Large-span guiding and supporting device for cold roll forming line

Abstract

The utility model provides a large span guide device for a cold roll forming line, which comprises a guide frame arranged along the conveying direction of a cold roll section and mounting seats arranged at the two ends of the guide frame, the guide frame is of a cavity structure, the cavity of the guide frame is matched with the section of the cold roll section, and the mounting seats are arranged at the two ends of the guide frame. A plurality of sets of universal ball devices used for abutting against the side wall of the sectional material are symmetrically arranged on the side wall of the guiding and supporting frame. The mounting base comprises a transverse moving mechanism and a lifting mechanism which are used for adjusting the position of the guiding and supporting frame. The roller die is reasonable in structure and low in cost, deformation such as bending and twisting caused by self weight and lack of constraint after a profile is separated from the roller die can be avoided, the section of a profile product is ensured, the forming precision of the product is greatly improved, and the surface of the product is effectively prevented from being scratched.

Description

Technical Field

[0001] This utility model relates to the field of cold bending forming technology, and in particular to a large-span guide device for cold bending forming lines. Background Technology

[0002] Cold bending is a process that uses a series of sequentially arranged forming rolls to continuously bend metal sheets and strips laterally to create profiles with specific cross-sections. Cold-formed profiles are lightweight, thin-walled, and highly efficient profiles with a large moment of inertia, widely used in steel structures, automobiles, railway vehicles, and cable trays. In the automotive industry, cold-formed tubular beam profiles can be used as crash beams, battery side beams, sill beams, or other side beam profiles. In recent years, with the development of roll forming production towards higher added value and higher precision, and the technical requirements for high energy absorption and lightweight automotive parts, the formed cross-sections are becoming increasingly complex, and product types are gradually developing towards special, irregular, and lightweight directions. Consequently, the number of roll forming passes is gradually increasing, and the production line layout is becoming longer. Currently, factories typically have 44 roll forming stations on their roll forming lines to meet the forming requirements of most profiles.

[0003] For conventional high-strength steel pipe beam structures with simple cross-sections, the forming process is relatively simple, requiring fewer forming passes. Taking a simple rectangular cross-section steel pipe beam as an example, it requires a maximum of only 24 rolling passes to meet the forming requirements, including laser welding or high-frequency welding processes. Since cold-formed profiles ultimately require roll forming, and the roll forming mechanism is located downstream of the rolling production line, for conventional high-strength steel pipe beam structures, after the product is formed and welded, it still needs to pass through several empty passes before entering the roll forming mechanism (see...). Figure 1 During the idle conveying process of multiple passes, the three-dimensional spatial state of the profile product needs to be constrained to ensure the subsequent arc forming quality. Therefore, it is necessary to set up a guide device to constrain the profile and prevent it from bending or twisting due to its own weight after it is freed from the roller constraint.

[0004] Traditional guide devices are conventional roll forming assemblies, which ensure the profile structure through the setting of the rolls. However, roll forming assemblies are expensive, with the cost of a single set of roller supports typically ranging from 20,000 to 30,000 yuan. Therefore, in order to control costs, the number of sets is often reduced, with a set of roller supports installed every one or two sets to support the profile, but it is necessary to ensure that a set is installed at the closest position in front of the roll arc.

[0005] Conventional roll forming units are generally divided into horizontal rolls (see...) Figure 2 ) and vertical rollers (see Figure 3There are two types of guide rollers. Horizontal rollers, due to their operating characteristics, are prone to causing regular arc-shaped scratches on the outer surface of the product. When scratches occur, further processing is required, such as PVD or TD treatment of the upper and lower rollers, significantly increasing manufacturing costs. Vertical rollers, on the other hand, rotate horizontally. While this improves scratch prevention, differences in control precision and force can lead to straight scratches along the longitudinal direction. Furthermore, using vertical rollers for material support requires additional design and installation fixtures. Therefore, it is clear that neither horizontal nor vertical rollers can completely prevent scratches on the profiles, and both installation and operating costs are high. Thus, how to solve the problem of surface scratches on cold-formed profiles while effectively constraining them has become a pressing issue for current guide roller systems. Utility Model Content

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a large-span guide device for cold bending forming lines.

