Pipe cutting machine

Abstract

To provide a pipe cutting machine which can be applied to materials to be cut of various thicknesses.SOLUTION: A pipe cutting machine includes: a cutting mechanism which cuts a tubular material to be cut along a longitudinal direction; and a holding mechanism which holds the material to be cut along a cutting direction. The pipe cutting machine cuts the material to be cut by bringing the cutting mechanism close to the material to be cut by a relative movement of the cutting mechanism and the holding mechanism. The cutting mechanism has an inside blade section which is provided in a rod-like body inserted into an inner diameter side of the material to be cut and bites from the inner diameter side of the material to be cut in an outer diameter direction and an outside blade section which is provided on the outer diameter side of the inside blade section and bites from the outer diameter side of the material to be cut in an inner diameter direction. The outside blade section and the inside blade section relatively move the material to be cut along a longitudinal direction while pressing to each other in a state of holding the material to be cut therebetween.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pipe cutting machine that cuts a tubular object along its longitudinal direction. [Background technology]

[0002] In the past, waste treated as radioactive material sometimes contained materials that did not need to be treated as radioactive material. Therefore, a clearance system has been established that allows materials that do not need to be treated as radioactive material to be reused or disposed of in the same way as general waste. In other words, the clearance system is a system in which waste that does not need to be treated as radioactive waste can be treated in the same way as ordinary recycled materials or industrial waste, without any conditions on use or disposal.

[0003] For example, in nuclear power plants, pipes used to transport contaminated materials, including radioactive materials, may be removed. Depending on the contamination level of the radioactive materials in the pipes to be removed, they may be subject to the clearance system and may be reused or disposed of in the same way as general waste materials. Therefore, a device that cuts pipes along their length has been proposed to measure the contamination level of radioactive materials in the pipes or to decontaminate the inner surfaces of the pipes (Patent Document 1).

[0004] The device disclosed in Patent Document 1 includes a first blade portion and a second blade portion, and the first blade portion moves relatively along the longitudinal direction of the pipe while contacting the outer diameter side of the pipe. As a result, the first blade portion bites into the pipe from the outer diameter side toward the inner diameter side, and stress is concentrated in the inner diameter direction on the outer diameter side of the pipe by the first blade portion, causing the outer diameter side of the pipe to be crushed and plastically deformed, forming a biting portion along the longitudinal direction. The second blade portion moves relatively along the longitudinal direction of the pipe while contacting this biting portion from the inner diameter side of the pipe. As a result, the auxiliary second blade portion can cut the portion that could not be completely cut by the first blade portion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-24043 Summary of the Invention [Problem to be solved by the invention]

[0006] The device disclosed in Patent Document 1 first forms a bite portion in the outer diameter portion of the pipe with the first cutting edge, so if the pipe is thick (for example, a pipe thickness exceeding 4 mm), there is a possibility that a sufficient bite portion will not be formed due to a reaction force from the pipe. If a sufficient bite portion is not formed, the cutting accuracy will be poor and in some cases, cutting may not be possible. Furthermore, if a sufficient bite portion is not formed by the first cutting edge, the load on the second cutting edge will be large, which may shorten the life of the device.

[0007] SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a pipe cutting machine that can be applied to workpieces of various thicknesses. [Means for solving the problem]

[0008] The pipe cutting machine of the present invention comprises a cutting mechanism that cuts a tubular material along its longitudinal direction, and a holding mechanism that holds the material along the cutting direction, and in this pipe cutting machine, the cutting mechanism is brought closer to the material by relative movement between the cutting mechanism and the holding mechanism, thereby cutting the material.The cutting mechanism is provided on a rod-shaped body that is inserted into the inner diameter side of the material, and comprises an inner blade portion that bites into the material from its inner diameter side toward its outer diameter, and an outer blade portion that is provided on the outer diameter side of the inner blade portion and bites into the material from its outer diameter side toward its inner diameter, and the outer blade portion and inner blade portion press against each other while sandwiching the material, and move the material relatively along the longitudinal direction.

