A continuous winding production method of a socket pipe

Abstract

The application discloses a continuous winding production method of a socket pipe, and first acquires a continuous winding device with the following structure, which comprises a winding forming mechanism and a feeding mechanism, the winding forming mechanism comprises a frame body and a forming cage, the forming cage comprises a suspension arm which is arranged in a cantilevered manner on the frame body, the outer end of the suspension arm is provided with a fixed disc which is coaxially arranged, a forming roller which is parallel to the suspension arm is rotatably arranged on the fixed disc, and a plurality of forming rollers are uniformly arranged along the circumference of the suspension arm; the forming roller comprises a main roller, an axially movable sleeve roller is arranged on one end of the main roller which faces the frame body, and the end of the sleeve roller which is far away from the frame body is an adapter section with a gradually decreasing diameter; the main roller and the sleeve roller are provided with a guide mechanism which can transmit torque in a circumferential direction; and the forming cage is provided with a feeding driving mechanism which is used for driving the sleeve roller to move in the axial direction of the main roller. The application has the advantages of reasonable structural design, continuous winding forming of a pipe body and a socket head, reduction of production cost, improvement of production efficiency and the like.

Description

Technical Field

[0001] This invention relates to the field of pipe manufacturing technology, and in particular to a continuous winding production method for socket-type pipes. Background Technology

[0002] Composite spiral wound pipe is a new type of irregularly shaped wall pipe with advantages such as light weight, strong pressure resistance, high joint quality, long service life, corrosion resistance, high ring stiffness, and convenient construction. It is widely used in urban water supply, drainage, long-distance water transmission, and farmland irrigation projects. Composite spiral wound pipe is made by spirally winding strip profiles and interlocking the adjacent sides of each subsequent coil with the previous coil to form a pipe. To increase the strength of the connection, adhesive is usually used at the interlocking points.

[0003] Currently, composite spiral wound pipes are manufactured using a continuous winding process. For example, a Chinese patent document discloses an HDPE spiral wound pipe production equipment (publication number CN108000858A), which employs a drive assembly and rollers. Rotatable rollers are positioned between the two end plates of the rollers, evenly distributed circumferentially. Each roller rotates synchronously in the same direction under the drive assembly. Even when the roller as a whole is stationary, the rotation of the rollers drives the strip wound on the rollers to continuously wind and form the pipe. During the continuous forming process, the pipe moves outward axially and continuously grows, ensuring that the inner diameter of the pipe is consistent with the outer diameter of the multiple rollers.

[0004] However, during construction, composite spiral wound pipes are installed in sections, and a sealed connection is required between adjacent ends. Therefore, existing composite spiral wound pipes require the separate fabrication of sockets with inner diameters matching the outer diameter of the pipe, which are then welded to one end of the pipe for easy sealing during construction. This post-welded socket requires additional socket processing equipment and can only be welded manually, impacting production efficiency and increasing costs. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a continuous winding production method that can continuously wind and form tubes and sockets, which is conducive to reducing production costs and improving production efficiency.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A continuous winding production method for socket-type pipes first obtains a continuous winding device with the following structure: the continuous winding device includes a winding forming mechanism and a feeding mechanism for hot extrusion of continuous strip material. The winding forming mechanism includes a frame and a cylindrical forming cage. The feeding mechanism is located on one side of the forming cage, allowing the discharge end of the feeding mechanism to convey continuous strip material along the tangent of the forming cage. The forming cage includes a cantilevered support arm mounted on the frame. The outer end of the cantilever arm has a coaxially mounted fixed disk. A forming roller parallel to the cantilever arm is rotatably mounted on the fixed disk. Multiple forming rollers are evenly distributed along the circumference of the cantilever arm. The other end of the forming roller is rotatably mounted on the frame. The frame has a mechanism for driving multiple forming rollers in the same direction. A rotating drive mechanism is provided; the forming roller includes a main roller, and an axially movable sleeve roller is fitted onto one end of the main roller facing the frame. The inner diameter of the sleeve roller is the same as the diameter of the main roller, and the end away from the frame is a connecting section with a gradually decreasing diameter; a guide mechanism for circumferentially transmitting torque is provided between the main roller and the sleeve roller, and the guide mechanism is located at the end of the main roller and the sleeve roller facing the frame; the forming cage has a feed drive mechanism for driving the sleeve roller to move axially along the main roller; during production, the continuous strip is first wound around the outer circumference of the forming cage to form a tube. After the tube length reaches the set length, the sleeve roller is pushed outward at the axial feed speed of the tube by the feed drive mechanism, so that the continuous strip gradually winds from the connecting section onto the sleeve roller, completing the winding of the socket pipe.

