Nearly unnoticed a kind of revolution took place in the automobile industry: Today´s cars do not have to be run in. Some formerly common noises are not audible anymore. This is a result of demands for longer durability of vehicles and has to do with precision. Precision, which results from the selection of the components of differential gears at the assembly stage of back axles for small trucks in the Austrian factory of Magna Powertrain. So adding up of the elemental manufacturing tolerances for single parts can be avoided. The result is the complete loss of formerly common functionality at the meshing of the different cogwheels. This increases the durability and reduces the risk of premature deterioration via percussions at load alternation.
Precision and selection
To obtain such a precision in the production process, exact measurements of the results of each fabrication step at the axle mounting as well as the permanent evaluation of the numerous results of measurement are necessary. Josef Gebeshuber, CEO of GTech automation engineering GmbH, says: “Quality as well as precision can not be added subsequently. Therefore measuring, selection and adaptation to the actual dimensions as an integrative basis is the very core of our production facility.”
The prioritization is reflected in the company´s history. Whereas most enterprises in machinery and plant engineering expand in electronics and software beginning with mechanics and drive system engineering, GTech does it the other way round: the company, founded in 1997, originally focused completely on information technology and so on software-programming. Soon switchgear manufacturing was added. After the company realized that the target quality of the complete facility can only be ensured when planning, production and mounting comes from a single source they became a comprehensive manufacturer of machinery and plant engineering in 2001. Due to more and more complex and lager projects they moved into the current factory premises in Ried/Austria in 2007. Today GTech is an international operating company with approx. 70 employees and a turnover of about 9 Mio. EUR.
Mechanics and Data Technology Parallel
„Each of our facilities are developed on the basis of a functional concept”, says the project manager responsible for the back axle facility Ing. Luis de la Cruz at Magna. “Based on this software, control engineering, drive system and measurement engineering can be developed collaterally. This reduces the development time and guarantees results which meet the requirements.” This is absolutely necessary considering the short time for the realization of the projects. So the order for the Magna project was placed only 2 months after the inquiry in Mai 2008 and the facility was built in February 2009. “The biggest challenge at this facility was the available space”, says Luis de la Cruz. “So we chose architecture with autonomous stations around a central turntable.” Together with the high metrological effort and the diversity of variants this caused a great increase in number and complexity of the software.
That is why GTech chose a decentralized setup of the hardware in the form of cross-linked spread intelligence via Ethernet. For this reason each of the 13 stations are equipped with its own CPU and so are largely autonomous. These 13 CPUs are connected with a host computer, which coordinates the complete facility, controls the communication between the single stations and the environment and manages the system data. “This enables a modular commissioning and even in case of changes it is only necessary to intervene into the affected parts,” says Josef Gebeshuber about the main advantages of the facility. “Troubleshooting, modifications or expansions only have to be tested in the respective subroutine and so it can be provided for the customer faster and safer.”
Further advantages are given by the operation of the CPUs in an Ethernet network under TCP/IP as a network protocol: The process data is exchanged completely transparent with the server in this application, which contains the central data base. GTech frequently implements plants with spread intelligence such that the single stations execute a direct data base reconciliation. Each of the stations is also directly reachable by teleservice. The technician responsible only has to take care of the affected subroutines.
GTech has been applying SPEED7 CPUs from VIPA since 2005. The reasons for this are that the CPUs which are compatible to Step7 have a better performance as comparable products of same size of competitors and also have the Ethernet coupler on board as standard. This enables cost and space saving for external modules.
Data Flood Determines CPU Type
One of the challenges of the Magna project is the flexible workflow of the robot operations in an extreme operation radius, which is completely made up of a single gripper to save time for reconnecting. There are also some challenges for the data technology during the measurement procedure, where nominal value and actual value are recorded and stored constantly. Even the smaller version VIPA 315-2AG12 is entirely sufficient to keep the cycle time within the range of 2 to 5 ms, despite the fact that in each applied CPU – besides the control of the processes – larger amounts of data are stored about product, advancements etc. and exchanged with the central CPU.
The central CPU VIPA 317-4NE12 was chosen, because this CPU has to communicate additionally within the control network, continuously with the measuring set and the assigned robot. Thereby the data transfer rate of 1,800 frames per second has to be managed. This means every 0.5 ms a data exchange is carried out.
„Besides the obvious advantages of a decentralized setup which the VIPA CPUs support, we are convinced about the cost-saving setup, which this product enables. Due to the outstanding architecture of the process chips less space is needed than for the comparably powerful products of the current market leader. And fewer applied modules means a reduction of possible source of errors at the same time,” says Luis de la Cruz. And Josef Gebeshuber adds: ”With a balanced combination of performance and easy, universal deployability VIPA CPUs support the combination of high precision and a complete production data technology. By means of this our customers are able to produce products for which they can guarantee a high durability.”
Author: Ing. Peter Kempter / x-technik