CN211820289U

CN211820289U - Screw fastening assembly and anti-collision ball

Info

Publication number: CN211820289U
Application number: CN202020470542.6U
Authority: CN
Inventors: 张明轩; 乐君浩
Original assignee: Beijing Shinaigu Connection Technology Co ltd
Current assignee: Beijing Shinaigu Connection Technology Co ltd
Priority date: 2020-04-02
Filing date: 2020-04-02
Publication date: 2020-10-30
Anticipated expiration: 2030-04-02

Abstract

The utility model aims at the problem that extra fasteners and special mounting tools need to be prepared when the existing anti-collision ball is assembled, and provides a thread fastening component and an anti-collision ball, the thread fastening component comprises two half-thread columns and a locking knob, the diameters of the two half-thread columns are equal, a complete thread column can be formed, the bottom of the locking knob is provided with a threaded hole matched with the diameter of the thread column and a thread, the two half-thread columns are connected through the locking knob, and the half-thread columns are fixedly connected with a connected piece corresponding to the half-thread columns; the utility model provides an anticollision ball, wholly is cyclic annularly, includes two semi-rings, and the one end of two semi-rings is passed through the hinge joint structure and is connected, and hinge joint structure's articulated axis is parallel with the ball ring axis, and the other end passes through screw thread fastening subassembly fixed connection, two the half screw post respectively with correspond the semi-ring fixed connection of side, the axis of half screw post sets up with the axis of the semi-ring that corresponds is perpendicular.

Description

Screw fastening assembly and anti-collision ball

Technical Field

The utility model relates to a robot pipeline package accessory, in particular to screw fastening subassembly and anticollision ball.

Background

The anti-collision ball is a fitting on a robot pipeline packet, is fixed at the position where the corrugated pipe is easy to rub, prevents the corrugated pipe from directly contacting with the robot, protects the corrugated pipe and prolongs the service life of the corrugated pipe. The whole anti-collision ball is spherical and wraps the corrugated pipe of the pipeline package when in use. The anticollision ball usually includes two at least semi-rings, and the anticollision ball on the existing market need use fasteners such as bolt to connect two semi-rings mostly when the assembly, need prepare extra fastener and dedicated mounting tool during the assembly, and the assembly is complicated loaded down with trivial details relatively, and it is unusual inconvenient that on-the-spot workman changes spare parts.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a screw thread fastening subassembly and anticollision ball to the problem that needs prepare extra fastener and dedicated mounting tool when current anticollision ball assembly.

The above technical purpose of the present invention can be achieved by the following technical solutions:

the utility model provides a threaded fastening subassembly, includes two half-thread posts and locking knob, and the diameter of two half-thread posts equals can constitute a complete screw thread post, and locking knob bottom is provided with the screw hole with screw thread post diameter and screw thread looks adaptation, and two half-thread posts pass through locking knob to be connected, by half-thread post and rather than corresponding by connecting piece fixed connection.

Furthermore, a locking boss is arranged on one half thread column, a yield groove is arranged at the position, matched with the locking boss, of the other half thread column, the shape and size of the yield groove are matched with those of the locking boss, and when the two half rings are integrally formed into a spherical ring shape, the locking boss is positioned in the yield groove; the locking boss is provided with a locking hole coaxial with the corresponding half-thread column, the inner circumferential surface of the locking hole is provided with a locking clamping groove, an elastic locking clamping plate coaxial with the half-thread column is arranged in a threaded hole of the locking knob, and the outer side of the free end of the locking clamping plate is provided with a clamping block; when the locking knob is screwed down, the anti-loosening clamping plate is positioned in the locking hole, and the clamping block is positioned in the anti-loosening clamping groove.

Furthermore, a positioning plate is arranged in the threaded hole, the positioning plate and the anti-loosening clamping plate are arc plates with equal diameters and are coaxial with the locking knob, a connecting groove is formed in the side wall of the locking hole, and the connecting groove and the anti-loosening clamping groove are staggered; when the fixture block is positioned in the connecting groove, the threads on the locking knob are positioned above the half-thread column.

When the locking knob is screwed down and no external force acts on the anti-loosening strips, the vertical distance from the anti-loosening lug boss to the axis of the locking knob is smaller than that from the anti-loosening strips to the axis of the locking knob, and the free ends of the anti-loosening strips abut against the anti-loosening lugs.

