CN212246055U

CN212246055U - Lifting device for be used for auto repair inspection

Info

Publication number: CN212246055U
Application number: CN202020729094.7U
Authority: CN
Inventors: 徐丹
Original assignee: Changzhou Liu Guojun Vocational Technology College
Current assignee: Changzhou Liu Guojun Vocational Technology College
Priority date: 2020-05-06
Filing date: 2020-05-06
Publication date: 2020-12-29
Anticipated expiration: 2030-05-06

Abstract

The utility model aims to solve the technical problem that a lifting device for auto repair inspection that can realize removing repair service, height-adjustable, be convenient for fixed maintenance vehicle is provided. The device includes first slope frame, second slope frame, base, first backup pad, second backup pad, first slope frame, second slope frame set up both ends around the base respectively, first backup pad, second backup pad are all fixed in the base top through height-adjustable device. The device is when using, promotes the base and removes to suitable position, removes maintenance vehicle to first backup pad and second backup pad upper surface, again with first tire stop device, second tire stop device with it fixed can, then rise certain height through height-adjustable device with first backup pad and second backup pad simultaneously, it can to be fit for the maintenance of maintenance personal. The operation is simple, and the method is suitable for popularization in the field of automobile repair.

Description

Lifting device for be used for auto repair inspection

Technical Field

The utility model relates to a vapour field of repairment, concretely relates to a elevating gear for auto repair inspection.

Background

The automobile maintenance is to find out the failure reason by means of technical means for the automobile with failure, and take certain measures to remove the failure and recover the failure to reach certain performance and safety standard. The existing automobile maintenance mode is that a ground groove is arranged on the ground, and a maintenance worker repairs an automobile in the ground groove, so that the maintenance operation is inconvenient and the height cannot be adjusted; the other mode is that a maintenance frame is adopted, an automobile is lifted up through the maintenance frame, maintenance personnel maintain the automobile at the bottom of the automobile, the existing mode can be realized only by stopping a maintenance vehicle at a fixed position, and the mobile service of a maintenance point cannot be realized.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a lifting device for auto repair inspection that can realize removing repair service, height-adjustable, be convenient for fixed maintenance vehicle is provided.

The utility model provides a technical scheme that its technical problem adopted does: the lifting device for automobile maintenance and inspection comprises a first slope frame, a second slope frame, a base, a first supporting plate and a second supporting plate, wherein the first slope frame and the second slope frame are respectively arranged at the front end and the rear end of the base, the first supporting plate and the second supporting plate are fixed above the base through height-adjustable devices, the length direction of the first supporting plate, the length direction of the second supporting plate and the length direction of the base are mutually parallel, the first supporting plate and the second supporting plate are symmetrically arranged relative to the center of the base, the front end of the first supporting plate is connected with the front end of the second supporting plate through a first connecting rod, the rear end of the first supporting plate is connected with the rear end of the second supporting plate through a second connecting rod, a first limiting groove is arranged on the upper surface of the first supporting plate, and the length of the first limiting groove is equal to the length of the first supporting plate, the tire positioning device comprises a first sliding block and a first limiting plate, wherein the first sliding block is arranged on the upper surface of the first sliding block, the first limiting plate is parallel to the width direction of a first supporting plate, and two ends of the first limiting plate respectively have gaps with the side walls of the two sides of the first limiting groove; the end faces of the left side and the right side of the first sliding block are respectively provided with a first bulge, the first bulges are matched with the first grooves, when the first sliding block is positioned in the first sliding grooves, the first bulges are positioned in the corresponding first grooves, the upper surface of the first sliding block is provided with a first tightening screw rod, a gap exists between the first tightening screw rod and the first limiting plate, the upper surface of the second supporting plate is provided with a second limiting groove, the length of the second limiting groove is equal to that of the second supporting plate, the distance between the first limiting groove and the second limiting groove is matched with the distance between tires at two sides of a maintenance vehicle, the groove bottom of the second limiting groove is provided with a second sliding groove, the length of the second sliding groove is equal to that of the first limiting groove, and the front end and the rear end of the second sliding groove are respectively provided with a second tire limiting device with the same structure, the second tire limiting device comprises a second sliding block and a second limiting plate, wherein second grooves are formed in the side walls of the two sides of the second sliding groove, the length of each second groove is equal to that of the second sliding groove, the shape of each second limiting plate is the same as that of the first limiting plate, the second limiting plates are fixed on the upper surface of the second sliding block and are parallel to the width direction of the second supporting plate, gaps are formed between the two ends of each second limiting plate and the side walls of the two sides of each second limiting groove, second protrusions are arranged on the end surfaces of the left side and the right side of each second sliding block and are matched with the second grooves, when the second sliding block is positioned in the second sliding groove, the second protrusions are positioned in the corresponding second grooves, second jacking screw rods are arranged on the upper surface of the second sliding block, gaps exist between the second jacking screw rods and the second limiting plates, and in an initial state, the bottom of the first chute, the bottom of the second chute, the highest point of the first slope frame and the highest point of the second slope frame are all located in the same horizontal plane, the distance between the front end surface of the first limiting plate, the distance between the front end surface of the second limiting plate and the first slope frame are all 1-2 cm, the distance between the rear end surface of the first limiting plate, the distance between the rear end surface of the second limiting plate and the second slope frame are all 1-2 cm, a plurality of fixing plates are arranged on the end surfaces of the left side and the right side of the base, each fixing plate is perpendicular to the end surface, a thread through hole is formed in the upper surface of each fixing plate, the central axis of each thread through hole is perpendicular to the upper surface of each fixing plate, a lead screw is arranged in each thread through hole, the upper end of the lead screw extends to the upper portion of each fixing plate, and a knob, the lower end of the screw rod penetrates through the threaded through hole to extend downwards, the lower end of the screw rod is provided with a universal wheel, the lower end of the screw rod is connected with the universal wheel through a bearing, and the distance between the lower surface of the fixing plate and the lower surface of the base is larger than the height of the universal wheel.

