JPH11117929A - Male screw and screwing structure between male screw and female screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a male screw capable of certainly preventing looseness and small in tightening torque. SOLUTION: Crest width H of a male screw 11 is made the same as root width (h) on a screwing part of a female screw 15, a flank angle (c) in the front in the fastening direction of the male screw is made smaller than a flank angle (d) of the female screw 15 facing against it, a flank angle in the rear is made different on the crest side (a) and the bottom side (b), a contact surface is made by making the angle (a) on the crest side smaller than the angle (d) of the female screw by 1-2 deg., and the flank angle (b) on the root side is made smaller than the flank angle (d) of the female screw. Consequently, female and male ridges make contact with each other only on crest parts of the ridges, and as resistance torque to looseness is generated at a position of the maximum diameter, it is possible to efficiently prevent looseness. A clearance is made out of the contact surface of the ridges, and it is possible to maintain tightening torque light. When a looseness preventive agent is filled in the clearance, no peeling is caused, and it is possible to repeatedly use the male screw.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a male screw such as a bolt or a screw, and more particularly to a screwing structure of a male screw which is easy to tighten and does not loosen easily and a female screw using the male screw.

[0002]

2. Description of the Related Art A female screw is engraved on a member to be fastened, such as metal or plastic, by tapping or the like, and a male screw which is tightened and fixed with a tightening screw such as a bolt or a screw is used as a machine screw for assembling various machines. Have been.

FIG. 5 is a sectional view showing such a conventional male screw 1 and female screw 2 in a screwed state. The thread of the male thread 1 and the thread of the female thread 2 have the same shape. If the crest of one thread and the bottom of the other thread are exactly overlapped, the thread stops without looseness and is loosened. It becomes difficult.

However, in such a case, the entire surfaces of both male and female threads come into contact with each other, so that the tightening torque is excessively increased and the tightening becomes difficult. Therefore, as shown in FIG.
The tightening torque is reduced by making the outer diameter D 'larger than the outer diameter D'.

However, with such a configuration,
When the male screw is screwed in the direction of the arrow in FIG. 5, the front slope 1 a in the screwing direction contacts the rear slope 2 a in the screwing direction of the female screw 2, but a gap s is formed on the opposite side.

Due to the formation of such a gap s, if vibration is applied after tightening, the slope 1a of the male screw and the slope 2a in contact with the female screw are separated at some point, and the screw is loosened.

As a countermeasure, various anti-slack agents may be used. In this method, a semi-molten anti-loosening agent is applied to a male screw in advance, dried, and then screwed into a female screw for use.The anti-loosening agent is made up of small capsules, which are broken when screwed. Then, it is again in a molten state, penetrates into a narrow gap and solidifies, and prevents loosening of the screw by the adhesive force.

However, as shown in FIG. 5, the contact area of the screw thread moves to the opposite side of the thread when the area where the male and female threads are in contact is large and when tightening and loosening. Most of the anti-slack agents rub against the threads of the mating side when tightening or loosening, and peel off.
In particular, when using screws repeatedly for machine maintenance, etc., loosen and remove the tightened male screws.
There is a problem that the anti-slack agent is peeled off each time, but the anti-slack effect is greatly reduced each time it is reused. In addition, when reused, there is also a problem that scum of the anti-loosening agent is scattered and stained around.

In order to solve such a problem, the applicant has proposed in Japanese Patent Application Laid-Open No. 5-71524 a screw having a structure shown in FIG. In FIG.
Indicates a male screw, and 4 indicates a female screw. The male screw advances in the direction of the arrow and is tightened. The thread W of the male screw 3 has a peak width W larger than the root width w of the female screw 4 to be screwed. Further, when the flank angles of the male screw 3 are α and β before and after the tightening direction as shown in the drawing, and the flank angles of the female screw 4 are γ on both sides as shown, α = γ and β <γ.

When the male screw is tightened to the female screw by the above configuration, the rear end portion 3a of the male screw crest bites into the female screw 4, and the auxiliary female screw 5 is screwed in while tapping. Then, even if this portion is strongly pressed against the female screw 4 and receives a vibration or the like after tightening, it becomes a resistance in the loosening direction, and the loosening can be prevented.

[0011]

However, since the above-mentioned screw taps the auxiliary female screw 5, the screw must be quenched, which increases the number of manufacturing steps, and
There was a problem that inexpensive materials could not be used.

The present invention has been made in view of such circumstances, and has as its object to provide an inexpensive male screw that can reliably prevent loosening, does not require quenching, and is inexpensive. Further, the present invention provides a male screw which can sufficiently exert the effect of the anti-loosening agent, is hardly peeled off even when used repeatedly, and has a long-lasting effect, and a female screw using the male screw. It is an object.

[0013]

In order to achieve the above object, a male screw according to the present invention has a peak width of a male screw equal to a root width at a threaded portion of a female screw, and a female screw is formed on at least one of both slopes at the peak. The contact surface is formed so as to overlap with the slope of the threaded portion, and a gap is formed between the contact surface and the female screw at a portion other than the contact surface.

