JPH0542496A - Cutter for synthetic resin pipe - Google Patents

Abstract

PURPOSE:To easily cut a synthetic resin sheath pipe for an existing sheath-pipe type pipe-line even in a narrow space without damaging the water passing pipe inside the sheath pipe by projectedly providing an edge on the inside of an flexible frame body of a C-shaped section for embracing the pipe to be cut. CONSTITUTION:In a cutter A for a synthetic resin pipe, an edge 2 is projectedly provided on the inside of a synthetic-resin made frame body 1 having an open part, and the height of the edge 2 is made to be nearly equal to the wall thickness of the synthetic resin pipe P. In the case where a synthetic resin pipe P is to be cut by the cutter A for a synthetic resin pipe, the open part 11 of the frame body 1 is extendedly opened so as to embrace the synthetic resin pipe P in the inside of the frame body 1, and then the cutter A is turned in the direction of the arrow m, so that the cutting edge 21 bites into the outside surface of the synthetic resin pipe P. Since the hardness of the synthetic resin pipe to be cut is relatively low, the cutting resistance acting on the edge is relatively low, so that the force acting on the frame body is also small. Thus, even if synthetic resin is used for the frame body, the fixing condition of the edge can be stably maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutter for synthetic resin pipes used as water supply pipes, hot water supply pipes, drainage pipes, gas pipes or electric wire protection pipes.

[0002]

2. Description of the Related Art Recently, a sheath pipe construction method has been used for indoor pipes such as the above-mentioned water supply pipes (a sheath pipe is previously arranged at the time of construction work of a building, and a gas pipe or the like is provided inside the existing sheath pipe at the time of facility construction at a later date. The inner pipe or the electric wire) is often used, and the sheath pipe is required to have flexibility, load resistance, corrosion resistance and the like, and a corrugated synthetic resin pipe is usually used.

Conventionally, a hand saw or an electric cutter is used to cut the synthetic resin pipe in indoor piping work such as a synthetic resin water supply pipe. However, when using a hand saw or the like to cut the sheath pipe in the repair work of the existing pipeline using the above sheath pipe construction method, there is a fear that it may also cut the water passage pipe or the electric wire in the sheath pipe, Cutter suitable for pipe cutting
Is expected to emerge.

Conventionally, as a cutter for metal pipes such as steel pipes for water supply, a pipe receiving roll is rotatably supported in an open frame in which pipes can be taken in and out, and a handle shaft can be moved up and down on the frame by a screw mechanism or the like. The blade holder, which is attached in such a manner as to hold the pipe to be cut by the above-mentioned roll receiver, is axially supported by the blade holder.
A so-called roll cutter in which the above is pivotally attached to the lower end of the handle shaft is known, and may be used for cutting a synthetic resin pipe.

In this roll cutter, a roll blade is used, and when the outer peripheral surface of the roll blade comes into contact with the outer surface of the pipe, the blade does not enter the pipe wall any more. Even if it is used for cutting the sheath pipe of the existing pipeline due to, it is possible to reliably prevent accidental cutting of the internal water passage pipe and the like.

[0006]

However, in the above roll cutter, since the handle shaft is projected, a wide space is required for the rotation of the roll cutter,
The handle shaft may interfere with the equipment installed in the existing pipe, making it difficult to cut the existing pipe.

When cutting a pipe with a cutter, the rotational moment required to rotate the cutter is the product of the cutting resistance force acting on the blade and the radius of gyration, and the cutting resistance force is the cutting force of the pipe to be cut. The smaller the hardness, the smaller the hardness. However, the hardness of the synthetic resin pipe is considerably smaller than that of a metal pipe such as a steel pipe, and therefore the rotation moment required to rotate the cutter is further reduced. Thus, if the rotational moment required to rotate the cutter is small, the force acting on the constituent members of the cutter is also small. In particular, in the above-mentioned corrugated sheath tube made of synthetic resin, the annular convex portion that constitutes the peak portion of the wave performs a rib action, and due to its excellent load resistance, the pipe wall thickness can be made thin and the cutting resistance of the blade Since the force can be made sufficiently small, the force acting on the constituent members of the cutter can also be made sufficiently small.

