Intelligent continuous polishing machine and process

Abstract

An intelligent continuous polishing machine and an intelligent continuous polishing process therefor are provided. The intelligent continuous polishing machine includes a base platen, a rotary platen, a multi-beam bridge mechanism, two workpiece holding mechanisms, a lap measuring mechanism, a lap cutting mechanism, a small-conditioner holding mechanism, a large-conditioner holding mechanism, and a control computer. The intelligent continuous polishing process includes a normal polishing procedure, a lap surface shape measuring procedure, and three procedures for correcting the lap surface shape error: a lap cutting procedure, a sub-aperture correcting procedure, and a full-aperture correcting procedure. All of these procedures are controlled by the control computer through CNC programs.

What is claimed is: 
     
         1 . An intelligent continuous polishing machine, the machine comprises:
 a rotary platen mounted on a base platen, the base platen placed on three supporting blocks that are mounted on ground;   a multi-beam bridge mechanism installed above the rotary platen, the multi-beam bridge mechanism configured with four horizontal beams. A first linear slide guide configured with a movable block is installed on one side of the first horizontal beam, and a second linear slide guide configured with a movable block is installed on the other side. A third linear slide guide configured with a movable block is installed on the third horizontal beam, and a fourth linear slide guide configured with a movable block is installed on the fourth horizontal beam. A guide base is installed on the second horizontal beam through an adjusting structure, and a precision aerostatic slide guide configured with a movable block is fixed on the guide base;   a first workpiece holding mechanism installed on the movable block of the first linear slide guide, and a second workpiece holding mechanism installed on the movable block of the fourth linear slide guide;   a lap measuring mechanism installed on the movable block of the precision aerostatic slide guide;   a lap cutting mechanism installed on the movable block of the precision aerostatic slide guide;   a small-conditioner holding mechanism installed on the movable block of the second linear slide guide;   a large-conditioner holding mechanism installed on the movable block of the third linear slide guide;   a control computer that can control every subsystems of the machine;   
     
     
         2 . The machine of  claim 1  in which the base platen is configured with a group of through holes for compressed air at the center area, compressed air with a preset pressure fed from the lower ports of the through holes and released from the upper ports to form a very thin cushion between the rotary platen and base platen; 
     
     
         3 . The machine of  claim 1  in which the supporting height of the three supporting blocks can be adjusted respectively so as to control the absolute verticality error of the base platen rotary axis; 
     
     
         4 . The machine of  claim 1  in which a layer of polishing pitch is prepared on the top surface of the rotary platen to form a polishing lap; 
     
     
         5 . The machine of  claim 1  in which the bottom side of the rotary platen is processed into a lug section that has a smaller diameter, a gear ring is installed around the circumference of the lug section of the rotary platen, and a drive motor assembly is fixed beside the lug section, the drive gear of the drive motor assembly matches the gear ring around the lug section so as to rotate the rotary platen; 
     
     
         6 . The machine of  claim 1  in which an electronic inclinometer is mounted on the guide base for determining the inclination of the guide base and the aerostatic slide guide, the inclination of the guide base and the aerostatic slide guide can be regulated by the adjusting structure, and the guide base is made from thermo-stable materials such as granite assuring precision of the aerostatic slide guide; 
     
     
         7 . The machine of  claim 1  in which the workpiece holding mechanism comprises a supporting frame, three holding wheels, a work ring, a drive motor and a septum;
 the supporting frame includes an upper part fixed on the movable block of the first linear slide guide and a lower part configured with an opening; 
 the three holding wheels are installed around the opening of the lower part, and the work ring placed within the opening is held by the three holding wheels; 
 a gear belt is installed around the circumference of the work ring, the drive motor is installed on the lower part of the supporting frame, and the drive gear of the drive motor matches the gear belt of the work ring so as to rotate the work ring; 
 the septum is fixed within the work ring and the workpiece is placed within the septum during polishing; 
 
     
     
         8 . The machine of  claim 1  in which the lap measuring mechanism comprises a displacement sensor, a featured measuring tool, and a measuring object;
 the displacement sensor is fixed on the movable block of the aerostatic slide guide through an adjustable connector, 
 they measuring tool includes an upper part fixed on the movable block of the aerostatic slide guide and a lower part with a work hole, the measuring object is placed within the work hole; 
 the measuring tool constrains the measuring object to move across the lap surface, and the displacement sensor measures the position of the measurement object that has a single degree of freedom in the vertical direction; 
 
     
     
         9 . The machine of  claim 1  in which the lap cutting mechanism comprises a fifth linear slide guide configured with a movable block, a high-speed motor fixed on the movable block, and a cutting knife installed on the rotor of the high-speed motor;
 the cutting knife is driven by the high-speed motor to rotate at a high speed, so as to cut the lap surface; 
 the movable block is controlled to move along the fifth linear slide guide in the vertical direction, so that the cutting depth of the cutting knife into the lap surface can be controlled instantaneously as the cutting knife moves along the lap surface radially; 
 
     
     
         10 . The machine of  claim 1  in which the small-conditioner holding mechanism is, configured to rotate the small conditioning tool with a determined eccentricity under a constant loading, comprising a drive motor, a drive belt, a pneumatic cylinder configured with a piston rod, an eccentricity adjusting structure, and a small conditioning tool;
 the drive motor rotates the piston rod of the pneumatic cylinder through the drive belt; 
 the eccentricity adjusting structure includes an upper column fixed on the piston rod and a lower column connecting the small, conditioning tool by a ball joint structure, the eccentricity of the lower column with respect to the piston rod can be adjusted by the eccentricity adjusting structure; 
 the applying force of the small conditioning tool onto the lap surface can be altered and controlled by the pneumatic cylinder through the piston rod; 
 
