A robot loads and unloads injection molding machines at Krumpholz

Plastics technology is still a relatively new area for Karl Krumpholz GmbH and Co. KG. It was originally founded in the Franconian town of Kronach in 1955 as a mold construction company, and in 1992 it acquired and integrated its own plastics technology unit. Whereas this enterprise had previously focused on supplying the electrical and toy industries, as well as on the manufacture of baby protection products, since the acquisition Krumpholz Plastics Technology has been specializing in the production of large-volume plastic parts for the automotive and commercial vehicle industries with its approximately 60 employees at the premises in Redwitz- Unterlangenstadt. Since the end of March 2013 Krumpholz has been producing various components for the plastic bumper system of a German commercial vehicle manufacturer with a 2,300 t injection molding machine made by Krauss-Maffei.

Starting point / Task definition:
Karl Krumpholz GmbH & Co. KG was looking for a solution that would allow the various plastic parts they produce with the machine not only to be handled but also to be quickly, easily and precisely processed following injection molding – within optimum cycle times. The requirements were clear: flexibility and reach.

Implementation / Solution:
Various molds are currently in use at the facility for the plastic bumper system. For the center part of the bumper bracket, the KUKA shelf-mounted robot first picks up the bushings from the feeding station with the aid of a gripper and moves to the waiting position between the machine tie-bars while the component is being produced in the injection molding machine. The machine opens and the robot inserts the bushings into the mold on the nozzle side. Then it turns its gripper 90 degrees in order to pick up the ejected plastic part. Once the robot has dynamically withdrawn from the machine, the sprue can be trimmed and the component can be shaped into various designs. The robot then places the part into a cooling device where the plastic parts are held in the correct position to prevent shrinkage. Furthermore, all common processes are integrated into the future-oriented facility, from the bushing magazine to the trimming process to flame-machining of the injection moldings. All subsequent steps needed to produce the plastic parts can also be performed by the KUKA shelf-mounted robot during non-productive machine time.

Video: KUKA automation solution for Karl Krumpholz.

System components:
KUKA brought the KR QUANTEC shelf-mounted robot onto the market especially for the requirements of the plastics industry. The weight has been reduced by up to 330 kg and axis 2 is located 400 mm further forward and lower down, making the KR QUANTEC K series an ideal partner for the injection molding machine.
Eleven types of robot finely incremented in terms of payload (90 – 270 kg) and reach (2,900 – 3,900 mm) enable use on injection molding machines with 1,000 to 4,000 t closing force. The KR QUANTEC series is provided with transmissions in all six axes; the maintenance intervals are an unparalleled 20,000 operating hours. The KR 120 R3900 ultra K model used has a reach of 3,900 mm and a payload of 120 kg. Thanks to its low height the six-axis robot only needs a small amount of headroom.

Results / Benefits:
Its low weight enables the shelf-mounted robot to achieve high dynamism and very low cycle times, shortened by up to 30 percent. The low robot weight also means that a simple, cost-effective base plate can be used, considerably contributing to the energy efficiency of the entire system.
The fourth-generation KUKA shelf-mounted robot sets standards in terms of flexibility, speed, reach and precision. The KUKA SafeOperation software allows the crane to move unimpeded across the production facility. Even if a large gripper is used on the robot, there is no risk of collision. Furthermore, the KUKA robot operates to the side of a necessary tie-bar pulling device in a space-saving manner.