Telescopic arm unit and hoisting machinery

Abstract

The invention belongs to the technical field of engineering machinery and provides a telescopic arm unit and hoisting machine.The telescopic arm unit comprises an outer arm section, an inner arm section and a sliding block assembly, the outer arm section is a polygonal barrel arm, the inner arm section is arranged in the outer arm section and is a polygonal barrel arm, and the number of edges of the inner arm section is smaller than that of edges of the outer arm section; the sliding block assembly is arranged between the outer arm section and the inner arm section. The number of edges of the inner arm section is set to be smaller than that of the outer arm section, and on the premise that both the inner arm section and the outer arm section meet the lifting performance of the telescopic arm, the manufacturing difficulty of the inner arm section can be reduced by reducing the number of the edges of the inner arm section, so that the manufacturing cost of the telescopic arm is reduced on the whole.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering machinery, and in particular relates to a telescopic arm unit and a lifting machinery. Background Art

[0002] At present, the cross-sections of the multi-section telescopic arms of the existing folding arm crane trucks at home and abroad are mostly of the same form, that is, the cross-section of the telescopic arm of a truck-mounted crane truck is one of the forms of hexagon, octagon, decagon, etc. The same truck-mounted crane truck uses telescopic arms with the same cross-section, which not only has a high manufacturing cost, but also has a lot of redundant performance of some telescopic arm units, resulting in performance waste. Summary of the invention

[0003] In view of the above-mentioned defects or shortcomings, the present invention provides a telescopic arm unit and a lifting machinery, aiming to reduce the manufacturing cost of the telescopic arm.

[0004] To achieve the above-mentioned purpose, the present invention provides a telescopic arm unit, which includes an outer arm section, an inner arm section and a slider assembly. The outer arm section is a polygonal cylindrical arm, the inner arm section is arranged inside the outer arm section and is a polygonal cylindrical arm, the number of sides of the inner arm section is smaller than the number of sides of the outer arm section, and the slider assembly is arranged between the outer arm section and the inner arm section.

[0005] In an embodiment of the present invention, the outer arm section is a decagonal cylinder arm, and the inner arm section is an octagonal cylinder arm or a hexagonal cylinder arm; or the outer arm section is an octagonal cylinder arm, and the inner arm section is a hexagonal cylinder arm.

[0006] In an embodiment of the present invention, the slider assembly includes a shoulder slider arranged between the shoulder of the outer arm section and the shoulder of the inner arm section, 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, and the shoulder slider is respectively fitted with the shoulder wall of the outer arm section and the shoulder wall of the inner arm section.

[0007] In an embodiment of the present invention, the shoulder of the outer arm section is provided with an inclined and adjacent first outer shoulder wall and a second outer shoulder wall, and the shoulder slider is provided with a first fitting surface and a second fitting surface respectively used to fit with the first outer shoulder wall and the second outer shoulder wall, and the first fitting surface and the second fitting surface are respectively aligned and parallel with the first outer shoulder wall and the second outer shoulder wall.

[0008] In an embodiment of the present invention, an arc transition edge is provided between the first outer shoulder wall and the second outer shoulder wall, and the shoulder slider further comprises an arc fitting surface between the first fitting surface and the second fitting surface.

[0009] In an embodiment of the present invention, the shoulder of the inner arm section is provided with an inclined first inner shoulder wall, the first inner shoulder wall is radially aligned with the first outer shoulder wall and the second outer shoulder wall respectively, and the shoulder slider is provided with a third fitting surface for fitting with the first inner shoulder wall, and the third fitting surface is arranged parallel to the first inner shoulder wall.

[0010] In an embodiment of the present invention, a position limiting installation component is provided on the outer side of the first inner shoulder wall, and the shoulder slider is position limitingly installed on the position limiting installation component.

[0011] In an embodiment of the present invention, the position limiting installation assembly includes a position limiting plug-in column arranged on the first inner shoulder wall, and the shoulder slider is plug-fitted with the position limiting plug-in column and connected to the first inner shoulder wall through a connecting piece.

[0012] In an embodiment of the present invention, the slider assembly includes a bottom slider disposed between a bottom inner side of the outer boom section and a bottom outer side of the inner boom section.

[0013] To achieve the above object, the present invention further provides a lifting machinery, wherein the lifting machinery comprises the telescopic arm unit described above.

