JPH0613373Y2 - Spring washer for flat head screw - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention, in the case of fastening an object to be fastened with flat head screws, of the outer surface of the flat head of the flat head screw and the counterbore hole in the fastened object. The present invention relates to an improvement of a spring washer which is inserted between the inner surface and the inner surface as a loosening prevention member for the countersunk screw.

[Conventional technology]

Conventionally, this type of spring washer 1 has been disclosed in, for example, Jpn.
As described in Japanese Patent No. 5168, etc., and as shown in FIGS. 9, 10, and 11, an elastic metal plate having an appropriate thickness t is formed into a conical shape, and the inner diameter hole 2 has an inner diameter d of Make a perfect circle,
The cone angle from the axis 3 is the cone angle θ from the axis 3 in the plate-shaped head 13 of the flat head screw 12 (or the fastened object 14) at the plurality of first locations 4, 5, 6, 7 on the circumference. Angle θ1 which is larger than the conical angle from the axial line 3 in the counterbore 15) and at the plurality of second points 8, 9, 10, 11 in the middle of the first points 4, 5, 6, 7.
The angle θ2 is smaller than the conical angle θ from the axis 3 of the countersunk head 13 of the flat head screw 12 (or the conical angle from the axis 3 of the counterbore 15 of the object to be fastened 14),
By forming a wavy shape along the circumferential direction as a whole,
It was configured to give elasticity.

[Problems to be solved by the device]

In the conventional spring washer described above, the inner diameter hole 2 is a perfect circle,
The base point of the cone angle θ1 from the axis 3 at each of the first locations 4, 5, 6, 7 and the cone angle θ2 from the axis 3 at each of the second locations 8, 9, 10, 11 is the inner diameter hole of the true circle. Two
The cross-sectional shape of the spring washer 1 has the above-mentioned first positions 4, 5, 5 in the circumferential direction.
The flat plate is formed at any of the positions 6, 7 and the second positions 8, 9, 10, 11. Therefore, in this conventional spring washer, the spring force for tightening the countersunk screw 12 depends only on the reaction force when the corrugated shape along the circumferential direction is extended, so that the spring force is the circumferential direction. Along the wavy shape, that is, each of the first locations 4, 5, 6,
7, the cone angle θ1 from the axis 3 and each second location 8,
It is proportional to the difference from the cone angle θ2 from the axis 3 at 9, 10, and 11.

Therefore, in order to increase the spring force in order to improve the loosening prevention effect on the flat head screw 12, the above-mentioned first locations 4, 5,
The conical angle θ1 from the axis 3 at 6 and 7 and the conical angle θ2 from the axis 3 at each of the second locations 8, 9, 10, and 11.
It is necessary to increase the difference in height of the corrugations along the circumferential direction or increase the plate thickness t by increasing the difference between and.

However, if the height difference of the corrugated shape along the circumferential direction is increased as in the former case, the flexure dimension in the direction of the axis 3 becomes large when tightening the flat head screw 12, and the flat head screw 12 causes the spring force of the spring washer 1 to be increased. Since the amount of rotation at the time of screwing in against the screw increases, it takes time for screwing the flat head screw 12 so that the workability of screwing is reduced, and moreover, the large deflection size in the direction of the axis 3 , Sag is likely to occur, and the reduction of the restoration rate (the value obtained by dividing the size of the flathead screw when it is loosened is divided by the above-mentioned flexure dimension) is greatly reduced. This means that the durability is significantly reduced, in other words, the durability when used repeatedly is low.

In addition, when the plate thickness t is increased like the latter, there is no problem as in the former, but the manufacturing cost is increased, and the depth of the counterbore 15 in the object to be fastened 14 is increased. The plate thickness must be increased by the increased amount.

The present invention aims to solve these problems.

[Means for Solving the Problems]

In order to achieve this object, the present invention provides a spring washer formed in a conical shape with an elastic metal plate having an appropriate thickness, and a conical portion on the inner peripheral side with a boundary line between the inner peripheral and the outer peripheral as a boundary. And a conical portion on the outer peripheral side, and the conical angle from the axis of the inner conical portion is formed to be equal to or substantially equal to the conical angle from the axis of the countersunk head of the countersunk screw, while the outer periphery is formed. The cone angle from the axis in the side cone is set to be larger than the cone angle from the axis in the dish head of the flat head screw at a plurality of first locations on the circumference, and in the middle of the first location. The plurality of second locations are formed at angles smaller than the conical angle from the axis of the countersunk head of the countersunk screw.

[Action]

According to this structure, of the inner peripheral side conical portion and the outer peripheral side conical portion, only the outer peripheral side conical portion can be formed in a wavy shape along the circumferential direction, while the axial line in the inner peripheral side conical portion can be formed. Due to the difference between the cone angle from the and the cone angle from the axis of the outer peripheral side cone portion, the shape of the cross section of the spring washer is bent in a V shape at each of the first position and the second position in the circumferential direction. Take the form.

As a result, the spring force for tightening the flat head screw adds the reaction force when the V-shaped cross section is extended to the reaction force when the corrugated shape along the circumferential direction is extended, Moreover, since the corrugations along the circumferential direction are formed only on the outer peripheral side cone portion, the reaction force when the corrugations along the circumferential direction are extended is also the corrugations along the circumferential direction. Since it is larger than the case where it is formed over the inner cone on the inside as in the past, a large spring force can be obtained without increasing the plate thickness or increasing the corrugated height difference along the circumferential direction. Can be obtained.

