Vibration testing system

Abstract

To provide a vibration testing system capable of aligning vibration by each vibration generation device.SOLUTION: Weight ratio acquisition means 102 of an entire control device 100 acquires a DC current when the DC drive current is applied to a drive coil 20a by a drive current application circuit 30a so as to hold a vibration table 24a in a reference position. The ratio of a DC current of each vibration generation device is acquired as a weight ratio. Control means 104 receives a ratio of the weight of a movable section from the weight ratio acquisition means 102, controls excitation current application circuits 90a, 90b on the basis of it, and allows the impedance of the drive coils 20a, 20b to be identical. The control means 104 of the entire control device 100 adjusts the gain of a drive current used for a vibration test according to the adjusted excitation current by a drive current application circuit 30, and allows vibration at the same excitation level (acceleration or speed or displacement) to be given to the vibration tables 24a, 24b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vibration test system for performing a vibration test on a specimen. [Background technology]

[0002] Generally, a vibration generator is composed of a vibrator and a power amplifier that supplies power to operate the vibrator.

[0003] Fig. 16A shows a conventional vibrator used for vibration testing of products, etc. Magnetic path members 12 and 13 are provided. Excitation coils 14 and 16 are housed in magnetic path member 12. Excitation coils 14 and 16 form upper and lower magnetic circuits, as shown in Fig. 16B. This generates a magnetic flux in gap 18.

[0004] A drive coil 20 is provided in this gap 18. Therefore, when a drive current for generating a desired vibration is passed through the drive coil 20, the drive coil 20 can be moved up and down. A vibration table 24 is provided above the drive coil 20. Therefore, the vibration table 24, on which a sample, which is a product, is placed, can be vibrated up and down. The vibration table 24 is supported by an upper support mechanism and a lower support mechanism (not shown).

[0005] When using this vibrator, first, a sample is fixed to the vibration table 24. In this state, air is fed into the air suspension 22 provided below the vibration table 24, and the vibration table 24 is moved upward. When the vibration table 24 reaches the midpoint of the maximum vertical amplitude, air supply to the air suspension 22 is stopped and a valve (not shown) is closed. In this way, the initial setup is completed.

[0006] After the vibration table 24 is raised to the center point in this manner, the amplifier then applies drive power to the drive coil 20 to generate the desired vibration, vibrating the vibration table 24 and the sample.

[0007] As the test specimen becomes larger, a vibration generator with a correspondingly large vibration table is used.

[0008] For larger or longer test specimens, vibration tests are also carried out by fixing the test specimens to the vibration tables of a plurality of vibration generators (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 10-124105 [Patent Document 2] Patent Publication No. 2010-54397 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in a multi-point vibration test in which the test specimen is fixed at multiple locations as described above, it is necessary to synchronize the vibrations generated by each vibration generator. If the vibrations are not synchronized, the desired vibrations will not be applied to the test specimen, which will affect the reliability of the vibration test. Furthermore, if the vibrations generated by each vibration generator differ significantly, the test specimen may be damaged.

[0011] Therefore, a test vibration is performed to obtain the frequency transfer characteristics of the vibrations generated by each vibration generator, and then the vibrations are controlled to be uniform based on the frequency transfer characteristics. However, performing test vibrations in this manner is cumbersome.

[0012] Furthermore, when performing test vibration, if the vibration level at each fixed point is low, the load on the test specimen due to the test vibration can be avoided, but it is difficult to obtain effective transmission characteristics. Conversely, if an attempt is made to obtain effective transmission characteristics by increasing the test vibration level, a considerable load will be applied to the test specimen before the actual test.

[0013] SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a vibration testing system that can align the vibrations generated by the vibration generators without the need for test vibrations. [Means for solving the problem]

[0014] The following are some independent features of the present invention. These features are independent of each other, and are not necessarily combined, but can be combined in any desired manner.

[0015] (1)(2)(3) The vibration test system according to the present invention is a vibration test system for performing a vibration test on a test piece fixed to a vibration table of a plurality of vibration generators, the vibration test system comprising a plurality of vibration generators and an overall control device, The vibration generating device includes a magnetic flux generating source that generates magnetic flux by an excitation current, a drive current application circuit that acquires a drive signal, amplifies it at a predetermined amplification factor, and outputs a drive current, a drive coil that is disposed in the magnetic flux generated by the magnetic flux generating source and is driven by the drive current, and a vibration table that is driven by the drive force of the drive coil and that fixes a specimen, The overall control device includes a weight ratio acquisition means for acquiring the weight ratio of the moving parts in each vibration generating device, including the vibration table on which the test specimen is fixed, and a control means for controlling the amplification factor of the excitation current and the drive current application circuit of each vibration generating device based on the weight ratio in each vibration generating device so that the vibrations generated by each vibration generating device approach the same.

