CN111152103A

CN111152103A - Overturning and polishing device for trapezoidal strip-shaped stool legs

Info

Publication number: CN111152103A
Application number: CN202010051148.3A
Authority: CN
Inventors: 林春华
Original assignee: Individual
Current assignee: Hebei Guyuxuan Furniture Co ltd
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2020-05-15
Anticipated expiration: 2040-01-17
Also published as: CN111152103B

Abstract

The invention discloses a flipping and grinding device for a trapezoidal bar stool leg, which relates to the technical field of wood processing, and solves the problem that the manual processing method is too inefficient and easy to grind unevenly, while the grinding method of mechanical processing equipment is mainly based on a flat structure. , does not have the function of grinding the inclined surface, and does not have the processing function of automatic flanging. A flipping and grinding device for a trapezoidal bar stool leg, comprising a base; a follower plate is arranged on the top of the base to rotate through a rotating shaft; a scissor mechanism is fixed on the top of the follower plate by bolts, and the top of the scissor mechanism is provided with bolts The abrasive belt seat is fixedly arranged; the scissors mechanism and the abrasive belt holder are provided to provide the function of adjusting the height and angle of the grinding mechanism of the grinding device, and it can be adjusted to an inclined angle by adjusting to fit the trapezoidal stool Legs, the width can be adjusted according to different models, which is conducive to even sanding the legs of the stool.

Description

Overturning and polishing device for trapezoidal strip-shaped stool legs

Technical Field

The invention relates to the technical field of wood processing, in particular to a turning and polishing device for trapezoidal strip stool legs.

Background

At present, most strip-shaped stool legs are formed by splicing at least 4 battens, a trapezoid structure can be formed for reinforcing a certain number of the strip-shaped stool legs, redundant burrs are unavoidably arranged on the outer sides of the stool legs after splicing, workers generally can polish the burrs on the outer sides of the stool legs, after holding the battens between the stool legs, the workers move the battens back and forth for many times to drive the stool legs to move back and forth on polishing parts to polish, after the burrs on one sides of the stool legs are ground off, the battens need to be turned over, the battens are pushed back and forth again, the other sides of the stool legs are polished, and thus the workers finish polishing work on the burrs on the two sides of the stool legs.

Through retrieval, for example, patent No. CN102166770A discloses a processing device for wood strips, which is characterized in that a lower roller at one end of the device is connected with an upper roller at the other end and one transition chain wheel thereof through a chain to form a first group of pressing plate devices, an upper roller at one end of the device is connected with a lower roller at the other end and the other transition chain wheel thereof through a chain to form a second group of pressing plate devices, wherein one group of pressing plate devices has a slow rotating speed, the other group of pressing plate devices has a fast rotating speed, the two groups of pressing plate devices are respectively driven by a first driving device and a second driving device, the opposite upper rollers and the lower rollers in the two groups of pressing plate devices alternate in speed, so that only one surface of the wood strips at a certain processing point is quickly polished under the pressing of the rollers, and the other surface is a slow roller, thereby ensuring that the wood strips cannot be driven by the high-rotating-speed rollers during feeding, and further controlling, the wood strips can move forward at a constant speed, and the wood strips which are relatively short can be processed.

However, the manual processing mode is too low in efficiency and easy to polish uneven, and the mechanical processing equipment polishing mode mainly takes a flat structure as a main mode, does not have the function of polishing the inclined plane, cannot make further adjustment according to the angle difference of the polished edge, and does not have the processing function of automatically flanging, so that the existing requirements are not met, and the overturning polishing device for the trapezoid strip-shaped stool legs is provided.

Disclosure of Invention

Problem (A)

The invention aims to provide a turnover polishing device for trapezoid strip stool legs, which solves the problems that the manual processing mode provided in the background technology is too low in efficiency and easy to polish uneven surfaces, and the mechanical processing equipment polishing mode mainly adopts a flat structure, does not have the function of polishing inclined surfaces, cannot make further adjustment according to different angles of polishing edges and does not have the processing function of automatic flanging.

