JP4837963B2 - Screw locking structure - Google Patents

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 locking part is elastically deformed and the tip of the locking 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.

  Therefore, the screw loosening prevention structure according to the present invention is a screw loosening prevention structure in which the screwed male and female screw members are loosened, and the male screw member has at least a female screw member in its axial direction. A locking recess is formed in the screw thread at the threaded portion, and a contact surface portion is formed on the leading side in the slack direction of the female screw member, and a relief surface portion is formed on the delay side, while the top of the female screw member is formed. A locking plate is fixed to the surface or the seat surface, and a locking projection that can be fitted into the locking recess of the male screw member is formed on the inner edge side portion of the locking plate. When the female screw member is inserted into the locking recess and abuts against the contact surface portion, relative rotation in the loosening direction of the female screw member is prevented, while the locking convex portion is guided by the relief surface portion and from the locking concave portion. Elastically deformed so that it can be detached And the is characterized in that no such relative rotation of the tightening direction of the female screw member is allowed.

  One of the features of the present invention is that a locking plate is fixed to the top surface or seating surface of the female screw member, and the locking projection of the locking plate is fitted into the locking recess of the male screw member so that the locking recess hits. The female screw member is prevented from rotating relatively in the slack direction by contacting the surface portion, and the locking convex portion is locked by elastically deforming the locking convex portion by the relief surface portion of the locking concave portion of the male screw member. It is made to detach | leave from a recessed part and to allow the relative rotation to the fastening direction of a female screw member.

  Thereby, since the locking of the screw fastening is prevented by fitting the locking recess and the locking projection, the fastening does not loosen unless the locking recess or the locking projection is destroyed. On the other hand, when the male and female screw members are rotated relative to each other in the tightening direction, the locking projection is elastically deformed by being guided by the relief surface of the locking recess and is released from the locking recess. Can be done without any problems.

  If the male and female screw members are rotated relatively in the loosening direction with an excessive force in a state where the locking convex portion is fitted in the locking concave portion, the side edge of the locking convex portion is locked. Although the load from the contact surface portion of the concave portion acts, this load is widely dispersed and received on the plate surface of the locking convex portion, so that the locking convex portion is not broken. In particular, as will be described later, when a plurality of locking projections and a plurality of locking recesses are formed to fit each other, the load that loosens the screw fastening is locked to each of the locking projections. Since it acts in a distributed manner with the recesses, it is possible to prevent the locking projections more reliably.

  Further, even if the locking plate is employed as described above, the locking projections are not broken, so that the thickness of the locking plate can be reduced. As a result, the female screw member does not become bulky and can be used in a narrow space. it can.

  One locking recess may be provided, and a plurality of locking recesses may be formed at an arbitrary angle, for example, 90 °, in the circumferential direction of the male screw member. Further, the locking recess only needs to be formed at least in the thread of the threaded portion of the female screw member in the axial direction of the male screw member. However, when the thickness of the member to be fastened is unknown, the position of the locking recess is different. It is necessary to prepare a plurality of male screw members. Therefore, the locking recess is preferably formed over substantially the entire length of the male screw member in the axial direction.

  The shape of the locking recess is such that the contact surface portion is formed on the leading side in the slack direction of the female screw member, and the relief surface portion is formed on the delay side, but the contact surface portion only needs to be in contact with the locking protrusion of the locking plate to restrict its rotation. For example, the contact surface portion can be a steep surface, that is, a flat surface extending substantially in the radial direction of the male screw member, and a surface having an arbitrary shape in which a concave groove into which the locking convex portion of the locking plate is fitted is formed. You can also

  Moreover, the relief surface part should just be able to detach | leave from a latching recessed part by elastically deforming a latching convex part. For example, the relief surface portion may be an inclined surface that gently extends in the circumferential direction from the base portion of the contact surface portion, and may further form a radius on the ridge line of the inclined surface so that the locking convex portion is easily elastically deformed.

  The locking recess may have any shape as long as it has the above-described contact surface portion and relief surface portion. For example, as the planar shape of the locking recess (the shape seen from the direction of the central axis of the male screw member), a substantially triangular shape, a planar rectangular shape, or a trapezoidal shape can be adopted.

  The shape of the locking projection may be any shape that fits into the locking recess, that is, a shape that can be fitted to restrict the rotation of the female screw member in the loosening direction. Moreover, it can also be set as the planar shape which fits in a latching recessed part with a clearance gap.

  Although the locking plate is fixed to the top surface or the seating surface of the female screw member, the fixing method is not particularly limited and can be fixed by welding or caulking. Moreover, the planar shape is not particularly limited as long as the anti-slack plate is not too thick. For example, it may be a ring shape or an arc shape. The material of the locking plate is not particularly limited as long as it can be elastically deformed.

