Feedrate optimization for 2.5D milling operations

Predstavljeno istraživanje se odnosi na CNC obradu glodanjem ravanskih kontura ravnim vretenastim glodalima. U radu je predstavljen skup funkcija, potrebnih za procesiranje modela obratka i tehnološkog programa obrade, sa ciljem rekonstrukcije trenutne površine obratka zahvaćene alatom. Izabrana je interpretacija obratka pomoću Z-mape. Rekonstruisana mapa zahvata, uz prethodno određene specifične sile rezanja, dovoljna je za predviđanje trenutnih i reprezentativnih sila glodanja u tačkama programirane putanje alata. Time se, nadalje, omogućava korigovanje brzina pomoćnog kretanja u tačkama putanje alata i naknadna rediskretizacija te putanje, a sve u cilju održavanja predefinisanog nivoa sile glodanja. U radu je opisan primer eksperimentalne identifikacije specifičnih sila rezanja i primer primene procedura implementiranih u Matlab okruženju, za optimizaciju brzina pomoćnog kretanja. Rezultati, dobijeni u eksperimentu, iskorišćeni su za diskusiju prednosti i nedostataka primenjenih modela.Presented research is focused on CNC milling operations of planar contours with flat end mills. Paper presents a set of functions required for processing the workpiece model and NC part program in order to reconstruction the instantaneous area of workpiece engaged by the tool. A Z-map interpretation of workpiece was chosen. Reconstructed engagement map, with previously obtained specific cutting forces, is enough for prediction of instantaneous and representative milling forces in points of programmed toolpath. Further, in order to maintain a specified level of milling force, the correction of the feedrate in toolpath points and then rediscretization of the path is enabled. Paper presents an example of experimental identification of specific cutting forces and the results of applications of the procedures, developed in Matlab, for optimization of feedrates. Results obtained through experiments are used for discussion of advantages and limitations of applied models

Feedrate optimization for 2.5D milling operations

Predstavljeno istraživanje se odnosi na CNC obradu glodanjem ravanskih kontura ravnim vretenastim glodalima. U radu je predstavljen skup funkcija, potrebnih za procesiranje modela obratka i tehnološkog programa obrade, sa ciljem rekonstrukcije trenutne površine obratka zahvaćene alatom. Izabrana je interpretacija obratka pomoću Z-mape. Rekonstruisana mapa zahvata, uz prethodno određene specifične sile rezanja, dovoljna je za predviđanje trenutnih i reprezentativnih sila glodanja u tačkama programirane putanje alata. Time se, nadalje, omogućava korigovanje brzina pomoćnog kretanja u tačkama putanje alata i naknadna rediskretizacija te putanje, a sve u cilju održavanja predefinisanog nivoa sile glodanja. U radu je opisan primer eksperimentalne identifikacije specifičnih sila rezanja i primer primene procedura implementiranih u Matlab okruženju, za optimizaciju brzina pomoćnog kretanja. Rezultati, dobijeni u eksperimentu, iskorišćeni su za diskusiju prednosti i nedostataka primenjenih modela.Presented research is focused on CNC milling operations of planar contours with flat end mills. Paper presents a set of functions required for processing the workpiece model and NC part program in order to reconstruction the instantaneous area of workpiece engaged by the tool. A Z-map interpretation of workpiece was chosen. Reconstructed engagement map, with previously obtained specific cutting forces, is enough for prediction of instantaneous and representative milling forces in points of programmed toolpath. Further, in order to maintain a specified level of milling force, the correction of the feedrate in toolpath points and then rediscretization of the path is enabled. Paper presents an example of experimental identification of specific cutting forces and the results of applications of the procedures, developed in Matlab, for optimization of feedrates. Results obtained through experiments are used for discussion of advantages and limitations of applied models

Prediction of thrust force and torque in tapping operations using computer simulation

Pristup opšte mehanike rezanja, uspešno je primenjivan za različite zahvate obrade alatima složene geometrije. Ovde je primenjen za predviđanje aksijalne sile i momenta pri urezivanju navoja mašinskim ureznikom. Osnovna ideja je da se podaci određeni kroz testove sa ortogonalnim rezanjem i izrazi za sile pri kosom rezanju iskoriste za određivanje komponenti sila rezanja na diskretizovanim delovima sečiva. Razvijeni program za simulaciju izračunava trenutnu poziciju ureznika u odnosu na rupu, presek nedeformisane strugotine za svaki zub. Integracijom po svim zubima u zahvatu dobijaju se trenutne vrednosti momenta i aksijalne sile za svaki simulacioni korak u ukupnom ciklusu urezivanja navoja.General cutting mechanics approach, successfully used for different machining operations using cutting tool with complex geometry, was here applied for prediction of cutting forces in tapping with machine taps. Basic idea was to exploit data obtained from orthogonal cutting tests and relations for oblique cutting forces to obtain force components on discretized parts cutting edges. Developed simulation program calculates instantaneous positions of tap in hole and un deformed chip area of each engaged tooth. Integration along all engaged teeth provides actual values of torque and thrust force in every simulation step in the whole tapping cycle

