Cutting device for skirt edge in pipe

Abstract

The invention discloses an in-pipe skirt edge cutting device, and belongs to the technical field of pipeline engineering, the in-pipe skirt edge cutting device comprises a plurality of telescopic cylinders which are circumferentially arranged and move in the radial direction of a center pipe, each telescopic cylinder is matched with a cutting assembly, and each cutting assembly comprises a bottom plate located on the corresponding telescopic cylinder and a tool bit located on the bottom plate; each bottom plate comprises a first linear part and a second linear part fixedly connected with the middle of the first linear part, the second linear parts are arranged in the axial direction of the central pipe, the tool bit is provided with a blade part extending in the circumferential direction of the central pipe, and the two ends of any first linear part directly face the second linear parts of the two adjacent bottom plates; and in the radial movement process of the telescopic cylinder, the swept areas are intersected or connected when the two adjacent cutting edge parts move in the axial direction of the central pipe. When the device is used, all the cutting edge parts are connected end to end to form a closed ring, the whole skirt edge can be integrally cut by axially moving the whole device, the influence of large pipeline elongation on the cutting efficiency is reduced, the skirt edge can be rapidly cut, and meanwhile operation is easy.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline engineering, in particular to the technical field of pipeline construction, and specifically relates to a device for cutting inner skirt of a pipe. Background Art

[0002] PE pipes or fiber reinforced composite pipes have internal skirts when they are butt-jointed, which affects pipe cleaning and increases medium resistance, limiting their application in large-diameter high-pressure oil and gas transportation. Therefore, it is of practical significance to remove the skirts produced by hot-melt butt-jointing inside the pipe.

[0003] At present, there are some cleaning devices for removing protrusions (such as scale, weld nodules, etc.) on the inner wall of the pipeline. These devices usually include a central shaft and use a tool or a friction block as a cleaning element. The end of the shaft is connected to a radial telescopic mechanism, and the cleaning element is installed at the end of the radial telescopic mechanism. When working, the radial telescopic mechanism extends outward, so that the tool or friction block is close to the inner wall of the pipeline, and then the central shaft rotates, driving the cleaning element to rotate on the inner wall of the pipeline, so as to cut or grind the skirt in a layer-by-layer peeling or overall grinding manner. The rotary cutting, grinding and other methods mainly used by these devices are difficult to be used for the butt joint construction of the inner lining of PE pipes and fiber-reinforced flexible composite pipes. The main reason is that PE pipe materials are completely different from metal materials, and they have strong toughness and ductility. They are prone to deformation during construction, which reduces the pressure of the cleaning element on the contact part after contacting the pipeline. The depth of the tool inserted into the skirt is insufficient, and the friction of the friction block on the skirt is reduced, thereby reducing the efficiency of cutting / wear. Therefore, it is necessary to use a blade for overall cutting to overcome the effect of its phase change on cutting. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a tube inner skirt cutting tool for removing the hot-melt butt skirt of PE tubes and fiber-reinforced composite tubes.

[0005] In order to achieve the above object, the solution provided by the present invention is as follows:

[0006] A tube inner skirt cutting tool, comprising:

[0007] An axial telescopic assembly, the axial telescopic assembly comprising a center tube;

[0008] A radial telescopic assembly, the radial telescopic assembly comprising a plurality of telescopic cylinders arranged circumferentially and capable of moving only radially along the central tube;

[0009] A radial drive assembly is used to push the telescopic tube to move radially along the central tube;

[0010] The cutting assembly is used to cut the inner skirt of the pipe. Each telescopic cylinder carries a cutting assembly, and each cutting assembly includes:

[0011] The bottom plate is carried on the telescopic tube, and the bottom plate is a T-shaped structure, including a first straight portion and a second straight portion fixedly connected to the middle portion of the first straight portion, wherein the second straight portion is arranged along the axial direction of the central tube;

[0012] A support rod, one end of which is fixed to a side of the bottom plate away from the telescopic cylinder;

[0013] A cutter head fixed to the end of the support rod away from the bottom plate, the cutter head is an arc-shaped plate structure, the curvature of the cutter head matches the curvature of the inner wall of the pipe, and the cutter head is provided with a blade portion extending along the circumferential direction of the center pipe, which is used to cut the skirt inside the pipe when the cutter head moves axially along the center pipe;

[0014] Among them, the first straight portions of the base plates of two adjacent cutting assemblies are arranged in opposite directions, so that the two ends of the first straight portion of any base plate are opposite to the second straight portions of the two adjacent base plates; when the telescopic tube is extended and retracted along the radial direction of the center tube, it will drive the cutter head to extend and retract along the radial direction of the center tube, and after being extended, the areas swept by the adjacent blade portions when they move axially along the center tube intersect or are connected; the axial telescopic assembly is used to push the cutting assembly to move axially along the center tube.

