Power Drawbar Safety Circuit Question

[RJS100]

My spindle used to be powered by a VFD & induction motor. The VFD was programmed to open a pair of dry contacts any time the spindle was moving. I used these contacts to disable the power drawbar so it would be impossible to activate the drawbar while the spindle was spinning. While this may seem a bit over-kill, I particularly like this logic because I use a foot pedal to operate the power drawbar, and I think there is a small chance that one could accidentally step on the pedal when the spindle is active.

This simple circuit worked great until I upgraded VFD/Induction motor for a JMC 2.6KW AC Servo. I love the AC servo, but the driver does not have set of programmable dry contacts.

I am wondering if there is an Acorn input that I can connect the servo enable signal to, so that each time this input is triggered, I can activate one of the output relays? I prefer not to accomplish this process via special programming as I prefer hard wired solutions for ultimate safety.

Thanks... Richard

[RJS100]

Actually, I was just looking at the attachment diagram and noticed that the first and second terminal of output relay 4 open whenever the servo is enabled. Would it be possible to for me to define a second output relay as VFDEnable? This would solve the problem.

[ShawnM]

An easy solution if you have the spare output is to set it up as "spindle fan" as this output will activate when the spindle starts and deactivate when the spindle stops. Just run your drawbar trigger through the NC side and you are done. It would be more wiring and an external relay if you piggy back on the VFD enable relay because the COM terminal on the relay already has a connection.

There is even a "delay off" setting in the wizard (if you were using it for cooling to keep the fan on longer) and you could set the delay to a few seconds to even allow for the spindle to come to a stop before the drawbar would be active which I'm sure is just a few seconds. Once that delay is up the relay goes back to it's NC state and your drawbar would be active.

[Gary Campbell]

My solution is similar to Shawn's. I use spindles that require case air pressurization. That solenoid is connected to an output configured as "SpindleBrakeRelease". The COM terminal of the drawbar release (ToolUnclamp) relay receives power from the NC terminal of that relay, ensuring that the drawbar cannot be activated when the spindle is active.

Reason for the difference in output config selection is that there is a spindle fan on these units and I often set a delay off, which would prohibit tool changes during that delay

[RJS100]

These are both fantastic solutions. Gary, I find the logic for the spindle fan output a bit easier to follow and I like the option of the time delay.

Thanks... This is great!

[ShawnM]

I suggested the "spindle fan" thinking that mills (with a servo drive and servo motor) dont have spindle motors like an ATC router with a separate cooling fan therefore he wasn't using the "spindle fan" output and it's the easiest method in my mind.

[RJS100]

Wiring it as we speak!

[ShawnM]

Wiring it as we speak!

Let us know how it works Richard.

[RJS100]

Works great! Thanks Shawn.

[ShawnM]

Works great! Thanks Shawn.

Glad to hear it Richard, thanks for reporting back.