JP3059939B2 - Screw loosening prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing relative loosening between a male screw member and a female screw member which are screwed together.

[0002]

2. Description of the Related Art In order to prevent relative loosening between a male screw member and a female screw member that are screwed together, a spring washer is interposed between the two screw members. However, it is not always possible to achieve a sufficient locking effect.

[0003] Further, by using a lock nut, a sufficient locking effect can be obtained. However, in order to use the lock nut, it is necessary to project the male screw member from the female screw member, so that the lock nut may not be used in some cases.

An object of the present invention is to provide a screw loosening prevention device which can solve the above-mentioned problem.

[0005]

SUMMARY OF THE INVENTION The present invention is an apparatus for preventing relative loosening between a male screw member and a female screw member which are screwed to each other. , The cam surface which is rotatable relative to the other in the loosening direction of the screw, and the other of the two screw members in the screwed state, and is rotatably rotated in the loosening direction of the screw to one of the two screw members. A possible cam receiving portion, and the cam surface and the cam receiving portion are pressed against each other from the axial direction of the male screw member in the screwed state of both screw members, and the cam surface is loosened when the screwing is loosened. The cam receiving portion has a shape that can be guided in the axial direction of the male screw member, and the axial moving distance of the cam receiving portion by the guidance of the cam surface is:
One characteristic is that the relative axial movement distances of the two screw members corresponding to the leads are made larger.

According to the structure of the present invention, when the male screw member and the female screw member relatively rotate in the loosening direction, one of the cam surface and the cam receiving portion becomes one of the male screw member and the female screw member. The other of the cam surface and the cam receiving portion rotates together with the other of the male screw member and the female screw member. As a result, the cam surface and the cam receiving portion rotate relative to each other, and the cam surface guides the cam receiving portion in the axial direction of the male screw member by the relative rotation. The axial movement distance of the cam receiving portion guided by the cam surface is larger than the relative axial movement distance corresponding to the leads of both screw members, and the cam surface and the cam receiving portion are in the screwed state of the two screw members. Since the male screw members are pressed against each other in the axial direction, an axial force acts on the screwed portions of the two screw members. The relative rotation of the two screw members in the loosening direction can be prevented by the axial force.

In the present invention, there is provided a pressing portion rotatable with one of the male screw member and the female screw member, and a washer through which the male screw member is inserted, and one of the pressing portion and one of the washers. The cam surface is formed on the other side, and the cam receiving portion is formed on the other side, and the washer is elastically compressed in the axial direction by being sandwiched between the male screw member and the female screw member via a pressing portion. It is preferable that the elastic member is deformable, and that the elastic member is capable of cutting into the other side of the male screw member and the female screw member so as not to rotate relative to each other when the screw is loosened. Thereby, the male screw member and the female screw member are screwed together, and the washer is elastically compressed and deformed through a pressing portion that rotates together with one of the male screw member and the female screw member, thereby changing the washer. When the screw is loosened, the male screw member and the female screw member can bite into the other side so that they can rotate together. A cam surface is formed on one of the pressing portion and the washer, and a cam receiving portion is formed on the other, so that one of the cam surface and the cam receiving portion has one of the male screw member and the female screw member, The other of the surface and the cam receiving portion rotates together with the other of the male screw member and the female screw member when the screwing is loosened. That is, the screw can be prevented from loosening only by providing the pressing portion and the washer in which the cam surface and the cam receiving portion are formed.

In the present invention, there is provided a pair of washers into which the male screw member is inserted. One of the washers is formed with the cam surface, and the other washer is formed with the cam receiving portion. A spring washer that is elastically compressively deformable in the axial direction by being sandwiched between the male screw member and the female screw member. One of the washers is screwed to the male screw member side by elasticity based on the deformation. It is preferable that the other washer can be cut into the female screw member side so as not to rotate relative to the female screw member due to elasticity based on the deformation of the other washer. Thereby, the male screw member and the female screw member are screwed together, and the pair of washers are elastically compressed and deformed, so that one washer is provided on one side of the male screw member and the female screw member and the other is provided on the other side. The washer can be bitten. A cam surface is formed on one of both washers, and a cam receiving portion is formed on the other, so that one of the cam surface and the cam receiving portion has one of a male screw member and a female screw member, and the cam surface and the cam receiving portion. Is rotated together with the other of the male screw member and the female screw member when the screwing is loosened. That is, the loosening of the screw can be prevented only by providing a pair of washers in which the cam surface and the cam receiving portion are formed.

