machine design, Vol.7(2015) No.2, ISSN pp

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1 macn sgn, Vl.7(05) N., ISSN Orgnal scnfc ar ETEINATION O THE OST AVOUABLE ICTION OENT O SCEW TIGHTENING avl KOVAC, * - usan JESIC - Brslav SAVKOVIC - arn GOSTIIOVIC Unvrsy f Nv sa, aculy f Tcncal Scncs, Nv Sa, Srba Trbnk, 5000 jka, Tv rg 6/4, Hrvaska cv ( ); vs ( ); Acc ( ) Absrac: In ar rsn s rcur fr rmnan f rcal valu f gnng mmn a rrsns sum f cung rssanc mmns n ras an frcn rssanc mmn n cnac zn f lwr frn surfac f nu an sm, namly n lanng surfac f nu. Bss gnral quans als s gvn rvw f xrssns fr gnng mmn w scrw a as nu w aralll lanng surfac. rsn s as wll sgn xrmnal vc fr suy f scrws an nus. asur wr frcn cffcn an frcn mmn. In xrmnal rgram w us scrw 0,, 4 an 6. T magnu f gnng frc a bgnnng f xrmnal rgram was rmn accrng Tcrmann. Invsgan rsuls sw a frcn cffcns n ra an bwn nu an larnng surfac ar n rang 0. an 0.6 nng n ra amr. T cc f mal frcn mmn f scrw gnng s ssbl rfrm bas n rsuls ban by ralzan f aqua xrmnal rgrams f s kn. Ky wrs: frcn mmn, frcn cffcn, xrmnal, scrws, nus.. INTOUCTION Unr cnc f "frcn" s unrs n a wr sns, rcss f sng mvmn f by. Ts sn mvmn f by can b masur by frman f nvrnmn n wc by mvs r urng labr ncssary fr mvmn ralzan[,]. rcn as mull alcans, an srvs scal ann suyng an analyzng n cnqu[]. On xaml s nmnn f frcn n ras an unr nu. In ry f bsrv rlans f gnng rqu bwn scrw r s nu, an assmbly frc sars frm gmrc sz f scrw cnncn an cffcn f frcn n ras an unr nu. Tgnng scrws r nus sll n s assmbly frm s rssancs a grw mr f gnng s gr. T rssanc frcn s ccurrng n ra scrws an nus an blw nus n gnng surfac.. ETEINATION O THE ICTIONAL ESISTANCE WHICH OCCUS BETWEEN NUTS AN SUACE gur sws axal crss-scn f scrw an nu w squar ra crss-scn. In cas f gnng nu, gnng rqu ( ) s ruc f frc ( a ) n arm, masur frm ky ns f aack frc (L) axs f scrw[4,5]. Tgnng nus n scf rqu rcn ( ) ccur n n (c) acv frc ( ), wc arss frm xrnal rqu ( ) an ( ), wc ccurs alng scrw, als knwn as munng frc, wc causs gnng sran f scrw, an n nu sran f rssur[6,7]. In an acv frcs ccur n n (c) racn frc ( N ), wc acs rncular surfac f ra an frcn rssanc ( ), wc ccurs n lan ra ucng surfac, bu s rcn f slng. T wl sysm s n frc s balanc f rsulan acv frc s qual rsulan racn frc, r wn =. rm gur l. s vn a r s a rlans bwn an. Equan () rrsns sz f rqu wrnc wc vrcms frcn rqu f ra scrw an nu. Ts mmn ns n gmrcal sz f scrw an ras c (), scnary ra amr ( ), n munng frc ( ) a w wan accmls n a scrw cnncn an a n, f sz f frcn cffcn (µ ) a xss n cnac surfacs rang scrws an nus. In mrc ra rfl s n squar bu qularal rangl. Trfr, a mmn f fnng frcnal rssanc n wnngs, wc vrcm xrnal rqu ( ), w us f g, rsul fllwng rlanss: y cs ; y sn () *Crrsnnc Aur s Arss: Unvrsy f Nv sa, aculy f Tcncal Scncs, Trg sja Obravca 6, 000 Nv Sa, Srba, kvac@uns.ac.rs

