CN111468535A - Four-wheel roller mill - Google Patents

Abstract

The invention relates to a four-wheel rolling mill, comprising a square linked telescopic frame, four movable mounting frames and four roller wheels; the square linked telescopic frame is driven by a first driving mechanism to extend outward or inward in a linked manner. shrink; the four mobile mounting frames are installed on the four sides of the linked telescopic frame, and can be moved and adjusted along the sides of the square; four roller wheels are correspondingly installed on the four mobile mounting frames, and the The rolling channel is formed between the outer peripheral surfaces through the adjustment of the linkage telescopic frame and the movable mounting frame. The four-wheel rolling mill of the present invention has novel design, compact structure, bright spots and new techniques; it can process wires of various sizes and cross-sections, such as square, trapezoid, flat, etc., with wide applicability, reliable processing and high precision. The wire exit effect is good, the stability of the working condition is excellent, and the setting of high-quality new products is realized.

Description

A four-wheel rolling mill

technical field

The invention relates to the field of rolling mills, in particular to a four-wheel rolling mill.

Background technique

With the rapid development of society and economy, the use of rolling mills has become more and more extensive and diversified. The rolling mill is the equipment that realizes the metal rolling process, which generally refers to the equipment that completes the whole process of rolling material production. Rolling system, drive system, hydraulic system, control system, roll removal device, etc. constitute the main working parts and tools on the rolling mill to produce continuous plastic deformation of metal. The roll is mainly composed of three parts: roll body, roll neck and shaft head. The roll body is the side part of the roll that actually participates in rolling the metal. It has a smooth cylindrical or grooved surface across the entire wheel. The roll neck is installed in the bearing, and the rolling force is transmitted to the frame through the bearing seat and the pressing device. Some workpieces need to be rolled on four sides, and a four-wheel press roll machine is required.

However, most of the roller heads of the existing four-wheel press roller machine are manually adjusted, and most of them are unidirectional adjustment of feeding. Even if there is a dual-axis adjustment, the adjustment operation is relatively complicated; therefore, it does not meet the existing needs. In this regard, we propose a new type of four-wheel rolling mill.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a four-wheel rolling mill, which has a novel design, compact structure, bright spots and new art; it can process wires with various sizes and cross-sections, such as square, trapezoid, flat, etc., and has wide applicability. , Reliable processing, high precision, good outlet effect, and excellent working condition stability.

The technical scheme adopted by the present invention to solve the technical problem is as follows: a four-wheel rolling mill includes a square linkage telescopic frame, four movable mounting frames, and four roller wheels; the square linkage telescopic frame is driven by a first driving mechanism to carry out The linkage type stretches outward or contracts inward; the four mobile mounting frames are installed on the four sides of the square of the linkage telescopic frame, and can be moved and adjusted along the sides of the square; the four roller wheels are correspondingly installed on the four mobile On the mounting frame, the rolling channel is formed between the outer peripheral surfaces of the four roller wheels through the adjustment of the linkage telescopic frame and the movable mounting frame.

Further, the linkage telescopic frame includes installation blocks located at four vertices of the square, a main shaft forming the four sides of the square, and the first drive mechanism; the installation block is provided with a shaft hole; the main shaft serving as one side of the square One end is connected to the drive end of the first drive mechanism after passing through the shaft hole of one mounting block, and the other end is connected and fixed with the side position of the other mounting block relative to the shaft hole, and the first drive mechanism is matched with the mounting block. Fixed connection; the four main shafts are connected in the same way, and each first drive mechanism is used to control the expansion and contraction of the main shaft, to control the distance between the mounting block fixed to it and the mounting block fixed at the other end of the connecting main shaft, and then control The distance between the two sets of opposite rolls, that is, the size of the rolling channel is controlled.

Further, each of the mobile mounting racks includes a roller wheel mounting rack; the roller wheel mounting rack is provided with a bushing; the roller wheel mounting rack is sleeved on the main shaft through the bushing; the roller wheel mounting rack faces One end of the inner side of the square linkage telescopic frame is connected to the roll wheel; the roll wheel mounting frame is used to move along the main shaft, thereby driving the roll wheel to move to form a rolling channel.

Further, each of the mobile mounting racks is also provided with a second driving mechanism at both ends along the main axis direction; any one of the two second driving mechanisms is used to drive the mobile mounting rack to move along the main axis. , and another second driving mechanism is used for positioning and locking the installation frame in the axial direction after the installation frame moves to the designated position.

