tight metal fitting 1 is fixed at a predetermined position, the molding material 2 is rolled up to a predetermined position to form a predetermined shape, and a holding tape or the like is reinforced. A heater 6 for heating such as the above is attached and electrically heated, and the molding material 2 is subjected to external heating to be added or cross-linked to be molded.

In such a conventional method, since the molding material 2 has a tape shape, it takes a long time to wind the molding material 2 and a long working time. Further, since the heater 6 for heating is used to heat from the outside of the mold material 2, it is not possible to work at a high temperature, so that it takes a long time to mold, and a large structure has a thick mold part, which causes The tape becomes in a molten state, the oil-tight metal fitting 1 moves, the molten tape flows inside, the internal space capacity becomes small, and the expansion of the cable insulator at the time of temperature rise is hindered, which may cause deformation of the cable. Was there.

[Means and Actions for Solving Problems]

The present invention has been made to solve the above-mentioned problems of the prior art, and the method of molding the oil-tight mold is such that the thickness of the molding material filled in the substantially conical cylindrical filling chamber is A pre-mold unit with a substantially conical cylinder shape in which embedding metal fittings are radially embedded at a position roughly bisected is provided around the cable to bond the minimum inner diameter portion of the pre-mold unit to the outer peripheral surface of the cable, and The part that gradually expands from the smallest inner diameter part to a substantially conical cylinder shape is made to rise with a substantially uniform thickness, and while maintaining this state, a high-frequency induction heating coil is placed outside the pre-mold unit. By heating the embedded metal fittings inside by high-frequency induction, the outer and inner halves of the molding material in the pre-mold unit have approximately the same thickness. And as a way to heat molded simultaneously from internal to each.

As described above, heating the outer half and the inner half of the mold material of the oil-tight mold part at the same thickness from the inside simultaneously, the time required for heating is substantially half the thickness of the mold material. Therefore, the heating time can be improved, and the time required for adding or crosslinking the molding material can be greatly shortened.

In addition, if a temperature sensor for temperature control is attached to a part of the embedded metal fitting in the pre-mold unit and heating is performed while controlling the temperature, the control becomes easy.

〔Example〕

An embodiment of the method for molding the oil-tight mold portion of the present invention will be described with reference to FIGS. 1 to 3. In the conventional example described above, the molding material 2 formed in the shape of a tape was wound around the cable and formed into a predetermined shape, which was then molded. In this embodiment, the molding material 2 shown in FIG. It uses a pre-molding unit preformed using a mold.

That is, the pre-molded unit has the cable 4 at its center.
It is formed by using a mold mainly having a substantially conical cylindrical filling chamber 12 having a hole 11 through which the oil-tight metal fitting 1 is supported in the central portion and a mold material is filled in the periphery. . A large number of metal plates (metal fittings) 3 for embedding are radially arranged and held in the filling chamber 12. The metal plate 3 for embedding is embedded in the mold material at a position approximately bisected in the thickness direction when the mold chamber is filled with the mold material, and the mold material is induction-heated. It becomes a heating element when doing. Therefore, the embedded metal fitting 3 is a metal whose heat generation can be ignored at a commercial frequency, and may be made of a metal material such as stainless steel, aluminum, or a copper alloy that generates heat by high frequency induction.

FIG. 1 shows a state in which a substantially conical premolding unit molded by the mold shown in FIG. 3 is provided at a predetermined position on the CV cable 4 and the molding material 2 is filled in the filling chamber 12. There is. That is, the stripped CV cable 4
The minimum inner diameter portion of the pre-mold unit is adhered to the upper predetermined position by the adhesive 9 and temporarily fixed. Then, the chamber 12 is set again on the circumference of the pre-mold unit, that is, the molding material 2. This is because, when the molding material 2 is heated to be flown and crosslinked, the pre-molding, particularly the portion that expands from the minimum inner diameter portion of the molding material to a substantially conical cylindrical shape and rises, does not flow and lose its shape. . A heating wire 6 as an auxiliary heat source is wound around the outer circumference of the chamber 12 and connected to an external power supply device (not shown). Further, a coil 5 for high frequency induction induction heating is arranged outside the heating wire 6 and connected to a high frequency heating device (not shown).