2 avl Kvac, usan Jsc, Brslav Savkvc, arn Gsmrvc: rmnan f s avurabl rcn mn fr Scrw Tgnng; acn sgn, Vl.7(05) N., ISSN 8-59; g.. Tgnng f nu w squar crss scn ras g.. Tgnng f nu w mrc ras Nw can b wrn a s n rcn y-y ( Y 0 ); y y Ny 0 Ny y y cs sn rm wn scn f mrc ra n rcn (y-y), vrcal la n s rfl ( N ) s qual : Ny cs sn N cs cs T frcnal rssanc v s qual ruc f vrcal racn frc ( N ) an frcn cffcn (µ ): 6 N cs sn cs / lans bwn angl (α/) an angl (α/) s rmn frm gur : an b ; an T rsulng quan (): cs / cs an ; / cs rrsns rv (µ ) frcn cffcns a crrsnng an(ρ) (angl ρ n gur ). b ()

3 avl Kvac, usan Jsc, Brslav Savkvc, arn Gsmrvc: rmnan f s avurabl rcn mn fr Scrw Tgnng; acn sgn, Vl.7(05) N., ISSN 8-59; rm gur w can sabls fllwng rlans: an / an mn crcumfrnal frc rrsns als frcn rqu n ra, a s: an an an an an () rcn rqu n ras wn clamng s qual : (4) By analgy rfrmng frcn rqu ( ) fr gnng nus, rfrm was frcn rqu fr unscrwng nu, barng n mn a frcnal rssanc s nw rc s rcn f slng nus: an (5)..: (6) rm quan () s ssbl calcula sz f rv cffcn f frcn (µ ): (7).. Analyss f frcnal rssanc unr nu gur sws ffrnal f frcn rssanc ( µ ), wc aacks ffrnal f nus surfac A = ρ ρ φ g.. rcn rssanc ffrnal T rssur n nu: A ffrnal f vrcal frcs: N = A = ρ ρ φ ffrnal f frcnal rssanc: µ = N µ (µ - cffcn f frcn a nrfac f nus an subsra). ffrnal frcn rqu: T al frcn rqu n surfac f nu: 0 0 (8) If subsun: = an = wll b: Nm (9) rm quan (9) can b calcula sz f frcn cffcn (µ ): (0).. rmnan f cffcn f frcn µ an µ Equan (7) can b wrn n fllwng frm: C B A () wr s: A= /(π), B= /, C=/(π ) Equan (0) can b wrn n fllwng frm: µ = E () Wr s: E In rr rmn sz f cffcn f frcn usng quan () an () was ncssary mak suc a vc wc cul masur munng frc ( ) vrsus mmn f frcn ( ) an ( ) an al gnng rqu [8,9]. r gmrc sz f scrws an nus was n ffcul bcaus y ar usually sanar sz, rscrb by JUS. T vc cnsss f fllwng ars, gur 4: - scrw sgn fr sng; - nu scrws; nrcangabl a a macs sz f scrw; 4- mmuabl a; 5- w axal rllng barng, y 5; 6- rng clam arm w a sz f 00 mm; 7- w ra sus lac n rack 6 an carrr 9; 8- w nus n bls 7; 9- sck (sn); 0- w annular sal; - by yraulc vcs; w rng sals; - cllar

4 avl Kvac, usan Jsc, Brslav Savkvc, arn Gsmrvc: rmnan f s avurabl rcn mn fr Scrw Tgnng; acn sgn, Vl.7(05) N., ISSN 8-59; rvn ran f scrw; 4- cylnrcal fxng n rn (); 5- nu; 6-bl clams fr clamng rng (6); 7- ynammr "Tmann" H 685; 8- w scrws fr fxng carrr 9; 9- ynammr qumn (7); 0- ra l n wc s scrw a rssur gaug; -bl w nu (4 cs) fr fasnng srng ; - cllar wc s lac nsa f ar (5); - cylnrcal n wc s scul bu unus. g. 4. vc fr xrmnal nvsgans f scrws urng suy bm f vc was clam w an clam. Scrw (s s. ) s lac unr an rug rng an br nrcangabl a an s gn w nu. Tgnng f nu s acv w rqu frc (). Trug l Ø 0 s ur lqu fr yraulc brak y "INA - UKA ". Wn s br w ra 0 gn manmr sr n gnng scrws, r s nu, causs mr rssur n flu unr r 9 f s grar gnng f nu. If r was n frcn bwn r an rng sals an 0, valu f assmbly frc scrw cnncn wul b qual ruc f rssur. Bu w s frcn s sul n b gnr, was ma rr calbran f yraulc qumn crf sng macn w 400 kn. In rr acv rqu f ( n ), wc vrcms frcn rqu f ra nu an scrw rv ar w axal rllng barngs 5. ng clams 6 s gn acrss nrnal barng 5 an av arm sz f 00 mm. A n f arm s n 7 by wc s aac a ynammr 7, wl s r arm aac carrr 9. Tgnng nu, wc rss n a rmvabl a, caus a cmmn ran an rng f rllr barng 5. ssanc unr nu s n ccur bcaus nu ras gr w ur barng rng 5. Hwvr, frcn n rllr barngs 5 xss an causs ran f arm clams 6 an rby 8