Further, the height-adjustable device comprises a controller, an operating handle and four electric scissor type lifting frames with the same structure, driving switches of the four electric scissor type lifting frames are respectively connected with the controller, the operating handle is connected with the controller through a signal line, and the controller and the four electric scissor type lifting frames are respectively connected with an external power supply.

Furthermore, the first slope frame, the second slope frame and the base are all made of hollow shells.

Furthermore, the number of the fixing plates is two and the fixing plates are respectively positioned at two ends of the end face where the fixing plates are positioned.

Furthermore, the cross section of the first limiting groove and the cross section of the second limiting groove are both isosceles trapezoids.

The utility model has the advantages that: when the lifting device for automobile maintenance and inspection is used, the screw rod is driven to rotate by rotating the knob to enable the universal wheel to descend to be in contact with the ground, meanwhile, the lower surface of the base is kept away from the ground for a certain distance, then the base can be pushed to move to a proper position, then the screw rod is driven to rotate by rotating the knob to enable the universal wheel to move upwards until the lower surface of the base is in contact with the ground, then the first tire limiting device at the front end of the first supporting plate is taken down through the first sliding groove, the second tire limiting device at the front end of the second supporting plate is taken down through the second sliding groove, then a maintenance vehicle is moved to the upper surfaces of the first supporting plate and the second supporting plate through the first slope frame arranged at the front end of the base, furthermore, the upper surface of the first supporting plate is provided with a first limiting groove, the upper surface of the second supporting plate is provided with a second limiting groove, thus, the risk that the maintenance vehicle slides out from the left side and the right side is avoided through the first limiting groove and the second limiting groove, the front wheels at the two sides of the maintenance vehicle are respectively moved to be contacted with the first tire limiting device at the rear end of the first supporting plate and the second tire limiting device at the rear end of the second supporting plate, the first tire limiting device at the front end of the first supporting plate is moved to be contacted with the rear wheel at one side of the maintenance vehicle through the first sliding groove and is fixed, the second tire limiting device at the front end of the second supporting plate is moved to be contacted with the rear wheel at the other side of the maintenance vehicle through the second sliding groove and is fixed, then the first supporting plate and the second supporting plate are simultaneously lifted to a certain height through the height adjusting device, the maintenance is suitable for maintenance personnel, after the maintenance work is finished, the first supporting plate and the second supporting plate are lowered to the initial state through the height adjusting device, the first tire limiting device at the rear end of the first supporting plate is released and taken down through the first sliding groove, the second tire limiting device at the rear end of the second supporting plate is released and taken down through the second sliding groove, and then the vehicle after maintenance is moved to the ground through the second slope frame arranged at the rear end of the base.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a lifting device for automobile maintenance and inspection according to the present invention;