     
     
         11 . The machine of  claim 1  in which the large-conditioner holding mechanism comprises a conditioner lifting structure, a large conditioner, and a drive motor;
 the conditioner lifting structure are fixed on one side of the movable block of the third linear slide guide; 
 the large conditioner is connected to the conditioner lifting structure while placed on the lap, and the loading force of the large conditioner onto the lap can be controlled; 
 a gear belt is installed around the circumference of the large conditioner, the drive motor is fixed on the other side of the movable block, and the drive gear of the drive motor matches the gear belt of the large conditioner so as to rotate the large conditioner; 
 
     
     
         12 . The machine of  claim 1  in which the control computer uses computer numerical controlled (CNC) programs, with proper feedback from linear and rotary encoders, to allow the accurate positioning and speed controls; 
     
     
         13 . An intelligent continuous polishing process, the process comprises a normal polishing procedure, a lap measuring procedure, and three procedures for correcting the lap surface shape error including a lap cutting procedure, a sub-aperture correcting procedure, and a full-aperture correcting procedure); all the procedures are controlled by the control computer though CNC programs; 
     
     
         14 . The process of  claim 13  in which the normal polishing procedure is conducted when polishing the workpiece, comprising:
 placing the workpiece on the lap in the septum within the work ring; 
 feeding abrasive slurry onto the lap surface that is transported to the polishing site by the slurry channels on the surface; 
 controlling the rotation of the pitch lap, the rotation and translation of the work ring; 
 
     
     
         15 . The process of  claim 14  in which material is removed from the workpiece surface by the slurry particles achieving a desired surface figure; 
     
     
         16 . The process of  claim 13  in which the lap measuring procedure is conducted when measuring the surface shape of the pitch lap, comprising:
 determining and calculating the reference error of the lap measuring procedure; 
 measuring the surface shape of the pitch lap by moving the measurement point of the displacement sensor in a generally radial direction while the rotary platen rotates; 
 creating the actual surface shape of the pitch lap according to the reference error and the lap measuring data; 
 generating the error map of the pitch lap by comparing the actual surface shape with the desired surface shape; 
 
     
     
         17 . The process of  claim 16  in which the reference error of the lap measuring procedure is divided into (a) the coupled error of the, absolute inclination error and straightness error of the aerostatic slide guide and (b) the absolute verticality error of the lap rotary axis;
 the coupled error of the aerostatic slide guide is determined using ,a displacement sensor fixed on the movable block of the aerostatic slide guide to measure a water surface as the movable block, is servo motorized to translate along the aerostatic slide guide; 
 the absolute verticality error of the lap rotary axis is determined using an electronic inclinometer placed on a platen that is mounted on the pitch lap, the absolute verticality error of the lap rotary axis is derived according to the instantaneous inclination of the electronic inclinometer passing through the aerostatic slide guide (q 1 ) and the opposing side (q 2 ) on the rotating pitch lap, q=(q 1 -q 2 )/2. 
 
     
     
         18 . The process of  claim 16  in which the movement of the displacement sensor can be achieved using the aerostatic slide guide configured the movable block; 
     
     
         19 . The process of  claim 16  in which measuring the surface shape of the pitch lap generates a spiral path with a self-defined pitch and provides an opportunity to create the entire surface shape with an interpolation method; 
     
     
         20 . The process of  claim 13  in which the lap cutting procedure is implemented by the lap cutting mechanism under the control of the control computer, comprising deriving the radial profile of the desired surface that is radial symmetric and generating the moving profile of the cutting knife can be obtained by integrating the radial profile of the desired surface and the reference error of the lap measuring procedure;
 and further comprising rotating the pitch lap and the cutting knife and controlling the cutting knife to move along the pitch lap radially with the moving profile so as to compensate for the desired lap profile and the reference error and thus achieve a desired surface shape of the pitch lap in despite of the initial surface shape; 
 
     
     
         21 . The process of  claim 13  in which the sub-aperture correction procedure is implemented by the small-conditioner holding mechanism under the control of the control computer, comprising:
 determining the actual surface shape of the pitch lap; 
 calculating the surface shape error according to the actual surface shape and the desired surface shape; 
 configuring the small conditioning tool and determining the work function, of the small conditioning tool; 
 calculating the tool dwell time over the lap surface and the required motion; 
 executing the calculated conditioning program; 
 
     
     
         22 . The process of  claim 21  in which configuring the small conditioning tool comprises adjusting the eccentricity, rotary speed, and loading pressure of the small conditioning tool to obtain work functions of different sizes and profiles; the work function of the small conditioning tool is obtained by measuring the surface shape of the pitch lap before and after a determined working duration time, and the positioning and dwell time of the small conditioning tool, over the lap surface is implemented by controlling the rotation of the pitch lap and the radial motion of the small conditioning tool; 
     
     
         23 . The process of  claim 13  in which the full-aperture correction procedure is implemented by the large-conditioner holding mechanism under the control of the control computer; the large conditioner is moved outwards a determined distance for correcting a concave surface shape or inwards a determined distance for correcting a convex surface shape.