Are you going to cut to length on the fly or move stop cut repeat?
move, stop, shear down (cut), move backward a little, shear up, move foward a little and then repeat.
That thread dragged on way too long. I would be embarrassed.The "move backward a little" is not covered in this thread but if your up for some reading try this.
http://www.plctalk.net/qanda/showthread.php?t=11015&page=1&highlight=learning
What about ramping down?david90 said:The controller counts the pulses and stops the motor at a preset or desired length.
That is a long time and lost production.After that, the controller delays for 1 sec before outputting a signal to a relay which extends a shear to cut the material.
Ok, now we know why.Before retracting the shear, the motor should reverse to pull the material back a bit before retracting the shear to prevent the material from briefly catching on to the shear's blade.
This seems like a wasted step. Why not index forward the cutlength plus the "clear shear" distance. This skips the retracing the "clear shear" move.The material should move forward to the original position after the shear retract to prepare for the next cycle.
It will work, eventually. The right tools depends on whether you are making many of these or just one.I'm trying to automate the system using Eaton's fusion controller. This controller is counter and PLC in one package. The controller has an encoder feedback input, analog output, high speed counter , LCD, buttons and limited ladder logic programming capability.
What about ramping down?
Waiting for inposition?
That is a long time and lost production.
Ok, now we know why.
What about ramping up and ramping down and then waiting for inposition then raise the shear. Then wait for the shear to be clear.
This seems like a wasted step. Why not index forward the cutlength plus the "clear shear" distance. This skips the retracing the "clear shear" move.
It will work, eventually. The right tools depends on whether you are making many of these or just one.
With the right tool the motion program would be done in about it took me to write this. Something with sequential function charts or a built in state machine would make this go faster.
Yes, you should use a statemachine.
http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Seq/impl.html
In PLCs there is usually a bit for each state. That looks like the F contracts. I don't see any outputs just the means of making the transition from one state to another.
I think you have the right idea. It is just the details that will take time to figure out.
Yes.Should I regard each of the machine's action (move, stop, shear down (cut), move backward a little, shear up) a state?
it is easier when each state definition is as small as possible. Some states may last only one scan. Show us your best attempt so we have some idea of how your controller works.When do I put the machine's action in a state and when do I put separate them in two different states?
the motor that moves the material to the shear is a large 100HP motor controlled by a DC drive.....
Before retracting the shear, the motor should reverse to pull the material back a bit before retracting the shear to prevent the material from briefly catching on to the shear's blade.....
I would like to give the operator the ability to jog the motor. In the state diagram, where would be the best place for this functionality? What are some safety concerns regarding the jog function?