{"id":210,"date":"2011-11-03T10:17:53","date_gmt":"2011-11-03T10:17:53","guid":{"rendered":"http:\/\/www.anvelope.ro\/blog\/?p=210"},"modified":"2011-11-27T22:26:21","modified_gmt":"2011-11-27T22:26:21","slug":"ce-inseamna-aderenta-in-tehnologia-cauciucului-de-iarna","status":"publish","type":"post","link":"https:\/\/www.anvelope.ro\/blog\/ce-inseamna-aderenta-in-tehnologia-cauciucului-de-iarna.htm","title":{"rendered":"Ce inseamna aderenta in tehnologia cauciucului de iarna"},"content":{"rendered":"<p>Pentru a decide\u00a0mai bine ce\u00a0fel de\u00a0<span class='wp_keywordlink'><a href=\"http:\/\/www.anvelope.ro\" title=\"Magazin online anvelope\">anvelope<\/a><\/span>\u00a0de iarna ne sunt necesare,\u00a0este\u00a0chibzuit\u00a0sa intelegem\u00a0 cum functioneaza\u00a0tractiunea la nivelul anvelopa-drum.<br \/>\nCu totii ne dorim o\u00a0anvelopa\u00a0care\u00a0sa aiba tractiune buna\u00a0pe tot parcursul anului, in\u00a0 orice conditii meteo,\u00a0sa fie durabila\u00a0si\u00a0ieftina.\u00a0Aceasta\u00a0anvelopa\u00a0inca nu exista, deoarece multe\u00a0dintre calitatile pe care\u00a0le dorim \u00a0intruchipate intr-o singura anvelopa sunt\u00a0 contradictii\u00a0tehnologice.<br \/>\nLa nivel\u00a0microscopic,\u00a0o anvelopa\u00a0nu\u00a0este neteda.\u00a0Suprafata\u00a0benzii de rulare\u00a0arata\u00a0ca o zona muntoasa\u00a0cu varfuri zimtate si ascutite\u00a0despartite de vai ad\u00e2nci, creand o suprafata\u00a0cu aspect ostil.<br \/>\nAcest lucru este bun deoarece\u00a0nici suprafata drumului\u00a0nu\u00a0este neteda,\u00a0imitand\u00a0 \u00a0conturul benzii de rulare\u00a0a anvelopei.\u00a0Aceste doua\u00a0suprafete\u00a0aspre\u00a0se angreneaza,\u00a0anvelopa\u00a0se roteste\u00a0si aceasta reprezinta\u00a0aderenta\u00a0care misca masina\u00a0inainte.<br \/>\n\u015ei\u00a0pentru a fi siguri\u00a0ca\u00a0zona de contact are cat mai mult cauciuc,\u00a0aceasta trebuie sa\u00a0fie\u00a0moale. Asta poate insemna ca\u00a0anvelopa ideala\u00a0este doar un\u00a0mare\u00a0balon neagru,\u00a0din cauciuc\u00a0moale.<br \/>\nDar mai e ceva\u00a0&#8211;\u00a0vrem\u00a0ca anvelopa sa reziste,\u00a0asa inc\u00e2t\u00a0nu putem\u00a0face\u00a0cauciucul atat de moale pe cat ar fi de ideal.\u00a0Asta ar\u00a0fi ca o anvelopa pentru masini de curse:\u00a0extrem de\u00a0aderenta\u00a0 pentru\u00a0un ciclu\u00a0de viata\u00a0foarte scurt.\u00a0Deci,\u00a0o anvelopa\u00a0pentru strada are nevoie de un cauciuc care sa fie mai rigid\u00a0dec\u00e2t\u00a0cel ideal.<\/p>\n<p>Acum,\u00a0anvelopa\u00a0noastra\u00a0ideala este\u00a0o minge\u00a0mare\u00a0neagra de\u00a0cauciuc\u00a0semi-rigid.\u00a0Dar ce\u00a0facem daca\u00a0ploua?<\/p>\n<p>Ar fi mai bine\u00a0daca am avea niste\u00a0caneluri\u00a0taiate in\u00a0anvelope.\u00a0Fiecare\u00a0canelura\u00a0este\u00a0o zona de\u00a0gol\u00a0unde cauciucul\u00a0nu\u00a0atinge drumul.\u00a0Mai putin\u00a0cauciuc\u00a0care atinge\u00a0drumul inseamna\u00a0o aderenta\u00a0mai mica\u00a0pe carosabil uscat, dar\u00a0mai mult spatiu pentru\u00a0ca apa de ploaie\u00a0sa scape\u00a0de sub\u00a0anvelopa\u00a0in miscare.