Bracket device based on pressure induction

Abstract

The utility model provides a bracket device based on pressure induction, which comprises a rack, a lifting driving source, a bracket assembly, a lifting transmission assembly, a telescopic pressure component, a signal board and a detection sensor, the lifting driving source is in transmission connection with the bracket assembly through the lifting transmission assembly, and the transmission tail end of the lifting transmission assembly is provided with a lifting bracket fixing seat; the bracket assembly comprises supporting bracket beams, the supporting bracket beams are distributed at the top of the bracket fixing base and hinged to the bracket fixing base, the pressure component is installed on the lifting transmission assembly and acts on the bottoms of the supporting bracket beams, and the signal board and the detection sensor are installed on the supporting bracket beams and the bracket fixing base respectively; when the bracket assembly is in a non-supporting state, the pressure component drives one end of the supporting bracket beam to be in an upwarp state. According to the invention, the lifting height of the bracket assembly can be more accurately controlled, so that a supported object can keep better planeness, and the supported object cannot be scratched down due to the gravity of the supported object and cannot be jacked to be bent.

Description

Technical Field

[0001] The utility model relates to the technical field of prestressed pipe pile production, in particular to a bracket device based on pressure induction. Background Art

[0002] The roll welding machine is one of the important production equipment in the production process of prestressed pipe piles. It is used to produce cage reinforcement, which is the main frame of the prestressed pipe piles. Usually, the roll welding machine includes five parts: head assembly, tail assembly, automatic reinforcement threading mechanism, material unloading buffer mechanism, and electrical system. For example, a roll welding machine disclosed in the Chinese utility model patent with application number 202220682516.9. In addition, the roll welding machine is equipped with multiple bracket mechanisms at the tail of the machine. The bracket mechanism has a liftable cage reinforcement bracket. After the cage reinforcement bracket rises, it can support the cage reinforcement to ensure that the longer cage reinforcement will not produce a large deflection due to its own weight.

[0003] At present, the bracket mechanism mainly drives the cage reinforcement bracket to rise and fall through the cylinder and the scissor rod group. However, this structure has the defect of large positioning error of the lifting height. When working, if the cylinder drives the cage reinforcement bracket to rise insufficiently through the scissor rod group, the cage reinforcement will bend downward; if the cylinder drives the cage reinforcement bracket to rise too high through the scissor rod group, the cage reinforcement will be bent. Ultimately, the quality of the cage reinforcement roll welding is affected, which also affects the quality of the prestressed pipe pile. Utility Model Content

[0004] In view of the above-mentioned shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a bracket device based on pressure sensing, which can more accurately control the lifting height of the bracket assembly.

[0005] To achieve the above-mentioned purpose, the utility model provides a bracket device based on pressure sensing, comprising a fixed frame, a lifting drive source installed on the frame, at least one set of liftable bracket components, a lifting transmission component, a retractable pressure component, a signal board, and a detection sensor capable of sensing the signal board, the lifting drive source is connected to the bracket component through the lifting transmission component, the transmission end of the lifting transmission component is a liftable bracket fixing seat, the bracket component comprises a supporting bracket beam, the supporting bracket beam is distributed on the top of the bracket fixing seat and is hinged to the bracket fixing seat, the pressure component is installed on the lifting transmission component and acts on the bottom of the supporting bracket beam, the signal board and the detection sensor are respectively installed on the supporting bracket beam and the bracket fixing seat;

[0006] When the bracket assembly is in a non-supporting state, the pressure component drives one end of the supporting bracket beam to be in an upward tilted state.

[0007] A preferred embodiment of the above technical solution is that the pressure member, and the hinge centers of the support bracket beam and the bracket fixing seat are distributed on both sides of the bracket fixing seat.

[0008] A preferred embodiment of the above technical solution is that a horizontally extending first connecting ear is fixedly provided on the outside of the bracket fixing seat, a downwardly extending second connecting ear is provided at the bottom of the support bracket beam, and the first connecting ear and the second connecting ear are hinged.