(II) technical scheme

In order to achieve the purpose, the invention provides the following technical scheme: a turning and polishing device for trapezoidal strip stool legs comprises a base; the top of the base is rotatably provided with a follow-up plate through a rotating shaft; the top of the follow-up plate is fixedly provided with a shear fork mechanism through a bolt, and the top of the shear fork mechanism is fixedly provided with an abrasive belt seat through a bolt; one side of the top of the abrasive belt seat is rotatably provided with an abrasive belt frame through a rotating shaft; a sliding column is arranged on one side of the top of the base in a sliding mode through a sliding rail; an adjusting seat is rotatably arranged on the inner side of the top of the sliding column through a bearing; the bottom of one side of the sliding column is rotatably provided with a synchronizing wheel through a rotating shaft, and an inner ratchet wheel gear is fixedly connected with the outer side of the synchronizing wheel through a coaxial key; the top of one side of the base is fixedly provided with a rack through a bolt, an inner ratchet wheel is meshed with the rack, and the diameter of the inner ratchet wheel is twice the tooth length of the rack.

Preferably, the front end of the follow-up plate is rotatably provided with a guide strip through a rotating shaft, and the middle of the guide strip is provided with a guide groove; the inboard fixed direction cylinder that is provided with of bottom through interference fit of slip post, and the middle department outer end of direction cylinder and guide way kinematic connection.

Preferably, the sand belt seat further comprises an adjusting frame; an adjusting frame is integrally arranged at the rear side of the abrasive belt seat, and a screw hole is formed in the middle of the adjusting frame; four groups of guide rods are fixedly arranged at the top of the follow-up plate, and four groups of round holes are formed around the abrasive belt seat and are in sliding connection with the guide rods.

Preferably, the abrasive belt frame further comprises a motor, an abrasive belt, a sliding frame and a screw frame; a motor is fixedly arranged on one side of the abrasive belt frame; the middle of the abrasive belt frame is rotatably provided with an abrasive belt through a rotating shaft, and the abrasive belt is movably connected with a motor; two groups of sliding frames are fixedly arranged on one side of the abrasive belt frame through welding, and screw frames are arranged in the sliding frames in a sliding mode; a round hole is formed in the screw rod frame, a screw rod penetrates through the round hole, and the bottom of the screw rod is connected with the middle screw hole of the adjusting frame.

Preferably, the sliding column further comprises a pin rod frame, a pin rod and a spring plate; two groups of pin rod frames are integrally arranged on two sides of the sliding column, and pin rods penetrate through the pin rod frames; one end of each pin rod is integrally provided with a hemispherical structure, and the outer side positions of the pin rods between the pin rod frames are fixedly provided with elastic sheets through welding; and springs are sleeved outside the pin rods between the elastic sheets and the pin rod frames close to the outer sides.

Preferably, the adjusting seat further comprises a circular shaft sleeve, a synchronous gear ring and a fixed sleeve; the outer end of the adjusting seat is integrally provided with a round shaft sleeve, and the outer side of the round shaft sleeve is rotatably connected with the sliding column through a bearing; a synchronous gear ring is integrally arranged on the outer side of the circular shaft sleeve, and the outer side of the synchronous gear ring is movably connected with a synchronous wheel at the bottom of one side of the sliding column through a synchronous belt, so that the transmission ratios are the same; a fixed sleeve is integrally arranged on the outer side of the synchronous gear ring, and a holding mechanism is movably arranged outside the fixed sleeve; an adjusting shaft is rotatably arranged in the circular shaft sleeve through a bearing; spherical grooves are formed in two ends of the outer portion of the adjusting seat, and the hemispherical structures at the end portions of the pin rods can be matched with the spherical grooves of the adjusting seat and are fixed in a self-locking mode.

Preferably, the clasping mechanism further comprises a locking rod; the clamping mechanism is a crank slider mechanism, the outer end of the clamping mechanism is provided with a screw rod through threaded connection, and the clamping mechanism can be elongated through the screw rod; the shaft ends of the clasping mechanisms are respectively and rotatably provided with a locking rod through a rotating shaft, and two sides of each locking rod are respectively provided with a guide groove; the fixed cover is provided with two groups of guide holes matched with the locking rods, and the locking rods are sleeved with springs and penetrate through the guide holes to be fixedly provided with arc-shaped holding sheets.