[0015] As a specific embodiment of the present invention, each base plate includes three cutter heads, and the three cutter heads are arranged in parallel in a T-shape, wherein two cutter heads are located on a first straight portion, and another cutter head is located on a second straight portion, and the cutter head located on the second straight portion is spaced a certain distance from the cutter head located on the first straight portion, and the areas swept by the blade portions of the three cutter heads when they move axially along the center tube intersect or connect.

[0016] As a specific embodiment of the present invention, the cutting assembly further includes:

[0017] An end cover fixedly connected to one end of the telescopic cylinder facing the bottom plate;

[0018] A slider movably arranged in the telescopic cylinder, the slider is a stepped shaft structure and one end of the slider passes through the end cover and is fixedly connected to the bottom plate;

[0019] A spring that pushes the slider to move axially along the telescopic cylinder toward the end cover;

[0020] A guide rod having one end fixedly connected to the end cover and the other end extending along the axial direction of the telescopic cylinder;

[0021] A guide rod hole located on the bottom plate and extending along the axial direction of the telescopic cylinder;

[0022] One end of the guide rod passes through the guide rod hole and is clearance-matched with the guide rod hole.

[0023] As a specific embodiment of the present invention, the radial telescopic assembly further includes:

[0024] A sliding sleeve is sleeved on the outer wall of the central tube, and the inner edge of the sliding sleeve extends along the axial direction of the sliding sleeve to form a cylindrical section;

[0025] An inner ring sleeved on the outer wall of the cylindrical section;

[0026] An outer ring with one side fixedly connected to the outer edge of the sleeve and the other side extending axially along the sleeve; all telescopic cylinders are arranged along the circumference of the outer ring and each telescopic cylinder can only move radially along the outer ring;

[0027] Connecting rod, each telescopic cylinder corresponds to a connecting rod, one end of each connecting rod is hinged to the inner ring, and the other end is hinged to the corresponding telescopic cylinder, and the hinge axis between the connecting rod and the inner ring and the hinge axis between the connecting rod and the telescopic cylinder are parallel to the center line of the sliding sleeve.

[0028] As a specific implementation of the present invention, the radial drive assembly is used to drive the inner ring and the outer ring to rotate relative to each other.

[0029] Further, the radial drive assembly includes:

[0030] A cylinder with one end hinged to the outer ring and the other end of the cylinder being free;

[0031] An inner connecting rod having one end hinged to the free end of the cylinder and the other end hinged to the inner ring;

[0032] An outer connecting rod having one end hinged to the free end of the cylinder and the other end hinged to the outer ring;

[0033] The hinge points of the cylinder and the outer ring, the hinge points of the inner connecting rod and the inner ring, and the hinge points of the outer connecting rod and the outer ring are arranged in a triangle, so that when the cylinder is extended or retracted, the inner connecting rod and the outer connecting rod are pushed to move, thereby causing the inner ring and the outer ring to rotate relatively.

[0034] Furthermore, the radial drive assembly also includes a disc-shaped cover plate, which is located on a side of the inner ring and the outer ring away from the sleeve and is fixedly connected to the inner ring for isolating the mechanical components between the inner ring and the outer ring from the outside.

[0035] As a specific embodiment of the present invention, the axial telescopic assembly further includes:

[0036] Two blind plates are fixed in the center tube at intervals and block the inner passage of the center tube. The side wall of the center tube is provided with a longitudinal slot extending along the axial direction of the center tube. Along the axial direction of the center tube, the longitudinal slot is located on one side of the two blind plates.