[0007] The technical solution adopted by this utility model to solve its technical problem is:

[0008] A large-span guide device for a cold-bending forming line includes a guide frame arranged along the conveying direction of the cold-bending profile and mounting seats arranged at both ends of the guide frame. The guide frame has a hollow structure, and its cavity is adapted to the cross-section of the cold-bending profile. Several sets of universal ball bearings for abutting against the side wall of the profile are symmetrically arranged on the side wall of the guide frame. The mounting seats include a lateral movement mechanism and a lifting mechanism for adjusting the position of the guide frame.

[0009] A further improvement of this utility model is that: the guide frame includes a left U-shaped groove and a right U-shaped groove arranged opposite to each other, and the left U-shaped groove and the right U-shaped groove are fastened together to form a cavity for cold-bent profiles to pass through; a plurality of mounting holes for fixing universal ball bearings are provided on the side walls of the left U-shaped groove and the right U-shaped groove along the length direction; ear plate assemblies for fixed connection with the lifting mechanism are respectively provided at both ends of the guide frame, and the ear plate assemblies are symmetrically arranged on the left and right sides of the guide frame.

[0010] A further improvement of this utility model is that: the transverse movement mechanism includes a mounting base plate, a slide seat fixed on the mounting base plate, and a left slider and a right slider disposed in the slide seat and slidingly engaged with the slide seat; the left slider is drivenly connected to a first lead screw, and the right slider is drivenly connected to a second lead screw; an operating end for worker operation is provided at one end of the first lead screw and the second lead screw; and screw holes for connecting the lifting mechanism are provided at the top of the left slider and the right slider.

[0011] A further improvement of this utility model is that: the left slider is provided with a threaded hole for driving and connecting the first lead screw, and a through hole for the second lead screw to pass through; the right slider is provided with a threaded hole for driving and connecting the second lead screw, and a through hole for the first lead screw to pass through; a lifting mechanism is connected to the top of both the left and right sliders.

[0012] A further improvement of this utility model is that: the mounting base plate has a guide groove along its length, and the slide seat is fixedly installed in the guide groove; the slide seat is also provided with a guide rail pressure plate to prevent the left and right slide blocks from derailing.

[0013] A further improvement of this utility model is that: the lifting mechanism includes a lifting base spanning the slide seat, and two height adjustment shafts disposed at both ends of the lifting base, the relative positions of the two height adjustment shafts being consistent with the relevant positions of the ear plate assembly; the height adjustment shafts are provided with external threads, and locking nuts and several bushings of unequal thickness are fitted on the height adjustment shafts; the lifting base is threadedly connected to the left slider / right slider.

[0014] A further improvement of this utility model is that the bottom of the lifting base is provided with a guide groove that matches the outer diameter of the left slider / right slider.

[0015] The beneficial effects obtained by this utility model through the above technical solution are:

[0016] This invention provides a large-span guide device for cold bending forming lines, enabling products to be output under constraint with fewer forming passes. This ensures the cross-section of the profile products and prevents bending and twisting deformations caused by the profile's own weight and lack of constraint after it leaves the rolling mill. Especially for multi-process rolled products, the guide and clamping action resists the reverse force from the rolled surface, greatly improving product forming accuracy and effectively preventing surface scratches. This invention has a reasonable structure, low processing and operating costs, and replaces the original investment in vacant guide wheels, support wheels, and roller supports, significantly reducing production costs.

[0017] This invention solves many negative effects of manual material guiding and straightening, such as safety hazards due to unstable binding structures, damage to spot welding equipment, inconvenience in debugging and disassembly, and poor product precision and surface scratches in simple material support devices. This invention is highly adaptable and practical, allowing for rapid adjustment of the product's center position based on parameters such as cross-sectional size and discharge height, through a lateral movement mechanism and a lifting mechanism. It is convenient to debug and offers high adjustment precision.

[0018] This utility model is flexible in application. The length of the guide frame can be adjusted according to the specific forming process of the product. Moreover, its installation position is flexible and unrestricted. It can be installed on the roller bending table or on composite process equipment (such as roller spot welding machine or laser welding machine).

[0019] This invention uses several universal ball bearings to constrain the product surface, converting large sliding friction into very small rolling friction. The small contact area and low friction not only help reduce upstream forming resistance and ensure that the product can be smoothly output from the guide frame under no-power conditions, but also effectively avoid the defects of scratches on the product surface. Attached Figure Description

[0020] Figure 1 This is a schematic diagram showing the location of the support material for the cold-formed profile;

[0021] Figure 2 This is a schematic diagram of the existing horizontal roller support material handling system.

