JP2020201050A - Method and device for testing screw fastening state - Google Patents

Abstract

To provide a method and device for appropriately performing an accurate test of a screw fastening state by performing a test in a state closer to a screw fastening body in a general structure compared with a conventional manner.SOLUTION: In a screw fastening state test method, a screw fastening body 16 whose first member 161 and second member 162 are fastened by screw structures 163, 164 is shaken in a first direction F so as to be vibrated. In this state, a position of the screw fastening body 16 in a second direction crossed with the first direction F is measured by a non-contact system, so as to detect a vibration aspect of a position in the second direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method and an apparatus for testing a screw fastening state.

Conventionally, there has been no end to accidents that occur when screws are loosened, causing them to fall off or drop. Originally, it is thought that loosening of screws will not occur if the screws are properly tightened, but it can be said that the above accident is due to the lack of interest of people regarding the tightening situation of screws. .. In order to prevent such loosening of screws, it is necessary to properly design screws, fasten them, and manage the fastening status.

On the other hand, there is known a screw loosening tester for performing a shaft right angle vibration type screw loosening test for testing the looseness of a screw for a screw fastening body such as a bolt / nut fastening body. In this screw loosening tester, for example, a shaft right-angle vibration type screw loosening tester, the axial force of the screw fastener is measured by a load cell or the like, and the movable plate of the screw fastener is reciprocated to reach the fixing plate. The screw is elastically deformed to cause loosening. Then, it can be seen that when the axial force is reduced due to the reciprocating slip, the screw fastener is loosened.

Further, as an apparatus improved from the above-mentioned screw loosening tester, for example, the device described in the following Patent Documents 1-3 has been proposed. In these devices, the point of vibrating the movable part corresponding to the movable plate is the same as the above, but the part fixed to the movable part by bolts, nuts or the like like the fixed plate is formed. By making it a movable structure that is not fixed and adds inertia such as a weight, it is possible to test under more realistic conditions instead of unrealistic conditions such as forced vibration, and a loose state is generated in a shorter time. Can be done.

Japanese Unexamined Patent Publication No. 53-106192 Japanese Unexamined Patent Publication No. 10-14209 Japanese Unexamined Patent Publication No. 51-4709

However, in the above-mentioned screw loosening tester or each of the above-mentioned devices improved thereto, the axial force of the screw fastening body is detected by a load cell, a pressure sensor, or the like. Therefore, it is common to intervene these force sensors. Since the test is performed under conditions different from the fastening state of the screw fastener in the structure of the above, there is a problem that accurate detection cannot be performed. Further, even if an attempt is made to detect a screw fastening state with respect to a formed portion of a screw fastening body in a general structure, there is a problem that it cannot be detected as it is because the above force sensor needs to be interposed. There is also a point. On the other hand, although there is a method of detecting by electric resistance as in Patent Document 2, it is not possible to detect the fastening state of the screw structure with high accuracy unless there is a large change such as crushing of the screw thread.

Therefore, the present invention solves the above-mentioned problems, and by performing the problem in a situation closer to a screw fastening body in a general structure than before, a high-precision screw fastening situation test is qualified. To provide methods and devices that can be performed.

In order to solve the above problems, in the method for testing the screw fastening state according to the present invention, a screw fastening body in which a first member and a second member are fastened by a screw structure is vibrated by vibrating in the first direction. In this state, the position of the screw fastener in the second direction intersecting with the first direction is measured by a non-contact method, and the vibration mode of the position in the second direction is detected. .. In this case, the second direction is preferably the axial direction of the screw structure.

According to the present invention, the screw structure is distorted in the first direction by vibrating the screw fastener in the first direction, so that a force component is generated in the second direction through the distortion of the screw structure. As a result, the vibration mode of the position in the axial direction changes depending on the fastening status of the screw fastening body, for example, the presence or absence of loosening and the degree of loosening. Therefore, the fastening status of the screw structure is grasped according to the vibration mode. Will be possible. At this time, since the vibration mode of the position is detected by a non-contact method such as measurement of the position of the reflecting surface by reflection of light on the reflecting surface of the screw fastening body, the measurement of the above position determines the fastening status of the screw fastening body. Since there is no effect, the fastening status can be grasped in a state close to the normal state of a general structure. For this reason, it is possible to properly test the screw fastening status, and it is possible to eliminate obstacles to the detection mode in line with the normal situation of a general structure, so that the screw fastening status can be grasped with high accuracy. be able to. For example, since it is not necessary to incorporate a measuring means such as a load cell or a pressure sensor inside the screw fastening body, the screw fastening body provided in a general structure (existing building, etc.) can be left as it is. , You can know the fastening status of the screw structure. Here, it is preferable that the second direction is orthogonal to the first direction. In particular, when the second direction is the axial direction of the screw structure, the vibration action in the direction intersecting the axial direction tends to cause distortion of the screw structure and strongly reflects the fastening status of the screw fastener. By detecting the axial vibration mode of the screw structure, the fastening status can be grasped more accurately. At this time, it is desirable that the direction intersecting the above-mentioned axial direction is a direction orthogonal to the axial direction.

By the way, in the test method of the present invention, the reason for vibrating the screw fastener is not only to shift the screw fastener from the tightened state to the loosened state as in the conventional screw looseness test. That is, in the conventional screw looseness test, in the test for evaluating the "looseness" such as how much load should be applied to the screw fastener in the tightened state to be in the loosened state, the tightened state is changed to the loosened state. The screw fastener is vibrated in order to shift to. However, in the present invention, the screw fastener is vibrated in the first direction in order to generate an "axial vibration mode" for grasping the screw fastening state (for example, tightened state or loosened state). There is. The "vibration state in the first direction" of the screw fastener is converted into the "vibration mode in the second direction" via the screw structure according to the fastening state of the screw structure. However, it is also possible to carry out the same screw loosening test as before by the method of the present invention. For example, as will be described later, by detecting the "vibration mode in the second direction" in the process of shifting from the tightened state to the loosened state by the "vibration state in the first direction" of the screw fastener due to vibration. It is also possible to grasp the fastening status of the screw structure of the screw fastening body.

