Dynamic characteristics measurement device

Abstract

To accurately measure the dynamic characteristics of a workpiece in the low-frequency range.SOLUTION: A dynamic characteristics measurement device 1 includes an upper mass 60 that is disposed on an upper side Z1 relative to a workpiece W and that holds the workpiece W, a lower mass 20 that is disposed on a lower side Z2 relative to the workpiece W and that holds the workpiece W, a frame 10 that is placed on a foundation G, upper vibration isolating rubbers 70 that support the upper mass 60 relative to the frame 10, lower vibration isolating rubbers 30 that support the lower mass 20 relative to the frame 10, a vibration exciter 40 that applies vibration E to the workpiece W, a load cell 80 that detects a load F applied to the workpiece W by the vibration exciter 40, and a controller 100 that measures a dynamic spring constant K of the workpiece W based on the load F detected by the load cell 80. The upper mass 60 is suspended from the frame 10 by the upper vibration isolating rubbers 70.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a dynamic characteristic measuring device. [Background technology]

[0002] A dynamic characteristic measuring device for measuring the dynamic characteristics of a workpiece is known. The dynamic characteristic measuring device according to Patent Document 1 includes a base, a support placed on the upper part of the base so as to be in a floating state via an air spring, an electrodynamic vibrator provided on the side of the base of a test object attached between the base and the support and applying vibrations to the test object, and a load washer provided on the side of the support of the test object and measuring the dynamic load applied to the test object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-085528 ​​A Summary of the Invention [Problem to be solved by the invention]

[0004] In the dynamic characteristic measuring device, a vibrator applies vibrations to a workpiece while changing the frequency, thereby measuring the dynamic characteristics of the workpiece at various frequencies.

[0005] However, in conventional dynamic characteristic measuring devices, when vibrations are applied to a workpiece by a vibrator, resonance occurs in the low frequency range, and there is a problem that the dynamic characteristics of the workpiece in the low frequency range cannot be measured with high accuracy.

[0006] The present disclosure has been made in consideration of the above points, and has an object to accurately measure the dynamic characteristics of a workpiece in the low frequency range. [Means for solving the problem]

[0007] The dynamic characteristic measuring device of the present disclosure comprises a first mass arranged on one of the upper and lower sides in a vertical direction relative to a workpiece and holding the workpiece, a second mass arranged on the other of the upper and lower sides in the vertical direction relative to the workpiece and holding the workpiece, a frame placed on a foundation, a first elastic body supporting the first mass on the frame, a second elastic body supporting the second mass on the frame, a vibrator that applies vibration to the workpiece, a load sensor that detects the load applied to the workpiece by the vibrator, and a controller that measures the dynamic characteristics of the workpiece based on the load detected by the load sensor, wherein the first mass is suspended from the frame by the first elastic body.

[0008] With this configuration, the first mass is suspended from the frame by the first elastic body, so that when the vibrator applies vibration to the workpiece, the combination of the first mass and the first elastic body performs pendulum vibration. Because the combination of the first mass and the first elastic body performs pendulum vibration, the natural frequency of the combination of the first mass and the first elastic body can be reduced.

[0009] In order to prevent the combination of the first mass and the first elastic body from resonating, the frequency of the vibration that the vibrator applies to the workpiece should be made higher than the natural frequency of the combination of the first mass and the first elastic body. The lower the natural frequency of the combination of the first mass and the first elastic body, the more advantageous it is in suppressing the occurrence of resonance in the low frequency range.

[0010] The dynamic characteristic measuring device can accurately measure the dynamic characteristics of a workpiece in the low frequency range.

[0011] In one embodiment, the first mass is spherical in shape.

[0012] With this configuration, because the first mass is spherical, the natural frequency of the first mass alone can be increased. In order to prevent the first mass from resonating, the frequency of the vibration applied to the workpiece by the vibrator should be set lower than the natural frequency of the first mass alone. The higher the natural frequency of the first mass alone, the more advantageous it is in suppressing the occurrence of resonance in the high frequency range.

[0013] In one embodiment, the load sensor is disposed on a side of the first mass relative to the workpiece, and the vibration exciter is disposed on a side of the second mass relative to the workpiece.

[0014] According to this configuration, the layout of the load sensor and the vibrator becomes easier.

[0015] In one embodiment, the first mass is disposed above the workpiece, and the second mass is disposed below the workpiece.

[0016] According to this configuration, the layout of the first mass and the second mass is facilitated.

[0017] In one embodiment, the natural frequency of the combination of the first mass body and the first elastic body is 10 Hz or less.

[0018] This configuration is advantageous in suppressing resonance of the combination of the first mass body and the first elastic body.

[0019] In one embodiment, the first mass has a natural frequency of 5000 Hz or more.

[0020] This configuration is advantageous in suppressing resonance of the first mass alone.

[0021] In one embodiment, the first elastic body is connected to the frame and to a portion of the first mass that is above the center in the up-down direction.

[0022] According to this configuration, the combination of the first mass body and the first elastic body is likely to perform pendulum oscillation, which is advantageous in reducing the natural frequency of the combination of the first mass body and the first elastic body.

[0023] In one embodiment, the frame includes a pillar extending in the vertical direction, and a first rigid member and a second rigid member attached to the pillar and facing each other in the vertical direction, the first mass being supported by the first elastic body with respect to the first rigid member, the second mass being supported by the second elastic body with respect to the second rigid member, and the first mass being suspended by the first elastic body with respect to the first rigid member.

[0024] With this configuration, it becomes easy to support the first mass and the second mass relative to the frame.

