Wire drawing apparatus

Abstract

The application relates to a wire drawing equipment, and belongs to the technical field of wire processing.The equipment comprises a wire feeding assembly for containing and feeding the wire to be drawn; a guide assembly located at the rear of the wire feeding assembly and used for guiding the wire to be drawn; a drawing assembly located at the rear of the drawing assembly, the drawing assembly comprising a drawing box, a drawing roller and a plurality of drawing dies, the drawing roller being rotationally arranged in the drawing box and used for providing the moving power for the wire, and the drawing dies each being provided with a drawing hole; a liquid supply assembly arranged on the drawing box and used for supplying lubricating oil to the surface of the wire to be drawn; and a wire winding assembly located at the rear of the drawing assembly and used for winding the drawn wire.The application realizes the uniformization and fullness of lubrication coverage in the wire drawing process by arranging a plurality of groups of drawing dies, the diameters of the drawing holes in each group being the same, the diameters of the drawing holes between groups being sequentially reduced, and the liquid supply assembly being used for directly supplying lubricating liquid to the drawing holes of the drawing dies in each group.

Description

Technical Field

[0001] This application relates to the technical field of wire processing, and in particular to a wire drawing device. Background Technology

[0002] Wire drawing technology is an important metal processing technology, and its development is of great significance to the entire industrial sector.

[0003] Currently, in the traditional wire drawing process, to reduce the wire diameter, a single drawing die or multiple drawing dies are typically used. The former involves directly passing the wire through a drawing die with a specific aperture, using the die's squeezing action to reduce the wire diameter; the latter involves sequentially passing the wire through multiple drawing dies with progressively smaller apertures, gradually reducing the wire diameter.

[0004] While using multiple drawing dies can improve the quality of the drawn wire and extend the die life to some extent, the lubricant cannot completely cover the wire before drawing. This results in the wire still experiencing significant and uneven friction during the drawing process, hindering further improvement in the quality of the finished wire. Furthermore, the reduced wire tension at the unwinding end leads to low drawing efficiency in the later stages of the process.

[0005] Therefore, there is an urgent need for a new type of wire drawing equipment. Summary of the Invention

[0006] To address the problems of existing wire drawing equipment using multiple drawing dies, such as the lubricant not being able to completely cover the wire before drawing and the low wire drawing efficiency in the later stages of the drawing process, this application provides a wire drawing device.

[0007] This application provides a wire drawing device, which adopts the following technical solution: A wire drawing device, comprising: A wire feeding assembly, used to hold and feed the wire to be pulled; A guiding component is located behind the wire feeding component and is used to guide the wire to be pulled out. A drawing assembly is located behind the drawing assembly. The drawing assembly includes a drawing box, drawing rollers, and multiple drawing dies. There are two drawing rollers, which are rotatably disposed in the drawing box and used to provide power for the movement of the wire. The drawing dies are clamped in the drawing box and located between the two drawing rollers. Each drawing die has a drawing hole for reducing the diameter of the wire. The multiple drawing dies are divided into multiple groups. The diameter of the corresponding drawing hole of the drawing die in each group is the same. Along the direction of wire movement, the diameter of the corresponding drawing hole in each group decreases sequentially. A liquid supply assembly is provided on the drawing box and is used to provide lubricating oil to the surface of the wire to be drawn; A take-up assembly is located behind the drawing assembly and is used to take up the drawn wire.

[0008] By adopting the above technical solution and setting up multiple sets of drawing dies, with the same drawing hole diameter in each set and the diameter decreasing sequentially between sets, progressive drawing of the wire is achieved, reducing the amount of deformation per pass and improving the surface quality and internal structural uniformity of the wire. Simultaneously, continuous power is provided by the drawing rollers, and the wire is lubricated by a liquid supply assembly, significantly reducing frictional resistance and temperature rise during the drawing process, thereby improving drawing efficiency and die lifespan.

[0009] Optionally, the number of drawing dies in each group is two.

[0010] By adopting the above technical solution, selecting two drawing dies in each group can not only reduce production costs, but also facilitate maintenance and reduce the resistance encountered by the drawn wire during movement.

[0011] Optionally, the multiple sets of drawing dies are spaced at the same distance.