fig. 2 is a partial structural schematic view of a lifting device for automobile maintenance and inspection according to the present invention;

fig. 3 is a schematic view of a combined structure of the first supporting plate and the first limiting device according to the present invention;

fig. 4 is a schematic view of a combined structure of the second supporting plate and the second limiting device according to the present invention;

fig. 5 is a front view of the first support plate according to the present invention;

fig. 6 is a front view of a second support plate according to the present invention;

the notation in the figure is: first slope frame 1, second slope frame 2, base 3, first backup pad 4, second backup pad 5, head rod connects 6, second connecting rod connects 7, first spacing recess 8, second spacing recess 9, first spout 10, second spout 11, fixed plate 12, lead screw 13, knob 14, universal wheel 15, first slider 16, first limiting plate 17, first recess 18, first tight screw 19 in top, second slider 20, second limiting plate 21, second recess 22, second tight screw 23 in top, controller 24, operating handle 25, electronic scissors formula crane 26, first arch 27, second arch 28.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

As shown in fig. 1-6, the lifting device for automobile maintenance and inspection comprises a first slope frame 1, a second slope frame 2, a base 3, a first supporting plate 4 and a second supporting plate 5, wherein the first slope frame 1 and the second slope frame 2 are respectively arranged at the front end and the rear end of the base 3, the first supporting plate 4 and the second supporting plate 5 are both fixed above the base 3 through a height adjusting device, the length direction of the first supporting plate 4, the length direction of the second supporting plate 5 and the length direction of the base 3 are parallel to each other, the first supporting plate 4 and the second supporting plate 5 are symmetrically arranged about the center of the base 3, the front end of the first supporting plate 4 is connected with the front end of the second supporting plate 5 through a first connecting rod 6, the rear end of the first supporting plate 4 is connected with the rear end of the second supporting plate 5 through a second connecting rod 7, the upper surface of the first supporting plate 4 is provided with a first limiting groove 8, the length of the first limit groove 8 is equal to that of the first support plate 4, a first sliding groove 10 is arranged at the bottom of the first limit groove 8, the length of the first sliding groove 10 is equal to that of the first limiting groove 8, the front end and the rear end of the first sliding groove 10 are respectively provided with a first tire limiting device with the same structure, the first tire limiting device is preferably of a structure comprising a first sliding block 16 and a first limiting plate 17, the side walls of the two sides of the first sliding chute 10 are both provided with a first groove 18, the length of the first groove 18 is equal to the length of the first sliding chute 10, the first limit plate 17 is triangular prism-shaped, the first limit plate 17 is fixed on the upper surface of the first slide block 16 and is parallel to the width direction of the first support plate 4, gaps exist between two ends of the first limiting plate 17 and the side walls of two sides of the first limiting groove 8 respectively; all be provided with first arch 27 on the terminal surface of the left and right sides of first slider 16, first arch 27 and first recess 18 phase-match, when first slider 16 was located first spout 10, first arch 27 was located the first recess 18 that corresponds, first slider 16 upper surface is provided with first tight screw rod 19 in top, there is the clearance between first tight screw rod 19 in top and the first limiting plate 17. The position of the first limiting plate 17 can be movably adjusted through the first sliding block 16 and the first sliding groove 10, the first sliding block 16 can be fixed through the first tightly-pushing screw rod 19, further, the height of the first limiting plate 17 is determined according to actual conditions, the upper surface of the second supporting plate 5 is provided with a second limiting groove 9, the length of the second limiting groove 9 is equal to that of the second supporting plate 5, the distance between the first limiting groove 8 and the second limiting groove is matched with that between tires on two sides of a maintenance vehicle, the groove bottom of the second limiting groove 9 is provided with a second sliding groove 11, the length of the second sliding groove 11 is equal to that of the first limiting groove 8, the front end and the rear end of the second sliding groove 11 are provided with second tire limiting devices with the same structure, the second tire limiting devices are preferably of the following structure, and comprise second sliding blocks 20, A second limiting plate 21, wherein the side walls of the two sides of the second chute 11 are both provided with a second groove 22, the length of the second groove 22 is equal to the length of the second sliding chute 11, the shape of the second limit plate 21 is the same as the shape of the first limit plate 17, the second limiting plate 21 is fixed on the upper surface of the second slider 20 and is parallel to the width direction of the second supporting plate 5, gaps are respectively reserved between the two ends