Further, an end of the roll wheel mounting frame facing the outer side of the square linkage telescopic frame is fixed with a gripping drive mechanism; the gripping drive mechanism is used to grip or release the main shaft, so that the mobile installation frame and the main shaft are in the circumference of the main shaft. Lock up to secure or loosen.

Further, the shaft sleeve has a through hole at a position corresponding to the drive end of the gripping drive mechanism; the drive end of the gripping drive mechanism extends into the through hole and cooperates with the main shaft to grip or release.

Further, a group of oppositely arranged rollers among the four described rollers is further coupled with a third driving mechanism respectively, and the third driving mechanism is used to drive the group of oppositely arranged rollers to rotate.

Further, both of the third driving mechanisms include a driven gear coaxially fixed on the side of the roll wheel, a transmission gear meshed with the driven gear, and a drive shaft fixed coaxially with the transmission gear; two The drive shafts are commonly connected to the drive elements for maintaining synchronous rotation.

Further, the rolling mill further includes a bottom plate; the linkage telescopic frame and the four movable mounting frames are placed on the bottom plate through the roller wheel mounting frame; the bottom side of the four mounting blocks of the linkage telescopic frame is also provided with a floating type Lifting device; the floating lifting device is used for locking and fixing the linkage telescopic frame and the bottom plate, or loosening the linkage telescopic frame relative to the bottom plate so that the linkage telescopic frame and the four mobile mounting frames are all floated, so that the linkage telescopic frame can be controlled Perform a stretch action.

Further, the floating lifting device includes a sliding seat and a sliding table; the sliding table is fixed to the bottom plate; the sliding seat is installed on the moving end of the sliding table; a lifting driving mechanism is also arranged under the bottom plate; The driving end of the driving mechanism protrudes upward through the bottom plate, the sliding table and the sliding seat and is connected with the bottom side of the corresponding mounting block; the driving end of the lifting driving mechanism is located in the area between the sliding seat and the mounting block. A floating spring; the outer side of the floating spring is located on the sliding seat, and an upper pressure block is fixed; the top surface of the lift drive mechanism is also fixed with a lower pressure block; the lift drive mechanism is used for installation by retracting the drive end The block is lowered and pressed on the upper pressure block, and the lower pressure block is pressed against the bottom side of the bottom plate; it is also used to extend through the driving end, so that the mounting block rises and separates from the upper pressure block, and the lower pressure block is separated from the bottom plate, and the floating The spring supports the mounting block to float the linkage telescopic frame and the four movable mounting frames; the bottom plate is provided with a long hole at the position where the driving end of the lifting drive mechanism passes through, which is used for the lifting and lowering drive mechanism when the linkage telescopic frame is extended and retracted. The drive end provides room for movement.

Advantages of the present invention: a four-wheel rolling mill of the present invention adopts the design of a linkage telescopic frame, a mobile mounting frame and a rolling wheel to control the size of the rolling channel formed by the four rolling wheels, thereby satisfying the rolling requirements of wires of different sizes. The first drive mechanism replaces manual adjustment, and the size control is more accurate; the linkage design of the linkage telescopic frame makes the adjustment of the four roller wheels simpler and more convenient; the mobile installation frame can be moved left and right, so that the four roller wheels The wheel surface and the side surface can cooperate with each other to form a closed rolling channel to avoid burrs generated during the rolling process; the movable mounting frame is adjusted along the main axis direction through the second driving mechanism, and the two second driving mechanisms form a mutual The lock makes the mobile mounting frame more accurately positioned in the axial direction of the main shaft, preventing loosening and improving the rolling accuracy; the adopted clamping drive mechanism can tightly position the mobile installation frame and the main shaft in the circumferential direction of the main shaft , to further improve the stability of the rolling process and ensure the accuracy of the rolling; using a floating lifting device, when the size is adjusted, the whole can be lifted floatingly, which is convenient for the adjustment of the linkage telescopic frame and the mobile mounting frame, and can be used in the After the adjustment is completed, it is lowered again and locked and fixed with the fixing plate, and the stability of the whole mechanism is strengthened; the four-wheel rolling mill of the present invention has a novel design and Flat shape, etc., wide applicability, reliable processing, high precision and good stability.

