Flexible Machining with Liebherr

Liebherr offers a comprehensive solution for complete machining by integrating a tool changing system and a chamfering device. Additionally, the company offers turning, drilling and gear cutting functions of the latest generation of Siemens controls.

The ability to completely machine a workpiece with a gear cutting machine requires the following:

1. Flexible programming which enables a combination of gear cutting processes with turning, drilling or hobbing operations.
2. A tool changing system which accelerates the workflow over various sub-processes.
3. Automated tool check and workflow correction.
4. An intelligent distribution of primary and secondary processes.

Flexible Programming

With the programming system LHGearTec and the new control panel LHStation, Liebherr offers a comprehensive operating concept which enables users to define gears with optimum efficiency and precision. When combined with the Siemens programming system programGUIDE, further contours can be programmed. Bores, slots, levelings, engravings and threads become a standard.

Tool-Changing System

The Liebherr tool changing system can be used in various ways. Firstly, it makes the process more flexible and efficient. It can incorporate different gear cutting tools, even those specifically intended for roughing and finishing processes. This means that more expensive tools are only used where they are necessary, thus saving money and extending tool life.

Secondly, sister tools can also be accommodated to increase productivity. The remaining magazine stations utilize up to twelve tools, enabling you to perform additional operations such as drilling, hobbing or turning in the same clamping fixture used for gear cutting processes.

“This enables us to achieve maximum flexibility at the same time as maximum precision, because the reference surfaces remain the same through all the machining steps,” said Dr. Peter Pruschek, head of electrical design and machine control development. “For specific application cases, this removes the need for an upstream turning machine or a downstream machining center.”

Deburring

Flexible chamfering is a major topic for precision gears for e-mobility. However, comprehensive technological solutions enabling flexible chamfering are increasingly in demand for collision-critical gears such as in the aerospace industry, as well.

“Deburring gears is now pretty much the norm”, says Dr. Gerd Kotthoff, head of technology gear cutting. “However, many customers are now also demanding pre-defined chamfers on the front sides. That’s why, with ChamferCut and FlexChamfer, we offer the option of integrated chamfering units which deburr a second workpiece during the machining process, so that no time is lost.”

Like the tool changing system, the chamfering device reduces the intralogistics to other machining processes and saves setup time. In the case of the new FlexChamfer unit, simple shank milling tools can be used here as well, replacing special deburring tools. “This enables us to obtain stable processes with optimum accuracy and minimal tool costs," he added.

Quality Control

For extremely precise manufacturing, continuous quality control is indispensable. At Liebherr, the customer can select a number of different methods for this. While the gear cutting machines themselves perform a gear check on the basis of a measuring probe, complete measurement can also be carried out on a separate gear inspection machine. This is connected to the control system by the network. If errors should occur, the overall system can optimally support the user and can also activate corrections itself, depending on the configuration.

“Until now, we have always spoken of a closed loop,” Pruschek explained. “However, with the LHOpenConnect service portfolio, we can go beyond the closed loop to connect both our own products and measuring systems and control station solutions by other manufacturers, via open interfaces. Measuring data only constitute a small part of the process data which we connect and use to optimize the entire process.”

Flexible And Accurate

Gear cutting in combination with chamfering, additional machining options, tool changing system in a closed quality loop:

LHGearTec with Siemens programGUIDE: Flexible programming of complete machining processes

FlexChamfer and ChamferCut: Very high quality deburring and chamfering during the machining process

Tool changing system: Roughing and finishing, sister tools for longer tool life and unsupervised manufacturing, and additional machining such as turning, drilling or hobbing using a hollow shank taper

Gear check: Measuring during the machining process with the possibility of correction

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