[0009] According to the pipe cutting machine of the present invention, the outer blade portion and the inner blade portion sandwich the object and press against each other while moving the object relatively along the longitudinal direction. That is, the outer diameter side of the object is crushed and plastically deformed by the stress concentration in the inner diameter direction of the outer blade portion, forming a bite portion. At the same time, the inner diameter side of the object is crushed and plastically deformed by the stress concentration in the inner diameter direction of the inner blade portion. In this way, the outer diameter side and the inner diameter side of the object press against each other, forming a cut portion. Furthermore, because the stresses of the outer blade portion and the inner blade portion are offset between the inside and outside of the object, no reaction force support is required. Forming this cut portion along the longitudinal direction of the object allows the object to be cut.

[0010] The outer blade portion and the inner blade portion are preferably circular blades that rotate in response to the relative movement of the workpiece. This allows the outer blade portion and the inner blade portion to make uniform contact with the workpiece, thereby extending the life of the blade portions. Furthermore, the workpiece can be guided along its longitudinal direction, allowing the workpiece to be plastically deformed while moving accurately.

[0011] In the above configuration, it is preferable that the outer diameter of the rod-shaped body is smaller than the inner diameter of the workpiece, and that the rod-shaped body is provided with a feed roller that contacts the inner diameter side of the workpiece and rotates in response to the relative movement of the workpiece. This allows the rod-shaped body to move smoothly along the inner diameter side of the workpiece while maintaining a stable posture while being supported by the feed roller inside the pipe. In addition, the contact surface between the workpiece and the rod-shaped body can be reduced, thereby reducing the driving energy of the rod-shaped body. Furthermore, it is possible to reduce wear of the rod-shaped body due to contact with the workpiece and suppress the generation of frictional heat, thereby extending the life of the device.

[0012] In the above configuration, it is preferable that the cutting mechanism is disposed above the holding mechanism, the holding mechanism holds the workpiece so that it extends in the vertical direction, and the outer blade portion and the inner blade portion are lowered to cut the workpiece, thereby allowing the outer blade portion and the inner blade portion to move efficiently relative to the workpiece and enabling a space-saving device.

[0013] It is preferable that the outer blade portion has an adjustment mechanism for moving closer to and farther away from the inner blade portion, which allows the position of the outer blade portion in contact with the workpiece to be adjusted to an optimum position depending on the thickness of the workpiece, and allows the outer blade portion to be moved closer to the workpiece even if the outer diameter of the outer blade portion decreases due to wear caused by long-term use, making the device highly versatile and convenient. [Effects of the Invention]

[0014] In the pipe cutting machine of the present invention, the outer diameter side and inner diameter side of the workpiece press against each other to form a cutting section along the longitudinal direction of the workpiece, thereby cutting the workpiece. Therefore, even thick workpieces can be cut, and the machine can be applied to workpieces of various thicknesses. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a simplified perspective view showing a tube cutting machine of the present invention; [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. 2 is a plan view showing a part of the pipe cutting machine. [Figure 5] FIG. 2 is an enlarged front view showing an inner blade portion and an outer blade portion that constitute the pipe cutting machine. [Figure 6] 6 is a cross-sectional view taken along the line AA in FIG. 5. [Figure 7] 5A to 5C are diagrams showing the order in which the inner blade portion and the outer blade portion of the pipe cutting machine are inserted into a pipe. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

[0017] FIG. 1 shows a pipe cutting machine of the present invention. This pipe cutting machine includes a cutting mechanism 1 that cuts a tubular object along its longitudinal direction, and a holding mechanism 2 that holds the object along the cutting direction. In this embodiment, the object 3 is a pipe used to distribute contaminated materials, including radioactive materials, in a nuclear power plant, for example. By cutting the pipe along its longitudinal direction (the vertical direction in FIG. 1), it is possible to measure the contamination level of radioactive materials in the pipe and decontaminate the inner surface of the pipe.

[0018] 2 and 3, the holding mechanism 2 is composed of a flat plate-like portion 4 and a pipe holding portion 5. The pipe holding portion 5 is provided in approximately the center of the plate-like portion 4 and is composed of a mounting plate 6 that is placed on the upper surface of the plate-like portion 4, and a pair of vertical plates 8 that stand vertically from the mounting plate 6. A cylindrical portion 7 is provided between the pair of vertical plates 8, and by inserting the end of the pipe 3 into a hole 7a on the inner diameter side of the cylindrical portion 7, the pipe 3 can be held upright.

