JP4172990B2 - Plastic pipe tensioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plastic pipe tensioning tool used when a small diameter plastic pipe is drawn into a large diameter pipe or duct.
[0002]
[Prior art]
As a method of laying an optical fiber cable, a method of laying a large-diameter pipe first, drawing a small-diameter plastic tube (conduit) into it, and drawing the optical fiber cable into the plastic tube is a method. It is known. In this construction method, when a plastic tube is pulled into the pipe, a pulling tool is attached to the tip of the plastic tube, and the pulling tool is pulled with a wire to pull the plastic tube. The pulling tool used here has a taper screw portion that is screwed and fixed to the end portion of the plastic tube on the rear end side, and has a wire connecting portion on the tip portion.
[0003]
[Problems to be solved by the invention]
However, since the conventional plastic pipe tensioner is entirely made of metal (steel), a large number of plastic pipes 12 are already in the large-diameter pipe 10 as shown in FIG. 6 (some may be cables). If the plastic pipe 12a is newly drawn into the remaining narrow space, the tension tool rubs strongly against the existing plastic pipe 12, which may damage the existing plastic pipe.
[0004]
An object of the present invention is to provide a plastic tube tensioner that is less likely to damage an existing plastic tube or cable even if it contacts an existing plastic tube or cable.
[0005]
[Means for Solving the Problems]
The plastic tensioner according to the present invention is a screwed member in which a spanner hook is integrally formed on the large-diameter end side of a tapered threaded portion that is screwed and fixed to an end of a plastic tube,
An intermediate block connected to the spanner hanging portion side of the screw member so as to be relatively rotatable on the same axis as the screw member;
A wire connecting portion provided on the tip side of the intermediate block;
A plastic cap that covers the outer periphery from the shoulder portion of the intermediate block to the spanner hanging portion of the screwed member and has an opening of a size that allows the wire connecting portion to pass through at the tip;
The cap is arranged on the same axis as the screwed member by an intermediate block, the outer diameter of the front end portion is smaller than the rear end portion, and the outer diameter of the rear end portion is the tapered screw portion. It is formed to be the same as or larger than the outer diameter of the end of the plastic tube into which
It is characterized by this.
[0006]
In the plastic tube tensioner according to the present invention, an axial hole is formed in the screw member in the axial direction, and a shaft bar penetrating the shaft hole is provided at a rear end of the intermediate block. It is preferable that a rear end block for preventing the screwing member from being pulled out is provided, and the screwing member and the intermediate block are connected so as to be relatively rotatable on the same axis.
[0007]
In the plastic tensioner according to the present invention, it is preferable that the rear end block is provided with a connecting portion of a nominal line inserted into the plastic tube.
[0008]
The plastic tensioner according to the present invention includes a small-diameter male screw formed at the rear end of the wire connecting portion, with a large-diameter male screw portion formed at the tip of the shaft rod screwed into a large-diameter female screw portion formed at the intermediate block. The portion is screwed into a small-diameter female screw portion formed at the tip of the shaft rod, and the screw pitch of the large-diameter male screw portion and the large-diameter female screw portion is different from the screw pitch of the small-diameter male screw portion and the small-diameter female screw portion, It can be set as the structure currently fixed so that a wire connection part and an intermediate block cannot rotate relatively.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a plastic tensioner according to the present invention. In the figure, 20 is a screw member, 22 is an intermediate block, 24 is a wire connecting member, 26 is a shaft rod, and 28 is a cap. The cap 28 is made of plastic, and the others are made of metal (usually steel).
[0010]
As shown in FIG. 2, the screw member 20 is formed by integrally forming a hexagonal (nut-shaped) spanner hook portion 32 on the large diameter end side of the taper screw portion 30 screwed and fixed to the end portion of the plastic pipe. It is. In order to prevent the plastic tube from being pulled out, the taper thread portion 30 is formed in a cap shape whose surface on the large-diameter end side is perpendicular to the axis, as shown in a partially enlarged view (D). A shaft hole 34 is formed in the center of the screw member 30 in the axial direction.
[0011]
As shown in FIG. 3, the intermediate block 22 has a short columnar shape with a rounded shoulder (a corner on the tip side). At the center of the intermediate block 22, a large-diameter internal thread portion 36 is formed from the rear end surface to the intermediate portion in the axial direction, and a hole 38 having a smaller diameter than the large-diameter internal thread portion 36 communicates from the distal end surface to the large-diameter internal thread portion 36. Is formed.
[0012]
As shown in FIG. 3, the wire connecting member 24 has a circular convex portion 42 and a small-diameter male screw portion 44 having a smaller diameter projecting from a part of the outer periphery of the ring portion 40 to which a take-up wire is connected. It is. The hole 38 of the intermediate block 22 is formed in such a size that the small-diameter male screw portion 44 of the wire connecting member 24 can be inserted, but the circular convex portion 42 cannot be inserted. The outer diameter of the ring portion 40 (the maximum width of the wire connecting member 24) is set smaller than the outer diameter of the intermediate block 22.
