JP3017331B2 - Loosening prevention screw - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tightening without the use of a washer
In particular, loosening occurs after tightening
The present invention relates to a slack-preventing screw which is difficult to be repelled .

[0002]

BACKGROUND ART screws for tightening, tightening a plurality of members
It is used in all industrial fields because it can be combined easily. However, there is a problem that such a screw generally has a small return torque and is easily reversed and loosened by vibrations received after tightening.

As a solution to this problem, when bolts and nuts are used, means such as a spring washer and a double nut are generally employed. Also, in the case of the tapping screw, it may be provided a washer backstop, and or using an adhesive.

Regarding this problem, the present inventor has previously proposed in Japanese Patent Application No. 2-246203 a tapping screw particularly suitable for plastics.
No. 7 proposes a slack preventing screw for relatively soft metal such as aluminum die cast. However, these screws are used to fasten thin plates such as iron plates without using washers.
Is not very suitable when the thickness is, for example, 0.5
In the case of mm approximately thin plate is made because the screw thread of the external thread is only about two mountains not screwed into the internal thread, the frictional resistance of the contact surface of the thin plate of the female screw and the male screw is rather small, easily loosened occurs this
From, as the tightening screw for thin, none of them can effectively prevent loosening.

[0005]

DISCLOSURE OF THE INVENTION The present invention is directed to a thin steel plate or the like.
Ideal as a male screw to be screwed into the plate without using a washer
It is intended to provide a loosening prevention screw .

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, a loosening prevention screw according to the present invention is tightened without using a washer.
In the male screw to attach and fix, on the bearing surface of the head of the male screw,
Co when forming the smooth wave shape along the circumferential direction
At the position where the bearing surface of the head of the male screw is divided by 3
And the height difference of the wave shape is about 4 m
Provide a plurality of shallow irregularities of about m / 100, the width of the irregularities to extend in the normal direction of the seat surface , the male screw,
The peak width of the male screw is wider than the root width at the threaded portion of the female screw.
Comb and divide the thread angle by a line perpendicular to the screw axis
The angle on the front side in the tightening direction of the male screw
Angle is almost the same as the angle
By making the angle smaller than the angle on the front side,
The rear end of the peak bites into the female screw and taps the female screw
It is constituted so that it may be screwed in while plugging.

[0007]

[Action] When the male screw is screwed into the female screw member made of a thin plate such as an iron plate, the wave-shaped irregularities of the seating surface of the head come into contact with the peripheral surface of the screw hole of the female screw member.
The unevenness of the wave shape and the peripheral surface of the screw hole come into contact with elastic compression deformation, so that the seating surface and the thin plate are in a state of familiarity.
Therefore , a large frictional resistance is generated on the contact surface by the elastic contact. Position where the wave-shaped unevenness divides the seat surface of the head by 3
The head is supported at three points on the seat,
A fixed pressure contact state is obtained. This frictional resistance is generated in a region extending in the normal direction of the seat surface.

A female screw is set up, and the rear end of the peak of the male screw screwed into the female screw bites into the valley of the female screw and is screwed in while tapping. With this tapping,
The slope in front of the male screw is pressed against the slope of the facing female screw with a strong force. since it resistance, frictional resistance slack direction of the male screw is further increased.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) to 1 (c) show a screw which is a male screw with a head according to the present invention. In these figures, male screw A
Has a male screw portion 1 and a head portion 2, and a cross hole 21 is formed in the head portion 2 for engaging with a tip portion of a driver. Reference numeral 3 denotes a female screw member made of a thin plate.

A plurality of irregularities are formed on the bearing surface 22 of the head 2 in a direction perpendicular to the plane of FIG. 1 (b). That is,
Reference numeral 22a denotes a convex portion, and 22b denotes a concave portion. As shown in FIG. 1 (b), the width of the concave / convex portion extends substantially the entire length of the seat surface 22 in the radiation direction. As shown in FIG. 1 (c), the unevenness draws a gentle sinusoidal wave in the circumferential direction of the seat surface 22. The depth d of the unevenness is appropriately determined from the hardness of the head and the female screw member, and the like .
, If the screw diameter is about 5 mm.phi, depth d of the irregularities about 4 m
m / 100, and three irregularities are provided on the circumference at substantially equal intervals.

