JPS6056927B2 - Loosening prevention screw - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a locking screw.

(Prior art) Various proposals have been made for anti-loosening screws with various deformations of the threads, but the ones that are highly effective have the disadvantage of having a complicated structure and high production costs, making them less marketable. On the other hand, in general, products with simple configuration and good productivity were not very effective.

For example, Utility Model Publication No. 51-479 as one of the prior art of the present application.
There is a locking bolt disclosed in the 5th official bulletin.

As shown in FIG. 3, this locking bolt 11 is made by removing an appropriate number of threads 13 formed on a threaded portion 12 in the axial direction to form a cutout portion 14, and the end of the thread facing the cutout portion 14. A biting tooth portion 15 is formed in the portion 13a by changing the lead angle from that of the other portions. (Problems to be Solved by the Invention) However, according to the above-mentioned conventional technology, the resection portion 1
4 and the biting tooth portion 15 are not easy to process, and it is difficult to obtain a certain quality.

Further, the relationship between the normal thread 13 of the bolt 11 and the anti-loosening thread 13a with a changed lead angle is as shown in the explanatory diagram of FIG. 4A, which conceptually shows the state in which it is screwed into a nut. be. In this case, tightening is applied between the pressure side bolt thread surface B, , and the pressure side nut thread m concave, and when the return force acts as shown by the arrow, the pressure side bolt thread surface B, , is tightened. Biting teeth 15 are on the pressure side nut thread surface N
2. It bites into and exerts a loosening prevention function. Therefore, even if you try to remove and reuse a nut that has been tightened once, the pressure side nut screw will be removed by the biting teeth 15 when loosening, and the force guard will be removed and damaged, so it cannot be reused. It is impossible. Therefore, an object of the present invention is to provide a loosening prevention screw that improves these problems of the prior art. (Means for Solving Problems) The gist of the present invention is to prevent each loosening by a certain lead angle selected within a range smaller than a normal thread from zero to a loosening prevention part provided in a part of the main body of the screw. A prevention thread is formed, and the starting end of the thread is continuous with the normal thread, and then gradually shifts toward the play side, causing a positional deviation of up to 112 pitches at the terminal end with respect to the normal thread. This is a loosening prevention screw configured as follows.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. Fig. 1 shows a loosening prevention screw according to the present invention, which has a hexagonal head 1,
The screw main body 2 includes a threaded main body 2 with a thread carved into the shaft part.
As with a normal screw, a thread 3 of peaks and valleys is formed at a predetermined pitch P1 with a certain lead angle line 11 as the apex, and a part of the main body 2 of the screw is provided with a loosening prevention part 4. be.

This loosening prevention portion 4 has a pitch P2 equal to the pitch P1.
The lead angle line 12 is perpendicular to the axial direction C of the screw.
(i.e., zero lead angle) loosening prevention screw thread 5
Multiple mountains are formed.

The loosening prevention threads 5 are formed continuously with the threads 3 at the starting end 4a of the loosening preventing portion 4, but do not match at the terminal end 4b because the lead angle difference between the two is 0. This causes a positional deviation d. That is, since the normal thread 3 and the thread 5 for preventing loosening have different lead angles, the thread 5 for loosening preventing loosening gradually deviates toward the play side and shifts from the starting end 4a to the terminal end 4b.

This positional deviation d is determined by the difference θ between both lead angles and the loosening prevention part 4.
Although it differs depending on the width h provided, it is desirable that the pitch be within 112 pitches at the maximum as a condition for screwing. For example, when the lead angle is set to zero to work most effectively against loosening as in the above embodiment, the width h is 1 of the circumference.
12, and even when the lead angle difference θ is minimized as it approaches a normal screw, it is kept below the circumference, and the starting end and the ending end do not overlap in any case. In the above embodiment, the loosening preventing portion 4 is provided at one location, but it is also possible to provide the loosening preventing portion 4 at two or more locations as desired.

