Device for testing telescopic service life of luggage case pull rod

Abstract

The invention relates to the field of mechanical testing, in particular to a luggage case pull rod telescopic life testing device which comprises a testing frame, a servo reciprocating push cylinder is fixedly installed on the inner side of the testing frame, a bearing frame is fixedly installed at the telescopic end of the servo reciprocating push cylinder, and a control panel is elastically installed in the middle of the inner side of the bearing frame. A bearing seat is fixedly installed at the front end of the control panel, a rod clamping piece is arranged on the bearing seat, a bearing shaft is rotatably installed on the upper portion of the bearing seat in a penetrating mode, an arc-shaped bent piece is fixedly installed at the front end of the bearing shaft, a servo motor is installed at the upper end of the bearing seat, and the servo motor is connected with the bearing shaft. And two vertical frames are symmetrically and fixedly mounted at the rear part of the upper end of the testing frame. The telescopic service life test of the pull rod is ensured to be smoothly carried out, and the phenomenon that the test is influenced due to damage of an internal buckle caused by continuous push-pull of the pull rod during locking is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mechanical testing, in particular to a luggage trolley rod telescopic life testing device. BACKGROUND

[0002] The luggage is a portable storage container with a storage chamber and can be moved through the bottom roller. The matching trolley rod is usually a multi-section telescopic structure with a built-in positioning buckle. After being pulled up, it can provide a holding force point to pull the box body. After being folded, it can fit the box body to reduce the occupied space, and together constitute a convenient travel storage tool.

[0003] In order to understand whether the luggage trolley rod meets the production standard, the telescopic life of the trolley rod usually needs to be tested. However, the existing testing device can only realize the push-pull function. Therefore, when testing the trolley rod, since the trolley rod is built-in with a positioning buckle, after being pushed or pulled to the gear position of the trolley rod, the trolley rod will be locked, so that the trolley rod cannot be continuously pushed or pulled, which causes that the telescopic life of the trolley rod cannot be normally tested. SUMMARY

[0004] The purpose of the present application is to solve the problems in the background art and provide a luggage trolley rod telescopic life testing device.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: a luggage trolley rod telescopic life testing device, comprising a testing frame, a servo reciprocating push cylinder is fixedly installed on the inner side of the testing frame, a bearing frame is fixedly installed at the telescopic end of the servo reciprocating push cylinder, a control board is elastically installed at the inner side of the middle part of the bearing frame, a bearing seat is fixedly installed at the front end of the control board, a clamping rod piece is arranged on the bearing seat, a bearing shaft is rotatably installed through the upper part of the bearing seat, an arc-shaped bending piece is fixedly installed at the front end of the bearing shaft, a servo motor is installed at the upper end of the bearing seat, the servo motor is connected with the bearing shaft, two vertical frames are symmetrically fixedly installed at the upper end of the testing frame, a plurality of protective positioning frames are elastically installed on the two vertical frames, the positions of the plurality of protective positioning frames match the gear positions of the trolley rod, a contact sensor is installed through the upper end of one side and the lower end of the other side of the control board, the contact sensor and the servo motor are electrically connected through a controller, the bearing shaft penetrates out from the rear end of the bearing frame, a separation frame is inlaid at the rear end of the bearing shaft, a wheel body is installed at the upper and lower ends of the separation frame, a separation rail is connected to the rear end of the protective positioning frame on both sides, and a luggage fixing piece is arranged on the testing frame.

[0006] Preferably, a connecting shaft is coaxially fixedly installed at the output end of the servo motor, a bevel gear is inlaid on the outer surface of the connecting shaft and the bearing shaft at the end thereof, and the two bevel gears are meshed.

[0007] Preferably, the rear end of the servo motor is fixedly provided with a motor frame, the lower end of the motor frame is fixedly connected with the bearing seat, the outer surface of the connecting shaft is rotatably provided with a shaft frame, and the lower end of the shaft frame is fixedly connected with the bearing seat.

[0008] Preferably, two guide rods are embedded between the upper and lower end faces of the inner part of the bearing frame, the control plate is slidably arranged on the outer surface of the guide rods, and two adaptive springs are wound around the outer sides of the guide rods, respectively.

