Automatic sewing device for bobbin yarn woven bags

Abstract

The present invention discloses an automatic sewing device for bobbin yarn woven bags, belonging to the technical field of packaging sewing, comprising a device body, an upper frame, a first frame, a second frame, a lower frame, an upper clamping plate cylinder, a lower clamping plate cylinder, a tensioning cylinder, a baffle cylinder, an upper roller cylinder, and a lower roller cylinder; a support base is provided on the inner side of the first frame, the support base is fixedly connected to the first crossbeam and the second crossbeam; the piston rod end of the upper clamping plate cylinder is fixed above the first crossbeam; one end of the upper clamping plate is connected below the first crossbeam, and one end of the lower clamping plate is connected above the second crossbeam; the tensioning cylinder is fixedly connected to the lower side of the first frame; the upper frame is fixedly connected to the baffle cylinder, and the piston rod end of the baffle cylinder is fixedly connected to the baffle; the frame edge of the second frame is connected to a sewing machine assembly; and the inner side of the second frame is provided with an upper roller cylinder and a lower roller cylinder. The present invention can achieve the shortest reserved length of the bag opening in the industry while ensuring the beautiful packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of packaging seams, and in particular relates to an automatic seaming device for a bobbin yarn woven bag. Background Art

[0002] After the bobbin yarn is bagged, the woven bag needs to be automatically sewn. In existing sewing devices, due to the size of the existing sewing machine cavity, the distance between the bag opening clamping structure and the baffle used to block the bobbin yarn is too large, about 70 mm. At this time, a long distance must be reserved for the bag opening during sewing, otherwise it will be difficult to grab during sewing. Therefore, the existing technology has the problem of the bag opening being too long during sewing. Summary of the Invention

[0003] In order to solve the above problems, the present invention proposes an automatic sewing device for bobbin yarn woven bags, which can automatically sew the woven bags while ensuring that the bag is kept at the shortest possible length.

[0004] The technical solutions of the present invention are as follows:

[0005] An automatic sewing device for bobbin yarn woven bags, comprising a device body, an upper frame, a first frame, a second frame, a lower frame, an upper clamping plate cylinder, a lower clamping plate cylinder, a tensioning cylinder, a baffle cylinder, an upper roller cylinder, and a lower roller cylinder;

[0006] A support seat is provided on the inner side of the first frame, and the support seat is fixedly connected to the first crossbeam and the second crossbeam; the piston rod of the upper plywood cylinder is fixed above the first crossbeam, and the piston rod of the lower plywood cylinder passes through the first crossbeam and is fixed above the second crossbeam; the cylinder seats of the upper plywood cylinder and the lower plywood cylinder are both fixedly connected to the support seat; one end of the upper plywood is connected to the lower side of the first crossbeam, and one end of the lower plywood is connected to the upper side of the second crossbeam, and the other ends of the upper plywood and the lower plywood are both suspended in the air;

[0007] The cylinder seat of the tensioning cylinder is fixedly connected to the lower frame, and the piston rod is fixedly connected to the support seat;

[0008] The upper frame is fixedly connected to the cylinder seat of the baffle cylinder, and the piston rod of the baffle cylinder is fixedly connected to the baffle;

[0009] The frame edge of the second frame is connected to the sewing machine assembly, and the sewing machine assembly is located between the second frame and the frame of the device body; the sewing machine assembly is slidably connected to the lower frame;

[0010] An upper roller cylinder and a lower roller cylinder are provided on the inner side of the second frame. The piston rod of the upper roller cylinder is connected to the upper roller, and the piston rod of the lower roller cylinder is connected to the lower roller. The cylinder seats of the upper roller cylinder and the lower roller cylinder are both fixedly connected to the second frame.

[0011] The upper splint is slidably connected to the upper roller; the lower splint is slidably connected to the lower roller.

[0012] Furthermore, the upper clamping plate is located on the lower side of the first crossbeam, and the lower clamping plate is located on the upper side of the second crossbeam, and the upper clamping plate and the lower clamping plate are arranged relatively parallel.

[0013] Furthermore, a cavity is provided below the support seat, and the tensioning cylinder moves relatively in the cavity.

