JP2001200826A - Male screw member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a male screw member which realizes an appropriate fastening by measuring the axial force of the male screw member such as a bolt by ultrasonic wave. SOLUTION: The squareness of the end surfaces of both the end parts of the male screw member to the shaft straight line of the male screw member is set to 0.0005-0.1 mm. Regarding the actual angle θ of the end surfaces of both the end parts of the male screw member to a virtual plane perpendicular to the axis which is perpendicular to the axis of the male screw member, tan θis set to 0.02 or below. The flatness of the end surfaces of both the end part of the male screw member can be set to 0.0005-0.1 mm, and the ten-point average roughness Rz of the end surfaces of both the end parts can be set to 1-15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a male screw member such as a bolt.

[0002]

2. Description of the Related Art An impact wrench or the like that completes tightening when a tightening torque reaches a predetermined value so that a tightening force of a bolt, a nut, or the like does not become excessive or excessive is widely used. However, if the bolts and nuts are not properly engaged or foreign matter is caught, the tightening torque may increase to the set value even if the tightening is not completed, and the tightening may stop. Can occur.

[0003] Instead of or in addition to such a tightening torque, there is also an attempt to complete the tightening by referring to the tensile force (bolt axial force) generated in the bolt shaft when the bolt or nut is tightened. . Therefore, the bolt slightly expands in the axial direction as the bolt axial force increases (the length in the bolt axial direction slightly increases). The extension of the bolt is measured using ultrasonic waves, and the elongation reaches a predetermined value. It is conceivable that the tightening is completed when it becomes. In that case,
Ultrasonic waves are emitted in the axial direction of the bolt, and the axial propagation force of the bolt and thus the axial force of the bolt can be measured by observing the increase in the propagation time of the ultrasonic wave that is repeatedly reflected and reciprocated at both axial end faces of the bolt.

[0004]

However, generally, the end faces at both ends in the axial direction of the bolt are defined by surfaces formed by forging, casting, or the like. It usually has a dimensional form. Therefore, even if the ultrasonic wave is reciprocated in the bolt axis direction, the transmitted ultrasonic wave is reflected obliquely or irregularly with respect to the axial direction at the end face, making it difficult to determine the propagation time, or The error was so large that it could not be put to practical use.

[0005] It is an object of the present invention to provide an identical member which enables the axial force of a male screw member such as a bolt to be measured by ultrasonic waves and realizes proper tightening.

[0006]

According to the present invention, the perpendicularity of each end face of both ends of the male screw member to the axis straight line of the male screw member is 0.0005 to 0.1 mm. In addition, tan θ is set to 0.02 or less with respect to an actual angle θ of each end surface of both ends of the male screw member with respect to a virtual axis perpendicular to the axis of the male screw member. Furthermore, the flatness of each end face of both ends of the male screw member is 0.0005 to 0.5.
1 mm, the ten-point average roughness Rz of each end face of the both ends is 1 to
15 can be set.

Here, the perpendicularity (perpendicularity tolerance) is 0.0005, where each end face of both ends of the male screw member such as a bolt is perpendicular to the axis of the male screw member (axial straight line: datum straight line).
It means defined between two parallel virtual planes separated by 〜0.1 mm (see JIS B 0021).
When the squareness is within this range, the ultrasonic waves and the like are reflected well at each end face at both ends in measuring the tightening axial force of the male screw member by the ultrasonic waves, and the ultrasonic waves and the like are reflected at both ends in the axial direction. It is possible to detect the increase in the propagation time of reciprocating reciprocation due to the elongation of the bolt or the like, and it is possible to complete the tightening when the proper axial force is reached while referring to the axial force of the bolt or the like.

If the perpendicularity exceeds 0.1 mm, the reflection angle of the ultrasonic wave is considerably inclined with respect to the axis of the male screw member.
If the propagation time of ultrasonic waves and the elongation of bolts and the like become difficult to correspond to each other, and the squareness is smaller than 0.0005 mm, the manufacturing process becomes complicated, and the cost of manufacturing equipment increases. Specify the angle.

The actual angle θ of each end face of the both ends of the male screw member with respect to an imaginary (geometric) axis perpendicular plane perpendicular to the axis of the male screw member is set so that tan θ is 0.02 or less. This makes it possible to accurately repeat the reflection of ultrasonic waves or the like for measuring the axial force of the male screw member, and to more accurately set the measurement of the axial force of a bolt or the like and, consequently, the completion time of the tightening. Tanθ of the actual angle θ of each end face
Is greater than 0.02, the deviation between the reflection direction of the ultrasonic wave reflected at each of the end faces and the axial direction of the male screw member increases, and the propagation time of ultrasonic waves or the like increases, and Since it is difficult to judge whether it is caused by elongation due to a tensile force (axial force) acting in the axial direction or due to oblique reflection of ultrasonic waves or the like, the value is set to the range of tan θ described above.