[0016] Therefore, in a vibration test in which a test specimen is fixed to a plurality of vibration generators, the vibrations generated by the vibration generators can be made uniform.

[0017] (4) The vibration testing system according to the present invention is characterized in that the weight ratio acquisition means applies a direct current as a drive current to the drive coil in an initial state to maintain the vibration table at a reference position, and calculates the weight ratio based on the value of the direct current.

[0018] Therefore, since the weight ratio is obtained based on the DC current for maintaining the vibration table at the reference position, there is no need to perform a separate process for obtaining the weight ratio.

[0019] (5) The vibration testing system according to the present invention is characterized in that the weight ratio acquisition means acquires the weight ratio by calculating it based on the shape and weight of the test specimen, or by acquiring it from an external input.

[0020] Therefore, the weight ratio can be calculated based on the shape or the like, or can be obtained by external input.

[0021] (6) The vibration testing system according to the present invention is characterized in that the vibration generator further comprises a short-circuit switch that short-circuits both ends of the drive coil when an abnormal state is detected.

[0022] Therefore, it is possible to prevent the vibration table from suddenly falling due to counter electromotive force when an abnormality occurs.

[0023] (7) The vibration testing method according to the present invention is a vibration testing method in which a test specimen is fixed to the vibration tables of a plurality of vibration generating devices and a vibration test is performed, the weight ratio of the moving parts of each vibration generating device including the vibration table on which the test specimen is fixed is obtained, and the amplification factor of the excitation current and the drive current application circuit of each vibration generating device is controlled based on the weight ratio of each vibration generating device so that the vibrations generated by each vibration generating device become approximately the same.

[0024] Therefore, in a vibration test in which a test specimen is fixed to a plurality of vibration generators, the vibrations generated by the vibration generators can be made uniform.

[0025] In the embodiment, step S105 corresponds to the "weight ratio acquisition means."

[0026] In the embodiment, steps S107 and S109 correspond to the "control means."

[0027] The concept of "device" includes not only what is constituted by one computer, but also what is constituted by multiple computers connected via a network, etc. Therefore, when the means of the present invention (or even a part of the means) is distributed among multiple computers, these multiple computers correspond to the device.

[0028] The term "program" is a concept that includes not only programs that can be executed directly by a CPU, but also programs in source format, compressed programs, encrypted programs, and programs that work in conjunction with an operating system to perform their functions. [Brief explanation of the drawings]

[0029] [Figure 1] 1 shows a functional configuration of a vibration testing system according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing the structure of a vibration exciter 1. FIG. [Figure 3] 3 is a diagram showing the structure of a vibration table 24. FIG. [Figure 4] 3 is a diagram showing a magnetic path member of the vibration exciter 1. FIG. [Figure 5a] FIG. 10 is a diagram showing a state in which a vibration table is incorporated into the magnetic path member. [Figure 5b] FIG. 10 is a diagram showing a state in which a vibration table is incorporated into the magnetic path member. [Figure 6] This shows the system configuration of a vibration testing system. [Figure 7] This shows the configuration of the drive current application circuit 30. [Figure 8] The configuration of the excitation current application circuit 90 is shown. [Figure 9] 1 shows the hardware configuration of the overall control device 100. [Figure 10] 10 is a flowchart of an overall control program 160. [Figure 11] 10 is an example of a correspondence table. [Figure 12] 10 is data showing the operation results of the vibration test system. [Figure 13]10 is a diagram for explaining the function when the drive coil 20 is short-circuited by the switch 72. FIG. [Figure 14] FIG. 10 is a diagram showing a mechanism for preventing a fall by an air cylinder 80. [Figure 15] FIG. 10 is a diagram showing a mechanism for preventing a fall by an air cylinder 80. [Figure 16] FIG. 1 is a diagram showing a conventional vibration generating device. DETAILED DESCRIPTION OF THE INVENTION

[0030] 1.Functional configuration FIG. 1 shows the functional configuration of a vibration testing system according to one embodiment of the present invention. This embodiment uses two vibration exciters 1a and 1b with the same characteristics. Vibrator 1a is provided with excitation coils 14a and 16a, which generate magnetic flux by an excitation current from an excitation current application circuit 90a. Drive coil 20a is provided in this magnetic flux and is driven by a drive current from a drive current application circuit 30a to vibrate a vibration table 24a. Vibrator 1a, together with the drive current application circuit 30a and excitation current application circuit 90a, constitutes a vibration generating device. Vibrator 1b has a similar configuration.

