The Monitoring of Machining Inherent

Transcription

1 Th Monitoring of Machining Inhrnt Ján Žitňanský, Jozf Žarnovský, Vladimír Kročko, Rastislav Mikuš Abstract: A contribution discusss about an analysis of th physical ffcts and gomtric accuracy, as wll as th roughnss of a machind surfac during th cutting procss with us of rplacabl cutting blads. W study achivd paramtrs at lath-cutting of stl catgory Chosn matrial is charactrizd in high hardnss which causs problms at its machining. Surfacs ar hardnd and carbonizd that affct th usag of chosn mthod in trms of dfind paramtrs such as cutting dpth and also fd. Evaluation of cutting blads is dpndnt on spcifid paramtrs to b achivd at th matrial machining. Kywords: physical ffct, accuracy, surfac roughnss, hardnss, cutting paramtrs Introduction Objctiv of th study is an valuation of th surfac quality, dimnsional accuracy, and hardnss, rachd tmpraturs at changing fd. Achivd rsults of ach rplacabl cutting plat in laboratory conditions ar also valuatd. Th nvironmntally frindly and fficint manufacturing procss is rquird. Suitabl cutting insrt has to b slctd along with appropriat conditions for th cutting dpth a p = 0.5 mm. An xprimnt dals with th assssmnt of cutting procss at machining, particularly at lath-turning using various cutting insrts which ar rcommndd by diffrnt manufacturrs. Slction of matrial is basd on th matrials suitabl for shifts production, xposd to shar strss. Sampls ar mad from th stl catgory which is carbonizd and hardnd to 55±2 HRC at functional surfacs. 2. Mthodology Charactristics and prparation of sampls Th sampl is mad from stl which is suprior, low alloyd stl suitabl for carbonizing with vry hard carbon layr, with high strngth in cor. Th matrial is in form of cylindrical bar. Th chmical composition is dtrmind in Slovak standard STN , with following lmnts contnt: C = %, Si = %, S = max %, Mn = 1 4 %, P = max %. insrts Charactristics of cutting insrt CNMG ER 6630 insrt CNMG ER 6630 (Pramt) is univrsal matrial that is usd for stl lath-turning. It can b also usd for machining of cast iron and stainlss stl. It is charactrizd in good war rsistanc and high toughnss. Th cmntd-carbid compositions coatd at middl tmpratur MT CVD procss is markd by four-digital cod. Charactristics of cutting insrt DNGA DISAL 210 insrt DNGA DISAL 210 is a cutting cramics which is basd on th oxid bas Al2O3+TiC. Cmntd corundum is charactrizd in high hardnss compard to cmntd-carbid compositions, high war rsistanc at high tmpraturs (up to C) and high cutting spds up to 400 m.min -1. Masurmnt of th dimnsional accuracy Dimnsional accuracy along with th surfac roughnss is th basic charactristics of th surfac quality. A digital micromtr MITUTOYO was usd for th dimnsional accuracy s masurmnt. Th digital dvic s masuring rang is mm and masurmnt accuracy mm. Rsultd diamtrs wr masurd thr tims for

2 ach sampl aftr lath-turning. Prsntd valu is th arithmtic man of all thr masurd valus. Tmpratur masurmnt Th main lmnt for tmpratur masurmnts is a thrmocoupl, working on a principl of th thrmolctric ffct. Th voltag is gnratd at th nds of conductors whn two conductors of diffrnt mtals ar hatd. Th voltag is dirctly proportional to th avrag tmpratur at th contact point of thos conductors. Th gnratd thrmolctric forc is proportional to avrag tmpratur at contact point of machind and cutting matrial. Masurmnt of hardnss Masurmnt of th hardnss is prformd according to th standard STN ISO This standard spcifis th tchniqu of Rockwll hardnss s masurmnt. A principl of th mthod is to forc a diamond con with th apical angl 120 into a surfac of tstd matrial. Thn a prssur mark lft on surfac is masurd. Tsting body is wightd down by th static forc F 0 = N bfor th masurmnts. So it ntrs into dpth h 0 of tstd matrial. It thrby liminats th ffct of surfac which is xposd to a prvious procssing. Masurmnt of roughnss A dvic SURFTEST 301 was usd for masurmnts. Following roughnss was masurd by th dvic: Ra arithmtical avrag dviation from a man lin, µm 3. Rsults Fd of machind matrial had bn changd at ach xprimnt on th basis of th dcidd mthod. Valus of fd ar shown in tabl Tabl 1 Valus of fd for ach sampl Sampl Fd (mm) Sampl No mm Sampl No mm Sampl No mm Sampl No mm Sampl No mm Othr dfind paramtrs: cutting dpth a p 0.5 mm diamtr of th sampl D 40.5 mm spindl rv. 710 min -1 cutting spd v c 89 m.min -1 Masurd valus of dimnsional accuracy at lath-turning at cutting dpth a p = 0.5 mm and cutting spd v c = 89 m.min -1 ar shown in th tabl 2. Tabl 2 Dimnsional accuracy at lath-turning Rachd diamtr, mm Dviation from th lath diamtr, mm No. of th sampl spd, m.min -1 Fd, mm Lath diamtr, mm DNGA CNMG ER 6630 plat DNGA CNMG ER

