CN218964447U

CN218964447U - Welding robot running gear

Info

Publication number: CN218964447U
Application number: CN202320118098.5U
Authority: CN
Inventors: 赵健; 高鹏飞; 赵子健
Original assignee: Panasonic Welding Systems Tangshan Co Ltd
Current assignee: Panasonic Welding Systems Tangshan Co Ltd
Priority date: 2023-01-18
Filing date: 2023-01-18
Publication date: 2023-05-05
Anticipated expiration: 2033-01-18

Abstract

The application provides a welding robot walking mechanism, which comprises a walking base and a mobile platform; the walking base comprises a supporting piece and a guide rail arranged on the supporting piece, and the mobile platform is in sliding connection with the supporting piece through the guide rail; the support piece is provided with a bending structure which bends towards the guide rail, and the bending structure is used for shielding the guide rail along the first plane; wherein the first plane intersects the height direction of the rail. In the above-mentioned technical scheme, be used for following first plane through the structure of bending and shelter from the guide rail to make the structure of bending shelter from dust and other foreign matter for the guide rail along first plane, need not to add dustproof guard shield again, improve present walking base and because of need add dustproof guard shield in order to make the problem of self structure complicacy.

Description

Welding robot running gear

Technical Field

The application relates to the technical field of welding robot equipment, in particular to a welding robot walking mechanism.

Background

With the development of the domestic robot welding equipment technology, the application of the welding robot travelling mechanism is also becoming wider and wider. Welding robot walkers generally include a walking base and a mobile platform. The walking base comprises a supporting piece, a guide rail and a dustproof shield. The dustproof shield is used for preventing dust to the guide rail.

Although dustproof work can be carried out by additionally arranging a dustproof shield, the walking base structure is complicated.

Disclosure of Invention

The application provides a welding robot running gear for solve at present can lead to the complicated problem of structure of walking base through addding dustproof guard shield and carrying out dirt-proof mode to the guide rail.

The embodiment of the application provides a welding robot walking mechanism, which comprises a walking base and a mobile platform; wherein,,

the walking base comprises a supporting piece and a guide rail arranged on the supporting piece, and the mobile platform is in sliding connection with the supporting piece through the guide rail; wherein,,

the support piece is provided with a bending structure which is bent towards the guide rail and is used for shielding the guide rail along a first plane; wherein,,

the first plane intersects a height direction of the guide rail.

In the above technical scheme, through setting up the bending structure that shelters from the guide rail along first plane, can make bending structure shelter from dust and other foreign matter for the guide rail along first plane, need not to add the dust guard shield again, improve present walking base because of need add the dust guard shield in order to make self structure complicated problem.

In some specific alternative embodiments, the length of the bending structure in a first direction is greater than the length of the guide rail in the first direction; wherein,,

the first direction is perpendicular to a length direction of the guide rail, and the first direction is perpendicular to a height direction of the guide rail.

In some specific alternative embodiments, the guide rail includes a guide member and a moving member; wherein,,

the bearing guide piece is arranged on the supporting piece, and the moving piece is arranged on the moving platform; wherein,,

a chute is arranged on one side of the moving part, which is close to the supporting part;

the bearing and guiding piece is in sliding fit with the sliding groove.

In some specific alternative embodiments, the support is a C-channel; wherein,,

the C-shaped channel steel comprises two leg plates and a waist plate, and the two opposite ends of the waist plate are respectively connected with the leg plates; wherein,,

the guide rail is arranged on the waist plate;

the two waist plates are arranged on two sides of the guide rail in a split manner along the height direction of the guide rail; the two waist plates are respectively used for shielding the guide rail.

In some specific alternative embodiments, the welding robot walking mechanism further comprises a drive mechanism; wherein,,

the driving mechanism comprises a rack, a rotary driving mechanism and a gear meshed with the rack; wherein,,

the rack is arranged on one side of the support piece, which is away from the guide rail;

the rotation driving mechanism is arranged on the moving platform and is connected with the gear.

