Fixture for improving balance precision of wheel

The invention discloses 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, steel balls, an upper pressure plate, a mounting plate, a connecting shaft, a shaft sleeve, a hydraulic cylinder, a bearing end cover, bearings, a guard, an expanding core, expanding flaps, a flange plate, springs, pins, a flange, a connecting shaft and limiting columns. The fixture can meet the requirement for improving the balance precision of a wheel, at the same time, has the characteristics of simple structure, convenient manufacture, stable performance and precision that can meet the machining requirement, and can meet the requirements of automatic production.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese Patent Application No. 201810063566.7, entitled FIXTURE FOR IMPROVING BALANCE PRECISION OF WHEEL and filed on Jan. 23, 2018, which is incorporated herein by reference in its entirety and for all purposes.

FIELD OF THE INVENTION

The present invention relates to a machining device.

BACKGROUND OF THE INVENTION

In the wheel machining industry, wheel balance degree is an important factor affecting the comfort and the safety of an automobile and is a 100% test item. At the same time, the reject rate of wheel balance out of tolerance is an important factor affecting the wheel yield. By research and analysis, the wheel balance out of tolerance may be caused by many factors, wherein the outer rim machining traces formed in the first and second procedures of the wheel machining process are the key factor of balance out of tolerance. The present invention introduces a precision fixture for improving the balance precision of a wheel. The fixture not only can realize no machining trace on the outer rim of the wheel and improve the balance precision of the wheel, but also can improve the machining effect on the outer rim.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a precision fixture for improving the balance precision of a wheel.

In order to fulfill the above aim, the technical solution of the present invention is: 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, steel balls, an upper pressure plate, a mounting plate, a first connecting shaft, a shaft sleeve, a hydraulic cylinder, a bearing end cover, bearings, a guard, an expanding core, expanding flaps, a flange plate, springs, pins, a flange, a second connecting shaft and limiting columns.

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 the two columns of bearings and the bearing end cover, the hydraulic cylinder is fixed inside the shaft sleeve, the 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 can move axially relative to each other.

The flange plate is fixed on the flange, eight T-shaped chutes distributed uniformly are formed in the inner cavity of the flange and the flange plate, the bottom surfaces of the eight expanding flaps are T-shaped structures formed in one-to-one correspondence with the eight T-shaped chutes, and the expanding flaps can slide in the chutes smoothly with high precision.

The inner walls of the expanding flaps are 15° bevels, and two ends of the eight springs are respectively connected with the flange plate and the eight expanding flaps.

Two groups of 15° bevels distributed uniformly at intervals are formed on the lateral surface of the expanding core, the number of bevels in each group is 8, the two groups of bevels have a height difference therebetween, and the 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, the 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; and the bevels matched with the expanding flaps can be switched between the two groups of bevels of the expanding core.

The hydraulic cylinder drives the second connecting shaft and the expansion core to move up and down, the eight expansion flaps move synchronously centripetally and centrifugally along the eight uniformly-distributed T-shaped chutes formed in the inner cavity of the flange and the flange plate through the fit of the expanding flaps and the bevels of the expanding core, and the eight expanding flaps realize high-precision synchronous expansion and contraction functions.

Since the two groups of bevels spaced uniformly on the lateral surface of the expanding core have a height difference, when the servo motor drives the expanding core to rotate 22.5°, the bevels matched with the expanding flaps are switched between the two groups of bevels of the expanding core, thus, the expansion and contraction diameters of the expanding flaps change in two different ranges, and eventually the expanding flaps achieve largestroke expansion and contraction.

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 the upper end face of the lower pressure plate, a third convex structure and a fourth convex structure are correspondingly formed on the lower end face of the upper pressure plate, the second convex structure on the outer side of the lower pressure plate and the fourth convex structure on the outer side of the upper pressure plate form a first jaw, and the first convex structure on the inner side of the lower pressure plate and the third convex structure on the 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 can move radially in the groove; three groups of steel balls are enclosed inside the second jaw and separated by the three limiting columns therebetween to avoid circumferential rotation of the steel balls during operation.