[0014] Furthermore, the baffle is in the shape of an inverted right triangle, and the right-angled surface is located on one side of the upper clamping plate and the lower clamping plate.

[0015] Furthermore, a belt is fixedly connected below the sewing machine assembly, a transmission shaft of the belt is connected to a motor fixed on the device body, and a driven shaft of the belt is connected to the sewing machine assembly.

[0016] Furthermore, the sewing machine assembly includes an industrial sewing machine, a sewing machine coil and a sewing machine fixing frame. The sewing machine coil is fixedly connected to the top of the industrial sewing machine, and the bottom is fixedly connected to the sewing machine fixing frame.

[0017] Furthermore, the upper portion of the lower frame is fixedly connected to a guide rail of the sewing machine, and a slider is provided below the fixed frame of the sewing machine, and the slider is slidably connected to the guide rail of the sewing machine.

[0018] Furthermore, the number of the upper rollers is 2, and the number of the lower roller is 1.

[0019] Furthermore, a track for the upper roller to slide is provided inside the upper splint; the bottom of the upper splint is a trapezoidal groove, the lower splint is a trapezoidal structure, the width of the trapezoidal groove at the bottom of the upper splint is greater than the width of the lower splint; the bottom of the lower splint is provided with a track for the lower roller to slide.

[0020] Furthermore, when the belt line flips the woven bag into the seaming position, the working process of the automatic seaming device is as follows:

[0021] (1) In the initial state, the bag opening of the woven bag is located between the upper and lower splints. At this time, the piston rods of the lower splint cylinder and the lower roller cylinder are in an extended state, the upper roller and the lower roller are located outside the upper and lower splints, and one side of the upper and lower splints is in a suspended state;

[0022] (2) Then, the piston rod of the baffle cylinder extends, driving the baffle to move downward a certain distance so that it is close to the upper surface of the woven bag;

[0023] (3) The piston rods of the upper plate cylinder and the upper roller cylinder extend to push the first crossbeam downward; the piston rods of the lower plate cylinder and the lower roller cylinder retract to drive the second crossbeam upward, thereby making the upper plate and the lower plate fit together. At this time, the bag opening of the woven bag is folded and pressed between the upper plate and the lower plate, and the surface of the upper plate fits the right-angle surface of the baffle;

[0024] (4) The piston rod of the tensioning cylinder extends, driving the support seat to move horizontally as a whole, and then driving the first beam and the second beam to move away from the baffle, thereby applying a pulling force to the woven bag, while the baffle remains stationary;

[0025] (5) The motor controls the belt to rotate, driving the second frame and the sewing machine assembly to move toward the first frame at the same time. The upper roller slides along the track inside the first beam, and the lower roller slides along the track at the bottom of the lower clamping plate. At this time, the needle part of the industrial sewing machine is located in the gap between the baffle and the upper clamping plate. The industrial sewing machine continues to automatically sew until the seam is completed. When sewing, the upper clamping plate and the lower clamping plate are located in the cavity of the industrial sewing machine.

[0026] (6) After the seam is completed, the upper clamping plate cylinder retracts 1mm to 2mm, driving the upper clamping plate to slightly lift up 1mm to 2mm, thereby releasing the clamping force between the clamping plates, ensuring that the belt line can pull the woven bag out from between the clamping plates; then, the piston rod of the baffle cylinder retracts, driving the baffle to move upward;

[0027] (7) The belt line drives the woven bag forward, so that the bag mouth of the woven bag is out of between the upper and lower splints;

[0028] (8) The belt line drives the woven bag to continue moving forward, and the motor controls the belt to rotate, driving the second frame and the sewing machine assembly to retreat. The piston rod of the upper splint cylinder retracts, and the piston rod of the lower splint cylinder extends, driving the upper splint and the lower splint to separate and return to the initial state.

