JPS6315902B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-shrinkable branch molded product used for waterproofing the branch connection portion of a power cable, and in particular to a method for manufacturing a molded product that can shrink only in the radial direction when heated. be.

When separating two-phase, three-phase or more phase cables in power cable terminal processing, it is necessary to prevent water from entering the cables after the sheath is stripped off.

For this reason, a Y-branch pipe (two-pronged branch pipe), a three-pronged branch pipe, or the like is placed over the branch part of the cable, and then the end of the branch pipe is wrapped with tape to perform waterproofing.

Conventionally, rubber molded products have been used for the branch pipes mentioned above, but there are problems such as having to make a rubber molded product for each cable size and having no waterproof effect unless the ends are sealed with tape. There were problems in terms of cost and work efficiency.

In addition, when branching a main line into several lines, the size of the main line and the size of the branch lines are not necessarily fixed and vary, so the number of types of molded products will increase, and it will be necessary to use not only power cables but also communication cables. The same can be said about cables.

Recently, there have been advantages such as improving work efficiency and omitting tape wrapping work, and even if the cable size is slightly different regardless of whether it is a main line or a branch line, many sizes can be covered with a single molded product. Because of this, heat-shrinkable tube molded products have come to be used for terminal processing, branch line processing from main lines, etc.

Normally, the conventional method for manufacturing heat-shrinkable tubes as described above is to introduce pressurized air or liquid into a molded product placed in a suitable outer mold, and then expand it using liquid pressure. .

However, with the above method, not only the diameter of the thick tube and the diameter of the branched thin tube of the molded product but also the arrangement are constant, and if any of them is changed, a new outer mold is required. Since it requires manufacturing and is expanded using fluid pressure, there are problems such as the accuracy of the wall thickness of the original molded product having a large effect on the wall thickness of the product.

In addition to the above-mentioned stretching method using fluid pressure, molded products can also be produced by covering guide wires arranged in a circle with a molded product and expanding the group of guide wires with wedge-shaped extensions. A method has been proposed in which the pipe is expanded only in the radial direction, but this method can only be applied to straight molded products with equal diameters at both ends, and cannot be used for molded products with different diameters at both ends used as branch pipes cannot be extended.

This invention was made in view of the above points, and provides a heat-shrinkable molded product for branch pipes that shrinks only in the radial direction by mechanically stretching a molded product whose ends have different diameters. The purpose of the present invention is to provide a method that allows for extremely simple manufacturing.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The expansion jig 2 used to produce the heat-shrinkable branched molded product A by stretching the thermoplastic synthetic resin branched molded product 1 in the radial direction includes a plurality of guide linear body groups 3 as shown in FIG. and a wedge-shaped extension 4 inserted into each linear body group 3.

The guide linear body group 3 includes a pair of linear bodies 3
Prepare a and 3a', 3b and 3b', and 3c and 3c',
As shown in FIG. 7, these linear bodies are arranged so as to be equally spaced and parallel to each other on the same circumference, and one end of these linear bodies is attached to the fixed support 5, and the other The end portions are assembled on the arrangement axis of the linear body and fixed in a bundle, forming a free end 6 that can be freely bent only as a collection.

Each of the linear bodies is made of a material having enough rigidity and thickness to stand up vertically within a required length range, such as piano wire or steel rod.

Linear bodies 3a to 3 in each guiding linear body group 3
There are two types of attachment of c' to the fixed support 5: a movable structure and a fixed structure.
There are two choices available: a case where a movable structure is employed, and a case where a combination of a movable structure and a fixed structure is employed.

As shown in FIG. 4, the movable structure is constructed by inserting the ends of each of the linear bodies 3a to 3c' from one side into a circular opening 7 provided in the fixed support 5, and inserting the ends of the linear bodies 3a to 3c' into the other side of the fixed support 5. The ends of each of the protruding linear bodies 3a to 3c' are bent outward, and the bent ends are fixed to the retaining ring 8, so that the guide linear body group 3 does not move toward the free end 6. They can move freely to the other side.

The fixing structure includes a fixing support 5 as shown in FIG.
A number of small holes 9 equal to the number of linear bodies 3a to 3c' are provided at regular intervals around the opening 7, and the ends of the linear bodies 3a to 3c' inserted into the opening 7 from one side are bent. This bent end is inserted into each small hole 9 and fixed.

