CN111657667A - Quickly disassembled and assembled office table support - Google Patents

Abstract

The invention relates to a quickly-disassembled and assembled office table support which comprises a longitudinal beam, a cross beam and table legs, wherein the table legs are electric lifting table leg upright posts, the table legs are assembled with the table top support through a quickly-disassembled and assembled mechanism, the quickly-disassembled and assembled mechanism comprises a clamping groove mechanism and a locking mechanism, the locking mechanism comprises a rotating part and a fixing part which are respectively arranged on the table legs and the longitudinal beam, the rotating part and the fixing part are driven and matched through a spiral structure, the locking mechanism drives the table legs to transversely move through the forward and reverse rotation of the rotating part, so that clamping heads are clamped into or withdrawn from a main body part of the clamping grooves, and the assembling relation between the table. According to the invention, the whole office table bracket can be assembled and disassembled only by rotating the rotating piece arranged on the longitudinal beam without using screws or tools, so that the reduction of packaging materials and cost is facilitated.

Description

Quickly disassembled and assembled office table support

Technical Field

The invention belongs to the technical field of furniture equipment, and particularly relates to a quickly-disassembled office table support.

Background

With the development of the times, the liftable office table becomes a new trend of modern office. The lifting platform, especially the electric lifting platform, such as a lifting table, is more and more popular in the office and home fields at present, and because the lifting platform occupies a large space and is inconvenient to transport, the electric lifting platform is not assembled when a manufacturer of the electric lifting table leaves a factory at present, and the electric lifting platform needs to be assembled by a consumer after purchase or assembled by the manufacturer. Therefore, how to achieve quick assembly and disassembly or how to facilitate assembly by consumers is a problem to be solved urgently by the current lifting platform or electric lifting platform.

The current lifting platform or lifting desk usually comprises a table top and a desk support, and the desk support comprises a longitudinal beam, a cross beam and electric lifting desk leg upright posts. Present quick assembly disassembly's desk support is usually with longeron and crossbeam welding together, and later stage equipment mainly lies in the installation between crossbeam and the electric lift table leg stand, thereby it compresses tightly crossbeam and electric lift table leg stand each other and makes both fixed connection to adopt crank or cam mechanism at present comparatively common, and its equipment step is comparatively loaded down with trivial details, also comparatively difficultly during the dismantlement. Meanwhile, as the longitudinal beams and the transverse beams are welded together, the occupied space of the packaging is large, so that the packaging and transportation are difficult, and the packaging and transportation cost of the product is increased, and the prior art is disclosed in Chinese patent document CN 209359912U.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: overcome not enough among the prior art, provide a quick assembly disassembly's desk support, can make the equipment and the dismantlement of desk support more quick, convenient, improved whole dismouting efficiency.

The technical scheme adopted by the invention for solving the technical problems is as follows: a quickly detachable desk support comprises a desktop support and desk legs for supporting the desktop support, wherein the desktop support comprises longitudinal beams and transverse beams, the desk legs are positioned at the intersection of the longitudinal beams and the transverse beams and are assembled with the desktop support through a quick detaching mechanism, the quick detaching mechanism comprises a clamping groove mechanism and a locking mechanism, the clamping groove mechanism comprises clamping heads and clamping grooves respectively positioned on the desk legs and the transverse beams, the main body part of the clamping groove transversely extends, the desk legs are assembled with the transverse beams in a mode that the clamping heads are clamped into the main body part of the clamping groove, the locking mechanism comprises rotating parts and fixing parts respectively positioned on the desk legs and the longitudinal beams, the rotating parts can be rotatably installed and fixedly installed, the rotating parts and the fixing parts are in driving fit through spiral structures, the locking mechanism drives the desk legs to transversely move through the positive and negative rotation of the rotating parts, and further ensures that, the assembly relationship between the legs and the cross member is locked or unlocked.

Further, the spiral structure matched with the rotating part and the fixed part specifically comprises a spiral groove and a pin shaft embedded in the spiral groove.

Further, the spiral groove is provided with a backstop pit for preventing the rotary member from reversing, and the pin shaft is clamped into the backstop pit when the clamping head moves to the stroke end of the clamping groove, so that the locking state of the table leg and the cross beam is maintained.

Further, the rotating part and the fixed part are nested and matched in and out.

