JP3046122U - Use of screws, nuts or toy building elements with threaded parts and the use of torque limiting couplings in the connection of the elements - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw which can be manufactured by plastic injection molding and is composed of only a small number of components. The screw includes a head and a shank having a threaded portion that is screwed into a preformed hole having a corresponding threaded portion. The head and shank are provided on two separate parts, with a torque limiting coupling between the head and shank. This allows the components to rotate relative to each other when the torque between the components exceeds a predetermined value. The principle of the invention can also be applied to nuts, in which case the shank is replaced by a bushing having an internal thread.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention comprises a head and a shank having a threaded portion, the screw being capable of being screwed into a preformed hole having a corresponding threaded portion by the threaded portion, and a hole having a threaded portion. The present invention relates to a nut which has a main body formed with a thread and which can be screwed to a shank having a corresponding thread by the above thread.

[0002]

[Prior art]

 Plastic screws and nuts for structural (assembled) building sets have the problem that excessive tightening forces can damage the threads. This damage can occur in screws, nuts, or pre-formed shanks or holes.

In order to prevent the above-mentioned excessive load (load) from acting on the screw portion of the building element included in the toy building set, the applicant of the present application proposed a new toy building in the fall of 1992. The set was introduced, but in this building set, a tool with a screwdriver shape is provided with a torque-limiting ratchet device. Such toy building sets are sold under the trademark TOOLO® and are described, for example, in International Patent Applications PCT / DK92 / 0319 and PCT / DK92 / 0321.

[0004] The screw and the screwdriver cooperate, the tip of the shank of the screwdriver has a triangular cross-section, and the screw head has a hole formed with a corresponding cross-section. The screwdriver has a torque limiting coupling formed between the shank and the handle, which limits the amount of torque that the screwdriver can apply to the screw.

[0005]

[Problem to be solved by the invention] However, there is a problem in the building set of toys, and generally, plastic elements can only withstand relatively small torque, and therefore, the tool and the screw are not used. The connection between them must be specially designed to prevent the use of other unauthorized tools that do not have torque limiting couplings that could cause damage to building elements.

[0006] Torque limiting couplings are known and are described, for example, in British Patent Applications GB-A-2,022,199 and GB-A-2,141,999, French Patent Specification FR-B-1,376,669. German patent specifications DE-C-2,114,793, DE-C-2,163,109 and DE-C-2,915,526, British patent specification GB-B-661,543, GB B-952,253, GB-B-1,151,544, GB-B-1,330,631, and GB-B-1,472,484, German Offenlegungsschrift DE-A-2, 608,304, Danish published applications DK-B-148,118 and DK-B-155,509, and US patent specifications US 2,731,865, US 3,712,433 and US 4,131,03. 9.

[0007] Torque limiting couplings have also been used directly on screws and nuts, and teachings in this regard are available, for example, from US 2,373,812, US 2,685,812, US 3,789,524 and US 3, 425, 314. All such documents teach metal components, and plastic injection molding techniques apply very specific conditions, such as withdrawal of the core, and therefore apply the taught techniques to plastic components. It is not easy.

[0008]

[Means for Solving the Problems]

 The present invention is intended to provide a screw that can be manufactured by plastic injection molding and is composed of only a few components. The screw must have a built-in torque limiting coupling, which protects the thread of the screw from damage by applying a large torque to the head of the screw.

[0009]

[Embodiment of the invention]

 The above object is achieved by the present invention comprising a screw as described in the characterizing part of claim 1. With the present invention, a solid toothed rim is formed inside a hollow screw head member, thereby eliminating the double wall structure of such a member. This is extremely attractive, just as the head should have a thick outer wall to withstand the loads experienced by the screw head. Further, the wall on which the toothed rim is formed should have a thickness that is somewhat greater than the height of the teeth.

[0010] Finally, elastic teeth are formed on the inner part, which is hollow due to the withdrawal of the core in the molding operation, so that the elastic teeth are solid toothed. Can move freely away from the rim.

[0011] Therefore, the screw of the present invention can be formed and assembled without using a complicated process, so that the screw can be tightened using both the tools of the building set and the actual tools. Suitable for inclusion in a building set of formulas.

The present invention is intended to provide a screw that cooperates with a screw hole having a corresponding screw portion and that can be tightened without damaging the screw portion.