The screw loosening prevention device according to the present invention includes a washer through which the male screw member is inserted and a washer sandwiched between the male screw member and the female screw member. The thickness of one end of the washer and the thickness of the other end of the washer are changed from one end to the other end, and the difference between the thickness of the one end of the washer and the thickness of the other end of the washer is set to the screw groove of the female screw member. It is characterized in that it is set so that it can be pressed against one axial end and the other radial end can be pressed against the other axial end. According to this configuration, when the male screw member is screwed into the female screw member, a force for bending the male screw member acts because the thickness of the washer gradually decreases from one end in the radial direction to the other end. By the force, the screw thread of the male screw member is pressed against the screw groove of the female screw member at one radial end toward one axial end, and at the other radial end against the other axial end. Can be prevented from loosening. Further, when a force acts to displace the male screw member in the axial direction with respect to the female screw member, the inner peripheral end of the female screw member is pressed against the male screw member from the radial direction, and the axial displacement is reduced. Can be blocked. The washer is preferably a spring washer, and the thickness of the washer is preferably the thickest in the split groove forming portion so that the washer can bite into each screw member side so as not to rotate relative to each other when the screw is loosened. . Thereby, the thread of the male screw member can be pressed against the screw groove of the female screw member also by the elasticity based on the deformation of the washer. Further, the washer bites into the screw member side so that one axial end of each of the opposed ends of the split groove forming portion does not relatively rotate when the screwing is loosened. Thereby, loosening of the screw can be reliably prevented. Further, it is preferable that a notch is formed in the washer so that a portion that bites into each screw member side when the screw is loosened is deformed in a circumferential direction by a reaction force of the biting. Thus, the other end in the axial direction of each of the opposed ends of the split groove forming portion of the washer can be more securely bitten into the screw member side by the stress that tends to oppose the deformation.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A screw loosening prevention device according to a first embodiment shown in FIGS. 1 to 3 has a female screw exemplified by a structural member having a female screw 3a for a mounting member 4 with a bolt (male screw member) 1. FIG. In the case of fixing to the member 3, relative loosening of the bolt 1 and the female screw member 3 is prevented. In the fixed state, the mounting member 4 is integrated with the female screw member 3 by being fixed via the bolt and the female screw even at another position, for example.

The bolt 1 has a head 1a whose outer periphery follows a hexagon and a male screw 1b. The mounting member 4 has a through hole 4a for the male screw 1b. The male screw 1b and the female screw 3a are right-handed screws in the present embodiment. The male screw 1b is inserted into the pressing portion 5 and the washer 6.

The pressing portion 5 has a cylindrical shape, and a groove 5a is formed on one end surface of the pressing portion 5 so that the head 1a of the bolt 1 is fitted therein, so that the bolt 1 and the pressing portion 5 can rotate together. ing.