[0037] A piston movably arranged between the two blind plates and sealedly connected to the inner wall of the center tube;

[0038] A piston rod having one end connected to the piston and the other end passing through a blind plate adjacent to the longitudinal slot;

[0039] A connecting pin passes through the longitudinal slot, one end of which is fixedly connected to the piston rod, and the other end of which is fixedly connected to the cylindrical section of the telescopic cylinder.

[0040] Furthermore, the axial telescopic assembly also includes a movable ring movably disposed in the central tube and fixedly connected to the piston rod, and the connecting pin is fixedly connected to the movable ring.

[0041] A method for cutting the inner skirt of a pipe, using the inner skirt cutting device to cut the inner skirt of a pipe, comprising the following steps:

[0042] The inner skirt cutting device is placed in the pipeline, and the inner ring and the outer ring are pushed to rotate relative to each other by charging the air cylinder, so as to drive the telescopic cylinder to extend to the limit position along the radial direction of the central pipe, and the cutter head is close to the inner wall of the pipeline, and the blade parts of all the cutter heads are connected end to end to form a closed ring;

[0043] The center tube is fixed in the pipeline, and gas is filled into the sealing cavity between the piston and the blind plate to push the piston to move axially along the center tube, thereby driving the cutter head to move axially along the pipeline to cut the entire skirt.

[0044] Compared with the existing technology, it has the following advantages:

[0045] The present invention can cut off the skirt inside the pipe. The present invention adopts a special cutting assembly. When in use, it is only necessary to move the cutting assembly along the axial direction of the pipe. There is no need to provide torque like the traditional pipe internal cleaning device. Therefore, the device is easy to operate. At the same time, when the present invention is cutting, the blades of all the cutter heads are connected end to end to form a closed ring. The entire skirt can be cut as a whole by moving the entire device axially, which reduces the influence of the high toughness and large elongation of the pipe material on the cutting efficiency, and can quickly cut the skirt. The extrusion force between the cutting assembly and the inner wall of the pipe is determined by the elastic force of the spring and the gravity of the cutting assembly itself, and the relevant extrusion force is controllable; the cutter head has radial activity in the PE pipe, which can automatically adapt to the error of the inner diameter of the pipe and the installation deviation of the device, to ensure that the cutter head can fit perfectly with the inner wall of the pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A cross-sectional view of a specific embodiment of the tube inner skirt cutting device of the present invention;

[0047] Figure 2 for Figure 1 A cross-sectional view of the combined structure of the radial telescopic assembly and the cutting assembly;

[0048] Figure 3 for Figure 1 A schematic diagram of the structure of the radial drive assembly;

[0049] Figure 4 for Figure 1 Schematic diagram of the structure of the middle cutter head;

[0050] Figure 5 for Figure 1Schematic diagram of the combined arrangement of the two cutting assemblies;

[0051] In the figure: blind plate 11; center tube 12; piston 13; piston rod 14; connecting pin 15; movable ring 16; inner ring 21; cover plate 22; connecting rod 23; sliding sleeve 24; outer ring 25; telescopic cylinder 26; slider 31; end cover 32; guide rod 33; bottom plate 34; support rod 35; cutter head 36; outer lug A41; inner lug 42; inner connecting rod 43; outer connecting rod 44; cylinder 45; outer lug B46. DETAILED DESCRIPTION

[0052] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0053] Example

[0054] Please refer to Figure 1 to Figure 5 , which shows the structure of a specific embodiment of the tube skirt cutting device of the present invention. The tube skirt cutting device of the present invention comprises an axial telescopic assembly, a radial telescopic assembly, a radial drive assembly and a cutting assembly, wherein the axial telescopic assembly comprises a central tube 12; the radial telescopic assembly comprises a plurality of telescopic cylinders 26 arranged circumferentially and capable of only moving radially along the central tube 12; the radial drive assembly provides power to the telescopic assembly, thereby pushing the telescopic cylinders 26 to move radially along the central tube 12; each telescopic cylinder 26 carries a cutting assembly for cutting the inner skirt of the pipe.