[0031] A specimen 3 is fixed to a vibration table 24a of the vibration exciter 1a and a vibration table 24b of the vibration exciter 1b. Since the weight distribution of the specimen 3 is not uniform, the weight applied to the vibration table 24a and the weight applied to the vibration table 24b are not the same.

[0032] An overall control device 100 is connected to each vibration generator (vibrator 1a, vibrator 1b). A weight ratio acquisition means 102 of the overall control device 100 acquires the DC current when a DC drive current is applied to the drive coil 20a by the drive current application circuit 30a in order to hold the vibration table 24a at a reference position. Similarly, a weight value acquisition means 102 acquires the DC current when a DC drive current is applied to the drive coil 20b by the drive current application circuit 30b in order to hold the vibration table 24b at a reference position. The ratio of the DC currents of the vibration generators is acquired as a weight ratio.

[0033] The control means 104 receives the ratio of the moving part weights of the vibrators 1a and 1b under load (the total weight of the vibration table when the specimen is fixed to the vibration table and the vibration table, drive coil, etc.) from the weight ratio acquisition means 102. Based on this, the control means 104 controls the excitation current application circuits 90a and 90b so that the impedances of the drive coils 20a and 20b are the same.

[0034] The impedance of the drive coils 20a, 20b is a function of the weight of the moving part, the excitation current, etc. Therefore, if the weight ratio is known, the excitation current can be controlled based on a function formula to make the impedance the same and apply vibrations of the same excitation level (acceleration, velocity, or displacement) to the vibration tables 24a, 24b.

[0035] However, the vibration level is a function of both the excitation current and the drive current, so the control means 104 of the overall control device 100 adjusts the gain of the drive current used for the vibration test in accordance with the weight ratio so that the same level of vibration is applied to the vibration tables 24a and 24b.

[0036] As described above, "the vibration table is held in a reference position by a DC drive current, the weight ratios applied to the multiple vibrators are measured, and the excitation current and drive current are controlled according to these weight ratios," which has the effect of "synchronizing the vibrations of the multiple vibrators."

[0037] 2. Structure of the vibration generator FIG. 2 shows a cross-sectional view of the structure of the vibration exciters 1a and 1b. In this embodiment, the vibration exciters 1a and 1b have the same structure and characteristics. Therefore, hereinafter, the vibration exciters 1a and 1b will not be distinguished from each other and will be described as vibration exciter 1. For this reason, for example, magnetic path members 14 and 16 shown in the drawings are magnetic path members 14a and 16a in the vibration exciter 1a, and magnetic path members 14b and 16b in the vibration exciter 1b. The same applies to other components.

[0038] The vibrator 1 is provided with magnetic path members 12 and 13. The magnetic path member 12 houses exciting coils 14 and 16. The exciting coils 14 and 16 generate magnetic flux in a gap 18.

[0039] A drive coil 20 is provided in this gap 18. Therefore, when a drive current for generating a desired vibration is passed through the drive coil 20, the drive coil 20 can be moved up and down. A vibration table 24 is provided above the drive coil 20. Therefore, the vibration table 24, on which a sample, which is a product, is placed, can be vibrated up and down. The vibration table 24 is provided with a shaft 25 for stabilizing the up and down movement. The vibration table 24 is also supported by an upper support mechanism 17 and a lower support mechanism 19.

[0040] In this embodiment, the structure does not include the air suspension 22. Therefore, there is no need for a cavity to provide the air suspension 22, and the cavity can be filled with a magnetic material. In other words, magnetic efficiency is good.

[0041] 3 shows the configuration of the vibration table 24. The vibration table 24 has a housing 28 that is generally cylindrical overall, and has a table 26 on top for fixing a specimen.

