Integrative Production Technology

Transcription

1 Cluster of Excellence Integrative Production Technology for High-Wage Countries Multi-Technology Machining Centre

2 Multi-Technology Machining Centre Introduction Rapid changes in global markets require high flexibility in production. However, the demands on the achievable product complexity and production profitability should not be reduced. Therefore, one focus for the design and selection of the necessary means of production and machinery lies on maximum productivity. In contrast, further focus is on the production of any complex components. These commonly contrary poles scale and scope are an essential part of the research within the Cluster of Excellence and can therefore be found in the mission statement, the polylemma of production technology. Practical Issues The project Development of Multi-Technology Platforms from the interdisciplinary cluster domain Integrated Technologies examines how various manufacturing technologies of traditional individual machines can be integrated into so-called Multi-Technology Platforms (MTP). In order to evaluate the success potential of an MTP, the comparison of an MTP and a concatenation of individual machine tools of the given production technologies can be performed. Important criteria for a distinction between MTPs and single machines are accuracy, lead times and idle times. Since in principal an MTP can perform several manufacturing processes in a single setup, the operator of an MTP can achieve higher accuracies and prevent waiting and setup times. Figure 2: Machine structure Figure 3: Decreasing costs per piece for small lots

3 Figure 4: Different laser based manufacturing technologies on a sample workpiece However, individual machines can also operate in parallel, and thus for a certain minimum number of pieces - at least theoretically - an occupancy rate of 100% can be achieved. The possibility of utilising all technologies integrated in an MTP in contrast decreases with an increasing number of integrated production technologies. Approach To make the benefits of MTP available and to be able to operate in an economically viable way, a promising solution is the integration of additional, simultaneously usable workspaces in the MTP. This approach has already been successfully used for single technology machine tools to reduce downtimes. To evaluate the technical possibilities and limitations of an MTP with multiple workspaces, as well as to evaluate its operation, such an MTP, the Multi- Technology Machining Centre was built up. The basic machine consists of the 5-axis milling centre Mill 2000 from CHIRON-WERKE GmbH & Co. KG, which already is equipped with a milling spindle and two equally and simultaneously usable rotary swivel tables. Within the project the machine has been extended with an industrial robot and two laser processing units, enabling the machine to perform several laser processes besides the main process of milling. One machining head allows wirebased cladding, hardening and material removal using a fibre laser. The second unit consists of a short-pulse laser and a scanner for laser structuring. For the execution of different laser processes and for the work piece handling the robot has been fully integrated into the machine structure and control. Through flexible combination strategies of the modules spindle, robot and both lasers with the two workspaces a high utilisation of all system components can be achieved. Bild 6: Übersicht der Arbeitsräume Figure 5: Motion axes of the robot Figure 6: Overview of workspaces

4 Technical Challenges One central issue during development for the mechanical construction, as well as for the control conception and commissioning was the integration of the industrial robot into the machine. The robot was placed mechanically on a platform between the two working spaces, which enabled it to reach both working spaces directly. The selected control concept is based on the idea to control both the robot and the spindle from the same numerical controller (NC). Axes values are generated for the robot and then sent to the robot controller for transformation and application. Due to the different signal propagation times between the NC and the robot controller, it is necessary to adjust the run times by using control extensions (NC kernel extensions). Figure 7: Machine and active laser protection housing Since the machine uses high power laser components, a sophisticated safety concept is necessary. As even the scattered reflections of laser radiation can already cause serious eye damage, the entire machine has been surrounded with a double-walled active protective enclosure. Damages to this enclosure immediately trigger an alarm which stops all machine resources. Due to the close integration of the described components, processes and mechanisms within a small space, interactions are to be expected. This can e. g. be the generation of vibrations from a milling process, the thermally caused displacement of the machine bed due to laser power, or heat accumulation due to the safety enclosure. Thus, another research focus is the investigation of these interactions on a mechanical, thermal and organisational level. Figure 8: Laser deposition welding (Laser off) Figure 9: Laser deposition welding (Laser on)

5 Figure 10: Laser deposition welding experiments Regarding the further development of the demonstrator the integration of additional tools and processes is planned for the near future. In particular a cooperative processing of robot and spindle for different processes such as handling operations or the robot-based deburring of components shall be achieved. Displacement Sensors X-Direction Y-Direction Z-Direction Figure 11: Measuring displacement with a laser tracker Figure 12: Investigation of thermal displacement

6 Technical Data Milling, drilling, laser deposition welding and laser structuring in a single machine Control of all components by a single NC controller All processes can be used in one clamping Two workspaces for optimal use of resources (parallel processing) Technical Equipment Hardware: Machines & components: Base machine: Chiron Mill axis milling centre Two identical workspaces, each with a swivel and rotary axis Spindle power: 25 kw Siemens 840D sl with own NCK extensions Robot: Kuka KR-16 6-axis industrial robot Payload: 16 kg Deposition welding laser Laser source vendor: IPG Laser scanner vendor: Arges Type: fiber laser Yb:YAG Power: 2.4 kw Welding head with scanner and media supply (Additional wire and shielding gas) Led by robot Structured laser Highly pulsed High-precision microstructuring / deburring Led by milling spindle Peripherals (chip conveyor, cooling and ventilation systems, hydraulics, etc.) Several camera and test computers Laser radiation protective enclosure Software: CAM-System Siemens PLM NX Extensions for simulation and laser cladding (self-developed) Laser control Lasernet Inscript Project Team Prof. Christian Brecher Frédéric du Bois-Reymond Wolfram Lohse Johannes Nittinger

7 Cluster of Excellence Integrative Production Technology for High-Wage Countries c/o Werkzeugmaschinenlabor WZL RWTH Aachen University Steinbachstraße 19 D Aachen Phone: +49 (0) Fax: +49 (0) Website: