Ball plunger with brim

Abstract

An object of the present invention is to provide a ball plunger wherein a main ball of the ball plunger is rotated surely and smoothly, when a mold, jig or other article is fixed, positioned, or transported. Another object is to control and keep constant the main ball projection height from a surface fixed to the ball plunger. A plurality of the sub balls are accommodated on the bottom portion of the ball roller which farther accommodates the main ball on the sub balls, thereby reducing the rolling friction between the main ball and the sub balls. Thus, the main ball rolls smoothly. The ball roller and the spring is inserted into the casing. Finally, the spring is fixed to the casing by the coupling ring such as a c-shaped ring.

What is claimed is:  
     
         1 . A ball plunger fixed at an object surface, which comprises: 
 a plurality of sub balls;    a ball roller for accommodating said plurality of sub balls;    a main ball disposed on said plurality of sub balls;    a spring for supporting said ball roller;    a casing which accommodates said ball roller and said spring;    a brim on an outer circumference of said casing for stopping said ball plunger at a surface of said object; and    a coupling ring for fixing said spring to said casing, wherein: 
 said sub balls reduce an rolling friction of said main ball and said coupling ring fixes said spring at a prescribed length of said spring.  
   
     
     
         2 . The ball spring according to  claim 1 , wherein an outer surface of said casing is tapped by a male screw.  
     
     
         3 . The ball plunger according to  claim 1 , wherein said coupling ring is a c-shaped ring.