[0013]
The shaft rod 26 is inserted into the shaft hole 34 of the screw-in member 20 and, as shown in FIG. 3, a large-diameter male screw portion 46 is integrally formed at the tip portion thereof. A small-diameter female thread portion 48 is formed from the distal end surface. A rear end block 50 having an outer diameter larger than the inner diameter of the shaft hole 34 is integrally formed at the rear end portion of the shaft rod 26. The rear end block 50 is formed with a connection hole 52 for connecting a nominal line (described later) inserted into the plastic tube.
[0014]
As shown in FIG. 4, the cap 28 has a substantially cylindrical shape, and the tip portion is smoothly reduced in diameter. The inner diameter D of the straight portion of the cap 28 is slidably fitted to the outer peripheral surface of the intermediate block 22 as shown in FIG. 1, and the inner diameter d of the tip opening of the cap 28 is smaller than the outer diameter of the intermediate block 22, It is set to be equal to or larger than the maximum width of the connecting member 24 (size that allows the wire connecting portion 24 to pass).
[0015]
Each member comprised as mentioned above is assembled as follows. First, the shaft rod 26 is inserted into the shaft hole 34 of the screw member 30 from the rear end side, and then the large-diameter male screw portion 46 at the tip portion of the shaft rod 26 is screwed into the large-diameter female screw portion 36 of the intermediate block 22. Next, after the small-diameter male screw portion 44 of the wire connecting member 24 is screwed into the small-diameter female screw portion 48 at the distal end portion of the shaft rod 26, the wire connecting member 24 and the intermediate block 22 are fixed by welding or the like so that they cannot be relatively rotated.
[0016]
Note that the thread pitch of the large-diameter male screw portion 46 and the large-diameter female screw portion 36 is different from the screw pitch of the small-diameter male screw portion 44 and the small-diameter female screw portion 48 in advance. For this reason, when the wire connecting member 24 and the intermediate block 22 are fixed by welding or the like, the shaft rod 26 and the intermediate block 22 cannot be rotated relative to each other, and there is no possibility that the screw connection between them is loosened. With the above assembly, the screwed member 20 can be rotated relative to the shaft 26 in a state in which movement in the axial direction is restricted.
[0017]
When the cap 28 is finally covered, the cap 28 covers the outer periphery from the shoulder portion of the intermediate block 22 to the spanner hooking portion 32 of the screwed member as shown in FIG. The cap 28 is in contact with the outer peripheral surface of the intermediate block 28 and is disposed on the same axis as the screwed member 20. The outer diameter (wall thickness) of the cap 28 is set in advance so as to be the same as or slightly larger than the outer diameter of the end portion of the plastic pipe whose diameter has been expanded by screwing the taper screw portion 30.
[0018]
Next, a method of using the plastic pipe tensioner configured as shown in FIG. 1 will be described. First, as shown in FIG. 5A, the cap 28 is removed, and the end portion of the nominal line 54 inserted in advance in the plastic tube 12 is connected to the rear end block 50 through the connecting hole 52. The nominal line 54 is for later drawing an optical fiber cable into the plastic tube 12. Next, the taper screw portion 30 is screwed into the end portion of the plastic tube 12. This screwing is performed by putting a spanner on the spanner hooking portion 32 and rotating the entire screwing member 20. As shown in the figure, the screwing is performed until almost all of the taper screw portion 30 enters the plastic tube 12. By this screwing, the end of the plastic tube 12 is expanded in diameter, and the screw thread of the taper screw portion 30 bites into the inner surface of the plastic tube 12, so that the screwing member 20 and the plastic tube 12 are integrated.
[0019]
Next, the cap 28 is put on as shown in FIG. The outer diameter of the cap 28 is set in advance so as to be the same as or slightly larger than the outer diameter of the end of the plastic tube 12 expanded by the screwing of the taper screw 30. Fits within the outer diameter of the cap 28. If necessary, a vinyl adhesive tape or the like may be wound from the rear end portion of the cap 28 to the front end portion of the plastic tube 12. Finally, the wire 56 is connected to the ring portion 40 of the wire connecting member 24. The wire 56 is inserted in advance in a conduit (12 in FIG. 6) through which the plastic tube 12 is to be drawn.
[0020]
In this state, the other end of the wire 56 is pulled with a winch or the like, and the plastic 12 is drawn into the pipe. In the process of retracting, the cap 28 mainly rubs strongly with the existing plastic pipe, but since the cap 28 is made of plastic, there is little risk of damaging the existing plastic pipe. Further, since the wire 56 is generally a twisted rope-like shape, a rotational force is generated in the direction in which the twist returns when tension is applied, but the wire connecting member 24 (integrated with the shaft rod 26) and the screw-in member 20 are relative to each other. Therefore, even if the wire connecting member 24 rotates in the twisting-back direction, the screwing member 20 only needs to be rotated, so that the plastic tube 12 does not have a risk of being twisted when retracted.
[0021]
The above is one embodiment of the present invention, and the present invention is not limited to this. For example, in the above-described embodiment, the intermediate block and the shaft bar are separate parts, but the intermediate block and the shaft bar may be formed as a single part, and the shaft bar and the rear end block may be separate parts. Moreover, you may form a wire connection part and an intermediate | middle block as an integral thing. In short, as long as the screwed member can rotate around the shaft rod, the wire connecting portion, the intermediate block, and the shaft rod may be joined in any structure.