Furthermore, a plurality of anti-slip ribs are arranged on the outer circumferential surface of the anti-loosening strip.

Furthermore, a groove is formed in the surface, opposite to the locking knob, of the locking strip, the shape of the groove is matched with that of the locking strip, and the locking strip can enter the groove when being extruded inwards.

The utility model provides an anticollision ball, wholly is cyclic annularly, includes two semi-rings, and the one end of two semi-rings is passed through the hinge joint structure and is connected, and hinge joint structure's articulated axis is parallel with the ball ring axis, and the other end passes through screw fastening subassembly fixed connection, the screw fastening subassembly is above-mentioned screw fastening subassembly, two half screw thread post respectively with the semi-ring fixed connection who corresponds the side, the axis of half screw thread post sets up with the axis of the semi-ring that corresponds is perpendicular.

Furthermore, the fixed end of the semi-ring is provided with a plane, the semi-threaded column and the anti-loosening boss are positioned on the plane, the hinged end is provided with a plane, the plane is provided with a connecting boss, the surface of the connecting boss, far away from the plane, is a spherical surface and is concentric with the spherical surface of the corresponding semi-ring in equal diameter, and the hinged structure is arranged on the connecting boss; the outer surface of each semi-ring is a spherical surface, and the top surface of each anti-loosening boss is a spherical surface and is concentric with and isodiametric to the spherical surface of the corresponding semi-ring; the top surface of the locking knob is a spherical surface and is equal in diameter to the spherical surface of the semi-ring, and when the locking knob is screwed down, the top surface of the locking knob is concentric with the semi-ring.

Furthermore, the inner wall of each half ring is respectively provided with a semicircular annular partition plate coaxial with the corresponding half ring; when the two semi-rings are integrally formed into a spherical ring shape, the partition plates on the two semi-rings are spliced into a ring shape; the inner ring of the ball ring is provided with at least two rings of clapboards, and a reinforced rib plate is fixedly connected between the adjacent clapboards.

Further, the hinge structure comprises an arc shaft and a shaft hole which are respectively arranged on the two hemispheres, the arc shaft is in the shape of a sector ring, the central angle of the sector ring is smaller than 180 degrees, the axis of the arc shaft is parallel to the axis of the corresponding hemisphere, and the shaft hole is matched with the arc shaft.

The utility model discloses following beneficial effect has:

the utility model discloses the screw-thread fastening subassembly of structure utilizes a complete screw thread post of two half-thread post amalgamation one, and locking knob and complete screw thread post threaded connection can make two unable relative movements of half-thread post, and the locking knob also is fixed on the screw thread post simultaneously, just so can be connected two by the connecting piece under the condition that need not with the help of extra instrument, and the dismouting operation is very simple and convenient, also need not extra fastener and dedicated mounting tool yet. Adopt the utility model discloses the anticollision ball of structure utilizes the one end that the screw fastening subassembly connects two semi-rings to connect the other end of two semi-rings through the hinge assembly, because the articulated structure is convenient for two semi-rings open and closed balling-up cyclic annular, the screw fastening subassembly can couple together two semi-rings under the condition that need not with the help of extra instrument, makes the holistic dismouting operation of anticollision ball very simple and convenient, also need not extra fastener and dedicated mounting tool.

Drawings

FIG. 1 is a schematic structural view of an embodiment of the anti-collision ball of the present invention;

FIG. 2 is a schematic view of the fastening ends of two half rings according to an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of a threaded fastener assembly according to an embodiment of the present invention;

fig. 4 is a schematic view of a locking knob according to an embodiment of the present invention;

FIG. 5 is a schematic view of the fastening end of the anti-collision ball of the present invention;

fig. 6 is a schematic view illustrating a fixture block located in a connection groove according to an embodiment of the present invention;

FIG. 7 is a schematic view of the hinged ends of two half rings in an embodiment of the invention;

figure 8 is a schematic cross-sectional view of a hinge assembly according to an embodiment of the present invention.

