JPS6131206Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tuft pin screw designed to prevent loosening.

Conventionally, when a tut pin screw is tightened into a pilot hole made in a viscoelastic material such as a thermoplastic resin, the tut pin screw recovers elastically over time after tightening, and the tightening force decreases, making it easier for the tut pin screw to come out. , they often fell off easily due to vibration or impact.

Such a decrease in the tightening force over time, which occurs when tightening a tuft pin screw into a viscoelastic material, cannot be prevented.

The purpose of the present invention is to provide a tuft pin screw that utilizes the elastic restorability of the thermoplastic resin and the like described above to produce a retaining effect even if the tightening force is lost, and that will not fall off due to vibration or impact.

Furthermore, another object of the present invention is to provide a tuft pin screw that exhibits an effect of preventing loosening not only when fastened to viscoelastic materials but also when fastened to die casting and the like.

Hereinafter, the present invention will be explained with reference to drawings which are embodiments.

FIG. 1 shows the first tuft pin screw 10 according to the present invention.
An embodiment is shown in which a drive tool engaging means is provided at one end of the main rod portion 11, in this example, as shown in FIG.
A head 13 is provided with an introduction part 14 at the other end,
Continuous two-thread threads 15 and 16 are formed across the main rod portion 11 and the introduction portion 14, and the common root diameter of these two-thread threads 15 and 16 is substantially at least on the main rod portion 11. The outer diameter of the thread on the main rod portion 11 is constant, and the first thread 15 tapers to a positive angle α, and the second thread 16 tapers to a negative angle β. In other words, the outer diameter of the first screw thread 15 increases as it approaches the head 13, and the outer diameter of the second thread 16 decreases as it approaches the head 13. , and the lines connecting these outer diameters intersect at an intermediate position 18 of the main rod portion 11.

Furthermore, in the introduction part 14, the double thread thread 1
Both numbers 5 and 16 change at a negative angle of inclination toward the tip of the screw.

Since the tuft pin screw 10 according to the present invention is constructed as described above, as shown in FIG. Pilot hole 2 provided in
When the tuft pin screw 10 is screwed into the hole 21, first, as shown in FIG. 4, a female thread is formed at the entrance of the pilot hole 21 at the introduction part 14, similar to the conventional tuft pin screw.

Further, as the screw continues to be screwed in, as the joint 17 advances into the pilot hole 21 as shown in FIG. Then, on the other hand, the outer diameter of the thread 15 increases toward the head 13, so that a gap 22 is created between the thread 16 and the previously formed female thread. On the other hand, the thread 15 removes the material of the mating member 20 in order to continue forming the internal thread deeply, and this removed material moves to fill the gap 22.
Furthermore, the viscoelastic material acts to fill this gap 22 due to its characteristic elastic restoration over time (see FIG. 6). Therefore, depending on the material of the mating member 20, the diameter of the pilot hole 21, the length of the threaded portion fitting with the tuft pin screw 10, the pitch P of the thread of the tatu pin screw 10, the thread angle θ, and the main rod portion 11. The specifications such as the root diameter on the upper part, the taper angle α of the first thread 15 on the main rod part 11 and the taper angle β of the second thread 16 on the main rod part 11, and the intermediate position 18 which is the intersection of the outer diameter lines are set as appropriate. By selecting, almost completely gap 2
You can fill in 2.

Generally, Tatsupin screws are prevented from rotating by the frictional force generated by the tightening force, so if this tightening force is lost for some reason, the frictional force also disappears and the screw becomes free, causing vibrations and shocks. It can easily rotate and fall off.

However, the tuft pin screw 10 according to the present invention
is fitted to the mating member 20 with almost no gap 22 as described above. Therefore, even if the tightening force of the mating member 20 is lost, since the tatu pin screw has an hourglass shape, in order for it to loosen, the female thread formed on the mating member 20 must be reworked. It must be passed through the threads 16 with a thick tip, and the tut pin screw cannot rotate naturally due to vibration or impact and cannot fall off.

Since the tatsu pin screw according to the present invention has the above-mentioned effects, it is particularly suitable for mating members such as thermoplastic resins that have elastic recovery properties and easily lose their tightening force, but are suitable for mating members such as die-cast materials. Even if the material does not have elastic recovery, if the above specifications are appropriately selected and the movement of the material during screwing is utilized,
Since similar effects can be obtained, it can be applied to usage conditions where vibrations and shocks are severe.

The flat-tipped tatsupin screw has been described above as an embodiment of the present invention, but as shown in Fig. 7,
The same applies to the tuft pin screw 10a whose introduction part has a pointed tip.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a front view of the tuft pin screw according to the invention, Fig. 2 is a side view, Fig. 3 is a partially cutaway front view showing its usage mode, and Fig. 4. is a partially enlarged view showing the fitted state of the screw at the initial stage of screwing, Fig. 5 is a partially enlarged view showing the fitted state of the screw during screwing, and Fig. 6 is a partially enlarged view showing the fitted state of the screw after screwing is completed. 7 are front views showing other embodiments of the tuft pin screw according to the present invention. 10, 10a...Tatsu pin screw, 11...Main rod part, 14...Introduction part, 15, 16...Double thread thread, 18...Intermediate position (crossing part), 20...Mating member, 21... Pilot hole, 30... Member to be tightened.

Claims (1)

[Claims for Utility Model Registration] (1) A head equipped with a driving tool engaging means is provided at one end of the main rod, an introduction section is provided at the other end, and two A thread is formed, and the root diameter of the two-start thread on the main rod portion is substantially constant, and the outer diameter of the thread on the main rod portion increases from the introduction portion toward the head side. A tatsu pin characterized in that the thread tapers at a positive angle, the second thread tapers at a negative angle, and a line connecting the outlines of both threads intersects in the middle of the main rod part. screw. (2) The tatsupin screw according to claim 1 of the utility model registration claim, wherein the outer diameter of the double thread screw provided in the introduction portion gradually decreases toward the tip. . (3) Claim 1 of the above-mentioned utility model registration, characterized in that the introduction part has a pointed shape.
Tatsu pin screws as described in section.