[0012] By adopting the above technical solution, precise lubrication is achieved. The lubricant is directly supplied to the key position before the wire enters the mold, ensuring sufficient and uniform lubrication, effectively reducing drawing resistance and mold wear, while facilitating centralized supply and management of lubricant.

[0013] Optionally, the liquid supply assembly includes a liquid supply tank and a liquid supply pipe. The liquid supply tank is connected to the bottom of the drawing box, and the middle part of the liquid supply pipe is connected to the drawing box. The first end of the liquid supply pipe is connected to the inside of the liquid supply tank, and the other end is inserted into the drawing box and used to supply lubricant to the drawing hole of the previous drawing die in each group.

[0014] By adopting the above technical solution, precise lubrication is achieved. The lubricant is directly supplied to the key position before the wire enters the mold, ensuring sufficient and uniform lubrication, effectively reducing drawing resistance and mold wear, while facilitating centralized supply and management of lubricant.

[0015] Optionally, the first drawing die in each group has a through hole, which is formed on the outer side of the drawing die and communicates with the drawing hole, and the end of the liquid supply pipe is connected to the inlet of the through hole.

[0016] By adopting the above technical solution, lubricant is directly introduced into the drawing hole through the through hole, realizing a lubrication method from the inside out, improving the lubrication effect, and is especially suitable for high-speed or large deformation drawing processes, further reducing frictional heat and die wear.

[0017] Optionally, the pull-out assembly further includes multiple pipe fittings, which are correspondingly disposed at the inlet of the respective through holes, and the pipe fittings are used to connect to the end of the liquid supply pipe.

[0018] By adopting the above technical solution, the pipe fitting enables a quick and reliable connection between the liquid supply pipe and the mold, facilitating disassembly and maintenance, while preventing lubricant leakage and improving the system's sealing and stability.

[0019] Optionally, a positioning groove is provided on the inner wall of the drawing box, and the drawing die passes through the positioning groove.

[0020] By adopting the above technical solution, the positioning groove enables precise positioning and fixation of the mold, preventing the mold from shifting or vibrating during the drawing process, and ensuring the stability and consistency of the wire drawing path.

[0021] Optionally, the liquid supply assembly further includes a recovery pipe and a filter screen. One end of the recovery pipe is connected to the interior of the drawing box, and the other end is connected to the liquid supply tank. The filter screen is disposed in the liquid supply tank and is used to filter the recovered lubricating fluid.

[0022] By adopting the above technical solutions, the lubricating fluid can be recycled and filtered for reuse, saving lubricating fluid consumption, reducing production costs, and reducing waste discharge, which meets the requirements of green manufacturing and sustainable development.

[0023] Optionally, a tension adjustment assembly is also included, comprising a tension wheel, a tension spring, wire clamps, a tension actuator, a tension sensor, and a controller. The tension wheel is rotatably mounted on the guide assembly and its outer edge always remains in contact with the wire. The tension sensor is located on the guide assembly, the tension spring is located between the tension wheel and the tension sensor, the tension actuator is mounted on the guide assembly, there are two wire clamps, both connected to the output end of the tension actuator, and both the tension actuator and the tension sensor are electrically connected to the controller.

[0024] By adopting the above technical solution, real-time monitoring and automatic adjustment of wire tension can be achieved. In particular, it can maintain a stable pulling state even when the tension drops at the end of the unwinding process, thereby improving the consistency of the pulling process and the uniformity of the finished wire.

[0025] Optionally, the tension adjustment assembly further includes a tension seat and a guide rod. The tension seat is slidably disposed on the guide assembly, the tension wheel is rotatably disposed on the tension seat, the tension sensor has a clearance hole in the middle, one end of the guide rod is connected to the tension seat, the other end passes through the clearance hole, and the tension spring is sleeved on the outside of the guide rod.

[0026] By adopting the above technical solution, the movement of the tension spring is guided by the guide rod, ensuring a smooth and linear tension adjustment process, improving the accuracy and response speed of tension control, and further optimizing the process stability of wire drawing.

[0027] In summary, this application includes at least one of the following beneficial technical effects: By setting up multiple sets of drawing dies, with the same diameter drawing hole in each set and the diameter decreasing sequentially between sets, and cooperating with the liquid supply component to directly supply lubricant to the drawing hole of the previous drawing die in each set, uniform and sufficient lubrication coverage is achieved during the wire drawing process. This effectively reduces the frictional resistance and local temperature rise between the wire and the die, thereby significantly improving the surface quality, dimensional accuracy and internal structure uniformity of the drawn wire, while also extending the service life of the drawing dies.

