Assembly in Action: Flexible Workcell Installs Pump Covers
January 1, 2007
Grundfos Group (Bjerringbro, Denmark) manufactures approximately 10 million pumps annually at factories in Europe, Asia, South America and the United States. Its product line also includes electric motors and high-tech pump-control systems. Since its founding in 1945, the company has remained dedicated to continually upgrading its products and production processes to improve the bottom line.
At its pump assembly plant in Sunderland, England, Grundfos recently installed a flexible, semiautomated workstation to attach pump covers to two different pump housings. The design specs call for using four screws in each assembly, but with different torque values depending on the model. The system is built around a manual workstation framework from DEPRAG Inc. (U.S. Headquarters: Lewisville, TX). Features include a base frame with Makrolon safety doors; a sliding part fixture; horizontal and vertical clamping cylinders equipped with sensors to verify positioning; four EC-Screwdriver spindles; four depth controls; an OPTO-Touch start button; a DEPRAG LC172 screwdriving controller; and a TP2plus display panel.
On the shop floor, the workstation is one of a number of stations that have been set up in a flexible setting for final assembly of the pumps. At the pump cover station, an operator first loads a pump housing into the part fixture. The operator then places the cover over the pump housing and inserts four screws, which are started manually with a half turn. Once the components are in place, the operator pushes the sliding part fixture into the machine until it dead-ends on a stopper, then presses the OPTO-Touch button, which closes the safety doors and initiates the screwdriving process.
Using a lift-locate station, the system moves the pump under the screwdriving system where a horizontal clamping cylinder locates and locks the pump in position to avoid any movement during screwdriving. The LC-Controller, which is programmed to accommodate both pump styles, instructs the horizontal clamping cylinder exactly how to grip the housing while this is taking place.
Once the housing is in place, the EC-Spindles move down to engage the screws, and the depth control system verifies that each spindle is positioned on top of the required screw location. To align the cover, the machine first tightens the screws to a torque of 22.1 in.-lbs. It then performs a second tightening to a final torque of 57.5 in.-lbs. The user interface tells the operator if the tightening functions were all performed correctly.
Once the screwdriving is complete, the EC-Spindles retract, the clamping cylinder releases, the safety doors open, and the operator removes the completed pump and places it back on a conveyor, which carries the pump to the next station.
For more on screwdriving and automated assembly, call 800-433-7724 or visit www.depragusa.com.