How to standalone test the servo motor of a shearing machine

[saesaria]

Hi Expert,

The following shearing machine having a problem with the measurement of its stopper position.

When we want to cut a metal plat, we usually set the stopper position to where the plat will be cut for a particular length. For example if we want to cut a 300mm metal plat, we set the axis of the stopper to be 300mm in the controller. The problem is, the cut result is always not exactly the same with the setting, when we manually measure the length of the stopper from the base, it is not exactly 300mm. Based on the several other trials and manual measurement, the error measurement is about 1mm for every 200mm move.

Beside the other factors which we believe can lead to this problem such as error in the gear train and the shaft, firstly we want to make sure if the servo motor whether is still good or not. Is there any way to do a standalone test of this servo motor? if yes, how to do it?

Or do you have another idea to resolve this problem?

Thanks in advance.
Sona

 

[KlausST]

Hi,

At first I´d analyze the error behaviour:
set the stopper to 50mm (without cut)
then
* set the stopper to the position (p)
* do a measuremetn with a ruler (r) from stopper to cutting edge
* cut a sheet and measure it´s length (s)

pos p | ruler r | sheet s
(forward from 50 to )100mm | ? r | ? s
fwd 200mm | ? r | ? s
fwd 300mm | ? r | ? s
fwd 400mm (no cut)
back 300mm | ? r | ? s
back 200mm | ? r | ? s
back 100mm | ? r | ? s

give us the six values of r and six values of s

With these values we are able to detect whether there is an accuracy problem, a general precision problem and/or a hysteresis problem.

Don´t hurt yourself.

Klaus