Application of the Month
Gearheads For High Cycle Applications
July, 2014 - View all Application Examples
With the surging development of cost effective computing, initially starting over 2 decades ago, there was widespread predictions that paper records would go the way of the dinosaurs. As most everyone knows, it hasn't worked out that way.
Actually, it's very possible that the use of paper, for many applications, has actually increased. With the acceleration in computer power, more reports, for a variety of information, are able to be generated. And, now that almost every household has a personal computer with a desktop printer, the demand for printer and copier paper continues to grow.
Typical machine designs for the making and wrapping of reams of paper included a lot of cams and cam boxes. Cutting, slicing, stacking, adjusting, wrapping, and delivery involved a lot of continuous, intermittent, and reciprocating motion. Most of these elements were mechanically linked and driven by a primary power source. Cams transmitted the rotary motion into the synchronized intermittent motion required to perform all the operations. While the concept worked, it was a complex design and limited in speed.
With the continuing development of servo motor motion control profiles, a manufacturer of paper reams decided it was time to eliminate all the mechanical timing linkages. They planned to integrate servo motors and gearheads to provide independent direct drive to all the operations. But, it wasn't as easy as some may think.
While many servo motors were up to the task, the gearhead was another story. The operation required up to 150 start/stop cycles per minute. This type of dynamic application would probably destroy most gearheads. Proper torque calculations were critical and a design that could hold up to the constant pounding was a necessity.
When our customer approached us with this challenge, we knew that the Servofoxx servo gearhead was the appropriate choice. They needed inline and right angle designs, both of which were available to satisfy this tough application.
The Servofoxx provided several features that made it's use possible. Low backlash was a must, to keep the reciprocating motion on target. The precision gearing kept transmission error to a minimum. The dual support planet shafts optimized bearing load sharing, and the widely spaced output bearings provided the radial capacity required.
The motor input assembly, which includes a flexible coupling, was a crucial element in guaranteeing maximum torque transmission and reduced gear wear. Many gearhead designs, which have a fixed motor connection, lock the sun gear in place. Inherent misalignments assure uneven load sharing between the planet gears. With a flexible motor connection, the sun gear is allowed the micro movements necessary to guarantee perfect load sharing. This is important, especially in highly dynamic applications, to reduce wear, noise, and increase efficiency.
For the right angle models, ground spiral bevel gears were incorporated. The precision bevels shared the loads over more of their tooth surface, drastically reducing wear and increasing shock capacity.
Most servo gearheads utilize aluminum mounting plates and bearing housings. With highly dynamic reciprocating motion, bolt holes and contact surfaces can wear rapidly, causing lost motion and lubrication leakage. With an all cast iron construction, the Servofoxx was able to provide the superior torsional rigidity required.
There are many other types of applications, other than paper converting, that have high cycles. These include any machine that has high feed rates, such as bottling, packaging, part processing, metal converting, and others. When high cycles are present, peak torques are more prevalent, putting extra demands on mechanical components. But, when properly applied, many mechanical components can stand up to the challenge. It's picking the right product for the job that determines success or failure. While there are many servo gearheads on the market, few were appropriate for this application.
Director of Marketing
Did you know that DieQua publishes a monthly email newsletter that features interesting articles just like this one?
Our newsletter was designed to be a little different than other manufacturer's newsletters that are primarily product centric. While products and services available from DieQua are highlighted, other elements revolve around the personal and professional development of the design engineer.
To receive this newsletter, please visit the registration page and fill out your information.