In some particular alternative embodiments, the drive mechanism further comprises a backlash adjustment assembly; the backlash adjusting assembly comprises a guide plate, a mounting plate and an adjusting assembly; wherein,,

the guide plate is arranged on the mobile platform;

the mounting plate is in sliding connection with the guide plate along a second direction; the rotation driving mechanism is arranged on the mounting plate; the gear is positioned on one side of the mounting plate, which is close to the supporting piece;

the adjusting component is arranged on the moving platform and is abutted with the mounting plate and used for driving the gear to move along the second direction; wherein,,

the second direction is perpendicular to the length direction of the rack, and the second direction is perpendicular to the axis direction of the gear.

In some specific alternative embodiments, the adjustment assembly includes two adjustment plates and two screws;

the two adjusting plates are arranged on two sides of the mounting plate in a row along the second direction, and the adjusting plates are arranged on the mobile platform;

the two screw rods are arranged on two sides of the mounting plate in a row along the second direction, the screw rods are in threaded connection with the adjusting plate, and the length direction of the screw rods is parallel to the second direction; wherein,,

one end of the screw rod is abutted with the end face, close to the adjusting plate, of the mounting plate.

In some specific alternative embodiments, the welding robot walking mechanism further comprises an origin correction device; wherein,,

the origin correction device comprises a positioning reference piece and a correction piece; wherein,,

the positioning reference piece is connected with the walking base;

the correcting piece is connected with the mobile platform, and is aligned and embedded into the positioning reference piece at a first set position; wherein,,

the first setting position is the origin position of the mobile platform.

In some specific alternative embodiments, the movable platform is provided with a guide groove, and the correcting element is in sliding fit with the guide groove along the height direction of the guide rail;

the origin correction device further comprises a limiting assembly, wherein the limiting assembly comprises a first limiting piece and a second limiting piece; wherein,,

the first limiting piece is arranged on the guide groove, and the second limiting piece is arranged on the correcting piece; the correcting piece slides along the height direction of the guide rail and limits movement at a second set position; wherein,,

the second setting position is the position of the correcting piece when the first limiting piece is abutted with the second limiting piece.

In some specific optional embodiments, the origin correcting device further includes an elastic member, one end of the elastic member abuts against the first limiting member, and the other end of the elastic member abuts against the second limiting member.

Drawings

Fig. 1 is a schematic structural diagram of a travelling mechanism provided in an embodiment of the present application;

FIG. 2 is a schematic diagram of the structure at A-A in FIG. 1;

fig. 3 is a schematic structural diagram of an origin correction device according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of a driving mechanism according to an embodiment of the present application.

1. A walking base; 11. a support; 111. a bending structure; 1111. a first bending structure; 1112. a second bending structure; 12. a guide rail; 121. a guide member; 122. a moving member; 2. a mobile platform; 3. a driving mechanism; 31. a rack; 32. a rotation driving mechanism; 33. a gear; 34. a backlash adjustment assembly; 341. a guide plate; 342. a mounting plate; 343. an adjustment assembly; 3431. an adjustment plate; 3432. a screw; 4. an origin correction device; 41. positioning a reference piece; 42. a correction member; 43. a guide member; 431. a guide groove; 441. a first limiting member; 442. a second limiting piece; 443. a blocking member; 45. an elastic member; 5. a welding robot; 6. a mounting platform; 7. a cable drag chain.

Detailed Description

The present application is further described in detail below by way of the accompanying drawings and examples. The features and advantages of the present application will become more apparent from the description.

The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are illustrated in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other.

For facilitating understanding of the travelling mechanism provided by the embodiment of the application, an application scene of the travelling mechanism is described first, and the welding robot travelling mechanism is used for driving the welding robot to move along a set movement track.

Welding robot walkers generally include a walking base and a mobile platform. The walking base comprises a supporting piece and a guide rail. The support is typically fixed to the mounting base. The moving platform is in sliding connection with the supporting piece through the guide rail, and moves along the length direction of the guide rail and moves relative to the supporting piece.

In order to ensure the better machining precision of the guide rail, the guide rail needs to be subjected to dustproof work so as to prevent dust and other foreign matters from entering the guide rail, and the service life of the guide rail is shortened. Therefore, the walking base is also required to be additionally provided with a dustproof shield to shield dust and other foreign matters.

