Stretching mechanism and operating frame height adjusting device
By designing the extension mechanism and height adjustment device of the portable operating frame, the problem of the inability to adjust the height of the operating frame is solved, improving workers' climbing efficiency and saving costs.
Patent Information
- Application Number
- CN202420803019.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-18
- Publication Date
- 2025-03-25
- Estimated Expiration
- 2034-04-18
AI Technical Summary
The existing portable operating rack cannot effectively adjust the height, which makes it difficult for shorter workers to climb up the operating rack, reduces work efficiency, and needs to replace the operating rack when working at different heights, increasing costs.
A stretching mechanism is designed, including an extension member and an operating frame height adjustment device. The extension mechanism simplifies the worker's climbing process by setting foot pedals and locking foot holes, and realizes height adjustment of the operating frame through a telescopic rod.
By setting up foot pedals, the time for workers to climb the operating frame is reduced and the work efficiency is improved. Through the telescopic rod, the need to replace the operating frame is avoided and costs are saved.
Smart Images
Figure CN222667529U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of building construction equipment, in particular to a stretching mechanism and an operating frame height regulating device. Background Art
[0002] The operating frame can provide a stable working platform, allowing workers to perform operations at different heights, such as maintenance, installation, cleaning, etc. However, it is inconvenient for workers to move the operating frame to different places for work, so workers need a portable operating frame. However, if the workers are short, it will be very difficult to climb up the portable operating frame. The time for workers to climb to the operating frame is prolonged, which reduces the workers' work efficiency.
[0003] In addition, if workers work at different heights, the existing operating frames cannot adjust the height, resulting in the workers having to replace other operating frames to continue working, which increases costs. Utility Model Content
[0004] The purpose of this section is to summarize some aspects of the embodiments of the utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and utility model name of this application to avoid blurring the purpose of this section, specification abstract and utility model name, and such simplifications or omissions cannot be used to limit the scope of the utility model.
[0005] In view of the above or existing problems in the prior art that workers are short in height and find it very difficult to climb up the portable operating frame, which prolongs the time for workers to climb up the operating frame and reduces the work efficiency of workers, the present utility model is proposed.
[0006] Therefore, an object of the present invention is to provide a stretching mechanism.
[0007] In order to solve the above technical problems, the utility model provides the following technical solutions: a stretching mechanism, characterized in that: it includes:
[0008] The extension piece includes two connecting plates, a rotating support plate disposed at the bottom of the connecting plates, a rotating support shell disposed on the rotating support plate, a first connecting rod disposed on the rotating support shell, a fixing rod disposed on the first connecting rod, and a fixing sheet disposed on the fixing rod;
[0009] A same steel rope is connected between the two fixing plates, and a foot pedal is arranged in the rotating support shell. During operation, the foot pedal is clamped with the steel rope.
[0010] As a preferred solution of the extension mechanism of the utility model, wherein: the connecting plate includes two connecting blocks, the connecting blocks are arranged at the bottom of the connecting plate, and the sides of the two connecting blocks close to each other are rotatably connected to the rotating support plate. During operation, the end of the rotating support plate away from the rotating support shell contacts the bottom of the connecting plate, and the rotating support shell includes two first bolts and a limit rod.
[0011] As a preferred solution of the extension mechanism of the utility model, wherein: the limit rod passes through the rotation support shell and the rotation support plate, the limit rod is close to the end of the rotation support plate away from the connecting plate, the outer walls on both sides of the rotation support plate are in conflict with the inner walls on both sides of the rotation support shell, and the rotation support plate and the rotation support shell are rotatably connected.
[0012] As a preferred solution of the extension mechanism of the utility model, wherein: the distance from the end of the first bolt to the end of the rotating support shell close to the rotating support plate is shorter than the distance from the end of the limiting rod to the end of the rotating support shell close to the rotating support plate, and during operation, both of the first bolts penetrate one side of the rotating support shell, extend and are inserted into the rotating support plate for limiting.
[0013] As a preferred solution of the extension mechanism of the utility model, wherein: the sides of the two first connecting rods that are close to each other are rotatably connected to the outer wall of the rotating support shell, when in operation, the end of the rotating support shell away from the rotating support plate contacts the fixed rod, and the inner walls on both sides of the rotating support shell are rotatably connected to the outer walls on both sides of the foot pedal.
[0014] As a preferred solution of the extension mechanism of the utility model, wherein: the foot pedal includes a descending shell, the descending shell is inclined downward in a direction parallel to one side of the steel rope, and two second connecting rods are arranged on the top of the descending shell, and the top height of the second connecting rod near the highest point of the top of the descending shell is flush with the top height of the second connecting rod near the lowest point of the top of the descending shell.