[0008] Since the sleeve rollers are fitted onto the main rollers, their outer diameter must be larger than that of the main rollers, and the outer diameter of the circumscribed circles of the multiple sleeve rollers must also be larger than that of the multiple main rollers. Because the sleeve rollers have a connecting section with a decreasing diameter at the end furthest from the frame, the outer diameter of the circumscribed circle at the connecting section also gradually decreases. During winding, winding begins near the sleeve rollers on the multiple main rollers. The rotation drive mechanism causes the multiple main rollers to rotate in the same direction, allowing the continuous strip to wind around the outer surface of the forming cage. The formed tube moves outward in the direction away from the frame, continuously forming subsequent tubes. Once the tube reaches the desired length, the feed drive mechanism pushes the sleeve rollers outward at the speed at which the tube moves forward. The newly wound continuous strip gradually forms an enlarged tube under the action of the connecting section, eventually winding onto the sleeve rollers to form a socket tube.

[0009] Furthermore, the feed drive mechanism includes a push plate coaxially sleeved outside the suspension arm, the push plate having a clearance hole corresponding to the main roller, and the end of the sleeve roller facing the frame being rotatably fitted into the clearance hole via a bearing; the frame has a linear telescopic mechanism arranged parallel to the suspension arm, and the push plate is connected to the telescopic end of the linear telescopic mechanism.

[0010] The sleeve rollers are mounted on the clearance holes of the push plate via bearings, allowing them to rotate with the main roller and also move axially along the main roller under the action of the push plate. Connecting all the sleeve rollers together via the push plate enables the linear telescopic mechanism to drive all the sleeve rollers to move simultaneously.

[0011] Furthermore, the push plate has a first reinforcing rib extending radially and a second reinforcing rib arranged circumferentially. Multiple first reinforcing ribs are distributed circumferentially along the push plate, and multiple second reinforcing ribs are distributed radially.

[0012] In this way, the rigidity of the push plate can be increased by the first and second reinforcing ribs, which can prevent the push plate from deforming during axial movement and thus affect the smoothness of the operation, and help extend its service life.

[0013] Furthermore, the push plate has a push rod arranged parallel to the cantilever arm on the side facing the frame. Multiple push rods are evenly distributed along the circumference of the push plate. The multiple push rods pass into the frame and are installed on the push-pull plate. The telescopic end of the linear telescopic mechanism is connected to the push-pull plate.

[0014] In this way, the push-pull plate can evenly distribute the thrust or pull force of the linear telescopic mechanism onto the push plate through the circumferentially distributed push rods, which allows the push plate to move more smoothly, avoids damage due to uneven load, and helps to extend its service life.

[0015] Furthermore, the linear telescopic mechanism is a hydraulic cylinder.

[0016] Furthermore, the guiding mechanism consists of an external spline on the main roller and an internal spline on the sleeve roller.

[0017] In this way, the combination of internal and external splines allows for a smoother power transmission.

[0018] Furthermore, the roller includes a forming sleeve and a first guide sleeve, the forming sleeve being integrally connected to the connecting section; the internal spline is disposed on the first guide sleeve, and the first guide sleeve is fixedly connected to the forming sleeve.

[0019] Furthermore, the main roller includes a roller body and a second guide sleeve sleeved on the roller body; the external spline is disposed on the second guide sleeve, and the second guide sleeve is fixed to the roller body by bolts.

[0020] This structure allows for easy upgrading of existing winding devices, thereby significantly reducing equipment costs.

[0021] Furthermore, one end of the main roller extends into the frame body, and the rotation drive mechanism includes a driven sprocket and a drive motor mounted on the main roller. The output end of the drive motor is provided with a drive sprocket, and chains are connected to the drive sprocket and multiple driven sprockets.