3 0.5 m 0.48 [m n tio 0.46 ia v d0.44 r t m0.42 ia d 0.4 Graph of th dimnsional accuracy?s dpndnc on th fd DNGA fd [mm Figur 1 Graph of th dimnsional accuracy s dpndnc on th fd Masurd valus of tmpratur at lath-turning at cutting dpth a p = 0.5 mm and cutting spd v c = 89 m.min -1 ar shown in th tabl 3. Tabl 3 Tmpratur at lath-turning No. of Rachd tmpratur [ C Fd, th spd, sampl m.min -1 mm Graph of th tmpratur dpndnc on th fd [ C r tu ra p m t fd [mm Figur 2 Graph of th tmpratur dpndnc on th fd Masurd valus of roughnss at lath-turning at cutting dpth a p = 0.5 mm and cutting spd v c = 89 m.min -1 ar shown in th tabl DNGA T03020 N

4 No. of th sampl spd, m.min -1 Fd, mm Tabl 4 Roughnss at lath-turning Rachd roughnss Ra [μm Sandvik Coromant Pramt Tools Graph of th roughnss?s dpndnc on th fd a [R s n h g u ro 1,4 1,2 1 0,8 0,6 0,4 0,2 0 fd [mm DNGA T03020 N Figur 3 Graph of th roughnss s dpndnc on th fd Masurd valus of hardnss at lath-turning at cutting dpth a p = 0.5 mm and cutting spd v c = 89 m.min -1 ar shown in th tabl 5. Tabl 5 Valus of hardnss HRC aftr lath-turning No. of Rachd hardnss [HRC Fd, th spd, sampl m.min -1 mm Conclusion Th objct of th xprimnt was to analys rplacabl cutting plats CNMG ER 6630 and DNGA , and also th rachd paramtrs at lathturning of th matrial - stl of catgory Slctd matrial is charactrizd in high hardnss which is on of th difficultis at its machining. Th surfacs wr carburizd and hardnd that influncs th mthod of lath-turning in trms of dfind paramtrs such as th cutting dpth and fd. Evaluation of thos cutting plats dpnds on dfind paramtrs which had to b rachd at matrial machining. Assssd critrion can b th roughnss as wll as th dimnsional accuracy. Effct of th tmpratur and hardnss

5 must also b considrd. Dtctd quality of ach surfac shows that som opration will b rplacd in th futur. Rduction of ths oprations will rsult in lowr costs for machining. An application of manufacturing mthods will liminat th tim lost that is causd by a product transfr btwn dvics, and also th tim lost causd by a clamping C R 57 [H s 56 n 55 rd a h Graph of hardnss s dpndnc on th fd DNGA CNMG ER 6630 fd [m m Figur 4 Graph of hardnss s dpndnc on th fd REFERENCE [1 BÁTORA,B-VASILKO,K.: Obrobné povrchy, Trnčianska univrzita, Trnčín 2000, str , str [2 BÁTORA, B Strojárnská tchnológia II. časť, Nitra : SPU 1995, s. [3 KREIDL, M : Měřní tploty snzory a měřicí obvody. vydání.praha: Martn 2005, 240 s. ISBN [4 KROČKO, V. TOMÁŠ, J Smry vývoja tchnológi obrábania z hľadiska kológi. Mdzinárodná vdcká konfrncia MF SPU. Nitra 1999, 123 s. [5 TOMÁŠ, J. KROČKO, V. DRLIČKA, R Tchnológiou tvrdého sústružnia k zvýšniu kologizáci výrobného procsu. Nové smry vo výrobných tchnológiách. Pršov 1999, s. [6 TOMÁŠ, J. KROČKO, V. DRLIČKA, R Suché sústružni ako kologická tchnológia obrábania tvrdých matriálov. Tchnológia 99. Bratislava 1999, s. [7 Krastv G., Kangalov Pl., Rsarch on th rat of coating iron with Hull cll, Rus: PB at Rus Univrsity A. Kanchv, 2006, Vol. 45 p Contact Ján Žitňanský: Dpartmnt of Quality and Enginring Tchnologis, Faculty of Enginring, Slovan Univrsity of agricultur in Nitra, -mail: jan.zitnansky@uniag.sk