[0019] As shown in FIGS. 2 and 3, the cutting mechanism 1 is composed of a drive unit 10 and a cutting unit 11. In this embodiment, as shown in FIGS. 1 and 4, the drive unit 10 is composed of four ball screw mechanisms 12a, 12b, 12c, and 12d. As shown in FIGS. 2 to 4, the ball screw mechanisms 12a to 12d are composed of spline shafts 13a to 13d and nuts 14a to 14d. The nuts 14a to 14d are inserted inside housings 15a to 15d, and as shown in FIG. 4, sprockets 16a to 16d are provided on flanges on the upper parts of the nuts. An endless chain 17 is wound around each of the sprockets 16a to 16d, and a motor (not shown) applies a rotational force to the nuts 14a to 14d, thereby driving the ball screw mechanisms 12a to 12d. Each of the housings 15a to 15d is fixed to the upper surface of a support plate 18, and the four nuts 14a to 14d are capable of vertically moving the spline shafts 13a to 13d together.

[0020] 4, a hole 19 is provided in the approximate center of the support plate 18, and a rod-shaped body 20 is inserted into this hole 19. The rod-shaped body 20 is fixed to the support plate 18 via a fixing block 21 fixed on the upper surface of the support plate 18 between the four housings 15a to 15d.

[0021] The rod-shaped body 20 has an outer diameter smaller than the inner diameter of the pipe 3 (see FIG. 6 ). That is, when the rod-shaped body 20 is inserted into the pipe 3, the outer diameter surface 24 of the rod-shaped body 20 is positioned radially inward relative to the inner diameter surface of the pipe 3, forming a gap between the rod-shaped body 20 and the pipe 3. As shown in FIG. 6 , a pair of shafts 22a, 22b are provided inside the rod-shaped body 20 at positions 180 degrees symmetrical thereto, and feed rollers 23a, 23b are rotatably provided on the shafts 22a, 22b via bearings (not shown), respectively. The feed rollers 23a, 23b protrude radially outward beyond the outer diameter surface 24 of the rod-shaped body 20. As a result, when the rod-shaped body 20 is inserted into the pipe 3, only the feed rollers 23a, 23b come into contact with the pipe 3. The feed rollers 23a, 23b are rotated by the relative movement of the pipe 3 while in contact with the pipe 3.

[0022] 5, the cutting unit 11 of the cutting mechanism 1 is provided inside and outside the rod-shaped body 20. That is, the cutting unit 11 includes a first inner blade portion 25a and a second inner blade portion 25b that bite into the pipe 3 from its inner diameter side toward its outer diameter, and a first outer blade portion 26a and a second outer blade portion 26b that are provided on the underside of the support plate 18, on the outer diameter side of the inner blade portions 25a, 25b, and bite into the pipe 3 from its outer diameter side toward its inner diameter.

[0023] As shown in Fig. 6, the rod-shaped body 20 has a pair of shafts 27a, 27b mounted 180 degrees symmetrically on its inner side. A first inner cutting edge 25a and a second inner cutting edge 25b, which are circular blades, are rotatably mounted on the shafts 27a, 27b via bearings (not shown). The inner cutting edges 25a, 25b contact the pipe 3 and are rotated by the relative movement of the pipe 3. As shown in Fig. 6, the inner cutting edges 25a, 25b have a tapered shape that protrudes outward from the axial center, and the leading edges 28a, 28b of the inner cutting edges 25a, 25b are slightly rounded. This reduces stress concentration at the contact points of the inner cutting edges 25a, 25b and prevents cracking of the cutting edges, thereby extending the life of the inner cutting edges 25a, 25b.

[0024] 5 and 6, a pair of support pieces 30a, 30b are provided on the underside of the support plate 18 at positions symmetrical with respect to the rod-shaped body 20. The support pieces 30a, 30b hold shafts 31a, 31b, respectively, and a first outer blade portion 26a and a second outer blade portion 26b, which are circular blades, are rotatably attached to the shafts 31a, 31b via bearings (not shown). The outer blade portions 26a, 26b abut against the pipe 3 and are rotated by the relative movement of the pipe 3. The outer blade portions 26a, 26b have the same configuration as the inner blade portions 25a, 25b, and have a tapered shape that protrudes outward from the axial center, and the leading edges 33a, 33b of the outer blade portions 26a, 26b are slightly rounded. This allows stress to be concentrated at the points where the outer cutting edges 26a, 26b come into contact, and also makes it possible to prevent cracks in the cutting edge, thereby extending the life of the outer cutting edges 26a, 26b.