Whether the guiding linear body group 3 has a movable structure or a fixed structure, the linear bodies 3a to 3c' are arranged in a substantially circular cross section corresponding to the circular shape of the opening 7. The movable structure allows the insertion of the molded product 1 into the guiding linear body group 3, as will be described later, without significantly bending the linear body group 3.

The extension 4 is formed into a conical shape, and has a guide groove 10 in which the linear bodies 3a to 3c' are fitted in the axial direction of the outer peripheral surface.
are provided in a number equal to the number of linear bodies.

A cable 11 is connected to the extension 4 and inserted into the guide wire group 3 through the opening 7 with the tip facing toward the free end 6, and is inserted into each guide groove 1.
0 is slidably fitted into the linear bodies 3a to 3c' so that it is surrounded by the linear bodies 3a to 3c'.

The extension 4 has a diameter that allows the maximum diameter portion to pass through the aperture 7 and expands the linear bodies 3a to 3c' to such an extent that they become parallel.

In the illustrated embodiment, one extension is used, but a plurality of extensions with different diameters are used, and each extension is connected in order, starting with the one with the smallest diameter.
It is also possible to insert it into c' and spread it out in stages.

As shown in FIGS. 5 to 7, the expansion jig 2 is attached to the fixed support 5 in an arrangement that matches the shape of the molded product 1 so that multiple sets do not overlap each other.

The molded product 1 shown in FIG. 5 is a bifurcated product having a thick tube 1a at one end and two thin tubes 1b branching from the thick tube 1a at the other end. For molded product 1,
Two sets of expansion jigs 2 are used.

That is, the number of expansion jigs 2 is determined by the number of thin tubes 1b, and three sets of expansion jigs are used in a three-pronged molded product.

The mounting interval of each expansion jig 2 to the fixed support 5 is as follows:
As shown in FIG. 6, the thin tubes A 2 are installed so as to be equal to the axial spacing of the thin tubes A ₂ in the heat-shrinkable branched molded product A after stretching. Therefore, the molded product 1 before stretching is inserted into each expansion jig 2. When doing so, the linear body 3a
3c' to 3c' may be bent and inserted into the thin tube 1b.

First, as shown in FIG. 5, insert the molded product 1 into the guide wire group 3 from the free end 6 side so that the thin tubes 1b of the molded product 1 pass through each guide wire group 3 one by one. The thick tube 1a is inserted to a position where a gap 12 is maintained between the end of the tube 1a and the fixed support 5. Note that, in order to simplify the drawings, FIGS. 3 to 6 only show the pair of linear bodies 3a and 3a'.

Next, an extension 4 is inserted into the interval portion 12 of each guiding linear body group 3, and the extension 4 is guided to the free end 6 side via the cable 11 by the linear bodies 3a to 3c'. index at a predetermined speed while simultaneously sliding as shown by arrow X in FIG.

At this time, the molded product 1 is heated to a temperature above its softening temperature by a heating means such as a hot air device (indicated by arrow Y in FIG. 6), which is provided to move in the same direction in synchronization with the extension 4. Moreover, the temperature condition is kept below the melting temperature.

If all the extensions 4 are moved in the same direction at the same time in this state, the free end 6 side of each guiding linear body group 3 will be sequentially pushed out as shown in FIG. The thick tube 1a of the molded product 1 heated to a temperature condition is first expanded.

As the extension 4 advances further, it enters the inside of the next thin tube 1b, and the thin tube 1b is expanded for each jig via the linear bodies 3a to 3c'.

Since the expansion jigs 2 of each expansion jig 2 move simultaneously at the same speed, the thick tube 1a and the subsequent thin tube 1b are expanded in the radial direction continuously.

That is, the thick tubes 1a are expanded by the same number of expansion jigs 2 as the number of thin tubes 1b,
After the thick tube 1a has been expanded, the thin tube 1b is simultaneously expanded by a separate expansion jig 2.

The expansion ends when the extensions 4 pass the entire length of the narrow tube 1b, and cooling means such as a cold air device (indicated by arrow Z in FIG. 6) moves in the same direction in synchronization with each extension 4. When the molded product is cooled and solidified, a heat-shrinkable branched molded product A in which both the thick tube A and the thin tube _A2 are expanded is completed.

