Patent Description:
The present application relates to the technical field of work machine, and in particular, to a pin shaft dismounting and mounting device, a frame body connecting structure and work machine.

A frame of work machine is generally provided with a pin shaft. For example, a gantry of a rotary drilling rig is connected to the frame through the pin shaft, both the frame and the gantry of the rotary drilling rig are provided with a pair of connecting seats, which is disposed at intervals corresponding to each other. Each connecting seat includes a pair of connecting plates disposed opposite at intervals and each connecting plate on the gantry and the frame is provided with pin shaft holes correspondingly.

When the gantry and the frame are connected together, the connecting plates on the gantry and the frame are first staggered, pin shaft holes on the gantry and the frame are aligned and the pin shaft is mounted into a corresponding pin shaft hole.

In order to facilitate the disassembly and assembly of the pin shaft in the related art, a piston rod of a cylinder is used as the pin shaft. The piston rod of the cylinder may be controlled to be stretched and mounted into the corresponding pin shaft hole when being mounted while the piston rod of the cylinder may be controlled to be retracted and withdrawn from the pin shaft hole when being dismounted.

However, the piston rod may be worn or deformed after being used for a long time.

Therefore, how to conveniently disassemble and assemble the pin shaft, and solve the problems of wear and deformation of the piston rod has become an important problem to be solved.

<CIT> discloses a device according to the preamble of claim <NUM>. In particular, it discloses that a first pinhole is formed in a first member (<NUM>) in a section facing a second member (<NUM>). A second pinhole is formed in the second member (<NUM>) in a section facing the first member (<NUM>). A connecting pin (<NUM>) is inserted into the first pinhole and the second pinhole from the side of the machine center. A coming-off prevention mechanism <NUM> includes a coming-off prevention lever (<NUM>). The coming-off prevention lever <NUM> can abut the inner end surface <NUM> of the connecting pin (<NUM>). The coming-off prevention lever <NUM> is supported by the second member (<NUM>) to be able to move between an abutting position of abutting the inner end surface (S10L) of the coupling pin (<NUM>) and a non-abutting position of not abutting the inner end surface <NUM>.

<CIT> discloses that a hydraulic power unit mounting/removing device which is constructed to reduce time and labor required for mounting/removing a hydraulic power unit on/from a revolving frame. On the right and left side faces of a main frame <NUM> of the revolving frame, first brackets <NUM> having pin holes 11a are provided protruded to the outside. On the lower face of a hydraulic power unit <NUM>, second brackets <NUM>, <NUM> having pin holes 18a, 19a opposed to the pin holes <NUM> a of the first brackets <NUM> are provided. On the lower face of the hydraulic power unit <NUM>, connection pins <NUM> and hydraulic cylinders <NUM> are mounted which are removably inserted into the pin holes 11a, 19a of the first brackets <NUM> and the second brackets <NUM> and which drive the connection pins <NUM>, respectively.

In view of the problems above, the present invention provides a pin shaft dismounting and mounting device as per claim <NUM>, which can conveniently disassemble and assemble a pin shaft and solve the problems of wear and deformation of a piston rod.

The present application further provides a frame body connecting structure and work machine. The frame body connecting structure includes a first frame body, a second frame body, and the above-mentioned pin shaft dismounting and mounting device. Each of the first frame body and the second frame body is provided with a connecting seat, each connecting seat is provided with a pin shaft, the second frame body is connected with the first frame body through a pin shaft, and the pin shaft is provided with a through hole; the pin shaft dismounting and mounting device is connected with the first frame body or the second frame body and the telescopic rod corresponds to the pin shaft. The work machine according to the present application includes the above-mentioned frame body connecting structure.

By the frame body connecting structure and the work machine according to the present application, the pin shaft may be dismounted and mounted conveniently and the problems of wear and deformation of the piston rod are solved. The beneficial effects of the frame body connecting structure and the work machine is generally similar to those of the above-mentioned pin shaft dismounting and mounting device, and will not be repeated here.

In order to more clearly illustrate the embodiments of the present application or related art, the drawings used in the descriptions of the embodiments or the related art will be briefly described below. The drawings in the following description are only certain embodiments of the present application, and other drawings may be obtained according to the drawings without any creative work for those skilled in the art.

A pin shaft dismounting and mounting device, a frame body connecting structure and work machine according to the embodiments of the present application are described below with reference to <FIG>.