Here, the "screw fastener" means that through holes are formed in the first member and the second member, respectively, and a nut is inserted into the tip of a bolt (screw) that has passed through each of these through holes and protrudes from each of the through holes. It is not limited to a structure that is screwed and tightened. For example, a structure in which a through hole is formed in the first member, a screw hole is formed in the second member, and a bolt (screw) is passed through the through hole and then screwed into the screw hole and tightened. Alternatively, a structure in which a through hole is formed in the second member, a screw hole is formed in the first member, and a bolt (screw) is passed through the through hole and then screwed into the screw hole and tightened. It may be. Further, the structure may be a structure in which a screw shaft integrally protruding in the first member is passed through a through hole provided in the second member and then a nut is screwed into the tip thereof to tighten the structure. It may be a structure in which a screw shaft integrally protruding from the two members is passed through a through hole provided in the first member, and then a nut is screwed to the tip thereof and tightened. Further, the structure may be such that the screw shaft integrally projected in the first member is screwed into the screw hole provided in the second member and tightened, or the screw integrally projected in the second member. The structure may be a structure in which the shaft is screwed into a screw hole provided in the first member and tightened. Further, one of the first member and the second member may be a bolt (screw) itself, and at this time, the other may be a nut itself. That is, the screw fastening body is a structure in which two or more members are mutually tightened by a screw structure (a structure in which a male screw and a female screw are screwed together).

In the present invention, the position in the second direction is preferably measured by an optical sensor. For example, it can be measured by detecting the reflected light of the light by the reflecting surface of the screw fastening body. By using light, it is possible to easily measure by a non-contact method, and it is possible to measure up to a high frequency band without any trouble. At this time, it is desirable that the optical sensor is a laser displacement meter. As a result, the position can be detected with higher accuracy, and a high frequency can be accurately dealt with, so that the vibration mode of the position can be reliably captured.

In the present invention, it is preferable that the vibrating action on the screw fastening body is given to the first member, and the measurement site of the position in the second direction on the screw fastening body is the second member. According to this, in the screw fastening body that is brought into a vibrating state by vibrating the first member, the position of the second member fastened to the first member via the screw structure in the second direction is determined. By measuring, the vibration mode of the position of the other portion via the screw structure with respect to the vibrating portion in the second direction is always detected. Therefore, since the detected vibration mode reflects the fastening state of the screw structure more greatly, the detection accuracy of the screw fastening status can be improved. Here, the first member and the second member are not limited to the members to be fastened other than the bolts and nuts, and may be in a state of being fastened via a screw structure. Or the nut itself.

In the present invention, it is preferable to further include a step of determining the fastening state of the screw structure of the screw fastening body according to the vibration mode. At this time, it is particularly desirable to determine the fastening state of the screw structure according to the vibration range of the position in the second direction or the variation in amplitude among the vibration modes of the position in the second direction. .. Since the vibration mode of the screw fastener is closely related to the fastening status of the screw structure, the vibration mode is not limited to the above-mentioned determination mode. However, when the screw fastener vibrates due to the given excitation energy, the variation in the vibration range and the amplitude varies greatly depending on the screw fastening condition. Therefore, by determining the screw fastening status based on at least one of the vibration range and the amplitude variation, the fastening status can be grasped more accurately and easily. Further, in the above stage, it is desirable to determine the fastening state of the screw structure by comparing the vibration mode with the vibration mode of the screw fastening body in the first direction. In this case, it is exemplified that the vibration mode is a stability mode of a vibration range or a variation of amplitude.

In the present invention, it is preferable that the vibrating action on the screw fastening body is applied to the first member, and the second member is movably configured. According to this, the first member is vibrated and the second member connected to the first member via the screw structure is movably configured, so that the normal situation in a general structure can be obtained. It will be possible to perform tests and detections in a closer state. Further, since the influence reflecting the structural characteristics of the first member and the second member other than the screw structure and their surroundings can be reduced, the fastening state of the screw structure can be detected accurately and accurately. For example, in the shaft right-angled vibration type screw loosening test, since the second member is fixed, the measurement is performed in a forced vibration state that does not actually occur, so it is different from the normal situation in a general structure. In some cases, the test will be conducted in different conditions. Further, by fixing the second member, the measurement is performed in a state that reflects the structural characteristics of the first member and the second member other than the screw structure and their surroundings, so that it is related to the fastening state of the screw structure. It is easily affected by the structure that is not used, and the test accuracy may decrease. However, according to the present invention, the above problems do not occur.

In this case, it is desirable to have a weight connected to the second member, and the weight is configured to give an inertial force to the second member according to the operating state of the second member. According to this, by connecting the weight to the second member, it is possible to adjust the inertial force received by the screw fastener according to the mass of the weight and the connection position. At this time, the second direction is also the axial direction of the screw structure, and the second member is oriented on both sides of the axial line of the screw structure and orthogonal to the axial direction of the first member. It is preferable that the weights are connected to both sides thereof, and the weights on both sides are configured so that the second member is given an inertial force equal to each other when the first member is vibrated. Thereby, the vibration state of the screw fastener in the first direction can be stabilized. Here, it is desirable that the first direction is a vertical direction and the second direction is a horizontal direction.

In the present invention, it is preferable to provide a rotation suppressing means for suppressing the rotation of the screw structure around the axis of the screw fastening body. Here, it is desirable that the rotation suppressing means includes a regulating member that is directly or indirectly connected to the second member and is configured to be in contact with a fixed portion around the axis. As a result, it is possible to avoid fluctuations in the fastening state of the screw structure due to rotation of the screw fastening body and influence on the vibration mode in the second direction. Further, it is more desirable to have the regulating members on both sides which are directly or indirectly connected to the weights on both sides.

Next, the device for testing the screw fastening state according to the present invention includes a vibrating device that vibrates a screw fastening body in which a first member and a second member are fastened by a screw structure in a first direction, and the above-mentioned vibrating device. A position measuring means for measuring the position of the screw fastening body in a second direction intersecting with the first direction by a non-contact method and the position measuring means in a state where the screw fastening body is vibrated by a shaker. It is characterized by comprising a vibration measuring means for measuring the vibration mode in the second direction based on the measurement result. In this case, the fastening status determining means for determining the fastening status of the screw structure of the screw fastening body according to the mode of variation in the range or amplitude of the vibration in the second direction measured by the vibration measuring means. Further, it is preferable to provide.