[0025] The first inner blade portion 25a and the first outer blade portion 26a face each other, and the second inner blade portion 25b and the second outer blade portion 26b face each other. That is, the first inner blade portion 25a and the first outer blade portion 26a are arranged such that the distance between their respective leading edges 28a, 33a is closer than the thickness of the pipe 3 to be cut. The second inner blade portion 25b and the second outer blade portion 25b are arranged such that the distance between their respective leading edges 28b, 33b is closer than the thickness of the pipe 3 to be cut. As a result, the pipe 3 is sandwiched between the first outer blade portion 25a and the first inner blade portion 26a, and also between the second outer blade portion 26a and the second inner blade portion 26b. As a result, stress is concentrated in the inner diameter direction at the outer blade portions 26a, 26b on the outer diameter side of the pipe 3, causing the outer diameter side of the pipe 3 to be crushed and plastically deformed. At the opposite positions, stress is concentrated in the inner diameter direction at the inner blade portions 25a, 25b on the inner diameter side of the pipe 3, causing the inner diameter side of the pipe 3 to be crushed and plastically deformed. In this manner, the outer diameter side and the inner diameter side of the outer blade portions 26a, 26b and the inner blade portions 25a, 25b press against each other, forming a cut portion. This cut portion is formed along the longitudinal direction of the pipe 3, allowing the pipe 3 to be cut. Furthermore, the outer diameter side and the inner diameter side of the outer blade portion 26a (26b) and the inner blade portion 25a (25b) press against each other, causing stress to be offset inside and outside the pipe 3, eliminating the need for reaction force support.

[0026] As shown in Fig. 5, the support pieces 30a, 30b are provided with adjustment mechanisms 34a, 34b that move the outer blade portions 26a, 26b toward and away from the inner blade portions 25a, 25b. In this embodiment, the adjustment mechanisms 34a, 34b are configured using bolt and nut mechanisms (adjuster bolts). That is, by rotating a nut that threads onto the adjuster bolt extending horizontally, the support piece 30a (30b) and the outer blade portion 26a (26b) move together in the horizontal direction (left and right in the illustrated example).

[0027] Next, a method for cutting a pipe using this pipe cutting machine will be described. First, as shown in Figure 1, the end of the pipe 3 is inserted into the pipe holding portion 5 of the holding mechanism 2, thereby holding the pipe 3 in an upright position. In this case, the upper end edge of the pipe 3 is located below the lower end of the rod-shaped body 20, as shown in Figures 1 and 7(a).

[0028] By driving the drive unit 10, the nuts 14a to 14d are rotated, and the support plate 18 is moved downward along the spline shafts 13a to 13d. That is, as shown by the arrows in FIG. 1, the support plate 18, the rod-shaped body 20 (inner blade portions 25a, 25b), and the outer blade portions 26a, 26b move downward together.

[0029] 7(b), the tip of the rod-shaped body 20 is inserted into the inner diameter side of the pipe 3, and the pipe 3 enters between the inner blade portions 25a, 25b and the outer blade portions 26a, 26b of the rod-shaped body 20. At this time, the inner diameter side of the pipe 3 abuts against the inner blade portions 25a, 25b, and the outer diameter side of the pipe 3 abuts against the outer blade portions 26a, 26b, and the pipe 3 is sandwiched between the inner blade portions 25a, 25b and the outer blade portions 26a, 26b. Because the outer diameter of the rod-shaped body 20 is smaller than the inner diameter of the pipe 3, when the rod-shaped body 20 is inserted into the pipe 3, the outer diameter surface 24 of the rod-shaped body 20 is positioned more inward than the inner diameter surface of the pipe 3, and a gap is formed between the rod-shaped body 20 and the pipe 3 (see FIG. 6). At this time, the feed rollers 23a, 23b provided on the rod-shaped body 20 abut against the pipe 3.