[0009] A preferred embodiment of the above technical solution is that the pressure member includes a spring seat fixed to the lifting transmission assembly, a pressure spring assembled in the spring seat, and a spring cap movably assembled up and down on the top of the spring seat. The upper end of the pressure spring is connected to the spring cap, and the top surface of the spring cap is in contact and cooperation with the bottom surface of the support bracket beam.

[0010] A preferred embodiment of the above technical solution is that the top surface of the spring cap is an arc-shaped curved surface.

[0011] A preferred embodiment of the above technical solution is that the lifting transmission assembly includes a first crank, a second crank and a transmission connecting rod. Both ends of the first crank and both ends of the second crank are respectively hinged to the frame and the transmission connecting rod. The lifting driving source is a hydraulic cylinder. The piston rod of the hydraulic cylinder is hinged to the first crank or the second crank, the cylinder body of the hydraulic cylinder is hinged to the frame, the bracket fixing seat is fixed to the transmission connecting rod, and the pressure member is installed on the transmission connecting rod.

[0012] A preferred embodiment of the above technical solution is that the piston rod of the hydraulic cylinder is hinged to the first crank, and there are two second cranks, which are symmetrically distributed on both sides of the first crank.

[0013] A preferred embodiment of the above technical solution is that the bracket assembly further includes several support sprockets rotatably installed on the support bracket beam, and a support chain sleeved on the outer periphery of the several support sprockets. The upper end of the support chain is higher than the top surface of the support bracket beam.

[0014] A preferred embodiment of the above technical solution is that the bracket assembly further includes a chain support plate fixed to the support bracket beam. The support bracket beam is distributed on the inner peripheral side of the support chain, and the top of the support bracket beam is in contact and cooperation with the lower end of the upper part of the support chain.

[0015] A preferred embodiment of the above technical solution is that the bracket assembly further includes a tensioning unit. At least one of the several support sprockets is rotatably installed on an adjustment shaft. The tensioning unit includes an adjustment groove opened in the support bracket beam and a locking nut threadedly connected to the adjustment shaft. The adjustment groove extends straight along the length direction of the support chain. The adjustment shaft is arranged in the adjustment groove, and the locking nut abuts against the outer wall surface of the support bracket beam.

[0016] As described above, the bracket device based on pressure sensing involved in the present utility model has the following beneficial effects:

[0017] In this application, when the bracket device is working, the lifting drive source drives the bracket assembly to rise through the lifting transmission assembly. When the bracket assembly contacts the object to be supported, under the pressure of the object to be supported, the upturned end of the support bracket beam descends, and the pressure component is compressed. At the same time, the detection sensor can detect the signal plate, and the output signal of the detection sensor changes. The control system controls the lifting drive source to stop operating, maintaining the current rising height of the bracket assembly and maintaining the support state of the object to be supported. Therefore, through the pressure component, the cooperating signal plate and detection sensor, and the hinge structure between the support bracket beam and the bracket fixing seat, this application can more precisely control the lifting height of the bracket assembly, controlling the rising height of the bracket assembly to the height when it contacts the object to be supported, effectively reducing the positioning error of the lifting height of the bracket assembly, and finally enabling the object to be supported to maintain good flatness, neither sagging due to its own gravity nor being bent upward. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the bracket device based on pressure sensing of this application.

[0019] Figure 2 is Figure 1 the rear view of

[0020] Figure 3 is Figure 1 the top view of

[0021] Figure 4 is Figure 3 the sectional view taken along the line A-A of , and the frame and the lifting drive source are omitted.

[0022] Figure 5 is a schematic structural diagram of the bracket assembly in this application.

