Telescopic arm unit and hoisting machinery

Abstract

The utility model belongs to the technical field of engineering machinery and provides a telescopic arm unit and hoisting machinery, the telescopic arm unit comprises an outer arm section, an inner arm section and a shoulder sliding block, the shoulder of the outer arm section is provided with a shoulder outer inclined wall, the inner arm section is arranged in the outer arm section, the shoulder is provided with a shoulder inner inclined wall, the shoulder inner inclined wall and the shoulder outer inclined wall are aligned in the radial direction, and the shoulder sliding block is arranged on the shoulder sliding block. The shoulder sliding block is fixedly installed on one of the shoulder outer inclined wall and the shoulder inner inclined wall and attached to the shoulder outer inclined wall and the shoulder inner inclined wall. Under the condition that special materials are not adopted, the shoulder sliding block is arranged to be attached to the shoulder wall of the outer arm section and the shoulder wall of the inner arm section, the contact area of the shoulder sliding block and the arm sections is increased, the stress of the outer arm section is evenly distributed on the shoulder sliding block, and therefore the probability that the shoulder sliding block is pressed to deform or be crushed is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of construction machinery, and particularly relates to a telescopic boom unit and a lifting machine. Background Art

[0002] At present, for the existing folding boom truck-mounted cranes at home and abroad, the sliders between the boom sections are generally made of ordinary materials. As people's requirements for the lifting performance of truck-mounted cranes are getting higher and higher, the sliders made of ordinary materials often deform and break. To solve this problem, some existing technologies use strengthened sliders or composite sliders made of special materials, but the prices of such sliders are relatively high and the installation difficulty is great. Summary of the Utility Model

[0003] In view of the above defects or deficiencies, the utility model provides a telescopic boom unit and a lifting machine, aiming to solve the technical problem that the existing sliders made of ordinary materials are difficult to meet the requirements of high lifting.

[0004] To achieve the above object, the utility model provides a telescopic boom unit, which includes an outer boom section, an inner boom section and a shoulder slider. The shoulder of the outer boom section is provided with a shoulder outer inclined wall, the inner boom section is arranged inside the outer boom section and the shoulder is provided with a shoulder inner inclined wall. The shoulder inner inclined wall is radially aligned with the shoulder outer inclined wall. The shoulder slider is fixedly installed on one of the shoulder outer inclined wall and the shoulder inner inclined wall and is respectively attached to the shoulder outer inclined wall and the shoulder inner inclined wall.

[0005] In an embodiment of the utility model, a limit installation component is arranged on the shoulder inner inclined wall, and the shoulder slider is fixedly installed on the shoulder inner inclined wall through the limit installation component.

[0006] In an embodiment of the utility model, the limit installation component includes a limit insertion column arranged on the shoulder inner inclined wall, and the shoulder slider is provided with a limit insertion hole for plugging and matching with the insertion column.

[0007] In an embodiment of the utility model, the limit installation component further includes a connecting piece for connecting the shoulder slider and the shoulder inner inclined wall.

[0008] In an embodiment of the utility model, threaded connection holes are respectively arranged on the shoulder slider and the shoulder inner inclined wall. The threaded connection hole on the shoulder slider is a counterbore hole, and the connecting piece is a threaded connecting piece.

[0009] In an embodiment of the utility model, the shoulder outer inclined wall includes a first outer shoulder wall and a second outer shoulder wall arranged adjacent to each other. The side of the shoulder slider facing the shoulder outer inclined wall is respectively provided with a first fitting surface and a second fitting surface for fitting with the first outer shoulder wall and the second outer shoulder wall. The first fitting surface and the second fitting surface are respectively parallel to and aligned with the first outer shoulder wall and the second outer shoulder wall.

[0010] In an embodiment of the present utility model, an arc transition edge is provided between the first outer shoulder wall and the second outer shoulder wall, and the shoulder slider further includes an arc fitting surface located between the first fitting surface and the second fitting surface.

[0011] In an embodiment of the present utility model, both the outer arm section and the inner arm section are polygonal tubular arms, and the number of sides of the inner arm section is less than that of the outer arm section.

