A workbench structure for a vertical machining center

Abstract

The present invention discloses a worktable structure for a vertical machining center, comprising a worktable main body, a work installation seam, a connecting platform, a movable seat, and a guide clamp, and also includes: a middle docking component, comprising a partition plate arranged at the middle of the inner side of the connecting platform, a contrast seam corresponding to the installation seam is opened on the partition plate, a plurality of spacer blocks arranged at intervals are filled in the contrast seam, a plurality of through cavities are formed between the plurality of spacer blocks, and a clustering member is arranged inside the through cavities; an adaptable component, comprising a positioning seat fixed on the partition plate, a lateral positioning member is arranged on the inner side of the positioning seat; a clustering push-up component, comprising a tie member arranged below the clustering member, a power member fixed to the inner bottom of the connecting platform is arranged at the lower end of the tie member, after the clustering member is opened, the power member drives the tie member to move upward and retracts the clustering member inward, so that the clustering member is tightly attached to the outer side of the workpiece. The present invention can improve the yield rate of the workpiece, and thus improve the accuracy of the machining center.

Description

Technical Field

[0001] The present invention relates to workpiece processing, in particular to a workbench structure for a vertical machining center. Background Art

[0002] A vertical machining center refers to a machining center in which the spindle axis is vertically arranged with respect to the workbench, and is mainly applicable to machining complex parts such as plate-like, disc-like, molds and small shell-like parts. The vertical machining center can complete processes such as milling, boring, drilling, tapping and cutting threads. The accuracy, strength and stability of the machine tool workbench have a direct impact on the quality, accuracy and machining efficiency of the machined parts in machining.

[0003] When installing a workpiece on a traditional workbench, it is mostly fixed by clamping the workpiece in the gap of the workbench, so as to achieve the stability of the workpiece during machining. Although it can initially form a fixation, when the machining accuracy is relatively high, the workpiece is still prone to jump due to the contact and separation of the machining tool head, and errors are likely to occur during multi-sided machining. Therefore, corresponding tooling is provided in the workbench in the prior art to fix the workpiece, but due to the different sizes of the workpieces, the tooling needs to be continuously replaced, and the tooling itself also needs to repeatedly replace the special fixing structure, thereby increasing the fixing difficulty of the workpiece, further weakening the machining accuracy of the machining center, and reducing the yield rate of batch workpieces.

[0004] Therefore, the present case aims to provide a workbench structure for a vertical machining center, which can not only effectively fix the installed workpiece, but also does not directly act on the workpiece itself to avoid damaging the workpiece, thereby improving the yield rate of the workpiece and further improving the accuracy of the machining center. Summary of the Invention

[0005] The present invention provides a workbench structure for a vertical machining center, which can effectively solve the above problems.

[0006] The present invention is implemented as follows:

[0007] A workbench structure for a vertical machining center includes a workbench main body, on which a plurality of installation slots for installing workpieces are provided. A connecting platform is connected to the lower end of the workbench main body, and a moving seat cooperating with a lead screw is connected to the lower end of the connecting platform. Guide clamps fixed below the connecting platform are arranged at both ends of the moving seat. The workbench structure further includes:

[0008] A middle docking assembly comprises a partition plate arranged at the middle of the inner side of the connecting platform, a contrasting seam corresponding to the installation seam is opened on the partition plate, the contrasting seam is filled with a plurality of spaced blocking blocks, a plurality of through cavities are formed between the plurality of blocking blocks, a clustering piece is arranged inside the through cavities, the workpiece is inserted into the installation seam and then passes through the contrasting seam, and is clamped and fixed by the clustering piece through the through cavities in the contrasting seam;

[0009] The adaptable assembly comprises a positioning seat fixed on the partition plate, wherein a lateral positioning member is arranged on the inner side of the positioning seat, and when the workpiece is fixed by the clustering member, the lateral positioning member is pressed against the outer side of the clustering member and the workpiece;

[0010] The clustering push-up assembly includes a tie piece arranged below the clustering member, and the lower end of the tie piece is provided with a power piece fixed to the inner bottom of the connecting platform. After the clustering member is expanded, the power piece drives the tie piece to move upward and causes the clustering member to retract inward, so that the clustering member is tightly attached to the outside of the workpiece.

