indirect & direct ball screw efficiency


Thread Starter

Roni Robinzon

I was searching the net for information on gear (lead screws, worm gear) efficiency matematical modeling. I need it for the evaluation of a closed loop algorithm, using simulink. It wasn't difficult to write the dynamic equation of a lead screw, input torque, and the movment of the nut. The problem strats when a linear, one direction, disturbance force acts on the nut. Then if u want to define all the forcess acting on the motor,the subject of direct and indirect efficiency of the lead screw arises. Have u any information I can use on the above? thanks, roni

Guy H. Looney

Roni, I think you're making this a little more complicated than necessary. As opposed to giving you a bunch of information & formulas that may be irrelevant, could you give me a little more information about what your application is? FYI, typical efficiencies for a lead screws & worm gears are about 30%. Let me know if you'd like to discuss this further. Regards, Guy Guy H. Looney Motion Control Engineer A.C.E. Systems, LLC 170 Medearis Drive Old Hickory, TN 37138 email: [email protected] website: work: (615) 754-2378 fax: (425) 944-5017 cell: (615) 330-0044
Roni, There are ballscrews, leadscrews, Acme screws, and worm gears. The ballscrews are the most efficient with efficiences well into the 90's. The manufacturers can tell you. Acme screws are much worse as there is a lot of friction to deal with. Again, the vendors can tell you. Worm gears are a study in themselves. We have information that Cone Operations out of Traverse City, Michigan, sent us. The big problem with worm gears is that they are difficult to back drive when the ratio exceeds 15. At low speeds with a ratio of 15, the back driving efficiency is about 50%. Best servo performance requires back driving, especially for stiffness. Again, contact your vendor and he should have this info. If you don't have luck with your vendors, I'll try to spend some time digging out some of this info when I can. Tom Bullock [email protected]