JP2014105862A - Reverse rotation preventive structure of screw body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reverse rotation preventive structure of a screw body which reliably prevents rotation in a specified direction of the screw body with a simple structure.SOLUTION: A reverse rotation preventive structure is a structure which fastens a member 80 to be fastened by means of a male screw body 10 and a washer 50, a screw body side seating part 22 is formed on the male screw body 10, a first reception part 60 and a second reception part 70 are formed on the washer 50 side, and a member side seating part 82 is formed on the member 80 to be fastened. A first engagement mechanism A is formed between the first reception 60 and the screw body side seating part 22, when at least the screw body side seating part 22 starts to rotate in the direction of relaxing the male screw body 10 in the fastened state, the first reception part 60 and the screw body side seating part 22 are engaged with each other to prevent relative rotation of them, a second engagement mechanism B is formed between the member side seating part 82 and the second reception part 70 and, when at least the washer 50 starts to rotate in the direction of relaxing the washer 50, the first reception part 70 and the member side seating part 82 are engaged with each other to prevent relative rotation of them and relaxation of the male screw body 10 and the member 80 to be fastened is prevented by the action of the first engagement mechanism A and the second engagement mechanism B.

Description

  The present invention relates to a reverse rotation prevention structure for preventing reverse rotation of a fastened screw body.

  Conventionally, in various scenes, a screw body is used to fasten an object to be fastened. This screw body has a structure in which a male screw body in which a spiral groove is formed on a columnar outer periphery and a female screw body in which a spiral groove is formed on the inner periphery of a cylindrical member are screwed together.

  At the time of use, after inserting a male screw body into the hole formed in a to-be-fastened member, a female screw body is screwed together. As a result, the fastened object is sandwiched between the head of the male screw body and the cylindrical member of the female screw body. What is devised so that such a screw body for fastening can be used easily is a so-called bolt formed by forming a hexagonal column head at one end of the male screw member, and an outer peripheral surface formed in a hexagonal column shape. There are some combinations of nuts. In addition, a so-called small screw having a head portion that is not hexagonal and has a slit (minus hole) or a cross hole (plus hole) formed on the end face is also widely used.

  In addition, a washer (washer) is inserted around the male screw body when the screw body is fastened. This washer protects the object to be fastened from buckling or scratches at the time of fastening, and conversely suppresses loosening of the screw body by positively pressing the object to be fastened.

  For example, the washer has a general ring-shaped “flat washer” and a protrusion extending in the radial direction on the inner periphery and outer periphery, and is engaged with a member to be fastened or a screw body to prevent loosening. `` Washer with hook '', `` Washer with claw '' in which short claws bent in the axial direction engage with the object to be fastened, `` Spring washer '' to prevent loosening of the screw body by elastic deformation, teeth around the fastening surface There is a “toothed washer” and so on.

Japanese Industrial Standard JIS 1251 Spring Washer

  However, the conventional washer has a degree of expectation of friction and biting with respect to the structure for preventing loosening between the screw body, and the effect thereof is insufficient as well known. Therefore, in an environment where vibrations and the like are severe, there is a problem that even if a washer is used, the screw body gradually loosens.

  The present invention has been made by the inventor's diligent research in view of the above-mentioned problems, and by using a washer effectively, it has a simple structure and highly prevents reverse rotation of the screw body, that is, prevents loosening. It is an object of the present invention to provide a structure for preventing looseness of a screw body that performs the above.

  That is, the present invention for achieving the above object has a screw body having a screw thread, a washer, and a screwed member fastened by the screw body and the washer, and the screw body is on the screw body side facing the washer. The washer includes a first receiving part facing the screw body side seat part and a second receiving part facing the fastened member, and the fastened member includes the first fastened part. Even if a rotational force in the loosening direction acts on the screw body side seat portion between the screw body side seat portion and the first receiving portion, the member side seat portion is opposed to the second receiving portion. A first engagement mechanism that maintains a state of being engaged with each other is configured, and a rotational force in the loosening direction acts on the washer between the member side seat portion and the second receiving portion. A second engagement mechanism that maintains a state of being engaged with each other is configured, and the screw body of the fastening body is Directed, ie, causing reverse rotation, for example, a reverse rotation preventing structure of the screw body, characterized in that to prevent the rotating direction of loosening the screw member.

  In relation to the reverse rotation prevention structure of the screw body, the first engagement mechanism includes a screw body side uneven portion formed on the screw body side seat portion and an engagement with the screw body side uneven portion on the first receiving portion. A first receiving portion side unevenness is formed to obtain the engagement state.

  In relation to the reverse rotation prevention structure of the screw body, the screw body side unevenness is a saw blade shape provided in the circumferential direction.

  In relation to the reverse rotation prevention structure of the screw body, the screw body side unevenness is a mountain shape or a wave shape provided in the circumferential direction.

    In relation to the reverse rotation prevention structure of the screw body, the screw body side unevenness is an embossed shape.