[0055] Please refer to Figure 1In some embodiments, the axial telescopic assembly includes a blind plate 11, a central tube 12, a piston 13, a piston rod 14 and a connecting pin 15. The central tube 12 is a cylindrical straight tube. There are two blind plates 11, both of which are disc-shaped. The two blind plates 11 are fixed in the central tube by pins to block the internal channel of the central tube 12. The two blind plates 11 are spaced a certain distance apart, thereby separating a space in the central tube 12 for the axial movement of the piston 13. The side wall of the central tube 12 is provided with a longitudinal slot extending along the axial direction of the central tube 12, and one of the blind plates 11 is located between the other blind plate 11 and the longitudinal slot along the axial direction of the central tube 12; the piston 13 is located between the two blind plates 11 and is sealed with the inner wall of the central tube 12. Therefore, a sealed cavity is formed between the piston 13 and the blind plate 11 near the left side. By filling the cavity with fluid, such as water or air, the piston 13 can be driven to move axially along the central tube 12. A through hole matching the size of the piston rod 14 is provided in the middle of the blind plate 11 adjacent to the longitudinal slot. One end of the piston rod 14 is fixedly connected to the piston 13, and the other end extends axially along the center tube 12 and passes through the blind plate 11 adjacent to the longitudinal slot. The piston rod 14 is matched with the clearance of the middle through hole of the blind plate 11, so that the blind plate 11 is used to straighten the piston rod 14. The connecting pin 15 passes through the longitudinal slot, and one end of it is fixedly connected to the radial telescopic assembly outside the center tube 12, and the other end is fixedly connected to the piston rod 14, so that the radial telescopic assembly can be driven to move axially along the center tube 12 by driving the piston 13. In some embodiments, in order to improve the stability of the piston rod 14 during the movement, the axial telescopic assembly also includes a movable ring 16 located in the center tube 12. The movable ring 16 is a circular ring structure and is fixed to the end of the piston rod 14 by a round nut. The connecting pin 15 is fixedly connected to the movable ring 16. This arrangement prevents the piston rod 14 from swinging radially along the center tube 12 through the combined action of the blind plate 11 and the movable ring 16, so that the piston rod 14 can only move axially during the movement, which makes the force on the side wall of the piston 13 more uniform, avoids the problem of eccentric wear on the bottom of the piston 13 under the action of its own weight, and thus increases the service life of the piston 13.

[0056] Please combine Figure 1 and Figure 2The radial telescopic assembly also includes an inner ring 21, a connecting rod 23, a sleeve 24, an outer ring 25 and a telescopic cylinder 26, wherein the sleeve 24 is disc-shaped and sleeved on the outer wall of the central tube 12, and the inner edge of the sleeve 24 extends along the axial direction of the sleeve to form a cylindrical section; the inner ring 21 is annular as a whole and sleeved on the outer wall of the cylindrical section, so that the two can rotate relative to each other; one side of the outer ring 25 is fixedly connected to the outer edge of the sleeve 24, and the other side extends along the axial direction of the sleeve 24, so that an annular groove area is formed between the outer ring 25 and the inner ring 21 for accommodating the connecting rod 23; multiple rings are arranged on the circumference of the outer ring 25 Through holes are arranged along the radial direction of the central tube 12. There are multiple telescopic cylinders 26, each of which is inserted into a corresponding through hole. Therefore, all telescopic cylinders 26 are arranged along the circumference of the outer ring 25 and each telescopic cylinder 26 can only move radially along the outer ring 25. There are also multiple connecting rods 23, each of which corresponds to one connecting rod 23. One end of each connecting rod 23 is hinged to the inner ring 21 and the other end is hinged to the corresponding telescopic cylinder 26. The hinge axis of the connecting rod 23 and the inner ring 21 and the hinge axis of the connecting rod 23 and the telescopic cylinder 26 are parallel to the center line of the sliding sleeve 24. Therefore, when the inner ring 21 and the outer ring 25 rotate relatively, the connecting rod 23 moves, thereby pushing the telescopic cylinder 26 to move radially along the central tube 12. In some embodiments, a cover plate 22 is also provided. The cover plate 22 is disc-shaped as a whole and is placed on the side of the inner ring 21 and the outer ring 25 away from the sleeve 24 and fixedly connected to the inner ring 21 to separate the mechanical components between the inner ring 21 and the outer ring 25 from the outside.