[0022] Figure 3 This is a schematic diagram of the existing vertical roller material support method;

[0023] Figure 4 This is a schematic diagram of the structure of this utility model;

[0024] Figure 5 This is a partial structural schematic diagram of the U-shaped groove of this utility model;

[0025] Figure 6 This is a schematic diagram of the cooperation structure between the guide frame and the cold-formed profile of this utility model;

[0026] Figure 7 This is a schematic diagram of the transverse movement mechanism of this utility model;

[0027] Figure 8 This is a schematic diagram of the lifting mechanism of this utility model;

[0028] In the diagram, 1. Guide frame, 1-1. U-shaped groove, 1-2. Universal ball bearing, 1-3. Ear plate assembly, 1-4. Mounting hole, 2. Mounting seat, 2-1-1. Mounting base plate, 2-1-2. Slide seat, 2-1-3. Left slider, 2-1-4. Right slider, 2-1-5. Limiting plate, 2-1-6. Lead screw fixing block, 2-1-7. First lead screw, 2-1-8. Second lead screw, 2-1-9. Operating end, 2-1-10. Guide rail pressure plate, 2-1-11. Oblong hole, 2-2-1. Lifting base, 2-2-2. Height adjustment shaft, 2-2-3. Bushing, 2-2-4. Locking nut, 2-2-5. Guide groove, 3. Cold-bent profile. Detailed Implementation

[0029] The technical solution of this utility model will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0030] A large-span guide device for cold bending forming lines, such as Figure 4 As shown, it includes a guide frame 1 and mounting seats 2 disposed at both ends of the guide frame 1; the mounting seats 2 are used to support the guide frame 1 and to adjust the position and height of the guide frame 1 to adapt to the output position of the cold-formed profile 3.

[0031] The guide frame 1 is a long, rectangular cavity structure arranged along the conveying direction of the cold-formed profile 3. Several sets of universal ball bearings 1-2 are symmetrically arranged along the length of the left and right side walls of the guide frame 1. When the profile passes through the guide frame 1, the universal ball bearings 1-2 abut against the side wall of the cold-formed profile 3, thereby constraining the side wall of the profile and preventing deformation of the side wall.

[0032] Specifically, such as Figures 4-6 As shown, the guide frame 1 is formed by two U-shaped grooves of the same structure interlocking with each other, creating a rectangular cavity for the cold-formed profile 3 to pass through. Multiple mounting holes 1-4 for fixing universal ball bearings 1-2 are provided along the length of the side walls of the two U-shaped grooves. The mounting holes 1-4 are arranged one-to-one on the left and right sides, and one universal ball bearing 1-2 is installed in each mounting hole 1-4. The universal ball bearings 1-2 are typically positioned according to the subsequent rolling arc position of the cold-formed profile 3. For example... Figure 1 As shown, the cold-formed profile 3 will subsequently undergo left and right roll forming. Therefore, the two U-shaped grooves are combined, one on the left and one on the right. Universal ball bearings 1-2 are installed on the left and right sides of the guide frame 1, while the upper and lower parts of the guide frame 1 are not equipped with them. Emphasis is placed on enhancing the constraint and support of the left and right walls of the cold-formed profile 3 to ensure the accuracy of the subsequent roll forming. If the cold-formed profile 3 requires subsequent upper and lower roll forming, it can be... Figure 1 The guide frame 1 is rotated 90° for use, that is, the two U-shaped grooves are interlocked with each other using an upper and lower structure. At this time, the universal ball bearings 1-2 are set at the upper and lower parts of the guide frame 1, which can effectively guide the upper and lower walls of the profile to be rolled.

[0033] It should also be noted that, as Figure 6 As shown, for the guide frame 1 used for left and right roller profiles, the inner cavity height is generally matched with the profile height, and the width of the inner cavity can be changed by adjusting the relative position of the U-shaped groove. It has a narrow range of adaptability to profile height and a wide range of adaptability to profile width.