Preferably, the adjusting shaft further comprises an adjusting gear; the fixed frame also comprises an adjusting rack; the end part of the adjusting shaft is fixedly provided with a handle, and the adjusting shaft penetrates through the circular shaft sleeve and is fixedly provided with an adjusting gear through key connection; adjusting racks are fixedly arranged on one sides of the fixing frames, and guide rails are fixedly arranged outside the adjusting racks through bolts; the inner sides of the adjusting seats are fixedly provided with sliding blocks through bolts, and the adjusting seats are connected with the guide rails in a sliding mode through the sliding blocks; the adjusting racks are meshed with the adjusting gears and are in movable connection, and the centers of the adjusting racks are symmetrical.

Has the advantages that:

the invention provides a turnover polishing device for trapezoid strip stool legs, which is provided with a shearing fork mechanism and a sand belt frame, provides a function of adjusting the height and the angle for a polishing mechanism of the polishing device, can be adjusted to be an inclined angle through adjustment so as to be suitable for the trapezoid stool legs, can be adjusted according to different types and widths, and is beneficial to uniformly polishing the stool legs.

Secondly, the setting of interior ratchet gear and rack provides the function of automatic upset for grinding device, and according to the removal of slip post, can carry out 180 rotations, realize the upset with the stool leg, compare the convenient laborsaving and lifting efficiency of manual rotation, simultaneously, the setting of pin pole provides the fixed ability of elasticity auto-lock for the adjustment seat, can inject the angle of adjustment seat and avoid its automatic deviation.

Moreover, the guide strips can be matched with the cylindrical guide to lift in the moving process of the sliding column, when the stool legs move to the abrasive belt, the abrasive belt is lifted to be attached to the stool legs to be polished, the stool legs are prevented from scraping the side of the abrasive belt, and the automation effect is good.

Drawings

FIG. 1 is a schematic top view of an embodiment of the present invention;

FIG. 2 is a schematic perspective rear view structure in an embodiment of the present invention;

FIG. 3 is a schematic perspective view of a base according to an embodiment of the present invention;

FIG. 4 is a schematic perspective view of a sliding column according to an embodiment of the present invention;

FIG. 5 is an enlarged partial view of the structure of A in the embodiment of the present invention;

FIG. 6 is an enlarged partial view of the structure of B in the embodiment of the present invention;

FIG. 7 is an enlarged partial view of the structure of C in the embodiment of the present invention;

FIG. 8 is an enlarged partial view of the structure of D in the embodiment of the present invention;

