CN212471776U - Punching equipment for racket frame - Google Patents

Abstract

The application relates to the technical field of punching equipment, in particular to a racket frame punching equipment which comprises a rack, wherein a bearing plate and a stepping motor are connected to the rack, the bearing plate is annular, a transmission gear is coaxially and fixedly connected to an output shaft of the stepping motor, an inner gear ring used for being matched with the transmission gear is coaxially arranged on the inner peripheral wall of the bearing plate, and the transmission gear is meshed with the inner gear ring; one surface of the bearing plate, which is far away from the rack, is a limiting surface, a positioning block is arranged on the limiting surface, and two limiting grooves for accommodating the end parts of the frame blanks are formed in the positioning block; the limiting surface is also provided with a plurality of limiting pieces for abutting the frame blank against the limiting surface, and the limiting pieces are uniformly distributed along the circumferential direction of the frame blank; still be connected with punching piece and locking piece in the frame, punching piece is located directly over the carrier plate, and the locking piece is located the regional that the carrier plate encloses. Through the cooperation of locating piece, locking piece, locating part and the piece of punching, improve the machining precision and the machining efficiency of line hole on the frame embryo.

Description

Punching equipment for racket frame

Technical Field

The application relates to the technical field of punching equipment, in particular to racket frame punching equipment.

Background

The badminton racket comprises a racket frame, a joint, a racket rod and a racket handle. Regarding the primary manufacturing process of the racket frame, a section of raw material strip with a rated length is generally cut firstly, and then a slot is formed in one side of the raw material strip, the slot extends along the length direction of the raw material strip, and the length of the slot is the same as that of the raw material strip; and then bending the raw material strips, generally calling the bent raw material strips as frame blanks, positioning the wire grooves on the outer peripheral wall of the frame blanks, and subsequently forming wire holes in the frame blanks along the circumferential direction of the frame blanks through punching equipment. The thread groove and the thread hole are arranged to facilitate the threading of the racket thread.

As shown in fig. 1, in the frame blank 29 of the badminton racket, the outer peripheral wall of the frame blank 29 is provided with the line slot 30, and in the process of forming the line hole in the peripheral wall of the frame blank 29, because the position locking of the frame blank 29 is often performed in a manual assistance mode, the situation that misoperation occurs frequently occurs, the processing precision of the whole line hole is poor, and the processing efficiency is low.

Therefore, a new technical scheme is needed to solve the problems of poor processing precision and low processing efficiency of the line holes.

SUMMERY OF THE UTILITY MODEL

Not enough to prior art exists, the purpose of this application is to provide a frame punching equipment claps, its machining precision that can not only improve the line hole to a certain extent, can also let the machining efficiency of line hole also obtain certain promotion.

The above utility model of this application aim at can realize through following technical scheme:

a frame punching device comprises a rack, wherein a bearing plate and a stepping motor are connected to the rack, the bearing plate is annular, a transmission gear is coaxially and fixedly connected to an output shaft of the stepping motor, an inner gear ring used for being matched with the transmission gear is coaxially arranged on the inner peripheral wall of the bearing plate, and the transmission gear is meshed with the inner gear ring; one surface of the bearing plate, which is far away from the rack, is a limiting surface, a positioning block is arranged on the limiting surface, two limiting grooves are formed in the positioning block, the two limiting grooves are not communicated with each other, one end of a frame blank is accommodated in one limiting groove, and the other end of the frame blank is accommodated in the other limiting groove; the limiting surface is also provided with a plurality of limiting pieces for abutting the frame blank against the limiting surface, and the limiting pieces are uniformly distributed along the circumferential direction of the frame blank; still be connected with punching piece and locking piece in the frame, punching piece is located directly over the carrier plate, and the locking piece is located the regional that the carrier plate encloses.

By adopting the technical scheme, two ends of the frame blank are accommodated by utilizing two limiting grooves formed in the positioning block, the frame blank is initially positioned on the bearing plate, and the frame blank is stably abutted against the limiting surfaces through the existence of a plurality of limiting parts, so that the frame blank is placed on the bearing plate;

then, the bearing plate is driven to rotate by means of the matching of the stepping motor, the transmission gear and the internal gear ring, and the frame blanks limited on the bearing plate are driven to rotate together; then, the punching piece and the locking piece are matched with each other to orderly complete the punching processing of the frame blank;

compared with the prior art that the position of the frame blank is locked in a manual auxiliary mode, the limiting of the frame blank can be quickly and accurately completed by utilizing the positioning block and the limiting part on the bearing plate, the punching precision of the frame blank can be improved to a certain extent, and the processing efficiency of the frame blank can be accelerated.