[0034] Preferably, the universal ball bearing 1-2 is a shock-absorbing universal ball bearing 1-2 with a shock-absorbing spring below the ball bearing. Its own shock absorption allows the ball bearing position to have a certain amount of fine adjustment stroke, which can ensure that the ball bearing fully fits the side wall of the profile. Especially for profiles with a certain curvature, it can achieve effective contact and restraint of each part and avoid hard scratches on the surface of the profile.

[0035] The guide frame 1 has ear plate assemblies 1-3 symmetrically arranged at its front and rear ends for connection with the mounting base 2, ensuring the levelness and stability of the guide frame 1. Generally, the ear plate assemblies 1-3 are symmetrically arranged on both sides of the guide frame 1, and there are no fewer than two ear plates on each side of the guide frame 1 to ensure the stability of the guide frame 1.

[0036] The mounting base 2 includes a horizontal movement mechanism and a lifting mechanism. The lifting mechanism is fixedly connected to the guide frame 1 through the ear plate assembly 1-3, thereby realizing the adjustment of the height of the guide frame 1. The bottom of the lifting mechanism is connected to the horizontal movement mechanism. The lifting mechanism drives the guide frame 1 to realize the horizontal orientation adjustment together, thereby ensuring that the position of the guide frame 1 is consistent with the center position of the product and ensuring the stable transportation of the profile product.

[0037] like Figure 7 As shown, the lateral movement mechanism includes a mounting base plate 2-1-1, a sliding seat 2-1-2, a left slider 2-1-3, and a right slider 2-1-4. The sliding seat 2-1-2 is fixed to the mounting base plate 2-1-1 with screws. Both ends of the sliding seat 2-1-2 are sealed by a limiting plate 2-1-5 and a lead screw fixing block 2-1-6, respectively. The left slider 2-1-3 and right slider 2-1-4, which can slide laterally along the sliding seat 2-1-2, are located within the sliding seat 2-1-2. The left slider 2-1-3 moves laterally via the rotation of a first lead screw 2-1-7, and the right slider 2-1-4 moves laterally via the rotation of a second lead screw 2-1-8. The tops of the left slider 2-1-3 and right slider 2-1-4 are provided with several threaded holes for connecting to a lifting mechanism; that is, a lifting mechanism is connected to both the left slider 2-1-3 and right slider 2-1-4. The left slider 2-1-3 is fixedly connected to the left U-shaped groove via the left lifting mechanism, and the right slider 2-1-4 is fixedly connected to the right U-shaped groove via the right lifting mechanism. By adjusting the lateral position of the left slider 2-1-3 and the right slider 2-1-4, the width of the guide frame 1 can be adjusted to ensure that the universal ball bearing 1-2 effectively guides the arc side wall of the roller.

[0038] The lead screw fixing block 2-1-6 is installed at the adjustment operation end of the first lead screw 2-1-7 / second lead screw 2-1-8. The lead screw fixing block 2-1-6 is provided with a through hole for the first lead screw 2-1-7 and the second lead screw 2-1-8 to pass through. The limiting plate 2-1-5 is located at the end away from the adjustment operation. The limiting plate 2-1-5 is provided with a rotating bearing that is fitted to the end of the first lead screw 2-1-7 and the second lead screw 2-1-8. The first lead screw 2-1-7 / second lead screw 2-1-8 passes through the lead screw fixing block 2-1-6, the left slider 2-1-3, and the right slider 2-1-4 and is then fitted onto the rotating bearing of the limiting plate 2-1-5. An operation end head 2-1-9 is provided at the end of the first lead screw 2-1-7 and the second lead screw 2-1-8 located outside the lead screw fixing block 2-1-6. The worker adjusts the position of the slider by rotating the operation end head 2-1-9.

[0039] Specifically, to achieve independent control of the positions of the left and right U-shaped grooves and facilitate rapid alignment between the guide frame 1 and the formed profile, the left slider 2-1-3 has a threaded hole on its side for threaded connection with the first lead screw 2-1-7 and a through hole for the second lead screw 2-1-8 to pass through. The right slider 2-1-4 has a threaded hole on its side for threaded connection with the second lead screw 2-1-8 and a through hole for the first lead screw 2-1-7 to pass through. During adjustment, the lead screws can be rotated by twisting the operating end 2-1-9 with a tool, thereby adjusting the lateral position of the sliders. When the first lead screw 2-1-7 rotates, only the left slider 2-1-3 is moved laterally, while the right slider 2-1-4 remains stationary; when the second lead screw 2-1-8 rotates, only the right slider 2-1-4 is moved laterally, while the left slider 2-1-3 remains stationary.

