Telescopic variable-diameter mold and method for manufacturing air duct by using telescopic variable-diameter mold

Abstract

The invention discloses a telescopic variable-diameter mold and a method for manufacturing an air duct through the telescopic variable-diameter mold, and belongs to the technical field of molds, the telescopic variable-diameter mold comprises a telescopic template, a telescopic positioning beam, a telescopic control disc, a telescopic driving shaft and a mold inner framework, the mold inner framework is arranged in the telescopic template, one end of the mold inner framework is connected with the telescopic control disc, and the other end of the mold inner framework is connected with the telescopic positioning beam. The center of the telescopic control panel is connected with a telescopic driving shaft, the telescopic template is provided with a plurality of telescopic positioning beams, the telescopic positioning beams are movably connected with the telescopic control panel, and the technical problems that an existing telescopic device is complex in structure and not beneficial to operation are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of molds, and in particular relates to a telescopic variable-diameter mold and a method for manufacturing a wind tube using the mold. Background Art

[0002] Ventilation is necessary during tunnel excavation. Common ventilation methods include forced-in air supply and exhaust air suction. No matter which method is used, a duct is needed to blow fresh air to the front or suck out the dirty air. Traditional forced-in ventilation often uses soft cloth ducts without frames, while exhaust ventilation requires skeleton ducts. However, these ducts have some problems during construction: 1) The storage volume of the flexible cloth duct is large, and the construction needs to rely on manpower to hang it, which is difficult and cannot be mechanized. 2) Different ventilation methods require different types of ducts, and the arrangement and installation of the ducts are carried out in sequence with the excavation construction process, which will take up construction time and affect construction efficiency. 3) The existing skeleton ducts are first shaped and then connected to the fabric. This skeleton duct has no tension, and the drooping problem during construction cannot meet the smoothness of the connection between the duct and the excavation equipment, and the wind resistance is large and it is not convenient for construction to stretch. 4) The extendable ducts currently available on the market use independent circular ring frames. After unfolding, the wind resistance between the frames increases, which is not suitable for use in long-distance excavation working faces. Since the continuous spiral skeleton air duct fixes the steel wire into a spiral shape before manufacturing, the elastic force between the pitches is opposite to the laying direction, which is not conducive to construction and has a large ventilation resistance. Therefore, it is not suitable for continuous laying and long-distance application.

[0003] In order to solve the above problems, it is necessary to design a new type of continuous extension ventilation duct. The extendable ducts currently available on the market use independent circular ring frames. After unfolding, the wind resistance between the frames increases, which is not suitable for use in long-distance excavation working faces; the continuous spiral frame duct fixes the steel wire into a spiral shape before manufacturing, so that the elastic force between the pitches is opposite to the laying direction, and the ventilation resistance is large, so it is not suitable for continuous laying and long-distance application. Chinese patent CN200964867Y discloses a telescopic curved duct for mining, which realizes a lightweight duct with simple structure, reasonable design, long service life, low wind resistance, high strength, but When manufacturing the hair duct, the folded cloth tube needs to be unfolded first, and then the cloth tube is wound according to the length of the supporting component. After the hair duct is used up, the supporting component and the cloth tube need to be disassembled. Not only is the use process complicated, but it is also time-consuming and labor-intensive, which reduces construction efficiency.

[0004] The manufacturing method of the wind tube in the prior art is mostly to first support the wind tube with a support, and then wind the steel wire around the wind tube to fix it. When the wind tube needs to be stored, because the wind tube is too large, multiple construction workers are required to compress and store the wind tube together. Therefore, it is necessary to provide a device with a telescopic function to manufacture the wind tube. Chinese patent CN218453189U discloses a variable diameter telescopic mold. Although the mold realizes the telescopic function, it requires the cooperation of complex gears, connecting rods, screws, hydraulic cylinders, rollers and other mechanisms to achieve it, which greatly increases the number of parts and assembly steps, and the operation is complicated. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a telescopic variable diameter mold and a method for manufacturing a wind tube, which solves the technical problems that the existing telescopic device has a complex structure and is not conducive to operation.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a telescopic variable diameter mold, comprising a telescopic template, a telescopic positioning beam, a telescopic control disk, a telescopic driving shaft and a mold inner skeleton, wherein the telescopic template is provided with a mold inner skeleton, one end of the mold inner skeleton is connected to the telescopic control disk, the center of the telescopic control disk is connected to the telescopic driving shaft, a plurality of telescopic positioning beams are provided on the telescopic template, and the telescopic positioning beams are movably connected to the telescopic control disk.