[0029] The beneficial technical effects brought about by the present invention are:

[0030] Through the cooperation of the cylinder, splint and roller, the second frame can be moved back and forth on the splint, and the splint can be brought as close to the baffle as possible, so that the reserved length of the bag opening can reach the shortest in the industry, about 10 to 20 mm; through the cooperation of the tightening cylinder and the baffle, it can be used to prevent the bobbin yarn in the woven bag from moving with the bag, which can ensure that the air in the woven bag is consumed to the greatest extent and the gap between the bobbins is reduced; after the seam is completed, the retraction of the upper splint cylinder can drive the upper splint to be slightly lifted up by 1mm to 2mm, releasing the clamping force between the splints, thereby ensuring that the belt line can pull the woven bag out from between the splints, and at the same time ensuring the beauty of the packaging when pulling it out. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a front view of the automatic sewing device for bobbin yarn woven bags in the initial state of the present invention;

[0032] Figure 2 This is a three-dimensional perspective view of the automatic sewing device for bobbin yarn woven bags of the present invention, after the upper and lower clamping plates are clamped and then pulled back;

[0033] Figure 3 for Figure 2 A partial enlarged view of middle A;

[0034] Figure 4 This is a front view of the automatic sewing device for bobbin yarn woven bags of the present invention with the upper and lower clamping plates in a closed state;

[0035] Figure 5 This is a front view of the automatic sewing device for bobbin yarn woven bags of the present invention in a state where the device is clamping the seam and preparing for automatic sewing;

[0036] Figure 6 This is a front view of the automatic sewing device for bobbin yarn woven bags of the present invention in a state where automatic sewing is completed;

[0037] Figure 7 It is a front view of the automatic sewing device for bobbin yarn woven bags of the present invention after the upper splint is slightly raised after the automatic sewing is completed;

[0038] Among them, 1-device body; 2-upper frame; 3-first frame; 4-second frame; 5-lower frame; 6-first crossbeam; 7-second crossbeam; 8-upper splint cylinder; 9-upper splint; 10-lower splint cylinder; 11-lower splint; 12-tensioning cylinder; 13-baffle cylinder; 14-baffle; 15-industrial sewing machine; 16-sewing machine coil; 17-sewing machine fixing frame; 18-sewing machine slide rail; 19-upper roller cylinder; 20-lower roller cylinder; 21-upper roller; 22-lower roller; 23-motor; 24-support base. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0040] Figure 1-Figure 7 An alternative embodiment of the present invention is presented.

[0041] like Figure 1 As shown, an automatic sewing device for bobbin yarn woven bags includes a device body 1, an upper frame 2, a first frame 3, a second frame 4, a lower frame 5, an upper splint cylinder 8, a lower splint cylinder 10, a tensioning cylinder 12, a baffle cylinder 13, an upper roller cylinder 19, and a lower roller cylinder 20.

[0042] like Figure 2 and Figure 3As shown, a support base 24 is provided on the inner side of the first frame 3, and the support base 24 is fixedly connected to the first crossbeam 6 and the second crossbeam 7; the piston rod of the upper plate cylinder 8 is fixed above the first crossbeam 6, and the piston rod of the lower plate cylinder 10 passes through the first crossbeam 6 and is fixed above the second crossbeam 7; the cylinder bases of the upper plate cylinder 8 and the lower plate cylinder 10 are fixedly connected to the support base 24; one end of the upper plate 9 is connected below the first crossbeam 6, and one end of the lower plate 11 is connected above the second crossbeam 7, with the other ends of the upper plate 9 and the lower plate 11 both suspended in the air. The upper plate 9 is located below the first crossbeam 6, and the lower plate 11 is located above the second crossbeam 7, and the upper plate 9 and the lower plate 11 are arranged relatively parallel.

[0043] The cylinder base of the tensioning cylinder 12 is fixedly connected to the lower frame 5, and the piston rod of the tensioning cylinder 12 is fixedly connected to the support base 24; the extension and retraction of the piston rod of the tensioning cylinder 12 controls the horizontal movement of the support base 24.

[0044] A cavity is provided below the support seat 24, and the tensioning cylinder 12 moves relatively in the cavity.

[0045] The upper frame 2 is fixedly connected to the cylinder seat of the baffle cylinder 13, and the piston rod of the baffle cylinder 13 is fixedly connected to the baffle 14. The baffle cylinder 13 controls the up and down movement of the baffle 14 through the extension and contraction of the piston rod; the baffle 14 is an inverted right triangle, and the right-angled surface is located on one side of the upper splint 9 and the lower splint 11; when working, the baffle 14 will have a backward pulling action to prevent the bobbin yarn in the woven bag from moving with the bag, which can ensure that the air in the woven bag is consumed to the greatest extent and the gaps between the bobbins are reduced.

