JP2002106538A - Screw part having locking function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a screw part to exert secure locking effect with simple structure at low cost. SOLUTION: In the screw part 1 comprising a screw head 2 and a foot 4 having a screw thread 3, a non thread part 10 sliding with an inside diameter of the internal screw 21 is formed on a leading end of the foot 4 having the screw thread 3 capable of screwing to an inside diameter of an internal thread 21 has the locking effect in which the non thread part 10 is of polygonal shape of triangle to hexagonal, therefore not only the locking effect is reduced in variation but also the screw part is resolved from screwing into with running off the thread. Since the inside of the internal thread is prescribed, the locking action is stable and reliability thereof is improved. Even when the screw part is made of austenitic stainless steel, a contraction percentage of the material is low at forging, thereafter the material can be sufficiently used for screw part so as to widen a range of usage for locking screw part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw component to be screwed into a female screw formed in a pilot hole of a work,
The present invention relates to a screw component having an anti-loosening action that makes it difficult for a looseness to occur between the screw component and a work due to vibration or impact.

[0002]

2. Description of the Related Art At present, a work is fixed to each other, and this fixing state is intended to prevent loosening of a fastening member, that is, to prevent loosening due to vibration or impact of a fastening action by a screw component as a fastening member. Various processes are performed mainly on the threads of screw parts, and adhesives are used. When the adhesive is used between the screw component and the work as described above, once loosened, the adhesive cannot be reused as it is, and the adhesive needs to be newly used each time. Also, depending on the material of the work, this adhesive may not be able to exert an adhesive effect at all, and thus it is necessary to confirm the material of the work in advance before using the material to confirm the effect.

[0003] Recently, many screw parts have been used which can easily obtain the loosening prevention effect by solving this problem. Among them, those whose use is increasing are shown in FIG. This is because the flank angles α and β on the advancing side and the play side of the screw thread 103 are formed to be equal in a normal screw part, but this angle is asymmetrical so that the female screw 121 and the leg screw thread 103 of the screw part 101 In between, the flank surfaces are brought into contact with each other or bite into each other, thereby having a locking effect. In addition, there is also one shown in FIG. This is because the normal thread is formed at 60 ° and the female screw 121 of the work 120 is formed.
On the other hand, when the screw thread angle is about 2/3 of the screw thread height, the screw thread angle is usually set to the angle θ ° (60 °) of the screw thread 103, / 3 is continuously formed as γ ° smaller than the above θ °, which is a so-called compound angle screw thread 103.
This tip thread diameter is formed slightly larger than the root diameter of the female screw 121, and the cross section of the leg 104 on which the thread 103 is formed is substantially triangular. Therefore, this leg 1
When the thread 103 of the work 04 is screwed into the female screw 121 of the work 120, it cuts into a valley of the female screw 121, whereby a loosening preventing action is generated.

[0004]

However, in the case where the flank angle of the thread is asymmetric as described above, the effect does not vary if the female screw of the preformed workpiece is always in a constant shape. However, in reality, the internal diameter of the internal thread is defined as a predetermined dimension, but since the valley diameter and the flank face of the internal thread are set relatively coarse, depending on the internal thread of the work in which the screw component is used, the screw may be screwed. The effect of preventing loosening is not sufficiently obtained, for example, the contact between the component and the female screw is insufficient, or the fitting is so tight that the screw component is not completely screwed. Further, even in a screw component having a composite thread having a different thread angle, since the root diameter of the internal thread is not constant, the tip thread of the composite thread does not bite sufficiently into the female screw, or conversely excessively bites. Its locking effect is not stable, and reliability has not been obtained.
Moreover, if the material of this screw part is austenitic stainless steel for corrosion prevention, the flow of the material is poor during cold heading, and the processing accuracy is reduced, especially in the formation of composite threads, and poor thread formation is caused. There are problems that occur.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a low-cost screw component which can exhibit a reliable loosening prevention effect with a simple structure.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a screw component comprising a head portion 2 having a driving hole 5 into which a driver bit is engaged, and a leg portion 4 having a thread 3 integrated therewith. Female screw 2 previously formed on work 20
A threadless portion 10 is formed at the tip of a leg portion 4 having a thread 3 that can be screwed into the threadless portion 10 to be in sliding contact with the internal diameter of the thread of the female screw 21. The external shape of the threadless portion 10 along the thread axis is polygonal. This is achieved by providing a shaped screw part having a locking action.

[0007] This object is also achieved by providing a screw part having the above configuration, in which the polygonal shape of the threadless portion 10 is triangular to hexagonal and has a locking action. Further, for this purpose, the threadless portion 10 in these configurations has a locus circular diameter connecting the vertexes 11 of a polygon having a slightly larger diameter than the inner diameter of the female screw 21 and also connects the vertices 11 of the polygon. The straight inscribed circle diameter is achieved by providing a threaded part with a locking action that is less than or equal to the inner diameter of the internal thread 21.

[0008]

FIG. 1 is a block diagram showing an embodiment of the present invention.
3 through FIG. In FIG. 1, 1 is a head 2
And a leg 4 having a thread 3 around the head 2 and the periphery. The head 2 of this screw part 1
On the center line of the leg portion 4, a driving hole 5 in the shape of a cruciform conical groove for engaging with a driver bit (not shown) is formed.
The drive hole 5 of the head 2 has a cross-conical groove shape, but is not limited to this. For example, a square, hexagonal or other groove or hole shape may be used. Nothing is restricted to this.