[0011] As a further improvement, the clustering member includes four hinge rods arranged in the through cavity, the lower ends of the hinge rods are provided with clustering plates, the lower ends of the clustering plates are provided with elastic binding seats, and after the workpiece is inserted, the clustering plates are stretched open and then adhered to the elastic binding seats.

[0012] As a further improvement, the clustering plate includes a hard steel plate connected to the hinge rod, a spring steel plate is provided at the lower end of the hard steel plate, and the lower end of the spring steel plate is connected to an elastic binding seat.

[0013] As a further improvement, the elastic binding seat includes a square plate connected to the elastic steel sheet, a plurality of the square plates form a square seat, and a compensation gasket is arranged below the square plate.

[0014] As a further improvement, a guide slot is provided on the partition plate, and the lateral positioning member includes a transverse frame movably connected in the guide slot, and an upper positioning portion and a lower positioning portion are respectively provided at the upper and lower ends of the transverse frame, and the upper positioning portion is affixed to the outer side of the workpiece, and the lower positioning portion is affixed to the outer side of the clustering member.

[0015] As a further improvement, the transverse frame includes an upper T-shaped rod and a lower T-shaped rod slidably arranged on the upper and lower ends of the partition plate, and the upper T-shaped rod and the lower T-shaped rod are connected by a connecting piece slidably arranged in the guide slot.

[0016] As a further improvement, a positioning cylinder is provided in the positioning seat, the positioning cylinder is connected to the lower positioning part, the lower positioning part includes a side push block connected to the positioning cylinder, and the side push block is connected to a crimping block attached to the outside of the clustering member.

[0017] As a further improvement, the anchor member includes an upper movable seat connected to a hard steel sheet, a connecting rod is connected to the lower end of the upper movable seat, a lower movable seat is fixedly connected to the lower end of the connecting rod, and the lower movable seat is connected to the power member.

[0018] The beneficial effects of the present invention are:

[0019] In existing vertical machining centers, the workpiece is mostly fixed directly in the installation gap of the worktable by rigid means, and then different tools are switched to process the workpiece. In this way, the workpiece is either fixed too tightly, resulting in damage to the lower end position of the workpiece, or it is not fixed tightly enough, resulting in the workpiece jumping when the tool enters and exits, and the workpiece shifts during multi-stage processing. Therefore, the present invention hollows out the middle position of the traditional worktable body through the provision of a middle docking component, and arranges partition plates and blocking blocks therein to form a number of through cavities that are roughly adapted to the size of the workpiece, and by arranging a clustering piece in the through cavity, when the workpiece enters, the workpiece will be fixed by the clustering piece, so that when setting the installation gap, there is no need to customize the size of the installation gap to be too narrow, and the bottom area of ​​the workpiece can still be fixed, thereby reducing the possible jumping of the workpiece at the bottom of the stage.

[0020] When the clustering piece is being bound, it has a square structure, so it can adapt to square or round workpiece blanks. Under normal conditions, it is affected by the torsion spring inside the hinge rod, and all the clustering pieces will gather towards the middle until a workpiece enters through the cavity, then the clustering pieces will be directly stretched open. Due to the reset effect of the clustering piece itself, the clustering piece will hold the outer side of the workpiece tightly and fix it, so that the workpiece is initially fixed.

[0021] The cluster sheet restraint is performed through multiple stages. The part that initially contacts the workpiece is contacted by a hard steel sheet, thereby forming a rigid single-point fixation at the top. At the end, it is gradually restrained and fixed through surface contact using an elastic spring steel sheet. At the bottom of the workpiece, it is supported by an elastic binding seat, thereby achieving three-point fixed limit at the middle of the outer side, the outer bottom, and the outer bottom surface.

[0022] If only the bottom of the workpiece is fixed, then its stabilizing force is definitely insufficient for a workpiece of a certain length. Therefore, the present invention provides an adaptive component on the basis of the bottom being limited by the middle docking component. By fixing the adaptive component at a lower middle position, the middle position of the entire workpiece is fixed in the horizontal direction, thereby avoiding left and right deviations.