[0007] Further preferably, one end of the telescopic drive shaft is connected to a motor.

[0008] Further preferably, the outer layer of the telescopic formwork is composed of more than two arc-shaped spliced ​​plates.

[0009] Further preferably, the outer layer of the telescopic formwork is composed of 2-4 arc-shaped spliced ​​plates.

[0010] Preferably, a plurality of guide grooves are provided on the surface of the telescopic control disk facing the telescopic driving shaft, and a telescopic positioning beam is slidably connected in each guide groove.

[0011] Preferably, the guide groove is arc-shaped.

[0012] Preferably, a positioning fixture is provided on the telescopic drive shaft.

[0013] Preferably, the positioning fixture comprises a bolt, a limit block and a connecting piece, and the bolt is connected to the connecting piece through the limit block.

[0014] Further preferably, the connecting piece is clamped on the surface of the telescopic drive shaft, and the telescopic drive shaft is clamped and loosened by cooperating with a bolt.

[0015] The connector is extended through the thread on the bolt and tightly engaged with the telescopic drive shaft. Once the bolt is rotated, the connector will tightly clamp the telescopic drive shaft, and use the strong friction of the thread and the clamping force of the connector to firmly fix the telescopic drive shaft in the current position, ensuring that the mold will not move or shake during the working process, greatly improving the stability and accuracy of the entire device. Users can easily adjust any telescopic radius.

[0016] Preferably, a plurality of telescopic positioning beams are equally spaced and distributed in a circle, which can ensure uniform force.

[0017] Preferably, at least three telescopic positioning beams are provided.

[0018] Preferably, a mold bracket is connected to the telescopic control plate, and the mold bracket is used to fix the mold.

[0019] Preferably, the mold support is a triangular three-dimensional structure, which has stronger support and makes the variable diameter mold more stable.

[0020] The present invention also provides a method for manufacturing a wind tube using the telescopic variable diameter mold, comprising the following steps: Select appropriate cloth tube material and make it into the required size of cloth tube, and prepare the variable diameter mold to match the required cloth tube diameter; Turn the telescopic control plate clockwise, the telescopic template will retract to one side of the cloth tube, and fix one end of the cloth tube on the variable diameter mold; Turn the telescopic control plate counterclockwise, and the telescopic template will only expand toward the side away from the cloth tube, ensuring that the cloth tube and the variable diameter mold fit completely; Select steel wires to be spirally wound around the outside of the cloth tube at equal intervals according to the required pitch, apply external force to the side of the cloth tube away from the variable diameter mold to compress the cloth tube toward the side of the variable diameter mold, and then bundle it.

[0021] Further preferably, the steel wire is spirally wound on the outer wall of the cloth tube.

[0022] Further preferably, the steel wire is made of high elastic steel with a diameter of 1 mm-6 mm, the pitch of the steel wire is 100 mm-600 mm, the cloth tube is made of flexible material, and the diameter of the cloth tube is 600 mm-1000 mm.

[0023] Further preferably, the cloth cylinder is a cylindrical closed structure.

[0024] Further preferably, the cloth tube is made of anti-static and flame-retardant flexible material.

[0025] Further preferably, docking rings are provided at both ends of the cloth tube.

[0026] Further preferably, the docking ring is a closed steel ring for continuously extending the air duct.

[0027] Further preferably, the steel wire is connected with a universal hook for construction suspension.

[0028] Further preferably, the spacing between the universal hooks is 500 mm-1000 mm.