[0046] The frame edge of the second frame 4 is connected to the sewing machine assembly, and the sewing machine assembly is located between the second frame 4 and the frame of the device body 1; a belt is fixedly connected to the bottom of the sewing machine assembly, and the belt is controlled by a motor 23; two relatively parallel sewing machine guide rails 18 are fixedly connected to the top of the lower frame 5, and a belt is fixedly connected to the bottom of the sewing machine assembly, and the transmission shaft of the belt is connected to the motor 23 fixed on the device body, and the passive shaft of the belt is connected to the sewing machine assembly; the motor 23 controls the movement of the belt, thereby driving the sewing machine assembly to move along the sewing machine guide rail 24; the sewing machine assembly includes an industrial sewing machine 15, a sewing machine coil 16 and a sewing machine fixed frame 17, the sewing machine coil 16 is fixedly connected to the top of the industrial sewing machine 15, and the bottom is fixedly connected to the sewing machine fixed frame 17, and a slider is provided below the sewing machine fixed frame 17, which is slidably connected to the sewing machine guide rail 18.

[0047] An upper roller cylinder 19 and a lower roller cylinder 20 are provided on the inner side of the second frame 4, the piston rod of the upper roller cylinder 19 is connected to two upper rollers 21, and the piston rod of the lower roller cylinder 20 is connected to a lower roller 22; the cylinder seats of the upper roller cylinder 19 and the lower roller cylinder 20 are fixedly connected to the second frame 4; the stroke range of the upper roller cylinder 19 is the same as that of the upper splint cylinder 8, which controls the upper roller 21 to move up and down; the stroke range of the lower roller cylinder 20 is the same as that of the lower splint cylinder 10, which controls the lower roller 22 to move up and down.

[0048] A track for the upper roller 21 to slide is provided inside the upper splint 9; the bottom of the upper splint 9 is a trapezoidal groove, and the lower splint 11 is a trapezoidal structure. The width of the trapezoidal groove at the bottom of the upper splint 9 is greater than the width of the lower splint 11; the upper splint 9 and the lower splint 11 cooperate to fold and press the bag opening of the woven bag; a track for the lower roller 22 to slide is opened at the bottom of the lower splint 11.

[0049] Among them, the upper splint cylinder 8, the lower splint cylinder 10, the baffle cylinder 13, the upper roller cylinder 19, and the lower roller cylinder 20 are all placed vertically, and the tensioning cylinder 12 is placed horizontally. The stroke range of all cylinders is pre-set according to the specific industrial process needs.

[0050] When the belt line flips the woven bag and sends it to the seam position, the working process of the automatic seam device of the present invention is as follows:

[0051] (1) In the initial state, the bag opening of the woven bag is located between the upper clamping plate 9 and the lower clamping plate 11. At this time, the piston rods of the lower clamping plate cylinder 10 and the lower roller cylinder 20 are in the extended state, as shown in FIG. Figure 1 As shown, the upper roller 21 and the lower roller 22 are now located outside the upper clamping plate 9 and the lower clamping plate 11, and one side of the upper clamping plate 9 and the lower clamping plate 11 is in a suspended state;

[0052] (2) Then, the piston rod of the baffle cylinder 13 extends, driving the baffle 14 to move downward a certain distance so that it is close to the upper surface of the woven bag;

[0053] (3) The piston rods of the upper clamping plate cylinder 8 and the upper roller cylinder 19 extend to push the first crossbeam 6 downward; the piston rods of the lower clamping plate cylinder 10 and the lower roller cylinder 20 retract to drive the second crossbeam 7 upward, so that the upper clamping plate 9 and the lower clamping plate 11 fit together. Figure 4 As shown, at this time, the bag mouth of the woven bag is folded and pressed between the upper plywood 9 and the lower plywood 11, and the surface of the upper plywood 9 is in contact with the right-angled surface of the baffle 14;

[0054] (4) Figure 2As shown, the piston rod of the tensioning cylinder 12 extends, driving the support base 24 to move horizontally as a whole, thereby driving the first crossbeam 6 and the second crossbeam 7 to move away from the baffle 14, thereby applying a pulling force to the woven bag. At this time, the baffle 14 remains stationary, which can not only increase the flatness of the woven bag, but also reduce the gaps between the yarns.

