JP6231790B2 - Locking nut - Google Patents

Description

  The present invention relates to a locking nut, and more particularly, to a nut that can guarantee a guaranteed load performance and has little change over time in the locking performance even when used over a long period of time.

  A method of fastening a material to be fastened using bolts and nuts is adopted in many structures. Bolts and nuts can be simply screwed and tightened to cause loosening due to the depression of the seating surface, roughness of the contact portion of the screw fastening body, initial loosening due to swell or shape error, static fluctuation or dynamic fluctuation of axial force There is a concern that the loosening of the fastening may occur due to the return rotation of the nut caused by the.

  Therefore, various types of loosening prevention structures have been conventionally proposed. For example, a method has been proposed in which a spring washer is fitted to a bolt shaft portion into which a nut is screwed, or rotation of the nut in the loosening direction is prevented by a double nut. Further, a method has been proposed in which a coil spring is tightly wound around a bolt shaft portion into which a nut is screwed to prevent the nut from rotating in the slack direction (Patent Document 1). However, in these methods, when used for a long period of time, once the nut starts to loosen due to vibration or impact, the bolts and nuts are easily loosened.

  On the other hand, a spring housing recess is formed on the top surface of the nut to house the coil spring. When the bolt and nut are rotated in the tightening direction, the coil spring is moved away from the male thread of the bolt to reduce the frictional force and to tighten the bolt. While the bolts and nuts rotate in the loosening direction, the coil springs are closely attached to the male threads of the bolts to increase the frictional force and prevent the bolts and nuts from rotating in the loosening direction. Has been proposed (Patent Documents 2 and 3).

JP 2001-059514 A JP 2003-307210 A JP 2010-007819 A

  Although the locking nuts described in Patent Documents 2 and 3 have been evaluated for the locking performance of the nut, studies on the guaranteed load performance that is basically necessary for the nut have not been made.

  In such a situation, an object of the present invention is to provide a locking nut that can guarantee a guaranteed load performance and has little change over time in the locking performance even when used over a long period of time.

  Therefore, in the locking nut structure according to the present invention, a spring housing recess is formed on the top surface of the nut, and the space between the bottom surface of the spring housing recess and the nut seat surface is JIS B 1181 Annex 1. The nut height is a specified nominal thread diameter, and a female screw is formed from the nut seat surface to the bottom of the spring housing recess, while a coil spring is installed in the spring housing recess. The coil spring has a wire diameter within a range of 0.5 to 0.9 times the male screw pitch of the bolt, and the winding direction is the winding direction of the bolt male screw. One end of the coil spring is equal to the diameter dimension, and one end of the coil spring is finished by open-end grinding. The other end is formed with a locking hook, and the locking hook is formed on the outer end surface of the spring housing recess. It is characterized by being inserted and locked in a blind hole

  In general, nut locking performance is greatly influenced by the axial force of the bolts used in combination, and nuts tightened with an axial force that exceeds the yield point of the bolt will almost never loosen without using a locking structure. Absent. The present invention realizes the prevention of loosening of a nut with a simple and effective structure when the nut is combined with a bolt of an elastic deformation castle whose axial force is below the yield point.

  That is, one of the features of the present invention is that a coil spring is installed in the spring housing recess on the top surface of the nut, and a locking hole at the other end of the coil spring is formed on the outer end surface of the spring housing recess. The point is that it is inserted and locked.

  As a result, when the bolt and nut are relatively rotated in the tightening direction, the coil spring is separated from the male screw of the bolt and the frictional force is reduced, so that the screw male screw is allowed to advance. On the other hand, when the bolt and nut are relatively rotated in the slack direction, the coil spring is brought into close contact with the male screw of the bolt and the frictional force is increased. As a result, the relative rotation of the bolt and nut in the slack direction is suppressed.

  In order to make the coil spring perform the above functions, the coil spring has a wire diameter in the range of 0.5 to 0.9 times the male screw pitch of the bolt, the winding direction is the winding direction of the male screw, and the coil spring The average diameter is equal to the dimension of the effective diameter of the bolt, and it is preferable that one end of the coil spring is subjected to open end grinding.

