CN220618345U - Arm support structure - Google Patents

Abstract

The utility model belongs to the technical field of telescopic arms and discloses a boom structure, which includes a first-level arm tube, a second-level arm tube, and an N-level arm tube that are nested in sequence. It also includes a driving cylinder and a pulley mechanism. The driving cylinder The fixed end is located in the primary arm tube and connected to the primary arm tube, and the telescopic end is located in the secondary arm tube and connected to the secondary arm tube; the secondary arm tube to the N-1 level arm tube are equipped with two pulleys, located at One of the two pulleys on the K-level boom is surrounded by an outrigger connector, and the other is surrounded by a telescopic arm connector. The two ends of the outrigger connector extend toward the side of the primary boom and are connected to the K‑1 arm respectively. The level 1 arm tube and the K+1 level arm tube are connected. The two ends of the shrink arm connector extend toward the side of the N level arm tube and are connected to the K‑1 level arm tube and the K+1 level arm tube respectively; K is a natural number and 2 ≤K≤N; For the secondary arm tube, the pulley corresponding to the outrigger connecting piece is located in the secondary arm tube and connected to the telescopic end. The arm structure provided by the utility model has a simple structure and a more reasonable spatial layout.

Description

A kind of arm structure

Technical field

The utility model relates to the technical field of telescopic arms, and in particular to an arm frame structure.

Background technique

An aerial work platform is a large-scale engineering machinery and equipment used to transport workers and work equipment to a designated height for operations. The boom structure of the aerial work platform includes a plurality of boom tubes that are nested in sequence. The arm tube located at the farthest end of the chassis of the aerial work platform is connected to the chassis, and the arm tube located at the farthest end of the chassis is connected to the workbench.

In the existing technology, some boom structures use a combination of a driving cylinder and a pulley mechanism to control expansion and contraction. Specifically, for example, the patent document with publication number CN209308712U discloses a boom telescopic mechanism. According to the disclosure, in a plurality of boom tubes nested in sequence, the first arm close to the chassis is connected to the adjacent third arm. The expansion and contraction between the two arms is controlled by a driving cylinder, and the expansion and contraction between the second arm and the third arm, between the third arm and the fourth arm... and between the N-1th arm and the Nth arm are all controlled by a pulley mechanism. The above-mentioned patent documents also have some shortcomings. Specifically, the driving oil cylinder is usually arranged outside the first arm, which directly exposes the driving oil cylinder to the external environment, increases the risk of damage and corrosion of the driving oil cylinder, and makes it difficult to protect. In addition, multiple pulleys are provided at the upper and lower ends of the boom, which further increases the external dimensions of the boom structure and makes the overall boom structure more complex.

Utility model content

The purpose of this utility model is to provide a boom structure that is simple in structure, can effectively enhance the protection of the driving cylinder, and reasonably optimizes the layout structure of the pulleys.

To achieve this purpose, the utility model adopts the following technical solutions:

A boom structure includes a first-level arm tube, a second-level arm tube, and N-level arm tubes that are nested in sequence. N is a natural number and N≥3. The boom structure also includes:

The driving cylinder includes a fixed end and a telescopic end. The fixed end is located in the primary arm tube and connected to the primary arm tube. The telescopic end is located in the secondary arm tube and connected to the secondary arm. cylinder;

The pulley mechanism includes a pulley, an extension arm connector and a retraction arm connector. The secondary arm tube to the N-1 level arm tube are each provided with two pulleys, and the two pulleys located on the K-level arm tube One of the pulleys is around the outrigger connecting piece, and the other is around the retracting arm connecting piece. Both ends of the outstretching arm connecting piece extend toward the retraction direction of the boom structure and are connected with each other respectively. The K-1 level arm tube and the K+1 level arm tube are connected. The two ends of the retractable arm connector extend toward the extension direction of the boom structure and are respectively connected with the K-1 level arm tube and the K+1 level arm. Cylinder connection; K is a natural number and 2≤K≤N-1;

For the secondary arm tube, the pulley corresponding to the arm connecting piece is provided in the secondary arm tube and connected to the telescopic end.