The description of the reference numerals,

10. a first half ring; 11. locking the boss; 12. a locking hole; 13. a locking clamping groove; 14. connecting grooves; 15. positioning a groove; 16. positioning the bump; 20. a second half ring; 21. a yielding groove;

30. a hinge structure; 31. a shaft hole; 32. an arc axis; 33. connecting the bosses;

40. a threaded fastener assembly; 41. a half-thread column I; 42. a half-thread column II; 43. locking the knob; 431. a threaded hole; 432. a side groove; 44. an anti-loosening clamping plate; 441. a clamping block; 45. positioning a plate; 46. a centering post; 50. an anti-loosening strip; 51. a locking boss; 52. a limiting edge;

60. a partition plate; 61. a reinforcing rib plate; 70. a fastening end; 80. a hinged end.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings. In which like parts are designated by like reference numerals.

An anti-collision ball is shown in figure 1 and is in a spherical ring shape integrally and comprises a first half ring 10 and a second half ring 20, wherein one end of the first half ring 10 is connected with one end of the second half ring 20 through a hinge structure 30, and the other end of the first half ring 10 is connected with the other end of the second half ring 20 through a threaded fastening assembly 40. For convenience of description, the end of the ball disposing threaded fastener assembly 40 will be referred to hereinafter as the fastening end 70, and the end of the hinge structure 30 will be referred to as the hinge end 80.

As shown in fig. 2 and 3, the threaded fastener assembly 40 includes a first half-threaded post 41, a second half-threaded post 42, and a locking knob 43. The half-thread column I41 is fixedly connected to the half ring I10, the half-thread column II 42 is fixedly connected to the half ring II 20, the two half-thread columns are respectively arranged at the fastening ends 70 of the corresponding half rings, the axis of each half-thread column is perpendicular to the axis of the corresponding half ring, and when the two half rings are closed, the two half-thread columns are spliced into a complete thread column. Referring to fig. 3 and 4, the bottom of the locking knob 43 is provided with a threaded hole 431 adapted to the above-mentioned complete threaded column, and the locking knob 43 is in threaded connection with the complete threaded column. The hinged structure facilitates the opening and closing of the two halves into a spherical ring shape, and the threaded fastener assembly 40 can connect the two halves without the aid of additional tools, and is very convenient to operate.

As shown in fig. 4 and 5, in order to prevent the locking knob 43 from being loosened, a loosening prevention bar 50 and a loosening prevention boss 51 may be provided, the loosening prevention bar 50 being provided on the side wall of the locking knob 43, and the loosening prevention boss 51 being provided on both half rings. The anti-loosening strip 50 is arc-shaped, the axis of the anti-loosening strip is parallel to the axis of the locking knob 43, the inner circumferential surface of the anti-loosening strip 50 faces the threaded hole 431, the distance from the connecting end of the anti-loosening strip 50 to the axis of the threaded hole 431 is smaller than the distance from the free end of the anti-loosening strip 50 to the axis of the threaded hole 431, and the anti-loosening strip 50 can be elastically deformed in the radial direction of the locking knob. The anti-loosening bosses 51 on the two half rings are arranged at the fastening ends 70 of the corresponding half rings, and the vertical distance from the anti-loosening bosses 51 to the axis of the corresponding half threaded column is greater than the radius of the locking knob 43. When no external force acts on the anti-loosening strip 50, the vertical distance from the free end of the anti-loosening strip 50 to the axis of the threaded hole 431 is larger than the vertical distance from the anti-loosening boss 51 to the axis of the threaded hole 431, when the locking knob 43 is screwed down, the free end of the anti-loosening strip 50 abuts against the limiting boss 51, and when the inner locking knob 43 is unscrewed, the free end of the anti-loosening strip 50 needs to move towards the limiting edge 103, so that the effect of preventing the locking knob 43 from being loosened is achieved. When the locking knob 43 is removed, the anti-loosening strip 50 can be manually pressed towards the threaded hole 431, so that the anti-loosening strip 50 can pass through the limiting boss 51. As shown in fig. 4, it is preferable that a side groove 432 is formed on a side wall of the locking knob 43, the side groove 432 is opposite to and matched with the locking bar 50 in shape, and the locking bar 50 can be inserted into the side groove 432 when being pressed inward, so that a sufficient space is left for elastic deformation of the locking bar 50. The outer circumferential surface of the anti-release strip 50 may be provided with an anti-slip rib to facilitate the application of force by rotation.

