A miniature freeform bending machine with post-bending kinematics for process control

自由形式的折弯机可以通过可移动的折弯头（5或6个自由度）将管材和型材成型为3D几何形状。这种增量过程的挑战是无法检测或难以检测的干扰变量，例如由半成品中的材料不均匀性和焊缝、不均匀壁厚分布和变化的摩擦学条件引起的。这导致工件的弯曲段中的局部不确定性和偏差，并且由于杠杆效应，最终导致大的全局偏差。这些过程不确定性取决于半成品和待生产的几何形状，并且目前不可能在弯曲过程中以有针对性的方式对它们做出反应。现有技术是先验地确定自由形式弯曲的过程控制，并在此基础上调整弯曲头的控制。通常，对制造的部件进行测量，并在必要时在试错过程中调整过程控制。到目前为止，还不存在在考虑全局尺寸精度的情况下用于过程适配的当前实际状态的直接反馈。在研究项目的范围内，将研究基本的科学问题，即当前部件几何形状的稳健在线采集，所需弯曲后运动学的实施以及全局过程控制的相关建模。为此，将开发和建立一种新的制造系统，其中机器人运动系统或机构专门介入弯曲过程。在此过程中，运动学的末端效应器拾取零部件。运动学末端执行器上的光学测量系统和力-扭矩传感器直接在运行过程中确定当前与目标状态的偏差。折弯机的自由度和机器人运动学的相互作用现在能够实现部件的局部和全局控制的折弯。本项目将建立一个小型的研究演示装置，包括弯曲机和弯曲后运动学。该演示系统将被设计用于弯曲小金属型材（吸管大小）。在这个系统上开发的模型和方法应该是可扩展和可转移的。将过程、模型和方法转移到规模化的系统和过程将是后续项目的一个重要组成部分。

A free-form bending machine makes it possible to form tubes and profiles into 3D geometries by means of a moveable bending head (5 or 6 degrees of freedom). A challenge of this incremental process are disturbance variables that are not or only with difficulty detectable, caused e.g. by material inhomogeneities and weld seams in the semi-finished product, uneven wall thickness distribution and changing tribological conditions. This leads to local uncertainties and deviations in the bent segments of the workpiece and, due to the leverage effect, finally to large global deviations. These process uncertainties vary depending on the semi-finished product and the geometry to be produced, and it is currently not possible to react to them in a targeted manner during the bending process. The state of the art is to determine the process control of free-form bending a priori and to adjust the control of the bending head on this basis. Usually, the manufactured component is measured and the process control is adjusted in a trial-and-error process if necessary. A direct feedback of the current actual state for the process adaptation under consideration of the global dimensional accuracy does not exist so far. Within the scope of the research project, the fundamental scientific questions are to be investigated, i.e. a robust inline acquisition of the current component geometry, the implementation of a required post-bending kinematics as well as the associated modelling for a global process control.For this purpose, a new manufacturing system is to be developed and set up in which a robot kinematic system or mechanism intervenes specifically in the bending process. During the process, the end effector of the kinematics picks up the component. An optical measuring system and a force-torque sensor on the end effector of the kinematics determine the current deviation from the target state directly in the running process. The interaction of the degrees of freedom of the bending machine and the robot kinematics now enable a locally and globally controlled bending of the component. In this project, a small-scale research demonstrator is to be set up, consisting of a bending machine and post-bending kinematics. The demonstration system will be designed for the bending of small metal profiles (size of straws). The models and methods developed on this system should be scalable and transferable. The transfer of the process, the models and the methods to scaled systems and processes is to be an essential part of a follow-up project.