In the present invention, it is preferable that the exciter is composed of a voice coil motor or an ultrasonic vibrator. Voice coil motors can form linear vibrations in a wide frequency band. In addition, since the voice coil motor can be configured so that the amplitude can be controlled, it depends on the configuration (dimensions, structure, material, etc.) of the target screw fastening body, or the purpose (looseness test or detection of fastening status). Depending on the situation, vibrations of appropriate amplitude can be applied. On the other hand, the ultrasonic vibrator can generate vibration in a higher frequency band than the voice coil motor, and can give high acceleration and vibration energy to the screw fastener. Further, since the amplitude of the ultrasonic vibrator is generally small, the load applied to the screw fastener can be reduced.

According to the present invention, by performing the test in a situation similar to that of a screw fastening body in a general structure, it is possible to appropriately test the screw fastening state with higher accuracy than before. In addition, it becomes easy to detect the screw fastening status of the screw fastening body in a general structure as it is.

It is a front view (a) of the main body part of the test apparatus of the screw fastening state of 1st Embodiment which concerns on this invention, and the plan view (b) of the main part of the main body part. It is a front view (a) of the main body part of the test apparatus of the screw fastening state of the 2nd Embodiment which concerns on this invention, and the plan view (b) of the main part of the main body part. It is a front view (a) of the main body part of the test apparatus of the screw fastening state of the 3rd Embodiment which concerns on this invention, and the plan view (b) of the main part of the main body part. It is a front view (a) of the main body part of the test apparatus of the screw fastening state of the 4th Embodiment which concerns on this invention, and the plan view (b) of the main part of the main body part. It is explanatory drawing which shows the measurement position and the measurement method of the position measuring means of the test apparatus of the screw fastening state of each embodiment. It is a schematic block diagram which shows the structure of the position measuring means, the vibration measuring means and the fastening state detecting means of each embodiment. It is a figure which shows the vibration direction vibration waveform derived based on the position measurement signal of the vibration direction in 2nd Embodiment. It is a figure which shows the axial vibration waveform at the time when a screw loosening occurs in a screw fastening body in 2nd Embodiment. It is a figure which shows the axial vibration waveform at the time of loosening of a screw in the screw fastening body in 2nd Embodiment. It is a figure which contrasts and shows the vibration mode in the screw axis direction and the vibration mode in a vibration direction in a tightened state of a screw fastening body in the 2nd Embodiment.

Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, a method and an apparatus for testing a screw fastening state according to the first embodiment of the present invention will be described with reference to FIGS. 1, 5 and 6.

FIG. 1 is a front view (a) showing the main body 10A of the test apparatus 10 in which the screws are fastened, and a plan view (b) showing the main part (central part) of the main body 10A. The substrate 13 is fixed on the vibration isolation table 11 via a plurality of (four in the illustrated example) columns 12. The exciter 14 is fixed to the substrate 13 in a suspended state. The exciter 14 is not particularly limited, but includes, for example, a drive motor such as a voice coil motor, and in the illustrated example, the exciter unit 14a vibrates in the vertical direction (first direction) by the drive motor. The vibrating portion 14a is exposed upward through the opening 13a provided in the center of the substrate 13. A connecting member 15 is fixed on the vibrating portion 14a. The vibration frequency and amplitude of the excitation unit 14a can be controlled by the frequency fd and the voltage Vd of the drive signal given to the drive motor. For example, the AC power applied to the exciter 14 can be used to vibrate at a frequency of 50 to 200 Hz (for example, 50 Hz, 60 Hz, 100 Hz, 200 Hz, etc.). Further, by adjusting the voltage Vd in the range of 0.1 to 1.0 V, the amplitude is 98 to 796 μm when fd = 50 Hz, 35 to 250 μm when fd = 100 Hz, and 6 to 40 μm when fd = 200 Hz. It can be changed in shape.

The connecting member 15 has a vertical mounting surface 15a along the central portion of the exciting portion 14a, and the screw fastening body 16 is mounted on the mounting surface 15a. The screw fastening body 16 penetrates the first member 161 fixed on the mounting surface 15a, the second member 162 arranged so as to overlap the first member 161 and the first member 161 and the second member 162. A bolt (screw) 163 to be screwed and a nut 164 screwed to the shaft portion of the bolt 163 to tighten the first member 161 and the second member 162 are provided. Although not particularly limited, in the illustrated example, the first member 161 and the second member 162 are plate-shaped bodies, respectively. The mounting surface 15a is provided with a recess 15b for accommodating the tip of the shaft portion of the bolt 163 and the nut 164. Here, as shown in FIG. 5, the connecting member 15 is configured to arrange the screw fastening body 16 so that the axis 14x of the exciting portion 14a of the exciter 14 passes through the screw fastening body 16. Is preferable. As a result, there is a deviation between the vibration direction F (first direction) by the exciter 14 and the vibration direction of the screw fastening body 16, and the vibration direction F of the vibration of the screw fastening body 16 caused by the deviation. It is possible to reduce the shaking in the direction of intersection.

The first member 161 is attached to the connecting member 15 by an attachment member 17. The mounting member 17 includes mounting brackets 17a and 17b. The first member 161 is fixed on the mounting surface 15a by bolts or the like using these mounting brackets 17a and 17b. In the illustrated example, the mounting bracket 17a is fixed to the connecting member 15 (mounting surface 15a) so as to support the lower two sides of the first member 161 from below, and the mounting bracket 17b is the upper two sides of the first member 161. Is fixed to the connecting member 15 (upper surface 15c) so as to support the above.

FIG. 5 is a position measuring means for measuring the position of the connecting member 15 to which the screw fastening body 16 is attached as described above and the direction (second direction) of the axis 16x of the screw structure of the screw fastening body 16. The laser displacement meter 18, the laser displacement meter 19 which is a position measuring means (substantially the vibration detecting means) for detecting the vibration in the vibration direction F of the screw fastening body 16, and these laser displacement meters 18, 19 It is explanatory drawing which shows a part of the position measuring means and the measuring apparatus 101 which constitutes a vibration measuring means, which was configured to display the measurement result by the above-mentioned measurement result, and also to display the vibration mode by the measurement result. The screw fastening status test device 10 includes the main body 10A and a detection unit 10B including the laser displacement meters 18 and 19 and the meter side machine 101.

