JP6191538B2 - Vibration test equipment - Google Patents

Description

  The present invention relates to a vibration test apparatus that repeatedly applies a test force to a specimen.

  In vibration test equipment, for example, the vibration (seismic acceleration) given to the structure by an actual earthquake and the vibration given to the part during driving of the automobile are reproduced, and the earthquake resistance of the structure and the durability of the part are reproduced. Fatigue / endurance tests are conducted to verify the above. Such a vibration test apparatus includes a vibration table that is supported by a bearing and on which a specimen is placed, a hydraulic cylinder that drives the vibration table, a displacement meter that detects the amount of movement of the vibration table, and when the vibration table moves. An accelerometer that detects the acceleration of (see Patent Document 1) is provided.

  Moreover, since vibrations such as actually measured seismic waves are usually recorded as acceleration waveforms, an acceleration control mechanism that uses an acceleration input signal as a target value and a displacement control mechanism that controls the position of the vibration table are provided. A vibration test apparatus has been proposed (see Patent Document 2).

JP-A-11-101708 Japanese Patent Publication No.7-18772

In the movement control of the shaking table, in order to grasp the absolute position of the shaking table (a position indicating how far from the neutral position as a reference), a displacement control mechanism is used as in the vibration testing apparatus described in Patent Document 2. Control is performed to maintain the center position of the shaking table. On the other hand, between the rolling element of the linear drive bearing that supports the vibration table and the rail raceway surface, moderate lubrication is required, but when the excitation stroke of the actuator that moves the vibration table is minute, so that the rolling elements of the bearing continues to contact the raceway surface of the rail at the same 箇 plants. For this reason, oil shortage occurs between the rolling elements and the raceway surface, which may cause problems such as fretting.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vibration test apparatus that reduces the problems of the bearings by moving the neutral position of the vibration table during the test.

The invention according to claim 1 includes a vibration table supported by a bearing and a load actuator connected to the vibration table, and the vibration table is moved by driving the load actuator to move the vibration table. A vibration test apparatus for applying vibration to a specimen placed on the apparatus, comprising a waveform adjustment unit for adding a superimposed waveform for changing the neutral position of the vibration table to a target waveform, and adjusting the waveform adjustment unit Control means for controlling the drive of the load actuator based on the target waveform , wherein the superimposed waveform is a waveform having an amplitude for rotating the rolling element in the bearing at least once with respect to the raceway surface. To do.

According to a second aspect of the present invention, in the vibration test apparatus according to the first aspect, the superimposed waveform is a waveform having an amplitude that causes the rolling element in the bearing to rotate five to five times with respect to the raceway surface.

  According to a third aspect of the present invention, in the first aspect of the present invention, the bearing is a linear drive bearing.

According to the first to third aspects of the present invention, the target waveform based on the actual vibration waveform in the waveform adjusting unit is set as the target waveform adjusted by adding the superimposed waveform for changing the neutral position of the vibration table, since controlling the driving of the adjusted load actuator based on the target waveform, is changed Shaking neutral position during the test, the rolling elements of the bearing is prevented from continuing to contact the raceway surface with the same 箇 plants Can do. As a result, it is possible to reduce problems such as fretting caused by running out of oil on the rolling elements and raceway of the bearing.

It is a schematic diagram which shows the main structures of the vibration test apparatus which concerns on this invention. 3 is a schematic diagram of a bearing 40. FIG. 3 is a block diagram showing a functional configuration of a control device 50. FIG. It is a wave form diagram explaining the adjustment of the target waveform in the waveform adjustment part 52. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a vibration test apparatus according to the present invention, and FIG. 2 is a schematic diagram of a bearing 40. 2 (a) is a partial perspective view of the bearing 40, FIG. 2 (b) is a sectional view for explaining the positional relationship between the rail 41 and the ball 46, and FIG. 2 (c) is a side view thereof. It is. 2B and 2C, the carriage 42 is not shown.

  In this vibration test apparatus, a vibration table 24 installed on a floor G through a bearing 40 so as to be able to reciprocate is vibrated by a load actuator 31 so as to be continuously connected to a specimen 20 placed on the vibration table 24. Thus, a test for applying a vibration load is performed.

