NOZZLE TOUCH MECHANISM FOR INJECTION MOLDING MACHINE

PROBLEM TO BE SOLVED: To fit a ball screw precisely without requiring skill. SOLUTION: A ball screw 6 is comprised of a fall screw shaft 8 and a ball nut 9 engaging with each other. The ball nut 9 is fitted to a sleeve 17 integrally, engages a first bearing 20 comprising small-diameter ball bearings, second and third bearings 21, 22, comprising large-diameter angular ball bearings and a fourth bearing 23 comprising small-diameter ball bearings in turn with the periphery of the sleeve 17, holds them by a fastening nut 19 and a flange part 18, and is assembled integrally as a nut unit. The fourth bearing 23 is engaged with the small diameter part 12 of a nut fitting hole 10, the second and third bearings 21, 22 are engaged with the large diameter part 13 of the nut fitting hole, and a bearing pressing member 24 is bolt-bonded to the rear wall of a heating cylinder housing so that the second and third bearing 21, 22 are pressed to the front wall of the large diameter part 13 of the nut fitting hole to be fitted integrally to the heating cylinder housing.