The pin shaft dismounting and mounting device according to the present embodiment includes a linear drive mechanism and a pull rod <NUM>. The pin shaft dismounting and mounting device according to the present embodiment is configured for dismounting and mounting the pin shaft <NUM> on the connecting seat.

Each connecting seat is provided with a pin shaft hole <NUM>. Specifically, the connecting seat may be a connecting seat on the frame body <NUM>. For example, in a rotary drilling rig in the related art, the frame body <NUM> is provided with a connecting seat. The gantry <NUM> of the rotary drilling rig is connected to the connecting seat on the frame body <NUM> through the pin shaft <NUM>. In other embodiments, the connecting seat can also be a pin connecting seat of other devices, for example, a pin connecting seat on a hoisting machine.

The pin shaft <NUM> is mounted inside the pin shaft hole <NUM> of the connecting seat. The pin shaft <NUM> is provided with a through hole <NUM> along its axial direction. The through hole <NUM> may be a central hole of the pin shaft <NUM>, specifically a circular hole.

The linear drive mechanism is disposed on one side of the connecting seat. The linear drive mechanism includes a telescopic rod <NUM> corresponding to the pin shaft hole <NUM>, and having a diameter smaller than a diameter of the pin shaft hole <NUM> and larger than a diameter of the through hole <NUM>. The linear drive mechanism may be an oil cylinder, an air cylinder, a linear motor, etc., and the telescopic rod <NUM> of the linear drive mechanism can perform telescopic movement along its axial direction. The diameter of the telescopic rod <NUM> is smaller than the diameter of the pin shaft hole <NUM>, and thus the telescopic rod <NUM> can perform telescopic movement in the pin shaft hole <NUM>, while the diameter of the telescopic rod <NUM> is larger than the diameter of the through hole <NUM>, and thus the telescopic rod <NUM> can abut against the end portion of the pin shaft <NUM> to drive the pin shafts <NUM> to move.

The outer diameter of the pull rod <NUM> is smaller than the inner diameter of the through hole <NUM> and the pull rod <NUM> can stretch into or out of the through hole <NUM>. A first end of the pull rod <NUM> is provided with an end cap structure <NUM> having a radial length greater than the inner diameter of the through hole <NUM> and a connecting structure is disposed between the second end of the pull rod <NUM> and the end portion of each telescopic rod <NUM>. The length of the main body of the pull rod <NUM> needs to be greater than the length of the pin shaft <NUM> and the second end of the pull rod <NUM> can stretch from an end where the through hole <NUM> of the pin shaft <NUM> is located and stretch out from another end of the pin shaft <NUM>.

When the pin shaft <NUM> is mounted by using the pin shaft dismounting and mounting device according to the present application, the pin shaft <NUM> and the linear drive mechanism are located on opposite sides of the pin shaft hole <NUM> respectively. The pin shaft is <NUM> firstly aligned with the pin shaft hole <NUM>, and the second end of the pull rod <NUM> passes into the through hole <NUM> of the pin shaft <NUM> and is connected to the telescopic rod <NUM> of the linear drive mechanism through the connecting structure after passing through the through hole <NUM>. The first end of the pull rod <NUM> is stuck outside the through hole <NUM> since the first end of the pull rod <NUM> is provided with an end cap structure <NUM>, and the radial length of the end cap structure <NUM> is greater than the inner diameter of the through hole <NUM>. The telescopic rod <NUM> of the linear drive mechanism is controlled to be retracted, and the pin shaft <NUM> is pulled into the pin shaft hole <NUM> through the telescopic rod <NUM> and thus the mounting of the pin shaft <NUM> is completed. When the pin shaft <NUM> needs to be dismounted, and the pin shaft <NUM> may be pushed out from the pin shaft hole <NUM> by controlling the telescopic rod <NUM> of the linear drive mechanism to stretch out.

By the pin shaft dismounting and mounting device of the present application, the pin shaft <NUM> may be dismounted and mounted conveniently and the problems of wear and deformation of the piston rod caused by directly adopting the piston rod as the pin shaft <NUM> are solved.

In a further embodiment, the connecting seat includes a first connecting seat <NUM> and a second connecting seat <NUM>, the first connecting seat <NUM> may include a pair of lugs disposed at intervals and provided with corresponding pin shaft holes <NUM>. Similarly, the second connecting seat <NUM> may include a pair of lugs disposed at intervals and provided with corresponding pin shaft holes <NUM>. In other embodiments, the first connecting seat <NUM> and the second connecting seat <NUM> may also have other structures.