  In relation to the reverse rotation prevention structure of the screw body, the screw body side unevenness is a spiral groove or mountain.

  In relation to the reverse rotation prevention structure of the screw body, the first receiving portion side unevenness is a saw blade shape provided in the circumferential direction.

  In relation to the reverse rotation prevention structure of the screw body, the first receiving-side unevenness is a mountain shape or a wave shape provided in the circumferential direction.

  In relation to the reverse rotation prevention structure of the screw body, the first receiving-side unevenness is an embossed shape.

  In relation to the reverse rotation prevention structure of the screw body, the first receiving side unevenness is a spiral groove or mountain.

  In relation to the reverse rotation prevention structure of the screw body, the screw body side seat portion is formed with a screw body side tapered surface inclined in the radial direction.

  In relation to the reverse rotation preventing structure of the screw body, the first receiving portion is formed with a washer-side tapered surface inclined in the radial direction.

  In relation to the reverse rotation prevention structure of the screw body, the first engagement mechanism is configured such that the engagement strength in the loosening direction increases as the distance between the screw body side seat portion and the first receiving portion decreases. It is characterized by being.

  In relation to the reverse rotation prevention structure of the screw body, the first engagement mechanism allows relative rotation in the tightening direction of the screw body side seat portion between the screw body side seat portion and the first receiving portion. It is characterized by that.

  In connection with the reverse rotation prevention structure of the screw body, the washer is elastically deformable in the axial direction of the screw body.

  In relation to the reverse rotation prevention structure of the screw body, the member side seat portion includes an accommodation recess capable of accommodating the second receiving portion.

  In relation to the reverse rotation prevention structure of the screw body, the second engagement mechanism obtains the engagement state by fitting the second receiving portion and the receiving recess.

  In relation to the reverse rotation prevention structure of the screw body, the inner wall of the housing recess varies in the distance from the axis of the screw body along the circumferential direction, and the outer wall of the second receiving portion is the screw body. The distance from the axis of fluctuates along the circumferential direction.

  In relation to the structure for preventing reverse rotation of the screw body, the inner wall of the housing recess and the outer wall of the second receiving portion have a circular shape eccentric with respect to the axis of the screw body.

  In relation to the reverse rotation prevention structure of the screw body, the member side seat portion has a member side step portion stepped in the axial direction of the screw body, and the second receiving portion includes the member side step portion. A washer-side step portion that engages with the portion is formed.

  According to the present invention, the screw body can be reliably prevented from loosening by preventing the screw body from rotating backward, for example, by preventing the screw body from rotating in the direction in which the screw body is loosened. Become.

It is a side surface fragmentary sectional view which shows the reverse rotation prevention structure of the screw body of 1st embodiment of this invention. It is the side surface fragmentary sectional view and bottom view of the external thread body used with the reverse rotation prevention structure. It is the top view and side surface fragmentary sectional view of a washer used with the reverse rotation prevention structure. (A) is a conceptual diagram which shows the effect | action of the saw blade of the reverse rotation prevention structure of the screw body, (B)-(D) is a conceptual diagram which shows the modification of a saw blade. (A)-(C) are the conceptual diagrams which show the modification of the saw blade of the reverse rotation prevention structure. (A) (B) is a side view, without tightening the application example of the external thread body of the reverse rotation prevention structure. (A) and (B) are the top views and side surface fragmentary sectional views of the washer used by the application example of the reverse rotation prevention structure. It is the top view and side surface fragmentary sectional view which show the fastening state of the reverse rotation prevention structure of the screw body which concerns on 2nd embodiment. (A) is the top view and side surface fragmentary sectional view of a washer used by the reverse rotation prevention structure, (B) is a side surface fragmentary sectional view which shows the open | release operation | work of the reverse rotation prevention structure. (A) is a side fragmentary sectional view showing the opening operation of the washer used in the application example of the reverse rotation prevention structure, and (B) is a top view and side surface partial cross section showing the opening operation of the washer used in the application example. FIG. (A) Top view and side partial sectional view of washer, (B) Side partial sectional view showing a state in which the washer and male threaded body are integrated, (C) FIG. 4 is a side sectional view showing a fastening state. It is the upper side figure and side surface fragmentary sectional view of a washer used by the application example of the reverse rotation prevention structure. (A) The top view and side surface fragmentary sectional view of a washer, (B) The side surface fragmentary sectional view which shows the fastening state of the reverse rotation prevention structure of the screw body which concerns on 4th embodiment. It is the (A) top view and (B) side surface fragmentary sectional view which show the fastening state of the reverse rotation prevention structure of the screw body which concerns on the application example of 1st to 4th embodiment. It is a side surface fragmentary sectional view which shows the fastening state at the time of applying the reverse rotation prevention structure of the screw body of this invention to an internal thread body.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a reverse rotation prevention structure for a screw body according to the first embodiment. As shown in FIG. 3, the reverse rotation prevention structure of the screw body includes the male screw body 10, an annular washer 50, a fastened member 80, and a base 90. A female screw hole 92 for screwing with the male screw body 10 is formed in the base 90, and the fastened member 80 is fixed by being sandwiched between the base 90 and the male screw body 10.

