Floating non-contact ultrasonic enhanced flexible sub-aperture polishing device and method

Patent metadata

Field	Value
Publication number	US-11839944-B2
Application number	US-202217891015-A
Country	US
Kind code	B2
Filing date	Aug 18, 2022
Priority date	Jul 28, 2021
Publication date	Dec 12, 2023
Grant date	Dec 12, 2023

Abstract

A floating non-contact ultrasonic enhanced flexible sub-aperture polishing device and method are disclosed, an X-axis moving platform, a Y-axis moving platform, a Z-axis moving platform and a workpiece swinging platform in linkage control ensure normal lines of a tool and a workpiece are kept at an identical angle to realize sub-aperture processing; the ventilation main shaft acts air pressure on the ball spline's end portion to form an axial thrust to let the tool axially float; a dynamic balance among hydrodynamic pressure, air pressure and dynamic pressure is performed on the polishing liquid by rotation of the flexible tool; a tiny gap between the tool and workpiece is formed by elastic deformation of the flexible tool due to the dynamic pressure; a shearing force for removing materials is generated when the polishing liquid flows through the gap; a cavitation effect in the gap is formed by ultrasonic waves.

First claim

What is claimed is:

1. A floating non-contact ultrasonic enhanced flexible sub-aperture polishing device comprising:
a flexible tool ( 101 );
an amplitude transformer ( 102 );
an ultrasonic transducer ( 103 );
a conductive ring rotor ( 104 );
a conductive ring stator ( 105 );
a connecting shaft ( 106 );
a shaft coupling ( 107 );
a ball spline nut ( 108 );
a ball spline shaft ( 109 );
two axial restraint shaft sleeves ( 110 );
wherein the ball spline nut ( 108 ) is fixed in a ventilation main shaft ( 201 ) through a first flange, the ball spline shaft ( 109 ) is extending through the ball spline nut ( 108 ); the two axial restraint shaft sleeves ( 110 ) are respectively set at two ends of the ball spline nut ( 108 ) in interference connection with the ball spline shaft ( 109 ); one end of the shaft coupling ( 107 ) is in interference connection with the ball spline shaft ( 109 ), the other end of the shaft coupling ( 107 ) is fixedly connected with one end of the connecting shaft ( 106 ); the other end of the connecting shaft ( 106 ) is extending through the conductive ring stator ( 105 ); the conductive ring rotor ( 104 ) is fixedly connected with the connecting shaft ( 106 ); the conductive ring stator ( 105 ) is fixed on an axial moving platform through a rotation stop sheet; the connecting shaft ( 106 ) is in interference connection with an end portion of the ultrasonic transducer ( 103 ); the ultrasonic transducer ( 103 ) is connected with the amplitude transformer ( 102 ) via a second flange; the flexible tool ( 101 ) is fixed with an output end of the amplitude transformer ( 102 ); the conductive ring stator ( 105 ) is coupled with the conductive ring rotor ( 104 ) through an electric brush; a positive end and a negative end of a transducer power of the ultrasonic transducer are respectively coupled with two terminals of the conductive ring rotor ( 104 ).

2. The device according to claim 1 , wherein the device further comprises a Z-axis moving platform ( 202 ), a supporter ( 203 ), an X-axis moving platform ( 204 ), a Y-axis moving platform ( 205 ) and a workpiece swinging platform ( 207 );
wherein the ventilation main shaft ( 201 ) is fixedly assembled on the Z-axis moving platform ( 202 ), the conductive ring stator ( 105 ) is fixedly assembled on the Z-axis moving platform ( 202 ), the Z-axis moving platform ( 202 ) is assembled on the supporter ( 203 ); a workpiece ( 206 ) is fixed on the workpiece swinging platform ( 207 ), the workpiece swinging platform ( 207 ) is fixed on the Y-axis moving platform ( 205 ), moving direction of the Y-axis moving platform ( 205 ) is defined as a vertical direction;
the Y-axis moving platform ( 205 ) is fixed on the X axis moving platform ( 204 ); the Z-axis moving platform ( 202 ) and the X-axis moving platform ( 204 ) are in a same plane with the moving directions thereof orthogonal to each other; the X-axis moving platform ( 204 ) is fixed on the supporter ( 203 ).