[0013] The object is achieved by the fact that the head and the shank of the screw are formed as two parts rotatably mounted on each other and that a torque limiting coupling is provided between the head and the shank. This is achieved by the invention in that the parts can rotate relative to each other when the torque between the parts exceeds a predetermined value.

According to the above configuration, the engagement surface of the screw head cooperating with the tool can be formed in an appropriate shape. The use of torque limiting couplings does not damage the threads when a child playing with a built-in building set containing such threads is tightened with real professional tools .

The screw can be operated by a finger, but preferably forms an engagement surface that can be operated by a tool. The engagement surface can be, for example, a slot in the end face of the screw or a screw head having a polygonal cross-sectional shape.

[0016] The torque limiting coupling used in the screw of the present invention includes an annular toothed rim provided on one part and a plurality of resilient teeth provided on the other part. The screw head preferably forms an annular toothed rim whose teeth project inward. In this case, the shank of the screw will have a plurality of radially outwardly facing resilient teeth adapted to engage the toothed rim. In a preferred embodiment where a screw is used to enhance the frictional connection between the two elements included in the building set of the toy, the screw should be moved so that the shank can move to some extent relative to the rest of the screw. Is preferably formed. For this purpose, the threaded component with the threaded head is provided with two axial shoulders, between which the projection of the shank component can move.

When a screw is formed by plastic injection molding, a hollow cylindrical body is formed in a shank, and a screw portion is provided at one end of the cylindrical body and a protruding portion is provided at the other end. It is effective. The resilient teeth are preferably connected to the cylinder via thin ribs to form part of such a protrusion. The slidable shank is preferably biased by an elastic element located inside said hollow cylinder.

According to the invention, the toothed rim may be formed asymmetrically, so that the pitch of the teeth is different in clockwise and counterclockwise directions. Therefore, the torque limit between the screwing and loosening operations is of different magnitude, whereby the loosening operation does not cause any problems. In a preferred embodiment, the screws of the present invention serve as the basis of a coupling head for connecting with other elements included in a toy building set. Then, the coupling head can be fixed to the screw as described in claim 11. If the screw is configured as described in claim 12, the screw may be a toy building set with box-shaped elements, for example of the type sold under the trademark DUPLO or TOOLO®. , So that a box-shaped element with screws can be connected to a box-shaped element with or without screw holes.

Claim 13 relates to a nut having a main body, wherein the main body is formed with a hole having a screw portion to be screwed into a preformed shank having a corresponding screw portion. . This hole is formed in the bushing, and the body and bushing are formed in two separate parts. A torque limiting coupling is provided between the body and the bushing so that when the torque between the two parts exceeds a predetermined value, the two parts can rotate relative to each other. The invention as set forth in the above claims is based on the same basic principles as the screw described above. In a general sense, the above principle can be described as the torque limiting coupling moving from the tool to the screw or nut contained in the structure.

Preferably, the nut forms an engagement surface for a tool that allows tightening. In a preferred embodiment, the torque limiting coupling of the nut comprises an annular toothed rim provided on one part and a radius provided elastically on the other part for engaging the toothed rim. A plurality of teeth protruding in the direction. Since the bushing has a cylindrical body, the annular toothed rim is preferably provided on the outside thereof, while the elastic teeth are provided on the head to engage the toothed rim. Face inward as shown. Preferably, the teeth of the toothed rim, as well as the resilient teeth, are asymmetrically shaped so that the torque limitation occurs with less torque during tightening of the screw than during loosening of the screw. .

Finally, the invention relates to a building element for a prefabricated building set, such a building element comprising a substantially box-shaped member on which integral screw parts are formed. This allows interconnection with other elements that have corresponding threaded components included in the prefabricated building set. Since the torque limiting coupling is provided between the member and the screw component, when the torque between the member and the screw component exceeds a predetermined value, the screw component rotates relative to the member. To be able to. The threaded component can be provided in the form of an external thread provided on a protruding shank or shaft, or an internal thread of a bushing.

In addition, the present invention provides a torquer having a cylindrical toothed rim on a screw or nut, wherein the threaded head and the shank / bushing can rotate relative to each other at a torque exceeding a predetermined value. Regarding the use of restriction couplings. The present invention will be described in detail below with reference to the drawings with reference to preferred embodiments.