  The male screw body 10 is a so-called bolt and has a head portion 20 and a shaft portion 30. A screw body side seat portion 22 is formed at a portion corresponding to a lower portion or a root of the head 20. The shaft portion 30 is formed with a cylindrical portion 30a and a screw portion 30b. Of course, the cylindrical portion 30a is not essential.

  A first receiving portion 60 is formed on one side of the washer 50 (upper surface side in FIG. 1). The first receiving portion 60 faces the screw body side seat portion 22, and a first engagement mechanism A is configured between the two. In the first engagement mechanism A, when at least the screw body side seat portion 22 tries to rotate in the direction of loosening the male screw body 10 in the fastened state, the first receiving portion 60 and the screw body side seat portion 22 engage with each other, Relative rotation between the first receiving portion 60 and the screw body side seat portion 22 with respect to the rotation direction is prevented.

  A second receiving portion 70 is formed on the other side (the lower surface side in FIG. 1) of the washer 50. The first receiving part 70 faces the fastened member 80.

  In the fastened member 80, a member side seat portion 82 that faces the second receiving portion 70 of the washer 50 is formed. A second engagement mechanism B is configured between the member side seat portion 82 of the fastened member 80 and the second receiving portion 70 of the washer 50. In the second engagement mechanism B, when at least the washer 50 rotates together with the male screw body 10 in the loosening direction, the first receiving portion 70 and the member side seat portion 82 engage with each other, and the second engagement mechanism B Relative rotation between the two receiving portions 70 and the member side seat portion 82 is prevented.

  When the male screw body 10 tries to rotate in the loosening direction by the action of the first engagement mechanism A and the second engagement mechanism B, the relative rotation of the male screw body 10 and the fastened member 80 is restricted by the interposition of the washer 50. The As a result, the male screw body 10 is prevented from loosening.

  As shown in FIG. 2, as the first engagement mechanism A, the screw body side uneven portion 24 is formed on the screw body side seat portion 22 of the male screw body 10. The screw body side unevenness 24 has a saw blade shape that is continuously provided in the circumferential direction. The direction in which each of the screw body side irregularities 24 extends, that is, the direction in which the ridge line extends is the radial direction of the male screw body 10. As a result, the screw body side unevenness 24 extends radially from the axis.

  Further, the threaded body side seat portion 22 is formed with a threaded body side tapered surface 26 inclined in the radial direction. The screw body-side tapered surface 26 is inclined so that the center side approaches the screw tip, and as a result, has a conical shape convex to the screw tip side. More preferably, the aforementioned threaded body side unevenness 24 is formed on the threaded body side tapered surface 26.

  As shown in FIG. 3, as the first engagement mechanism A, the first receiving portion 60 of the washer 50 is formed with a first receiving portion side unevenness 64 that engages with the screw body side unevenness 24. The 1st receiving part side unevenness | corrugation 64 becomes the saw blade shape provided in multiple numbers by the circumferential direction continuously. The direction in which each of the first receiving portion side irregularities 64 extends, that is, the direction in which the ridge line extends, is along the radial direction of the male screw body 10. As a result, the first receiving portion side unevenness 64 extends radially from the center of the through hole 52 of the washer 50.

  Further, preferably, the first receiving portion 60 is formed with a washer-side tapered surface 66 inclined in the radial direction. The washer-side tapered surface 66 has a mortar shape that is inclined so that the center side approaches the screw tip. As a result, a concave conical shape is formed on the screw tip side. On the washer-side tapered surface 66, the above-described first receiving portion-side irregularities 64 are formed.

  As a result, when the male screw body 10 is tightened, in the first engagement mechanism A, the screw body side tapered surface 26 of the screw body side seat portion 22 enters the recess of the washer side tapered surface 66 of the washer 50, and the screw body side unevenness 24. And the first receiving portion side unevenness 64 are engaged. As shown in FIG. 4 (A), when the male screw body 20 tries to rotate in the fastening direction Y, the inclined surfaces 24Y and 64Y come into contact with each other, and the distance between them is set in the axial direction. Allow relative sliding while separating. On the other hand, when the male screw body 20 tries to rotate in the loosening direction X, the vertical surfaces (surfaces with a strong inclination) 24X and 64X come into contact with each other to prevent relative movement between the two. In particular, in the first engagement mechanism A, as the distance between the screw body side seat portion 22 and the first receiving portion 60 decreases by tightening the male screw body 10, the engagement between the screw body side unevenness 24 and the first receiving portion side unevenness 64 becomes stronger. Thus, the engagement strength on the loosening direction X side is increased. Here, the inclination angle of the screw body side taper surface 26 and the inclination angle of the washer side taper surface 66 are made different from each other. In particular, the inclination angle from the axis of the washer side taper surface 66 is set to the axis of the screw body side taper surface 26. By setting it to be narrower than the inclination angle from, it is possible to tighten without rattling regardless of the pitch of the sawtooth formed on each tapered surface.