[0012] In an embodiment of the present utility model, the outer arm section is a decagonal tubular arm, and the inner arm section is an octagonal tubular arm or a hexagonal tubular arm; or the outer arm section is an octagonal tubular arm, and the inner arm section is a hexagonal tubular arm.

[0013] To achieve the above object, the present utility model further provides a hoisting machine, wherein the hoisting machine includes the telescopic arm unit described above.

[0014] Through the above technical solutions, the telescopic arm unit provided by the embodiments of the present utility model has the following beneficial effects:

[0015] The shoulder slider is installed on one of the outer arm section and the inner arm section and is in sliding contact with the other. Through the shoulder slider, the outer arm section and the inner arm section can be spaced apart to ensure normal sliding between the inner arm section and the outer arm section. To solve the problem that the shoulder slider made of ordinary material is prone to deformation or breakage, the present utility model specifically optimizes the shape of the shoulder slider so that the shoulder slider is transitionally arranged between the outer arm section and the inner arm section. By setting the shoulder slider to be respectively in contact with the shoulder wall of the outer arm section and the shoulder wall of the inner arm section, without using special materials, by increasing the contact area between the shoulder slider and the arm section, the stress of the outer arm section is evenly distributed on the shoulder slider, thereby reducing the probability of the shoulder slider being deformed or crushed by pressure.

[0016] Other features and advantages of the present utility model will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings are used to provide an understanding of the present utility model and constitute a part of the specification, and are used together with the following specific implementation to explain the present utility model, but do not constitute a limitation to the present utility model. In the drawings:

[0018] Figure 1 is a schematic structural diagram of the telescopic arm unit according to an embodiment of the present utility model;

[0019] Figure 2 is a schematic structural diagram of the shoulder slider according to an embodiment of the present utility model;

[0020] Figure 3 is a schematic structural diagram of the inner arm section according to an embodiment of the present utility model;

[0021] Figure 4 It is a schematic cross-sectional shape diagram of the outer arm section in the embodiment of the present utility model;

[0022] Figure 5 It is a schematic cross-sectional shape diagram of the inner arm section in the embodiment of the present utility model.

[0023] Description of the reference numerals

[0024] 1. Outer arm section; 11. Outer inclined shoulder wall; 111. First outer shoulder wall; 112. Second outer shoulder wall; 113. Arc transition edge; 2. Inner arm section; 21. First inner shoulder wall; 31. Shoulder slider; 311. First fitting surface; 312. Second fitting surface; 313. Arc fitting surface; 314. Third fitting surface; 315. Limit insertion hole; 316. Threaded connection hole; 4. Limit installation component; 41. Limit insertion post. Detailed implementation manners

[0025] The following will describe in detail the specific embodiments of the present utility model with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present utility model, and are not used to limit the present utility model.

[0026] Next, the telescopic arm unit of the present utility model will be described with reference to the accompanying drawings.

[0027] After the outer arm section 1 and the outer arm section 1 are assembled, affected by the cross-sectional shape, without using special materials, if the shoulder slider 31 uses the existing sliders of ordinary materials, the slider is very likely to be deformed or broken due to excessive force or uneven force. Therefore, the structure of the slider needs to be specially designed.

[0028] For this reason, the present utility model provides a telescopic arm unit, as Figure 1 、 Figure 2 and Figure 3 shown, the telescopic arm unit includes:

[0029] An outer arm section 1, with an outer inclined shoulder wall 11 provided at the shoulder;

[0030] An inner arm section 2, arranged inside the outer arm section 1 and having an inner inclined shoulder wall at the shoulder, and the inner inclined shoulder wall at the shoulder is radially aligned with the outer inclined shoulder wall 11; and

[0031] A shoulder slider 31, fixedly installed on one of the outer inclined shoulder wall 11 and the inner inclined shoulder wall at the shoulder and respectively fitting with the outer inclined shoulder wall 11 and the inner inclined shoulder wall at the shoulder.

