JP2016125622A - Special double hard-lock nuts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard-lock nut [registered trademark] not producing any looseness even though its working is easy to perform and its seat surface is unstable.SOLUTION: This invention has a structure comprising an upper nut 3 and a lower nut 2. The lower nut 2 is provided with a salient 22 protruded toward the upper nut 3. The upper nut 3 is provided with a recess part 32 to which the salient 22 is fitted. The salient 22 is set to be eccentric with respect to a threaded hole 21, the eccentric salient 22 is fitted to the recess part 32 to cause the upper nut 3 and the lower nut 2 to be depressed in a horizontal direction from each other. A thin-wall part of the salient 22 is deformed in an inward radial direction, the thread at the inner surface is bulged out in the inward radial direction. Even when the lower nut 2 is independently engaged in thread with a thread shaft 1, the lower nut 2 is fastened against the thread shaft 1 in a slight eccentric state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a locking special double nut.

  The applicant of the present application has been developing a special locking nut that exhibits a high locking function, and has been disclosed in, for example, Patent Document 1 below.

  As shown in FIG. 5, the hard lock nut (registered trademark) includes a lower nut 2 and an upper nut 3 having screw holes 21 and 31 into which a screw shaft 1 of a bolt is screwed. The upper nut 3 is provided with a convex portion 22 protruding upward, and the lower surface of the upper nut 3 is provided with a concave portion 32 into which the convex portion 22 of the lower nut 2 is fitted. The outer peripheral surface of the convex portion 22 and the inner peripheral surface of the concave portion 32 are formed in a tapered shape. Further, the convex portion 22 is slightly eccentric with respect to the screw hole 21, and the upper and lower nuts 2, 3 are horizontally aligned with each other along the eccentric direction by the eccentric fitting between the convex portion 22 and the concave portion 32 of the upper nut 3. More specifically, a horizontal force in the direction opposite to the eccentric direction (left direction in the figure) acts on the lower nut 2, and more specifically in the eccentric direction (right direction in the figure) on the upper nut 3. A horizontal force acts, and a large locking action is generated by these horizontal forces.

  The screw holes 21 and 31 are respectively radially inward from the outer peripheral surface of the convex portion 22 or the inner peripheral surface of the concave portion 32, and the convex portion 22 is eccentric with respect to the screw hole 21. The thickness of the convex portion 22 is gradually increased toward the eccentric direction (right direction in the figure) of the convex portion 22 with respect to the screw hole 21, and a part of the circumferential direction opposite to the eccentric direction. The convex part 22 is the thinnest in the left part of the figure.

Japanese Patent Publication No. 3-526

  In general, the female thread effective diameter of the screw hole of the nut is made slightly larger than the male thread effective diameter of the screw shaft of the bolt, and there is a slight amount of play between the bolt and the nut. The same applies to the upper and lower nuts in the hard lock nut.

  When the lower nut 2 of the hard lock nut is first fastened and fixed to the screw shaft 1 with an impact wrench or the like, the centripetal action caused by the contact between the screw shaft 1 and the screw thread flank 21 as shown in FIG. The lower nut 2 is mounted concentrically with respect to the screw shaft 1, and the upper flank of the screw hole 21 and the lower flank of the screw shaft 1 are strongly pressed, and the lower flank of the screw hole 21 and the screw shaft 1 are pressed. There is play between the upper flank and the upper flank.

  Thereafter, when the upper nut 3 is fastened to the screw shaft 1 and the concave portion 32 of the upper nut 3 and the convex portion 22 of the lower nut 2 are fitted, a large horizontal force in the right direction in the figure is generated in the upper nut 3. The lower nut 2 generates a large horizontal force in the left direction, but the lower nut 2 is in contact with the lower surface of the lower nut 2 with respect to the seating surface of the mounted member A and the above. Since the position of the lower nut 2 with respect to the screw shaft 1 is firmly fixed by contact between the flankes, the lower nut 2 does not move eccentrically in the horizontal direction with respect to the screw shaft 1, and accordingly, the convex portion 22 and the concave portion 32. Taper fitting in a slightly eccentric state. Therefore, as shown in the drawing, the upper nut 3 is fastened and fixed with a relatively large gap between the upper surface of the lower nut 2 and the lower surface of the upper nut 3.