[0023] Description of Component Labels

[0024] 10 Frame

[0025] 20 Lifting Drive Source

[0026] 30 Bracket Assembly

[0027] 31 Support Bracket Beam

[0028] 32 Second Connecting Ear

[0029] 33 Support Sprocket

[0030] 34 Support Chain

[0031] 35 Chain support plate

[0032] 36 Adjusting shaft

[0033] 37 Adjusting groove

[0034] 38 Locking nut

[0035] 40 Lifting drive assembly

[0036] 41 Bracket fixing seat

[0037] 42 First connecting ear

[0038] 43 First crank

[0039] 44 Second crank

[0040] 45 Transmission connecting rod

[0041] 50 Pressure component

[0042] 51 Spring seat

[0043] 52 Pressure spring

[0044] 53 Spring cap

[0045] 60 Signal plate

[0046] 70 Detection sensor Detailed implementation mode

[0047] The following specific embodiments illustrate the implementation mode of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0048] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the implementation conditions of the present invention. Therefore, they do not have any technical essence. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for convenience of description and are not used to limit the implementation scope of the present invention. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope within which the present invention can be implemented.

[0049] It should also be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element present at the same time. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or can also be indirectly connected to the other element through an intermediate element.

[0050] In addition, the descriptions involving "first", "second", etc. in this application are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0051] The present utility model provides a bracket device based on pressure sensing for supporting a longer component. The longer component supported by the bracket device is defined as the object to be supported. The following embodiments are described by taking the bracket device used in the production of prestressed pipe piles as an example. The bracket device is configured at the tail of the welding machine and there are multiple sets. The object to be supported is the cage bars processed and produced by the welding machine. At the same time, for the convenience of description, the definitions of each direction in the following embodiments are as follows: the length direction of the cage bars is defined as the front-back direction; based on this, Figure 3 In the shown view, the left side and the right side of the paper surface are the front direction and the back direction respectively, the upper side and the lower side of the paper surface are the right direction and the left direction respectively, and the front side and the back side of the paper surface are the upper direction and the lower direction respectively.

[0052] As Figures 1 to 4 shown, the bracket device based on pressure sensing involved in the present utility model includes a fixedly arranged frame 10, a lifting drive source 20 installed on the frame 10, at least one set of liftable bracket assemblies 30, a lifting transmission assembly 40, a pressure member 50 that can be telescopically extended up and down, a signal plate 60, and a detection sensor 70; in this embodiment, there are two sets of bracket assemblies 30 and they are symmetrically arranged left and right. The lifting drive source 20 is in transmission connection with the bracket assemblies 30 through the lifting transmission assembly 40 to drive the bracket assemblies 30 to rise or fall. In particular, the transmission end of the lifting transmission assembly 40 is a liftable bracket fixing seat 41. The bracket fixing seat 41 is a rectangular steel pipe extending straight left and right. Each set of bracket assemblies 30 includes a support bracket beam 31. The support bracket beams 31 are distributed on the top of the bracket fixing seat 41 and are hinged to the bracket fixing seat 41. The pressure member 50 is installed on the lifting transmission assembly 40 and acts on the bottom of the support bracket beam 31. The signal plate 60 and the detection sensor 70 are respectively installed on the support bracket beam 31 and the bracket fixing seat 41, and the detection sensor 70 can sense the signal plate 60.

[0053] When the above-mentioned bracket assembly 30 is in a non-support state, the bracket assembly 30 does not support the cage reinforcement. Under the action of the pressure member 50 pushing upward against the support bracket beam 31 and based on the hinge structure between the support bracket beam 31 and the bracket fixing seat 41, one end of the support bracket beam 31 is in an upturned state, that is, the support bracket beam 31 as a whole has an inclination angle relative to the horizontal plane. When the cage reinforcement is produced by the welding machine, the towing cart in the welding machine drags the cage reinforcement forward. When the cage reinforcement passes above the bracket device, the bracket device works. At this time, the lifting drive source 20 drives the bracket assembly 30 to rise through the lifting transmission assembly 40. When the bracket assembly 30 contacts the cage reinforcement, under the pressure of the cage reinforcement, the upturned end of the support bracket beam 31 descends, and the pressure member 50 is compressed. At the same time, the detection sensor 70 can detect the signal plate 60, and the output signal of the detection sensor 70 changes. The control system controls the lifting drive source 20 to stop operating, maintaining the current rising height of the bracket assembly 30, and thus maintaining the support state for the cage reinforcement. The bracket assembly 30 is in a support state, realizing reliable support for the cage reinforcement.