The washer 6 has a cylindrical portion 7 and a plate portion 8 having an outer periphery along a square.
Is welded to one end surface of the cylindrical portion 7. On one end surface of the cylindrical portion 7, a cam surface 10 in which the height of the cylindrical portion 7 gradually increases as the counterclockwise progression is made along the circumferential direction.
And a joining surface 11 along the axial direction at one end of the cam surface 10 where the height of the cylindrical portion 7 is the lowest.
The plate portion 8 is formed of, for example, spring steel, and its four corners are bite portions 12 bent toward the other end surface. Thereby, the washer 6 is attached to the bolt 1
Is inserted between the head portion 1a of the first member 1 and the female screw member 3 via the pressing portion 5 and the mounting member 4, the respective bite portions 1
2 is elastically deformed, so that it is elastically compressed and deformed in the axial direction. Further, in each of the bite portions 12, the length of each of the orthogonal portions 12a and 12b along the outer periphery of the plate portion 8 is the front portion 1 when the counterclockwise advance is made.
2a is shorter than the rear portion 12b. Accordingly, the elasticity based on the deformation causes the distal end 12 ′ of each biting portion 12 to rotate relatively to the mounting member 4 on the female screw member 3 side when the screwing is tightened, and not to rotate relatively when the screwing is loosened. Dig into it. By the biting, the cam surface 10 is rotatable relative to the bolt 1 along with the female screw member 3 in the screwed state in the loosening direction of the screwing.

The other end surface of the pressing portion 5 faces one end surface of the cylindrical portion 7 of the washer 6, and the cam surface 1
0, and a joining surface 16 that can be joined to the joining surface 11. Thereby, the cam receiving portion 15 is rotatable relative to the female screw member 3 along with the bolt 1 in the loosening direction of screwing. Also,
When the bolt 1 is screwed into the female screw member 3, the cam surface 10 and the cam receiving portion 15 are pressed against each other from the axial direction of the bolt 1 in the screwed state.

As described above, the cam surface 10 is formed so that the height of the cylindrical portion 7 gradually increases as it goes counterclockwise along the circumferential direction. At the time of loosening, the cam receiving portion 15 is
In the axial direction (upward in FIG. 3). The axial movement distance of the cam receiving portion 15 guided by the cam surface 10 is as follows.
The shape of the cam surface 10 is set so as to be larger than the relative axial movement distance between the bolt 1 and the female screw member 3 corresponding to the lead of the male screw 1b of the bolt 1 and the female screw 3a of the female screw member 3. I have.

According to the above configuration, the bolt 1 and the female screw member 3 are screwed together, and the washer 6 is elastically compressed and deformed via the pressing portion 5 so that the washer 6 is attached to the mounting member 4 on the female screw member 3 side. When the screw is loosened, the screw can be rotatably driven. When the bolt 1 and the female screw member 3 rotate relative to each other in the loosening direction, the cam surface 10 formed on the washer 6 rotates together with the female screw member 3 and the cam receiving portion 15 formed on the pressing portion 5 rotates with the bolt 1. I do. As a result, the cam surface 10 and the cam receiving portion 15 rotate relative to each other.
0 guides the cam receiving portion 15 in the axial direction of the bolt 1. The axial movement distance of the cam receiving portion 15 guided by the cam surface 10 is larger than the relative axial movement distance of the bolt 1 and the female screw member 3 corresponding to the leads of the male screw 1b and the female screw 3a. The surface 10 and the cam receiving portion 15 are bolts 1
Since the bolt 1 and the female screw member 3 are pressed against each other from the axial direction of the bolt 1 in the screwed state, an axial tensile force acts on the screwed portion of the bolt 1 and the female screw member 3. The relative rotation of the bolt 1 and the female screw member 3 in the loosening direction can be prevented by the axial force. The loosening can be prevented only by providing the pressing portion 5 and the washer 6.

It is to be noted that, instead of the bolt 1 in the above embodiment, a bolt 20 with a hexagonal hole 20 'of the second embodiment as shown in FIGS. 4A and 4B may be used as a male screw member. Good. In this case, the head 20a of the bolt 20
A pair of inclined surfaces 2 inclined with respect to the axial direction of the male screw 20b
By providing “0” so as to be able to abut on the groove 5 a of the pressing portion 5, it is possible to rotate together with the pressing portion 5.

Further, instead of the bolt 1 and the pressing portion 5 in the above embodiment, a bolt 30 with hexagonal holes 30 'of the third embodiment as shown in FIG. 5 may be used. In this case, a pressing portion 5 ′ in which a cam receiving portion 15 similar to the above embodiment is formed is integrally formed on the head 30 a of the bolt 30.