of the second limiting plate 21 and the side walls of the two sides of the second limiting groove 9, the end surfaces of the left side and the right side of the second sliding block 20 are respectively provided with a second bulge 28, the second bulges 28 are matched with the second grooves 22, when the second slider 20 is positioned in the second runner 11, said second projection 28 is positioned in the corresponding second recess 22, the upper surface of the second slider 20 is provided with a second jacking screw 23, and a gap exists between the second jacking screw 23 and the second limiting plate 21. The position of the second limiting plate 21 can be movably adjusted through the second slider 20 and the second sliding chute 11, the first slider 16 can be fixed through the second tightening screw 23, further, the height of the second limiting plate 21 is determined according to the actual situation, in the initial state, the groove bottom of the first sliding chute 10, the groove bottom of the second sliding chute 11, the highest point of the first slope frame 1 and the highest point of the second slope frame 2 are all located in the same horizontal plane, the distance between the front end surface of the first limiting plate 17, the distance between the front end surface of the second limiting plate 21 and the first slope frame 1 are all 1-2 cm, the distance between the rear end surface of the first limiting plate 17, the distance between the rear end surface of the second limiting plate 21 and the second slope frame 2 are all 1-2 cm, the left and right end surfaces of the base 3 are provided with a plurality of fixing plates 12, each fixing plate 12 is perpendicular to the end surface where the fixing plates are located, the upper surface of every fixed plate 12 all is provided with the screw through-hole, the central axis of screw through-hole and the upper surface mutually perpendicular of fixed plate 12, be provided with lead screw 13 in the screw through-hole, lead screw 13 and screw through-hole phase-match, the upper end of lead screw 13 extends to fixed plate 12 top, the fixed knob 14 that is used for rotating lead screw 13 that is provided with in upper end of lead screw 13, the lower extreme of lead screw 13 passes screw through-hole downwardly extending, the lower extreme of lead screw 13 is provided with universal wheel 15, the lower extreme of lead screw 13 passes through the bearing with universal wheel 15 and is connected, the distance between the lower surface of fixed plate 12 and the lower surface of base 3 is greater than the height of universal. When the lifting device for automobile maintenance and inspection is used, firstly, the rotary knob 14 is rotated to drive the screw rod 13 to rotate so as to enable the universal wheel 15 to descend to be contacted with the ground, meanwhile, the lower surface of the base 3 is kept away from the ground for a certain distance, then the base 3 can be pushed to move to a proper position, then the rotary knob 14 is rotated to drive the screw rod 13 to rotate so as to enable the universal wheel 15 to move upwards until the lower surface of the base 3 is contacted with the ground, then the first tire limiting device at the front end of the first supporting plate 4 is taken down through the first sliding groove 10, the second tire limiting device at the front end of the second supporting plate 5 is taken down through the second sliding groove 11, then a maintenance vehicle is moved to the upper surfaces of the first supporting plate 4 and the second supporting plate 5 through the first slope frame 1 arranged at the front end of the base 3, further, the upper surface of the first supporting plate 4 is provided with the first limiting groove, the upper surface of the second supporting plate 5 is provided with a second limiting groove 9, so that the risk that the maintenance vehicle slides out from the left side and the right side can be avoided through the first limiting groove 8 and the second limiting groove 9, the front wheels at the two sides of the maintenance vehicle are respectively moved to be contacted with the first tire limiting device at the rear end of the first supporting plate 4 and the second tire limiting device at the rear end of the second supporting plate 5, then the first tire limiting device at the front end of the first supporting plate 4 is moved to be contacted with the rear wheel at one side of the maintenance vehicle through the first chute 10 and fixed, meanwhile, the second tire limiting device at the front end of the second supporting plate 5 is moved to be contacted with the rear wheel at the other side of the maintenance vehicle through the second chute 11 and fixed, then the first supporting plate 4 and the second supporting plate 5 are simultaneously lifted to a certain height through the height adjusting device, and the maintenance vehicle is suitable for maintenance personnel, after the maintenance work is finished, the first supporting plate 4 and the second supporting plate 5 are descended to the initial state through the height adjustable device, the first tire limiting device at the rear end of the first supporting plate 4 is removed and taken down through the first sliding groove 10, the second tire limiting device at the rear end of the second supporting plate 5 is removed and taken down through the second sliding groove 11, and then the vehicle after maintenance is moved to the ground through the second slope frame 2 arranged at the rear end of the base 3.