[0030] When the inner blade portions 25a, 25b and the outer blade portions 26a, 26b come into contact with the pipe 3, stress is concentrated in the inner diameter direction by the outer blade portions 26a, 26b on the outer diameter side of the pipe 3, causing the outer diameter side of the pipe 3 to be crushed and plastically deformed, forming a bite portion (a portion where the pipe 3 is thinned or cut). Meanwhile, stress is concentrated in the outer diameter direction by the inner blade portions 25a, 25b on the inner diameter side of the pipe 3, causing the outer diameter side of the pipe 3 to be crushed and plastically deformed, forming a bite portion. In this manner, the inner blade portions 25a, 25b and the outer blade portions 26a, 26b press against each other on the outer diameter side and the inner diameter side, connecting the bite portion on the outer diameter side and the bite portion on the inner diameter side to form a cut portion. At this time, stress is offset between the inner blade portions 25a, 25b and the outer blade portions 26a, 26b inside and outside the pipe 3, eliminating the need for reaction force support. In this embodiment, a pair of inner blade portions 25a, 25b and outer blade portions 26a, 26b are provided at positions symmetrical to the rod-shaped body 20, so that two cutting portions are formed at positions approximately 180° apart along the circumferential direction.

[0031] 7(c), the support plate 18, the rod-shaped body 20 (inner blade portions 25a, 25b), and the outer blade portions 26a, 26b move further downward. That is, the relative movement of the pipe 3 causes the feed rollers 23a, 23b, the inner blade portions 25a, 25b, and the outer blade portions 26a, 26b to rotate, and the feed rollers 23a, 23b, the inner blade portions 25a, 25b, and the outer blade portions 26a, 26b move along the longitudinal direction of the pipe 3, thereby forming two cut portions continuously along the longitudinal direction of the pipe 3, and the pipe 3 can be cut.

[0032] In this case, the inner blade portions 25a, 25b and the outer blade portions 26a, 26b are circular blades that rotate in response to the relative movement of the pipe 3, so that the contact points with the pipe 3 are uniform, thereby extending the life of the blade portions. Furthermore, the pipe 3 can be guided along its longitudinal direction, allowing the pipe 3 to be plastically deformed while accurately moving. Furthermore, by providing the feed rollers 23a, 23b that rotate in response to the relative movement of the pipe 3, the rod-shaped body 20 can move smoothly along the inner diameter side of the pipe 3 while maintaining a stable posture while being supported by the feed rollers 23a, 23b inside the pipe 3. Furthermore, the contact surface between the pipe 3 and the rod-shaped body 20 can be reduced, thereby reducing the driving energy of the rod-shaped body 20. Furthermore, wear of the rod-shaped body 20 due to contact with the pipe 3 can be reduced, and the generation of frictional heat can be suppressed, thereby extending the life of the device.

[0033] The adjustment mechanisms 34a, 34b allow the horizontal positions of the outer blade portions 26a, 26b to be changed. For example, if the outer diameter of the outer blade portions 26a, 26b decreases due to wear caused by long-term use, the outer blade portions 26a, 26b can be moved closer to the pipe 3, or if cutting a thick pipe 3, the outer blade portions 26a, 26b can be moved away from the pipe 3. This allows the outer blade portions 26a, 26b to be positioned optimally so that they come into contact with the pipe 3, making the device highly versatile and convenient.

[0034] In the pipe cutting machine of the present invention, the outer diameter side and inner diameter side of the pipe 3 press against each other to form a cutting section along the longitudinal direction of the workpiece, making it possible to cut even large pipes 3 with a pipe thickness of 4 mm or more, and making it applicable to workpieces of various thicknesses.

[0035] Although the above describes an embodiment of the present invention, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the embodiment, the cutting mechanism 1 is moved while the holding mechanism 2 is placed on standby. However, the cutting mechanism 1 may be placed on standby while the holding mechanism 2 is moved, or both the cutting mechanism 1 and the holding mechanism 2 may be moved. In the embodiment, the cutting mechanism 1 is disposed above the holding mechanism 2 and moved vertically. However, the cutting mechanism 1 and the holding mechanism 2 may be disposed horizontally and the cutting mechanism 1 may be moved horizontally. In the embodiment, the drive unit 10 is a ball screw mechanism 12. However, various mechanisms capable of reciprocating motion, such as a cylinder mechanism or a linear motor mechanism, may be used. The number of outer blades, inner blades, and feed rollers may each be any number. [Example]

