Analysis and optimisation of the needle transfer mechanism

5 ANALYSIS AND OPTIMISATION OF THE NEEDLE TRANSFER MECHANISM Ja osla Be an *Ka el Pejcha **Jiří Komá ek Technical Uni e si y o Libe ec Facul y o Mechanical Enginee ing Depa men o Design o Tex ile Machine S uden ská 2, 461 17, Libe ec 1, Czech Republic [email p o ec ed] *Technical Uni e si y o Libe ec Facul y o Mechanical Enginee ing Depa men o Design o Tex ile Machine S uden ská 2, 461 17, Libe ec 1, Czech Republic [email p o ec ed]z **Technical Uni e si y o Libe ec Facul y o Mechanical Enginee ing Depa men o Design o Tex ile Machine S uden ská 2, 461 17, Libe ec 1, Czech Republic [email p o ec ed] Abs ac The pape is conce ned wi h an analysis and op imisa ion o he needle ans e mechanism by means o he so wa e P o/Enginee Wild i e 4 wi h he aim o educe he noise a high . p.m. o he machine. The e has been ca ied ou an op imisa ion o selec ed pa ame e s o he mechanism wi h he aim o a e he ib a ion o he elemen ha con ols he momen o elease o he needle du ing i s ans e om one needle ba o he o he one. Subsequen ly, he e is ca ied ou a sensi i i y analysis o he e ec o designing pa ame e s o he mechanism upon he eloci y o impac o he con olling elemen upon he machine ame. On he basis o he esul s o he analysis and op imisa ion, he e ha e been p oposed modi ica ions o he design o he needle ans e mechanism, and subsequen ly, hey ha e been e i ied expe imen ally by measu ing he sound p essu e on a unc ional model. 1 In oduc ion The p esen end in he de elopmen o sewing machines is o sho en he sewing imes in he sewing p ocess and o inc ease he p oduc i i y. O he pa ame e s o he sewing machines manu ac u ed nowadays a e e.g. silen unning, minimum ib a ions, long se ice li e o employed mechanisms and easy ope a ion o he machine. The machine, a pa o which is he needle ans e mechanism, ope a es in he eloci y ange o 100 – 250 . p.m. A highe . p.m., he sewing machine p esen s conside able ib a ions and high le els o noise [2]. The objec o his pape is o analyse he needle ans e mechanism and o op imise i s dynamic beha iou , and subsequen ly, o ealise modi ica ions ha should esul in a educ ion o he noise gene a ed by his mechanism. 6 2 Analysis o he needle ans e mechanism The needle ans e mechanism ( ig. 1) o ms a pa o he sys em ha allows imi a ing he hand s i ch. I s ask consis s in p o iding o he ans e o he loa ing needle be ween wo needle ba s ope a ing abo e he wo k able o he machine and below i . The loa ing needle is clamped by colle s (i em 12) in he needle ba , owing o he p essing o ce o he sp ings, i ems 11 and 15. The unlocking o colle s is ac ua ed du ing he mo emen o he needle ba by impac o i s con olling elemen upon he machine ame be o e he dead cen e o needle ans e , whe e he impac is damped by a ubbe pad (i em 10). The s op block can be seen in he igu e 2. The jacke o he needle ba (i em 2) goes on mo ing o he lowe dead cen e and comple es he p ocess o he needle ans e . A ma hema ical model o he needle ans e mechanism has been de ised by means o he sys em P o/Enginee Wild i e 4.0 in he module Mechanism. The indi idual pa s o he needle ans e mechanism a e ep esen ed by means o igid elemen s. The igu e 1 shows he design o he needle ans e mechanism including wo sp ings. These wo sp ings a e simula ed by means o he unc ions SPRING and DAMPER. Ano he pliable elemen is he ubbe pad men ioned abo e al eady. This pad is simula ed by means o he unc ions FORCES and