[0025] In one embodiment, a displacement sensor is provided to detect the displacement of the workpiece caused by the vibration exciter, and the controller measures a dynamic spring constant as the dynamic characteristic of the workpiece based on the load detected by the load sensor and the displacement detected by the displacement sensor.

[0026] According to this configuration, the dynamic spring constant of the workpiece, which is a representative index expressing the dynamic characteristics of the workpiece, can be measured with high accuracy in the low frequency range. Effect of the Invention

[0027] According to the present disclosure, the dynamic characteristics of a workpiece in the low frequency range can be measured with high accuracy. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 shows a front view of the dynamic characteristics measuring device. [Diagram 2] FIG. 2 shows a rear view of the dynamic characteristic measuring device. [Diagram 3] FIG. 3 is a left side view of the dynamic characteristic measuring device. [Figure 4] FIG. 4 shows a right side view of the dynamic characteristic measuring device as seen from the right side. [Diagram 5] FIG. 5 shows a plan view of the dynamic characteristic measuring device as seen from above. [Figure 6] FIG. 6 shows a bottom view of the dynamic characteristic measuring device. [Figure 7] FIG. 7 is a perspective view showing the dynamic characteristic measuring device as seen obliquely from above. [Figure 8] FIG. 8 is a perspective view showing the dynamic characteristic measuring device as viewed obliquely from below. [Figure 9] FIG. 9 is a front view showing the periphery of a workpiece in the dynamic characteristic measuring device as viewed from the front side. [Figure 10] FIG. 10 shows a schematic diagram of the pendulum vibration of the combination of the upper mass and the upper vibration isolator. [Figure 11] FIG. 11 is a graph showing vibration characteristics over a range from low frequency to high frequency when the upper mass and upper vibration isolator are combined. [Figure 12] FIG. 12 is a graph showing vibration characteristics, particularly in the low frequency range, when the upper mass and upper vibration isolator are combined. [Figure 13] FIG. 13 is a graph showing vibration characteristics when the mass of the upper mass alone is changed. [Figure 14] FIG. 14 is a graph showing vibration characteristics when the shape of the upper mass alone is changed. [Figure 15] FIG. 15 is a schematic diagram showing the swing vibration of the combination of the upper mass and the upper vibration isolator according to the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its application, or its uses.

[0030] (Dynamic characteristics measuring device) 1 to 9 show a dynamic characteristic measuring device 1. The dynamic characteristic measuring device 1 is also called a dynamic characteristic measuring machine. The dynamic characteristic measuring device 1 measures a dynamic spring constant K as a dynamic characteristic in the up-down direction Z of a workpiece W. The up-down direction Z is a vertical direction. The upper side Z1 of the up-down direction Z is one side of the upper side Z1 and the lower side Z2 in the up-down direction Z. The lower side Z2 of the up-down direction Z is the other side of the upper side Z1 and the lower side Z2 in the up-down direction Z. The horizontal direction is a direction perpendicular to the up-down direction, and includes the left-right direction and the front-back direction.

[0031] FIG. 1 shows a front view of the dynamic characteristic measuring device 1 as seen from the front side. FIG. 2 shows a rear view of the dynamic characteristic measuring device 1 as seen from the rear side. FIG. 3 shows a left side view of the dynamic characteristic measuring device as seen from the left side. FIG. 4 shows a right side view of the dynamic characteristic measuring device 1 as seen from the right side. FIG. 5 shows a plan view of the dynamic characteristic measuring device 1 as seen from the upper side Z1. FIG. 6 shows a bottom view of the dynamic characteristic measuring device 1 as seen from the lower side Z2. FIG. 7 shows a perspective view of the dynamic characteristic measuring device 1 as seen from diagonally above. FIG. 8 shows a perspective view of the dynamic characteristic measuring device 1 as seen from diagonally below. FIG. 9 shows a front view of the periphery of the workpiece W in the dynamic characteristic measuring device 1 as seen from the front side.

[0032] As shown in FIG. 1, the dynamic characteristic measuring device 1 includes a frame 10, a lower mass 20 as a second mass body, a lower vibration-proof rubber 30 as a second elastic body, a vibration exciter 40, an upper mass 60 as a first mass body, a workpiece receiver 61, an upper vibration-proof rubber 70 as a first elastic body, a load cell 80 as a load sensor, a displacement sensor 90, and a controller 100.

[0033] (Frame) As shown in Figures 1 to 8, the frame 10 includes four pillars 11, a lower plate 12, a middle plate 13 as a second rigid member, an upper plate 14 as a first rigid member, two supporters 15, and a screw jack mechanism 16.

[0034] The frame 10 is made of metal. The rigidity of the frame 10 is higher than the rigidity of the lower vibration-proof rubber 30 and the upper vibration-proof rubber 70. The rigidity of the middle plate 13 is higher than the rigidity of the lower vibration-proof rubber 30. The rigidity of the upper plate 14 is higher than the rigidity of the upper vibration-proof rubber 70.

[0035] The four pillars 11 are arranged to correspond to the corners of a rectangle. The pillars 11 are columnar. The pillars 11 extend in the vertical direction Z. The lower plate 12, the middle plate 13, and the upper plate 14 are provided on the pillars 11. Each of the plates 12, 13, and 14 is formed in a rectangular shape extending in the horizontal direction. The four pillars 11 penetrate holes provided at the four corners of each of the plates 12, 13, and 14. The plates 12, 13, and 14 are lined up in the vertical direction Z from the lower side Z2 to the upper side Z1 in the order of the lower plate 12, the middle plate 13, and the upper plate 14.

