To position (without experiencing friction or play) a clamped tool in x-, z- and psi-direction on the Lifrel, a Philips diamond turning machine, an aluminium toolholder has been designed. The toolholder has a stroke of +-0.5mm in x- and z- and +-1degreesC in psi-direction with an accuracy of respectively 0.25microm and 0.1degreesC. Positioning can be done manually using the intuitive mechanism with differential micrometers. The mechanism contains a virtual point of rotation, providing translation-free tooltip rotation. Applying this toolholder in combination with a converging adjustment procedure reduces the adjustment time from a two day to a two hour maximum. During machining the desired position is fixed using a clamp, which improves the stiffness and natural frequency.Displacement information for tool positioning on the Lifrel comes from the differential micrometerscale and from measuring a product copy. Applying the toolholder on a more accurate machine requires displacement sensors.Some groove structures made with two tools require a depth variation in or in between grooves. A closed-loop piezo-driven small-stroke module with a profile tool, added to the toolholder, establishes a 10microm depth variation with respect to the reference tool at a machining frequency of 50Hz. An additional encoder attached to the drum, provides necessary position information. A second toolholder is used to position the reference tool.
|Title of host publication||euspen 2005|
|Place of Publication||France, Montpellier|
|Publication status||Published - 2005|