JP2006055989A - Bolt fastener and bolt fastening method, and bolt plasticity zone fastening determining device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bolt fastener and bolt fastening method for exactly fastening a bolt to a plasticity zone. <P>SOLUTION: The bolt fastener is equipped with a bolt fastening means 1 for fastening the bolt 2, a sensor for detecting elastic waves (acoustic emission) emitted by the bolt 2 when the bolt fastening means 1 fastens the bolt 2, an analysis part for determining whether the bolt 2 is fastened to the plasticity zone by analyzing a detected signal detected by the sensor, and a notifying means for notifying a user that the analysis part determines that the bolt 2 is fastened to the plasticity zone. When the user is notified that the notifying means determines that the bolt 2 is fastened to the plasticity zone, the user completes the fastening of the bolt 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bolt fastener and a bolt fastening method for fastening a plastic zone of a bolt, a bolt plastic zone fastening determination device, and a bolt plastic zone fastening judgment method.

  In the automobile industry and the like where vibration is a problem, bolts are tightened in a plastic zone for the purpose of reducing the occurrence of bolt loosening and bolt fatigue failure. The plastic region tightening is a method of tightening by increasing the tightening force until the bolt is plastically deformed beyond the elastic region. On the other hand, as the most used bolt fastening force management method, there is a torque management method in which tightening is performed while torque management is performed using a torque wrench. In this method, the tightening force is controlled by utilizing the linear relationship between the torque and the axial force of the bolt. In addition, in order to perform stable plastic region tightening, a rotation angle method, a torque gradient method, or a method using an ultrasonic bolt axial force meter that requires a larger apparatus, complicated procedures than a torque wrench is used. There is a need.

  However, in the torque management method, the relationship between the torque and the axial force varies greatly depending on the friction coefficient generated on the surface where the bolt and the torque wrench are fitted, so that the plastic region is required to accurately control the axial force. Not suitable for tightening.

  In addition, the rotation angle method and the torque gradient method described above can perform stable plastic region tightening, but they require a large-scale device and complicated procedures, and are therefore used at the site where bolts are actually tightened. It is difficult.

Japanese Patent Laid-Open No. 05-203513 Japanese Patent Laid-Open No. 06-079552 Japanese Patent Laid-Open No. 07-040262 JP 2000-094355 A JP 2000-114182 A JP 2004-114182 A

  The present invention has been proposed in view of such a conventional situation, and a bolt fastener and a bolt fastening method capable of accurately and easily fastening a plastic region of a bolt, a bolt plastic region fastening determination device, and An object of the present invention is to provide a bolt plastic zone tightening determination method.

  In order to achieve the above-described object, a bolt fastener according to the present invention detects a fastening means for fastening the bolt and an elastic wave (acoustic emission) emitted by the bolt when the bolt is fastened by the fastening means. A sensor that analyzes the detection signal detected by the sensor to determine whether the bolt is tightened to the plastic region, and the analysis unit determines that the bolt is tightened to the plastic region And notifying means for notifying that effect.

  The bolt fastener according to the present invention includes a fastening means for fastening the bolt, a drive means for driving the fastening means, and an elastic wave (acoustic emission) emitted by the bolt when the bolt is fastened by the fastening means. ), A sensor that analyzes the detection signal detected by the sensor and determines whether or not the bolt is tightened to a plastic region, and a controller that controls the drive means and the analyzer. The control unit controls the driving unit according to a determination result from the analysis unit.

  Further, the bolt fastening method according to the present invention detects an elastic wave (acoustic emission) emitted when the bolt is tightened, analyzes the detected elastic wave, and determines whether the bolt is tightened to a plastic region or not. It is characterized by determining.

  Further, the bolt fastening method according to the present invention is a method of fastening the bolt using a predetermined driving means, detecting an elastic wave (acoustic emission) emitted when the bolt is fastened, and analyzing the detected elastic wave. Then, it is determined whether or not the bolt is tightened to a plastic region, and the driving means is controlled according to the determined result.