[0014] Through the above technical solution, the telescopic arm unit provided by the embodiment of the present invention has the following beneficial effects:

[0015] The outer arm section and the inner arm section in the embodiment of the present invention 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 arm section and the inner arm section respectively. Under the condition of equal quality and size, the arm section of this structure will bring stronger bending resistance, but correspondingly, the processing cost will be higher than the existing welded arm section, and the more sides of the arm section of this type of structure, the higher the processing difficulty and processing cost. Considering that when the telescopic arm is working, the inner arm section is closer to the head, under the premise of the same lifting weight, the structural strength required for the inner arm section is less than that of the outer arm section. Therefore, the present invention takes a different approach. By setting the number of sides of the inner arm section to be less than that of the outer arm section, under the premise that both the inner arm section and the outer arm section meet the lifting performance of the telescopic arm, by reducing the number of sides of the inner arm section, the manufacturing difficulty of the inner arm section can be reduced, thereby reducing the manufacturing cost of the telescopic arm as a whole.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

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

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

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

[0021] Figure 4 is a schematic diagram of the cross-sectional shape of an outer arm section according to an embodiment of the present invention;

[0022] Figure 5 Schematic diagram of the cross-sectional shape of the inner arm section according to an embodiment of the present invention.

[0023] Description of Reference Numerals

[0024] 1. Outer arm section; 11. First outer shoulder wall; 12. Second outer shoulder wall; 13. Arc transition edge; 2. Inner arm section; 21. First inner shoulder wall; 3. Slider assembly; 31. Shoulder slider; 311. First fitting surface; 312. Second fitting surface; 313. Arc fitting surface; 314. Third fitting surface; 315. Limiting plug-in hole; 316. Threaded connection hole; 4. Limiting installation assembly; 41. Limiting plug-in column. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0026] The telescopic arm unit of the present invention will be described below with reference to the accompanying drawings.

[0027] The cross-sectional design of the telescopic arm is closely related to the lifting performance of the crane. The stronger the lifting performance, the higher the bending and torsion resistance requirements of the cross-sectional telescopic arm. Under the weight and size restrictions 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 way to increase the lifting performance.

[0028] All the boom sections of a telescopic boom on a folding boom crane on the market have the same cross-sectional shape. For example, the number of sides of the base boom section of some telescopic booms is generally hexagonal, octagonal, decagonal, etc., and the number of sides of the head boom section and the middle boom section of the telescopic boom remain the same as the base boom section.

[0029] For a folding-arm crane transport vehicle, during lifting operations, the load borne by the arm section close to the head is much smaller than the load borne by the arm section close to the root. Setting the number of sides of the head arm section, the middle arm section, and the root arm section to be the same will not only cause a waste of arm section performance, but the increase in the number of sides will also increase the difficulty of manufacturing, leading to higher production costs.

[0030] Based on the above considerations, if Figure 1 , Figure 4 and Figure 5 As shown, the present invention provides a telescopic arm unit, the telescopic arm unit comprising:

[0031] The outer arm section 1 is a polygonal cylinder arm;

[0032] The inner arm section 2 is arranged in the outer arm section 1 and is also a polygonal cylinder arm, and the number of sides of the inner arm section 2 is smaller than the number of sides of the outer arm section 1;

[0033] The slider assembly 3 is arranged between the outer arm section 1 and the inner arm section 2 .

[0034] Among them, the outer arm section 1 refers to the arm section closer to the root of the telescopic arm, and the inner arm section 2 refers to the arm section closer to the head of the telescopic arm. Both the outer arm section 1 and the inner arm section 2 are hollow cylindrical arm sections. The inner arm section 2 is arranged in the outer arm section 1 and can telescopically move relative to the outer arm section 1.

[0035] The polygonal cylinder arm means that the cross-sections of the outer arm section 1 and the inner arm section 2 are polygonal.

[0036] like Figure 4 and Figure 5 As shown, the outer boom section 1 and the inner boom section 2 in the embodiment of the present invention 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. The boom section of this structure will have stronger bending resistance under the condition of the same quality and size, but correspondingly, the processing cost will be higher than that of the existing tailor-welded boom section, and the more sides the boom section of this structure has, the higher the processing difficulty and processing cost will be.

[0037] Under the premise that the existing technology is very mature, it is difficult to reduce the production cost of the boom section by optimizing the process. Considering that the inner boom section 2 is closer to the head when the telescopic boom is working, the structural strength required by the inner boom section 2 is less than that of the outer boom section 1 in general lifting conditions. Therefore, the present invention 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, and 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 manufacturing cost of the telescopic boom unit as a whole.