  Returning to FIG. 3, the distance from the axial center of the screw of the outer wall 72 of the second receiving portion 70 of the washer 50 varies along the circumferential direction. Specifically, the outer wall 72 has a circular shape that is eccentric with respect to the axis of the screw (the center of the through hole 52).

  On the other hand, the member side seat portion 82 of the fastened member 80 is provided with a housing recess 84 for housing the second receiving portion 70 of the washer 50, and the inner wall of the housing recess 84 is also formed on the axis of the screw. On the other hand, it has an eccentric circular shape. The amount of eccentricity is the same for the second receiving portion 70 and the accommodating recess 84, and the difference in diameter (margin gap) between the second receiving portion 70 and the accommodating recess 84 is set smaller than the amount of eccentricity.

  Therefore, as shown in FIG. 1, when the second receiving portion 70 of the washer 50 is received in the receiving recess 84 of the fastened member 80, the two fit together, and the screw shafts are aligned. As it is, relative rotation in the circumferential direction of both is restricted. That is, the second receiving portion 70 and the accommodating recess 84 act as the second engagement mechanism B.

  As mentioned above, according to the reverse rotation prevention structure of the screw body of the first embodiment, the first engagement mechanism A is configured between the screw body side seat portion 22 and the first receiving portion 60 by interposing the washer 50. When the second engagement mechanism B is configured between the member side seat portion 82 and the second receiving portion 70 and the male screw body 10 is about to be loosened, both the first engagement mechanism A and the second engagement mechanism B are restricted. By the action, the male screw body 10 is engaged with the fastened member 80 in the circumferential direction, and the reverse rotation, that is, the loosening is prevented. Therefore, even if vibration etc. arise, the fastening state which does not loosen at all can be obtained.

  Further, in the present embodiment, as the first engagement mechanism A, the screw body side unevenness 24 and the first receiving portion side unevenness 64 are formed in a saw blade shape in which a plurality of continuous in the circumferential direction, and as a so-called ratchet mechanism or one-way clutch mechanism Works. As a result, during the fastening operation, the screw body side unevenness 24 and the first receiving portion side unevenness 64 are allowed to move relative to each other to realize smooth relative rotation, while during the loosening operation, the screw body side unevenness 24 and the first receiving portion. The relative movement of the side irregularities 64 is completely restricted. As a result, workability at the time of fastening and subsequent locking can be rationally achieved.

  In the first embodiment, as the first engagement mechanism A, the screw body side seat portion 22 and the first receiving portion 60 are formed with the screw body side taper surface 26 and the washer side taper surface 66. The contact area can be increased. Further, the fastening force in the axial direction of the male screw body 10 also acts in the radial direction by the tapered surface. By pressing the taper surfaces of each other in the radial direction, centering can be carried out by self-excitation. As a result, the concentricity of the male screw body 10 and the washer 50 is increased, and the engagement accuracy between the screw body side unevenness 24 and the first receiving portion side unevenness 64 can be increased. It is also preferable to slightly increase the inclination of the convex screw body side tapered surface 26 and slightly decrease the inclination angle of the concave washer side tapered surface 66 so as to provide a small difference in angle. If it does in this way, a mutual taper surface can be made to contact | abut little by little toward the radial direction outer side from the center with the increase in clamping pressure.

  Furthermore, in the first embodiment, as the second engagement mechanism B, the shape of the outer wall of the second receiving portion 70 of the washer 50 and the inner wall of the accommodating recess 84 of the fastened member 80 is different from the axial center of the screw. To avoid concentric circles. In other words, the distance from the axial center of the screw of the inner wall of the housing recess 84 and the outer wall of the second receiving portion 70 changes along the circumferential direction. With this shape, when the inner wall of the housing recess 84 and the second receiving portion 70 are fitted, the relative rotation in the circumferential direction is restricted while keeping the axial centers thereof aligned. In particular, here, since it has an eccentric circular shape, it is possible to prevent relative rotation between the two while making the shape processing of the washer 50 and the fastened member 80 extremely simple.