The first connecting seat <NUM> and the second connecting seat <NUM> are disposed at intervals, and the linear driving mechanism is disposed between the first connecting seat <NUM> and the second connecting seat <NUM>. A mounting seat for mounting the linear drive mechanism may be disposed on a corresponding surface of the first connecting seat <NUM> or the second connecting seat <NUM> and the linear drive mechanism may be connected to the mounting seat through bolts.

The linear drive mechanism includes a pair of telescopic rods <NUM>, and the pair of telescopic rods <NUM> correspond to the pin shaft holes <NUM> of the first connecting seat <NUM> and the second connecting seat <NUM> respectively.

In this case, the telescopic rod <NUM> corresponding to the first connecting seat <NUM> of the linear drive mechanism is configured to disassemble and assemble the pin shaft <NUM> of the first connecting seat <NUM>, and the telescopic rod <NUM> corresponding to the second connecting seat <NUM> of the linear driving mechanism is configured to disassemble and assemble the pin shaft <NUM> of the second connecting seat <NUM>.

In a further embodiment, the linear drive mechanism disposed between the first connecting seat <NUM> and the second connecting seat <NUM> is configured as a double-ended oil cylinder <NUM>. Two telescopic rods <NUM> of the double-ended oil cylinder <NUM> are driven by a hydraulic system to perform telescopic movement, and the disassembly and assembly of the pin shafts <NUM> at both ends of the double-ended oil cylinder <NUM> is completed.

The extending or retraction of the telescopic rods <NUM> of the double-ended oil cylinder <NUM> is driven by hydraulic pressure and controlled by a reversing valve <NUM>. The double-ended oil cylinder <NUM> may be single-stage or multi-stage. In other embodiments, the double-ended oil cylinder <NUM> can also be replaced with an air cylinder or a linear motor according to different application occasions. When the linear motor is used, a switch is used for control.

In some embodiments, a manual reversing valve may be used to uniformly control the extending or retraction of the two telescopic rods <NUM> of the double-ended oil cylinder <NUM>. the two telescopic rods <NUM> may be non-synchronous due to uneven resistance and the two telescopic rods <NUM> can be fully stretched or fully retracted finally. Two reversing valves <NUM> may be used to individually control the two telescopic rods <NUM> if the independent movement of the two telescopic rods <NUM> is required.

In order to conveniently connect the double-ended oil cylinder <NUM>, an oil cylinder support base <NUM> may be disposed on corresponding surfaces of the first connecting seat <NUM> and the second connecting seat <NUM>, a bolt hole is disposed on the oil cylinder support base <NUM>, and both ends of a barrel of the double-ended oil cylinder <NUM> are respectively connected to the oil cylinder support base <NUM> by bolts.

Detail description will be made below by taking the double-ended oil cylinder <NUM>, the frame body <NUM> and the gantry <NUM> disposed on the frame body <NUM> as examples.

The dismounting of pin shaft <NUM> for connecting the gantry <NUM> to the frame body <NUM> is described as follows.

In a first step, referring to <FIG>, after the connecting assembly <NUM> between the end portion of the pin shaft <NUM> and the connecting seat is removed, the double-ended oil cylinder <NUM> is operated to stretch the two telescopic rods <NUM>, and the pin shaft <NUM> is then ejected by the telescopic rod <NUM>, the pin shaft <NUM> remains in the pin shaft hole <NUM> of an outer lug plate of the frame body <NUM> (the pin shaft <NUM> is in a disengaged state). In this case, the telescopic rod <NUM> remains inside the pin shaft hole <NUM> and the surface of the telescopic rod <NUM> will not be worn by the pin shaft hole <NUM> since the outer diameter of the telescopic rod <NUM> is smaller than the inner diameter of the pin shaft hole <NUM>.

In a second step, referring to <FIG>, the double-ended oil cylinder <NUM> is operated to retract the two telescopic rods <NUM> and the pin shaft <NUM> remains in the pin shaft hole <NUM> of an outer lug plate of the frame body <NUM>. The gantry <NUM> and the frame body <NUM> can be separated by an external force since the connection between them has been released.

The mounting process of pin shaft <NUM> for connecting the gantry <NUM> to the frame body <NUM> is described as follows.

In a first step, referring to <FIG>, the double-ended oil cylinder <NUM> is operated to stretch the two telescopic rods <NUM> again until two telescopic rods <NUM> come into contact with an inner end surface of the pin shaft <NUM> in the above-mentioned disengaged state. The pull rod <NUM> is inserted into the through hole <NUM> of the pin shaft <NUM> from the outside, and is connected to the telescopic rod <NUM> of the double-ended oil cylinder <NUM>.