[0036] The lower plate 12 of the frame 10 is placed on a foundation G. The foundation G is, for example, a floor surface. The foundation G extends in the horizontal direction. The upper surface of the middle plate 13 and the lower surface of the upper plate 14 face each other in the vertical direction Z.

[0037] The two supporters 15 extend in the front-rear direction and connect the front support column 11 and the rear support column 11. The ends of the supporters 15 grip the support columns 11. The supporters 15 are movable in the up-down direction Z relative to the support columns 11. The supporters 15 are disposed between the middle plate 13 and the upper plate 14 in the up-down direction Z.

[0038] The screw jack mechanism 16 includes two screw rods 16a, two cradles 16b, and a handle 16c. The screw rod 16a extends in the up-down direction Z between the lower plate 12 and the supporter 15. The two screw rods 16a pass through holes provided at the left and right ends of the lower plate 12 and holes provided at the left and right ends of the middle plate 13. The two cradles 16b correspond to the two screw rods 16a. The cradles 16b are engaged with the screw rods 16a. The cradles 16b are disposed on the lower side Z2 of the middle plate 13 and support the middle plate 13. The handle 16c is for rotating the screw rods 16a.

[0039] By rotating the threaded rod 16a with the handle 16c, the receiving base 16b and the supporter 15 move in the vertical direction Z2. When the receiving base 16b and the supporter 15 move in the vertical direction Z, the middle plate 13 also moves in the vertical direction Z in conjunction with them.

[0040] (Lower mass, lower vibration isolator) 1 to 8, the lower mass 20 is cylindrical with an axis O extending in the up-down direction Z. The lower mass 20 is made of metal. The lower mass 20 is disposed on an upper side Z1 above an upper surface of the middle plate 13 of the frame 10.

[0041] The lower vibration-proof rubbers 30 are disposed between the upper surface of the middle plate 13 of the frame 10 and the lower surface of the lower mass 20. There are six lower vibration-proof rubbers 30, spaced at 60° intervals from the cylindrical lower mass 20. The lower vibration-proof rubbers 30 are made of rubber.

[0042] The lower mass 20 is placed on the upper surface of the middle plate 13 of the frame 10 via a lower vibration-proof rubber 30. The lower vibration-proof rubber 30 supports the lower mass 20 against the upper surface of the middle plate 13 of the frame 10. The lower mass 20 is supported by the lower vibration-proof rubber 30 under compression against the upper surface of the middle plate 13 of the frame 10. The lower mass 20 is also called a floating mass.

[0043] The lower mass 20, as a single unit, has a predetermined mass and a predetermined spring constant. The spring constant of the lower mass 20 is determined by the shape of the lower mass 20, etc. The lower mass 20, as a single unit, has a predetermined natural frequency. The natural frequency of the lower mass 20 as a single unit is determined mainly by the mass of the lower mass 20 and the spring constant of the lower mass 20 (due to the shape, etc.).

[0044] Similarly, the lower vibration isolator rubber 30 as a single unit has a predetermined mass and a predetermined spring constant.

[0045] The lower mass 20 and the lower vibration-proof rubber 30 as a combination have a predetermined natural frequency. The natural frequency of the combination of the lower mass 20 and the lower vibration-proof rubber 30 is determined mainly by the mass of the lower mass 20, the spring constant of the lower mass 20, the mass of the lower vibration-proof rubber 30, the spring constant of the lower vibration-proof rubber 30, the number of lower vibration-proof rubbers 30, the method of supporting the lower mass 20 by the lower vibration-proof rubber 30, etc.

[0046] (Vibrator) 1 to 8, the vibration exciter 40 includes a main body 41, a tubular portion 42, an attachment 43, and legs 44. The main body 41 of the vibration exciter 40 is cylindrical with an axis O extending in the vertical direction Z. An actuator is built in the inside of the main body 41 of the vibration exciter 40. The main body 41 of the vibration exciter 40 is disposed on the upper side Z1 above the upper surface of the lower mass 20.

[0047] The tubular portion 42 of the vibration exciter 40 is cylindrical with an axis O extending in the vertical direction Z. In the vibration exciter 40, the tubular portion 42 is fixed to the upper surface of the main body portion 41 and extends from the upper surface of the main body portion 41 to the upper side Z1.

[0048] The attachment 43 of the vibration exciter 40 is rod-shaped with an axis O extending in the vertical direction Z. In the vibration exciter 40, the upper end of the attachment 43 protrudes upward Z1 from the upper surface of the tubular portion 42. In the vibration exciter 40, an actuator built into the main body portion 41 is driven to cause the attachment 43 to vibrate in the vertical direction Z. As shown in FIG. 9, the upper end of the attachment 43 of the vibration exciter 40 is in contact with the lower surface of the workpiece W. The vibration exciter 40 applies vibration E to the workpiece W in the vertical direction Z.

[0049] The legs 44 of the vibration exciter 40 are disposed between the upper surface of the lower mass 20 and the lower surface of the main body 41 of the vibration exciter 40. The legs 44 of the vibration exciter 40 are fixed to the upper surface of the lower mass 20 and also to the lower surface of the main body 41 of the vibration exciter 40.

[0050] (Upper mass, upper vibration isolator) As shown in FIGS. 1 to 8, the upper mass 60 has a spherical shape. The upper mass 60 is made of metal. The upper mass 60 does not have a principal axis of inertia. The upper mass 60 has an infinite number of axis centers. One of the infinite number of axis centers of the upper mass 60 is an axis center O extending in the vertical direction Z. The upper mass 60 is disposed on a lower side Z2 below the lower surface of the upper plate 14 of the frame 10.

