CN112872057B

CN112872057B - Axial prestress self-repairing spinning pipe, force application structure and spinning pipe self-repairing method

Info

Publication number: CN112872057B
Application number: CN202110091757.6A
Authority: CN
Inventors: 张海霞; 王斯琪
Original assignee: Beijing Dugenhongyun Technology Development Co ltd
Current assignee: Beijing Dugenhongyun Technology Development Co ltd
Priority date: 2021-01-23
Filing date: 2021-01-23
Publication date: 2022-01-28
Anticipated expiration: 2041-01-23
Also published as: CN112872057A

Abstract

The application discloses an axial prestress self-repairing laying pipe, a force application structure and a laying pipe self-repairing method, wherein the axial prestress self-repairing laying pipe comprises an outer pipe, an inner pipe and a pipe head, the inner pipe is lined in the outer pipe, and the inner pipe is in frictional contact with the outer pipe to restrain movement relative to the outer pipe; an elastic part is arranged at the output end of the tube head, the outer tube is fixedly connected with the tube head, and the elastic part is compressed and pressed on the inner tube. When the laying pipe undergoes heating and cooling cycles, the expansion force or the contraction force overcomes the friction force, the driving force and the elastic force drive the inlet end of the inner pipe to gradually displace in the outer pipe towards the output end of the outer pipe, and the gradual displacement changes the inner surface of the inner pipe in frictional contact with the hot rolled product, so that the inner surface of the inner pipe in frictional contact with the hot rolled product is updated, and the permanent frictional contact of any area of the inner wall of the inner pipe is avoided; under the same excess steel amount, abnormal pipe replacement phenomena such as deep groove wire disorder and the like can be effectively reduced.

Description

Axial prestress self-repairing spinning pipe, force application structure and spinning pipe self-repairing method

Technical Field

The application relates to the technical field of laying pipes, in particular to an axial prestress self-repairing laying pipe, a force application structure and a laying pipe self-repairing method.

Background

Wire is one of the important varieties of steel products, and is widely applied to the building and product industries. At present, the countries mainly producing steel generally adopt a full-continuous high-speed torsion-free wire rod finishing mill group and a controlled cooling technology as main process equipment means for wire rod production.

High speed wire production is a continuous process from billet to finished product, and the laying head laying pipe is a key device for controlling the transition of wire from straight line to wire rod. The temperature of the rolled piece after finish rolling is kept at 850 ℃ approximately, the speed can be as high as 120m/s, after the rolled piece enters a spinning pipe, the wire rod moves forwards according to the spinning pipe under the comprehensive actions of driving force, relative inertia force, friction force, positive pressure and the like caused by a pinch roll and a spinning machine, the linear motion is changed into spiral motion, a stable coil with the diameter of 1080mm is formed, and the stable coil is discharged from the spinning pipe and evenly laid on a roller way.

A paper entitled "study and improvement of spatial curves of a laying pipe of a high-speed wire laying machine", published in journal 2006, volume 8, volume 11 of China engineering science "records that when the laying pipe works, the wire moves forwards in the laying pipe, and because of the backward friction resistance of the wall of the laying pipe, a certain micro-section of wire is always pushed and pulled by the front and rear adjacent parts of the wire, so that the wire has certain axial force and always runs along the central line direction of the wire; also described are a trend graph of the relative velocity of the wire in the laying pipe, a pressure profile (as shown in FIG. 7) against the inner wall of the laying pipe, and a friction profile (as shown in FIG. 8) against the inner wall of the laying pipe.

Through research and analysis, the wire is subjected to rapid increase after entering the inlet of the laying pipe, the position with the maximum friction force is about 500mm away from the inlet of the laying pipe, the inner wall of the laying pipe is severely abraded, and even the laying pipe is worn through after long-time work, so that steel piling accidents occur.

Abnormal wear of the laying pipe leading to excessively short service life and laying anomalies has been a major problem in wire production.

Disclosure of Invention

In view of the above problems, the present application provides an axial prestress self-repairing laying pipe, a force application structure, and a laying pipe self-repairing method.

In a first aspect, the present application provides an axial pre-stress self-repairing laying pipe, which adopts the following technical scheme:

an axial prestress self-repairing spinning pipe comprises an outer pipe, an inner pipe and a pipe head, wherein the inner pipe is lined in the outer pipe, and the inner pipe is in frictional contact with the outer pipe to restrain movement relative to the outer pipe; an elastic part is arranged at the output end of the tube head, the outer tube is fixedly connected with the tube head, and the elastic part is compressed and pressed on the inner tube.

