JP2006292717A - Bolt and manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape of the bolt head section and end face of an inexpensive axial force measuring bolt of which axial force can be measured by ultrasonic waves or the like, and its manufacturing method. <P>SOLUTION: The bolt head section is polygonal, the inside of the upper face of the head section has a polygonal groove of which top position is matched to an external polygonal shape, and the inside of the polygonal groove inside the upper surface has a flat part. The height of the polygonal external part of the upper surface of the bolt and the height of the flat part inside the polygonal groove are the same, or the flat part inside the polygonal groove is slightly higher. The head section of the bolt is processed in 2-4 steps in a cold forging machine, and simultaneously the shaft section and a cut flat part of the bolt tip are formed. On the tip of the bolt, a C face part is formed by screw-processing the shaft section from a perpendicular flat face by rolling, simultaneously remaining the flat part inside the tip, and extending the outside. The axial force measuring bolt can be clamped using an axial force measuring instrument with ultrasonic waves or the like or an ultrasonic type axial force control clamping machine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an axial force measurement bolt using ultrasonic waves or the like.

  Conventionally, as an axial force measuring bolt, it is common to measure an axial force on a bolt head plane and an end plane using an axial force measuring instrument such as an ultrasonic wave.

  However, in order to use an axial force measuring instrument such as an ultrasonic wave, the two flat portions are formed by cutting and polishing, or the two flat portions are formed by cold forging. Is costly, and in order to form a flat part in the two-step process of cold heading, the diagonal tension of the head hexagon is worsened. Although it is possible to form a recess-shaped flat portion and make it diagonal, the multi-step process is expensive, and the recess shape is limited to the size of the sensor part such as ultrasonic waves entering the recess . Also, when axial force is applied, there may be errors in axial force measurement due to the warp on the flat part of the head, and the C surface part is formed at the bolt end due to insertability, but in the case of cold heading, it is not a multistage process. And a plane part and a C surface part cannot be formed. Or it became a cutting process etc., and the axial force measuring bolt had a problem that the cost was still high.

Accordingly, an object of the present invention is to invent a bolt head and end shape and manufacturing method at low cost and to provide an inexpensive axial force measuring bolt.

  As a means for solving the above-mentioned conventional problems, the present invention has a polygonal groove in which the bolt head has a polygonal shape, the top surface of the head is aligned with the apex position of the external polygonal shape, The polygonal shape is formed in the range of 6 to 12, and a polygonal or circular plane portion is formed inside the polygonal groove inside the upper surface. The height of the polygon outer surface of the bolt upper surface and the polygon groove inner plane portion are the same or the position of the polygon groove inner plane portion is slightly higher, and the diameter of the polygon groove inner plane portion is from 1/5 to 4 / The polygonal groove bottom surface is inclined in the range of −30 ° to + 30 ° to the head upper surface side with respect to the shaft portion, and the polygonal groove depth is formed within ½ of the head height. Yes. The heads of these bolts are processed in a cold forging machine in two to four steps, and at the same time, the shaft and the cut flat portion of the bolt tip are formed. The cut plane part has a parallelism with the head plane part of 0.1 mm or less and an average roughness Rz of 12.5 or less. The front end portion of the bolt is formed by rolling from a vertical plane, and at the same time as the threading of the shaft portion, the flat surface portion is left inside the front end, and the C surface portion is formed while extending the outside. The bolt of the present invention is formed by cold forging 2 to 4 step process and rolling process to produce an inexpensive axial force measuring bolt.

The axial force measuring bolt according to the present invention uses a cold forging machine to form a polygonal groove in which the top surface of the head is aligned with the outer polygonal shape on the polygonal head of the bolt in a two-stage process and a flat portion on the inside thereof. By making the head polygon diagonally stretched sufficiently, the height of the polygon outer surface of the bolt upper surface and the polygon groove inner plane part is the same or slightly higher, so it can be measured regardless of the size of the sensor such as ultrasonic waves, Further, when an axial force is applied, the warp is absorbed by the groove having a polygonal shape on the head, and the axial force can be measured with an ultrasonic wave or the like that is not affected by the warp on the flat portion. In addition, the cut plane part of the shaft part and the tip part is formed at the same time in the two-stage process, and the C surface part is formed while the shaft part and the tip part are formed by rolling, and at the same time leaving the maximum flat part inside the tip part while screwing. As a result, the area of the flat portion inside the tip can be made larger than that of the conventional C-face machining, so that the axial force measurement with ultrasonic waves is more accurate than the conventional C-face machining, and the flat portion of the tip is located inside. Since it is formed, scratches such as hammering are hardly scratched, so that the influence of reflection noise due to hammering when measuring the ultrasonic axial force is reduced. The bolt of the present invention can be manufactured as a normal bolt because the cost is not much different from that of a normal bolt, and can be used as a normal bolt. In that case, the axial force measurement for inspection or the like can be performed at any time. Also, if an ultrasonic axial force control tightening machine is used, stable axial force tightening is possible.