[0015] As a preferred solution of the extension mechanism of the utility model, wherein: the downward inclined end of the landing shell is provided with a first slide groove and a second slide groove, the first slide groove and the second slide groove are connected, the distance from the top inner wall to the bottom inner wall of the first slide groove is shorter than the distance from the top inner wall to the bottom inner wall of the second slide groove, and a slide plate is slidably sleeved in the first slide groove.
[0016] As a preferred solution of the extension mechanism of the utility model, wherein: an arc-shaped limit plate is provided on the side of the slide away from the downward inclined end of the landing shell, the distance from the top height to the bottom height of the arc-shaped limit plate clamped with the steel rope is greater than the distance from the top inner wall to the bottom inner wall of the first slide groove, a locking foot hole is provided at the top of the slide, and an anti-slip groove is provided at the top of the slide, and the anti-slip groove is located between the downward inclined end of the slide and the locking foot hole.
[0017] The extension mechanism of the utility model has the following beneficial effects: by providing a foot pedal, it is prevented that shorter workers have difficulty climbing onto the portable operating frame, the time taken by workers to climb to the operating frame is reduced, and the work efficiency of workers is improved; by providing a foot locking hole, the worker's foot is inserted into the foot locking hole to limit the foot and prevent it from slipping, further facilitating the worker's climbing.
[0018] In actual use, workers still work at different heights, and the existing operating frames cannot adjust the height, which causes the workers to replace other operating frames to continue working, increasing the cost.
[0019] In order to solve the above technical problems, the utility model also provides the following technical solutions: an operating frame height adjustment device, characterized in that: it includes:
[0020] The lifting member includes a first supporting plate, a first curved plate arranged on the first supporting plate, a second curved plate arranged on one side of the first curved plate, and a second supporting plate arranged on the second curved plate, the second curved plate is threadedly connected with a wing bolt passing through the first curved plate, a nut is arranged on the wing bolt, and the first supporting plate and the second supporting plate are rotatably connected with a U-shaped bracket at one end away from each other.
[0021] As a preferred solution of the height adjustment device of the operating frame of the utility model, wherein: a telescopic groove is opened at the bottom of the U-shaped bracket, a telescopic rod is slidably sleeved in the telescopic groove, a plurality of evenly arranged limiting holes are arranged on the telescopic rod, and the U-shaped bracket is provided with a second bolt that penetrates the outer wall of the U-shaped bracket and is threadedly connected to the limiting hole.
[0022] The beneficial effect of the operating frame height adjustment device of the utility model is that by arranging the telescopic rod, workers do not need to change other operating frames to continue working, thus saving costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0024] Figure 1 It is a schematic diagram of the three-dimensional structure of the extension mechanism and the operating frame height adjustment device.
[0025] Figure 2 It is a schematic diagram of the three-dimensional enlarged structure of the extension part.
[0026] Figure 3 for Figure 2 Enlarged structural diagram at A in the middle.
[0027] Figure 4 for Figure 2 Enlarged structural diagram at B in the middle.
[0028] Figure 5 It is a schematic diagram of the partially cutaway enlarged structure of the foot pedal, fixing plate and steel rope after assembly.
[0029] Figure 6 It is a three-dimensional enlarged structural diagram of the lifting parts.
[0030] Figure 7 for Figure 6 Enlarged structural diagram at point C in the middle.
[0031] Figure 8 for Figure 6 Enlarged structural diagram at D in the middle.
[0032] Fig. 9 for Figure 6 Enlarged structural diagram at E in the middle. DETAILED DESCRIPTION
[0033] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.
[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0035] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.
[0036] Example 1
[0037] Reference Figure 1-2, which is the first embodiment of the utility model, and this embodiment provides a stretching mechanism. By setting a foot pedal 106, it can prevent shorter workers from climbing up the portable operating frame with difficulty, reduce the time for workers to climb up the operating frame, and improve the work efficiency of workers.
[0038] Specifically, the extension member 100 includes two connecting plates 101, a rotating support plate 102 disposed at the bottom of the connecting plate 101, a rotating support shell 103 disposed on the rotating support plate 102, a first connecting rod 105 disposed on the rotating support shell 103, a fixing rod 104 disposed on the first connecting rod 105, and a fixing sheet 104b disposed on the fixing rod 104;
[0039] A same steel rope 107 is connected between the two fixing plates 104 b , and a foot pedal 106 is arranged in the rotating support shell 103 , and the foot pedal 106 is engaged with the steel rope 107 during operation.