<br \/>\nDaca\u00a0se aduna prea multa apa\u00a0in\u00a0partea din fata a\u00a0pneului sub forma unei perne,\u00a0aceasta va salta\u00a0masina\u00a0(hidroglisare),\u00a0si putem pierde controlul.\u00a0Deoarece fiecare\u00a0anvelopa\u00a0are un punct critic de\u00a0acvaplanare,\u00a0fiecare\u00a0model de banda de rulare\u00a0 este\u00a0un compromis\u00a0de\u00a0aderenta intre drumul umed\u00a0si\u00a0cel uscat.\u00a0 Deci,\u00a0anvelopa\u00a0noastra\u00a0ideala este\u00a0acum\u00a0un balon\u00a0de culoare neagra,\u00a0din cauciuc cu rigiditate medie, cu\u00a0santuri taiate in\u00a0el.<br \/>\nVrem ca\u00a0anvelopa sa aiba aderenta\u00a0at\u00e2t vara c\u00e2t\u00a0si iarna.\u00a0Acum avem\u00a0o mare problema.\u00a0 Compusii de cauciuc se intaresc atunci cand scade temperatura iar cauciucul\u00a0 dur\u00a0nu\u00a0 are aderenta.<br \/>\nPutem\u00a0crea\u00a0o mixtura\u00a0care ram\u00e2ne\u00a0moale\u00a0la temperaturi de inghet, dar\u00a0acesta se va\u00a0 uza foarte repede\u00a0atunci cand mercurul termometrului\u00a0urca.\u00a0Care\u00a0este cea mai buna\u00a0reteta pentru\u00a0nevoile noastre?<br \/>\nEvident,\u00a0anvelopa noastra\u00a0ideala de iarna\u00a0 este\u00a0acum\u00a0un amestec de cauciuc\u00a0care ram\u00e2ne\u00a0moale, atunci cand temperaturile scad brusc.<br \/>\nAici\u00a0ajungem la\u00a0un nou punct de decizie spre\u00a0anvelopa\u00a0de iarna\u00a0ideala:\u00a0de ce\u00a0ne facem griji\u00a0despre multa gheata sau zapada?\u00a0Fiecare\u00a0dintre aceste conditii\u00a0necesita\u00a0 anvelope\u00a0 care sunt\u00a0complet diferite.<\/p>\n<p><strong>Aderenta pe gheata<\/strong><\/p>\n<p>Aderenta pe gheata necesita\u00a0o suprafata mare de\u00a0cauciuc\u00a0in contact cu\u00a0drumului,\u00a0ca un\u00a0pneu de curse\u00a0dar facut\u00a0din\u00a0amestec de cauciuc\u00a0de iarna.<br \/>\nAcest tip de cauciuc trebuie sa aiba zeci de mii de\u00a0crestaturi\u00a0superficiale taiate in\u00a0el, numite striuri\u00a0.\u00a0Striuile\u00a0nu\u00a0creaza\u00a0blocuri, ci\u00a0mai degraba doar\u00a0taieturi de mica profunzime in\u00a0banda de rulare.\u00a0Anvelopa\u00a0de iarna\u00a0Pirelli\u00a0Carving\u00a0are mai mult de 120\u00a0de metri\u00a0de striuri\u00a0intr-o singura\u00a0anvelopa.<br \/>\nStriurile sunt\u00a0elemente cheie\u00a0in\u00a0aderenta\u00a0pe gheata.\u00a0Chiar si\u00a0cea mai rece\u00a0gheata\u00a0 elibereaza o\u00a0pelicula\u00a0de apa, atunci c\u00e2nd este apasata de o greutatea\u00a0si\u00a0acest film subtire \u00a0 actioneaza ca un\u00a0lubrifiant\u00a0intre\u00a0anvelopa\u00a0si\u00a0gheata.<br \/>\nCercetarile firmei Yokohama Tire au aratat\u00a0ca mai putin de 10\u00a0miimi\u00a0de milimetru\u00a0poate\u00a0cauza micro-acvaplanare\u00a0pe gheata si a concluzionat ca aceasta conditie este\u00a0cea mai frecventa la\u00a0temperaturi intre -6\u00a0C si 0\u00a0C.<br \/>\nEste\u00a0treaba striurilor sa se deschida\u00a0cand acestea\u00a0vin in contact\u00a0cu\u00a0gheata\u00a0pentru a permite apei sa intre in aceste taieturi, acest fenomen \u201cuscand\u201d\u00a0astfel\u00a0gheata\u00a0 pentru\u00a0 tractiune.<\/p>\n<p><strong>Aderenta pe zapada<\/strong><\/p>\n<p>Tractiunea pe zapada solicita\u00a0c\u00e2t mai multe\u00a0muchii\u00a0ascutite\u00a0posibil, astfel inc\u00e2t\u00a0cu cat putem crea mai multe blocuri,\u00a0cu atat avem mai multa aderenta.