However, in any case, it is desirable to leave about two normal screw threads 3 at the tip of the screw main body 2 to facilitate screwing. Further, the lead angle of the thread 5 for preventing loosening can be arbitrarily selected in the range from zero to the four lead angles of the normal thread 3 so as to obtain the desired tightening and disengaging torque.
Next, a rolling die for forming the above-mentioned loosening prevention screw will be explained below.

As shown in FIG. 2, a rolling thread surface 6a for rolling the normal thread 3 is formed on the moving die 6 by peaks and valley bottoms arranged in parallel at a predetermined lead angle and pitch, A notch 6b is provided on the rolling end side of the die 6.

On the other hand, a chip die 7 is provided which has a deformed thread surface 7a having peaks and valleys parallel to the thread rolling direction (zero lead angle) at the same pitch as the rolled thread surface 6a. It is removably fitted into the notch 6b. The die 6 and the chip die 7 are joined by aligning the peaks and valley bottoms of both thread surfaces 6a and 7a at the starting end h1 and making them continuous, and at the terminal end h1 due to the difference in the lead angles of both sides, a maximum of 112 pitches are formed. Destination position deviation d
It is formed so as to cause

The die 6 is used to roll the loosening prevention screw in cooperation with a corresponding fixed die (not shown), and the thread material, which has been pressed in advance with a header etc., is rolled on the threaded surface 6a.
Screw threads 3'' are sequentially formed while rolling the top part.Then, when the thread reaches the chip die 7 provided at the end of the rolling process,
The deformed thread surfaces 7a having different lead angles are forcibly pressed and deformed to form the loosening preventing screw threads 5 with a predetermined length h, thereby making it possible to obtain the loosening preventing screw shown in FIG. 1. In the screw of the present invention having the above-mentioned configuration, the relationship between the normal thread 3 and the loosening prevention thread 5 is as shown in FIG. 4B. In this case, the action of the tightening force is the same as in the conventional example shown in FIG. is prevented. Therefore, even if the once-fastened nut is loosened, there will be no damage like in the conventional example, and even if there is some deformation, it can be removed and reused. (Effects of the Invention) As is clear from the examples described above, the loosening prevention screw thread of the present application has an extremely simple structure, so it can be mass-produced at low cost and with uniformity like ordinary thread rolling, and can achieve the desired tightening. The attaching and disengaging torque can be arbitrarily selected.

Moreover, the structure allows reuse without damaging the mating nut.

[Brief explanation of drawings]

FIG. 1 is a front view of a loosening prevention screw according to an embodiment of the present invention;
Fig. 2 is an explanatory diagram of a rolling die for the same screw, Fig. 3 is a front view showing a conventional loosening prevention screw, and Fig. 4 is an explanatory diagram showing the relationship between a normal screw thread and a loosening prevention screw thread. It is. Explanation of symbols, 1...Head, 2...Screw main body, 3...Screw thread, 4...Loosening prevention part, 4
a, h1...Starting end, 4b, 112...
・Terminal part, 5...Screw thread for preventing loosening, 6...
...Dice, 6a...Rolled thread surface, 6b...
...Notch, 7...Chip die, 7a...
...Deformed thread surface, C...Axis direction, h...
... Width of loosening prevention part, 11, 12 ... Lead angle wire, Pl, P2 ... Pitch, d ...
Positional deviation, θ...Difference in lead angle.

Claims (1)

[Claims] 1. A part of the screw main body 2 with a normal thread 3 has a loosening prevention part with a width h shorter than the circumferential length of the screw main body 2, and the loosening prevention part has a lead angle from zero to A plurality of loosening prevention screw threads 5 having a constant lead angle selected within a range smaller than the lead angle of the normal screw thread 3 are provided, and each loosening prevention screw is provided at the starting end 4a of the loosening prevention part 4. The threads 5 are continuous with the normal threads 3, and the threads 5 for loosening are gradually biased with respect to the normal threads 3, and at the terminal end 4b of the loosening prevention part 4, the threads 5 for loosening are gradually offset from the normal threads 3. A loosening prevention screw characterized by having a positional deviation within 1/2 pitch toward the play side.