  There may be one locking projection, or a plurality of locking projections, but if a plurality of locking projections are formed, fastening loosening can be prevented at an arbitrary rotation angle of the female screw member. In addition, when a plurality of locking projections are formed, the locking projections not related to the engagement with the locking recesses are elastically deformed and pressed against the threaded slope of the male screw member, thereby imparting rotational resistance to the female screw member. As a result, the loosening prevention performance of the fastening can be reliably improved.

  That is, a plurality of locking projections are formed side by side on the inner edge side portion of the locking plate, and the locking projections other than the locking projections fitted into the locking recesses are elastically deformed to form the thread slope of the male screw member. It is preferable to apply rotational resistance to the female screw member by pressing.

  In addition, although a plurality of locking projections are formed, a part of the locking projections has a shape different from that of the locking projections, that is, a shape that does not fit into the locking recesses, and serves as a pressing piece that performs only a pressing function. You may make it function.

  That is, a pressing piece portion having a shape different from that of the locking concave portion is formed on the inner edge side portion of the loosening prevention plate, and the pressing piece portion is elastically deformed and pressed against the thread slope of the male screw member to thereby provide rotational resistance to the female screw member. It can also be configured to give.

  The male screw member can be used in the form of a screw rod having a male screw engraved 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 5 show a preferred embodiment of the screw loosening prevention structure according to the present invention. In the figure, a bolt (male thread member) 10 is formed by forming a hexagonal head 10A at one end of a round bar, a male thread 10B is formed at the other end of the round bar, and the male thread 10B has a male thread 10B. 10 C of latching recessed parts are formed in every 90 degrees of the circumferential direction in almost all the threads of a longitudinal direction, for example.

  As shown in FIG. 4, the locking recess 10C has a steep vertical wall shape on the advancing side in the slack direction of the nut, that is, a flat contact surface portion 10D extending in the radial direction of the bolt 10, and a gentle inclination angle on the delay side. The relief surface portion 10E is formed, and the upper ridge line of the relief surface portion 10E is formed in the radius 10F.

  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 formed on the inner surface, and a short cylindrical shape on the top surface 20B opposite to the seating surface of the nut 20. The mounting flange portion 20C is integrally formed, 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. The nut 20 is fixed to the top surface 20B.

  The loosening prevention plate 30 is made of an elastically deformable material, for example, a metal material, and has a ring shape as shown in FIGS. 3 and 5, and its inner edge is a nut 20 as shown in FIG. The female screw member 20A protrudes to the vicinity of the thread tip, and a plurality of locking projections 30A are formed side by side on the inner edge side portion of the locking plate 30. Each locking projection 30A is in the loosening direction of the nut 20. After the advancing side rises steeply, it forms a triangular shape that gently falls toward the lagging side, so that it can be fitted almost exactly into the locking recess 10C of the bolt 10.

  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 inserted between the head 10 </ b> A of the bolt 10 and the nut 20. The male screw 10 </ b> B of the bolt 10 is rotated relative to the female screw 20 </ b> A of the nut 20 so as to advance.

  At this time, as shown in FIG. 5, the locking projection 30B of the loosening prevention plate 30 of the nut 20 is elastically deformed upward by the thread flank of the male screw 10B and pressed against the thread flank. When the screw 10 reaches the position of the locking recess 10C of the bolt 10, it fits into the locking recess 10C.

  However, the locking projection 30A of the locking plate 30 has a shape that gently rises from the leading side in the slack direction of the nut 20 toward the lagging side, and the lagging side of the locking recess 10C in the nut slacking direction is gently inclined. Since the upper ridge line is rounded 10F, when the bolt 10 and nut 20 are relatively rotated in the tightening direction of the nut 20, the locking projection of the loosening prevention plate 30 is formed. 30A is guided by the relief surface portion 10E of the locking recess 10C and elastically deformed upward, and can be detached from the locking recess 10C. The male screw 10B of the bolt 10 and the female screw 20A of the nut 20 smoothly thread, The member can be securely fastened.

  When the members are fastened, as shown in FIG. 5, some of the locking projections 30A are fitted into the locking recesses 10C of the bolt 10, and the remaining locking projections 30A are elastically deformed to be externally threaded 10B. Is pressed against the thread flank.

  In this state, when an excessive force in the slack direction is applied to the bolt 10 or the nut 20, the steep rising side edge of the locking projection 30A of the locking plate 30 and the steep contact surface portion 10D of the locking recess 10C are formed. It abuts and is prevented from rotating relative to the slack direction, and loosening of the screw fastening is prevented.

