JP7733586B2 - Synthetic resin pipe scraper - Google Patents

Description

The invention relates to a synthetic resin pipe scraper used to scrape the outer surface of the end of a synthetic resin pipe, particularly a polyethylene pipe or polypropylene pipe, to facilitate welding prior to fusing the pipe to a fitting.

In recent years, synthetic resin pipes such as polyethylene pipes have become increasingly popular for water supply, drainage, and gas piping, as they are resistant to corrosion and earthquakes and are easy to install. The most common method for connecting this type of synthetic resin pipe is to use an electrofusion (EF) fitting, which heats and melts the outer surface of the end of the synthetic resin pipe to the inner surface of the fitting to join them.

When connecting and joining synthetic resin pipes using EF fittings, a pre-processing step is required to remove any dirt or altered surface layers from the surfaces to be welded in order to ensure the quality of the joint, such as airtightness and strength. For this reason, the outer surface of the synthetic resin pipe near the end is thinly scraped (scraped) before the joining process.

A known tool for this scraping is a pipe scraper tool comprising a collet member, an expansion member, a threaded rod, and a scraper blade. The collet member has an outer periphery shaped similar to the inner periphery of the cutting pipe, a tapered inner periphery narrowing toward the opening of the cutting pipe, and is divided into several pieces circumferentially. The expansion member has an outer surface shaped similar to the inner periphery of the collet member, and the portion protruding from the collet member is threaded with a male thread for threading a nut. It is further fitted to the collet member for free axial movement. The threaded rod protrudes by threading its threaded portion into a female thread formed in the center hole of the expansion member, and its protruding end is provided with a head shank for clamping to the spindle chuck of an electric drill. The scraper blade is attached to a blade support rod that is fixed to the threaded rod and protrudes approximately parallel to the outer periphery of the cutting pipe so that it contacts the outer periphery of the cutting pipe (see, for example, Patent Document 1).

In addition to the above structure, scrapers currently in general use on the market generally come with a chip storage cover to prevent the cutting blade from running over chips.

Publication number 7-005921

The scraper described in Patent Document 1 has a problem in that chips get tangled in the pipe during cutting, and the cutting blade rides up on the tangled chips, causing uneven cutting.
Furthermore, in addition to the structure described in Patent Document 1, scrapers that are equipped with a chip storage cover have the problem that chips get stuck between the entrance of the chip storage cover and the cutting blade, preventing the chips from being stored in the chip storage cover and causing the blade to run over the chips that overflow from the chip storage cover, making it impossible to cut. Also, chips do not enter the chip storage cover properly in the first place, and just like when there is no chip storage cover, chips get tangled in the pipe during cutting, causing the cutting blade to run over the tangled chips, resulting in uneven cutting.

Furthermore, when the diameter of the synthetic resin pipe is medium to large, such as 75A or above, the amount of cutting increases, so the chip storage cover itself becomes larger and heavier, which generates centrifugal force, causing the main frame equipped with the cutting blade to vibrate significantly, resulting in greater variation in the amount of cutting.

The present invention was made in consideration of the above circumstances, and aims to provide a scraper for synthetic resin pipes that can prevent the cutting blade from riding on chips, thereby preventing uneven cutting, and minimizes the effect of centrifugal force on the main frame.

The present invention has the following aspects.
[1] A synthetic resin pipe scraper comprising a main frame having a cutting blade disposed so as to contact the outer peripheral surface of a synthetic resin pipe, a feeding means for moving the cutting blade in the circumferential direction and the pipe axis direction along the outer peripheral surface of the synthetic resin pipe, and a holding means for holding the synthetic resin pipe so that it can be cut, and which rotates the main frame to cut the outer peripheral surface of a joint between the synthetic resin pipes connected using a joint,
A scraper for synthetic resin pipes, in which a plate member is arranged parallel to the axial direction of the synthetic resin pipe, ahead of the cutting blade which is directly or indirectly installed on the main frame, and ahead of the cutting direction.
[2] A scraper for synthetic resin pipes as described in [1], which has a block-shaped chip holding plate located forward of the cutting blade in the cutting direction.
[3] A scraper for synthetic resin pipes according to [1] or [2], wherein the length of the plate member is 3 mm or more and 50 mm or less.
[4] A scraper for synthetic resin pipes according to any one of [1] to [3], wherein the thickness of the plate member is 0.1 mm or more and 5 mm or less.
[5] A scraper for synthetic resin pipes as described in [2], wherein the length of the chip holding plate in the cutting direction is 1 mm or more and 40 mm or less from the cutting blade.
[6] A scraper for synthetic resin pipes according to [2] or [5], wherein the height of the chip holding plate is at least 1 mm and not more than the height of the main frame.
[7] The scraper for synthetic resin pipes according to any one of [1] to [6], wherein the plate member is detachable.
[8] A scraper for synthetic resin pipes according to any one of [1] to [7], which has a mechanism for moving the plate member up and down via an elastic body.
[9] A scraper for synthetic resin pipes as described in [2], in which the chip holding plate and the plate member are shaped as a single piece that is integrated in an arc when viewed from the side.

