{"id":9961,"date":"2026-07-27T17:39:05","date_gmt":"2026-07-27T09:39:05","guid":{"rendered":"https:\/\/www.clirik.com\/?p=9961"},"modified":"2026-07-27T17:39:07","modified_gmt":"2026-07-27T09:39:07","slug":"reparation-du-systeme-hydraulique-du-reducteur-dun-broyeur-a-rouleaux-vertical","status":"publish","type":"post","link":"https:\/\/www.clirik.com\/fr\/reparation-du-systeme-hydraulique-du-reducteur-dun-broyeur-a-rouleaux-vertical\/","title":{"rendered":"R\u00e9paration du r\u00e9ducteur et du syst\u00e8me hydraulique d'un broyeur \u00e0 rouleaux vertical"},"content":{"rendered":"<div class=\"wp-block-themepark-block-themepark-wright content-super-p  blog-jiange\" style=\"font-size:17px;line-height:28px;color:#211c1c;padding:10px 20px;\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<p class=\"wp-block-paragraph\">Pour rem\u00e9dier \u00e0 la surchauffe et au bruit anormaux du r\u00e9ducteur du broyeur vertical (broyeur \u00e0 rouleaux vertical) ainsi qu\u2019aux chutes de pression fr\u00e9quentes du syst\u00e8me hydraulique, il est essentiel d\u2019identifier imm\u00e9diatement les deux probl\u00e8mes principaux : la \u201c charge partielle de la but\u00e9e de pouss\u00e9e \u201d et la \u201c d\u00e9faillance de la vessie d\u2019azote de l\u2019accumulateur \u00bb. Si ces deux d\u00e9faillances critiques sont mal diagnostiqu\u00e9es, cela aboutit souvent \u00e0 la fissuration des dents des engrenages plan\u00e9taires ou des rouleaux de broyage. Vous le savez, une heure d'arr\u00eat entra\u00eene des pertes se chiffrant en dizaines de milliers de yuan. Si vous souhaitez identifier la cause r\u00e9elle, la seule solution infaillible consiste \u00e0 v\u00e9rifier la courbe de contre-pression du v\u00e9rin hydraulique et la vitesse de vibration de l\u2019arbre d\u2019entr\u00e9e du r\u00e9ducteur (mm\/s). L\u2019ensemble suivant de logiques de d\u00e9pannage avanc\u00e9es et de param\u00e8tres de maintenance essentiels a en r\u00e9alit\u00e9 \u00e9t\u00e9 r\u00e9sum\u00e9 sur site par des experts en r\u00e9vision de niveau constructeur (OEM).<\/p>\n\n\n\n<iframe loading=\"lazy\" width=\"1080\" height=\"608\" src=\"https:\/\/www.youtube.com\/embed\/HIOjy442Gco\" title=\"Contr\u00f4le des vannes et d\u00e9tection des fuites par ultrasons\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n\n\n\n<h3 class=\"wp-block-heading\">M\u00e9thode d'isolation et d'analyse V-P-T : d\u00e9cortiquer les d\u00e9fauts complexes<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Une d\u00e9faillance complexe d'un broyeur vertical n'est jamais un cas isol\u00e9. Pour identifier avec pr\u00e9cision la source du probl\u00e8me, vous devez vous appuyer sur le cadre de d\u00e9pannage \u201c V-P-T \u201d (vibrations, pression, temp\u00e9rature).<br>Premi\u00e8re \u00e9tape : v\u00e9rifier la pression (Pression). La diff\u00e9rence de pression dynamique entre la pression de tension r\u00e9gl\u00e9e par le syst\u00e8me hydraulique et la pression r\u00e9elle d\u00e9velopp\u00e9e d\u00e9termine directement la stabilit\u00e9 du lit de disques de broyage. Si le lit de mati\u00e8re est instable, l\u2019\u00e9norme force d\u2019impact se r\u00e9percutera sur le \u00ab dragon jaune \u00bb le long du disque de broyage et atteindra le r\u00e9ducteur.<br>Deuxi\u00e8me \u00e9tape : surveiller attentivement la temp\u00e9rature (Temp\u00e9rature). Si la sonde de mesure de temp\u00e9rature RTD enfouie dans l'alliage Babuton de la tuile de pouss\u00e9e enregistre une hausse instantan\u00e9e de temp\u00e9rature (sup\u00e9rieure \u00e0 65 \u00b0C), cela signifie sans aucun doute que le film d'huile de transmission hydraulique est d\u00e9finitivement rompu, ou que la force exerc\u00e9e sur la tige de traction hydraulique est tr\u00e8s in\u00e9gale.<br>\u00c9tape 3 : Analysez les vibrations (Vibration). Affichez la carte des hautes fr\u00e9quences du r\u00e9ducteur. Si vous constatez que le pic de la fr\u00e9quence d'engr\u00e8nement (GMF) est net et bien d\u00e9fini, et qu'il s'accompagne d'une bande lat\u00e9rale dense, la conclusion est sans appel : la surface des dents a subi une d\u00e9formation plastique irr\u00e9versible.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Vertical_Mill_Reducer_Dead_Hole_and_Solution_of_High_Frequency_Failure\"><\/span>R\u00e9ducteur de broyeur vertical : \u00ab trou mort \u00bb et solution aux d\u00e9faillances \u00e0 haute fr\u00e9quence<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Pour rem\u00e9dier \u00e0 la d\u00e9faillance du r\u00e9ducteur du broyeur vertical, il est n\u00e9cessaire de se concentrer simultan\u00e9ment sur les deux aspects que sont les \u201c roulements \u201d et la \u201c lubrification \u201d. Sous l'effet d'une charge dynamique, tout \u00e9cart de tol\u00e9rance g\u00e9om\u00e9trique de l'ordre du micron sera amplifi\u00e9 \u00e0 l'infini.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Premiers secours en cas de br\u00fblure et de d\u00e9formation thermique des tuiles de pouss\u00e9e<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">La cause de l'usure des tuiles de pouss\u00e9e r\u00e9side dans l'effondrement instantan\u00e9 du film d'huile hydraulique. D\u00e8s que le broyeur avale de gros morceaux de minerai dur ou que l'\u00e9paisseur du lit de mati\u00e8re diminue brusquement, la charge d'impact instantan\u00e9e peut facilement percer le film d'huile de l'ordre du micron qui s\u00e9pare la tuile de pouss\u00e9e de la base du broyeur.<br>Dans ce cas, il faut imm\u00e9diatement pr\u00e9lever un \u00e9chantillon de l\u2019\u00e9l\u00e9ment filtrant du syst\u00e8me de lubrification du r\u00e9ducteur. Si vous apercevez \u00e0 l\u2019\u0153il nu des copeaux de babbit brillants, n\u2019h\u00e9sitez pas \u00e0 vous arr\u00eater et \u00e0 ouvrir le bo\u00eetier imm\u00e9diatement. La r\u00e8gle d\u2019or pour les r\u00e9parations d\u2019urgence sur site est la suivante : lorsque la surface de contact est racl\u00e9e avec du bleu de Prusse, il faut s\u2019assurer que la plaquette de but\u00e9e pr\u00e9sente au moins 3 \u00e0 4 points de contact par centim\u00e8tre carr\u00e9. La diff\u00e9rence de hauteur entre toutes les tuiles apr\u00e8s installation doit \u00eatre inf\u00e9rieure \u00e0 0,02 mm. D\u00e8s que cette valeur maximale d\u00e9passe la norme, une seule tuile devra supporter le double de la force axiale, et la tuile br\u00fblera \u00e0 nouveau d\u00e8s le d\u00e9marrage de la machine.