[0054] Therefore, the bracket device based on pressure induction involved in the present application further includes a control system, and both the lifting drive source 20 and the detection sensor 70 are communicatively connected to the control system. In particular, the present application constitutes a pressure induction system through the pressure member 50, the cooperating signal plate 60 and detection sensor 70, and the hinge structure between the support bracket beam 31 and the bracket fixing seat 41, which can more precisely control the lifting height of the bracket assembly 30, control the rising height of the bracket assembly 30 to the height when it contacts the cage reinforcement, effectively reducing the positioning error of the lifting height of the bracket assembly 30, and ultimately enabling the cage reinforcement to maintain good flatness, so that it will neither deflect due to its own gravity nor be bent by being pushed, greatly ensuring the welding quality of the cage reinforcement and ultimately ensuring the quality of the prestressed pipe pile.

[0055] Preferably, in the bracket device involved in the present application, the signal plate 60 can be fixed to the support bracket beam 31 and the detection sensor 70 can be fixed to the bracket fixing seat 41; or the signal plate 60 can be fixed to the bracket fixing seat 41 and the detection sensor 70 can be fixed to the support bracket beam 31. Figure 4 In the shown embodiment, the signal plate 60 is fixed to the support bracket beam 31 and the detection sensor 70 is fixed to the bracket fixing seat 41. When the lifting drive source 20 drives the bracket assembly 30 to rise through the lifting transmission assembly 40 and contacts the cage reinforcement, the support bracket beam 31 rotates downward, driving the signal plate 60 to descend, causing the output signal of the detection sensor 70 to change, giving a signal that the bracket assembly 30 has risen in place.

[0056] Further, as Figures 1 to 4As shown, the pressure component 50, and the hinge centers of the support bracket beam 31 and the bracket fixing seat 41 are distributed on the front and rear sides of the bracket fixing seat 41. Thus, when the bracket assembly 30 is in a non-support state, the pressure component 50 drives the front end of the support bracket beam 31 to tilt upward; and, the signal plate 60 and the detection sensor 70 are distributed between the pressure component 50 and the hinge centers of the support bracket beam 31 and the bracket fixing seat 41. Additionally, the hinge structure between the support bracket beam 31 and the bracket fixing seat 41 is: a first connecting ear 42 extending horizontally backward is fixedly provided on the rear side of the bracket fixing seat 41, a second connecting ear 32 extending downward is provided at the bottom of the support bracket beam 31, and the first connecting ear 42 and the second connecting ear 32 are hinged by a pin extending left and right.

[0057] Furthermore, the preferred structure of the pressure component 50 is: as Figure 2 and Figure 4 shown, the pressure component 50 includes a spring seat 51 fixed to the lifting transmission component 40, a pressure spring 52 assembled in the spring seat 51, and a spring cap 53 movably assembled up and down on the top of the spring seat 51. The pressure spring 52 extends up and down, the lower end of the pressure spring 52 is fixed in the spring seat 51, the upper end of the pressure spring 52 is connected to the spring cap 53, and the top surface of the spring cap 53 is in contact and cooperation with the bottom surface of the support bracket beam 31. When the bracket assembly 30 is in a non-support state, under the action of the pressure spring 52, the spring cap 53 is in the upper limit position, causing the front end of the support bracket beam 31 to tilt upward. When the bracket assembly 30 is in a support state, the up and down telescoping of the pressure spring 52 allows the spring cap 53 to descend, which also allows the support bracket beam 31 to rotate downward by an angle around its hinge center with the bracket fixing seat 41 and stop rotating further under the abutting action of the bracket fixing seat 41. Preferably, the top surface of the spring cap 53 is an arc-shaped curved surface to reduce the contact friction force between it and the bottom surface of the support bracket beam 31.