Further limiting, the locking mechanism further comprises a return spring, the return spring acts on the rotating piece to drive the rotating piece to return to an unlocking position, and when the rotating piece is in the unlocking position, the pin shaft on the rotating piece is over against the front end opening of the spiral groove and is embedded into the spiral groove through the front end opening of the spiral groove. The design of reset spring has made things convenient for the quick cartridge of rotating member with the mounting, improves the convenience of desk support assembly.

One of the specific structures of the locking mechanism is as follows: the rotating piece comprises a columnar part and an operation cantilever part extending out of the columnar part, the columnar part can be rotatably arranged on the longitudinal beam through a rotating shaft, and two pin shafts which are coaxially distributed are arranged on the columnar part; the mounting is a cavity cylinder, and the rotating member passes through the hole of column portion embedding mounting, has seted up two helicla flutes that supply the round pin axle embedding in the periphery of mounting, has rotatory limit structure between column portion and the pivot for rotatory spacing to the rotating member to the unblock position at the rotating member, reset spring has the pretightning force when the rotating member is in the unblock position, and reset spring is the torsional spring, and reset spring sets up between the column portion and the pivot of rotating member.

Further inject, the table leg is electric lift table leg stand, and electric lift table leg stand includes the drive box at lift stand and lift stand top, and the drive box is assembled with the desktop support through quick assembly disassembly mechanism.

In order to reduce packaging materials and cost, the transverse beam and the longitudinal beam are of a split structure, the end portion of the transverse beam is inserted and positioned on the longitudinal beam through an end portion positioning structure, when the locking mechanism locks the assembling relation of the table legs and the transverse beam, the clamping head moves to the tail end of the stroke of the clamping groove, and the inserting relation of the transverse beam and the longitudinal beam is locked.

Further inject, tip location structure includes the base on the longeron, fix on the lateral wall of the locating pin of vertical setting and the crossbeam on the base and the grafting constant head tank of locating pin complex, and the head of locating pin has spacing end cap, and when locking state, the locating pin embedding grafting constant head tank, base and spacing end cap are located the inside and outside both sides of grafting constant head tank respectively.

Further inject, the crossbeam is provided with two, and the table leg is located between two crossbeams, and the table leg is all assembled through two draw-in groove mechanisms with every crossbeam, and two crossbeams pass through the connecting plate to be connected as a whole, and the draw-in groove of draw-in groove mechanism includes vertical downwardly extending's entry part and transversely extended main part, and the main part of draw-in groove and the grafting constant head tank outer width of crossbeam tip are the tubaeform in, and column portion is through the pivot rotationally concrete structure on the longeron do: the convex ring has in the hole of column portion, and column portion passes through the convex ring cover and rotates in the pivot, has a retaining ring at the head end of pivot through the fix with screw, and the retaining ring keeps off and carries out the axial spacing outside the convex ring, and rotatory limit structure between column portion and the pivot includes spacing annular in the column portion and changes epaxial spacing pin, and spacing pin embedding spacing annular carries out rotation limitation, and the head end of the spacing pin of twist pivot pushes up the side at the screw simultaneously.

The invention has the beneficial effects that: need not to use the screw, need not with the help of the instrument, only need just can accomplish the equipment and the dismantlement work of whole desk support through the rotating member of rotatory operation installation on the longeron, removable structure is favorable to reducing packaging material and cost simultaneously.

Drawings

The invention is further described with reference to the following figures and embodiments.

FIG. 1 is a schematic view of an assembly structure of embodiment 1 of the present invention (only one side of a desktop support is shown by cutting to show the assembly relationship with the upright post of the electric elevating table leg on the side);

FIG. 2 is an exploded view of FIG. 1;

FIG. 3 is a schematic structural view of a rotary member according to embodiment 1 of the present invention;

fig. 4 is a schematic structural view of a fixing member of embodiment 1 of the present invention;

FIG. 5 is a schematic structural view of a rotating member and a fixed member in a locked state according to embodiment 1 of the present invention;

FIG. 6 is a schematic structural view of a rotating member and a fixed member in another perspective in a locked state according to embodiment 1 of the present invention;

FIG. 7 is a schematic structural view of a rotating member and a fixed member in an unlocked state according to embodiment 1 of the present invention;

fig. 8 is a schematic structural view of a side member of embodiment 1 of the invention;

fig. 9 is a cross-sectional view of a swivel on a stringer of embodiment 1 of the present invention;

FIG. 10 is a schematic structural view of a rotary member according to embodiment 2 of the present invention;

fig. 11 is a sectional view of a rotary member according to embodiment 2 of the present invention.