[0057] In the present invention, the radial drive assembly is used to drive the inner ring 21 and the outer ring 25 to rotate relative to each other. In some embodiments, the inner ring 21 can be driven to rotate by a conventional drive structure such as a motor and a gear. In some embodiments, the same power source can be used as the axial telescopic assembly, such as Figure 3 As shown, the radial drive assembly includes an inner connecting rod 43, an outer connecting rod 44 and a cylinder 45, wherein one end of the cylinder 45 is hinged to the outer ring 25 and the other end is a free end; one end of the inner connecting rod 43 is hinged to the free end of the cylinder 45 and the other end is hinged to the inner ring 21; one end of the outer connecting rod 44 is hinged to the free end of the cylinder 45 and the other end is hinged to the outer ring 25; the hinge points of the cylinder 45 and the outer ring 25, the hinge points of the inner connecting rod 43 and the inner ring 21, and the hinge points of the outer connecting rod 44 and the outer ring 25 are arranged in a triangle, so that when the cylinder 45 is extended or retracted, the inner connecting rod 43 and the outer connecting rod 44 are pushed to move, thereby causing the inner ring 21 and the outer ring 25 to rotate relative to each other. Of course, due to the large difference in diameter between the inner ring 21 and the outer ring 25, support ears can also be provided to facilitate the formation of a triangular arrangement, such as Figure 3As shown, the outer lug A41 is fixed to the edge of the outer ring 25, the inner lug 42 is fixed to the edge of the inner ring 21, the outer lug B46 is fixed to the edge of the outer ring 25, one end of the inner connecting rod 43 is hinged to the inner lug 42, one end of the outer connecting rod 44 is hinged to the outer lug A41, one end of the cylinder 45 is hinged to the outer lug B46, and the outer lug A41, the inner lug 42, and the outer lug B46 are arranged in a triangle.

[0058] In the present invention, each telescopic cylinder 26 carries a cutting assembly for cutting the inner skirt of the pipeline. Each cutting assembly includes a bottom plate 34, a support rod 35 and a cutter head 36. The bottom plate 34 is carried on the telescopic cylinder 26. The bottom plate 34 is a T-shaped structure, including a first straight portion and a second straight portion, wherein one end of the second straight portion is fixedly connected to the middle of the first straight portion, and the second straight portion is arranged along the center line direction of the center pipe 12; one end of the support rod 35 is fixed to the side of the bottom plate 34 away from the telescopic cylinder 26; the cutter head 36 is fixed to the end of the support rod 35 away from the bottom plate 34, and the cutter head 36 is an arc plate structure. The curvature of the center tube 12 matches the curvature of the inner wall of the pipe, and the cutter head 36 is provided with a blade portion extending along the circumferential direction of the center tube 12, which is used to cut the skirt in the pipe when the cutter head 36 moves axially along the center tube 12; wherein, the first straight portions in two adjacent cutting assemblies are arranged in opposite directions, so that the two ends of the first straight portion of any base plate 34 are directly opposite to the second straight portions of the two adjacent base plates 34; when the telescopic cylinder 26 is radially extended and retracted along the center tube 12, it will drive the cutter head 36 to be radially extended and retracted along the center tube 12, and after being extended, the areas swept by the adjacent blade portions when moving along the center line of the center tube 12 intersect or connect, thereby ensuring that the skirt is cut off as a whole. In some embodiments, such as Figure 4 , 5 As shown, each base plate 34 includes three cutter heads 36, and the three cutter heads 36 are arranged in parallel in a V-shape, wherein two cutter heads 36 are located on the first straight portion, and another cutter head 36 is located on the second straight portion, and the cutter heads 36 located on the second straight portion are spaced a certain distance from the cutter heads 36 located on the first straight portion, and the areas swept by the blades of the three cutter heads 36 when moving along the center line of the center tube 12 intersect or connect. In some examples, the cutting assembly further includes a slider 31, an end cap 32, a spring and a guide rod 33, such as Figure 3 As shown, the end cover 32 is fixedly connected to one end of the telescopic cylinder 26 facing the bottom plate 34 by means of threaded connection, bolt connection, etc.; the slider 31 is movably arranged in the telescopic cylinder 26, and the slider 31 is a stepped shaft structure and one end of which passes through the end cover 32 and is fixedly connected to the bottom plate 34, so that the bottom plate 34 can be pushed to move radially by the slider 31; the spring is arranged in the telescopic cylinder 26, one end of which contacts the slider 31 and the other end contacts the telescopic cylinder 26, pushing the slider 31 to move axially toward the end cover 32 along the telescopic cylinder 26; as shown in FIG. Figure 2As shown, the guide rod 33 is fixed to the end cover 32 and extends axially along the telescopic cylinder 26. The base plate 34 is provided with a guide rod hole at a position corresponding to the guide rod 33. The guide rod 33 passes through the guide rod hole of the base plate 34 and intermittently cooperates with it, so that the guide rod 33 limits the base plate 34 to only perform linear motion and prevents it from rotating.