in fig. 1 to 8, the correspondence between the part names or lines and the reference numbers is: 1. the automatic adjusting device comprises a base, 2, a follow-up plate, 201, a guide strip, 3, a sand belt seat, 301, an adjusting frame, 4, a scissor fork mechanism, 5, a sand belt frame, 501, a motor, 502, a sand belt, 503, a sliding frame, 504, a screw rod frame, 6, a sliding column, 601, a pin rod frame, 602, a pin rod, 603, a spring plate, 7, an adjusting seat, 701, a circular shaft sleeve, 702, a synchronous gear ring, 703, a fixing sleeve, 8, a holding mechanism, 801, a locking rod, 9, an adjusting shaft, 901, an adjusting gear, 10, a fixing frame, 1001, an adjusting rack, 11, a synchronous belt, 12, an inner ratchet gear, 13 and a rack.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Referring to fig. 1 to 8, an embodiment of the present invention includes: a turning and polishing device for trapezoid strip stool legs comprises a base 1, wherein the top of the base 1 is rotatably connected with a follow-up plate 2 through a rotating shaft, the front side of the follow-up plate 2 is rotatably connected with a guide strip 201 through the rotating shaft, a guide groove is formed in the middle of the guide strip 201, the inner side of the bottom of a sliding column 6 is connected with a guide cylinder through interference, the outer end of the middle of the guide cylinder is movably connected with the guide groove, and the top of the follow-up plate 2 is provided with a scissor mechanism 4 through a bolt; the top of the shearing fork mechanism 4 is connected with an abrasive belt seat 3 through a bolt, the abrasive belt seat 3 further comprises an adjusting frame 301, the rear side of the abrasive belt seat 3 is integrally connected with the adjusting frame 301, and the middle of the adjusting frame 301 is provided with a screw hole; four guide rods are arranged at the top of the follow-up plate 2, four round holes are formed around the abrasive belt seat 3, and the four guide rods respectively penetrate through the four round holes in a sliding manner; the rear side of the top of the abrasive belt seat 3 is rotatably connected with an abrasive belt frame 5 through a rotating shaft, the abrasive belt frame 5 further comprises a motor 501, an abrasive belt 502, a sliding frame 503 and a screw rod frame 504, the motor 501 is mounted on the left side of the abrasive belt frame 5 through a bolt, the abrasive belt 502 is rotatably connected in the middle of the abrasive belt frame 5 through the rotating shaft, and the abrasive belt 502 is movably connected with the motor 501; two sliding frames 503 are welded at the upper part of the rear side of the abrasive belt frame 5, a screw frame 504 is arranged in the sliding frames 503 in a sliding manner, a round hole is formed in the screw frame 504, a screw is arranged in the round hole, and the bottom end of the screw is connected with a middle screw hole of the adjusting frame 301; the front side of the top of the base 1 is connected with a sliding column 6 in a sliding manner through a sliding rail, the top of the sliding column 6 is connected with a handle, the sliding column 6 further comprises pin rod frames 601, pin rods 602 and elastic pieces 603, the left side and the right side of the upper part of the sliding column 6 are connected with the two pin rod frames 601 in a uniform manner, the pin rods 602 are fixedly connected between the two pin rod frames 601 on the left side in a penetrating manner, the pin rods 602 are also fixedly connected between the two pin rod frames 601 on the right side in a penetrating manner, the end parts of the two pin rods 602 are connected with a hemispherical structure in a uniform manner, the elastic pieces 603 are connected between the two pin rod frames 601 on the left side, the elastic pieces 603 are also connected between the two pin rod frames 601 on the right side, the two elastic pieces 603 are respectively connected; the inner side of the top of the sliding column 6 is rotatably connected with an adjusting seat 7 through a bearing, the adjusting seat 7 further comprises a circular shaft sleeve 701, a synchronous gear ring 702 and a fixed sleeve 703, the outer end of the adjusting seat 7 is integrally connected with the circular shaft sleeve 701, the outer side of the circular shaft sleeve 701 is rotatably connected with the sliding column 6 through a bearing, the synchronous gear ring 702 is integrally installed on the outer side of the circular shaft sleeve 701, the synchronous gear ring 702 is movably connected with a synchronous wheel on the sliding column 6 through a synchronous belt 11, the transmission ratios are the same, and the fixed sleeve 703 is integrally connected to; the fixing sleeve 703 is movably provided with a clasping mechanism 8, the clasping mechanism 8 further comprises a locking rod 801, the clasping mechanism 8 is a slider-crank mechanism, the outer end of the clasping mechanism 8 is connected with a screw through a thread, the clasping mechanism 8 can be elongated through the screw, the upper end and the lower end of the clasping mechanism 8 are rotatably connected with the locking rod 801 through a rotating shaft, two sides of the locking rod 801 are respectively provided with a guide groove, the fixing sleeve 703 is externally provided with two guide holes which are respectively matched with the two locking rods 801, the two locking rods 801 are respectively provided with a spring, and the locking rod 801 passes through the guide holes and is connected with an arc clasping sheet; the round shaft sleeve 701 is rotatably connected with an adjusting shaft 9 through a bearing, the adjusting shaft 9 further comprises an adjusting gear 901, the front end of the adjusting shaft 9 is connected with a handle, and the adjusting gear 901 is installed on the adjusting shaft 9 through a flat key; spherical grooves have all been seted up at the outside both ends of adjustment seat 7, round pin pole 602 tip semi-spherical structure all can with the spherical groove inosculation of adjustment seat 7 and the auto-lock is fixed, slip post 6 front side lower part is connected with the synchronizing wheel through the pivot rotary type, install interior ratchet gear 12 through the parallel key in the pivot of synchronizing wheel, rack 13 is installed through the bolt in the right front side in base 1 top, interior ratchet gear 12 and rack 13 mesh, the diameter of interior ratchet gear 12 is the tooth length twice of rack 13.