  The bolt plastic zone tightening determination device according to the present invention includes a sensor for detecting an elastic wave (acoustic emission) emitted when the bolt is tightened, and a detection signal detected by the sensor to analyze the bolt. An analysis unit for determining whether or not the bolt has been tightened to a region; and a notifying unit for notifying that the analysis unit has determined that the bolt has been tightened to a plastic region.

  Also, the bolt plastic zone tightening determination method according to the present invention detects an elastic wave (acoustic emission) released when the bolt is tightened, analyzes the detection signal detecting the elastic wave, and detects the bolt in the plastic zone. It is determined whether or not the bolt has been tightened, and notification is made that it has been determined that the bolt has been tightened to the plastic range.

  The present invention detects an elastic wave (acoustic emission) emitted from a bolt when the bolt is tightened, and analyzes the detected elastic wave to determine whether the bolt is tightened to a plastic region. can do.

  As a result, the present invention measures the torque applied to the wrench and, based on the measurement result, determines whether or not the bolt is tightened to the plastic region. It can be determined whether or not it has been tightened.

  Further, according to the present invention, it is possible to determine whether or not the bolt is tightened to the plastic region accurately by a simple procedure as compared with the conventional method, without the apparatus becoming large.

  Hereinafter, a bolt fastener to which the present invention is applied will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an operation of tightening a bolt 2 with a plastic zone using a wrench 1.

  The wrench 1 is a bolt fastener according to the present invention, and is used when two fastened materials 4 are joined, as shown in FIG. 1, and fastens the bolt 2 and the nut 3. Further, the wrench 1 may be configured such that a bolt is fastened to a structure having a hole in which an internal thread is cut. The wrench 1 is composed of a head 1a, a handle 1b, and a socket 1d. The wrench 1 also includes a plastic zone tightening determination notification unit 10 that determines whether or not the bolt 2 is tightened to the plastic region and notifies the user of the determination result. Note that the present invention is not limited to the wrench 1 as described above, and can be applied to any bolt fastener such as a spanner that can tighten the bolt 2.

  The bolt 2 includes a head portion having a hexagonal column shape and a shaft portion formed of a rod-like body having a male screw formed on the outer peripheral surface and coupled to the head portion. Exclude bolts that may cause hydrogen embrittlement cracking to perform plastic zone tightening. Also excluded are bolts that do not emit elastic waves during plastic deformation. The bolt 2 may be a bolt made of any shape or material as long as the above-described conditions are satisfied.

  As shown in FIG. 1, the nut 3 has a female screw formed on the inner peripheral surface of the hole of the nut 3, and the female screw of the nut 3 and the male screw of the bolt 2 are screwed together.

  Moreover, the to-be-fastened material 4 is a member fastened between the volt | bolt 2 and the nut 3, for example, as shown in FIG.

  As shown in FIG. 1, the head 1a of the wrench 1 has a cylindrical shape, and a socket portion 1d is detachably connected to one end surface. The socket part 1d has a cylindrical shape, one end face is connected to the head part 1a, and the other end face opposite to the bolt 2 is provided with a recess 1c in which the head part of the bolt 2 is fitted. Yes. The socket 1d is provided with a recess 1c having a size corresponding to the head of the bolt 2.

  As shown in FIG. 1, the handle 1b of the wrench 1 has a rectangular parallelepiped shape, and one end in the longitudinal direction is coupled to the side surface of the head 1a. In addition, the handle portion 1b can fasten the bolt by rotating around the shaft portion of the bolt 2 in a state where the head portion of the bolt 2 is fitted in the recess 1c. The handle portion 1a is not limited to a rectangular parallelepiped shape, and may be any shape as long as the bolt 2 can be tightened. For example, the handle portion 1a may have a cylindrical shape.

  Further, the head 1a and the handle 1b are not limited to being coupled to each other from the beginning, but may be coupled via a predetermined coupling material.

  FIG. 2 is a diagram schematically illustrating the configuration of the plastic zone tightening determination notification unit 10.

