Copper-chromium contact surface laser remelting rotating device

Abstract

The invention discloses a copper-chromium contact surface laser remelting rotating device. The copper-chromium contact surface laser remelting rotating device comprises a working table, a rotating clamping table, an adjusting assembly and a laser, wherein the rotating clamping table and the adjusting assembly are arranged on the working table; the rotary clamping table comprises a mounting seat, a rotary seat rotationally clamped on the mounting seat, a movable clamping block arranged on the rotary seat and a rotary motor for providing power for the rotary seat; the adjusting assembly comprises a first arc-shaped frame and an adjusting seat; the laser is arranged on the lower bottom surface of the adjusting seat; the device is reasonable in structural design, the laser is arranged on the adjusting seat capable of freely moving along the first arc-shaped frame, so that the laser can be matched with the curved surface radian of the R chamfer of the copper-based contact, it is ensured that a laser beam can'follow 'each point of the chamfer surface, the machining blind area of the curved surface radian in the circumferential direction is completely eliminated, and the machining efficiency is improved. The microstructure of a copper-chromium alloy remelting layer is refined, alloy elements are distributed more evenly, and the hardness, abrasion resistance, arc erosion resistance and other performance of the surface of the copper-chromium contact are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of laser remelting technology, and more specifically to a rotating device for laser remelting of copper-chromium contact surfaces. Background Technology

[0002] In modern power systems, safe and efficient power transmission and distribution are crucial. Copper-chromium alloy contacts, as key components of power equipment, bear the heavy responsibility of connecting and disconnecting current. Their performance directly affects the reliability and stability of power equipment. Especially under the harsh operating conditions of high voltage and high current, copper-chromium alloy contacts face many severe challenges. Laser remelting technology, as an advanced material surface treatment technology, has brought new opportunities to improve the performance of copper-chromium alloy contacts. Through the rapid heating and cooling of high-energy laser beams, the alloy elements on the contact surface can be melted, diffused, and solidified, optimizing the alloy microstructure at the micro level, refining the grains, and improving the uniformity of alloy element distribution. This microstructure optimization can significantly improve the hardness, wear resistance, arc erosion resistance, and weld resistance of copper-chromium alloy contacts, effectively extending the service life of contacts and improving the operational reliability of power equipment.

[0003] Patent CN222834397U describes a laser cladding device with an auxiliary support structure. The device fixes a copper-chromium contact on a rotating platform, which drives the contact to rotate, allowing the laser to scan different areas of the contact from various angles. For example, when processing columnar copper-chromium contacts, the rotating platform rotates the contact around its central axis, and the laser irradiates from the side. This method expands the laser's effective range to some extent, enabling remelting of certain circumferential areas of the contact. However, when the contact has a complex three-dimensional shape, such as not only circumferential changes but also axial curves, chamfers, etc., a single rotating platform cannot ensure that the laser comprehensively and uniformly covers all complex parts of the contact. For the R-shaped chamfer at the contact end, because the laser cannot simultaneously accommodate changes in angle and position, insufficient remelting still occurs, failing to meet the requirements for high-precision, all-around remelting of copper-chromium contacts.

[0004] Patent CN117690742A describes a method for modifying the surface of copper-chromium contacts using SLM printing technology. This method utilizes 3D printing equipment to print a remelted layer onto the surface of a sintered copper-chromium contact made of mixed powder. This technology designs different printing parameters for different areas of the contact (such as the central plane area and the rounded edge area of ​​the front arc-burning surface, and the welding area of ​​the back welding surface), which can improve surface density to some extent. However, this technology focuses on printing and forming; when remelting pre-formed copper-chromium contacts, the equipment is complex and costly, making it difficult to widely apply to large-scale contact remelting. Another method involves fixing copper-chromium alloy contacts in a temperature-controlled fixture within a controlled oxygen chamber and processing their surface by controlling a laser along a predetermined path. While this method can form a fine-grained layer on the contact surface and improve some performance, it is also difficult to achieve uniform and efficient remelting of various parts when dealing with complex-shaped contacts. Furthermore, the operation is cumbersome and has high requirements for equipment and the environment. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a rotating device for laser remelting of copper-chromium contact surfaces.