[0022] Furthermore, the roller has an insert shaft section that matches the relief hole, and the insert shaft section passes through the relief hole; the insert shaft section has a relatively protruding retaining ring, and both sides of the relief hole have thrust bearings sleeved on the insert shaft section, one of the thrust bearings abutting between the retaining ring and the push plate, and the other thrust bearing has a retaining ring on the side away from the push plate, and the retaining ring is fixedly installed on the roller.

[0023] By installing thrust bearings on both sides of the push plate, the friction between the roller and the push plate can be reduced during the pushing and pulling process, thus making the winding process smoother.

[0024] In summary, the continuous winding production method of the present invention has the advantages of being able to continuously wind and form tubes and connectors, which helps to reduce production costs and improve production efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of this embodiment.

[0026] Figure 2 This is a cross-sectional structural diagram of this embodiment.

[0027] Figure 3 This is a schematic diagram of the pusher plate and forming roller.

[0028] Figure 4 for Figure 3 A schematic diagram of its decomposed structure.

[0029] Figure 5 This is a schematic diagram of the sprocket arrangement.

[0030] Figure 6 This is a schematic diagram of the overall structure of the pressure roller mechanism.

[0031] Figure 7 This is a cross-sectional structural diagram of the pressure roller mechanism.

[0032] Figure 8 This is a schematic diagram of the pressure roller frame.

[0033] Figure 9 This is a schematic diagram of the disassembled structure of the pressure roller frame. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the embodiments.

[0035] In practical implementation: such as Figures 1-5 As shown, a continuous winding forming device for socket-type pipes includes a winding forming mechanism and a feeding mechanism for hot extrusion of continuous strip material. The winding forming mechanism includes a frame 1 and a cylindrical forming cage 2. The feeding mechanism is located on one side of the forming cage 2, allowing the discharge end of the feeding mechanism to convey the continuous strip material along the tangent of the forming cage 2. The forming cage 2 includes a cantilevered support arm 21 mounted on the frame 1. The outer end of the cantilever arm 21 has a coaxially mounted fixed disk 22. A forming roller 23 parallel to the cantilever arm 21 is rotatably mounted on the fixed disk 22. Multiple forming rollers 23 are evenly distributed along the circumference of the cantilever arm 21. The other end of the forming roller 23 is rotatably mounted on... On the frame 1, there is a rotary drive mechanism 3 that drives multiple forming rollers 23 to rotate in the same direction; the forming rollers 23 include a main roller 231, and an axially movable sleeve roller 232 is sleeved on the end of the main roller 231 facing the frame 1. The inner diameter of the sleeve roller 232 is the same as the diameter of the main roller 231, and the end away from the frame 1 is a connecting section 233 with a gradually decreasing diameter; there is a guide mechanism between the main roller 231 and the sleeve roller 232 that can transmit torque circumferentially. The guide mechanism is located at the end of the main roller 231 and the sleeve roller 232 facing the frame 1; the forming cage 2 has a feed drive mechanism 4 for driving the sleeve roller 232 to move axially along the main roller 231.

[0036] The feed drive mechanism 4 includes a pusher plate 41 coaxially sleeved outside the cantilever arm 21. The pusher plate 41 has a clearance hole corresponding to the main roller 231. The end of the sleeve roller 232 facing the frame 1 is rotatably fitted into the clearance hole via a bearing. The frame 1 has a linear telescopic mechanism arranged parallel to the cantilever arm 21, and the pusher plate 41 is connected to the telescopic end of the linear telescopic mechanism. By mounting the sleeve roller in the clearance hole of the pusher plate via bearings, the sleeve roller can both rotate with the main roller and move axially along the main roller under the action of the pusher plate. By connecting all the sleeve rollers together through the pusher plate, the linear telescopic mechanism can drive all the sleeve rollers to move together simultaneously.

[0037] To increase the overall rigidity of the push plate 41, the push plate 41 has a first reinforcing rib extending radially and a second reinforcing rib arranged circumferentially. Multiple first reinforcing ribs are distributed circumferentially along the push plate 41, and multiple second reinforcing ribs are distributed radially. The first and second reinforcing ribs increase the rigidity of the push plate, preventing deformation during axial movement that could affect the smoothness of operation and extending its service life.