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img title=\"High-Definition Comparison Images Of Contact Points On A Thrust Pad&apos;s Babbitt Lining. The Left Side Shows Severe Scuffing Or Smearing Marks, While The Right Side Displays Blue Markings Indicating Full Compliance With Contact Point Standards Following Manual Scraping.\" loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"576\" src=\"https:\/\/www.clirik.com\/wp-content\/uploads\/2026\/07\/pasted-image-20260727-092931-188-1024x576.png\" alt=\"Images comparatives en haute d\u00e9finition des points de contact sur le rev\u00eatement en Babbitt d&#039;un patin de pouss\u00e9e. Le c\u00f4t\u00e9 gauche pr\u00e9sente de graves traces de rayures ou de frottement, tandis que le c\u00f4t\u00e9 droit affiche des marques bleues indiquant une conformit\u00e9 totale aux normes relatives aux points de contact apr\u00e8s un raclage manuel.\" class=\"wp-image-9963\" srcset=\"https:\/\/www.clirik.com\/wp-content\/uploads\/2026\/07\/pasted-image-20260727-092931-188-1024x576.png 1024w, https:\/\/www.clirik.com\/wp-content\/uploads\/2026\/07\/pasted-image-20260727-092931-188-300x169.png 300w, https:\/\/www.clirik.com\/wp-content\/uploads\/2026\/07\/pasted-image-20260727-092931-188-768x432.png 768w, https:\/\/www.clirik.com\/wp-content\/uploads\/2026\/07\/pasted-image-20260727-092931-188-1536x864.png 1536w, https:\/\/www.clirik.com\/wp-content\/uploads\/2026\/07\/pasted-image-20260727-092931-188-18x10.png 18w, https:\/\/www.clirik.com\/wp-content\/uploads\/2026\/07\/pasted-image-20260727-092931-188.png 1672w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Micropitting des engrenages plan\u00e9taires : cause du probl\u00e8me et solutions sur site<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">La micro-piq\u00fbre au niveau d'un \u00e9tage d'engrenage plan\u00e9taire est souvent due \u00e0 la pr\u00e9sence de particules d'huile et \u00e0 une surcharge due aux contraintes de contact. Bien que la micro-piq\u00fbre n'entra\u00eene pas la rupture imm\u00e9diate de l'engrenage, elle endommage de mani\u00e8re irr\u00e9versible le profil involutif des dents, ce qui provoque l'\u00e9mission par la machine d'un grincement aigu extr\u00eamement d\u00e9sagr\u00e9able.<br>Les donn\u00e9es de d\u00e9tection de la taille des particules d'huile (ISO 4406) constituent la r\u00e9f\u00e9rence la plus pr\u00e9cise. Si le code ISO d\u00e9passe les seuils critiques de 18\/16\/13, cela signifie qu\u2019une usure par abrasion ronge la surface des dents. La mesure d\u2019urgence \u00e0 prendre sur site ne consiste en aucun cas \u00e0 changer aveugl\u00e9ment d\u2019engrenage, mais \u00e0 retirer imm\u00e9diatement un filtre \u00e0 huile \u00e0 d\u00e9shydratation sous vide hors ligne d\u2019une pr\u00e9cision de 3 microns et \u00e0 remplacer l\u2019huile par une huile pour engrenages enti\u00e8rement synth\u00e9tique \u00e0 haute viscosit\u00e9 (telle que l\u2019ISO VG 320) riche en additifs extr\u00eame pression (EP). Pour les dents pr\u00e9sentant un \u00e9caillage visible, chanfreiner les ar\u00eates \u00e0 l\u2019aide d\u2019une meuleuse de pr\u00e9cision portable. Cette \u00e9tape vise \u00e0 \u00e9liminer le point de concentration de contraintes local et \u00e0 emp\u00eacher la fissure de se propager jusqu\u2019\u00e0 la racine de la dent.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Tableau de corr\u00e9lation entre le spectre de vibrations des bo\u00eetes de vitesses et le diagnostic des d\u00e9fauts<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Type de d\u00e9faut \/ de panne<\/td><td>Param\u00e8tres de fr\u00e9quence dominante<\/td><td>Caract\u00e9ristiques du spectre et pics de tension<\/td><td>Remarques de diagnostic et mesures correctives<\/td><\/tr><tr><td><strong>D\u00e9s\u00e9quilibre<\/strong><\/td><td><strong>1X<\/strong>&nbsp;(Vitesse de rotation de l'arbre)<\/td><td>Flamb\u00e9e de&nbsp;<strong>1X<\/strong>&nbsp;Amplitude radiale. Faibles vibrations axiales. Les harmoniques sup\u00e9rieures (2X, 3X) sont g\u00e9n\u00e9ralement tr\u00e8s faibles, voire inexistantes.<\/td><td>Ceci est principalement d\u00fb \u00e0 l'excentricit\u00e9 de la masse sur l'engrenage ou l'arbre. Ce probl\u00e8me est r\u00e9solu par un \u00e9quilibrage de pr\u00e9cision du rotor.<\/td><\/tr><tr><td><strong>D\u00e9salignement<\/strong><\/td><td><strong>1X, 2X<\/strong><\/td><td>Flamb\u00e9e de&nbsp;<strong>2X<\/strong>&nbsp;vibration radiale ou \u00e9lev\u00e9e&nbsp;<strong>1X \/ 2X<\/strong>&nbsp;vibration axiale. Rapport \u00e9lev\u00e9 entre les vibrations axiales et radiales.<\/td><td>Indique un d\u00e9salignement angulaire ou parall\u00e8le. Correction effectu\u00e9e par alignement de l'arbre au laser de haute pr\u00e9cision.<\/td><\/tr><tr><td><strong>Dents cass\u00e9es<\/strong><\/td><td><strong>GMF<\/strong>&nbsp;&amp;&nbsp;<strong>1X bandes lat\u00e9rales<\/strong><\/td><td>Flamb\u00e9e de&nbsp;<strong>Fr\u00e9quence d'engr\u00e8nement (GMF)<\/strong>&nbsp;amplitude. Pr\u00e9sence de \u00e9l\u00e9ments distincts&nbsp;<strong>1X<\/strong>&nbsp;bandes lat\u00e9rales autour du GMF. La courbe temporelle montre des impulsions d'impact 1X bien marqu\u00e9es.<\/td><td>D\u00e9faillance structurelle grave. Pour les dents pr\u00e9sentant un effritement macroscopique avant une rupture compl\u00e8te, utilisez des outils de meulage de pr\u00e9cision portatifs afin de chanfreiner les ar\u00eates, dans le but d\u2019\u00e9liminer les points de concentration de contraintes localis\u00e9s et de pr\u00e9venir les fissures radiculaires.<\/td><\/tr><tr><td><strong>Micro-piq\u00fbres \/ Piq\u00fbres<\/strong><\/td><td><strong>GMF<\/strong>&nbsp;&amp;&nbsp;<strong>Harmoniques \u00e0 haute fr\u00e9quence<\/strong><\/td><td>Forte hausse de&nbsp;<strong>GMF<\/strong>&nbsp;et ses harmoniques \u00e0 haute fr\u00e9quence, provoquant un sifflement caract\u00e9ristique \u00e0 haute fr\u00e9quence d\u00fb \u00e0 une alt\u00e9ration irr\u00e9versible des profils involut\u00e9s des engrenages.<\/td><td>C'est le r\u00e9sultat d'une surcharge due aux contraintes de contact et d'une contamination par des particules. Diagnostic de base : le nombre de particules dans l'huile, selon la norme ISO 4406, d\u00e9passe les valeurs de 18\/16\/13.&nbsp;<strong>Correction sur le terrain :<\/strong>&nbsp;Mettez imm\u00e9diatement en service un purificateur d'huile \u00e0 d\u00e9shydratation sous vide hors ligne de 3 microns et passez \u00e0 une huile pour engrenages enti\u00e8rement synth\u00e9tique \u00e0 haute viscosit\u00e9 (par exemple, ISO VG 320) contenant des additifs \u00ab Extreme Pressure \u00bb (EP).