JPH0220492Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention has a protrusion that bites into the seat surface on the back of the screw head, and is suitable for use for grounding in electrical equipment, etc. Regarding screws.

[Conventional technology]

7 to 11 show an example of a conventional screw of this type. In these figures, 1 is the entire screw, 2 is the screw head, and 3 is the shaft portion.Four convex portions 4 are integrally provided on the back surface 2a of the screw head 2. Each of these convex portions 4 has a screw 1 all over it.
It has an arcuate shape centered on the axis of , and its cross section has a roughly isosceles triangular shape as shown in FIG.

FIG. 10 shows an example of the use of this screw 1, where 5 is a chassis, 6 is an insulating plate such as a Bakelite plate, 7 is a thin conductive layer made of copper or the like provided on the surface of the insulating plate 6, and 8 is a conductive layer 7. It is a varnish layer applied to the surface of. Then, when the shaft portion 3 of the screw 1 is screwed into the screw hole provided in the chassis 5 and the screw 1 is tightened, the convex portion 4 breaks the varnish layer 8 and bites into the conductor layer 7, and the convex portion 4 breaks through the varnish layer 8 and bites into the conductor layer 7. The conductor layer 7 and the chassis 5 are electrically connected and grounded.

[Problem that the invention attempts to solve]

However, in this conventional screw 1, (a) When the convex part 4 first contacts the conductor layer 7, the length of the contact part between the convex part 4 and the conductor layer 7 is short as shown in FIG. In addition, the front end 4a of the convex portion 4 becomes longer.
(In FIG. 11, arrow A indicates the direction of movement of the convex portion 4 with respect to the conductor layer 7.)
Since it is perpendicular to the conductor layer 7, a very large resistance force acts on the protrusion 4 and thus on the screw 1 at the initial stage when the protrusion 4 tries to bite into the conductor layer 7. Therefore, with low torque, the convex portion 4 cannot be deeply dug into the conductor layer 7, and a good conduction state between the screw 1 and the conductor layer 7 cannot be achieved, making it impossible to obtain a good grounding. I can't.

(b) Since the convex portion 4 has an arc shape centered on the axis of the screw 1, when the screw 1 is about to be rotated in the direction of loosening, the convex portion 4 will not touch the conductor layer 7. Since the convex portion 4 moves backward in the circumferential direction of the circular arc formed, the resistance force that the convex portion 4 receives from the conductor layer 7 at this time is small. Therefore, the screw 1 tends to loosen.

There were other drawbacks.

[Purpose of invention]

The present invention was made in order to solve the above-mentioned conventional problems, and the convex part provided on the back side of the screw head
With low torque, it bites deeply and widely into the part to be mounted such as a conductor layer, increases the contact area between the convex part and the part to be mounted at the biting part, and also tightly adheres the convex part and the part to be mounted. It is an object of the present invention to provide a screw which can achieve extremely good electrical conduction between the screw and a part to be attached, and which is less likely to come loose.

[Means for solving problems]

The screw according to the present invention has a convex portion integrally provided on the back surface of the screw head, and the convex portion has a generally triangular cross section, and the top side of the convex portion is when viewed from the axial direction of the screw. It is formed in a straight line perpendicular to the radial direction of the screw, and in an arc shape when viewed from directly beside the convex portion.

[Effect]

In the screw according to the present invention, since the convex part has the shape described above, when the convex part first contacts the seat surface of the attached part, the convex part and the seat surface are at the apex of the convex part, Since contact is made only at one point, at the initial stage when the protrusion cuts into the seat surface, the protrusion cuts into the seat surface, so the resistance that the protrusion receives is extremely small, and low torque is applied. The convex part can be deeply and widely dug into the seat surface.

In addition, when the screw is rotated, the protrusion does not move in the same direction as the top of the protrusion relative to the seat surface, but in a diagonal direction with respect to the top, so the protrusion moves against the seat surface. As it digs deeper, the convex portion does not simply cut the seat surface cleanly, but instead deforms the seat surface plastically as it digs further into the seat surface. The plastically deformed portion of the seat surface due to this swells from the seat surface toward the back surface of the head of the screw.