  Even in such a fastened state, a large horizontal stress is accumulated in the screw shaft 1 and the upper and lower nuts 2 and 3 due to the so-called wedge action by the taper fitting, thereby exerting a strong loosening prevention action.

  However, when a hard lock nut is used for a net fence or the like installed along a railroad track, the attached member A itself such as a net fence with which the lower surface of the lower nut 2 abuts is subjected to vibrations, strong winds, etc. As a result of the vibration or deformation in the axial direction with respect to the screw shaft 1, the lower nut 2 may be lifted from the seating surface of the mounted member A as shown in FIG. When the lower nut 2 is thus lifted from the seating surface, the lower nut 2 is slightly left along the flank by the amount of play of the screw shaft 1 on the contact portion side of the convex portion 22 and the concave portion 32. Since the flank is allowed to move obliquely upward and the flank has a smaller angle with respect to the horizontal than the inner peripheral surface of the recess 32, the pressing force of the contact portion between the protrusion 22 and the recess 32 is released, and the loosening In some cases, the stopping action disappeared and loosening occurred.

  To solve this problem, as shown in FIG. 7, the upper and lower nuts 2 and 3 are screwed together to the screw shaft 1 together with the convex portion 22 and the concave portion 32 fitted to some extent. After the bottom surface of the lower nut 2 is brought into contact with the seat surface (see FIG. 7B), the lower nut 2 is first fastened with a predetermined tightening torque, and then the upper nut 3 Is proposed to the user with a predetermined tightening torque (see FIG. 7C). According to this construction method, the lower nut 3 is fastened with a slight eccentricity with respect to the screw shaft 1, and even if the lower nut 3 is lifted from the seating surface, a large slack is caused by the eccentric fitting. The stopping action can be maintained.

  However, this construction procedure is laborious, and when several hundreds to thousands of nuts need to be constructed, the construction period is prolonged and the construction cost is increased, so some improvement has been demanded.

  Accordingly, an object of the present invention is to provide a hard lock nut that is easy to construct but does not loosen even when the seating surface is unstable.

  In order to achieve the above object, the present invention takes the following technical means.

  That is, the present invention is composed of a lower nut and an upper nut having screw holes into which the screw shafts of bolts are screwed, and the screw holes of these upper and lower nuts are formed to have a slight play with respect to the screw shafts. One of the two is provided with a convex portion protruding in the axial direction toward the other and having a tapered outer peripheral surface, and the other of the upper and lower nuts is provided with a concave portion for fitting the convex portion, and is provided on the lower nut. The projecting portion or the recessed portion is eccentric with respect to the screw hole of the lower nut, and the upper and lower nuts are pressed against each other in the horizontal direction along the direction of the eccentricity by the eccentric fitting of the projecting portion and the recessed portion. In the special double nut for preventing locking, the lower nut is preliminarily eccentrically screwed with respect to the screw shaft in the direction in which the lower nut is pushed during the eccentric fitting. screw It is characterized in that the circumferential portion of the threads of the upper side portion of bulges radially inward as compared to other portions.

  According to such a special double nut for preventing loosening of the present invention, when the lower nut is screwed onto the screw shaft, the lower portion of the screw hole of the lower nut can be easily screwed by hand. After the upper part of the screw hole of the lower nut is screwed onto the screw shaft, a predetermined pre-leveling torque is generated. In this state, tightening with an impact wrench or the like will tighten the lower nut to the predetermined fastening completion position. It can be quickly concluded. Moreover, when the part of the expanded circumferential direction abuts on the screw shaft, the lower nut is drawn toward the partial side of the circumferential direction and fastened in a state slightly decentered with respect to the screw shaft. After that, the upper nut is tightened to the screw shaft, and when the concave and convex portions of the upper and lower nuts are fitted, the upper and lower nuts are tightened in the state of being eccentric in the opposite horizontal direction with respect to the screw shaft. As a result, a large horizontal force acts on the upper and lower nuts and the screw shaft, and even when the lower nut is lifted from the seating surface, the horizontal force is not released and the loosening prevention operation is maintained.