Preferably, the height adjustable device comprises a controller 24, an operating handle 25 and four electric scissor type lifting frames 26 with the same structure, driving switches of the four electric scissor type lifting frames 26 are respectively connected with the controller 24, the operating handle 25 is connected with the controller 24 through a signal line, and the controller 24 and the four electric scissor type lifting frames 26 are respectively connected with an external power supply. The electric scissors type lifting frame 26 is in the prior art, and can also adopt an electric telescopic rod to achieve the same purpose, the lifting of the four electric scissors type lifting frames 26 can be simultaneously controlled through the operating handle 25 and the controller 24, and further, the controller 24 adopts an AT89S51 singlechip or other realizable controllers 24.

In order to move the lifting device for automobile maintenance and inspection conveniently, the first slope frame 1, the second slope frame 2 and the base 3 are all made of hollow shells, so that the overall weight can be reduced, and the lifting device is convenient to move.

According to actual requirements, the number of the fixing plates 12 is two and the fixing plates are respectively located at two ends of the end face where the fixing plates are located.

Furthermore, in the process that the maintenance vehicle moves to the first supporting plate 4 and the second supporting rod, the friction between the tire and the side wall of the first limiting groove 8 or the side wall of the second limiting groove 9 may occur, and for this reason, the cross section of the first limiting groove 8 and the cross section of the second limiting groove 9 are both isosceles trapezoids. Therefore, a slope is buffered to avoid damaging the tire, and further, the depth of the first limiting groove 8 and the depth of the second limiting groove 9 are determined according to actual conditions.