Description of drawings

1 is a schematic perspective view of a four-wheel rolling mill according to an embodiment;

2 is a schematic top view of a four-wheel rolling mill according to an embodiment;

3 is a schematic diagram of a linkage telescopic frame of a four-wheel rolling mill according to an embodiment;

4 is a schematic diagram of the assembly of a mobile mounting frame, a roller wheel, and a second drive mechanism of a four-wheel roller mill according to an embodiment;

FIG. 5 is a schematic front view of a four-wheel rolling mill according to an embodiment.

Detailed ways

In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and do not limit the protection scope of the present invention.

Example

As shown in FIGS. 1 to 5 , this embodiment provides a four-wheel rolling mill, including a square linked telescopic frame 1 , four movable mounting frames 2 , and four roller wheels 4 ; the square linked telescopic frame 1 passes through the first A driving mechanism 102 drives to extend or retract in a linked manner; the four movable mounting frames 2 are installed on the four sides of the square of the linked telescopic frame 1, and can be moved and adjusted along the sides of the square; four roller wheels 4 is correspondingly installed on the four mobile mounting frames 2, and the rolling channel 7 is formed between the outer peripheral surfaces of the four roller wheels 4 through the adjustment of the linkage telescopic frame 1 and the mobile mounting frame 2; among them, the linkage type refers to the telescopic When the four sides of the frame 1 are connected, they are stretched outward or contracted inward.

In the four-wheel rolling mill of this embodiment, when the cross-section of the processed wire rod is square (square or rectangular), the rolling surface of the rolling wheel used is perpendicular to the side of the wheel, that is, the two sides of the rolling wheel are concentric and the diameter In the same way, the four roll wheels cross each other, that is, the side surface of one roll wheel overlaps with the wheel surface part of the adjacent one roll wheel, so that the non-overlapping wheel surfaces of the four roll wheels form a square rolling channel; When the cross-section of the processed wire rod is trapezoid or other quadrilateral with at least one set of opposite sides parallel, the wheel surfaces of the two oppositely distributed roller wheels in one group are perpendicular to the side of the wheel, and the other group of two oppositely distributed roller wheels are. The surface of the wheel and the side of the wheel are non-perpendicular, and the angle between the surface and the side of the wheel depends on the inner angle of the desired product, that is, the two sides of the roller wheel are concentric and have different diameters. The angle and length of the wheel surface of the non-vertical roller wheel Corresponding to the size of the wire to be added, the side surfaces of a set of non-vertical roll wheels partially overlap with the wheel surfaces of a set of vertical roll wheels, so that the non-overlapping wheel surfaces of the four roll wheels form a set of opposite sides parallel to each other. The quadrilateral rolling channel; when the processed wire is flat, only one set of two oppositely distributed rolls can be used; according to this design idea, it can be processed including but not limited to square, trapezoidal, flat cross-section wire , and other similar special-shaped wires can also be processed.

In a four-wheel roller mill of this embodiment, the linkage telescopic frame 1 includes mounting blocks 101 located at four vertices of a square, a main shaft 103 forming four sides of the square, and the first drive mechanism 102; the first drive mechanism 102; The mounting block 101 is provided with a shaft hole; one end of the main shaft 103 as one side of the square is connected to the driving end of the first driving mechanism 102 after passing through the shaft hole of one mounting block 101, and the other end is connected with the relative shaft of the other mounting block 101. The side positions of the holes are connected and fixed, and the first driving mechanism 102 is fixedly connected with its matching mounting block 101; the four main shafts 103 are connected in the same way, and each first driving mechanism 102 is used to control the expansion and contraction of the main shaft 103 to control its The distance between the fixed installation block and the fixed installation block at the other end of the connecting main shaft 103 further controls the wheel surface spacing of the two sets of oppositely arranged two roll wheels 4, that is, controls the size of the rolling channel 7; wherein , and the first drive mechanism 102 controls the extension and retraction of the main shaft to achieve linkage outward extension or inward retraction.

In the four-wheel rolling mill of this embodiment, each of the mobile mounting frames 2 includes a rolling wheel mounting frame 201; the rolling wheel mounting frame 201 is provided with a bushing 202; the rolling wheel mounting frame 201 The shaft sleeve 202 is sleeved on the main shaft 103; the end of the roller wheel mounting frame 201 facing the inner side of the square linkage telescopic frame 1 is connected to the roller wheel 4; the roller wheel mounting frame 201 is used to move along the main shaft 103, and then The rolling channel is formed by driving the roller wheel 4 to move.