By adopting the technical scheme, when the spinning pipe is subjected to heating and cooling circulation, the expansion force or the contraction force overcomes the friction force, the driving force FD and the elastic force drive the inlet end of the inner pipe to gradually shift in the outer pipe towards the output end of the outer pipe, and the gradual shifting changes the inner surface of the inner pipe in friction contact with the hot rolled product, so that the inner surface of the inner pipe in friction contact with the hot rolled product is updated, and the permanent friction contact of any area of the inner wall of the inner pipe is avoided; under the same excess steel amount, abnormal pipe replacement phenomena such as deep groove wire disorder and the like can be effectively reduced.

Optionally, the output end of the tube head is coaxially and fixedly connected with a connecting tube, and the connecting tube is lined in the inner tube; the elastic piece is sleeved on the connecting pipe.

Through adopting above-mentioned technical scheme, the connecting pipe provides the installation basis for the elastic component, and the guarantee elastic component compression or the process that resets go on steadily.

Optionally, the material of the inner pipe is selected from one of spring steel, duplex stainless steel, high-speed steel, precipitation hardening stainless steel, high manganese steel and nodular cast iron.

Optionally, the specification length of the inner tube is 1000-4000mm, and the thickness is 2-8 mm.

In a second aspect, the present application provides a structure for applying thrust to an axially prestressed self-repairing laying pipe, comprising a ring structure driven to advance by a screw thread, the ring structure being mounted inside a pipe head, the elastic member being located between the ring structure and an inner pipe; the thrust of the annular structure is used for extruding and deforming the inner tube (2) of the elastic part.

By adopting the technical scheme, after the laying pipe works for a period of time, the elastic part can recover deformation along with the displacement of the inner pipe, and the pressure acting on the inner pipe can be correspondingly reduced; the annular structure driven to advance by the threads is arranged, so that the compression amount of the elastic piece can be adjusted when the laying head is normally stopped for trimming, the pressure of the elastic piece acting on the inner pipe is improved, and the gradual displacement rate of the inner pipe is guaranteed; and the thread has a certain self-locking function, so that the elasticity of the elastic part acting on the annular structure can be effectively counteracted.

Optionally, the annular structure is in threaded connection with a connecting pipe of the pipe head, teeth are arranged on the outer annular surface of the annular structure, a gear is rotatably connected to the pipe head, and the gear is in meshed connection with the annular structure; the rotation axis of the gear is parallel to the axis of the connecting pipe.

By adopting the technical scheme, when the gear rotates, the lantern ring is driven to synchronously rotate through the meshing transmission of the teeth; meanwhile, the lantern ring is in threaded connection with the connecting pipe, the rotating lantern ring can synchronously move along the axial direction of the connecting pipe to extrude the spring, and the spring compresses to store force.

Optionally, the annular structure is slidably connected with a connecting pipe of the pipe head, a screw which advances through a thread is arranged on the pipe head, and the advancing direction of the screw is parallel to the axis of the connecting pipe; the annular structure is connected with the screw rod.

Optionally, a support block is fixedly connected to the tube head, the screw is slidably supported on the support block, and a nut in threaded fit with the screw is arranged at the support block; the annular structure is fixedly connected with a connecting rod, and the connecting rod is fixedly connected with the screw rod.

By adopting the technical scheme, the nut is screwed to drive the screw rod to move towards the inner pipe along the axis of the screw rod, the screw rod pulls the connecting rod and the lantern ring to move synchronously, the spring is extruded again, and the spring is compressed to store force.

In a third aspect, the present application provides a laying pipe self-repair method, which adopts the following technical scheme:

a self-repairing method for a laying pipe adopts a prestress self-repairing laying pipe to realize the following processes:

providing a double-layer laying pipe having an inner pipe lining an outer pipe, the inner pipe constrained against movement relative to the outer pipe by frictional contact with the outer pipe;

applying axial prestress to the inner pipe to enable the inner pipe to have an axial displacement trend relative to the outer pipe;

as the double layer laying pipe undergoes heating or cooling, the portion of the inner pipe lining the outer pipe is progressively displaced relative to the outer pipe.

