Machine Design: Innovative Drive Combines Best of Hydraulic, Electric Technologies

Rexroth teamed up with Berlin-based BEKUM Maschinenfabriken GmbH to develop a hybrid drive for the closing system of blow molding machines. The drive not only meets dynamic axis requirements, but also the need for fast, stroke-independent buildup of force at closure and contemporary (low) energy consumption and noise levels.

The innovative hybrid drive leverages the benefits of hydraulic and electric drives to maintain applied forces over extended periods and gently buffer fast changes in direction. It is also efficient, precise, and minimizes noise emissions. To develop this system, which does without a classic hydraulic setup with tank and displacer unit, both partners had to break new ground.

A hydraulic gearbox was fitted between the electric drive and linear axis for the closing system of blow molding machines and is used to convert rotary to linear movement and provide for targeted switching between rapid and power strokes. This considerably reduces the loads for the drive side and the ball screw drive. A locking function in the hydraulic gearbox enables the closing force to be held without drive torque, similar to a classic hydraulic machine.

Internal tests and initial field applications confirm the everyday suitability of the new development.

The hybrid drive can also be used for closing systems involving other applications, such as presses and injection molding machines. This innovative, customized solution is just one example of the many years of experience Rexroth has gained as an engineering partner in development projects.

Bosch Rexroth AG is one of the world’s leading specialists in the field of drive and control technologies. Under the Rexroth brand name, the company supplies more than 500,000 customers with tailored solutions for driving, controlling and moving. Bosch Rexroth is a partner for Mobile Applications, Machinery Applications and Engineering, Factory Automation and Renewable Energies. The company provides customized solutions tailored to the needs and specifications of each individual market. As The Drive & Control Company, Bosch Rexroth develops, produces and sells components and systems in more than 80 countries. As part of the Bosch Group, Bosch Rexroth and its 38,400 associates generated approximately 6.4 billion euros in revenue in 2011.