S120 for Machine Tool Spindle with Positioning

Hello,

With the S120, how do we smoothly transition from running at a speed set-point (up to 10,000 rpm), to a positioning (traverse) command without first stopping the spindle?

We are trying to use the S120 drive with CU320-2 controller and Basic Positioner to replace a Siemens 6SC650 spindle drive in one of our older vertical spindle machine tools. Spindle position feedback is from incremental encoder via SMC30. All the Siemens drives we have used in the past ( Simodrive 6SC650, 611A, and 611U) all allowed accelerating or decelerating spindle to a "search" speed of several hundred rpm, and then positioning the spindle.

We have been told that with S120 and Basic Positioner, we should be stopping the spindle before positioning. This will add time to each spindle positioning (each tool change). Maybe only a second or two, but it will be noticeable, and for production machines, loosing this time every tool change adds up. In a test setup we have been able to activate reference & traverse modes from a slow rpm w/o fault, but not higher rpm.

We must also emulate the existing drive interface of analog speed set-point, and one digital input "spindle orient" command. We are using Free Function Blocks in CU-320-2 so "orient" commands reference if not already referenced, and then commands a traverse block (position), or goes directly to traverse block command if spindle had been referenced.

Thank you,
Marty

... you can use the Basic positioner in MDI- mode

1st) you use "setup" mode (within MDI - mode)

2nd) you can Change on the fly to absolute positioning.

... I don´t understand what you want to do in Speed controlled mode.

Use the Basic positioner in MDI. So you can do the endless Setup mode and Change to absolute positioning during Operation.

If you want to use an analoge Input as Speed setpoint, you can take the Basic positioner override.

For negative direction use the direction bit BWD from MDI- mode.

Thank you Zako_ and Marko for responses.

Reason for speed control mode :

Motor (spindle) is normally run in positive direction, at 20 - 10,000 rpm., or positioned to an angle of 0 deg or 180 deg. for tool changes, etc. However, machine also does "rigid tapping" of holes. Tap is held in spindle tool adapter. Spindle rpm must be varied smoothly and is synchronized with linear feed of machine Z-axis by the CNC. At bottom of tapped hole, both spindle rpm and axis feed decelerate together to stop, then accelerate together in reverse to pull tap back out of hole. If spindle does not do forward deceleration to reverse acceleration smoothly, tapped hole is damaged and/or tap broken.

Using MDI mode looks good except that v_set limited to positive values. Machine CNC uses analog command of -10v to +10vdc to command spindle rpm. Using direction selection inputs would require using Free Function Block logic to sense when analog command transitions +/- to then set direction bit(s) in MDI. This probably not as smooth as CNC analog command. We will have to test.

I don't understand - "If you want to use analoge Input as Speed setpoint, you can take the Basic Positioner override." - How do you use Basic Positioner override to allow dynamic control of rpm.?

New question published by MBS is split to a separate thread with the subject Using 2 S110 drive one as feed and other one speed - Not able to synchronize both .

Best regards
Jen_Moderator