Gear skiving according to the Liebherr concept has proved itself. Specialists from Kempten, Ettlingen, and Collegno offer competences from a single source in a full-service package.
"For successful gear skiving, users need more than just a good machine," said Dr.-Ing. Oliver Winkel, head of application technology. "With Skiving3, we not only sell the LK 300 or 500 but a whole process. The customer presents a gear, and we supply a machine, tools, and technology for its production."
The holistic approach from Liebherr has already been tried and tested in practice. For many customers, the process of skiving is new, and therefore the operators of the machines need comprehensive training and assistance. On top of that, the tool design is a complex issue.
"We have organized our division of labor very well," Winkel said. "In Kempten, we calculate the tools which are then designed and manufactured in Ettlingen, or in Collegno, in Italy. We have the entire process under control for both cylindrical and conical tools."
Skiving machines have to endure a lot
The gear skiving machines LK 300 and 500 are based on the tried-and-tested components of the corresponding large hobbing machines. However, process-related modifications were essential. For instance, the entire machine had to be more rigid and equipped with extremely powerful spindles. A gear skiving machine requires a table with a direct drive owing to the high workpiece speeds required. This drive works with an automatic control that constantly has the optimal parameters. The clamping fixture, which links the workpiece and the machine, is extremely complex and is designed by Liebherr.
As skiving is a highly dynamic process, the machine is practically supplied on a "turnkey" basis with individual clamping fixtures for each workpiece, precise rigidity, and contour accuracy.
"This overall view is an important part for the production success," said Siegfried Schmidt, team leader in development and design of skiving. "A complex process such as skiving has many specific obstacles, which we overcome with very specific mathematical solutions."
The newly developed LHGe@rTec control system also contains the mathematical formulas for pressure angle corrections. This way, quality improvements can be easily achieved via the kinematics of the machine.
Simple integration in production
The optional tool changer, which can be used to change between roughing and finishing tools, for example, is new. Liebherr offers a ringloader as a standard option for the workpiece changing device; other automation solutions, such as belts and robots, can also be realized upon request.
Skiving3 is popular especially for internal gearing with medium size and quantity as it is much faster than shaping and more economical than broaching. In situations where gear skiving is not possible or appropriate, owing to interfering contours or quantities that are too low, Liebherr still offers technological alternatives with gear shaping and gear hobbing.
Machines overview
- LK 300/500 features include:
- Maximum module: 5.
- Maximum gearing diameter: 300/500 mm.
- Maximum workpiece outside diameter: 500/600 mm.
- Maximum tool diameter: 250 mm.
- Maximum tool speed: 2,700 rpm.
- Maximum spindle output: 32 kW.
