JP3977496B2 - Male thread, and screwed structure of male thread and female thread - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a male screw such as a bolt or a screw, and particularly relates to a screwed structure of a male screw that is easy to tighten and that is not easily loosened, and a female screw using the male screw.
[0002]
[Prior art]
2. Description of the Related Art A male screw that has a female screw engraved on a member to be fastened such as metal or plastic by tapping or the like and is fastened and fixed with a fastening screw such as a bolt or a screw is used as a machine screw for assembly of various machines.
[0003]
FIG. 5 is a cross-sectional view showing such a state in which the conventional male screw 1 and female screw 2 are screwed together. The thread of the male screw 1 and the thread of the female screw 2 have the same shape. If the top of one screw thread and the bottom of the other screw thread are exactly overlapped, the screw thread stops without looseness and loosens. It becomes difficult.
[0004]
However, if this is done, the entire surface of both male and female threads will come into contact with each other, so that the tightening torque will increase excessively and tightening will be difficult. Therefore, as shown in FIG. 5, the trough diameter D of the female screw 2 is made larger than the outer diameter D ′ of the male screw 1 to reduce the tightening torque.
[0005]
However, with such a configuration, when the male screw is screwed in the direction of the arrow in FIG. 5, the front slope 1a in the screwing direction contacts the slope 2a behind the female screw 2 in the screwing direction. Can be done.
[0006]
Because of such a gap s, when vibration is applied after tightening, the inclined surface 1a of the male screw and the inclined surface 2a in contact with the female screw are separated soon, and the screw is loosened.
[0007]
As a countermeasure against this, various slack preventing agents may be used. In this method, a semi-molten anti-sagging agent is applied to the male screw in advance, dried, and then screwed into the female screw. The anti-sagging agent consists of a small capsule that breaks when it is screwed in. Then, it becomes a molten state again, enters into a narrow space and solidifies, and prevents loosening of the screw by the adhesive force.
[0008]
However, as shown in FIG. 5, the area where the male and female screw threads are in contact is large, and when the screw is tightened and when the screw thread is loosened, the contact surface of the screw thread moves to the opposite side of the mountain (or the gap s). Most of the anti-sagging agent rubs and peels off against the other thread when tightening or loosening. In particular, when the screw is used repeatedly for machine maintenance, etc., the tightened male screw is loosened and removed, and then tightened again.Each time, the anti-loosening agent peels off and prevents loosening. There was a problem that the effect was greatly reduced with each reuse. In addition, there is also a problem that the slack of the anti-sagging agent is scattered around the periphery when reused.
[0009]
In order to solve such a problem, the applicant has proposed a screw that does not require a slack preventing agent having the configuration shown in FIG. 6 in Japanese Patent Laid-Open No. 5-71524.
In the figure, 3 is a male screw, 4 is a female screw, and the male screw advances in the direction of the arrow and is tightened. The screw thread of the male screw 3 has a crest width W greater than the valley width w of the female screw 4 to be screwed. Further, when the flank angle of the male screw 3 is α and β before and after the tightening direction as shown in the drawing and the flank angle of the female screw 4 is γ on both sides as shown, α = γ and β <γ.
[0010]
When the male screw is fastened to the female screw with the above configuration, the rear end portion 3a of the top of the male screw bites into the female screw 4, and the auxiliary female screw 5 is screwed in while tapping. And even if this part is strongly pressed by the internal thread 4 and receives a vibration etc. after tightening, it becomes resistance to a slack direction and can prevent slack.
[0011]
[Problems to be solved by the invention]
However, since the above-mentioned screw is tapped with the auxiliary female screw 5, there is a problem that the screw has to be quenched, the manufacturing process is increased, and inexpensive materials cannot be used.
[0012]
The present invention has been conceived from such circumstances, and an object of the present invention is to provide a male screw that can surely prevent loosening and that can be inexpensively quenched without being quenched. In addition, the present invention provides a screwed structure of a male screw that can sufficiently bring out the effect of the anti-sagging agent, is difficult to peel off even when used repeatedly, and that maintains the effect, and a female screw using this male screw. It is an object.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the male screw according to the present invention eliminates the gap between the male screw's crest and the female screw by making the crest width of the male screw the same as the valley width at the screwed portion of the female screw, and both slopes at the crest. Two slopes are formed on at least one of the two slopes, and the slope on the mountain top side of the two slopes is a contact surface that overlaps the slope of the threaded portion of the female screw, and the other slope of the two slopes is connected to the female screw. It is characterized in that a gap is formed between them.