In the figure: 1. the novel electric lifting table leg comprises an electric lifting table leg upright column, 1-1 lifting upright column, 1-2 driving box, 2 crossbeam, 3 longitudinal beam, 3-1 side plate, 3-2 top folded edge, 4 clamping groove, 5 clamping head, 6 rotating part, 6-1 columnar part, 6-1-1 pin shaft, 6-2 cantilever part, 7 fixing part, 7-1 spiral groove, 7-1-1 stopping pit, 7-2 mounting plate, 8 reset spring, 9-1 base, 9-2 positioning pin, 9-2-1 limiting end cap, 9-3 inserting positioning groove, 10 convex ring, 11 connecting plate, 12 rotating shaft, 13 retaining ring, 14 screw, 15 limiting ring groove and 16 limiting pin.

Detailed Description

The invention will now be further described with reference to the accompanying drawings. These drawings are simplified schematic diagrams only illustrating the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.

Embodiment 1, as shown in fig. 1-9, a quick assembly disassembly's desk support, including desktop support and the table leg that supports desktop support, desktop support includes longeron 3 and crossbeam 2, and the table leg is located the intersection of longeron 3 and crossbeam 2 to assemble with desktop support through quick assembly disassembly mechanism, quick assembly disassembly mechanism includes draw-in groove mechanism and locking mechanical system.

The clamping groove mechanism comprises a clamping head 5 and a clamping groove 4 which are respectively positioned on the table leg and the cross beam 2, the main part of the clamping groove 4 transversely extends, and the table leg is assembled with the cross beam 2 in a mode that the clamping head 5 is clamped into the main part of the clamping groove 4.

The card slot 4 of the card slot mechanism comprises an inlet part extending vertically downwards and a main body part extending transversely, and the main body part of the card slot 4 is wide at the outside and narrow at the inside and is in a horn shape.

The locking mechanism comprises a rotating part 6, a fixing part 7 and a return spring 8 which are respectively positioned on the table legs and the longitudinal beams 3, the rotating part 6 can be rotatably installed, the fixing part 7 is fixedly installed, the rotating part 6 and the fixing part 7 are in driving fit through a spiral structure, the locking mechanism drives the table legs to transversely move through the forward and reverse rotation actions of the rotating part 6, so that the clamping heads 5 are clamped into or withdrawn from the main body parts of the clamping grooves 4, and the assembling relation between the table legs and the transverse beams 2 is locked or released.

The matched spiral structures on the rotating part 6 and the fixing part 7 specifically comprise a spiral groove 7-1 and a pin shaft 6-1-1 embedded in the spiral groove 7-1.

The spiral groove 7-1 is provided with a backstop pit 7-1-1 for preventing the rotary piece 6 from reversing, and the pin shaft 6-1-1 is clamped into the backstop pit 7-1-1 when the clamping head 5 moves to the stroke end of the clamping groove 4, so that the locking state of the table leg and the cross beam 2 is maintained.

The rotating member 6 and the fixed member 7 are nested inside and outside.

The more concrete structure of the rotating member 6 and the fixed member 7 is: the rotating part 6 comprises a columnar part 6-1 and an operation cantilever part 6-2 extending out of the columnar part 6-1, the columnar part 6-1 can be rotatably arranged on the longitudinal beam 3 through a rotating shaft 12, and two pin shafts 6-1-1 which are coaxially distributed are arranged on the columnar part 6-1; the fixed part 7 is a hollow cylinder, the rotating part 6 is embedded into an inner hole of the fixed part 7 through the columnar part 6-1, two spiral grooves 7-1 for embedding the pin shafts 6-1-1 are formed in the periphery of the fixed part 7, and the backstop pits 7-1-1 are located on one side, close to the rotating part 6, of the tail end of each spiral groove 7-1. The return spring 8 acts on the rotating part 6 to drive the rotating part 6 to return to an unlocking position, when the unlocking position is reached, the pin shaft 6-1-1 on the rotating part 6 is over against the front end opening of the spiral groove 7-1, and the pin shaft 6-1-1 is embedded into the spiral groove 7-1 through the front end opening of the spiral groove 7-1. The return spring 8 is a torsion spring, and the return spring 8 is disposed between the columnar portion 6-1 of the rotary member 6 and the rotary shaft 12.