[0032] The shoulder slider 31 is mounted on one of the outer arm section 1 and the inner arm section 2 and is in sliding contact with the other. Through the shoulder slider 31, the outer arm section 1 and the inner arm section 2 can be spaced apart to ensure normal sliding between the inner arm section 2 and the outer arm section 1. To solve the problem that the shoulder slider 31 made of ordinary materials is prone to deformation or breakage, the present utility model specifically optimizes the shape of the shoulder slider 31 so that the shoulder slider 31 is transitionally arranged between the outer arm section 1 and the inner arm section 2. By setting the shoulder slider 31 to be respectively in contact with the shoulder wall of the outer arm section 1 and the shoulder wall of the inner arm section 2, without using special materials, by increasing the contact area between the shoulder slider 31 and the arm section, the stress of the outer arm section 1 is evenly distributed on the shoulder slider 31, thereby reducing the probability of the shoulder slider 31 being deformed or crushed by pressure.

[0033] In an embodiment of the present utility model, the shoulder slider 31 can be mounted on the inner side of the outer arm section 1 and is arranged to be in sliding contact with the outer surface of the inner arm section 2, or the shoulder slider 31 can be mounted on the outer side of the inner arm section 2 and is arranged to be in sliding contact with the inner surface of the outer arm section 1. Among them, for the convenience of installation, it is preferable to mount the shoulder slider 31 on the outer side of the inner arm section 2, and this installation method can avoid the shoulder slider 31 falling off during installation.

[0034] Taking the preferred solution as an example, a limit mounting component 4 is provided on the inner inclined shoulder wall. The shoulder slider 31 is fixedly mounted on the inner inclined shoulder wall through the limit mounting component 4.

[0035] Specifically, as Figure 1 、 Figure 2 and Figure 3 shown, the limit mounting component 4 can include a limit insertion post 41 provided on the first inner shoulder wall 21. The limit insertion post 41 can be mounted on the first inner shoulder wall 21 by welding or other means. In order to cooperate with the limit insertion post 41, a limit insertion hole 315 for inserting and cooperating with the limit insertion post 41 needs to be provided on the side (the third fitting surface 314) of the shoulder slider 31 facing the first inner shoulder wall 21. Through the insertion and cooperation of the shoulder slider 31 and the limit insertion post 41, the limit of the shoulder slider in the X-axis and Y-axis directions can be realized. And in order to realize the installation and fixation of the shoulder slider 31 and the Z-axis limit, a connecting piece can be used to penetrate the shoulder slider 31 and the first inner shoulder wall 21. Or the shoulder slider 31 can be adhered to the first inner shoulder wall 21 with glue.

[0036] As Figure 1 and Figure 3 shown, in an embodiment of the present utility model, first inner shoulder walls 21 are provided on both sides of the inner arm section 2, and a plurality of limit insertion posts 41 can be provided on each first inner shoulder wall 21. Through the insertion and cooperation of the plurality of limit insertion posts 41, the stability and firmness of the installation of the shoulder slider 31 can be increased.

[0037] In the embodiments of the present utility model, the limiting insertion post 41 can be circular, square, oval, etc.

[0038] In the embodiments of the present utility model, the limiting insertion hole 315 can penetrate through the shoulder slider 31 for convenient installation.

[0039] In the embodiments of the present utility model, the limiting insertion hole 315 can be a round hole, a square hole, an oval hole, etc.

[0040] Such as Figure 1 , Figure 2 and Figure 3 As shown in

[0041] Figure 1 In the embodiments of the present utility model, the connecting member can be a threaded connecting member such as a bolt or a screw. Threaded connecting holes 316 for alignment connection can also be respectively provided on the shoulder slider 31 and the first inner shoulder wall 21. Preferably, the threaded connecting hole 316 on the shoulder slider 31 can be a countersunk hole. After the connecting member aligns and connects the threaded connecting holes 316 of the shoulder slider 31 and the first inner shoulder wall 21, the head of the connecting member can be located in the countersunk hole, thereby preventing the head of the connecting member from protruding from the surface of the shoulder slider 31 and affecting the sliding of the arm section. As shown in

[0042] In the embodiments of the present utility model, there can be many arrangement forms of the limiting installation assembly 4. For example, a limiting block can be welded on the first inner shoulder wall 21, or the shoulder slider 31 can be directly fixed on the first inner shoulder wall 21 by several screws.

