Process for straightening a tube

Details Process for straightening a tube Process for straightening a tube

2008-10-08

2010-02-02

Ross, Dana (Department: 3725)

Metal deforming

By use of tool acting during relative rotation between tool...

During rotation of work

C072S099000

Reexamination Certificate

active

07654122

ABSTRACT:
In straightening a tube using a roll straightening machine provided with drum type straightening roll pairs vertically opposingly disposed, at least an outer layer portion of a roll main body is made of elastic material having spring type hardness Hs (JIS K 6301 A type) of 50 to 100 in at least three pairs of straightening rolls on an outlet side of the roll straightening machine, and an offset amount is imparted to a tube engaged in the three pairs, at least, of straightening opposing rolls such that η defined by an equation (1) ranges from 1.0×10−3to 1.5×10−3. The offset amount is set at three positions along a tube axis where the upper and lower rolls of each pair horizontally cross. Therefore, an S/N ratio can be enhanced in an eddy current test from inside of the tube to improve inspection efficiency, and excellent quality accuracy can be ensured in a heat transfer tube used in a steam generator and the like.[Formula⁢⁢1]η=1R×(d2)(1)where a relationship of R=(δ2+L2)/2δ holds, assuming that d (mm) is a tube outside diameter, L (mm) is a roll stand span of the roll straightening machine, and δ (mm) is an offset amount.

REFERENCES:
patent: 2655194 (1953-10-01), Nilsson
patent: 55-103222 (1980-08-01), None
patent: 60-184424 (1985-09-01), None
patent: 61-286205 (1986-12-01), None
patent: 2000-317521 (2000-11-01), None
patent: 2004-330297 (2004-11-01), None
International Preliminary Report on Patentability from the International Bureau of WIPO, dated Nov. 17, 2008.
International Search Report in corresponding PCT/JP2007/058157 dated Jun. 5, 2007.
Written Opinion of the ISA in corresponding PCT/JP2007/058157 dated Jun. 5, 2007 in Japanese language only.

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