<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Vertical_mill_hydraulic_system_pressure_drop_disease_and_pollution_control\"><\/span>Syst\u00e8me hydraulique d'un broyeur vertical : probl\u00e8me de perte de charge et contr\u00f4le de la pollution<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Le syst\u00e8me hydraulique est le \u201c muscle \u201d du broyeur vertical. Son r\u00f4le essentiel est de fournir une force de tension constante et d'absorber les violentes vibrations g\u00e9n\u00e9r\u00e9es pendant le processus de broyage. Si le syst\u00e8me ne parvient pas \u00e0 maintenir la pression, ou si la pompe \u00e0 huile d\u00e9marre et s'arr\u00eate fr\u00e9quemment, cela constitue un signe avant-coureur direct d'une d\u00e9faillance totale.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Fuite d'azote de l'accumulateur : le pi\u00e8ge de la \u201c vibration fant\u00f4me \u201d<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Une fuite d\u2019azote au niveau de l\u2019accumulateur provoquera une \u201c vibration fant\u00f4me \u201d tr\u00e8s trompeuse dans l\u2019ensemble de la structure du broyeur. D\u00e8s que la vessie de l\u2019accumulateur se rompt ou que la pression de pr\u00e9charge d\u2019azote s\u2019\u00e9puise, le v\u00e9rin hydraulique perd compl\u00e8tement l\u2019effet d\u2019amortissement et de protection du \u201c ressort \u00e0 gaz \u201c. Dans ce cas, toute la r\u00e9sistance rencontr\u00e9e par le rouleau de broyage se transformera en un choc m\u00e9canique violent, qui frappera directement les fondations et le r\u00e9ducteur. Le personnel de terrain est souvent induit en erreur par ce ph\u00e9nom\u00e8ne et croit \u00e0 tort que le r\u00e9ducteur est gravement endommag\u00e9.<br>Dans ce cas, il est n\u00e9cessaire d'arr\u00eater imm\u00e9diatement la machine et de raccorder l'outil de remplissage d'azote pour mesurer la pression statique. La pression normale de pr\u00e9-remplissage d'azote doit \u00eatre comprise entre 60% et 70% de la pression de service (g\u00e9n\u00e9ralement entre 60 et 80 bars, selon le mod\u00e8le de laminoir). Si vous appuyez sur l'obturateur de la poche en cuir et que de l'huile hydraulique gicle, cela signifie que la poche en cuir est compl\u00e8tement hors d'usage. Lors du remplacement du sac en cuir, n\u2019oubliez pas d\u2019appliquer une couche d\u2019huile hydraulique de la m\u00eame marque que celle du syst\u00e8me avant de l\u2019installer, afin d\u2019\u00e9viter que le sac ne s\u2019entortille ou ne s\u2019emm\u00eale et ne se d\u00e9chire au d\u00e9but du gonflage.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Stagnation et encerclement d'une servovalve proportionnelle et suppression du film de peinture<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">D\u00e8s que la servovalve proportionnelle se bloque, l'\u00e9quilibre entre les pressions de tension de plusieurs rouleaux de broyage est imm\u00e9diatement rompu, ce qui entra\u00eene directement de violentes vibrations m\u00e9caniques du broyeur. Le v\u00e9ritable coupable derri\u00e8re le blocage de la servovalve est en r\u00e9alit\u00e9 le film de r\u00e9sidus g\u00e9n\u00e9r\u00e9 par la d\u00e9gradation thermique et l'oxydation de l'huile hydraulique. Cette substance agit comme de la superglue. Les filtres m\u00e9caniques classiques install\u00e9s sur les conduites ne parviennent pas \u00e0 la retenir.<br>La premi\u00e8re \u00e9tape pour v\u00e9rifier ce probl\u00e8me consiste \u00e0 mesurer la courbe d'hyst\u00e9r\u00e9sis entre le courant de commande de la bobine de la servovalve et le d\u00e9placement r\u00e9el du tiroir. Si le taux de retard d\u00e9passe 5%, on peut globalement conclure que le noyau de pr\u00e9cision de la valve a \u00e9t\u00e9 bloqu\u00e9 par le film de peinture. La solution la plus radicale consiste \u00e0 installer un syst\u00e8me de filtration d\u2019huile \u00e9lectrostatique, afin d\u2019extraire directement les oxydes submicroniques pr\u00e9sents dans l\u2019huile au niveau mol\u00e9culaire, et de ramener de force l\u2019indice colorim\u00e9trique (MPC) de la membrane filtrante microporeuse en dessous de 15. N\u2019utilisez pas ces solvants chimiques agressifs pour rincer violemment le noyau de la valve de pr\u00e9cision, car cela ne ferait que d\u00e9truire son jeu d\u2019ajustement de l\u2019ordre du micron.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Fixing_the_End_Dynamic_Load_Balancing_Doorways\"><\/span>R\u00e9glage de l'extr\u00e9mit\u00e9 : \u00e9quilibrage dynamique de la charge au niveau des passages de porte<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Une fois le r\u00e9ducteur et le syst\u00e8me hydraulique r\u00e9par\u00e9s, il est indispensable de valider l\u201c\u201d \u00e9quilibre dynamique des charges \u00bb avant de mettre l\u2019installation en production \u00e0 pleine charge. Apr\u00e8s avoir remplac\u00e9 le joint du v\u00e9rin hydraulique ou r\u00e9ajust\u00e9 le palier de but\u00e9e du r\u00e9ducteur, il est formellement interdit d\u2019appliquer directement la force de tension hydraulique \u00e0 vide.<br>Vous devez suivre scrupuleusement la proc\u00e9dure de mise en charge progressive. Une fois le moteur principal d\u00e9marr\u00e9, appliquez d'abord une force de tension hydraulique initiale de 30%, puis maintenez la pression pendant 15 minutes \u00e0 chaque augmentation de 10%. Pendant cette p\u00e9riode de rodage, deux s\u00e9ries de donn\u00e9es doivent \u00eatre surveill\u00e9es de pr\u00e8s : premi\u00e8rement, la diff\u00e9rence de pression des v\u00e9rins hydrauliques sur la diagonale doit \u00eatre maintenue \u00e0 moins de 2 bars ; deuxi\u00e8mement, les donn\u00e9es du vibrom\u00e8tre au niveau des si\u00e8ges de roulements d\u2019entr\u00e9e et de sortie du r\u00e9ducteur doivent rester bien en dessous de la limite critique de 4,5 mm\/s. D\u00e8s qu\u2019un de ces deux crit\u00e8res n\u2019est pas respect\u00e9, rel\u00e2chez imm\u00e9diatement la pression, arr\u00eatez la machine, puis recalibrez avec pr\u00e9cision le nivellement m\u00e9canique de la tige de tension.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Part_7_Common_Hardcore_Questions_and_Answers_FAQ\"><\/span>Partie 7 : Questions et r\u00e9ponses courantes sur le hardcore (FAQ)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>1. Comment v\u00e9rifier en toute s\u00e9curit\u00e9 la pression d'azote du circuit hydraulique du broyeur vertical ?