[0040] The steel ropes 107 exert tension on the two fixing plates 104 b , and the foot pedal 106 is clamped with the steel ropes 107 . The gravity of the foot pedal 106 not only exerts further tension on the fixing plates 104 b , but also the steel ropes 107 provide support for the foot pedal 106 .
[0041] In summary, by setting the foot pedal 106, the rotating support plate 102 and the foot pedal 106 are covered by the rotating support shell 103 before operation, and the bottom of the foot pedal 106 is in contact with the bottom of the rotating support plate 102. During operation, the worker rotates both rotating support shells 103 away from the connecting plate 101. The foot pedal 106 rotates under the action of gravity and engages with the steel rope 107, which prevents shorter workers from climbing up the portable operating frame with difficulty, reduces the time it takes for workers to climb up the operating frame, and improves the work efficiency of workers.
[0042] Example 2
[0043] Reference Figure 1 to Figure 5 This is the second embodiment of the utility model. Different from the previous embodiment, by providing a foot locking hole 106b-2, the worker's foot is inserted into the foot locking hole 106b-2 to limit the foot and prevent it from slipping, which further facilitates the worker's climbing.
[0044] Specifically, the connecting plate 101 includes two connecting blocks 101a, and the connecting blocks 101a are arranged at the bottom of the connecting plate 101. The sides of the two connecting blocks 101a close to each other are rotatably connected to the rotating support plate 102. During operation, the end of the rotating support plate 102 away from the rotating support shell 103 contacts the bottom of the connecting plate 101. The rotating support shell 103 includes two first bolts 103a and a limiting rod 103b.
[0045] The limiting rod 103b passes through the rotating support shell 103 and the rotating support plate 102. The limiting rod 103b is close to one end of the rotating support plate 102 away from the connecting plate 101. The outer walls of the rotating support plate 102 are in contact with the inner walls of the rotating support shell 103, and the rotating support plate 102 and the rotating support shell 103 are rotatably connected.
[0046] The distance from the end of the first bolt 103a to the end of the rotating support shell 103 close to the rotating support plate 102 is shorter than the distance from the end of the limiting rod 103b to the end of the rotating support shell 103 close to the rotating support plate 102. During operation, the two first bolts 103a both penetrate one side of the rotating support shell 103, extend and are inserted into the rotating support plate 102 for limiting.
[0047] The sides of the two first connecting rods 105 that are close to each other are rotatably connected to the outer wall of the rotating support shell 103. During operation, the end of the rotating support shell 103 away from the rotating support plate 102 contacts the fixing rod 104, and the inner walls of the rotating support shell 103 are rotatably connected to the outer walls of the foot pedal 106.
[0048] The foot pedal 106 includes a descending shell 106a, which is inclined downward in a direction parallel to one side of the steel rope 107. Two second connecting rods 106a-1 are arranged on the top of the descending shell 106a. The top height of the second connecting rod 106a-1 near the highest point of the top of the descending shell 106a is flush with the top height of the second connecting rod 106a-1 near the lowest point of the top of the descending shell 106a.
[0049] The downwardly inclined end of the landing shell 106a is provided with a first slide groove and a second slide groove 106a-2, the first slide groove and the second slide groove 106a-2 are connected, the distance from the top inner wall to the bottom inner wall of the first slide groove is shorter than the distance from the top inner wall to the bottom inner wall of the second slide groove 106a-2, and a slide plate 106b is slidably sleeved in the first slide groove.
[0050] An arc-shaped limit plate 106b-1 is provided on the side of the slide plate 106b away from the downward inclined end of the landing shell 106a, and the distance from the top height to the bottom height of the arc-shaped limit plate 106b-1 clamped with the steel rope 107 is greater than the distance from the top inner wall to the bottom inner wall of the first slide groove, and a locking foot hole 106b-2 is provided at the top of the slide plate 106b, and an anti-skid groove 106b-3 is provided at the top of the slide plate 106b, and the anti-skid groove 106b-3 is located between the downward inclined end of the slide plate 106b and the locking foot hole 106b-2.
[0051] Among them, the limiting rod 103b is close to the end of the rotating support plate 102 away from the connecting plate 101, so as to prevent the end of the rotating support plate 102 from colliding with the top inner wall of the rotating support shell 103 during rotation. The distance from the end of the first bolt 103a to the end of the rotating support shell 103 close to the rotating support plate 102 is shorter than the distance from the end of the limiting rod 103b to the end of the rotating support shell 103 close to the rotating support plate 102, which is conducive to the first bolt 103a to limit the rotating support shell 103 and the rotating support plate 102.