[0040] The first lead screw 2-1-7 and the second lead screw 2-1-8 have the same structure, both featuring a stepped design. Specifically, their left ends are both small-diameter ends, which are mounted on the limiting plate 2-1-5 with bearings. When the lead screw rotates, the small-diameter end slides smoothly within the bearing. The operating end on the right side of the lead screw has a stepped shaft with a variable diameter, which is mounted in the through hole of the lead screw fixing block 2-1-6. This design feature at both ends of the lead screw allows it to rotate without lateral displacement, ensuring that the sliders on both sides can move laterally on the lead screw. This allows for adjustment of the inner cavity width of the guide frame 1 to accommodate cold-formed profiles 3 with different cross-sectional shapes.

[0041] Preferably, the mounting base plate 2-1-1 has a guide groove 2-2-5 along its length, and the sliding seat 2-1-2 is fixedly installed in the guide groove 2-2-5 to prevent the sliding seat 2-1-2 from shifting along the width of the base plate during lateral movement.

[0042] Preferably, to ensure the horizontality of the left slider 2-1-3 and the right slider 2-1-4 during the lateral movement, the slide seat 2-1-2 is also provided with a guide rail pressure plate 2-1-10 to prevent the left slider 2-1-3 and the right slider 2-1-4 from derailing. The guide rail pressure plate 2-1-10 is threadedly connected to the slide seat 2-1-2.

[0043] Preferably, the lead screw fixing block 2-1-6 is composed of an upper fixing block and a lower fixing block, see reference. Figure 2 Semi-circular arc grooves are made on both the upper and lower fixing blocks, and when combined, they form a through hole for the lead screw to pass through. The split design of the lead screw fixing block 2-1-6 facilitates the installation and maintenance of the lead screw.

[0044] The mounting base plate 2-1-1 is also provided with elongated holes 2-1-11 on both sides for connecting with the equipment. The mounting base plate 2-1-1 is horizontally fixed by bolts passing through the elongated holes 2-1-11. The lateral position can be adjusted significantly according to the center position of the profile product through the elongated holes 2-1-11.

[0045] like Figure 8 As shown, the lifting mechanism includes a lifting base 2-2-1, a height adjustment shaft 2-2-2, a bushing 2-2-3, and a locking nut 2-2-4. The lifting base 2-2-1 spans the slide rail seat 2-1-2. A threaded hole corresponding to the threaded hole at the top of the left slider 2-1-3 / right slider 2-1-4 is provided in the middle of the lifting base 2-2-1. The lifting base 2-2-1 is fixed to the left slider 2-1-3 / right slider 2-1-4 by bolts. A height adjustment shaft 2-2-2 is fixedly connected to each end of the lifting base 2-2-1 for connection with the ear plate assembly 1-3. The height adjustment shaft 2-2-2 is provided with an external thread. Several bushings 2-2-3 of different thicknesses are fitted on the lower part of the height adjustment shaft 2-2-2. Two sets of locking nuts 2-2-4 are fitted on the upper part of the bushings 2-2-3. The height of the locking nuts 2-2-4 is adjusted by the number of bushings 2-2-3, thereby adjusting the height of the guide frame 1.

[0046] Preferably, each set of locking nuts 2-2-4 includes a working positive nut and a reverse nut to prevent the nuts from loosening due to vibration.

[0047] Preferably, in order to ensure the stability of the connection between the lifting base 2-2-1 and the slider, the bottom of the lifting base 2-2-1 is provided with a guide groove 2-2-5 that matches the outer diameter of the left slider 2-1-3 / right slider 2-1-4. The lifting base 2-2-1 is first secured to the outside of the slider by the guide groove 2-2-5 and then tightened with screws to avoid twisting and displacement between the lifting base 2-2-1 and the slider during the position adjustment process.

[0048] The working principle of this utility model is as follows:

[0049] By using the elongated holes in the mounting base plate, the lateral position can be adjusted over a wide range according to the center position of the cold-bent product. After connecting the height adjustment shaft to the ear plate assembly one by one, first manually rotate the operating end to adjust the position of the left and right sliders according to the actual width of the cold-bent product; then, adjust the locking height of the locking nut according to the height of the cold-bent product by adjusting the number of bushings, so that the inner cavity position of the guide bracket is consistent with the output position of the cold-bent profile product.