5 avl Kvac, usan Jsc, Brslav Savkvc, arn Gsmrvc: rmnan f s avurabl rcn mn fr Scrw Tgnng; acn sgn, Vl.7(05) N., ISSN 8-59; causs n ynammr 7 nsfar ( N ) grar frc f frcn rqu n barngs 5 gr. Sz f frcn rqu n rus barngs 5 s rmn by mullyng frc n ynammr arm ( n ) an arm clam (b): b. = n b T ban frcn rqu n ras ( ) nly, ncssary s frm rqu n ky ( + b. ) subrac frcn rqu n barngs ( b ). =( + b. )- b. T rvn ran f r 9 ar w laf srngs n acrss sn, s y ar b aac n n f r 9, wl r n n by vc. T w laf srngs rcv n mslvs ar f gnng rqu an n aar w nsn frcs muually an aralll, an acng n lan rncular axs f scrw. u vry small sffnss f laf srngs, an bcaus f vry ll mvmn f r u ncmrssbly an lqus (as cnfrm by masurmns) cran lms ss - 50 bar - can b cnsr b caus by frc f laf srngs raccally nglgbl, s swn an sng sffnss laf srngs. In rr ban vrall gnng rqu ( ), s ncssary rlac wasr barngs 5 w rng a can b aac rmvabl rng, accrng sz f scrws l. Bcaus bas rng s aac by 9 by ns (n swn n g 4), bwn nu an aars frcnal rssanc wn urnng nu. Tgnng nu, arss vrall gnng rqu ( ), wc can b ra n rqu wrnc a nclus frcn rqu n nu ( ) an frcn rqu blw nu ( ): = + If fr sam assmbly frc nus ar gnng fr w cass: wn r ar a barng 5 blw, an wn r ar mssng, r s bas rng, n s ssbl g frcn rqu unr nu ( ) usng fllwng quan: = -.. Exrmnal sng f scrws T rmn valu f frcn cffcn n ra ( ) was ncssary xamn 5 scrws mnsn l0,, 4 an l6. r ac sz f scrw was frs rmn sz f assmbly frc ( max ) accrng Tcrmann: z Av max () Wr s: z = v / v N/mm (4) v = yl srng f scrw maral fr 0 : v =400; fr, 4 an 6 : v =640 (N/mm ) v = cffcn f safy v =.4 fr 0 ; v =. fr an 4 ; v =. fr 6 A 4 (5) = amr f ra cr = c amr Bas n quans (), (4), (5) rmn ar valus f munng frc fllwng: = 0400, 8700, 9800 an N, fr 0,, 4 an l6 rscvly. T masur valu f rqu ( ) us was rqu wrnc fr a rang u 00 Nm, scally calbra usng wgs frm N, wc ar ung a n f rqu wrnc (anls), ws arm was 40 cm. Tabl l. gvs sascal analyss f mmn f wg (x) an ra aa n cmarar rqu wrnc (y). T valus n Tabl rfr cas wr cnsrans f rqu wrnc wr lac n a scal f 00 Nm. Bas n abv abl rmn ar fllwng valus: T man valu f varabl x: 7840 x x 87. N 9 T man valu f varabl y: y 54.8 y 57. N 9 T sl m: x y x y m x x x T cu-f n y-axs: b y m x Equan rcn wll nw v: y = m x + b = x -.0 If nsa f (y) u numbr f aa n cmarar rqu wrnc (N) nsa f (x) gnng rqu ( ), w ban fllwng quan fr ( ) as a funcn f numbr f aa (N): N.0, fr 00 (6) Tabl. N x y (x- x ) (x- x ) (y-ȳ) (y-ȳ) x y x y