By adopting the technical scheme, the laying pipe undergoes heating and cooling circulation, the inner pipe which is in relative motion is restrained by frictional contact and is gradually displaced along the outer pipe, and the axial prestress applied to the inner pipe can improve the updating area and the updating speed of the inner surface of the inner pipe, so that the abrasion problem of the transition region L of the laying pipe is better solved.

Optionally, the manner of applying axial prestress to the inner tube is as follows: the double-layer spinning pipe has one pipe head in the input end, one outer pipe fixed to the pipe head, one compressed elastic part between the pipe head and the inner pipe, and one elastic part with elastic force acting on the pipe head and the inner pipe.

Optionally, the manner of applying axial prestress to the inner tube is as follows: the double-layer spinning pipe is characterized in that a pipe head is arranged at the input end of the double-layer spinning pipe, the outer pipe is fixedly connected with the pipe head, an annular structure which is driven to advance through threads is arranged on the pipe head, an elastic part in a compressed state is arranged between the annular structure and the inner pipe, and the elastic force of the elastic part acts on the annular structure and the inner pipe.

Drawings

FIG. 1 is a schematic structural view of an axially prestressed self-repairing laying pipe of example 1;

FIG. 2 is a schematic view showing the fitting state of the inner and outer tubes in embodiment 1;

3A-3C are diagrammatic depictions showing the forces acting on the inner tube during heating and cooling cycles;

FIG. 4 is a schematic structural view of an axially prestressed self-repairing laying pipe according to example 2;

FIG. 5 is a schematic structural view of a force application structure in embodiment 3;

FIG. 6 is a schematic structural view of a force application structure in embodiment 4;

FIG. 7 is a graph of the pressure profile experienced by the inner wall of the laying pipe;

FIG. 8 is a graph of the friction profile experienced by the inner wall of the laying pipe.

Description of reference numerals: 1. an outer tube; 2. an inner tube; 3. a pipe head; 31. a connecting ring; 32. a connecting pipe; 33. connecting holes; 4. a spring; 5. a collar; 51. a connecting rod; 6. a gear; 7. a screw; 8. a support block; 9. and a nut.

Detailed Description

The present application is described in further detail below with reference to the attached drawings.

The embodiment of the application discloses an axial prestress self-repairing laying pipe.

Example 1

Referring to fig. 1 and 2, the axial prestress self-repairing laying pipe comprises an outer pipe 1 and an inner pipe 2, wherein the outer pipe 1 is sequentially provided with a linear leading-in section 1A, a bending deformation section 1B and a stable section 1C from an input end to an output end of the outer pipe, and the linear leading-in section 1A, the bending deformation section 1B and the stable section 1C are integrally formed. The material of the outer tube 1 is a thermally stable material commonly used for existing single-layer laying pipes, such as 10CrMo 918.

The inner tube 2 is a straight tube made of wear-resistant material, the axial dimension of the inner tube 2 is 1000-4000mm, and the wall thickness is 2-8 mm. The inner pipe 2 is lined in the outer pipe 1 from the linear leading-in section, the inner pipe and the outer pipe are in transition fit, the maximum gap is 0.2mm, and the maximum interference is 0.05mm, so that the inner pipe 2 is only in frictional contact with the outer pipe 1 to restrict the movement relative to the outer pipe 1; the inner tube 2 and the outer tube 1 constitute a laying pipe body.

The wear-resistant material of the inner tube 2 can be spring steel, duplex stainless steel, high-speed steel, precipitation hardening stainless steel, high manganese steel, nodular cast iron and the like.

It has been shown that the internal wall of the laying pipe tends to produce accelerated localized wear in the transition region L between the straight lead-in section and the curved deformation section, which if left unchecked, could lead to premature grooving of the internal wall of the laying pipe, which in turn could lead to product penetration through the wall of the laying pipe.

The wear problem can be solved by the following means: the outer tube 1 is lined with an inner tube 2 and the inner tube 2 is only allowed to be constrained to move within the outer tube 1 by frictional contact between their respective inner and outer surfaces.

When the laying pipe is in use, it can rotate about the axis of the laying pipe, the hot rolled product passes through the laying pipe, the linear motion in the laying pipe is changed into a spiral motion, and the formed stable coil is discharged from the laying pipe. In the above process, the inner pipe 2 is heated due to contact with the hot rolled product. Typically, the hot rolled product will be at a temperature of about 900 ℃ to 1100 ℃, which will result in heating the inner tube 2 to a temperature of about 400 ℃. The outer tube 1 generally has a lower temperature due to its exposure to the surrounding environment.