[0052] The top height of the second connecting rod 106a-1 near the highest point of the top of the landing shell 106a is flush with the top height of the second connecting rod 106a-1 near the lowest point of the top of the landing shell 106a, which is beneficial to the rotation of the second connecting rod 106a-1 in the rotating support shell 103. The landing shell 106a is tilted downward in a direction parallel to one side of the steel rope 107, which is beneficial for the worker to put his foot on the slide plate 106b. The distance from the top inner wall to the bottom inner wall of the first slide groove is shorter than the distance from the top inner wall to the bottom inner wall of the second slide groove 106a-2, which is beneficial for the first slide groove to limit the arc-shaped limit plate 106b-1. After the slide plate 106b slides out, the first slide groove limits the arc-shaped limit plate 106b-1 earlier than the arc-shaped limit plate 106b-1 is clamped to the steel rope 107. The anti-slip groove 106b-3 increases the friction when the worker's foot steps on the slide plate 106b.
[0053] In summary, by setting the foot locking hole 106b-2, when the foot pedal 106 rotates under the action of gravity, the slide plate 106b slides out first to make the first slide groove limit the arc-shaped limit plate 106b-1. When the foot pedal 106 rotates to a certain extent, the arc-shaped limit plate 106b-1 clamps the steel rope 107, and the worker's foot is inserted into the foot locking hole 106b-2 to limit the foot and prevent it from slipping, which further facilitates the worker's climbing.
[0054] Example 3
[0055] Reference Figure 1 , Figure 2 and Figure 7 , which is the third embodiment of the utility model, is different from the previous embodiment in that, by providing a telescopic rod 205, workers do not need to change other operating frames to continue working, thus saving costs.
[0056] Specifically, the lifting member 200 includes a first supporting plate 201, a first curved plate 201a arranged on the first supporting plate 201, a second curved plate 202a arranged on one side of the first curved plate 201a, and a second supporting plate 202 arranged on the second curved plate 202a. The second curved plate 202a is threadedly connected with a wing bolt 206 that passes through the first curved plate 201a, and a nut 206a is provided on the wing bolt 206. The ends of the first supporting plate 201 and the second supporting plate 202 that are away from each other are both rotatably connected with a U-shaped bracket 203.
[0057] A telescopic groove is provided at the bottom of the U-shaped bracket 203, and a telescopic rod 205 is slidably sleeved in the telescopic groove. The telescopic rod 205 is provided with a plurality of evenly arranged limiting holes 205a. The U-shaped bracket 203 is provided with a second bolt 203a that passes through the outer wall of the U-shaped bracket 203 and is threadedly connected to the limiting hole 205a.
[0058] The wing bolt 206 is convenient for workers to rotate, and the telescopic rod 205 is provided with a plurality of evenly arranged limiting holes 205a, which is helpful for workers to adjust the height.
[0059] In summary, by setting the telescopic rod 205, the worker limits the first bearing plate 201 and the second bearing plate 202 through the wing bolt 206 and the nut 206a, and then turns the U-shaped bracket 203 to a certain extent and limits it through other bolts. When it is necessary to adjust the height, the second bolt 203a is rotated to make the second bolt 203a threadedly rotated to the side away from the U-shaped bracket 203 to pull out the limiting hole 205a, and the telescopic rod 205 can slide freely in the U-shaped bracket 203. After adjusting to the required height, the second bolt 203a is inserted into another limiting hole 205a on the side close to the U-shaped bracket 203 and threadedly rotated to limit the telescopic rod 205. The worker does not need to change other operating frames to continue working, which saves costs.
[0060] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and ratio of various elements, and parameter values (e.g., temperature, pressure, etc.), installation arrangements, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present utility model. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the present invention is not limited to a specific embodiment, but extends to various modifications that still fall within the scope of the appended claims.
[0061] Additionally, in order to provide a concise description of example embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.
[0062] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.
[0063] It should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.
Claims
1. A stretching mechanism, characterized in that: include, The extension piece (100) comprises two connecting plates (101), a rotating support plate (102) disposed at the bottom of the connecting plates (101), a rotating support shell (103) disposed on the rotating support plate (102), a first connecting rod (105) disposed on the rotating support shell (103), a fixing rod (104) disposed on the first connecting rod (105), and a fixing sheet (104b) disposed on the fixing rod (104); A same steel rope (107) is connected between the two fixing plates (104b), and a foot pedal (106) is arranged inside the rotating support shell (103). During operation, the foot pedal (106) is clamped with the steel rope (107).