When the high-frequency heating device and the external power supply device are turned on in this state, the molding material 2 is heated by the heating wire 6 as an auxiliary heat source and the heat generated in the embedded metal fitting 3 by high-frequency induction by the high-frequency induction heating coil 5. The fluidization or cross-linking is promoted, and the CV cable 6 is bonded and integrated to be molded. At this time, temperature control is performed by a temperature sensor 7 attached to a part of the embedded metal fitting 3, and heating control is performed so that the molding material 2 can be easily molded.

Due to the above-mentioned heating, particularly the heat generated by the embedded metal fitting 3, the outer half and the inner half of the mold material 2 in the pre-molding unit are substantially simultaneously heated from the inside, and thus the mold material is added or The time required for crosslinking can be greatly reduced.

The heating wire 6 is used to supplement the shortage of heat from the embedded metal fitting 3 for heat generation from the outside.

Therefore, conventionally, a tape of a molding material is wound into a predetermined shape to form an oil-tight mold portion, but it can be formed in a short time, and mainly by heating from the inside center to the inside and outside of the molding material. Therefore, the molding time can be significantly reduced. Further, it is not necessary to sufficiently provide a reinforcing material for moving the tape, and the working time can be greatly shortened.

〔The invention's effect〕

As described above, in the present invention, when heating the oil-tight mold part or the like, the heating element by high frequency induction is previously provided in the mold material of the pre-mold unit, so that the molding work is extremely short. Can be done in time. Moreover, the pre-mold unit is a unit having a substantially conical cylindrical shape in which the embedding metal fittings are radially embedded at a position that roughly divides the thickness of the molding material filled in the substantially conical cylindrical filling chamber into a cable. The minimum inner diameter portion of the premold unit is bonded to the outer peripheral surface of the cable by surrounding it, and the portion gradually expanding from the minimum inner diameter portion of the premold unit into a substantially conical cylindrical shape is raised with a substantially uniform thickness. In this way, while maintaining this state, the embedded metal fitting in the pre-mold unit is heated by high-frequency induction from the outside, so that the outer half and the inner half of the molding material in the pre-mold unit have substantially the same wall thickness, respectively. However, since the molding is performed by simultaneously heating from the inside, the time required for heating can be applied to substantially half the thickness of the molding material. It may be the time, vulcanization or crosslinking time by heating can be further shortened, with it, it can significantly reduce the molding time required.

Therefore, not only is the performance of the mold part stabilized, and extremely excellent effects such as the simplification of the molding work and the shortening of the work time at the site can be obtained, but the molding of the oil-tight mold part can be performed in a prescribed shape. The quality is improved because it is done accurately together.

[Brief description of drawings]

FIG. 1 shows an embodiment of a method for molding an oil-tight mold part of the present invention, and is a cross-sectional view showing a state of molding the oil-tight mold part. FIG. 2 is a line II-II in FIG. FIG. 3 is a sectional view taken along the line, FIG. 3 is a sectional view of a mold used for molding the premolding unit used in the molding method of the present invention, and FIG. It is sectional drawing shown. In the reference numeral, 2 is a molding material (premolding unit), 3 is an embedded metal fitting, 4 is a cable, 5 is a high frequency induction coil, and 7 is a temperature sensor.

Claims (2)

[Claims] 1. A method of molding an oil-tight molded part such as a plastic insulated cable, in which an embedding metal fitting is radially embedded at a position approximately dividing a thickness of a molding material filled in a substantially conical cylindrical filling chamber. A pre-molded unit with a substantially conical cylinder shape is provided around the cable to bond the smallest inner diameter part of the pre-molded unit to the outer peripheral surface of the cable, and gradually expand from the smallest inner diameter part of the pre-molded unit into a substantially conical cylinder shape. The part to be heated is made to rise with a substantially uniform thickness, and while maintaining this state, a coil for high frequency induction heating is placed outside the premold unit to heat the embedded metal fitting in the premold unit by high frequency induction. This allows the inner half of each of the outer and inner halves of the molding material in the pre-molding unit to be approximately the same thickness. A method for molding an oil-tight molded part such as a cable end connection part, which is characterized in that the molded product is heated at the same time and molded. 2. The cable according to claim 1, wherein a temperature sensor for temperature control is attached to a part of the embedded metal fitting in the premold unit to heat while controlling the temperature. Molding method for oil-tight molded parts such as terminal connection parts.