  In the above-described special locking nut according to the present invention, a method of causing a part of the thread in the circumferential direction of the upper part of the screw hole of the lower nut to bulge radially inward compared with other parts is appropriate. For example, when processing the thread of the screw hole by tapping, it is possible to process only a part in the circumferential direction of the screw hole so that the effective diameter is smaller than other parts by appropriate control of the processing device. it can.

  Further, when the convex portion is provided in the lower nut and the concave portion is provided in the upper nut, the circumferential portion of the convex portion is pressed and deformed radially inward, so that the lower nut A part of the thread in the circumferential direction of the upper portion of the screw hole can be bulged inward in the radial direction as compared with other portions.

  Further, by forming a coating layer made of a material softer than the nut constituent material on the inner surface of the upper side portion of the screw hole of the lower nut, a part of the screw in the circumferential direction of the upper side portion of the screw hole of the lower nut is formed. It is also possible to bulge the mountain inward in the radial direction in comparison with other parts. In this case, the coating layer may be formed relatively thick so that the coating layer is scraped by the male screw of the screw shaft when screwed onto the screw shaft.

  According to the present invention, it is possible to provide a hard lock nut that is easy to construct but does not loosen even when the seating surface is unstable.

FIG. 2A is a cross-sectional view of a process of screwing a lower nut onto a screw shaft, and FIG. 4B is a cross-sectional view when the upper and lower nuts are completely tightened. One embodiment of a lower nut is shown, (a) is a top view and (b) is a half section front view. One Embodiment of a lower nut is shown, (a) is a longitudinal cross-sectional view, (b) is a top view. It is a half section front view of the locking special double nut concerning another embodiment of the present invention. It is sectional drawing which shows a conventional structure. It is sectional drawing which shows the state which the lower nut floated from the seat surface in the conventional structure. It is explanatory drawing of an example of the construction method of a conventional structure.

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

  1 and 2 show a special double nut for preventing loosening according to an embodiment of the present invention. The basic configuration is the same as that of the conventional structure shown in FIG.

  In the present embodiment, as shown in FIG. 2, after the internal thread of the screw hole 21 of the lower nut 2 is processed by tapping with a predetermined inner diameter d1, the thin portion of the eccentric protrusion 22 is slightly inward in the radial direction. By deforming, the inner diameter d2 of the screw hole 21 inside the thin portion is made smaller than the inner diameter d1 of the female thread. Such deformation processing can be performed by an appropriate method such as forging by a forging die. The difference between the female thread inner diameter d1 and the inner diameter d2 of the thin portion is smaller than the eccentric amount D of the convex portion 22 with respect to the screw hole 21, and can be, for example, about half.

  According to this embodiment, when the lower nut 2 is fastened to the screw shaft 1, first, the lower portion of the screw hole 21 of the lower nut 2 is first screwed onto the screw shaft 1 by hand as shown in FIG. The lower nut 2 can be fastened with a predetermined torque using an appropriate tool such as an impact wrench after being screwed together for two to three turns. At the time of such fastening, since the thin portion of the eccentric convex portion 22 is deformed radially inward, the lower nut 2 is opposite to the screw hole 21 in the direction opposite to the eccentric direction with respect to the screw hole 21 on the outer peripheral surface of the convex portion 22. The lower nut 2 is fastened to the screw shaft 1 with a predetermined tightening torque in such an eccentric state.

  Thereafter, the upper nut 3 is fastened to the screw shaft 1 and the convex portion 22 of the lower nut 2 is fitted into the concave portion 32 of the upper nut 3 as shown in FIG. Is set in a state of being eccentric with respect to the screw shaft 1, the convex portion 22 is deeply fitted into the concave portion 32, and the upper and lower flank of the female screw of the lower nut 2 is formed on the thick portion side of the convex portion 22. The upper and lower flanks of the screw shaft 1 are substantially in close contact with the upper and lower flank, and the female screw of the upper nut 3 and the male screw of the screw shaft 1 are in close contact with the upper and lower flank on the thin portion side of the convex portion 22.