[0050] After the cold-formed profiles are output from the roll forming unit, they directly enter the cavity of the guide frame. The universal ball bearings on both sides of the guide frame abut against the side wall of the product, constraining the shape of the product and preventing hard scratches on the surface of the profile.

[0051] The above description is only a preferred embodiment of the present utility model. All equivalent changes and modifications made within the scope of the patent application of the present utility model shall be covered by the present utility model.

Claims

1. A large span guide and support device for a cold roll forming line, characterized by: The guide bracket (1) is provided with a plurality of groups of universal ball bearings (1-2) on the side wall of the guide bracket (1) for abutting the side wall of the profile.

2. A long span guide and support device for a cold roll forming line as defined in claim 1, characterized in that: The guide bracket (1) comprises a left U-shaped groove and a right U-shaped groove arranged oppositely, and the left U-shaped groove and the right U-shaped groove are buckled to form a cavity for the cold bending profile (3) to pass through; a plurality of mounting holes (1-4) for fixing the universal ball bearings (1-2) are arranged on the side wall of the left U-shaped groove and the right U-shaped groove along the length direction; the two ends of the guide bracket (1) are respectively provided with an ear plate assembly (1-3) for fixed connection with the lifting mechanism, and the ear plate assemblies (1-3) are arranged symmetrically along the left and right of the guide bracket (1).

3. A long span guide and support device for a cold roll forming line as defined in claim 1, characterized in that: The horizontal moving mechanism comprises a mounting bottom plate (2-1-1), a sliding groove seat (2-1-2) fixed on the mounting bottom plate (2-1-1), and a left sliding block (2-1-3) and a right sliding block (2-1-4) arranged in the sliding groove seat (2-1-2) and in sliding fit with the sliding groove seat (2-1-2); the left sliding block (2-1-3) is in transmission connection with a first lead screw (2-1-7), the right sliding block (2-1-4) is in transmission connection with a second lead screw (2-1-8), and operation end heads (2-1-9) for worker operation are arranged at one end of the first lead screw (2-1-7) and the second lead screw (2-1-8); screw holes for connecting the lifting mechanism are arranged on the top of the left sliding block (2-1-3) and the right sliding block (2-1-4).

4. A long span guide and support device for a cold roll forming line as defined in claim 3, characterized in that: The left sliding block (2-1-3) is provided with a threaded hole for transmission connection with the first lead screw (2-1-7) and a through hole for the second lead screw (2-1-8) to penetrate, and the right sliding block (2-1-4) is provided with a threaded hole for transmission connection with the second lead screw (2-1-8) and a through hole for the first lead screw (2-1-7) to penetrate.

5. A long span guide and support device for a cold roll forming line as defined in claim 3, wherein: The mounting bottom plate (2-1-1) is provided with a guide groove (2-2-5) along the length direction of the bottom plate, and the sliding groove seat (2-1-2) is fixedly installed in the guide groove (2-2-5); the sliding groove seat (2-1-2) is further provided with a guide rail pressing plate (2-1-10) for preventing the left sliding block (2-1-3) and the right sliding block (2-1-4) from derailing.

6. A long span guide and support device for a cold roll forming line as defined in claim 4, characterized in that: The lifting mechanism comprises a lifting base (2-2-1) transversely arranged on the sliding groove seat (2-1-2), and a height adjusting shaft (2-2-2) arranged on the lifting base (2-2-1) and used for connecting with the ear plate assembly (1-3); the height adjusting shaft (2-2-2) is provided with an external thread, and a locking nut (2-2-4) and a plurality of shaft sleeves (2-2-3) with different thicknesses are sleeved on the height adjusting shaft (2-2-2); the lifting base (2-2-1) is in threaded connection with the left sliding block (2-1-3) and the right sliding block (2-1-4).

7. A long span guide and support device for a cold roll forming line as defined in claim 6, characterized in that: The lifting base (2-2-1) is provided with a guide groove (2-2-5) at the bottom, which is matched with the outer diameter of the left slider (2-1-3) and the right slider (2-1-4).

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