[0028] By adding a tension adjustment component, the tension of the wire is monitored and automatically adjusted in real time during the drawing process. Especially when the tension drops in the later stage of wire unwinding, it can still maintain a stable drawing state, ensuring the stability and continuity of the drawing process from beginning to end, and improving the overall drawing efficiency and product consistency of the equipment.

[0029] By adopting a modular drawing die layout and positioning structure, combined with a lubricant circulation and filtration system, not only can the drawing process be flexibly configured and quickly maintained, but the lubricant can also be recycled and reused, reducing production energy consumption and material consumption, which meets the needs of the modern wire processing industry for efficient, energy-saving and sustainable production models. Attached Figure Description

[0030] Figure 1 This is an isometric schematic diagram of a wire drawing device provided in this application; Figure 2 yes Figure 1 Front view; Figure 3 yes Figure 1 A schematic diagram of the structure after rotating by an angle; Figure 4 yes Figure 3 Enlarged view of part A in the middle; Figure 5 This is a structural schematic diagram of the internal components of the pull box in this application; Figure 6 This is a schematic diagram of the structure of the pull assembly in this application after the top cover of the pull box is hidden; Figure 7 This is a cross-sectional view of the mating point between the previous drawing die and the pipe fitting in this application; Figure 8 This is a schematic diagram of the structure at the junction of the liquid supply tank and the filter screen in this application.

[0031] In the picture: 1. Pay-off assembly; 2. Guiding assembly; 3. Pull-out assembly; 4. Liquid supply assembly; 5. Take-up assembly; 6. Tension adjustment assembly; 7. Ventilation fan; 11. Cable feeder; 12. Cable feed reel; 21. Guide frame; 22. First guide wheel; 23. Second guide wheel; 24. Third guide wheel; 31. Drawing box; 32. Drawing roller; 33. Drawing die; 34. Drawing hole; 35. Through hole; 36. Drawing actuator; 41. Liquid supply tank; 42. Liquid supply pipe; 43. Liquid supply pump; 44. Recovery pipe; 45. Filter screen; 46. Pipe fitting; 51. Cable take-up frame; 52. Cable take-up drum; 61. Tension wheel; 62. Tension spring; 63. Wire clamp; 64. Tension actuator; 65. Tension sensor; 66. Tension seat; 67. Guide rod. Detailed Implementation

[0032] The following is in conjunction with the appendix Figures 1-8 This application will be described in further detail.

[0033] This application discloses a wire drawing device.

[0034] refer to Figures 1 to 3 A wire drawing device includes a wire feeding assembly 1, a guiding assembly 2, a drawing assembly 3, and a take-up assembly 5 arranged sequentially along the wire's moving direction. The wire feeding assembly 1 is used to hold and feed the wire to be drawn; the guiding assembly 2 is used to guide the wire to be drawn, thereby improving the stability of the wire during movement; the drawing assembly 3 is used to draw the wire so that the wire diameter meets the usage requirements; the fluid supply assembly 4 is used to provide lubricant to the wire being drawn, thereby not only reducing the temperature of the wire, but also reducing the resistance encountered by the wire when passing through the drawing hole 34; the take-up assembly 5 is used to collect the drawn wire.

[0035] refer to Figure 1 and Figure 2 The wire feeding assembly 1 includes a wire feeding frame 11 and a wire feeding reel 12. The wire feeding reel 12 is placed on the ground, and the wire feeding frame 11 is rotatably mounted on the wire feeding reel 12. The wire feeding frame 11 is used to hold the coiled wire.

[0036] refer to Figure 1 and Figure 2The guide assembly 2 includes a guide frame 21, a first guide wheel 22, a second guide wheel 23, and a third guide wheel 24. The guide frame 21 is set on the ground. The first guide wheel 22 and the second guide wheel 23 are both rotatably mounted on the top of the guide frame 21. The third guide wheel 24 is located in the middle of the guide frame 21. After the wire comes out of the wire feeding frame 11, it will pass over the first guide wheel 22, the second guide wheel 23, and the third guide wheel 24.