Further, when the hot rolled product passes through the inner pipe 2, it is rubbed against the inner pipe 2, and the axial force of the hot rolled product exerts a driving force FD on the inner pipe 2.

As shown in fig. 3A, since the inner pipe 2 is heated by being brought into contact with the hot rolled product, the inner pipe 2 will undergo expansion, thereby exerting forces in two directions opposite to the directions toward the inlet end (arrow FEE) and the outlet end (arrow FDE). The expansion forces FEE and FDE are sufficient to overcome the frictional resistance FF. The expansion force FEE is overcome by the combined force of the expansion force FDE and the driving force FD, causing the inner pipe 2 to be progressively displaced within the outer pipe 1 towards the output end of the outer pipe 1.

As shown in fig. 3B, when the temperature of the inner pipe 2 is stabilized, there is no expansion force or contraction force. The friction force FF overcomes the driving force FD so that the inner tube 2 remains fixed within the outer tube 1.

As shown in fig. 3C, when the inner tube 2 cools, the inner tube 2 will experience contraction, again applying opposing forces towards the inlet end (arrow CEE) and the outlet end (arrow CDE). The forces CEE and CDE are sufficient to overcome the frictional force FF. The contraction force CEE is overcome by the combined force of the contraction force CDE and the driving force FD, causing the inlet end of the inner tube 2 to be progressively displaced within the outer tube 1 towards the outlet end of the outer tube 1.

Thus, it will be appreciated that as the laying pipe undergoes heating and cooling cycles, the inner pipe 2 will progressively displace in one direction towards the output end of the outer pipe 1, which progressive displacement will change the inner surface of the inner pipe 2 in frictional contact with the hot rolled product and thus renew the inner surface of the inner pipe 2 in frictional contact with the hot rolled product, avoiding permanent frictional contact of any region of the inner wall of the inner pipe 2. Thus, under the same excess steel amount, the abrasion depth of the inner surface of the inner pipe 2 is reduced to about 15 percent of the prior art, thereby preventing abnormal pipe replacement phenomena such as deep groove wire disorder and the like.

In this application, the axial dimension of inner tube 2 is far less than the axial dimension of outer tube 1, certainly also can select to inlay the pipe for whole, and inner tube 2 is isometric with outer tube 1 promptly, and both can solve the excessive problem of laying head pipe inner wall local wear.

Example 2

The difference between this embodiment and embodiment 1 is that, referring to fig. 4, the self-repairing axial prestress spinning pipe further includes a pipe head 3, the main body of the pipe head 3 is a hollow tubular structure, the input end of the pipe head 3 has a tapered guide portion, the output end of the pipe head 3 is coaxially and fixedly connected with a connection ring 31 and a connection pipe 32, the connection ring 31 and the pipe head 3 have the same outer diameter, the connection pipe 32 and the pipe head 3 have the same inner diameter, and the inner diameter of the limit ring is larger than the outer diameter of the connection pipe 32, so that a space is left between the two, and the space is not smaller than the wall thickness of the inner pipe 2.

The connection tube 32 of the ferrule 3 is sleeved with an elastic member, which can be a spring 4 or an arc-shaped elastic sheet, and the spring 4 is taken as an example in this embodiment for description.

When the main body of the laying pipe is matched with the pipe head 3, the inner pipe 2 is sleeved on the connecting pipe 32, the input end of the inner pipe 2 extends into the space between the connecting pipe 32 and the connecting ring 31 to extrude the spring 4, so that the spring 4 compresses to store force; the input end of the outer tube 1 abuts on the connection ring 31 and is finally welded at the joint of the outer tube 1 and the connection ring 31. The spring force of the spring 4 acts on the inner tube 2 such that the inner tube 2 has a tendency to displace towards the output end of the outer tube 1.

When the pipe to be spun undergoes heating and cooling cycles, the expansion force or the contraction force overcomes the friction force, the driving force FD and the elastic force of the spring 4 jointly drive the inlet end of the inner pipe 2 to gradually displace in the outer pipe 1 towards the output end of the outer pipe 1, and the updating area and the updating rate of the inner surface of the inner pipe 2 are effectively improved.

