Development and Polishing Process of a Mobile Robot Finishing Large Mold Surface

Abstract

Abstract□ A novel self-determination polishing robot finishing large mold free-form surface is developed, and the finishing process method is researched. Contrary to traditional approaches, our premise is that a large mold surface can be polished by using a small robot. This robot system is mainly composed of a polishing robot part, a computer system and a visual positioning system. A type of robot with four uniform distribution wheels was designed, which has two driving wheels and two driven wheels. Active compliant control of the polishing tool was provided by a pneumatic servo system, and a new special compliant abrasive tool was proposed on the basis of robot characteristics. The process planning steps consisted of subdividing the free-form surface, choosing an abrasive tool, planning the polishing path and optimizing machining parameters. Based on the orthogonal experiment and the grey relational analysis method, the optimal parameter combination was obtained for polishing force, tool speed and feed rate. Aiming to polishing times, the surface roughness method and polishing efficiency method were studied in detail. The polishing experiments were carried out in the robot using process parameters obtained by the efficiency method. These research results provided significant theory foundation and experimental data for a mobile robot planning polishing to realize intelligible process parameter selection.Keywords: mobile polishing robotmold free-form surfaceprocess planningsurface roughness NOMENCLATURETi=abrasive toolNi=polishing times of abrasive tool, TiEf=polishing efficiency, umcm2/min△Ra=surface roughness variation, μmva=feed rate, mm/minL=contacting width orthogonal to feed rate direction in contact region between the polishing tool and the workpiece, mmN=polishing timesxij=normalized resultsXij=jth experimental result in the ith experiment=minimum in the jth experimental results=maximum in the jth experimental resultsξij=grey relational coefficientx0j=ideal normalized result for the jth performance characteristicsξ=distinguishing coefficientri=grey rational grade for the ith experimentm=number of performance characteristicsRa0=workpiece surface roughness before polishing, μmRa=workpiece surface roughness after polishing, μmRae=surface roughness closing to a fixed value with increase of polishing times, μmNL1, NL2, NL3=critical polishing times corresponding to three curves respectivelyλ=a comprehensive dimensionless coefficientNL=critical polishing timesNT=critical polishing times of all abrasive toolRa0i=workpiece surface roughness using abrasive tool Ti before polishing, μmRai, Ra(i +1)=workpiece surface roughness using abrasive tool Ti, Ti +1 after polishing, μmRaei, Rae(i +1)=surface roughness closing to a fixed value, using abrasive tool, Ti, Ti +1, μmλi, λi+1=a comprehensive dimensionless coefficient, using abrasive tool, Ti, Ti +1Efi, Ef(i +1)=polishing efficiency, using abrasive tool Ti, Ti +1, μm cm2/minA=polishing area, cm2