2. The stretching mechanism according to claim 1, characterized in that: The connecting plate (101) includes two connecting blocks (101a), and the connecting blocks (101a) are arranged at the bottom of the connecting plate (101). The two connecting blocks (101a) are rotatably connected to the rotating support plate (102) at their sides close to each other. During operation, the end of the rotating support plate (102) away from the rotating support shell (103) contacts the bottom of the connecting plate (101), and the rotating support shell (103) includes two first bolts (103a) and a limiting rod (103b).
3. The stretching mechanism according to claim 2, characterized in that: The limiting rod (103b) passes through the rotating support shell (103) and the rotating support plate (102); the limiting rod (103b) is close to one end of the rotating support plate (102) away from the connecting plate (101); the outer walls on both sides of the rotating support plate (102) are in contact with the inner walls on both sides of the rotating support shell (103); and the rotating support plate (102) and the rotating support shell (103) are rotatably connected.
4. The stretching mechanism according to claim 3, characterized in that: The distance between the end of the first bolt (103a) and the end of the rotating support shell (103) close to the rotating support plate (102) is shorter than the distance between the end of the limiting rod (103b) and the end of the rotating support shell (103) close to the rotating support plate (102). During operation, the two first bolts (103a) both penetrate one side of the rotating support shell (103) and extend and are inserted into the rotating support plate (102) for limiting.
5. The stretching mechanism according to claim 4, characterized in that: The sides of the two first connecting rods (105) that are close to each other are rotatably connected to the outer wall of the rotating support shell (103); during operation, the end of the rotating support shell (103) that is away from the rotating support plate (102) contacts the fixing rod (104); and the inner walls on both sides of the rotating support shell (103) are rotatably connected to the outer walls on both sides of the foot pedal (106).
6. The stretching mechanism according to claim 5, characterized in that: The foot pedal (106) includes a descending shell (106a), and the descending shell (106a) is inclined downward in a direction parallel to one side of the steel rope (107). Two second connecting rods (106a-1) are arranged on the top of the descending shell (106a), and the top height of the second connecting rod (106a-1) near the highest point of the top of the descending shell (106a) is flush with the top height of the second connecting rod (106a-1) near the lowest point of the top of the descending shell (106a).
7. The stretching mechanism according to claim 6, characterized in that: The descending end of the landing shell (106a) is provided with a first slide groove and a second slide groove (106a-2), the first slide groove and the second slide groove (106a-2) are connected, the distance from the top inner wall to the bottom inner wall of the first slide groove is shorter than the distance from the top inner wall to the bottom inner wall of the second slide groove (106a-2), and a slide plate (106b) is slidably sleeved in the first slide groove.
8. The stretching mechanism according to claim 7, characterized in that: An arc-shaped limit plate (106b-1) is provided on one side of the slide plate (106b) away from the downwardly inclined end of the landing shell (106a); the distance from the top height to the bottom height of the arc-shaped limit plate (106b-1) clamped with the steel rope (107) is greater than the distance from the top inner wall to the bottom inner wall of the first slide groove; a locking foot hole (106b-2) is provided on the top of the slide plate (106b); an anti-skid groove (106b-3) is provided on the top of the slide plate (106b); and the anti-skid groove (106b-3) is located between the downwardly inclined end of the slide plate (106b) and the locking foot hole (106b-2).
9. An operating frame height adjustment device, characterized in that: comprising the extension mechanism according to any one of claims 1 to 8; and The lifting member (200) comprises a first supporting plate (201), a first curved plate (201a) arranged on the first supporting plate (201), a second curved plate (202a) arranged on one side of the first curved plate (201a), and a second supporting plate (202) arranged on the second curved plate (202a), wherein the second curved plate (202a) is threadedly connected with a wing bolt (206) penetrating the first curved plate (201a), and a nut (206a) is arranged on the wing bolt (206), and the ends of the first supporting plate (201) and the second supporting plate (202) which are away from each other are both rotatably connected with a U-shaped bracket (203).
10. The operating frame height adjustment device according to claim 9, characterized in that: The bottom of the U-shaped bracket (203) is provided with a telescopic groove, a telescopic rod (205) is slidably sleeved in the telescopic groove, a plurality of evenly arranged limiting holes (205a) are provided on the telescopic rod (205), and the U-shaped bracket (203) is provided with a second bolt (203a) penetrating the outer wall of the U-shaped bracket (203) and threadedly connected to the limiting hole (205a).