DAMPER. The mechanism o he needle ba and i s p ope unc ion a e p o ided by a sys em o s op blocks modelled by means o he unc ion CAM, which allows simula ing impac o bodies. The coe icien s o es i u ion ha e been adjus ed o such a alue ha he beha iou o he ma hema ical model would be as close as possible o he beha iou o he eal mechanism which has been examined by means o a as -speed came a. F igu e 1 Sec ional iew o he needle ans e mechanism F igu e 2 Newly p oposed c ank mechanism The needle ans e mechanism pe o ms he ec ilinea e e se mo emen ha has been ealised by a cam mechanism in he exis ing machine. The newly p oposed unc ional model o he machine consis s o c ank mechanism wi h se o-d i e con e ing he o a y swinging mo ion in o ec ilinea e e se mo emen – see igu e 2. In he ollowing diag am 1 he e is shown he dependence o he posi ion o he needle ba on he ime. The ime alue 0.24 sec. s op block 7 co esponds o one cycle o he needle mechanism o he machine egime o 250 . p.m. In he ollowing sec ion, we shall deal wi h he i s passage om he uppe posi ion o he needle ba o he lowe one, because in his a ea he e exis he highes alues o he accele a ion, and du ing his mo emen impac s and noise a e gene a ed in pa icula . The alues o s i ness o he sp ings K1 and K2, i ems 11 and 15, ha e been aken o e om he wo k [1]. The alues o in insic damping o he sp ings B1 and B2, i ems 11 and 15, and o in insic damping o he ubbe pad B3 ha e been aken o e om he wo k [3]. The esul ing alues o s i ness o he sp ings and hei in insic damping a e shown in he able No. 1 below. Dependency posi ion o needle ba on ime 410 415 420 425 430 435 440 445 450 455 460 465 0 0,03 0,06 0,09 0,12 0,15 0,18 0,21 0,24 ime (s) posi ion (mm) D iag am 1 Dependence o he posi ion o he needle ba on ime Table 1 Values o s i ness and in insic damping o he sp ings S i ness K [N/mm] In insic damping B [N.s/mm] Sp ing i em 11 0,899 0,013152 Sp ing i em 15 0,69 0,03322 Rubbe pad i em 10 - 0,0285 The model comp ises he pliabili y o he ubbe pad. The cou se o he o ce necessa y o he comp ession o he ubbe pad has been es ablished expe imen ally in he wo k [1]. In he eco d, he e can be seen he expec ed non-linea beha iou o he ubbe pad du ing i s comp ession. The cou se o he ac ing o ce has been app oxima ed by a polynomial o hi d deg ee (1). 246,111,2364,1515693,79)( 23 +++−= xxxxF (1) Inc eased . p.m. o he machine a e accompanied wi h ib a ions o he con olling elemen o he needle ba ha con ols he momen o elease o he needle du ing i s ans e om one needle ba o he o he one. The ib a ions b ing an inc ease o he impac eloci y o he con olling elemen as a consequence, and hence, an inc ease o kine ic ene gy a he impac on he machine ame. This phenomenon has an ad e se e ec upon he se ice li e o he pa s, and na u ally, upon he noise le el o he mechanism. F om he e ec ed analysis he e ollows ha he exis ing sp ings o he mechanism a e no dimensioned o high . p.m. o he machine su icien ly. The diag am 2 displays he eloci ies o he jacke o he needle ans e mechanism and he eloci ies o he con olling elemen o wo di e en egimes. A he 8 ope a ing egimes up o 160 . p.m., he ib a ions o he con olling elemen do no come up ye , and a he egime 250 . p.m., he di e ence o he eloci ies o he jacke and o he con olling elemen is ∆ = 0.56m/s. The impac eloci y o he con olling elemen a ains he alue 2.68m/sec. in his case. ‐2750 ‐2500 ‐2250 ‐2000 ‐1750 ‐1500 ‐1250 ‐1000 ‐750 ‐500 ‐250 0 250 500 750 