Gearmotors lift pallet output

Friday, September 15, 2000

With the goal of increasing throughput by 20%, Zygot Automation Inc. (Englewood, CO) developed a patented concept for its ZA series palletizers. The units concurrently gather cartons, bags, or boxes into rows; form layers; and strip the layers onto a pallet. However, the faster cycle times necessary exceeded existing drive technology which consists of two-speed motors, pneumatic brakes, and vector and servo drives.

By switching to gearmotors and brake motors from Mannesmann Dematic (Cleveland, OH), engineers achieved better drive system response times, yielded greater machine throughputs, and provided simpler controls and less maintenance.

"We faced some tough challenges in trying to decrease cycle times and reduce maintenance when designing the ZA-50 and its smaller sister units, the ZA-30 and ZA-20 palletizers," explains Zygot President Youssef Hennes. "For example, the response time of the two-speed motors we were using was so poor that on smaller machines with a short travel requirement, we had to eliminate the high-speed segment and traverse on slow speed only. Obviously, this slowed down the operation. Servo controls turned out to be too expensive. The sophisticated vector drives we tried required clean power, which was a real headache because we had to isolate the palletizer from 'noise' with line reactors and shielding to achieve reliable operation. Another nagging problem was the high incidence of motor-brake housings working loose due to vibration."

Mannesmann Dematic Conical Rotor Brake Motors (type KB) and Cylindrical Rotor Motors with and without brake (type Z, ZB) eliminated all these headaches, according to Hennes. Simple PLC-controlled contactors operate the new motors and brakes. Integral brake mechanisms eliminate components such as a separate brake disk and lining, clamping device, coil, and rectifier. Moreover, the gearmotors allowed Zygot engineers to upgrade from worm gears to more efficient and reliable helical gearing.

"Since we have eliminated vector drives in our ZA-50, our customers are happy that the drive systems are less expensive, more rugged, require much less maintenance, and are simpler to troubleshoot. We are currently investigating the elimination of servo drives in other equipment applications with the Demag Cylindrical Rotor Motors."

For more information about Demag Gearmotors from Mannesmann Dematic go to http://www.dematic-us.com.