<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">La mesure doit \u00eatre effectu\u00e9e apr\u00e8s avoir enti\u00e8rement d\u00e9pressuris\u00e9 le circuit hydraulique. Arr\u00eatez d\u2019abord la pompe hydraulique, ouvrez le clapet anti-retour de retour d\u2019huile, puis purgez compl\u00e8tement la pression du v\u00e9rin hydraulique jusqu\u2019\u00e0 atteindre 0 bar absolu. \u00c0 ce stade, l'appareil d'essai de charge d'azote est raccord\u00e9 \u00e0 la vanne de gaz situ\u00e9e sur le dessus de l'accumulateur, et la valeur relev\u00e9e correspond \u00e0 la pression statique de pr\u00e9charge d'azote la plus r\u00e9elle. Si la pression est mesur\u00e9e, les donn\u00e9es obtenues sont toutes des valeurs erron\u00e9es, et il n'y a absolument aucune fuite.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>2. \u00c0 quoi est due la temp\u00e9rature \u00e9lev\u00e9e de l'huile dans le r\u00e9ducteur d'un broyeur vertical ?<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Les causes les plus \u00e9videntes sont simplement les suivantes : le faisceau tubulaire du refroidisseur est obstru\u00e9 par du tartre, la circulation ne parvient pas \u00e0 suivre en raison de la baisse de d\u00e9bit due au vieillissement de la pompe \u00e0 huile, ou la plaque de pouss\u00e9e subit un frottement \u00e0 sec en raison d\u2019une charge partielle. Lors de la v\u00e9rification, examinez tout d'abord la diff\u00e9rence de temp\u00e9rature entre l'entr\u00e9e et la sortie de l'\u00e9changeur de chaleur \u00e0 calandre et tubes. Si cette diff\u00e9rence de temp\u00e9rature est inf\u00e9rieure \u00e0 5 \u00b0C, cela signifie que le refroidisseur est soit gravement encrass\u00e9, soit obstru\u00e9 par de l'air ; il convient alors de proc\u00e9der imm\u00e9diatement \u00e0 un d\u00e9capage ou \u00e0 une purge.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>3. Comment le v\u00e9rin hydraulique peut-il s'affaisser (glissement du v\u00e9rin) lorsque la pompe est \u00e0 l'arr\u00eat ?<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Cela indique qu\u2019il y a un important \u00e9coulement d\u2019huile \u00e0 l\u2019int\u00e9rieur du v\u00e9rin hydraulique, ou que le clapet anti-retour de commande hydraulique n\u2019est pas \u00e9tanche. Un test de maintien de pression permet de mettre le d\u00e9faut en \u00e9vidence : amenez le v\u00e9rin hydraulique \u00e0 une certaine hauteur, bloquez-le m\u00e9caniquement, puis desserrez d\u2019un tour le raccord de la conduite d\u2019huile au niveau de la cavit\u00e9 de la tige 1. Si du liquide s'\u00e9coule au niveau du raccord, cela signifie que le joint du piston (tel que la bague Glaire ou le joint d'\u00e9tanch\u00e9it\u00e9) est compl\u00e8tement us\u00e9. Si aucune fuite n'est constat\u00e9e, d\u00e9montez la vanne de maintien de pression situ\u00e9e sur le bloc de vannes de commande afin de la nettoyer.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>4. Quelle est la valeur normale des vibrations du r\u00e9ducteur d'un broyeur vertical ?<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Conform\u00e9ment \u00e0 la norme ISO 10816, pour ce r\u00e9ducteur de broyeur vertical \u00e0 usage intensif, la valeur efficace (RMS) de la vitesse de vibration du carter doit \u00eatre inf\u00e9rieure \u00e0 2,8 mm\/s, 4,5 mm\/s constituant le seuil d\u2019alerte ; d\u00e8s que cette valeur d\u00e9passe 7,1 mm\/s, l\u2019arr\u00eat imm\u00e9diat s\u2019impose. En temps normal, on accorde davantage d'attention au pic de l'impulsion de choc (Shock Pulse) sur le spectrogramme, qui peut r\u00e9v\u00e9ler la pr\u00e9sence de microfissures dans le roulement trois mois avant que la vitesse de vibration globale ne d\u00e9passe la norme.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>5. \u00c0 quelle norme doit se conformer la propret\u00e9 de l'huile du syst\u00e8me hydraulique du broyeur vertical ?<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Le syst\u00e8me hydraulique du broyeur vertical repose sur une vanne proportionnelle tr\u00e8s sensible pour fonctionner ; par cons\u00e9quent, la propret\u00e9 de l\u2019huile doit strictement respecter la norme ISO 4406 (16\/14\/11), voire \u00eatre sup\u00e9rieure. Si le contr\u00f4le par \u00e9chantillonnage sur site r\u00e9v\u00e8le que les particules de plus de 4 microns d\u00e9passent la norme, mettez imm\u00e9diatement en service le camion externe \u00e9quip\u00e9 d\u2019un filtre \u00e0 huile \u00e0 circulation haute pression en d\u00e9rivation jusqu\u2019\u00e0 ce que la norme soit respect\u00e9e ; sinon, le v\u00e9rin de levage des rouleaux se bloquera in\u00e9vitablement.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>6. La plaquette de pouss\u00e9e du r\u00e9ducteur peut-elle \u00eatre r\u00e9par\u00e9e sur place si elle est cass\u00e9e ?<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">La r\u00e9paration est possible, mais uniquement en cas de l\u00e9g\u00e8res rayures en surface. Le technicien sur place peut gratter et meuler manuellement la couche d\u2019alliage de Babbitt \u00e0 l\u2019aide d\u2019un grattoir sp\u00e9cial afin de pr\u00e9server la rainure d\u2019huile et la surface de contact de haute pr\u00e9cision. Toutefois, si l\u2019alliage de Babbitt se d\u00e9tache, se d\u00e9lamine sur une grande surface ou fond \u00e0 haute temp\u00e9rature (br\u00fblure), l\u2019ensemble des plaquettes de but\u00e9e doit \u00eatre emball\u00e9 et envoy\u00e9 \u00e0 un atelier de r\u00e9paration professionnel ; l\u2019alliage de Babbitt doit alors \u00eatre coul\u00e9 \u00e0 nouveau et un contr\u00f4le par ultrasons doit \u00eatre effectu\u00e9. Ce type de r\u00e9paration \u00e0 chaud ne peut pas \u00eatre effectu\u00e9 sur le site du broyeur.<\/p>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"themepark_post_bcolor":"#f5f5f5","themepark_post_width":"1022px","themepark_post_img":"","themepark_post_img_po":"left","themepark_post_img_re":false,"themepark_post_img_cover":false,"themepark_post_img_fixed":false,"themepark_post_hide_title":false,"themepark_post_main_b":"","themepark_post_main_p":100,"themepark_paddingblock":false,"_geo_short_summary":"Expert guide to fixing vertical roller mill gearbox overheating and hydraulic system pressure drops. Master the V-P-T protocol to diagnose thrust pad wear, accumulator leaks, and vibration issues, preventing costly downtime and gear failures.","_geo_structured_desc":"This article provides an OEM-level troubleshooting guide for vertical roller mill (VRM) failures, focusing on gearbox (reducer) abnormalities (overheating, noise) and hydraulic system pressure drops. The core methodology is the V-P-T (Vibration, Pressure, Temperature) protocol, which isolates root causes by analyzing hydraulic pressure differentials, thrust pad temperature surges (over 65\u00b0C), and gear mesh frequency (GMF) vibration spectra.