Bocca & Malandrone Sunebo S.p.A, Italy, produces Centerless Grinders characterized by rigidity, stability, precision and reliability. With the advent of electronic application on machine tools, Bocca & Malandrone has completely re-designed and rationalized its range of machines and developed a new family of products to make the maximum use of CNC controls, measurement devices and automation loading unloading devices.
At present, BMS range of centerless grinders consist of three models, all of which guarantee maximum flexibility in application since they are designed to work in both thrufeed or infeed.
These machines are Fixed Center machines. It means that the work rest blade support is firmly fixed on the machine base. Grinding and regulating wheel are mounted on solid support fixed on the hydrostatic slides which can be moved towards dressing unit or backwards to the blade.
BMS centerless are completely CNC controlled. As shown in the figure, the grinding wheel axis (X2) manages the grinding wheel slide movement towards the dressing unit and backwards to the blade (the part to be machined). The control wheel axis (X1) manages the control wheel slide movement towards the dressing unit and backwards to the blade (to the pat to be machined). The axes (Z2) and (Z1) respectively manage the longitudinal movement of dressing tool of grinding and control wheel and can interpolate with X2 and X1.
The above mentioned four axes together with the axis to manage the regulating wheel rotation speed and the axis to manage the grinding wheel constant rotation speed, are then enough to completely control all the machine movements.
The precision of BMS grinders is achieved due to the high rigidity of the system. The machine bed in electro-welded steel is fulfilled with a special elastic concrete to absorb the vibration and it is designed to guarantee the better discharge of coolant and avoid leakage of fluid. All Bocca & Malandrone models of centerless grinders are equipped with hydrostatic slides and hydrodynamic spindles for grinding and regulating wheels. Hydrostatic slide is the best technological solution for the long-term reliability of precision. The slides are driven with brushless motors and precision reduction gear units; a thin film of lubricant separates the two sliding surfaces, and maintains them at a defined distance avoiding the wearing of parts. No pulley system is used and no linear re-circulations bearings are used.
The dresser of the machines are CNC type, but in order to increase the reliability of geometrical linearity of the traverse movement of the dresser, a template act as reference point for infeed axis of CNC. As a result, the dresser doesn’t require and maintenance for a longer time.
The patented BMS solution permits changing the grinding and regulating wheel rapidly without disassembling the spindle from the machine by means of open-able wheel front support. The protection guard sliding on guide permits a complete opening of machines to facilitate machine set up, maintenance and cleaning operations.