Alternative to creep feed from Okamoto

The Okamoto UPG 31Li Ultra Precision profile grinding machine has been developed to provide a compact, self-contained production or toolroom grinding process as an alternative to creep feed systems, optical profile grinding machines or even wire EDM. It incorporates linear motor drives and adjustable hydrostatic slideway technology and, unlike creep feed methods, the process is able to generate new orders of flatness and straightness within 0.3 microns over 300 mm even when grinding a profile out of solid material by utilising a rapid reciprocating table movement. The compact Okamoto UPG 31Li is able to ensure component geometry, surface finish and very competitive process times on smaller components up to 30 mm by 25 mm such as carbide inserts for punches, high precision slots used in the connector industry, and parts requiring face contouring or edge profiling features to be ground. The machine has a longitudinal travel of 280 mm and cross travel of 170 mm with a magnetic chuck of 170 mm by 105 mm. Daylight between wheel and table top is a maximum of 400 mm. The 2.2 kW 20,000 rpm wheelhead is able to tilt ± 5º and is available with programmable dressing. Both carbide disc and pre-formed diamond wheels can be used. Rapid traverse rates are 1,000 mm/min and feed rates programmable between 1 mm/min and 1,000 mm/min. The machine enables components to be progressively ground by rapidly reciprocating the machine table at up to 650 passes per min as a viable alternative to more traditional creep feed methods that use high wheel speed and a slow progressive feed rate. One major advantage of the new Okamoto method against creep feed is that it does not require the added machine complexity involving high pressure coolant and special dressing systems. Controlled by Fanuc 31i Model A, the machine uses high speed linear drives to provide the rapid acceleration/deceleration to power the high speed reciprocation of the table. The table is supported on dual hydrostatic slideways that are adjusted automatically to maintain a constant oil thickness to create a stable and consistent bearing condition. This configuration of the table overcomes any forces input by the linear drive and removes any tendency for table lift or pull-down during the grinding process. It also eliminates any effects of thermal growth that could otherwise be influenced by the rapid table movement and the linear drive system. Positioning is via linear scale measurement.