  In the first embodiment, the case where the screw body side unevenness 24 and the first receiving portion side unevenness 64 have a saw blade shape is illustrated as the first engagement mechanism A, but the present invention is not limited to this. For example, as shown in FIG. 4B, the unevenness of each other can be a mountain shape (both are inclined surfaces). In this manner, when the male screw body 20 rotates in the loosening direction X, the inclined surfaces 24X and 64X tend to move relative to each other. The screw body side unevenness 24 and the first receiving portion side unevenness are along the inclined surface. 64 tries to leave. If this moving distance (separation angle α) is set larger than the lead angle of the male screw body 10, even if the male screw body 10 tries to loosen, the screw body side unevenness 24 and the first receiving part side unevenness 64 are more likely to be separated from each other. You will not be able to relax. In FIG. 4B, the irregularity of the isosceles triangle is illustrated. However, as shown in FIG. 4C, the angle of the inclined surfaces 24Y and 64Y that are in contact with each other at the time of fastening rotation is smaller than that at the time of loose rotation. It is also preferable to make the inclination angles of the inclined surfaces 24X and 64X in contact with each other gentle. In this way, the circumferential distance P between the inclined surfaces 24Y and 64Y that must be overcome during fastening rotation can be shortened, so that looseness (gap) after fastening can be reduced.

  Moreover, as an application of FIGS. 4A to 4C, as shown in FIG. 4D, corrugated irregularities with curved ridges and valleys are also preferable. Smooth operability can be obtained during fastening. Furthermore, in the first embodiment, the unevenness extending in the radial direction is illustrated, but it is also preferable to form a spiral (spiral) groove or mountain (unevenness) as shown in FIG. Further, as shown in FIG. 5B, even a groove or mountain (unevenness) extending linearly can be inclined so that the circumferential phase changes with respect to the radial direction of the screw. Further, as shown in FIG. 5C, it is also preferable to adopt a so-called embossed shape in which a plurality of fine irregularities are formed both in the circumferential direction and the radial direction (planar shape) of the screw.

  Further, unlike the first embodiment, the uneven shapes of the screw body side unevenness 24 and the first receiving portion side unevenness 64 are not necessarily matched (similar). For example, different shapes from the various shapes in FIGS. 4 and 5 can be selected and combined with each other.

  In the first embodiment, the case where the screw body side tapered surface 26 is convex and the washer side tapered surface 66 is concave is illustrated, but the present invention is not limited thereto. For example, as shown in FIG. 6 (A), the threaded body side tapered surface 26 can be formed into a planar shape, or can be formed into a concave shape as shown in FIG. 6 (B). The same applies to the washer-side tapered surface. Although not particularly illustrated, for example, if the elastic deformation of the washer 50 is effectively used, it is not necessary to match the inclination angles of the two tapered surfaces. Of course, a tapered surface may be formed on only one of the male screw body 10 or the washer 50. Furthermore, by making both the tapered surfaces convex or concave, the elastic deformation of the washer can be utilized to bring them into close contact. Further, in order to obtain the elasticity of the washer 50, it is preferable to use a so-called spring washer shape in which the basic shape of the washer 50 is a spiral shape.

  Furthermore, as an application of the first embodiment, as shown in FIG. 7A, the outer wall of the second receiving portion 70 of the washer 50 and the inner wall of the housing recess 84 of the member-side pedestal portion 82 are the axial center of the screw. On the other hand, a concentric partial arc shape S can be used, and the rest can be cut into a straight line like the chord G. That is, also in this case, the distance from the axial center of the screw of the inner wall of the housing recess 84 and the outer wall of the second receiving portion 70 varies along the circumferential direction. Accordingly, the inner wall of the housing recess 84 and the second receiving portion 70 are engaged by the shape of the string G, and relative rotation in the circumferential direction is restricted.

  7B, the outer wall of the second receiving portion 70 of the washer 50 has a partial arc shape S concentric with the axial center of the screw, and a protrusion T extending in the radial direction is formed on the remaining portion. Can be formed. At this time, a recess K recessed in the radial direction is formed in the inner wall of the housing recess 84. By the engagement of the protrusion T and the recess K, the inner wall of the housing recess 84 and the second receiving portion 70 are engaged, and the relative rotation in the circumferential direction is restricted. At this time, it is preferable that the recess K formed in the housing recess 84 has a small perfect circular shape (partial arc). This is because the recess K can be formed by only one processing of the rod-shaped drill when the housing recess 84 is cut. Although not particularly illustrated, a recess (notch) can be formed on the second receiving portion 70 side of the washer 50, and a protrusion protruding radially inward can be formed on the housing recess 84 side.

  Next, with reference to FIG. 8, the reverse rotation prevention structure of the screw body which concerns on 2nd embodiment of this invention is demonstrated. In this reverse rotation prevention structure, the male screw body 10 is the same as that in the first embodiment, but the structures of the washer 50 and the fastened member 80 are partially different. A description of common parts with the above is omitted.

  As shown in FIG. 9A, the washer 50 is thinner than the first embodiment, and also protrudes in the screw tip direction on the second receiving portion 70 side facing the fastened member 80. A second washer-side tapered surface 76 is formed.

  As in the first embodiment, the outer wall 72 of the second receiving portion 70 of the washer 50 and the inner wall of the housing recess 84 are eccentric and have a perfect circular shape, so that they can rotate in the circumferential direction by being fitted to each other. Is regulated.