[0029] Further preferably, the surface of the steel wire is covered with a fixing rubber strip for fixing the steel wire to the cloth tube.

[0030] In the above technical solution, the provision of the docking ring enables the two ends of the wind tube to be more easily connected and docked with other components or systems, thereby improving the compatibility and practicality of the wind tube.

[0031] The introduction of the universal hook makes it easier to connect and fix the wind tube to other equipment or components, improving the flexibility and customizability of the wind tube. At the same time, the rotation function of the universal hook also helps to maintain the stability and reliability of the connection when adjusting the diameter of the wind tube.

[0032] The provision of the fixing rubber strip further enhances the stability and firmness of the connection between the steel wire and the cloth tube, avoids the problem of the steel wire loosening or falling off during use, and improves the overall durability and safety of the wind tube.

[0033] The above manufacturing method further comprises the following steps: The air duct is made of flexible material to form a cylindrical closed structure; rubber strips are covered on the steel wire to fix the steel wire to the cloth tube; universal hooks are buckled on the steel wire for construction suspension; the docking ring is made into a closed steel ring for continuous extension of the air duct; the variable diameter mold is a retractable bracket with a cylindrical outer diameter, and the outer layer of the tooling is composed of more than 2 arc-shaped splicing plates, which are retracted or expanded through the tail support; the total length of the spiral is 10-20m, and the pitch is 200-500mm. The spiral steel wire ribs are wrapped around the outside of the cloth tube and fixed to the cloth tube with a fixing rubber strip. When compressed, the cloth tube is driven to fold.

[0034] The wind duct of the present invention adopts the winding of steel wire and the tension control with the variable diameter mold, so that the wind duct can be opened to the maximum extent in the horizontal direction to improve the ventilation effect. This design enables the wind duct to effectively transport air in underground mining tunnels, provide a good ventilation environment, and improve working conditions and safety; through the application of directional tension, the wind duct can remain straight after unfolding, reducing wind resistance. This design enables the wind duct to reduce energy loss, improve air supply efficiency, and reduce energy consumption during operation. In addition, the cloth tube is used as the main structure of the wind duct, combined with the steel wires wound on the outer wall of the cloth tube at equal intervals, which significantly enhances the structural strength and durability of the wind duct.

[0035] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a telescopic variable diameter mold, in which a telescopic template, a telescopic positioning beam, a telescopic control disk, a telescopic drive shaft and an inner skeleton of the mold together constitute the fine structure of the variable diameter mold. The inner skeleton of the mold provides stable support, the telescopic positioning beam ensures the precise position of the template during the adjustment process, and the telescopic control disk and the telescopic drive shaft realize rapid and precise adjustment of the diameter. Through the coordinated cooperation of the telescopic template, the telescopic positioning beam, the telescopic control disk and the telescopic drive shaft, the mold greatly reduces the number of parts and assembly steps, and is easy to operate. This simple structure not only reduces the overall weight of the product, but also improves stability and reliability. In the manufacturing and production links, the simple structure makes the production process smoother. There is no need to rely on high-precision, high-cost processing equipment and complex process flows, which greatly shortens the production cycle and reduces production costs.

[0036] Furthermore, the setting of the guide groove converts the rotational motion of the mold into a linear telescopic and opening motion. This ingenious design allows the mold to complete the telescopic motion without the need to set up complex driving components, and enables the telescopic positioning beam to move more smoothly and accurately, further improving the accuracy and stability of the mold.

[0037] Furthermore, the guide groove is designed to be arc-shaped, so that the telescopic positioning beam can move along the arc-shaped track during the telescopic process, thereby adjusting the diameter of the mold more smoothly. This design helps to reduce the friction and wear of the mold during the telescopic process and extend the service life of the mold.

[0038] Furthermore, by setting a positioning fixture on the telescopic drive shaft, any telescopic radius can be adjusted. This feature greatly expands the application scenarios of the product, whether it is the processing of workpieces of different sizes in industrial production or the precise operation of a specific range in scientific research experiments, it can be perfectly adapted. At the same time, it also helps to fix the position of the telescopic drive shaft to prevent it from shifting or shaking during operation. This design improves the stability and processing accuracy of the mold.