[0038] like Figure 1 , Figure 4 and Figure 5 As shown, in the embodiment of the present invention, there are many forms of matching between the outer arm section 1 and the inner arm section 2, such as the outer arm section 1 can be a decagonal cylinder arm, and the inner arm section 2 can be an octagonal cylinder arm or a hexagonal cylinder arm. Or the outer arm section 1 can be an octagonal cylinder arm, and the inner arm section 2 can be a hexagonal cylinder arm. Of course, the number of sides of the inner arm section 2 and the outer arm section 1 can also be an odd number, such as the outer arm section 1 can be a heptagonal cylinder arm, and the inner arm section 2 can be a hexagonal cylinder arm, a pentagonal cylinder arm, a quadrilateral cylinder arm, etc.

[0039] The slider assembly 3 generally includes a shoulder slider 31 disposed between the shoulder of the outer arm section 1 and the shoulder of the inner arm section 2. The shoulder slider 31 is installed on one of the outer arm section 1 and the inner arm section 2 and is in sliding contact with the other. The shoulder slider 31 can separate the outer arm section 1 from the inner arm section 2 to ensure normal sliding between the inner arm section 2 and the outer arm section 1.

[0040] After the outer arm section 1 and the inner arm section 2 with different numbers of sides are assembled, due to the different cross-sectional shapes, if the shoulder slider 31 uses the existing universal slider without using special materials, the slider may be easily deformed or broken due to uneven force, so a special design of the slider structure is required.

[0041] In order to solve the problem that the shoulder slider 31 is easily deformed or broken, in the embodiment of the present invention, it is necessary to optimize the shape of the shoulder slider 31 so that the shoulder slider 31 is disposed transitionally between the outer arm section 1 and the inner arm section 2. The optimization method may be to arrange the shoulder slider 31 to fit with the shoulder wall of the outer arm section 1 and the shoulder wall of the inner arm section 2 respectively, so that the stress of the outer arm section 1 is evenly distributed on the shoulder slider 31 through the fitting.

[0042] Specifically, Figure 1 and Figure 2 As shown, the outer arm section 1 is a decagonal cylinder arm as an example. When the number of sides of the arm section exceeds the pentagon, an inclined wall will be formed at the shoulder of the arm section, and the more sides the arm section has, the more inclined walls there are at the shoulder.

[0043] like Figure 2 , Figure 4 and Figure 5 As shown, for the decagonal cylinder arm, the shoulder of the outer arm section 1 is provided with an inclined first outer shoulder wall 11 and a second outer shoulder wall 12, and the first outer shoulder wall 11 and the second outer shoulder wall 12 are two adjacent walls, and there is a certain angle between the two. In order to achieve the fit between the shoulder slider 31 and the outer arm section 1, a first fit surface 311 and a second fit surface 312, which are respectively used to fit with the first outer shoulder wall 11 and the second outer shoulder wall 12, can be provided on the side of the shoulder slider 31 facing the outer arm section 1, and the first fit surface 311 and the second fit surface 312 are respectively aligned and parallel with the corresponding first outer shoulder wall 11 and the second outer shoulder wall 12. By providing the first fit surface 311 and the second fit surface 312, the contact area between the shoulder slider 31 and the outer arm section 1 can be increased, and it is 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 fit surface 311 and the second fit surface 312.

[0044] like Figure 2 , Figure 4 and Figure 5As shown, in the embodiment of the present invention, since the outer arm section 1 is formed by bending a whole steel plate through a special process, an arc transition edge 13 is inevitably formed between the first outer shoulder wall 11 and the second outer shoulder wall 12. In order to further increase the degree of fit between the shoulder slider 31 and the outer arm section 1, an arc fitting surface 313 for fitting with the arc transition edge 13 can be provided between the first fitting surface 311 and the second fitting surface 312 of the shoulder slider 31.

[0045] In the embodiment of the present invention, when the outer arm section 1 is a decagonal cylinder arm, the inner arm section 2 can be a pentagonal cylinder arm, an octagonal cylinder arm, a heptagonal cylinder arm, a hexagonal cylinder arm, etc. In order to further highlight the characteristics of the shoulder slider 31, the structure of the shoulder slider 31 is described below by taking the inner arm section 2 as a hexagonal cylinder arm as an example.

[0046] like Figure 2 , Figure 4 and Figure 5 As shown, 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 11 and a second outer shoulder wall 12, while the shoulder of the hexagonal cylinder arm only includes a first inner shoulder wall 21, and the first inner shoulder wall 21 is radially aligned with the first outer shoulder wall 11 and the second outer shoulder wall 12 respectively. The side of the shoulder slider 31 opposite to the first fitting surface 311 and the second fitting surface 312 is provided with a third fitting surface 314 for fitting with the first inner shoulder wall 21, and the third fitting surface 314 is arranged parallel to the first inner shoulder wall 21. By providing the third fitting surface 314, it can be ensured that the other side of the shoulder slider 31 can be well fitted with the inner arm section 2, thereby ensuring that the stress borne by the shoulder slider 31 can be evenly transferred to the first inner shoulder wall 21.