  As shown in FIG. 2, the plastic zone tightening determination notification unit 10 includes a sensor 11 that detects an elastic wave (acoustic emission) emitted from the bolt 2, an amplifier 12 that amplifies a detection signal detected by the sensor 11, and An A / D converter 13 for converting the detection signal amplified by the amplifier 12 into a digital signal, and a detection signal digitized by the A / D converter 13 are supplied. And an analysis unit 14 that determines whether or not the bolt 2 is tightened to a plastic region, and a buzzer 15 that notifies the sound that the analysis unit 14 has determined that the bolt 2 has been tightened to the plastic range.

  The sensor 11 is attached to the recess 1 c so as to come into contact with the head of the bolt 2 when the recess 1 c of the wrench 1 is fitted to the head of the bolt 2. It is detected as a signal. Specifically, a sensor such as an acoustic emission sensor or an acceleration sensor that can detect elastic waves is used. The sensor 11 is not limited to being attached to the recess 1c, but is attached to the nut 3 or the fastened material 4 or the like. That is, you may make it install in the position which touches the volt | bolt 2 and can detect the elastic wave which the volt | bolt 2 discharge | releases. However, when attaching the sensor 11 to the nut 3 or the material 4 to be fastened, an operation of attaching the sensor 11 is required in addition to the operation of fitting the recess 1c and the bolt 2 together. On the other hand, by attaching the sensor 11 to the concave portion 1c, the concave portion 1c and the head of the bolt 2 are fitted, and the elastic wave emitted from the bolt 2 can be detected. Therefore, attaching the sensor 12 to the concave portion 1c has an advantage that preparation work until tightening is facilitated as compared with the case where the sensor is attached to other positions.

  The analysis unit 14 analyzes the detection signal amplified by the amplifier 12 and converted into a digital signal by the A / D converter 13, and determines that the bolt 2 has been tightened to the plastic region.

  When the analysis unit 14 determines that the bolt 2 has been tightened to the plastic region, the buzzer 15 outputs a sound according to a command from the analysis unit 14 to notify the user that the bolt 2 has been tightened to the plastic region. The buzzer 15 may be used to notify the user that the bolt 2 has been tightened to the plastic region, and a blinking display of an LED (Light Emitting Diode) may be used.

  Next, the operation | movement which fastens the volt | bolt 2 to a plastic region is demonstrated.

  First, the user inserts the shaft portion of the bolt 2 into the hole provided in the fastened material 4 and fastens the nut 3 to the shaft portion. The user fits the concave portion 1 c of the wrench 1 and the head of the bolt 2, and rotates the handle 1 b around the shaft portion of the bolt 2 to tighten the bolt 2. As shown in FIG. 3, the bolt 2 is tightened and emits an elastic wave, and when the bolt 2 is tightened to a plastic region, the number of times the elastic wave is released increases rapidly. The sensor 11 detects an elastic wave released when the bolt 2 is tightened. The detection signal detected by the sensor 11 is subjected to amplification processing and digital conversion. The analysis unit 14 is supplied with a digitally converted detection signal and analyzes the detection signal to determine whether or not the bolt 2 has been tightened until it is plastically deformed. When it is determined that the bolt 2 has been tightened to the plastic region, the buzzer 15 generates a sound according to a command from the analysis unit 14 and notifies the user that it has been determined that the bolt 2 has been tightened to the plastic region. The user listens to the sound generated by the buzzer 15 and completes the tightening of the bolt 2. In this way, the bolt 2 is tightened to the plastic region.

  Note that the wrench 1 is not limited to the case where the user manually operates the handle 1b of the wrench 1 and is notified by the buzzer 15; Control means for controlling may further be provided, and when the bolt is tightened to the plastic region by the driving means, the control means may complete the tightening according to the determination result based on the detection signal.

  As described above, the wrench 1 analyzes the detection result of the elastic wave released when the bolt 2 is tightened without measuring the axial force or extension applied to the bolt 2, and determines whether the bolt 2 is tightened to the plastic region. Since it can be determined accurately, it can be easily determined as compared with the case where other methods are used.