[0039] Furthermore, the telescopic radius can be precisely controlled through the coordinated action of the bolts, the limit blocks and the connecting parts.

[0040] Furthermore, the equally spaced telescopic positioning beams can evenly support the telescopic template, ensuring the stability and balance of the mold during the telescopic process. This design helps prevent the mold from being deformed or damaged during the telescopic process.

[0041] Furthermore, at least three telescopic positioning beams can provide sufficient support to ensure the stability and strength of the mold during the telescopic process. This design helps to improve the bearing capacity and service life of the mold.

[0042] Furthermore, the mold support is connected to the telescopic control plate to further enhance the overall structural strength of the mold. As a supporting structure, the mold support helps prevent the mold from shaking or tilting during processing, thereby improving the accuracy and stability of processing.

[0043] Furthermore, the triangular three-dimensional mold support has good stability and load-bearing capacity. This design can ensure that the mold maintains a stable posture during the processing, while reducing the material usage of the mold support and reducing the manufacturing cost.

[0044] The present invention also provides a method for manufacturing an air duct using the above-mentioned retractable variable diameter mold, wherein the variable diameter mold is connected to one end of the cloth tube, and the retracting and extending of the variable diameter mold is driven by a telescopic control plate, thereby controlling the compression and expansion of the cloth tube, making the installation and storage of the cloth tube more convenient, and solving the technical problem that the manufacture of traditional air ducts requires a lot of manpower costs. The use of new manufacturing processes and variable diameter molds makes the manufacture and installation of air ducts more efficient. This newly invented air duct and its manufacturing process and mold have created huge economic value for mines. By improving ventilation efficiency and reducing energy consumption, operating costs can be reduced. At the same time, efficient manufacturing processes and construction methods can save manpower and time costs, and improve production efficiency and capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a structural diagram of a variable diameter air duct of the present invention; Figure 2 This is a diagram of the internal components of the variable diameter die of the present invention; Figure 3 This is a diagram of the internal components of the variable diameter die of the present invention; Figure 4 This is a diagram of the internal components of the variable diameter die of the present invention; Figure 5 This is a diagram of the internal components of the variable diameter die of the present invention; Among them: 1-cloth tube; 2-steel wire; 3-fixing rubber strip; 4-universal hook; 5-docking ring; 6-diameter-changing mold; 7-telescopic template; 8-telescopic positioning beam; 9-telescopic control panel; 10-telescopic driving shaft; 11-mold bracket; 12-mold inner skeleton; 13-guide groove; 14-bolt; 15 limit block; 16-connecting piece. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0047] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings: like Figure 1-3 As shown, the present invention provides a telescopic variable diameter mold 6, which includes a telescopic template 7, a telescopic positioning beam 8, a telescopic control disk 9, a telescopic driving shaft 10 and a mold inner skeleton 12, the telescopic template 7 is provided with a mold inner skeleton 12, one end of the mold inner skeleton 12 is connected to the telescopic control disk 9, the center of the telescopic control disk 9 is connected to the telescopic driving shaft 10, a plurality of telescopic positioning beams 8 are arranged on the telescopic template 7, and a plurality of guide grooves 13 are opened on the surface of the telescopic control disk 9 facing the telescopic driving shaft 10, and a telescopic positioning beam 8 is slidably connected in each guide groove 13.

[0049] Preferably, the guide groove 13 is arc-shaped.

[0050] Preferably, a positioning fixture is provided on the telescopic driving shaft 10 .

[0051] Preferably, the positioning fixture includes a bolt 14 , a limiting block 15 and a connecting piece 16 , and the bolt 14 is connected to the connecting piece 16 via the limiting block 15 .

[0052] Further preferably, the connecting member 16 is clamped on the surface of the telescopic drive shaft 10 , and the telescopic drive shaft 10 can be clamped and loosened by cooperating with the bolt 14 .