As shown in fig. 2 and 3, in order to prevent the locking knob 43 from being loosened, a locking hole 12 coaxial with the locking hole may be further provided on the first half-threaded column 41, and a locking notch 13 (see fig. 6) is provided on an inner side wall of the locking hole 12, as shown in fig. 3 and 4, an elastically deformable locking plate 44 is provided in a threaded hole 431 of the locking knob 43, a length and a width of the locking plate 44 are adapted to a depth and a width of the locking hole 12, and a free end of the locking plate 44 is provided with a locking block 441; when the locking knob 43 is screwed, the locking clamping plate 44 is located in the locking hole 12, and the clamping block 441 is clamped in the locking clamping groove 13, so that when no external force is applied, the locking clamping groove 13 can limit the circumferential movement of the clamping block 441, thereby limiting the rotation of the locking knob 43 and preventing the locking knob 43 from loosening. As shown in fig. 2, in order to provide the space required for providing the locking hole 12, a locking boss 11 may be provided at the fastening end of the first half-threaded column 41, a relief groove 21 adapted to the locking boss 11 may be provided on the second half-threaded column 42, and when the two half-rings are closed, the locking boss 11 is located in the relief groove 21. The side wall of the abdicating groove 21 can be provided with a positioning lug 16, and the anti-loosening clamping groove 13 penetrates through the locking boss 11; when the two half rings are closed, the positioning lug 16 is also positioned in the anti-loosening clamping groove 13, so that the two half rings are conveniently aligned. The two different anti-loosening structures can be arranged at the same time or independently.

The screwing length of the threads of the locking knob 43 and the half-thread column is one half of the corresponding thread pitch, so that the locking knob 43 can be locked by rotating half a turn. In order to facilitate the locking knob 43 to rotate 180 degrees, the locking fixture 411 just enters the locking slot 13, the positioning groove 15 may be disposed on the inner circumferential surface of the locking hole 12, the positioning groove 15 is disposed along the axial direction of the locking hole 12, and the positioning groove 15 is opposite to the locking slot 13, so that the locking fixture 411 may be inserted into the positioning groove 15 when being installed, and then the locking knob is rotated 180 degrees, and the locking fixture 411 enters the locking slot 13 from the positioning groove 15.

As shown in fig. 2, a coupling groove 14 may be provided on a side wall of the locking hole 12, as shown in fig. 3, the coupling groove 14 is offset from the locking groove 13, and the coupling groove 14 is provided in a rectangular shape. A positioning plate 45 is arranged in the threaded hole 431, and the positioning plate 45 and the anti-loosening clamping plate 44 are arc-shaped plates with equal diameters and are coaxial with the locking knob 43. As shown in fig. 6, when the clamping block 441 is located in the connecting groove 14, the threads on the locking knob 43 are located above the threads of the half-threaded column, and the two threads are not in contact with each other, so that when the locking knob 43 is not connected with two half-rings, the locking knob 43 can be clamped on the half-threaded column one 41 to provide a stable placing position for the locking knob 43, which is convenient for a user to take and place, and reduces the risk of losing the locking knob 43. In order to facilitate the processing, a complete tubular structure can be arranged, the tubular structure is matched with the locking hole, and the side wall of the tube is provided with two open slots arranged along the axial direction of the tube to divide the tube wall into two parts, so that an anti-loosening plate 44 and a positioning plate 45 are formed. As shown in fig. 2 and 3, the locking hole 12 is preferably provided with a centering column 46 coaxial therewith, and the centering column 46 is adapted to the inner wall of the pipe structure to prevent the locking plate 44 from being excessively deformed.

As shown in fig. 7 and 8, the hinge structure 30 includes a shaft hole 31 formed on the first half ring 10 and an arc shaft 32 fixed to the second half ring 20. The arc shaft 32 is in a shape of a column with a sector ring-shaped cross section, the central angle of the sector ring shape is smaller than 180 degrees, the axis of the arc shaft 32 is parallel to the axis of the second half ring 20, and the concave-convex directions of the arc shaft 32 and the second half ring 20 are opposite. The shaft hole 31 is an arc-shaped through hole and is matched with the arc shaft 32; when the arc shaft 32 is located in the shaft hole 31, the arc shaft can rotate around the axis of the shaft hole 31, the hinge structure 30 is convenient to separate, on one hand, two shell half rings can be conveniently opened, on the other hand, when the thread fastening assembly 40 is connected with the two shell half rings, the connection stability of the hinge end 80 can be ensured, the operation is very convenient during installation and disassembly, and the abrasion to the hinge structure 30 during disassembly and assembly is very small. Of course, the positions of the shaft hole 31 and the arc shaft 32 can be interchanged; the hinge structure 30 may also take other conventional forms such as hinges, pins, etc.