In the above embodiment, the bolt 1 with the head 1a is shown as the male screw member, and the structural member having the female screw 3a is shown as the female screw member 3, but as shown in the fourth embodiment in FIG. The present invention can be applied to a case where a nut 41 is screwed as a female screw member to a structural member 40 having a stud bolt 40a as a male screw member. In this case, the pressing portion 5 rotates together with the nut 41, and the washer 6 can bite into the mounting member 4 on the male screw member 40 side so as not to rotate relatively when the screw is loosened. Other parts are the same as those of the above embodiment, and the same parts are denoted by the same reference numerals.

The screw loosening prevention device of the fifth embodiment shown in (1), (2), (3) of FIG. 7 and (1), (2) of FIG. 8 is similar to the first embodiment. Bolt (male screw member) 1
When the mounting member 4 is fixed to the female screw member 3 exemplified by the structural member having the female screw 3a, relative loosening between the bolt 1 and the female screw member 3 is prevented.

The bolt 1 has a head portion 1a whose outer periphery follows a hexagon and a male screw 1b. The mounting member 4 has a through hole 4a for the male screw 1b. The male screw 1b and the female screw 3a are right-handed screws in the present embodiment. The male screw 1b is inserted through a pair of washers 50 and 51.

The washers 50 and 51 are spring washers having the same size and having split grooves, and are joined to each other by being juxtaposed in the axial direction. One washer 50 is joined to the head 1a of the bolt 1, and is arranged so that its thickness gradually increases as it advances clockwise along the circumferential direction. The other washer 51 is joined to the mounting member 4 and is arranged so that its thickness gradually increases as it advances counterclockwise along the circumferential direction.

The other washer 51 has one end surface in the axial direction serving as the cam surface 10 to be joined to one washer 50, and one end surface in the circumferential direction of the portion having the largest thickness is the joining surface 1.
The intersection between the joint surface 11 and the other end surface in the axial direction is a bite portion 12. Accordingly, when the other washer 51 is sandwiched between the head 1a of the bolt 1 and the female screw member 3 via the one washer 50 and the mounting member 4, it is elastically compressed and deformed in the axial direction. Due to the elasticity based on the deformation, the biting portion 12 bites into the mounting member 4 on the female screw member 3 side so as to rotate relatively when tightening the screw and not to rotate relatively when loosening the screw. By this biting, the cam surface 10
Are rotatable relative to the bolt 1 along with the female screw member 3 in the screwed state in the loosening direction of the screwing.

One of the washers 50 has a cam surface 1 whose other end in the axial direction faces one end of the other washer 51.
The cam receiving portion 15 can be joined to the joint surface 11 and one end in the circumferential direction of a portion having the largest thickness is a joining surface 16 that can be joined to the joining surface 11. The intersection of is a biting portion 72. Thereby, when one washer 50 is sandwiched between the head 1a of the bolt 1 and the female screw member 3 via the other washer 51 and the mounting member 4, it is elastically compressed and deformed in the axial direction. Due to the elasticity based on the deformation, the biting portion 72 bites into the head 1a of the bolt 1 so as to rotate relatively when tightening the screw, but not to rotate when loosening the screw. By this biting, the cam receiving portion 15 is rotatable relative to the female screw member 3 along with the bolt 1 in the screwed state in the loosening direction of the screwing. When the bolt 1 is screwed into the female screw member 3, the cam surface 10 and the cam receiving portion 15 are pressed against each other from the axial direction of the bolt 1 in the screwed state.

As described above, the cam surface 10 is constituted by one end surface of the other washer 51 whose thickness gradually increases as it advances counterclockwise along the circumferential direction.
When the bolt 1 and the female screw member 3 are loosened, the cam receiving portion 15 is guided in the axial direction of the bolt 1. The axial movement distance of the cam receiving portion 15 guided by the cam surface 10 is as follows.
The shape of the cam surface 10 is set so as to be larger than the relative axial movement distance between the bolt 1 and the female screw member 3 corresponding to the lead of the male screw 1b of the bolt 1 and the female screw 3a of the female screw member 3. I have.