Although the dustproof shield can prevent dust and other foreign matters from entering the guide rail, the mode of adding the dustproof shield to prevent dust on the guide rail can lead to the complex structure of the walking base. Therefore, the embodiment of the application provides a welding robot walking mechanism, which solves the problem that the structure of the existing walking base is complex because a dustproof shield is additionally arranged. The following detailed description is made with reference to the specific drawings and examples.

Reference is made to fig. 1 and 2 together. Fig. 1 is a schematic structural diagram of a running mechanism provided in an embodiment of the present application, and fig. 2 is a schematic structural diagram of a section at A-A in fig. 1. The welding robot walking mechanism comprises a walking base 1 and a mobile platform 2. The walking base 1 includes a support 11 and a guide rail 12 provided on the support 11. The mobile platform 2 is slidingly connected to the support 11 by means of a guide rail 12. The movable platform 2 can move relative to the support 11 along the length direction of the guide rail under the drive of the driving structure or the driving of manpower.

The welding robot walking mechanism also comprises, as an example, a welding robot 5 and a mounting platform 6. Wherein, mounting platform 6 sets up on moving platform 2, and welding robot 5 sets up on mounting platform 6. The welding robot 5 moves along the longitudinal direction of the guide rail 12 in synchronization with the moving platform 2.

For convenience of description, an XYZ coordinate system is constructed. Wherein, the X direction is parallel to the length direction of the guide rail 12, the Z direction is parallel to the height direction of the guide rail 12, and the Y direction is perpendicular to the X direction and the Z direction respectively.

Referring to fig. 1 and fig. 3 together, fig. 3 is a schematic structural diagram of an origin correction device 4 according to an embodiment of the present application. In some alternative embodiments, the welding robot walking mechanism further comprises an origin correction device 4. The origin correction device 4 includes a positioning reference 41 and a correction 42. Wherein the positioning reference member 41 is connected with the walking base 1. The correcting member 42 is connected to the moving platform 2, and the correcting member 42 is aligned with the positioning reference member 41 at the first setting position. The first setting position is an origin position of the mobile platform 2.

For example, the positioning reference member 41 is slidably connected to the walking base 1, the correcting member 42 is slidably connected to the moving platform 2, or the correcting member 42 is fixedly connected to the moving platform 2, so that the correcting member 42 and the positioning reference member 41 can move relatively, and the correcting member 42 is aligned at the first setting position and embedded in the positioning reference member.

The positioning reference member 41 is fixedly connected to the walking base 1, and the correcting member 42 is slidably connected to the moving platform 2, so that the correcting member 42 and the positioning reference member 41 can move relatively, and the correcting member 42 is aligned at the first set position and embedded in the positioning reference member.

The origin correction device of the welding robot generally adopts a scale type at present. That is, the first scale mark is provided on the traveling base, the second scale mark is provided on the mobile platform, and the mobile platform is returned to the origin position by aligning the first scale mark with the second scale mark. The first scale mark and the second scale mark are checked by naked eyes to determine whether the alignment is performed, and have certain errors and poor correction precision. The origin correction device 4 provided in the embodiment of the present application determines whether the positioning reference member 41 and the correction member 42 are aligned or not by means of the embedding cooperation of the positioning reference member 41 and the correction member 42 by means of a mechanical manner, and the correction accuracy is higher than that determined by naked eyes.

In some specific embodiments, the moving platform 2 is provided with a guide groove 431, and the correcting member 42 is slidably engaged with the guide groove 431 in the Z direction. The origin correcting device 4 further includes a limiting assembly. The stop assembly includes a first stop 441 and a second stop 442. The first limiting member 441 is disposed on the guide groove 431, and the second limiting member 442 is disposed on the correcting member 42. The correction member 42 slides in the Z direction and restricts movement at the second set position.

The second setting position is a position of the calibration member 42 when the first limiting member 441 abuts against the second limiting member 442. The correcting element 42 can not be separated from the guide groove 431 through the limiting function of the limiting component.

In some specific embodiments, the origin correction device 4 further comprises a guide 43. Wherein the guide 43 is provided on the moving platform 2 and the guide groove 431 is provided on the guide 43. Illustratively, the alignment member 42 may be a reference pin and the guide member 43 may be a reference pin mounting platform.

