VMC toolchangers

[Billiam]

Hello,

I'm curious as to how toolchangers interface with the control on modern VMCs. I understand that a macro firsts gets the spindle to the proper Z-height. But what happens next during the M6 execution?

I was told that the toolchangers themseves are cam driven. Is that true with both umbrella type and arm type ATCs? Does a servo drive the cams? And is all this controlled using a PLC or could Mach 3 or similar software take care of it?

Thanks!

[Starleper1]

Check out hossmachine.info he made a ATC using stepper motors and Mach3 to control it. Theres many different ways it can be done.

[Glacern]

Sorry, replied to the wrong thread.

[Caprirs]

ATCs vary on the full size VMCs. There are two general types. One is the umbrella style as seen on machines like Haas and Fadal. The other is the swing arm seen on higher end machines where the tools are stored on a belt (and the tools are laying horizontally).

On the umbrella types, the tool magazine is driven to/from the spindle using an air cylinder usually. The control just activates air solenoids to drive it in and out. To rotate the magazine, there is a motor that drives a geneva wheel to move from tool to tool. A proximity sensor or roller switch counts each time the geneva wheel makes a revolution so the control knows when to turn the wheel off.

There are numerous switches to tell the control where everything is and a lot of interlocks designed into the PLC to prevent something catastrophic from happening. For example, it is undesirable to attempt a tool change while the spindle is turning 8000rpm. There are switches at the top of the drawbar actuator to tell the control when the drawbar is engaged or released. Switches tell when the magazine is in or back. There is a spindle orientation sensor.

Some controls do everything through a macro using G & M codes. Others do everything in the PLC. Most use some combination of a macro and PLC ladder circuit.

The swing arm tool changers are more complicated but have a lot of advantages such as considerably faster tool changes and keeping the unused tools away from where the chips are flying.

[Starleper1]

I was unaware about the geneva wheel. Interesting...