1000 1250 1500 0 0,0025 0,005 0,0075 0,01 0,0125 0,015 0,0175 0,02 0,0225 0,025 0,0275 0,03 0,0325 0,035 0,0375 0,04 Veloci y[mm/s] Time[s] Veloci yo  hejacke o needle ans e mechanism(160 .p.m.) Veloci yo  hecon olelemen (160 .p.m.) Veloci yo  hejacke o needle ans e mechanism(250 .p.m.) Veloci yo  hecon olelemen (250 .p.m.) D iag am 2 Time beha iou s o eloci ies o he elemen s o he needle ans e mechanism o he egimes 160 . p.m. and 250 . p.m. 3 Op imisa ion o he s i ness o he sp ing o he ans e mechanism The ib a ions o he con ol elemen o he ans e mechanism a e in luenced by he s eng h o he sp ing i em 11 - ig. 1 p ima ily. By inc easing he s i ness o his sp ing, i is possible o supp ess he ib a ion o he con ol elemen , hus educing he di e ence in eloci ies o he jacke and o he con ol elemen . Howe e , he p oduced s eng h o he sp ings mus no be oo high; o he wise, he se o-mo o d i ing he c ank mechanism would ha e o gene a e a highe o que in he lowe posi ion o he mechanism. By means o a ma hema ical model, he e has been ound such a alue o sp ing s i ness a which no ib a ions o he con olling elemen migh occu o he egime 250 .p.m. By he e ec ed sensi i i y analysis he e has been ound he alue o s i ness o he sp ing i em 11 K1 = 1.235 N/mm. When se ing up his alue o s i ness, he eloci y o he jacke o he ans e mechanism coincides wi h he eloci y o he con ol elemen , namely up o he momen o i s impac upon he s op block. This eloci y is ep esen ed in he diag am 4. 4 Sensi i i y analysis – educ ion o kine ic ene gy o he con ol elemen An in eg al pa o he needle ans e mechanism is he s op block which p o ides o opening o he colle s. A e he impac o he ubbe pad upon he s op block, he con olling elemen o he needle mechanism is b ough o a hal . The kine ic ene gy o he con olling elemen o he needle ans e mechanism a he d op upon he s op block is de e mined by he ela ion , 2 12 mEK= (2) whe e m is he mass o all pa s o he con olling elemen and is he impac eloci y o he con olling elemen . F om he ela ion i can be seen ha i is possible o educe he kine ic ene gy h ough a educ ion o he mass, howe e , i is mo e e ec i e o educe he impac 9 eloci y. A educ ion o he eloci y is achie ed by sho ening he leng h o he inne cylinde – see ig. 3, which o ms a pa o he con olling elemen . Thanks o his al e a ion, he momen o he impac is ans e ed o an a ea whe e he impac eloci y a ains conside ably lowe alues – see he diag am 4. F igu e 3 Inne cylinde The able 2 shows he esul s o sensi i i y analysis o he op imised s i ness o he sp ing i em 11, namely he esul ing alues o he impac eloci y o he con olling elemen and he alues o kine ic ene gy o indi idual alues o he sho ened g oo e. Table 2 Table o esul s o sensi i i y analysis – impac eloci y and kine ic ene gy a he impac Sho ening o he g oo e [mm] Leng h o he pa [mm] Leng h o he g oo e [mm] Posi ion o he g oo e [mm] Weigh [g] Regime 250 . p.m. Impac eloci y [m/s] Kine ic ene gy [J] 0 58,8 14,1 24,6 10,60 2,157 0,102826 1 59,8 13,1 25,6 11,15 2,061 0,095043 2 60,8 12,1 26,6 11,7 1,952 0,086303 3 61,8 11,1 27,6 12,24 1,826 0,076422 4 62,8 10,1 28,6 12,79 1,682 0,065622 5 63,8 9,1 29,6 13,34 1,524 0,054511 In he ollowing diag am 3 he e is shown he dec ease o kine ic ene gy due o designing al e a ion o he inne cylinde in o de o op imise he s i ness o he sp ing, i em 11. 