[0051] The upper vibration-proof rubber 70 is disposed between the top of the upper mass 60 and the lower surface of the upper plate 14 of the frame 10. There are four upper vibration-proof rubbers 70, arranged at 90° intervals with respect to the spherical upper mass 60. The upper vibration-proof rubbers 70 are made of rubber.

[0052] The upper mass 60 is suspended from the upper plate 14 of the frame 10 by upper vibration-isolating rubber 70. Specifically, the upper mass 60 is suspended from the upper plate 14 of the frame 10 by the upper vibration-isolating rubber 70. The upper vibration-isolating rubber 70 supports the upper mass 60 from the upper plate 14 of the frame 10. The upper mass 60 is supported by being suspended from the upper plate 14 of the frame 10 by the upper vibration-isolating rubber 70. The upper mass 60 is also called a floating mass.

[0053] In detail, as shown in Fig. 5, a through hole 14a penetrating in the up-down direction Z is provided in the center of the upper plate 14 of the frame 10. The upper end of the upper vibration isolating rubber 70 is fixed to the inner peripheral surface of the through hole 14a provided in the upper plate 14 of the frame 12. Meanwhile, as shown in Fig. 9, the lower end of the upper vibration isolating rubber 70 is fixed to a portion 60b (more specifically, near the upper end of the upper mass 60) on the upper side Z1 of the center 60a in the up-down direction Z of the upper mass 60. The upper vibration isolating rubber 70 is connected to the upper plate 14 of the frame 10 and the portion 60b on the upper side of the center 60a in the up-down direction Z of the upper mass 60.

[0054] The upper mass 60, as a single unit, has a predetermined mass and a predetermined spring constant. The spring constant of the upper mass 60 is determined by the shape of the upper mass 60, etc. The upper mass 60, as a single unit, has a predetermined natural frequency fa. The natural frequency fa of the upper mass 60 as a single unit is determined mainly by the mass of the upper mass 60 and the spring constant of the upper mass 60 (due to the shape, etc.).

[0055] The natural frequency fa of the upper mass 60 alone is preferably 5000 Hz or more. The natural frequency fa of the upper mass 60 alone is more preferably 7500 Hz or more. The natural frequency fa of the upper mass 60 alone is further preferably 10000 Hz or more.

[0056] Similarly, the upper vibration isolator 70 has a predetermined mass and a predetermined spring constant as a single unit.

[0057] The upper mass 60 and the upper vibration-proof rubber 70 as a combination have a predetermined natural frequency fb. The natural frequency fb of the combination of the upper mass 60 and the upper vibration-proof rubber 70 is determined mainly by the mass of the upper mass 60, the spring constant of the upper mass 60, the mass of the upper vibration-proof rubber 70, the spring constant of the upper vibration-proof rubber 70, the number of upper vibration-proof rubbers 70, the method of supporting the upper mass 60 by the upper vibration-proof rubber 70, etc.

[0058] The natural frequency fb of the upper mass 60 and the upper vibration isolating rubber 70 combined is preferably 10 Hz or less.

[0059] (Work receiving) 9, the workpiece receiver 61 is fixed to the lower end of the upper mass 60 via the load cell 80. The workpiece receiver 61 includes a lower large diameter portion 61a and an upper small diameter portion 61b. The large diameter portion 61a of the workpiece receiver 61 receives the upper surface of the workpiece W. The small diameter portion 61b of the workpiece receiver 61 contacts the load cell 80.

[0060] (Load Cell) 9, the load cell 80 is disposed between the top surface of the workpiece W and the lower end of the upper mass 60 (through the workpiece receiver 61). The load cell 80 is fixed to the lower end of the upper mass 60. Various known methods can be applied as the load cell 80. The load cell 80 detects a load F in the vertical direction Z applied to the workpiece W by the vibrator 40.

[0061] (Displacement Sensor) As shown in Fig. 9, the displacement sensor 90 is disposed near the vibration exciter 40. Specifically, the displacement sensor 90 is built into the tubular portion 42 of the vibration exciter 40. The displacement sensor 90 detects a displacement δ of the workpiece W in the vertical direction Z caused by the vibration exciter 40. Various known methods can be applied as the displacement sensor 90. In this example, the displacement sensor 90 is actually an acceleration sensor, and the displacement δ is calculated by integrating the obtained acceleration by the controller 100.

[0062] (Work) As shown in FIG. 9, the workpiece W is disposed between the lower mass 20 and the upper mass 60. The workpiece W is an elastic body. The displacement δ of the workpiece W occurs due to elastic deformation of the workpiece W. The workpiece W is, for example, an anti-vibration rubber. The anti-vibration rubber may be applied, for example, to a vehicle anti-vibration device. The workpiece W is not limited to being an anti-vibration rubber and may be in any form.

[0063] In this example, the workpiece W includes a main body W1, a lower held part W2, and an upper held part W3. The main body W1 is cylindrical with an axis O extending in the vertical direction Z. The lower held part W2 is disc-shaped and covers the lower surface of the main body W1. The upper held part W3 is disc-shaped and covers the upper surface of the main body W1. The outer diameter of the lower held part W2 and the outer diameter of the upper held part W3 are larger than the outer diameter of the main body W1.

[0064] The lower mass 20 is disposed on the lower side Z2 relative to the workpiece W. The lower mass 20 holds the workpiece W from the lower side Z2 (via the vibrator 40). More specifically, the lower mass 20 holds the lower surface of the lower held portion W2 of the workpiece W. The upper mass 60 is disposed on the upper side Z1 relative to the workpiece W. The upper mass 60 holds the workpiece W from the upper side Z1 (via the workpiece receiver 61 and the load cell 80). More specifically, the upper mass 60 holds the upper surface of the upper held portion W3 of the workpiece W.