[0023]

【Example】

 First, refer to FIG. FIG. 4 is a longitudinal sectional view of the screw of the present invention. The screw includes a head 1 and a shank 2 having a screw portion 3. This allows the screw to be screwed into a preformed hole with a corresponding thread, for example, a hole formed in an injection molded plastic building element included in a toy building set. Good. It can be seen that the head 1 and the shank 2 are provided on two separate parts 10,20. A torque limiting coupling 30 is provided between the head 1 and the shank 2 such that when the torque between the two parts 10, 20 exceeds a predetermined magnitude, the parts rotate relative to each other. Is allowed. The torque limiting coupling shown along section VI-VI corresponds to the coupling shown in FIGS.

In a preferred embodiment, the shank part 20 is manufactured in its entirety by plastic injection moulding, with the shank 2 formed with a thread 3 via a conical step 22. It has a converging cylindrical portion 23. The shank 2 terminates at an end wall. The inner wall of the step 22 serves as a shoulder 21 for a screw spring 25 extending in the longitudinal direction of the shank. The shank part 20 is formed at the other end of the cylindrical part 23 with an annular bead 24, which terminates at a resilient wing 37 via an axially extending boss 36. The wing is provided with teeth for engaging a toothed annular rim of the main part 10. This structure will be described later in more detail with reference to FIGS.

The main part 10 likewise has a cylindrical part 12, on the outside of which an engaging surface 11 for a tool (not shown) is formed. Surface 11 may have a hexagonal cross-section to fit a well-known clamp wrench. The cylindrical part 12 merges with another cylindrical part 14 via a step 13, which has a diameter which fits into a cylindrical part 23 of the shank part 20. This allows rotation between the two parts and provides a good guide between such parts.

On the outside of the cylindrical part 14 is formed an annular bead 15 having an axially extending wall and an inclined or conical guide wall. I have. Thereby, a box-shaped skirt 80 with a circular central opening is guided around the bead 15 of the part 14 and is held rotatably between said bead and the step 13. To this end, the step 13 is formed with an annular bead 13a for increasing the size of the engaging surface with the skirt 80. The squart 80 is locked to the cylindrical portion by an irreversible snap lock formed with an asymmetrical bead 15.

The other end of the cylindrical part 12 is provided with two beads 16, 17, one of which holds a coupling part 90 for a coupling part 90 which will be described later with reference to FIGS. It plays the role of a tool. The other bead 17 has a guide wall so that the coupling part 90 can move above the guide wall of the bead 17 and irreversible snap between the beads 16, 17 It is held inside the coupling.

Inside the cylindrical part 12 there is formed a toothed annular rim 31 corresponding to that which will be described later with reference to FIGS. The teeth of the toothed rim 31 have an axial length corresponding to the axial displacement of the shank part 20 in the chamber formed by the cylindrical portion 12. The shank part 20 is urged to the position shown in FIG. 4 by a spring 25, and the spring 25 applies pressure between the inner wall 21 of the step part 22 and the plug 91 of the coupling part 90. I have. The plug 91 has a central pin 92, which is effective because the spring 25 can be held in place. The bead 24 having the wings 37 of the shank part 20 can move the shank part 20 between the position where the bead engages the shoulder including the step 13 and the position where the bead engages the plug 91. Is allowed. Therefore, when a force greater than the spring force of the spring 25 is applied in the axial direction, the shank component 20 is pushed into the main component 10.

FIG. 3 shows the same structure exploded. It can be seen that the skirt 80 is in the form of a box, which in the preferred embodiment has four couplings provided on a structural building element of the type marketed under the trademark DUPLO (registered trademark). Can be connected to studs. This building element further has a threaded hole of the type indicated by reference numeral 66 in FIG. 12 and the connection between the coupling stud 67 and the skirt 80 is strengthened by screwing in the shank of the screw. can do.

Referring to FIGS. 2 and 3, the coupling component 90 has two prongs 93, each prong having a respective round protrusion 94 inside it. You can see that. FIG. 1 shows another type of coupling component 90 ′, which is secured to a screw in the same manner as coupling component 90 but includes a beak-like portion including a beak 97. The beak has a slot 96 and two concave portions 98 having a partial circular shape. When the coupling part 90 ′ is connected to the coupling part 90, the protruding part 94 is received in the concave part 98 due to the bending of the prong 93, while the tightening screw 95 is attached to the beak 97. Housed in a slot. The connection of the two coupling parts 90, 90 'can be maintained by tightening the screw 95, and the prong cannot bend until the screw 95 is loosened again. The screw of FIG. 1 is integrally connected to one of the structural elements 100 of the toy building set, such a structural element being known from International Patent Application No. PCT / DK92 / 00319 and coupling components 90 'A coupling component corresponding to' is formed.