In a second step, referring to <FIG>, the double-ended oil cylinder <NUM> is operated to retract the telescopic rods <NUM>, the pin shaft <NUM> is pulled into a hole under the action of the pull rod <NUM>, and then the end portion of the pin shaft <NUM> is connected to the connecting seats through the connecting assembly <NUM>.

In a further embodiment, the linear drive mechanism includes a bracket, a first oil cylinder <NUM> and a second oil cylinder <NUM>.

The bracket is slidably disposed between the first connecting seat <NUM> and the second connecting seat <NUM>, and the bracket is switchable between a first position and a second position. Specifically, the bracket includes a first clamping body <NUM> and a second clamping body <NUM>, the first clamping body <NUM> and the second clamping body <NUM> may have plate-like structures, and the barrels of the first oil cylinder <NUM> and the second oil cylinder <NUM> are sandwiched between the first clamping body <NUM> and the second clamping body <NUM>, and the first clamping body <NUM> and the second clamping body <NUM> are connected by a fastener.

A corresponding surface of the first connecting seat <NUM> and the second connecting seat <NUM> is provided with a seat body, the seat body is provided with a chute <NUM>, and the bracket is slidably matched with the chute <NUM>.

The first oil cylinder <NUM> is disposed on the bracket. When the bracket is in the first position, the telescopic rod <NUM> of the first oil cylinder <NUM> corresponds to the pin shaft hole <NUM> of the first connecting seat <NUM>. The second oil cylinder <NUM> is also disposed on the bracket and disposed side by side with the first oil cylinders <NUM>. When the bracket is in the second position, the telescopic rod <NUM> of the second oil cylinder <NUM> corresponds to the pin shaft hole <NUM> of the second connecting seat <NUM>. The arrangement directions of the first oil cylinder <NUM> and the second oil cylinder <NUM> are opposite since the first connecting seat <NUM> and the second connecting seat <NUM> are respectively disposed at two ends of the linear drive mechanism.

Since the first oil cylinder <NUM> and the second oil cylinder <NUM> are disposed side by side on the bracket, when the pin shaft <NUM> corresponding to the first oil cylinder <NUM> needs to be dismounted and mounted, the bracket can be controlled to slide, and the first oil cylinder <NUM> correspond to the pin shaft hole <NUM> of the first connecting seat <NUM>. After the disassembly and assembly of the pin shaft <NUM> are completed through the first oil cylinder <NUM>, the bracket is controlled to slide to the second position, the second oil cylinder <NUM> corresponds to the pin shaft hole <NUM> of the second connecting seat <NUM>, and the pin shaft <NUM> on the second connecting seat <NUM> can be dismounted and mounted through the second oil cylinder <NUM>. In the pin shaft dismounting and mounting device according to the present embodiment, the overall length formed by the first oil cylinder <NUM> and the second oil cylinder <NUM> is short, which can be adapted to the case where the distance between the first connecting seat <NUM> and the second connecting seat <NUM> is small.

Detail description will be made below by taking the linear drive mechanism consisting of the first oil cylinder <NUM>, the second oil cylinder <NUM> and the bracket, the frame body <NUM> and the gantry <NUM> disposed on the frame body <NUM> as examples.

Dismounting process of the pin shaft <NUM> for connecting the gantry <NUM> to the frame body <NUM> is described as follows.

In a first step, referring to <FIG>, the connecting assembly <NUM> between the end portion of the pin shaft <NUM> and the connecting seat is removed, the bracket is controlled to slide along the chute <NUM>, the telescopic rod <NUM> of the first oil cylinder <NUM> is aligned with the in shaft hole <NUM> on the first connecting seat <NUM>, and the telescopic rod <NUM> of the first oil cylinder <NUM> is then operated to stretch to eject the pin shaft <NUM> on the first connecting seat <NUM> into the pin shaft hole <NUM> of an outer lug plate of the first connecting seat <NUM>.

In a second step, the telescopic rod <NUM> of the first oil cylinder <NUM> is controlled to retract and exit out of the pin shaft hole <NUM> of the first connecting seat <NUM>.

In a third step, as shown in <FIG>, the bracket is operated to slide along the chute <NUM> of the seat body, and the telescopic rod of the second oil cylinder <NUM> is aligned with the pin shaft hole <NUM> of the second connecting seat <NUM>.

