Series 831 mechanical expansion chuck

Vorwald series 831 mechanical expansion chuck

The Vorwald series 831 expansion chuck is suitable for unwinding and rewinding machines, whereby the required clamping force is achieved by axial displacement of the expansion chuck support. The core presses against the core stop collar of the expansion chuck, causing the expansion lugs to expand centrically. The fixed centring nose prevents premature expansion of the expansion chuck. Two types of expansion lug are available to cover all requirements: longitudinally grooved steel expansion lugs and polyurethane expansion lugs with smooth surfaces. The customer’s requirements determine how many expansion lugs there are inside the “mantle” and where these lugs are placed. The longitudinally grooved and hardened surface of the steel lugs allows maximum possible torque transmission when using cardboard cores. In the case of steel, aluminium and plastic cores, this same force transmission is enabled by the smooth surface of the polyurethane lugs. All expansion lugs are equipped with a leg spring to ensure slide-back into the mantle. This makes it easy to slide the material cores on and off. Expansion chucks with expansion lugs are available for cores with internal diameters ranging from 50 to 500 mm.

The functional principle relies on the use of an inclined plane. The axial force pulls the expansion lugs outwards on the cone like on a wedge. The cone and expansion lugs have the same bevel. This creates a radial movement from an axial one. This arrangement provides the expansion chuck with a very large clamping force. Another very important advantage of this arrangement is that the clamping of the cores is perfectly centred, as all expansion lugs expand evenly. This enables very high winding speeds to be achieved. The mantles can be made from a large number of materials with various wall thicknesses – depending on the
customer’s application. The expansion chucks are based on the Vorwald standard and are custom-made using a modular concept.

Options

• Various expansion lug surfaces, tailored to the respective core material
• Flange or bearing shaft according to customer requirements
• Quick adjustment to different core diameters using adapters
• Special dimensions are available on request

Benefits

• High torque transmission
• Radial run-out accuracy: +/- 0.1 mm
• Quick clamping and unclamping
• No additional medium required for expansion, e.g. compressed air