Configuring a virtual desktop 5-axis machine tool for machine simulation

This paper discusses the possibilities of application machine simulation and verification of the program before machining. Process of virtual machine configuring for machine simulation in CAD/CAM and VeriCUT environment is shown. Configured virtual prototypes are used for the verification of tool path as part of the offline programming system, using machine simulation in the CAD/CAM environment. Verification of machining program, in G code, using machine simulation in the solid cutting simulation software VERICUT, are also described on examples

Evaluation of infeed strategies for turning of large thread profiles

Several infeed strategies for multipass threading operations on CNC lathes are well known and they are implemented in form of apropriate canned cycles in system software of CNCs. These strategies are especially suitable for triangular profiles of thread. Paper presents method developed for analysing of infeed strategy in threading operations for arbitrary geometry of thread profile and geometry of tool profile, including trapezoidal threads and worm wheels. Proposed method uses two criteria for evaluation of specific infeed strategy in multipass turning of threads. The first one is the measure of balance of uncut chip area in subsequent passes (implemented application in Matlab is described). Calculation of chip area is based on numerical integration The second criterion is referred to predicion of cutting forces and their distibution in subsequent passes.. Cutting force estimation is based on specific cutting forces and engaged chip area acting on discretized lenghts of cutting edges

Verifikacije procedure predikovanja sila pri obradi cilindričnim vretenastim glodalima

U konceptu virtuelne obrade (VM), bitnu funkciju predstavlja predikovanje sila duž programirane putanje. To je važno kako za ocenu projektovanog tehnološkog procesa, tako i za njegovu optimizaciju, kroz off-line podešavanje parametara obrade. U radu je primenjen makromehanički model sila rezanja i procedura predikovanja trenutnih vrednosti sila glodanja, zasnovan na simulaciji obrtanja alata diskretizovane rezne geometrije. Obavljena je procedura eksperimentalne identifikacije specifičnih sila rezanja. Poznati simulacioni model je unapređen detaljima koji se odnose na radijalno bacanje sečiva alata i na složenije mape zahvata. Eksperimentalno je potvrđen kvalitet predstavljene procedure kroz skup reprezentativnih primera obrade

Functions for processing of wokpiece CAD model for prediction and optimization of milling process

This paper deals with specific presentation of wokpiece volume and with functions for manipulating them in order to extract necessary data for various functions in virtual manufacturing environment. Basic idea was to use standard STL output of created model of blank material and convert to Z-map model. Functions for simulation of material removal process and extracting of geometry of instant tool immersion conditions are developed in Matlab environment. Exacting of engaging (tool immersion) map along discretized tool path is of great importance for application of model for instant cutting forces, based on simulation of discetized cutting geometry of the tool. Such simulation algorithm provides a solid base for prediction of cutting forces along tool path and for optimization of NC part program via feedrate scheduling. Presented methodology is tested in milling operations for machining of planar contours with flat end-mills, and some illustrative results are shown

Verifikacije procedure predikovanja sila pri obradi cilindričnim vretenastim glodalima

U konceptu virtuelne obrade (VM), bitnu funkciju predstavlja predikovanje sila duž programirane putanje. To je važno kako za ocenu projektovanog tehnološkog procesa, tako i za njegovu optimizaciju, kroz off-line podešavanje parametara obrade. U radu je primenjen makromehanički model sila rezanja i procedura predikovanja trenutnih vrednosti sila glodanja, zasnovan na simulaciji obrtanja alata diskretizovane rezne geometrije. Obavljena je procedura eksperimentalne identifikacije specifičnih sila rezanja. Poznati simulacioni model je unapređen detaljima koji se odnose na radijalno bacanje sečiva alata i na složenije mape zahvata. Eksperimentalno je potvrđen kvalitet predstavljene procedure kroz skup reprezentativnih primera obrade

Synthesis and analysis of the tool dynamometer for turning operations

Virtual manufacturing has predicting of cutting forces in prepared program for CNC machine tool as one of the most important functional block. Development of reliable models of cutting forces requires appropriate sensor technique. It’s application is needed in building of data base with specific cutting forces, as well as for evaluation of developed models of cutting forces. Wide use of superior piezo-electric tool dynamometers is significantly reduced because its very high price. Paper presents development of the three- component tool dynamometer with strain gauges. Basic shape of this dynamometer is well known double extended octagonal ring (DEOR). Geometric parameters of the dynamometer body is optimised through FEA analysis. Designed dynamometer achieves partial decomposition of force components. Completing of such force decomposition is realized through decomposition matrix, created using FEA environment

Functions for processing of wokpiece CAD model for prediction and optimization of milling process

This paper deals with specific presentation of wokpiece volume and with functions for manipulating them in order to extract necessary data for various functions in virtual manufacturing environment. Basic idea was to use standard STL output of created model of blank material and convert to Z-map model. Functions for simulation of material removal process and extracting of geometry of instant tool immersion conditions are developed in Matlab environment. Exacting of engaging (tool immersion) map along discretized tool path is of great importance for application of model for instant cutting forces, based on simulation of discetized cutting geometry of the tool. Such simulation algorithm provides a solid base for prediction of cutting forces along tool path and for optimization of NC part program via feedrate scheduling. Presented methodology is tested in milling operations for machining of planar contours with flat end-mills, and some illustrative results are shown