Machine tools are commonly used in industrial production and machining of materials. CNC machine tools are capable of forming metal parts with micrometer accuracy. However, this accuracy is not needed everywhere. Using robots would be significantly cheaper.
A machine tool usually costs more than 100 thousand euros, while a robot costs 2-3 times less. Therefore, scientists are looking at the possibility of replacing machine tools with industrial robots, if the application allows it. in which it gathered the possible applications of the robots, their technological approaches and the limitations of their application, as well as the related experience. For the publication “Robots in Machining” published in the journal of the International Academy of Manufacturing Technology, CIRP, the group considered about 400 studies. The publication shows the different approaches available to make robots suitable for new machining tasks with higher process forces
Robots are not only cheaper. When used, a larger work area is also available. In addition to machining, they are also capable of performing handling tasks. The use of robots is of particular interest in the production of small quantities of high-precision goods
Control technology can compensate for errors
A “normal” an industrial robot, for example, is optimized to perform a spot welding task. However, in applications requiring higher process forces (e.g. milling), the flexibility of the joints leads to unacceptable inaccuracies and therefore metal parts cannot be machined with sufficient accuracy. “There are several approaches to improving the accuracy of robots. This is possible by properly programming the robot: The nominal trajectories of the robot’s motion are generated to compensate for errors due to the robot’s flexibility. In addition, redundant degrees of freedom the remaining residual error can be learned and taken into account for the next run, “explained Professor Verl on the University of Stuttgart’s news site.
” However, the robot’s flexibility is highly nonlinear and asymmetric, which means that the tensile or compressive load it is not the same and therefore not easy to calculate.It does not matter, for example, the spatial direction of the milling process and whether milling takes place downwards or upwards.It is not easy or even possible to program the robot to compensate for inaccuracies. One of the things we try to do in our institute is to create a digital twin deviations of the robot from the nominal trajectory. With this model, we determine the behavior of the robot so that we can incorporate it into the tolerances accordingly, “the research leader explained.
Robots create light structures
robots are suitable for tasks such as removing cut edges (deburring) or sanding off rust.The robots can be used virtually anywhere where milling accuracy is not required.This is often the case for materials such as wood, foam, concrete and marble.This makes the robots interesting in architecture and in the manufacture of lightweight structures.
They are used to make components for pavilions made of wood or carbon fiber, etc. These parts must fit exactly, but not in the micrometer range but in the millimeter range. No two parts are the same, everything is cut out individually by the programmed robot.
Construction is the new field of application
If the application possibilities of robots are further optimized, one a properly programmed robot can produce parts at the touch of a button. Verl believes that in the future, in addition to the automotive and electronics industries, the construction industry will also be a new area of application. “Some of the technologies are already being used to build prefabricated houses. We will be able to do much more in ten years. Our long-term vision is to print the shells of buildings and houses,” Alexander Verl pointed out about the future of robots.
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