JPH02269503A - Cutting tool for plastic tube - Google Patents

Abstract

PURPOSE:To cut a fixed amount of depth on the outer surface of a plastic tube, after rectifying deformation of the tube, it any, by forming a cutting tool comprising a guide portion for allowing the end portion of the tube to be fittingly inserted therein, a cutter whose blade is projected by a cutting allowance from inner surface and forming the inner diameter of the guide portion within a prescribed range. CONSTITUTION:Blind holes 2, 3 of a main body 1 are formed with guide portion 2a, 3a respectively at their inlet sides with a proper length and the inner diameter (di) is formed in such a relation as 0.9p<=di<=Dp to an outer diameter (Dp) of a plastic tube 9 forcebly fitted therein. And for cutting, the end part of the plastic tube 9 is inserted into the one side blind hole 3 until it hits a step, thereby rectifying deformation at its inserted end portion of the tube. then the outer peripheral surface of the tube is slitted by a cutter 4 from end portion thereof. When the grip 1a of the main body 1 is gripped and pushingly turned under this condition, the tube is cut on its outer surface by a fixed amount of depth by the cutter 4 to be gradually advanced deeper. When the end face of the tube reaches to a cutter 8, it is cut perpendicuarly to the axis of the tube.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used for cutting the outer surface of relatively flexible plastic pipes such as polyethylene pipes used as water pipes, hot water pipes, gas pipes, etc. related to cutting tools.

In conventional piping work, various types of joints such as T joints, socket joints, elbow joints, saddle joints, camp joints, etc. are used to connect or connect pipes and to close pipe ends. If the connection between and the pipe is a plastic pipe,
This is generally done by heat fusion. Such heat fusion bonding has normally been carried out by heating and melting the outer circumferential surface of a plastic tube with a heater and then inserting it into a joint or pressing it into a crimped joint. There is also a type in which a hot wire is embedded so that heat fusion is performed by energizing. In any case, in order to ensure that the fusion is performed properly and that the fusion strength is not impaired, it is necessary to remove dirt and foreign matter adhering to the outer surface of the plastic tube. For this purpose, the surface of the tube was scraped in the axial direction using a woodworking plane or the like, or a rotary plane was fitted onto the plastic tube and rotated.

Problems to be Solved by the Invention When using a conventional wood planer, it is difficult to uniformly scrape the surface of a pipe, resulting in uncut parts, uneven cutting depth, and a rough surface after cutting. Also, when using a conventional rotary plane, if the pipe is crushed and deformed, uncut portions may be left or the depth of cut may be uneven.

The present invention has been made with the aim of solving the above-mentioned problems, and even if the tube is deformed, it can be corrected and the outer circumferential surface of the tube can be cut with a constant depth of cut.

A cutting tool according to the present invention is a cutter for cutting the outer surface of a plastic pipe, and is provided with a guide portion having a circular cross section on the inlet side of the cutter under the following conditions, so that the cutting edge of the cutter is It protrudes from the circumferential surface of the guide part by the amount of cutting allowance.

0.9Dp≦di≦Dp, preferably 0.95Dp≦d
i≦Dp Here, Dp Outer diameter di of the niblastic tube: Inner diameter of the guide portion The plastic tube to which the present invention is directed is a relatively flexible plastic tube that can be press-fitted. Typical examples of such plastic pipes include polyethylene pipes and polybutene pipes.

The guide part is composed of a fitting hole into which the end of the plastic tube can be fitted, and for example, a cutter may be provided therein, but it is preferably formed on the inlet side of the cylindrical body or the inlet side of the main body provided with a blind hole. A guide portion is formed in the guide portion, and a cutter is located at the outlet of the guide portion and attached to the cylinder or main body. And preferably,
Further, the fitting hole is formed as a stepped hole, the large diameter portion serves as a guide portion, and the diameter of the small diameter portion is made smaller than the large diameter portion by the amount of milling.

The cylindrical body or rotating body that uses a part of the fitting hole as a guide also preferably includes a cutter in the other part of the hole that cuts the tube end surface to a position where the tube end surface reaches the position when the required cutting length is approached. is provided.

The cutter is preferably made replaceable.

Known replacement blades are used for this purpose, and are removed and replaced when they become dull.

The cylindrical body or rotary body is further provided with stepped holes or blind holes with different diameters on the left and right sides, and guide portions are similarly provided on the left and right sides.

The stepped hole or the blind hole may be formed as a stepped hole whose inner diameter gradually decreases toward the back, and guide portions may be similarly provided at each portion having a different diameter.

By pushing the working guide into the plastic tube, or conversely by pushing the plastic tube into the guide, the deformation of the tube is corrected. Then, you can rotate the plastic tube by pushing one toward the other, or by rotating the tool while pushing both, but it is easier to do the work by rotating the tool), and the tube is straightened. At the same time, the outer peripheral surface is cut by a cutter.