FIG. 5 shows another embodiment of the screw of the present invention, which has a more conventional appearance, in contrast to the embodiment shown in FIGS. That is because the head 1 does not form one basis of the coupling mechanism of the building set of toys. In addition to the head 1, the screw comprises a shank 2 having a thread 3. The screws are screwed into complementary screw holes in other building elements, so that the plate member can be held by the shoulder 66 of the head 1. The head 1 further has a grip surface 11 for a tool. Rather, the screw can be formed with a wing to act as a finger operated thumbscrew. The shank 2 and the head 1 are two relatively rotatable parts interconnected via a torque limiting coupling corresponding to that shown in FIGS. The head 1 also has a cylindrical collar 64 which acts as a bearing for the shank 2, which stabilizes the relative movement of the two parts.

FIG. 6 is a cross-sectional view of a preferred embodiment of the torque limiting coupling 30 used with the nut or screw of the present invention. The coupling 30 comprises an outer part 31 comprising an annular rim with teeth therein. The outer part 31 has a bushing shape. The length of this bushing depends on whether the inner part 32 of the coupling 30 moves a predetermined amount in the axial direction. If the movement of the part 32 is allowed, the toothed rim of the part 31 corresponds at least to the distance of its movement plus the width of the contact part of the part 32 engaging this toothed rim. It has an axial length.

The toothed rim teeth 33 are shown as asymmetrical, which in a preferred embodiment is such that the pitch is 0 with respect to the bushing radius R in one direction. This is because an angle of from 10 to 10 °, preferably 2 to 5 °, and an angle of from 45 to 80 °, preferably 55 to 65 ° in another direction.

The inner part 32 has a bushing part 34 mounted coaxially with the outer part 31. In a preferred embodiment, the bushing part is formed with two bosses 36 projecting in the axial direction. A wing 37 extending in the peripheral direction of this component is fixed to a boss 36 at one end 35, and the other end is a free end. Thus, the outwardly facing teeth 38 of the wing 37 resiliently engage the toothed rim teeth 33 of the outer part 31.

As long as the torque in direction A between the inner part 32 and the outer part 31 is less than a given threshold, the coupling locks the two parts together. When the torque exceeds the threshold, the wings 37 are pressed inward in the direction indicated by arrow B in FIG. 7 and the teeth 38 move away from the teeth 33 of the toothed rim 39. When the torque exceeds the threshold, the parts 32, 31 can rotate with respect to each other in the direction indicated by arrow C, and the wing 37 performs a ratchet function. The inner part 32 and the outer part 31 are preferably manufactured by plastic injection molding and are therefore formed from a plastic material such as ABS. The torque threshold when the teeth are out of engagement is determined by parameters such as tooth pitch and the elasticity of the wings 37 and bosses 35, the elasticity being determined by the elastic modulus of the material and Depends on molding parameters.

Obviously, by changing the pitch of the teeth, it is also possible to limit the torque in the opposite direction. Also, a rim with external teeth can be formed on the coupling so that its elastic teeth face radially inward.

FIG. 9 is a perspective view of a preferred embodiment of the nut of the present invention. The nut, generally designated by the reference numeral 40, comprises a nut body 41, on the outside of which there is an operation for cooperating with a tool (not shown), for example in the form of a spanner. Surface 42 can be formed. The illustrated nut has a hexagonal cross section. The nut is formed with an annular bead 43 to provide a substantially round cross section at the axial end of the nut. Both ends of the nut 40 are provided with bushings having internal threads 45 for threaded engagement with shank having external threads. A torque limiting coupling of the type shown in FIGS. 6 and 7 is provided between each bushing 44 and the nut body 41. FIG. 8 shows a longitudinal section of the nut shown in FIG. The nut body is divided into two chambers 46 by a partition (partition) 47 integral with the nut body. On the left side of the chamber 46, a bushing 44 is provided, and it can be seen that an elastic wing 48 having teeth 49 is engaged with the toothed rim 50 of the nut body. The toothed rim 50 is shown on the right side of the chamber 46, and the bushing 44 is omitted here for the same reason. A bushing 44 is held in the two chambers 46, and the two parts are each formed with a bead 51 and a groove 52, thereby providing an irreversible snap lock after installation.