[0009] Preferably, a sleeve is slidably arranged on the outer surface of the protective positioning frame, the sleeve is embedded in the front end of the stand, a reset spring is fixedly arranged on the inner side of the sleeve, the end of the reset spring is fixedly connected with the protective positioning frame, and a connecting frame is arranged in the middle of the opposite sides of the two separation rails.

[0010] Preferably, the clamping rod part comprises an upper clamping frame fixedly arranged in the middle of the front end of the bearing seat, a threaded column rotatably arranged at the lower end of the bearing seat, a lower clamping plate screwed on the outer side of the threaded column, and a guide column extended from the lower end of the bearing seat to the side close to the threaded column.

[0011] Preferably, the fixed box part comprises rear bending frames fixedly arranged in the middle of the two sides of the test frame, L-shaped clamping grooves formed at the upper end front edges of the rear bending frames, front bending frames arranged in front of the rear bending frames, and the rear end portions of the front bending frames inserted into the L-shaped clamping grooves.

[0012] Preferably, the two ends of the control plate are provided with second inclined guide faces, the second inclined guide faces of the two ends of the control plate are oppositely arranged, the opposite sides of the protective positioning frames are provided with first inclined guide faces, and the first inclined guide faces of the protective positioning frames are oppositely arranged.

[0013] Compared with the prior art, the present application has the following beneficial effects: 1. When the servo reciprocating push cylinder drives the bearing frame to move up and down continuously to push and pull the pull rod of the luggage box, when the pull rod is pulled to the gear position and the buckle in the pull rod is locked, the control plate is just on the protective positioning frame, at this time, the contact sensor will drive the servo motor to work to drive the arc-shaped bending piece on the bearing shaft to rotate downward to press the button on the pull rod, so that the buckle in the pull rod is unlocked, and the pull rod can be continuously pushed and pulled, thereby ensuring that the extension and retraction life test of the pull rod can be smoothly carried out.

[0014] 2, When the buckle inside the pull rod is locked, the control plate is on the protective positioning frame, the control plate is limited by the protective positioning frame and can keep still, so it cannot continue to push and pull the pull rod, at this time the bearing frame still keeps moving, and the adaptive spring will deform, so that the movement of the bearing frame will not be blocked, when the bearing shaft drives the arc-shaped bending piece to rotate downward, the buckle inside the pull rod is unlocked, the bearing shaft continues to rotate, the arc segment of the arc-shaped bending piece continues to press the button on the pull rod, so that the buckle inside the pull rod remains unlocked, and the wheel body on the separation frame rotates under the drive of the bearing shaft to push the two separation rails to move in opposite directions, thereby driving the protective positioning frame to move in the opposite direction, so that the end of the protective positioning frame is separated from the control plate, at this time the control plate loses the limitation of the protective positioning frame, and the adaptive spring restores the deformation to push the control plate to reset to the middle of the bearing frame, and the control plate pushes and pulls the pull rod during the resetting process, so that the pull rod is separated from the gear position, then the servo motor drives the bearing shaft to reverse to reset to release the button, then the bearing frame continues to push and pull the pull rod, so that the buckle inside the pull rod is locked, and the pull rod is not continuously pushed and pulled to avoid the internal buckle being damaged when locked, which affects the test. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a structural schematic view of the luggage pull rod telescopic service life testing device. Figure 2 It is a schematic view of the servo motor of the luggage pull rod telescopic service life testing device. Figure 3 It is a schematic view of the upper clamping frame of the luggage pull rod telescopic service life testing device. Figure 4 It is a schematic view of the bearing frame of the luggage pull rod telescopic service life testing device. Figure 5 It is a schematic view of the control plate of the luggage pull rod telescopic service life testing device. Figure 6 It is a schematic view of the Figure 1 enlarged view of A. Figure 7 It is an internal view of the frame sleeve of the luggage pull rod telescopic service life testing device. Figure 8 It is a use view of the luggage pull rod telescopic service life testing device. Figure 9 It is a schematic view of the Figure 8 enlarged view of B.

