Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1991-01-15
1992-03-24
Gorski, Joseph M.
Metal working
Method of mechanical manufacture
Assembling or joining
29447, 29507, 29DIG24, 138140, 219 85, 219 1043, B23P 1102, B21D 3920, H05B 606
Patent
active
050975854
ABSTRACT:
A multi-walled composite tube member is formed from two superimposed pipes having a gap therebetween. The inner pipe is forcibly expanded in excess of the gap to deform and expand the outer pipe. The expander including a mandrel is forced through the aligned pipes while maintaining the longitudinal alignment. The diameter of the mandrel corresponding to the final desired diameter to finally size the composite pipe section and establish a true round inner passage. An induction heating coil operating at a low frequency operating in the range of low hundreds hertz in contrast to a conventional high frequency unit operating at thousands of hertz is coupled to and moved relative to the expanded pipe unit, progressively heats small lengths of the expanded pipe unit. The expanded pipe unit is quenched with a chilled brine solution applied to both surfaces. The brine solution provides a rapid interchange of heat and hardening of the inner liner, while the application to both surfaces improves the hardening of the outer pipe wall. The composite pipe is formed in a single pass to avoid distortion which may occur on each of a plurality of heating passes, and to improve grain growth, minimize cracking and reduce energy consumption and cost.
REFERENCES:
patent: 3914481 (1975-10-01), Bostroem
patent: 4030711 (1977-06-01), Siller
patent: 4332073 (1982-06-01), Yoshida et al.
patent: 4433227 (1984-02-01), Brittin
patent: 4449281 (1984-05-01), Yoshida et al.
patent: 4598857 (1986-07-01), Matsui
"Hardenability of Carbon and Alloy Steels", Jatczak, ASM Handbook, 9th Edition, vol. 1, Properties & Selection, pp. 471-472.
"Heat Treatment of Steel", Machinery's Handbook, 21st Edition, pp. 2140-2141.
Construction Forms, Inc.
Dungba Vo Peter
Gorski Joseph M.
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