  Therefore, even if the lower nut 2 is lifted from the mounted member A, the eccentric fitting force between the convex portion 22 and the concave portion 32 is not released, and no loosening occurs.

  FIG. 3 shows another embodiment of the lower nut 2. In this embodiment, for example, a nylon resin material (66 nylon or the like) is applied over the inner surface of a predetermined range in the circumferential direction on the thin portion side of the convex portion 22. The coating layer 23 is formed by solidifying. The thickness of the covering layer 23 is preferably larger than about half of the eccentric amount D of the convex portion 22 with respect to the screw hole 21. The nut is preferably made of a metal such as SUS.

  FIG. 4 shows a special double nut for preventing loosening according to another embodiment of the present invention. In this embodiment, a convex portion 33 is provided concentrically with the screw hole 31 on the lower surface of the upper nut 3, and A concave portion 24 into which the convex portion 33 is fitted is provided on the upper surface, and the tapered inner peripheral surface of the concave portion 24 is eccentric with respect to the screw hole 21. And the coating layer 23 is formed in the circumferential direction part of the upper side site | part of the screw hole 21 of the lower nut 2 in the eccentric direction other side of the recessed part 24, and, thereby, the effective diameter of the screw hole upper end part of the lower nut 2 is set. The effective diameter of the female screw at the lower side of the screw hole 21 is made smaller and the substantial center of the upper end of the screw hole is slightly in the same direction as the eccentric direction of the recess 24 with respect to the center of the lower side of the screw hole 21. It is eccentric. Also according to the present embodiment, the same effects as those of the embodiment shown in FIG.

  The present invention is not limited to the above-described embodiment, and the design can be changed as appropriate. For example, by attaching and fixing a solid member protruding from the inner peripheral surface of the screw hole to a mounting recess provided in a part of the upper end of the screw hole of the lower nut, the effective diameter of the upper end of the screw hole is reduced to the lower part of the screw hole. It can also be made substantially smaller than the female thread effective diameter of the side part.

Claims (3)

It consists of a lower nut and an upper nut having screw holes into which the screw shafts of the bolts are screwed. These screw holes of the upper and lower nuts are formed so as to have a slight play with respect to the screw shaft, and either one of the upper and lower nuts has the other And a convex portion having a tapered outer peripheral surface is provided and a concave portion into which the convex portion is fitted is formed on the other of the upper and lower nuts, and the convex portion provided on the lower nut or The concave portion is eccentric with respect to the screw hole of the lower nut, and the upper and lower nuts are configured to press against each other in the horizontal direction along the eccentric direction by the eccentric fitting of the convex portion and the concave portion. In special double nut,
A part of the circumferential direction of the upper side portion of the screw hole of the lower nut so that the lower nut is eccentrically screwed with respect to the screw shaft in advance in the direction in which the lower nut is pushed during the eccentric fitting. A special double nut to prevent loosening, characterized by the fact that the screw thread bulges radially inward compared to other parts.   2. The special double nut for preventing loosening according to claim 1, wherein the convex portion is provided in a lower nut, the concave portion is provided in an upper nut, and a circumferential portion of the convex portion is pressed and deformed radially inward. A special double nut for preventing loosening, characterized in that a part of the thread in the circumferential direction of the upper part of the screw hole of the lower nut is bulged inward in the radial direction as compared with other parts.   The special double nut for preventing loosening according to claim 1, wherein a coating layer made of a material softer than a nut constituent material is formed on the inner surface of the upper side portion of the screw hole of the lower nut, whereby the screw hole of the lower nut A special double nut for preventing loosening, characterized in that a part of the thread in the circumferential direction of the upper part of the bulge is bulged radially inward compared with other parts.

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