[0016] In the figure: 1, test frame; 2, rear bending frame; 3, front bending frame; 4, servo reciprocating push cylinder; 5, pressing frame; 6, servo motor; 7, protective positioning frame; 8, separation rail; 9, frame sleeve; 10, first inclined guide surface; 11, vertical frame; 12, control panel; 13, upper clamping frame; 14, connecting shaft; 15, bevel gear; 16, bearing shaft; 17, arc-shaped bending piece; 18, lower clamping plate; 19, bearing seat; 20, bearing frame; 21, separation frame; 22, wheel body; 23, contact sensor; 24, guide column; 25, threaded column; 26, L-shaped clamping groove; 27, connecting frame; 28, guide rod; 29, adaptive spring; 30, second inclined guide surface; 31, reset spring; 32, motor frame; 33, shaft frame; 34, luggage case; 35, pull rod. DETAILED DESCRIPTION

[0017] The following description is provided to enable any person skilled in the art to practice the present application. The preferred embodiments described below are only examples of the present application and other obvious variants can be conceived by those skilled in the art.

[0018] As Figures 1-9The luggage pull rod telescopic life test device shown, including test frame 1, the inner side of test frame 1 is fixedly installed servo reciprocating push cylinder 4, the telescopic end of servo reciprocating push cylinder 4 is fixedly installed bearing frame 20, servo reciprocating push cylinder 4 drives bearing frame 20 to move up and down constantly, to constantly push and pull the pull rod 35 of luggage 34, the inner side of bearing frame 20 is elastically installed control panel 12, the front end of control panel 12 is fixedly installed bearing seat 19, the bearing seat 19 is provided with clamping rod piece, the upper portion of bearing seat 19 is rotatably installed bearing shaft 16, bearing seat 19 plays the role of bearing bearing shaft 16, the front end of bearing shaft 16 is fixedly installed arc-shaped bending piece 17, the upper end of bearing seat 19 is installed servo motor 6, servo motor 6 is connected with bearing shaft 16, servo motor 6 plays the role of driving bearing shaft 16 to rotate, the upper end of test frame 1 is symmetrically fixedly installed two stands 11, the stand 11 plays the role of bearing, a plurality of protective positioning frames 7 are elastically installed on the two stands 11, the positions of the plurality of protective positioning frames 7 are matched with the gear positions of pull rod 35, can ensure that the gear position of pull rod 35 is pulled, when the buckle inside pull rod 35 is locked, control panel 12 just tops on protective positioning frame 7, the upper end of control panel 12 one side, the other side of lower end is rotatably installed contact sensor 23, after the contact sensor 23 senses protective positioning frame 7, servo motor 6 is driven to work to drive arc-shaped bending piece 17 on bearing shaft 16 to rotate downward to press the button on pull rod 35, so that the buckle inside pull rod 35 is unlocked, so that pull rod 35 can be continuously pushed and pulled, to ensure that the telescopic life test of pull rod can be smoothly carried out, the contact sensor 23 and servo motor 6 are electrically connected through the controller, the controller controls servo motor 6 to work after the instruction is sent through the sensing of contact sensor 23, which is prior art and has been widely used, so it is not described in detail here, bearing shaft 16 penetrates from the rear end of bearing frame 20, the rear end of bearing shaft 16 is embedded with separation frame 21, wheel body 22 is installed on the upper and lower ends of separation frame 21, the rear end of the protective positioning frame 7 on both sides is connected with separation rail 8, when bearing shaft 16 drives arc-shaped bending piece 17 to rotate downward, so that the buckle inside pull rod 35 is unlocked, bearing shaft 16 will continue to rotate, at this time, the arc segment of arc-shaped bending piece 17 will continue to press the button on pull rod 35, so that the buckle inside pull rod 35 remains unlocked, while the wheel body 22 on separation frame 21 will rotate under the drive of bearing shaft 16 to push the separation rail 8 on both sides to move in opposite directions, thereby driving the protective positioning frame 7 to move in opposite directions, so that the end of the protective positioning frame 7 is separated from control panel 12, test frame 1 is provided with fixed box piece.

[0019] The output end of the servo motor 6 is coaxially fixedly installed with a connecting shaft 14, the connecting shaft 14 plays a role of transmission, the end of the connecting shaft 14 is coaxially inlaid with a bevel gear 15 on the outer surface of the bearing shaft 16, the two bevel gears 15 are engaged, and the bevel gear 15 plays a role of connecting the connecting shaft 14 and the bearing shaft 16 together.

