JPS602731B2 - Manufacturing method of cable with gas dam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cable with a gas dam, and in particular to a gas dam that prevents filler from flowing into the cable sections on both sides of the gas dam when forming the gas dam. This invention relates to an improvement in the manufacturing method of attached cables.

Generally, a gas dam part is formed by unraveling a cable core in a portion of the cable where the gas dam part is to be formed, and then filling the unraveled cable core and the cable parts on both sides with a resin filler.

The filler material forming the gas dam part is required to have low melting viscosity and good fluidity so as not to create gaps that serve as gas passages in the gas dam part, and it is also required that the filler material is not included in the material or rolled up during molding. After filling, the filling material is usually pressurized in order to expel the air and the like and completely fill the gap. However, when the filler is pressurized in this way, the filler flows into the cable sections on both sides of the gas dam, reducing the flexibility of the cable and also causing the cable to be exposed to vibrations when bent. When this happens, the cable tends to break due to the solidified resin filler, making it difficult to install the cable. Furthermore, when pulling out a branch line or distribution line from this gas dam, it is necessary to loosen the gas dam and the cable sections on both sides, but the resin that has flowed into the cable section makes it difficult to loosen the cable core, making it difficult to loosen the cable core. If you forcefully remove it, there is a risk that the insulation will be destroyed. Therefore, when forming the gas dam part, it is necessary to prevent the filler resin from flowing into the cable parts on both sides of the gas dam part. In the conventional technology, in order to prevent the resin from flowing into the cable section, a fluid of an appropriate viscosity is poured into the cable section on both sides of the section where the gas dam section is to be formed before filling the resin filler to form the gas dam section. A stopper was formed on the end face of the cable by press-fitting it into the cable and solidifying it. Epoxy resin or polyurethane resin is used as such flow-stopping fluid, but when this fluid is press-fitted, it leaks into the loosened cable core that is to form the gas dam part other than the cable section, and There is a tendency to deposit in or on the cable core. In this way, the flow stopper resin that has solidified inside the cable core or on the surface of the cable core that forms the gas dam section does not adhere to the resin filler that forms the gas dam section, creating gaps in the gas dam area and further preventing the flow stop. The end face of the solidified resin for gas dams gives a notch effect to the resin for gas dams, reducing the mechanical strength of the gas dam part. In addition, the injection level of the flow-stopping resin is not constant depending on the length of the cable core and the porosity, so it is difficult to control this. An object of the present invention is to provide a method for manufacturing a cable with a gas dam, which prevents the resin filler for gas dam from flowing into the cable portions on both sides of the gas dam portion through simple processing operations.

Embodiments of the present invention will be described in detail with reference to the drawings.
The figure shows a cable treated by the method of the present invention, in which the sheath la is stripped off at the part where the gas dam part is to be formed and the cable core lb is loosened, as shown in the figure.

Next, as shown in FIG. 2, the cut end faces 2a, 2 of the cable parts 2, 2' on both sides of the part where the gas dam part is to be formed are cut.
A plurality of spacers 10 for preventing the inflow of filler material are individually inserted into a large number of gaps 5 therein from 'a' to fill the gaps. In the illustrated embodiment, these spacers 10 are inserted into the gaps 5 between the units 3 of the cable core lb and between the units 3 and the core wrap 4, but they are also inserted into the gaps between the core wires in the units 3. You can. As shown in the figure, the gaps 5 have different cross-sectional areas between the units 3, between the units 3 and the core wrap 4, and within the unit. Alternatively, the length L may be selected from various dimensions depending on the type of cable and usage conditions (see FIG. 3A).
In order to prevent the insulation of the core wire from being damaged when inserting the spacer 10 into the gap 5, the tip on the insertion side is formed into a tapered part 10a, or a tapered part 10a with a rounded end is formed.
It is preferable to set it to 0b (see FIGS. 3A and 3B). The spacer 10 can be made of plastic materials such as polyethylene, nylon, polypropylene, polymethyl methacrylate, polystyrene, polycarbonate, or hardened paper impregnated with these plastic materials. It is preferable that the cable core has a Shore D hardness of 50 or more so that it will not break during insertion. A mold 12 is attached so as to surround the mold 1 and the cable portions 2 and 2' on both sides thereof, and a resin filler for gas dam is filled and pressurized through the injection port 12a by an inserter (not shown).