This invention prevents the cutting blade from climbing over chips, thereby preventing uneven cutting, and minimizes the effect of centrifugal force on the main body frame. It is possible to provide a scraper for synthetic resin pipes.

1 is a side view, partly cut away, showing an example of a scraper for a synthetic resin pipe according to an embodiment of the present invention. FIG. 1 is a side view showing an example of a scraper for synthetic resin pipes according to an embodiment of the present invention. FIG. 1 is a side view showing an example of a scraper for synthetic resin pipes according to an embodiment of the present invention. FIG. 1 is a side view showing an example of a scraper for synthetic resin pipes according to an embodiment of the present invention. FIG.

The best mode for implementing a synthetic resin pipe scraper according to one embodiment of the present invention will be described below with reference to the drawings.

[Scraper for synthetic resin pipes]
Fig. 1 is a side view, partially cut away, showing an example of a scraper for synthetic resin pipes according to an embodiment of the present invention. Fig. 2 is a side view, partially cut away, showing an example of a scraper for synthetic resin pipes according to an embodiment of the present invention.
1 and 2, the synthetic resin pipe scraper 1 of this embodiment includes a main body frame 2. The main body frame 2 has a holding means 21 for holding a synthetic resin pipe 3 so that it can be cut, a cutting blade 22 disposed so as to abut against the outer circumferential surface of the held synthetic resin pipe 3, and a feeding means 23 for moving the cutting blade 22 circumferentially and axially along the outer circumferential surface of the synthetic resin pipe 3.
The synthetic resin pipe scraper 1 of this embodiment cuts the outer circumferential surface of a connecting portion 31 between synthetic resin pipes 3 connected by a joint by rotating the main body frame 2.

The holding means 21 has a core portion 211 that can be expanded to fit the inner diameter of the synthetic resin pipe 3, and an abutment plate 212 provided on the outside of this core portion 211 is attached to the inner surface of the connecting portion 31 of the synthetic resin pipe 3, thereby holding the synthetic resin pipe 3.

The main body frame 2 is also provided with a rotating shaft 231 that extends coaxially with the core portion 211. The feed means 23 is configured to automatically advance the cutting blade 22 as the rotating shaft 231 rotates. In the embodiment shown in Figures 1 and 2, a connecting shaft portion 232 is provided on the outside of the main body frame 2 and is formed on an extension of the rotating shaft 231. A rotary operating tool such as an electric drill can be connected to this connecting shaft portion, allowing the rotating shaft 231 to be rotated as desired.

An arm 24 extends from the main frame 2 along the outer periphery of the held synthetic resin pipe 3, parallel to the pipe axis. The cutting blade 22 is attached directly or indirectly to the main frame 2. The cutting blade 22 is provided at the tip of the arm 24. A cutting tool for thin-wall cutting is used as the cutting blade 22. While a blade with a thickness of 0.2 mm is generally used for thin-wall cutting, a blade with a larger cutting capacity may also be used. The cutting blade 22 preferably has a protrusion of 0.1 mm to 0.5 mm, more preferably 0.15 mm to 0.45 mm, and even more preferably 0.2 mm to 0.4 mm.

Furthermore, a chip holding plate 25 and a plate member 26 are arranged on the arm 24, parallel to the axial direction of the synthetic resin pipe 3, ahead of the cutting blade 22 in the cutting advance direction. The chip holding plate 25 is arranged ahead of the cutting blade 22 in the cutting advance direction. The chip holding plate 25 is block-shaped. The plate member 26 scoops up chips after cutting, and the chip holding plate 25 holds the chips a certain distance ahead of the cutting blade 22, allowing the cutting blade 22 to cut without running over chips tangled in the synthetic resin pipe 3.