\n\n**Gearbox (Reducer) Failure &amp; Solutions:**\n- Immediate root causes of burning thrust pads include oil film collapse from impact loads or material bed instability. Emergency response includes oil filter sampling for babbitt chips, immediate shutdown if found, and precise scraping to achieve 3-4 contact points per square centimeter and a 0.02mm height difference limit across thrust pads.\n- Planetary gear micropitting results from oil particle contamination and contact stress overload. Diagnosis uses ISO 4406 oil particle counts; an ISO code exceeding 18\/16\/13 indicates active abrasive wear. Field remediation involves using a 3-micron offline vacuum dehydration oil filter and switching to high-viscosity full-synthetic ISO VG 320 gear oil with EP additives. For visible peeling, chamfer edges to relieve stress and prevent crack propagation.\n- A detailed vibration spectrum correlation table is provided, linking defects (unbalance, misalignment, broken teeth, micropitting) to specific frequency patterns and corrective actions.\n\n**Hydraulic System Failures &amp; Solutions:**\n- Accumulator nitrogen leakage creates deceptive 'ghost vibrations' that can be misdiagnosed as reducer failure. The fix is to stop the mill and measure static nitrogen pre-charge pressure (must be 60-70% of working pressure, typically 60-80 bar). If hydraulic oil sprays from the valve core, the bladder is ruined and must be replaced with a new one lubricated with system-compatible hydraulic oil.\n- Proportional servo valve sticking is caused by varnish (paint film) from oil degradation. Diagnosis involves measuring the hysteresis curve of the servo valve coil; a lag rate above 5% indicates varnish locking. The remedy is an electrostatic oil filtration system to reduce the MPC index below 15, never using chemical solvents for flushing.\n\n**Post-Repair Dynamic Load Balancing:**\nAfter repair, a ladder loading process is mandatory. Start with 30% initial hydraulic tension, then increase by 10% increments, holding for 15 minutes each. Criteria for success: hydraulic cylinder pressure difference on the diagonal must be within 2 bar, and vibration velocity on the input\/output bearing housings must stay below 4.5 mm\/s.","_geo_faqs":"[{\"question\":\"How to safely test the nitrogen pressure of the vertical mill hydraulic system?\",\"answer\":\"Stop the hydraulic pump first, open the oil return check valve, and completely vent the oil cylinder pressure to an absolute 0 bar. Then connect the nitrogen charging test tool to the gas valve on top of the accumulator and read the static nitrogen pre-charge pressure. If the pressure is measured without complete pressure relief, the data is false and leakage points can be missed.\"},{\"question\":\"What is the reason for the high oil temperature of the vertical mill reducer?\",\"answer\":\"The most direct causes are: cooler tube bundle blockage by scale, reduced circulation due to aging flow of the oil pump, or dry friction of the thrust tile due to partial load. Check the temperature difference between the inlet and outlet of the shell-and-tube heat exchanger. If the difference falls below 5\u00b0C, the cooler is either seriously fouled or air-blocked, so arrange pickling or exhaust immediately.\"},{\"question\":\"How can the hydraulic cylinder fall down (slip cylinder) when the pump is stopped?\",\"answer\":\"This indicates serious internal oil flow in the cylinder or a poorly sealing hydraulic control check valve. Perform a pressure holding test: push the cylinder to height, lock it mechanically, then loosen the rod cavity oil pipe joint a seam. If oil drips, the piston seal is finished. If no oil leaks, remove and clean the pressure retaining valve on the control valve block.\"},{\"question\":\"How much is the vibration value of the vertical mill reducer normal?\",\"answer\":\"Per ISO 10816 for heavy-duty vertical mill reducers, an RMS vibration velocity below 2.8 mm\\\/s is excellent. 4.5 mm\\\/s is the alarm red line, and crossing 7.1 mm\\\/s requires immediate shutdown. Also monitor shock pulse peaks on the spectrogram, as they can expose microcracks in bearings up to 3 months earlier than overall vibration velocity standards.\"},{\"question\":\"What standard should the oil cleanliness of the hydraulic system of the vertical mill be controlled to?\",\"answer\":\"Oil cleanliness must meet or be cleaner than ISO 4406 code 16\\\/14\\\/11, since the system relies on highly sensitive proportional valves. If on-site sampling finds particles larger than 4 microns exceeding the standard, immediately run an external high-pressure circulation bypass oil filter truck until the standard is reached, otherwise the roller lifting cylinder will likely get stuck.\"},{\"question\":\"Can the thrust tile of the reducer be repaired on site if it is broken?\",\"answer\":\"Yes, but only for slight surface scratches. On-site masters can manually scrape and grind the babbitt alloy layer with a special scraper to restore oil grooves and high-precision contact surfaces. However, if the babbitt alloy falls off, delaminates over a large area, or melts at high temperature (burns), the entire set of thrust tiles must be sent to a professional repair shop for re-pouring babbitt alloy and ultrasonic flaw detection. This kind of hot repair cannot be done on the mill site.\"}]","_geo_key_points":"[\"Use the V-P-T (Vibration, Pressure, Temperature) protocol to isolate vertical mill faults: check hydraulic pressure difference, thrust pad RTD temperature (over 65\u00b0C is critical), and gear mesh frequency (GMF) vibration spectrum.\",\"Thrust pad burning is caused by oil film collapse. On-site emergency repair requires scraping to 3-4 contact points per square cm and keeping tile height difference within 0.02mm.\",\"Planetary gear micropitting is diagnosed via ISO 4406 oil analysis; an ISO code above 18\\\/16\\\/13 demands immediate filtration and oil upgrade (ISO VG 320 with EP additives).