w Heavy workpieces – safe clamping, precision machining The live centre is an important element in a load system of a heavy-duty machine tool and plays a decisive role in the final machining result. The BRUCKNER design is especially suited to the high requirements of heavy-duty machining. The maximum admissible load depends on the mounting taper diameter and we therefore offer a choice of two different designs: Load carried only on the taper Load carried on the taper with additional tailstock-sleeve support The formula is applicable when the workpiece weight FW is equally divided between headstock and tailstock. If the component has an irregular shape, the weight has to be split up correspondingly. The radial cutting force FS has to be either a positive or negative figure, depending on the direction of rotation. Any unbalance of the workpiece has to be allowed for with the centrifugal force FF. Load capacity of live centres for heavy-duty machining The data for workpiece weight and load given in our tables and diagrams are based on the dynamic state of the live centre. Taper and centrepoint cross sections are designed for actual operating criteria and not for static conditions. The load figures are calculated for the average diameter of the 60° angle. The radial load measured on the clamping diameter of workpiece and centrepoint is relevant. The load can be determined by the following approximation formula: FR = ± FS + FF FW 2 FR – radial load FW – workpiece weight FS – Radial cutting forces FF – centrifugal force 1 2 3 4 ▼ ▼ High Performance Live Centres for heavy-duty machining High concentricity accuracy Shaft seal ring protects the bearings from dirt and coolant Housing high quality material, forged, therefore uniform grain structure, tensile strength approx. 1000 N/mm2 Head and shank hardened Large zero clearance precision roller bearings to absorb radial and axial forces. No bearings in the taper shank. Bearing seats in the housing and on the centre spindle are precision ground to ultra fine tolerances. The bearings and their seats are selected for optimum fit. Maintenance-free due to permanent lubrication Safety spigot (patented) acts as an additional safeguard when connecting the centre housing to the support ring 5 Housing Safety spigot Tailstock sleeve Support ring 1 2 3 4 5 48
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