[0036] A pipe cutting machine having the configuration of the present invention was used to cut stainless steel pipes of various thicknesses. Specifically, an experiment was conducted to cut stainless steel using a pipe cutting machine comprising: a rod-shaped body inserted into the inner diameter of the pipe; an inner blade portion, which is a circular blade attached to the rod-shaped body and cuts into the pipe from the inner diameter side toward the outer diameter; and an outer blade portion, which is a circular blade attached to the outer diameter side of the inner blade portion and cuts into the pipe from the outer diameter side toward the inner diameter. The outer blade portion and the inner blade portion press against each other while sandwiching the pipe and moving the pipe relative to each other along its longitudinal direction. The outer diameter of the rod-shaped body was assumed to be smaller than the inner diameter of the pipe, and a feed roller was attached to the rod-shaped body that abutted against the inner diameter side of the pipe and rotated in response to the relative movement of the pipe. This enabled cutting of stainless steel pipes with thicknesses up to 10.7 mm. Furthermore, compared to an average power consumption of 7.0 A for a conventional device, the power consumption of the device in this example was an average of 5.7 A, demonstrating a reduction in power consumption. [Explanation of symbols]

[0037] 1 Cutting mechanism 2 Retention mechanism 3 Piping 20 Rod-shaped body 23a, 23b Feed rollers 24 Outer diameter surface 25a, 25b Inner cutting edge 26a, 26b Outer edge Adjustment mechanisms 34a and 34b

Claims

1. A pipe cutting machine comprising a cutting mechanism that cuts a tubular object along its longitudinal direction, and a holding mechanism that holds the object so as to extend in a vertical direction, the cutting mechanism being disposed above the holding mechanism, and the cutting mechanism being moved downward to bring the cutting mechanism closer to the object and cut it; The cutting mechanism includes a rod-shaped body having an outer diameter smaller than an inner diameter of the object to be cut and inserted into the inner diameter side of the object to be cut; a first inner cutting edge portion and a second inner cutting edge portion provided on each of the shafts, the shafts being symmetrically provided on the rod-shaped body with respect to an axis of the rod-shaped body; a pair of feed rollers respectively provided on the rod-shaped body at positions symmetrical with respect to the axis of the rod-shaped body, the feed rollers being driven to rotate by the relative movement of the workpiece; a first outer cutting edge portion provided on the shaft opposite the first inner cutting edge portion and a second outer cutting edge portion provided on the shaft opposite the second inner cutting edge portion, the first outer cutting edge portion being provided on the shaft radially outer than the rod-shaped body; The first inner cutting portion, the second inner cutting portion, the first outer cutting portion, and the second outer cutting portion have tapered portions that rise and protrude toward the outer diameter side of the shafts only at axial central portions of the shafts on which the first inner cutting portion is provided, the shaft on which the second inner cutting portion is provided, the shaft on which the first outer cutting portion is provided, and the shaft on which the second outer cutting portion is provided, the tapered portion of the first outer blade portion and the tapered portion of the first inner blade portion press against each other while sandwiching the object to be cut, the first inner blade portion bites into the object from its inner diameter side in a direction toward its outer diameter, thereby plastically deforming the object to be cut, and the first outer blade portion bites into the object from its outer diameter side in a direction toward its inner diameter, thereby plastically deforming the object to form a cut portion; the tapered portion of the second outer blade portion and the tapered portion of the second inner blade portion press against each other while sandwiching the object to be cut, the second inner blade portion bites into the object from its inner diameter side toward its outer diameter, plastically deforming the object to be cut, and the second outer blade portion bites into the object from its outer diameter side toward its inner diameter, plastically deforming the object to form a cut portion; A pipe cutting machine characterized in that the feed roller contacts the workpiece from the inner diameter side thereof while the rod-shaped body moves along the inner diameter side of the workpiece in the longitudinal direction, thereby forming the two cut portions continuously along the longitudinal direction of the pipe and cutting the pipe.

2. A pipe cutting machine as described in Claim 1, characterized in that the first outer blade portion, the second outer blade portion, the first inner blade portion, and the second inner blade portion are circular blades that rotate in response to the relative movement of the workpiece.

3. 2. The tube cutting machine according to claim 1, further comprising: one adjustment mechanism for moving the first outer cutting edge closer to and away from the first inner cutting edge; and another adjustment mechanism for moving the second outer cutting edge closer to and away from the second inner cutting edge.

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