In a fourth step, as shown in <FIG>, the telescopic rod <NUM> of the second oil cylinder <NUM> is controlled to eject the pin shaft <NUM> on the second connecting seat <NUM> into the pin shaft hole <NUM> of an outer lug plate of the second connecting seat <NUM>.

In a fifth step, as shown in <FIG>, the telescopic rod <NUM> of the second oil cylinder <NUM> is controlled to be retracted and thus the gantry <NUM> may be disengaged from the frame body <NUM>.

Mounting process of the pin shaft <NUM> for connecting the gantry <NUM> to the frame body <NUM> is opposite of the above-mentioned dismounting process and is described in detail as follows.

In a first step, after the gantry <NUM> is aligned with the pin shaft hole <NUM> of the frame body <NUM>, the telescopic rod <NUM> of the second oil cylinder <NUM> is controlled to stretch into the pin shaft hole <NUM> and comes into contact with the pin shaft <NUM>.

In a second step, the pull rod <NUM> is inserted into the through hole <NUM> of the pin shaft <NUM> of the second connecting seat <NUM>, and is connected with the telescopic rod <NUM> of the second oil cylinder <NUM>.

In a third step, the telescopic rod <NUM> of the second oil cylinder <NUM> is controlled to be retracted, and the pin shaft <NUM> is pulled into the pin shaft hole <NUM> of the second connecting seat <NUM> through the pull rod <NUM> to mounting a pin shaft <NUM>.

In a fourth step, the pull rod <NUM> in the pin shaft <NUM> of the second connecting seat <NUM> is removed, and the bracket is controlled to slide along the chute <NUM> of the seat body and thus the telescopic rod <NUM> of the first oil cylinder <NUM> is aligned with the pin shaft hole <NUM> of the first connecting seat <NUM>.

In a fifth step, the telescopic rod <NUM> of the first oil cylinder <NUM> is controlled to stretch into the pin shaft hole <NUM> of the first connecting seat <NUM> and the telescopic rod <NUM> of the first oil cylinder <NUM> comes into contact with the pin shaft <NUM> on the first connecting seat <NUM>.

In a sixth step, the pull rod <NUM> is inserted into the through hole <NUM> of the pin shaft <NUM> of the first connecting seat <NUM>, and is connected to the telescopic rod <NUM> of the first oil cylinder <NUM>.

In a seventh step, the telescopic rod <NUM> of the first oil cylinder <NUM> is controlled to be retracted, and the pin shaft <NUM> is pulled into the pin shaft hole <NUM> of the first connecting seat <NUM> through the pull rod <NUM> to mount another pin shaft <NUM>.

In order to conveniently connect the pull rod <NUM> and the telescopic rod <NUM>, in a further embodiment, a connecting structure between the pull rod <NUM> and the telescopic rod <NUM> includes an external thread <NUM> disposed at a second end of the pull rod <NUM> and a threaded hole <NUM> disposed on the end face of the telescopic rod <NUM> where the external thread <NUM> is fitted with threaded hole <NUM>.

In this case, the connection between the pull rod <NUM> and the telescopic rod <NUM> can be realized by screwing the second end of the pull rod <NUM> into the threaded hole <NUM> of the telescopic rod <NUM>.

In other embodiments, the connecting structure between the pull rod <NUM> and the telescopic rod <NUM> can also be configured as a snap connection or a keyway connection or the like.

In order to conveniently rotate the pull rod <NUM>, a head-screwing structure <NUM> may be disposed on an end surface of the end cap structure <NUM> of the pull rod <NUM>, and the head-screwing structure <NUM> may be an elongated protrusion for the operator to hold and rotate.

In a further embodiment, guide grooves <NUM> are disposed on the corresponding surfaces of the first connecting seat <NUM> and the second connecting seat <NUM>, two ends of the guide groove <NUM> have closed structures, and guide posts <NUM> are disposed on two sides of the bracket and are slidably matched with the guide groove <NUM>, that is, the guide post <NUM> can slide between a first end and a second end of the guide groove <NUM>. When the bracket is in the first position, the guide post <NUM> abuts against the first end of the guide groove <NUM>; when the bracket is in the second position, the guide post <NUM> abuts against the second end of the guide groove <NUM>, and two ends of the guide groove <NUM> can have a limiting effect on the guide post <NUM>.