[Effect of device]

Thus, according to the present invention, without increasing the plate thickness or increasing the height difference of the corrugations along the circumferential direction,
Since a large spring force can be obtained, it is possible to avoid the cost increase due to thickening the plate thickness and the deepening of the counterbore hole in the object to be fastened, while making it possible to reduce the axial deflection size and flat head screw. It is possible to achieve improvement in workability when screwing in, improvement in restoration rate, and further improvement in durability when repeatedly used.

Moreover, there is an effect that the spring force can be easily increased / decreased and adjusted by the ratio of the width dimension of the inner peripheral side conical portion and the width dimension of the outer peripheral side conical portion.

〔Example〕

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described with reference to the drawings (FIGS. 1 to 5). In the drawings, reference numeral 1 denotes a spring washer formed in a conical shape by an elastic metal plate having an appropriate thickness t. The washer 1 has an inner peripheral side conical portion 1 adjacent to the inner diameter hole 2 of the inner diameter d with a boundary line 1a located between the outer circumference and the inner circumference as a boundary.
b and the outer peripheral side cone portion 1c.

Then, the cone angle θ _o from the axis 3 in the inner peripheral side cone portion 1 b is made equal to or substantially equal to the cone angle θ (for example, 90 degrees) from the axis 3 in the countersunk head 13 of the flat head screw 12. Form.

On the other hand, the cone angle from the axis 3 in the outer peripheral side cone portion 1c is set to a plurality of (for example, four locations) first circles on the circumference.
At points 4, 5, 6, and 7, the angle θ1 is larger than the circumferential angle θ from the axis 3 of the countersunk head 13 of the countersunk screw 12 by an appropriate angle (for example, about 3.5 degrees), and At a plurality of second locations 8, 9, 10, 11 in the middle of each of the first locations 4, 5, 6, 7, an angle that is more appropriate than the cone angle θ from the axis 3 in the dish head 13 of the countersunk screw 12 described above. By making the angle θ2 smaller (for example, about 3.5 degrees), only the outer peripheral side cone portion 1c is formed in a corrugated shape along the circumferential direction.

According to this structure, the spring force for tightening the flat head screw is added with the reaction force when the corrugated cross section is extended and the reaction force when the corrugated shape along the circumferential direction is extended. Moreover, since the corrugations along the circumferential direction are formed only on the outer peripheral side cone portion, the reaction force when the corrugations along the circumferential direction are extended is also the corrugations along the circumferential direction. Since the mold becomes larger than the case where the mold is formed over the inner peripheral side conical portion as in the conventional case, the plate thickness is increased, or even if the height difference of the corrugated shape along the circumferential direction is not increased, A large spring force can be obtained.

The inventor conducted a comparative test between the conventional spring washer having an inner diameter of 8 mm and the spring washer having an inner diameter of 8 mm according to the present invention, and the spring washer according to the present invention was bent in the axial direction with respect to the same tightening torque. The dimensions are shown in Figs.
It can be reduced to about 0.6 as compared with the conventional one shown in the figure, and the restoration rate can be increased to about 1.5 times as much as that of the conventional one shown in FIGS. The ratio of the width dimension 1 from the inner surface to the boundary line 1a and the width dimension 2 from the outer peripheral surface to the boundary line 1a is appropriately 1: 2 to 1: 5,
By setting this ratio, the spring force could be increased or decreased.

In addition, in the above-mentioned embodiment, the case of forming four corrugations in the circumferential direction is not limited to the above four corrugations, but may be three corrugations as shown in FIGS. 6 and 7. It is also possible to make a plurality of them, etc. Further, if the embossed portion 16 is integrally formed on the inner peripheral edge of the inner diameter hole 2 as shown in FIG.

[Brief description of drawings]

1 to 8 show an embodiment of the present invention, and FIG.
A plan view of a spring washer of the embodiment, FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is a sectional view taken along line III-III of FIG. 1, and FIG. , FIG. 5 is an enlarged view of a main part of FIG. 3, and FIG.
The drawing is a plan view of the spring washer of the second embodiment, and FIG. 7 is the VI of FIG.
FIG. 8 is a sectional view of a spring washer of the third embodiment, FIG. 9 is a plan view of a conventional spring washer, and FIG.
FIG. 11 is a sectional view taken along line XX in FIG. 11, and FIG. 11 is a sectional view taken along line XI-XI in FIG. 1 ... Spring washer, 1a ... Boundary line, 1b ... Inner peripheral cone part, 1c ... Outer peripheral cone part, 2 ... Inner diameter hole, 3 ... Axis line, 4, 5, 6, 7 ... One place, 8, 9, 10, 11
...... 2nd place, 12 ...... Disc screw, 13 ...... Disc head, 1
4 ... Object to be fastened, 15 ... Counterbore hole, 16 ... Embossed portion 16, θ ... Cone angle from axis in dish head,
θ _o …… The cone angle from the axis in the inner cone, θ
1 …… Conical angle from the axis at the first location, θ2 ……
The cone angle from the axis at the second location.

Claims (1)

[Scope of utility model registration request] 1. A spring washer formed in a conical shape by an elastic metal plate having an appropriate thickness has a cone portion on the inner peripheral side and a cone on the outer peripheral side with a boundary line between the inner periphery and the outer periphery as a boundary. And a cone angle from the axis of the inner peripheral cone portion to an angle equal to or substantially equal to the cone angle from the axis of the countersunk head of the flat head screw, while the axis of the outer peripheral cone portion is formed. From the axis of the flat head of the flat head screw to a cone angle from the axis of the flat head of the flat head screw at a plurality of first locations, and at a plurality of second locations in the middle of the first location. Then, a spring washer for a countersunk screw, which is formed at an angle smaller than a conical angle from the axis of the countersunk head of the countersunk screw.