[0059] Working principle: fix the whole device in the PE pipe, charge the cylinder 45 with pressure, so that the inner ring 21 and the outer ring 25 rotate relative to each other, the telescopic cylinder 26 extends radially along the center pipe 12 to the limit position, the cutter head 36 is pressed against the inner wall of the pipe, the cutter head 36 is squeezed and drives the slider 31 to shrink inward through the support rod 35 and the bottom plate 34, and the slider 31 squeezes the spring in the telescopic cylinder 26. In this way, the squeezing force between the cutter head 36 and the inner wall of the pipe is determined by the elastic force of the spring and the gravity of the cutting assembly itself, and the relevant squeezing force is controllable. In addition, the cutter head 36 has radial activity in the PE pipe, which can automatically adapt to the error of the inner diameter of the pipe and the installation deviation of the device, so as to ensure that the cutter head 36 can fit perfectly with the inner wall of the pipe. At the same time, after stretching, the blades of all the cutter heads 36 are connected end to end to form a closed ring, and then the sealed cavity between the blind plate 11 and the piston 13 is filled with gas to push the piston 13 to move axially along the center tube 12, thereby driving the cutter head 36 to move axially along the PE pipe to cut the entire skirt. This reduces the impact of the high toughness and high elongation of the pipe material on the cutting efficiency and can quickly cut the skirt.

[0060] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the embodiments of the present invention should be covered within the protection scope of the present invention.

Claims

1. A tube inner skirt cutting device, characterized in that: include: The axial telescopic assembly is used to push the cutting assembly to move axially along the center tube; the axial telescopic assembly includes the center tube; A radial telescopic assembly, the radial telescopic assembly comprising a plurality of telescopic cylinders arranged circumferentially and capable of moving only radially along the central tube; A radial drive assembly, used for driving the telescopic cylinder to move radially along the central tube; The cutting assembly is used for cutting the inner skirt of the pipe. Each telescopic cylinder carries a cutting assembly, and each cutting assembly includes: The bottom plate is carried on the telescopic tube, and the bottom plate is a T-shaped structure, including a first straight portion and a second straight portion fixedly connected to the middle portion of the first straight portion, wherein the second straight portion is arranged along the axial direction of the central tube; A support rod, one end of which is fixed to a side of the bottom plate away from the telescopic cylinder; A cutter head fixed to the end of the support rod away from the bottom plate, the cutter head is an arc-shaped plate structure, the curvature of the cutter head matches the curvature of the inner wall of the pipe, and the cutter head is provided with a blade portion extending along the circumferential direction of the central pipe, which is used to cut the skirt in the pipe when the cutter head moves axially along the central pipe; Among them, the first straight portions in two adjacent cutting assemblies are arranged in opposite directions so that the two ends of the first straight portion of any base plate are opposite to the second straight portions of the two adjacent base plates; when the telescopic cylinder is extended and retracted along the radial direction of the center tube, it will drive the cutter head to extend and retract along the radial direction of the center tube, and after being extended, the areas swept by adjacent blade portions when moving axially along the center tube intersect or connect.

2. The tube inner skirt cutting device according to claim 1, characterized in that: Each of the base plates is provided with three cutter heads, which are arranged in parallel in a T-shape, wherein two cutter heads are located on the first straight line portion, and another cutter head is located on the second straight line portion, and the cutter heads located on the second straight line portion are spaced a certain distance apart from the cutter heads located on the first straight line portion.