Preferably, it also includes an adjustment block, which is hingedly arranged on the primary arm tube around the first direction. The adjustment block is provided with fixing holes on both sides of the hinged position and is located on the secondary arm. There are two outrigger connectors on the barrel. The first ends of the two outrigger connectors are fixed on the three-stage arm barrel, and the second ends are fixed and threaded respectively after winding the pulley. on the two fixing holes;

The first direction is perpendicular to the telescopic direction of the boom structure and the axial direction of the pulley.

Preferably, the adjustment block is provided with two guide cylinders coaxially communicating with the fixing holes.

Preferably, a bracket is fixedly provided on the first-stage arm tube, and the adjustment block is hingedly arranged on the bracket through a hinge shaft.

Preferably, the inner peripheral wall of the fixing hole is provided with internal threads, and the outer peripheral walls of the second ends of the two arm connectors on the secondary arm tube are provided with external threads that are matched with the internal threads. thread.

Preferably, it also includes a position sensor and an alarm device. The position sensor is provided on the bracket and is used to detect the position of the adjustment block. The alarm device is suitable for detecting the position of the adjustment block when the position sensor detects the position of the adjustment block. Alarm when the position change exceeds the threshold.

Preferably, the K-level arm is fixedly provided with a pulley pin corresponding to the pulley. The pulley pin includes a primary shaft portion and a secondary shaft extending from the end of the primary shaft portion. part, the primary shaft part is fixed on the K-level arm tube, the shaft diameter of the secondary shaft part is smaller than the shaft diameter of the primary shaft part, and the pulley is sleeved on the secondary shaft part superior.

Preferably, a baffle is provided on a side of the secondary shaft part away from the primary shaft part, and the primary shaft part and the secondary shaft part are connected by a stepped end surface, and the stepped end surface is connected to The baffles can jointly limit the movement of the pulley in its axial direction.

Preferably, a screw connector is provided between the pulley pin and the baffle, and a first through hole is provided on the pulley pin that penetrates the primary shaft part and the secondary shaft part. The baffle is correspondingly provided with a second through hole, and the second through hole is provided with an internal thread that is matched and connected to the screw connector. The screw connector passes through the first through hole and is screwed to the second through hole. .

Preferably, the secondary shaft part is provided with a shaft sleeve, the pulley is rotatably sleeved on the shaft sleeve, and the shaft sleeve is provided with wear-resistant sleeves on both sides opposite to itself in the axial direction. parts, and the wear-resistant parts are sleeved on the secondary shaft part.

Beneficial effects:

In the boom structure provided by the utility model, the fixed end is located in the primary arm tube and connected to the primary arm tube, and the telescopic end is located in the secondary arm tube and connected to the secondary arm tube. The entire structure equivalent to the driving cylinder is located on the boom frame. Inside the structure, the drive cylinder can be better protected to avoid damage and corrosion of the drive cylinder.

In addition, for the secondary boom, the pulley corresponding to the outrigger connector is located in the secondary boom and connected to the telescopic end, which can reduce the number of pulleys located on the side ends of the boom and ensure the reliable operation of the entire boom structure. Under the premise of further reducing the overall external size of the boom structure, the internal space of the boom tube can be effectively utilized, and the layout structure of the pulleys can be reasonably optimized.

Description of the drawings

Figure 1 is a schematic diagram of the boom structure provided by the utility model;

Figure 2 is a cross-sectional view of part of the boom structure provided by the utility model;

Figure 3 is a partially enlarged schematic diagram of the utility model at position A in Figure 2;

Figure 4 is a schematic structural diagram of the adjusting block provided by the utility model;

Figure 5 is a cross-sectional view of another part of the boom structure provided by the utility model;

Figure 6 is a schematic structural diagram of the pulley pin provided by the present utility model.

In the picture:

11. First-level arm; 12. Second-level arm; 13. Third-level arm; 14. Fourth-level arm;

2. Driving cylinder; 21. Fixed end; 22. Telescopic end;

31. Pulley; 32. Extending arm connecting piece; 33. Retracting arm connecting piece;

41. Adjustment block; 411. Fixed hole; 412. Guide cylinder; 42. Bracket; 43. Hinge shaft;

5. Position sensor;

61. Pulley pin; 6101. First hole; 611. Primary shaft part; 612. Secondary shaft part; 613. Step end face; 62. Baffle; 621. Second hole; 63. Screw joint; 64. Bushing; 65. Wear-resistant parts.