[0023] When fixing at the middle position, instead of fixing at the upper or lower single end, the upper positioning part and the lower positioning part are used simultaneously to fix both the upper end position and the lower end position of the workpiece. Thus, while restricting the workpiece, a certain limiting and binding function is provided for the rigid part of the beam collecting member.

[0024] The upper positioning part and the lower positioning part are not driven in segments. Since the area under the entire workbench is relatively narrow, it is not suitable to set many driving structures. Therefore, in the present invention, the upper positioning part and the lower positioning part are connected by a transverse moving frame, and a linkage upper and lower limiting structure is formed through the provided upper T-shaped rod, lower T-shaped rod, and connecting piece.

[0025] When the beam collecting member acts on the workpiece, it is bound by its own resilience, and its actual binding force is small. However, if directly pressed laterally, it is easy to deform the beam collecting member relative to the inclined beam collecting member. Therefore, on the basis of the above, the present invention further provides a beam collecting upward pushing assembly. The beam collecting upward pushing assembly is arranged downward on the outside of the beam collecting member. Through the upward thrust, the closing force of the entire beam collecting member is made greater, and since it acts on the side of the beam collecting member, the closing effect can be directly improved without applying too much force to the beam collecting member. Thus, while increasing the binding force, the phenomenon of beam collecting member deformation can be greatly avoided to improve the practicability of the present invention.

[0026] During the setting process of the beam collecting upward pushing assembly, it needs to be set relatively flexibly so that the beam collecting piece can better fit the workpiece. Therefore, in the present invention, the pulling member is arranged in a way that both ends are movable, so that the degree of freedom of the pulling member is higher. When the power member pushes upward, it can push and pull the connecting rod upward, thus realizing the effect of pushing upward at the bottom and further realizing the inward gathering effect of the beam collecting member. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 is a schematic structural diagram of the present invention (top view perspective).

[0029] Figure 2 is a schematic structural diagram of the present invention (bottom view perspective).

[0030] Figure 3 is a top view structural schematic diagram of the present invention.

[0031] Figure 4 is the present inventionFigure 3 The sectional view at A-A in [it].

[0032] Figure 5 It is the present invention Figure 3 The sectional view at B-B in [it].

[0033] Figure 6 It is the structural schematic diagram of the beam collecting member of the present invention.

[0034] Figure 7 It is the structural schematic diagram of the adaptable component of the present invention.

[0035] In the figure:

[0036] Workbench main body 10, installation seam 11, connecting platform 20, moving seat 30, guiding clamp 40, middle docking component 50, partition board 51, through cavity 54, beam collecting member 55, hinge rod 551, beam collecting sheet 552, hard steel sheet 5521, spring steel sheet 5522, elastic tightening seat 553, square sheet board 5531, compensation gasket 5532, adaptable component 60, positioning cylinder 611, lateral positioning member 62, transverse moving frame 621, upper T-shaped rod 6211, lower T-shaped rod 6212, connecting piece 6213, upper positioning part 622, lower positioning part 623, side pushing block 6231, pressing block 6232, beam collecting upward pushing component 70, pulling member 71, upper movable seat 711, connecting rod 712, lower movable seat 713, power member 72. Specific embodiments