[0058] Furthermore, the preferred structure of the lifting transmission component 40 is: as Figure 1 、 Figure 2 and Figure 4As shown, the lifting drive assembly 40 is a double-crank lead screw structure. The lifting drive assembly 40 includes a first crank 43, a second crank 44, and a drive link 45. The lower end and the upper end of the first crank 43 are respectively hinged to the frame 10 and the drive link 45. The lower end and the upper end of the second crank 44 are respectively hinged to the frame 10 and the drive link 45. The lifting drive source 20 is a hydraulic cylinder. The piston rod of the hydraulic cylinder is hinged to the first crank 43 or the second crank 44, and the cylinder block of the hydraulic cylinder is hinged to the frame 10. The bracket fixing seat 41 is fixed to the drive link 45, and the spring seat 51 in the pressure member 50 is fixed to the drive link 45. When the hydraulic system drives the piston rod of the hydraulic cylinder to extend, the drive link 45 is driven to rise horizontally through the first crank 43 and the second crank 44, and then the bracket fixing seat 41 and the left and right two sets of bracket assemblies 30 are driven to rise horizontally together. On the contrary, when the hydraulic system drives the piston rod of the hydraulic cylinder to retract, the drive link 45 is driven to descend horizontally through the first crank 43 and the second crank 44, and then the bracket fixing seat 41 and the left and right two sets of bracket assemblies 30 are driven to descend horizontally together.

[0059] Preferably, in this embodiment, as Figure 1 shown, the piston rod of the hydraulic cylinder is hinged to the first crank 43. There are two second cranks 44, which are symmetrically distributed on the left and right sides of the first crank 43, improving the operating stability of the lifting drive assembly 40.

[0060] Furthermore, the preferred structure of the bracket assembly 30 is: as Figure 5 shown, the bracket assembly 30 further includes two support sprockets 33 that are rotatably mounted on the support bracket beam 31, one in the front and the other in the back, and a support chain 34 sleeved on the outer circumferences of the two support sprockets 33. The upper end of the support chain 34 is higher than the top surface of the support bracket beam 31. The cage bars are supported by the support sprockets 33 and the support chain 34. When the cage bars pass forward through the bracket assembly 30, the support chain 34 rotates accordingly, reducing the resistance when the cage bars are dragged forward. At the same time, the bracket assembly 30 further includes a chain support plate 35 fixed to the inner surface of the support bracket beam 31. The support bracket beam 31 is distributed on the inner circumferential side of the support chain 34. The top of the support bracket beam 31 is in contact and cooperation with the lower end of the upper part of the support chain 34, preventing the support chain 34 from sagging.

[0061] Preferably, as Figure 1 and Figure 2As shown, the bracket assembly 30 further includes a tensioning unit. The front support sprocket 33 of the two support sprockets 33 is rotatably mounted on the adjustment shaft 36 that extends straight left and right. The tensioning unit includes an adjustment slot 37 formed in the support bracket beam 31 and a locking nut 38 threadedly connected to the adjustment shaft 36. The adjustment slot 37 extends straight forward and backward along the length direction of the support chain 34. The adjustment shaft 36 passes through the adjustment slot 37, and the locking nut 38 abuts against the outer wall surface of the support bracket beam 31. In this way, the front and rear positions of the front support sprocket 33 can be adjusted, and then the tension of the support chain 34 can be adjusted, improving the support effect on the cage bars.

[0062] In summary, the bracket device based on pressure sensing involved in the present application can reliably support the cage bars during the roll welding production process, can not only avoid the downward deflection of the cage bars due to their own gravity, but also avoid the cage bars being bent upward due to excessive support. Moreover, the bracket device based on pressure sensing involved in the present application has a simple structure and reliable operation, and can also adapt to the cage bars of various pile types. Therefore, the utility model effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0063] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A pressure-sensitive bracket device, comprising a fixed frame (10), a lifting drive source (20) mounted on the frame (10), at least one set of liftable bracket components (30), and a lifting transmission component (40), wherein the lifting drive source (20) is connected to the bracket component (30) through the lifting transmission component (40), and characterized in that: It also includes a retractable pressure component (50), a signal board (60), and a detection sensor (70) capable of sensing the signal board (60); the transmission end of the lifting transmission assembly (40) is a liftable bracket fixing seat (41); the bracket assembly (30) includes a support bracket beam (31); the support bracket beam (31) is distributed on the top of the bracket fixing seat (41) and is hinged to the bracket fixing seat (41); the pressure component (50) is installed on the lifting transmission assembly (40) and acts on the bottom of the support bracket beam (31); the signal board (60) and the detection sensor (70) are installed on the support bracket beam (31) and the bracket fixing seat (41) respectively; When the bracket assembly (30) is in a non-supporting state, the pressure component (50) drives one end of the supporting bracket beam (31) to be in an upward tilted state.

