MODELING THE FRONTAL TILT ANGLES AND SIDEWAYS IN THE MILLING PROCESS WITH SPHERICAL HEAD USING A 3D GRAPHICS PROGRAM

Transcription

1 BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI Publicat de Universitatea Tehnică Gherghe Asachi din Iaşi, Tmul LX (LXIV), Fasc. 3, 2014 SecŃia CONSTRUCłII DE MAŞINI MODELING THE FRONTAL TILT ANGLES AND SIDEWAYS IN THE MILLING PROCESS WITH SPHERICAL HEAD USING A 3D GRAPHICS PROGRAM BY OVIDIU TOADER RUSU 1, OCTAVIAN LUPESCU 2 and ADRIAN CIPRIAN BĂLAN 2 1 University Ştefan cel Mare f Suceava, Department f Mechanics and Technlgies 2 Gherghe Asachi Technical University f Iaşi, Department f Machine Manufacturing Technlgy Received: Nvember 10, 2014 Accepted fr publicatin: Nvember 24, 2014 Abstract. Milling prcess with spherical head is widely used in aernautical industry fr machining f cmplex shapes and in manufacturing industry fr machining cmplex surfaces f dies and mulds. One reasn except the capability f machining mre cmplex surfaces is the pssibility t cut material with a tl having the axe different than the nrmal directin t surface. In this way we can avid zer cut speed at tl tip and ensure predictin f the cutting tl life and the machined surface higher quality. There are simple relatins used t calculate tilt angle frntal and sideways, but fr study the effect f these parameters assciated t machined surface quality we need a mre cmplex mdel. Using a 3D CAD sftware we can find the value and the real psitin f the cntact area between cutting tl and the machined surface material. In same time we get the radius f the pint n the cutting edge with the maximum rtatinal speed, related t the axial depth f cut and tilt angles frntal and sideways. Key wrds: tilt; lead; ball end milling. Crrespnding authr; rusu.@fim.usv.r

2 40 Ovidiu Tader Rusu et al. 1. Intrductin Fr a milling cutting prcess with SPHERICAL HEAD using a 3D CAD sftware, generated mdel fr different frntal tilt angles are presented in Figs. 1,,6. Fig. 1 3D CAD mdel with zer tilt and lead. Fig. 2 Ball end milling with tilt angle (uncut chip). Fig. 3 Ball end milling with lead angle (uncut chip). Fig. 4 Ball end milling with tilt and lead angle (uncut chip). Fig. 5 Psitive and negative tl tilt angle. Fig. 6 Psitive and negative tl lead angle.

3 Bul. Inst. Plit. Iaşi, t. LX (LXIV), f. 3, As we see in Figs. 2,,4, fr different tilt and lead angles uncut chip vlume is identical, fr identical axial depth f cut and feed per tth. In 3D mdelling uncut chip area desn t depend n technlgical parameters such as: spindle speed, cutting directin (up r dwn milling), lead and tilt tl angles. Instead changing tl lead and tilt angle will vary entrance and exit angles in cutting zne related t axial psitin f pint n the cutting edge. As is knwn due t changing value f lag angle with the axial depth f cut nt all the pints n the cutting edge will enter in cutting zne at the same time. Related t tl axis pints n the cutting edge with same elevatin n tl axis, have different cutting speeds fr different lead and tilt angles (Yamada et al., 2007; Ozturk et al., 2009). 2. Radius and Speed fr Pints n the Cutting Edge A change f psitin radius f different pints n cutting edge fr milling with cnstant feed per tth and cnstant radial and axial depth f cut is presented in Figs. 7,,13 (axial depth f cut = 0.5 mm, cutting tl radius = 8 mm, tilt (left/right) = ( ), lead (frnt/back) = ( ) and cumulated in Fig. 14: Fig. 7 Lead angle frnt 15, tilt (left/right = -15,-10,-5, 0, +5, +10, +15 ). Fig. 8 Lead angle frnt 10, tilt (left/right = -15,-10,-5, 0, +5, +10, +15 ). Fig. 9 Lead angle frnt 5, tilt (left/right = -15, -10, -5, 0, +5, +10, +15 ).