[0006] The technical solution of the present invention is: a rotating device for laser remelting of copper-chromium contact surface, comprising a worktable, a rotating chuck disposed on the upper surface of the worktable, an adjustment component disposed on the worktable and located outside the rotating chuck, and a laser movably disposed on the adjustment component; The rotary table includes a mounting base located at the center of the upper surface of the worktable, a rotary seat rotatably engaged with the upper surface of the mounting base, several movable locking blocks equidistantly distributed on the upper surface of the rotary seat and slidably engaged with the rotary seat, and a rotary motor located inside the mounting base that provides power to the rotary seat. A tensioning ring is rotatably engaged inside the rotary seat, with a helical groove on its upper surface and a conical toothed groove on its outer side wall. Each movable locking block has a threaded seat on its underside that is threaded into the helical groove. A tensioning shaft is rotatably engaged on the rotary seat, with one end connected to a bevel gear meshing with the conical toothed groove, and the other end connected to an internal hexagonal end cap. A positioning shaft is rotatably engaged with the mounting base at the bottom of the rotary seat, and a drive gear ring is sleeved on the outside of the positioning shaft. A drive gear meshing with the drive gear ring is connected to the output end of the rotary motor. The adjustment assembly includes a first arc-shaped frame disposed on the upper surface of the workbench and an adjustment seat slidably engaged with the inner side wall of the first arc-shaped frame; two arc-shaped guide grooves are provided through the first arc-shaped frame, and a gear groove is provided on the side wall of the first arc-shaped frame between the two arc-shaped guide grooves; a connecting post is rotatably engaged with the adjustment seat and slidably engaged with the two arc-shaped guide grooves respectively; an operating rod is rotatably engaged with the adjustment seat, and an adjustment gear is connected to the operating rod and meshes with the gear groove; The laser is located on the bottom surface of the adjustment base.

[0007] Furthermore, a rotating sleeve is fitted around the outside of the connecting column; Note: By setting a rotating sleeve on the outside of the connecting column, the stability of the first arc frame when sliding on the adjusting seat can be improved, thereby enabling the copper-chromium alloy to be uniformly and completely fused onto the surface of the contact material, improving the reliability of the copper-chromium alloy contacts.

[0008] Furthermore, a movable ball head is connected to the bottom surface of the adjusting seat, and the laser is movably engaged with the movable ball head through the connecting ball seat; Note: The connection between the movable ball head and the connecting ball seat allows the laser to be adjusted at any angle on the bottom surface of the adjustment seat.

[0009] Furthermore, hinge seats are provided on both sides of the upper surface of the workbench, and the two ends of the first arc frame are respectively movably hinged to the two hinge seats one by one; both ends of the first arc frame are provided with sector-shaped tooth blocks, and the two hinge seats are rotatably engaged with linkage gears that mesh with the sector-shaped tooth blocks at the corresponding positions. Explanation: The first arc-shaped frame is movably hinged to the worktable using a hinged base, which allows for adjustment of the laser's pitch angle; while the meshing of the sector-shaped toothed block and the linkage gear improves the accuracy of the first arc-shaped frame rotating along the hinged base.

[0010] Furthermore, both sides of the linkage gear inside one of the hinge seats and located at the corresponding position are slidably engaged with locking teeth blocks via sliding rods. Both sliding rods are fitted with compression springs that abut against the sides of the two locking teeth blocks that are far apart from each other. Both locking teeth blocks are connected with wedge-shaped seats. Inside the hinge seat, there is an unlocking rod that abuts against both wedge seats simultaneously. The unlocking rod is connected with a push plate that penetrates the hinge seat. Explanation: The locking tooth block slides along the sliding rod under the action of the compression spring and engages with the linkage gear to lock, thereby preventing the first arc frame from swaying during laser operation and improving the stability of the device. When it is necessary to adjust the rotation of the first arc frame on the hinge seat, the push plate is used to push the unlocking rod to move inside the hinge seat. The connection between the unlocking rod and the wedge seat causes the locking tooth block to slide on the sliding rod and disengage from the linkage gear.

[0011] Furthermore, both ends of the unlocking lever are rotatably engaged with sliding rollers; Note: By installing a sliding roller on the unlocking lever, the frictional resistance between the unlocking lever and the wedge seat can be reduced, improving the smoothness of the unlocking lever's movement inside the hinge seat.