[0065] The vibration exciter 40 is disposed between the upper surface of the lower mass 20 and the lower surface of the workpiece W. That is, the vibration exciter 40 is disposed on the lower side Z2, which is the side of the lower mass 20, with respect to the workpiece W.

[0066] The load cell 80 is disposed between the top surface of the workpiece W and the lower end of the upper mass 60. That is, the load cell 80 is disposed on the upper side Z1, which is the upper mass 60 side, with respect to the workpiece W. On the other hand, the displacement sensor 90 is disposed on the lower side Z2, which is the lower mass 20 side, with respect to the workpiece W.

[0067] (controller) The controller 100 is composed of a microcomputer and a program. The controller 100 is connected to the vibration exciter 40, the load cell 80, and the displacement sensor 90. The controller 100 measures (calculates) a dynamic spring constant K as a dynamic characteristic of the workpiece W, based on the load F in the vertical direction Z detected by the load cell 80 and the displacement δ in the vertical direction Z detected by the displacement sensor 90. The dynamic spring constant K [N / mm] is obtained by dividing the load F [N] by the displacement δ [mm] (dynamic spring constant K [N / mm] = load F [N] / displacement δ [mm]).

[0068] (Pendulum vibration of the combination of the upper mass 60 and the upper vibration isolating rubber 70) 10 shows a schematic diagram of the pendulum vibration P of the combination of the upper mass 60 and the upper vibration-proof rubber 70. As described above, the upper mass 60 is suspended from the upper plate 14 of the frame 10 by the upper vibration-proof rubber 70. The upper vibration-proof rubber 70 is connected to the upper plate 14 of the frame 10 and to a portion 60b of the upper mass 60 above the center 60a in the vertical direction Z.

[0069] At this time, the combination of the upper mass 60 and the upper vibration-proof rubber 70 causes pendulum oscillation P, starting from the upper vibration-proof rubber 70 fixed to the part 60b above the center 60a of the upper mass 60 in the vertical direction Z.

[0070] Here, FIG. 15 shows a schematic diagram of a swing vibration P' of a combination of an upper mass 60' and an upper vibration-proof rubber 70' according to the conventional technology. In the conventional technology, the upper mass 60' includes a main body 61' and a lower extension 62'. The main body 61' of the upper mass 60' is supported by the upper vibration-proof rubber 70' against the upper surface of the upper plate 14 of the frame 10 under compression. In the upper mass 60', the lower extension 62' extends from the main body 61' to the lower side Z2. The lower extension 62' of the upper mass 60' passes through a hole formed in the upper plate 14 of the frame 10 and protrudes to the lower side Z2 below the lower surface of the upper plate 14 of the frame 10.

[0071] A load cell 80 is fixed to the lower end of the lower extension 62' of the upper mass 60'. The main body 61' of the upper mass 60' is disposed on the upper side Z1 above the upper vibration-proof rubber 70'. The lower extension 62' of the upper mass 60' is disposed on the lower side Z2 below the upper vibration-proof rubber 70'.

[0072] At this time, the combination of the upper mass 60' and the upper vibration-proof rubber 70' in the conventional technology generates a swaying vibration P' starting from the upper vibration-proof rubber 70' arranged between the main body portion 61' and the lower extension portion 62' of the upper mass 60'.

[0073] (Vibration characteristics of the combination of the upper mass 60 and the upper vibration isolating rubber 70) Fig. 11 is a graph showing vibration characteristics over a range from low frequency to high frequency when the upper mass 60 and the upper vibration isolating rubber 70 are combined. Fig. 12 is a graph showing vibration characteristics, particularly in the low frequency range, when the upper mass 60 and the upper vibration isolating rubber 70 are combined.

[0074] The horizontal axis is the frequency f [Hz] of the vibration E given to the workpiece W by the vibration exciter 40. The vertical axis is the vibration transmissibility Eb [-] for the combination of the upper mass 60 and the upper vibration-proof rubber 70. In Figures 11 and 12, the compression mode R1 is indicated by a solid line, and the tension mode R2 is indicated by a dashed line. Note that there is no significant difference between the compression mode R1 and the tension mode R2, so the following description will be given without making any particular distinction between them.

[0075] The upper mass 60 is spherical. The mass of the upper mass 60 is 40 kg. The diameter of the upper mass 60 is 215 mm. The spring constant of the upper vibration-proof rubber 70 is 20 N / mm. There are four upper vibration-proof rubbers 70. The lower end of the upper vibration-proof rubber 70 is connected to an upper portion 60b by 75% of the length from the center 60a of the upper mass 60 to the upper end of the upper mass 60, rather than the center 60a in the vertical direction Z of the upper mass 60.

[0076] 11, over a wide range of frequencies f of vibration E from low to high frequencies, specifically over a wide range of frequencies f of vibration E from near 0 Hz to 5000 Hz, the vibration transmissibility Eb for the combination of the upper mass 60 and the upper vibration-proof rubber 70 is 1 or less. Although not shown in the graph, the vibration transmissibility Eb is also 1 or less when the frequency f of vibration E is 5000 Hz or higher.

[0077] As shown in FIG. 12, in some regions where the frequency f of vibration E is 10 Hz or less, specifically when the frequency f of vibration E is in the vicinity of 6 Hz to 9 Hz, the vibration transmissibility Eb for the combination of the upper mass 60 and the upper vibration-proof rubber 70 is 1 or more.

[0078] That is, the combination of the upper mass 60 and the upper vibration-proof rubber 70 has a peak Q of the vibration transmissibility Eb in a part of the range where the frequency f of the vibration E applied to the workpiece W by the vibrator 40 is 10 Hz or less.