It is preferable that the chip holder plate 25 and the plate member 26 be shaped as a single, integrated member that forms an arc when viewed from the side. A shape that forms an integrated member that forms an arc when viewed from the side specifically refers to a structure that tapers diagonally from the plate member to the chip holder plate 25, as shown in Figure 3, or a shape like a slide, as shown in Figure 4, that forms an arc when viewed from the side and appears rectangular when viewed from the front. By having the chip holder plate 25 and the plate member 26 shaped in this way, the plate member 26 can penetrate under the chips tangled in the synthetic resin pipe 3 after cutting and hold the chips a certain distance forward, allowing the cutting blade 22 to cut without climbing over the chips tangled in the synthetic resin pipe 3.

It is preferable that the plate member 26 be detachable from the arm 24. By making the plate member 26 detachable, the plate member 26, which is thinner than the main frame 2, can be replaced if it becomes deformed, allowing for long-term use.

The synthetic resin pipe scraper 1 of this embodiment preferably has a mechanism for moving the plate member 26 up and down via an elastic body. By having such a mechanism, even if the end of the synthetic resin pipe 3 is cut at an angle, it can cut in a way that follows the shape of the pipe end. Even after it has run up onto the synthetic resin pipe 3, the plate member 26 penetrates under the chips and holds them a certain distance forward, allowing the cutting blade 22 to cut without running up onto the chips entangled in the synthetic resin pipe 3.

Examples of elastic bodies include metal springs such as coil springs and leaf springs, and non-metallic springs such as polymer springs, inorganic springs, and fluid springs.

The length of the plate member 26 is preferably 3 mm or more and 50 mm or less, more preferably 4 mm or more and 40 mm or less, and even more preferably 5 mm or more and 30 mm or less. If the length of the plate member 26 is equal to or greater than the lower limit, the plate member 26 can easily enter under the chips while at the same time retaining a certain amount of chips in front of the plate member 26. If the length of the plate member 26 is equal to or less than the upper limit, the plate member 26 is easy to handle as a tool and is less likely to deform, allowing for long-term use.

The thickness of the plate member 26 is preferably 0.1 mm to 5 mm, more preferably 0.2 mm to 4 mm, and even more preferably 0.3 mm to 3 mm. If the thickness of the plate member 26 is equal to or greater than the lower limit, the plate member 26 can be strong enough to resist deformation when subjected to impacts during installation or when handled on-site. If the thickness of the plate member 26 is equal to or less than the upper limit, the plate member 26 can easily penetrate under chips entangled in the synthetic resin pipe 3, and by holding the chips a certain distance forward, the cutting blade 22 can cut without climbing over the chips entangled in the synthetic resin pipe 3.

The length of the chip holder 25 in the cutting direction is preferably 1 mm to 40 mm from the cutting blade 22, more preferably 3 mm to 35 mm, and even more preferably 5 mm to 30 mm. If the length of the chip holder 25 in the cutting direction is equal to or greater than the lower limit, chips held in front of the chip holder 25 will not enter under the cutting blade 22, and the cutting blade 22 can cut without climbing over chips entangled in the synthetic resin pipe 3. If the length of the chip holder 25 in the cutting direction is equal to or less than the upper limit, cutting can be performed without interference between the chip holder 25 and the synthetic resin pipe 3, even in piping where the cutting section is close to the branch or in fittings where the diameter changes midway, such as reducers.

The height of the chip holding plate 25 is preferably 1 mm or more but less than the height of the main frame 2, more preferably 3 mm or more but less than 40 mm, and even more preferably 5 mm or more but less than 30 mm. If the height of the chip holding plate 25 is above the lower limit, the chip holding plate 25 will be higher than the height of the cutting blade 22, and by holding the chips at a certain height or higher, the chips held in front of the chip holding plate 25 will not enter under the cutting blade 22, and the cutting blade 22 can cut without climbing over chips tangled in the synthetic resin pipe 3. If the height of the chip holding plate 25 is below the upper limit, the chip holding plate 25 will not protrude from the main body, so chips will not get caught when removed from the main frame 2, improving workability during installation.

Since this type of synthetic resin pipe scraper 1 is used at work sites where synthetic resin pipes 3 are fusion spliced, it is preferable that it be lightweight and robust. Therefore, it is preferable that the main components that make up the main frame 2 be made of lightweight metals such as aluminum or duralumin.

The cutting blade 22 may be a cutting tool as shown in the example, a spiral rotary blade, or any other steel blade capable of thinly cutting the outer surface of the synthetic resin pipe 3.