Detailed ways

The utility model will be further described in detail below in conjunction with the accompanying drawings and examples. It can be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for convenience of description, only some but not all structures related to the present utility model are shown in the drawings.

In the description of the present utility model, unless otherwise explicitly stipulated and limited, the terms "connected", "connected" and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or a detachable connection. Integration; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interaction between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

In the present invention, unless otherwise expressly stipulated and limited, the first feature being "above" or "below" the second feature may include direct contact between the first and second features, or may include the first and second features being in direct contact with each other. Features are not in direct contact but through other features between them. Furthermore, the terms "above", "above" and "above" a first feature on a second feature include the first feature being directly above and diagonally above the second feature, or simply mean that the first feature is higher in level than the second feature. “Below”, “under” and “under” the first feature is the second feature includes the first feature being directly below and diagonally below the second feature, or simply means that the first feature is less horizontally than the second feature.

In the description of this embodiment, the terms "upper", "lower", "right", etc. are based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplified operation, rather than instructions. Or it is implied that the device or component mentioned must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and have no special meaning.

This embodiment provides an arm structure. Referring to Figures 1 to 5, the boom structure includes primary booms 11, secondary booms 12... N-level booms, which are nested in sequence. N is a natural number and N≥3. The boom structure also includes a drive. Cylinder 2 and pulley mechanism. The driving cylinder 2 includes a fixed end 21 and a telescopic end 22. The fixed end 21 is located in the primary arm tube 11 and connected to the primary arm tube 11. The telescopic end 22 is located in the secondary arm tube 12 and connected to the secondary arm tube 12. The pulley mechanism includes a pulley 31, an extension arm connector 32 and a retraction arm connector 33. The secondary arm tube 12 to the N-1 level arm tube are each provided with two pulleys 31, which are located in the two pulleys 31 on the K-level arm tube. One of the arms is surrounded by an outrigger connector 32, and the other is surrounded by a retractable arm connector 33. The two ends of the outrigger connector 32 extend toward the retraction direction of the boom structure and are respectively connected with the K-1 level arm tube and K The +1 level arm tube is connected. The two ends of the retractable arm connector 33 extend towards the extension direction of the boom structure and are connected to the K-1 level arm tube and the K+1 level arm tube respectively. K is a natural number and 2≤K≤ N-1. For the secondary arm tube 12, the pulley 31 corresponding to the boom connecting piece 32 is provided in the secondary arm tube 12 and connected to the telescopic end 22.

In this embodiment, the fixed end 21 is located in the primary arm tube 11 and connected to the primary arm tube 11 , and the telescopic end 22 is located in the secondary arm tube 12 and connected to the secondary arm tube 12 , which is equivalent to the overall structure of the driving cylinder 2 They are all located inside the boom structure, which can better protect the driving cylinder 2 and avoid damage and corrosion of the driving cylinder 2.

In addition, for the secondary boom 12, the pulley 31 corresponding to the boom connector 32 is provided in the secondary boom 12 and connected to the telescopic end 22, which can reduce the number of pulleys provided on the side ends of the boom while ensuring that the entire On the premise of reliable operation of the boom structure, the overall external dimensions of the boom structure can be further reduced, the internal space of the boom structure can be effectively utilized, and the layout structure of the pulleys 31 can be reasonably optimized.

In this embodiment, the lower end side walls of the first-level arm tube 11 to the N-level arm tube are all configured to be arc-shaped. Such an arrangement can further improve the bending modulus of the overall boom structure, making it better suitable for high-meter aerial work platforms.

Specifically, the arc shape of the lower end side wall of the first-level arm tube 11 to the N-level arm tube can be a smooth arc or a polygonal arc, which is not limited here.

As an optional embodiment, in this embodiment, the number of arm tubes is set to four, namely the first-level arm tube 11, the second-level arm tube 12, the third-level arm tube 13, and the fourth-level arm tube 14, as shown in Figures 1 to What is shown in Figure 5 is also the situation when the number of arm tubes is set to four.

