Swinging device of chair base

Abstract

The present invention is to provide a swinging device of a chair base, including a support frame, and a base frame which are combined with each other by connecting racks, screws, and fastening structures. The support frame includes two side racks, two support rods each secured between the two side racks by screws, and two crossbars mounted between the bottoms of the two side racks. The base frame includes two side racks, and four connecting rods each secured between the two side racks by screws. The fastening structure includes a screw bearing, a cap washer, and a sleeve, and is locked by screws and nuts.

What is claimed is:  
     
         1 . A swinging device of a chair base, comprising: a support frame, and a base frame which are combined with each other by connecting racks, screws, and fastening structures; wherein, 
 the support frame includes two side racks each having an inner face having a top having a left side and a right side each defining a plurality of screw holes, two support rods each secured and locked between the two side racks by means of a plurality of screws being screwed into the screw holes, and two crossbars mounted between the bottoms of the two side racks, each of the two support rods is formed with two through holes;    the base frame includes two side racks each having an inner face having a top and a bottom each having a left side and a right side each defining a plurality of screw holes, and four connecting rods each secured and locked between the two side racks by means of a plurality of screws being screwed into the screw holes;    the connecting rack includes two side rods, and a connecting rod secured and locked between the two side rods by means of a plurality of screws;    the fastening structure includes a screw bearing, a cap washer, and a sleeve, and is locked by screws and nuts;    the improvement comprising: 
 the support frame has a bottom having a front end and a rear end each having a left side defining a recess and a right side defining a recess, and four screw holes around each recess; the screw bearing is received in the recess, with its threaded end directed upward; the cap washer is placed on the screw bearing, and the screws are then screwed into the screw holes; through holes defined in a bottom of the connecting rack are planted on the screw bearings buried in the front and rear ends of the support frame, and the screw bearings are locked by nuts; through holes defined in a top of the connecting rack are respectively buried with a screw bearing, and four screw holes are formed around each through hole; the cap washer is locked on the top of the connecting rack by screws, and the screw bearing is protruded outward from the cap washer; the protruding screw bearings of the connecting racks are planted into through holes formed in a top of the base frame, and are locked by nuts.  
   
     
     
         2 . The swinging device of a chair base in accordance with  claim 1 , wherein the through holes of the top of the support frame may fit various chairs.  
     
     
         3 . The swinging device of a chair base in accordance with  claim 1 , wherein the cap washer defines a recess having a circular shape or a polygonal shape.