2014-03-25 12:24 GMT-03:00 Dave Cole <linuxcncro...@gmail.com>: > Is the drive train self locking, so that if you loose power, the load > does not drop? > Or do you have a brake on the motor or someplace else? > > The joint is moved by means of a lead screw of 50 mm of diameter and 8 mm of pitch. The nut is made out of nylon and it's 150 mm long. Given this the load is well supported and it can't be moved if the motor stops or in case of power failure. Also the ways are made of steel of about 80 mm of diameter so the machine is really heavy. The motor is coupled to the screw in a 2:1 reduction with spur gears.
One thing I have heard that can be a problem when using a squirrel cage > AC motor like this at very low speeds, is that the motor can overheat > due to insufficient cooling because the the fan does not push much air > over the motor to cool it. That is why many specialty motors that are > designed to run at low speeds, have forced air cooling via a separate > motor driven blower. > > Yes indeed. For example we have a Mazak turning center that has forced air through the spindle motor (wich is an ordinary AC motor) to cool it at any speed. Anyway this machine is going to work at really short intervals so the motor is not going to suffer from the heat, plus the speed we're going to use is always full speed and somtimes a little bit more so the motor is always cooled. The only problem would be if we have to heat treat a long bar, then the feed woul be low and the motor can suffer. But this machine is intended to heat camshafts so there's no need of continuous low feed. Is the motor encoder tied into the Delta VFD also? With most brands of > VFDs, in order to run in true "Vector mode", they need encoder feedback.. > > No, the encoder is only feeding the LinuxCNC pid loop. I didn't really dig too much on that aspect but I can check it on the manual. Now I'm only using the VFD to command the velocity of the motor. > Delta says the C2000 runs in FOC (Field oriented control) which I have > never heard of before. > Yes that's right but I'm not well informed about all that, I'm still on the learning curve. I was interested in this VFD because it was recomended for precise positioning and also because it can handle standar AC induction motors and also permanent magnet AC motors up to 5 kw. Also, it was 700$ on ebay with free shipping so it was really tempting. -- *Leonardo Marsaglia*. ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. Written by three acclaimed leaders in the field, this first edition is now available. Download your free book today! http://p.sf.net/sfu/13534_NeoTech _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