As shown in fig. 9, the concrete structure of the column part 6-1 rotatably mounted on the longitudinal beam 3 through the rotating shaft 12 is: a convex ring 10 is arranged in an inner hole of the columnar part 6-1, the columnar part 6-1 is sleeved on a rotating shaft 12 through the convex ring 10 to rotate, a retaining ring 13 is fixed at the head end of the rotating shaft 12 through a screw 14, and the retaining ring 13 is retained outside the convex ring 10 to carry out axial limiting.

The table legs are electric lifting table leg upright posts 1, the electric lifting table leg upright posts 1 comprise lifting upright posts 1-1 and driving boxes 1-2 arranged at the tops of the lifting upright posts 1-1, and the driving boxes 1-2 are assembled with the table top support through a quick assembling and disassembling mechanism. The clamping head 5 is a trapezoidal convex block on the driving box 1-2.

The cross beam 2 and the longitudinal beam 3 are of a split structure, the end part of the cross beam 2 is inserted and positioned on the longitudinal beam 3 through an end part positioning structure, when the locking mechanism locks the assembly relation of the table legs and the cross beam 2, the clamping head 5 moves to the tail end of the stroke of the clamping groove 4, and the insertion relation of the cross beam 2 and the longitudinal beam 3 is locked.

The end positioning structure comprises a base 9-1 on the longitudinal beam 3 and a positioning pin 9-2 which is longitudinally arranged and fixed on the base 9-1, the head of the positioning pin 9-2 is provided with a limiting end cap 9-2-1, the side wall of the cross beam 2 is provided with an inserting positioning groove 9-3 matched with the positioning pin 9-2, the positioning pin 9-2 is embedded into the inserting positioning groove 9-3 in a locking state, and the base 9-1 and the limiting end cap 9-2-1 are respectively positioned at the inner side and the outer side of the inserting positioning groove 9-3.

The crossbeams 2 are provided with two crossbeams, the desk legs are arranged between the two crossbeams 2, the desk legs and each crossbeam 2 are assembled through two clamping groove mechanisms, and the two crossbeams 2 are connected into a whole through the connecting plate 11. The longitudinal beam 3 comprises a side plate 3-1 and a top folding edge 3-2 at the top of the side plate 3-1. The rotary member 6 and the base 9-1 are located on the side plate 3-1.

The front end of the fixing piece 7 is provided with a mounting plate 7-2, the fixing piece 7 is fixed on the driving box 1-1 through the mounting plate 7-2 and a screw, and the fixing piece 7 is positioned inside the driving box 1-2.

The cross beam 21 is specifically a square tube.

This embodiment 1 has the following advantages:

firstly, the assembly and disassembly of the whole office table bracket can be completed only by rotating the rotating piece 6 arranged on the longitudinal beam 3 without using screws or tools;

secondly, the rotating piece 6 is rotated by operating the cantilever part 6-2, so that the operation is fast and labor-saving, the assembling and disassembling workload of an installer is greatly reduced, and the assembling and disassembling efficiency is obviously improved;

thirdly, the assembly steps are simplified, when in assembly, the base 9-1 of the longitudinal beam 3 is firstly inserted into the end hole of the cross beam 2, the horn-shaped inserting positioning groove 9-3 is matched with the positioning pin 9-2, and then the clamping head 5 on the upright post 1 of the electric lifting table leg enters the clamping groove 4 from bottom to top through the inlet part of the clamping groove 4. The rotating member 6 is kept at an unlocking position under the reset action of the reset spring 8, when the rotating member is at the unlocking position, the pin shaft 6-1-1 on the rotating member 6 is over against the front end opening of the spiral groove 7-1, the electric lifting table leg upright post 1 is only slightly transversely moved to enable the pin shaft 6-1-1 to enter the spiral groove 7-1, the rotating member 6 is manually and positively rotated by operating the cantilever part 6-2 to enable the locking mechanism to be in a locking state, and as shown in figures 5 and 6, the screw-free rapid assembly between the electric lifting table leg upright post 1 and the table top support as well as between the cross beam 2 and the longitudinal beam 3 is completed;

fourthly, the disassembly steps are simplified, in the whole disassembly process, the upright column 1 and the cross beam 2 of the electric lifting table leg can be automatically separated only by operating the cantilever part 6-2 to reversely rotate the rotating part 6 to the unlocking position, and then the chuck 5 of the driving box 1-2 is withdrawn from the clamping groove 4 of the cross beam 2, so that the whole disassembly process can be completed, time and labor are saved, and the disassembly efficiency is greatly improved;

fifthly, the cross beam 2 and the longitudinal beam 3 adopt split design, the cross beam 2 and the longitudinal beam 3 are packaged after being disassembled, packaging materials and cost are reduced, and the transportation cost of the whole office table support or the lifting office table can be reduced.