\",\"Accumulator nitrogen leakage causes 'ghost vibration'\u2014pre-charge must be 60-70% of working pressure (typically 60-80 bar).\",\"Proportional servo valve sticking is often caused by varnish. Check hysteresis (over 5% indicates lock), and remediate with electrostatic filtration to reduce MPC index below 15.\",\"After repairs, always follow a ladder loading process: start with 30% hydraulic tension, increase by 10% every 15 minutes, and ensure diagonal pressure differential stays within 2 bar and vibration remains below 4.5 mm\\\/s.\",\"Vibration velocity RMS below 2.8 mm\\\/s is excellent, 4.5 mm\\\/s is the alarm limit, and 7.1 mm\\\/s demands immediate shutdown per ISO 10816.\",\"Oil cleanliness for the hydraulic system must meet or exceed ISO 4406 code 16\\\/14\\\/11 to prevent proportional valve sticking.\"]","_geo_target_audience":"Maintenance engineers, reliability specialists, and mill operators in cement, mining, and minerals processing industries who are responsible for troubleshooting and repairing vertical roller mill gearboxes and hydraulic systems. They need practical, OEM-level diagnostic procedures, emergency repair parameters, and preventive maintenance guidance to minimize unscheduled downtime and avoid catastrophic equipment failure.","_geo_content_type":"","_geo_last_modified":"2026-09-09T10:21:17+08:00","_geo_version":2,"themepark_seo_title":"Vertical Roller Mill Gearbox & Hydraulic System Fix Guide","themepark_seo_description":"Expert fixes for vertical roller mill gearbox overheating and hydraulic system pressure drops. Master the V-P-T protocol to diagnose thrust pad wear, accumulator leaks, and vibration issues, preventing costly downtime and gear failures.","footnotes":""},"categories":[23],"tags":[],"class_list":["post-9961","post","type-post","status-publish","format-standard","hentry","category-blog"],"metadata":{"_edit_lock":["1785467724:4"],"rank_math_primary_category":["23"],"rank_math_seo_score":["10"],"views":["1074"],"_edit_last":["4"],"themepark_seo_title":["Vertical Roller Mill Gearbox & Hydraulic System Fix Guide"],"themepark_seo_description":["Expert fixes for vertical roller mill gearbox overheating and hydraulic system pressure drops. Master the V-P-T protocol to diagnose thrust pad wear, accumulator leaks, and vibration issues, preventing costly downtime and gear failures."],"themepark_seo_keyword":["Vertical Roller Mill Gearbox\uff0cVertical Roller Mill Hydraulic System"],"catce":["sidebar-widgets4"],"rank_math_og_content_image":["a:2:{s:5:\"check\";s:32:\"50f5eac811c24d4b92a4bd98e2d10619\";s:6:\"images\";a:1:{i:0;i:9963;}}"],"_geo_short_summary":["Expert guide to fixing vertical roller mill gearbox overheating and hydraulic system pressure drops. Master the V-P-T protocol to diagnose thrust pad wear, accumulator leaks, and vibration issues, preventing costly downtime and gear failures."],"_geo_structured_desc":["This article provides an OEM-level troubleshooting guide for vertical roller mill (VRM) failures, focusing on gearbox (reducer) abnormalities (overheating, noise) and hydraulic system pressure drops. The core methodology is the V-P-T (Vibration, Pressure, Temperature) protocol, which isolates root causes by analyzing hydraulic pressure differentials, thrust pad temperature surges (over 65\u00b0C), and gear mesh frequency (GMF) vibration spectra.\n\n**Gearbox (Reducer) Failure &amp; Solutions:**\n- Immediate root causes of burning thrust pads include oil film collapse from impact loads or material bed instability. Emergency response includes oil filter sampling for babbitt chips, immediate shutdown if found, and precise scraping to achieve 3-4 contact points per square centimeter and a 0.02mm height difference limit across thrust pads.\n- Planetary gear micropitting results from oil particle contamination and contact stress overload. Diagnosis uses ISO 4406 oil particle counts; an ISO code exceeding 18\/16\/13 indicates active abrasive wear. Field remediation involves using a 3-micron offline vacuum dehydration oil filter and switching to high-viscosity full-synthetic ISO VG 320 gear oil with EP additives. For visible peeling, chamfer edges to relieve stress and prevent crack propagation.\n- A detailed vibration spectrum correlation table is provided, linking defects (unbalance, misalignment, broken teeth, micropitting) to specific frequency patterns and corrective actions.\n\n**Hydraulic System Failures &amp; Solutions:**\n- Accumulator nitrogen leakage creates deceptive 'ghost vibrations' that can be misdiagnosed as reducer failure. The fix is to stop the mill and measure static nitrogen pre-charge pressure (must be 60-70% of working pressure, typically 60-80 bar). If hydraulic oil sprays from the valve core, the bladder is ruined and must be replaced with a new one lubricated with system-compatible hydraulic oil.\n- Proportional servo valve sticking is caused by varnish (paint film) from oil degradation. Diagnosis involves measuring the hysteresis curve of the servo valve coil; a lag rate above 5% indicates varnish locking. The remedy is an electrostatic oil filtration system to reduce the MPC index below 15, never using chemical solvents for flushing.\n\n**Post-Repair Dynamic Load Balancing:**\nAfter repair, a ladder loading process is mandatory. Start with 30% initial hydraulic tension, then increase by 10% increments, holding for 15 minutes each. Criteria for success: hydraulic cylinder pressure difference on the diagonal must be within 2 bar, and vibration velocity on the input\/output bearing housings must stay below 4.5 mm\/s."],"_geo_faqs":["[{\"question\":\"How to safely test the nitrogen pressure of the vertical mill hydraulic system?\",\"answer\":\"Stop the hydraulic pump first, open the oil return check valve, and completely vent the oil cylinder pressure to an absolute 0 bar. Then connect the nitrogen charging test tool to the gas valve on top of the accumulator and read the static nitrogen pre-charge pressure. If the pressure is measured without complete pressure relief, the data is false and leakage points can be missed.\"},{\"question\":\"What is the reason for the high oil temperature of the vertical mill reducer?\",\"answer\":\"The most direct causes are: cooler tube bundle blockage by scale, reduced circulation due to aging flow of the oil pump, or dry friction of the thrust tile due to partial load. Check the temperature difference between the inlet and outlet of the shell-and-tube heat exchanger. If the difference falls below 5\u00b0C, the cooler is either seriously fouled or air-blocked, so arrange pickling or exhaust immediately.