In the screw fastening state test device 10 of the present embodiment, the position of the second member 162 (the position of the light reflecting surface on the surface) of the screw structure of the screw fastening body 16 in the direction of the axis 16x is measured by the laser displacement meter 18. Then, the vibration mode such as the vibration range and / or the amplitude variation at this position is detected. The laser displacement meter 18 irradiates the surface of the second member 162 with the laser beam 18i, detects the reflected light 18r reflected by the surface (light reflecting surface), and thereby determines the position of the surface in the measurement direction E. The distance between them can be measured. Here, in the illustrated example, the measurement direction E is the direction of the axis 16x of the screw structure of the screw fastening body 16. However, the measurement direction E is not limited to the case where it coincides with the direction of the axis 16x (second direction) as shown in the illustrated example, and an angle of less than 90 degrees with the direction of the axis 16x (second direction). You may have. This is because the position of the screw fastener 16 in the direction of the axis 16x can be measured by the laser displacement meter 18, so that the measurement signal may include the detection component in the above direction.

Further, the measurement position of the screw fastening body 16 may be any position as long as it is a position in the direction of the axis 16x of the screw structure. However, in particular, it is preferable to measure the position of the surface of the overlapping portion of the first member 161 and the second member 162 that intersects (preferably orthogonally) the axis line 16x. Further, it may be the head portion of the bolt 163 or the surface of the nut 164. As described above, the measurement position is connected to the first member 161 to be vibrated, such as the second member 162, the bolt 163, or a part of the nut 164, via the screw structure as in the present embodiment. It is preferably a portion. This is a mode in which other parts vibrate via the screw structure due to the vibration (driving vibration component) of the first member 161 generated by being vibrated by the exciter 14 (a mode of the driven vibration component). This reflects the fastening status of the screw structure, and detecting as much of this driven vibration component as possible leads to a highly accurate grasp of the fastening status of the screw. However, since it is considered that the vibration mode of any part of the screw fastening body 16 (including the first member 161) always includes a part of the mode of the driven vibration component, the measurement position is set as described above. Of course, it is not limited.

The laser displacement meter 19 detects vibration in the vibration direction F by the exciter 14 of the screw fastening body 16. Specifically, the laser beam 19i is applied to the surface of the vibrating portion 14a or the connecting member 15 or the mounting member 17 (17a, 17b) fixed directly or indirectly to an arbitrary portion of the screw fastening body 16. By irradiating and detecting the reflected light 19r, the vibration state of the surface in the vibration direction F can be detected. In this example, since the laser displacement meter 19 is used, the position of the vibration direction F on the surface is measured. Here, the vibration state of the screw fastening body 16 due to the vibration by the vibration device 14 ( The purpose is to detect the state of the drive vibration component), that is, the frequency and amplitude of the vibration in the vibration direction F. The position measurement of the vibration direction F and the measurement direction of the vibration measurement are the same as the measurement of the axis 16x direction described above, if the component of the vibration direction F (first direction) can be measured, the vibration is performed. It does not have to be the direction F (first direction) itself.

In the method for testing the screw fastening state of the present embodiment, the laser displacement meter 18 and the laser displacement meter 19 may be used in combination with one laser displacement meter. Further, in each measurement or detection, the position measuring means or the vibration detecting means may be any one capable of measuring the position or detecting the vibration without contacting the screw fastening body 16, and the laser displacement is described above. It is not limited to the total. In general, as a method capable of measuring a position by a non-contact method, a light detection method, a magnetic detection method, or the like can be mentioned. For example, a proximity sensor is an example, which includes an induction type, a capacitance type, an ultrasonic type, a photoelectric type, and a magnetic type. The laser displacement meter derives a vibration waveform indicating the position of the unit to be measured and the passage of time at the position based on the measurement units 18 and 19 and the signals transmitted from the measurement units 18 and 19. Preferably, it can be considered to be composed of the measuring instrument 101 displaying these. Here, the measuring device 101 is provided with an axial position measurement value display unit 101a, a vibration direction position measurement value display unit 101b, an axial vibration waveform display unit 101c, and a vibration direction vibration waveform display unit 101d. Be done.

FIG. 6 is a schematic configuration diagram showing a configuration of a screw fastening status detection process or a screw fastening status detection system for the screw fastening body 16 of the present embodiment. First, the exciter 14 is operated (by the vibrating means), and the screw fastening body 16 is vibrated via the connecting member 15. As a result, the screw fastening body 16 vibrates in the vibration direction F. This is the drive vibration component. The position of the measurement direction E, which is the direction of the axis 16x of the screw structure, is measured with respect to the screw fastening body 16 in the vibrating state by the laser displacement meter 18 which is a position measuring means, and the position measurement signal 18t indicating the time change of the position. Is output to the vibration mode detector 18A. Based on the input position measurement signal 18t, the vibration mode detector 18A forms a waveform of the position measurement signal 18t indicating a variation in the vibration range and amplitude of the position. Then, the vibration waveform signal 16d including the waveform itself and the information indirectly indicating the waveform is output. The vibration mode detector 18A can be configured as a function realizing means of the detection unit 10B by operating an operation program (not shown) by a computer device (not shown) or the like.

Next, the vibration waveform signal 16d of the screw fastening body 16 detected as described above (for example, the vibration waveform itself, or the signal indicating the variation in the vibration range and amplitude) 16d is output to the screw fastening status determining device 18B. To. The screw fastening status determining device 18B determines the fastening status of the screw structure of the screw fastening body 16 based on the vibration waveform signal 16d, and outputs the determination result. The screw fastening status determination device 18B can also be configured as a function realizing means of the detection unit 10B by operating an operation program by a computer device in the same manner as the vibration mode detector 18A. The determination of the fastening status of the screw structure is determined by the deviation from the reference position of the vibration range of the axial position of the screw fastening body 16 indicated by the vibration waveform signal 16d (measurement surface (second member 162) shown in FIG. 5). (Surface), depending on the degree of deviation of the vibration range of the above position in the increasing direction) or the change in the amplitude variation of the position in the axial direction (in the illustrated example, the increase in variation). Will be done. Here, it is determined that the tightening state of the screw structure is moving in the loosening direction as the deviation amount and variation increase. The determination result 16s of the screw fastening status thus obtained is displayed by the determination indicator 18C which is the determination display means. Here, the determination result 16s of the screw fastening status can be displayed by various methods such as characters (strings), numerical values, symbols, and colors. For example, as the determination result 16s of the screw fastening status, a numerical value indicating the stage of the loosening state (presence or absence of the loosening state) and the fastening status (degree of loosening) (for example, 1 to 10 in the case of 10 steps). Numerical value). On the other hand, the determination display 18C can be configured by an output device connected to the computer device, for example, a display monitor or a printing machine.