When the entrance side of the blind hole is used as a guide part, cutting is possible until the tube end reaches the bottom of the blind hole. Therefore, the cutting length in the tube axis direction can be regulated by the blind hole, making it possible to maintain a constant cutting length.

If the hole has a stepped shape by reducing the inner diameter by the amount of cutting allowance, forcefully fit the hole until it hits the plastic pipe and start cutting.
Continue cutting while maintaining the abutted state. Therefore, the stepped portion positions the cutting position, and the uncut portion cannot get over the stepped portion, and only the cut portion can enter the small diameter portion, so that cutting can be performed reliably without leaving any uncut parts.

In addition, when a cutter for cutting the tube end surface is installed in the hole into which the cut plastic tube enters, when the cutting of the outer peripheral surface of the tube has progressed a certain amount, the cutting and the cutting of the tube end surface are performed in parallel, In addition to the outer peripheral surface, the tube end surface is cut smooth and perpendicular to the tube axis. In this case, the cutting length corresponds to the distance between the cutter that cuts the outer peripheral surface and the cutter that cuts the tube end surface.

When guide portions are provided on the left and right sides or when guide portions are provided at each step of the stepped hole, plastic pipes with different diameters can be cut with one tool.

Problems to be Solved by the Invention When a plastic pipe is press-fitted by providing a guide part, if the pipe end is press-fitted into the small diameter part even after cutting, the frictional resistance during rotation increases. Therefore, after cutting, it is desirable to release the pipe end or enlarge the hole after cutting so that the cut plastic pipe end fits loosely, but the problem in this case is that after cutting, the pipe end is loosely fitted. When the tube end is released from pressure, it swells, and when it is pulled out after cutting, the surface of the tube end is damaged by the cutting edge of the cutter. This problem is particularly likely to occur when press-fitting, but it also occurs with tools in which the end of the tube expands after cutting.

Another object of the present invention is to solve the above-mentioned problems and prevent the cutter from being damaged by the edge of the cutter when it is pulled out after cutting.

Means for Solving the Problems In order to achieve the above object, the cutting tool of the present invention is provided with a guide portion whose diameter gradually increases from the cutting edge on the exit side of a cutter for cutting the outer surface of a plastic pipe.

It is desirable that the cutting tool be provided with a guide section meeting the above conditions on the inlet side of the cutter.

When the end of the plastic tube whose outer surface has been cut by the working cutter enters the guide section, the frictional resistance during rotation is reduced. Even if it bulges at the guide part, when it is pulled out after cutting, it contracts at the guide part and the cutting edge does not cut into the outer peripheral surface.

Embodiment The main body 1 has a large diameter central portion and is formed as a gripping portion 1a.
A large diameter blind hole 2 and a small diameter blind hole 3 are formed on the left and right sides. Each blind hole 2 and 3 has an appropriate length guide portion 2a on the entrance side,
3a, and its inner diameter di is 0,9 rap≦di with respect to the outer diameter Dρ of the plastic pipe 9 to be press-fitted.
There is a relationship of ≦Dp, and the inner diameter of the inner diameter is smaller due to the machining. Then, straddle the stepped part and force it so that the cutting edge is flush with the inner peripheral surface on the back side.
It is fastened by a set screw 6 through a recess 5 formed toward.

The main body 1 also has a rectangular window 7 formed in the grip portion 1a. A cutter 8 whose cross section is a parallelogram is attached to this window 7.
is inserted, and the cutting edges forming acute angles on both the left and right sides protrude toward the shaft center into the blind holes 2 and 3, respectively.

During cutting, the tube end of the plastic tube 9 is pushed into one of the blind holes until it hits the step (the illustrated example shows an example in which it is pushed into the blind hole 3), and the fitted tube ends are Accordingly, the deformation is corrected.

When the tube is pushed in until it hits the step, the cutter 4 also makes a cut in the tube's outer peripheral surface in the axial direction from the tube end.

In this state, when the main body 1 is gripped by the gripping portion 1a and rotated while pushing the main body 1 into contact with the stepped portion, the outer peripheral surface is cut by the cutter 4, and the cut portion gradually enters the inner side. When the tube end surface reaches the cutter 8 and rotates while being pushed, the tube end surface is cut. This cutting is performed until the tube end reaches the bottom of the blind hole 3, and when the tube end is rotated while being pressed against the hole bottom, the tube end surface is cut perpendicular to the tube axis.

The cutting tool shown in FIG. 4 has a main body 11 formed with a stepped hole 12 whose inner diameter gradually increases toward the outlet, and each of the stepped portions 12A, 12B, and 12C having different inner diameters has a guide portion on the inlet side. 12a, 12b, and 12c are formed under the same conditions as above, and the inner diameter of each stepped portion is first made smaller by the cutting allowance, and then gradually enlarged. A cutter 13 is attached to each of the stepped portions 12A, 12B, and 12C in the same manner as described above, so that the cutting edge continues continuously on the peripheral surface on the back side.

