SPINDLE AND PULLEY CONNECTING STRUCTURE ON MAIN SHAFT OF AUTOMATIC LATHE

PURPOSE: A spindle and pulley connecting structure connects a spindle and a pulley without a key and removes the gap between the spindle and pulley assembling part to improve rotatory stability of a main shaft. CONSTITUTION: A bearing nut(20) supporting an end plate(24) is engaged with a screw part(52) formed on the periphery of a spindle(50). A pilot shaft part(54) is formed on the end part of the spindle(50) extended from the screw part(52). A pilot hole part(74) is formed on a boss part(72) of a pulley(70). The periphery of the pilot shaft part(54) and the inner circumference of the pilot hole part(74) are fitted to be engaged. An end part surface(56) of the pilot shaft part(54) is engaged with the inner lower surface(76) of the pilot hole part(74) closely. The spindle(50), the end part surface(56) and the inner lower surface(76) of the spindle(50) are fixed by multiple bolts(90) inserted from the outer side end surface of the pulley(70).