Since the force acting on the constituent members of the cutter is small as described above, the structure of the roll cutter is unnecessarily robust, too large, and disadvantageous in operation. An object of the present invention is to reduce the size of a cutter used for cutting synthetic resin pipes for indoor piping, particularly a synthetic resin sheath pipe, in accordance with the fact that the rotational moment in operation thereof is small. It is an object of the present invention to provide a synthetic resin pipe cutter capable of easily cutting a synthetic resin sheath pipe of a type pipe line even with a narrow space without accidentally damaging an internal water passage pipe or the like.

[0009]

The cutter for synthetic resin pipes according to the present invention is characterized in that a blade is projectingly provided on the inner surface of a flexible frame body having an opening for holding the pipe to be cut.

[0010]

[Function] Since the hardness of the synthetic resin pipe, which is the pipe to be cut, is relatively low, the cutting resistance acting on the blade is relatively small, and the force acting on the frame body corresponding to this cutting resistance is small. Therefore, the fixed state of the blade can be stably maintained even if the frame is made of synthetic resin of the same material as the pipe to be cut. Therefore, the synthetic resin pipe can be smoothly cut even with a small and simple structure in which the blade is fixed in the frame body. In addition, a flexible material such as synthetic resin can be used for the frame body, and can be easily attached to and detached from the pipe to be cut.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention in its use state.

In FIG. 1, P is a synthetic resin pipe as a pipe to be cut. A shows a cutter for a synthetic resin pipe according to the present invention, in which a blade 2 is projected on the inner surface of a synthetic resin frame body 1 having an open portion, and the height of the blade 2 is the wall thickness of the synthetic resin pipe P. Is almost equal to. Reference numeral 21 indicates a cutting edge.

In order to cut the synthetic resin pipe P with the above-mentioned cutter A for synthetic resin pipe, the open portion 11 of the frame 1 is expanded to enclose the synthetic resin pipe P in the frame 1 and then The cutter A is rotated in the direction of the arrow so that the cutting edge 21 bites into the outer surface of the synthetic resin pipe P. In this case, if the cutting resistance force acting on the blade 2 is f ₁ , the frictional force acting between the frame 1 and the synthetic resin pipe P is f ₂ , and the radius of the frame 1 is R, the cutter A is The rotation moment M required to rotate is M = (f ₁ + f ₂ ) R.

As a method of applying the rotation moment, as shown in FIG. 2 (a), the blade 2 is provided with an outward projecting portion 22, and a force is applied to the projecting portion 22. As shown in (b), there is a method in which a synthetic resin frame body 1 is provided with an outer protrusion 12 and a force is applied to the protrusion 12. In the former case, only the above-mentioned frictional force f ₂ acts on the synthetic resin frame body 1. Since this frictional force is due to the friction between the synthetic resin surfaces, the synthetic resin frame body 1 is small. The force acting on the body 1 can be kept sufficiently small. On the other hand,
In the latter case, a cutting resistance force f ₁ received by the blade 2 from the synthetic resin pipe P acts on the synthetic resin frame body 1 in addition to the frictional force f ₂ . Therefore, the cutting resistance force received by the blade 2 is a force required for the blade 2 to propel the pipe wall of the synthetic resin pipe P in the circumferential direction, and is embedded in the synthetic resin frame body 1. Base 2 of blade 2
At 0, the resin cannot move in the synthetic resin frame body 1 with such a force, and the fixed state of the base portion 20 of the blade 2 in the synthetic resin frame body 1 is as shown in FIG. It can be maintained stable even under severe force.

