Off Axis Grinding Machine
Workpiece orientation in general dictates the machine concept. In this case, it should be mounted much as it will be in service, in a way that enables rapid set up and to enable coolant and grinding debris to be removed.
In view of the accuracy requirements and the need for convenient handling of very expensive vulnerable glass segments, it was decided at an early stage that the workpiece should be nominally horizontal with special provision made for the removal of coolant and grinding debris. The size and mass of the workpiece and its mounting fixture determined that it should be stationary with the grinding spindle and measuring probe moving in a three co-ordinate system above it on a travelling gantry.
The grinding spindle and measuring probe carried on the lower end of the vertical Z axis ram, having 610mm stroke. The Z axis, in turn is carried on a Y axis carriage which traverses horizontally with 2.675m stroke across a bridge member. The bridge is mounted on columns which traverse horizontally along the X axis guideways disposed at either side of the worktable. The X axis operational stroke is 2.6m extending to 3.15m to facilitate component loading.
Machine Axis Layout
From this configuration it can be seen that both the overall dimensions of the machine and the effect of machine distortion due to variations of workpiece/fixture mass are minimised. The measuring probe, which operates vertically, is placed at a fixed offset of 175mm in the Y direction from the grinding wheel. It is retracted during the grinding process and lowered into its operational position for operating the machine in the measurement mode.