During operation, the wheel rotates at a high speed, the steel balls are thrown outward through centrifugal force, the steel balls drive the rubber strip to move out and to compress the inner rim of the wheel, and the rubber strip in the compressed state have strong elasticity and can effectively offset the vibration of the wheel rim during machining, thereby improving the machining effect of the wheel, realizing once forming of the outer rim of the wheel without machining traces and accordingly improving the balance precision of the wheel.

A bevel structure is formed on an outer portion of the upper end face of the lower pressure plate, and after the operation is completed, the steel balls roll inward under the action of selfweight and disengage from the rubber strip to facilitate removal of the wheel.

Corresponding pin holes are formed in the flange and the flange plate, and the pins are respectively connected with the pin holes of the flange and the flange plate to ensure the assembly precision of the flange and the flange plate.

Before actual use, the fit of the corresponding bevels of the expanding core and the expanding flaps is adjusted through the servo motor and the hydraulic cylinder according to the diameter of the center hole of the wheel. During actual use, when a wheel is placed on the fixture, the expanding flaps are placed in the center hole of the wheel, tiny gaps are reserved between the rubber strip and the inner rim of the wheel, then, the hydraulic cylinder drives the second connecting shaft and the expanding core to rise vertically, the eight expanding flaps are expanded with high precision through the fit of bevels of the expanding core and inner bevels of the expanding flaps and expand the center hole of the wheel, the bevel manufacturing precision of the expanding core and the expanding flaps is very high, the expansion consistency and precision of the expansion flaps are extremely high, and the wheel positioning operation is completed. Then, machining of the wheel begins, the wheel rotates at a high speed, the steel balls are thrown outward through the centrifugal force, and the steel balls drive the rubber strip to move out and to compress the inner rim of the wheel. The rubber strip in the compressed state has strong elasticity and can effectively offset the vibration of the wheel rim during machining, thereby improving the machining effect of the wheel, realizing once forming of the outer rim of the wheel without machining traces and accordingly achieving the aim of improving the balance precision of the wheel.

The fixture can meet the requirement for improving the balance precision of a wheel, at the same time, has the characteristics of simple structure, convenient manufacture, stable performance and precision that can meet the machining requirement, and can meet the requirements of automatic production.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The details and working conditions of the specific device according to the present invention will be described in detail below in combination with the drawings.

A precision fixture for improving the balance precision of a wheel according to the present invention comprises a chuck1, a base2, a servo motor3, a lower pressure plate4, a rubber strip5, steel balls6, an upper pressure plate7, a mounting plate8, a connecting shaft9, a shaft sleeve10, a hydraulic cylinder11, a bearing end cover12, bearings13, a guard14, an expanding core15, expanding flaps16, a flange plate17, springs18, pins19, a flange20, a connecting shaft21and limiting columns22.

The mounting plate8, the bearing end cover12and the flange20are fixed on the base2, the servo motor3is mounted on the mounting plate8, the shaft sleeve10is mounted on the base2through the two columns of bearings13and the bearing end cover12, the hydraulic cylinder11is fixed inside the shaft sleeve10, the output end of the hydraulic cylinder11is connected with the connecting shaft21, the servo motor3is connected with the shaft sleeve10through the connecting shaft9, and the guard14is fixed on the expanding core15.

The expanding core15is connected with the shaft sleeve10through the connecting shaft21; the expanding core15, the connecting shaft21and the shaft sleeve10are locked circumferentially without relative rotation, and the connecting shaft21and the shaft sleeve10can move axially relative to each other.

The flange plate17is fixed on the flange20, eight T-shaped chutes distributed uniformly are formed in the inner cavity of the flange20and the flange plate17, the bottom surfaces of the eight expanding flaps16are T-shaped structures formed in one-to-one correspondence with the eight T-shaped chutes, and the expanding flaps16can slide in the chutes smoothly with high precision.

The inner walls of the expanding flaps16are 15° bevels, and two ends of the eight springs18are respectively connected with the flange plate17and the eight expanding flaps16.

Two groups of 15° bevels15-1and15-2distributed uniformly at intervals are formed on the lateral surface of the expanding core15, the number of bevels in each group is 8, the two groups of bevels have a height difference, and the upper side walls of the two groups of bevels are intersected at a tapered surface15-3; under the coaction of tension of the hydraulic cylinder11and elasticity of the springs18, when the expanding core15is at the bottom, the side walls of the expanding flaps16contact the tapered surface15-3of the expanding core15; the servo motor3drives the expanding core15to rotate 22.5° through the connecting shaft9, the shaft sleeve10and the connecting shaft21; and the bevels matched with the expanding flaps16can be switched between the bevels15-1and the bevels15-2of the expanding core15.

