Stepper motor using experience
Often meet a problem when use stepper motors ---- step lost.
Our engineer use stepper motor for so many years,stepper motor do not imagine so bad, unless stepper driver developers level is not good.
Because have a good using experience of stepper motor,so the servo motor is not easy to use for me,stepper motor has the advantage of simple programming, wiring less,less fault,large torque,and now the stepper motor pulses up to 60000 PUL/REV,enough accuracy.Speed can also reach 3000 rpm, generally can reach 600 rpm.Stepper motor is generally said to be able to reach 600 rpm, in fact,can not reach this speed,manufacturers says 600 rpm,it is good if can get 500RPM during the running.Normally,the machine can go to 500 rpm,it is very fast.If over 500RPM,may be stalled,the motor make noise like a stuck,which is the speed too high,and the motor can not respond.The occurrence of this phenomenon,solution is: 1,to reduce the maximum operating frequency; 2,enlarge the increase and decrease accelerationtime; 3,reduce the starting frequency; 4,adjust the micro-step to a high level.
Stepper motor speed and torque inversely proportional,the faster rotation, the smaller torque.This is very important in the selection, not a small horse pull a big cart.It does not matter select a big motor,small or just enough is not good,step lost caused by small motor,heavy load.
Generally,the drive signal pulse is 24V string 2K resistance.Manufacturers normally recommend resistance of 1.8K ~ 2K. In fact,I measured, 2K resistance,the pulse voltage is only 2.2V.Later I use 1.5K resistance.The problem is that I came through practice,there is a motor do not go smooth,check a lot of places and did not find the reason,then changed a resistance,it is fine.Normally,optocoupler can withstand 24V, especially there is no resistance,also can be used directly connected.Of course, it is better to install a resistor.
Many people say stepping motor lost step,actually,there are many mechanical reasons, screw bearings are not installed better, screw wore,rail wore,all these problems can make mechanical incorrect,as well as the origin switch quality,directly affect the accuracy.
I have encountered their own procedures to have position fighting,perhaps a technical problem,that is,after processing is completed,the program sometimes run the processing program to back original position,homing program is not connected.This directly caused the cumulative error,after a long time monitoring to find out this problem.This more happens in the evenly degree distribution machine. See a lot of topics about the cumulative error,I think a lot of things meet the case that I met.
Stepper motor produce inertia as big load,this situation caused by moving too far.
Jogging instructions are not correct,especially with the point to move back to the origin,it is wrong.Start and stop of jogging is a complete 90 degrees right angle, start and stop equal to a sudden brake.So the origin must still use homing instructions.
The stepper motor current should not set to rated current, generally a small level,rated 6A, adjust to 5.5A.At this time the torque is enough,the temperature will be high. Although the stepper motor can reach 80 degrees,the temperature is too high,will affect the magnetic field.