Claims

1. The utility model provides a elevating gear for be used for auto repair inspection which characterized in that: comprises a first slope frame (1), a second slope frame (2), a base (3), a first supporting plate (4) and a second supporting plate (5), wherein the first slope frame (1) and the second slope frame (2) are respectively arranged at the front end and the rear end of the base (3), the first supporting plate (4) and the second supporting plate (5) are fixed above the base (3) through a height adjusting device, the length direction of the first supporting plate (4), the length direction of the second supporting plate (5) and the length direction of the base (3) are mutually parallel, the first supporting plate (4) and the second supporting plate (5) are symmetrically arranged relative to the center of the base (3), the front end of the first supporting plate (4) and the front end of the second supporting plate (5) are connected through a first connecting rod (6), the rear end of the first supporting plate (4) and the rear end of the second supporting plate (5) are connected through a second connecting rod (7), the upper surface of the first supporting plate (4) is provided with a first limiting groove (8), the length of the first limiting groove (8) is equal to the length of the first supporting plate (4), the bottom of the first limiting groove (8) is provided with a first sliding chute (10), the length of the first sliding chute (10) is equal to the length of the first limiting groove (8), the front end and the rear end of the first sliding chute (10) are respectively provided with a first tire limiting device with the same structure, each first tire limiting device comprises a first sliding block (16) and a first limiting plate (17), the side walls of the two sides of the first sliding chute (10) are respectively provided with a first groove (18), the length of the first groove (18) is equal to the length of the first sliding chute (10), the first limiting plate (17) is triangular prism-shaped, the first limiting plate (17) is fixed on the upper surface of the first sliding block (16) and is parallel to the width direction of the first supporting plate (4), gaps are reserved between the two ends of the first limiting plate (17) and the side walls of the two sides of the first limiting groove (8) respectively; all be provided with first arch (27) on the terminal surface of the left and right sides of first slider (16), first arch (27) and first recess (18) phase-match, when first slider (16) is located first spout (10), first arch (27) are located corresponding first recess (18), first slider (16) upper surface is provided with first top tight screw rod (19), there is the clearance between first top tight screw rod (19) and first limiting plate (17), the upper surface of second backup pad (5) is provided with second spacing recess (9), the length of second spacing recess (9) equals the length of second backup pad (5), the distance between first spacing recess (8) and the second spacing recess matches with the distance between the both sides tire of maintenance vehicle, the tank bottom of second spacing recess (9) is provided with second spout (11), the length of the second sliding chute (11) is equal to that of the first limiting groove (8), the front end and the rear end of the second sliding chute (11) are respectively provided with a second tire limiting device with the same structure, each second tire limiting device comprises a second sliding block (20) and a second limiting plate (21), the side walls of the two sides of the second sliding chute (11) are respectively provided with a second groove (22), the length of the second groove (22) is equal to that of the second sliding chute (11), the shape of the second limiting plate (21) is the same as that of the first limiting plate (17), the second limiting plate (21) is fixed on the upper surface of the second sliding block (20) and is parallel to the width direction of the second supporting plate (5), the two ends of the second limiting plate (21) respectively have gaps with the side walls of the two sides of the second limiting groove (9), and the end faces of the left side and the right side of the second sliding block (20) are respectively provided with a second protrusion (28), the second protrusion (28) is matched with the second groove (22), when the second slider (20) is positioned in the second sliding groove (11), the second protrusion (28) is positioned in the corresponding second groove (22), the upper surface of the second slider (20) is provided with a second tightening screw rod (23), a gap exists between the second tightening screw rod (23) and the second limiting plate (21), in an initial state, the groove bottom of the first sliding groove (10), the groove bottom of the second sliding groove (11), the highest point of the first slope frame (1) and the highest point of the second slope frame (2) are all positioned in the same horizontal plane, the distance between the front end surface of the first limiting plate (17), the front end surface of the second limiting plate (21) and the first slope frame (1) is 1-2 cm, the distance between the rear end surface of the first limiting plate (17), the rear end surface of the second limiting plate (21) and the second slope frame (2) is 1-2 cm, the left and right side end surfaces of the base (3) are respectively provided with a plurality of fixing plates (12), each fixing plate (12) is vertical to the end surface, the upper surface of each fixing plate (12) is provided with a threaded through hole, the central axis of the threaded through hole is vertical to the upper surface of the fixing plate (12), a screw rod (13) is arranged in the threaded through hole, the upper end of the screw rod (13) extends to the upper part of the fixing plate (12), a knob (14) for rotating the screw rod (13) is fixedly arranged at the upper end of the screw rod (13), the lower end of the screw rod (13) passes through the threaded through hole and extends downwards, the lower end of the screw rod (13) is provided with a universal wheel (15), the lower end of the screw rod (13) is connected with a universal wheel (15) through a bearing, and the distance between the lower surface of the fixing plate (12) and the lower surface of the base (3) is greater than the height of the universal wheel (15).

2. The lifting device for vehicle maintenance inspection according to claim 1, wherein: the height-adjustable device comprises a controller (24), an operating handle (25) and four electric scissor type lifting frames (26) with the same structure, wherein driving switches of the four electric scissor type lifting frames (26) are respectively connected with the controller (24), the operating handle (25) is connected with the controller (24) through a signal line, and the controller (24) and the four electric scissor type lifting frames (26) are respectively connected with an external power supply.

3. The lifting device for vehicle maintenance inspection according to claim 2, wherein: the first slope frame (1), the second slope frame (2) and the base (3) are all made of hollow shells.

4. A lifting device for vehicle maintenance inspection according to claim 3, characterized in that: the number of the fixing plates (12) is two and the fixing plates are respectively positioned at two ends of the end face where the fixing plates are positioned.

5. The lifting device for automobile maintenance inspection according to claim 4, characterized in that: the cross section of the first limiting groove (8) and the cross section of the second limiting groove (9) are both isosceles trapezoids.