\u00a0 Marginile\u00a0de\u00a0blocuri \u201emusca\u201d\u00a0in\u00a0zapada,\u00a0impingand-o\u00a0deoparte\u00a0si o sfarama p\u00e2na c\u00e2nd\u00a0ajunge la\u00a0un strat\u00a0destul de\u00a0compact\u00a0pentru\u00a0asigurarea aderentei.<br \/>\n\u00cen cazul in care\u00a0zapada este\u00a0prea moale,\u00a0anvelopa\u00a0o\u00a0comprima\u00a0intre\u00a0blocurile\u00a0benzii de\u00a0 rulare.\u00a0Compresia creeaza\u00a0apa\u00a0si\u00a0stratul\u00a0umed\u00a0de ninsoare\u00a0de pe anvelopa\u00a0se leaga de\u00a0zapada\u00a0de pe sol\u00a0si\u00a0asigura tractiunea.<br \/>\nAnvelopa\u00a0de iarna\u00a0ideala este\u00a0acum\u00a0din cauciuc moale, cu\u00a0profilul format dintr-o multime de\u00a0blocuri\u00a0 mici, cu margini ascutite\u00a0acoperite\u00a0cu striuri.\u00a0Dar, din nou,\u00a0 aceste fragmente independente\u00a0de cauciuc\u00a0vor face masina\u00a0sa se simta\u00a0ca\u00a0si cand\u00a0pneurile\u00a0sunt realizate din\u00a0gelatina.<br \/>\nDeci, avem nevoie\u00a0sa reducem\u00a0numarul de\u00a0blocuri\u00a0din\u00a0 banda de rulare si numarul de\u00a0striuri\u00a0pentru\u00a0ceva ce va merge\u00a0pe\u00a0asfalt, fara sa ne agite simturile si\u00a0sa se rupa ea insasi.<\/p>\n<p><strong>Compusi multicelulari pentru gheata<\/strong><\/p>\n<p>Acum,\u00a0inginerii\u00a0trebuie sa gaseasca un echilibru intre\u00a0striuri\u00a0si\u00a0blocuri\u00a0pentru\u00a0anvelop\u00a0de iarna\u00a0ideala.<br \/>\nIntra pe scena Bridgestone\u00a0Blizzak.\u00a0Acesta utilizeaza\u00a0goluri de aer\u00a0in\u00a0anvelopa\u00a0de cauciuc\u00a0pentru a prelua\u00a0munca striurilor pe gheata.\u00a0Este\u00a0un concept\u00a0revolutionar, iar\u00a0publicul\u00a0a reactionat\u00a0prin cumpararea a\u00a0peste 100 de milioane de <span class='wp_keywordlink'><a href=\"http:\/\/www.anvelope.ro\" title=\"Cauciucuri\">cauciucuri<\/a><\/span>\u00a0in intreaga lume\u00a0incepand cu anul 1988.<br \/>\nConceptul\u00a0a fost imbunatatita\u00a0de mai multe ori\u00a0de-a lungul timpului,\u00a0bulele de aer\u00a0si-au schimbat\u00a0forma,\u00a0 a fost adaugat\u00a0siliciu dar\u00a0principiul de baza\u00a0este inca\u00a0aceeasi.<br \/>\nExista\u00a0milioane de\u00a0bule microscopice de aer\u00a0&#8211;\u00a0cam 55 la suta\u00a0din\u00a0grosimea cauciucul\u00a0benzii de rulare.\u00a0Acestea sunt expuse\u00a0strat cu strat\u00a0ca si cauciuc\u00a0de uzura. Micile bule actioneaza\u00a0 ca\u00a0niste\u00a0cupe\u00a0ascunse pentru stratul de\u00a0apa de pe\u00a0gheata.<br \/>\nTotusi sunt doar neajunsuri:\u00a0ad\u00e2ncimea\u00a0benzii de rulare\u00a0nu poate fi complet\u00a0umpluta cu\u00a0aceste\u00a0bule de aer si o\u00a0anvelopa\u00a0de mare viteza\u00a0este\u00a0imposibil\u00a0de realizat\u00a0&#8211;\u00a0ar\u00a0deveni\u00a0 spongioasa.<br \/>\nPorozitatea\u00a0si\u00a0vibrarea\u00a0cauzeaza caldura\u00a0la aceasta viteza astfel ca\u00a0Bridgestone\u00a0a\u00a0 stabilit\u00a055 de procente pentru\u00a0ad\u00e2ncimea benzii de rulare\u00a0 cu bule de aer\u00a0completate cu\u00a0 particule\u00a0de nisip\u00a0in\u00a0fiecare.