\"},{\"question\":\"How can the hydraulic cylinder fall down (slip cylinder) when the pump is stopped?\",\"answer\":\"This indicates serious internal oil flow in the cylinder or a poorly sealing hydraulic control check valve. Perform a pressure holding test: push the cylinder to height, lock it mechanically, then loosen the rod cavity oil pipe joint a seam. If oil drips, the piston seal is finished. If no oil leaks, remove and clean the pressure retaining valve on the control valve block.\"},{\"question\":\"How much is the vibration value of the vertical mill reducer normal?\",\"answer\":\"Per ISO 10816 for heavy-duty vertical mill reducers, an RMS vibration velocity below 2.8 mm\\\/s is excellent. 4.5 mm\\\/s is the alarm red line, and crossing 7.1 mm\\\/s requires immediate shutdown. Also monitor shock pulse peaks on the spectrogram, as they can expose microcracks in bearings up to 3 months earlier than overall vibration velocity standards.\"},{\"question\":\"What standard should the oil cleanliness of the hydraulic system of the vertical mill be controlled to?\",\"answer\":\"Oil cleanliness must meet or be cleaner than ISO 4406 code 16\\\/14\\\/11, since the system relies on highly sensitive proportional valves. If on-site sampling finds particles larger than 4 microns exceeding the standard, immediately run an external high-pressure circulation bypass oil filter truck until the standard is reached, otherwise the roller lifting cylinder will likely get stuck.\"},{\"question\":\"Can the thrust tile of the reducer be repaired on site if it is broken?\",\"answer\":\"Yes, but only for slight surface scratches. On-site masters can manually scrape and grind the babbitt alloy layer with a special scraper to restore oil grooves and high-precision contact surfaces. However, if the babbitt alloy falls off, delaminates over a large area, or melts at high temperature (burns), the entire set of thrust tiles must be sent to a professional repair shop for re-pouring babbitt alloy and ultrasonic flaw detection. This kind of hot repair cannot be done on the mill site.\"}]"],"_geo_key_points":["[\"Use the V-P-T (Vibration, Pressure, Temperature) protocol to isolate vertical mill faults: check hydraulic pressure difference, thrust pad RTD temperature (over 65\u00b0C is critical), and gear mesh frequency (GMF) vibration spectrum.\",\"Thrust pad burning is caused by oil film collapse. On-site emergency repair requires scraping to 3-4 contact points per square cm and keeping tile height difference within 0.02mm.\",\"Planetary gear micropitting is diagnosed via ISO 4406 oil analysis; an ISO code above 18\\\/16\\\/13 demands immediate filtration and oil upgrade (ISO VG 320 with EP additives).\",\"Accumulator nitrogen leakage causes 'ghost vibration'\u2014pre-charge must be 60-70% of working pressure (typically 60-80 bar).\",\"Proportional servo valve sticking is often caused by varnish. Check hysteresis (over 5% indicates lock), and remediate with electrostatic filtration to reduce MPC index below 15.\",\"After repairs, always follow a ladder loading process: start with 30% hydraulic tension, increase by 10% every 15 minutes, and ensure diagonal pressure differential stays within 2 bar and vibration remains below 4.5 mm\\\/s.\",\"Vibration velocity RMS below 2.8 mm\\\/s is excellent, 4.5 mm\\\/s is the alarm limit, and 7.1 mm\\\/s demands immediate shutdown per ISO 10816.\",\"Oil cleanliness for the hydraulic system must meet or exceed ISO 4406 code 16\\\/14\\\/11 to prevent proportional valve sticking.\"]"],"_geo_target_audience":["Maintenance engineers, reliability specialists, and mill operators in cement, mining, and minerals processing industries who are responsible for troubleshooting and repairing vertical roller mill gearboxes and hydraulic systems. They need practical, OEM-level diagnostic procedures, emergency repair parameters, and preventive maintenance guidance to minimize unscheduled downtime and avoid catastrophic equipment failure."],"_geo_manual_overrides":["[\"_geo_short_summary\",\"_geo_structured_desc\",\"_geo_faqs\",\"_geo_key_points\",\"_geo_target_audience\"]"],"_geo_last_modified":["2026-09-09T10:21:17+08:00"],"_geo_version":["2"],"_geo_has_data":["1"],"_geo_ai_search_text":["Vertical Roller Mill Gearbox &amp; Hydraulic System Fix\nExpert guide to fixing vertical roller mill gearbox overheating and hydraulic system pressure drops. Master the V-P-T protocol to diagnose thrust pad wear, accumulator leaks, and vibration issues, preventing costly downtime and gear failures.\nThis article provides an OEM-level troubleshooting guide for vertical roller mill (VRM) failures, focusing on gearbox (reducer) abnormalities (overheating, noise) and hydraulic system pressure drops. The core methodology is the V-P-T (Vibration, Pressure, Temperature) protocol, which isolates root causes by analyzing hydraulic pressure differentials, thrust pad temperature surges (over 65\u00b0C), and gear mesh frequency (GMF) vibration spectra.\n\n**Gearbox (Reducer) Failure &amp; Solutions:**\n- Immediate root causes of burning thrust pads include oil film collapse from impact loads or material bed instability. Emergency response includes oil filter sampling for babbitt chips, immediate shutdown if found, and precise scraping to achieve 3-4 contact points per square centimeter and a 0.02mm height difference limit across thrust pads.\n- Planetary gear micropitting results from oil particle contamination and contact stress overload. Diagnosis uses ISO 4406 oil particle counts; an ISO code exceeding 18\/16\/13 indicates active abrasive wear. Field remediation involves using a 3-micron offline vacuum dehydration oil filter and switching to high-viscosity full-synthetic ISO VG 320 gear oil with EP additives. For visible peeling, chamfer edges to relieve stress and prevent crack propagation.\n- A detailed vibration spectrum correlation table is provided, linking defects (unbalance, misalignment, broken teeth, micropitting) to specific frequency patterns and corrective actions.