Therefore, the contact area between the convex portion and the seat surface can be increased, the convex portion and the seat surface can be brought into close contact with each other, and the state of electrical conduction between the screw and the seat surface can be improved.

Furthermore, when the screw is about to be rotated in the direction of loosening, the convex portion moves backward in a direction diagonal to the top side of the convex portion with respect to the seat surface. The resistance force received from the seat surface becomes extremely large. Further, since the plastically deformed portion of the seat surface is in a state where it is entangled with the convex portion, this plastically deformed portion also exerts a resistance force against the backward movement of the convex portion. Therefore, loosening of the screw is extremely unlikely to occur.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings.

1 to 6 show an embodiment of the present invention. In this example, 9 is the entire screw, 10
Reference numeral 11 indicates a screw head, and 11 indicates a shaft portion. Three protrusions 12 are integrally provided on the back surface 10a of the screw head 10 at intervals of 120 degrees. Each of these convex portions 12 has a roughly triangular cross section as shown in FIG. When viewed from the side of the convex portion 12 (that is, when viewed from the direction of arrow B in FIG. 1), it has an arcuate shape as shown in FIG. 2.

Note that the slope 12b on the inside of the convex portion 12 has a gentler slope than the slope 12c on the outside of the convex portion 12.

FIG. 4 shows an example of the use of this screw 9, in which 13 is a chassis, 14 is an insulating plate such as a Bakelite plate, 15
16 is a thin conductor layer made of copper or the like provided on the surface of the insulating plate 14, and 16 is a varnish layer coated on the surface of the conductor layer 15. Then, when the shaft portion 11 of the screw 9 is screwed into the screw hole provided in the chassis 13 and the screw 9 is tightened, the convex portion 12 breaks the varnish layer 16 and bites into the conductor layer 15, and the screw 9 is inserted into the conductor layer 15. The conductor layer 15 and chassis 13 are electrically connected and grounded.

Here, in this screw 9, since the convex part 12 has the above-described shape, the convex part 12 is similar to the conductor layer 1.
When contacting the conductor layer 1 for the first time, the convex portion 12 and the conductor layer 1
5 contacts only at one point, which is the apex 12d of the convex portion 12. Therefore, at the initial stage when the convex portion 12 bites into the conductor layer 15, the convex portion 12 cuts into the conductor layer 15 as if cutting the conductor layer 15. Therefore, the resistance that the convex part 12 receives is extremely small, and the convex part 12 can be deeply and widely penetrated into the conductor layer 15 with low torque (in FIG. 5, the arrow C indicates the conductor layer 7 of the convex part 12). direction of movement).

Furthermore, when the screw 9 is rotated, the convex portion 12 does not move in the same direction as the top side 12a of the convex portion 12 with respect to the conductor layer 15, but in a diagonal direction with respect to the top side 12a. , the convex portion 12 is the conductor layer 15
As it digs deeper into the conductor layer 15, the protrusion 12 does not simply cut the conductor layer 15 cleanly, but creates a scratch 17 in the conductor layer 15 in the shape shown in FIG. 6 when viewed from the axial direction of the screw 9. While attaching (in addition,
In FIG. 6, arrow D indicates the tightening rotation direction of the screw 9), while plastically deforming the conductor layer 15,
Further, it begins to dig into the conductor layer 15.
The plastically deformed portion of the conductor layer 15 due to this is
From the surface (seat surface) of the conductor layer 15 to the back surface 1 of the head 10
It gets more exciting towards 0a.

Therefore, the contact area between the convex portion 12 and the conductor layer 15 is increased, and the convex portion 12 and the conductor layer 15 are brought into close contact with each other, so that the conductive state between the screw 9 and the conductor layer 15 is improved. can do.

