Belt tension meter

It is a sonic belt tension meter.
Calculate the tension (unit: N) of the belt (timing belt etc) tightened between the pulleys from the frequency when the belt is played.

Measurement method

1, initial setting
Set the belt.
1) Press the setting button.
Enter the state of the belt you want to measure.
1. The number of teeth on the left and right pulleys and the number of teeth on the belt.
2. Belt pitch mm.
3, belt width mm.
4, belt unit weight g / (m ・ mm)
　= Belt width: 1 mm x belt length: 1 m weight g
Note)
If the unit mass of the belt is kg / m (weight per 1 m),
　3. Enter 1 for the belt width!
　4, W (kg / m) x 1000 for unit length mass

2, measurement
1) Bring the phone's mouthpiece close to the center of the belt you want to measure and press the ensure button. (Displays during measurement)
2) Play the center of the belt to make a sound like a string.
(When the belt is flipped, its frequency has the property of converging to a constant frequency according to the tension of the belt.)
3) When vibration of a certain frequency of the belt is detected, the waveform of the sound at the time of detection, the frequency and the belt tension (unit N) calculated by the belt setting set in 1 are displayed on the monitor.

3, Other
1) You can save the belt setting values.
2) You can flip the screen upside down by setting the ↑ ↓ toggle on.
(If you turn it upside down, you can measure with the call port facing up.)
3) If you turn on repeat toggle, you can measure continuously.

Caution
This tool uses the recording function of smart phone, and obtains the obtained waveform
A certain frequency is detected with a simple method.
For this reason, please use measurement results and accuracy as a guide only.
Maximum measured frequency: Approximately 400hz

Remarks
Calculation formula of belt tension conversion from frequency is carried out by the following calculation.

Hz: Measurement frequency / sec
T 1: pulley 1 number of teeth
T 2: Number of pulleys 2 teeth
B: Number of belt teeth
P: Belt pitch mm
M: Belt unit mass g / m.mm (1 mm width x 1 m belt weight g)
W: Belt width width mm
Note) When unit of mass per unit weight of belt is set to kg / m (weight per kg)
M = W (kg / m) x 1000, w = 1 (mm) Please enter!

Z: Pulley shaft length
S: length of linear portion of belt
R1: Pulley 1 radius
R 2: Pulley 2 radius
Pi: Pi = 3.14 ,,,

R 1 = t 1 × p / pi
R 2 = t 2 × p / pi

Z = (b + (b ^ 2- 8 x (r 1 - r 2) ^ 2) ^ 0.5) / 8
S = (Z ^ 2- (r 1 - r 2) 2/4) 0.5

Belt tension N = 4 × m × w × S ^ 2 × Hz 2 × 10 ^ - 9