BCH makes connection with Lenze

26 March 2009

BCH, a food machinery specialist, has turned to Lenze to help it meet strict cleaning requirements on its Micro Extrusion Line, designed to handle small runs of extruded liquorice. Cleaning demands mean the connection between the drive gearbox and rotary heat exchanger has to be regularly stripped down, which is where the Lenze ETP-Express locking bush comes into play.

The bush offers single screw operation and creates a connection that can be quickly and easily disassembled for cleaning.

Heating of the raw materials is done in a scraped surface called a Viscotator, which is effectively a heated tube with an internal shaft and blades. The raw materials pass through the tube under pumped pressure and their temperature increases by about 100 per cent. The Viscotator is driven by a Lenze helical bevel geared motor, chosen to accept the high axial loads from the pumped ingredients. In operation it is necessary to disconnect the Viscotator shaft from the gearbox for cleaning, at least every two weeks. BCH rejected keyway and spline solutions. Keyways were felt to be liable to wear over time, causing them to jam. Splines were expensive to machine and require a non-standard gearbox incurring extra cost and a long lead time.

BCH says the ETP-Express locking bush was its ‘ideal solution’. It consists of a double-walled hardened steel sleeve filled with a pressure medium and a flange. The flange contains a radically mounted pressure screw and piston. The bush sits between the Viscotator shaft and the gearbox hollow shaft. When the single screw is tightened, the walls of the bush expand and create a friction connection that transmits both the torque and the axial force. As well as making a simple and compact assembly without the cost of thrust bearings, the ETP bush gives real benefit when disassembly is needed for cleaning. Loosening the single screw gives full and fast release of the Viscotator shaft with no tendency to stick or jam.

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