JP2505155B2 - Manufacturing method of cable with water shield - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method of manufacturing a cable with water shield.

[Technical background of the invention and its problems] As shown in FIG. 5, the water-blocking tape 1 comprises an adhesive layer 2 for a sheath, a lead foil layer 3, a polyester layer (PET layer) 4, and a semiconductive layer 5 which are laminated in this order. Is configured. When manufacturing a cable with water shield, it is vertically attached to the cable core 6 with the anti-sheath adhesive layer 2 on the outer periphery as shown in FIG. 4, and heat is welded between the lap portions of the water shield tape to block water. There are layers. That is, the lap portion of the water blocking tape 1 is opened between the two forming dies which are in charge of forming during vertical addition, and the hot jet 7 is blown into this opening to blow hot air over the lap portion of the water blocking tape 1. The semiconductive layer 5 of the tape (upper tape) and the anti-sheath adhesive layer 2 of the lower tape (lower tape) are heated to thermally weld them.

In the above-mentioned conventional manufacturing method, since the heat capacity of the hot air as the heating source is small, it takes a considerable time to raise the temperature until the welding is completed, thereby limiting the line speed. There was a drawback. Although the above problem can be solved by adding more hot jets, the number of hot jets installed is limited. In addition, if the number of hot dies is increased, the interval between the forming dies becomes large, and the so-called bulge is likely to be raised in the lap portion.

In addition, the width of the lap portion of water-impervious cables is set to 20 mm for all sizes of cables, and for small-sized cables, the lap portion must be opened too large and the depth of the lap portion is limited due to the curvature. There was a drawback that hot air could not reach and the welding inside the lap was insufficient. However,
If the opening of the lap portion is wide, there is a possibility that burrs may occur as described above.

Furthermore, when the water-blocking tape or cable core is at a low temperature in winter or the like, heat may be taken by the lead foil layer of the cable core or water-blocking tape, and the temperature rise of the welded part may not be sufficient, resulting in defective welding. .

Further, since it is difficult to control the volume of hot air as a heating source, it is difficult to perform optimum heating and it is almost impossible to obtain a constant welded state with good reproducibility.

In order to solve the above-mentioned problems of hot air heating and welding by a hot jet, the present applicant applies a high frequency to a lap portion by a high frequency heating coil to simultaneously solve the above problems of the hot air heating welding, and thus the lead in the water shielding tape is applied. We have developed a method of manufacturing a waterproof cable that heats the foil layer and heat-bonds the lap portion.

The outline of the invention disclosed above is as follows.

That is, FIG. 6 in which the same parts as those in FIGS. 4 and 5 are designated by the same reference numerals shows an embodiment of the invention. In this figure, the water-blocking tape 1 is vertically attached to the cable core 6.
The high frequency heating coil 8 is opposed to the lap portion of the. When a high frequency is applied to the high frequency heating coil, the lead foil layers of the upper tape and the lower tape are heated by the high frequency, and this heat heats the semiconductive layer 5 of the upper tape and the anti-sheath adhesive layer 2 of the lower tape. It is heated and heat welding is performed between the two.

In the above-described method of manufacturing a water-impervious cable, the lead foil layer is heated by high-frequency heating without using a hot jet, thereby heating the welded portion, so that the temperature of the welded portion is sufficiently raised. Therefore, good heat welding is performed.

However, since the upper tape of the lap portion is close to the high frequency heating coil, the heat generation is larger than that of the lower tape and the temperature rises more quickly. Therefore, if the high-frequency power applied to the high-frequency heating coil is increased and the lower tape is also heated to a high temperature so that sufficient heat welding can be obtained, the upper tape can be turned up to be close to the high-frequency heating coil, There is a possibility that the temperature is abnormally increased and melted due to strong influence of high frequency.

In the invention of the above-mentioned disclosure, in order to solve the above-mentioned problems, temporary welding is carried out by a hot jet heater, and then heat welding is carried out by high-frequency heating. Even if a hot jet is used for temporary fixing, it does not cause the above-mentioned problems due to the use of the hot jet because it is the heat welding of a small part of the lap portion, but it takes two steps for the hot welding. For example, it is preferable that thermal welding is performed only by high frequency heating.

[Object of the Invention] The present invention has been made based on the above circumstances, and is a method of manufacturing a waterproof cable with which the lap portion of the waterproof tape can be heat-welded only by high-frequency heating without temporary fixing by a hot jet. The purpose is to get.

[Summary of the Invention] A method of manufacturing a waterproof cable according to the present invention is provided between a first forming die for vertically adding a waterproof tape to a running cable and a press roll for molding the vertically mounted waterproof tape. To
The first high-frequency heating coil having an elongated U-shaped coil wire is arranged such that the longitudinal direction of the coil wire is parallel to the cable running direction, and the second forming die is arranged next to the second forming die and corresponding thereto. A second high-frequency heating coil having the same coil wire as that described above between the pressing roll and the pressing roll is arranged with the longitudinal direction of the coil wire being inclined with respect to the cable traveling direction, and both high-frequency heating coils form a waterproof tape. By applying a high frequency and heat generation of the metal layer such as lead foil constituting the water shielding tape, the first high frequency heating coil temporarily fixes the lap portion of the water shielding tape, and the second high frequency heating coil temporarily fixes the entire lap portion. It is characterized in that heat welding is performed.

