Cox MHP, a manufacturer of automated equipment including bag-filling and closing machinery, recently encountered a customer whose bag material was especially challenging. The bags are made of a porous material that makes it virtually impossible for vacuum devices to pick and place them so that they can be fed to filling and bag-sewing stations on the Cox machine. Clamps, grippers, hooks, and a variety of other devices failed. An especially dusty environment didn’t make bag handling any easier.
The dust is caused by the granular product being filled. However, Cox could not divulge what the product is or the customer’s name. As Cox sought a solution to its customer’s vexing problem, it received a sales call from a Bosch Rexroth representative. “He was here for something else and asked what projects we had going on, and we showed him this application,” says Brian Harvey, engineering manager for Cox MHP. “He said he could help out, and we later purchased the first Noncontact Transfer (NCT) unit. Time was getting tight on the project,” Harvey adds.
Cox employs three NCTs on the indexing machine used by the customer with the dusty product. The disk-shaped devices measure about 3?4” deep. Bosch sells them in 20-, 40-, and 60-mm sizes, with lift capacities up to 2 lb. For this application, Cox uses two of the 40-mm units and one 60-mm-diameter device.
The two 40-mm devices are positioned side by side on a mounting plate on an actuator near the beginning of the indexing machine. “There are mounting holes on the back of them and we connect plastic tubing from an air compressor to the NCTs,” says Harvey. The two NCTs at this location move along an XY axis. They travel about 1’ down to pick up the bag and ascend again. Next they travel horizontally for a little less than 2’, releasing the bag to the third NCT. This 60-mm NCT “holds” the bag in place so that other devices on the Cox machine can take the bag into bag filling and sewing stations.
The 4”x8” empty bags, which weigh but ounces, are stacked in magazines. As the two NCTs move to pick up the top bag in the magazine, they do so without contacting the porous bag. This makes the process unique.
According to Bosch Rexroth, the NCTs operate by the Bernoulli principle (see diagram), which applies airflow under the device to create a vacuum and lift force between the center and the circumference. Because of the dynamic vacuum and continuous flow, the lifted object does not attach to the NCT surface, thus enabling the handling of delicate items.
The unit presents a bag every five seconds to the main portion of the indexing machine.
“We shipped the machine to our customer in September, and the customer has been running in full production with it since about October,” says Harvey. “It’s a one-of-a-kind machine, and the customer has been very happy with it.”