The present application may be further configured in a preferred example to: the limiting groove extends along the thickness direction of the bearing plate, elastic limiting blocks used for limiting the end parts of the frame blank are arranged on the inner walls of the two sides of the limiting groove, the distance between the two elastic limiting blocks is smaller than the diameter of the cross section of the frame blank, and the end parts of the frame blank are limited in the area between the two elastic limiting blocks and the bottom of the limiting groove.

Through adopting above-mentioned technical scheme, utilize the existence of two elasticity stoppers, the setting of cooperation spacing groove, it is convenient spacing on the loading board to accomplish the frame embryo tip.

The present application may be further configured in a preferred example to: the limiting piece comprises a first limiting plate and a second limiting plate, the first limiting plate is arc-shaped and is abutted against the inner peripheral wall of the frame blank, and the second limiting plate is abutted against the outer peripheral wall of the frame blank; one side of the second limiting plate, which faces the first limiting plate, is provided with an elastic lug which is arc-shaped and is abutted against the slot wall of the slot on the peripheral wall of the frame blank.

By adopting the technical scheme, after the limiting groove utilizes the two elastic limiting blocks to limit the end part of the frame blank, the rest part of the frame blank is further limited by utilizing the matching of the first limiting plate and the second limiting plate, so that the frame blank can stably abut against the limiting surface;

the elastic bump is arranged on the second limit plate to increase the contact area between the limit piece and the frame blank, so that the frame blank can obtain a better limit effect.

The present application may be further configured in a preferred example to: the locking piece comprises a locking cylinder and a locking block; the locking cylinder is connected to the frame, a piston rod of the locking cylinder extends towards the punching piece, and the extending end is fixedly connected with the locking block; a material groove is formed in one surface, facing the punching piece, of the locking block, and the motion trail of the punching piece penetrates into the material groove; when the piston rod of the locking cylinder extends out, the locking block is tightly propped against the inner peripheral wall of the frame blank.

Through adopting above-mentioned technical scheme, lean on spacing face when the frame embryo, utilize the locking cylinder to drive the locking piece and shift up, provide the support to the part that the frame embryo is located under the piece that punches to this ensures that the frame embryo can not take place great deformation under the piece effect that punches.

The present application may be further configured in a preferred example to: the punching part comprises an oil cylinder and a punching needle, the oil cylinder is connected to the rack, a piston rod of the oil cylinder extends downwards along the vertical direction, and the extending end is coaxially and fixedly connected with the punching needle; the perforating needle is sleeved with a conical protective sleeve.

By adopting the technical scheme, the punching needle is driven to move downwards by the oil cylinder, so that the punching operation of the frame blank is completed; the conical protective sleeve is arranged on the perforating needle to enhance the structural stability of the perforating needle, so that the probability of deflection of the perforating needle is reduced.

The present application may be further configured in a preferred example to: the limiting plate is connected with a limiting plate used for limiting the punching needles, the limiting plate is located between the punching piece and the locking piece, limiting needle through holes are formed in the limiting plate along the axial direction of the punching needles, and the motion tracks of the punching needles penetrate through the limiting needle through holes.

By adopting the technical scheme, the motion trail of the punching needle is further constrained by utilizing the existence of the needle limiting through hole; meanwhile, workers can also quickly judge whether the punching needle has the problem of position deflection by observing the abrasion condition of the inner wall of the needle limiting through hole.

The present application may be further configured in a preferred example to: the limiting surface is provided with a notch convenient for taking out the frame blank, and when the frame blank is abutted against the limiting surface, one part of the frame blank is projected in the notch.

Through adopting above-mentioned technical scheme, after the frame embryo accomplished processing, utilize the existence of scarce groove, the workman can take off the frame embryo from the loading board comparatively conveniently.

The present application may be further configured in a preferred example to: the rack is rotatably connected with a limiting wheel used for limiting the bearing plate, the limiting wheel is positioned above the bearing plate, the axial direction of the limiting wheel is consistent with the thickness direction of the bearing plate, and the outer edge of the bearing plate is abutted against the peripheral wall of the limiting wheel.

Through adopting above-mentioned technical scheme, utilize the existence of spacing round, do certain spacing to the position of loading board on the frame to this structural stability who strengthens the loading board.

To sum up, the application comprises the following beneficial technical effects:

1. the hole-punching operation of the frame blank is conveniently finished by matching the bearing plate, the stepping motor, the positioning block, the limiting piece, the locking piece and the punching piece, and the processing precision and the processing efficiency of the wire hole on the frame blank are improved;

2. the arrangement of the notches is utilized to facilitate the taking out of the frame blanks on the bearing plate;

3. the protective sleeve is arranged to protect the punching piece to a certain extent, so that the service life of the punching piece is prolonged to a certain extent.

Drawings

FIG. 1 is a schematic view of a frame blank of a badminton racket in the prior art;

FIG. 2 is a first schematic structural diagram of the present embodiment;

FIG. 3 is a second schematic structural view of the present embodiment with the locking member hidden;

FIG. 4 is an enlarged partial schematic view of portion A of FIG. 3;

FIG. 5 is an enlarged partial schematic view of portion B of FIG. 3;

FIG. 6 is a detail view of the punch in the present embodiment;

fig. 7 is a part view of the locking member in this embodiment.

Reference numerals: 1. a frame; 2. a carrier plate; 3. a stepping motor; 4. punching a hole; 5. a locking member; 6. an inner gear ring; 7. a transmission gear; 8. a support member; 9. a support bar; 10. a support block; 11. a limiting wheel; 12. a limiting surface; 13. positioning blocks; 14. a limiting groove; 15. an elastic limiting block; 16. a limiting member; 17. a first limit plate; 18. a second limiting plate; 19. an elastic bump; 20. an oil cylinder; 21. a perforating needle; 22. a protective sleeve; 23. a needle limiting plate; 24. a needle limiting through hole; 25. locking the air cylinder; 26. a locking block; 27. a trough; 28. notching; 29. a frame blank; 30. a wire slot.

Detailed Description

The present application is described in further detail below with reference to the attached drawings.

Referring to fig. 3 and 4, the racket frame punching apparatus disclosed in the present application includes a frame 1, wherein a supporting plate 2 and a stepping motor 3 for driving the supporting plate 2 to rotate are connected to the frame 1, and the supporting plate 2 is annular.

As shown in fig. 2 and 4, the frame 1 is further provided with a punching member 4 for processing the frame blank 29 and a locking member 5 for matching with the punching member 4, the punching member 4 is located above the bearing plate 2, and the locking member 5 is located in an area enclosed by the inner wall of the bearing plate 2.

Be equipped with internal gear circle 6 on the internal perisporium of loading board 2, step motor 3 output shaft extends along the thickness direction of loading board 2, extends the coaxial fixedly connected with drive gear 7 of end, drive gear 7 and internal gear circle 6 intermeshing.

The loading board 2 is erected on the frame 1 through two sets of supporting pieces 8, each set of supporting pieces 8 comprises a supporting rod 9 connected to the frame 1 and two supporting blocks 10 arranged on the supporting rod 9, the supporting rod 9 extends along the thickness of the loading board 2, the two supporting blocks 10 are abutted to the inner wall of the loading board 2, and the internal gear ring 6 is located between the two supporting blocks 10.

In order to further regulate the position of the bearing plate 2 on the frame 1, the frame 1 is also rotatably connected with a limiting wheel 11, the axial direction of the limiting wheel 11 is consistent with the thickness direction of the bearing plate 2, and the peripheral wall of the limiting wheel 11 is abutted against the outer edge of the bearing plate 2.

One surface of the bearing plate 2, which is far away from the rack 1, is called a limiting surface 12, a positioning block 13 is arranged on the limiting surface 12, limiting grooves 14 are formed in two sides of the positioning block 13, and the two limiting grooves 14 are not communicated with each other.

Every spacing groove 14 all link up locating piece 13 along loading board 2 thickness direction, all is equipped with elastic limiting block 15 on the both sides lateral wall of every spacing groove 14, and two elastic limiting block 15 intervals that are located same spacing groove 14 are lighter than the diameter of frame embryo 29 cross section, and frame embryo 29 one end is accomodate in one of them spacing groove 14, and frame embryo 29 other end is accomodate in another one spacing groove 14.