0,04 0,05 0,06 0,07 0,08 0,09 0,1 0,11 00,511,522,533,544,55 Kine icene gy[J] Sho eningo  heg oo e[mm] D iag am 3 Sensi i i y analysis o he e ec o sho ening o he g oo e o he inne cylinde upon he kine ic ene gy 10 In he diag am 4 he e is shown he ime beha iou o he eloci y o indi idual pa s o he ans e mechanism o he egime 250 . p. m du ing he mo emen om he uppe posi ion o he needle mechanism o he lowe one, because he impac o he con olling elemen upon he s op block occu s in his phase. The blue cu e ep esen s he eloci y o he jacke o he needle ba o he ans e mechanism – see i em 2, igu e 1. The iole cu e shows he eloci y o he con olling elemen o he o iginal design wi h o iginal s i ness o he sp ing, i em 11. The ed cu e ep esen s he eloci y o his elemen o he op imised s i ness alue o he sp ing, i em 11 K = 1.235 N/mm. The diag am also includes a g een cu e, which s ands o he modi ied design o he con olling elemen in acco dance wi h he able 2, wi h he g oo e sho ened by 5mm. ‐2750 ‐2500 ‐2250 ‐2000 ‐1750 ‐1500 ‐1250 ‐1000 ‐750 ‐500 ‐250 0 250 500 750 1000 1250 1500 1750 0 0,0025 0,005 0,0075 0,01 0,0125 0,015 0,0175 0,02 0,0225 0,025 Veloci y[mm/s] Time[s] Veloci yo  hejacke o needle ans e mechanism Veloci yo con ollingelemen –op imiseds i nesso  hesp ing Veloci yo  hecon ollingelemen –modi ieddesign Veloci yo  hecon ollingelemen –o iginaldesign D iag am 4 Kinema ic condi ions o eloci ies o indi idual pa s o he needle ans e mechanism o he egime 250 . p.m. The able 3 compa es he alues o kine ic ene gy a he impac o he o iginal needle ans e mechanism, whe e ib a ions o he con olling elemen occu ed, and o he mechanism wi h op imised s i ness o he sp ing and modi ied inne cylinde . Table 3 Reduc ion o kine ic ene gy Impac eloci y [m/s] Impac ene gy [J] O iginal mechanism 2,676 0,158261 Op imised mechanism 1,524 0,054511 5 Expe imen al e i ica ion o he op imisa ion o he needle ans e mechanism The aim o expe imen al measu ing has been a e i ica ion o esul s o he needle ans e mechanism. Fo his pu pose, he e has been pe o med measu ing o he sound p essu e in he p oximi y o he needle ans e mechanisms bo h o he o iginal mechanism and o he op imised one. I has been a compa a i e measu emen , no p e ending o ob ain s anda d alues o sound p essu e. Fo measu ing he sound p essu e he e has been employed a measu ing appa a us manu ac u ed by B üel & Kjae wi h he dual-channel analyse 2144 and mic ophone ype 4165. The ollowing diag am 5 shows he o e all le els o sound p essu e measu ed on a unc ional model a he egime 250 . p.m. The alue A/L s ands o he o e all le el gi en by he sum o ene gies in indi idual equencies. The alue W s ands o he o e all le el weigh ed by he il e A. The il e A is sui able o he analysis o sound p essu e 11 in audible equencies; i espec s he p ope ies o human hea ing. The measu ed esul s and di e ences in sound p essu es a e summa ised and compa ed in he able 4. Table 4 Compa ison o o e all le els o sound p essu e Ope a ing egime 250 . p.m. O e all le els o sound p essu e (dB) A/L W O iginal cylinde 105,74 80,8 Modi ied cylinde 102,68 76,4 Reduc ion o o e all le els o he sound p essu e (dB) 3,06 4,4 The esul s o he measu ing con i m a ma ked imp o emen , achie ed by he modi ica ion o he inne cylinde and op imisa ion o he s i ness o he sp ing. This modi ica ion has b ough a dec ease o he o e all le el o sound p essu e by 4 dB app oxima ely. 6 Conclusion In his pape , he e has been analysed he needle ans e mechanism bo h by means o he so wa e P o/Enginee and expe imen ally. The e has been ca ied ou an op imisa ion o s i ness o he sp ing o