3. A polishing method of utilizing the floating non-contact ultrasonic enhanced flexible sub-aperture polishing device of claim 2 , comprising:
moving the device close to the workpiece through the Z-axis moving platform wherein the workpiece is and aspherical workpiece;
adjusting a processing position through the X-axis moving platform and the Y-axis moving platform, ensuring the flexible tool is capable of processing the workpiece at any position along the X-axis and Y-axis directions; and
realizing a sub-aperture processing for the workpiece by moving the workpiece swinging platform along the X-axis direction to search a position of the tool where normal lines of the flexible tool and the workpiece are kept at a same angle.

4. The polishing method according to claim 3 , further comprising:
driving the flexible tool to move freely in an axial direction of the ball spline shaft through acting air pressure on an end portion of the ball spline shaft by the ventilation main shaft, wherein the ball spline shaft has a certain movement allowance in its axial direction;
spraying polishing liquid stably between the flexible tool and the workpiece during the sub-aperture processing, wherein the polishing liquid generates a dynamic pressure along with rotation of the flexible tool, and the dynamic pressure is balanced with the air pressure acted from the ventilation main shaft.

5. The polishing method according to claim 4 , further comprising:
generating an ultrasonic wave by the transducer generates;
transmitting the ultrasonic wave to the flexible tool through the amplitude transformer, wherein the flexible tool includes super-elastic materials, the ultrasonic wave passes through the flexible tool to form an ultrasonic wave with a shape resembling the flexible tool;
transmitting the ultrasonic wave to the polishing liquid through the flexible tool, wherein microbubbles are generated in the polishing liquid under the action of the ultrasonic wave, then broken due to cavitation effect generated by the ultrasonic wave;
generating local turbulence in a gap between the flexible tool and the workpiece through micro-jets generated when the microbubbles are broken, wherein the local turbulence promotes collision and rub between abrasive particles and atoms on a surface of the workpiece;
driving the abrasive particles to remove materials of the workpiece under a shear force generated in the polishing liquid.

6. The polishing method according to claim 4 , further comprising:
rotating the flexible tool to balance the dynamic pressure generated by the polishing liquid with the air pressure from the ventilation main shaft.

7. The polishing method according to claim 4 , further comprising:
forming a tiny gap between the flexible tool and the workpiece by elastic deformation of the flexible tool due to the dynamic pressure;
generating a shearing force for removing materials in the gap when the polishing liquid flows through the gap;
distributing the shearing force in gradient, the closer to the workpiece, the shearing force applied to a surface of the workpiece is larger;
driving the abrasive particles to contact the surface of the workpiece to remove materials under the shearing force.

Assignees

• Univ Zhejiang

Inventors

• Zhu Wule
• Han Fang
• Wu Lu
• Sun Anyu
• Ju Bingfeng

Classifications

• B24B13/012 Primary

  conformable in shape to the optical surface, e.g. by fluid pressure acting on an elastic membrane · CPC title

• B06B3/02

  involving a change of amplitude · CPC title

• B24B1/04

  subjecting the grinding or polishing tools, the abrading or polishing medium or work to vibration, e.g. grinding with ultrasonic frequency (involving oscillating or vibrating containers B24B31/06; superfinishing surfaces on work, e.g. by means of abrading blocks reciprocating with high frequency, B24B35/00) · CPC title

• B24B35/00

  Machines or devices designed for superfinishing surfaces on work, i.e. by means of abrading blocks reciprocating with high frequency · CPC title

• B24B41/04 Primary

  Headstocks; Working-spindles; Features relating thereto · CPC title