As shown in FIG. 5, the position measurement signal 18t is displayed on the axial position measurement value display unit 101a of the measuring device 101 as a numerical value that changes with time. Further, the position measurement signal 19t is displayed as a numerical value that changes with time on the vibration direction position measurement value display unit 101b of the measuring device 101. Further, the vibration waveform signal 16d is a two-dimensional graph of the vibration waveform (for example, the vertical axis is the amplitude and the horizontal axis is the time) on the axial vibration waveform display unit 101c of the measuring device 101 by sampling the position measurement signal 18t or the like. ) Is displayed. Further, the vibration waveform in the vibration direction obtained from the position measurement signal 19t is a vibration waveform (for example, the vertical axis is amplitude and horizontal) on the vibration direction vibration waveform display unit 101d by sampling the position measurement signal 19t or the like. The axis is displayed as a two-dimensional graph of time). The display contents of the axial vibration waveform display unit 101c and the vibration direction vibration waveform display unit 101d may indicate the average waveform up to that point, or may be displayed periodically or by an appropriate operation. It may be updated each time.

Here, as described above, when the laser displacement meter 19 detects the vibration state of the screw fastening body 16 in the vibration direction F and outputs the position measurement signal 19t, the position measurement signal 19t is used as the vibration mode. It can be input to the detector 18A and / or the screw fastening status determination device 18B and used for the output processing of the vibration waveform signal 16d and the determination processing of the screw fastening status determination result 16s. For example, when determining the amount of deviation in the vibration range of the position and the degree of variation in amplitude, noise removal or the like is performed by using the position measurement signal 19t as a reference signal for the vibration waveform in the axial direction of the position. be able to. Further, among the vibration modes in the direction of the axis line 16x indicated by the vibration waveform signal 16d, the stability of the vibration range and the variation in amplitude are basically measured in the position when the screw fastening body 16 is in the tightened state. It is almost the same as the stability of the vibration range and the variation of the amplitude of the vibration mode of the vibration direction F obtained from the signal 19t. On the other hand, when the screw fastening body 16 is in a loosened state, or when it shifts from a tightened state to a loosened state, it is in the direction of the axis 16x as compared with the stability of the vibration range in the vibration direction F and the variation in amplitude. The stability of the vibration range is reduced and the amplitude variation is increased. Therefore, the screw fastening state of the screw fastening body 16 may be determined by comparing the vibration mode in the direction of the axis 16x with the vibration mode in the vibration direction F.

Further, since the position measurement signal 19t indicates the actual vibration state of the screw fastening body 16 in the vibration direction F, that is, the frequency and amplitude of the vibration in the same direction, the vibration device 14 (vibration means) is used as a standard. For example, the vibration waveform signal 16d and the screw fastening status determination result 16s are added in order to confirm whether or not the vibration state is obtained and to eliminate the influence of the deviation of the vibration direction F from the standard vibration state. It may be used to correct according to the degree of deviation of the vibration direction F from the standard vibration state. However, the position measurement signal 19t may be simply displayed as a reference signal. For example, it is conceivable to show the waveform of the position measurement signal 19t in comparison with the waveform of the vibration waveform signal 16d.

In the present embodiment, the screw fastening body 16 is vibrated and vibrated in the vibration direction F (first direction), and the measurement direction E (that is, the screw of the screw fastening body 16) is non-contacted using light. The position of the screw fastening body 16 in the direction of the axis 16x of the structure (second direction) is measured, and the vibration waveform signal 16d (for example, the range of vibration) in the direction of the axis 16x of the screw fastening body 16 from the position measurement signal 18t. And amplitude variation). In this way, the fastening state of the screw structure can be reliably grasped based on the vibration mode of the screw fastening body 16 itself. In particular, the screw fastening status can be objectively shown by determining the fastening status of the screw structure based on the vibration waveform signal 16d and obtaining the screw fastening status determination result 16s. In this test method, for example, unlike a conventional load cell or pressure sensor, there is no risk of affecting the vibration system of the screw fastening body 16, and a physical quantity that is easily adversely affected by the vibration system, such as measurement of electrical resistance. Since it does not measure, the fastening status of the screw structure can be detected with high accuracy. In particular, since it is not necessary to interpose a member such as a load cell or a pressure sensor other than the screw structure in the measurement, the measurement can be performed in a situation similar to that of a screw fastener in a general structure.

Further, in the present embodiment, the second member 162, which is connected to the first member 161 excited by the exciter 14 via the screw structure, is movably configured and is not fixed. In the illustrated example, the second member 162 is provided only with a tightening action by a screw structure such as a bolt 163 and a nut 164, and is not subjected to any other binding force. Therefore, while the screw fastening body 16 can be reliably vibrated by the exciter 14, it is possible to avoid the possibility of giving an excessive load to the screw structure itself, and only the load necessary for detection is applied to the screw structure. Given, the screw fastening status can be detected appropriately. That is, when it does not have the purpose of causing the screw to loosen by vibration as in the conventional shaft right-angle vibration type screw loosening test, it is only necessary to detect the current screw fastening status of the screw fastening body 16. Since it is not necessary to apply an excessive stress, the amplitude at the time of vibration can be reduced, so that the strain generated around the screw structure can be suppressed. Here, the load applied to the screw structure by the vibration of the screw fastening body 16 is basically an inertial force due to the second member 162 and the mass connected to the second member 162.

The above inertial force can be set by the shape dimension (size and shape) and specific gravity of the second member 162 itself, and as will be described later, the shape dimension (size and size) of the weight and other members connected and fixed to the second member 162. It can be set appropriately according to the shape) and specific gravity. As a result of this configuration, in the present embodiment, the screw fastening body 16 using a bolt or screw having a small diameter of 10 mmφ or less can be used without any problem. In the test for determining the ease of loosening of a screw by a conventional axial right-angle vibration type screw loosening tester, it is necessary to give a large amplitude in order to cause the screw to loosen by vibration, and to fix the second member 162. , Small diameter bolts and screws may be severely damaged or broken, making the test itself impossible. In the present embodiment, when the function of loosening the screw structure is not required, the inertial force, excitation frequency, amplitude, etc. are adjusted in order to match the screw structure or to improve the detection accuracy of the screw fastening status. It can be set in a wider range. In addition, if the amplitude of excitation is secured to some extent, the conventional testing machine that confirms the ease of loosening is performed by increasing the inertial force to some extent while avoiding the above-mentioned untestable situation. As described above, a function capable of loosening the screw structure can also be imparted.