As shown in fig. 2 and 8, it is preferable to provide flats at the hinge end 80 and the fastening end 70 of the two half rings. The plane of the hinged end 80 is provided with a connecting boss 33, the connecting boss 33 is close to the radial end surface of the corresponding half ring, the surface of the connecting boss 33 far away from the plane is a spherical surface, the spherical surface and the spherical surface of the corresponding half ring are concentric and have the same diameter, the shaft hole 31 is arranged on the connecting boss 33 of the first half ring 10, and the arc shaft 32 is arranged on the connecting boss 33 of the second half ring 20. The half-thread column and the anti-loosening boss 51 are arranged on the plane of the fastening end 70, and the top surface of the anti-loosening boss 51 is a spherical surface and is concentric with the spherical surface of the corresponding semi-ring in equal diameter; the top surface of the locking knob 43 is spherical and has the same diameter as the spherical surface of the corresponding half ring, and when the locking knob 43 is tightened, the top surface of the locking knob 43 is concentric with the half ring. Thus, the hinge structure 30 and the threaded fastener assembly 40 do not protrude from the spherical surface of the two half rings when connecting the two half rings, and can be integrally formed with the two half rings to form a relatively round spherical surface.

As shown in fig. 1, the inner walls of the first half ring 10 and the second half ring 20 are both provided with a semi-circular partition 60 coaxial with the corresponding half ring, when the two half rings are in a spherical ring shape as a whole, the partitions 60 on the two half rings are spliced into a complete circular ring shape, and when the anti-collision ball wraps the corrugated pipe, the partitions 60 can extend into the concave on the outer wall of the corrugated pipe, so that the anti-collision ball is fixed relative to the corrugated pipe in the axial direction of the corrugated pipe. The inner ring of the ball ring is preferably provided with two or more than two rings of partition plates 60, for example, four rings of partition plates 60 are arranged in the present embodiment, and adjacent partition plates 60 are arranged at intervals, so that two sections of corrugated pipes can be respectively positioned by the partition plates 60 of different rings, the damaged or broken corrugated pipes can be temporarily connected, and the maintenance and replacement can be carried out after the equipment is shut down, which is helpful for ensuring the working efficiency of the equipment. It is preferable that a reinforcing rib 61 is fixedly connected between the partitions 60 of adjacent turns to reinforce the coupling strength between the partitions 60 and the half rings.

During installation, the corrugated pipe is placed in one of the half rings, the partition plate 60 extends into the recess of the outer wall of the corrugated pipe, the arc shaft 32 is inserted into the shaft hole 31, the two half rings are hinged, the other half ring is closed, the two half rings are integrally in a spherical ring shape, and the locking knob 43 is screwed down.

The specific embodiments are merely illustrative of the present invention, and are not intended to limit the present invention.

Claims

1. A threaded fastener assembly characterized by: including two half-thread posts and locking knob (43), the diameter of two half-thread posts equals can constitute a complete screw thread post, locking knob (43) bottom be provided with screw thread post diameter and screw thread looks adaptation screw hole (431), two half-thread posts pass through locking knob (43) to be connected, by half-thread post with rather than corresponding by connecting piece fixed connection.

2. The threaded fastener assembly of claim 1, wherein: one half of the threaded columns is provided with a locking boss (11), the other half of the threaded columns is provided with a abdication groove (21) at the position matched with the locking boss (11), the shape and the size of the abdication groove are matched with the locking boss, and when the two half rings are integrally formed into a spherical ring, the locking boss (11) is positioned in the abdication groove (21); a locking hole (12) coaxial with the corresponding half-threaded column is formed in the locking boss (11), a locking clamping groove (13) is formed in the inner circumferential surface of the locking hole (12), an elastic locking clamping plate (44) coaxial with the half-threaded column is arranged in a threaded hole (431) of the locking knob (43), and a clamping block (441) is arranged on the outer side of the free end of the locking clamping plate (44); when the locking knob (43) is screwed down, the anti-loosening clamping plate (44) is positioned in the locking hole (12) and the clamping block (441) is positioned in the anti-loosening clamping groove (13).