In some alternative embodiments, the origin correction device 4 further comprises a resilient member 45. The elastic member 45 is used for returning after the alignment member 42 is aligned with the positioning reference member 41. One end of the elastic member 45 abuts against the first limiting member 441, and the other end of the elastic member 45 abuts against the second limiting member 442. When the movable platform 2 moves to the first setting position, the correction piece 42 is manually pressed to make the correction piece 42 move downward in the Z direction to be embedded in alignment with the positioning reference piece 41, at which time the elastic piece 45 is compressed. When the correcting member 42 is released, the elastic member 45 will return to its original state, and the correcting member 42 will return to its non-pressed position under the action of the elastic force of the elastic member 45.

The elastic member 45 may be a spring or an elastic rubber member, for example. When the elastic member 45 is a spring, the spring is sleeved outside the correcting member 42.

In some specific embodiments, the end of the correction member 42 near the positioning reference member 41 protrudes from the guide groove 431, the end of the correction member 42 protruding from the guide member 43 is the protruding end, and the blocking member 443 is provided on the peripheral wall of the protruding end. Wherein, the blocking member 443 is used to abut against one end of the guiding member 43 near the positioning reference member 41, so as to prevent the correcting member 42 from being separated from the guiding groove 431 along the Z direction under the elastic force of the elastic member 45.

With continued reference to fig. 1 and 2. In some alternative embodiments, rail 12 includes a guide 121 and a moving member 122. The guide 121 is provided on the support 11, and the moving member 122 is provided on the moving platform 2. Wherein, the length direction of the guide member 121 is parallel to the X direction, a sliding groove is disposed on one side of the moving member 122 near the supporting member 11, and the guide member 121 is slidably engaged with the sliding groove. The moving member 122 slides on the guide member 121 in the X direction.

In some particular alternative embodiments, the chute has a trapezoidal cross-sectional shape. The guide member 121 has a protrusion cooperating with the chute, and the cross-sectional shape of the protrusion is trapezoidal.

The support 11 has a bending structure 111 bent toward the guide rail 12. The bending structure 111 in the embodiment of the present application is used to shield the guide rail 12 along the first plane. Wherein the first plane intersects the Z direction. That is, the included angle between the first plane and the Z direction is greater than 0 ° and less than 180 °. Specifically, the included angle between the first plane and the Z direction may be 30 °, 45 °, 60 °, 70 °, 80 °, 90 °, 105 °, 175 °, or the like.

The bending structure 111 provided by the embodiment of the application shields dust and other foreign matters for the guide rail 12 along the first plane, and a dustproof shield is not required to be additionally arranged, so that the problem that the structure of the current walking base is complex due to the fact that the dustproof shield is required to be additionally arranged is solved.

In the above embodiment it was mentioned that the side of the moving member 122 close to the supporting member 11 is provided with a chute. The side walls of the chute may shield the interior of the chute from dust and other foreign matter, reducing the likelihood of dust and other foreign matter entering the interior of the rail 12.

In some particular embodiments, the bend feature 111 is located above the rail 12. Dust and other foreign matter mostly enter the interior of the rail 12 by gravity. The bending structure 111 is located above the guide rail 12, and can shield most of dust and other foreign matters falling under the action of gravity for the guide rail 12 without additionally arranging a dust-proof shield, so that the problem that the structure of the existing walking base 1 is complex due to additionally arranging the dust-proof shield is solved.

In some embodiments, at least two of the bending structures 111 are arranged on both sides of the guide rail 12 in a row along the Z-direction of at least two bending structures 111. The bending structure 111 above the guide rail 12 can shield the guide rail 12 from most of the dust and other foreign matters falling under the action of gravity. The bending structure 111 below the guide rail 12 can shield the guide rail 12 from escaping dust and other foreign matters. By double shielding of the two bending structures 111, the possibility of dust and other foreign matter entering the interior of the guide rail 12 is reduced.

Furthermore, the support 11 needs to be provided on the installation basis. The bending structure 111 below the guide rail 12 can be connected with the installation foundation to enlarge the installation contact surface between the supporting piece 11 and the installation foundation and improve the installation stability of the supporting piece 11.

