Complete hydraulic system for punching and shearing applications DRIVE TECHNOLOGY Punching and shearing operations in the metal works industry require an extremely lean and robust drive system. To create an ideal system delivering large output forces yet providing significant energy savings and high machine availability requires the combination of expert engineering, hydraulics and detailed understanding of the application. The BWIL drive Voith combines all these expertises in a single unit. The company Voith Turbo H+L Hydraulic, a subsidiary of the Voith group, with its expertise in intelligent drive solutions has developed a new hydraulic drive system BWIL especially for punching and shearing applications that delivers forces upto 2,500 kN. Hydraulic drive systems for punching and shearing applications are compact, short-stroke valve cylinder units. The multi-pressure circuits and accumulator charging technology of the system make it highly energy efficient. Due to its compact design and modular construction, the system provides flexibility in its application. Hydraulic drive systems in roll form units are usually compact in design. To minimize the number of interfaces and ensure short cycle times, Voith has optimally synchronized the hydraulic power pack, control unit, actuator, control electronics and application software in the BWIL drive. The close connection between the machine and drive system provides operators with the benefit of high reliability and availability. According to respective machine requirements, proven components are combined in a modular structure. As a result, the BWILdrive requires a shorter development time and is available faster. The programmable high-performance drives are equipped with extremely simple and safe process control, consisting of hydrodynamic servo valves. These also facilitate complex forming processes and positioning tasks. Apart from the high quality of the produced parts, the BWIL drive also impresses with its performance data. The application-optimized electrohydraulic drive allows punching forces of up to 2,500 kN in pressing applications, with a cycle time of 400 ms and 20 mm stroke. In shearing applications, forces of 1,000 kN with 200 mm stroke and cycle times of up to 3 seconds are possible. Design and function The electrohydraulic servo drive BWIL is a free programmable high performance drive. The ram cylinder operates in the hydromechanical control loop and delivers high ram performance in punching or shearing operations and precision work during forming operations. HS4 is the electronic link between servo drive MDA Technologies 5/2016
BWIL and machine control PLC/CNC. The machine control communicates all the parameters, like stroke positions and speed, using the data interface. After the cycle has started, all management and monitoring of hydraulic actuators and sensors is done by HS4. A robust position feedback with digital interface is used to monitor the closed loop ram operation. In a compact design, all valves are placed on a manifold directly on the cylinder. This provides ease of installation and maintenance along with an improved hydraulic response. Principle of operation The servo motor specifies the set-point via a toothed belt drive to the control valve. In the control valve, the rotational movement is converted into linear motion and is amplified by the hydraulic cylinder many times. The actual position of the working piston is guided directly on these back through the mechanical connection between the hydraulic cylinder and control valve. Thus, the hydromechanical control loop is closed. When switched, the attached high holding valve will keep the cylinder and the mass attached to it in the starting position. Energy savings For driving the internal gear pump, Voith equips the unit with the latest IE3 motor technology. The delivery capacity of the pump is 2 × 125 litres. In combination with the accumulator charging technology and an additional three 50-liter accumulators, this delivery capacity is sufficient to realize even long dynamic strokes if necessary. The combination of Voith’s well-known accumulator charging systems and the highly efficient internal gear pump provides significant energy savings compared to conventional drives. Photographs: Voith GmbH www.voith.com About Voith Turbo H + L Hydraulic and Voith GmbH Voith Turbo H + L Hydraulic is a subsidiary of Voith Turbo. Voith Turbo, a Group Division of Voith GmbH, is a specialist for intelligent drive solutions. Customers from highly diverse industries such as oil and gas, energy, mining and mechanical engineering, ship technology, rail and commercial vehicles rely on advanced technologies from Voith Turbo. Voith sets standards in the markets for energy, oil & gas, paper, raw materials, transport & automotive. Founded in 1867, Voith employs more than 20,000 people, generates € 4.3 billion in sales, operates in over 60 countries around the world and is one of the largest family-owned companies in Europe.