[0022]
【The invention's effect】
As described above, in the plastic tube tensioner according to the present invention, the taper screw portion of the screw member is screwed into the end portion of the plastic tube, and the outer periphery from the shoulder portion of the intermediate block to the spanner hook portion of the screw member is made of plastic. Because it is covered with a cap, the portion that rubs strongly with the existing plastic tube or cable when pulling the plastic tube will be made of plastic, and the plastic tube can be pulled in without damaging the existing plastic tube or cable. it can.
[0023]
Further, the cap is arranged on the same axis as the screwed member by the intermediate block so that the outer diameter of the rear end portion is equal to or larger than the outer diameter of the end portion of the plastic pipe expanded by screwing of the tapered screw portion. Therefore, there is no possibility that the corner portion of the outer peripheral portion of the end face of the plastic tube will be caught around during the retraction, and the retraction can be performed smoothly.
[0024]
Furthermore, since the screwed member that is screwed and fixed to the plastic tube can rotate around the shaft rod, when a rotational force is applied by twisting back the wire to the wire connection part, the shaft rod simply turns idle in the screwed member. Since the screw-in member does not need to be rotated, there is no possibility that the plastic tube is twisted by the rotational force caused by twisting back of the wire, and the plastic tube can be drawn in a natural state.
[Brief description of the drawings]
1A is a half-cut side view, FIG. 1B is a front end side view, and FIG. 1C is a rear end side view showing an embodiment of a plastic tube tensioner according to the present invention.
2A is a side view, FIG. 2B is a front end side view, FIG. 2C is a rear end side view, and FIG. 2D is an enlarged view of a main part of the screw-in member constituting the pulling tool of FIG. .
3A is an exploded side view, and FIG. 3B is a rear end side view of the shaft rod, of the wire connecting portion, the intermediate block, and the shaft rod constituting the pulling tool of FIG. 1;
4A is a half-cutaway side view, FIG. 4B is a front end side end view, and FIG. 4C is a rear end side end view of the cap constituting the pulling tool of FIG. 1;
5A is a partially cutaway side view showing a state in which the screwing member of the tensioning tool of FIG. 1 is screwed into a plastic tube, and FIG. 5B is a part of a state in which the plastic tube is pulled by the tensioning tool of FIG. Incision side view.
FIG. 6 is a cross-sectional view showing a state in which a plurality of plastic pipes are drawn into a large-diameter pipe line.
[Explanation of symbols]
10: Pipe line
12: Plastic pipe
20: Screwed member
22: Intermediate block
24: Wire connecting member
26: Shaft bar
28: Plastic cap
30: Taper thread
32: Wrench span
34: Shaft hole
36: Large diameter female thread
40: Ring part
44: Small diameter male thread
46: Large diameter male thread
48: Small diameter female thread
50: Rear end block
52: Connecting hole
54: Nominal line
56: Wire

Claims (4)

A screwed member in which a spanner hook is integrally formed on the large-diameter end side of the tapered threaded portion screwed and fixed to the end of the plastic tube;
An intermediate block connected to the spanner hanging portion side of the screw member so as to be relatively rotatable on the same axis as the screw member;
A wire connecting portion provided on the tip side of the intermediate block;
A plastic cap that covers the outer periphery from the shoulder portion of the intermediate block to the spanner hanging portion of the screwed member and has an opening of a size that allows the wire connecting portion to pass through at the tip;
The cap is arranged on the same axis as the screwed member by an intermediate block, the outer diameter of the front end portion is smaller than the rear end portion, and the outer diameter of the rear end portion is the tapered screw portion. It is formed to be the same as or larger than the outer diameter of the end of the plastic tube into which
A plastic pipe tensioning tool characterized by that. 2. The plastic tube tensioning tool according to claim 1, wherein a shaft hole is formed in the axial direction in the screwed member, and a shaft bar penetrating the shaft hole is provided at a rear end of the intermediate block. A plastic tube tensioner characterized in that a rear end block is provided at the end to prevent the screwing member from being pulled out, whereby the screwing member and the intermediate block are connected so as to be relatively rotatable on the same axis. Ingredients. 3. The plastic pipe tensioner according to claim 2, wherein a connecting portion of a nominal line inserted into the plastic pipe is provided in the rear end block. 4. The plastic tensioner according to claim 2, wherein a large-diameter male screw portion formed at a tip portion of a shaft rod is screwed into a large-diameter female screw portion formed in an intermediate block, and is formed at a rear end of a wire connecting portion. The small-diameter male screw portion is screwed into the small-diameter female screw portion formed at the tip of the shaft rod, and the screw pitch of the large-diameter male screw portion and the large-diameter female screw portion and the screw pitch of the small-diameter male screw portion and the small-diameter female screw portion are A plastic pipe tensioning tool, which is different and is fixed so that the wire connecting portion and the intermediate block cannot relatively rotate.

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