  Returning to FIG. 8, a member-side tapered surface 86 that is concave on the screw tip side is formed on the bottom surface of the accommodation recess 84 of the fastened member 80. As a result, the fastening force of the male screw body 10 is received through the washer 50 by coming into contact with the second washer-side tapered surface 76 of the washer 50.

  Further, a pulling space 88 is formed in a part of the inner wall of the housing recess 84. The pulling space 88 is secured by expanding the inner wall of the housing recess 84 radially outward and increasing the depth of the recess. The pulling space 88 forms a gap in a part of the outer wall of the second receiving portion 70 of the washer 50.

  When the fastened member 80 is fixed using the male screw body 10 and the washer 50, the screw body side unevenness 24 of the male screw body 10 and the first receiving portion side unevenness 64 on the washer 50 side are engaged as the first engagement mechanism A. To do. Further, as the second engagement mechanism B, the outer wall of the second receiving portion 70 of the washer 50 and the inner wall of the accommodating recess 84 are fitted to each other, so that circumferential rotation is restricted. As a result, the reverse rotation of the male screw body 10 is prevented, that is, is not loosened.

  FIG. 9B illustrates an operation when the male screw body 10 is forcibly loosened. For example, by inserting the tip of the minus driver D into the pulling space 88, the tip is inserted into the back side of the washer 50. In this state, by lifting the tip of the minus driver D, the second receiving part 70 of the washer 50 can be deformed upward. As a result, the second engagement mechanism B formed by the second receiving portion 70 and the accommodating recess 84 is released. If the male screw body 10 is rotated in the loosening direction in this state, the washer 50 can also be rotated together, so that the male screw body 10 can be loosened.

  In the second embodiment, the case where the pulling space 88 is formed in the housing recess 84 of the fastened member 80 is illustrated, but the present invention is not limited to this. For example, as shown in FIG. 10A, by forming an inclined surface 77A on the outer wall of the washer 50, the tip of the minus driver D can be inserted into the back side of the washer 50 (the fastened member 80 side). To. Further, as shown in FIG. 10B, an insertion recess 77B is formed on the periphery of the washer 50 so as to be separated from the fastened member 80. The tip of the minus driver D can be inserted into the back side of the washer 50 through the insertion recess 77B. In addition, a crescent-shaped gap is created using the diameter difference between the outer diameter of the washer 50 and the inner diameter of the housing recess 84, and the tip of the minus driver D is created using this crescent-shaped gap (not shown). Can be inserted into the back side of the washer 50.

  FIG. 11 shows the screw loosening prevention structure of the third embodiment. As shown in FIG. 11B, the screw body side seat portion 22 of the male screw body 10 has a planar shape, and a saw blade-shaped screw body side unevenness 24 is formed there. Further, a constriction 32 for holding the washer 50 is formed at the root of the shaft portion 30 of the male screw body 10.

  As shown in FIG. 11A, the first receiving portion 60 of the washer 50 has a planar shape, and a saw-tooth-shaped first receiving portion-side unevenness 64 is formed there. In the through hole 52 of the washer 50, an engagement protrusion 52 </ b> A that protrudes toward the inner peripheral side is formed, and is engaged with the constriction 32 of the male screw body 10. As a result, the male screw body 10 and the washer 50 can be integrated (coupled) in advance.

  Furthermore, a washer side stepped portion 74 extending in the axial direction of the screw is formed in the second receiving portion 70 of the washer 50. Here, the washer-side stepped portion 74 is constituted by a claw bent toward the fastened member 80 side.

  On the other hand, the member side seat portion 82 of the fastened member 80 has a member side step portion 82A extending in the axial direction of the screw. The member-side stepped portion 82A is a step that falls to the screw tip side. The distances from the screw shaft center of the washer side step 74 and the member side step 82A coincide with each other. Accordingly, as shown in FIG. 11C, when the male screw body 10 is tightened, the washer side stepped portion 74 and the member side stepped portion 82A are engaged, and the relative rotation of the washer 50 and the fastened member 80 is prevented. The

  In the third embodiment, the case where the two are integrated in advance by the constriction 32 of the male screw body 10 and the engagement protrusion 52A of the washer 50 is exemplified, but the method is not limited to this. For example, the male screw body 10 and the washer 50 can be integrated by magnetic force by giving magnetism to at least one of them. In addition, the male screw body 10 and the washer 50 can be integrated in advance by an adhesive, (spot) welding, or press-fitting (frictional force). It is also possible to integrate the male screw body 10 and the washer 50 using an auxiliary tool such as an O-ring.

  In addition, although the case where the washer side step part 74 was formed in the outer periphery of the washer 50 was illustrated here, this invention is not limited to this. For example, as shown in FIG. 12, a washer side step (projection) 74 can be formed inside the outer edge of the washer 50. A member-side stepped portion (depression) 82 </ b> A for accommodating the washer-side stepped portion 74 is formed in the accommodating recess 84 of the fastened member 80. As a result, the washer-side step (projection) 74 and the member-side step (depression) 82A are engaged to prevent relative rotation.

