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Flexible and Energy Efficient Operation with Servo Drives

Technical papers

retrofitting of automatic punching presses

Customers who decide on a completely overhauled automatic punching press by Nidec SYS benefit twice over: Purchasing a used machine is not only cost-saving, the automatic punching presses also work more energy-efficient thanks to the changeover to servo motors. In addition, the individual drives are flexibly controlled, which enables faster production processes. Servo amplifiers by SIEB & MEYER AG make a high-dynamic operation of the servo motors possible, thus contributing significantly to the success of the overhauled machines.

The company Nidec SYS specializing in the automation and optimization of punching and forming processes offers customers system solutions from a single source – from planning to implementation. There is a second business area, though, in which the company with headquarters in Grafenau in the Bavarian Forest (Germany) applies its know-how: buying and selling used automatic punching presses of the brand BRUDERER. These machines are retrofitted by skilled personnel at the facilities in Grafenau. In addition, the company modernizes automatic punching presses on behalf of customers: The service includes removal and transport of the press as well as initial operation including customer trainings on site.

Completely modernized with state-of-the-art technology

"We always have a selection of used automatic punching presses by BRUDERER available for our customers," says Wolfgang Biewald, CEO at Nidec SYS. The experts specialize in different models from the 70s to the 90s, from the small construction type BSTA 25 to the large type BSTA 160. Depending on the model these machines are used for punching everyday objects such as spoons or electrical switches but also automotive parts. "Basically everything that is made of metal and produced in series. The professionally retrofitted machines run almost es well as current models. However, the customer can save up to 40 percent on the purchase price."

During retrofitting of the automatic punching presses the saying 'not one stone will be left upon another' applies: Within about ten weeks the presses are disassembled, mechanically repaired, equipped with modern electrical drives as well as a new control system, sanded and repainted. "No old electrical components remain in the machine. Cables, buttons, safety switches and the like are replaced without exception," Wolfgang Biewald explains. "The same applies to wear parts, of course, such as seals, bearings and foils."

Less power consumption, more flexible control

The BRUDERER automatic punching presses of the respective series were already equipped with electric drive systems. Therefore the changeover to modern servo motors does not make the striking improvement that is reached when hydraulic systems are replaced. Nevertheless, the energy efficiency can be increased: "The new machines consume up to 2 or 3 percent less power by comparison," says Wolfgang Biewald. "At first glance this may not seem much, but with continuous operation the savings add up to a considerable sum over the years."

The second major benefit of servo drives is their superior controllability: The old machines were equipped with one AC motor each, which served as center drive. Auxiliary drives of e.g. feed axes or pumps were controlled mechanically via gears. After retrofitting each function unit of the machine is assigned to a separately controllable servo motor. This way the user can control parameters like strokes or speed flexibly and individually. The outcome is not only a faster setup of the machine but also a higher efficiency during production: If you set speeds individually, for example, smaller parts can be fed faster to the machine and therefore idle time is reduced. "The used automatic punching presses are controlled by our inhouse-developed press control system PCS-100," says Wolfgang Biewald. "It is possible to integrate additional functions into PCS-100, such as an AC servo coil feed system, tool protection or a stacking control."

A compact and cost-effective drive package

"It is no secret that servo-driven systems are on the rise in many applications," says Ralph Sawallisch, key account manager drive technology at SIEB & MEYER. "The advantages include a more flexible process design and the opportunity to implement a more accurate process monitoring and documentation." Servo amplifiers by SIEB & MEYER enable the required high-dynamic operation of servo motors. In addition, the devices provide application-specific interfaces and functions that make the development of the according system easier.

For the retrofitted automatic punching presses Nidec SYS uses mostly servo amplifiers of the type SD2, less frequently the type SD2S. "Each axis of an automatic punching press has its own servo amplifier," Ralph Sawallisch explains. "The SD2 series is designed as multi axis system. When several axes are moved, the central power supply module PS2 supplies all the connected SD2 drive amplifiers. Compared to devices with individual power supply units, this saves a considerable amount of energy." Since Nidec SYS retrofits automatic punching presses of various construction types, the experts exhaust the whole 'vendor's tray' of the SD2 series devices: All in all, SIEB & MEYER supplies almost 30 different device variants with output powers from 1.5 kW to 80 kW.


A cooperation at eye level

Since the company was founded in 1994, Nidec SYS has been cooperating with SIEB & MEYER, the specialist for control and drive technology based in Lueneburg, Germany. "It is a cooperation at eye level that is based on trust and becomes ever closer over the years," Wolfgang Biewald explains. "Beside the quick availability and the good price-performance ratio, we especially value the expertise of the development team. Together we have found an individual solution for every problem that came up." Satisfied partners, satisfied customers: In the end, users benefit of the combined know-how of both companies – also and especially with the 'new old' automatic punching presses.