2. The pressure-sensing bracket device according to claim 1, characterized in that: The pressure component (50) and the hinge centers of the support bracket beam (31) and the bracket fixing seat (41) are distributed on both sides of the bracket fixing seat (41).

3. The pressure-sensing bracket device according to claim 1 or 2, characterized in that: A first connecting ear (42) extending horizontally is fixedly disposed on the outside of the bracket fixing seat (41), and a second connecting ear (32) extending downward is disposed on the bottom of the supporting bracket beam (31), and the first connecting ear (42) and the second connecting ear (32) are hinged.

4. The pressure-sensing bracket device according to claim 1, characterized in that: The pressure component (50) comprises a spring seat (51) fixed to the lifting transmission assembly (40), a pressure spring (52) mounted in the spring seat (51), and a spring cap (53) mounted on the top of the spring seat (51) so as to be movable up and down, wherein the upper end of the pressure spring (52) is connected to the spring cap (53), and the top surface of the spring cap (53) is in contact with the bottom surface of the support bracket beam (31).

5. The pressure-sensing bracket device according to claim 4, characterized in that: The top surface of the spring cap (53) is an arc curved surface.

6. The pressure-sensing bracket device according to claim 1 or 4, characterized in that: The lifting transmission assembly (40) comprises a first crank (43), a second crank (44) and a transmission connecting rod (45); both ends of the first crank (43) and both ends of the second crank (44) are respectively hinged to the frame (10) and the transmission connecting rod (45); the lifting drive source (20) is a hydraulic cylinder; the piston rod of the hydraulic cylinder is hinged to the first crank (43) or the second crank (44); the cylinder body of the hydraulic cylinder is hinged to the frame (10); the bracket fixing seat (41) is fixed to the transmission connecting rod (45); and the pressure component (50) is installed on the transmission connecting rod (45).

7. The pressure-sensing bracket device according to claim 6, characterized in that: The piston rod of the hydraulic cylinder is hinged to the first crank (43), and there are two second cranks (44) which are symmetrically distributed on both sides of the first crank (43).

8. The pressure-sensing bracket device according to claim 1, characterized in that: The bracket assembly (30) further comprises a plurality of support sprockets (33) rotatably mounted on the support bracket beam (31), and a support chain (34) sleeved on the outer periphery of the plurality of support sprockets (33), wherein the upper end of the support chain (34) is higher than the top surface of the support bracket beam (31).

9. The pressure-sensing bracket device according to claim 8, characterized in that: The bracket assembly (30) also includes a chain support plate (35) fixed to a support bracket beam (31), wherein the support bracket beam (31) is distributed on the inner peripheral side of the support chain (34), and the top of the support bracket beam (31) contacts and cooperates with the lower end of the upper section of the support chain (34).

10. The pressure-sensing bracket device according to claim 8, characterized in that: The bracket assembly (30) also includes a tensioning unit, at least one of the plurality of support sprockets (33) is rotatably mounted on an adjustment shaft (36), the tensioning unit includes an adjustment slot (37) provided in the support bracket beam (31), and a locking nut (38) threadedly connected to the adjustment shaft (36), the adjustment slot (37) extending straight along the length direction of the support chain (34), the adjustment shaft (36) passing through the adjustment slot (37), and the locking nut (38) abutting against the outer wall surface of the support bracket beam (31).

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