The customer is a well-known German manufacturer of Gugelhupf baking molds. The baking molds, consist of a deep-drawn body and an inner conical tube, both of which are joined together by a fold in a forming tool, thus forming the baking mold.
Up to now, the production was realized in a partially automated process, in which circular sheet metal blanks were automatically fed to a hydraulic press and deep-drawn by means of a deep-drawing tool. The deep-drawn body was removed from the die by a gripper and fed to a second hydraulic press with a loaded cutting die, which performed the edge trimming on the formed sheet body. Another gripper removed the trimmed deep-drawn body from the second press and fed it to a third hydraulic press by means of a conveyor line. An employee at the third press then manually inserted the conical tube and the deep-drawn body into the folding tool. The press was then released manually and, after the stroke, the conical tube was connected to the deep-drawing body and the edges of the baking mold were rolled in. The finished baking mold could then be removed manually by the employee.
The entire process from loading the first press, to removal by the operator at the third press, had a cycle time of 16 seconds. The rolled and folded conical tube had to be inserted into the folding tool in exactly the right position by hand, as the bulging fold would otherwise get stuck in the tool during the joining process of the thermoformed body and the conical tube. If such a serious malfunction occurred, the complete die had to be removed from the press and freed from the stuck component. This malfunction lasted about 45 minutes until the production line was running again and could produce.
Due to increasing quantities and the resulting delivery pressure, the customer decided to implement a fully automatic press line without manual intervention.
The customer’s specification was a cycle time of 7 seconds and the fully automatic joining of thermoformed body and conical tube over a total of 8 different baking mold variants.
B+R GmbH solved the concept as follows:
Set-up of three new hydraulic presses in a line of different press force. The stacked sheet blanks are removed from the blank magazine by a vacuum suction system and fed to the first press for the deep drawing operation. After the stroke of the press, a pneumatic linear axis system with vacuum suction removes the deep-drawn die body from the die of the first press and feeds it to the die of the second press. In the second press, the deep-drawn mold body is trimmed. There, after the stroke has been completed, a 3D-printed special vacuum gripper removes the trimmed thermoformed body and places it in a centering station. A gripper system specially developed by B+R GmbH removes the centered thermoformed body and positions it at an angle of approx. 10°. The preformed and folded conical tube is removed from a magazine stack located in a bypass by means of a 6-axis robot with gripper system. Since the position of the fold on the conical tube is arbitrary due to the pre-process, the gripped conical tube is rotated past a non-contact sensor and the exact position of the fold on the tube is determined by the control system. With this information, the conical tube is placed in a cup in the joining station and joined to the thermoformed body. A step gripper removes the two joined components and places them in the folding die of the third press by means of a pneumatic linear axis. After the press has lifted, the finished Gugelhupf baking mold is removed from the die by means of another gripper system, fed to a conveyor line and discharged from the fully automatic press line.
After completion of the fully automatic press line, the customer was able to produce large quantities of Gugelhupf baking molds in 7-second cycles without any malfunctions.