The cutting tool shown in FIG.
1, fit the replaceable blade 22 that has been bent to a length that fits into the recess so that the cutting edge is parallel to the tube axis and flush with the inner peripheral surface on the back side,
A presser foot 23 is fitted on top of the presser foot 23 and screwed down. By loosening the screw 24 and removing the presser foot 23, the replaceable blade 22
It can be removed and replaced.

(1l) The cutter for cutting the pipe end face can also be made into a replaceable blade. In this case, the replaceable blade is usually installed obliquely with respect to the tube axis direction.

Effects of the Invention The present invention is configured as described above, and has the following effects.

Before the outer circumferential surface of the tube is cut by the cutter, the deformation of the tube is corrected by the guide section, so by rotating the tool, the outer circumferential surface of the tube can be cut with a constant depth of cut without leaving any uncut parts, at least in the circumferential direction. be able to.

In the case of a tool that uses the entrance side of the blind hole as a guide part, cutting can be performed with a constant cutting length by cutting until the tube end hits the bottom of the blind hole.

When the hole is stepped and the entrance side is used as a guide part, the cutting position can be determined and uncut parts in the tube axis direction can be eliminated.

By making the cutter a known replaceable blade and making it replaceable,
The cutter is inexpensive and can be replaced when it becomes dull (l2), and there is no need to sharpen it, further improving work efficiency.

When a cutter for cutting the tube end surface is provided, it is possible to cut the tube outer circumferential surface and the tube end surface, and the cutting length can be changed by the cutter for cutting the outer circumferential surface and the cutter for cutting the tube end surface. The interval can be of constant length.

In the case of a tool in which guide portions are provided on the left and right, or guide portions with different diameters are provided in stages, one tool can cut plastic pipes with different diameters.

Furthermore, if the cutter for cutting the tube end surface is made to protrude into both the left and right holes, one cutter can be used for both purposes, which simplifies the structure.

Tools that have a guide section on the exit side of the cutter whose diameter gradually increases from the cutting edge can reduce frictional resistance during rotation, allowing smooth cutting work and making it easier to pull out the tool after cutting. The cut tube surface will not be damaged by the cutter's edge.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a tool according to the present invention, Fig. 2 is a front view of the same tool, Fig. 3 is a sectional view taken along line A-A in Fig. 2, and Fig. 4 is a sectional view of a tool according to another invention. FIG. 5 is a partially cutaway plan view of a tool according to another invention. 1.11.19...Main body 2.3.17.18...
Blind hole 4.13...Cutter 8...Cutter 12...
Stepped hole 5. 21... Recess 22... Replacement blade 23... Holder 24... Screw Applicant Osaka Gas Co., Ltd. and two other agents Patent attorney Akira Sato

Claims (11)

[Claims] (1) Consisting of a guide part with a circular inner circumferential surface into which the end of the plastic pipe can fit, and a cutter provided on the exit side of the guide part, the cutting edge of which protrudes from the inner circumferential surface by the cutting allowance, The guide portion is a cutting tool for a plastic pipe whose inner diameter di satisfies the following condition: 0.9Dp≦di≦Dp, where Dp is the outer diameter of the plastic tube. (2) The cutting tool for plastic pipes according to claim 1, wherein the plastic pipes are polyethylene pipes, polybutene pipes, etc. (3) A cutting tool for a plastic pipe according to claim 1, wherein the entrance side portion of the blind hole is a guide portion. (4) A cutting tool for a plastic pipe according to claim 1, wherein the inlet side portion of the cylindrical body is a guide portion. (5) The cutting tool for plastic pipes according to claim 3 or 4, wherein the hole whose inlet side portion is a guide portion is formed as a stepped hole whose inner diameter is reduced by a cutting allowance on the back side. (6) A cutting tool for plastic pipes according to claim 3 or 4, wherein a cutter is provided for cutting the pipe end face at a position where the pipe end face reaches when cutting a certain length. (7) The cutting tool for plastic pipes according to any one of claims 1 to 6, wherein the cutter is replaceable with a replaceable blade. (8) A cutting tool for plastic pipes, which is provided with a guide section and a cutter according to claim 1 on both sides of a cylindrical body with holes with different diameters on the left and right sides or a main body with blind holes with different diameters on both the left and right sides. (9) A cutting tool for plastic pipes in which the cutter according to claim 7 is provided so as to protrude into the holes on both the left and right sides. (10) A cutting tool for plastic pipes, which is provided with a guide part whose diameter gradually increases from the cutting edge on the exit side of the cutter that cuts the outer surface of the plastic pipe. (11) A cutting tool for plastic pipes according to any one of claims 1 to 9, wherein a guide portion whose diameter gradually increases from the cutting edge is provided on the exit side of the cutter.