  At this time, a load from the contact surface portion 10D of the locking concave portion 10C acts on the locking convex portion 30A, but this load is widely dispersed and received on the plate surface of the locking convex portion 30A. In addition, since the plurality of locking projections 30A and the plurality of locking recesses 10C are fitted, the load in the nut loosening direction is distributed and acts on the plurality of locking projections 30A and the locking recesses 10C. The locking projection 30A is not destroyed.

  Further, in addition to the loosening prevention of the screw fastening by fitting the locking recess 10C and the locking projection 30A, the locking projection 30A pressed against the thread flank of the male screw 10B of the bolt 10 rotates with respect to the nut 20. Resistance is imparted, and this also ensures that the looseness of the screw fastening is prevented.

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

  FIG. 6 shows a second embodiment, in which the same reference numerals as those in FIGS. 1 to 5 denote the same or corresponding parts. In this example, the locking projections 30A and the pressing pieces 30B are alternately formed on the inner edge side portion of the locking plate 30, and the pressing pieces 30B are formed in a substantially rectangular shape different from the locking projections 30B. Instead of being fitted into 10C, it is elastically deformed and pressed against the thread flank of the male screw 10B to give rotational resistance to the nut 20.

  FIG. 7 shows a third embodiment, in which the same reference numerals as those in FIGS. 1 to 5 denote the same or corresponding parts. In this example, the loosening prevention plate 30 is formed in an arc shape instead of a ring shape, and the locking projections 30A are formed side by side on the inner edge side portion of the loosening prevention plate 30, and the two loosening prevention plates 30 are formed on the top surface of the nut 20 ( (Or seating surface).

  8 and 9 show a fourth embodiment, in which the same reference numerals as those in FIGS. 1 to 5 denote the same or corresponding parts. This example is the same as in the first embodiment except that a short rectangular locking protrusion 30A 'is formed at an inner edge portion of the ring-shaped slack stop plate 30 with a gap therebetween.

  In this example, the locking projection 30A ′ of the locking plate 30 is fitted into the locking recess 10C of the bolt 10 with a gap, but the locking projection 30A is relative to the relative rotation of the nut 20 in the slack direction. The side edge of 30A ′ hits the contact surface portion 10D of the locking recess 10C to prevent loosening.

  Since the three embodiments described above have the same effects as those of the first embodiment, a detailed description thereof will be omitted.

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 a nut in the said embodiment. It is a figure which shows the volt | bolt and latching recessed part in the said embodiment. It is a figure for demonstrating the loosening prevention effect | action of the said embodiment. It is a figure which shows 2nd Embodiment. It is a figure which shows 3rd Embodiment. It is a figure which shows 4th Embodiment. It is a figure which shows the slack stopper plate in the said embodiment.

Explanation of symbols

10 Bolt (Male Thread Member) 10B Male Thread 10C Locking Recess 10D Contact Surface 10E Relief Surface 20 Nut (Female Thread)
20A Female thread 20B Top surface 30 Slack stop plate 30A, 30A 'Locking convex part 30B Pressing piece part

Claims (1)

A screw loosening prevention structure configured to prevent the screwed male and female screw members (10, 20) from loosening,
The male screw member (10) is formed with a locking recess (10C) at least in the threaded portion of the female screw member (20) in the axial direction, and the female screw member (20 ) In the slack direction, the contact surface portion (10D) is formed on the lag side, the relief surface portion (10E) is formed on the delay side, and the upper edge line (10F) of the relief surface portion (10E) is formed in a round shape ,
A locking plate (30) is fixed to the top surface (20B) or seating surface of the female screw member (20), and a locking recess of the male screw member (10) is provided on the inner edge side portion of the locking plate (30). A plurality of locking projections (3) that can be fitted into (10C) are formed, and the locking projections (30A) are fitted into the locking recesses (10C) and come into contact with the contact surface portion (10D). While the relative rotation of the female screw member (20) in the slack direction is prevented, the locking projection (30A) is guided by the relief surface portion (10E) and detached from the locking recess (10C). By allowing the female thread member (20) to be elastically deformed, relative rotation in the tightening direction of the female screw member (20) is allowed,
The male screw member (10) is formed by elastically deforming the pressing piece (30B) having a shape that does not fit into the locking convex part (30A) or the locking concave part (10C) formed side by side on the locking convex part (30A). The locking projection (30A) is inserted into the threaded flank of the screw having the locking recess (10C), and the female thread member (20) is given rotational resistance. Screw loosening prevention structure.

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