Example 3

The difference between the present embodiment and embodiment 2 is that the pipe head 3 of the present embodiment is provided with a force application structure for adjusting the compression amount of the spring 4, so that the pressure of the spring 4 acting on the inner pipe 2 can be adjusted.

Referring to fig. 5, the force application structure includes a collar 5 sleeved on the connecting pipe 32, a spring 4 is arranged between the collar 5 and the inner pipe 2, and the end of the spring 4 is respectively abutted against the collar 5 and the inner pipe 2; the outer wall of the connecting pipe 32 is provided with a thread section, and the inner ring surface of the lantern ring 5 is provided with an internal thread, so that the lantern ring 5 is in threaded connection with the connecting pipe 32 and can advance along the axial thread of the connecting pipe 32.

The coupling ring 31 of the pipe head 3 is provided with a driving member for driving the sleeve to rotate, in this embodiment, the driving member is a gear 6. A connecting hole 33 in a long strip shape is radially arranged on the connecting ring 31 in a penetrating way, and the length direction of the connecting hole 33 is the same as the axial direction of the connecting pipe 32; the length of the gear 6 is matched with that of the connecting hole 33, the gear 6 is rotatably arranged in the connecting hole 33, and the rotating axis of the gear 6 is parallel to the axis of the connecting pipe 32. The ferrule 3 may be provided with a limit structure, such as a jack screw or a detent structure, for holding the gear 6 in a fixed state.

The tooth surface of the gear 6 penetrates out of the connecting ring 31 through the connecting hole 33, teeth are uniformly distributed on the outer ring surface of the lantern ring 5, and the lantern ring 5 is meshed and connected with the gear 6; therefore, when the gear 6 rotates, the lantern ring 5 is driven to synchronously rotate through the meshing transmission of the teeth; meanwhile, as the lantern ring 5 is in threaded connection with the connecting pipe 32, the rotating lantern ring 5 synchronously moves axially along the connecting pipe 32 to extrude the spring 4, and the spring 4 compresses and stores force.

After the laying pipe works for a period of time, the spring 4 can recover deformation along with the displacement of the inner pipe 2, and the pressure acting on the inner pipe 2 can be correspondingly reduced; the arrangement of the force application structure can adjust the compression amount of the spring 4 and improve the pressure of the spring 4 acting on the inner tube 2 when the laying head is normally stopped for trimming, thereby ensuring the speed of the progressive displacement of the inner tube 2.

Example 4

The difference between this embodiment and embodiment 3 is that the force application structure in this embodiment drives the collar 5 to axially displace along the connection pipe 32 by the screw 7.

Referring to fig. 6, the collar 5 is sleeved on the connecting tube 32 and is in sliding fit with the connecting tube 32; a plurality of groups of connecting rods 51 are fixedly connected to the outer annular surface of the lantern ring 5 along the radial direction, correspondingly, a plurality of groups of connecting holes 33 on the connecting ring 31 are also arranged, and the connecting rods 51 correspond to the connecting holes 33 one by one; the end of the connecting rod 51 passes through the connecting ring 31 through the through hole and is vertically and fixedly connected with a screw rod 7, and the screw rod 7 is in threaded connection with a nut 9. The axis of the screw 7 is in the same direction as the axis of the lantern ring 5 and is distributed towards the output end of the pipe head 3.

The outer wall of the connecting ring 31 is fixedly connected with a supporting block 8, a through hole is formed in the supporting block 8, and the screw 7 penetrates through the through hole and is slidably supported on the supporting block 8; the nut 9 is located on the side of the support block 8 facing away from the collar 5.

The elastic force of the spring 4 acts on the lantern ring 5 and the inner tube 2 to enable the lantern ring and the inner tube to move away from each other; under the action of the elastic force of the spring 4, the nut 9 is always pressed against the supporting block 8.

The nut 9 is screwed to drive the screw 7 to displace along the axis thereof towards the inner tube 2, and the screw 7 pulls the connecting rod 51 and the lantern ring 5 to move synchronously, so that the spring 4 is extruded again, and the spring 4 is compressed and stored.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. The utility model provides an axial prestressing force selfreparing laying pipe which characterized in that: the device comprises an outer tube (1), an inner tube (2) and a tube head (3), wherein the inner tube (2) is lined in the outer tube (1), and the inner tube (2) is in frictional contact with the outer tube (1) to restrict the movement relative to the outer tube (1);

the output end of the tube head (3) is provided with an elastic part, the outer tube (1) is fixedly connected with the tube head (3), and the elastic part is compressed and pressed on the inner tube (2) so that the inner tube (2) has a tendency of moving towards the output end of the outer tube (1);

when the axially prestressed self-repairing laying pipe undergoes heating or cooling, the portion of the inner pipe (2) lining the outer pipe (1) is progressively displaced relative to the outer pipe (1).