3. The tube inner skirt cutting device according to claim 1, characterized in that: The cutting assembly also includes: An end cover fixedly connected to one end of the telescopic cylinder facing the bottom plate; A slider movably arranged in the telescopic cylinder, the slider is a stepped shaft structure and one end of the slider passes through the end cover and is fixedly connected to the bottom plate; A spring that pushes the slider to move axially along the telescopic cylinder toward the end cover; A guide rod having one end fixedly connected to the end cover and the other end extending along the axial direction of the telescopic cylinder; A guide rod hole located on the bottom plate and extending along the axial direction of the telescopic cylinder; One end of the guide rod passes through the guide rod hole and is clearance-matched with the guide rod hole.

4. The tube inner skirt cutting device according to claim 1, characterized in that: The radial telescopic assembly also includes: A sliding sleeve is sleeved on the outer wall of the central tube, and the inner edge of the sliding sleeve extends along the axial direction of the sliding sleeve to form a cylindrical section; An inner ring sleeved on the outer wall of the cylindrical section; An outer ring with one side fixedly connected to the outer edge of the sleeve and the other side extending axially along the sleeve; all telescopic cylinders are arranged along the circumference of the outer ring and each telescopic cylinder can only move radially along the outer ring; Connecting rod, each telescopic cylinder corresponds to a connecting rod, one end of each connecting rod is hinged to the inner ring, and the other end is hinged to the corresponding telescopic cylinder, and the hinge axis between the connecting rod and the inner ring and the hinge axis between the connecting rod and the telescopic cylinder are parallel to the center line of the sliding sleeve.

5. The tube inner skirt cutting device according to claim 4, characterized in that: The radial driving assembly is used to drive the inner ring and the outer ring to rotate relative to each other.

6. The tube inner skirt cutting device according to claim 5, characterized in that: The radial drive assembly comprises: A cylinder with one end hinged to the outer ring and the other end of the cylinder being free; An inner connecting rod having one end hinged to the free end of the cylinder and the other end hinged to the inner ring; An outer connecting rod having one end hinged to the free end of the cylinder and the other end hinged to the outer ring; The hinge points of the cylinder and the outer ring, the hinge points of the inner connecting rod and the inner ring, and the hinge points of the outer connecting rod and the outer ring are arranged in a triangle, so that when the cylinder is extended or retracted, the inner connecting rod and the outer connecting rod are pushed to move, thereby causing the inner ring and the outer ring to rotate relatively.

7. The tube inner skirt cutting device according to claim 6, characterized in that: The radial drive assembly also includes a disc-shaped cover plate, which is located on a side of the inner ring and the outer ring away from the sleeve and is fixedly connected to the inner ring, and is used to separate the mechanical components between the inner ring and the outer ring from the outside.

8. The tube inner skirt cutting device according to claim 7, characterized in that: The axial telescopic assembly also includes: Two blind plates are fixed in the center tube at intervals and block the inner passage of the center tube. The side wall of the center tube is provided with a longitudinal slot extending along the axial direction of the center tube. Along the axial direction of the center tube, the longitudinal slot is located on one side of the two blind plates. A piston movably arranged between the two blind plates and sealedly connected to the inner wall of the center tube; A piston rod having one end connected to the piston and the other end passing through a blind plate adjacent to the longitudinal slot; A connecting pin passes through the longitudinal slot, one end of which is fixedly connected to the piston rod, and the other end of which is fixedly connected to the cylindrical section of the telescopic cylinder.

9. The tube inner skirt cutting device according to claim 8, characterized in that: The axial telescopic assembly also includes a movable ring movably arranged in the central tube and fixedly connected to the piston rod, and the connecting pin is fixedly connected to the movable ring.

10. A method for cutting the inner skirt of a tube, characterized in that: Using the inner skirt cutting device of claim 8 or 9 to cut the skirt inside the pipe comprises the following steps: The inner skirt cutting device is placed in the pipeline, and the inner ring and the outer ring are pushed to rotate relative to each other by charging the air cylinder, so as to drive the telescopic cylinder to extend to the limit position along the radial direction of the central pipe, and the cutter head is close to the inner wall of the pipeline, and the blade parts of all the cutter heads are connected end to end to form a closed ring; The center tube is fixed in the pipeline, and gas is filled into the sealing cavity between the piston and the blind plate to push the piston to move axially along the center tube, thereby driving the cutter head to move axially along the pipeline to cut the entire skirt.

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