FIG. 10 is an exploded view of the same nut as that shown in FIGS. 8 and 9. In this figure, the annular beads 51 are more clearly shown. The bushing 44 also has a reduced diameter portion 54 that provides clearance for the toothed rim 50, while the adjacent portion 53 is located inside the chamber 46. It serves as a bearing wall for the cylindrical wall.

FIG. 11 illustrates the use of the screw of FIG. 5, where the screw is designated by the reference numeral 60. Four screws 60 of the type described above hold the plate-like building element 61 of the frame structure 62 attached to the beam-shaped building element 63 of the structural building set. The building element 63 is provided with a screw hole corresponding to the shank of the screw 60, and the plate 61 has a hole through which the shank of the screw 60 can pass without being disturbed. Only some of such holes are shown and can be added as needed, but the holes are aligned with modules corresponding to other building elements of the toy building set. Is convenient.

The bottom 65 of the vehicle is shown in FIG. 12, which is known from International Patent Application No. PCT / DK 92/00319. The bottom 65 of this vehicle differs from the bottom of the vehicle shown in the international patent application in that a threaded hole along the side of the element is formed with a torque limiting coupling of the type shown in FIGS. Is different. Therefore, the longitudinal section along the line VI-VI corresponds to the torque limiting coupling shown in FIGS. 6 and 7, and the outer part 31 has axial ribs or grooves facing outward. This allows the outer part to be held together with or integral with the bottom member of the vehicle. For manufacturing reasons, it is usually preferred that the torque limiting coupling be formed as a separate insert element which is plastic injection molded. In the method of use shown in FIG. 12, the inner part 32 is formed with an internal thread extending in the axial direction of the bushing. A coupling stud 67 is further formed on the bottom of the vehicle, and a screw hole 66 is provided between the coupling studs.

Because the teeth of the torque limiting coupling are asymmetrical, the nut or screw can be securely tightened with a torque less than a predetermined threshold, and then by applying a rather large torque. Can be loosened.

The present invention is suitable for implementation on plastic injection molded products, but is effective, for example, for complex toys where a plastic screw is screwed into a wooden block with screw holes. The present invention is not limited to such plastic injection-molded products, as it can be implemented in any of the aforementioned ways.

[Brief description of the drawings]

FIG. 1 is a perspective view of a screw according to the present invention;
It is screwed into a building element included in the building set of the toy, and the screw is formed with a coupling means in the form of a gripping claw for connecting to another building element.

FIG. 2 is a perspective view of the screw of the present invention corresponding to the screw shown in FIG. 1, wherein the grip pawl is replaced by a coupling means instead of the grip pawl;

FIG. 3 is an exploded view of the screw shown in FIG. 2;

FIG. 4 is a longitudinal sectional view of the screw shown in FIG. 2;

FIG. 5 shows another embodiment of the screw of the present invention.

FIG. 6 shows a torque limiting coupling used in the screw or nut of the present invention.

FIG. 7 shows the coupling of FIG. 6 without teeth engaged because the applied torque exceeds a predetermined level.

FIG. 8 is a longitudinal sectional view of a preferred embodiment of the nut of the present invention.

FIG. 9 is a perspective view of the nut shown in FIG. 8;

FIG. 10 is an exploded view of the nut shown in FIG.

11 shows a structure in which a plate is fixed to a frame using four nuts shown in FIG. 8;

FIG. 12 shows a torque limiting coupling used in the building element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head 2 Shank 3 Screw part 10, 20 Parts 11 Engagement surface 30 Torque limiting coupling 31 Rim 32 Teeth

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[Procedure amendment]

[Submission date] August 21, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims for utility model registration

[Correction method] Change

[Correction contents]

[Utility model registration claims]

Claims (15)