[0012] Furthermore, a second arc-shaped frame is connected to the bottom of the mounting base, and a U-shaped bracket is provided on the upper surface of the worktable to slide and engage with the second arc-shaped frame; an arc-shaped rack is provided on the lower bottom surface of the second arc-shaped frame, and a micro motor is provided on the upper surface of the worktable, with a small gear connected to the output end of the micro motor and meshing with the arc-shaped rack. Explanation: A micro motor drives a small gear to rotate, and the meshing action of the small gear and the arc-shaped rack drives the second arc-shaped frame to deflect on the U-shaped chuck, thereby adjusting the tilt angle of the rotating chuck and allowing the rotating seat to rotate at any tilt angle.

[0013] Furthermore, a shielding cover located outside the first arc-shaped frame is provided on the upper surface of the workbench; Note: By setting up a shield, the high temperature heat generated during laser operation can be effectively prevented from causing harm to external equipment and personnel.

[0014] Furthermore, several coolant nozzles are evenly distributed around the upper surface of the worktable and located on the circumference of the rotating seat. A liquid collection chamber is provided inside the worktable, and a collection trough communicating with the liquid collection chamber is provided on the upper surface of the worktable. Instructions: During use, external coolant is introduced into each coolant nozzle. The coolant sprayed from the nozzles cools the rotary seat, preventing heat from being transferred to the rotary seat during the processing of the copper-chromium contact material and causing damage.

[0015] The working principle of this invention is as follows: In use, the laser is fixed to the bottom surface of the adjusting base, and the copper-based contact is placed above the rotating base. An external tool is used to twist the tensioning shaft, and the meshing of the bevel gear and the conical tooth groove causes the tensioning ring to rotate inside the rotating base. The connection between the threaded seat and the spiral groove causes the movable blocks to move closer together on the rotating base, clamping and fixing the copper-based contact. A rotary motor drives the drive gear to rotate, and the meshing of the drive gear and the drive gear ring causes the rotating base and the copper-based contact to rotate on the mounting base. The heat from the high-energy laser beam emitted by the laser melts, diffuses, and solidifies the copper-chromium alloy elements on the surface of the copper-based contact, optimizing the alloy's microstructure at the microscopic level. During the laser remelting process of the copper-based contact surface, the operating lever drives the adjusting gear to rotate. The meshing of the adjusting gear and the gear groove causes the adjusting base to move the laser along the arc-shaped guide groove on the first arc-shaped frame, adjusting the position of the laser so that the copper-chromium alloy elements in all areas of the copper-based contact surface can be melted.

[0016] Compared with the prior art, the beneficial effects of the present invention are reflected in the following aspects: First, the present invention has a reasonable structural design. By setting the laser on an adjustment seat that can move freely along the first arc frame, the laser can match the curvature of the R-shaped chamfer of the copper-based contact, ensuring that the laser beam can "follow" every point of the chamfer surface, completely eliminating the blind spots in the circumferential direction and the curvature of the surface, thus refining the microstructure of the copper-chromium alloy remelting layer, making the alloy elements more uniformly distributed, and significantly improving the hardness, wear resistance, and arc erosion resistance of the copper-chromium contact surface. Secondly, the first arc-shaped frame of the present invention can be deflected and adjusted on the hinge seat, so that the laser angle of the laser and the rotation of the copper-based contact are coordinated, and the laser beam spot shape on the R-chamfer surface is always consistent and the energy density is uniform, ultimately forming a remelted layer with uniform thickness and dense structure, avoiding the occurrence of local overmelting or incomplete melting, and improving the bonding strength between the copper-chromium remelted layer and the copper-based contact. Third, the laser and rotating stage of the present invention can be coupled and rotated in multiple dimensions, so that the copper-chromium alloy elements in each area of ​​the copper-based contact surface can be remelted, which can extend the arc life of the contact and improve the electrical contact reliability of the contact. Attached Figure Description