[0053] The connector 16 extends out through the thread on the bolt 14 and is tightly engaged with the telescopic drive shaft 10. Once the bolt 14 is rotated, the connector 16 will tightly clamp the telescopic drive shaft 10, and the telescopic drive shaft 10 will be firmly fixed in the current position by using the strong friction force of the thread and the clamping force of the connector 16, ensuring that the mold will not be displaced or shaken during the working process, greatly improving the stability and accuracy of the entire device. Users can easily adjust any telescopic radius.

[0054] Further preferably, the outer layer of the telescopic template 7 is composed of more than two arc-shaped spliced ​​plates.

[0055] Further preferably, the outer layer of the telescopic template 7 is composed of 2-4 arc-shaped spliced ​​plates.

[0056] Preferably, the plurality of telescopic positioning beams 8 are distributed at equal intervals.

[0057] Preferably, at least three telescopic positioning beams 8 are provided.

[0058] Preferably, the telescopic control plate 9 is connected to a mold bracket 11, and the mold bracket 11 is used to fix the mold.

[0059] Preferably, the mold support 11 is a triangular three-dimensional structure.

[0060] The present invention also provides a method for manufacturing a wind tube using the telescopic variable diameter mold, which is characterized by comprising the following steps: 1) Make the cloth tube 2 and prepare the variable diameter mold 7: According to the required diameter range of the cloth tube 2, select the appropriate cloth tube material and make the cloth tube 2 of the required size. Connect two or more arc-shaped splicing plates to form a telescopic template 7, and make the outer diameter of the telescopic template 7 smaller than the diameter of the cloth tube 2; 2) Slip the cloth tube 2 onto the variable diameter mold 6: Slip the prepared cloth tube 2 onto the telescopic template 7, and place the docking rings 5 ​​at both ends of the cloth tube 2 to ensure that the cloth tube 2 is completely fitted with the variable diameter mold 6; 3) Wrap the steel wire 1 around the outside of the cloth tube 2: Select a steel wire with a diameter of 6 mm, and wrap the steel wire 1 around the outside of the cloth tube 2 according to the required pitch of 600 mm, ensuring that the steel wire 2 is tensioned and evenly distributed; 4) Fix the universal hook 4: Arrange the universal hook 4 longitudinally on the steel wire 1, and the spacing between the universal hooks 4 is 1000mm. The universal hook 4 can provide a fixing point for the subsequent installation and adjustment of the wind tube; 5) Use the fixing rubber strip 3 to fix the steel wire 1 and the cloth tube 2: Use the fixing rubber strip 3 to firmly fix the steel wire 1 and the cloth tube 2 together to ensure the stability and durability of the air tube; 6) Reduce the diameter of the variable diameter mold 6 and fix the cloth tube 2: Reduce the diameter of the mold 6 so that one end of the cloth tube 2 is fixed on the variable diameter mold 6. Apply external force to the other end to squeeze and compress it together, and then tie it to ensure the shape of the wind tube is stable; 7) When the telescopic control disk 9 rotates clockwise and the telescopic template 7 does not rotate, the telescopic template 7 retracts, otherwise, it extends.

[0061] Further preferably, the steel wire 1 is spirally wound on the outer wall of the cloth tube 2 .

[0062] Further preferably, the steel wire 1 is made of high elastic steel with a diameter of 1 mm-6 mm, the pitch of the steel wire 1 is 100 mm-600 mm, the cloth tube 2 is made of flexible material, and the diameter of the cloth tube 2 is 600 mm-1000 mm.

[0063] Further preferably, the cloth cylinder 2 is a cylindrical closed structure.

[0064] Further preferably, the cloth tube 2 is made of anti-static and flame-retardant flexible material.

[0065] Further preferably, two ends of the cloth tube 2 are provided with docking rings 5 ​​.

[0066] Further preferably, the docking ring 5 is a closed steel ring used for continuous extension of the wind tube.

[0067] Further preferably, a universal hook 4 is connected to the steel wire 1 for construction suspension.

[0068] Further preferably, the spacing between the universal hooks 4 is 500 mm-1000 mm.