[0042] A support plate 27 extending radially from the shaft 25 is provided below the table 26. The support plate 27 is fixed to the shaft 25 and a housing 28. An opening 29 is provided in the housing 28, leaving an area for fixing the support plate 27.

[0043] Furthermore, the lower part remains cylindrical, with a drive coil 20 wound around the outer periphery.

[0044] 4 shows the configuration of the magnetic bodies 12 and 13. The magnetic body 12 is formed in a cylindrical shape with a bottom, and the magnetic body 13 is provided in its central portion. The magnetic body 13 is composed of a predetermined number (eight in this embodiment) of triangular prisms, and is arranged with a predetermined gap 11 between them. A gap 18 is provided between the outer magnetic body 12 and the inner magnetic body 13. The cylindrical portion of the vibration table 24 in FIG. 3 is inserted into this gap 18.

[0045] 5a shows the state in which vibration table 24 is inserted into gap 18 between magnetic bodies 12 and 13. The cylindrical portion of housing 28 of vibration table 24 is inserted into gap 18, and support plate 27 of vibration table 24 is inserted into interval 11. After insertion, auxiliary magnetic body 15 is inserted between magnetic body 12 and magnetic body 13.

[0046] A metal protrusion 42 is provided on the side of the table 26. An eddy current displacement sensor 40 is provided facing this protrusion 42. The protrusion 42 is formed so that the height of the part facing the displacement sensor 40 changes in accordance with the vertical movement of the vibration table 24. This allows the displacement sensor 40 to detect the height position of the vibration table 24.

[0047] 3. System configuration and hardware configuration 6 shows a system configuration of the drive current application circuits 30a, 30b, the excitation current application circuits 90a, 90b, and the overall control device 100. The overall control device 100 controls the drive current application circuits 30a, 30b and the excitation current application circuits 90a, 90b.

[0048] 7 shows the configuration of the drive current application circuit 30. Since the drive current application circuits 30a and 30b have the same configuration, they will be described as the drive current application circuit 30. The operation of the drive current application circuit 30 can be controlled from the overall control device 100.

[0049] The center position indicator 82 has an operation unit for determining the center position (initial position when no excitation signal is present) of the vibration table 24. When the operator operates this operation unit, the voltage output from the center position indicator 82 changes, and the vibration table 24 is maintained at a position corresponding to this voltage by a feedback loop formed by the difference calculator 84, adder 94, power module 35, drive coil 20, and displacement sensor 40.

[0050] The excitation signal input circuit 88 receives an excitation signal and applies it to the power module 35 , which then applies a drive current to the drive coil 20 .

[0051] In this embodiment, a switch 72 is provided to short-circuit both ends of the drive coil 20. The function of the switch 72 will be described later.

[0052] 8 shows the configuration of the excitation current application circuit 90. Since the excitation current application circuits 90a and 90b have the same configuration, they will be described as the excitation current application circuit 90. The operation of the excitation current application circuit 90 can be controlled from the overall control device 100.

[0053] The output of the excitation current application circuit 90 is applied as an excitation current to the excitation coils 14, 16. The magnitude of this excitation current can be set by an excitation current setting device 91.

[0054] 9 shows the hardware configuration of the overall control device 100. Connected to a CPU 150 are a memory 152, an SSD 154, and an I / O port 156. Via the I / O port 156, the CPU 150 can control the drive current application circuit 30a and excitation current application circuit 90a of the vibration exciter 1a, and can also control the drive current application circuit 30b and excitation current application circuit 90b of the vibration exciter 1b.

[0055] The SSD 154 stores an operating system 158 and an overall control program 160. The overall control program 160 cooperates with the operating system 158 to perform its functions.

[0056] 4. Control Processing 10 shows a flowchart of the overall control program 160. The CPU 150 operates the excitation current application circuits 90a and 90b. As a result, the rated excitation current Ifa is applied to the excitation coils 14a and 16a of the vibration exciter 1a, and the rated excitation current Ifb is applied to the excitation coils 14b and 16b of the vibration exciter 1b. Next, the CPU 150 turns off the switches 72a and 72b (step S102). Furthermore, the CPU 150 sets the adders 94a and 94b to a state where no excitation signal is applied, so that a DC drive signal is applied to the drive coil 20 (step S103).