Next, a second embodiment according to the present invention will be described with reference to FIG. Since the above-mentioned explanations regarding the contents shown in FIGS. 5 and 6 in the first embodiment are common to the second embodiment, duplicate explanations regarding these contents will be omitted.

In the present embodiment, instead of the second member 162 in the first embodiment, the arm-shaped second member 165 extending to the left and right is provided. However, since the other configurations are exactly the same as those in the first embodiment, the description of the same parts will be omitted. The second member 165 includes a central portion 165a tightened to the first member 161 by bolts 163 and nuts 164, a pair of arm portions 165b and 165b extending to the left and right from the central portion 165a, and these arms. The weight portions 165c and 165c fixed to the tip of the portion 165b are provided. Further, the second member 165 is connected to the left and right weight portions 165c, and each includes an extension portion 165d extending downward toward the surface of the substrate 13. The tip of the extension portion 165d may be in contact with the surface of the substrate 13, for example, but in the illustrated example, it is slightly separated from the surface of the substrate 13.

In the present embodiment, since the second member 165 is provided with the arm portion 165b extending from the central portion 165a and the weight portion 165c connected to the arm portion 165b, the inertial force acting on the second member 165 is increased. A larger load can be applied to the screw structure of the screw fastening body 16 than in the first embodiment. Therefore, when the proof stress of the screw structure composed of the bolt 163 and the nut 164 is large, by applying a sufficient load to the screw structure, the fastening status of the screw structure can be easily detected and the detection accuracy can be improved. can do. Further, although it is necessary to secure an amplitude due to a certain degree of vibration, the screw structure is intentionally loosened by applying a large load to the screw structure, thereby determining the ease of loosening of the screw fastening body 16. It is also possible to carry out tests. Further, the left-right symmetrical structure including the arm portion 165b and the weight portion 165c also contributes to the suppression of the rotation component around the axis 16x at the time of excitation.

Further, when the first member 161 is vibrated and vibration is generated in the screw fastening body 16 by providing the second member 165 with an extension portion 165d that extends downward and reaches a position extremely close to the surface of the substrate 13. It is possible to suppress the occurrence of oscillating motion in the direction of rotating around the axis 16x of the screw structure due to the vibration by the restricting action. In the illustrated example, by providing a pair of left and right extension portions 165d, rotation in either the left or right direction can be suppressed by the restricting action of the surface of the substrate 13. As such a rotation suppressing means, for example, a rotation direction formed around the axis 16x of the screw structure between the first member 161 and the second member 162, 165 (for example, the central portion 165a). It may be configured by a stopper structure or the like.

According to the present embodiment, as the mass of the second member 165 (or the mass connected to the second member) increases, the inertial force when the screw fastening body 16 vibrates increases, so that the screw structure is formed. It can give a large load. Therefore, the vibration energy given to the screw structure increases due to the above-mentioned inertial force generated based on the vibration component (driving vibration component) given by the vibration, which reflects the tightening state of the screw structure in the vibration waveform signal 16d. Since the generated vibration component (driven vibration component) also becomes large, it becomes easy to determine the screw fastening status from the vibration waveform signal 16d, and a highly accurate determination becomes possible. Further, in this case, if sufficient amplitude is generated by the exciter 14, loosening is likely to occur even in the tightened screw structure. Further, in this configuration, the rotation suppressing means (extension portion 165d) described above can suppress the rotation of the screw fastening body 16 around the axis 16x during vibration, so that the vibration is performed by the exciter 14. Only the axis perpendicular component can be left, and the rotation component can be eliminated. Therefore, when used for the purpose of determining only the screw fastening status, it becomes easier to maintain the fastening status at the time of the test, and when used for the purpose of testing the ease of loosening of the screw, it rotates. It is possible to avoid the loosening promoting action of the components and improve the accuracy of the loosening test in the direction perpendicular to the axis.

Next, a third embodiment according to the present invention will be described with reference to FIG. Since the above-mentioned explanations regarding the contents shown in FIGS. 5 and 6 in the first embodiment are common to the third embodiment, duplicate explanations regarding these contents will be omitted.

In the third embodiment, instead of the exciter 14 of the first embodiment, the screw loosening test device 20 using the exciter 24 made of an ultrasonic oscillator is configured. As the exciter 24 made of an ultrasonic oscillator, for example, a bolt-tightened Langevin type oscillator (BLT) can be used, but is not particularly limited. Further, a conical horn 24a is attached to the exciter 24 composed of an ultrasonic vibrator, and the horn 24a is connected and fixed to the substrate 23. The substrate 23 is fixed to a support plate 22 provided on the box-shaped base frame 21.

Also in this third embodiment, the same connection member 15 as in the first embodiment and the screw fastening body 16 attached to the connecting member 15 are used. In the first embodiment, the connecting member 15 is attached along the axis 14x of the exciting portion 14a of the exciter 14, and is mounted along the axis 24x of the exciter 24 and its horn 24a. It is attached and fixed to the board 23. The excitation direction F of the ultrasonic vibrator at this time is a direction along the axis 24x. Further, since the connecting member 15 and the screw fastening body 16 of this embodiment can be configured in the same manner as those of the first embodiment, their description will be omitted.

In the present embodiment, ultrasonic waves (for example, a frequency of 15 to 60 kHz, for example, 29 kHz) emitted from the exciter 24 are applied to the connecting member 15 and the screw fastening body 16 on the substrate 23 via the horn 24a. At this time, it is preferable that the shape and dimensions of the horn 24a are adjusted so that the ultrasonic node is generated at the position of the mounting surface of the substrate 23 with respect to the support plate 22. As a result, the ultrasonic energy can be efficiently propagated to the screw fastening body 16. Further, it is preferable that the antinode of the ultrasonic wave is formed at a position on the connecting member 15 at a position intersecting the axis 16x of the screw structure of the screw fastening body 16. As a result, the excitation energy given to the screw fastening body 16 can be increased.

