JPS6118977B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of measuring stress values that occur continuously in opposite directions, especially for an object to be measured that is fixedly attached to an engine or a vibrator and is vibrated. This invention relates to a device that automatically displays values.

Graphing stress values generated in opposite directions along with changes in vibration frequency is an important resource for understanding the stress distribution of a fixed object and determining its fatigue limit.
For this reason, various methods have been used to create the above-mentioned graphs, and a conventional graph creation device is shown in FIG. 1 and will be described below.

The object to be measured 6 is fixed to the movable part 1' of the vibrator 1,
A strain gauge 2 is attached to point A', and the gauge 2 is connected to a bridge circuit 3, a strain amplifier 4, and an electromagnetic oscilloscope 5. When the strain gauge 2 is vibrated, the low resistance value changes depending on the amount of strain, so a bridge circuit 3 is used to measure the low resistance, and the minute change is amplified by the strain amplifier 4.

Then, the amplified alternating voltage is input to the electromagnetic oscilloscope 5 and the phenomenon waveform is recorded. Thereafter, the width of the waveform is measured, and the gauge factor of the strain gauge 2, the Young's modulus of the object to be measured 6, etc. are substituted into the stress calculation formula to calculate the stress value. For example, set the stress value to 10
Figure 2 shows the graph plotted for each frequency of Hz and connects them with a line, and the graph of the stress value when strain gauge 2 is attached to point A' is shown in Figure 2 A. . The diagrams B and C in FIG. 2 show the strain gauge 2 (another strain gauge of the same type) attached to a portion of the part to be measured other than A'. According to Figure 2, the stress measurement diagrams at three locations A, B, and C have the maximum stress value at a frequency of approximately 110 Hz, but as mentioned above,
The figure shows stress measurements at 10Hz intervals, and the true maximum stress value is
It cannot be said that the actual maximum stress value is displayed because it may exist at another frequency of 100 to 120Hz.

Furthermore, creating graphs using this device requires work such as measuring the waveform width, converting by multiplying by a coefficient, plotting stress values for each frequency, and connecting lines, which is prone to errors and requires a huge amount of man-hours. It had a problem.

The present invention has been made to solve the above-mentioned problems, and a peak detector and an X-Y recorder are connected after the conventional strain amplifier, and stress values due to changes in vibration frequency are measured using a pen of the X-Y recorder. This allows continuous, automatic recording of multiple records at the same time.

Examples thereof will be described below with reference to the drawings.

FIG. 3 is a block diagram according to the present invention, in which the object to be measured 6 is fixed to the movable part 1' of the vibrator 1, and the stress measurement point is
A foil strain gauge 2 is attached to A', a bridge circuit 3 and a strain amplifier 4 are connected, and then a peak detector 7 and an XY recorder 8 are connected.

For convenience of explanation, the measurement point in this embodiment is set to one point A'. Normally, measurement is carried out at several points at the same time, and the measurement line diagram for the measurement point A' is shown as A in Figure 4, while the other B and C lines are drawn using strain gauges at other locations on the object to be measured. 2 was pasted and recorded automatically in the same way as line A.

By changing the frequency of the movable part 1' of the vibrator 1, the strain gauge 2 attached to the measuring part A' of the object to be measured 6 changes its low resistance value due to compression and tension, and the bridge circuit 3 , strain amplifier 4
The amplified alternating voltage waveform is output and input to the peak detector 7.

The peak detector 7 determines the envelope of the upper limit or lower limit of the input waveform, or, for example, if the upper limit of the envelope is Pu and the lower limit is Pl, the peak detector 7 calculates the curve of Pu+Pl/2 or Pu-Pl/2. It has a function that allows it to record. That is, the peak detector 7 has a function of setting the gauge factor of the strain gauge 2 and the Young's modulus of the material of the object to be measured 6 in order to calculate the stress value from the envelope. In addition to the linear output, since the stress value is extremely large, it will protrude from the recording paper of the X-Y recorder 8, so log output is also possible. In this way, the peak detector 7 has various functions, and the various units of the peak detector 7 (not shown in the figure) ) are adjusted and set.

The X-Y recorder 8 inputs the frequency emitted from the vibrator 1 on the X axis (the horizontal axis is the frequency shown in Figure 4), and the stress value is input on the Y axis (the vertical axis is the stress vibration frequency shown in Figure 4). As shown in FIG. 4, the data is continuously and automatically recorded using a pen that is operated in conjunction with each servo motor.

As described above, the present invention replaces the conventional method of manually measuring, converting, plotting, etc. using an electromagnetic oscilloscope to obtain the stress value for the vibration frequency of the object to be measured by using a peak detector and an X-Y A recorder is used to continuously and automatically record the stress values over the entire vibration frequency measurement range, so there are no measurement errors, the maximum stress value can be read accurately, and the stress of the object being measured is Since multiple values can be recorded simultaneously, the number of man-hours required for measurement can be significantly reduced. In addition, this device has many excellent effects that can be used to measure positive and negative pressures, variable loads, etc.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional device, and Fig. 2 is a graph showing the relationship between vibration frequency and stress in the device.
FIG. 3 is a block diagram showing the device of the present invention, and FIG. 4 is a graph showing the relationship between vibration frequency and stress created with the device. 2... Strain gauge, 3... Bridge circuit, 4... Strain amplifier, 6... Measured object,
7...Peak detector, 8...X-Y recorder.

Claims (1)

[Claims] 1. Attach a strain gauge to the object to be measured, connect the gauge to a bridge circuit and a strain amplifier, input the output of the alternating voltage amplified by the amplifier to a peak detector, and detect the waveform of the alternating voltage by the detector. An apparatus for automatically displaying a stress value, which converts the envelope of the above into a stress value, and continuously and automatically records the measured frequency and its stress value on an X-Y recorder connected to the peak detector.