Furthermore, when the screw 9 is about to be rotated in the loosening direction, the protrusion 12 moves backward relative to the conductor layer 15 in a diagonal direction with respect to the direction of the top side 12a of the protrusion 12. At this time, the convex portion 12
The resistance force received from 5 becomes extremely large. Moreover, since the plastically deformed portion of the conductor layer 15 is in a state where it is entangled with the convex portion 12, this plastically deformed portion also exerts a resistance force against the backward movement of the convex portion 12. Therefore, loosening of the screw 9 is extremely unlikely to occur.

Note that even if the seat surface of the conductor layer 15 is depressed, in order for the screw 9 to rotate in the loosening direction, the convex portion 12 must be formed in the recess formed in the conductor layer 15 by the seat surface depression (this recess is The convex portion 12 has to dig deeper into the conductor layer 15 (formed on the conductor layer 15) in a diagonal direction with respect to the top side 12a, and at this time a very large resistance force acts. Therefore, loosening of the screw 9 is very unlikely to occur.

By the way, suppose that in the conventional screw 1 shown in FIGS. 7 to 11, the shape of the convex portion 4 is as shown in (a).
While leaving the cross section approximately triangular in shape and (b) the circular arc shape centered on the axis when viewed from the axial direction of the screw 1, as in the case of the present invention, the convex portion 4 If the top side of the convex part 4 forms an arc shape when viewed from the side, the convex part 4 will cut the conductor layer 7 consistently from the beginning to the end when the screw 1 is tightened. Then, it bites into the conductor layer 7. Therefore, the resistance force that the convex portion 4 receives from the conductor layer 7 is relatively small until the end. However, unlike in the case of the screw of the present invention, it is not possible to cause large plastic deformation in the conductor layer, and therefore the excellent effects of the present invention described above cannot be obtained.

In the embodiment described above, three convex portions 12 are provided, but in the present invention, the number of convex portions may be less than or greater than this.

In addition, in the above embodiment, an example was shown in which the screw according to the present invention was used for grounding, but as described above, the screw according to the present invention has a low torque and the convex portion is attached to the bearing surface of the conductor layer etc. It bites deeply and widely,
The contact area between the convex part and the seat surface is increased at the biting part, and the convex part and the seat surface can be brought into close contact with each other. It can also be used for this purpose.

[Effect of idea]

As described above, the screw according to the present invention allows the convex portion provided on the back surface of the screw head to bite deeply and widely into the bearing surface of the conductor layer etc. with low torque, and at the biting portion, the convex portion and the bearing surface. The contact area is large, and the convex part and the seat surface are brought into close contact, making it possible to achieve extremely good electrical conduction between the screw and the seat surface, and to have the excellent effect of being less likely to loosen. It is something that can be done.

[Brief explanation of the drawing]

Fig. 1 is a bottom view showing an embodiment of the screw according to the present invention, and Fig. 2 is a view taken in the direction of arrow B in Fig. 1 (however,
3 is a sectional view taken along the - line in FIG. 1, FIG. 4 is a sectional view showing an example of use of the embodiment, and FIG. 5 is a convex portion of the embodiment. 6 is a cross-sectional view showing the initial stage of penetration of the conductor layer into the conductor layer.
7 is a bottom view showing an example of a conventional screw, and FIG. 8 is a view taken in the direction of arrow E in FIG. 7 (however, the shaft portion is not shown). ), FIG. 9 is a sectional view taken along the - line in FIG. 7, FIG. 10 is a sectional view showing an example of the use of the conventional screw, and FIG. FIG. 3 is a cross-sectional view showing the initial stage of digging into the layer. 9... Screw, 10... Screw head, 10a... Back side of screw head, 12... Convex portion, 12a... Top side.

Claims (1)

[Scope of utility model registration request] In a screw having a convex portion integrally provided on the back surface of the screw head, the convex portion has a generally triangular cross section,
A screw characterized in that the top side of the convex portion is formed in a straight line perpendicular to the radial direction of the screw when viewed from the axial direction of the screw, and in an arc shape when viewed from directly beside the convex portion. .