Embodiments of the present invention will be described below.
A bolt according to an embodiment of the invention is shown in FIG. The bolt head shown in FIG. 1 has a hexagonal shape (5), and a hexagonal groove (3) in which the top surface of the head is aligned with the outer hexagonal shape is formed inside the top surface. The bottom surface of the shaped groove (3) is inclined within −30 ° (Xa) to + 30 ° (Xb) on the upper surface side of the head with respect to the shaft portion. The hexagonal groove depth (Ya, Yb, Yc) should be within ½ of the head height. A polygonal or circular plane portion (6) is formed inside the hexagonal groove inside the bolt upper surface, and the diameter of the plane portion (6) is 1/5 to 4/5 of the hexagonal outer two-surface width. Range. The heights of the hexagonal exterior (5) and the hexagonal groove inner plane part (6) on the upper surface of the bolt are the same or the hexagonal groove inner plane part (6) is slightly higher. The manufacturing method of the said bolt is processed in a 2-4 step process in a cold forging machine, and simultaneously forms a cut plane part (4a) of a shaft part and a tip part. The cut plane part has a parallelism with the head plane part of 0.1 mm or less and an average roughness Rz of 12.5 or less. After that, by rolling the shaft part (2) and the vertical cut plane (4a) perpendicular to the tip part, while screwing the shaft part (2), the plane part (4b) remains at the maximum inside the tip part and the outside is extended. However, the C surface portion (7) is formed.

The bolt head shown in FIG. 1 has a hexagonal shape (5), and the upper surface of the head has a hexagonal groove (3) in which the apex position is aligned with the outer hexagonal shape. Each corner has a slight R shape for the die life. The hexagonal groove bottom surface angle is preferably within the range of −30 ° (Xa) to + 30 ° (Xb) to the top surface of the head with respect to the shaft portion, preferably + 1 ° to + 2 °, and the inside is deepened and the outside is shallowed. Reflection noise at the time of ultrasonic axial force measurement is reduced, and the diagonal tension (8) of the hexagonal head is improved. The hexagonal groove depth (Yb) is within ½ of the head height, preferably about ８. The inside of the hexagonal groove inside the bolt upper surface is formed with a polygonal or circular, preferably circular flat surface portion (6), and the diameter of the flat surface portion (6) is 1/2 of the hexagonal outer surface width. The range is 5 to 4/5, preferably about 1/2. The height of the hexagonal exterior (5) on the upper surface of the bolt and the hexagonal groove inner flat surface portion (6) are the same or preferably the hexagonal groove inner flat surface portion (6) is slightly higher. In the cold forging machine, the bolt is preferably processed in a two-stage process, and at the same time, a shaft plane and a cut plane portion (4a) at the tip are formed. The cut plane part has a parallelism with the head plane part of 0.1 mm or less and an average roughness Rz of 12.5 or less. After that, by rolling the shaft part (2) and the vertical cut plane (4a) perpendicular to the tip part, while screwing the shaft part (2), the plane part (4b) remains at the maximum inside the tip part and the outside is extended. However, since the C surface portion (7) is formed, the area can be made larger than that of the tip flat surface portions (44) and (444) of conventional C surface processing, and the axial force measurement using ultrasonic waves or the like becomes accurate.

The present invention is not limited to the embodiment shown in the drawings, and various modifications can be made without departing from the scope of the present invention. For example, although it is a hexagonal bolt in one embodiment of the present invention, a polygonal bolt may be used if the outer polygonal shape and the inner groove polygonal shape are in the same apex position within a range of 6 to 12 corners. Each corner portion of the inner groove polygonal shape may have a slight R shape for mold life. The inner groove bottom surface angle is used to reduce malfunction of the reflected wave of the ultrasonic wave. Therefore, the angle within the range of −30 ° to + 30 ° may be changed to the optimum angle according to the bolt shape (length, diameter, etc.). Also, the head neck side may or may not have a collar or flange, and a washer may or may not be incorporated. The flat surface inside the hexagonal groove inside the bolt upper surface may be polygonal on the outer side and polygonal or circular on the inner side. The bolt end face portion of the bolt head of the present invention may be flat or may be provided with a C surface portion that leaves the flat portion at the maximum inside the tip by rolling. When the C surface part that leaves the maximum flat part inside the tip by the rolling process of the present invention is attached to the bolt end surface part, the area can be made larger than the tip flat part of the conventional C surface processing, and ultrasonic waves, etc. Therefore, the bolt head may be a conventional polished bolt or a flat portion of a conventional recess cold work.