he needle ans e in o de o a e he ib a ions o he con olling elemen . By means o a ma hema ical model he e has been es ablished he heo e ical eloci y o he impac o he ubbe pad upon he s op block. The e has been ca ied ou a sensi i i y analysis o he e ec o he modi ica ion o designing dimensions o he inne cylinde upon he kine ic ene gy o he con olling elemen a i s impac upon he machine ame. On he basis o his sensi i i y analysis he e has been al e ed he design o he inne cylinde , and he e has been e ec ed measu ing o he sound p essu e, which has shown a conside able educ ion. The expe imen al analysis has also con i med ha he designing al e a ion o he inne cylinde has exe ed no e ec upon he p ocess o he needle ans e . 12 Li e a u e [1] PEJCHAR, K.: Analysis and op imisa ion o he dynamic beha iou o sewing machine. (Diploma wo k). Libe ec, TUL 2008 [2] PEJCHAR, K., BERAN, J., Expe imen al analysis o he mechanisms o sewing machine (Pape ). Libe ec, TUL 2008 [3] PEJCHAR, K., BERAN, J.: Op imisa ion o he needle ba mechanism. /En y in he collec ion o pape s/. Libe ec, TUL 2009 P o . Ing. Ja osla Be an, CSc. Ing. Ka el Pejcha Ing. Jiří Komá ek 13 ANALÝZA A OPTIMALIZACE MECHANISMU PŘEDÁVÁNÍ JEHLY Článek pojedná á o analýze a op imalizaci mechanismu předá ání jehly pomocí so wa u P o/Enginee Wild i e 4 s cílem sníži hluk při ysokých o áčkách s oje. Je p o edena op imalizace yb aných pa ame ů mechanismu s cílem zamezi kmi ání členu, k e ý řídí okamžik u olnění jehly při jejím předání z jedné jehelní yče na d uhou. Následně je p o edena ci li os ní analýza li u kons ukčních pa ame ů mechanismu na ychlos dopadu řídícího členu na ám s oje. Na základě ýsledků analýzy a op imalizace jsou na ženy kons ukční úp a y mechanismu předání jehly a následně expe imen álně o ěřeny měřením akus ického laku na unkčním modelu. ANALYSE UND OPTIMIERUNG BEIM NADELÜBERGABEWERK De A ikel behandel die Un e suchung und Op imie ung beim Nadelübe gabewe k mi els de So wa e P o/Enginee Wild i e 4 mi dem Ziel, den Lä mpegel bei hohe Maschinend ehzahl zu eduzie en. Es wi d eine Op imie ung de ausgewähl en We kspa ame e o genommen, wo das Ziel gese z wi d, die Schwingung im Augenblick de Nadellösung bei ih e Übe gabe aus eine Nadels ange in die ande e s eue nden Glied zu e hinde n. Anschließend olg die Emp indlichkei sanalyse de Auswi kung on We kskons uk ionspa ame e n au die Geschwindigkei des S eue gliedein alls au den Maschinen ahmen. Anhand on den Un e suchungs- und Op imie ungse gebnissen we den Kons uk ionsanpassungen beim Nadelübe gabewe k en wo en, die anschließend du ch Messung des Schalld ucks beim unk ions ähigen Modell e suchsmäßig übe p ü we den. ANALIZA I OPTYMALIZACJA MECHANIZMU PRZEKAZYWANIA IGŁY A ykuł jes poświęcony analizie i op ymalizacji mechanizmu p zekazywania igły za pomocą op og amowania P o/Enginee Wild i e 4, dokonywanej w celu obniżenia hałasu p zy wysokich ob o ach maszyny. P zep owadzona jes op ymalizacja wyb anych pa ame ów mechanizmu w celu eliminacji wib acji elemen u, k ó y ok eśla momen zwolnienia igły podczas jej p zekazywania z jednego p owadnika igły na d ugi. Nas ępnie jes p zep owadzona analiza w ażliwości wpływu pa ame ów kons ukcyjnych mechanizmu na p ędkość opadania elemen u s e ującego na amę maszyny. Na pods awie wyników analizy i op ymalizacji zap oponowano zmiany kons ukcyjne mechanizmu p zekazywania igły, k ó e nas ępnie ekspe ymen alnie sp awdzono pomia ami ciśnienia akus ycznego na działającym modelu.