[0079] It can be seen from FIG. 12 that the natural frequency fb of the combination of the upper mass 60 and the upper vibration-isolating rubber 70 is 10 Hz or less.

[0080] (Vibration characteristics of upper mass alone) 13 is a graph showing vibration characteristics when the mass of the upper mass 60 alone is changed. The horizontal axis is the frequency f [Hz] of the vibration E applied to the workpiece W by the vibrator 40, and the vertical axis is the vibration transmissibility Ea [-] for the upper mass 60 alone.

[0081] In each of the first pattern S1, the second pattern S2, and the third pattern S3, the upper mass 60 is spherical. In the first pattern S1, the mass of the upper mass 60 is 40 kg, and the diameter of the upper mass 60 is 215 mm. In the second pattern S2, the mass of the upper mass 60 is 100 kg, and the diameter of the upper mass 60 is 290 mm. In the third pattern S3, the mass of the upper mass 60 is 400 kg, and the diameter of the upper mass 60 is 461 mm.

[0082] 13, in the first pattern S1, the vibration transmissibility Ea of the upper mass 60 alone reaches a primary peak S1a when the frequency f of the vibration E is near 12000 Hz. In the second pattern S2, the vibration transmissibility Ea of the upper mass 60 alone reaches a primary peak S2a when the frequency f of the vibration E is near 9000 Hz. In the third pattern S3, the vibration transmissibility Ea of the upper mass 60 alone reaches a primary peak S3a when the frequency f of the vibration E is near 5500 Hz.

[0083] FIG. 13 shows that in any of the first pattern S1, second pattern S2, and third pattern S3, i.e., regardless of the mass of the upper mass 60 (40 kg, 100 kg, 400 kg), the natural frequency fa of the upper mass 60 alone is 5000 Hz or higher.

[0084] 13, it can be seen that the natural frequency fa of the upper mass 60 alone is highest in the first pattern S1 (40 kg), followed by the second pattern S2 (100 kg) and the third pattern S3 (400 kg).

[0085] 14 is a graph showing vibration characteristics when the shape of the upper mass 60 alone is changed. The horizontal axis is the frequency f [Hz] of the vibration E applied to the workpiece W by the vibrator 40. The vertical axis is the vibration transmissibility Ea [-] for the upper mass 60 alone.

[0086] In each of the first pattern T1, the second pattern T2, and the third pattern T3, the mass of the upper mass 60 is 40 kg, and the diameter of the upper mass 60 is 215 mm.

[0087] In the first pattern T1, the upper mass 60 is spherical. In the second pattern T2, the upper mass 60 is cylindrical with an axis O extending in the vertical direction Z. In the third pattern T3, the upper mass 60 is cylindrical with an axis O extending in the vertical direction Z and has a chamfered edge (cylindrical + chamfered).

[0088] 14, in the first pattern T1, when the frequency f of the vibration E is about 12000 Hz, the vibration transmissibility Ea of the upper mass 60 alone reaches a primary peak T1a. In the second pattern T2, when the frequency f of the vibration E is about 9500 Hz, the vibration transmissibility Ea of the upper mass 60 alone reaches a primary peak T2a. In the third pattern S3, when the frequency f of the vibration E is about 10000 Hz, the vibration transmissibility Ea of the upper mass 60 alone reaches a primary peak T3a.

[0089] FIG. 14 shows that in any of the first pattern T1, second pattern T2, and third pattern T3, i.e., regardless of the shape of the upper mass 60 (spherical, cylindrical, or cylindrical + chamfered), the natural frequency fa of the upper mass 60 alone is 5000 Hz or more.

[0090] FIG. 14 shows that the natural frequency fa of the upper mass 60 alone is highest for the first pattern T1 (spherical), followed by the third pattern T3 (cylindrical + chamfered) and the second pattern T2 (cylindrical).

[0091] (Action and effect) In the dynamic characteristic measuring device 1 according to this embodiment, the upper mass 60 is suspended (more specifically, hung) from the upper plate 14 of the frame 10 by the upper vibration isolating rubber 70. Therefore, when vibration E is applied to the workpiece W by the vibrator 40, the combination of the upper mass 60 and the upper vibration isolating rubber 70 performs pendulum vibration P.

[0092] Since the combination of the upper mass 60 and the upper vibration isolating rubber 70 performs pendulum vibration P, the natural frequency fb of the combination of the upper mass 60 and the upper vibration isolating rubber 70 can be made small (for example, 10 Hz or less).

[0093] To prevent the combination of the upper mass 60 and the upper vibration-proof rubber 70 from resonating, the frequency f of the vibration E that the vibrator 40 applies to the workpiece W should be made higher than the natural frequency fb of the combination of the upper mass 60 and the upper vibration-proof rubber 70. The smaller the natural frequency fb of the combination of the upper mass 60 and the upper vibration-proof rubber 70, the more advantageous it is in suppressing resonance in the low-frequency range.

[0094] The dynamic characteristic measuring device 1 according to this embodiment can accurately measure the dynamic characteristic (dynamic spring constant) K of a workpiece in the low frequency range (particularly, about several Hz to 10 Hz).

[0095] 12, since the natural frequency fb of the combination of the upper mass 60 and the upper vibration-proof rubber 70 is 10 Hz or less, the frequency f of the vibration E that the vibrator 40 applies to the workpiece W may be set to 10 Hz or more. As long as the frequency f of the vibration E is 10 Hz or more, even in the low-frequency region, resonance of the combination of the upper mass 60 and the upper vibration-proof rubber 70 is suppressed, and the dynamic characteristic (dynamic spring constant) K of the workpiece W can be measured with high accuracy.