[Utility model registration claims] 1. A head (1) and a shank (2) having a thread (3) screwed into a preformed hole having a corresponding thread, the head (1) and the shank. (2) is formed in two separate parts (10, 20), between the head (1) and the shank (2) a torque limiting coupling (30) is provided. A screw that allows the parts to rotate relative to each other when the torque between the parts (10, 20) exceeds a predetermined value, wherein the torque limiting coupling (30) comprises: One part (1
0) provided with an annular, inwardly facing toothed rim (31), and a plurality of outwardly facing teeth (32), the plurality of teeth having elasticity and , So as to engage the toothed rim (31).
0) Screws characterized in that they are arranged radially above. 2. The screw according to claim 1, wherein said head has an engagement surface (11) formed thereon, and said head can be operated by a tool using said engagement surface. Screws. 3. The screw (1) according to claim 1, wherein the part (10) including the head (1) has a cylindrical body (1) having the annular toothed rim (31) provided inside.
2) wherein the resilient teeth (32) are provided on the part (20) with the shank (2) and are externally engaged to engage the toothed rim (31). Screws characterized by facing. 4. The screw according to claim 1, wherein the cylindrical body (12) of the main part (10) has two fasteners allowing the axial movement of the shank part (20). (1
3, 91), and the movement of the shank part is performed by the two fasteners (13, 9).
1) and a protrusion (2) radially provided on the shank.
4, 37) characterized in that they are limited by the cooperation between them. 5. The screw according to claim 1, wherein the shank part (20) has a central cylindrical part (23).
A hollow cylindrical body having an opening at one end and terminating at a radial annular protrusion (24, 37); Wherein the other end is closed and terminated at a step (22) of the threaded portion (3). 6. The screw according to claim 5, wherein said resiliently provided teeth (38) are thin pins (36).
A screw which is integral with the cylindrical body (23) through a through hole and constitutes a part of the annular protrusion (24, 37). 7. The screw according to claim 5, comprising a resilient element (25) for axially biasing the head (1) and the shank (2) of the screw. 8. The screw according to claim 1, wherein said toothed rim teeth (33) and said resilient teeth (3) are provided.
8) A screw having an asymmetric shape in which different pitches in a clockwise direction and a counterclockwise direction are respectively formed in the annular direction. 9. The screw according to claim 1, wherein the screw head (1) is formed with a coupling head (90) facing in a direction opposite to the shank (2). A screw characterized in that the coupling head (90) is adapted to be removably connected to an element incorporated in the toy building set. 10. The screw according to claim 9, wherein the coupling head (90) is attached to the screw head (1) by an irreversible snap coupling, wherein the screw head (1) is connected to the coupling head. Head (9
0) comprising a cylindrical part having a bead (17) housed in a corresponding opening, said coupling head (90) being adapted to be housed in said cylindrical part. A screw having a cylindrical protrusion (91) arranged coaxially with the opening. 11. The screw according to claim 1, wherein the screw head (1) is adjacent to a rotatably mounted box-shaped part (80), the box-shaped part comprising: It has coupling means for connecting to building elements incorporated into a building set of toys, said shank (2) at one end position comprising:
It protrudes beyond the box-shaped part (80), and at the other end position, the part (8)
A screw which is completely located in 0). 12. A body (41) having a hole having a threaded portion (45) that is screwed into a preformed shank having a corresponding threaded portion, said hole being provided in a bushing (44). The body (41) and the bushing (44) are provided in two separate parts, and a torque limiting coupling () is provided between the body (41) and the bushing (44). 49, 50), whereby the parts (41, 44) are able to rotate relative to each other when the torque between these parts exceeds a predetermined value. Wherein the torque limiting coupling (49, 50) is provided on one part and has an inwardly facing annular toothed rim (50); and a plurality of outwardly facing teeth (49). And these teeth are A nut characterized by being resilient and radially arranged on said other part to engage said toothed rim (50). 13. The nut according to claim 12, wherein the body (41) has an engagement surface (42) formed thereon, and the body can be operated by a tool using the engagement surface. A nut characterized by being made as described above. 14. The nut according to claim 12, wherein said bushing comprises a cylindrical part having said resiliently arranged teeth (49) provided on the outside thereof, and said annular toothed part. A nut, wherein the rim (50) is provided on the body and faces inward to engage the teeth (49). 15. The nut according to claim 12, wherein the teeth of the toothed rim (50) and the resiliently arranged teeth (49) are formed asymmetrically. Accordingly, the nut has different pitches in a clockwise direction and a counterclockwise direction in the annular direction.