  The control device 50 is configured by a computer or a sequencer that includes a storage device such as a ROM and a RAM, and an arithmetic device, and controls the overall operation of the vibration test device. The control device 50 functions as control means of the present invention. A drive signal for the load actuator 31 is transmitted from the control device 50. This drive signal is input to the servo valve 32 of the load actuator 31 via the amplifier 35. The displacement amount of the vibration table 24 is detected by the displacement meter 23, and the displacement detection signal is input to the control device 50 via the amplifier 36.

  The load actuator 31 is a double-acting hydraulic cylinder, and the piston 31c and the rod 31b are reciprocated by hydraulic fluid supplied from the hydraulic source 34 into the cylinder 31a via the accumulator 33 and the servo valve 32. By connecting the vibration table 24 to the rod 31b of the load actuator 31, the vibration table 24 repeatedly moves in the X direction shown in FIG. 1 in synchronization with the reciprocation of the rod 31b of the load actuator 31.

  The bearing 40 inserted between the vibration table 24 and the floor G is a carriage 41 connected to the rail 41 fixed to the floor G and the lower surface of the vibration table 24 as shown in FIG. 42 is a linear drive bearing (linear motion bearing). A rail groove 43 is formed in the rail 41, and the ball 46 as a rolling element rotates on the surface of the rail groove 43, that is, the raceway surface of the bearing 40 as the carriage 42 moves (FIG. 2 ( b) and (c)). Note that the X direction in FIGS. 2A and 2C is the moving direction when the vibration table 24 reciprocates as in FIG.

  The vibration acting on the specimen 20 is measured by the accelerometer 21 provided on the vibration table 24 on which the specimen 20 is placed, and the measured value is input to the control device 50 via the amplifier 37. In this vibration test apparatus, the accelerometer 21 is configured to be able to be moved to an arbitrary location on the vibration table 24 and the specimen 20 according to the content of the test to be performed.

  FIG. 3 is a functional block diagram inside the control device 50. In FIG. 3, only the configuration necessary for executing the functions of this embodiment is shown.

The control device 50 includes a transfer function correction unit 51 and a waveform adjustment unit 52, and executes excitation control of the shaking table 24. The transfer function correcting unit 51 identifies each transfer function G _A (S), G _S (S) in the control system including the load actuator 31 and the specimen 20 and monitors the control target, and also includes the displacement meter 23 and the accelerometer. Each transfer coefficient is corrected according to the output from 21. That is, in this vibration test apparatus, it is possible to issue a vibration command for the vibration table 24 by displacement control by feedback from the displacement meter 23 and vibration control by acceleration control by feedback from the accelerometer 21.

  The waveform adjustment unit 52 adjusts the actual vibration waveform r1 that is an acceleration waveform such as an actual seismic wave, which is input as a target waveform to be reproduced by the vibration test apparatus, as a control target for the vibration control of the vibration table 24. The adjustment of the waveform to be the target waveform r2 is executed.

  FIG. 4 is a waveform diagram for explaining the adjustment of the target waveform in the waveform adjustment unit 52. 4A shows an example of the actual vibration waveform r1, and FIG. 4B is a preferred example of the superimposed waveform to be superimposed on the actual vibration waveform r1 of FIG. 4A. The superimposed waveform is a sine wave. Shows the case. FIG. 4C shows a target waveform r2 in which the sine wave of FIG. 4B is superimposed on the actual vibration waveform r1 of FIG. In addition, the vertical axis | shaft of each waveform diagram in FIG. 4 is acceleration (gal), and a horizontal axis is time (ms).

  For example, in the case of the ball 46 having a radius Amm, the displacement in the X direction from the design neutral position of the vibration table 24 is at least ± Aπmm, and the ball 46 makes one rotation with respect to the track surface of the rail groove 43. .

  The acceleration and the displacement have a relationship that they can be converted into displacement by integrating the acceleration twice, and can be converted into acceleration by differentiating the displacement twice. Therefore, if the absolute value of the maximum amplitude of the displacement waveform obtained by integrating the acceleration waveform shown in FIG. 4A twice does not exceed Aπmm, the ball 46 is 1 with respect to the track surface of the rail groove 43. It will continue to contact at the same location without rotating, causing problems such as fretting.

