UKRAINIAN JOURNAL OF MECHANICAL ENGINEERING AND MATERIALS SCIENCE Vol. 2, No. 2, 2016 Mykol Krpenko, Mrijons Bogdevicius, Olegs Prentkovskis Vilnius Gedimins Technicl University, Vilnius, Lithuni EXPERIMENTAL IMPROVEMENT OF THE TECHNOLOGY OF CUTTING OF HIGH-PRESSURE HOSES WITH METAL BRAID ON HAND CUTTING MACHINE Received: Octoer 24, 2016 / Revised: Decemer 2, 2016 / Accepted: Decemer 26, 2016 Krpenko M., Bogdevicius M., Prentkovskis O., 2016 Astrct. In the rticle the review of the prolem of improvement of technology of high pressure hoses cutting on the hnd cutting mchines is nlyzed. Different methods of cutting of high pressure hoses into the illets re overviewed nd the qulity of edge cuts of hoses is nlyzed. The comprison of tretment on utomtic cutting mchines nd on hnd cutting mchines is crried out. Different experimentl techniques of improvement of the qulity of edges cutting of high pressure hoses re presented. On the sis of experimentl method, new cutting technology which consists in mximlly close fixtion of high pressure hoses to the cutting disc is proposed. In the sic design of the hnd cutting mchine, the only supports re provided, so tht the cutting of the edge section of high pressure hoses cuses the metl rid loosening. The proposed technology excludes the scrolling nd ending of high pressure hoses during cutting, so tht the loosening of metl rid is lso excluded. In the pper it is shown tht the scheme of distriution of cutting forces during the cutting of high pressure hoses is presented nd the mthemticl model of determintion of norml nd tngentil cutting forces is formed. With help of tensiometric tle the vlues of components of cutting forces during free nd fixed cutting of high pressure hoses were defined nd their comprison ws performed. As result of the use of this technology the edges of the cut off high pressure hoses meet the necessry requirements without using of complicted technologicl processes. Keywords: high pressure hose, metl rid, cutting force, hnd cutting mchine, tensiometric tle, technologicl process, loosening. Introduction Eventully, the mchines sed on hydrulic drive need to e repired or the replcement of components of hoses of high pressure (HPH) to e done. HPH re used s flexile pipe in hydrulic systems of mchines nd mechnisms for trnsporting of minerl nd hydrulic oils, fuel oil nd wter-oil emulsions nd re widely used in rod construction, mining, griculture, forestry, oil nd gs industries. HPH re influenced y significnt lods nd y significnt pressure drops, ensuring stle opertion of the equipment, so there is need in the preprtion of mterils nd components of HPH in ccordnce with the requirements. A technologiclly properly mnufctured HPH ensures mximum performnce of pssing of the working fluid, nd minimizes hydrulic losses. One of the mssive opertions during the mnufcturing of HPH is cutting to the pproprite length. In most cses t smll nd medium enterprises the hnd cutting mchines re used. However, when using these mchines there is technologicl prolem: the cut edge fces of the HPH does not meet the requirements for further usge [1], s loosening of metl rid does not llow to crry out the production opertions, nd in some cses there is n opportunity of metl prts getting into the hydrulic system.
