JPS5923684B2 - Manufacturing method of half-split heat shrink tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a half-split heat shrinkable tube used for reconnecting connection portions of communication cables and power cables, for corrosion protection of steel pipes, and the like.

For reconnecting various cable connections and for corrosion protection of steel pipes, half-split heat shrink tubes are used, in which a portion of a cylinder is cut off in the axial direction.

As shown in Fig. 1, the conventional method for producing a half-split heat shrink tube is to crosslink a circular pipe 2 made of synthetic resin with two protrusions 1 on its outer circumferential surface using electron beam irradiation or a chemical crosslinking agent. After that, it is heated and expanded to expand its diameter as shown in Figure 2.
After this, the portion between the protrusions 1 was cut and opened.

The manufacturing method described above has many problems such as the complexity of the expansion method and the uniformity of the structure after expansion, and there is a strong desire for a manufacturing method that can be easily manufactured and that can yield products with uniform performance. is the current situation.

This invention was made in view of the above points, and it is possible to manufacture a tube by heating and stretching a crosslinked polyolefin sheet having protrusions on both sides, thereby making it possible to obtain a homogeneous tube by an easy method. The purpose is to provide a manufacturing method that can. Embodiments of the present invention will be described below with reference to FIGS. 3 to T. FIG. 3 shows the cross-sectional shape of the original sheet 11 before being stretched, and shows the sheet portion 12 to be stretched, the projections 13 provided on both sides of one side of the sheet portion 12, and the portion of the sheet portion 12. It consists of tongues 14 connected to the sides and is manufactured by profile extrusion or other methods.

The protrusions 13 on both sides become a fitting part after stretching, and the tongue part 14 is for maintaining airtightness of the fitting part, and since it is not stretched, it is formed somewhat thinner than the sheet part 12. There is.

The original sheet 11 is formed using crosslinked polyolefin.

Examples of the polyolefin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, crystalline polypropylene, EVA resin, PVC resin, EEA resin, and elastomer.

Of course, it also includes blends of multiple types of these and materials containing inorganic fillers such as carbon.

In addition, crosslinking methods include forming a flat base sheet and then crosslinking it by irradiating it with an electron beam, or crosslinking it when forming a flat base sheet using a chemical crosslinking agent. can.

In addition, the gel fraction of crosslinked polyolefin, that is, xylene 1
After 8 hours of reduction at 20℃? The weight percent of the solution part is about 30
-50% range is often used.

As shown in FIG. 4, the original sheet 11 as described above is held by pressing the protrusions 13 on both sides with the grips 15, and then heated to a stretching temperature, and the grips 15 are separated as shown by the arrows. Then, only the sheet portion 12 is stretched to the required stretching ratio.

Figure 5 shows the cross-sectional shape after being stretched in this way.As for the stretching conditions, the temperature can be either above or below the melting point or softening point of the polyolefin sheet, but it should be kept as constant as possible. The temperature must be precisely controlled within the temperature range.

A suitable temperature is 20 to 20 degrees higher than the melting point or softening point.
Stretching can be performed efficiently at a temperature 40°C higher. The stretching speed depends on the material, but is possible in the range of 100 mm/min to 5000 mm/min. Stretched sheet 1 obtained as above
6, a heat-curing adhesive 17 is uniformly applied to the entire surface of the side without the projections 13, and then, as shown in FIG. By abutting the outer surfaces of the two in a palm-shaped manner, the half-split mold K is used as a contraction tube 18. As a method of fixing the fitting portions of the protrusions 13 on both sides of the half-split type heat-shrinkable tube 18, as shown in FIG. The half-split type heat-shrinkable tube 18 attached to the cable A etc. in this manner is heated with a torch lamp or the like to heat-shrink it, thereby protecting the connection portion or the sheath repair portion. As described above, according to the present invention, a crosslinked polyolefin sheet provided with protrusions is heated and stretched by gripping the protrusions with a gripper, so that the sheet stretching operation can be performed extremely easily and unlike the conventional method. This eliminates the need for complicated expansion work, and since stretching is used, the homogeneity of the structure can be improved throughout.

[Brief explanation of the drawing]

Figure 1 is a front view of a circular pipe used in the conventional manufacturing method.
Figure 2 is a front view of the tube heated and expanded.
The figure is a front view of an original sheet used in the manufacturing method according to the present invention, FIG. 4 is a front view showing a state in which grips are set on the same, and FIG. 5 is a front view of a stretched sheet obtained by stretching the original sheet.
FIG. 6 is a cross-sectional view of the same as above used as a half-split type heat-shrinkable tube, and FIG. 7 is a front view of the same with the fitting portion of the tube fixed. 11... Original sheet, 12... Sheet part, 13... Protrusion, 14... Tongue piece part, 15... Grip , 16...Stretched sheet, 17...Hot melt adhesive, 18...
・Half-split type heat shrink tube.

Claims (1)

[Scope of Claims] 1. The above protrusion of a sheet made of crosslinked polyolefin is provided with bonding protrusions of the same size along both sides of the sheet, and has a tongue piece on the outside of one of the protrusions, Grasp with a grip, heat and stretch, then abut the sides of both protrusions with the protrusions on the outside in the shape of palms together,
A method for manufacturing a half-split heat shrinkable tube characterized by fixing it with a fixture. 2. The method for manufacturing a halved heat-shrinkable tube according to claim 1, wherein the heat-stretched sheet has a heat-melting adhesive applied to a surface opposite to the projections.