The hydraulic cylinder11drives the connecting shaft21and the expansion core15to move up and down, the eight expansion flaps16move synchronously centripetally and centrifugally along the eight uniformly-distributed T-shaped chutes formed in the inner cavity of the flange20and the flange plate17through the fit of the bevels of the expanding flaps16and the bevels of the expanding core15, and the eight expanding flaps16realize high-precision synchronous expansion and contraction functions.

Since the two groups of bevels spaced uniformly on the lateral surface of the expanding core15have a height difference, when the servo motor3drives the expanding core15to rotate 22.5°, the bevels matched with the expanding flaps16are switched between the bevels15-1and the bevels15-2of the expanding core15, thus, the expansion and contraction diameters of the expanding flaps16change in two different ranges, and eventually the expanding flaps16achieve large-stroke expansion and contraction.

The lower pressure plate4is fixed on the base2, the limiting columns22and the upper pressure plate7are mounted on the lower pressure plate4, and the steel balls6and the rubber strip5are enclosed in a space formed by the lower pressure plate4and the upper pressure plate7. A first convex structure4-1and a second convex structure4-2are formed on the upper end face of the lower pressure plate4, a third convex structure7-1and a fourth convex structure7-2are correspondingly formed on the lower end face of the upper pressure plate7, the second convex structure4-2on the outer side of the lower pressure plate4and the fourth convex structure7-2on the outer side of the upper pressure plate7form a first jaw23-1, and the first convex structure4-1on the inner side of the lower pressure plate4and the third convex structure7-1on the inner side of the upper pressure plate7form a second jaw23-2.

The rubber strip5is enclosed in a ring groove formed by the first jaw23-1and the second jaw23-2, and can move radially in the groove; three groups of steel balls6are enclosed inside the second jaw23-2and separated by the three limiting columns22therebetween to avoid circumferential rotation of the steel balls6during operation.

During operation, the wheel rotates at a high speed, the steel balls6are thrown outward through centrifugal force, the steel balls6drive the rubber strip5to move out and to compress the inner rim of the wheel, and the rubber strip5in the compressed state has strong elasticity and can effectively offset the vibration of the wheel rim during machining, thereby improving the machining effect of the wheel, realizing once forming of the outer rim of the wheel without machining traces and accordingly improving the balance precision of the wheel.

A bevel structure4-3is formed on an outer portion of the upper end face of the lower pressure plate4, and after the operation is completed, the steel balls6roll inward under the action of self-weight and disengage from the rubber strip5to facilitate removal of the wheel.

Corresponding pin holes are formed in the flange20and the flange plate17, and the pins19are respectively connected with the pin holes of the flange20and the flange plate17to ensure the assembly precision of the flange20and the flange plate17.

Before actual use, the fit of the corresponding bevels of the expanding core15and the expanding flaps16is adjusted through the servo motor3and the hydraulic cylinder11according to the diameter of the center hole of the wheel. During actual use, when a wheel is placed on the fixture, the expanding flaps16are placed in the center hole of the wheel, tiny gaps are reserved between the rubber strip and the inner rim of the wheel, then, the hydraulic cylinder11drives the connecting shaft21and the expanding core15to rise vertically, the eight expanding flaps16are expanded with high precision through the fit of bevels of the expanding core15and the inner bevels of the expanding flaps16and expand the center hole of the wheel, the bevel manufacturing precision of the expanding core15and the expanding flaps16is very high, the expansion consistency and precision of the expansion flaps16are extremely high, and the wheel positioning operation is completed. Then, machining of the wheel begins, the wheel rotates at a high speed, the steel balls6are thrown outward through the centrifugal force, and the steel balls6drive the rubber strip5to move out and to compress the inner rim of the wheel. The rubber strip5in the compressed state has strong elasticity and can effectively offset the vibration of the wheel rim during machining, thereby improving the machining effect of the wheel, realizing once forming of the outer rim of the wheel without machining traces and accordingly achieving the aim of improving the balance precision of the wheel.