72 Mykol Krpenko, Mrijons Bogdevicius, Olegs Prentkovskis Sttement of purpose nd prolems of reserch The purpose of this work consists in improvement of the technology of cutting of high-pressure hoses with metl rid on hnd cutting mchines, nd in experimentl determintion of chnges of cutting forces under different prmeters nd cutting technologies with help of tensiometric tle. Min mteril High-pressure hoses re used in hydrulic systems of vrious mchines nd mechnisms (construction nd rod mchinery, forestry mchinery, lifting nd trnsporting equipment, trctor nd griculturl mchinery, industril equipment, etc.) for trnsporting of hydrulic nd engine oils, liquid fuel comptile oils nd emulsions. As rule, HPH re not reinforced, ut they re strengthened y one or more lyers of spirl/cross steel (coted y rss) sheth in order to chieve the required reserve tensile strength. In most cses, the hose consists of three min elements: the inner ruer lyer, or cmer, reinforcing lyer, or the strength frme, nd the outer ruer lyer, or the protective coting. The cmer ensures hose tightness nd its resistnce to chemicl nd physicl ction of the working environment. Strength frme intended for the perception of mechnicl strins cused y the internl or externl pressure. The outer ruer lyer protects the hose from the influence of externl fctors (rsion nd other mechnicl stresses, wether conditions etc.) (Fig. 1) [2; 3; 4]. Fig. 1. Structure of HPH: with one metl rid 1SN; with two hoses with metl rid 2SN At lrge enterprises which del with the mnufcturing of HPH (IMM Hydrulics, Hypress, Mdejski) the modern servo cutting mchines with vrile serving of cutting discs re widely used (Fig. 2, ) [5; 6] tht provides clen cut edge of the hose nd the sence of loosening of metl rid (Fig. 3, ). Fig. 2. Mchines of hoses cutting: utomtic cutting mchine; hnd cutting mchine
Experimentl Improvement of the Technology of Cutting of High-Pressure Hoses 73 When using the hnd cutting mchines (Fig. 2, ) [5; 6] the cut hose edges do not meet the requirements for further usge, s the loosening metl rid tkes plce (Fig. 3, ). As result, the susequent HPH mnufcturing opertions (crimping nd fitting) cn t e crried out without prior stripping of the edge, nd in some cses there is n opportunity of metl prts getting into the hydrulic system when using such hoses. To eliminte the loosening of metl rid while cutting t lrge enterprises the utomted cutting mchines with vrile serving of cutting element nd with the grdul fixtion of HPH re used. In the hnd cutting mchines this technology is not ville, tht s why it s n importnt prolem to improve the cutting technology in order to prevent the loosening of metl frmework of hoses. Fig. 3. Edge fce cuts of hose: on utomtic mchine; on hnd cutting mchine The reserch ws crried on the sis of the enterprise Hydrohouse (Kyiv, Ukrine). During the reserch, severl technologicl tests of the effectiveness of elimintion of metl rid loosening when cutting of the HPH on the hnd cutting mchine. Hoses with one metl rid 1SN nd two metls rids 2SN were cut. One of the cutting methods consists in surfce winding of het-resistnt firous film on the cutting plce (Fig. 4, ). During the cutting, there re dditionl externl lods P d, which prtilly restrin the loosening of metl frmework, ut do not completely eliminte it. The usge of this method is inefficient nd costly in continuous opertion modes. Another method consists in the supplying of compressed ir long the whole length of HPH in order to crete dditionl internl forces P d (Fig. 4, ), s result of which the lignment of internl nd externl forces, cting on the hose during the cutting, tkes plce. This method is not effective, ecuse the time spent on permnent chnge of hoses of different dimeters nd constnt connection / disconnect of supply of compressed ir to the ends of the hose tkes considerle time of the mnufcturing process. Fig. 4. Technologicl methods of improving of hoses cutting: surfce winding y het-resistnt firous film; supply of compressed ir
74 Mykol Krpenko, Mrijons Bogdevicius, Olegs Prentkovskis One of the most optiml methods of hoses cutting is cutting with hose rigid fstening (clmping) s close to the cutting element (cutting disc) s possile. In the sic configurtion of hnd cutting mchines (the scheme is shown in Fig. 5) there re only the utments (umpers) (A) tht cuses the scrolling nd deflection of the hose when the cutting disc (C) moves to the stopper (B). In the work the norml nd tngentil cutting forces were determined during the cutting of hoses with one (1SN) nd two (2SN) metl rids. The reserch ws performed while cutting y the cut into method. Power prmeters were investigted on the experimentl stnd. The stnd ws estlished on the sis of hnd cutting mchine TAGLTF2D/E, which prmeters re presented in Tle 1. Fig. 5. Bsic configurtion scheme of hnd cutting mchine Prmeters of hnd cutting stnd TAGLTF2D/E Article TAGLTF2D/E 2 rids 2" 4 windings 2" 6 windings 1 1/2" Mx Ø 75 mm (2.953") Rpm 2900 disc Ø, mm 250 mm (9.843") Mesurement error ± 2 % Stndrd voltge 400V 50 Hz 3Ph Engine power, kw 3 Weight, kg 42 Dimensions (L W H) mm 665 700 420 Suction rnch yes Protective system yes Tle 1 The suggested method of hoses cutting consists in hose rigid fstening (clmping) s close to the cutting disc s possile (Fig. 6) nd in incresing of the feed rte of the cutting disc. As result, the movement of the hose is completely eliminted during the cutting process on hnd mchine tool.