Therefore, during the cutting of the synthetic resin pipe P by the cutter A, the fixed state of the blade 2 in the synthetic resin frame body 1 is stably maintained regardless of how the rotational force is applied, and the synthetic resin pipe is maintained. The cleavage of P can be smoothly performed.

In the above synthetic resin frame body 1, FIG.
Even when the force is applied as shown in (B), a predetermined thickness is given to the cutting resistance force received by the blade 2 so that the base portion 20 of the blade 2 can be embedded and fixed in a sufficiently stable manner. It is preferable that the thickness of the cut synthetic resin pipe P is 0.5 to 2 times, and if it is 2 times or more, it is difficult to open and close the open portion 11 of the frame 1 to the pipe P to be cut. Become.

Metal can be used for the frame body 1. In this case, the thickness of the frame body interferes with attachment / detachment to / from the pipe P to be cut by expanding the open portion 11 of the frame body 1. Set not to. In the frame body, as shown in (a) and (b) of FIG. 3 [a cross-sectional view taken along line (a) of FIG. 3], only a part 10 of the frame part 1 has a C-shaped cross section. Can also be used.

When the above-mentioned corrugated sheath tube made of synthetic resin is cut by the cutter of the present invention, in order to prevent the internal water passage tube from being completely damaged, the middle of the annular convex portion which is the peak of the wave. It is safe to disconnect the. Further, as shown in (a) of FIG. 4, it is preferable that the inner surface of the frame 1 is provided with the ridge guides 13, ... For the valleys of the corrugated sheath tube.

Further, in order to accommodate various diameters of the synthetic resin corrugated sheath tube, as shown in FIG. 4B, the convex guide 13 is provided at the least common multiple of the wave pitch of these various sheath tubes. You can also

The position of the blade 2 in the frame 1 is usually at the center in the length direction (pipe axis direction) of the frame 1, but it may be at the rear end side or the front end side. It is also possible to provide at a plurality of locations in the circumferential direction of the body, for example, both ends in the circumferential direction and their centers.

The outer surface of the frame 1 is provided with a protrusion as shown in FIGS. 2A and 2B, and a grip 14 is formed as shown in FIG. 5B. You can also Further, a mark for indicating the position of the blade 2 may be provided on the frame body 1. For example, as shown in FIG. 5A, the notch 15 may be provided at the same position as the blade 2 at the edge of the frame 1. A protrusion may be provided instead of the notch 15. Further, marking may be provided on the entire outer peripheral surface of the frame body corresponding to the position of the blade 2.

[0022]

The cutter for synthetic resin pipes of the present invention is constructed as described above, and the base of the blade is placed in a frame body having an open portion so that the blade can withstand the cutting resistance force received from the synthetic resin pipe to be cut. The fixed state of the blade can be stably maintained during cutting of the synthetic resin pipe only by embedding, and the cutting of the synthetic resin pipe can be smoothly performed. Further, even if the diameter of the pipe to be cut changes a little, the flexibility of the frame can cope with it, and unlike the conventional roll cutter, in order to cope with the change in the diameter of the pipe to be connected, the roll for the receiving roll is adjusted. -Because it does not require a screw-type handle to adjust the position of the blade, it does not take a space for operation,
It is possible to easily cut the sheath pipe of the existing sheath pipe type in a narrow place near the equipment without damaging the internal water passage pipe.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

2A and 2B are cross-sectional views showing another embodiment different from the above of the present invention.

3 (A) is a cross-sectional view showing another embodiment different from the above of the present invention, and FIG. 3 (B) is a cross-sectional view taken along line (A) of FIG.

4 (a) and 4 (b) are transverse sectional views showing another embodiment different from the above of the present invention.

5 (a) and 5 (b) are side views showing another embodiment different from the above of the present invention.

[Explanation of symbols]

 1 Frame 2 Blades P Cut tube

Claims (1)

[Claims] 1. A cutter for a synthetic resin pipe, characterized in that a blade is projected on an inner surface of a flexible frame body having an opening portion for holding a pipe to be cut.