VFD with air brake on Series I BP

[Mr. Technical]

Hi,

I just bought a VFD from Hitachi (SJ200-015NFU2) and am running my BP Series I spindle from it with no problems. I would like to retain the air brake system since I need it to stop the spindle quickly, but more importantly to hold the spindle in position while I tighten the tools into the collet chucks. (I know that I could get a bench holder for changing tools, but that's too much hassle.) I'm wondering if anyone has integrated the VFD and the original spindle brake, and how they accomplished it.

The VFD has logic outputs and a relay that can be N.O or N.C. The spindle brake relay is 24V, and is activated to release the brake and allow spindle rotation. So my questions are:

Am I asking for trouble using the VFD to control the spindle brake solenoid since it will take a second for the solenoid to release the brake, and meanwhile the VFD is trying to ramp up?

Is there a better way to use the run command from Mach 3 to release the brake, and say a second later pass the run command on to the VFD?

Will our hero get the help he needs to complete this daring project?!?!?

Thanks for any help (especially schematics)

Ian

[mactec54]

Hi Mr Technical

If you want to stop the spindle very fast, then you will need a braking resistor to do it,
the drives have a small braking resistor, but if you try to stop to fast the drive will go into an alarm, you can use the drive's relay to turn the brake on & off, but you will also need to have a switch for manual mode for switching the brake on & off as well, you would do this by using a relay if it is not controled by software then you may need a timer but I see you are using Mach so you can do it in Mach by using the Brain

[Al_The_Man]

It should hardly take a second for a pneumatic brake to activate!
A few msec maybe.
I have mine set up using a VFD output configured for At-Zero-speed.
The brake comes off immediately at start and picks up when the VFD has stopped.
I have a manual override that picks the valve up when stopped if need be.
Al.

[Mr. Technical]

Thanks for the replies. It jogged something in my consciousness. The original system sent the command to start the spindle and release the brake at the same time. I seem to remember the motor working a little bit harder for less than a second, and then continuing on just fine. In view of that, I plan to wire the brake release circuit to the on-board relay in the VFD and see if I fault out. If not, problem solved. I appreciate the help!

Ian