[0096] Using the upper vibration-proof rubber 70 in a tensioned state (hanging state) is more advantageous in reducing the natural frequency of the vibration mode in the vertical direction Z of the combination of the upper mass 60 and the upper vibration-proof rubber 70 than using the upper vibration-proof rubber 70 in a compressed state.

[0097] Since the upper mass 60 has a spherical shape, the natural frequency fa of the upper mass 60 alone can be made large. In order to prevent the upper mass 60 alone from resonating, the frequency f that the vibrator 40 applies to the workpiece W may be made smaller (for example, 5000 Hz or less) than the natural frequency fa of the upper mass 60 alone. The larger the natural frequency fa of the upper mass 60 alone, the more advantageous it is in suppressing resonance in the high frequency range.

[0098] The spherical upper mass 60 does not have a principal axis of inertia in any direction, and therefore can be manufactured with a high degree of design freedom.

[0099] 13 and 14, since the natural frequency fa of the upper mass 60 alone is 5000 Hz or more, the frequency f of the vibration E that the vibrator 40 applies to the workpiece W may be set to 5000 Hz or less. As long as the frequency f of the vibration E is 5000 Hz or less, resonance of the upper mass 60 alone is suppressed even in the high wave region, and the dynamic characteristic (dynamic spring constant) K of the workpiece W can be measured with high accuracy.

[0100] Since the load cell 80 is arranged on the upper side Z1, which is the side of the upper mass 60, relative to the workpiece W, and the vibration exciter 40 is arranged on the lower side Z2, which is the side of the lower mass 20, relative to the workpiece W, the layout of the load cell 80 and the vibration exciter 40 is simplified.

[0101] Since the vibration exciter 40 is supported by the lower vibration isolator 30 relative to the lower mass 20, the transmission of vibrations from the vibration exciter 40 to the lower mass 20 can be suppressed.

[0102] Since the upper mass 60 is disposed on the upper side Z1 relative to the workpiece W and the lower mass 20 is disposed on the lower side Z2 relative to the workpiece W, the layout of the upper mass 60 and the lower mass 20 is simplified.

[0103] Since the natural frequency fb of the combination of the upper mass 60 and the upper vibration-proof rubber 70 is 10 Hz or less, this is advantageous in suppressing resonance of the combination of the upper mass 60 and the upper vibration-proof rubber 70.

[0104] Since the natural frequency fa of the upper mass 60 alone is 5000 Hz or more, this is advantageous in suppressing resonance of the upper mass 60 alone.

[0105] The upper vibration-proof rubber 70 is connected to the upper plate 14 of the frame 10 and to a portion 60b above the center 60a of the upper mass 60 in the vertical direction Z. This makes it easier for the combination of the upper mass 60 and the upper vibration-proof rubber 70 to produce pendulum vibration P. This is advantageous in reducing the natural frequency fb of the combination of the upper mass 60 and the upper vibration-proof rubber 70.

[0106] If the upper anti-vibration rubber 70 is connected to a portion of the upper mass 60 below the center 60a in the vertical direction Z, it will be in a so-called floating state, requiring horizontal spring rigidity for stable support, and the natural frequency of the combination will approach the horizontal translation mode and the rotation mode around the horizontal axis. As a result, the vibration of the horizontal translation mode and the vibration of the rotation mode around the horizontal axis will be coupled with each other, and the combination of the upper mass 60 and the upper anti-vibration rubber 70 will resonate, making it easy for swinging vibration (bounce / roll resonance) to occur.

[0107] On the other hand, when the upper vibration-proof rubber 70 is connected to the part 60b above the center 60a in the vertical direction Z of the upper mass 60, it is in a suspended state, and the natural frequency of the combination can be separated from the translational mode in the horizontal direction and the rotational mode around the horizontal axis. Therefore, the vibration of the translational mode in the horizontal direction and the vibration of the rotational mode around the horizontal axis are unlikely to be coupled with each other, so that the combination of the upper mass 60 and the upper vibration-proof rubber 70 is unlikely to resonate, and pendulum vibration (where the vibration of the translational mode and the vibration of the rotational mode are independent of each other) is likely to occur instead of swinging vibration. Pendulum vibration is advantageous in suppressing the combination of the upper mass 60 and the upper vibration-proof rubber 70 from resonating in the low-frequency range.

[0108] Because frame 10 includes support posts 11, middle plate 13, and top plate 14, it is easy to support upper mass 60 and lower mass 20 relative to frame 10.

[0109] Since the dynamic characteristic measuring device 1 is equipped with not only the load cell 80 but also the displacement sensor 90, the dynamic spring constant K of the workpiece W, which is a representative index representing the dynamic characteristic K of the workpiece W, can be measured with high accuracy in the low frequency range.

[0110] According to the dynamic characteristic measuring device 1 of this embodiment, the dynamic characteristic (dynamic spring constant) K of the workpiece W can be measured with high accuracy by suppressing resonance in a wide frequency range of 10 Hz to 5000 Hz.

[0111] The dynamic characteristics measuring device 1 according to this embodiment is effective in achieving Goal 9 of the SDGs, "Build resilient infrastructure, promote inclusive and sustainable industrialization and innovation."

[0112] (Other embodiments) Although the present disclosure has been described above with reference to the preferred embodiments, such description is not limiting, and it goes without saying that various modifications, substitutions, or combinations are possible.