[0069] Further preferably, the surface of the steel wire 1 is covered with a fixing rubber strip 3 for fixing the steel wire 1 to the cloth tube 2 .

[0070] Working principle of the retractable variable diameter die: When it is necessary to manufacture the wind tube, the telescopic drive shaft 10 in the variable diameter mold 6 is driven to rotate by a motor or manpower, thereby driving the telescopic control disk 9 to rotate, thereby driving the variable diameter mold 6 to perform telescopic movement along the axial direction of the mold. In this process, the telescopic template 7 will retract or extend as needed. Since the cloth tube 2 has been tightly sleeved on the variable diameter mold 6 and reinforced by the steel wire 1 and the fixed rubber strip 3, the expansion and contraction of the variable diameter mold 6 will directly drive the expansion and contraction of the cloth tube 2. Specifically: when the telescopic control disk 9 rotates clockwise, it will drive the telescopic template 7 to retract. When it retracts to the shortest position, the wind tube is sleeved on one end of the variable diameter mold, and then the control disk 9 is rotated counterclockwise, and the telescopic template 7 extends along the axial direction, thereby opening the wind tube. This method adjusts the expansion and contraction of the variable diameter mold 6 by simply rotating the telescopic control disk 9, thereby making the manufacture of the cloth tube 2 more convenient, and the structure is simple and easy to implement.

[0071] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A telescopic variable diameter die, characterized in that: The invention comprises a telescopic template (7), a telescopic positioning beam (8), a telescopic control disk (9), a telescopic driving shaft (10) and a mold inner frame (12); the telescopic template (7) is provided with a mold inner frame (12); one end of the mold inner frame (12) is connected to the telescopic control disk (9); the center of the telescopic control disk (9) is connected to the telescopic driving shaft (10); a plurality of telescopic positioning beams (8) are provided on the telescopic template (7); the telescopic positioning beams (8) are movably connected to the telescopic control disk (9).

2. A telescopic variable diameter die according to claim 1, characterized in that: A plurality of guide grooves (13) are provided on the surface of the telescopic control plate (9) facing the telescopic drive shaft (10), and a telescopic positioning beam (8) is slidably connected in each guide groove (13).

3. A telescopic variable diameter die according to claim 2, characterized in that: The guide groove (13) is in an arc shape.

4. The telescopic variable diameter die according to claim 1, characterized in that: A positioning fixture is provided on the telescopic driving shaft (10).

5. The telescopic variable diameter die according to claim 4, characterized in that: The positioning fixture comprises a bolt (14), a limiting block (15) and a connecting piece (16), wherein the bolt (14) is connected to the connecting piece (16) via the limiting block (15).

6. The telescopic variable diameter die according to claim 1, characterized in that: A plurality of telescopic positioning beams (8) are distributed at equal intervals.

7. The telescopic variable diameter die according to claim 1, characterized in that: At least three telescopic positioning beams (8) are provided.

8. The telescopic variable diameter die according to claim 1, characterized in that: The telescopic control disk (9) is connected to a mold support (11).

9. The telescopic variable diameter die according to claim 8, characterized in that: The mold support (11) is a triangular three-dimensional structure.

10. A method for manufacturing a wind tube using a telescopic variable diameter mold according to any one of claims 1 to 9, characterized in that: The following steps are involved: Selecting a suitable cloth tube material and manufacturing a cloth tube (1) of a desired size, and preparing a diameter-changing mold (6) to match the diameter of the cloth tube (1) to be manufactured; The telescopic control plate (9) is rotated clockwise, and the telescopic template (7) is retracted toward one side of the cloth tube (1), and one end of the cloth tube (1) is fixed on the variable diameter mold (6); The telescopic control plate (9) is rotated counterclockwise, and the telescopic template (7) is unfolded toward the side away from the cloth cylinder (1); A steel wire (2) is selected and spirally wound around the outer side of the cloth tube (1) at equal intervals according to a required pitch, and an external force is applied to the side of the cloth tube (1) away from the diameter-changing die (6) to compress the cloth tube (1) toward the diameter-changing die (6).

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