[0043] It should be particularly emphasized that the shoulder slider 31 is a vulnerable part and needs to be replaced regularly. The method of using the limiting insertion post 41 for installation can facilitate the quick disassembly, assembly and replacement of the shoulder slider 31 in the later stage.

[0044] The cross-section design of the telescopic arm is closely related to the lifting performance of the crane. The stronger the lifting performance, the higher the requirements for the bending and torsional resistance of the telescopic arm cross-section. Under the limitations of the weight and size of the telescopic arm, the more sides the telescopic arm has, the stronger the bending resistance of the telescopic arm. Therefore, increasing the number of sides of the telescopic arm is the most common method to increase the lifting performance.

[0045] On the market, the cross-section shapes of all the arm sections in the telescopic arm of a folding boom crane and transporter are the same. For example, the number of sides of the basic arm section in some telescopic arms is generally hexagon, octagon, decagon, etc., and the number of sides of the head arm section and the intermediate arm section in the telescopic arm remains the same as that of the basic arm section.

[0046] For a folding boom crane truck, during lifting operations, the load on the boom sections near the head is much smaller than that on the boom sections near the root. Setting the number of sides of the head boom section, the middle boom section, and the root boom section to be the same will not only result in a waste of boom section performance, but also increase the manufacturing difficulty as the number of sides increases, leading to a relatively high production cost.

[0047] Based on the above considerations, as Figure 1 , Figure 4 and Figure 5 shown, in the present utility model, the outer boom section 1 and the inner boom section 2 are both polygonal tube booms, and the number of sides of the inner boom section 2 is less than that of the outer boom section 1.

[0048] In the embodiments of the present utility model, the outer boom section 1 and the inner boom section 2 are both formed by bending a high-strength steel plate through a specific process, and there is only one weld seam in the cross-section of the outer boom section 1 and the inner boom section 2 respectively. The boom sections of this structure will bring stronger bending resistance under the same mass and size. However, correspondingly, the processing cost will be higher than that of the existing welded boom sections, and the more the number of sides of the boom sections of this structure, the higher the processing difficulty and processing cost will be.

[0049] On the premise that the existing process is already very mature, it is very difficult to reduce the production cost of the boom section by optimizing the process. Considering that when the telescopic boom is working, the inner boom section 2 is closer to the head, and the required structural strength of the inner boom section 2 is less than that of the outer boom section 1. Therefore, the present utility model takes a different approach. By setting the number of sides of the inner boom section 2 to be less than that of the outer boom section 1, on the premise that both the inner boom section 2 and the outer boom section 1 meet the lifting performance of the telescopic boom, by reducing the number of sides of the inner boom section 2, the manufacturing difficulty of the inner boom section 2 can be reduced, thereby reducing the production cost of the telescopic boom unit as a whole.

[0050] As Figure 1 , Figure 4 and Figure 5 shown, in the embodiments of the present utility model, there are many forms of cooperation between the outer boom section 1 and the inner boom section 2. For example, the outer boom section 1 can be a decagonal tube boom, and the inner boom section 2 can be an octagonal tube boom or a hexagonal tube boom. Or the outer boom section 1 can be an octagonal tube boom, and the inner boom section 2 can be a hexagonal tube boom. Of course, the number of sides of the inner boom section 2 and the outer boom section 1 can also be odd numbers. For example, the outer boom section 1 can be a heptagonal tube boom, and the inner boom section 2 can be a hexagonal tube boom, a pentagonal tube boom, a quadrilateral tube boom, etc.

[0051] After the outer boom section 1 and the inner boom section 2 with different numbers of sides are assembled, affected by the different cross-sectional shapes, without using special materials, if the shape of the shoulder slider 31 is not changed, the slider is likely to deform or break due to uneven stress. Therefore, the shape of the slider also needs to be specially designed.

[0052] Specifically, as Figure 1 andFigure 2 As shown, taking the outer arm section 1 as a decagonal cylindrical arm as an example. When the number of sides of the arm section exceeds five, inclined walls will be formed at the shoulders of the arm section, and the more the number of sides of the arm section, the more the number of inclined walls at the shoulders.