[0020] The rear end of the servo motor 6 is fixedly installed with a motor frame 32, the lower end of the motor frame 32 is fixed with the bearing seat 19, the motor frame 32 plays a role of fixing the servo motor 6, the outer surface of the connecting shaft 14 is rotatably installed with a shaft frame 33, the lower end of the shaft frame 33 is fixed with the bearing seat 19, and the shaft frame 33 plays a role of bearing the connecting shaft 14.

[0021] Two guide rods 28 are inlaid between the upper and lower end faces of the inside of the bearing frame 20, the control plate 12 is slidably installed on the outer surface of the guide rod 28, the guide rod 28 plays a role of guiding the control plate 12, the outer side of the guide rod 28 is respectively wound with two adaptive springs 29, the opposite surfaces of the two adaptive springs 29 are respectively fixed with the upper and lower end faces of the control plate 12, and the opposite surfaces of the two adaptive springs 29 are respectively fixed with the upper and lower end faces of the inside of the bearing frame 20, when the control plate 12 is pulled to the gear of the pull rod 35 and the buckle inside the pull rod 35 is locked, the control plate 12 is just on the protective positioning frame 7, at this time, the control plate 12 is limited by the protective positioning frame 7 and will remain stationary, so that it will not continue to push and pull the pull rod 35, and the bearing frame 20 still keeps moving, and the adaptive spring 29 is deformed, so that the movement of the bearing frame 20 is not blocked.

[0022] The outer surface of the protective positioning frame 7 is slidably installed with a frame sleeve 9, the frame sleeve 9 is inlaid in the front end of the stand 11, the frame sleeve 9 plays a role of guiding the protective positioning frame 7, the inside of the frame sleeve 9 is fixedly installed with a reset spring 31, the end of the reset spring 31 is fixed with the protective positioning frame 7, the reset spring 31 plays a role of resetting the moved protective positioning frame 7, and the opposite surfaces of the two sides of the separation rail 8 are respectively extended with a connecting frame 27, the end of the connecting frame 27 is fixed with the protective positioning frame 7, and the connecting frame 27 plays a role of fixing the separation rail 8 and the protective positioning frame 7 together.

[0023] The clamping rod piece includes an upper clamping frame 13 fixedly installed in the front end of the bearing seat 19, a threaded column 25 is rotatably installed at the lower end of the bearing seat 19, a lower clamping plate 18 is screwed on the outer side of the threaded column 25, the threaded column 25 plays a role of moving the lower clamping plate 18, a guide column 24 is extended at the side of the lower end of the bearing seat 19 close to the threaded column 25, the lower clamping plate 18 is slidably installed on the outer surface of the guide column 24, the guide column 24 plays a role of guiding the lower clamping plate 18, and the threaded column 25 is rotated to drive the lower clamping plate 18 to move upwards, so that the end of the pull rod 35 of the luggage 34 is clamped between the upper clamping frame 13 and the lower clamping plate 18.

[0024] The fixed box part includes a rear bent frame 2 fixedly installed at the middle of two sides of the test frame 1, an L-shaped clamping groove 26 is formed at the upper end front edge of the rear bent frame 2, a front bent frame 3 is arranged at the front of the rear bent frame 2, the rear end of the front bent frame 3 is inserted into the L-shaped clamping groove 26, two pressing frames 5 are symmetrically extended at the upper end front part of the test frame 1, the luggage box 34 is placed on the test frame 1, at this time, the test frame 1 is attached to the bottom and the rear end of the luggage box 34, the pressing frame 5 is attached to the upper end of the luggage box 34, the rear bent frame 2 is attached to the two sides of the luggage box 34, then the front bent frame 3 is inserted into the L-shaped clamping groove 26 on the rear bent frame 2, so that the front bent frame 3 is attached to the front end of the luggage box 34, thereby fixing the luggage box 34.