Example 2, the difference compared to example 1 is that: a rotation limiting structure is arranged between the columnar part 6-1 and the rotating shaft 12 and used for limiting the rotation of the rotating part 6 when the rotating part 6 rotates to an unlocking position, the reset spring 8 has pretightening force when the rotating part 6 is at the unlocking position, the rotation limiting structure between the columnar part 6-1 and the rotating shaft 12 comprises a limiting ring groove 15 on the columnar part 6-1 and a limiting pin 16 on the rotating shaft 12, the limiting pin 16 is embedded into the limiting ring groove 15 to limit the rotation, the head end of the limiting pin 16 screwed into the rotating shaft 12 simultaneously props against the side face of the screw 14, and the screw 14 is prevented from loosening, as shown in figures 10 and 11.

Example 3, the difference compared to example 1 is that: by changing the return direction of the return spring 8, the return spring 8 has a function of preventing the rotation member 6 from being reversed, and is used to maintain the locked state of the table leg and the cross member 2 instead of the retaining depressions 7-1-1. This solution has the disadvantage of being disadvantageous for rapid assembly compared to example 1. Certainly, the scheme that the spiral structure is self-locked through a pluggable limiting bolt or a designed spiral angle can be kept in a locking state, so that the rotating piece 6 cannot be reversely rotated and unlocked in a locking position.

Example 4 differs from examples 1 and 2 in that: the cross beam 2 and the longitudinal beam 3 are fixedly connected together by welding and other methods, the locking mechanism drives the table legs to transversely move through the forward and backward rotation action of the rotating piece 6, so that the clamping head 5 is clamped in or withdrawn from the main body part of the clamping groove 4, and the assembling relation between the table legs and the table top support is locked or released.

Example 5 differs from examples 1 and 2 in that: the positions of a clamping head 5 and a clamping groove 4 of the clamping groove mechanism are interchanged, the clamping groove 4 is positioned on the driving box 1-2, and the clamping head 5 is positioned on the cross beam 2. The positions of the rotating member 6 and the fixed member 7 of the locking mechanism are interchanged, the rotating member 6 is positioned on the drive box 1-2, and the fixed member 7 is positioned on the longitudinal beam 3.

Example 6 differs from examples 1 and 2 in that: the desktop support is a single beam.

Claims (10)

1. The utility model provides a quick assembly disassembly's desk support, includes desktop support and the table leg that supports desktop support, desktop support includes longeron (3) and crossbeam (2), and the table leg is located the cross section of longeron (3) and crossbeam (2) to assemble its characterized in that through quick assembly disassembly mechanism and desktop support: the quick disassembly and assembly mechanism comprises a clamping groove mechanism and a locking mechanism,

the clamping groove mechanism comprises a clamping head (5) and a clamping groove (4) which are respectively positioned on the desk leg and the cross beam (2), the main part of the clamping groove (4) transversely extends, the desk leg is assembled with the cross beam (2) in a way that the clamping head (5) is clamped into the main part of the clamping groove (4),

locking mechanical system is including being located rotating member (6) and mounting (7) on table leg and longeron (3) respectively, rotating member (6) rotatable installation, mounting (7) fixed mounting, rotating member (6) and mounting (7) carry out the drive cooperation through helical structure, locking mechanical system drives table leg lateral shifting through the positive and negative rotation action of rotating member (6), and then make dop (5) block in or withdraw from the main part of draw-in groove (4), the assembled relation of locking or relieving table leg and crossbeam (2).

2. The quick release desk bracket as recited in claim 1, further comprising: the matched spiral structures on the rotating part (6) and the fixing part (7) specifically comprise a spiral groove (7-1) and a pin shaft (6-1-1) embedded in the spiral groove (7-1).

3. The quick release desk support of claim 2, wherein: the spiral groove (7-1) is provided with a stopping pit (7-1-1) for preventing the rotating piece (6) from reversing, and the pin shaft (6-1-1) is clamped into the stopping pit (7-1-1) when the clamping head (5) moves to the tail end of the stroke of the clamping groove (4).

4. A quick-release desk stand as defined in claim 2 or 3 in which: the rotating part (6) and the fixing part (7) are nested and matched inside and outside.