[0055] (5) Figure 5 As shown, the motor 23 controls the belt to rotate, driving the second frame 4 and the sewing machine assembly to move toward the first frame 3 at the same time. The upper roller 21 slides along the track inside the first crossbeam 6, and the lower roller 22 slides along the track at the bottom of the lower clamping plate 11. At this time, the needle part of the industrial sewing machine 15 is located in the gap between the baffle 14 and the upper clamping plate 9. The industrial sewing machine 15 continues to automatically sew until the seam is completed. Figure 6 As shown, the upper clamping plate 9 and the lower clamping plate 11 are located in the cavity of the industrial sewing machine 15 during sewing;

[0056] (6) After the seam is completed, Figure 7 As shown, the upper clamping plate cylinder 8 retracts 1mm to 2mm, driving the upper clamping plate 9 to slightly lift up 1mm to 2mm, thereby releasing the clamping force between the clamping plates, which can ensure that the belt line can pull the woven bag out from between the clamping plates; then, the piston rod of the baffle cylinder 13 retracts, driving the baffle 14 to move upward;

[0057] (7) The belt line drives the woven bag forward, so that the bag mouth of the woven bag is out of between the upper splint 9 and the lower splint 11;

[0058] (8) The belt line drives the woven bag to continue moving forward, and the motor 23 runs to control the belt rotation, driving the second frame 4 and the sewing machine assembly to retreat, the piston rod of the upper clamping plate cylinder 8 to retract, and the piston rod of the lower clamping plate cylinder 10 to extend, driving the upper clamping plate 9 and the lower clamping plate 11 to separate and return to the initial state.

[0059] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0060] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. An automatic sewing device for bobbin yarn woven bags, characterized in that: It includes a device body, an upper frame, a first frame, a second frame, a lower frame, an upper clamping plate cylinder, a lower clamping plate cylinder, a tensioning cylinder, a baffle cylinder, an upper roller cylinder, and a lower roller cylinder; A support seat is provided on the inner side of the first frame, and the support seat is fixedly connected to the first crossbeam and the second crossbeam; the piston rod of the upper plywood cylinder is fixed above the first crossbeam, and the piston rod of the lower plywood cylinder passes through the first crossbeam and is fixed above the second crossbeam; the cylinder seats of the upper plywood cylinder and the lower plywood cylinder are both fixedly connected to the support seat; one end of the upper plywood is connected to the lower side of the first crossbeam, and one end of the lower plywood is connected to the upper side of the second crossbeam, and the other ends of the upper plywood and the lower plywood are both suspended in the air; The cylinder seat of the tensioning cylinder is fixedly connected to the lower frame, and the piston rod is fixedly connected to the support seat; The upper frame is fixedly connected to the cylinder seat of the baffle cylinder, and the piston rod of the baffle cylinder is fixedly connected to the baffle; The frame edge of the second frame is connected to the sewing machine assembly, and the sewing machine assembly is located between the second frame and the frame of the device body; the sewing machine assembly is slidably connected to the lower frame; An upper roller cylinder and a lower roller cylinder are provided on the inner side of the second frame. The piston rod of the upper roller cylinder is connected to the upper roller, and the piston rod of the lower roller cylinder is connected to the lower roller. The cylinder seats of the upper roller cylinder and the lower roller cylinder are both fixedly connected to the second frame. The upper splint is slidably connected to the upper roller; the lower splint is slidably connected to the lower roller.

2. The automatic sewing device for bobbin woven bags according to claim 1 is characterized in that: The upper clamping plate is located at the lower side of the first cross beam, and the lower clamping plate is located at the upper side of the second cross beam. The upper clamping plate and the lower clamping plate are arranged relatively parallel.

3. The automatic sewing device for bobbin woven bags according to claim 1, characterized in that: A cavity is provided below the support seat, and the tensioning cylinder moves relatively in the cavity.