[0038] The push plate 41 has push rods 42 arranged parallel to the cantilever arm 21 on the side facing the frame 1. Multiple push rods 42 are evenly distributed along the circumference of the push plate 41, and these push rods 42 pass into the frame 1 and are mounted on a push-pull plate 43. The telescopic end of the linear telescopic mechanism is connected to the push-pull plate 43. Figure 2 As shown in the figure, the linear telescopic mechanism is a hydraulic cylinder. The push-pull plate can evenly distribute the thrust or pull force of the linear telescopic mechanism onto the push plate through the circumferentially distributed push rods, thereby allowing the push plate to move more smoothly, avoiding damage due to uneven load, and helping to extend its service life.

[0039] The guiding mechanism consists of an external spline on the main roller 231 and an internal spline on the sleeve roller 232. For example... Figure 3 and Figure 4 As shown, the sleeve roller 232 includes a forming sleeve and a first guide sleeve 234, the forming sleeve being integrally connected to the connecting section 233; the inner spline is disposed on the first guide sleeve 234, and the first guide sleeve 234 is fixedly connected to the forming sleeve. The main roller 231 includes a roller body and a second guide sleeve 235 sleeved on the roller body; the outer spline is disposed on the second guide sleeve 235, and the second guide sleeve 235 is fixed to the roller body by bolts.

[0040] This allows for improvements to existing technologies (such as the rotary roller in CN108000858A) for continuously forming tubes with a constant inner diameter. By installing a second guide sleeve on the main roller of the existing device, and then fitting a first guide sleeve and a sleeve roller together, along with a pusher plate, push rod, and hydraulic cylinder, existing equipment can be retrofitted at low cost, reducing production costs and increasing production efficiency. Furthermore, the continuously wound forming socket has a higher connection strength with the tube body, thereby improving product quality and market competitiveness.

[0041] The roller 232 has an insert shaft section that matches the clearance hole, and the insert shaft section passes through the clearance hole. The insert shaft section has a relatively protruding retaining ring 236. Thrust bearings 237 are sleeved on the insert shaft section on both sides of the clearance hole. One thrust bearing 237 abuts against the retaining ring 236 and the push plate 41, while the other thrust bearing 237 has a retaining ring on the side facing away from the push plate 41. The retaining ring is fixedly installed on the roller 232. Thus, by providing thrust bearings on both sides of the push plate, the friction between the roller and the push plate during the push-pull process can be reduced, thereby making the winding process smoother.

[0042] One end of the main roller 231 extends into the frame 1. The rotary drive mechanism includes a driven sprocket and a drive motor mounted on the main roller 231. A drive sprocket is mounted at the output end of the drive motor. Chains are connected to the drive sprocket and multiple driven sprockets. Figure 5 As shown, an auxiliary wheel is provided between two adjacent main rollers 231. The chain passes sequentially around the driven sprocket and the auxiliary wheel, and at least one auxiliary wheel or driven sprocket is connected to the drive motor. That is, the auxiliary wheel or driven sprocket connected to the drive motor is the driving sprocket.

[0043] In existing winding forming devices, to accommodate winding of pipes with different inner diameters, the frame 1 is equipped with radially outward extending grooves. Combined with other adjustment mechanisms, this allows all main rollers to expand outwards or contract inwards uniformly, thereby changing the outer diameter of the main rollers. Specifically, for this structure, an adjustment groove extending radially outwards can be provided on the push plate 41. An adjustment block is slidably engaged within the adjustment groove, and a clearance hole is provided through the adjustment block. This allows for modification of existing equipment.

[0044] In continuous winding, a pressure roller mechanism is typically added to ensure the continuous strip adheres better to the winding cage. Most existing pressure rollers are integral cylindrical structures, primarily designed for continuously wound tubes with a constant diameter. However, in this embodiment, the tube diameter transitions at the connection section. During winding, some strips have a smaller winding diameter, while others have a larger diameter. To allow the continuous strip to better adhere to the connection section and achieve variable diameter winding, this embodiment employs a pressure roller mechanism with the following structure: Figures 6-9 As shown, the device includes a mounting frame and a sheet-like pressure roller frame 701. The mounting frame includes a support shaft 702. One end of the pressure roller frame 701 is rotatably mounted on the support shaft 702, and the other end is rotatably provided with a pressure roller plate 703. The axis of the pressure roller plate 703 is parallel to the support shaft 702. Multiple pressure roller frames 701 are arranged side by side along the support shaft 702. The mounting frame includes side plates 704 connected to both ends of the support shaft 702. Two side plates 704 are tightly disposed on the outer side of the multiple pressure roller frames 701. The side of the pressure roller plate 703 that protrudes from the support shaft 702 relative to the pressure roller frame 701 is the pressing side. Each pressure roller frame 701 has an elastic reset member 705 between itself and the mounting frame to rotate the pressure roller frame 701 toward the pressing side.