When the male screw A having the above configuration is screwed into the female screw member 3 and tightened so that the seat surface 22 and the female screw member 3 are pressed against each other, the seat surface 22 is strongly pressed against the female screw member 3. Since the unevenness of the bearing surface 22 is a smooth wave shape was along Tsu <br/> the circumferential direction of the seating surface 22 fastening the male thread A
Only easy, since the depth d of the concave-convex it is shallower and 4 mm / 100, easily pressing surface mutually deformed elastically compressed, and as it were the seat surface
When the female screw member is in a familiar state, the seating surface 22 can be in close contact with the female screw member 3 with a large area almost close to the entire surface . Therefore, even if a torque in the loosening direction acts on the male screw A after the tightening, the frictional force due to the elastic compressive force between the seat surface 22 and the female screw member 3 increases, and the male screw A screwed into the thin plate.
It is possible to prevent the slack. This mutual pressing surface
Since it is elastic deformation within the elastic limit, it will not be damaged.
No.

FIG. 2 is a partial cross-sectional view of the shape of the male screw A having the unevenness on the seat surface 22 for further increasing the slack prevention force of the male screw A. It is sectional drawing which shows the state which the male screw part 1 of the male screw A screwed with the female screw 31 formed in the female screw member 3, and the arrow symbol of the figure has shown the advancing direction of the male screw part 1 at the time of fastening. The thread 11 of the external thread portion 1 has a top parallel to the screw tightening direction and a flat surface along the spiral of the screw, and the width W of the top is the position at which the top is screwed with the female screw 31. It is wider than the valley width w.

Another feature of the male screw portion 1 is shown in FIG.
As shown in the figure, when the thread angles of the male screw and the female screw are divided into angles α, β and α ′, β ′ before and after the tightening direction by lines 13, 13 ′ perpendicular to the screw shaft 12, as shown in FIG. And the angle β on the rear side in the tightening direction of the male screw is β <α or β <β ′.
It is to make it. In other words, the slope 11a on the front side in the tightening direction of the male screw is made substantially parallel to the slope 31a on the facing female screw, and the slope 11b on the rear side in the tightening direction of the male screw is made closer to the vertical direction to form an asymmetric thread. In the male screw shown in the embodiment of the present invention , α = 3
0 °, a β = 20 °, the internal thread, α '= β' = 3
0 °.

A female screw 31 is set on the female screw member 3, and a bolt or a screw-like male screw is screwed into the female screw 31. As described above, the peak width W of the external thread is wider than the root width w of the threaded portion of the corresponding internal thread, and the front slope 11a of the thread.
Is substantially parallel to the slope 31a of the female screw, and the rear slope 11b
Stands nearer to the screw shaft 12 than the slope 31b of the female screw, so that the rear end of the crest of the male screw 11 bites into the female screw 31, and the female screw 4 is screwed in while tapping. Due to this tapping, the slope 11a in front of the male screw is strongly pressed against the slope 31a of the female screw, and the frictional force due to this pressing and the engagement of the tapped female screw 4 generate a resistance against the torque in the loosening direction.

For comparison with the anti-loosening screw of the present invention,
FIG. 4 shows a screwed state of a general screw. Here, α = β
= Α ′ = β ′, and the peak width W ′ ≦ the valley width w ′. Therefore, when the rear slope 11b of the male screw is pressed by the slope 31b of the female screw, the male screw is screwed in, and a gap is formed between the front slope 11a of the opposite male screw and the slope 31a of the opposite female screw. I have.
When screw tightening is completed,
The adhesion between the slopes 11b and 31b is easily reduced, and the thread 11 is loosely fitted in the valley of the female screw. Therefore, when a torque in the loosening direction is generated, the torque is easily loosened without being able to resist the torque.

[0016] In contrast, FIG. 2, the screw shown in FIG. 3, the rear of the summit of the male screw bites into the valleys of the female thread 4, since the slope 11a of the front external thread is pressed against the inclined surface 31a of the female thread 4 by the bite In addition, the resistance to the torque in the loosening direction increases. When the female screw member is a thin plate, although the number of screw threads to be screwed with the male screw is small, a loosening prevention effect corresponding to the number of screw threads to be screwed is generated.
By adding the embodiment of FIGS. 2 and 3 to the male screw of the embodiment of the present invention, a female screw member having a small number of crests such as a thin iron plate can be obtained.
Also , the effect of preventing the external thread from being loosened can be further enhanced.