As shown in fig. 3 and 5, three limiting members 16 are further disposed on the limiting surface 12, and the three limiting members 16 are uniformly distributed along the circumferential direction of the bearing plate 2; each limiting member 16 includes a first limiting plate 17 and a second limiting plate 18; the first limiting plate 17 is arc-shaped, the inner peripheral wall of the frame blank 29 is abutted with one surface, facing the second limiting plate 18, of the first limiting plate 17, and the outer peripheral wall of the frame blank 29 is abutted with one surface, facing the first limiting plate 17, of the second limiting plate 18; the side of the second limit plate 18 facing the first limit plate 17 is further provided with an arc-shaped elastic lug 19, and the elastic lug 19 is abutted with the slot wall 30 on the outer peripheral wall of the frame blank 29.

The two limiting grooves 14 are used for accommodating the two ends of the frame blank 29 to be processed, so that the frame blank 29 obtains a certain position on the bearing plate 2, wherein the elastic limiting block 15 is arranged for further limiting the end part of the frame blank 29 and preventing the end part of the frame blank 29 from being easily separated from the limiting grooves 14.

After the position of the end of the frame blank 29 is determined, the rest part of the frame blank 29 is abutted against the limiting surface 12, and the rest part of the frame blank 29 is clamped and limited by the matching of the first limiting plate 17 and the second limiting plate 18, so that the frame blank 29 is confined in an elliptical area surrounded by the three limiting parts 16 and the positioning block 13; in order to increase the contact area between the limiting member 16 and the frame blank 29 and improve the limiting effect of the frame blank 29, the first limiting plate 17 is formed in an arc shape, and an elastic protrusion 19 is further disposed on a surface of the second limiting plate 18 facing the first limiting plate 17.

As shown in fig. 2 and 4, after the frame blank 29 is completely stopped on the stop surface 12, the worker starts the stepping motor 3, the punching member 4, and the locking member 5. Under the transmission effect of drive gear 7 and internal gear circle 6, step motor 3 can drive loading board 2 and rotate, and spacing frame embryo 29 on loading board 2 can follow loading board 2 and rotate, and every time frame embryo 29 rotates once, the piece 4 that punches just can carry out the operation of once punching a hole to frame embryo 29 perisporium correspondingly, and locking piece 5 also can correspond the effect and provide certain supporting role for frame embryo 29 to prevent that frame embryo 29 from taking place too big deformation under the effect of piece 4 that punches.

After the frame blank 29 rotates one circle, the stepping motor 3, the punching element 4 and the locking element 5 stop working, at this time, the positioning block 13 is located above the three limiting elements 16, and the punching element 4 is located right above the positioning block 13.

As shown in fig. 3 and 6, the punching member 4 comprises a punching needle 21 and an oil cylinder 20 for driving the punching needle 21 to move, the oil cylinder 20 is connected to the frame 1, a piston rod of the oil cylinder 20 extends downwards, and the extending end is coaxially and fixedly connected with the punching needle 21. During the intermittent rotation of the frame blank 29, the cylinder 20 drives the perforating needle 21 to move downwards, and the perforating needle 21 can complete the perforating operation on the peripheral wall of the frame blank 29 by the power provided by the cylinder 20.

Compared with a punching head on a common punching machine, the diameter of the punching needle 21 is relatively small, so that the punching needle 21 is easy to deflect and even deform and bend under the action of external force, in order to reduce the probability of deflection of the punching needle 21, the conical protective sleeve 22 is sleeved on the punching needle 21, the effect of the external force on the punching needle 21 is reduced by utilizing the existence of the protective sleeve 22, meanwhile, the structural stability of the whole punching needle 21 is improved, and the probability of deflection of the punching needle 21 is reduced.

In order to help workers to find the position offset of the perforating needle 21 in time, the frame 1 is also connected with a limiting needle plate 23, the limiting needle plate 23 is positioned under the perforating piece 4, the limiting needle plate 23 is positioned above the bearing plate 2, the limiting needle plate 23 is provided with a limiting needle through hole 24 along the axial direction of the perforating needle 21, and the motion track of the perforating needle 21 passes through a limiting ring. When the punching needle 21 passes through the needle limit through-hole 24 downward by the oil cylinder 20, the peripheral wall of the punching needle 21 abuts against the inner wall of the needle limit through-hole 24.