As described above, according to the present invention, there is provided a guiding linear body group in which one or more pairs of linear bodies are attached to a fixed support;
An expansion jig is formed with an extension inserted into the inside of this linear body group, two or more sets of expansion jigs are arranged so as not to overlap, and a molded product with a thin tube inserted into each linear body group is formed as an expansion jig. Since the thick tube and thin tube are made to expand continuously in the radial direction by simultaneously moving the In the terminal processing of power cables, branch molded products used for branch connection parts can be formed from heat-shrinkable tubes.

According to this method, the shrinkage rate is different between the thicker diameter part and the thinner part of one heat-shrinkable tube, and at the branched part, a product with a different shrinkage rate depending on the diameter can be obtained in one step, and the expansion The shrinkage rate of the branched portion can also be adjusted by changing the diameter of the tip.

In addition, by appropriately combining expansion jigs, it is possible to easily respond not only to changes in diameter but also to the number of branches, without having to create a new outer mold as in the past for branch molded products with various conditions. It is possible to reduce the cost required for equipment.

Furthermore, since the thick tube and thin tube of the molded product are expanded only in the radial direction by pushing out the linear body by moving the extension, the molded product is mechanically stretched, which reduces the wall thickness of the molded product. Variations have little effect on the wall thickness of heat-shrinkable branched molded products.

In addition, we used a rigidity and thickness that allows the guiding linear body to stand up vertically, so when a molded product to be expanded is inserted into several groups of guiding linear bodies, the guiding linear body will not move inward to the extreme. This eliminates the inconvenience of not being able to insert an extension because the file is crooked.

Moreover, since the free ends of the guide wires are collectively bundled, the wires will not come apart or expand unevenly in the radial direction when inserting the extension, and the guide wires will not become loose or expand unevenly in the radial direction. Since the part or all of the part can move only in the direction opposite to the free end with respect to the fixed support, there is no need to forcibly bend the guide linear body when inserting the molded product, and a more uniform This has the effect of making expansion possible.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a guiding linear body group used in the method of the present invention, Fig. 2 is a perspective view of an extension incorporated into the same, and Fig. 3 is a fixed attachment structure of the guiding linear body group. 4 is an enlarged sectional view showing the movable mounting structure, FIG. 5 is a vertical side view showing the molded product set in the expansion jig, and FIG. 6 is a vertical side view showing the expanded state of the same. FIG. 7 is an enlarged cross-sectional view taken along the line--in FIG. 5. 1... Molded product, 1a... Thick tube, 1b...
... Thin tube, 2 ... Expansion jig, 3 ... Guide linear body group, 3a, 3b, 3c, 3a', 3b', 3
c'... Linear body, 4... Extension, 5... Fixed support, 6... Free end, 7... Opening, 10... Guide groove, 11... Cable, 12... Spacing portion, A...Heat-shrinkable branched molded product.

Claims (1)

[Scope of Claims] 1. One or more ends of a pair or more of guiding linear bodies having sufficient rigidity and thickness to stand up vertically within a necessary length range are attached to a fixed support, and each guiding line is The other end of the shaped body has a group of guiding linear bodies that are assembled and fixed to form a free end that can be bent freely only as a group, and fitting grooves for the guiding linear bodies at opposing positions across the axis. , forming an expansion jig with at least one wedge-shaped extension inserted into the group of guiding linear bodies from the fixed support side, and arranging at least two or more sets of the expansion jig so as not to overlap each other; One end is a thick tube, the other end is branched from that single tube, and the synthetic resin molded product has at least two thin tubes, each of which is expanded one by one. Insert the large-diameter tube into the guiding wire group of the jig from the large-diameter tube side so as to maintain the predetermined gap between the end of the large-diameter tube and the fixed support, and then insert the extension into its wedge-shaped cross section. Insert the fitting grooves into the respective guide wires within the spacing of each expansion jig, with the tip of the expansion jig facing toward the gathering free end side, and then insert all the expansion While heating the molded product at a predetermined temperature with the molded product in contact with the inner wall surface of the molded product, the extension is guided by the guiding linear body in the direction away from the fixed support in the axial direction within the molded product. A method for producing a heat-shrinkable branched molded product, characterized by simultaneously sliding the thick tube and the next thinner tube of the molded product only in the radial direction. 2. A part or all of the guide linear body group is configured such that the part attached to the fixed support does not move in the direction of the free end, but can freely move in the opposite direction to the free end. A method for producing a heat-shrinkable branched molded product according to claim 1.