K 2013: Wittmann creates 3D inspection for round IML containers

An “all-wheel” drive concept will allow the creation of four inmold labeled 300-ml cups in a 4.5-second cycle at K for Wittmann Battenfeld (hall 10, booth A04). In this process, both cog belt wheels of the horizontal axis are synchronized and driven by dynamic drive systems, allowing acceleration rates of up to 110 m/sec with extremely low power consumption.
The 4-cavity line is based on a Wittmann Battenfeld TM Xpress 210 injection molding machine; the mold and the W837 automation equipment also come from Wittmann. The robot’s operation time amounts to less than 0.7 sec. Labels are presented to the robot by a tilted four-fold dispenser, with the individual dispenser compartment’s filling level monitored by a level switch. Whenever a stack gets too low, operators are alerted via a light and can refill the labels without interrupting the automatic process.
The insertion and removal gripper is mounted on the horizontal axis. The rigid frame structure of the extension arm with a servo-driven insertion stroke ensures accurate label positioning in the cavity with simultaneous removal of the finished parts. The labels are taken over by dummy cores and precisely wrapped. The loading zones of the dummy cores are made of nonporous material to ensure that they remain free of wear and are easy to clean. Electrostatic charge is used to hold the labels in a fixed position inside the mold.
The servo-driven stacking axis with integrated horizontal stroke and pivoting axis takes finished parts and places them on a conveyor belt. The IML unit is completed with a mold height adjustment device to adjust the complete line, a protective housing complying with European safety standards and the Wittmann CNC8.2 control system. The line on display at the K 2013 is a basic system extended by a quality inspection module and a stacking module.

3D high-speed inspection station
Continuous quality inspection occurs at a separate inspection station. Parts are deposited on a transport track to pass through individually. In this setup, parts must be presented to the cameras in precisely the same position every time. For rectangular containers, this presents no problem, but with rotationally symmetrical parts, “pseudo defects” can occur. In order to solve this problem, Wittmann said it has created a 3D high-speed inspection station for checking IML decorations, calling it a world’s first.
Four high-resolution cameras are installed around the conveyor belt, which take pictures of every single product transported on the belt. The software evaluates the from all four cameras and produces a 3D model of every part. The result of the inspection is now decided by this specific 3D model. “Less sophisticated image processing methods cause shadows and blurring, which make it more difficult to read bar codes and data matrix symbols; small defects are not detected whenever they happen to lie below the ‘seams’ between individual pictures,” Wittmann noted. In its new advance, the software “breaks down” the 3D model created in each case and transmits the resulting image file to the extensive tool library of the image processing program for examination. The software is now able to check and compare all aspects of a product, starting from the ID codes right down to the label patterns, including colors at a rate of more than 500 parts per minute.