Assembly in Action: Car Seat Fittings Benefit From Robots
Lanz Industrietechnik AG (Wolfwil, Switzerland) specializes in metal extruding and joining techniques, such as welding, riveting and extrusion joining. The company uses conveyors and robots from Bosch Rexroth AG (Lohr am Main, Germany) to assemble car seat fittings. Car seat fittings are comprised of various sheet metal parts bent into shape.
The new assembly system edges different plain bearings and bracket bearings. Another station inserts rubber sleeves onto levers. Control stations for quality assurance are also incorporated into the system.
The assembly line has to meet extremely demanding requirements. The preassembled bent parts only allow for a minimum tolerance limit, which is especially critical when inserting the rubber sleeves. The joint position can only deviate by a maximum of 4 millimeters. Each seat has a left and a right hinge. The hinges vary depending on their position in relation to the outside or inside of the vehicle.
The seat fitting process begins and ends with manually loading and unloading the workpieces. Two manual workstations are used for this purpose. At one of the stations, the metal hinge pieces are loaded onto the workpiece pallet. The second station is located at the end of the line where the assembled fittings are taken off the pallet for final visual inspection. The cells at the process and testing stations consist of edging presses, test and measurement equipment, and two SCARA robots for inserting work.
All the process and test stations, as well as the manual workcells are linked by a TS 2plus conveyor. There are two conveyors for carrying right and left seat fittings. In the middle of the circular assembly line, there is space for both pallets to remain in the system. While one pallet is operating, the other pallet is waiting. The change from right to left hinges can be performed quickly without rearranging the system.
Two SR6 Turboscara robots guide other individual parts in the system. In the first robotic cell, the separated plain and bracket bearings, which are stored in conveyor containers, are inserted into the correct positions on the workpiece. These positions have different X, Y and Z directions, depending on the type of hinge. The second robot fills an insertion machine with rubber sleeves that have been lubricated with a slip additive. The robots’ grippers can accommodate the four different types of fittings.
The PC-based robot controls produced by Bosch Rexroth are the basis of the entire seat fitting assembly process. This robot control communicates with the second control (the slave) over standard transmission control protocol and Internet protocol. The conveyors, rivet press stations, and the test and measurement equipment are all controlled by the integrated SoftSPS. The standard pneumatic cylinders are operated via VTS 02 valve block systems with bus modules for electrical control. The valve blocks are connected to the master control over the serial field bus. This also applies to the BT5 interfaces that help simplify system handling and operating.
The modularity of the equipment reduces construction time and costs. Modifications for customer-specific applications can be introduced quickly and cost-effectively. The assembly line can also be adapted to future product and process changes.
For more information on robots and conveyors, call 800-322-6724 or visit www.boschrexroth-us.com.