5. The quick release desk bracket as recited in claim 4, further comprising: the locking mechanism further comprises a return spring (8), the return spring (8) acts on the rotating piece (6) to drive the rotating piece (6) to return to an unlocking position, when the unlocking position is reached, a pin shaft (6-1-1) on the rotating piece (6) is over against the front end opening of the spiral groove (7-1), and the pin shaft (6-1-1) is embedded into the spiral groove (7-1) through the front end opening of the spiral groove (7-1).

6. The quick release desk support of claim 5, wherein: the rotating part (6) comprises a columnar part (6-1) and an operation cantilever part (6-2) extending out of the columnar part (6-1), the columnar part (6-1) can be rotatably arranged on the longitudinal beam (3) through a rotating shaft (12), and two pin shafts (6-1-1) which are coaxially distributed are arranged on the columnar part (6-1); the fixed part (7) is a hollow cylinder, the rotating part (6) is embedded into an inner hole of the fixed part (7) through the columnar part (6-1), two spiral grooves (7-1) for embedding the pin shaft (6-1-1) are arranged on the periphery of the fixed part (7),

a rotation limiting structure is arranged between the columnar part (6-1) and the rotating shaft (12) and is used for limiting the rotation of the rotating piece (6) when the rotating piece (6) rotates to an unlocking position, the reset spring (8) has pretightening force when the rotating piece (6) is at the unlocking position,

the return spring (8) is a torsion spring, and the return spring (8) is arranged between the columnar part (6-1) of the rotating piece (6) and the rotating shaft (12).

7. The quick release desk bracket as recited in claim 1, further comprising: the table legs are electric lifting table leg uprights (1), the electric lifting table leg uprights (1) comprise lifting upright columns (1-1) and driving boxes (1-2) at the tops of the lifting upright columns (1-1), and the driving boxes (1-2) are assembled with the table top support through a quick assembling and disassembling mechanism.

8. The quick release desk bracket as recited in claim 1, further comprising: crossbeam (2) and longeron (3) be the components of a whole that can function independently structure, the tip of crossbeam (2) passes through tip location structure cartridge and fixes on longeron (3), when locking mechanical system locking table leg and the equipment relation of crossbeam (2), dop (5) move to the stroke end of draw-in groove (4), lock the cartridge relation of crossbeam (2) and longeron (3).

9. The quick release desk support of claim 8, wherein: the end positioning structure comprises a base (9-1) on a longitudinal beam (3), a positioning pin (9-2) longitudinally arranged fixed on the base (9-1) and an inserting positioning groove (9-3) matched with the positioning pin (9-2) on the side wall of a cross beam (2), the head of the positioning pin (9-2) is provided with a limiting end cap (9-2-1), the positioning pin (9-2) is embedded into the inserting positioning groove (9-3) in a locking state, and the base (9-1) and the limiting end cap (9-2-1) are respectively positioned on the inner side and the outer side of the inserting positioning groove (9-3).

10. The quick release desk bracket as recited in claim 6, further comprising: the two beams (2) are arranged, the table legs are arranged between the two beams (2), the table legs and each beam (2) are assembled through two clamping groove mechanisms, the two beams (2) are connected into a whole through a connecting plate (11), the clamping grooves (4) of the clamping groove mechanisms comprise inlet parts extending vertically downwards and main body parts extending transversely, the main body parts of the clamping grooves (4) and the inserting positioning grooves (9-3) at the ends of the beams (2) are horn-shaped in outer width and inner width,

the concrete structure that the columnar part (6-1) can be rotatably arranged on the longitudinal beam (3) through the rotating shaft (12) is as follows: a convex ring (10) is arranged in an inner hole of the columnar part (6-1), the columnar part (6-1) is sleeved on the rotating shaft (12) through the convex ring (10) to rotate, a check ring (13) is fixed at the head end of the rotating shaft (12) through a screw (14), the check ring (13) is blocked outside the convex ring (10) to carry out axial limiting,

the rotation limiting structure between the columnar part (6-1) and the rotating shaft (12) comprises a limiting ring groove (15) on the side surface of the columnar part (6-1) and a limiting pin (16) on the side surface of the rotating shaft (12), the limiting pin (16) is embedded into the limiting ring groove (15) for rotation limiting,

the head end of the limit pin (16) screwed into the rotating shaft (12) is simultaneously pressed against the side surface of the screw (14).

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