[Embodiment of the Invention] FIG. 1 is a plan view of an embodiment of the present invention, and FIG.
A sectional view taken along line II and FIG. 3 are sectional views taken along line III-III. In these figures, the cable 11 incoming side forming die 12 and the next forming side die 13
A high-frequency heating coil 14 having an elongated U-shaped coil wire 14a is provided between and, with the longitudinal direction of the coil wire 14a aligned with the running direction of the cable 11. Also, between the forming die 13 and the presser roll 15 at the final stage,
The high frequency heating coil 16 is provided by inclining the longitudinal direction of the coil wire 16a with respect to the traveling direction of the cable 11.
Reference numeral 17 in the figure denotes a pressing roll that exits the forming die 12 and presses the water-blocking tape 18 that is heat-welded by the high-frequency heating coil 14.

In the present invention, the high-frequency heating coil 14 is attached to the water-blocking tape 18 vertically attached to the cable core with the forming die 12.
When a high frequency is applied by the eddy current, an eddy current is generated in the metal layer such as aluminum foil or lead foil in the waterproof tape, and the metal layer is heated,
As a result, the temperature of the lap portion of the water blocking tape rises and heat welding is performed. However, the generation of eddy current and the heating due to it are limited only to directly under the coil wire, and the heat welding is performed in the form of two lines parallel to the cable axis line (indicated by the black dots in FIG. 2). The upper tape and the lower tape are fixed and temporarily fixed.The cable with the lap portion heat-welded linearly as described above is molded by the press roll 17 and the forming die 13 and is inclined with respect to the cable axis. A high frequency is applied by the high frequency heating coil 16 arranged in a vertical direction.This high frequency is applied to the entire lap portion because the coil wire 16a is inclined with respect to the cable traveling direction, and the heat generation of the metal layer does not occur. The entire width of the lap portion is welded and the entire lap portion is heat-welded satisfactorily (thick line in FIG. 3). Koi 16 and the upper tape are not very close to each other, the upper tape is heated almost in the same way, and even if the temperature is raised to obtain sufficient heat welding, the upper tape is turned over or the temperature is abnormal. In order to prevent the above-mentioned upper tape from overheating and curling, it is desirable that temporary fixing be made near the opening of the lap portion as much as possible.

[Effects of the Invention] As is apparent from the above, according to the manufacturing method of the present invention, heat generation of a metal layer such as a lead foil due to application of high frequency is applied to a water-impervious tape lap portion by heat generation without applying heat welding by hot air heating of a hot jet. Since heat welding is performed, the heat capacity of the heating source is sufficient, and the temperature of the lap portion can be raised to the temperature required for heat welding in a short time, so that the line speed can be increased. Furthermore, first, temporary fixing is performed with a high-frequency heating coil in which the longitudinal direction of the coil wire is parallel to the cable axis, and then the high-frequency heating coil whose longitudinal direction is inclined with respect to the cable axis heats the entire width of the lap portion. Since the welding is performed, the upper tape is not overheated, melted, or turned over, and good thermal welding is performed.

Also, if you add more hot jets to shorten the heating time, the spacing between the forming dies will increase,
Although blister tends to occur, in the present invention, since the high frequency power applied to the heating coil only needs to be increased, the above problem does not occur.

Furthermore, since heating is performed without opening the lap portion, insufficient heat welding or burring does not occur even when the cable size is small.

Further, since heat is applied for heat welding by heat generation of the metal layer due to application of high frequency, sufficient heating is performed to prevent welding defects even when the water-blocking tape, cable core, etc. are at a low temperature. It never happens.

Further, unlike the conventional hot air that is a heating source, the control of the high-frequency heating coil is easy, so that optimum heating can be performed as necessary and a constant welded state can be obtained with good reproducibility.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is its II-II.
A horizontal cross-sectional view, FIG. 3 is a horizontal cross-sectional view in III-III thereof, FIG. 4 is a cross-sectional view showing a conventional manufacturing method, FIG. 5 is an enlarged view of a part thereof, and FIG. It is a cross-sectional view explaining the manufacturing method of the waterproof cable with heating. 1 …… Water-blocking tape, 1a …… Lap part 2 …… Sheath adhesive layer 3 …… Lead foil layer, 4 …… PET layer 5 …… Semiconductive layer, 6 …… Cable core 7 …… Hot jet 11 …… Cables 12, 13 …… Forming dies 14,16 …… High frequency heating coils 14a, 16a …… Heating coil wires 15,18 …… Presser roll

Claims (1)

(57) [Claims] 1. An elongated U-shaped coil wire is provided between a first forming die that vertically attaches a water blocking tape to a running cable and a holding roll that forms the vertically attached water blocking tape. The first high-frequency heating coil is arranged with the longitudinal direction of the coil wire parallel to the cable traveling direction, and the same as described above between the second forming die arranged next and the corresponding press roll. Second having a coil wire of
The high-frequency heating coil is arranged such that the longitudinal direction of the coil wire is inclined with respect to the cable traveling direction, and high-frequency waves are applied to the water-blocking tape by both high-frequency heating coils to form a water-blocking layer in the water-blocking tape. The first high-frequency heating coil temporarily fixes the lap portion of the water blocking tape by the heat generated by
A method for manufacturing a water impervious cable, characterized in that the whole of the lap portion is heat-welded by the high frequency heating coil.