[0057] The operator can determine the center position of the vibration table 24 (the initial position when no excitation signal is present) by operating the center position indicator 82 in Figure 7. A difference calculator 84, which is composed of an operational amplifier and other components, calculates the difference between the output of the displacement sensor 40 (i.e., the position of the vibration table 24) and the center position determined by the center position indicator 82. This difference is given to an adder 94, and passed through a power module 35 to change the drive current and move the vibration table 24 up and down. The output of the displacement sensor 40 changes depending on the vertical position of the vibration table 24, and the difference from the difference calculator 84 also changes.

[0058] Therefore, the vibration table 24 is held at the center position (see FIG. 5b) set by the center position indicator 82 by a feedback circuit including the displacement sensor 40, the difference calculator 84, and the drive coil 20.

[0059] Next, the CPU 150 acquires the drive current values ​​i a and ib when the vibration tables 24 a and 24 b are held at the reference position (step S104). For example, these values ​​can be acquired from an ammeter attached to the output of the power module 35. The drive current values ​​i a and ib vary depending on the weights applied to the vibration tables 24 a and 24 b. Here, the weights of the specimen 3 differ between the vibration tables 24 a and 24 b, and therefore the drive current values ​​i a and ib also differ.

[0060] The CPU 150 calculates the weight ratio applied to the vibration tables 24a and 24b based on the drive current value (direct current for maintaining the vibration tables 24a and 24b at the reference position) (step S105). The calculation method is as follows.

[0061] The weight of the vibration table 24 is m [kg], the force coefficient of the vibration exciter is Bl [N / A], the driving current I [A] (peak value) is applied, and the acceleration is a [m / s 2 ], if the excitation force of the vibrator at that time is F[N], then F=m*a=Bl*I (1) where F, a, and I are the rated values ​​of the vibrator and are known values.

[0062] When a specimen of M [kg] is fixed to the vibration table 24 and held at the reference position by passing a DC current Idc, the gravitational acceleration is 9.8 [m / s 2 ], then, as above, Fdc=(m+M)*9.8=Bl*Idc (2) It can be expressed as:

[0063] From equations (1) and (2), the weight of the specimen, M, is M=(Idc / I*aa / 9.8-1)*m It can be calculated as:

[0064] Here, the weight of the moving part of vibrator 1a when loaded is defined as md+ma, where md is the weight of the drive coil and ma is the mounted mass (the weight on the vibration table when the test specimen is fixed to the vibration table and the weight of the vibration table). The weight of the moving part of vibrator 1b when loaded is defined as md+mb, where md is the weight of the drive coil and mb is the mounted mass (the weight on the vibration table when the test specimen is fixed to the vibration table and the weight of the vibration table).

[0065] The impedances Za and Zb of the drive coils 20a and 20b of the vibrators 1a and 1b are expressed by the following equations: If the resistance of the drive coil is R, the inductance is L, and the force coefficient is Bl (B is the excitation magnetic flux density in the drive coil section, and l is the drive coil length), then: Za=R+jωL+(Bl)2 / jω(md+ma) Zb=R+jωL+(Bl) 2 / jω(md+mb) As described above, the moving part weights md+ma and md+mb under load are different in the vibration exciters 1a and 1b. Therefore, even if the same drive signal is applied to the vibration exciters 1a and 1b, the vibrations will not be the same. To apply the same vibration, the impedances Za and Zb of the drive coils 20a and 20b must be the same. Therefore, in this embodiment, the impedances Za and Zb are made equal by adjusting the force coefficient Bl.

[0066] Here, if we consider the case where md+ma is greater than md+mb, the Bl of the vibrator 1a is determined by the rated excitation current, so the excitation current cannot be made greater than the rated excitation current. Therefore, adjustment is made by reducing the Bl of the vibrator 1b. Here, if the reduced Bl is called Bl', then Bl' = Bl×((md+mb) / (md+ma)) 1 / 2 It is sufficient to adjust it so that

[0067] The relationship between the excitation current If and Bl is given by the approximate formula obtained from the actual measured values: Bl = c5 × If 5 + c4×If 4 + c3×If 2 + c2×If (3) Therefore, based on this formula, If' is calculated so as to obtain Bl' (step S106).

[0068] Bl' may also be calculated as follows.