By utilizing the existence of the limiting needle through hole 24, a certain limiting effect is provided for the perforating needle 21 in the using process of the perforating needle 21, so that the structural stability of the perforating needle 21 is further improved; meanwhile, a worker can also quickly judge whether the punching needle 21 has serious position deviation according to the abrasion condition of the inner wall of the needle limiting through hole 24, so that the deviated punching needle 21 can be timely found and replaced after the punching needle 21 has the position deviation.

As shown in fig. 3 and 7, the locking member 5 includes a locking cylinder 25 and a locking block 26, the locking cylinder 25 is connected to the frame 1, a piston rod of the locking cylinder 25 extends toward the position of the punch 4, and the extending end is fixedly connected to the locking block 26. A trough 27 is formed in one surface, away from the locking cylinder 25, of the locking block 26, chamfers are formed in parts, located on two sides of the trough 27, of the locking block 26, when the locking block 26 moves upwards under the driving of the locking cylinder 25, the parts, located on two sides of the trough 27, of the locking block 26 are abutted to the inner peripheral wall of the frame blank 29, and when the punching needle 21 penetrates through the frame blank 29, the penetrating end of the punching needle 21 is located in the trough 27.

The locking block 26 is used for supporting the frame blank 29, so that the part of the frame blank 29, which is positioned right below the punching piece 4, can obtain a certain support, and thus, when the frame blank 29 is processed by the punching piece 4, the part of the frame blank 29, which is positioned right below the punching piece 4, cannot be easily deformed and bent.

In order to facilitate the taking out of the frame blank 29 from the limiting surface 12, two notches 28 are formed in the bearing plate 2, and the two notches 28 are symmetrically distributed on two sides of the positioning block 13; when the frame blank 29 abuts against the limiting surface 12, one section of the frame blank 29 projects into the notch 28.

The frame blank 29 and the bearing plate 2 are separated by a certain gap due to the existence of the notch 28, so that the fingers of a worker can extend between the frame blank 29 and the bearing plate 2, and the worker can conveniently take the frame blank 29 off from the bearing plate 2 after the frame blank 29 is processed.

The use process comprises the following steps:

one end of the frame blank 29 is placed in one of the limiting grooves 14, and the other end of the frame blank 29 is placed in the other limiting groove 14, so that the initial determination of the position of the frame blank 29 on the bearing plate 2 is completed.

Then the frame blank 29 is abutted against the limiting surface 12, the frame blank 29 is placed between the first limiting plate 17 and the second limiting plate 18, the first limiting plate 17 is abutted against the inner peripheral wall of the frame blank 29, the second limiting plate 18 is abutted against the outer peripheral wall of the frame blank 29, and at the moment, the elastic lug 19 is abutted against the groove wall of the wire groove 30 of the outer peripheral wall of the frame blank 29.

Then starting the oil cylinder 20, the locking cylinder 25 and the stepping motor 3, and under the transmission of the transmission gear 7 and the internal gear ring 6, the stepping motor 3 drives the bearing plate 2 and the frame blank 29 to move in a stepping manner; in the intermittent process of the rotation of the frame blank 29, the locking block 26 is driven by the locking cylinder 25 to move upwards and support the frame blank 29, the perforating needle 21 is driven by the oil cylinder 20 to move downwards and complete the punching process of the frame blank 29, then the piston rod of the locking cylinder 25 and the piston rod of the oil cylinder 20 are reset, and the frame blank 29 and the bearing plate 2 are driven by the stepping motor 3 to rotate again.

After the frame blank 29 is driven by the stepping motor 3 to rotate for a whole circle, the stepping motor 3, the locking cylinder 25 and the oil cylinder 20 stop, and at this time, a worker can take down the processed frame blank 29 through the notches 28 on the two sides of the positioning block 13.

