Need Help!- Spindle RPM -Manual Range Change

[drdfab]

Hello, I'm new to posting on this forum, but have often come to get ideas and advice. I just acquired a 1994 Fadal VMC 15 (10 HP Baldor SWEODRIVE w/ 7500 RPM spindle w/manual high/low range) and am trying to teach myself the control and machine. I have been having spindle speed issues as well as belt slipping problems. Today I spent hours trying to discover why the actual RPM of the spindle nose was drastically different from the 'S word' which I input on the control (talk bout weird things happening before I found this out!!). Well, come to find out that the spindle RPM adjustment factor (in 'SETP') was set to high. I adjusted it back down to "0" and got the RPM within 30. Now for my main question..... How does the control know when you manually change the range to "low" ??? The encoder is mounted on top of the motor not the spindle..... Along with that, when rigid tapping, will I always have to be in high range? Or will I just have to adjust some other parameter? I noticed earlier that Edster had posted about upgrading to cogged belts on a VMC 15....

[Neal]

Hi range goes from 2501 to max RPM and Low range goes from 0 to 2500 RPM.

Neal

[drdfab]

So how does the control know that you manually changed the belt from 1:1 to 2:1 ? Or do you just have to double the "s" command and the lead in rigid tapping?

[Neal]

When you program the "S" spindle speed code you must know that 2500 is the top of low range and the bottom of high range is 2501. You must adjust the pulley belt accordingly. That is why the later machine have automatic high/low system that keys off the program "S" command.
There in lays the difference between MANUAL and AUTOMATIC spindle RPM handling.

Neal

[drdfab]

Just in answer to my own question if anyone is interested.... I called David from VMC Electric and he was very helpful in answering all of my questions.... Ok, so my VMC 15 has a 10HP closed-loop vector drive and the motor has a wye-delta configuration. It has a set of contactors which switch the motor windings between wye and delta namely at 2500 and 2501 RPM... (pardon any errors in my feeble explanation, hopefully the idea is clear) So I'm in 'high belt range' (1:1) I have RPM range of 0 to 7500 RPM. And in my control I select "SETP" then change "SPINDLE TYPE" to "7500 WYE/DEL" ..... Now my control knows where I have my manual range set so that the "S" word will correspond to the actual spindle RPM. So when the need for more torque comes, I manually change the belt to 'low belt range' (2:1) Now I have spindle RPM range of 0-3750 RPM. (The motor still goes 0-7500) Then I go into "SETP" and change "SPINDLE TYPE" to "3750 WYE/DEL" .... And now the "S" word which I input is correct with actual spindle RPM....


And then back to one of my other wonderments... What does "RPM FACTOR" in "SETP" do? Well, David told me that setting was for the models of VMC's which had only inverter drives on them (not Closed-Loop Vector Drives).... You could adjust that up and gain a little torque by compensating for 'electrical slip' in the motor.