  The second feature of the present invention is that the space between the bottom surface of the spring housing recess and the nut seat surface is the dimension of the nut height of the nominal thread diameter defined in JIS B 1181 Annex 1. Thereby, the basic guaranteed load performance of the nut can be secured.

  A shape in which a spring housing recess is countersunk on the top surface of the nut, and the height between the bottom surface of the spring housing recess and the nut seating surface is the height of the nut with the nominal diameter of the screw specified in JIS B 1181 Annex 1. The nut blank may be manufactured by cutting, but is preferably manufactured by forging, preferably hot forging, in order to ensure the guaranteed load performance.

It is a figure which shows the partially notched side surface (a) and plane (b) which show the nut blank in preferable embodiment of the locking nut which concerns on this invention. It is a figure which shows the side surface (a) and bottom face (b) of the coil spring in the said embodiment. It is a figure which shows the fastening structure using the locking nut of the said embodiment. It is a principal part enlarged view of FIG.

  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 locking nut according to the present invention. In the figure, a nut blank 10 has a nut top surface 11 formed with a circular spring housing recess 12 having an inner diameter dz, and a portion between the bottom surface of the spring housing recess 12 and the nut seat surface 14 is attached to JIS B 1181. The thread height dimension ml of the nominal thread diameter specified in the book 1 is established, and a female thread is formed in a portion from the nut seat surface 14 to the bottom surface of the spring accommodating recess 12.

  A coil spring 20 is installed in the spring housing recess 12. The coil spring 20 has a wire diameter in the range of 0.5 to 0.9 times the male screw pitch of the bolt 30 and the winding direction is the winding direction of the bolt male screw. Further, one end 21 of the coil spring 20 is finished by open end grinding, the other end is formed with a locking hook 22, and the locking hole 13 is formed on the outer end surface of the spring housing recess 12. In the locking hole 13, a locking hook 22 at the other end of the coil spring 20 is inserted and locked.

  Next, a nut having a nominal screw diameter of M18 will be described as an example. JIS ・ B ・ 1052 ・ 2 Use S45C steel material specified in JIS ・ G ・ 4051 to meet the guaranteed load requirement value and hardness requirement value of strength category 10 specified in Table 5, and call the screw by hot forging. It is forged into a shape having a diameter and height of 18 mm and having a countersink in the screw storage recess on the top surface of the nut, and is tempered from a predetermined hardness HV272 to HV353.

  The depth of the counterbore is about 20% of the total nut height. A locking hole having an inner diameter of 1.52 mm and a depth of 9 mm is machined to fix the torsion coil spring at the end of the nut top surface.

  The coil spring combined with the locking nut blank has a wire diameter of 0.5 to 0.9 times the screw pitch of the bolt combined with the nut, this time 1.47 mm, the winding direction is a right-handed coil, and the average diameter is a bolt. The diameter is approximately equal to the effective diameter of 16,3730 mm, one end is subjected to open end grinding, and the other end is processed to a locking hook.

  A torsion coil spring is set on a nut blank having a countersink formed in the screw storage recess, with the open-end ground end being the bottom side. The locking hook at the opposite end of the coil spring is inserted into a locking hole formed in the top surface of the nut blank.

  The effective height and effective screw length (80% of the nominal diameter) of a nut with a proven track record are ensured, and the mechanical properties of hardness Hv 272 to 335 and guaranteed load stress of 1060 N / mm 2 are satisfied.

  Now, as shown in FIG. 3 and FIG. 4, when the shaft portion 31 of the bolt 30 is inserted into the insertion holes of the fastened members 40, 41, screwed into the above-described locking nut 10, and inserted into the coil spring 20, As a result of the coil spring 20 being separated from the male screw of the bolt 30 and reducing the frictional force, the bolt 30 is allowed to be screwed.