Further, the flatness is represented by the distance between the two parallel planes when the distance between the two parallel planes is minimized when each end face of both ends of the male screw member is sandwiched between the two parallel geometric planes. (See JIS B 0621). And the flatness of each end face of both ends of the male screw member is 0.0005 to 0.5.
When the length is set to 1 mm, when an ultrasonic wave or the like is repeatedly propagated in the axial direction for measuring the axial force of the male screw member and the propagation time is increased, the reflected waves on both end surfaces are hardly diffused, and the propagation becomes difficult. The directivity of the signal is improved, and the reliability of the axial force measurement is improved. When the flatness exceeds 0.1 mm, the ultrasonic wave is dispersed by the so-called undulation of the male screw member, and it becomes difficult or ambiguous to determine which signal wave the propagation time is to be observed in, and conversely, it is less than 0.0005 mm. Therefore, the manufacturing process becomes complicated, and the cost of the male screw member increases. Therefore, it is desirable to set the flatness within the above range.

In addition, when the ten-point average roughness Rz of each end face of both ends of the male screw member is set to 1 to 15, when the ultrasonic force or the like is used for measuring the axial force, the ultrasonic wave or the like is irregularly reflected at each end face. As a result, the directivity and strength of a signal wave for detecting an increase in propagation time of an ultrasonic wave or the like increase, and a highly reliable axial force measurement becomes possible. When the above-mentioned surface roughness Rz is 15 or more, signal waves such as ultrasonic waves are irregularly reflected at each end face to reduce the directivity and intensity of the signal. When the above-mentioned Rz is 1 or less, processing steps are complicated and costly. Therefore, it is desirable to define the surface roughness Rz in the above range.

When tightening while measuring the axial force of a male screw member such as a bolt, the means for measuring the axial force is not limited to ultrasonic waves. As a thing to use, it is also possible to use a predetermined radio wave, vibration wave, shock wave, etc.
It is also effective for axial force measurement media other than ultrasonic waves.

[0013]

Embodiments of the present invention will be described below with reference to embodiments shown in the drawings. A bolt 1 as a male screw member shown in FIG. 1 has a head 2 and a shaft 3. Each of the end faces of both ends of the bolt, in other words, the end face 4 of the head 2 and the end face 5 of the shaft 3 have a perpendicularity to the bolt axis A of 0.0.
005 to 0.1 mm, especially 0.0
It is formed in the range of 0.01 to 0.08 mm, particularly 0.01 to 0.07 mm. That is, as shown in FIG. 2, each of the end faces 4 and 5 of the bolt 1 is perpendicular (perpendicular to) the bolt axis A and two parallel virtual planes P separated by the range (distance t).
1, defined between P2.

As shown in FIG. 3, an angle (intersecting angle) θ between the end faces 4 and 5 at both ends of the bolt 1 with respect to a geometric plane P perpendicular (perpendicular) to the bolt axis A is tan
θ (b / a in the figure) is set to 0.02 or less (0.00003 as the lower limit), and especially 0.00006 to 0.0
16, particularly in the range of about 0.0006 to 0.014. If this is converted to θ (it can also be called tan ⁻¹ θ), θ or tan ⁻¹ θ is 1.2 degrees or less (the lower limit is 0.001 degrees), and especially 0.003 to 0.9 degrees. ,
In particular, it can be set to about 0.03 to 0.8 degrees.

The flatness of each of the end faces 4 and 5 at both ends of the bolt 1 is 0.0005 to 0.1 mm, particularly 0.001 to 0.08, especially 0.002 (or 0.02 mm).
1) It is set to about 0.07.

Further, the end faces 4, 5 at both ends of the bolt 1 are provided.
Has a surface roughness of 15 or less in ten-point average roughness Rz (for example, 1 as a lower limit value).
5 to 11. In particular, Rz is 2 to 8 (further 5 to 5
7) is desirable.

By determining the perpendicularity, flatness, and surface roughness of both end surfaces 4 and 5 of the bolt as described above, for example, as shown in FIG. When the nut 7 is tightened, the tightening process or operation can be performed with a tightening device or tool such as an impact wrench while measuring the axial force Tf (FIG. 5) of the bolt using ultrasonic waves. The bolt axial force Tf is a tensile force generated in the axial direction of the bolt by tightening. If the tensile force (bolt axial force) increases, the bolt slightly expands in the axial direction. Bolt axial force is measured indirectly by detecting the increase in
Tightening is completed when a predetermined bolt axial force is reached.