[0025] The two ends of the control plate 12 are provided with two No. 2 inclined guide surfaces 30, the two No. 2 inclined guide surfaces 30 at the two ends of the control plate 12 are oppositely arranged, the opposite surfaces of the two protective positioning frames 7 are provided with No. 1 inclined guide surfaces 10, the No. 1 inclined guide surfaces 10 on the two protective positioning frames 7 are oppositely arranged, when the control plate 12 moves upward, the No. 2 inclined guide surface 30 at one end of the control plate 12 will abut against the No. 1 inclined guide surface 10 on one side of the protective positioning frame 7, at this time, under the action of the inclined guide surface, the upward moving control plate 12 will push one side of the protective positioning frame 7 to move sideways, so that it smoothly passes through one side of the protective positioning frame 7, when passing through one side of the protective positioning frame 7, the other end of the control plate 12 is just on the other side of the protective positioning frame 7, at this time, the pull rod 35 is just located at the gear position and is locked, conversely, when the control plate 12 moves downward, the No. 2 inclined guide surface 30 at the other end of the control plate 12 will push the other side of the protective positioning frame 7 to move sideways, so that the control plate 12 smoothly passes through the other side of the protective positioning frame 7, after passing through, one end of the control plate 12 is just on one side of the protective positioning frame 7, at this time, the pull rod 35 is just located at the gear position and is locked.

[0026] When testing, the luggage 34 is placed on the test frame 1, at this time the test frame 1 is attached to the bottom and rear end of the luggage 34, the pressing frame 5 is attached to the upper end of the luggage 34, the rear bending frame 2 is attached to the two sides of the luggage 34, then the front bending frame 3 is inserted into the L-shaped clamping groove 26 on the rear bending frame 2, so that the front bending frame 3 is attached to the front end of the luggage 34, so as to fix the luggage 34, then the threaded column 25 is rotated to drive the lower clamping plate 18 to move upwards to clamp the end of the drawbar 35 of the luggage 34 between the upper clamping frame 13 and the lower clamping plate 18, then the servo reciprocating push cylinder 4 drives the carrying frame 20 to continuously move up and down to continuously push and pull the drawbar 35 of the luggage 34, in the process, when reaching the gear position of the drawbar 35, the buckle inside the drawbar 35 is locked, the control plate 12 just abuts on the protective positioning frame 7 at this time, the control plate 12 is limited by the protective positioning frame 7 and will remain stationary, so it will not continue to push and pull the drawbar 35, while the carrying frame 20 still keeps moving state, at the same time, the spring 29 deforms, so that the movement of the carrying frame 20 is not hindered, when the control plate 12 abuts on the protective positioning frame 7, the contact sensor 23 senses the protective positioning frame 7 and drives the servo motor 6 to work to drive the arc-shaped bending piece 17 on the carrying shaft 16 to rotate downward to press the button on the drawbar 35, so that the buckle inside the drawbar 35 is unlocked, after unlocking, the carrying shaft 16 continues to rotate, at this time, the arc segment of the arc-shaped bending piece 17 continues to press the button on the drawbar 35, so that the buckle inside the drawbar 35 remains in an unlocked state, at the same time, the wheel body 22 on the separation frame 21 rotates under the drive of the carrying shaft 16 to push the two separation rails 8 to move in opposite directions, thereby driving the protective positioning frame 7 to move in the opposite direction, so that the end of the protective positioning frame 7 is separated from the control plate 12, at this time, the control plate 12 loses the limitation of the protective positioning frame 7, at the same time, the spring 29 restores the deformation to push the control plate 12 to reset to the middle part of the carrying frame 20, while the control plate 12 synchronously pushes and pulls the drawbar 35 during the resetting process, so that the drawbar 35 is away from the gear position, then the servo motor 6 drives the carrying shaft 16 to reverse to reset to release the pressing of the button, then the carrying frame 20 continues to push and pull the drawbar 35, so as to cycle, so as to test the extension and contraction life of the drawbar 35.

[0027] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited to the above embodiments, the above embodiments and descriptions in the specification are only the principles of the present application, various changes and improvements can be made without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection required by the present application is defined by the appended claims and their equivalents.