[0069] If the excitation forces are Fa and Fb, the force coefficient is Bl, the acceleration is a, the mounted weights are ma and mb, the drive coil weight is md, and the center holding current is Ia and Ib, respectively, then Fa = (ma+md)×9.8 = Bl×Ia Fb = (mb+md)×9.8 = Bl×Ib holds, so the ratios are expressed as Fa / Fb = (ma+md) / (mb+md) = Ia / Ib The weight ratio can be replaced with the DC current ratio when the position is maintained.

[0070] Bl' is Bl'=Bl×((md+mb) / (md+ma)) 1 / 2 =Bl×((Idcb) / (Idca)) 1 / 2 ···(4) It can be calculated as:

[0071] If' corresponding to Bl' may be calculated using a correspondence table between force coefficient ratios and excitation currents, calculated in advance for each model of vibrator, where Bl' / Bl is the force coefficient ratio. An example of the correspondence table is shown in Figure 11.

[0072] The CPU 150 controls the excitation current application circuit 90b of the vibration exciter 1b, and controls the excitation current setter 91 so that the excitation current If'b calculated above is obtained (step S107). Note that the excitation current application circuit 90a of the vibration exciter 1a is controlled so that the rated (100%) excitation current Ifa is output.

[0073] The excitation forces Fa and Fb of the vibrators 1a and 1b are expressed by the following equations, where ia and ib are driving currents and A is acceleration.

[0074] Fa = A×(md+ma) = Bl×ia Fb = A×(md+mb) = Bl'×ib Taking the ratio of the equations for a and b in the center and right-hand sides, we get (md+mb) / (md+ma)=Bl' / Bl×ib / ia To calculate ib / ia, ib / ia=(md+mb) / (md+ma)×Bl' / Bl From the above formula (4), Bl'=((md+mb) / (md+ma)) 1 / 2 ×Bl Substituting and rearranging, ib / ia=((md+mb) / (md+ma)) 1 / 2 If ia is a current with a gain of 100%, then ib should be set to the level on the right-hand side.

[0075] Therefore, in order for the right-hand side equality to hold, ib must be adjusted in accordance with the adjustment of Bl to Bl'.

[0076] If the gain of the vibration signal input circuit 88a of the drive current application circuit 30a of the vibration exciter 1a is 100%, the gain Gain_b of the vibration signal input circuit 88b of the drive current application circuit 30b of the vibration exciter 1b can be calculated as follows.

[0077] Gain_b = (Idcb / Idca) 1 / 2 ×100% The CPU 150 calculates Gain_b as described above (step S108), and provides the calculated Gain_b to the vibration signal input circuit 88b to control the gain (step S109).

[0078] The CPU 150 then performs the vibration test by receiving the vibration signal through the vibration signal input circuit 88. In this way, it is possible to apply uniform vibration to specimens 3 even if they do not have the same weight balance.

[0079] Figure 12A shows the frequency characteristics of acceleration when vibration is applied with different weights. It can be seen that the frequency characteristics change significantly depending on the weight. Figure 12B shows the frequency characteristics when the gain of the excitation current and drive current is adjusted according to the weight as described above. It can be seen that the characteristics generally match, except in the high frequency range.

[0080] If control stops when a system abnormality occurs or when the vibration test is completed, the vibration table 24 may fall, causing unnecessary vibrations to the test piece.

[0081] Therefore, in this embodiment, a switch 72 is provided in each vibrator 1. The short circuit indication signal output circuit 92 outputs a short circuit indication signal when it receives a stop signal from the vibration control circuit, when a drive current exceeding a limit value is output, when the vibration table 24 vibrates beyond a predetermined limit, when it receives a signal indicating an abnormal state from the vibrator in an abnormal situation such as when a power supply malfunctions, or when it receives an emergency stop signal from a thermostatic bath or the like due to an operator's operation.

[0082] When a short circuit instruction signal is given to switch 72, switch 72 turns on. If there is a static magnetic field from excitation coils 14, 16, this generates a current that generates a driving force in the direction that prevents the fall of drive coil 20, which falls together with vibration table 24, as shown in Figure 13. This brakes the fall of vibration table 24, allowing it to be lowered gently.

[0083] In the event of a power outage, power is also cut off to the excitation coils 14 and 16, which generate the static magnetic field. However, due to the nature of coils, the magnetic flux of the excitation coils 14 and 16 does not change suddenly even when the power supply is cut off, and the static magnetic field remains for approximately the time required for the brake to be applied. Therefore, even if the excitation current is not supplied due to a power outage, the brake can be applied in the same way.