[0045] like Figure 6As shown, a limiting plate 706 is connected between the two side plates 704. The limiting plate 706 is located on the side of the pressure roller frame 701 away from the support shaft 702. The limiting plate 706 has a limiting strip protruding towards the pressure roller frame 701, and the limiting strip is located on the pressing side of the pressure roller frame 701. A beam plate 707 is connected between the two side plates 704. The beam plate 707 is located on the side of the support shaft 702 facing the pressing side. The elastic reset member 705 is a tension spring connected between the beam plate 707 and the pressure roller frame 701.

[0046] like Figure 8 and Figure 9 As shown, the pressure roller frame 701 has a semi-circular groove, the diameter of which matches the diameter of the pressure roller plate 703. The pressure roller plate 703 is rotatably fitted within the groove, and its thickness is the same as that of the pressure roller frame 701. A limiting block 708 is installed on one side of the groove. The inner side of the limiting block 708 has an arc surface concentrically connected to the groove, and the sum of the central angle of the arc surface and the central angle of the groove is greater than 180°. The pressure roller plate 703 is rotatably fitted onto the arc surface. Specifically, a threaded hole is provided on one side of the groove, and a bolt hole matching the threaded hole is provided through the limiting block 708. The limiting block 708 is installed on the threaded hole by a bolt passing through the bolt hole. To make the pressure roller rotate more smoothly, the inner wall of the roller groove has rotatable balls. Multiple balls are evenly distributed along the circumference of the roller groove, and the outer surface of the pressure roller 703 is fitted onto the multiple balls.

[0047] The pressure roller structure of this embodiment features a plate-shaped pressure roller frame with multiple pressure roller frames arranged side-by-side on the support shaft. Each pressure roller frame has an elastic reset element between itself and the mounting frame. In this way, the pressure roller plates on multiple pressure roller frames combine to form a pressure roller. When the continuous strip is pressed against the surface of the forming cage, the reaction force borne by each pressure roller frame is independent. As the outer diameter of the forming mold surface changes, the rotation angle of each pressure roller frame relative to the support shaft is also different. This allows it to adapt to forming molds of different diameters, ensuring that the continuous strip is always in contact with the surface of the forming mold, which is beneficial to improving the forming quality of the wound tube.

[0048] The winding process for socket-type pipes using the continuous winding forming apparatus of this embodiment is as follows:

[0049] 1. A pressure roller mechanism is used to press the continuous strip onto the surface of the main roller. As the main roller rotates, the strip is wound into a forming cage and continuously formed in a spiral shape.

[0050] 2. Once the length of the formed tube meets the preset length, the pusher plate is pushed outward by the hydraulic cylinder, and the pushing speed is controlled to be consistent with the feeding speed of the formed tube. At this time, the sleeve roller and the tube are moving synchronously, which can ensure the stability and reliability of the winding.