  Therefore, in the present invention, the waveform adjusting unit 52 sets the waveform obtained by adding the superimposed waveform to the actual vibration waveform r1 input as the acceleration waveform as the target waveform r2, thereby providing a neutral position that serves as a reference position in the reciprocating motion of the vibration table 24. The position is moved to a position different from the designed neutral position so that the ball 46 in the bearing 40 can rotate at least once relative to the raceway surface. The superimposed waveform is a repetitive waveform having a constant cycle, and is a long cycle waveform that does not affect the vibration load applied to the specimen 20. The period of the superimposed waveform is desirably about 10 times or more the longest period of the actual vibration waveform r1.

The superimposed waveform in the present invention is a waveform having an amplitude D that causes the ball 46 to rotate at least once with respect to the track surface, as shown in FIG. The value of the amplitude D is, for example, and FIG. 4 (b) waveform twice integrating the amplitude Oh lever with a value equal to or larger than the radius Amm balls 46 of the displacement waveform, to ensure the ball 46 against the raceway surface It is possible to make one rotation or more. The amplitude D is not limited as long as the ball 46 is rotated by one or more rotations, but is preferably about 2 to 5 rotations. If there is a margin in the length of the rail 41 and the stroke of the load actuator 31, the amplitude D may be larger than that.

  When a long-period sine wave shown in FIG. 4B is added to the actual vibration waveform r1 shown in FIG. 4A, the waveform shown in FIG. 4C is obtained. By outputting a vibration command with the waveform shown in FIG. 4C as the target waveform r2 from the control device 50, a vibration load is applied to the specimen 20 while changing the neutral position of the vibration table 24 at a constant period. The applied vibration control is executed. Then, when the neutral position of the vibration table 24 fluctuates during the test, the ball 46 makes one rotation or more with respect to the track surface during the test.

  In the present invention, the actual vibration waveform r1 input as the acceleration waveform is not adjusted after being converted into a displacement waveform, but the actual vibration waveform r1 input as the acceleration waveform has a long period that is a direct waveform of a constant period. Since the target waveform r2 to which the sine wave is added is adjusted, even when the vibration control of the vibration table 24 is performed by acceleration control instead of displacement control, the neutral position can be easily changed at a constant cycle, It is possible to prevent problems such as fretting caused by running out of oil in the bearing 40.

  In this embodiment, a sine wave is shown as the superimposed waveform. However, for example, a triangular wave may be used. That is, the superimposed waveform is a waveform having a period that does not affect the vibration load applied to the specimen 20 and a waveform having an amplitude D that causes the ball 46 to rotate at least once with respect to the track surface. It is not limited to waves.

  In the embodiment described above, the relationship between the rotation of the rolling element and the raceway surface has been described using the ball 46 having a spherical shape as an example. However, even when the rolling element has a cylindrical roller shape, Application can prevent problems such as fretting caused by running out of oil.

  In the above-described embodiment, the example in which the linear motion bearing is inserted between the vibration table 24 and the floor surface is shown. However, the vibration table in the vibration test apparatus that applies rotational vibration to the specimen 20 is connected. With respect to the bearing that supports the rotating shaft, the application of the present invention can prevent problems such as fretting due to running out of oil.

DESCRIPTION OF SYMBOLS 20 Specimen 21 Accelerometer 23 Displacement meter 24 Shaking table 31 Load actuator 32 Servo valve 33 Accumulator 34 Hydraulic power source 35 Amplifier 36 Amplifier 37 Amplifier 40 Bearing 41 Rail 42 Carriage 43 Rail groove 46 Ball 50 Controller 51 Transfer function correction | amendment part 52 Waveform Adjustment section

Claims (3)

A vibration table supported by a bearing; and a load actuator connected to the vibration table; and driving the load actuator to move the vibration table to vibrate the specimen placed on the vibration table. A vibration test apparatus for providing
A control unit for controlling driving of the load actuator based on the target waveform adjusted by the waveform adjustment unit, the waveform adjustment unit adding a superimposed waveform for changing the neutral position of the shaking table to the target waveform; ,
The vibration test apparatus according to claim 1, wherein the superimposed waveform is a waveform having an amplitude that causes the rolling element of the bearing to rotate at least once with respect to the raceway surface . The vibration test apparatus according to claim 1,
The superposed waveform is a vibration test apparatus having a waveform with an amplitude that causes the rolling element in the bearing to rotate two to five times with respect to the raceway surface. The vibration test apparatus according to claim 1,
The vibration test apparatus, wherein the bearing is a linear drive bearing.

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