[0084] Furthermore, it is preferable that the switch 72 be configured to turn on if the drive current application circuit 30 loses power and stops. For example, a switch whose reference position is off and which is off only while a signal is being applied from the drive current application circuit 30 is used. In this case, the switch 72 is in the reference on position when the drive current application circuit 30 stops.

[0085] 5. Variations (Other) (1) In the above embodiment, a vibration test is performed by supporting the specimen 3 using two vibrators. However, the present invention can be applied to a case where three or more vibrators are used. In this case, the vibrator with the largest moving part weight is used as a reference, and the excitation current and drive current of the other vibrators are adjusted accordingly.

[0086] (2) In the above embodiment, the excitation current and drive current gain of one of the vibrators are changed for adjustment. However, the excitation current and drive current gain of both vibrators may be changed.

[0087] (3) In the above embodiment, the control portion of the drive current application circuit 30 is configured by hardware logic. However, this may also be realized by a control program using a CPU.

[0088] (4) In the above embodiment, the ratio of the DC current is used as the weight ratio. However, the weight ratio may be calculated based on the DC current, and this weight ratio may be used as the weight ratio. In other words, the direct weight ratio may be used, or an index that indirectly indicates the weight ratio may be used.

[0089] (5) In the above embodiment, the CPU 150 calculates the weight ratio based on the DC current value for holding the vibration table 24 at the reference position. However, the worker may calculate the weight ratio based on the DC current value and input it to the CPU 150 via a keyboard or the like.

[0090] Alternatively, a weight scale may be set in advance at the position of the vibration table 24 of each vibrator 1, and the test specimen 3 may be placed on the scale to measure the weight and calculate the weight ratio. Alternatively, the weight applied to the vibration table 24 of each vibrator 1 may be calculated based on the shape of the test specimen 3, and the weight ratio may be calculated.

[0091] (6) In the above embodiment, the switch 72, which is a short-circuiting switch, shorts both ends of the drive coil 20, generating a counter electromotive force during a fall, thereby acting as a brake. However, instead of or in addition to this, an air cylinder 82 may be provided as a fall prevention mechanism, as shown in FIG. 14. When the drive current application circuit 30 receives a stop signal, it extends the rod 84 of the air cylinder 82 to prevent the vibration table 24 from falling. In FIG. 14, the rod 84 indicated by the dashed line is in the extended state. It is preferable to provide multiple air cylinders 82.

[0092] The rod 84 of the air cylinder 82 is normally retracted so as not to interfere with the vibration. When a stop signal is received, the CPU 50 extends the rod 84 of the air cylinder 82. This prevents the vibration table 24 from suddenly falling.

[0093] Furthermore, as shown in FIG. 15, when an auxiliary table 27 is provided on the vibration table 24, an air cylinder 82 may be provided below the auxiliary table 27 as a fall prevention mechanism.

[0094] (7) In the above embodiment, the center point of the vertical movement range of the vibration table is set as the reference position. However, a position below (above) the center point may also be set as the reference position.

[0095] (8) In the above embodiment, the eddy current displacement sensor 40 is used to detect the position of the vibration table 24. However, other displacement sensors such as a laser displacement sensor may also be used.

[0096] (9) In the above embodiment, no air suspension is provided. However, it is also possible to provide an air suspension as in the past. Under normal circumstances, the air suspension is opened and not functioning, but in an emergency (when a stop signal is received), the air suspension can be activated (by closing the release valve) to send in air and be used to prevent falls. In this case, the air suspension is only used to prevent falls, so precise adjustment and control are not required.

[0097] (10) In the above embodiment, the vibration table is held at the reference position by applying a DC drive current, and the weight ratio is calculated based on the drive current. However, it is also possible to use a conventional vibration generator as shown in Fig. 16 to calculate the weight ratio by another method, and to perform similar control of the gains of the excitation current and drive current.

[0098] (11) In the above embodiment, the overall control device 100 calculates the gains of the excitation current and the drive current, and controls the excitation current application circuit 90 and the drive current application circuit 30 of the vibrator 1. However, some or all of these operations may be performed manually by an operator.

[0099] For example, the gains of the excitation current and drive current calculated by the overall control device 100 may be displayed (printed) so that an operator can manually adjust the gains of the excitation current and drive current of the vibrator 1 while looking at this.

