Fotografie \u010depu jasn\u011b odhalily otisky n\u00e1raz\u016f na ofr\u00e9zovan\u00fdch ploch\u00e1ch. Makro sn\u00edmky lomov\u00e9 plochy uk\u00e1zaly \u0161\u00ed\u0159en\u00ed lomu z obou stran sm\u011brem do st\u0159edu, kde do\u0161lo k definitivn\u00edmu poru\u0161en\u00ed p\u0159i p\u0159ekro\u010den\u00ed meze pevnosti.<\/p>\n\n\n\n Fraktografie (SEM sn\u00edmky)<\/strong><\/p>\n\n\n\n Na lomov\u00e9 plo\u0161e byly nalezeny \u0161\u00ed\u0159en\u00e9 striace 4\u20135 \u03bcm<\/strong> typick\u00e9 pro \u00fanavov\u00fd lom p\u0159i st\u0159\u00eddav\u00e9m ohybov\u00e9m nam\u00e1h\u00e1n\u00ed. V centr\u00e1ln\u00ed \u010d\u00e1sti lomu byly patrn\u00e9 znaky p\u0159et\u00ed\u017een\u00ed.<\/p>\n\n\n\n Metalografick\u00e1 anal\u00fdza<\/strong><\/p>\n\n\n\n \u0158ezem \u010depu byly zhotoveny v\u00fdbrusy. Zji\u0161t\u011bna byla sm\u011bs feritu, bainitu a \u010d\u00e1ste\u010dn\u011b transformovan\u00e9ho perlitu. Prim\u00e1rn\u00ed trhliny vznikaly zejm\u00e9na v oblasti r\u00e1diusu.<\/p>\n\n\n\n Sekund\u00e1rn\u00ed trhliny se \u0161\u00ed\u0159ily preferen\u010dn\u011b bainitickou strukturou, kter\u00e1 vykazuje ni\u017e\u0161\u00ed hou\u017eevnatost.<\/p>\n\n\n\n EBSD a EDS anal\u00fdza<\/strong><\/p>\n\n\n\n EBSD mapy prok\u00e1zaly cementovanou vrstvu do hloubky 0,8 mm s martenzitickou strukturou, kter\u00e1 p\u0159ech\u00e1z\u00ed ve feriticko-bainitickou a d\u00e1le feriticko-perlitickou.<\/p>\n\n\n\n Chemick\u00e9 slo\u017een\u00ed podle EDS odpov\u00eddalo oceli \u010cSN 14220, obsah uhl\u00edku byl odhadnut na cca 0,25 %.<\/p>\n\n\n\n V\u00fdsledky a interpretace<\/strong><\/p>\n\n\n\n Fraktografick\u00e1 anal\u00fdza prok\u00e1zala, \u017ee selh\u00e1n\u00ed \u010depu bylo zp\u016fsobeno n\u00edzkocyklovou \u00fanavou p\u0159i st\u0159\u00eddav\u00e9m ohybu, p\u0159i\u010dem\u017e trhliny vznikaly v oblasti r\u00e1diusu a 3 mm nad n\u00edm. Materi\u00e1l i tepeln\u00e9 zpracov\u00e1n\u00ed odpov\u00eddaly p\u0159edepsan\u00fdm norm\u00e1m, tak\u017ee porucha nevznikla v d\u016fsledku vady materi\u00e1lu \u010di chybn\u00e9ho tepeln\u00e9ho zpracov\u00e1n\u00ed.<\/p>\n\n\n\n Pravd\u011bpodobnou p\u0159\u00ed\u010dinou selh\u00e1n\u00ed bylo nedostate\u010dn\u00e9 dota\u017een\u00ed matice, kv\u016fli kter\u00e9mu \u010dep nedol\u00e9hal t\u011bsn\u011b k fr\u00e9zovan\u00e9 plo\u0161e h\u0159\u00eddele. To umo\u017e\u0148ovalo vznik mikroohyb\u016f p\u0159i n\u00e1razech na dorazy, co\u017e postupn\u011b vedlo k \u0161\u00ed\u0159en\u00ed \u00fanavov\u00e9 trhliny.<\/p>\n\n\n\n Pro prevenci opakov\u00e1n\u00ed podobn\u00e9 poruchy je proto kl\u00ed\u010dov\u00e9 zajistit spr\u00e1vn\u00e9 dota\u017een\u00ed spoj\u016f a p\u0159esn\u00e9 dosednut\u00ed \u010depu, \u010d\u00edm\u017e se eliminuje vznik mikroohyb\u016f a prodlou\u017e\u00ed \u017eivotnost cel\u00e9ho mechanizmu.<\/p>\n\n\n\n <\/p>\n","protected":false},"excerpt":{"rendered":" Praskl\u00fd \u010dep dok\u00e1\u017ee zastavit i ten nejv\u00fdkonn\u011bj\u0161\u00ed stroj. Spole\u010dnost RETOS VARNSDORF proto po\u017e\u00e1dala odborn\u00edky z Technick\u00e9 univerzity v Liberci o detailn\u00ed fraktografickou anal\u00fdzu. Zkouman\u00fd d\u00edl byl sou\u010d\u00e1st\u00ed rota\u010dn\u00ed h\u0159\u00eddele ruky manipul\u00e1toru, kde \u010dep plnil funkci dorazu p\u0159i kontaktu se stav\u011bc\u00edmi \u0161rouby. V d\u016fsledku n\u00e1raz\u016f doch\u00e1zelo k ohybov\u00e9mu nam\u00e1h\u00e1n\u00ed \u010depu, co\u017e vy\u00fastilo v jeho selh\u00e1n\u00ed. Odborn\u00edci […]<\/p>\n","protected":false},"author":1,"featured_media":613,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[14],"_links":{"self":[{"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=\/wp\/v2\/posts\/598"}],"collection":[{"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=598"}],"version-history":[{"count":3,"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=\/wp\/v2\/posts\/598\/revisions"}],"predecessor-version":[{"id":618,"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=\/wp\/v2\/posts\/598\/revisions\/618"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=\/wp\/v2\/media\/613"}],"wp:attachment":[{"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=598"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=598"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/support4sme.cxi.tul.cz\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=598"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/support4sme.cxi.tul.cz\/wp-content\/uploads\/2025\/09\/Obrazek2.png\")
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