The screw fastening body 16 is vibrated and vibrated by ultrasonic waves. In this case, since the vibration is performed at a higher frequency than in each of the above embodiments, the frequency of the vibration direction F of the screw fastening body 16 itself is also high, high acceleration is generated in each part, and high vibration energy is generated. Be in a state. On the other hand, when ultrasonic waves were used, the amplitude was small, about 0.01 to 0.05 μm. By receiving high vibration energy in this way, it becomes possible to detect the screw fastening status with high accuracy. On the other hand, since the amount of strain of the screw fastening body 16 is small even in a vibrating state due to the small amplitude, it is difficult to affect the screw fastening status, and the screw fastening status is easily maintained. It can be seen that the device 20 is suitable for use for the purpose of detecting the situation with high accuracy. On the contrary, since it is difficult to create a loosened state of the screw by the vibration caused by the ultrasonic wave, it may not be suitable for testing the looseness of the screw.

In the present embodiment, although the vibration frequency and amplitude bands of the exciter 24 are different, the overall configuration of the main body of the screw loosening test device 20 is different from that of the main body 10A of the device 10 of each of the above embodiments. , The method of detecting the vibration mode in the axial direction indicating the screw fastening state, the sensors such as the laser displacement meters 18 and 19, and their operations are completely the same as the contents of the detection unit 10B shown in FIGS. 5 and 6.

Next, a fourth embodiment according to the present invention will be described with reference to FIG. Since the above-mentioned explanations regarding the contents shown in FIGS. 5 and 6 in the first embodiment are common to the fourth embodiment, duplicate explanations regarding these contents will be omitted.

In this embodiment, the same exciter 24 composed of the base frame 21, the support plate 22, the substrate 23, and the ultrasonic oscillator is provided as in the third embodiment, and the same as in the first embodiment. Since it has a connecting member 15 and a screw fastening body 16, the description thereof will be omitted.

In the present embodiment, instead of the second member 161 similar to the first embodiment, a second member 166 similar to the second embodiment is provided. The second member 166 has an arm portion 166b and 166b extending to the left and right from the central portion 166a, and a weight portion 166c connected to the tip of each of these arm portions 166b. On the other hand, guide portions 25 and 25 are provided on the left and right portions of the base frame 21, and these guide portions 25 guide the arm portion 166b or the weight portion 166c in the vibration direction F so as to be slidable. In the illustrated example, the weight portion 166c is slidably supported in the vibration direction F on the guide surface 25a of the guide portion 25.

In the present embodiment, as in the second embodiment, a large mass is applied to the second member 166, so that when the screw fastening body 16 vibrates, the screw structure receives a large inertial force from the second member 166. Therefore, since a large load can be applied to the screw structure, it is possible to improve the accuracy of detecting the screw fastening status and facilitate the test of the screw fastening status as in the second embodiment. Further, since the inertial force can be adjusted by adjusting the length of the arm portion 166b and the mass of the weight portion 166c, the inertial force by the second member 166 can be appropriately set according to the purpose to detect the fastening state. It is possible to improve the accuracy and optimize the test conditions of the fastening condition.

Although not shown in this embodiment, for example, a guide groove or a guide rib (linear) along the vibration direction F between the left and right guide portions 25, 25 (guide surfaces 25a) and the arm portion 166b or the weight portion 166c. By providing a guide structure similar to a guide) so as to fit each other, the second member 166 can be used as a rotation suppressing means that does not rotate around the axis 16x of the screw structure. The action and effect of this rotation suppressing means is the same as that of the second embodiment.

The second members 162 and 166 are not movably configured as in the third embodiment and the present embodiment, but the second member is fixed to the base frame 21, for example, the left and right guide portions 25, 25. It may be fixed to. In the third embodiment and the present embodiment, the exciter 24 generates ultrasonic waves, but since the amplitude thereof is small, there is little possibility that an excessive load is applied to the screw structure even if the second member is fixed. Therefore, it is possible to detect the tightening status of screws and perform a looseness test on small-diameter bolts and screws without any trouble. The fixing of the second member may be carried out in the first embodiment or the second embodiment.

Finally, an example of a specific vibration waveform will be described. 7-10 show the vibration waveform measured in the second embodiment. FIG. 7 is a vibration waveform in the vibration direction based on the position measurement signal 19t in the vibration direction F measured by the laser displacement meter 19. At this time, the excitation frequency fd = 50 Hz, and the excitation voltage is Vd = 1.0 V. The vibration mode of the vibration direction F hardly changed between when the screw structure of the screw fastening body 16 was in the tightened state and when it was in the loosened state. Further, FIG. 8 shows an axial vibration waveform based on the axial position measurement signal 18t measured by the laser displacement meter 18 when the screw fastener 16 is in the tightened state when the vibration is continued under the same conditions. The vibration waveform by the signal 16d is shown. The range of vibration in the axial direction at this time was −135 μm − + 25 μm, and the amplitude variation of about 150 μm was about 15-25% (about 20%).

FIG. 9 shows a change in the vibration waveform in the axial direction when a screw is loosened in the screw fastening body 16 in the middle when vibration is continued under the same conditions as described above. After the loosening occurs, the vibration range shifts to 0-200 μm, and the vibration range at the axial position moves to the plus side (the side where the measurement distance of the laser displacement meter 18 increases). Here, in the position measurement by the laser displacement meter 18, the movement to the plus side corresponds to the case where the distance between the laser displacement meter 18 and the measurement target (screw fastening body 16) becomes closer (smaller), so that the screw fastening body This means that the surface of the second member 162 of 16 has moved from the first member 161 to the front side. This is consistent with the loosening of the screws of the screw fastener 16. Further, the amplitude variation at this time increased from the degree shown in FIG. 8 as shown in FIG. 9, and the amplitude variation was about 50-90% (about 70%).