The synthetic resin pipe scraper 1 of this embodiment does not have a chip storage cover attached, and the plate member 26 is arranged ahead of the cutting blade 22 in the cutting direction and parallel to the pipe axis direction of the synthetic resin pipe 3. Therefore, the plate member 26 scoops up chips on the surface of the synthetic resin pipe 3 at the point where the cutting blade 22 cuts, preventing the cutting blade 22 from running over the chips and preventing uneven cutting.
Furthermore, because the plate member 26 is lighter and smaller than the chip storage cover, it is possible to minimize the effect of centrifugal force acting on the main frame 2. When using a chip storage cover, it was previously necessary to remove the chips from the chip storage cover after cutting the synthetic resin pipe 3. The synthetic resin pipe scraper 1 of this embodiment does not have a chip storage cover, which eliminates the need to remove the chips from the chip storage cover and improves workability.

[How to use a synthetic resin pipe scraper]
The method of using the synthetic resin pipe scraper 1 will now be described.
When using the synthetic resin pipe scraper 1, first, an insertion mark is marked on the outer surface of the connecting portion 31 of the synthetic resin pipe 3 to be joined by the joint. If there are scratches or dents on the surface of the synthetic resin pipe 3, these are removed and any dirt on the surface is also removed.

Next, the connecting portion 31 of the synthetic resin pipe 3 is set in the holding means 21 of the main frame 2 so that the arm 24 is parallel to the pipe axis direction. The core portion 211 is inserted into the inside of the synthetic resin pipe 3 and attached by expanding its diameter. The chip holding plate 25 is also adjusted in the pipe axis direction so that the cutting length extends to just before the insertion mark line of the synthetic resin pipe 3.

Finally, a rotary operating tool such as an electric drill is connected to the connecting shaft 232, and cutting begins. This makes it easy to cut the outer surface of the connecting portion 31 of the synthetic resin pipe 3 for the specified cutting length, and also allows for the subsequent connecting work of the synthetic resin pipe 3 to proceed efficiently.

In this way, the synthetic resin pipe scraper 1 makes it easy to cut the outer surface of the connecting portion 31 of the synthetic resin pipe 3 for a specified cutting length, and also allows for efficient subsequent connection work of the synthetic resin pipe 3.

The present invention can be suitably used to cut the outer surface of the end of a synthetic resin pipe, particularly a polyethylene or polypropylene pipe, to facilitate welding prior to fusing the pipe to a fitting.

REFERENCE SIGNS LIST 1 Synthetic resin pipe scraper 2 Main body frame 21 Holding means 211 Core portion 212 Contact plate 22 Cutting blade 23 Feeding means 231 Rotating shaft 232 Connecting shaft portion 24 Arm 25 Chip holding plate 26 Plate member 3 Resin pipe 31 Connecting portion

Claims (8)

A synthetic resin pipe scraper includes a main body frame having a cutting blade disposed so as to contact the outer peripheral surface of a synthetic resin pipe, a feeding means for moving the cutting blade in the circumferential direction and the pipe axial direction along the outer peripheral surface of the synthetic resin pipe, and a holding means for holding the synthetic resin pipe so that it can be cut, and the main body frame is rotated to cut the outer peripheral surface of a joint between the synthetic resin pipes that are connected using a joint,
A block-shaped chip holding plate is provided in front of the cutting blade, which is directly or indirectly installed on the main body frame, in the cutting advance direction in the pipe axis direction of the synthetic resin pipe,
A plate member is provided in front of the chip holding plate in the cutting advance direction in the pipe axial direction of the synthetic resin pipe,
A scraper for synthetic resin pipes, wherein the plate member is disposed parallel to the axial direction of the synthetic resin pipe. 2. The synthetic resin pipe scraper according to claim 1 , wherein the length of the plate member is 3 mm or more and 50 mm or less. 3. The synthetic resin pipe scraper according to claim 1 , wherein the thickness of the plate member is 0.1 mm or more and 5 mm or less. 2. The scraper for synthetic resin pipes according to claim 1 , wherein the length of the chip retaining plate in the cutting direction is 1 mm or more and 40 mm or less from the cutting blade. 5. The synthetic resin pipe scraper according to claim 1 , wherein the height of the chip retaining plate is 1 mm or more and less than the height of the main body frame. The synthetic resin pipe scraper according to any one of claims 1 to 5 , wherein the plate member is detachable. The scraper for synthetic resin pipes according to any one of claims 1 to 6 , further comprising a mechanism for moving the plate member up and down via an elastic body. 2. The synthetic resin pipe scraper according to claim 1 , wherein the chip retaining plate and the plate member are formed as a single member that is integrated into one piece and has an arcuate shape when viewed from the side.