Specifically, two pulleys 31 corresponding to the secondary arm tube 12 are both arranged in the secondary arm tube 12, one of the secondary arm tubes 12 is connected to the telescopic end of the driving cylinder 2, and the other pulley 31 is connected to the secondary arm tube 12. on the inner wall of the arm tube 12. The two pulleys 31 corresponding to the three-stage arm tube 13 are both arranged on the inner wall of the three-stage arm tube 13 .

In this embodiment, both the extending arm connecting member 32 and the retracting arm connecting member 33 can be configured as ropes or chains.

Specifically, when the control boom structure extends at a speed V1, the telescopic end 22 of the control driving cylinder 2 extends relative to the fixed end 21 at a speed V1, so that the secondary arm 12 extends relative to the primary arm 11. The outrigger connector 32 of the secondary boom 12 and the pulley 31 around it together form a movable pulley structure. Driven by the outrigger connector 32 around the pulley 31 on the telescopic end 22, the third-level boom 13 is driven relative to the secondary boom 13. The stage boom 12 extends at a speed V2, where V2=2V1. The outrigger connector 32 of the third-stage boom tube 13 and the pulley 31 around it together form a movable pulley structure. Driven by the outrigger connector 32 around the pulley 31 on the third-stage boom tube 13, the fourth-stage boom tube 14 is driven. The relative three-stage arm tube 13 extends outward at a speed V3, where V3=2V2. When the boom structure is required to retract at a speed V1', the telescopic end 22 of the driving cylinder 2 is controlled to retract relative to the fixed end 21 at a speed V1', so that the secondary boom 12 retracts relative to the primary boom 11. The retractable arm connector 33 of the secondary boom 12 and the pulley 31 around it together form a movable pulley structure. Driven by the retractable arm connector 33 around the pulley 31 on the telescopic end 22, the third-level boom 13 is driven relative to the secondary boom 13. The stage boom 12 retracts at a speed V2', where V2'=2V1'. The retractable arm connector 33 of the third-stage boom 13 and the pulley 31 around it together form a movable pulley structure. The fourth-stage boom 14 is driven by the retractable arm connector 33 around the pulley 31 on the third-stage boom 13. The relative three-stage boom retracts at 13 speed V3', where V3'=2V2'.

In this embodiment, the boom structure also includes an adjustment block 41. The adjustment block 41 is hingedly provided on the primary arm tube 11 around the first direction. The adjustment block 41 is provided with fixing holes 411 on both sides of the hinged position, and is located on the second level. There are two outrigger connectors 32 on the three-stage arm tube 12. The first ends of the two outrigger connectors 32 are fixed on the three-stage arm tube 13, and the second ends are respectively fixed through the pulleys 31. Provided in two fixing holes 411; the first direction is perpendicular to the telescopic direction of the arm structure and the axial direction of the pulley 31. Specifically, when pre-tightening the outrigger connector 32, if the tensile forces of the two outrigger connectors 32 are different, due to the tension difference, the adjustment block 41 will rotate around the hinge point relative to the primary arm barrel 11 to adjust the outrigger automatically. The tensile force of the connecting member 32 is equal to the tensile force of the two outrigger connecting members 32 .

Specifically, the adjustment block 41 is provided with two guide tubes 412 coaxially communicating with the fixing holes 411 . The guide tube 412 is provided to guide the outrigger connector 32 passing through the fixing hole 411 to facilitate the insertion of the outrigger connector 32.

Specifically, a bracket 42 is fixedly provided on the primary arm tube 11 , and the adjustment block 41 is hingedly mounted on the bracket 42 through a hinge shaft 43 . Optionally, the bracket 42 is provided with a connection hole (not shown), the adjustment block 41 is provided with a hinge hole (not shown), the hinge shaft 43 is penetrated through the connection hole and the hinge hole, and the hinge shaft 43 is rotationally connected through the hinge hole. to the adjustment block 41.

Specifically, the inner peripheral wall of the fixing hole 411 is provided with internal threads, and the outer peripheral walls of the second ends of the two arm connectors 32 on the secondary arm barrel 12 are provided with external threads that match the internal threads. The above arrangement allows the arm connecting piece 32 on the secondary arm tube 12 to be reliably fixed to the fixing hole 411 after passing through the corresponding fixing hole 411 . Furthermore, by twisting the outrigger connector 32, the penetration length of the outrigger connector 32 relative to the fixing hole 411 through which it is inserted can be controlled, thereby adjusting the pre-tightening force of the corresponding outrigger connector 32.