[0014]
Alternatively, the crest width of the male screw is the same as the valley width at the threaded portion of the female screw, eliminating the gap between the crest portion of the male screw and the female screw, and forming two slopes bent at at least one of the two slopes at the summit portion. The slope on the top of the two slopes is the contact surface, and the flank angle of the contact surface is made smaller by a minute angle than the flank angle of the opposing slope of the female screw, so that the contact surface is always in contact with the female screw on the peak side. On the other hand, it is characterized in that it is in contact with the female screw when subjected to elastic displacement on the heel side, and a gap is formed between the other inclined surface and the thread of the female screw.
[0015]
Or it may be a full rank angle of the contact surface as a structure in which 1 to 2 ° smaller than the flank angle of opposing internal thread.
[0016]
In each of the above configurations, it is desirable that the contact surface be formed on a slope on the rear side of the male screw in the tightening direction.
The screwed structure of the male screw and the female screw according to the present invention is a screwed structure of any of the above male screws and female screws, and is characterized in that the gap is filled with a slack preventing agent.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a view showing a main part of a screw 10 provided with a male screw 11 according to the present invention. As shown in the figure, the screw 10 has a male screw 11, a head 12 for turning by a screwdriver, and a cross-shaped bit hole 12a formed in the head 12 for fitting a driver bit. is doing. The male screw 11 has a contact surface 11a on the top of the screw head 12 side.
[0018]
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 shape of the thread of the male screw 11 and the female screw 15, and FIG. 4 is a diagram of the male screw 11 and the female screw 15 of FIG. It is principal part sectional drawing which shows a state. In these drawings, the traveling direction of the male screw 11 is indicated by an arrow.
[0019]
As shown in FIG. 3, first, the width H of the crest of the male screw 11 is the same as the valley width h into which the female screw 15 is fitted. Further, 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 summit side becomes the contact surface 11a. The slope in front of the tightening direction is only 11c. And let the flank angle of each slope be a, b, c as shown in the figure.
[0020]
On the other hand, the thread of the female screw 15 is an isosceles triangle, and the flank angles of the front and rear inclined surfaces 15a and 15b are both equal d.
And in the said Example, the value of these a, b, c, and d is as follows. a = 29 °, b = 20 °, c = 25 °, d = 30 °
[0021]
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 mountain top side, but a minute gap is formed between the contact surface 11a and the female screw 15 on the lower side (or the heel side) of the contact surface 11a. 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 is eliminated. With such a configuration, the contact surface 11a A large force is applied to the top of the mountain as if it were pressed by a spring.
[0022]
Here, the peak portion of the thread of the male screw 11 is the maximum position of the diameter of the male screw 11. And since the frictional force by an elastic force is added to the position where the diameter is the maximum, the resistance torque by this frictional force becomes the maximum. In other words, after the screw is tightened, the force applied to the contact surface 11a acts to the maximum to prevent loosening, which is most efficient.
[0023]
Next, there is a relationship of b <a, and a wedge-shaped gap s is formed between the male and female screws on the heel side of the male screw 11. Although c <d, a−b is about 10 °, whereas the value of d−c is about half of the angle, about 5 °.
[0024]
As shown in the screwed state diagram of FIG. 4, when the male screw 11 is screwed into the female screw 15, the crest portion of the screw thread of the male screw 1 is fitted into the valley of the female screw 15 without backlash in the axial direction (of the screw). Further, the male screw 11 can be deformed until the entire contact surface 11a comes into surface contact with the inclined surface 15b of the female screw 15 by the tightening force. On the other hand, on the slope opposite to the contact surface, only the ridgeline at the summit is in line contact.
[0025]
Further, since the flank angle is different between the top of the male screw and the bottom of the female screw except for the top of the male screw 11, a gap s can be secured between the slopes of the male and female screw threads. Therefore, it is possible to lightly tighten without increasing the tightening torque.
[0026]
In the above configuration, the flank angles a, b, and c are not limited to the numerical values of the embodiments. Although da was 1 ° in the above-described embodiment, it may be in a range where the deformation of the screw thread is within the elastic limit, and about 1 to 2 ° is an appropriate range.
[0027]
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 above-described effect due to the elastic force cannot be obtained. However, since the contact surface 11a itself is at the top of the screw thread, a large tightening force or the like is applied thereto, and the effect of preventing loosening is slightly reduced, but it is far superior to the conventional screw. .
[0028]
FIG. 4B is a view showing an example in which the gap s is filled with the slack preventing agent A. As described in the prior art, various anti-loosening agents are used to prevent the loosening of the screw. In the case of the male screw of the present invention, such an anti-loosening agent is optimal.
[0029]
In the case of conventional screws as shown in FIG. 5, even when a loosening preventive agent is applied, the male and female screw threads come into contact and rub against each other when tightening, and the loosening preventive agent peels off. I couldn't get enough.