Alternatively, the crest width of the male screw is made equal to the trough width of the threaded portion of the female screw, a contact surface is formed on at least one of the two slopes of the crest, and the flank angle of the contact surface is set to the flank angle of the opposite slope of the female screw. The contact surface is always in contact with the internal thread at the top of the mountain by making it smaller than the angle by the angle smaller than the angle. A gap is formed between the thread and the thread.

Alternatively, the peak width of the male screw is made equal to the root width of the threaded portion of the female screw, one of the flank angles of both slopes of the male screw is made smaller than the opposite flank angle of the female screw, and the other flank angle is made the peak side. The flank angle on the peak side may be made smaller by 1 to 2 degrees than the flank angle of the female screw, and the flank angle on the foot side may be smaller than the flank angle of the female screw.

In each of the above structures, it is preferable that the contact surface is formed on a slope rearward in the tightening direction of the male screw. The screwing structure of the male screw and the female screw of the present invention is a screwing structure of any one of the above-described male screw and female screw, and is characterized in that the clearance is filled with a slack preventing agent.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a main part of a screw 10 having a male screw 11 of the present invention. As shown in the figure, a screw 10 has a male screw 11, a head 12 for turning by a driver, and a head 12 for fitting a driver bit.
And a cross-shaped bit hole 12a.
The male screw 11 has a contact surface 11a on the top of the screw head 12 side.

This contact surface will be described with reference to FIGS. FIG. 2 is an enlarged view of the contact surface 11a, FIG. 3 is an enlarged view showing the shapes of the threads of the male screw 11 and the female screw 15, and FIG.
FIG. 2 is a sectional view of a main part showing a state where the male screw 11 and the female screw 15 of FIG. 1 are screwed together. In these figures, the traveling direction of the male screw 11 is indicated by an arrow.

As shown in FIG. 3, first, the width H of the crest of the male screw 11 is the same as the root width h into which the female screw 15 is fitted. The thread of the male screw 11 has two slopes 11a and 11b bent rearward in the tightening direction, and the slope 11a on the top of the mountain serves as the contact surface 11a. The front slope in the fastening direction is only 11c. The flank angles of the slopes are a, b, and c as shown in the figure.

On the other hand, the thread of the female screw 15 is an isosceles triangle, and the flank angles of the front and rear slopes 15a and 15b are both equal d. In the above embodiment, the values of a, b, c, and d are as follows. a
= 29 °, b = 20 °, c = 25 °, d = 30 °

There is a slight difference of 1 ° between a and d.
That is, the contact surface 11a is always in contact with the slope of the female screw on the top of the mountain, but is below (or at the foot of) the contact surface 11a.
In this case, a small gap is formed between the female screw 15. When receiving a stress due to a tightening force or a temperature change after the tightening, the thread of the male screw 11 is elastically deformed, but the deformation is possible until the gap disappears. With such a configuration, the contact surface 11a A large force will be applied to the top of the mountain as if pressing it with a spring.

Here, the crest of the thread of the male screw 11 is the maximum position of the diameter of the male screw 11. Then, since a frictional force due to the elastic force is applied to the position where the diameter is the largest, the resistance torque due to the frictional force is maximized. In other words, the force applied to the contact surface 11a after tightening the screw acts maximally to prevent loosening, and is most efficient.

Next, there is a relationship of b <a, and a gap s having a wedge-shaped cross section is formed between the male and female screws at the foot of the male screw 11. Then, although c <d, ab is about 10 °, whereas the value of dc is about half of the angle, about 5 °.

As shown in FIG. 4, when the male screw 11 is screwed into the female screw 15, the crest of the screw thread of the male screw 1 fits into the valley of the female screw 15 without play in the axial direction (of the screw). Combine. Further, the male screw 11 can be deformed by the tightening force until the entire contact surface 11a comes into surface contact with the inclined surface 15b of the female screw 15. On the other hand, on the slope opposite to the contact surface, only the ridgeline of the peak is in line contact.

Apart from the crest of the male screw 11, there is a difference in the flank angle as well as between the crest of the male screw and the root of the female screw, so that a gap s is formed between the slopes of the male and female threads. Can be secured. Therefore, it is possible to lightly tighten without increasing the tightening torque.

In the above configuration, the flank angles a, b,
c is not limited to the numerical value of the embodiment. Although da was 1 ° in the above embodiment, it is sufficient that the deformation of the thread is within the elastic limit, and about 1-2 ° is an appropriate range.

If the flank angle a is exactly the same as d, the entire contact surface 11a is always in contact with the female screw, and the effect of the above-described elastic force cannot be obtained. However, since the contact surface 11a itself is at the top of the screw thread, a force such as a large tightening force is applied thereto, and the effect of preventing loosening is slightly reduced, but is far superior to the conventional screw. .

