Fixture for improving balance precision of wheel

A precision fixture for improving the balance precision of a wheel, comprising a chuck, a base, a servo motor, a lower pressure plate, a rubber strip, a plurality of steel balls, an upper pressure plate, a mounting plate, a first connecting shaft, a shaft sleeve, a hydraulic cylinder, a bearing end cover, a plurality of bearings, a guard, an expanding core, eight expanding flaps, a flange plate, eight springs, a plurality of pins, a flange, a second connecting shaft and a plurality of limiting columns, wherein

• the mounting plate, the bearing end cover and the flange are fixed on the base, the servo motor is mounted on the mounting plate, the shaft sleeve is mounted on the base through two columns of the plurality of bearings and the bearing end cover, the hydraulic cylinder is fixed inside the shaft sleeve, an output end of the hydraulic cylinder is connected with the second connecting shaft, the servo motor is connected with the shaft sleeve through the first connecting shaft, and the guard is fixed on the expanding core;
• the expanding core is connected with the shaft sleeve through the second connecting shaft;
• the expanding core, the second connecting shaft and the shaft sleeve are locked circumferentially without relative rotation, and the second connecting shaft and the shaft sleeve are configured to move axially relative to each other;
• the flange plate is fixed on the flange, eight T-shaped chutes distributed uniformly are formed in an inner cavity of the flange and the flange plate, a bottom surface of each of the expanding flaps are T-shaped structures formed in one-to-one correspondence with the eight T-shaped chutes, and the expanding flaps are configured to slide in the T-shaped chutes smoothly with high precision;
• inner walls of the expanding flaps are 15° bevels, and two ends of the springs are respectively connected with the flange plate and the expanding flaps;
• two groups of 15° bevels are distributed uniformly at intervals are formed on a lateral surface of the expanding core, the number of bevels in each group is eight, the two groups of bevels have a height difference therebetween, and upper side walls of the two groups of bevels are intersected at a tapered surface;
• under the coaction of tension of the hydraulic cylinder and elasticity of the springs, when the expanding core is at the bottom, side walls of the expanding flaps contact the tapered surface of the expanding core;
• the servo motor drives the expanding core to rotate 22.5° through the first connecting shaft, the shaft sleeve and the second connecting shaft;
• bevels matched with the expanding flaps are configured to be switched between the two groups of bevels of the expanding core;
• the hydraulic cylinder drives the second connecting shaft and the expanding core to move up and down, and the eight expanding flaps move synchronously centripetally and centrifugally in the eight uniformly-distributed T-shaped chutes formed along the inner cavity of the flange and the flange plate through a fit of the bevels of the expansion flaps and the bevels of the expansion core;
• the lower pressure plate is fixed on the base, the limiting columns and the upper pressure plate are mounted on the lower pressure plate, and the steel balls and the rubber strip are enclosed in a space formed by the lower pressure plate and the upper pressure plate;
• a first convex structure and a second convex structure are formed on an upper end face of the lower pressure plate, a third convex structure and a fourth convex structure respectively corresponding to the first convex structure and the second convex structure are formed on a lower end face of the upper pressure plate, the second convex structure on an outer side of the lower pressure plate and the fourth convex structure on an outer side of the upper pressure plate form a first jaw, and the first convex structure on an inner side of the lower pressure plate and the third convex structure on an inner side of the upper pressure plate form a second jaw;
• the rubber strip is enclosed in a ring groove formed by the first jaw and the second jaw, and are configured to move radially in the groove;
• and
• three groups of steel balls are enclosed inside the second jaw and separated by three of the limiting columns therebetween to avoid circumferential rotation of the steel balls during operation.