JP2007092836A - Loosening prevention structure of screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a loosening prevention structure capable of securely preventing loosening when tightening a screw. <P>SOLUTION: In this loosening prevention structure of the screw for preventing loosening of screw-fitted female and male screw members, a locking plate 30 is fixed on a top face 20B of the female screw member 20, at least one of locking piece parts 30A, 30C is formed in an inner fringe side part of the locking plate, a plurality of locking step parts 10, 10E are formed on a screw thread of the male screw member 10, and a locking piece part rotating in the direction of loosening of the female screw member is locked by the locking step parts. The locking step parts may be formed on a screw thread flank on a side of direction of loosening of the female screw member of the male screw member and be formed in a top part of the screw thread. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a screw loosening prevention structure, and more particularly to a structure in which a male and female screw members screwed together are not easily loosened.

  For example, when fastening a member, a method is generally used in which an insertion hole is formed in the member, a bolt is inserted into the insertion hole, a female screw of a nut is screwed into a male screw of the bolt, and a bolt / nut is tightened. .

  Since fastening with such bolts and nuts may be loosened due to vibration, thermal expansion, aging, or the like, various types of loosening prevention methods have been proposed. For example, a loosening prevention plate is fixed to the periphery of the screw hole on the top surface or seating surface of the nut, and the loosening prevention plate is elastically deformed and pressed against the thread flank of the bolt, thereby providing a rotational resistance to the nut. A stop structure is known (Patent Document 1).

  In addition, an arc-shaped lock portion whose tip side is deflected toward the center of the nut is integrally formed on the top surface of the nut, while a recess is formed in the male thread of the bolt, and the tip of the lock portion is inserted into the recess. This prevents the nut from rotating in the loosening direction, while the lock part is elastically deformed and the tip of the lock part is pulled out of the recess to allow the nut to rotate in the tightening direction. It has been proposed (Patent Document 2).

Japanese Patent Laid-Open No. 2001-124043 Japanese Patent Laid-Open No. 2002-242921

  However, in the loosening prevention structure described in Patent Document 1, when the nut is deliberately turned with an excessive force exceeding the rotational resistance caused by pressing the loosening prevention plate against the thread flank of the bolt, the fastening can be easily removed. End up.

  On the other hand, the loosening prevention structure described in Patent Document 2 can prevent the nut from loosening unless the tip of the lock part or the recess of the male screw is broken, but the nut becomes bulky by the height of the lock part, and the space When it was narrow, it could not be used. Of course, it is only necessary to reduce the thickness of the lock portion, but in that case, it is difficult to ensure the strength of the lock portion due to the form of the lock portion, and if an excessive force acts on the nut in the slack direction, the lock portion There is a risk of being destroyed.

  In view of such problems, an object of the present invention is to provide a screw loosening prevention structure that can reliably prevent loosening of screw fastening without incurring bulkiness.

  Accordingly, the screw loosening prevention structure according to the present invention is a screw loosening prevention structure that prevents the screwed male and female screw members from loosening, and a locking plate is fixed to the top surface of the female screw member. And at least one locking piece portion is formed on the inner edge side portion of the locking plate, while a plurality of locking step portions are formed on the thread of the male screw member. The locking piece portion rotating in the slack direction of the female screw member is locked.

  One of the features of the present invention is that the locking plate is fixed to the top surface of the female screw member, and when the female screw member rotates in the slack direction, the locking piece portion of the locking plate fixed to the female screw member is locked to the male screw member. It is in the point which made it latch by a step part.

  As a result, as long as the locking piece portion or the locking step portion is not damaged, the screw fastening is not loosened, and a reliable fastening can be performed. On the other hand, the locking step only locks the locking piece that rotates in the slack direction, and therefore, when the male and female screw members are relatively rotated in the tightening direction, tightening can be performed without any trouble.

  Moreover, since the thickness of the locking plate is small, the female screw member does not become bulky and can be used even in a narrow space.

  The locking step portion may be formed anywhere in the screw thread as long as the locking piece portion rotating in the slack direction of the female screw member can be locked, and may be in any form. Specifically, the locking step portion can be formed on the thread flank on the loose rotation direction side of the female screw member of the male screw member. The locking step portion can also be formed on the top of the thread of the male screw member.