According to the above configuration, one washer 50 can be inserted into the bolt 1 and the other washer 51 can be inserted into the mounting member 4 on the female screw member 3 side. Since the cam surface 10 is formed on the other washer 51 and the cam receiving portion 15 is formed on one of the washers 50, the cam surface 10 and the bolt 1 are carried together when the screw is loosened. Rotate. As a result, the cam surface 10 and the cam receiving portion 15 rotate relative to each other.
0 guides the cam receiving portion 15 in the axial direction of the bolt 1. The axial movement distance of the cam receiving portion 15 guided by the cam surface 10 is larger than the relative axial movement distance of the bolt 1 and the female screw member 3 corresponding to the leads of the male screw 1b and the female screw 3a. The surface 10 and the cam receiving portion 15 are bolts 1
Since the bolt 1 and the female screw member 3 are pressed against each other from the axial direction of the bolt 1 in the screwed state, an axial force acts on the screwed portion of the bolt 1 and the female screw member 3. The relative rotation of the bolt 1 and the female screw member 3 in the loosening direction can be prevented by the axial force. Further, the loosening can be prevented only by providing the pair of washers 50 and 51.

Each washer 5 in the fifth embodiment is described.
Instead of 0 and 51, as shown in the sixth embodiment of FIGS. 9 (1) and 9 (2), washers 50 and 51 in which a part of the axial end surface is a concave curved surface 58 are used, and the concave curved surfaces thereof are used. The biting portions 12, 72 may be constituted by 58 and the joining surfaces 11, 16. Other configurations are the same as those of the fifth embodiment, and the same portions are denoted by the same reference numerals.

In the above embodiment, one of the female screw member 3 and the male screw member 40 does not rotate itself as a structural member, and only the other rotates to cause loosening. However, as shown in the seventh embodiment of FIG. 10 and the eighth embodiment of FIG. 11, the male screw member is a bolt 1 and the female screw member 3 ′ is a nut, and both are loosened by rotating themselves. In this case, the locking may be performed by using two sets of the locking device of the present invention. In this case, two members 4 are formed by the bolt 1 and the nut 3 '.
Insert 4 '. Other configurations of the seventh embodiment are the same as those of the first embodiment, and other configurations of the eighth embodiment are the same as those of the fifth embodiment, and the same portions are denoted by the same reference numerals.

The screw loosening prevention device according to the ninth embodiment shown in FIGS. 12A and 12B includes a bolt (male screw member) 10.
When the two plate-like members 103 and 104 are connected by the nut 1 and the nut (female screw member) 102, the bolt 101 and the nut 102 are prevented from being relatively loosened. The bolt 101 and the nut 102 are right-handed threads in the present embodiment.

The bolt 101 has a head portion 101 ′ having an outer periphery along a hexagon and a male screw 101 ″, and the male screw 101 ″ is inserted into the stupid holes of the plate members 103 and 104. The male screw 101 ″ is inserted into a washer 106. The washer 106 is screwed into a nut 102 so that the plate-like members 103 and 104 are formed.
Is sandwiched between the bolt 101 and the nut 102.

The thickness of the washer 106 gradually decreases from one end in the radial direction to the other end (from left to right in the drawing). A maximum thickness t1 at one end of the washer 106 and a minimum thickness t2 at the other end.
The difference is that the thread 101a of the bolt 101 is pressed against the thread groove 102a of the nut 102 at one end in the radial direction (left side in FIG. 2) and one end in the axial direction (lower side in FIG. 2). On the end side, it is set so that it can be pressed against the other end in the axial direction. That is, the difference between the maximum thickness t1 and the minimum thickness t2 is determined by the thread 101a of the bolt 101.
The clearance between the nut and the thread groove 102a of the nut 102 is made larger than the axial dimension of the clearance, and preferably, the difference in thickness is 1.5 times or more the axial dimension of the clearance.

