The chattering /)henomelloll often occurrillg ill case oj extremely heav)1 cold rolling up to .94 0 0 total reduction has beell illvestiga ted at a Ihreestalld talldem mill. The resulls obtailled are as Jollows : (1) The chatterillg arises Jrom impaired lubricatioll Jar which illstability oj emulsions alld inadequate st"ength oj oil film are res/)ollsible. (2) Th e fluctuatiolls in strip thickness and lellsioll durillg the chalterillg correspolld to the second mode natural vibration(requellcy oj Ihe Toll aligllments. The chattering takes place when the tellsioll flu clllatioll Jrequenc)1 coinsides with the second mode natural./r•equellcy. (3) A theoretical analysis is made all Ih e basis oj NJalhieu's equatioll to predict the stability criterion oj a roll alignment under givell rolling conditiolls. I II order to make the rollillg stable withoul chattering. the stabili(y criterioll. C;C c > (J k jk)2 jll IIlUSt be Julfilled. w here C alld C c : coifficiellts ~(viscous dmll/)ing and critical dall/ping. J k: variatioll ~r rollillg stifflless, alld k : mill moduills combined with equivalent s/)rillg constant ~(stri/) being rolled. U) One oj the IIIOSt /Jractica ble alld ~ffective measure to meet th e above criterioll is the use oj the lubricallt with good lubrici(y. A lIew lubricant containing orgallo-metallic z inc compounds for extreme j)ressure additive is developed to successfully /Jrevent the chatterillg.

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Juvenile polyposis syndrome (JPS) is an autosomal dominant inherited disorder characterized by multiple hamartomatous polyps in the gastrointestinal tract, and is caused by germline mutations in SMAD4 or BMPR1A. 1 However, no pathogenic variant is found in 40% of cases, and one‐fourth of cases occur without a family history. Multiple polyps are typically found in the colon (98%), stomach (14%), duodenum (7%), jejunum, and ileum (7%).This article is protected by copyright. All rights reserved.