The embodiments of the present invention are preferred embodiments of the present application, and the scope of protection of the present application is not limited by the embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims (8)

1. A racket frame punching equipment is characterized in that: the bearing plate is characterized by comprising a rack (1), wherein a bearing plate (2) and a stepping motor (3) are connected to the rack (1), the bearing plate (2) is annular, a transmission gear (7) is coaxially and fixedly connected to an output shaft of the stepping motor (3), an inner gear ring (6) used for being matched with the transmission gear (7) is coaxially arranged on the inner peripheral wall of the bearing plate (2), and the transmission gear (7) is meshed with the inner gear ring (6); one surface, away from the rack (1), of the bearing plate (2) is a limiting surface (12), a positioning block (13) is arranged on the limiting surface (12), two limiting grooves (14) are formed in the positioning block (13), the two limiting grooves (14) are not communicated with each other, one end of a frame blank (29) is accommodated in one of the limiting grooves (14), and the other end of the frame blank (29) is accommodated in the other limiting groove (14); the limiting surface (12) is also provided with a plurality of limiting pieces (16) for abutting the frame blank (29) against the limiting surface (12), and the limiting pieces (16) are uniformly distributed along the circumferential direction of the frame blank (29); still be connected with on frame (1) and punch piece (4) and locking piece (5), punch piece (4) and are located loading board (2) directly over, locking piece (5) are located the region that loading board (2) enclose.

2. The racket frame punching apparatus of claim 1, wherein: the limiting groove (14) extends along the thickness direction of the bearing plate (2), elastic limiting blocks (15) used for limiting the end portions of the frame blanks (29) are arranged on the inner walls of the two sides of the limiting groove (14), the distance between the two elastic limiting blocks (15) is smaller than the diameter of the cross section of the frame blank (29), and the end portions of the frame blank (29) are limited in the area between the two elastic limiting blocks (15) and the groove bottom of the limiting groove (14).

3. A racquet frame punch apparatus as claimed in claim 2, wherein: the limiting piece (16) comprises a first limiting plate (17) and a second limiting plate (18), the first limiting plate (17) is arc-shaped and is abutted against the inner peripheral wall of the frame blank (29), and the second limiting plate (18) is abutted against the outer peripheral wall of the frame blank (29); one surface of the second limiting plate (18) facing the first limiting plate (17) is provided with an elastic lug (19), and the elastic lug (19) is arc-shaped and is abutted against the slot wall of the slot (30) on the outer peripheral wall of the frame blank (29).

4. The racket frame punching apparatus of claim 1, wherein: the locking piece (5) comprises a locking cylinder (25) and a locking block (26); the locking cylinder (25) is connected to the rack (1), a piston rod of the locking cylinder (25) extends towards the punching piece (4), and the extending end is fixedly connected with the locking block (26); a trough (27) is formed in one surface, facing the punching piece (4), of the locking block (26), and the motion track of the punching piece (4) penetrates into the trough (27); when the piston rod of the locking cylinder (25) extends out, the locking block (26) is tightly propped against the inner peripheral wall of the frame blank (29).

5. The racket frame punching apparatus of claim 1, wherein: the punching piece (4) comprises an oil cylinder (20) and a punching needle (21), the oil cylinder (20) is connected to the rack (1), a piston rod of the oil cylinder (20) extends downwards along the vertical direction, and the extending end is coaxially and fixedly connected with the punching needle (21); the perforating needle (21) is sleeved with a conical protective sleeve (22).

6. The racket frame punching apparatus of claim 5 wherein: the limiting plate mechanism is characterized in that a limiting plate (23) used for limiting the perforating needle (21) is connected to the rack (1), the limiting plate (23) is located between the perforating piece (4) and the locking piece (5), a limiting needle through hole (24) is formed in the limiting plate along the axial direction of the perforating needle (21), and the limiting needle through hole (24) is penetrated by the motion track of the perforating needle (21).

7. The racket frame punching apparatus of claim 1, wherein: the limiting surface (12) is provided with a notch (28) which is convenient for taking out the frame blank (29), and when the frame blank (29) is abutted against the limiting surface (12), one part of the frame blank (29) is projected in the notch (28).

8. The racket frame punching apparatus of claim 1, wherein: the bearing plate is characterized in that a limiting wheel (11) used for limiting the bearing plate (2) is rotatably connected to the rack (1), the limiting wheel (11) is located above the bearing plate (2), the axis direction of the limiting wheel (11) is consistent with the thickness direction of the bearing plate (2), and the outer edge of the bearing plate (2) is abutted to the peripheral wall of the limiting wheel (11).

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