After solidification of the filler, the mold is removed to obtain a cable having a gas dam portion 14 as shown in FIG. In this way, before filling the resin filling material for gas dam, the cable part 2
, 2', the gas dam resin filler is inserted into the cable portions 2, 2'.
If it does, it does not flow into the cable, or even if it does, it only flows in a small amount, so it does not reduce the flexibility of the cable 10 or make it difficult to unravel the cable sections 2, 2' when pulling out the branch line. The following table shows specific examples according to the method of the present invention and comparative examples according to methods other than the present invention.

Note that in these examples, the cable consists of 8 units of 10 pairs, with one unit in the center and seven units around it, each insulated wire having a thickness of 0.4 to 0.
It had an outer diameter of 67 mm. The resin filler for the gas dam was polyurethane foam with a viscosity of 150 and PS (200C). Table Example Comparative example Material of base material Nylon 12
Shape of the hardness Shore D55 A: Outer diameter: 4, Length: 30 B: Outer diameter: 3, Length: 30
A 7 pieces 1 B 6 pieces Filling material inflow length
50 to 60 items 120 to 150 items From the above results, the method of the present invention requires very little filler to flow into the cable portion, so the flexibility and properties of the cable are maintained and there is no problem in its installation.

According to the present invention, as described above, the gas dam resin filler is spread into the cable portions on both sides of the gas dam by the filler inflow prevention filler inserts inserted into the numerous gaps in the cable portions on both sides where the gas dam is to be formed. Since it can prevent inflow, the flexibility of the cable will not be reduced, and the work of inserting this smoother into the cable part can avoid the disadvantages of conventional inflow prevention resin due to leakage, so it can improve mechanical strength. A large gas dam section can be obtained economically.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the method of the present invention, FIG. 2 is an enlarged cross-sectional view of one cable section, FIGS. 3A and B are side views of the subaper used in the present invention, and FIG. 4 is a diagram of the present invention. It is a side view showing a part of cable with a gas dam manufactured by the method in section. 1...cable, la...sheath, lb...cable core, 2, 2'...cable part, 2a, 2'a...
Cut end surface, 10...Subasa, 10a, 10b...
...Boopa part, 12...mold, 14...gas dam part. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. After peeling off the sheath of the portion of the cable where the gas dam portion is to be formed and loosening the cable core, a resin filler is filled across the loosened cable core and the cable portions on both sides thereof. In the method for manufacturing a cable with a gas dam, before filling the resin filler, a plurality of spacers for preventing the inflow of filler are individually inserted into a number of gaps inside the cut end surfaces of the cable portions on both sides. A manufacturing method for cables with gas dams. 2. The method of manufacturing a cable with a gas dam according to claim 1, wherein the spacer has a tapered portion at the tip on the insertion side. 3. The method of manufacturing a cable with a gas dam according to claim 2, wherein the tapered portion has a rounded end. 4. The method of manufacturing a cable with a gas dam according to any one of claims 1 to 3, wherein the spacer is made of a plastic material. 5. The method of manufacturing a cable with a gas dam according to any one of claims 1 to 3, wherein the spacer is made of paper impregnated with a plastic material. 6. The method of manufacturing a cable with a gas dam according to any one of claims 1 to 5, wherein the gaps into which the spacers are inserted are between the units of the cable core and between the units and the core wrap. 7. The method of manufacturing a cable with a gas dam according to any one of claims 1 to 6, wherein the gap into which the spacer is inserted is within a unit of a cable core. 8. The method for manufacturing a cable with a gas dam according to any one of claims 1 to 7, wherein the spacer has a hardness of Shore D50 or more.