[0037] refer to Figure 2 , Figure 3 , Figure 5 and Figure 6 The drawing assembly 3 includes a drawing box 31, drawing rollers 32, drawing dies 33, and a drawing driver 36. The drawing box 31 is disposed on the ground. There are two drawing rollers 32, both rotatably disposed inside the drawing box 31. The drawing driver 36 is disposed outside the drawing box 31, and its output end is connected to the end of the drawing rollers 32. There are multiple drawing dies 33, all located between two drawing rollers 32. The wire is wound on the drawing rollers 32 in a multi-turn winding manner. The multiple drawing dies 33 are divided into multiple groups, with two drawing dies 33 in each group. The system consists of a first drawing die 33 and a second drawing die 33. Each drawing die 33 has a drawing hole 34. After the wire passes through the drawing hole 34, its diameter decreases. The drawing holes 34 in each group of drawing dies 33 have the same diameter. Along the direction of wire movement, the diameter of the drawing holes 34 in each group gradually decreases. The diameter of the drawing holes 34 in the last group just meets the final diameter of the wire. During the rotation of the two drawing rollers 32, they not only provide power for the movement of the wire, but also enable the wire to pass through drawing holes 34 of different diameters.

[0038] A positioning groove is provided on the inner wall of the drawing box 31, and the drawing die 33 is inserted into the positioning groove to fix the drawing die 33 and prevent the drawing die 33 from moving with the wire.

[0039] The drawing roller 32 is in the form of a conical roller, and the wire is wound on the drawing roller 32 in multiple turns.

[0040] In order to allow the wire to dissipate heat to a certain extent before entering the drawing hole 34, there is a certain interval between each set of drawing dies 33, and the structure and size of the drawing dies 33 are exactly the same, only the diameter of the drawing hole 34 is different.

[0041] refer to Figures 1 to 3 In addition, the wire drawing equipment also includes a ventilation fan 7. The side of the drawing box 31 is provided with ventilation holes, and the ventilation fan 7 is installed in the ventilation holes. When the ventilation fan 7 rotates, it will exchange the gas inside the drawing box 31, thereby allowing the heat of wire drawing to be quickly displaced, ensuring the surface effect of the wire after drawing and avoiding changes in the internal crystal structure of the wire.

[0042] refer to Figure 2 and Figure 8 The liquid supply assembly 4 includes a liquid supply tank 41, a liquid supply pipe 42, and a liquid supply pump 43. The liquid supply tank 41 is connected to the bottom of the drawing box 31, and the liquid supply tank 41 contains lubricating fluid. The liquid supply pump 43 is located outside the liquid supply tank 41. One end of the liquid supply pipe 42 is connected to the liquid supply pump 43, and the other end is connected to the inside of the drawing box 31. It is used to supply lubricating fluid to the inside of the drawing box 31. The lubricating fluid flows into the drawing hole 34, thereby reducing the resistance encountered by the wire when passing through the drawing hole 34, and further reducing the surface temperature of the wire.

[0043] refer to Figure 6 Because the drawing box 31 is equipped with multiple sets of drawing dies 33, and each set includes two drawing dies 33, the outlet end of the liquid supply pipe 42 is divided into multiple branches, each branch corresponding to a set of drawing dies 33. In each set of drawing dies 33, the top surface of the previous drawing die 33 is provided with a through hole 35, which connects to the drawing hole 34. The top of the through hole 35 is provided with a pipe connector 46, which is fixedly connected to the drawing die 33. The pipe connector 46 and the end of the liquid supply pipe 42 are connected by a quick-connect method. The liquid supply pipe 42 can provide lubricant to the drawing hole 34 in the previous drawing die 33 through the pipe connector and the through hole 35, thereby achieving lubrication of the surface of the wire to be drawn. The top surface of the previous drawing die 33 in each set is connected to a pipe connector, and at the same time, it corresponds to a branch at the end of the liquid supply pipe 42.

[0044] refer to Figure 8 To improve the utilization rate of the lubricant, it can be recycled. The lubricant supply assembly 4 also includes a recovery pipe 44 and a filter screen 45. One end of the recovery pipe 44 is connected to the inside of the drawing box 31, and the other end is connected to the supply tank 41. The filter screen 45 is located inside the supply tank 41. The connection port between the recovery pipe 44 and the supply tank 41 is located above the filter screen 45. The recovered lubricant falls onto the filter screen 45, thus completing the filtration and leaving impurities in the lubricant above the filter screen 45. The connection port between the supply pump 43 and the supply tank 41 is located below the filter screen 45, so the supply pump 43 and the supply pipe 42 can provide clean lubricant to the wire.