\u00a0Dupa\u00a0cele 55 la suta procente ad\u00e2ncime, Blizzak\u00a0devine\u00a0 o anvelopa de iarna\u00a0normala.<br \/>\nYokohama\u00a0a rezolvat\u00a0aceasta\u00a0problema\u00a0la\u00a0ultimele\u00a0sale\u00a0cauciucuri \u00a0IG20\u00a0Ice Guard.\u00a0 Ea\u00a0si-a fixat bulele de aer cu un invelis de rasina,\u00a0care contine\u00a0fulgi\u00a0absorbanti de\u00a0 carbon.<br \/>\nAceste\u00a0bile\u00a0mici si aspre\u00a0se amesteca\u00a0in\u00a0mixtura de cauciuc a\u00a0benzii de rulare\u00a0de sus in jos.\u00a0Atat timp cat sunt intacte,\u00a0acestea sunt o\u00a0parte\u00a0stabila a\u00a0amestecului de cauciuc.<br \/>\nOdata cu\u00a0uzura benzii de rulare,\u00a0fiecare\u00a0nou strat\u00a0de bile de aer\u00a0este expus\u00a0si\u00a0trece la lucru. Anvelopa\u00a0este mai\u00a0rigida, deoarece\u00a0numai unele\u00a0bile\u00a0sunt deschise. Fulgii\u00a0de carbon\u00a0 elimina umiditatea.<br \/>\nBilele de aer\u00a0permit apei\u00a0ramase\u00a0sa se ascunda si\u00a0cauciucul\u00a0are\u00a0o relativa\u00a0gheata\u00a0 uscata pentru aderenta. Desi\u00a0aparent\u00a0au\u00a0rezolvat problema\u00a0vibrarii\u00a0benzii de rulare,\u00a0 Yokohama\u00a0 nu\u00a0a facut o\u00a0versiune\u00a0de mare viteza\u00a0a anvelopei\u00a0Ice Guard.<br \/>\nMichelin\u00a0a\u00a0aderat la\u00a0linia bulelor\u00a0de aer\u00a0cu\u00a0X-Ice\u00a0Xi2.\u00a0Acesta utilizeaza\u00a0\u00a0tunele verticale ca\u00a0tuburi,\u00a0in blocurile\u00a0benzii de rulare,\u00a0ca\u00a0o cale\u00a0de evacuare\u00a0a apei.<\/p>\n<p><strong>Aderenta echilibrata intre gheata si zapada<\/strong><\/p>\n<p>Aceasta este\u00a0o zona unde inginerii\u00a0sunt ca pe muchie de cutit.\u00a0In ce directie deviaza produsul,\u00a0gheata sau\u00a0zapada?<br \/>\nPentru a concluziona,\u00a0trebuie sa aratam ca exista o cerere\u00a0mare\u00a0pentru\u00a0anvelope\u00a0de iarna\u00a0 cu viteza\u00a0nominala\u00a0(H la\u00a0W)\u00a0 pentru autoturisme\u00a0sport\u00a0si\u00a0sedan\u00a0de lux.\u00a0Pentru aceste aplicatii,\u00a0orice\u00a0solutie cu tehnologie multicelule\u00a0 este exclusa.\u00a0Exista o\u00a0anvelopa \u00a0Blizzak\u00a0in acest\u00a0segment de piata, dar este\u00a0Blizzak\u00a0doar ca nume.\u00a0Ea nu\u00a0utilizeaza\u00a0 tehnologia multicelulara.<br \/>\nCompanii\u00a0cum ar fi\u00a0Pirelli,\u00a0Goodyear,\u00a0Toyo\u00a0si\u00a0Nokian\u00a0au atacat\u00a0problema\u00a0in diferite moduri\u00a0pentru a ajunge la aceeasi solutie finala:\u00a0aderenta fara\u00a0multa vibratie.\u00a0Ei\u00a0au realizat acest lucru\u00a0prin\u00a0caneluri\u00a0inovatoare,\u00a0cu deschidere variabila, dar\u00a0care se blocheaza\u00a0atunci c\u00e2nd\u00a0sunt in sarcina in viraje; mici umeri de sprijin\u00a0intre\u00a0blocurile\u00a0benzii de rulare; folosirea\u00a0mai\u00a0multor compusi\u00a0de cauciuc\u00a0&#8211;\u00a0lista este lunga. \u015ei\u00a0aceste anvelope\u00a0 isi faca treaba\u00a0lor\u00a0&#8211;\u00a0ele nu\u00a0pot concura\u00a0cu amestecul\u00a0multicelular\u00a0pe gheata\u00a0pura,\u00a0dar ruleaza\u00a0superb\u00a0pe\u00a0noroi,\u00a0zapada\u00a0si\u00a0asfalt.<\/p>\n<p><strong>Evaluarea vitezei<\/strong><\/p>\n<p>Am facut o trecere in revista a anvelopelor de iarna de la\u00a0 Pirelli, Goodyear, Michelin si Nokian V.