However, manual work is still required when feeding the cylindrical blanks with a length of up to 120 millimetres. This is because some special spring variants are used that cannot be fed automatically due to their complex output symmetry. The system can therefore be loaded in two different ways. This applies both to loading the raw parts and to collecting the finished bent springs.

Cylindrical blanks, which are quite simply shaped, are fed into the work cell via a magazine shaft. There are 300 pieces per pack. The worker places very complex parts manually on a pegboard. This holds 48 pieces at a time. The Fanuc robot, which is equipped with a quadruple gripper, operates from the magazine shaft or pegboard. Even with the gripper arm extended to a length of 700 millimetres, it can still lift a weight of seven kilograms. It uses the first gripper to pick up the springs from the magazine or from the pegboard in order to insert them into the center of the press's two-stage forming tool. Due to the upstream processing steps, however, the parts can be of different lengths. Initial image processing therefore checks the position and length of the springs in order to calculate any offset required for the gripper position. The measured value is transmitted to the robot, which uses this data to correct its position independently in the hundredths of a millimeter range.

The springs are bent three times in succession until they have the right shape. The other three grippers are used for this, with the blank moving upwards step by step in the forming tool of the press. A second camera was installed in the press. This checks whether the spring to be bent has been correctly inserted into the die. This prevents faults in the production process from the outset. Should a fault occur, the system would stop automatically and alert the worker. He can usually rectify the fault in a few simple steps. The finished bent springs go into three different ejection chutes: one for the parts that are OK, a second for those that are not OK and the third for the statistical process control (SPC). The worker can request any component at will from the running production operation in order to check it. If the quality does not meet the requirements, he intervenes in the production process to correct it.

Alternatively, the robot places the finished bent springs, which are deemed to be in order, in rack drawers. The system stacks up to ten such drawers, each filled with 48 springs, on top of each other in a lift system. The operator can call up the status at any time via the control panel to see which magazine is already fully loaded. He then removes this manually from the lift. The MPA242226 automation cell was equipped with a Siemens S7 PLC controller and a second-generation mobile panel, the MOP277. sw