Experimentl Improvement of the Technology of Cutting of High-Pressure Hoses 75 1 2 Fig. 6. Scheme of HPH fixing (clmping) with regrd to cutting disc: 1 cutting disc; 2 hose fixers In this cse, there re some chnges in the distriution of cutting forces. The verticl P yv (N) nd horizontl P yg (N) components of cutting force my e determined with help of the tensiometric tle y the method presented in [7]. To improve the efficiency of reserch the multivrite experiment plnning method [8] ws used. This llows to reduce the numer of crried out experiments in comprison with trditionl methods of experiments crrying out. In Fig. 7 the scheme of lods, which cts upon the hose during its cutting, is shown. According to [9] the point of ppliction of the resulting forces generted during the cutting is on the line connecting the centers of the disc nd cut hose. Fig. 7. Scheme of lods generted during the hose cutting: 1 cutting disc; 2 high pressure hose
76 Mykol Krpenko, Mrijons Bogdevicius, Olegs Prentkovskis The norml P y (N) nd tngentil P z (N) cutting forces my e determined from the following dependencies [10]: Pz = Pyg cosα Pyv sin α; (1) P = P cosα P sin α, y yv yg where P yg is horizontl component of cutting force, N; P yv is verticl component of cutting force, N; α is corner tht determines the point of ppliction of the resultnt cutting force, ; d0 d α= rccos, (2) d0 d y where d 0 is cutting disc dimeter, m; d is hose outer dimeter, m; d y is hose internl dimeter, m. When determining the cutting force the vlues P yg (N) nd P yv (N) otined experimentlly for mximum contct rc of cutting disc nd cut hose were plced in dependence (1). During the reserch it ws ssumed tht the trjectory of ny point locted on the worked surfce of the cutting disc, is close ot the circle, s its supply rte is smll in comprison with the circulr one. Also, it ws considered tht the destruction of the worked mteril is crried out only due to the ction of tngentil forces P z (N), evenly distriuted long the contct re nd relted with norml forces P y (N) y the rtio: Pz = KTPy, (3) where K T is coefficient of trnsformtion. The work spent on the destruction of the mteril (ruer nd metl rid) during cutting, my e determined from the dependence [9; 10; 11]: or da 0 Pdl z k, = (4) 0 v v c z k, da = qdv = q HPdl (5) where q v is proportionlity fctor (energy consumption), which is determined experimentlly nd is equl to the work spent on the destruction of the unit volume of mteril; H is cutting disc height, m; dv - elementry volume of mteril tht is destroyed, m 3 ; l k is elementry pltform length long the rc of contct, m; c is depth of cut, m; V n c = dlk sin α0; Vp (6) lk α 0 =, R0 where α 0 is centrl ngle which chrcterizes the size of contct re, rd. According to the previous equtions: V l 1 cos, n k Pz = RqH 0 v V p R 0 where R 0 is circle rdius, m; V n is supply rte, m/s; V p is circulr speed, m/s. The power of hnd mchine which is spent on the supply of the working ody (cutting disk): Nn = PV n n ; (8) P = P + P, (9) n zv yv where, P zv nd P yv re, correspondingly, the sum of projections of tngentil nd norml forces on the xis, which coincides with the supply direction, (N). (7)
Experimentl Improvement of the Technology of Cutting of High-Pressure Hoses 77 The point of ppliction of the resulting forces generted during cutting, is locted on the line connecting the centers of the disc nd the hose (Fig. 7). Tht s why, for defining of α 0 it is expedient to use the formul in ccordnce with [12]: R0 r0 α 0 = rccos. (10) R0 + rv where R 0 is the rdius of cutting disc, m; r 0 is hose outer rdius, m; r v is hose inner rdius, m. Tking into ccount (6) nd (7) zv = α0 v V lk n α0 α0 k Vp 0 P P cos q H sin cos dl ; yv = α0 v lk V n 2 0 k V α p 0 P P sin q H sin dl. After integrtion nd sustitution in (8) nd (9) 2 R0 Vn lk 1 lk sin2 sin 2 lk Nn = qv H. 2 V + p R 0 2 R 0 R (12) 0 2 N As one cn see n Vn << 1, ecuse the vlue is rther smll. Tht s why the power consumed for N Vp the supply of mchine cutting disc my e ignored [13]. Ultimtely, the norml nd tngentil cutting forces re s follows: Py = Pyv cos α 0 + Pzv ; (13) Pz = Pzv cosα 0 + Pzv sin α0. During reserch the dependences of tngentil nd norml forces on the supply rte of the free hose position nd fixed one were determined using the tenzometric tle nd the simultion process in MthCd softwre. The results re presented s plots in Fig. 8. (11) Fig. 8. Plots of cutting forces determined experimentlly with help of tenzometric tle: free cutting; fixed cutting The cut edge fce of the hose meets the necessry requirements nd hs the form shown in Fig. 9, without the use of complicted technologicl processes in comprison with the previous methods.