6 avl Kvac, usan Jsc, Brslav Savkvc, arn Gsmrvc: rmnan f s avurabl rcn mn fr Scrw Tgnng; acn sgn, Vl.7(05) N., ISSN 8-59; On bass f quan (6) w ar abl rlas any nfrman n cmarar g acual valu f gnng rqu.. IGUES EASUING O THEA ICTION COEICIENT (µ ) asurmns wr carr u fr vry 5 aa f masur frc sarng frm aa n gaug. v masurmns wr n fr vry scfc aa. Hr ar a fw valus: fr n valu f frc = 5800 (N), sx valu s = 8700 (N), an n unr an ffy valu s = 6700 (N). r xaml, f rmnan f cffcn f frcn (µ ) n 0. 0 scrw a b u n nu as nca n gur 4. Tgnng w rqu wrnc ( ) vrcm frcn rqu n ras.. mmn f rssanc n rllng barng. rcn rqu f rllng barngs s masur usng a ynammr (7) n wc cmarar was ra valu f frcn rssanc frc n rllng barngs. Ts frc s mull by arm clams (6), wc amun 00 (mm). rcn rqu n ras was rmn, rfr, wn al rqu n rqu wrnc subsrac frcn rqu n barng. A gmrcal sz n quan () gvs sz f cffcn f frcn n ras (µ )... T valus f nu cffcn f frcn (µ ) Insa f rllng barngs was lac wasr (). Wn gnng wl nus n scf munng frc ( ), wc was masur n rssur gaug vcs, acv gnng rqu ( al ), wc n slf nclus frcn rqu n ras, r frcn rqu unr nu. T g jus sz f frcn rqu unr nu s rqur frm al rqu ra n rssur gaug ky ( al ), subrac frcn rqu n ra ( ): = al - Subsung sz ( ),, an r gmrcal szs ( an ) n quan () gvs sz f frcn cffcn unr nu (µ ). All valus f frcn cffcn (µ ) an (µ ) fr all 5 scrws, fr ac sz f scrws wr analyz by sascal m an man valus an sanar vans wr rmn [0]. T s rsuls gav fllwng valus f cffcn f frcn: µ = fr 0 x 0 mm; µ = 0.66 fr x 0 mm; µ = 0.4 fr 4 x 5 mm; µ = 0.56 fr 6 x 40 mm; µ = 0.06 fr 0 x 0 mm; µ = 0.45 fr x 0 mm; µ = 0.06 fr 4 x 5 mm; µ = fr 6 x 40 mm; CONCLUSION In s wrk, rcal valu f rqu ( ), bas n sum f frcn rssan rqu n ra ( ) an frcn rqu unr nu ( ) ar rmn, wc s xrss by quans (7) an (8). In an rv quans rvs an vrvw f quan fr gnng rqu ( ) f scrw wc as a nu a as a fla glu surfacs. r f munng frc valu n a yraulc vc n wc ar f xrmnal wrk was carr u s ssbl rfrm rrr u % snc s a vc calbra crf sng macn. T vc allws sng f scrws a maxmum amr f 0 mm, wa qu, cvr buss ara f scrw wc s al n mcancal ngnrng. On vc can b s scrws an r ras ffrn an mrc. In an, vc can b us fr sng macs f varus wasrs marals w ffrn surfac rugnss, an suy r ffc n frcn a scrw gnng. EEENCES [] Ivkvć, B.. (98). Osnv rblgj u nusrj rra mala, Građvnska knjga, Bgra. [] Glubvc,.; Kvac,.; Savkvc B.; Jsc,.; Gsmrvc. (04). Tsng rblgcal caracrscs f nular cas rn ausmr by a cnvnnal an an srmal rcur, arals an Tcnlgy, Vl. 48., N., [] Glubvc,.; Kvac,.; Jsc,.; Gsmrvc. (0). Trblgcal rrs Of A aral, Jurnal f Balkan Trblgcal Asscan, Vl. 8., N., [4] ckr K.H.. (99). ascnnlmn, Gsalung un Anwnung, 0. Auflag, Carl Hansr Vrlag, üncn/wn. [5] Nman K. H.. (97). Knsrukn m ascnn - aaral un Graban, rsnalsrag GmbH, uncn. [6] Obrsm, E. (98). Osnv knsrusanja, SB, Zagrb. [7] Vas,. (989). Osnv mašnsk knsrukcja, Naučna knjga. Bgra. [8] Kvač, ; ankva, ; Gsmrvć, ; Skulć, ; Savkvć B. (04). A rvw f macnng mnrng sysms, Jurnal f rucn Engnrng, Vl. 4., N.4,. -6. [9] Kvac, ; Gsmrvc, ; Jšc, ; Savkvc, B; Kulunzc, N. (04). T l Of aral Qualy Cnrl In rn anufacurng, Jurnal f rucn Engnrng, Vl. 7., N., [0] Jsc,. (000). Trblgcal rrs f Nular Cas Irn, ngray, Jurnal f Balkan Trblgcal Asscan, Sfa.