Ball given quantity supply apparatus and method and apparatus for assembling ball screw apparatus

Abstract

There are provided with a ball given quantity supply apparatus for supplying a given quantity of balls to an apparatus using a given quantity of balls such as a bearing, a ball screw and a linear guide, and a method and apparatus for assembling a ball screw apparatus for use in a feed mechanism employed in various machines.

1 . A method for assembling a ball screw apparatus, comprising the steps of: 
 loosely fitting a nut with a circulating part previously assembled thereto with a provisional shaft including a tapered step portion formed between a small-diameter shaft portion and a large-diameter shaft portion thereof;    in this state, fitting a ball insertion jig into between the provisional shaft and the nut from the small-diameter shaft portion and rotating the provisional shaft to introduce a given number of balls inserted from the ball passage of the ball insertion jig into between the screw groove of the nut and the provisional shaft through a guide portion formed between the ball insertion jig and the tapered step portion;    moving the provisional shaft to the small-diameter shaft portion side with respect to the nut and the ball insertion jig to allow the balls existing in the guide portion to climb over the tapered step portion,    introducing the balls into between the screw groove of the nut and the provisional shaft; and    fitting the screw shaft of the ball screw apparatus with the nut.    
   
   
       2 . The method for assembling a ball screw apparatus as set forth in  claim 1 , wherein 
 when introducing the balls into between the screw groove of the nut and the provisional shaft, the nut is made eccentric to the provisional shaft.    
   
   
       3 . An apparatus for assembling a ball screw apparatus, comprising: 
 a provisional shaft which includes a tapered step portion formed between a small-diameter shaft portion and a large-diameter shaft portion thereof and also with which a nut of the ball screw apparatus with a circulating part previously assembled thereto can be loosely fitted;    a drive device for rotating the provisional shaft;    a ball insertion jig fittable into between the provisional shaft and the nut from the small-diameter shaft portion, including a ball passage for receiving a given number of balls, defining a guide portion between the tapered step portion and itself, and capable of introducing the balls inserted into the ball passage into between the provisional shaft and a screw groove formed in the nut, and    a moving device the provisional shaft to the small-diameter shaft portion side with respect to the nut and the ball insertion jig.    
   
   
       4 . The apparatus for assembling a ball screw apparatus as set forth in  claim 3 , wherein 
 the ball insertion jig includes:    a ball stopper disposed on the ball exit side of the ball passage so as to separate the ball exit portion or ball entrance portion of the circulating part from the guide portion in order to be able to prevent the balls introduced into between the screw groove of the nut and the provisional shaft from interfering with the balls inserted from the ball passage; and    a projection for preventing the balls inserted from the ball passage from touching directly the groove shoulder of the screw groove of the nut, said projection being disposed on the leading end portion of the ball stopper.    
   
   
       5 . The apparatus for assembling a ball screw apparatus as set forth in  claim 3 , wherein 
 an elastic member is applied to, buried in, shrinkage fitted with, or bonded to the outer peripheral surface of the provisional shaft including the tapered step portion.