  On the other hand, when the bolt 30 and the nut 10 are relatively rotated in the slack direction, the coil spring 20 is brought into close contact with the male screw of the bolt 30 and the frictional force is increased. As a result, the relative rotation of the bolt 30 and the nut 10 in the slack direction is suppressed. The

  That is, when the bolt 30 is inserted into the nut 10 and tightened with a simple structure in which the coil spring ridge is inserted into the locking hole on the top surface of the nut, the open end grinding of the coil spring 20 fixed to the nut countersink is performed. The end face enters the pitch of the male screw of the bolt 30 and winds around the male screw of the bolt 30 while extending in the axial direction.

  When the bolt 30 is further tightened, the fixed coil spring 20 is deformed in a direction in which the spring is loosened by the frictional force between the bolt 30 and the coil spring 20, that is, in a force direction that expands the diameter of the spring. Can be inserted.

  When the tightening of the bolt 30 is stopped, the frictional force between the bolt 30 and the coil spring 20 is lost, the coil spring 20 is loosened, that is, the diameter of the coil spring 20 is not increased, and the coil spring 20 is bolted by the elastic restoring force of the coil spring 20. 30 is tightened, and the loosening prevention effect is exhibited by the printing force of the coil spring 20 and the bolt 30.

  When the bolt 30 is removed while the coil spring 20 is tightened by the elasticity of the coil spring 20, that is, a loosening force is applied, a printing force is generated between the coil spring 20 and the bolt 30. The generated friction force deforms the coil spring 20 in the tightening direction. Since the coil spring 20 is tightened, the frictional force between the coil spring 20 and the bolt 30 is further increased, and a loosening prevention effect is exhibited.

  When removing the bolt 30 from the nut 10, the nut 10 can be removed by extracting the locking hook 22 of the coil spring 20 fixed to the locking hole 13 of the nut 10. However, since the coil spring 20 is deformed, it cannot be reused.

  Table 1 shows the dimensions of the nut blanks having the respective nominal diameters of M12 to M39, and Table 2 shows the dimensions of the coil springs used for the nut blanks.

DESCRIPTION OF SYMBOLS 10 Nut flank 11 Nut top surface 12 Spring accommodation recess 13 Locking hole 14 Nut seat surface 20 Coil spring 21 End end grinding end 22 Locking hook

Claims (2)

The nut (10) has a spring housing recess (12) having a countersink structure on the top surface (11), and the space between the bottom surface of the spring housing recess (12) and the nut seat surface (14) is JIS B. - 1181 has become the dimensions of the nut the thread height nominal diameter of Annex 1N (ml), the portion of the bottom surface of the nut bearing surface (14) to the spring housing recess (12) while having an internal thread,
The above spring housing recess (12) within which is disposed a coil spring (20) is in the range 0.5 to 0.9 times the external thread pitch diameter of said coil spring (20) is a bolt (30) And the winding direction is the winding direction of the male screw, the average diameter of the coil spring (20) is equal to the effective diameter of the bolt, and one end (21) of the coil spring (20) is open-ended. It has a grinding finish and has a locking hook (22) at the other end, and the locking hook (22) is inserted into the locking hole (13) on the outer end surface of the spring housing recess (12). Is locked,
When the bolt (30) is screwed, the open end ground end of the coil spring (20) enters the pitch of the male screw of the bolt (30) and is held by the male screw of the bolt (30). Is wound around the male screw of the bolt (30) in a state of extending along the bolt shaft portion (31), and the coil spring (20) and the male screw of the bolt (30) with respect to rotation in the slack direction of the bolt (30) A nut for preventing loosening , wherein frictional force is generated between the two to prevent loosening.   A spring housing recess (12) is formed in the nut top surface (11) with a countersink, and the space between the bottom surface of the spring housing recess (12) and the nut seat surface (14) is defined in JIS B 1181 Annex 1. The nut according to claim 1, wherein a nut blank having a shape of a nut height (ml) of a nominal diameter of the screw is manufactured by forging.

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