|Robotics interfacing to machine tools
Setting up the Robot call for load/unloading of parts
Robot integration with machine tools is actually very simple. You generally do not need any robot interface from the Machine tool builder if you are adding on your own PLC, although it will make things easier to interface because then you would not have to search through the electrical books to find the signals to tie into. The only thing you may or may not need from the machine tool is some external M-codes (sometimes special order) Depending on if you want the robot to perform the clamping and monitoring or do you want the machine tool to perform these functions. The other signals you will need are End of cycle, NC in operation, Alarm, External feed hold or alarm input and door open or closed. Many of these signals can usually be taken off of the 3 stage signal light, and the door interlock circuit.
The robot load/unload usually is called in one of the following two ways.
First the robot can be called by the end of cycle signal / M30. When a machine hits the M30 in the NC program a signal is output to the robot and the robot looks at various conditions and begins to unload and load new parts. When the robot has completed its operation it will output a cycle start to the machine tool just as if the operator hit the start button himself. The robot load will then be complete. This is the most common setup.
The second way in which the robot cycle is somtimes called is by an M-code. An External M-code can be output and the NC program will wait on that m-code until it receives a completion signal or M code finish as it is sometimes called. Once the robot receives this signal it begins the load/unload process and when it is complete output a M code finish signal back to the machine tool.