JPS6323608Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to screws, and particularly to a screw that is optimal as a minute tuft pin screw for precision machinery.

Conventionally, the screws used in cameras, video equipment, and other precision machinery are tiny tutpin screws with a head outer diameter of about 2.5 m/m, but this type of screw has a head that engages with a tightening bit. If the groove of the section is a cross groove, it is difficult to form the corners accurately, making it difficult to tighten properly.In addition, the cross groove has a deep pyramidal hole structure in the center, so the bottom part In the longitudinal section of the screw, the screw reaches the area of the screw shaft, and therefore, the screw head is likely to be cut at the lower neck portion by the tightening torque applied at the time of tightening, resulting in the problem of so-called head skipping.

In addition, there are parts of precision equipment that users are prohibited from dismantling, and it is desirable that the screws used in these parts have a structure that cannot be removed with a normal screwdriver or the like.

In some screws, the planar shape of the screw head is oval, and an oval hole is provided on the bit side to fit the entire head, and the screw head is fitted into this hole and rotated to tighten. There is a method that attempts to solve the above problem, but according to this method, if the screwed part is inside a groove or recess, the bit will not enter the groove or recess, so the groove or recess should be made larger than necessary. The disadvantage is that it has to be made larger.

In view of this, the present invention is capable of transmitting sufficient tightening torque to tighten the head of a minute pin screw with a predetermined tightening strength. There is no tool to rotate the screw head, and it is difficult to determine what kind of tool can be used to turn the screw head at a glance. The invention was also developed for the purpose of providing a screw that can be tightened.

Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

The figure shows the case where the present invention is applied to a minute pin screw.
A tapered circular hole 3 whose diameter becomes smaller as it goes downward is formed with the axis centered at the bottom 3A.
is located in the region of the screw head 1 in longitudinal section.

Three planar inclined parts 4, 4, 4 are formed in an equiangular arrangement on the inner peripheral surface of the circular hole 3. The plane inclined portions 4, 4, 4 form the upper edge 3 of the circular hole 3.
It is formed from B to the bottom 3A, and has a substantially semi-elliptical front shape, and a portion 4A continuous to the bottom 3A is linear. Therefore, the bottom 3A
The planar shape of the above part 4A is a virtual circular bottom part 3A.
A portion 3C of the circular hole 3 connected to the bottom 3A is an arc, and these strings and arcs are arranged alternately to form a substantially hexagonal shape.

By the way, bit 5 used in the screw of this invention is
As shown in FIG. 5A and B, the tip surface 5
The shape of A matches the shape of the bottom portion 3A, and matches the substantially semi-elliptical planar inclined portions 5B, 5B, 5B which match the planar inclined portions 4, 4, 4, and the inner peripheral surface of the circular hole 3. It has a shape having tapered portions 5C, 5C, and 5C.

Therefore, the planar inclined portions 5B, 5 of the bit 5
If B and 5B are inserted into the circular hole 3 so as to match the plane inclined parts 4, 4, 4, the bit 5 is fitted into the circular hole 3 without rotation, and then by turning the bit 5, the plane inclined part 4, 4, 4 is inserted. Torque is transmitted through portions 4 and 5B, allowing tapping. In this case, as mentioned above, the plane inclined parts 4 and 5B are in close contact with each other and the rotational torque is transmitted, so there is no collapse of the grooves or slippage as in the case of cross grooves, and even with a minute screw, the rotational torque is transmitted. It can be tightened with a suitable tightening torque.

To remove the screw, if you use the bit 5 mentioned above, you can easily remove it by turning the bit 5 in the opposite direction, but you cannot turn it with other tools.

In addition, in the present invention, it is most appropriate to provide the planar inclined portion 4 on three sides as in the illustrated embodiment, but the number is not necessarily three, and depending on the size of the screw and the relationship between the tightening torques, there may be two or four sides. It is also possible to do this.

As explained above, the present invention is designed to provide a circular hole that is formed at the top of the screw head, and that is formed on the inner circumferential surface of the circular hole that is centered on the axis of the screw shaft and whose diameter becomes smaller as it goes downward. A plurality of straight plane inclined parts are formed in an equiangular arrangement, and the part connected to the bottom of the circular hole becomes the chord of the circular bottom, so that the plane inclined part of the bit comes into close contact with the flat inclined part when tightening the screw. Since the tightening torque is transmitted using the conventional cross grooves, there is no tightening failure due to collapse of the corners, which is the case with conventional cross grooves, and the tightening can be done with sufficient strength. Since the torque is transmitted through the circular hole, there is no need to make the circular hole very deep, and therefore head jump can be prevented even if sufficient torque is transmitted.

In particular, according to the present invention, since the planar inclined portion is formed on the inner circumferential surface of the circular hole, it is not clear at first glance what kind of tool should be used for small screws, and as a result, This prevents the screw from being removed unnecessarily, making it extremely effective as a screw for use in dangerous locations where disassembly would be a problem.

Furthermore, there are various excellent effects such as the fact that there are no restrictions on where the screw can be used and it can be used in the same way as a normal screw, unlike those in which the head of the screw is shaped differently and the screw is tightened around its outer periphery.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of the screw according to the present invention, Fig. 2 is an enlarged plan view of the screw head, Fig. 3 is a longitudinal sectional view of the same, Fig. 4 is a perspective view of the same, and Fig. 5 Figure A,
B is a partial side view and an end view showing an example of the same tightening bit. 1...screw head, 2...screw shaft, 3...circular hole, 3
A...Bottom, 3B...Top edge, 4...Plane slope, 5...
Bit.

Claims (1)

[Scope of utility model registration request] A hole is formed on the inner circumferential surface of a circular hole 3 that is formed at the top of the screw head 1 and becomes smaller in diameter as it goes downwards around the axis of the screw shaft 2, from the upper edge 3B of the circular hole 3 to the bottom 3A. A screw characterized in that a plurality of straight planar inclined portions 4 are formed in an equiangular arrangement so that a portion 4A connected to a bottom portion 3A of a circular hole 3 forms a chord of the circular bottom portion.