[0051] 3. After the winding length of the socket section meets the preset length, the continuous strip is cut and the end is shaped. The hydraulic cylinder pulls the push plate to retract the sleeve roller, preparing for the next pipe winding.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for continuous winding production of socket-type pipes, characterized in that, First, obtain a continuous winding device with the following structure. The continuous winding device includes a winding forming mechanism and a feeding mechanism for hot extrusion of continuous strip. The winding forming mechanism includes a frame (1) and a cylindrical forming cage (2). The feeding mechanism is located on one side of the forming cage (2), so that the discharge end of the feeding mechanism can convey the continuous strip along the tangent of the forming cage (2). The forming cage (2) includes a cantilever arm (21) arranged on the frame (1). 1) has a coaxially arranged fixed disk (22) at its outer end. A forming roller (23) parallel to the cantilever arm (21) is rotatably arranged on the fixed disk (22). Multiple forming rollers (23) are evenly distributed along the circumference of the cantilever arm (21). The other end of the forming roller (23) is rotatably arranged on the frame (1). The frame (1) has a rotary drive mechanism (3) that drives multiple forming rollers (23) to rotate in the same direction. The forming roller (23) includes a main roller. (231) An axially movable sleeve roller (232) is fitted onto one end of the main roller (231) facing the frame (1). The inner diameter of the sleeve roller (232) is the same as the diameter of the main roller (231), and the end away from the frame (1) is a connecting section (233) with a gradually decreasing diameter. A guide mechanism for circumferentially transmitting torque is provided between the main roller (231) and the sleeve roller (232). The guide mechanism is located between the main roller (231) and the sleeve roller (232) facing the frame (1). 1) One end; the forming cage (2) has a feed drive mechanism (4) for driving the sleeve roller (232) to move axially along the main roller (231); during production, the continuous strip is first wound around the outer circle of the forming cage to form a tube. After the tube length reaches the set length, the sleeve roller (232) is pushed outward at the axial feed speed of the tube by the feed drive mechanism (4), so that the continuous strip is gradually wound from the connecting section (233) to the sleeve roller (232) to complete the winding of the socket pipe.

2. The continuous winding production method for socket-type pipes as described in claim 1, characterized in that, The feed drive mechanism (4) includes a push plate (41) coaxially sleeved outside the suspension arm (21). The push plate (41) has a clearance hole corresponding to the main roller (231). The end of the sleeve roller (232) facing the frame (1) is rotatably fitted on the clearance hole through a bearing. The frame (1) has a linear telescopic mechanism arranged parallel to the suspension arm (21). The push plate (41) is connected to the telescopic end of the linear telescopic mechanism.

3. The continuous winding production method for socket-type pipes as described in claim 2, characterized in that, The push plate (41) has a first reinforcing rib extending radially and a second reinforcing rib arranged circumferentially. Multiple first reinforcing ribs are distributed circumferentially along the push plate (41), and multiple second reinforcing ribs are distributed radially.

4. The continuous winding production method for socket-type pipes as described in claim 2, characterized in that, The push plate (41) has a push rod (42) on the side facing the frame (1) that is parallel to the cantilever arm (21). Multiple push rods (42) are evenly distributed along the circumference of the push plate (41). Multiple push rods (42) are inserted into the frame (1) and are mounted on a push-pull plate (43). The telescopic end of the linear telescopic mechanism is connected to the push-pull plate (43).

5. The continuous winding production method for socket-type pipes as described in claim 4, characterized in that, The linear telescopic mechanism is a hydraulic cylinder.

6. The continuous winding production method for socket-type pipes as described in claim 2, characterized in that, The guiding mechanism consists of an external spline on the main roller (231) and an internal spline on the sleeve roller (232).

7. The continuous winding production method for socket-type pipes as described in claim 6, characterized in that, The roller (232) includes a forming sleeve and a first guide sleeve (234), the forming sleeve being integrally connected to the connecting section (233); the internal spline is disposed on the first guide sleeve (234), and the first guide sleeve (234) is fixedly connected to the forming sleeve.

8. The continuous winding production method for socket-type pipes as described in claim 6, characterized in that, The main roller (231) includes a roller body and a second guide sleeve (235) sleeved on the roller body; the external spline is disposed on the second guide sleeve (235), and the second guide sleeve (235) is fixed on the roller body by bolts.

9. The continuous winding production method for socket-type pipes as described in claim 1, characterized in that, One end of the main roller (231) extends into the frame (1). The rotary drive mechanism (3) includes a driven sprocket (31) and a drive motor mounted on the main roller (231). The output end of the drive motor is provided with a drive sprocket (32). Chains (33) are connected to the drive sprocket (32) and a plurality of driven sprockets (31).

10. The continuous winding production method for socket-type pipes as described in claim 2, characterized in that, The roller (232) has an insert shaft section that matches the relief hole, and the insert shaft section passes through the relief hole; the insert shaft section has a relatively protruding retaining ring (236), and both sides of the relief hole have thrust bearings (237) sleeved on the insert shaft section, one of the thrust bearings (237) abuts between the retaining ring (236) and the push plate (41), and the other thrust bearing (237) has a retaining ring on the side away from the push plate (41), and the retaining ring is fixedly installed on the roller (232).

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