[0017] Figure 1 This is a longitudinal sectional view of the present invention; Figure 2 This is a schematic diagram showing the connection between the rotating chuck, the adjusting assembly, and the worktable of the present invention; Figure 3 This is a schematic diagram of the rotating card table of the present invention; Figure 4 This is the present invention. Figure 3 A magnified view of a portion of point A in the middle; Figure 5 This is a distribution diagram of the movable blocks of the present invention on the rotating base; Figure 6 This is a schematic diagram of the connection between the tensioning shaft and the tensioning ring of the present invention; Figure 7 This is a schematic diagram showing the connection between the laser and the adjustment base of the present invention; Figure 8 This is a schematic diagram of the connection between the first arc-shaped frame and the hinge seat of the present invention; Figure 9 This is a schematic diagram of the connection between the locking tooth block and the linkage gear of the present invention; Among them, 1-worktable, 10-liquid collection chamber, 11-collection tank, 2-rotary clamping table, 20-mounting base, 21-rotary seat, 210-positioning vertical shaft, 211-drive gear ring, 22-movable clamping block, 220-threaded seat, 23-rotary motor, 230-drive gear, 24-tensioning ring, 240-spiral groove, 241-conical tooth groove, 25-tensioning shaft, 250-bevel gear, 251-internal hexagonal end cap, 3-adjusting component, 30-first arc-shaped frame, 300-arc-shaped guide groove, 301-gear groove, 302-sector-shaped tooth block 31-Adjusting seat, 310-Connecting column, 311-Rotating sleeve, 32-Operating lever, 320-Adjusting gear, 4-Laser, 40-Modible ball head, 41-Connecting ball seat, 5-Hinged seat, 50-Linkage gear, 51-Sliding rod, 510-Compression spring, 52-Locking tooth block, 520-Wedge seat, 53-Unlocking lever, 530-Push plate, 531-Sliding roller, 6-Second arc frame, 60-U-shaped card seat, 61-Arc rack, 62-Micro motor, 620-Small gear, 7-Shielding cover, 8-Coolant nozzle. Detailed Implementation

[0018] Example 1 like Figure 1 The rotating device for laser remelting of copper-chromium contact surfaces shown includes a worktable 1, a rotating chuck 2 disposed on the upper surface of the worktable 1, an adjustment component 3 disposed on the worktable 1 and located outside the rotating chuck 2, and a laser 4 (commercially available product) movably disposed on the adjustment component 3. like Figure 2 , 3 As shown in Figures 4, 5, and 6, the rotating clamping table 2 includes a mounting base 20 located at the center of the upper surface of the worktable 1, a rotating seat 21 rotatably engaged with the upper surface of the mounting base 20, three movable clamping blocks 22 equidistantly distributed on the upper surface of the rotating seat 21 and slidably engaged with the rotating seat 21, and a rotary motor 23 located inside the mounting base 20 and providing power to the rotating seat 21; a tensioning ring 24 is rotatably engaged inside the rotating seat 21, the upper surface of the tensioning ring 24 is provided with a spiral groove 240, and the outer wall of the tensioning ring 24 is provided with a conical toothed groove 241; the bottom surface of each movable clamping block 22 is provided with a screw threadedly connected to the spiral groove 240. The rotating seat 21 has a tensioning shaft 25 rotatably engaged with a tensioning base 220. One end of the tensioning shaft 25 is connected to a bevel gear 250 that meshes with a conical toothed groove 241, and the other end of the tensioning shaft 25 is connected to an internal hexagonal end cap 251. The bottom end of the rotating seat 21 is connected to a positioning shaft 210 that is movably engaged with the mounting base 20. A drive gear ring 211 is sleeved on the outside of the positioning shaft 210. The output end of the rotary motor 23 is connected to a drive gear 230 that meshes with the drive gear ring 211. The rotary motor 23 is a product of existing technology, such as an RV type geared motor produced by Shanghai Fengxin Transmission Machinery Co., Ltd. like Figure 2 , 7 As shown, the adjustment assembly 3 includes a first arc-shaped frame 30 disposed on the upper end face of the workbench 1 and an adjustment seat 31 slidably engaged with the inner side wall of the first arc-shaped frame 30; two arc-shaped guide grooves 300 are provided through the first arc-shaped frame 30, and a gear groove 301 is provided on the side wall of the first arc-shaped frame 30 and located between the two arc-shaped guide grooves 300; a connecting post 310 is rotatably engaged with the adjustment seat 31 and slidably engaged with the two arc-shaped guide grooves 300 respectively; a rotating sleeve 311 is sleeved on the outside of the connecting post 310; an operating rod 32 is rotatably engaged with the adjustment seat 31, and an adjustment gear 320 is connected to the operating rod 32 and meshes with the gear groove 301; like Figure 2 As shown, the laser 4 is located on the bottom surface of the adjustment base 31.

