Automation and Control, Robotics

WITTMANN robot functions for maximum efficiency One criterion to measure the efficiency of an injection molding machine is the number of molded parts produced per time unit. Consequently, the stoppages of the processing machine must be reduced as much as possible to achieve maximum efficiency. Robots influence the efficiency by the time taken for parts removal, the mold open time. WITTMANN robots equipped with R8 and R9 control systems have some special functions as standard, which substantially shorten the removal time. It is clear that a robot should reduce as much as possible the time it takes to remove injection-molded parts. However, programming such time-optimized processes is not always so simple. Especially users with little or no experience can quickly reach their limits when it comes to laying down the most efficient sequence of program steps. WITTMANN is aware of this problem and offers effective tools to solve it. The WITTMANN robot control systems R8 and R9 provide the command SmartRemoval IN as a prerequisite for every highly efficient parts removal process. This command is based on a process of machine signal analysis patented by WITTMANN. It calculates the relationship between the time taken by the injection molding machine to open the mold and the traveling and acceleration characteristics of the robot. This functions automatically in the background without operator intervention. SmartRemoval IN thus offers the advantage that the robot already starts to accelerate its vertical axis before the moving mold half has reached its end position. In this way, several valuable tenths of a second can be saved, since the acceleration phase takes relatively long compared to the distance to be covered. By having the accelerated movement carried out parallel to mold opening, any negative effect resulting from the robot’s inertia can be eliminated. In combination with an early command release (e.g. the release for ejector movement), total time savings of about 30% can be achieved. To facilitate the operation of SmartRemoval, the command sequence is visualized to the operator by a simple chart. SmartRemoval IN demonstrates its strength by automatic selection of the optimal travel sequence adapted to each individual application in producing a great variety of parts. Mold opening synchronization is available as standard for every WITTMANN robot which is fully integrated in the machine’s control system. In the case of molded parts with deep cavities (such as waste bins or flower pots with filling volumes of more than 20 l), this function can provide a major savings potential. For here it is already possible to pull out the parts while the mold opening movement is still in progress. In this way, the connection between the gripper and the part can be established earlier. This enables savings in terms of the injection molding machine‘s opening stroke as well as in mold open time. Regardless of the type of travel attributes selected, programming the demolding sequence with SmartRemoval OUT is always possible. SmartRemoval OUT functions in combination with an early “close mold” command release and is based on effective response to signals. This includes the choice of optimal timing when the signal to release the “close mold” command is given. SmartRemoval OUT offers the possibility to transmit this command to the injection molding machine before the mold protection sensor is reached. This eliminates delays in signal transmission. The injection molding machine starts the Display of SmartRemoval OUT on the screen of the R8 robot control system