JPS5727660A - High-frequency spindle for internal grinder - Google Patents

Abstract

PURPOSE: To greatly lengthen the lifetime of ball bearings and heighten the durability of an internal grinder, by providing a previous pressurization mechanism to previously apply appropriate pressure to the ball bearings and providing a damper mechanism to prevent only the sharp axial displacement of a shaft to avoid impulsive backward movement at the time of starting.

CONSTITUTION: A rotor shaft 10 is supported between a rear bearing 7 and front bearings 4, 5. An appropriate clearance is defined between a rear bearing housing 8 and a damper housing 2 to permit the thermal elongation of the shaft 10. A screw 18 for adjusting previous pressurization is engaged in a damper lid 17 fitted on the rear end of the damper case 12. An energizing means such as a coiled spring 19 is provided between the screw 18 and a second piston. An incompressible fluid is filled between both pistons 13, 14. When the rotor shaft 10 is elongated because of the rise in the temperature inside of a spindle, the fluid easily and smoothly flows through an orifice 16 from the left chamber of a cylinder 11 to its right chamber. When the rotor shaft 10 is contracted because of the fall of the temperature, the fluid easily and smoothly flows through the orifice 16 from the right chamber to the left chamber. As a result, the fluid acts as a damper.

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