In the four-wheel rolling mill of this embodiment, each of the moving mounting frames 2 is further provided with a second driving mechanism 3 at both ends along the main axis direction; any one of the two second driving mechanisms 3 is first Two driving mechanisms are used to drive the movable mounting frame 2 to move along the main shaft, and another second driving mechanism 3 is used to position and lock the mounting frame 2 in the axial direction after the installation frame 2 moves to a designated position; wherein, the main shaft 103 is close to the two Each end position is provided with a threaded section 104; the second driving mechanism is a screw transmission mechanism, the threaded section 104 of the main shaft is used as the screw, the screw nut cooperates with the threaded section 104, and the outer circumference of the screw nut is provided with a driven The second driving mechanism also includes a second driving element (motor), and the output end of the second driving element is fixed with a driving gear; the driving gear is meshed with the driven teeth; The screw nut of the movable tooth rotates, and the screw nut moves along the main shaft under the cooperation of the threaded section of the main shaft, thereby driving the mobile mounting frame 2 to move along the main shaft; when adjusting the position of the mobile mounting frame 2 on the main shaft 103, two second drives are required The mechanisms act synchronously. After the adjustment is completed, one does not move and the other continues to act, so that the mounting bracket 2 is locked on the main shaft 103 in the axial direction.

In a four-wheel roller machine of this embodiment, a gripping drive mechanism 203 is fixed at one end of the roller wheel mounting frame 201 facing the outer side of the square linkage telescopic frame 1; the gripping drive mechanism 203 is used for gripping or releasing The main shaft 103 is turned on, so that the movable mounting frame 2 and the main shaft 103 are locked, fixed or released in the circumferential direction of the main shaft 103 .

In a four-wheel rolling mill of this embodiment, the bushing 202 has a through hole at a position corresponding to the driving end of the gripping driving mechanism 203; the driving end of the gripping driving mechanism 203 extends into the through hole and is The main shaft 103 cooperates to hold or release.

In the four-wheel rolling mill of the present embodiment, a group of the oppositely arranged roll wheels 4 among the four said rolling wheels 4 is further coupled with a third driving mechanism 8 respectively, and the third driving mechanism 8 is used for The set of oppositely arranged roller wheels 4 are driven to rotate.

In the four-wheel rolling mill of this embodiment, the two third driving mechanisms 8 both include a driven gear 801 fixed on the side of the roll wheel 4 in a coaxial manner, and a transmission gear 802 meshing with the driven gear. 2. A drive shaft 803 fixed coaxially with the transmission gear 802; the two drive shafts 803 are jointly connected to the drive element for maintaining synchronous rotation.

In a four-wheel rolling mill of this embodiment, the rolling mill further includes a bottom plate 6; the linked telescopic frame 1 and the four moving mounting frames 2 are placed on the bottom plate 6 through the rolling wheel mounting frame 201; The bottom side of the four mounting blocks 101 of the frame 1 is also provided with a floating lifting device 5; the floating lifting device 5 is used to lock and fix the linkage telescopic frame 1 and the bottom plate 6, or to connect the linkage telescopic frame 1 relative to the bottom plate. When loosening, the linked telescopic frame 1 and the four mobile mounting frames 2 are all floated up, so that the linked telescopic frame 1 can be controlled to perform telescopic action.

In a four-wheel rolling mill in this embodiment, the floating lifting device 5 includes a sliding seat 501 and a sliding table 502 ; the sliding table 502 is fixed to the bottom plate 6 ; the sliding seat 501 is installed on the moving end of the sliding table 502 The bottom of the bottom plate 6 is also provided with a lift drive mechanism 503; the drive end of the lift drive mechanism 503 extends upward through the bottom plate 6, the sliding table 502 and the sliding seat 501 and is connected to the bottom side of the corresponding mounting block 101 ; The driving end of the lift drive mechanism 503 is located in the area between the sliding seat 501 and the mounting block 101 is also sleeved with a floating spring 504; the outer side of the floating spring 504 is located on the sliding seat 501 and is also fixed with an upper pressure block 505 ; The top surface of the lift driving mechanism 503 is also fixed with a lower pressing block 506; 506 is pressed on the bottom side of the bottom plate; it is also used to extend through the driving end, so that the mounting block 101 is lifted up and separated from the upper pressing block 505, and the lower pressing block 506 is separated from the bottom plate, and the mounting block is supported by the floating spring, so that the linkage telescopic frame 1 and the The four mobile mounting frames 2 are floated up; the bottom plate 6 is provided with a long hole at the position where the driving end of the lifting driving mechanism 503 passes through, which is used to provide a moving space.