According to this configuration, when the bolt 101 is screwed into the nut 102, the washer 106 becomes thinner gradually from one end in the radial direction to the other end, so that a force for bending the bolt 101 acts. . With this force, the thread 101a of the bolt 101 is pressed against the thread groove 102a of the nut 102 at one end in the radial direction toward one end in the axial direction, and at the other end in the radial direction against the other end in the axial direction. And the nut 102 can be prevented from loosening. Further, as shown in FIG. 12 (3), even if the screw thread and the screw groove are eliminated from the bolt 101 and the nut 102, when the axial force F acts on the bolt 101,
The inner peripheral end portion 102c of the nut 102 is pressed against the bolt 101 from the radial direction, so that its axial displacement can be prevented. Accordingly, this configuration is suitable for use in a structure in which an axial force acts on a bolt or a nut. For example, in a lifting device or a pulling device,
It is suitable for use when a member on which the lifting force or the pulling force acts is connected to another member by a screw.

FIGS. 13A and 13B show a tenth embodiment. The difference from the ninth embodiment is that the washer 1
The point that a spring washer 111 is used in place of 06. Thereby, the nut 1 of the bolt 101
02, the screw 101a of the bolt 101 is also formed by elasticity based on the axial deformation of the washer 111 caused by screwing into the screw 101.
Can be pressed against the thread groove 102a of the nut 102. Further, the thickness of the washer 111 is
2 is the thickest in the formation part. This allows
The washer 111 can bite into the nut 102 and the one plate-like member 103 on the bolt 101 side so as not to rotate relative to each other when loosening the screw. That is, the washer 111 is provided on one of the plate-like members 103 on the bolt 101 side so that the axial one ends 111a and 111b of the respective opposite ends in the formation portion of the split groove 112 do not rotate relative to each other when the screwing is loosened. Bite into. Thereby, loosening of the bolt 101 and the nut 102 can be reliably prevented. The bolt 101 is connected to the nut 102
When screwing into the nut, the other ends 111 c and 111 d of the opposite ends in the formation portion of the split groove 112 do not bite into the nut 102 and the plate-like member 103.
c and 111d are chamfered portions. Note that a convex curved surface may be used instead of the chamfered portion. Other parts are the same as those of the above embodiment, and the same parts are denoted by the same reference numerals.

FIGS. 14A and 14B show an eleventh embodiment. The difference from the tenth embodiment is that the spring washer 111 has portions 111a and 111b that bite into the nut 102 and the plate member 103 when the screw is loosened.
As shown by the arrow p in the drawing, the notch 120 is formed so as to be deformed along the circumferential direction by the reaction force of the bite. Thereby, the washer 121
The axial end portions 111a and 111b of the respective opposing ends in the portion where the split groove 112 is formed are more reliably fixed to the nut 102 and the plate-like member 103 by the stress that is going to oppose the deformation.
Can be digged into. Other parts are the same as those of the above embodiment, and the same parts are denoted by the same reference numerals.

[0035]

According to the present invention, relative loosening of the male screw member and the female screw member screwed together can be reliably prevented even when the lock nut cannot be used.

[Brief description of the drawings]

FIG. 1 is a perspective view for explaining the configuration of a screw loosening prevention device according to a first embodiment of the present invention.

FIG. 2 is a side view of the screw loosening prevention device according to the first embodiment of the present invention before screw adjustment.

FIG. 3 is a side view of the screw loosening prevention device according to the first embodiment of the present invention in a state after screwing;

FIG. 4 is a perspective view of a bolt of a screw loosening prevention device according to a second embodiment of the present invention, and FIG.

FIG. 5 is a perspective view of a bolt of a screw loosening prevention device according to a third embodiment of the present invention.

FIG. 6 is a side view of a screw loosening prevention device according to a fourth embodiment of the present invention.

