Rotation unevenness on winding rolls for pulp, magnetic tape, industrial film, etc. will have a serious effect on the product quality. In this example, in order to evaluate the interrelationship between the rotation unevenness of a winding roll and the product quality, the rotation unevenness (rotation fluctuation ratio) of the winding roll is analyzed.
<Measurement procedure>
1) Using a line speedometer the RP-7400 roller encoder, detect the line speed of the target by directly contacting the roller with the target.
2) Calculate the fluctuation of the line speed by the FV-1500 high-speed F/V converter.
3) Input the output (calculation result) into the CF-9000 series portable FFT analyzer, and analyze the frequency variation output to obtain the speed fluctuation ratio.
Equipment configuration
| Model name | Product name | Remarks | |
|---|---|---|---|
| 1 | CF-9000 series | FFT analyzer | Analyze frequency and extract the speed fluctuation components of the timing belt. |
| 2 | FV-1500 | High-speed F/V converter | Converts the input pulse from the period time between pulses to the frequency and outputs a voltage proportional to the frequency of the input pulse. |
| 3 | RP-7400-1200 P/R | Roller encoder | Measures the line speed or the length of the target by detecting the rotation of the roller by directly contacting the roller on the object moving on the production line. The outer circumference of the roller is 200 mm, and 1,200 pulses are output. |
Commentary
The outer circumference of the roller of the RP - 7400 roller encoder is 200 mm, and the number of output pulses per rotation is 1,200 pulses. When the FV-1500 high-speed F/V converter is used with the RP-7400, 1,200 times of rotation fluctuation can be measured to 200 mm of roller rotation.
In addition, FV-1500 has digital display function of input frequency. The relation between gate time, velocity, and count value (display value) can be obtained from the following equation.
|
C : Count value (display value) T : Gate time πＤ: 0.200 m R : 1200 P/R (number of pulses per rotation) V : Velocity m/min |
The gate time T = 1 s.
For example when V = 20 m/min, the digital display of FV-1500 is 2000 from the above equation.
That means when you read it as 20. 00, it shows the speed per minute.
Also, using the deviation output function of FV-1500, if you set the average speed to 20 m/min (in this case, frequency = 2,000), it outputs ± 5 V for ± 5% of 20 m/min, and can output voltage as speed fluctuation ratio. This voltage output is also high-speed response.
Analysis data example
This analysis data is obtained by measuring and analyzing the rotation unevenness of the winding roll that has the following specification with the above-mentioned equipment configuration. It decelerates the rotation of the motor, which is the driving supply by the timing belt.
| Motor rotation speed | 200 r/min |
|---|---|
| Rotation speed of winding roll | 80 r/min |
| Number of gears of timing belt | 67 |
| Roll feed speed | 20 m/min |
The following values can be read from this analysis data.
•Frequency H at which fluctuation due to timing belt appears
H: H = 80 r/min x 1/60 x 67 (number of the gears of the timing belt) ≈ 90 (Hz)
Speed fluctuation due to the timing belt appears in the frequency analysis data as a component of approximately 90 Hz.
| Frequency | 90 Hz |
|---|---|
| Voltage | 50.7 mV (0.0507 V) |
| Roll feed speed | 20 m/min |
| Fluctuation ratio | 0.051% |
| Frequency | Total power value |
|---|---|
| Voltage | 90.8 mV(0.0908 V) |
| Roll feed speed | 20 m/min |
| Total fluctuation ratio | 0.091% |
Key points
•Detect the speed fluctuation correctly by a high-pulse rotary encoder and a fast-response FV converter.Revised:2018/10/31