In the four-wheel rolling mill of this embodiment, when processing is completed after assembly, it must first be adjusted according to the size to be processed. At this time, the overall gravity is borne by the floating springs at the four corners, and the bottom ends of the floating springs are pressed on the sliding seat. At this time, the linkage telescopic frame and the mobile mounting frame are both separated from the bottom plate; then, the rolling mechanism is adjusted by the first drive mechanism. The size of the length and width of the channel is determined; after that, the movable mounting frame is driven by the second drive mechanism to move along the main shaft, so that the side of each roller is in close contact with the surface of the adjacent roller, and the four rollers are attached to each other. Then, a closed rolling channel is obtained (taking a square rolling channel as an example), and then the two second driving mechanisms cooperate to lock the mobile mounting frame and the main shaft in the axial direction, and then through the tightening driving mechanism, The mobile mounting frame and the main shaft are tightly fixed in the circumferential direction; at this time, the wire to be rolled is sent into the rolling channel, and the third drive mechanism is activated to make the corresponding group of rollers rotate synchronously, driving the wire while rolling. Output, another group of rollers is driven, and the four rollers jointly roll the wire.

A four-wheel rolling mill in this embodiment adopts the design of a linked telescopic frame, a mobile mounting frame, and a roll wheel to control the size of the rolling channel formed by the four roll wheels, thereby meeting the rolling requirements of wires of different sizes; The first drive mechanism replaces manual adjustment, and the size control is more accurate; the linkage design of the linkage telescopic frame makes the adjustment of the four roller wheels simpler and more convenient; the mobile installation frame can be moved left and right, so that the wheel surface and side surface of the four roller wheels can be adjusted more easily and conveniently. It can cooperate with each other to form a closed rolling channel to avoid burrs generated during the rolling process; the mobile mounting frame is adjusted along the main axis direction through the second driving mechanism, and is interlocked through the two second driving mechanisms to make the movement The mounting frame can be positioned more precisely in the axial direction of the main shaft to prevent loosening and improve the rolling accuracy; the adopted clamping drive mechanism can tightly position the mobile installation frame and the main shaft in the circumferential direction of the main shaft to further improve the rolling The stability during processing ensures the accuracy of rolling; the floating lifting device is adopted, and the whole can be lifted floating when the size is adjusted, which is convenient for the adjustment of the linkage telescopic frame and the mobile mounting frame, and can be re-adjusted after the adjustment is completed. It is lowered and locked and fixed with the fixing plate, and the stability of the whole mechanism is strengthened; the four-wheel rolling mill of this embodiment has a novel design and a compact structure, and can process wires of various sizes and cross-sections, such as square, rectangular, trapezoidal, flat, etc. , Wide applicability, reliable processing, high precision and good stability.

The above embodiments should not limit the present invention in any way, and all technical solutions obtained by means of equivalent replacement or equivalent conversion fall within the protection scope of the present invention.

Claims (10)

1. A four-wheel roller mill is characterized in that: the device comprises a square linkage telescopic frame, four movable mounting frames and four rolling wheels; the square linkage telescopic frame is driven by a first driving mechanism to perform linkage type outward extension or inward contraction; the four movable mounting frames are arranged on four sides of the square of the linkage telescopic frame and can be movably adjusted along the square sides; four rolling wheels are correspondingly arranged on the four movable mounting frames, and rolling channels are formed between the peripheral wheel surfaces of the four rolling wheels through the adjustment of the linkage expansion bracket and the movable mounting frames.