[0053] As Figure 2 , Figure 4 and Figure 5 shown, for the decagonal cylindrical arm, the shoulders of the outer arm section 1 are provided with an inclined first outer shoulder wall 111 and a second outer shoulder wall 112. The first outer shoulder wall 111 and the second outer shoulder wall 112 are two adjacent walls, and there is a certain included angle between them. In order to achieve the fitting of the shoulder slider 31 with the outer arm section 1, a first fitting surface 311 and a second fitting surface 312 for fitting with the first outer shoulder wall 111 and the second outer shoulder wall 112 respectively can be provided on the side of the shoulder slider 31 facing the outer arm section 1, and the first fitting surface 311 and the second fitting surface 312 are respectively parallel to the corresponding first outer shoulder wall 111 and the second outer shoulder wall 112 in position. By providing the first fitting surface 311 and the second fitting surface 312, the contact area between the shoulder slider 31 and the outer arm section 1 can be increased, and it can be ensured that the shoulder slider 31 and the outer arm section 1 can be well fitted, so as to ensure that the stress of the outer arm section 1 can be evenly distributed on the shoulder slider 31 through the first fitting surface 311 and the second fitting surface 312.

[0054] As Figure 2 , Figure 4 and Figure 5 shown, in the embodiment of the present utility model, since the outer arm section 1 is bent from a whole steel plate through a special process, an arc transition edge 113 will inevitably be formed between the first outer shoulder wall 111 and the second outer shoulder wall 112. In order to further increase the fitting degree between the shoulder slider 31 and the outer arm section 1, an arc fitting surface 313 for fitting with the arc transition edge 113 can be provided between the first fitting surface 311 and the second fitting surface 312 of the shoulder slider 31.

[0055] In the embodiment of the present utility model, when the outer arm section 1 is a decagonal cylindrical arm, the inner arm section 2 can be a nonagonal cylindrical arm, an octagonal cylindrical arm, a heptagonal cylindrical arm, a hexagonal cylindrical arm, etc. In order to further highlight the characteristics of the shoulder slider 31, taking the inner arm section 2 as a hexagonal cylindrical arm as an example, the structure of the shoulder slider 31 will be described next.

[0056] As Figure 2 , Figure 4 and Figure 5As shown in the figure, the cross-sectional shape of the hexagonal cylinder arm is quite different from that of the decagonal cylinder arm. The shoulder of the decagonal cylinder arm is provided with a first outer shoulder wall 111 and a second outer shoulder wall 112, while the shoulder of the hexagonal cylinder arm only includes a first inner shoulder wall 21. The first inner shoulder wall 21 is radially aligned with the first outer shoulder wall 111 and the second outer shoulder wall 112 respectively. On the side of the shoulder slider 31 opposite to the first fitting surface 311 and the second fitting surface 312, there is a third fitting surface 314 for fitting with the first inner shoulder wall 21. The third fitting surface 314 is arranged parallel to the first inner shoulder wall 21. By setting the third fitting surface 314, it can be ensured that the other side of the shoulder slider 31 can fit well with the inner arm section 2, so as to ensure that the stress borne by the shoulder slider 31 can be evenly transmitted to the first inner shoulder wall 21.

[0057] As Figure 4 and Figure 5 shown, in the embodiment of the present invention, vertical wire edges extending vertically can be respectively arranged at the waists of the inner arm section 2 and the outer arm section 1. The vertical guiding edges can better limit the telescoping of the arm sections and ensure the centering of the inner arm section 2 and the outer arm section 1.

[0058] It can be understood that when the number of sides of the inner arm section 2 changes to other numbers, the shape of the third fitting surface 314 can be adaptively changed to make the first fitting surface 311 fit with the shoulder of the inner arm section 2 in a profiling manner. Or when the number of sides of the outer arm section 1 changes to other numbers, the shapes of the first fitting surface 311 and the second fitting surface 312 can be adaptively changed to make the shoulder slider 31 fit with the shoulder of the outer arm section 1.