  In this case, the locking step portion can be locked by forming a step surface on the loose rotation direction side of the female screw member and abutting the locking piece portion rotating in the loose rotation direction of the female screw member. On the other hand, the portion of the female screw member on the tightening rotation direction side when viewed from the step surface is preferably an inclined surface that smoothly continues to the flank or top of the thread.

  The locking piece portion may be formed by forming a rectangular protrusion flush with or inclined with respect to the locking plate, and the locking piece portion has a rectangular portion flush with the locking plate with respect to the locking plate. It can also be formed by twisting 90 ° and bending it so as to be inclined in the circumferential direction.

  The locking plate is fixed to the top surface of the female screw member, but the fixing method is not particularly limited, and can be fixed by welding or caulking. In addition, the planar shape of the locking plate is not particularly limited as long as it is not too thick. For example, the locking plate may be a ring shape or an arc shape.

  The male screw member can be used in the form of a screw rod formed by rolling, cutting, rolling, or the like of a male screw on the outer peripheral surface of the steel bar, or a bolt having a head. The female screw member can be used in the form of a member having an internal thread formed on the inner peripheral surface, for example, a nut.

  Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. 1 to 4 show a preferred embodiment of a screw loosening prevention structure according to the present invention. In the figure, a bolt (male screw member) 10 is formed by forming a hexagonal head 10A at one end of a round bar, a shaft portion 10B is formed at the other end portion of the round bar, and a male screw is formed at the shaft portion 10B. 10C is formed, and the male screw 10C is formed with a plurality of locking step portions 10D on the flank on the slack direction side of the male screw 10C.

  As shown in FIG. 4, the locking step portion 10 </ b> D is formed with a step surface that suddenly falls on the loose rotation direction side of the nut 20, and the screw thread from the step surface toward the tightening rotation direction side of the nut 20. It has a shape that rises smoothly up to the flank.

  On the other hand, the nut (female screw member) 20 has a hexagonal outer shape and a substantially cylindrical inner shape, a female screw 20A is formed on the inner surface, and a short cylindrical mounting flange portion 20C is formed on the top surface 20B of the nut 20. The locking plate 30 is press-fitted into the mounting flange portion 20C, and the locking plate 30 is caulked by bending the upper edge portion of the mounting flange portion 20C inward, and the top surface 20B of the nut 20 is formed. It is fixed to.

  As shown in FIG. 3, the locking plate 30 has a ring shape as a whole, and a plurality of long rectangular locking pieces 30A are formed at regular intervals on the inner edge side portion thereof. The stopper portion 30A is brought into contact with and locked by the locking step portion 10D of the bolt 10 when the nut 20 is rotated in the loosening direction side.

  Now, when fastening a member (not shown) with the bolt 10 and the nut 20, the shaft portion of the bolt 10 is inserted into an insertion hole formed in the member, and the member is placed between the head 10 </ b> A of the bolt 10 and the nut 20. Then, the male screw 10C of the bolt 10 is rotated relative to the female screw 20A of the nut 20 to rotate.

  At this time, as shown in FIG. 4, the locking piece 30A of the locking plate 30 of the nut 20 drops down the locking step 10D of the bolt 10 and is guided by an inclined surface continuous to the locking step 10D. When the next locking step portion 10D is reached, the locking step portion 10D falls downward, and while repeating such an operation, the nut 20 smoothly advances the male screw 10C of the bolt 10 to smoothly tighten the members. Can be done.

  After the fastening of the members is completed, an excessive force in the loosening direction is applied to the bolt 10 or the nut 20 and when the nut 20 is slightly rotated in the loosening direction, as shown in FIG. The locking piece portion 30A of the plate 30 moves toward the locking step portion 10C along the inclined surface of the thread connected to the locking step portion 10D of the bolt 10, and is brought into contact with and locked to the locking step portion 10C. Therefore, the rotation of the nut 20 in the further loosening direction is prevented, and the loosening of the screw fastening is prevented.

  At this time, a load acts on the locking piece portion 30A from the locking step portion 10D, but since the plurality of locking piece portions 30A are locked by the plurality of locking step portions 10D, the nut loosening rotation direction The load is distributed to the plurality of locking pieces 30A and the locking step 10D.

  Further, since the thickness of the locking plate 30 is small, the nut 20 does not become bulky and can be used even in a narrow space.

  Further, the screw thread flank on the tightening side of the male screw 10C of the bolt 10 has a smooth surface similar to that of a normal thread flank. Therefore, when the bolt 10 and the nut 20 are screwed together, The female screw 20A contacts in the same manner as a normal male and female screw, and does not adversely affect the screw fastening.