[0045] refer to Figure 3 5 includes a take-up frame 51 and a take-up drum 52. The take-up frame 51 is set on the ground, and the take-up drum 52 is rotatably set on the take-up frame 51 and used to collect the finished wire after it has been pulled.

[0046] refer to Figure 3 and Figure 4Because the tension of the coiled wire decreases in the final stage of unwinding, it is detrimental to wire drawing and significantly reduces wire drawing efficiency. To solve this problem, the wire drawing equipment also includes a tension adjusting assembly 6 disposed between the first guide wheel 22 and the second guide wheel 23. The tension adjusting assembly 6 includes a tension wheel 61, a tension spring 62, a wire clamping claw 63, a tension driver 64, a tension sensor 65, a controller, a tension seat 66, and a guide rod 67. Tension seat 66 is slidably mounted on guide frame 21 along the setting direction. Tension wheel 61 is rotatably mounted on tension seat 66. The outer edge of tension wheel 61 always keeps in contact with the wire. Tension sensor 65 is a piezoelectric sensor with a clearance hole in the middle. Tension sensor 65 is located directly below tension seat 66. One end of guide rod 67 is connected to tension seat 66, and the other end passes into clearance hole. Tension spring 62 is sleeved on the outside of guide rod 67. One end of tension spring 62 abuts against tension seat 66, and the other end abuts against tension sensor 65. Tension wheel 61 is located below wire. Tension spring 62 can apply a certain preload to wire. At the same time, the tension on wire can also be transmitted to tension sensor 65. Tension actuator 64 is mounted on guide frame 21. Two clamping claws 63 are mounted on the drive end of tension actuator 64. Tension actuator 64 can move the two clamping claws 63 closer to each other or further apart. Rubber wear-resistant pads are provided on the inner surface of clamping claws 63. Under the action of tension actuator 64, clamping claws 63 clamp the wire, thereby ensuring that the wire always maintains a certain tension and improving the wire pulling efficiency.

[0047] The controller is electrically connected to the tension sensor 65 and the tension driver 64. The controller controls the tension driver 64 through the signal transmitted from the tension sensor 65, thereby adjusting the clamping force of the wire clamping claw 63 on the wire.

[0048] When the wire in the wire feeding assembly 1 enters the final stage, the tension on the wire will change, and the pressure sensed by the tension sensor 65 will change. At this time, the controller will adjust the driving force of the tension driver 64 according to the sensing value of the tension sensor 65, and finally adjust the clamping force applied to the wire by the wire clamping claw 63.

[0049] The implementation principle of the wire drawing equipment in this application embodiment is as follows: After the wire is released from the unloading reel 12, it is guided into the drawing box 31 by the guide wheel set. Inside the drawing box 31, the wire is wound sequentially between two drawing rollers 32 to form a multi-turn traction structure, and the drawing rollers 32 provide continuous and stable drawing power. Under the traction of the drawing rollers 32, the wire passes sequentially through the drawing holes 34 of each set of drawing dies 33.

[0050] During the drawing process, the liquid supply component 4 delivers the lubricant directly to the through hole 35 of the previous drawing die 33 through the liquid supply pipe 42, so that the lubricant can fully wet the surface of the wire and the inner wall of the drawing hole 34, achieving pre-lubrication and uniform coverage, significantly reducing the frictional resistance and local temperature rise between the wire and the die.

[0051] As the wire passes through the drawing holes 34 with decreasing diameters one after another, its diameter is gradually and uniformly reduced, avoiding surface defects and internal stress concentration caused by large single deformation. At the same time, the ventilation fan 7 installed in the drawing box 31 continuously ventilates and assists in heat dissipation, further stabilizing the drawing temperature field.

[0052] During the drawing process, the tension adjustment component 6 monitors the changes in wire tension in real time and dynamically adjusts the clamping force of the wire clamping claw 63 through the controller to ensure that a stable drawing tension can still be maintained even when the tension drops at the end of the wire feeding process, thus ensuring a continuous and efficient drawing process.