[0037] To make the embodiments of the present invention, they all belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0038] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0039] Reference Figures 1 to 7 As shown, a workbench structure for a vertical machining center includes a workbench main body 10. A number of installation slots 11 for installing workpieces are provided on the workbench main body 10. A connecting platform 20 is connected to the lower end of the workbench main body 10. A moving seat 30 that cooperates with a lead screw is connected to the lower end of the connecting platform 20. Guide clips 40 fixed below the connecting platform 20 are provided at both ends of the moving seat 30. The workbench structure further includes: a middle docking component 50, which includes a partition plate 51 arranged in the middle of the inner side of the connecting platform 20. A corresponding slot is provided on the partition plate 51 corresponding to the installation slot 11. A number of spaced barrier blocks are filled in the corresponding slot. A number of through cavities 54 are formed between the barrier blocks. A bundling member 55 is arranged inside the through cavity 54. After the workpiece is inserted into the installation slot 11, it penetrates through the corresponding slot and is clamped and fixed by the bundling member 55 through the through cavity 54 in the corresponding slot; an adaptable component 60, which includes a positioning seat fixed on the partition plate 51. A lateral positioning member 62 is arranged inside the positioning seat. After the workpiece is fixed by the bundling member 55, the lateral positioning member 62 presses against the outer sides of the bundling member 55 and the workpiece; a bundling and upward pushing component 70, which includes a pulling member 71 arranged below the bundling member 55. A power member 72 fixed to the bottom of the inner side of the connecting platform 20 is arranged at the lower end of the pulling member 71. After the bundling member 55 is expanded, the power member 72 drives the pulling member 71 to move upward and makes the bundling member 55 contract inward, so that the bundling member 55 closely adheres to the outer side of the workpiece.

[0040] When installing the workpiece, the workpiece is embedded into the installation slot 11 of the workbench main body 10, so that the workpiece extends into the hole position of the installation slot 11 until it enters the through cavity 54 of the corresponding slot for fixation.

[0041] In existing vertical machining centers, the workpiece is mostly directly fixed in the installation slot 11 of the workbench by hard means, and then different tools are switched to process the workpiece. In this way, either the fixation is too tight, resulting in damage to the lower end position of the workpiece, or the fixation is not tight enough, resulting in the workpiece jumping when the tool enters and exits, and the workpiece shifting during multi-stage processing. Therefore, in the present invention, by setting the middle docking component 50, the middle position of the traditional workbench main body 10 is hollowed out, and a partition plate 51 and barrier blocks are arranged therein to form a number of through cavities 54 that are roughly adapted to the size of the workpiece. By arranging a bundling member 55 in the through cavity 54, when the workpiece enters, it will be fixed by the bundling member 55. Therefore, when setting the installation slot 11, there is no need to customize the size of the installation slot 11 to be too narrow, and the bottom area of the workpiece can still be fixed, thereby reducing the possible jumping phenomenon of the workpiece at the bottom of the stage.

[0042] In this embodiment, the clustering piece 55 has a square structure when being bound, so that it can adapt to square or round workpiece blanks. Specifically, the clustering piece 55 includes four hinges 551 arranged in the through cavity 54, and the lower end of the hinge 551 is provided with a clustering piece 552, and the lower end of the clustering piece 552 is provided with an elastic binding seat 553. After the workpiece is inserted, the clustering piece 552 is stretched open and then adhered to the elastic binding seat 553. Under normal conditions, under the influence of the torsion spring inside the hinge 551, all the clustering pieces 552 will gather towards the middle until a workpiece enters through the through cavity 54, and then the clustering pieces 552 will be directly stretched open. Due to the reset effect of the clustering piece 552 itself, the clustering piece 552 will hold the outer side of the workpiece tightly and fix it, so that the workpiece is initially fixed.

[0043] The binding of the clustering plate 552 is performed through multiple sections, so the clustering plate 552 is arranged in sections, and the clustering plate 552 includes a hard steel plate 5521 connected to the hinge rod 551, and the lower end of the hard steel plate 5521 is provided with an elastic steel plate 5522, and the lower end of the elastic steel plate 5522 is connected to an elastic binding seat 553, and the part that initially contacts the workpiece is contacted with the part of the hard steel plate 5521, thereby forming a rigid single-point fixation at the top position, and at the end position, it is gradually bound and fixed by means of surface contact through the elastic elastic steel plate 5522, and at the bottom position of the workpiece, it is supported by the elastic binding seat 553, thereby realizing three-point fixed limit of the outer middle part, the outer bottom, and the outer bottom surface.

[0044] The entire elastic binding seat 553 is tightly attached to the bottom of the workpiece. Although it does not completely cover it, it will present a wrapping manner. Specifically, the elastic binding seat 553 includes a square plate 5531 connected to the elastic steel sheet 5522. Several square plates 5531 form a square seat. A compensation gasket 5532 is arranged under the square plate 5531, so that the wrapping limit area can be changed as the workpiece goes deeper, thereby improving the stabilization effect.