78 Mykol Krpenko, Mrijons Bogdevicius, Olegs Prentkovskis Fig. 9. The edge fce cuts of the high-pressure hose fter fixed cutting method The incresing of cutting speed nd fixing of hose improves the qulity of edge fce cuts of hose nd reduces the cutting forces up to 10 20 %. On the sis of the plots nlysis, it cn e concluded tht the proposed method reduces the cutting forces nd slightly reduces the wer of the tool. Conclusions The new method of fixed cutting of high-pressure hoses on hnd cutting mchines is proposed. On the sis of reserch, the mthemticl model tht descries the chnge of tngentil nd norml forces depending on the process conditions of cutting on the hnd cutting mchine is formed for vrying cutting disc speed tking into ccount different cutting technologies (free cutting nd fixed one). The plots, which show tht the usge of fixed method reduces the cutting forces re y 10 20 % in comprison with the free cutting, re presented. Fixed cutting effectively influences the energy consumptions, s well s the durility of the cutting tool. While using the proposed method the effect of susidence nd scrolling of hose is excluded resulting in the sence of loosening of the hose metl rid. References [1] Лощенов П. Ю. Способ диагностирования рукавов высокого давления // Вестник Московского государственного университета леса Лесной вестник. 2012. 3 (86). С. 72 84. [2] ГОСТ-6286-73. Рукава резиновые высокого давления с металлической оплеткой неармированные. Технические условия. Введ. 1974-07-01. М.: Изд-во стандартов, 2003. 16 с. [3] Наумов Ю. Н. Гидродинамические процессы, протекающие в гидросистемах высокого давления горных машин // Горный информационно-аналитический бюллетень (научно-технический журнал). 2002. 8. С. 24 31. [4] Мефедова Ю. А. Расчет рукавов высокого давления по распределению нагрузки между слоями оплетки // Вестник Саратовского государственного технического университета. 2011. 2 (58), т. 3. С. 97 102. [5] Tois S., Fishwick W. Theory of regenertive mchine tool chtter // Engineer. 1958. Vol. 205. P. 199 203; 238 239. [6] Merritt H. E. Theory of self-excited mchine-tool chtter, contriution to mchine-tool chtter, reserch-1 // Trnsctions of the ASME, Journl of Engineering for Industry. 1965. Vol. 87. P. 447 454. [7] Мифлиг Д. М., Семенов Е. Б., Шор Г. М. Приборы для исследования силовых параметров при шлифовании и резании камня. В сб. Горный породоразрушающий инструмент. К. : Техника, 1970. [8] Адлер Ю. П., Маркова Е. В., Грановский Ю. В. Планирование экспериментов при поиске оптимальных условий. М. : Наука, 1976. [9] Абрашкевич Ю. Д., Пелевін Л. Е., Човнюк О. В. Визначення силових параметрів процесу різання абразивними армованими кругами // Гірничі, будівельні, дорожні та меліоративні машини. 2012. Вип. 79. С. 53 56. [10] Qin Hu, Sun Cunzhi. New method of circle nd rc cutting // Optik Interntionl Journl for Light nd Electron Optics. Septemer 2012. Vol. 123, Issue 17. pp. 1550 1554. [11] Никулин В.В. К определению глубины реза зубками барабанных режущих органов // Изв. ВУЗов. Горный журнал. 1966. 4. С. 91 94. [12] Абрашкевич Ю., Рашківський В., Поліщук В., Човнюк О. Силові параметри машин з абразивним інструментом // Гiрничi, будiвельнi, дорожні та мелiоратiвнi машини. 2015. Вип. 85. С. 67 71. [13] Pvel A. Chentsov, Alexnder A. Petunin. Tool Routing Prolem for CNC Plte Cutting Mchines // IFAC-PpersOnLine. 2016. Volume 49, Issue 12. pp. 645 650.