[0059] To achieve the above object, the present invention also provides a hoisting machine, wherein the hoisting machine includes at least one set of telescopic arm units as described above. That is, the hoisting machine has at least two arm sections, and any two adjacent arm sections form a telescopic arm unit. Since the hoisting machine adopts all the technical solutions of the above embodiments, it has at least the beneficial effects brought by the above embodiments, which will not be repeated here.

[0060] In summary, by assembling two arm sections with different numbers of sides together, the present invention breaks the current situation of the unified cross-sectional form of the telescopic arms on the same folding boom hoisting and transporting vehicle, realizes the reduction of the cost of the telescopic arm unit, and at the same time uses special-shaped sliders for transition. Without using special materials, when the arm sections with different cross-sectional shapes are sleeved and matched, it can also ensure the uniform stress and normal telescoping between the arm sections, and improve the durability and reliability of the sliders.

[0061] In the description of the present utility model, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present utility model, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0062] In the present utility model, unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0063] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0064] Although the embodiments of the present utility model have been described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present utility model. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present utility model.

Claims

1. A telescopic arm unit, characterized in that: The telescopic arm unit comprises: The outer arm section (1) has a shoulder with an outer inclined shoulder wall (11); An inner arm section (2) is arranged inside the outer arm section (1) and has a shoulder inner inclined wall, wherein the shoulder inner inclined wall is radially aligned with the shoulder outer inclined wall (11); and The shoulder slider (31) is fixedly mounted on one of the shoulder outer inclined wall (11) and the shoulder inner inclined wall and is respectively fitted with the shoulder outer inclined wall (11) and the shoulder inner inclined wall.

2. The telescopic arm unit according to claim 1, characterized in that: A position limiting installation component (4) is provided on the inner inclined wall of the shoulder, and the shoulder slider (31) is fixedly installed on the inner inclined wall of the shoulder via the position limiting installation component (4).

3. The telescopic arm unit according to claim 2, characterized in that: The position-limiting installation assembly (4) comprises a position-limiting plug-in column (41) arranged on the inner inclined wall of the shoulder, and the shoulder slider (31) is provided with a position-limiting plug-in hole (315) for plugging and cooperating with the plug-in column.

4. The telescopic arm unit according to claim 3, characterized in that: The position limiting installation assembly (4) also includes a connecting piece for penetrating the shoulder slider (31) and the inner inclined wall of the shoulder.

5. The telescopic arm unit according to claim 4, characterized in that: The shoulder slider (31) and the shoulder inner inclined wall are respectively provided with threaded connection holes (316); the threaded connection holes (316) on the shoulder slider (31) are countersunk holes, and the connecting piece is a threaded connecting piece.

6. The telescopic arm unit according to any one of claims 1 to 5, characterized in that: The outer inclined shoulder wall (11) of the shoulder portion comprises a first outer shoulder wall (111) and a second outer shoulder wall (112) which are arranged adjacent to each other. The shoulder slider (31) is provided with a first fitting surface (311) and a second fitting surface (312) on one side facing the outer inclined shoulder wall (11) of the shoulder portion, respectively, for fitting with the first outer shoulder wall (111) and the second outer shoulder wall (112). The first fitting surface (311) and the second fitting surface (312) are respectively aligned and parallel with the first outer shoulder wall (111) and the second outer shoulder wall (112).

7. The telescopic arm unit according to claim 6, characterized in that: An arc transition edge (113) is provided between the first outer shoulder wall (111) and the second outer shoulder wall (112), and the shoulder slider (31) further comprises an arc fitting surface (313) located between the first fitting surface (311) and the second fitting surface (312).

8. The telescopic arm unit according to any one of claims 1 to 5, characterized in that: The outer arm section (1) and the inner arm section (2) are both polygonal cylindrical arms, and the number of sides of the inner arm section (2) is smaller than the number of sides of the outer arm section (1).

9. The telescopic arm unit according to claim 8, characterized in that: The outer arm section (1) is a decagonal cylinder arm, and the inner arm section (2) is an octagonal cylinder arm or a hexagonal cylinder arm; or the outer arm section (1) is an octagonal cylinder arm, and the inner arm section (2) is a hexagonal cylinder arm.

10. A lifting machine, characterized in that: Comprising a telescopic arm unit according to any one of claims 1 to 9.

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