  FIG. 13 shows a reverse rotation prevention structure for a screw body according to a fourth embodiment of the present invention. As shown in FIG. 13A, the outer shape of the washer 50 is a circular shape that is eccentric with respect to the axial center of the screw. The washer 50 is a so-called disc spring, and when it receives a fastening force from the male screw body 10, it is elastically deformed in the axial direction.

  As shown in FIG. 13B, the washer 50 is accommodated in an eccentric circular accommodation recess 82 formed in the fastened member 80. The threaded body side seat portion 22 of the male threaded body 10 has a threaded body side unevenness 24 formed at the center, and engages with the first receiving portion side unevenness 64 of the washer 50. Further, on the outer side of the screw body side unevenness 24 in the screw body side seat portion 22, a pressing surface 23 that directly contacts the fastened member 80 is formed.

  Furthermore, the gap L between the bottom surface of the housing recess 82 and the screw body side unevenness 24 of the male screw body 10 is set to be slightly smaller than the axial dimension of the washer 50. As a result, when the male screw body 10 is tightened, the washer 50 is sandwiched between the bottom surface of the housing recess 82 and the screw body side unevenness 24 and is elastically deformed. However, the amount of elastic deformation is sufficient to prevent relative rotation of the screw body side unevenness 24 and the first receiving portion side unevenness 64. This is because the fastening force of the male screw body 10 is directly transmitted to the fastened member 80 via the pressing surface 23. According to the present embodiment, the strength and rigidity of the washer 50 itself can be lowered, so that the manufacturing cost can be reduced.

  In the first to fourth embodiments, the case where the head 20 of the male screw body 10 protrudes from the fastened member 80 is illustrated. However, if the depth of the accommodation recess 84 of the fastened member 80 is increased, the head 20 Can be accommodated in the accommodating recess 84.

  For example, as shown in FIG. 14, the first receiving portion 60 of the washer 50 can be formed in a cylindrical shape that can accommodate the head 20 of the male screw body 10. That is, an accommodation hole 51 for accommodating the head 20 of the male screw body 10 is formed on the upper surface of the washer 50. As a result, the head 20 is less likely to come into contact with the external member, and the male screw body 10 is difficult to loosen. At this time, it is possible to limit the second receiving portion 70 to be an eccentric circle to the vicinity of the head 20 side (the upper end side in FIG. 14) of the washer 50. As described above, both the concentric circumferential wall 71 and the eccentric second receiving portion 70 are formed on the washer 50, and each is engaged with the fastened member 80. The relative engagement between the two can be prevented by the second engagement mechanism B while ensuring the coaxiality.

  Furthermore, as shown in FIG. 14, it is also preferable to arrange a boundary surface 89 between the fastened member 80 and the base 90 in the middle of the washer 50 in the axial direction. In this case, when a shearing force along the boundary surface 89 acts between the fastened member 80 and the base 90, the shearing force is received by the outer peripheral surface (the peripheral wall 71 or the outer wall 72) of the washer 50. I can do it. Therefore, even if the male screw body 10 is not thickened, if the washer 50 has a high rigidity, both can be integrated and the rigidity against the shearing force can be increased. At this time, the annular portion of the first receiving portion 60 in which the first receiving portion side unevenness 64 is formed and the washer 50 having a long cylindrical shape having an eccentric flange-shaped outer wall 72 are separated, The outer periphery of the annular first receiving portion 60 is eccentric with respect to the axis of the screw. On the other hand, the washer 50 is provided with an eccentric fitting portion into which the annular portion can be inserted, and the annular portion and the washer 50 are It may also be configured to prevent relative rotation.

  In the first to fourth embodiments, the case where the head of the male screw body 10 and the washer 50 are engaged is illustrated. However, the present invention is not limited to the case of applying to the male screw body, and this locking mechanism is applied to the female screw body side. You can also For example, as shown in FIG. 15, by providing the first engagement mechanism A and the second engagement mechanism B between the female screw body 18, the washer 50, and the fastened member 80, the female screw body 18 can be rotated in the reverse direction. It is also possible to prevent it.

  In the first to fourth embodiments, the washer 50 is exemplified only when the outer shape of the washer 50 is a circle or a partial arc, but other shapes can be adopted. For example, the outer shape of the washer 50 may be oval, oval, polygonal or the like. In other words, in order to prevent relative rotation by fitting with the accommodating recess, it is only necessary that the outer shape of the washer 50 is “non-perfect circle (not concentric perfect circle)” with respect to the shaft center. In the fourth embodiment of FIG. 13, the case where the washer 50 is elastically deformed as a disc spring is illustrated. However, it can be elastically deformed like a spring washer. Furthermore, it is also preferable that a washer is formed of a composite material in which a metal and an elastically deformable material (for example, rubber) are integrated so as to be elastically deformable.