1 to 6 show an embodiment of the present invention. Front view of the bolt of the present invention Top view of the bolt of the present invention AA sectional view in FIG. Front view of conventional grinding bolt Front view of conventional recessed bolt Top view of conventional recessed bolt 2 is a cross-sectional view taken along the line AA in which the bottom surface of the polygonal groove of the bolt of the present invention in FIG. 2 is a cross-sectional view taken along the line AA in which the bottom surface of the polygonal groove of the bolt of the present invention in FIG. Sectional view of the inner flat surface portion and C surface portion in the rolling process of the head flat shape of the conventional polishing bolt or the like and the tip of the present invention Sectional view of the inner flat surface portion and the C surface portion in the rolling process of the head flat shape of the conventional recessed bolt and the present invention tip Sectional view of the flat part and C-plane part of a conventional grinding bolt Sectional view of the inner flat surface and C surface of the conventional recessed bolt Cross-sectional view of the inner flat surface portion and C surface portion of the bolt of the present invention Rolling process front side view of the bolt of the present invention Rolling side view of the bolt of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Head part 2 Bolt part 3 Thread part 3 Hexagonal groove part 4a Plane part 4b before tip rolling processing Rolling end face plane part 5 Hexagonal outside 6 Head hexagonal groove inner plane part 7 Tip rolling process C surface portion 8 head hexagonal diagonal tension portion 11 head of conventional polishing bolt 22 screw portion 44 polishing end surface flat portion 55 hexagonal trim outer portion 66 head polishing flat portion 111 cold heading processing head of conventional concave bolt Portion 222 Threaded portion 444 Cold forging end face flat portion 555 Hexagonal recess-shaped outer surface 666 Hexagonal recess-shaped flat surface portion Xa Angle of the bottom of the polygonal groove (within −30 ° on the upper surface of the head relative to the shaft portion)
Xb Reverse angle of the bottom of the polygonal groove (within + 30 ° on the top side of the head relative to the shaft)
9a Screw part C surface part simultaneous rolling process die fixing side 9b Screw part C surface part simultaneous rolling process die moving side Yc Hexagonal groove depth Ya Xa side hexagonal groove maximum depth Yb Xb side hexagonal groove maximum depth The

Claims (10)

It is a bolt that can measure axial force with ultrasonic waves, etc., the bolt head has a polygonal shape, and the top surface of the head has a polygonal groove with the apex position aligned with the outer polygonal shape inside the top surface of the head Features bolts. The bolt according to claim 1, wherein the polygonal shape is formed in a range of 6 to 12. The bolt according to claim 1 or 2, wherein a polygonal or circular plane portion is formed inside the polygonal groove inside the bolt upper surface. The bolt according to any one of claims 1 to 3, wherein the height of the polygonal outer surface and the polygonal groove inner plane part on the upper surface of the bolt are the same or the polygonal groove inner plane part is slightly higher. The bolt according to any one of claims 1 to 4, wherein a diameter of a polygonal groove inner plane portion on the upper surface of the bolt is in a range of 1/5 to 4/5 of a width of two outer sides of the polygon. The bolt according to claim 1, wherein the bottom surface of the polygonal groove of the bolt is inclined in the range of −30 ° to + 30 ° on the upper surface side of the head with respect to the shaft portion. The bolt according to claim 1, wherein a depth of the polygonal groove of the bolt is within ½ of a head height. The bolt manufacturing method according to claim 1, wherein the bolt is processed in a cold forging machine in 2 to 4 steps. Bolt that can measure axial force with ultrasonic waves, etc., such as the bolt, while the tip of the bolt is rolled from a vertical plane, the flat part is left inside the tip at the same time as the threading of the shaft, and the outside is extended A bolt characterized by forming a C-plane part. The bolt manufacturing method according to claim 9, wherein the shaft portion and the tip portion of the bolt are formed by simultaneous rolling.

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