For example, as shown in FIG.
The detecting unit (transducer) 11 of the ultrasonic bolt axial force meter 10 is applied to either the head end surface 4 or the shaft end surface 5 (the head end surface 4 of the bolt 1 if the nut 7 is tightened). Emits ultrasonic waves in the axial direction of the bolt. The ultrasonic wave is reflected by the shaft end surface 5 of the bolt 1 and returns to the bolt head side,
Both end faces 4, 5 are reflected at head end face 4 again.
To reciprocate (for example, several hundred to several thousand times).
By measuring the propagation time of this ultrasonic wave, the elongation of the bolt 1 due to the tightening, and thus the axial force of the bolt 1 can be measured. In the case of FIG. 4A, one transducer 1 is used.
1 transmits and receives an ultrasonic wave, but as shown in FIG. 3B, transmitting and receiving transducers 11 and 12 may be applied to both end surfaces 4 and 5 of the bolt 1, respectively. Even in this case, a change in the propagation time of the ultrasonic wave that has reciprocated many times is observed.

When the axial force of a bolt is to be measured using ultrasonic waves, if the perpendicularity of both end surfaces 4 and 5 of the bolt deviates from the aforementioned range as shown in FIG. The sound wave is reflected so as to be inclined in the bolt axis direction, and is also reflected on the side surface of the bolt shaft portion, so that the propagation path becomes longer. Therefore, it is difficult to distinguish the increase in the propagation time due to the elongation of the bolt. Also, as shown in FIG.
If the flatness deviates from the above-mentioned range, the reflected wave of the ultrasonic wave is dispersed on the undulating end face, and it becomes difficult to grasp the propagation time of the ultrasonic wave. Further, when the surface roughness Rz of the both end surfaces 4 and 5 of the bolt 1 is out of the above range as shown in FIG. 3C, the ultrasonic wave is irregularly reflected on the both end surfaces 4 and 5 and its intensity is reduced (in other words, attenuated). Therefore, it is difficult to generate a reciprocal wave having directivity of ultrasonic waves.

In the above embodiment, the squareness, flatness, and surface roughness of both end faces of the bolt are synergistically defined.
With the detection of the reflection of the ultrasonic wave and, consequently, the propagation time, the ultrasonic wave is easy to follow along the bolt axis direction and is hard to disperse, and the irregular reflection is suppressed, so that the bolt axial force can be measured and its accuracy is high. Become.

In the above description, a general bolt is taken as an example, but the present invention can be applied to other screw members such as a bolt without a head.

As shown in FIG. 7, a concave portion 56 is formed on the head-side end surface of the bolt 76, and a concave portion 48 is also formed on the shaft-side end surface. A plane substantially perpendicular to the bolt axis, the same applies hereinafter), recess 48
Can be used as a reference plane on the shaft portion side. In this case, the width of the bottom surface 57 on the head side is, for example, substantially equal to or larger than the plane on which the cross section d of the bolt shaft is projected, with the bolt axis as the center.
Alternatively, it can be narrower. Further, the bottom surface 49 of the concave portion 48 on the shaft portion side is smaller than the shaft portion cross section d.
The relationship between the diameter d1 of the reference plane 57 on the head side (a diagonal line indicating the size of the polygon in the case of a polygon) and the diameter d2 of the bottom surface 49 on the shaft side is d1> d2, d1 <d2, or d1 =
Any of d2 is possible.

As shown in FIG. 7B, the width (d1) of the reference plane 57 on the head side of the bolt 77 and the width (d2) of the reference plane 49 on the shaft side are coaxial with the bolt axis. Is present in a region (d1 = d2) equal to the position of (1), ultrasonic waves can be repeatedly reflected and reciprocally propagated in a region inside a cylindrical (for example, cylindrical) connecting these reference planes 57 and 49. Therefore, the reference plane necessary for the reflection of the ultrasonic wave can be minimized, and the formation area of the high-precision reference plane can be small, so that the processing is easy and the manufacturing cost can be suppressed.

As shown in FIG. 7 (c), the shaft end surface 36 of the bolt 78 is not formed as the bottom surface of the concave portion, but the entire shaft end surface is formed as a flat surface to serve as the reference plane 36. The concave portion 56 as described above is formed on the head side, and the bottom surface 57 can be used as a reference plane. In this case, the width d1 of the bottom surface 57 can be formed equal to or slightly larger than the cross section d of the bolt shaft portion. In this case, the ratio of the width of d1 to d is, for example, d1 = 0.7d
1.3d, especially 0.9d to 1.1d. As shown in FIG. 14A, concave portions 56 and 4 are provided at both ends.
8, the ratio of the size of each reference plane is d1 =
0.5d2 to 2d2, especially 0.7d2 to 1.3d2, especially about 0.8d2 to 1.2d2, and d1 = d2
Is substantially equivalent to the example shown in FIG.