[0053] After drawing, the wire is wound up by the take-up spool 52 to form the finished product. Throughout the process, the lubricant flows back to the supply tank 41 through the recovery pipe 44, is purified by the filter screen 45, and is then recycled.

[0054] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A wire drawing device, characterized in that, include: The wire feeding assembly (1) is used to hold and feed out the wire to be pulled; The guide component (2) is located behind the wire feeding component (1) and is used to guide the wire to be pulled. A drawing assembly (3) is located behind the drawing assembly (3). The drawing assembly (3) includes a drawing box (31), a drawing roller (32), and a plurality of drawing dies (33). There are two drawing rollers (32). The drawing rollers (32) are rotatably disposed in the drawing box (31) and used to provide the power for moving the wire. The drawing dies (33) are locked in the drawing box (31) and located between the two drawing rollers (32). Each drawing die (33) is provided with a drawing hole (34). The drawing hole (34) is used to reduce the diameter of the wire. The plurality of drawing dies (33) are divided into multiple groups. The diameter of the corresponding drawing hole (34) of the drawing die (33) in each group is the same. Along the direction of wire movement, the diameter of the corresponding drawing hole (34) in each group decreases sequentially. The liquid supply assembly (4) is provided on the drawing box (31) and is used to provide lubricating oil to the surface of the wire to be drawn; The take-up assembly (5) is located behind the pull assembly (3) and is used to take up the pulled wire.

2. The wire drawing equipment according to claim 1, characterized in that: The number of drawing dies (33) in each group is two.

3. The wire drawing equipment according to claim 2, characterized in that: The multiple sets of drawing dies (33) are spaced at the same distance.

4. The wire drawing equipment according to claim 3, characterized in that: The liquid supply assembly (4) includes a liquid supply tank (41) and a liquid supply pipe (42). The liquid supply tank (41) is connected to the bottom of the drawing box (31). The middle part of the liquid supply pipe (42) is connected to the drawing box (31). The first end of the liquid supply pipe (42) is connected to the liquid supply tank (41), and the other end is inserted into the drawing box (31) and used to supply lubricant to the drawing hole (34) of the previous drawing die (33) in each group.

5. The wire drawing equipment according to claim 4, characterized in that: The first drawing die (33) in each group has a through hole (35), which is located on the outer side of the drawing die (33) and connects to the drawing hole (34). The end of the liquid supply pipe (42) is connected to the inlet of the through hole (35).

6. The wire drawing equipment according to claim 5, characterized in that: The pull-out assembly (3) also includes a pipe connector, which is a plurality of pipe connectors and is correspondingly disposed at the inlet of the corresponding through hole (35). The pipe connector is used to connect to the end of the liquid supply pipe (42).

7. The wire drawing equipment according to claim 1, characterized in that: The inner wall of the drawing box (31) is provided with a positioning groove, and the drawing die (33) passes through the positioning groove.

8. The wire drawing equipment according to claim 4, characterized in that: The liquid supply assembly (4) also includes a recovery pipe (44) and a filter screen (45). One end of the recovery pipe (44) is connected to the interior of the pull box (31), and the other end is connected to the liquid supply tank (41). The filter screen (45) is installed in the liquid supply tank (41) and is used to filter the recovered lubricating liquid.

9. A wire drawing device according to any one of claims 1-8, characterized in that: It also includes a tension adjustment assembly (6), which includes a tension wheel (61), a tension spring (62), a wire clamp (63), a tension driver (64), a tension sensor (65), and a controller. The tension wheel (61) is rotatably mounted on the guide assembly (2) and its outer edge is always in contact with the wire. The tension sensor (65) is located on the guide assembly (2). The tension spring (62) is located between the tension wheel (61) and the tension sensor (65). The tension driver (64) is mounted on the guide assembly (2). There are two wire clamps (63), both of which are connected to the output end of the tension driver (64). The tension driver (64) and the tension sensor (65) are both electrically connected to the controller.

10. A wire drawing device according to claim 9, characterized in that: The tension adjustment assembly (6) further includes a tension seat (66) and a guide rod (67). The tension seat (66) is slidably disposed on the guide assembly (2). The tension wheel (61) is rotatably disposed on the tension seat (66). The tension sensor (65) has a clearance hole in the middle. One end of the guide rod (67) is connected to the tension seat (66), and the other end passes through the clearance hole. The tension spring (62) is sleeved on the outside of the guide rod (67).

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