Volkswagen’s massive Wolfsburg manufacturing plant in Germany has installed a TwinServo Technology press blanking line from Schuler with a production capacity of 33,000 blanks a day, replacing three older machines.
The automobile manufacturer uses it to cut sheets of steel for its entire plant, which are later formed into engine hoods, doors or roofs. The line has replaced three older machines.
The new “Route 20”, as it is known internally, produces around 33,000 blanks a day. This represents an increase in production capacity of 25 percent. In a performance test at the start of August, the system actually produced 52,000 blanks within 24 hours – and there were ten setups during this time.
Thanks to the high availability of the press blanking line, the setup can be performed in less than ten minutes (“Single Minute Exchange of Die”, SMED). The compact design of the 800 ton TwinServo press at the heart of the line reduces the footprint by around 30 percent, and the moving bolsters and dies are easier for operators to access.
With fully automatic coil loading, including cutting and moving in, the strip can also be replaced in no time at all. The high-precision straightener prepares the material before the highly dynamic roll feed guides it with a maximum speed of over 200 metres a minute into the blanking press. The sensitive blanks are then de-stacked using the “Stop2Drop” process. The state of the entire line can be permanently monitored during this time by means of Condition Monitoring.
Other Automotive Users
The TwinServo Technology (TST) was unveiled in 2012. In the meantime, several companies have decided for the further development of Schuler’s ServoDirect Technology (SDT), which has established itself on the market – like automotive supplier Fischer & Kaufmann (Fiuka), who improves both product quality and die life with a TwinServo press.
“We already have a number of presses from Schuler and Müller Weingarten in operation,” said Site Manager Tobias Heutger. “The quality and performance are always exactly right for us.”
With the new TwinServo press, Fiuka now has the most modern line available on the market. “We are generally open for new technologies,” says Heutger. “Ultimately though it was the price-performance ratio which was decisive. Compared to our conventional presses, we can more than double the number of strokes per minute from a maximum of 16 to 34 now.”
TwinServo Technology features two decentralized servo motors in the press bed. This new design makes it possible to combine properties and characteristics which used to be regarded as contradictory. The result: benefits for the user which cannot be achieved with conventional press designs.
In a traditional press, the slide is pushed downward – thus closing the die and generating the press force. The resulting reaction force has to be absorbed by the press frame. Due to restrictions caused by part transport considerations, presses are often designed in two parts clamped together by tie rods. The force is then distributed over the entire press frame and the pre-tensioned tie rods.
As the force application points of the slide are located further toward the edge,
this opens up new possibilities for part production.
In the TST design, the slide is no longer pushed downward but pulled downward. This makes the force flow much more direct and thus reduces deflection by around 30 percent. Favourable leverage effects with force application points toward the outer edges result in geometrically enhanced conditions and off-centre force applications. This improves tilting resistance by up to 400 percent compared to conventional machines.
A further decisive benefit: as the force application points on the slide are located further toward the edge, the entire clamping surface can now be used: This means one can achieve both greater eccentricities as well as greater eccentric loads in absolute terms — which are particularly important for multi-station presses.
In addition to the rigid construction of the press, slide tilting can also be actively influenced during strong eccentric loads by regulating the two electronically linked drives of the TwinServo press. This also results in shorter try-out times and reduced die wear.
With the same useful space as a conventional machine, the external dimensions are much more compact. As a consequence, the press has a smaller footprint and also fits in halls with lower ceilings. Although the drive has been integrated into the press bed, the foundation dimensions and underfloor space requirements have not increased, and accessibility for service and maintenance remains good.
Drive Parts Separated
Since the oil-lubricated drive parts are separated by seals,
the press work area is largely oil-free.
The oil-lubricated drive parts in the press bed are separated by seals from the press work area. As a result, the work area can be said to be largely oil-free. This also prevents the formation of the dreaded oil mist – which sooner or later precipitates as an oil drop in the work area.
The compact design of the TST means it can be completely enclosed by sound insulation. As this sound enclosure stands freely and is not connected to any machine parts, there is no transmission of structure-borne sound. Compared to conventional presses, noise emissions are reduced by around 15 decibels – corresponding to a halving of noise pollution for employees.
The stated benefits are further enhanced by the possibilities offered by modern servo drive technology. Such drives enable the user to actively influence the speed of the forming process. In combination with various operating modes, such as full stroke or pendular stroke, users can achieve significant output gains over presses operated with flywheels.
In September, Schuler launched a technology centre for forming technology systems featuring a TwinServo press with an innovation day.
The demonstration and reference centre in the Northern China industrial metropolis of Tianjin offers automotive manufacturers, suppliers and other companies from the sheet metal-processing sector the opportunity to try out a servo press from the latest generation for themselves.
The Servo TechCenter Tianjin is Schuler’s first demonstration centre across all of Asia and forms a key part of the company’s strategy, to be ranked among the leading providers in China, as the largest press market in the world, in all the key price-performance sectors.
APMEN Cutting Tools, Dec 2016