[0019] Example 2 The difference between this embodiment and Embodiment 1 is that: like Figure 7 As shown, a movable ball head 40 is connected to the bottom surface of the adjustment seat 31, and the laser 4 is movably engaged with the movable ball head 40 through the connecting ball seat 41; the connection between the movable ball head 40 and the connecting ball seat 41 enables the laser 4 to be adjusted at any angle on the bottom surface of the adjustment seat 31.

[0020] Example 3 The difference between this embodiment and Embodiment 2 is that: like Figure 1 , 8 As shown, hinge seats 5 are provided on both sides of the upper surface of the worktable 1. The two ends of the first arc frame 30 are respectively movably hinged to the two hinge seats 5. The two ends of the first arc frame 30 are provided with sector-shaped tooth blocks 302. The two hinge seats 5 are rotatably engaged with linkage gears 50 that mesh with the sector-shaped tooth blocks 302 at the corresponding positions. By using the hinge seats 5 to movably hinge the first arc frame 30 to the worktable 10, the pitch angle of the laser 4 can be adjusted. The meshing action of the sector-shaped tooth blocks 302 and the linkage gears 50 can improve the accuracy of the first arc frame 30 when rotating along the hinge seats 5.

[0021] Example 4 The difference between this embodiment and Embodiment 3 is that: like Figure 8 , 9As shown, inside one of the hinge seats 5, and at the corresponding position, both sides of the linkage gear 50 are slidably engaged with locking teeth 52 via sliding rods 51. Each of the two sliding rods 51 is fitted with a compression spring 510 that abuts against the side of the two locking teeth 52 that is away from each other. Each of the two locking teeth 52 is connected to a wedge-shaped seat 520. Inside the hinge seat 5, an unlocking rod 53 is slidably engaged, simultaneously abutting against both wedge seats 520. A push plate 530 penetrating the hinge seat 5 is connected to the unlocking rod 53. Both ends of the unlocking rod 53 are rotatably engaged with sliding rollers. Wheel 531; Locking tooth block 52 slides along sliding rod 51 under the action of compression spring 510 and engages with linkage gear 50 to lock, thereby preventing the first arc frame 30 from swinging during the operation of laser 4, which is beneficial to improving the stability of the device; When it is necessary to adjust the rotation of the first arc frame 30 on the hinge seat 5, the push plate 530 pushes the unlocking rod 53 to move inside the hinge seat 5, and the connection between the unlocking rod 53 and the wedge seat 520 makes the locking tooth block 52 slide on sliding rod 51 and disengage from linkage gear 50.

[0022] Example 5 The difference between this embodiment and embodiment 4 is that: like Figure 2 As shown, the bottom of the mounting base 20 is connected to a second arc-shaped frame 6, and the upper surface of the worktable 1 is provided with a U-shaped bracket 60 that slides and engages with the second arc-shaped frame 6; the lower surface of the second arc-shaped frame 6 is provided with an arc-shaped rack 61, and the upper surface of the worktable 1 is provided with a micro motor 62 (commercially available product). The output end of the micro motor 62 is connected to a pinion 620 that meshes with the arc-shaped rack 61; the micro motor 62 drives the pinion 620 to rotate, and the meshing action of the pinion 620 and the arc-shaped rack 61 drives the second arc-shaped frame 6 to deflect on the U-shaped bracket 60, thereby adjusting the tilt angle of the rotating bracket 2, so that the rotating base 21 can rotate at any tilt angle.

[0023] Example 6 The difference between this embodiment and embodiment 5 is that: like Figure 1 As shown, a shielding cover 7 is provided on the upper surface of the workbench 1 outside the first arc frame 30. By setting the shielding cover 7, the high temperature heat of the laser 4 during operation can be effectively prevented from causing damage to external equipment and personnel.

[0024] Example 7 The difference between this embodiment and embodiment 6 is that: like Figure 1As shown, four coolant nozzles 8 are evenly distributed around the upper surface of the worktable 1 and the circumference of the rotary seat 21. A liquid collection chamber 10 is provided inside the worktable 1, and a collection groove 11 communicating with the liquid collection chamber 10 is provided on the upper surface of the worktable 1. External coolant is introduced into each coolant nozzle 8, and the coolant sprayed from the coolant nozzles 8 is used to cool the rotary seat 21, so as to avoid heat transfer to the rotary seat 21 during the processing of copper-chromium contact material and damage to the rotary seat 21.

