JPH024247Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention relates to a nut that has excellent locking performance.

(Prior Art) As shown in FIG. 5, a standard nut 11 has a thread 12 and a root 13 that are symmetrical on both sides of center lines φ ₁ and φ ₂ . Therefore, even if we compare the tightening process in which the nut 11 is moved in the direction of the arrow S relative to the bolt 14 as shown in FIG. 6A, and the tightening process in which the nut 11 is moved in the direction of the arrow t as shown in FIG. 6B, , the gap l ₁ between the valley bottom 13 of the nut 11 and the peak 15 of the bolt 14 is equal, and the advancing flank 16a,
Since there is no difference in the contact state between the trailing flanks 17a and the trailing flanks 16b and 17b, the tightening torque and the return torque have the same value. Therefore, such a nut has the disadvantage that it is easily loosened due to vibration or the like after being tightened.

Therefore, as a means to prevent the above-mentioned loosening, conventional methods have generally been used, such as deforming a part of the screw by hammering it after tightening, or interposing a synthetic resin or the like at the interface with the bolt. On the other hand, various locking nuts have been proposed in which the internal thread shape is devised to suppress loosening after tightening.

(Problems to be solved by the invention) However, with the above-mentioned method of hitting the nut after tightening, it becomes impossible to return the nut.
Nuts and bolts often become unusable due to screw deformation. Furthermore, when using an inclusion such as a synthetic resin, an extremely strong force is required during tightening, and the cost is also high. Furthermore, while most of the conventional locking nuts have a large return torque, they also have a large tightening torque, and still require strong force for tightening.

This invention was made to solve these conventional problems, and the purpose is to provide a nut with ideal performance as a locking nut, which has a large return torque and a small tightening torque. .

(Means for solving the problem) For the above purpose, the nut related to this invention:
The angle between the trailing flank of the screw thread and a surface orthogonal to the axis is smaller than the angle between the leading flank and the above-mentioned surface, and the root of the thread is configured with a tapered surface that is low on the leading flank side and high on the trailing flank side. It is something.

(Example) This invention will be explained below based on the illustrated example.

FIG. 1 shows a nut 1 which is an embodiment of this invention. The female thread 2 of this nut 1 has a structure in which the thread 3 is entirely inclined toward the return direction, as shown in FIG. That is, the leading flank 4a of the thread 3 has an inclination angle θ ₁ with respect to the plane P perpendicular to the axis O.
(for example, 35 degrees), but the trailing flank 4b has an inclination angle θ ₂ (for example, a tapered surface, that is, _{θ 1 >} θ ₂ ) that is smaller than the above-mentioned inclination angle θ 1 with respect to the plane P. The valley bottom 5 has an inclination angle φ ₁ that is lower toward the advancing flank 4a side and higher toward the trailing flank 4b side (for example,
It consists of a tapered surface of 10°). Further, the crest 6 of the thread 3 is formed of a tapered surface having an inclination angle φ ₂ (for example, 10°) that is high on the leading flank 4a side and low on the trailing flank 4b side.

In the case of such a nut 1, as shown in FIG. 3, the flanks 9a and 9b on both sides of the thread 8 are tilted in the direction of the arrow S, compared to a standard nut 7 in which both flanks 9a and 9b have an equal inclination angle α (for example, 30 degrees). When tightened, the crest 8a of the thread 8 of the bolt 7 is positioned opposite to the lower side of the tapered surface of the root 5 of the nut 1, that is, the advancing flank 4a side, and a gap _l2 is created between the crest 8a and the root 5. It is formed. Then, the flat surface of the leading flank 4a of the nut 1 comes into contact with the convex curved surface near the peak 8a of the leading flank 9a of the bolt 1. Therefore, the nut 1 can be tightened with sufficient margin relative to the bolt 7 and with little sliding resistance.

On the other hand, if the nut 1 is rotated in the opposite direction and the nut 1 is returned in the direction of the arrow t relative to the bolt 7 as shown in FIG.
slides into contact with the higher side of the tapered surface of the root 5 of the nut 1, that is, the side of the trailing flank 4b, resulting in a state where there is no room between the nut 1 and the bolt 7, and the trailing flank 4b of the peak 6 of the nut 1.
The side corner 6a is pressed into contact with the trailing flank 9b of the bolt 7 so as to bite strongly into the edge shape. Therefore, the returning operation of the nut 1 requires a significantly larger torque than the tightening operation, and as a result, the nut 1 has a strong resistance to loosening after tightening.

In addition, in the above, when the nut 1 is returned, the nut 1
The case where the root of the nut 1 contacts the peak 8a of the bolt 7 is shown, but even in a non-contact state, the gap becomes smaller than the gap during the tightening operation, corresponding to the inclination angle φ ₁ of the root of the nut 1. Since the margin between the bolt 7 and the bolt 7 is reduced, the return torque becomes larger than the tightening torque.

Further, in the above embodiment, the inclination angle θ ₂ of the leading flank 4a of the nut 1 is larger than the inclination angle α of the flanks 9a and 9b on both sides of the bolt 7, but both inclination angles θ ₂ and α may be equal angles. . In other words, in this invention, the relationship between each inclination angle is θ ₁ ≧α≧θ ₂
That's fine. On the other hand, thread 3 in nut 1
The peak 6 of the mountain does not need to be sloped.

(Effects unique to the invention) In the nut according to this invention, the top of the thread of the bolt is located on the lower side of the root of the thread during tightening operation, and there is room for the bolt, and during the return operation, the top of the thread of the bolt is located on the side with the higher root of the root. The above-mentioned peak is located at the top of the bolt, leaving no room for the bolt, and the corner of the top of the thread of the nut presses into the trailing flank of the thread of the bolt in an edge-like manner, so the tightening torque must be reduced. It has the revolutionary feature of being small and having a significantly large return torque. Therefore, this nut can be easily tightened and exhibits an excellent locking effect, making it ideal as a locking nut. Also, nuts like this,
Nuts and taps with corresponding cutting edge shapes allow the same shape to be produced in large quantities, so they can be manufactured at low cost despite their unique shape.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a nut according to an embodiment of the invention, Fig. 2 is a partial longitudinal sectional view of the female threaded portion of the nut, and Fig. 3 is a threaded connection between the nut and bolt during tightening operation. Vertical cross-sectional view of main parts showing the relationship, No. 4
The figure is a longitudinal cross-sectional view of the main part showing the same screwing relationship during the return operation, Fig. 5 is a longitudinal cross-sectional view of the main part of the female thread part of a conventional standard nut, and Fig. 6 A and B are the same as Fig. 4. FIG. 3 is a vertical cross-sectional view of a main part showing the screwing relationship between a nut and a bolt. 1...Nut, 2...Female thread, 3...Screw thread,
4a...Advance flank, 4b...Chasing flank,
5...Trough bottom, θ ₁ ...Inclination angle of leading flank, θ ₂ ...
...Inclination angle of trailing flank, O...axis, P...plane perpendicular to the axis.

Claims (1)

[Scope of utility model registration request] The angle between the trailing flank of the screw thread and a surface orthogonal to the axis is smaller than the angle between the leading flank and the above-mentioned surface, and the root of the thread is configured with a tapered surface that is low on the leading flank side and high on the trailing flank side. Natsuto.