  Further, the embodiments of the present invention are not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the scope of the present invention.

  According to the present invention, it is possible to reliably prevent screws from loosening with a simple structure.

DESCRIPTION OF SYMBOLS 10 Male screw body 20 Head part 22 Screw body side seat part 24 Screw body side uneven | corrugated 23 Press surface 26 Screw body side taper surface 30 Shaft part 30a Cylindrical part 30b Screw part 50 Washer 52 Through-hole 52A Engagement protrusion 60 First receiving part 64 First receiving part Part side unevenness 66 Washer side taper surface 70 Second receiving part 72 Outer wall 80 Fastened member 82 Member side seat part 84 Housing recess 90 Base 92 Female screw hole

Claims (20)

A screw body having a thread and a washer are provided to fasten a member to be fastened by the screw body and the washer.
The screw body has a screw body side seat portion facing the washer,
The washer includes a first receiving portion facing the screw body side seat portion and a second receiving portion facing the fastened member,
The fastened member has a member side seat portion facing the second receiving portion,
A first engagement mechanism is configured between the screw body side seat portion and the first receiving portion so that the screw body side seat portion is maintained in an engaged state even when a rotational force in a specific direction acts on the screw body side seat portion. And
Between the member side seat portion and the second receiving portion, a second engagement mechanism is configured that maintains a state where the washers are engaged with each other even if a rotational force in the specific direction acts on the washer. A structure for preventing reverse rotation of a screw body, wherein the screw body in a fastened state is prevented from rotating in a specific direction. In the first engagement mechanism, a screw body side unevenness is formed on the screw body side seat portion, and a first receiving portion side unevenness engaging with the screw body side unevenness is formed on the first receiving portion, and the engagement Characterized by getting state,
The structure for preventing reverse rotation of the screw body according to claim 1. The screw body side unevenness is a saw blade shape provided in the circumferential direction,
The reverse rotation prevention structure for a screw body according to claim 2. The screw body side unevenness is a mountain shape or a wave shape provided in the circumferential direction,
The reverse rotation prevention structure for a screw body according to claim 2. The screw body side unevenness is an embossed shape,
The reverse rotation prevention structure for a screw body according to claim 2. The screw body side unevenness is a spiral groove or mountain,
The reverse rotation prevention structure for a screw body according to claim 2. The first receiving part side unevenness is a saw blade shape provided in the circumferential direction,
The reverse rotation prevention structure for a screw body according to any one of claims 2 to 6. The first receiving portion side unevenness is a mountain shape or a wave shape provided in the circumferential direction,
The reverse rotation prevention structure for a screw body according to any one of claims 2 to 6. The first receiving side unevenness is an embossed shape,
The reverse rotation prevention structure for a screw body according to any one of claims 2 to 6. The first receiving part side unevenness is a spiral groove or mountain,
The reverse rotation prevention structure for a screw body according to any one of claims 2 to 6. In the screw body side seat portion, a screw body side tapered surface inclined in a radial direction is formed,
The structure for preventing reverse rotation of the screw body according to any one of claims 1 to 10. The first receiving portion is formed with a washer side tapered surface inclined in the radial direction.
The reverse rotation prevention structure for a screw body according to any one of claims 1 to 11. The first engagement mechanism is configured to increase the engagement strength in the loosening direction as the distance between the screw body side seat portion and the first receiving portion decreases.
The structure for preventing reverse rotation of the screw body according to any one of claims 1 to 12. The first engagement mechanism allows relative rotation in the tightening direction of the screw body side seat portion between the screw body side seat portion and the first receiving portion.
The structure for preventing reverse rotation of the screw body according to any one of claims 1 to 13. The washer is elastically deformable in the axial direction of the screw body,
The reverse rotation prevention structure for a screw body according to any one of claims 1 to 14. The member side seat portion includes an accommodation recess capable of accommodating the second receiving portion,
The structure for preventing reverse rotation of the screw body according to any one of claims 1 to 15. The second engagement mechanism is characterized in that the engagement state is obtained by fitting the second receiving portion and the receiving recess.
The reverse rotation prevention structure for a screw body according to claim 16. The inner wall of the receiving recess varies in the circumferential direction from the axis of the screw body, and the outer wall of the second receiving portion varies in the circumferential direction from the axis of the screw body. By this, the engagement state is obtained by contact of the inner wall of the housing recess and the outer wall of the second receiving portion,
The reverse rotation prevention structure for a screw body according to claim 16 or 17. The fastening force of the screw body is transmitted to the fastened member via a contact surface between the bottom surface of the housing recess and the second receiving portion.
The reverse rotation prevention structure for a screw body according to claim 16 or 17. The member side seat portion has a member side step portion stepped in the axial direction of the screw body,
The second receiving portion is formed with a washer side stepped portion that engages with the member side stepped portion.
The reverse rotation prevention structure for a screw body according to any one of claims 1 to 19.

Images