\u00a0Toate trec prin noroi, zapada moale sau tare si gasesc aderenta la masinile de viteza din Campionatul\u00a0 Mondial de Raliuri.<br \/>\nCele mai surprinzator, au alergat cu viteze apropiate de cele ale anvelopele de vara pe asfalt uscat, rece.<br \/>\nPirelli Sottozero, Michelin Pilot Alpin PA3, Goodyear Eagle Ultra Grip GW3, si Nokian WR sunt cele mai bune pentru aceste performante.\u00a0Cauciucul WR Nokian este neobisnuit, deoarece poate fi lasat pe vehicul pe tot parcursul anului.\u00a0El si Yokohama W.Drive sunt cu adevarat anvelope \u201eall-weather\u201d.<\/p>\n<p><strong>Alegerea\u00a0dupa aspect<\/strong><\/p>\n<p>C\u00e2nd\u00a0doriti\u00a0doar aderenta pe\u00a0gheata\u00a0si nimic altceva,\u00a0incepeti cu\u00a0o anvelopa pe baza de\u00a0 compusi\u00a0multicelulari,\u00a0apoi cautati\u00a0dupa striuri. Cu\u00a0c\u00e2t\u00a0suntem\u00a0mai\u00a0multi,\u00a0cu\u00a0at\u00e2t\u00a0mai\u00a0bine.<br \/>\nAderenta pe zapada este data de blocuri cu\u00a0cat mai multe muchii\u00a0ascutite\u00a0posibile.\u00a0Un bloc\u00a0cu cinci\u00a0laturi\u00a0are mai multe margini decat unul\u00a0cu patru laturi.\u00a0Un bloc\u00a0al benzii de rulare\u00a0care este\u00a0crestat\u00a0in loc sa fie lis este mai bun.\u00a0Blocuri\u00a0benzii de rulare\u00a0pe marginea\u00a0anvelopei\u00a0trebuie sa\u00a0iasa in evidenta\u00a0brusc.<br \/>\n\u015ei, desigur,\u00a0anvelopa\u00a0trebuie sa aiba\u00a0certificarea indeplinirii testelor specifice de iarna: o\u00a0pictograma triunghiulara, cu munti\u00a0si in interiorul\u00a0 un fulg de nea.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Pentru a decide\u00a0mai bine ce\u00a0fel de\u00a0anvelope\u00a0de iarna ne sunt necesare,\u00a0este\u00a0chibzuit\u00a0sa intelegem\u00a0 cum functioneaza\u00a0tractiunea la nivelul anvelopa-drum. Cu totii ne dorim o\u00a0anvelopa\u00a0care\u00a0sa aiba tractiune buna\u00a0pe tot parcursul anului, in\u00a0 orice conditii meteo,\u00a0sa fie durabila\u00a0si\u00a0ieftina.\u00a0Aceasta\u00a0anvelopa\u00a0inca nu exista, deoarece multe\u00a0dintre calitatile pe care\u00a0le dorim \u00a0intruchipate intr-o singura anvelopa sunt\u00a0 contradictii\u00a0tehnologice. La nivel\u00a0microscopic,\u00a0o anvelopa\u00a0nu\u00a0este neteda.\u00a0Suprafata\u00a0benzii de rulare\u00a0arata\u00a0ca o zona&hellip;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"limit_modified_date":"","last_modified_date":"","footnotes":""},"categories":[3],"tags":[],"class_list":["post-210","post","type-post","status-publish","format-standard","hentry","category-cum-sa-alegi-anvelopele"],"_links":{"self":[{"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/posts\/210","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/comments?post=210"}],"version-history":[{"count":0,"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/posts\/210\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/media?parent=210"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/categories?post=210"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.anvelope.ro\/blog\/wp-json\/wp\/v2\/tags?post=210"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}