  Next, specific criteria for determining that the bolt 2 is tightened to the plastic region by the analysis unit 14 based on the detection signal of the elastic wave emitted by the bolt 2 will be described.

  The bolt used as a specific example is a bolt made of chrome molybran steel of strength category 10.9, M10. In addition, you may make it use not only this kind of bolt but the other kind of bolt in which plastic zone fastening is performed.

  As described above, in order to determine whether or not the bolt has been tightened to the plastic region, it can be determined from a load-elongation diagram which is a relationship between the axial force of the bolt and its extension.

  Here, while tightening the bolt 2, it is desirable to measure the axial force and elongation of the bolt and determine the plastic deformation start point of the bolt 2, but to accurately measure these values when tightening the bolt 2. It is difficult. Therefore, a bolt tension test is performed, and the bolt axial force and the bolt elongation corresponding to the bolt axial force are measured to obtain an accurate plastic deformation start point. The sensor 11 releases the bolt during the tensile test. The elastic wave was measured and the relationship with the plastic deformation start point was clarified.

  Here, the tensile tester used for the tensile test can measure the tensile force and the elongation of the member.

  In this embodiment, instead of tightening the bolt, the bolt 2 is stretched using a tensile tester, the axial force of the bolt 2 and its elongation are measured, the yield point of the bolt 2 is calculated, and the yield point is plastic. It is used as an indicator for judging whether or not it has been tightened up to the range. Further, when the bolt is extended by the tensile testing machine, the elastic wave emitted from the bolt 2 is detected using the sensor 11 of the wrench 1. The detected elastic wave is as shown in FIG. In this example, the cumulative number of elastic waves emitted by the analysis unit 14 is calculated from the detection signal, and this cumulative number is used as a determination index.

  In FIG. 5, when the bolt 2 is extended by a tensile testing machine, the axial force applied to the bolt 2 is shown on the horizontal axis, and the extension of the bolt 2 is shown on the right axis. As shown in FIG. 5, the relationship between the axial force applied to the bolt 2 and its extension is proportional to the bolt's axial force at 54 kN or less, but when tightened to 54 kN or more, this proportional relationship The extension of the bolt with respect to the axial force of the release bolt increases. That is, it can be determined that the bolt has been tightened to the plastic region with the bolt member's axial force at 54 kN as the yield point of the bolt member.

  In this specific example, the example of the bolt 2 with a yield load of 54 kN is shown. However, the yield load of a bolt that performs other types of plastic region tightening is also measured using a tensile tester and the axial force of the bolt and its elongation. It can be easily obtained from the relationship. It is also possible to calculate the yield load from the yield stress and effective cross-sectional area of the bolt described in the JIS standard or the manufacturer's catalog.

  In FIG. 5, the left axis shows the cumulative number of elastic waves released by the bolt 2 when the bolt 2 is extended by a tensile tester.

  As shown in FIG. 5, the relationship between the cumulative number of elastic waves released by the bolt 2 and the axial force of the bolt 2 measured by the tensile tester is based on the boundary when the axial force of the bolt 2 becomes 54 kN. The cumulative number of elastic wave emissions increases rapidly. Here, from the relationship between the axial force of the bolt 2 and the extension of the bolt 2, the bolt 2 is tightened to the plastic region at the boundary where the axial force of the bolt 2 reaches 54 kN. It is almost the same as the axial force of the bolt when is rapidly increased. Therefore, determining that the bolt 2 has been tightened to the plastic region can be determined based on the cumulative number at which the elastic wave discharge cumulative number increases rapidly.

  The relationship between the yield point of such a bolt and the cumulative number of elastic wave emissions can be obtained even if trials are repeated many times.

  Therefore, the cumulative number of elastic waves released from the bolt is an effective determination index that can accurately determine whether or not the bolt is tightened to the plastic range. Therefore, the wrench 1 provided with the plastic area determination notification unit 10 can accurately and easily tighten the plastic area of the bolt.