FIG. 7 is a side view for explaining a configuration of a screw loosening prevention device according to a fifth embodiment of the present invention, (2) is a side view in a screwed state, and (3) is both washers in a screwed state. Development diagram of

FIG. 8 is a perspective view of a washer of a device for preventing loosening of a screw according to a fifth embodiment of the present invention, and FIG.

9A and 9B are side views of a screw loosening prevention device according to a sixth embodiment of the present invention, and FIG. 9B is a development view of both washers in a screwed state.

FIG. 10 is a side view of a screw loosening prevention device according to a seventh embodiment of the present invention.

FIG. 11 is a side view of a screw loosening prevention device according to an eighth embodiment of the present invention.

FIG. 12 is a cross-sectional view for explaining the configuration of a screw loosening prevention device according to a ninth embodiment of the present invention, (2) is a perspective view of a nut, and (3) is an operation explanatory view.

FIG. 13 is a perspective view of a nut and (2) is a partial side view of a screw loosening prevention device according to a tenth embodiment of the present invention.

FIG. 14 is a perspective view of a nut, and (2) is a partial side view of a screw loosening prevention device according to an eleventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 101 Bolt (male screw member) 3 Female screw member 5 Pressing part 6 Washer 10 Cam surface 15 Cam receiving part 50, 51, 106, 111, 121 Washer 102 Nut

Claims (6)

(57) [Claims] 1. A device for preventing relative loosening between a male screw member and a female screw member to be screwed together, wherein one of the two screw members in the screwed state accompanies the screwing loosening direction. And a cam surface rotatable relative to the other, a screw member in the screwed state, and a cam receiving portion accompany in the loosening direction of the screw screw and rotatable relative to the other. The cam surface and the cam receiving portion are pressed against each other from the axial direction of the male screw member when the two screw members are screwed together. The axial movement distance of the cam receiving portion by the guidance of the cam surface is larger than the relative axial movement distance corresponding to the leads of both screw members. Anti-loose device . 2. A pressing portion rotatable with one of the male screw member and the female screw member, and a washer through which the male screw member is inserted, wherein one of the pressing portion and the washer is provided on one of the washer and the washer. A cam surface is formed, and the other cam receiving portion is formed. The washer is elastically compressively deformable in the axial direction by being sandwiched between the male screw member and the female screw member via a pressing portion. The screw according to claim 1, wherein the elasticity based on the deformation allows the screw to bite into the other side of the male screw member and the female screw member so as not to rotate relative to each other when the screwing is loosened. Loosening prevention device. 3. A pair of washers into which the male screw member is inserted, wherein the cam surface is formed on one of the washers and the cam receiving portion is formed on the other, and each washer is provided with the male screw member. A spring washer that can be elastically deformed in the axial direction by being sandwiched between the female screw member and one of the washers is relatively rotated by the elastic force based on the deformation when the screw is loosened toward the male screw member. The looseness of the screw according to claim 1, wherein the other washer is configured to be able to bite so as not to rotate relative to the female screw member side when the screwing is loosened by an elastic force based on the deformation of the other washer. Prevention device. 4. An apparatus for preventing relative loosening between a male screw member and a female screw member screwed to each other, wherein the male screw member is inserted and the male screw member and the female screw member are connected to each other. The thickness of the washer is gradually reduced from one radial end to the other end, and the difference between the thickness of one end of the washer and the thickness of the other end is determined by the male screw. A loosening prevention device for a screw, wherein a thread of a member is pressed against a thread groove of a female screw member at one end in a radial direction toward one end in an axial direction, and at another end in a radial direction, is pressed against the other end in an axial direction. 5. The washer is formed as a spring washer, and the thickness of the washer is set to be the thickest at the split groove forming portion so that the washer can bite into each screw member side so as not to rotate relative to each other when the screw is loosened. 5. The screw loosening prevention device according to claim 4, wherein: 6. The screw according to claim 5, wherein a notch is formed in the washer so that a portion that bites into each screw member side when the screw is loosened is deformed in a circumferential direction by a reaction force of the biting. Loosening prevention device.