[0030]
On the other hand, in the male screw 11 of the present invention, as shown in FIG. 4 (b), there is always a gap s other than the contact surface 11a, and this gap s is (for screwing between the male screw and the female screw). The same shape is maintained when tightening and loosening (there is no axial backlash). Therefore, the slack preventing agent A is not peeled off, and the screw threads on both sides can be kept in an adhesive state, and slack can be effectively prevented. In particular, even when the screw is used repeatedly, the anti-sagging agent does not peel off, so that the adhesive force can be reduced little and the anti-slack effect can be maintained.
[0031]
Further, since the male screw 11 of the present invention does not need to be tapped with the auxiliary female screw 5 like the screw of FIG. 6, it is not necessary to quench and use a tempered material that is inexpensive in terms of material. This makes it possible to reduce costs from both materials and processes.
[0032]
Furthermore, in the case of the male screw according to the present invention, the contact surface 11a is always in contact with the female screw even during the screwing with the female screw. . Therefore, it can be used as an adjusting screw.
In the above-described embodiment, the contact surface 11a is formed behind the progression of the male screw. However, the contact surface 11a may be formed on the front or both sides, and the effects of the present invention can be obtained.
[0033]
【The invention's effect】
As described above, in the male screw of the present invention, the crest width of the male screw is the same as the valley width in the threaded portion of the female screw, and at least one of both slopes in the summit portion has a contact surface overlapping the slope of the threaded portion of the female screw. Since a gap is formed between the outer surface of the male screw and a portion other than the contact surface, the force applied to the outermost diameter of the male screw can be maximized to prevent loosening. In addition, a gap is formed between the other thread portion of the male screw and the screw thread of the female screw, so that tightening can be performed with a light tightening torque.
[0034]
In addition, if the contact surface is always in contact with the female screw on the mountain top side and the female side is elastically displaced on the heel side, a difference between the facing slope and the flank angle of the female screw by a small angle will be provided. Since the elastic force due to the elastic deformation of the mountain is added, it is possible to prevent loosening more powerfully.
[0035]
In particular, if the contact surface is formed behind the tightening direction of the male screw, it is particularly effective for preventing looseness.
Moreover, since it is not necessary to quench the screw, the cost can be reduced from both the manufacturing process and the material.
[0036]
A gap is secured between the male screw and the female screw, and if the anti-sagging agent is filled here, the anti-sagging agent is not peeled by the gap, and the adhesive force can be kept strong. Further, even if it is used repeatedly, the decrease in the loosening prevention effect is negligible.
[Brief description of the drawings]
FIG. 1 is a front view of a screw provided with a male screw of the present invention.
FIG. 2 is an enlarged view showing a main part of the male screw in FIG.
FIG. 3 is an enlarged view showing a male and female thread shape.
FIG. 4A is a cross-sectional view of a main part showing a state in which the male screw of the present invention is screwed to the female screw, and FIG. 4B is a diagram showing a state in which a gap is filled with a slack preventing agent.
FIG. 5 is a cross-sectional view showing a conventional screwed state of male and female screws.
FIG. 6 is a cross-sectional view showing a screwed state of another conventional male and female screw.
[Explanation of symbols]
11 Male thread 11a Contact surface (slope)
11b, 11c Slope 15 Female thread 15a, 15b Slope H (top of female thread) Slope width h Valley width s Gap A Slack preventing agent a, b, c, d Frank angle

Claims (5)

The crest width of the male screw is made the same as the valley width at the threaded portion of the female screw, the gap between the crest portion of the male screw and the female screw is eliminated, and two slopes are formed that are bent on at least one of both slopes at the summit portion, The slope on the mountain top side of the two slopes is a contact surface that overlaps the slope of the threaded portion of the female screw, and a gap is formed between the two slopes and the female screw on the other slope. Male screw to do. The crest width of the male screw is made the same as the valley width at the threaded portion of the female screw, the gap between the crest portion of the male screw and the female screw is eliminated, and two slopes are formed that are bent on at least one of both slopes at the summit portion , Whereas the slope on the summit side of the two slopes is a contact surface, the flank angle of the contact surface is made smaller than the flank angle of the opposing slope of the female screw by a small angle, whereas The male screw is configured to contact with a female screw when subjected to elastic displacement on the side, and a gap is formed between the other inclined surface of the two inclined surfaces and the thread of the female screw. External thread according to claim 2, characterized in that the full rank angle of the contact surface to 1 to 2 ° smaller than the flank angle of opposing internal thread.   The male screw according to any one of claims 1 to 3, wherein the contact surface is formed on an inclined surface behind the tightening direction of the male screw.   5. A screwed structure of the male screw and the female screw according to claim 1, wherein the gap is filled with a slack preventing agent.

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