When the bracket is controlled to slide along the chute <NUM>, the guide post <NUM> on the bracket is displaced along the chute <NUM> at the same time. When the guide post <NUM> is displaced to the first end of the guide groove <NUM>, the bracket can no longer move and is in the first position state, and the telescopic rod <NUM> of the first oil cylinder <NUM> corresponds to the pin shaft hole <NUM> of the first connecting seat <NUM>. Similarly, when the guide post <NUM> is displaced to the second end of the guide groove <NUM>, the bracket can no longer move and is in the second position, and the telescopic rod <NUM> of the second oil cylinder <NUM> corresponds to the pin shaft hole <NUM> of the second connecting seat <NUM>. By this arrangement, the first oil cylinder <NUM> and the second oil cylinder <NUM> can be quickly aligned with the pin shaft hole <NUM>.

After the pin shaft <NUM> is mounted in place, in a further embodiment, in order to improve the connection stability between the pin shaft <NUM> and the connecting seats, a connecting assembly is detachably disposed at the end portion of the pin shaft <NUM> and is used for being connected with sides of the connecting seats.

In an embodiment, the end portion of the pin shaft <NUM> is provided with an annular groove <NUM>, and the connecting assembly <NUM> may be a non-enclosed connecting flange sleeved in the annular groove <NUM>. The connecting flange can be sleeved within the annular groove <NUM> since the connecting flange is a non-enclosed structure. The connecting seat and the connecting flange are provided with corresponding bolt holes, the connecting flange can be fixedly connected to the connecting assembly <NUM> by bolts inserted inside the bolt holes and then the pin shaft <NUM> is fixedly connected.

An embodiment of the present application further provides a frame body connecting structure, which includes a first frame body and a second frame body. In some embodiments, the first frame body may be the frame body <NUM> in the above-mentioned embodiments, and the second frame body may be the gantry <NUM> in the above-mentioned embodiments. In other embodiments, the first frame body and the second frame body may also be other frame bodies used on the mechanical equipment.

Each of the first frame body and the second frame body is provided with a connecting seat, each connecting seat is provided with a pin shaft hole, the second frame body is connected with the first frame body through a pin shaft, and the pin shaft is provided with a through hole.

The pin shaft dismounting and mounting device is connected with the first frame body or the second frame body, the pin shaft dismounting and mounting device may be the pin shaft dismounting and mounting device in any of the above embodiments, and the telescopic rod corresponds to the pin shaft.

In some embodiments, the connecting seat includes a first connecting seat <NUM> and a second connecting seat <NUM> disposed at intervals, and a bracket is slidably disposed between the first connecting seat <NUM> and the second connecting seat <NUM>, and may be switchable between a first position in which the telescopic rod of the first oil cylinder <NUM> corresponds to the pin shaft hole of the first connecting seat <NUM> and a second position in which the telescopic rod of the second oil cylinder <NUM> corresponds to the pin shaft hole of the second connecting seat <NUM>.

An embodiment of the present application further provides work machine, including the above-mentioned frame body connecting structure.

By the frame body connecting structure and the work machine according to the present embodiment, the pin shaft <NUM> can be dismounted and mounted conveniently, and the problems of wear and deformation of the piston rod are solved.

Claim 1:
A pin shaft dismounting and mounting device for dismounting and mounting a pin shaft (<NUM>) on a connecting seat, the pin shaft (<NUM>) is provided with a through hole (<NUM>) along an axial direction of the pin shaft, comprising:
a linear drive mechanism, comprising telescopic rods (<NUM>), the telescopic rods (<NUM>) being extendable from both ends of the linear drive mechanism; and
a pull rod (<NUM>) configured to pass through the through hole (<NUM>), a first end of the pull rod (<NUM>) being provided with an end cap structure (<NUM>), a connecting structure being disposed between a second end of the pull rod (<NUM>) and an end portion of each telescopic rod (<NUM>); characterised in that:
a length of the main body of the pull rod (<NUM>) is greater than a length of the pin shaft (<NUM>) and the second end of the pull rod (<NUM>) stretches from an end where the through hole (<NUM>) of the pin shaft (<NUM>) is located and stretches out from another end of the pin shaft (<NUM>),
a diameter of each telescopic rod (<NUM>) is larger than a diameter of the through hole (<NUM>);
the pin shaft (<NUM>) is pulled into a pin shaft hole (<NUM>) or pushed out from a pin shaft hole (<NUM>) through one of the telescopic rod (<NUM>) of the linear drive mechanism.