JPS6224811Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tuft pin screw, and more specifically to a tutu pin screw that is composed of a round shaft portion and a conical portion at the tip thereof, and has a double thread thread formed on its surface.

Tatupin screws are screwed into a mating member that has not been threaded using their own tapping effect, and by sustaining the tightening force, the two members are semi-permanently joined. Therefore, tatsupin screws must have good initial bite, do not require a large force for tightening, can be screwed in quickly, have reliable holding power and are difficult to loosen, and have sufficient threads. It is required to have strength.

Tatsupin screws are usually formed with a single triangular thread, but require a large amount of force to tighten. In addition, in order to enable quick screwing, the lead angle can be increased, but as a result, a larger tightening force is required, resulting in the disadvantage that the screw is more likely to loosen. To overcome this drawback of easy loosening, double thread screws are used. A double thread screw has a more reliable holding force and is less likely to loosen than a single thread screw with the same lead angle, but requires a large force to tighten. If the screw thread is a square thread or a serrated thread, a large force is not required for tightening, but the drawback is that it tends to loosen and has poor biting.

As described above, the characteristics that a tuft pin screw should have are mutually exclusive, and in order to solve this problem, various tatu pin screws have been devised in the past. for example,
By making the round shaft part of the screw a double-thread thread and the conical part a single-thread thread, some screws have both the holding power of the double-thread part and the quick drilling ability of the single-thread part. However, when the mating material of this tuft pin screw is made of a hard material such as iron, the thread of the single threaded portion may be crushed. In order to compensate for this drawback, there is a device in which the entire body including the conical portion is made of a double-thread thread, and the first thread of the conical portion is formed lower than the second thread. However, in this case, although the threads were no longer crushed, a large amount of force was required for tightening, and this did not solve the problem. There has never been a tuft pin screw that completely solves the above-mentioned contradictory problems in this way.

The technical problem to be solved by the present invention is that the two
To provide a tuft pin screw that has good initial biting, does not require a large force for tightening, and has sufficient strength without impairing the reliable holding power and speed of screwing that a thread screw has.

The structure of the present invention is a tatsupin screw in which a double-thread thread is formed by a first thread and a second thread on the surface of a round shaft part and a conical part at the tip, and the first thread has a triangular shape over the entire length. The second thread at the tip on the conical side is lower than the first thread and has a smaller thread angle, and is a serrated thread with an acute tip. The part is characterized by a triangular thread similar to the first thread.

(Operation of the present invention) When screwing the conical portion 2 of the tatsu pin screw according to the present invention into a mating member, the second thread 8 of the tip portion 4 is
Since it is lower than the thread 7 and has a small thread angle and an acute angle at the tip, and the first thread 7 is a triangular thread, the conical portion 2 bites into the mating member sharply. Then, the conical part 2 makes a hole in the mating member,
Thereafter, the round shaft portion 1 penetrates into the hole.

Since the second thread 8 of the tip 4 of the tatsu pin screw according to the present invention is a sawtooth thread, the first thread and the second thread may both be triangular threads, or only the conical part may have a single thread thread. Perforate the mating member with a smaller force compared to the previous one. Once the hole is drilled, the round shaft 1 of the screw is easily screwed into the hole. Therefore, the force required to completely screw the tuft pin screw into the mating member is relatively small.

In addition, since the force generated on the thread surface when the conical part 2 perforates the mating member is shared between the first thread and the second thread, the force acting on each is relatively small.
This does not reach the breaking stress of the screw thread.

Furthermore, in a state where the entire tuft pin screw is screwed into the mating member, the double thread screw of the round shaft portion 1 exerts a reliable holding force.

(Specific Effects) The tatsupin screw according to the present invention has the second thread 8 of the tip 4 formed with a serrated thread having a low height and a small angle of the thread and an acute tip. It has good initial bite, does not require a large force for tightening, and has sufficient strength. Moreover, since all parts other than the tip 4 are double thread threads formed of triangular threads, the advantages of the double thread threads are not impaired.

The present invention will be specifically described below based on embodiments shown in the drawings.

Fig. 1 shows a tuft pin screw according to the present invention, in which the round shaft part 1 and the conical part 2 at the tip are all connected to the first
It is formed with a double thread thread having threads 5, 7 and second threads 6, 8. FIG. 2 shows the tip, and FIG. 3 shows the cross section of the other threads. The first threads 5 and 7 are triangular threads with a thread angle of 60° over the entire length. On the other hand, as shown in FIG. 2, the second thread 8 has a range 4 extending slightly from the tip of the conical part 2 to the round shaft part 1, and has a height that is approximately one third of the adjacent first thread 7. It is a serrated screw with a thread angle of 15° and a sharp tip. The remaining portion 6 of the second thread is a triangular thread having a thread angle of 60°, similar to the first thread 5, as shown in FIG. The tip angle of the conical portion 2 is approximately 28 degrees. In addition, the length under the neck of this invention is approximately 6 mm to 75 mm, and the nominal diameter of the round shaft portion 1 is approximately
It is desirable to apply this to M3 to M6 screws.

As mentioned above, the tuft pin screw according to the present invention has good initial bite, does not require a large force for tightening, is difficult to loosen, and has sufficient strength. Furthermore, since the second thread at the tip is a serrated thread with an acute angle and a low height, it does not damage the mating member more than necessary and does not cause burrs. Therefore, the screws will not loosen due to this.

Incidentally, the tuft pin screw according to the present invention can be easily manufactured by a method such as rolling. By changing the shape of the screw head and the material of the screw, it can be used in various fields such as architecture, light electrical appliances, and automobiles.

[Brief explanation of the drawing]

Figure 1 is a front view of the tatsu pin screw according to the present invention;
FIG. 2 is a sectional view of the thread at the tip, and FIG. 3 is a sectional view of the thread other than the tip. 1... Round shaft part, 2... Conical part, 4... Tip part,
5, 6, 7...triangular screw, 8...serrated screw.

Claims (1)

[Scope of Claim for Utility Model Registration] In a tatsupin screw in which a double-thread thread consisting of a first thread and a second thread is formed on the surface of a round shaft part and a conical part at the tip thereof, the first thread thread extends over the entire length. It has a triangular thread, and the second one at the tip on the conical side.
The thread is a serrated thread that is lower than the first thread and has a smaller thread angle and has an acute tip, and the remaining part of the second thread is a triangular thread similar to the first thread. Tatsu pin screw. The thread angle of the first thread is about 60°, the thread angle of the second thread is 15° at the tip on the conical side, and 60° at the remaining part. Tatsu pin screw as described. The tuft pin screw according to claim 1 or 2, wherein the length of the sawtooth screw of the second thread is such that it extends slightly from the tip of the conical portion to the round shaft portion.