[0113] The vibrator 40 may apply vibrations to the workpiece W in the horizontal direction instead of the vertical direction Z. The load cell 80 may detect the horizontal load applied to the workpiece W by the vibrator 40. The displacement sensor 90 may detect the horizontal displacement of the workpiece W caused by the vibrator 40. The dynamic characteristic measuring device 1 may measure the horizontal dynamic characteristic (dynamic spring constant) K of the workpiece W.

[0114] An object may be interposed between the upper vibration isolation rubber 70 and the frame 10 or between the upper vibration isolation rubber 70 and the upper mass 60.

[0115] Both the upper mass 60 and the lower mass 20 may be suspended from the frame 10 by the upper vibration isolation rubber 70 and the lower vibration isolation rubber 30. The upper vibration isolation rubber 70 and the lower vibration isolation rubber 30 may be of a type that suspends the upper mass 60 and the lower mass 20 in a compressed state, for example, like a hanging-type vibration isolation hanger.

[0116] The dynamic characteristic measuring device 1 may include a third elastic body (e.g., a vibration-isolating rubber for the vibration exciter) that supports the vibration exciter 40 with respect to the lower mass (second mass body) 20. With this configuration, it is possible to suppress the vibration of the vibration exciter 40 from being transmitted to the lower mass (second mass body) 20.

[0117] The frame 10 may be placed on the foundation G via an air spring as an elastic body for the frame.

[0118] The lower mass 20 may be the first mass, and the upper mass 60 may be the second mass. Similarly, the lower vibration-proof rubber 30 may be the first elastic body, and the upper vibration-proof rubber 70 may be the second elastic body. In this case, the lower mass 20 as the first mass is suspended from the frame 10 by the lower vibration-proof rubber 30 as the first elastic body. In this case, the upper mass 60 as the second mass does not have to be suspended from the frame 10 by the upper vibration-proof rubber 70 as the second elastic body.

[0119] The first mass is not limited to a spherical shape. The first mass may be cylindrical or may have a cylindrical shape with chamfered edges, as shown in FIG. 14. Furthermore, the first mass may be polygonal prism such as a rectangular parallelepiped, or a polyhedron. For example, a hook may be attached to the first mass, or the first mass may be processed.

[0120] The first elastic body and the second elastic body are not limited to anti-vibration rubber, and may be, for example, a coil spring, etc. The first elastic body and the second elastic body may have any configuration as long as they have elasticity.

[0121] The first rigid member and the second rigid member are not limited to being plate-shaped, and may be, for example, rod-shaped or block-shaped, or may be formed from the brackets of the vibration-proof hanger described above.

[0122] The first mass may be disposed above the first rigid member of the frame. For example, the first elastic body is configured with a rod-shaped anti-vibration hanger. The first elastic body (anti-vibration hanger) extends upward from the first rigid member. The first mass may be supported by being suspended by the first elastic body (anti-vibration hanger) above the first rigid member. Furthermore, the frame may not include the first and second rigid members and the support columns.

[0123] The dynamic characteristic K is not limited to the dynamic spring constant, but may include various other indices that represent the dynamic properties of the workpiece W. The workpiece W is not limited to anti-vibration rubber, but may be, for example, a coil spring or the like.

[0124] The displacement sensor 90 may not be provided. The controller 100 may measure the dynamic characteristic K of the workpiece W based on at least the load F detected by the load cell 80. [Industrial Applicability]

[0125] Since the present disclosure can be applied to dynamic characteristic measuring devices, it is extremely useful and has high industrial applicability. [Explanation of symbols]

[0126] Z vertical direction Z1 upper side Z2 lower side O axis center G Basics E Vibration F load δ Displacement K Dynamic spring constant (dynamic characteristics) f frequency fa Natural frequency fb Natural frequency Ea Vibration transmissibility Eb Vibration transmissibility Double work P pendulum oscillation 1. Dynamic characteristics measurement device 10 Frames 13 Middle plate (second rigid member) 14 Upper plate (first rigid member) 20 Lower mass (second mass) 30 Lower vibration isolating rubber (second elastic body) 40 Shaker 60 Upper mass (first mass) 60a Center 60b part 61 Work receiver 70 Upper vibration isolating rubber (first elastic body) 80 Load cell (load sensor) 90 Displacement Sensor 100 Controller

Claims

1. A first mass body that is disposed on one of the upper and lower sides in the vertical direction with respect to the workpiece and that holds the workpiece; a second mass body that is disposed on the other of the upper and lower sides in the vertical direction with respect to the workpiece and that holds the workpiece; A frame placed on a foundation; a first elastic body that supports the first mass body relative to the frame; a second elastic body that supports the second mass body relative to the frame; A vibrator that applies vibration to the workpiece; a load sensor that detects a load applied to the workpiece by the vibration exciter; a controller for measuring a dynamic characteristic of the workpiece based on the load detected by the load sensor; A dynamic characteristic measuring device, wherein the first mass is suspended relative to the frame by the first elastic body.

2. The dynamic characteristic measurement apparatus according to claim 1 , wherein the first mass is spherical.

3. the load sensor is disposed on a side of the first mass with respect to the workpiece, The vibrator is disposed on the second mass side with respect to the workpiece.

3. The dynamic characteristic measuring device according to claim 1 or 2.

4. The first mass is disposed above the workpiece, The dynamic characteristic measuring device according to claim 1 , wherein the second mass is disposed below the workpiece.

5. 3. The dynamic characteristic measuring device according to claim 1, wherein a natural frequency of the combination of the first mass body and the first elastic body is 10 Hz or less.

6. 3. The dynamic characteristic measuring device according to claim 1, wherein the first mass has a natural frequency of 5000 Hz or more as a single unit.

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