Claims

1. A luggage case drawbar extension life test device, comprising a test stand (1), characterized in that: A servo reciprocating push cylinder (4) is fixedly installed on the inner side of the test frame (1), a supporting frame (20) is fixedly installed on the telescopic end of the servo reciprocating push cylinder (4), a control board (12) is elastically installed on the inner middle part of the supporting frame (20), a supporting seat (19) is fixedly installed on the front end of the control board (12), a clamping rod is provided on the supporting seat (19), a supporting shaft (16) is rotatably installed on the upper part of the supporting seat (19), an arc-shaped bent piece (17) is fixedly installed on the front end of the supporting shaft (16), a servo motor (6) is installed on the upper end of the supporting seat (19), and the servo motor (6) is connected to the supporting shaft (16). Two symmetrical fixed parts are installed on the rear end of the upper end of the test frame (1). A stand (11), a plurality of protective positioning frames (7) are elastically mounted on the two stands (11), the positions of the plurality of protective positioning frames (7) match the gear positions of the pull rod, a contact sensor (23) is installed through one side of the upper end and the other side of the lower end of the control panel (12), the contact sensor (23) is electrically connected to the servo motor (6) through a controller, the load-bearing shaft (16) extends from the rear end of the load-bearing frame (20), the rear end of the load-bearing shaft (16) is inlaid with a separation frame (21), the upper and lower ends of the separation frame (21) are both installed with wheels (22), the rear ends of the protective positioning frames (7) on both sides are connected to separation rails (8), and a fixed box member is provided on the test frame (1).

2. The luggage case drawbar extension life test device according to claim 1, characterized in that: The output end of the servo motor (6) is coaxially fixedly mounted with a connecting shaft (14), and the end of the connecting shaft (14) and the outer surface of the load-bearing shaft (16) are coaxially inlaid with bevel gears (15), and the two bevel gears (15) are meshed.

3. The luggage case drawbar extension life test device according to claim 2, characterized in that: A motor frame (32) is fixedly mounted on the rear end of the servo motor (6), the lower end of the motor frame (32) is fixed to the bearing seat (19), and a shaft frame (33) is rotatably mounted on the outer surface of the connecting shaft (14), the lower end of the shaft frame (33) is fixed to the bearing seat (19).

4. The luggage case drawbar extension life test device according to claim 1, characterized in that: Two guide rods (28) are embedded between the inner upper and lower end surfaces of the carrying frame (20), and the control board (12) is slidably mounted on the outer surface of the guide rods (28). Two adaptive springs (29) are respectively wound around the outer sides of the guide rods (28), and the opposite surfaces of the two adaptive springs (29) are respectively fixed to the upper and lower end surfaces of the control board (12), and the opposite surfaces of the two adaptive springs (29) are respectively fixed to the inner upper and lower end surfaces of the carrying frame (20).

5. The luggage case drawbar extension life test device according to claim 1, characterized in that: A frame sleeve (9) is slidably mounted on the outer surface of the protective positioning frame (7), and the frame sleeve (9) penetrates and is embedded in the front end of the vertical frame (11). A return spring (31) is fixedly mounted on the inner side of the frame sleeve (9), and the end of the return spring (31) is fixed to the protective positioning frame (7). Connecting frames (27) are extended from the middle of the opposite surfaces of the separation rails (8) on both sides, and the end of the connecting frame (27) is fixed to the protective positioning frame (7).

6. The luggage case drawbar extension life test device according to claim 1, characterized in that: The clamping rod comprises an upper clamping frame (13) fixedly mounted on the middle part of the front end of the bearing seat (19); a threaded column (25) is rotatably mounted on the lower end of the bearing seat (19); a lower clamping plate (18) is screwed onto the outer side of the threaded column (25); a guide column (24) extends from the lower end of the bearing seat (19) near the side of the threaded column (25); and the lower clamping plate (18) is slidably mounted on the outer surface of the guide column (24).

7. The luggage case drawbar extension life test device according to claim 1, characterized in that: The fixed box member comprises a rear bending frame (2) fixedly mounted on the middle of both sides of the test frame (1), an L-shaped slot (26) is provided at the front edge of the upper end of the rear bending frame (2), a front bending frame (3) is provided in front of the rear bending frame (2), the rear end of the front bending frame (3) is plugged into the L-shaped slot (26), and two pressing frames (5) are symmetrically extended from the front of the upper end of the test frame (1).

8. The luggage case drawbar extension life test device according to claim 1, characterized in that: Both ends of the control panel (12) are configured as second inclined guide surfaces (30), and the second inclined guide surfaces (30) at both ends of the control panel (12) are arranged oppositely. The opposite surfaces of the protective positioning frames (7) on both sides are configured as first inclined guide surfaces (10), and the first inclined guide surfaces (10) on the protective positioning frames (7) on both sides are arranged oppositely.

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