4 42 Ovidiu Tader Rusu et al. Fig. 10 Lead angle = 0, tilt (left/right = -15, -10, -5, 0, +5, +10, +15 ). Fig. 11 Lead angle back -5, tilt (left/right = -15,-10,-5, 0, +5, +10, +15 ). Fig. 12 Lead angle back -10, tilt (left/right = -15, -10, -5, 0, +5, +10, +15 ). Fig. 13 Lead angle back -15, tilt (left/right = -15, -10, -5, 0, +5, +10, +15 ). Fr a pint A n the cutting edge with elevatin related t tl tip z = a, n rt / min, ω rad / s, AD= diameter f tl fr z ( mm), R = ball radius ( ) ( ) A p A b we define cutting speed with relatin (1):

5 Bul. Inst. Plit. Iaşi, t. LX (LXIV), f. 3, AD π n AD VA = VD = ω = = π n ap 1 m = Rb sin acs 1 30 Rb 1000 s (1) If we rtate tl axis related t tl tip with lead (l) r tilt (t) angle radius fr pint A turn int AE (frm AD/2) and cutting speed fr pint A is given by relatin (2). Fig. 14 Changing f psitin radius fr axial depth f cut = 0.5 mm, cutting tl radius = 8 mm, tl tilt (left/right) = ( ), lead (frnt/back) = ( ).

6 44 Ovidiu Tader Rusu et al. ( κ ) sin( κ ) ( ) ( ) AE = Rb cs 90 + l = Rb + l l r t π n a p 1 VA = ω AE = Rb sin a cs 1 l 30 + R b 1000 AD whereκ is immersin angle sinκ = 2 Rb (2) Relatin (2) with values btained frm Fig. 14 can be used t calculate real cutting speed fr pints n the cutting edge at different tilt and lead angles f tl axis. 3. Cnclusins 1) Related t tl tip as we change tls angles: lead frm 0 t +15 in feed per tth directin, radius f extreme pint n the cutting edge increase frm 2.78 mm t 4.32 mm; lead frm 0 t -15 ppsite t feed per tth, directin radius f extreme pint n the cutting edge decrease frm 2.78 mm t 2.32mm. Gemetrically is recmmended t change tl angle in feed per tth directin (frnt): tilt frm 0 t +15 in radial depth f cut, radius f extreme pint n the cutting edge decrease frm 2.78 mm t 2.4 mm; tilt frm 0 t -15 ppsite frm radial depth f cut, radius f extreme pint n the cutting edge increase frm 2.78 mm t 4.85 mm. Gemetrically is recmmended t change tl angle ppsite frm radial depth f cut directin (left). 2) Analyzing extreme psitin f cutting area fr feed per tth frm -15 t +15 and fr radial depth f cut frm -15 t +15 we have graphical presentatin in Fig. 15: frnt15 frnt15 5,69 3,69 R= mm R= mm left15 right15 frnt / back 0 R 2,78 mm = left / right 0 back15 back15 R 5, 28mm R 3,30 mm = = left15 right15 Fig. 15 Radial psitin f a pint n the cutting tl edge fr different lead and tilt angles.

7 Bul. Inst. Plit. Iaşi, t. LX (LXIV), f. 3, S strictly frm gemetrical pint f view is recmmended t increase cutting speed by changing tl angle frward and left. REFERENCES Yamada M., Knd T., Tanaka F., Kishinami T., Tilted Tl Axis Machining n 5-Axis Machine Tls. Int. J. f Autmatin Technlgy, 1, 2, , Ozturk E., Tunc L.T., Budak E., Investigatin f Lead and Tilt Angle Effects in 5-Axis Ball-End Milling Prcesses. Internatinal Jurnal f Machine Tls & Manufacture, 49, , MODELAREA UNGHIURILOR DE ÎNCLINARE FRONTALĂ ŞI LATERALĂ ÎN PROCESUL DE FREZARE CU FREZĂ CU CAP SFERIC FOLOSIND UN PROGRAM DE GRAFICĂ 3D (Rezumat) În timpul experimentelr la frezarea cu freză cu cap sferic pe maşinile cu trei axe s-a bservat, pentru regimuri de aşchiere nrmale, diminuare drastică a durabilităńii sculei şi uzură până la disparińie, a stratului de prtecńie depus, la vârful sculei. Acestea sunt datrate efectului de viteză nulă de la vârful sculei cu transfrmarea fenmenului de aşchiere în frecare de alunecare. Scpul studiului cnstă în creşterea durabilităńii sculei prin înclinarea acesteia şi implicit studiul efectului parametrului înclinare asupra îmbunătăńirii calităńii suprafeńei prelucrate. S-a demnstrat strict gemetric flsind un prgram 3D că este recmandat să înclinăm scula în sensul avansului şi înspre stânga pentru a creşte viteza de aşchiere. Ne prpunem să verificăm rezultatele tretice cu cele bńinute cncret în practică flsind un plan de experienńe.