In some alternative embodiments, the length of the bending structure 111 in the Y direction is greater than the length of the rail 12 in the Y direction, so that the bending structure 111 can shield the entire rail 12 in the Y direction, reducing the likelihood of dust and other foreign objects entering the rail 12.

In some specific embodiments, the support 11 is a C-channel. The C-shaped channel steel comprises two leg plates and a waist plate. Leg plates are respectively connected with the opposite ends of the waist plate. The two waist plates are arranged on both sides of the guide rail 12 in a row along the Z direction. The two waist plates are used for shielding the guide rail 12 respectively. The waist plate above the guide rail 12 in the Z direction serves to shield the guide rail 12 from most of the dust and other foreign matter that falls under the force of gravity. Along the Z direction, the waist plate located below the guide rail 12 serves to shield the guide rail 12 from dust and other foreign matter that may escape partially.

In addition, the support piece in the prior art mostly adopts a square tube, and the cross section shape of the square tube is a mouth shape. The guide rail is arranged above the square tube. In this embodiment, the C-shaped channel steel is adopted, and the guide rail 12 is hung on the waist plate, which is equivalent to being arranged on the inner side wall of the square tube, so that the installation space of the walking base 1 is reduced, and the structure is more compact.

Reference is made to fig. 2 and 4 together. Fig. 4 is a schematic structural diagram of a driving mechanism 3 according to an embodiment of the present application. In some alternative embodiments, the welding robot walking mechanism further comprises a drive mechanism 3. The driving mechanism 3 includes a rack 31, a rotation driving mechanism 32, and a gear 33 engaged with the rack 31. Wherein the rack 31 is arranged on the side of the support 11 facing away from the guide rail 12. The rotation driving mechanism 32 is provided on the moving platform 2, and the rotation driving mechanism 32 is connected to a gear 33. The length direction of the rack 31 is parallel to the length direction of the guide rail 12. The rotation driving mechanism 32 drives the gear 33 to rotate, and the moving platform 2 moves relative to the walking base 1 under the meshing transmission action between the gear 33 and the rack 31. Illustratively, the rotary drive mechanism 32 is a motor, an output shaft of which is connected to the gear 33, and an axis of the output shaft of the motor and an axis of the gear 33 are on the same line.

In some specific embodiments, the drive mechanism 3 further comprises a cable drag chain 7, the cable drag chain 7 being connected to the mobile platform 2. Wherein the cable drag chain 7 is used for accommodating a cable connected with the driving structure.

In some specific alternative embodiments, the drive mechanism 3 further comprises a backlash adjustment assembly 34, the backlash adjustment assembly 34 being used to adjust the backlash between the gear 33 and the rack 31. At present, most domestic welding robot travelling mechanisms do not have a backlash adjusting function. After the driving mechanism is assembled, if the situation that the tooth gap between the gear and the rack is unsuitable occurs, the installed driving mechanism needs to be disassembled and reinstalled, so that the assembly difficulty is increased. According to the embodiment of the application, the backlash adjusting assembly 34 is additionally arranged, if the backlash between the gear 33 and the rack 31 is unsuitable, the driving mechanism 3 after installation is not required to be disassembled, and only the backlash between the gear 33 and the rack 31 is required to be adjusted through the backlash adjusting assembly 34, so that the assembly difficulty is reduced.

In some alternative embodiments, the backlash adjustment assembly 34 includes a guide plate 341, a mounting plate 342, and an adjustment assembly 343. The guide plate 341 is provided on the moving platform 2. The mounting plate 342 is slidably coupled to the guide plate 341 in the second direction. Wherein the second direction is perpendicular to the X direction and the second direction is perpendicular to the axial direction of the gear 33. The rotary drive mechanism 32 is provided on the mounting plate 342, and the gear 33 is located on the side of the mounting plate 342 near the support 11. Gear 33 moves in synchronization with mounting plate 342. The adjusting assembly 343 is disposed on the moving platform 2, and the adjusting assembly 343 is abutted to the mounting plate 342 for driving the gear 33 to move along the second direction.

The gear 33 is relatively close to or relatively far from the rack 31 in the second direction to adjust the backlash between the gear 33 and the rack 31.