[0017]

According to the loosening prevention screw of the present invention , a gentle wavy shallow unevenness is formed on the seat surface of the head of the male screw.
And the height difference of the wave shape is about 4 mm /
Since it is of the order of 100, irregularities and the female screw member and Ji large frictional resistance force is raw elastic compression force to prevent the loosening occurs on the contact surface, it is possible to reliably prevent loosening. Ma
In addition, since the irregularities extend in the normal direction of the seat surface, they are prevented from loosening.
The force generation area is widened, and the irregularities are
Because it is formed at a position that divides the bearing surface by 3
The seat surface is supported at three points, resulting in good stability.
You. Therefore, the female screw member having a small number of threads, such as a thin iron plate, and the male screw can be tightened and fixed without damaging the contact surface, and a loosening prevention effect can be exhibited. When the male screw is screwed into the female screw, the male screw
The rear end of the mountain top bites into the female screw and taps the female screw.
This tapping allows
The slope in front of the male screw is strongly pressed by the slope of the female screw,
Engagement of the frictional force due to this pressing with the tapped female screw
This produces a resistance to the torque in the loosening direction.
Therefore, the male screw is loosened by the unevenness provided on the bearing surface of the head.
Combined with the anti-sagging effect, it is possible to further increase the slack prevention power
it can. FIG. 5 shows the loosening of the present invention by the torque analyzer.
Tightening / loosening torque as a result of measuring the return torque of the prevention screw
It is a graph which shows a lux ratio, S is a tightening torque, L is
It shows return resistance (relaxation torque). It is clear from this figure
As can be seen, high loosening torque for low screwing torque
And has excellent slack prevention effect.
I will tell. After tightening and loosening 5 times,
The tightening / loosening torque ratio has hardly changed.
It turns out that usability is high.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a loosening prevention screw according to the present invention, wherein (a) is a front view, (b) is a right side view of (a), and (c) is a view of B in FIG. .

FIG. 2 is a partial cross-sectional view showing a screwed state of a male screw and a female screw having asymmetrical threads.

FIG. 3 is an enlarged view of a portion C in FIG. 2;

FIG. 4 is a cross-sectional view of a main part showing a screwed state of a conventional general screw.

FIG. 5 Tightening / loosening screws in the loosening prevention screw of the present invention
It is a graph which shows a luck ratio.

[Explanation of symbols]

 A Male screw W Peak width of male screw w 'Root width at threaded portion of female screw α Angle of front side in tightening direction of male screw β Angle of rear side in tightening direction of male screw α' Angle of front side in tightening direction of female screw β ' Backward angle in tightening direction 1 Male thread 11 Thread 11a Front slope of thread 11b Rear slope of thread 2 Head 22 Seat 22a, 22b Irregularity 3 Female thread member 31 Female thread 31a, 31b Female thread slope 12 Screw shaft 13 Line perpendicular to screw axis

Continuation of the front page (56) References JP-A-61-286605 (JP, A) JP-A-61-241512 (JP, A) JP-A-62-63013 (JP, A) JP-A-62-63012 (JP, A) JP-A-57-186611 (JP, A) JP-A-47-6266 (JP, U) JP-A-61-84217 (JP, U) JP-A-63-99016 (JP, U) 63-86103 (JP, U) Jiko 36-108 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16B 39/282 F16B 39/30

Claims (1)

(57) [Claims] (1) A male member that is fastened and fixed without using a washer.
In the same manner, the surface of the head of the male screw has a gentle wave shape along the circumferential direction , and the head of the male screw has
Each be formed a seat surface 3 divided position, difference in height of the wave shape is provided about 4 mm / 100 about shallow plurality of irregularities, the width of the concave convex actinomycetes direction of the seat surface And the external thread has a crest width of the external thread.
Make the width wider than the root width at the threaded portion of the female screw, and
Angle divided by a line perpendicular to the screw axis,
Make the angle on the front side of the attachment direction almost the same as the angle on the rear side of the female screw.
The angle on the rear side in the tightening direction of the male screw as the angle on the front side.
The rear end of the crest of the male screw is
It is screwed while tapping the female screw while biting into the screw
A slack-preventing screw characterized in that it is configured as follows .