\n\n**Hydraulic System Failures &amp; Solutions:**\n- Accumulator nitrogen leakage creates deceptive 'ghost vibrations' that can be misdiagnosed as reducer failure. The fix is to stop the mill and measure static nitrogen pre-charge pressure (must be 60-70% of working pressure, typically 60-80 bar). If hydraulic oil sprays from the valve core, the bladder is ruined and must be replaced with a new one lubricated with system-compatible hydraulic oil.\n- Proportional servo valve sticking is caused by varnish (paint film) from oil degradation. Diagnosis involves measuring the hysteresis curve of the servo valve coil; a lag rate above 5% indicates varnish locking. The remedy is an electrostatic oil filtration system to reduce the MPC index below 15, never using chemical solvents for flushing.\n\n**Post-Repair Dynamic Load Balancing:**\nAfter repair, a ladder loading process is mandatory. Start with 30% initial hydraulic tension, then increase by 10% increments, holding for 15 minutes each. Criteria for success: hydraulic cylinder pressure difference on the diagonal must be within 2 bar, and vibration velocity on the input\/output bearing housings must stay below 4.5 mm\/s.\nUse the V-P-T (Vibration, Pressure, Temperature) protocol to isolate vertical mill faults: check hydraulic pressure difference, thrust pad RTD temperature (over 65\u00b0C is critical), and gear mesh frequency (GMF) vibration spectrum. Thrust pad burning is caused by oil film collapse. On-site emergency repair requires scraping to 3-4 contact points per square cm and keeping tile height difference within 0.02mm. Planetary gear micropitting is diagnosed via ISO 4406 oil analysis; an ISO code above 18\/16\/13 demands immediate filtration and oil upgrade (ISO VG 320 with EP additives). Accumulator nitrogen leakage causes 'ghost vibration'\u2014pre-charge must be 60-70% of working pressure (typically 60-80 bar). Proportional servo valve sticking is often caused by varnish. Check hysteresis (over 5% indicates lock), and remediate with electrostatic filtration to reduce MPC index below 15. After repairs, always follow a ladder loading process: start with 30% hydraulic tension, increase by 10% every 15 minutes, and ensure diagonal pressure differential stays within 2 bar and vibration remains below 4.5 mm\/s. Vibration velocity RMS below 2.8 mm\/s is excellent, 4.5 mm\/s is the alarm limit, and 7.1 mm\/s demands immediate shutdown per ISO 10816. Oil cleanliness for the hydraulic system must meet or exceed ISO 4406 code 16\/14\/11 to prevent proportional valve sticking.\nHow to safely test the nitrogen pressure of the vertical mill hydraulic system?\nStop the hydraulic pump first, open the oil return check valve, and completely vent the oil cylinder pressure to an absolute 0 bar. Then connect the nitrogen charging test tool to the gas valve on top of the accumulator and read the static nitrogen pre-charge pressure. If the pressure is measured without complete pressure relief, the data is false and leakage points can be missed.\nWhat is the reason for the high oil temperature of the vertical mill reducer?\nThe most direct causes are: cooler tube bundle blockage by scale, reduced circulation due to aging flow of the oil pump, or dry friction of the thrust tile due to partial load. Check the temperature difference between the inlet and outlet of the shell-and-tube heat exchanger. If the difference falls below 5\u00b0C, the cooler is either seriously fouled or air-blocked, so arrange pickling or exhaust immediately.\nHow can the hydraulic cylinder fall down (slip cylinder) when the pump is stopped?\nThis indicates serious internal oil flow in the cylinder or a poorly sealing hydraulic control check valve. Perform a pressure holding test: push the cylinder to height, lock it mechanically, then loosen the rod cavity oil pipe joint a seam. If oil drips, the piston seal is finished. If no oil leaks, remove and clean the pressure retaining valve on the control valve block.\nHow much is the vibration value of the vertical mill reducer normal?\nPer ISO 10816 for heavy-duty vertical mill reducers, an RMS vibration velocity below 2.8 mm\/s is excellent. 4.5 mm\/s is the alarm red line, and crossing 7.1 mm\/s requires immediate shutdown. Also monitor shock pulse peaks on the spectrogram, as they can expose microcracks in bearings up to 3 months earlier than overall vibration velocity standards.\nWhat standard should the oil cleanliness of the hydraulic system of the vertical mill be controlled to?\nOil cleanliness must meet or be cleaner than ISO 4406 code 16\/14\/11, since the system relies on highly sensitive proportional valves. If on-site sampling finds particles larger than 4 microns exceeding the standard, immediately run an external high-pressure circulation bypass oil filter truck until the standard is reached, otherwise the roller lifting cylinder will likely get stuck.\nCan the thrust tile of the reducer be repaired on site if it is broken?\nYes, but only for slight surface scratches. On-site masters can manually scrape and grind the babbitt alloy layer with a special scraper to restore oil grooves and high-precision contact surfaces. However, if the babbitt alloy falls off, delaminates over a large area, or melts at high temperature (burns), the entire set of thrust tiles must be sent to a professional repair shop for re-pouring babbitt alloy and ultrasonic flaw detection. This kind of hot repair cannot be done on the mill site.\nMaintenance engineers, reliability specialists, and mill operators in cement, mining, and minerals processing industries who are responsible for troubleshooting and repairing vertical roller mill gearboxes and hydraulic systems. They need practical, OEM-level diagnostic procedures, emergency repair parameters, and preventive maintenance guidance to minimize unscheduled downtime and avoid catastrophic equipment failure."]},"views":1074,"medium_url":false,"thumbnail_url":false,"full_url":false,"_links":{"self":[{"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/posts\/9961","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/comments?post=9961"}],"version-history":[{"count":1,"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/posts\/9961\/revisions"}],"predecessor-version":[{"id":9965,"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/posts\/9961\/revisions\/9965"}],"wp:attachment":[{"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/media?parent=9961"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/categories?post=9961"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.clirik.com\/fr\/wp-json\/wp\/v2\/tags?post=9961"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}