[0047] like Figure 4 and Figure 5 As shown, in an embodiment of the present invention, the waists of the inner arm section 2 and the outer arm section 1 may also be provided with vertically extending vertical guide edges, respectively. The vertical guide edges can better limit the extension and retraction of the arm sections, thereby ensuring the alignment of the inner arm section 2 and the outer arm section 1.

[0048] It is understandable that when the number of sides of the inner arm section 2 is changed to another number, the shape of the third fitting surface 314 can be adaptively changed so that the first fitting surface 311 can be contoured and fit with the shoulder of the inner arm section 2. Or when the number of sides of the outer arm section 1 is changed to another number, the shapes of the first fitting surface 311 and the second fitting surface 312 can be adaptively changed so that the shoulder slider 31 can be contoured and fit with the shoulder of the outer arm section 1.

[0049] In summary, the telescopic arm unit of the present invention uses a special-shaped slider to transition between the inner arm section 2 and the outer arm section 1, so that when arm sections with different cross-sectional shapes are socketed and matched, uniform force and normal telescopic movement between the arm sections can be ensured.

[0050] like Figure 1 , Figure 2 and Figure 3 As shown, in the embodiment of the present invention, the shoulder slider 31 can be installed on the inner side of the outer arm section 1 and arranged to be in sliding contact with the outer surface of the inner arm section 2, or the shoulder slider 31 can be installed on the outer side of the inner arm section 2 and arranged to be in sliding contact with the inner surface of the outer arm section 1. For the convenience of installation, the shoulder slider 31 can be preferably installed on the outer side of the inner arm section 2, and this installation method can prevent the shoulder slider 31 from falling off during installation.

[0051] Specifically, Figure 1 , Figure 2 and Figure 3 As shown, in an embodiment of the present invention, a limit installation assembly 4 may be provided on the outer surface of the first inner shoulder wall 21 of the inner arm section 2 , and the shoulder slider 31 is preferably detachably mounted on the first inner shoulder wall 21 through the limit installation assembly 4 .

[0052] like Figure 1 , Figure 2 and Figure 3 As shown, the position-limiting installation assembly 4 may include a position-limiting plug-in column 41 disposed on the first inner shoulder wall 21. The position-limiting plug-in column 41 may be installed on the first inner shoulder wall 21 by welding or other means. In order to cooperate with the position-limiting plug-in column 41, a position-limiting plug-in hole 315 for plugging and cooperating with the position-limiting plug-in column 41 needs to be provided on one side (third fitting surface 314) of the shoulder slider 31 facing the first inner shoulder wall 21. The position-limiting of the shoulder slider on the X-axis and the Y-axis can be achieved by plugging and cooperating the shoulder slider 31 with the position-limiting plug-in column 41. In order to achieve the installation and fixation of the shoulder slider 31 and the position-limiting of the Z-axis, a connector may be used to penetrate the shoulder slider 31 and the first inner shoulder wall 21. Alternatively, the shoulder slider 31 may be adhered to the first inner shoulder wall 21 by glue.

[0053] like Figure 1 and Figure 3 As shown, in an embodiment of the present invention, a first inner shoulder wall 21 is provided on both sides of the inner arm section 2, and a plurality of limiting plug-in columns 41 can be provided on each first inner shoulder wall 21. Through the plug-in cooperation of the plurality of limiting plug-in columns 41, the stability and firmness of the installation of the shoulder slider 31 can be increased.

[0054] In the embodiment of the present invention, the limiting plug-in column 41 can be circular, square, oval, etc.

[0055] In the embodiment of the present invention, the limiting plug hole 315 may be provided through the shoulder slider 31 to facilitate installation.

[0056] In the embodiment of the present invention, the limiting plug hole 315 can be a round hole, a square hole, an elliptical hole, etc.

[0057] like Figure 1 , Figure 2 and Figure 3 As shown, in the embodiment of the present invention, the connecting member may be a threaded connecting member such as a bolt or a screw, and the shoulder slider 31 and the first inner shoulder wall 21 may be respectively provided with threaded connecting holes 316 for alignment connection. Preferably, the threaded connecting hole 316 on the shoulder slider 31 may be a countersunk hole, and after the connecting member is aligned and connected to the shoulder slider 31 and the threaded connecting hole 316 of the first inner shoulder wall 21, the head of the connecting member may 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.

[0058] like Figure 1 As shown, in the embodiment of the present invention, shoulder sliders 31 are provided on the two lateral shoulders of the inner arm section 2, that is, the number of the shoulder sliders 31 can be two.