The head 2 is formed integrally with a cylindrical leg 4 having a smaller diameter than the head 2 on a seating surface 6 thereof.
Threads 3 are formed on the legs 4 at a predetermined pitch. The thread 3 formed on the leg 4 has a crest angle of usually 60 °, and a threadless portion 1 having no thread 3 is provided at the end of the leg 4 which is continuous with the thread 3.
0 is a predetermined length, that is, the thread 2 of the female screw 21 shown in FIG.
It is formed in the axial direction by a length corresponding to three peaks.
On the other hand, a tapered neck 7 having a large diameter on the head side is formed between the head 2 and the leg 4 on which the screw thread 3 is formed. And the leg 4 is prevented from breaking.

Further, as shown in FIG. 2, the non-threaded portion 10 has a polygonal shape having a triangular to hexagonal cross section which crosses the axis of the leg portion 4. As shown in FIG. The threadless portion 10 of the inner diameter A of the internal thread 21 formed in advance on the work 20 to which the set screw component 1 fits.
It has a locus circle diameter B diagonally connecting the polygonal vertices 11 having a slightly larger diameter, and the inscribed circle diameter of a straight line connecting the polygonal vertices 11 is smaller than the inner diameter of the female screw 21. It has a polygonal shape. That is, the unthreaded portion 10 is a female screw 2 formed in advance on the work 20.
1 is located at the tip of a leg portion 4 having a thread 3 which can be screwed into the threaded portion 1, and is in sliding contact with the inner diameter of the thread of the female screw 21. By having a polygonal shape like
The apex 11 of the threadless portion 10 is in sliding contact with the inner diameter of the female screw 21.

When the locking screw component 1 having such a shape is first press-fitted into the female screw 21 formed in advance on the work 20 and then screwed into the female screw 21, the screw component 1 becomes a thread 2-3 of the female screw 21. No thread part 10 against the mountain
Are screwed in contact with each other. At this time, the inner diameter of the female screw 21 is slightly elastically deformed at the non-threaded portion 10, and when the thread 3 of the screw component 1 is screwed in and the contact of the non-threaded portion 10 is deviated from the inner diameter, the original diameter is changed. Returns to the shape of Accordingly, when a force acts in the direction in which the screw component 1 is loosened, a resistance acts between the inner diameter of the female screw 21 and the apex 11 of the threadless portion 10, and the action of the loosening force is prevented, and the loosening screw component 1 is prevented. Becomes

[0012]

As is clear from the embodiments described above, the present invention comprises a head 2 having a driving hole 5 with which a driver bit is engaged and a leg 4 having a screw thread 3 integrated therewith. In the threaded component 1, a threadless portion 10 is formed at the tip of a leg 4 having a thread 3 that can be screwed into a female screw 21 formed in advance on a work 20, which is in sliding contact with the internal diameter of the female screw 21. Since the threaded part 1 has a loosening preventing action in which the outer shape of the threadless portion 10 along the thread axis is a triangular to hexagonal polygonal shape, there is a variation in the loosening preventing effect with respect to the female screw formed on the work. Is reduced, and it is also eliminated that the screw component is lifted and screwed. Further, even if the root diameter and the flank surface of the female screw are not constant, if the internal diameter of the female screw is specified, the locking action is stabilized, and the reliability is improved. Furthermore, even when the material of this screw part is made of austenitic stainless steel for corrosion prevention, the material is sufficiently used for the screw part because the drawing ratio of the material at the time of forging the legs of the screw part is small. Can be used, and the use of the locking screw component is expanded.

Further, the unthreaded portion 10 has a trajectory circle diameter connecting the vertices 11 of a polygon having a slightly larger diameter than the inner diameter of the female screw 21 and inscribes a straight line connecting the vertices 11 of the polygon. Since the threaded part 1 has a loosening preventing action whose circular diameter is equal to or less than the inner diameter of the female screw 21, the non-threaded portion in contact with the female screw is only at its apex. A press-fitted locking screw component that can be press-fitted accurately and can be easily screwed in thereafter is obtained. Moreover, since only three to six vertices are in contact when screwed in, the contact resistance during screwing is relatively small and the screwing torque during screwing is reduced. In addition, since the unthreaded part is processed together with the head forming by cold heading, high dimensional accuracy can be obtained, and adjustment of the length of this threadless part only requires adjusting the length of the die at the time of heading. Its length can be adjusted, and unique effects such as easy setting of the loosening prevention force can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view of a screw component according to an embodiment of the present invention.

FIG. 2 is a bottom view of the present invention.

FIG. 3 is an enlarged sectional view of a main part showing a screwed state of the present invention.

FIG. 4 is an enlarged sectional view of a main part showing a screwed state of a conventional example.

FIG. 5 is an enlarged sectional view of a main part showing a screwed state of another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw part 2 Head 3 Thread 4 Leg 5 Drive hole 6 Seat surface 7 Neck 10 Non-thread part 11 Vertex 20 Work 21 Female screw

Claims (3)

[Claims] A drive hole (5) with which a driver bit engages.
And a screw part composed of a head part (2) having a screw thread (3) and a head part (4) integral with the head part (2), can be screwed into a female screw (21) formed in advance on the work (20). A threadless portion (10) is formed at the tip of the threaded leg at the tip of the female screw to be in sliding contact with the internal diameter of the thread of the female screw, and the outer shape of the threadless portion along the thread axis is polygonal. A threaded part with a locking action. 2. The screw component having a locking function according to claim 1, wherein the polygonal shape of the non-threaded portion is triangular to hexagonal. 3. The non-threaded portion has a trajectory circle diameter connecting the vertices (11) of the polygon having a slightly larger diameter than the inner diameter of the female screw and an inscribed circle of a straight line connecting the vertices of the polygon. 3. The screw component having a locking function according to claim 1, wherein the diameter is not more than the inner diameter of the female screw.