[0045] If only the bottom of the workpiece is fixed, its stabilizing force is definitely insufficient for a workpiece of a certain length. Therefore, the present invention provides an adaptive component 60 on the basis of the bottom being limited by the middle docking component 50. By fixing the adaptive component 60 at a lower middle position, the middle position of the entire workpiece is fixed in the horizontal direction, thereby avoiding the phenomenon of left and right deviation.

[0046] When fixing in the middle position, it is not a single-end upper or lower fixation, and a guide slot is provided on the partition plate 51 of this embodiment, and the lateral positioning member 62 includes a transverse frame 621 movably connected in the guide slot, and the upper and lower ends of the transverse frame 621 are respectively provided with an upper positioning portion 622 and a lower positioning portion 623, and the upper positioning portion 622 is attached to the outer side of the workpiece, and the lower positioning portion 623 is attached to the outer side of the clustering member 55. The upper positioning portion 622 and the lower positioning portion 623 are simultaneously implemented to fix the workpiece at both the upper and lower ends, thereby providing a certain limiting and restraining function to the hard part of the clustering member 55 while restricting the workpiece.

[0047] The upper positioning portion 622 and the lower positioning portion 623 are not driven in sections. Since the area under the entire workbench is relatively narrow, it is not suitable to set up more driving structures. Therefore, the transverse frame 621 of this embodiment includes an upper T-bar 6211 and a lower T-bar 6212 slidably set at the upper and lower ends of the partition plate 51. The upper T-bar 6211 and the lower T-bar 6212 are connected by a connecting piece 6213 slidably set in the guide gap. The upper positioning portion 622 and the lower positioning portion 623 are connected by a transverse frame 621, and a linked upper and lower limit structure is formed by the upper T-bar 6211, the lower T-bar 6212, and the connecting piece 6213.

[0048] The lower positioning portion 623 is provided with active power. Specifically, a positioning cylinder 611 is arranged in the positioning seat. The positioning cylinder 611 is connected to the lower positioning portion 623. The lower positioning portion 623 includes a side push block 6231 connected to the positioning cylinder 611. The side push block 6231 is connected to a crimping block 6232 attached to the outer side of the clustering member 55. The crimping block 6232 cooperates with the clustering member 55. The crimping block 6232 has a certain elasticity to avoid direct damage to the clustering member 55. The upper positioning portion 622 cooperates with the workpiece in a rigid manner. It should be specifically noted that the length of the upper positioning portion 622 is longer than that of the lower positioning portion 623.

[0049] When the clustering member 55 acts on the workpiece, it relies on its own resilience to restrain it, and its actual restraining force is relatively small. However, if pressure is applied directly from the side, it is easy for the clustering member 55 that is set obliquely to deform. Therefore, the present invention is further provided with a clustering push-up assembly 70 on the basis of the above. The clustering push-up assembly 70 is arranged downward on the outer side of the clustering member 55. The upward thrust makes the gathering force of the entire clustering member 55 greater, and because it acts on the side of the clustering member 55, the gathering effect can be directly improved, and there is no need to apply excessive force to the clustering member 55, thereby improving the binding force while avoiding the deformation of the clustering member 55 to a great extent, thereby improving the practicality of the present invention.

[0050] During the setting process of the cluster upward pushing component 70, it needs to be set relatively flexibly so that the cluster piece 552 can fit more closely to the workpiece. Therefore, in this embodiment, the tying member 71 includes an upper movable seat 711 connected to the hard steel piece 5521. A connecting rod 712 is connected to the lower end of the upper movable seat 711. A lower movable seat 713 is fixedly connected to the lower end of the connecting rod 712. The lower movable seat 713 is connected to the power member 72. The tying member 71 is movably arranged at both ends, so that the tying member 71 has a higher degree of freedom. When the power member 72 pushes upward, it can push and pull the connecting rod 712 upward, so as to achieve the effect of upward pushing at the bottom, and further achieve the inward gathering effect of the cluster member 55.