When the gear 33 moves in the second direction close to the gear 33, the backlash between the gear 33 and the rack 31 decreases. When the gear 33 moves away from the gear 33 in the second direction, the backlash between the gear 33 and the rack 31 becomes large.

In some specific embodiments, the axis direction of the gear 33 is parallel to the Z direction, or the axis direction of the gear 33 is parallel to the Y direction. Wherein, when the axis direction of the gear 33 is parallel to the Z direction, the second direction is the Y direction. When the axis direction of the gear 33 is parallel to the Y direction, the second direction is the Z direction.

In some particular alternative embodiments, the adjustment assembly 343 includes two adjustment plates 3431 and two threaded rods 3432. Two adjusting plates 3431 are arranged in a row on both sides of the mounting plate 342 in the second direction, and the adjusting plates 3431 are arranged on the moving platform 2. The two screws 3432 are arranged on both sides of the mounting plate 342 in a row along the second direction, and the screws 3432 are screwed with the adjusting plate 3431, and the length direction of the screws 3432 is parallel to the second direction. One end of the screw 3432 abuts against an end surface of the mounting plate 342 adjacent to the adjustment plate 3431. When the screw 3432 rotates, the screw 3432 moves in the second direction relative to the adjustment plate 3431. The gear 33 is driven to be relatively close to or relatively far from the rack 31 in the second direction by moving the screw 3432 in the second direction, so as to adjust the backlash between the gear 33 and the rack 31.

Assuming that the two screws 3432 are a first screw and a second screw, the first screw is closer to the rack 31 than the second screw.

When the gear 33 moves in the second direction close to the gear 33, the first screw is rotated so that there is a certain gap between the first screw and the mounting plate 342. The second screw is then rotated, and the second screw pushes the mounting plate 342 toward the first screw side so that the backlash between the gear 33 and the rack 31 is reduced.

When the gear 33 moves away from the gear 33 in the second direction, the second screw is rotated so that there is a gap between the second screw and the mounting plate 342. The first screw is then rotated, and the first screw pushes the mounting plate 342 toward the second screw side, so that the backlash between the gear 33 and the rack 31 is reduced.

In the description of the present application, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc. are based on the directions or positional relationships in the working state of the present application, are merely for convenience of description and simplification of description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.

In the description of the present application, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly, unless explicitly specified and limited otherwise. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.

The present application has been described in connection with the preferred embodiments, but these embodiments are merely exemplary and serve only as illustrations. On the basis of this, many alternatives and improvements can be made to the present application, which fall within the scope of protection of the present application.

Claims

1. The welding robot walking mechanism is characterized by comprising a walking base and a mobile platform; wherein,,

the first plane intersects a height direction of the guide rail.

2. The welding robot walking mechanism of claim 1, wherein a length of the bending structure in a first direction is greater than a length of the rail in the first direction; wherein,,

3. The welding robot walking mechanism of claim 1, wherein the guide rail comprises a guide and a moving member; wherein,,

the bearing and guiding piece is in sliding fit with the sliding groove.

4. The welding robot walking mechanism of claim 1, wherein the support is a C-channel; wherein,,

the guide rail is arranged on the waist plate;

5. The welding robot walking mechanism of any of claims 1-4, further comprising a drive mechanism; wherein,,

6. The welding robot walking mechanism of claim 5, wherein the drive mechanism further comprises a backlash adjustment assembly; the backlash adjusting assembly comprises a guide plate, a mounting plate and an adjusting assembly; wherein,,

the guide plate is arranged on the mobile platform;

7. The welding robot walking mechanism of claim 6, wherein the adjustment assembly comprises two adjustment plates and two screws;

8. The welding robot walking mechanism according to any one of claims 1 to 4, further comprising origin correction means; wherein,,

the positioning reference piece is connected with the walking base;

the first setting position is the origin position of the mobile platform.

9. The welding robot running mechanism according to claim 8, wherein the moving platform is provided with a guide groove, and the correction member is slidably fitted with the guide groove in a height direction of the guide rail;

10. The welding robot running mechanism according to claim 9, wherein the origin correcting means further includes a resilient member, one end of the resilient member abuts against the first stopper, and the other end of the resilient member abuts against the second stopper.