Claims

1. A rotating device for laser remelting of copper-chromium contact surfaces, characterized in that, It includes a worktable (1), a rotating chuck (2) disposed on the upper surface of the worktable (1), an adjustment component (3) disposed on the worktable (1) and located outside the rotating chuck (2), and a laser (4) movably disposed on the adjustment component (3). The rotating table (2) includes a mounting base (20) located at the center of the upper surface of the workbench (1), a rotating seat (21) rotatably engaged with the upper surface of the mounting base (20), several movable locking blocks (22) equidistantly distributed on the upper surface of the rotating seat (21) and slidably engaged with the rotating seat (21), and a rotating motor (23) located inside the mounting base (20) and providing power to the rotating seat (21). The adjustment assembly (3) includes a first arc-shaped frame (30) disposed on the upper end face of the workbench (1) and an adjustment seat (31) slidably engaged with the inner side wall of the first arc-shaped frame (30); two arc-shaped guide grooves (300) are provided through the first arc-shaped frame (30), and a gear groove (301) is provided on the side wall of the first arc-shaped frame (30) between the two arc-shaped guide grooves (300); a connecting post (310) is rotatably engaged with the adjustment seat (31), which is slidably engaged with the two arc-shaped guide grooves (300) respectively; an operating rod (32) is rotatably engaged with the adjustment seat (31), and an adjustment gear (320) is connected to the operating rod (32) and meshes with the gear groove (301); The laser (4) is located on the bottom surface of the adjustment seat (31).

2. The rotating device for laser remelting of copper-chromium contact surfaces according to claim 1, characterized in that, A rotating sleeve (311) is fitted around the outside of the connecting column (310).

3. The rotating device for laser remelting of copper-chromium contact surfaces according to claim 1, characterized in that, The bottom surface of the adjustment seat (31) is connected to a movable ball head (40), and the laser (4) is movably engaged with the movable ball head (40) through the connecting ball seat (41).

4. The rotating device for laser remelting of copper-chromium contact surfaces according to claim 1, characterized in that, The workbench (1) has hinge seats (5) on both sides of its upper surface. The two ends of the first arc frame (30) are respectively movably hinged to the two hinge seats (5). The two ends of the first arc frame (30) are provided with fan-shaped tooth blocks (302). The two hinge seats (5) are rotatably engaged with the fan-shaped tooth blocks (302) at the corresponding positions.

5. The rotating device for laser remelting of copper-chromium contact surfaces according to claim 4, characterized in that, Inside one of the hinge seats (5) and at the corresponding position, both sides of the linkage gear (50) are slidably engaged with locking teeth (52) via sliding rods (51). Both sliding rods (51) are fitted with compression springs (510) that abut against the side of the two locking teeth (52) that is far away from each other. Both locking teeth (52) are connected with wedge seats (520). Inside the hinge seat (5), there is an unlocking rod (53) that abuts against both wedge seats (520) simultaneously. The unlocking rod (53) is connected with a push plate (530) that penetrates the hinge seat (5).

6. The rotating device for laser remelting of copper-chromium contact surfaces according to claim 5, characterized in that, Both ends of the unlocking rod (53) are rotatably engaged with sliding rollers (531).

7. The rotating device for laser remelting of copper-chromium contact surfaces according to claim 5, characterized in that, The bottom of the mounting base (20) is connected to a second arc frame (6), and the upper surface of the workbench (1) is provided with a U-shaped card seat (60) that slides and engages with the second arc frame (6); the lower surface of the second arc frame (6) is provided with an arc rack (61), and the upper surface of the workbench (1) is provided with a micro motor (62), and the output end of the micro motor (62) is connected to a small gear (620) that meshes with the arc rack (61).

8. The rotating device for laser remelting of copper-chromium contact surfaces according to claim 1, characterized in that, The upper surface of the workbench (1) is provided with a shield (7) located outside the first arc frame (30).

9. The rotating device for laser remelting of copper-chromium contact surfaces according to claim 1, characterized in that, Both ends of the unlocking rod (53) are rotatably engaged with sliding rollers (531).

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