4. The automatic sewing device for bobbin woven bags according to claim 1, characterized in that: The baffle is in the shape of an inverted right triangle, and the right-angled surface is located on one side of the upper clamping plate and the lower clamping plate.

5. The automatic sewing device for bobbin woven bags according to claim 1 is characterized in that: A belt is fixedly connected to the lower side of the sewing machine assembly, a transmission shaft of the belt is connected to a motor fixed to the device body, and a driven shaft of the belt is connected to the sewing machine assembly.

6. The automatic sewing device for bobbin woven bags according to claim 1, characterized in that: The sewing machine assembly comprises an industrial sewing machine, a sewing machine coil and a sewing machine fixing frame. The top of the industrial sewing machine is fixedly connected to the sewing machine coil, and the bottom end is fixedly connected to the sewing machine fixing frame.

7. The automatic sewing device for bobbin woven bags according to claim 6, characterized in that: The upper portion of the lower frame is fixedly connected to a guide rail of the sewing machine. A sliding block is provided below the fixed frame of the sewing machine. The sliding block is slidably connected to the guide rail of the sewing machine.

8. The automatic sewing device for bobbin woven bags according to claim 1, characterized in that: The number of the upper rollers is 2, and the number of the lower roller is 1.

9. The automatic sewing device for bobbin woven bags according to claim 1, characterized in that: The upper splint is provided with a track for the upper roller to slide inside; the bottom of the upper splint is a trapezoidal groove, the lower splint is a trapezoidal structure, the width of the trapezoidal groove at the bottom of the upper splint is greater than the width of the lower splint; the bottom of the lower splint is provided with a track for the lower roller to slide.

10. The automatic sewing device for bobbin woven bags according to claim 1, characterized in that: When the belt line flips the woven bag and sends it to the seam position, the working process of the automatic seam device is as follows: (1) In the initial state, the bag opening of the woven bag is located between the upper and lower splints. At this time, the piston rods of the lower splint cylinder and the lower roller cylinder are in an extended state, the upper roller and the lower roller are located outside the upper and lower splints, and one side of the upper and lower splints is in a suspended state; (2) Then, the piston rod of the baffle cylinder extends, driving the baffle to move downward a certain distance so that it is close to the upper surface of the woven bag; (3) The piston rods of the upper plate cylinder and the upper roller cylinder extend to push the first crossbeam downward; the piston rods of the lower plate cylinder and the lower roller cylinder retract to drive the second crossbeam upward, thereby making the upper plate and the lower plate fit together. At this time, the bag opening of the woven bag is folded and pressed between the upper plate and the lower plate, and the surface of the upper plate fits the right-angle surface of the baffle; (4) The piston rod of the tensioning cylinder extends, driving the support seat to move horizontally as a whole, and then driving the first beam and the second beam to move away from the baffle, thereby applying a pulling force to the woven bag, while the baffle remains stationary; (5) The motor controls the belt to rotate, driving the second frame and the sewing machine assembly to move toward the first frame at the same time. The upper roller slides along the track inside the first beam, and the lower roller slides along the track at the bottom of the lower clamping plate. At this time, the needle part of the industrial sewing machine is located in the gap between the baffle and the upper clamping plate. The industrial sewing machine continues to automatically sew until the seam is completed. When sewing, the upper clamping plate and the lower clamping plate are located in the cavity of the industrial sewing machine. (6) After the seam is completed, the upper clamping plate cylinder retracts 1mm to 2mm, driving the upper clamping plate to slightly lift up 1mm to 2mm, thereby releasing the clamping force between the clamping plates, ensuring that the belt line can pull the woven bag out from between the clamping plates; then, the piston rod of the baffle cylinder retracts, driving the baffle to move upward; (7) The belt line drives the woven bag forward, so that the bag mouth of the woven bag is out of between the upper and lower splints; (8) The belt line drives the woven bag to continue moving forward, and the motor controls the belt to rotate, driving the second frame and the sewing machine assembly to retreat. The piston rod of the upper splint cylinder retracts, and the piston rod of the lower splint cylinder extends, driving the upper splint and the lower splint to separate and return to the initial state.

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