2. The axially prestressed self-healing laying pipe of claim 1, wherein: the output end of the tube head (3) is coaxially and fixedly connected with a connecting tube (32), and the connecting tube (32) is lined in the inner tube (2); the elastic piece is sleeved on the connecting pipe (32).

3. The axially prestressed self-healing laying pipe of claim 1, wherein: the material of the inner pipe (2) is selected from one of spring steel, duplex stainless steel, high-speed steel, precipitation hardening stainless steel, high manganese steel and nodular cast iron.

4. The axially prestressed self-healing laying pipe of claim 1, wherein: the specification length of the inner tube (2) is 1000-4000mm, and the thickness is 2-8 mm.

5. A structure for imparting thrust to an axially prestressed self-repairing laying pipe as claimed in any one of claims 1 to 4, characterized by: the pipe head comprises an annular structure which is driven to advance through threads, the annular structure is arranged in the pipe head (3), and the elastic part is positioned between the annular structure and the inner pipe (2); the thrust of the annular structure is used for extruding and deforming the inner tube (2) of the elastic part.

6. The laying pipe forcing structure of claim 5, wherein: the annular structure is in threaded connection with a connecting pipe (32) of the pipe head (3), teeth are arranged on the outer annular surface of the annular structure, a gear (6) is rotatably connected to the pipe head (3), and the gear (6) is in meshed connection with the annular structure; the rotation axis of the gear (6) is parallel to the axis of the connecting pipe (32).

7. The laying pipe forcing structure of claim 5, wherein: the annular structure is connected with a connecting pipe (32) of the pipe head (3) in a sliding mode, a screw rod (7) which advances through threads is arranged on the pipe head (3), and the advancing direction of the screw rod (7) is parallel to the axis of the connecting pipe (32); the annular structure is connected with the screw (7).

8. The laying pipe forcing structure of claim 7, wherein: a supporting block (8) is fixedly connected to the tube head (3), the screw rod (7) is slidably supported on the supporting block (8), and a nut (9) in threaded fit with the screw rod (7) is arranged at the supporting block (8); and a connecting rod (51) is fixedly connected to the annular structure, and the connecting rod (51) is fixedly connected with the screw rod (7).

9. A self-repairing method for a laying pipe is characterized by comprising the following steps: with the laying pipe forcing structure of any one of claims 5 to 8, the following is achieved:

providing a double-layer laying pipe having an inner pipe (2) lining an outer pipe (1), the inner pipe (2) constrained from movement relative to the outer pipe (1) by frictional contact with the outer pipe (1);

applying axial prestress to the inner pipe (2) to enable the inner pipe (2) to have an axial displacement trend relative to the outer pipe (1);

when the double-layer laying pipe is subjected to heating or cooling, the portion of the inner pipe (2) lining the outer pipe (1) is progressively displaced with respect to said outer pipe (1).

10. The laying pipe self-repair method of claim 9, wherein: the mode of applying axial prestress to the inner pipe (2) is as follows: the double-layer spinning pipe is characterized in that a pipe head (3) is arranged at the input end of the double-layer spinning pipe, the outer pipe (1) is fixedly connected with the pipe head (3), an elastic part in a compressed state is arranged between the pipe head (3) and the inner pipe (2), and the elastic force of the elastic part acts on the pipe head (3) and the inner pipe (2).

11. The laying pipe self-repair method of claim 9, wherein: the mode of applying axial prestress to the inner pipe (2) is as follows: the double-layer spinning pipe is characterized in that a pipe head (3) is arranged at the input end of the double-layer spinning pipe, the outer pipe (1) is fixedly connected with the pipe head (3), an annular structure which is driven to advance through threads is arranged on the pipe head (3), an elastic part in a compressed state is arranged between the annular structure and the inner pipe (2), and the elastic force of the elastic part acts on the annular structure and the inner pipe (2).