[0100] Alternatively, an operator may calculate the gains of the excitation current and the drive current based on the weight ratio, and manually adjust the gains of the excitation current and the drive current of the vibrator 1.

[0101] (12) In the above embodiment, the operator sets the center position by operating the center position indicator 82 of the vibration exciter 1. However, the vibration exciter 1 may set the stop position by receiving an instruction value from an external device such as the overall control device 100.

[0102] (13) In the above embodiment, the characteristics are generally matched except in the high frequency range. However, if it is desired to match the characteristics in the high frequency range as well, the following can be done. A controller is provided for each vibrator 1, and a vibration signal is applied to the drive current application circuit 30 of each vibrator 1 in synchronization. The frequency transfer characteristics are calculated based on the output of the acceleration sensor provided on the test specimen and the vibration signal, and control is performed so that the frequency characteristics of the target vibration signal and the frequency characteristics of the acceleration sensor output match. This makes it possible to match the characteristics in the high frequency range as well.

[0103] In this case, the controller can be used to control the actual excitation (test using excitation signals) without trial excitation. Because the characteristics match in the low frequency range, there is no difference in vibration in the low frequency range that could destroy the test piece.

[0104] (14) The above-described embodiments and their modifications can be implemented in combination with each other.

Claims

1. A vibration test system for performing a vibration test on a test piece fixed to a vibration table of a plurality of vibration generators, the vibration test system comprising: a plurality of vibration generators; and an overall control device; The vibration generating device is a magnetic flux generating source that generates magnetic flux by an excitation current; a drive current application circuit that receives a drive signal, amplifies the signal at a predetermined amplification factor, and outputs a drive current; a drive coil disposed in the magnetic flux generated by the magnetic flux generating source and driven by the drive current; a vibration table driven by the driving force of the drive coil and for fixing a specimen; Equipped with The overall control device includes: a weight ratio acquisition means for acquiring a weight ratio of a moving part including a vibration table to which a test piece is fixed in each vibration generator; a control means for controlling the excitation current of each vibration generator and the amplification factor of the drive current application circuit based on the weight ratio of each vibration generator so that the vibrations generated by each vibration generator are approximately the same; Vibration test system equipped with

2. 1. An overall control device for use in a vibration test system for performing vibration tests on a test specimen fixed to a vibration table of a plurality of vibration generators, comprising: a weight ratio acquisition means for acquiring a weight ratio of a moving part including a vibration table to which a test piece is fixed in each vibration generator; a control means for controlling the excitation current of each vibration generator and the amplification factor of a drive current application circuit that amplifies the drive signal and applies it to the drive coil, based on the weight ratio of each vibration generator, so that the vibrations generated by each vibration generator become nearly identical; An overall control device equipped with

3. 1. An overall control program for implementing, by a computer, an overall control device for use in a vibration test system for performing vibration tests on a test specimen fixed to a vibration table of a plurality of vibration generators, the overall control program comprising: a weight ratio acquisition means for acquiring a weight ratio of a moving part including a vibration table to which a test piece is fixed in each vibration generator; An overall control program for functioning as a control means for controlling the excitation current of each vibration generator and the amplification factor of the drive current application circuit that amplifies the drive signal and supplies it to the drive coil so that the vibrations from each vibration generator approach the same based on the weight ratio of each vibration generator.

4. In the system of claim 1, the device of claim 2, or the program of claim 3, the weight ratio acquisition means applies a direct current as a drive current to the drive coil in an initial state to maintain the vibration table at a reference position, and calculates the weight ratio based on the value of the direct current.

5. In the system of claim 1, the device of claim 2, or the program of claim 3, The weight ratio acquisition means acquires the weight ratio by calculating it based on the shape and weight of the specimen, or by input from an external source.

6. In the system of claim 1, the device of claim 2, or the program of claim 3, The system or apparatus is characterized in that the vibration generating device further comprises a short-circuit switch that short-circuits both ends of the drive coil when an abnormal state is detected.

7. A vibration testing method for performing a vibration test by fixing a test piece to a vibration table of a plurality of vibration generators, comprising: Obtain the weight ratio of the moving parts of each vibration generator, including the vibration table on which the test specimen is fixed, A vibration testing method that controls the excitation current and the amplification factor of the drive current application circuit of each vibration generator based on the weight ratio of each vibration generator so that the vibrations generated by each vibration generator approach the same.

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