reference report on gear hobbing at zf ... - Artis MARPOSS

Reference Report Gear hobbing Version 4-2013_web
REFERENCE REPORT ON GEAR HOBBING AT ZF SAARBRÜCKEN ON
LIEBHERR GEAR-CUTTING MACHINES
NEW FEATURES FOR THE GEAR HOBBING FUNCTION IMPROVE
PROCESS MONITORING AND OPTIMIZE THE TOOL SERVICE LIFE
In contrast to processes where absolute information such as "tool
breakage" or "missing tool" is sufficient, gear hobbing requires
continuous monitoring, which reliably ensures to keep the wear of the tool
strictly within the specified tolerances. For optimizing such hobbing
processes, ARTIS has developed a new feature for the monitoring function
gear hobbing. It is already successfully in operation at ZF in Saarbrücken
in the production of high-quality automatic gearboxes. All ARTIS products
are exclusively marketed by the MARPOSS Group of which it is a member
company.
In their works at Saarbrücken, ZF Friedrichshafen AG develops
and manufactures 6- and 8-speed automatic gearboxes for
medium and upper class cars. The 8-speed automatic gearbox
8HP consists of four sets of planetary gears and five shift
elements with a total of 20 to 25 gearwheels. With an annual
production of 1.9 million gearboxes in 2012, the gear cutting
machines are in continuous operation – and reliable processes
are required.
Reliable gear hobbing processes with ARTIS
The ARTIS process monitoring utilizes the measured torque of
the milling spindle to obtain information about the condition of
the tool. The torque curve is "taught" once and compared with
the actual machining process. To monitor breakage, the signal
intensity is used. The product from power and time is visualized
as area below the signal curve, from which the condition of the
tool can be determined. The function of gear hobbing fully
automatically records the wear without intervention of the
machine operator "in full section" or in the range of the largest
cutting forces respectively. Gear hobbing is one of several
methods that can be selected for the process monitoring system
CTM from ARTIS. It has been especially conceived for the
requirements and characteristics of gear hobbing and has been
in use worldwide since 2009.
The new ZF-automatic transmission
generation is based on a completely new
transmission concept with four planetary
gear sets and five shift elements.
Photo: ZF
Optimization with ARTIS
Savings in the cost of tools can add up to five-figure sums
within a few months. ARTIS continually works on new
developments that, amongst other benefits, could reduce the
machining times in gear hobbing in relation to the load.
The function Gear hobbing of the tool and
process monitoring system CTM from
ARTIS offers a method which is ideally
tailored to the characteristics of the
process.
A detailed list of addresses can be found under:
www.marposs.com
ARTIS GmbH • Sellhorner Weg 28-30 • 29646 Bispingen-Behringen • Tel +49 (0) 51 94 9 50-0 • info@artis.marposs.com • www.artis.de

Reference Report Gear hobbing Version 4-2013_web
Liebherr-Verzahntechnik
The Liebherr gear-cutting machines, Type LC, belong to the
machine park for producing gearboxes at ZF in Saarbrücken. In
addition to the production machines for the automobile industry,
the portfolio of Liebherr-Verzahntechnik also includes universal
machines for large workpieces and special machines for fine
machining. For the process monitoring on milling machines, the
machine manufacturer already has already used ARTIS
systems for many years. The gear hobbing function is of
particular interest for machine types
which machine workpieces with a diameter of up to 500 mm. Dr.
Oliver Winkel is head of the area of application technology /
technology development for gear milling at Liebherr-
Verzahntechnik. His conclusion: "The CTM system from ARTIS
assists our customers to ensure the daily number of units of
gearwheels required and, simultaneously, protects the valuable
milling tools and machines. A breakage not only means
unplanned tool costs and rejects, but also downtimes in the
production and, in the worst case, costly damage to the gear
hobbing machines. Briefly, the customer can reliably deploy the
capabilities of the machine and tool."
At Liebherr-Verzahntechnik, the monitoring system CTM V5 is
utilized, signal transmission is carried out without a sensor, via
digital performance data (DTA, Digital Torque Adapter) that is
directly exported from the controller via a Profibus connection.
Up to the present, the new features for gear hobbing have been
successfully utilized on Liebherr milling machines with Siemens
840D SL controllers. The system also functions on older
machines with Siemens 840D PL or other controllers. There is
also an option for analog measurement of the effective power.
The tooth wheels for the automatic
transmissions are manufactured on these
gear cutting machines LC120 from
Liebherr. Photo: Liebherr-Verzahntechnik
Safe milling processes and an optimized tool
utilization – supported by ARTIS process
monitoring. Photo: Liebherr-Verzahntechnik
A detailed list of addresses can be found under:
www.marposs.com
ARTIS GmbH • Sellhorner Weg 28-30 • 29646 Bispingen-Behringen • Tel +49 (0) 51 94 9 50-0 • info@artis.marposs.com • www.artis.de