  Note that determining that the bolt 2 has been tightened to the plastic region is not limited to the cumulative number of elastic waves released by the bolt 2, but a determination index of the elastic wave emission ratio, the accumulated amplitude distribution of the elastic waves, or the like. You may make it use as.

It is the figure which showed typically the structure when tightening a volt | bolt using a wrench. It is the figure which showed typically the structure of the plastic zone fastening analysis part. It is the figure which showed typically the elastic wave which a volt | bolt discharge | releases. It is the figure which showed the detection signal of the elastic wave which a volt | bolt discharge | releases. It is a figure which shows the axial force of a bolt measured during the tension test of a bolt, the expansion | extension of a bolt, and the cumulative number of the elastic waves which a bolt discharge | releases.

Explanation of symbols

  1 wrench, 2 bolts, 3 nuts, 4 material to be fastened, 10 plastic area tightening determination notification unit, 11 sensor, 12 amplifier, 13 A / D converter, 14 analysis unit, 15 buzzer

Claims (10)

In bolt fasteners that tighten bolts,
Fastening means for fastening the bolt;
A sensor for detecting an elastic wave (acoustic emission) emitted by the bolt when the bolt is tightened by the fastening means;
An analysis unit that analyzes the detection signal detected by the sensor and determines whether the bolt is tightened to a plastic region; and
A bolt fastening device comprising: notification means for notifying that the analysis unit has determined that the bolt has been tightened to a plastic range.   The bolt fastener according to claim 1, wherein the analysis unit determines whether or not the bolt is tightened to a plastic region based on a cumulative number of the elastic waves released by the bolt. In bolt fasteners that tighten bolts,
Fastening means for fastening the bolt;
Drive means for driving the fastening means;
A sensor for detecting an elastic wave (acoustic emission) emitted by the bolt when the bolt is tightened by the fastening means;
An analysis unit that analyzes the detection signal detected by the sensor and determines whether the bolt is tightened to a plastic region; and
A controller that controls the driving means and the analyzer;
The said control part controls the said drive means according to the determination result from the said analysis part. The bolt fastener characterized by the above-mentioned.   The bolt fastener according to claim 3, wherein the analysis unit determines whether or not the bolt is tightened to a plastic region based on a cumulative number of the elastic waves released by the bolt. In the bolt fastening method,
Detects acoustic waves (acoustic emission) released when the bolt is tightened,
A bolt fastening method comprising: analyzing the detected elastic wave to determine whether or not the bolt is tightened to a plastic region.   The bolt fastening method according to claim 5, wherein it is determined that the bolt has been tightened to a plastic region based on a cumulative number of the elastic waves released when the bolt is tightened. In the bolt tightening method for tightening the bolt,
Tighten the bolt using a predetermined driving means,
Detects acoustic waves (acoustic emission) released when the bolt is tightened,
A bolt fastening method comprising: analyzing the detected elastic wave to determine whether or not the bolt is tightened to a plastic region; and controlling the driving means according to the determined result.   The bolt fastening method according to claim 7, wherein it is determined whether or not the bolt is tightened to a plastic region based on a cumulative number of the elastic waves released when the bolt is tightened. In the bolt plastic zone tightening determination apparatus for determining whether or not the bolt is tightened in the plastic zone,
A sensor for detecting an elastic wave (acoustic emission) emitted when the bolt is tightened;
An analysis unit that analyzes the detection signal detected by the sensor and determines whether the bolt is tightened to a plastic region; and
A bolt plastic region tightening determination apparatus comprising: notification means for notifying that the analysis unit has determined that the bolt has been tightened to a plastic region. In the bolt plastic region tightening determination method for determining whether or not the bolt is tightened in the plastic region,
Detects acoustic waves (acoustic emission) released when the bolt is tightened,
Analyzing the detection signal that detected the elastic wave to determine whether the bolt has been tightened to the plastic region,
A bolt plastic region tightening determination method characterized by notifying that the bolt has been tightened to a plastic region.

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