FIG. 10 shows a vibration mode of the screw fastening body 16 in the direction of the axis 16x and vibration in the vibration direction F when the screw fastener 16 is vibrated at a vibration frequency fd = 50 Hz and a vibration voltage Vd = 0.5 V in the second embodiment. It is a graph which shows in comparison with the aspect. In this example, the sampling frequencies of the position measurement signals 18t and 19t of the laser displacement meters 18 and 19 are set to 40 kHz, and the display is performed under the condition that the measurement points in one vibration cycle are about 800 points. At this time, the screw fastening body 16 is in a tightened state, and although there is a phase difference between the vibration mode in the axis 16x direction and the vibration mode in the vibration direction F, the stability of the vibration range and the variation in amplitude There was almost no difference in terms of. As described above, the difference between the vibration mode of the vibration direction F when the screw fastening body 16 is in the tightened state and the vibration mode when the screw fastening body 16 is in the loosened state is smaller than the change in the vibration mode in the direction of the axis 16x. Therefore, by comparing the vibration mode in the direction of the axis 16x in the tightened state with the vibration mode in the excitation direction F, the fastening state (tightened state or loosened state) of the screw structure can be reliably detected and determined. You can see that you can.

Here, with respect to the determination of the fastening state such as whether or not the screw fastening body 16 is loosened or how much the screw is loosened, a predetermined condition is set with the above vibration mode, and the relevant setting is made. It is preferable to make a judgment according to the conditions. For example, when making a judgment based on the vibration range of the position in the axial direction, how to obtain the vibration range (calculation method for determining the range) and the shift amount from the reference value of the vibration range. Determine the threshold value to be used when determining. Further, when making a judgment based on the variation in the amplitude of the position in the axial direction, the difference between the method of obtaining the variation in the amplitude (calculation method for obtaining the variation) and the reference value of the variation in the amplitude. Determine the threshold value to be used at the time of judgment. The specific elements of the vibration mode used for the determination (the above-mentioned vibration range, stability of the vibration range, variation in amplitude, etc.) may be appropriately changed depending on the situation.

It should be noted that the method and apparatus for testing the screw fastening state according to the present invention are not limited to the above-mentioned illustrated examples, and it goes without saying that various changes can be made without departing from the gist of the present invention. .. For example, in each of the above embodiments, an example is shown in which a screw fastening body is attached to a vibration exciter to test a screw fastening state, a screw looseness test, and the like. The present invention is not limited to this, and for example, it can be applied to the case where an existing building is vibrated by a vibrator and the screw fastening state of the screw fastening body existing in the building is tested. In addition, the term "test" used in the present specification does not include only actions performed by existing methods, but also various actions (fastening) that can be performed in various situations for confirming the screw fastening status. It includes detection, derivation, calculation, evaluation, etc. of information related to the situation).

10, 20 ... Test device for screw fastening status, 10A ... Main body, 10B ... Detection unit, 11 ... Anti-vibration table, 12 ... Support, 13, 23 ... Board, 13a ... Opening, 14, 24 ... Exciter , 14a ... Vibration part, 15 ... Connection member, 15a ... Mounting surface, 15b ... Recession, 16 ... Screw fastener, 161 ... First member, 162 ... Second member, 163 ... Bolt, 164 ... Nut, 16d ... Vibration Waveform signal, 16s ... Screw fastening status determination result, 17 ... Mounting member, 17a, 17b ... Mounting bracket, 18, 19 ... Laser displacement meter, 18t ... Position measurement signal, 18A ... Vibration mode detector, 18B ... Screw fastening status determination Instrument, 18C ... Judgment display, 19t ... Position measurement signal, 21 ... Base frame, 22 ... Support plate, 25 ... Guide unit, 25a ... Guide surface, 24a ... Horn, 101 ... Measuring instrument, 101a ... Axial position measurement value Display unit, 101b ... Vibration direction position measurement value display unit, 101c ... Axial vibration waveform display unit, 101d ... Vibration direction vibration waveform display unit

Claims (15)

A second member that intersects the first direction of the screw fastening body in a state where the screw fastening body in which the first member and the second member are fastened by the screw structure is vibrated and vibrated in the first direction. A method for testing a screw fastening state, which comprises measuring a position in a direction by a non-contact method and detecting a vibration mode of the position in the second direction. The second direction is the axial direction of the screw structure.
The method for testing a screw fastening state according to claim 1. The position in the second direction is measured by an optical sensor.
The method for testing a screw fastening state according to claim 1 or 2. The optical sensor is a laser displacement meter.
The method for testing a screw fastening state according to claim 3. The vibrating action on the screw fastening body is given to the first member, and the measurement site of the position in the second direction on the screw fastening body is the second member.
The method for testing a screw fastening state according to any one of claims 1-4. Further including a step of determining the fastening state of the screw structure according to the vibration mode.
The method for testing a screw fastening state according to any one of claims 1-5. In the step, the vibration mode used to determine the fastening state of the screw structure is at least one of the vibration range and the amplitude variation of the position in the second direction.
The method for testing a screw fastening state according to claim 6. In the step, the fastening state of the screw structure is determined by comparing the vibration mode with the vibration mode of the screw fastening body in the first direction.
The method for testing a screw fastening state according to claim 6 or 7. The vibrating action on the screw fastening body is given to the first member, and the second member is movably configured.
The method for testing a screw fastening state according to any one of claims 1-8. It has a weight connected to the second member, and the weight is configured to give an inertial force to the second member according to the operating state of the second member.
The method for testing a screw fastening state according to claim 9. The second direction is the axial direction of the screw structure.
The weights are connected to the second member on both sides of the axis of the screw structure and in a direction orthogonal to the axis direction with respect to the first member, respectively, and the weights on both sides provide the second member. It is configured so that the second member is given an inertial force equal to each other when the one member is vibrated.
The method for testing a screw fastening state according to claim 10. Further provided with rotation suppressing means for suppressing rotation of the screw structure around the axis of the screw fastening body.
The rotation suppressing means includes a regulating member that is directly or indirectly connected to the second member and is configured to be in contact with a fixed portion around the axis.
The method for testing a screw fastening state according to any one of claims 9-11. A vibrator that vibrates a screw fastener in which a first member and a second member are fastened by a screw structure in a first direction, and a state in which the screw fastening body is vibrated by the vibration device, the first member. A position measuring means for measuring the position in the second direction intersecting the one direction by a non-contact method, and a vibration measuring means for measuring the vibration mode in the second direction based on the measurement result by the position measuring means. A test device for a screw fastening state, which comprises. The exciter is composed of a voice coil motor.
The test apparatus for a screw fastening state according to claim 13. The exciter is composed of an ultrasonic oscillator.
The test apparatus for a screw fastening state according to claim 13.

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