FIG. 4B is a view showing an embodiment in which the above-mentioned gap s is filled with the anti-loosening agent A. As described in the conventional example, various anti-loosening agents are used to prevent the loosening of the screw. In the case of the male screw of the present invention, the anti-loosening agent is most suitable.

In a conventional ordinary screw as shown in FIG. 5, even when an anti-loosening agent is applied, the female and male threads come into contact and rub against each other when tightening, and the anti-loosening agent is peeled off to prevent loosening. Could not be sufficiently obtained.

On the other hand, in the male screw 11 of the present invention, as shown in FIG. 4 (b), a gap s is always formed except for the contact surface 11a. The same shape is maintained when tightening and loosening (because there is no axial backlash in the screwing). Therefore, the anti-loosening agent A is not peeled off, and the threads on both sides are kept in an adhered state, so that loosening can be effectively prevented. In particular, even when the screw is used repeatedly, since the anti-loosening agent does not peel off, the decrease in the adhesive strength is minimal, and the effect of preventing the loosening can be maintained.

Further, since the external thread 11 of the present invention does not require tapping of the auxiliary internal thread 5 like the thread of FIG. It can be used, and cost reduction from both materials and processes is possible.

Further, in the case of the male screw of the present invention, the contact surface 11a is always in contact with the female screw even during the screwing with the female screw. Never. Therefore, it can be used as an adjusting screw. In the above embodiment, the contact surface 11a is formed behind the advance of the male screw.
The effect of the present invention can be obtained even if it is formed on the front or on both sides.

[0033]

As described above, in the male screw of the present invention, the crest width of the male screw is made equal to the crest width of the screw portion of the female screw, and at least one of the two slopes at the crest is the slope of the screw portion of the female screw. The contact surface is formed so as to overlap with the contact surface, and a gap is formed between the contact surface and the female screw in a portion other than the contact surface, so that the force applied to the outermost diameter of the male screw can be maximally used to prevent loosening. . In addition, since a gap is formed between the external thread and the female thread at other portions, the screw can be tightened with a light tightening torque.

Further, if the contact surface is always in contact with the female screw on the top of the mountain and at the foot thereof is contacted with the female screw when subjected to elastic displacement, a difference is made between the opposing slope of the female screw and the flank angle by a small angle. Since the elastic force due to the elastic deformation of the thread of the male screw is applied, loosening can be more strongly prevented.

In particular, if the contact surface is formed rearward in the direction of tightening the male screw, it is particularly effective to prevent loosening. Also,
Since there is no need to quench the screws, cost reductions are possible in both manufacturing processes and materials.

A gap is provided between the male screw and the female screw. If the anti-loosening agent is filled in this space, the anti-loosening agent is not peeled off by the clearance, and the adhesive strength can be kept strong. Further, even if it is repeatedly used, the decrease in the slack-preventing effect is small.

[Brief description of the drawings]

FIG. 1 is a front view of a screw provided with a male screw according to the present invention.

FIG. 2 is an enlarged view showing a main part of the male screw of FIG.

FIG. 3 is an enlarged view showing male and female screw thread shapes.

FIG. 4 (a) is a cross-sectional view of a main part showing a state in which a male screw of the present invention is screwed into a female screw, and FIG. 4 (b) is a view showing a state in which a clearance is filled with a slack preventing agent.

FIG. 5 is a cross-sectional view showing a conventional male and female screw threaded state.

FIG. 6 is a cross-sectional view showing another conventional male and female screw threaded state.

[Explanation of symbols]

 11 Male thread 11a Contact surface (slope) 11b, 11c Slope 15 Female screw 15a, 15b Slope (of female screw) H Peak width h Root width s Gap A Anti-loose agent a, b, c, d Frank angle

Claims (5)

[Claims] 1. A crest width of a male screw is made equal to a root width of a screw portion of a female screw, and a contact surface overlapping with a slope of the screw portion of the female screw is formed on at least one of both slopes at the crest. A male screw characterized in that a gap is formed between the female screw and the female screw. 2. A crest width of a male screw is made equal to a root width of a threaded portion of a female screw, a contact surface is formed on at least one of both slopes of the crest, and a flank angle of the contact surface is determined by a flank angle of a flank of the opposite slope of the female screw. The contact surface is always in contact with the internal thread at the top of the mountain by making it smaller than the angle by the angle smaller than the angle. A male thread, wherein a gap is formed between the thread and the thread. 3. The crest width of the male screw is made equal to the root width of the threaded portion of the female screw, one flank angle of both slopes of the male screw is made smaller than the opposite flank angle of the female screw, and the other flank angle is made the crest side. 2. A contact surface in which the flank angle at the peak is smaller by 1 to 2 degrees than the flank angle of the female screw, and the flank angle at the foot is smaller than the flank angle of the female screw. Male screw as described. 4. The contact surface according to claim 1, wherein the contact surface is formed on a slope rearward in a tightening direction of the male screw.
The male screw according to any one of the above. 5. The male screw according to claim 1, wherein:
A screwing structure of a female screw and a female screw, wherein the clearance is filled with a slack preventing agent.