3. The threaded fastener assembly of claim 2, wherein: a positioning plate (45) is arranged in the threaded hole (431), the positioning plate (45) and the anti-loosening clamping plate (44) are arc-shaped plates with equal diameters and are coaxial with the locking knob (43), a connecting groove (14) is arranged on the side wall of the locking hole (12), and the connecting groove (14) is staggered with the anti-loosening clamping groove (13); when the clamping block (441) is positioned in the connecting groove (14), the threads on the locking knob (43) are positioned above the half-threaded column.

4. The threaded fastener assembly of claim 2, wherein: the anti-loosening device is characterized by further comprising anti-loosening bosses (51) fixedly connected to two connected pieces respectively, elastic anti-loosening strips (50) are fixedly connected to the side walls of the locking knobs (43), the anti-loosening strips (50) are arc-shaped, the axes of the anti-loosening strips are parallel to the axes of the threaded holes (431), the inner circumferential surfaces of the anti-loosening strips (50) face the threaded holes, when the locking knobs (43) are screwed down and no external force acts on the anti-loosening strips (50), the vertical distance from the anti-loosening bosses (51) to the axes of the locking knobs (43) is smaller than the vertical distance from the anti-loosening strips (50) to the axes of the locking knobs (43), and the free ends of the anti-loosening strips (50) abut against the anti.

5. The threaded fastener assembly of claim 4, wherein: the outer circumferential surface of the anti-loosening strip (50) is provided with a plurality of anti-slip ribs.

6. The threaded fastener assembly of claim 4, wherein: the surface of the locking knob (43) opposite to the anti-loosening strip (50) is provided with a groove, the shape of the groove is matched with that of the anti-loosening strip (50), and the anti-loosening strip (50) can enter the groove when being extruded inwards.

7. The utility model provides an anticollision ball, wholly is cyclic annularly, includes two semi-rings, its characterized in that: one end of each of the two half rings is hinged through a hinge structure (30), the hinge axis of the hinge structure is parallel to the axis of the ball ring, the other end of the hinge structure is fixedly connected through a threaded fastening component (40), the threaded fastening component (40) is the threaded fastening component (40) of any one of claims 1-6, the two half-threaded columns are respectively and fixedly connected with the half rings on the corresponding sides, and the axes of the half-threaded columns are perpendicular to the axes of the corresponding half rings.

8. The impact ball of claim 7, wherein: the fixed end of the semi-ring is provided with a plane, the semi-thread column and the anti-loosening boss (51) are positioned on the plane, the hinged end (80) is provided with a plane, the plane is provided with a connecting boss, the surface of the connecting boss, which is far away from the plane, is a spherical surface and is concentric with and isodiametric to the spherical surface of the corresponding semi-ring, and the hinged structure is arranged on the connecting boss; the outer surface of each semi-ring is a spherical surface, and the top surface of each anti-loosening boss (51) is a spherical surface and is concentric with and isodiametric to the spherical surface of the corresponding semi-ring; the top surface of the locking knob (43) is spherical and has the same diameter with the spherical surface of the semi-ring, and when the locking knob (43) is screwed down, the top surface of the locking knob (43) is concentric with the semi-ring.

9. The impact ball of claim 7, wherein: the inner wall of each half ring is respectively provided with a semi-circular clapboard (60) which is coaxial with the corresponding half ring; when the two semi-rings are integrated into a spherical ring shape, the partition plates (60) on the two semi-rings are spliced into a ring shape; the inner ring of the ball ring is provided with at least two rings of clapboards (60), and a reinforcing rib plate (61) is fixedly connected between the adjacent clapboards (60).

10. The impact ball of claim 7, wherein: the hinge structure comprises arc shafts (32) and shaft holes (31) which are respectively arranged on two hemispheres, wherein each arc shaft (32) is in a fan-shaped cylindrical shape, the central angle of each fan ring is smaller than 180 degrees, the axis of each arc shaft (32) is parallel to the axis of the corresponding hemisphere, and the shaft holes (31) are matched with the arc shafts (32).