A Study On The Dynamic Characteristics Of Grinding Process System And Application

The stab le grind ing is one of the precond itio n and the key techno logies ofsmoothly mac hining and getting high qua lity on grind ing mac hine. Grind ingprocess syste m is the unity o f grind ing mac hine, tool, c la mp a nd workp iece. Itsdyna mic property is fata l to steady grind ing. In this paper, based on the no nlineartheory, the no nlinear vibratio n on re latio ns hip a mong the vario us factors isstud ied.And so me meas ures are p ut forward to restra in the grind ing vibrationthro ugh the ana lys is o f the grind ing process. Dyna mic characteristics are stud ied ongrind ing wheel sp ind le a nd grind ing whee l in both free mode and working mode,thro ugh connecting the finite e le me nt method and experime nta l modal a na lys is.Based on unba la nce syste m, the vibratio n characteristic o f the spind le isana lyzed.A co mpensatio n device is des igned for the d yna mic ba la nc ing o f grind ingwhee l.Dyna mic characteristics of grind ing process syste m are ana lyzed sys te matic,based on dyna mic substructure technique. Thro ugh the theoretical a na lys is,experimenta l test a nd nume rica l co mputa tion method, so me impro ving projects areput forward.Main research’s work inc ludes the fo llowing aspects:(1) Nonlinear theory is stud ied on externa l cylindrica l grind ing, and thenonlinear vibratio n model o f grind ing process are establis hes. The influe nce ofparameters o f the angular freque nc y, the no nlinear damp ing a nd no nlinear stiffnessof interface between grind ing whee l a nd workpiece are stud ied, to put forwardmothods on the grind ing q ua lity o f increas ing damp ing and stiffness. Based onmulti-sca le method, quantitative ana lys is is researched on the ma in resonance, andthe nonlinear resona nce regio n o f grind ing process.It get c haracteristic equatio n onamp litude freque ncy o f the primary resona nce and no n-resona nce. It effective lyrevea ls the rule o f the nonlinearity of the grind ing process, to provide a theoreticalbasis for impro ving the processing qua lity.(2) Based on the e lastic theory, us ing finite ele me nt a na lys is and e xperime nta lmoda l ana lys is method, the dyna mica l mode ls are constructed on thespind le/sp ind le s yste m in free state, and the working condition. The natura lfreq uenc y and vibra tion mode of the syste m are ca lcula ted. Ratio na lity o f the finiteele me nt mode l is vethrified b y experime nta l moda l a na lys is method, and furtherana lyzes the influence o f the grinder spind le speed to contact stress, axia l te ns ionforce, connectio n stiffness, natura l freque nc y and damp ing ratio o f the syste m structure, and weak pos itio n of structure tools, etc.(3)The finite e le me nt model o f unba la nce spind le sys te m is established.Andthe vibratio n of each part on grind ing whee l spind le, the ha ndle end face and ha nd lecone are stud ied. The influe nce of vibratio n ma gnitude of the rotationa l speed inspind le syste m and the unba la nce va lue o f grind ing whee l syste m to the qua lity ofthe workpiece are stud ied.(4) From the perspective o f contro l e ngineering a nd comp utationa l mec ha nics,the device o f adjus tive co mpensatio n of dyna mic ba lanc ing is designed on thespind le syste m. The precis io n grade of the dyna mic bala nc ing, vibratio n va lue andthe processing workp iece surface roughness are co mpared before and after dyna miccorrection sys te m, and get a co nc lus io n about the va lue of vibratory a mp litude isdecreased significa ntly a fter d yna mic bala nce.The ba lance o f sp ind le accuracygrade is higher tha n be fore the co mpensatio n. Based on the method of influe ncecoeffic ie nt, methods of fast dyna mic ba lanc ing of the s ingle a nd doub le side areapp lied on the grind ing whee l s yste m. Not only it s hortens the eq uilibrium times,but also imp roves the product ing effic ienc y. It proves that the design ofcompensatio n device of dyna mic bala nc ing for impro ving the va lue of workpiecesurface is e ffective and feasib le.(5)Equiva le nt dyna mics model o f each substructure is set up on an effic ientinte gratio n of a prec is ion grind ing machine. By tests of freq uenc y responsefunction, va lues of stiffness and damp ing parameter are ide ntified. Numerica lcalc ulation is done to each substructure for joints of fixed taper, the rolling bearing,slid ing ra il, and bo lt, etc.There force, natura l freq uenc y and vibratio n model areobtained.(6) Based on the method of d yna mic s ubstructure, a high precis io n grind ingmac hine structure is d ivided into d ifferent s ubstructures of grind ing whee l---spind le syste m, headstock---the workp iece spindle s yste m, grind ing whee l fra me,column, operating p latform, bed, dragging p late o f grind ing whee l a nd draggingplate o f operating p latform. The parameters s uc h as stiffness, da mp ing va luesbetween each substructure are ide ntified through experime nta l modal method.Dyna mic c haracteristics o f prec is ion grind ing machine o f each s ubstructure areana lyzed in the software of finite e le ment ana lys is. Thro ugh ana lys is o f dyna miccharacteristics o n who le the mac hine, the acc uracy o f the s imulatio n and res ults ofthe substructure are further proved.