2. The four-wheel roller mill according to claim 1, characterized in that: the linkage telescopic frame comprises mounting blocks positioned at four vertexes of a square, main shafts forming four sides of the square and the first driving mechanism; the mounting block is provided with a shaft hole; one end of a main shaft serving as one side of the square penetrates through the shaft hole of one mounting block and then is connected with the driving end of a first driving mechanism, the other end of the main shaft is fixedly connected with the side position, relative to the shaft hole, of the other mounting block, and the first driving mechanism is fixedly connected with the mounting block matched with the first driving mechanism; the four main shafts are connected in the same mode, and each first driving mechanism is used for controlling the extension and retraction of the main shaft to control the distance between the fixed mounting block and the mounting block fixed at the other end of the main shaft, so that the wheel surface space of two groups of oppositely arranged rolling wheels is controlled, namely the size of a rolling channel is controlled.

3. A four-wheel roller mill according to claim 2, characterized in that: each movable mounting rack comprises a roller mounting rack; a shaft sleeve is arranged in the rolling wheel mounting frame; the roller wheel mounting rack is sleeved on the main shaft through a shaft sleeve; one end of the rolling wheel mounting rack facing the inner side of the square linkage telescopic rack is connected with the rolling wheel; the rolling wheel mounting rack is used for moving along the main shaft so as to drive the rolling wheel to move to form a rolling channel.

4. A four-wheel roller mill according to claim 3, characterized in that: each movable mounting frame is also provided with a second driving mechanism at two ends along the direction of the main shaft; any one of the two second driving mechanisms is used for driving the movable mounting frame to move along the main shaft, and the other second driving mechanism is used for positioning and locking the mounting frame in the axial direction after the mounting frame moves to the designated position.

5. The four-wheel roller mill according to claim 4, characterized in that: one end of the rolling wheel mounting frame, which faces the outer side of the square linkage telescopic frame, is fixed with a holding driving mechanism; the holding driving mechanism is used for holding or releasing the main shaft, so that the movable mounting frame and the main shaft are locked or loosened in the circumferential direction of the main shaft.

6. The four-wheel roller mill according to claim 5, characterized in that: the shaft sleeve is provided with a through hole at a position corresponding to the driving end of the enclasping driving mechanism; and the driving end of the clasping driving mechanism extends into the through hole and then is matched with the main shaft to clasp or release.

7. A four-wheel roller mill according to any one of claims 1 to 6, characterized in that: one group of the four rolling wheels which are arranged oppositely is also respectively connected with a third driving mechanism which is used for driving the group of the rolling wheels which are arranged oppositely to rotate.

8. The four-wheel roller mill according to claim 7, characterized in that: the two third driving mechanisms comprise driven gears which are coaxially fixed on the side surfaces of the roller wheels, transmission gears which are in meshing transmission with the driven gears, and driving shafts which are coaxially fixed with the transmission gears; the two drive shafts are connected together with a drive element for synchronous rotation.

9. A four-wheel roller mill according to any one of claims 3 to 6, characterized in that: the roller machine also comprises a bottom plate; the linkage telescopic frame and the four movable mounting frames are arranged on the bottom plate through the rolling wheel mounting frame; floating type lifting devices are further arranged on the bottom sides of the four mounting blocks of the linkage telescopic frame; the floating type lifting device is used for locking and fixing the linkage telescopic frame and the bottom plate or loosening the linkage telescopic frame relative to the bottom plate to enable the linkage telescopic frame and the four movable mounting frames to float so as to control the linkage telescopic frame to perform telescopic action.

10. The four-wheel roller mill of claim 9, wherein: the floating type lifting device comprises a sliding seat and a sliding table; the sliding table is fixed with the bottom plate; the sliding seat is arranged on the moving end of the sliding table; a lifting driving mechanism is further arranged below the bottom plate; the driving end of the lifting driving mechanism extends upwards to penetrate through the bottom plate, the sliding table and the sliding seat and then is connected with the bottom side of the corresponding mounting block; a floating spring is sleeved in an area, between the sliding seat and the mounting block, of the driving end of the lifting driving mechanism; an upper pressing block is also fixed on the sliding seat at the outer side of the floating spring; a lower pressing block is fixed on the top surface of the lifting driving mechanism; the lifting driving mechanism is used for enabling the mounting block to descend and press the upper pressing block through retraction of the driving end, and enabling the lower pressing block to be pressed against the bottom side of the bottom plate; the linkage telescopic frame and the four movable mounting frames are floated by supporting the mounting block through the floating spring; and a long hole is formed in the position, through which the driving end of the lifting driving mechanism penetrates, of the bottom plate, and is used for providing a moving space for the driving end of the lifting driving mechanism when the linkage expansion bracket expands and contracts.

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