Automatic tailstock assembly for Hermle machining centres

To allow single-hit, 4/5-axis prismatic machining of long, thin workpieces that need to be supported at both ends to achieve the required accuracy, German machining centre manufacturer, Hermle, has introduced an optional tailstock assembly. It clamps onto the trunnion of the company’s C 30 U and C 40 U vertical machining centres, alongside the 360-degree rotary table.

Sole UK agent, Kingsbury Machine Tools, says that turbine blades, medical parts, cutting tools and tool holders are typical examples of components up to a maximum length of 420 mm whose manufacture is speeded and simplified with this arrangement.

Unusual is the facility to position the tailstock automatically in two axes under NC command. In a single cycle and without manual intervention, it allows precise, all-round machining on four sides of a part held between centres, followed by machining on the fifth side (unclamped end) after automatic removal of the rotating centre.

This is achieved by retracting it using the 220 mm stroke of twin linear slides on which the centre moves, and then swivelling the slide assembly downwards through 90 degrees to allow the cutter to access the end of the component. In the latter mode, normal 5-axis simultaneous machining or 5-sided machining can be performed on shorter, self-supporting billets, castings or forgings.

In conjunction with Hermle’s HS 30 robotic handling system for loading and unloading workpieces automatically, long periods of unattended operation are achievable, irrespective of whether 5-axis machining, 4-axis machining with tailstock, or a combination of the two is required.

Features of the C 30 U and C 40 U vertical machining centres include Heidenhain iTNC 530 or Siemens S 840 D CNC system, three staggered Y-axis guideways for stability, ± 115 degree swivelling of the trunnion, and a mineral casting bed that promotes vibration-free machining, particularly as the bearings for the trunnion are set directly into cast holes in the sides of the bed.