VT 4-4 Vertical Turning Machine: Top efficiency rating in large volume gearbox production
15/08/2014 - Oliver Hagenlocher
The market is growing and competition intensifies. According to a study by Roland-Berger, this is how future prospects of the suppliers to the automotive industry can be summarised. The study further concludes that a market growth rate of approximately 6 percent within the next two years is achievable. However, the supply industry is facing increased competition from new players on the emerging markets. What can be done to counteract this? First and foremost, a closer look at the profitability of production sites might help. Component production must become faster, deliver greater precision and show a greater degree of economic viability. What the relevant production solutions should be like, becomes apparent with a closer look at the new vertical turning machine VT 4-4 developed by the turning specialists at EMAG. This machine delivers top efficiency levels in large volume gearbox production.
For a number of reasons, the production of drive and gear shafts represents a very specific key task in the manufacture of automobiles. For one, many of their components are of a very detailed and highly complex geometry, on which so much depends. For instance, high-precision gearings ensure a highly effective torque transmission within the gearbox, whilst high-precision shoulders and grooves guarantee the safe connectivity of components. The efficiency of the powertrain as a whole depends to a large degree on the functionality of their shafts. And these highly complex components must be produced in their millions – quickly and at the greatest precision. On completion of the central turning work the shaft should ideally display a geometry that is as close to its final contour as possible. The tolerances production planners are looking for in this respect are in the micrometre range.
How can these high-performance requirements be reconciled? The turning specialists at EMAG have been focusing on this particular question for decades. The machine builder’s development team creates tailor-made, highly innovative manufacturing solutions for the production of shaft-type components. Their vertical, 4-axis shaft turning machine VT 4-4 in particular follows this tradition. It opens up new potentials in the machining of components of a maximum length of 1,050 mm and a maximum diameter of 200 mm:
• Simultaneous: Machining is carried out in 4 axes at a maximum speed of 4,500 rpm. The process employs two turrets with twelve tool stations each, equipped with turning tools or driven tools (with one station reserved for the gripper).
• Automated: Workpiece grippers move the raw-parts to the machining area and remove the finished components, i.e. whilst one gripper inserts a new raw-part into the machine, the other gripper removes the finished component from it.
A reduction in unit costs is guaranteed
“This principle offers a great step up in performance in the production of shafts – especially in an environment that deals with large component volumes“, explains Dr Guido Hegener, Managing Director of EMAG Maschinenfabrik GmbH. “Owing to the fast workpiece changeovers and the powerful machining in four axes cycle times are very short. In combination a simple automation system, this ensures that the unit costs are kept to a minimum. This is of great benefit to the user.“ In its standard execution, the machine is equipped with two space-saving, recirculating conveyors that accommodate up to 28 raw-parts and 28 finished components respectively. Transfer and turnover units or robots ensure that a number of VT machines can be linked up cost-effectively and with great ease.
Focusing on component quality
Of particular importance to the development engineers at EMAG is the quality of the components produced. For this purpose, the machine base is made of the polymer concrete MINERALIT®. It carries all technology modules: the powerful workspindle, the turrets and the tailstock. Its rigid, vibration resistant construction guarantees an equally vibration resistant turning process that guarantees high-quality surfaces and highly accurate geometries. EMAG’s typical vertical alignment of the workpiece also guarantees constant process integrity, as the unhindered chip flow it offers prevents the accumulation of chips in the machining area.
“Last, but by no means least, we have also attached great importance to the ease of operation of these machines“, emphasises Guido Hegener. “After all, the human factor is a very important one when it comes to productivity. We want to make it as simple as possible for the operator.” To achieve this, all relevant components – from electrics to hydraulics and including the cooling system – are very easy to access, with the user interface being of an intuitive, clearly laid out design.
A wide range of possibilities
All in all, the VT 4-4 opens up a wide range of possibilities for the production planner in gearbox manufacturing. Use of the machine is made even more economical by its compact design, with the vertical alignment taking up very little space. There is also no necessity for additional automation, as this already forms part of the machine.
Short cycle times, a high degree of flexibility and a small footprint... What to the experts think of the chances of success for their new machine concept? “We are extremely optimistic”, declares Guido Hegener. “With its very attractive price-performance ratio the VT4-4 ingeniously complements our vertical shaft turning programme. It is the reason why we believe our chances in the marketplace to be excellent.”
|Workpiece diameter, max.||mm||200|
|Workpiece length, max.||mm||1,050|
|Travel in X||mm||395|
|Travel in Z||mm||1,230|
|Power rating main spindle |
at 40% / 100% duty cycle
|kW||38 / 29|
at 40% / 100% duty cycle
|Nm||250 / 200|
|Turret – tool positions||Qty.||2 x 12 (1 gripper)|
|Rapid traverse speed in X/Z||m/min||30 / 30|
|Speed of driven tools||Rpm||9,600|
|Torque of driven tools|
at 30% / 100% duty cycle
|Nm||56 / 33|