Specifically, it also includes a position sensor 5 and an alarm device. The position sensor 5 is provided on the bracket 42 and is used to detect the position of the adjustment block 41. The alarm device is adapted to alarm when the position sensor 5 detects that the position change of the adjustment block 41 exceeds a threshold. In this embodiment, the boom structure is provided with a control module, and the position sensor 5 can detect the position of the adjustment block 41 in real time and send a position signal to the control module. When the two arm connectors 32 installed on the adjustment block 41 are operating normally, the adjustment block 41 may deflect slightly due to the pulling force of the arm connector 32 on one side, but the deflections are still within the threshold range. When one of the two cantilever connecting parts 32 breaks unexpectedly, the adjusting block 41 will be greatly pulled by the other cantilever connecting part 32 and produce a large deflection. At this time, the position of the adjusting block 41 will change greatly. exceeds the threshold range. At this time, the position sensor 45 detects that the adjustment block 41 exceeds the threshold and sends a signal to the control module. After receiving the signal, the control module controls the alarm module to alarm in time, thereby providing timely feedback to the relevant operators to perform maintenance on the aerial work platform. Timely maintenance.

In this embodiment, the position sensor 5 can be configured as a travel switch.

Optionally, the alarm module can be configured as an alarm etc. and/or a buzzer.

In this embodiment, as shown in FIG. 6 , the K-level arm is fixedly provided with a pulley pin 61 corresponding to the pulley 31 . The pulley pin 61 includes a primary shaft portion 611 and an end extending from the primary shaft portion 611 . The secondary shaft portion 612 at the bottom, the primary shaft portion 611 is fixed on the K-level arm tube, the shaft diameter of the secondary shaft portion 612 is smaller than the shaft diameter of the primary shaft portion 611, and the pulley 31 is sleeved on the secondary shaft portion 612 . The pulley pin 61 provides a reliable assembly space for the pulley 31. By providing the pulley pin 61, the pulley 31 can be reliably and effectively installed on the corresponding arm.

Specifically, a baffle 62 is provided on the side of the secondary shaft part 612 away from the primary shaft part 611. The primary shaft part 611 and the secondary shaft part 612 are connected through a stepped end surface 613. The stepped end surface 613 and the baffle 62 can The common limiting pulley 31 moves in its own axial direction. Specifically, through the cooperation of the stepped end surface 613 and the baffle 62, the two ends of the pulley 31 can be reliably limited, so that the pulley 31 can be reliably and stably installed on the pulley pin 61 to prevent the pulley 31 from accidentally falling off.

Further, a screw connector 63 is provided between the pulley pin 61 and the baffle 62. The pulley pin 61 is provided with a first through hole 6101 that penetrates the primary shaft part 611 and the secondary shaft part 612, and the baffle 62 is opened correspondingly. There is a second through hole 621, and the second through hole 621 is provided with an internal thread that is matched with the screw connector 63. The screw connector 63 passes through the first through hole 6101 and is screwed to the second through hole 621, so that the pulley pin 61 and The baffle 62 is reliably fixed.

Further, the secondary shaft portion 612 is provided with a sleeve 64, and the pulley 31 is rotatably sleeved on the sleeve 64. The sleeve 64 is provided with wear-resistant parts 65 on both sides opposite to itself in the axial direction, and is resistant to wear. The grinding piece 65 is sleeved on the secondary shaft portion 612 . The pulley 31 is rotatably connected to the pulley pin 61 through the sleeve 64, and the provision of the wear-resistant part 65 can prevent friction and heat between the pulley 31 and the pulley pin 61 and between the pulley 31 and the baffle 62 from damaging the sleeve 64.

Obviously, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those of ordinary skill in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of the present invention. An exhaustive list of all implementations is neither necessary nor possible. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model shall be included in the protection scope of the claims of the present utility model.

Claims (10)

1. A boom structure, including a first-level arm tube (11), a second-level arm tube (12)...N-level arm tubes, which are nested in sequence. N is a natural number and N≥3. It is characterized in that: The boom structure also includes: The driving cylinder (2) includes a fixed end (21) and a telescopic end (22). The fixed end (21) is located in the first-level arm tube (11) and connected to the first-level arm tube (11). The telescopic end (22) is located in the secondary arm tube (12) and connected to the secondary arm tube (12); The pulley mechanism includes a pulley (31), an extending arm connecting piece (32) and a retracting arm connecting piece (33). The secondary arm tube (12) to the N-1 level arm tube are each provided with two Pulley (31), one of the two pulleys (31) located on the K-level arm tube is around the extending arm connector (32), and the other is around the retracting arm connector (33) , the two ends of the extending arm connector (32) extend toward the retraction direction of the boom structure and are connected to the K-1 level arm tube and the K+1 level arm tube respectively, and the retracting arm connector (33 ) extends toward the extension direction of the boom structure and is connected to the K-1 level arm tube and the K+1 level arm tube respectively; K is a natural number and 2≤K≤N-1; For the secondary arm tube (12), the pulley (31) corresponding to the arm connecting piece (32) is provided in the secondary arm tube (12) and connected to the telescopic end ( 22) on. 2. The boom structure according to claim 1, further comprising an adjustment block (41), the adjustment block (41) being hingedly arranged on the primary arm tube (11) around the first direction, The adjustment block (41) is provided with fixing holes (411) on both sides of the hinged position, and there are two outrigger connecting pieces (32) located on the secondary arm tube (12). The first ends of the arm connectors (32) are fixed on the three-stage arm tube (13), and the second ends are fixed on the two fixing holes after winding the pulley (31). (411); The first direction is perpendicular to the telescopic direction of the boom structure and the axial direction of the pulley (31). 3. The boom structure according to claim 2, characterized in that the adjustment block (41) is provided with two guide tubes (412) coaxially connected with the fixing hole (411). 4. The boom structure according to claim 2, characterized in that a bracket (42) is fixedly provided on the first-level boom tube (11), and the adjustment block (41) is hingedly arranged through a hinge shaft (43). on the bracket (42). 5. The boom structure according to claim 2, characterized in that the inner peripheral wall of the fixing hole (411) is provided with internal threads, and the two outriggers on the secondary arm tube (12) are connected The outer peripheral wall of the second end of the component (32) is provided with external threads that are matched with the internal threads. 6. The boom structure according to claim 4, further comprising a position sensor (5) and an alarm device, the position sensor (5) being provided on the bracket (42) and used to detect the adjustment. The position of the block (41), the alarm device is adapted to alarm when the position sensor (5) detects that the position change of the adjustment block (41) exceeds a threshold. 7. The boom structure according to claim 1, characterized in that a pulley pin (61) corresponding to the pulley (31) is fixedly provided on the K-level arm tube, and the pulley pin (61) ) includes a primary shaft portion (611) and a secondary shaft portion (612) extending from the end of the primary shaft portion (611). The primary shaft portion (611) is fixed to the K-level arm tube. On the other hand, the shaft diameter of the secondary shaft part (612) is smaller than the shaft diameter of the primary shaft part (611), and the pulley (31) is sleeved on the secondary shaft part (612). 8. The boom structure according to claim 7, characterized in that a baffle (62) is provided on the side of the secondary shaft part (612) away from the primary shaft part (611), and the first shaft part (612) is provided with a baffle (62). The step shaft part (611) and the secondary shaft part (612) are connected through a stepped end face (613). The stepped end face (613) and the baffle (62) can jointly limit the pulley (31). ) along its own axial direction. 9. The boom structure according to claim 8, characterized in that a screw connector (63) is provided between the pulley pin (61) and the baffle (62), and the pulley pin (63) 61) is provided with a first through hole (6101) penetrating the primary shaft part (611) and the secondary shaft part (612), and the baffle (62) is provided with a corresponding second through hole (621), The second through hole (621) is provided with an internal thread that is matched with the screw connector (63), and the screw connector (63) passes through the first through hole (6101) and the second through hole. (621) Screw connection. 10. The boom structure according to claim 8, characterized in that the secondary shaft part (612) is provided with a sleeve (64), and the pulley (31) is rotatably sleeved on the said shaft. On the shaft sleeve (64), wear-resistant parts (65) are provided on both sides of the shaft sleeve (64) opposite to the axial direction of the shaft sleeve (64). The wear-resistant parts (65) are sleeved on the secondary shaft part. (612) on.