[0059] In the embodiment of the present invention, the limit installation assembly 4 can be arranged in many forms, such as welding a limit block on the first inner shoulder wall 21, or directly fixing the shoulder slider 31 on the first inner shoulder wall 21 by a plurality of screws.

[0060] It should be particularly emphasized that the shoulder slider 31 is a wearing part and needs to be replaced regularly. The shoulder slider 31 can be installed by means of a limiting plug-in column 41 to facilitate the rapid disassembly, assembly and replacement of the shoulder slider 31 at a later time.

[0061] In the embodiment of the present invention, the slider assembly 3 includes a bottom slider (not shown in the figure) disposed between the bottom inner side of the outer arm section 1 and the bottom outer side of the inner arm section 2. The bottom slider is generally disposed at the head end of the outer arm section 1, and the shoulder slider 31 is generally disposed at the root end of the inner arm section 2. The cooperation of the bottom slider and the shoulder slider 31 can ensure smooth extension and retraction of the inner arm section 2.

[0062] To achieve the above object, the present invention further provides a lifting machinery, wherein the lifting machinery comprises at least one set of telescopic arm units according to the above. That is, the lifting machinery has at least two arm sections, and any adjacent arm sections constitute a telescopic arm unit. Since the lifting machinery 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.

[0063] In summary, the present invention breaks the current situation of unified cross-sectional form of telescopic arms on the same folding arm crane and transport vehicle by assembling two arm sections with different numbers of sides together, thereby reducing the cost of the telescopic arm unit. At the same time, the slider adopts a transition design, which can achieve the coordination of arm sections with different cross-sectional forms without using special materials, thereby improving the durability and reliability of the slider.

[0064] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0065] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. 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 may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0067] Although the embodiments of the present invention have been described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A telescopic arm unit, characterized in that: The telescopic arm unit comprises: The outer arm section (1) is a polygonal cylindrical arm; an inner arm section (2) which is arranged inside the outer arm section (1) and is a polygonal cylindrical arm, wherein the number of sides of the inner arm section (2) is smaller than the number of sides of the outer arm section (1); and A slider assembly (3) is arranged between the outer arm section (1) and the inner arm section (2).

2. The telescopic arm unit according to claim 1, 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.

3. The telescopic arm unit according to claim 1, characterized in that: The slider assembly (3) comprises a shoulder slider (31) arranged between the shoulder of the outer arm section (1) and the shoulder of the inner arm section (2); the shoulder slider (31) is installed on one of the outer arm section (1) and the inner arm section (2) and is in sliding contact with the other; the shoulder slider (31) is respectively fitted with the shoulder wall of the outer arm section (1) and the shoulder wall of the inner arm section (2).

4. The telescopic arm unit according to claim 3, characterized in that: The shoulder of the outer arm section (1) is provided with an inclined and adjacent first outer shoulder wall (11) and a second outer shoulder wall (12); the shoulder slider (31) is provided with a first fitting surface (311) and a second fitting surface (312) respectively used for fitting with the first outer shoulder wall (11) and the second outer shoulder wall (12); the first fitting surface (311) and the second fitting surface (312) are respectively aligned and parallel with the first outer shoulder wall (11) and the second outer shoulder wall (12).

5. The telescopic arm unit according to claim 4, characterized in that: An arc transition edge (13) is provided between the first outer shoulder wall (11) and the second outer shoulder wall (12), 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).

6. The telescopic arm unit according to claim 4, characterized in that: The shoulder of the inner arm section (2) is provided with an inclined first inner shoulder wall (21), and the first inner shoulder wall (21) is radially aligned with the first outer shoulder wall (11) and the second outer shoulder wall (12), respectively; the shoulder slider (31) is provided with a third fitting surface (314) for fitting with the first inner shoulder wall (21), and the third fitting surface (314) is arranged parallel to the first inner shoulder wall (21).

7. The telescopic arm unit according to claim 6, characterized in that: A position limiting installation component (4) is provided on the outer side of the first inner shoulder wall (21), and the shoulder slider (31) is position limitingly installed on the position limiting installation component (4).

8. The telescopic arm unit according to claim 7, characterized in that: The position limiting installation assembly (4) comprises a position limiting plug-in column (41) arranged on the first inner shoulder wall (21), and the shoulder slider (31) is plug-fitted with the position limiting plug-in column (41) and connected to the first inner shoulder wall (21) via a connecting piece.

9. The telescopic arm unit according to any one of claims 1 to 8, characterized in that: The slider assembly (3) comprises a bottom slider arranged between the bottom inner side of the outer arm section (1) and the bottom outer side of the inner arm section (2).

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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