[0051] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A worktable structure for a vertical machining center, comprising a worktable body (10), the worktable body (10) being provided with a plurality of mounting slots (11) for mounting workpieces, the lower end of the worktable body (10) being connected to a connecting platform (20), the lower end of the connecting platform (20) being connected to a moving seat (30) cooperating with a screw rod, the two ends of the moving seat (30) being provided with guide clips (40) fixed below the connecting platform (20), characterized in that: The workbench structure also includes: The middle docking assembly (50) comprises a partition plate (51) arranged at the middle of the inner side of the connecting platform (20), the partition plate (51) being provided with a contrasting seam corresponding to the installation seam (11), the contrasting seam being filled with a plurality of spaced-apart blocking blocks, a plurality of through cavities (54) being formed between the plurality of blocking blocks, a clustering piece (55) being arranged inside the through cavities (54), the workpiece being inserted into the installation seam (11) and then passing through the contrasting seam, and being clamped and fixed by the clustering piece (55) through the through cavities (54) in the contrasting seam; An adaptable component (60) comprises a positioning seat fixed on the partition plate (51), a lateral positioning piece (62) being arranged on the inner side of the positioning seat, and when the workpiece is fixed by the bundling piece (55), the lateral positioning piece (62) is pressed against the outer side of the bundling piece (55) and the workpiece; The bunching push-up assembly (70) comprises a tie piece (71) arranged below the bunching piece (55); the lower end of the tie piece (71) is provided with a power piece (72) fixed to the inner bottom of the connecting platform (20); after the bunching piece (55) is opened, the power piece (72) drives the tie piece (71) to move upward and retract the bunching piece (55) inward, so that the bunching piece (55) is closely attached to the outer side of the workpiece; The clustering member (55) comprises four hinge rods (551) arranged in the through cavity (54); a clustering sheet (552) is arranged at the lower end of the hinge rod (551); an elastic binding seat (553) is arranged at the lower end of the clustering sheet (552); after the workpiece is inserted, the clustering sheet (552) is stretched open and then the workpiece is adhered to the elastic binding seat (553); The clustering sheet (552) comprises a hard steel sheet (5521) connected to the hinge rod (551), a spring steel sheet (5522) is provided at the lower end of the hard steel sheet (5521), and the lower end of the spring steel sheet (5522) is connected to an elastic fastening seat (553); The elastic binding seat (553) comprises a square plate (5531) connected to the elastic steel sheet (5522), a plurality of the square plates (5531) form a square seat, and a compensation gasket (5532) is arranged below the square plates (5531).

2. A worktable structure for a vertical machining center according to claim 1, characterized in that: A guide slit is provided on the partition plate (51), and the lateral positioning member (62) comprises a transverse moving frame (621) movably connected in the guide slit. An upper positioning portion (622) and a lower positioning portion (623) are respectively provided at the upper and lower ends of the transverse moving frame (621), the upper positioning portion (622) being attached to the outer side of the workpiece, and the lower positioning portion (623) being attached to the outer side of the clustering member (55).

3. A worktable structure for a vertical machining center according to claim 2, characterized in that: The transverse moving frame (621) comprises an upper T-shaped rod (6211) and a lower T-shaped rod (6212) slidably arranged at the upper and lower ends of the partition plate (51); the upper T-shaped rod (6211) and the lower T-shaped rod (6212) are connected via a connecting piece (6213) slidably arranged in the guide slot.

4. A worktable structure for a vertical machining center according to claim 1, characterized in that: A positioning cylinder (611) is arranged in the positioning seat, the positioning cylinder (611) is connected to a lower positioning portion (623), the lower positioning portion (623) comprises a side push block (6231) connected to the positioning cylinder (611), and the side push block (6231) is connected to a crimping block (6232) affixed to the outside of the clustering member (55).

5. The worktable structure for a vertical machining center according to claim 1, characterized in that: The anchor member (71) comprises an upper movable seat (711) connected to a hard steel sheet (5521); the lower end of the upper movable seat (711) is connected to a connecting rod (712); the lower end of the connecting rod (712) is fixedly connected to a lower movable seat (713); and the lower movable seat (713) is connected to a power member (72).

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