Reduce cycle time with robot path planning

If robot movement is perfectly matched to the injection moulding machine, this reduces the cycle time by up to 10% in very many applications. Since linear robots usually move from point to point, these individual points or the path must be determined manually by the operator in order to define the optimum travel paths.

Optimised path planning is already implemented in the iQ motion control feature for ENGEL viper robots. The linear robot calculates its path independently, which means that far fewer parameters need to be set or positions taught. The reduction of the cycle time is best achieved by an early start function of the robot, combined with a better planned motion path.

In order to plan the robot movement during entry so that it reaches the removal position exactly when the mould reaches the mould opening position, the parameters set by the user, such as positions and linear distances as well as the movement of the mould, must be taken into account on the one hand, and the robot-specific limit values for speed, acceleration and jerk on the other. In order to be able to determine an optimal robot movement during the entry process, the following 3 steps are necessary:

• Determining the optimum robot trajectory duration

  Based on the last cycle, the time span from reaching the set early start position to the mould opening is measured. This time span tF,opt corresponds to the trajectory duration of the robot so that robot and mould reach their end positions at the same time.
  
  

• Calculate the shortest possible robot trajectory

  With the help of the robot-specific kinematic limits of the individual axes and the linear distance defined by the operator, a robot trajectory can be calculated. The trajectory duration is the shortest possible trajectory duration that can be achieved under consideration of the given boundary conditions.
  
  

• Scaling the robotics trajectory

  When the early start function is activated, make sure that the trajectory duration of the robot movement tR,opt is greater than or equal to the determined optimal duration. If this is the case anyway, then it is not possible for the robot to reach the target position with the mould in time due to its limits. If, however, tR,opt<tF,opt applies, the robot would hit the mould. To avoid this, the trajectory is scaled so that the condition tR,opt=tF,opt is fulfilled.

Regardless of the injection moulding machine type and the type of removal, injection moulders benefit even with simple handling tasks. The efficiency gain is particularly clear in applications with large mould opening strokes, such as the production of deep housing components, boxes or containers that require long mould cores. iQ motion control can be used for both vertical and - for tie-bar-less machines - horizontal demoulding. In addition, a variant for longitudinal mounting is also available.