Further, as shown in FIG. 7D, the bottom surface 57 of the concave portion 56 on the bolt head side is made as large as possible, and the bottom surface 49 of the concave portion 48 on the bolt shaft side is made as large as possible. be able to. In other words, it means that the raised portion 59 of the concave portion 56 and the raised portion 50 of the concave portion 48 are minimized. In this case, the reference planes 57 and 49 that contribute to the reflection of ultrasonic waves and the like can be widened.

The raised portion 59 of the concave portion 56 and the raised portion 50 of the concave portion 48 are removed by, for example, a double-ended grinding machine as described above, and as shown in FIG. It is possible to form a reference plane 57 that is substantially flat throughout the entire surface by eliminating the concave portion on the end face, and eliminates the concave portion on the shaft portion side as well. Such raised portions 59 and 50 in the post-process.
7 (d) when removal by grinding or the like is planned.
By minimizing the raised portions 59 and 50 as described above, the amount of cutting by grinding can be reduced, and grinding and the like in a later step can be easily performed. In addition, the swelling part 5
The reference plane 5 formed by forging, for example, cold forging (hot forging and warm forging can also be adopted), together with the cuts 9 and 50.
7, 49 can also be ground with a slight grinding allowance to finally adjust the surface roughness, flatness and the like. Even in this case, since a plane with high accuracy such as a squareness is formed in advance by cold forging, a reference plane with higher surface accuracy can be obtained by grinding or the like.

Further, as shown in FIG. 8 (b), the reference planes 57 and 49 (or the surfaces thereof were finished by grinding or the like) by cold forging or the like in the state where the raised portions were removed as described above. As for the widths d1 and d2 of the surface) about the bolt axis, the ratio between d1 and d2 can be determined as described in the above-described recesses 56 and 48.

Further, instead of the idea of forming a reference plane by cold forging as described above, d1 is applied to the bolt head by finishing such as grinding from the rough end face of the bolt head and the end face of the shaft as in the prior art. It is also possible to form a d2 reference plane on the bolt shaft portion, respectively.

[Brief description of the drawings]

FIG. 1 is a front view showing a bolt according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a perpendicularity of an end face of a bolt.

FIG. 3 is a diagram illustrating an angle of an end face of a bolt with respect to a geometric reference plane.

FIG. 4 is a diagram illustrating an example of measuring an axial force of a bolt.

FIG. 5 is a diagram conceptually showing propagation (reflection) of an ultrasonic wave.

FIG. 6 is a diagram conceptually showing propagation (reflection) of an ultrasonic wave in relation to a squareness of an end face, flatness, and surface roughness.

FIG. 7 is a process chart showing some specific examples of the bolt of the present invention.

FIG. 8 is a view schematically showing still another example of FIG. 7;

[Explanation of symbols]

 1 bolt (male screw member) 4 end face (of bolt head) 5 end face (of bolt shaft)

Claims (8)

[Claims] 1. The perpendicularity of each end face of both ends of the male screw member to the axis of the male screw member is 0.0005 to 0.1 mm.
A male screw member characterized by the above. 2. The perpendicularity of each end face of both ends of the male screw member to the axis of the male screw member is 0.0005 to 0.1 mm.
And the flatness of each end face of the both ends is 0.000
A male screw member having a thickness of 5 to 0.1 mm. 3. The perpendicularity of each end face of both ends of the male screw member to the axis of the male screw member is 0.0005 to 0.1 mm.
And a ten-point average roughness Rz of each end face of the both end portions is set to 1 to 15. 4. The perpendicularity of each end face of both ends of the male screw member to the axis of the male screw member is 0.0005 to 0.1 m.
m, and the flatness of each end face of the both ends is 0.00
A male screw member characterized in that the ten-point average roughness Rz of each end face of the both end portions is 1 to 15. 5. The tan θ is set to 0.02 or less with respect to an actual angle θ of each end face of both ends of the male screw member with respect to an imaginary plane perpendicular to an axis of the male screw member. Screw member. 6. An actual angle θ of each end face of both ends of the male screw member with respect to an imaginary plane perpendicular to the axis of the male screw member, tan θ is set to 0.02 or less, and A male screw member characterized in that the flatness of the end face is 0.1 mm or less. 7. An actual angle θ of each end face of both ends of the male screw member with respect to an imaginary axis perpendicular plane perpendicular to the axis of the male screw member, tan θ is set to 0.02 or less, and A male screw member having a ten-point average roughness Rz of 15 or less on an end face. 8. An actual angle θ of each end face of both ends of the male screw member with respect to an imaginary axis perpendicular to the axis of the male screw member, tan θ is set to 0.02 or less, and each of the both ends is A male screw member, wherein the flatness of the end face is 0.1 mm or less, and the ten-point average roughness Rz of each end face of the both ends is 15 or less.