  5 to 8 show a second embodiment, in which the same reference numerals as those in FIGS. 1 to 4 denote the same or corresponding parts. In this example, a plurality of locking step portions 10E are formed at intervals on the top of the screw thread of the male screw 10C of the bolt 10, and the locking step portion 10E stands suddenly in the loosening rotation direction side of the nut 20 in the radial direction of the bolt 10. A stepped surface is formed, and the shape is such that the stepped surface smoothly rises from the stepped surface toward the tightening rotation direction of the nut 20 to the top of the screw thread.

  On the other hand, a plurality of locking piece portions 30C are formed on the inner edge side portion of the locking plate 30 with a space between each other, and the locking piece portion 30C twists a rectangular shape flush with the locking plate 30 by 90 °, and further the first half For example, the portion is bent so as to be inclined in the circumferential direction of 30 ° to 45 °.

  The shaft portion of the bolt 10 is inserted into the insertion hole formed in the member, and is sandwiched between the head portion 10A of the bolt 10 and the nut 20, and the male screw 10C of the bolt 10 is relative to the female screw 20A of the nut 20. Rotate and screw.

  At this time, as shown in FIG. 8, the locking piece 30 </ b> C of the locking plate 30 of the nut 20 is elastically deformed by the male screw 10 </ b> C of the bolt 10 into a shape greatly bent along the top of the thread. When the locking piece portion 30C of the plate 30 reaches the position of the locking step portion 10E, it falls in the radial direction due to the elastic restoring force, and is guided by the inclined surface continuous to the locking step portion 10E to the top of the original thread. When it is elastically deformed into a shape bent greatly along and reaches the next locking step portion 10E, the locking piece portion 30C similarly falls in the locking step portion 10E in the radial direction, and the nut is repeated while repeating such an operation. 20 can smoothly screw the male screw 10 </ b> C of the bolt 10, and can smoothly fasten the members.

  After the fastening of the members is completed, an excessive force in the loosening direction is applied to the bolt 10 or the nut 20 and when the nut 20 is slightly rotated in the loosening direction, as shown in FIG. The locking piece portion 30C of the plate 30 is guided along an inclined surface continuing to the locking step portion 10E of the bolt 10 and is elastically restored, and when it reaches the locking step portion 10E of the bolt 10, the locking step portion 10E is brought into contact with the locking step portion 10E. Since the front half part is bent obliquely, the elastic deformation that detaches the locking step portion 10E hardly occurs, the locking step portion 10C is securely locked, and the nut 20 is further loosened. , And the loosening of the screw fastening is prevented.

It is a schematic perspective view which shows the volt | bolt and nut in preferable embodiment of the loosening prevention structure of the screw concerning this invention. It is a figure which shows the cross-sectional shape of the volt | bolt nut in the said embodiment. It is a top view which shows the latching plate in the said embodiment. It is a figure for demonstrating the loosening prevention effect | action of the said embodiment. It is a schematic perspective view which shows the volt | bolt nut in 2nd Embodiment. It is a figure which shows the cross-sectional shape of the volt | bolt nut in the said embodiment. It is a top view which shows the latching plate in the said embodiment. It is a figure for demonstrating the loosening prevention effect | action of the said embodiment.

Explanation of symbols

10 Bolt (Male thread member)
10C male screw 10D locking step 20 nut (female screw member)
20A Female thread 20B Top surface 30 Locking plate 30A Locking piece 30C Locking piece

Claims (4)

A screw loosening prevention structure designed to prevent the screwed male and female screw members from loosening,
A locking plate is fixed to the top surface of the female screw member, and at least one locking piece is formed on the inner edge side portion of the locking plate, while a plurality of engagements are formed on the thread of the male screw member. A locking structure for a screw, wherein a locking step is formed, and the locking step is configured to lock the locking piece that rotates in the loosening direction of the female screw member.   The screw locking structure according to claim 1, wherein the locking step portion is formed on a thread flank on a loosening direction side of the female screw member of the male screw member.   The screw locking structure according to claim 1, wherein the locking step is formed on a top of the screw thread of the male screw member. The screw locking structure according to claim 1, wherein the locking piece is formed by twisting a rectangular portion flush with the locking plate by 90 ° and bending the tip portion so as to incline in the circumferential direction.

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