When filling up your vehicle, have you ever asked yourself how crude oil finds its way from the desert or oil rig to the gas station? Probably not. Actually, it is quite an exciting topic as our report on Voith shows.
Voith is a technology company with a global reach and has a broad portfolio of systems, products, services and digital applications. With energy, oil and gas, paper, raw materials and transport and automotive – Voith addresses five essential markets in every region around the globe.
Voith has locations in more than 60 countries around the globe, one of which their facility located in Crailsheim, Germany, wich was founded in 1956. Approximately 1000 employees develop and manufacture solutions for mobility and industry. The focus of the Industry Group based in Crailsheim is the production of variable-speed drives for oil and gas production – and this brings us a step closer to answering the question we asked at the beginning.
Hydrodynamic controllable planetary gears – extremely reliable even under challenging conditions
Oil and gas often have to be pumped under adverse conditions: the heat of desert regions, or cold weather and high humidity on offshore oil rigs. Approximately 14.3 billion liters of oil are pumped every day. A real challenge for pump and drive technology.
Voith Crailsheim plays an important role here with its VoreconNX product line, a multi-circuit controllable coupling with hydrodynamically controllable planetary gear for power ratings exceeding 50 MW and speeds exceeding 20,000 rpm. Reliable mechanics are combined here with hydrodynamic power transmission.
The average operating time between non-scheduled downtimes (MTBF) is 48 years for this type of equipment.
Faster fabrication of components weighing tons
The right kind of production technology is required to
manufacture rugged products such as these. Production at Voith in Crailsheim is based on 27 top-of-the line CNC
milling and turning machines. For decades now, Voith has relied on Sinumerik control technology for its
machine fleet. Production Head Karl Augustin remembers the 880 and 840C systems very well. Today, most machines are equipped with Sinumerik 840D sl. This also applies to the machine from Waldrich Coburg, a MasterTec 3500 AT, which Voith purchased four years ago. Impressive: Workpieces weighing up to 20 tons can be loaded on to each of the two machining tables of the gantry milling machine (coupled: 40 tons)
The VoreconNX enclosures are also machined here. The machine hall is climate-controlled to rule out any changes so the components or the machine as a result of temperature fluctuations. The Vorecon cast enclosures weighing up to 18 tons have to be machined on several sides, either as individual parts or as an assembly. To facilitate this, the portal gantry machine is equipped with four interchangeable heads.
During operation, the machine kinematics can be modified by fitting a complete milling head so that surfaces and drill holes can be machined at the component in almost any situation.
Software minimizes spindle center offset for tool changes
The requirements placed on the interchangeable heads are extreme. The spindle units have a mechanical spindle center offset of less than 0.02 mm. The maximum geometrical error between two tools must not exceed 0.005 mm. This demands maximum precision when processing the various machine parameters in the CNC. The Siemens VCR-Rotary software package reduces the spindle center offset to less than 0.01 mm.
The interchangeable spindle units are mounted and removed fully automatically. This is implemented by switching over the motor data sets. Machine builder Waldrich Coburg generated these motor data sets during the commissioning phase.
Swivel cycle as key technology
Dietmar Danzer from the Voith NC programming department is very enthusiastic about the Cycle 800 swivel cycle. This makes it easier for him to program all the swivel operations on the component. Machine operator Jürgen Höll then implements these programs at the machine. As an experienced CNC technician, he is familiar with products from other CNC manufacturers, and is convinced that Voith has found the best possible solution with Sinumerik 840D sl. Operation, for instance when selecting the tools and programs, is easy to understand.
The option of recompiling the cycles into the programs supplied by production planning is yet another feature that he finds very useful. This means that subsequent corrections can be directly entered at the control system without the risk of entering incorrect parameters.
Cast parts with fluctuating dimensions
The maximum batch size for this machine is three. Semi-finished products in the form of cast parts are used as the basis. However, machining individual pockets, fits and drilling patterns has to match customer specifications. For programming specialist Dietmar Danzer, Sinumerik 840D sl is the perfect solution for this level of variance.
The dimensions of the cast parts show production-related tolerances. Any variant can be essentially pre-designed, based on macros using the parameter programming and powerful high-level language commands in the NC program. Starting from the (initially unknown) unmachined dimensions of the castings, standard machining and measuring techniques (drilling, milling, boring with bridge dies, thread cutting/milling and measuring using probes) are implemented in the program. The post processor outputs a “standard” DIN/ISO program and the programs developed by Danzer take into account the continually varying upper/lower tolerances without having to change the main program.
To achieve this, each part is directly measured at the machine before and during the process. Voith uses Renishaw measuring probes and powerful Sinumerik probing cycles. Dietmar Danzer is enthusiastic about being able to log the results of this online measurement directly in the control system. He can read out these logs from the control and use them as quality verification for customers.
Virtual machines reduce production times and training needs
ITo further optimize the time between order intake and order dispatch, experiments are currently under way with a digital twin of the machine based on Siemens NX and the virtual NC kernel (VNCK). In the future, this means that production planning will be uncoupled even more from machine operation, thus saving valuable time.
This can be achieved because the virtual machine and the control behave exactly like the real physical machine during the machining processes. While another part is being machined, the user can already run in the next part virtually, including a collision check. In this way, NC programs are already optimized in advance.
A positive spin-off of having a virtual machine is familiarizing and training new personnel. The virtual machine can be used for testing and training without having to use the real CNC machine.
Future focus for training
Voith is gearing up for the future and training its up-and-coming technicians itself.
This year, there are 61 trainees embarking on careers as industrial mechanical engineers, mechatronic specialists and technical product designers and on dual-study careers as machine builders and mechatronic service engineers. For its CNC training courses, Voith uses a classroom equipped with SinuTrain training software and the practical exercises are carried out on machines equipped with Sinumerik.