The fixing frame 10 further comprises an adjusting rack 1001, the front side of the fixing frame 10 is connected with the adjusting rack 1001, the bottom of the fixing frame 10 is also connected with the adjusting rack 1001, guide rails are mounted on the two adjusting racks 1001 through bolts, the inner side of the adjusting seat 7 is connected with a sliding block through bolts, and the adjusting seat 7 is connected with the guide rails in a sliding mode through the sliding block; the adjusting rack 1001 is engaged with and movably connected with the adjusting gear 901, and the adjusting rack 1001 is centrosymmetric.

The working principle is as follows: when the adjustable stool is used, the screw of the clasping mechanism 8 is loosened, the stool is vertically placed between the fixing frames 10, the adjusting shaft 9 is rotated to draw the fixing frames 10 close to clamp the stool, meanwhile, the screw of the clasping mechanism 8 is manually screwed, and the locking rod 801 is used for locking the clasping sheet to fix the circumferential positions of the adjusting seat 7 and the adjusting shaft 9; the sliding column 6 is moved to the middle position of the guide strip 201, meanwhile, the guide strip 201 is lifted up through the guiding of the cylinder, the front end of the abrasive belt frame 5 is lifted up by tightly pressing the adjusting frame 301 and the screw frame 504 through the bolts, the abrasive belt frame 5 is adjusted to the inclination angle same as that of the stool leg, and then the position of the abrasive belt seat 3 is lifted up according to the position of the stool leg through the scissor mechanism 4, so that the abrasive belt 502 is attached to the stool leg; starting motor 501, utilize the handle to remove slip post 6, remove through manual pulling slip post 6, polish the stool leg, can lift up abrasive band 502 when slip post 6 removes the bottom position of gib block 201 direction and polish, and will fall down through gib block 201 when slip post 6 removes the border position, make abrasive band 502 leave the bottom of stool leg, continue to remove slip post 6 simultaneously, it is rotatory to drive hold-in range 11 through ratchet 12 in the rack 13 cooperation, rotate adjustment seat 7 180, accomplish the upset, cooperate the position of pin 602 fixed adjustment seat 7 simultaneously, avoid its auto-migration.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. A flipping and grinding device for a trapezoidal bar stool leg, characterized in that: it comprises a base (1); the top of the base (1) is provided with a follower plate (2) by rotating a rotating shaft; the follower plate (2) ) A scissor mechanism (4) is fixed on the top by bolts, and an abrasive belt seat (3) is fixed on the top of the scissor mechanism (4) by bolts; one side of the top of the abrasive belt seat (3) is rotated by a rotating shaft and is provided with An abrasive belt holder (5); a sliding column (6) is provided on one side of the top of the base (1) through sliding rails; an adjustment seat (7) is provided on the inner side of the top of the sliding column (6) through a bearing to rotate; the A synchronizing wheel is arranged on the bottom of one side of the sliding column (6) through a rotating shaft, and an inner ratchet gear (12) is fixedly arranged on the outer side of the synchronizing wheel through coaxial key connection; the top of one side of the base (1) is fixed with a rack through bolts (13), and the inner ratchet gear (12) meshes with the rack (13), and the diameter of the inner ratchet gear (12) is twice the length of the teeth of the rack (13).

2. The flipping and polishing device for a trapezoidal bar stool leg according to claim 1, characterized in that: the front end of the follower plate (2) is provided with a guide strip (201) through the rotation of the rotating shaft, and the guide strip ( 201) is provided with a guide groove in the middle; the inner side of the bottom of the sliding column (6) is fixedly provided with a guide cylinder through interference fit, and the outer end of the middle of the guide cylinder is movably connected with the guide groove.

3. The device for flipping and grinding the legs of a trapezoidal bar stool according to claim 1, characterized in that: the abrasive belt seat (3) further comprises an adjustment frame (301); the abrasive belt seat (3) An adjustment frame (301) is integrally provided on the rear side of the sled, and a screw hole is formed in the middle of the adjustment frame (301); four sets of guide rods are fixedly arranged on the top of the follower plate (2), and the belt seat (3) is surrounded by Four groups of round holes are provided for sliding connection with the guide rod.

4. The device for flipping and grinding the legs of a trapezoidal bar stool according to claim 1, wherein the abrasive belt holder (5) further comprises a motor (501), an abrasive belt (502), a sliding frame ( 503), a screw rack (504); a motor (501) is fixedly arranged on one side of the abrasive belt rack (5); an abrasive belt (502) is arranged in the middle of the abrasive belt rack (5) through a rotating shaft, and the sand The belt (502) is movably connected with the motor (501); one side of the abrasive belt holder (5) is fixedly provided with two sets of sliding frames (503) by welding, and a screw frame (504) is slidably arranged in the sliding frame (503). ); a round hole is opened in the screw frame (504), and a screw rod is penetrated in the round hole, and the bottom of the screw rod is connected with the middle screw hole of the adjusting frame (301).

5. The device for flipping and grinding the legs of a trapezoidal bar stool according to claim 1, wherein the sliding column (6) further comprises a pin rod frame (601), a pin rod (602), a shrapnel (601). 603); two sets of pin rod brackets (601) are integrally provided on both sides of the sliding column (6), and pin rods (602) are passed through the pin rod brackets (601); 602) is integrally provided with a hemispherical structure at one end, and the outer positions of the pin rods (602) between the pin rod frames (601) are fixedly provided with elastic sheets (603) by welding; The pin rods (602) between the pin rod frames (601) are all sleeved with springs.

6 . The device for flipping and grinding the legs of a trapezoidal bar stool according to claim 5 , wherein the adjustment seat ( 7 ) further comprises a circular shaft sleeve ( 701 ), a synchronous gear ring ( 702 ), a fixed A sleeve (703); the outer end of the adjustment seat (7) is integrally provided with a circular shaft sleeve (701), and the outer side of the circular shaft sleeve (701) is rotatably connected to the sliding column (6) by setting a bearing; the circular shaft The outer side of the sleeve (701) is integrally provided with a synchronous gear ring (702), and the outside of the synchronous gear ring (702) is movably connected with the bottom synchronizing wheel on one side of the sliding column (6) by setting a synchronous belt (11), and the transmission ratio is the same; A fixing sleeve (703) is integrally provided on the outer side of the synchronous gear ring (702), and a holding mechanism (8) is movably provided outside the fixing sleeve (703); an adjusting mechanism (8) is arranged in the circular shaft sleeve (701) through the rotation of the bearing. The shaft (9); the outer ends of the adjustment seat (7) are provided with spherical grooves, and the hemispherical structures at the ends of the pin rods (602) can be matched with the spherical grooves of the adjustment seat (7) and self-locking and fixed.

7. The device for flipping and polishing the legs of a trapezoidal bar stool according to claim 6, characterized in that: the holding mechanism (8) further comprises a locking rod (801); the holding mechanism (8) further comprises a locking rod (801); ) is a crank-slider mechanism, and the outer end of the gripping mechanism (8) is provided with a screw through a threaded connection, and the gripping mechanism (8) can be elongated by the screw; the shaft end of the gripping mechanism (8) is set by rotating the shaft There is a locking rod (801), and both sides of the locking rod (801) are provided with guide grooves; the fixing sleeve (703) is provided with two sets of guide holes that match the locking rod (801), and is locked The rods (801) are sleeved with springs and fixed with arc-shaped holding pieces through the guide holes.

8 . The device for flipping and polishing the legs of a trapezoidal bar stool according to claim 6 , wherein the adjusting shaft ( 9 ) further comprises an adjusting gear ( 901 ); the fixing frame ( 10 ) further comprises an adjusting gear ( 901 ) . There is an adjusting rack (1001); the end of the adjusting shaft (9) is fixedly provided with a handle, and the adjusting shaft (9) passes through the circular shaft sleeve (701) and is fixedly provided with an adjusting gear (901) through a key connection; An adjustment rack (1001) is fixedly arranged on one side of the fixing frame (10), and a guide rail is arranged outside the adjustment rack (1001) by means of bolts; , and the adjustment seats (7) are slidably connected to the guide rails through the sliders; the adjustment racks (1001) are meshed with the adjustment gears (901) and are connected in motion, and the adjustment racks (1001) are centrally symmetrical.