US 5,705,794 A · Combined heating cycles to improve efficiency in inductive heating operations

Abstract

Our induction heating workcell permits rapid and controlled heating and cooling of a workpiece within a wide temperature range. The induction workcell allows us to combine manufacturing operations, like SPF, brazing, and annealing, into a single heating cycle to save time, energy, capital, touch labor, and factory space. Superplastic forming (SPF) and brazing occur at temperatures that differ by about 150.degree.-200.degree. F. (85.degree.-105.degree. C.) or more as do SPF and .beta.-annealing of titanium. We can combine these operations into an economical single cycle in which both operations are done during a single heating of the press Multisheet SPF parts with braze joints at selected locations are made by (a) heating a multisheet pack to its superplastic forming range below the melting point of the braze alloy, (b) superplastically forming the pack at the SPF temperature to form the sheets and to define braze joints having unmelted braze alloy, (c) increasing the temperature to the braze temperature of the braze alloy, and (d) cooling the pack below the superplastic range to freeze the braze alloy in the braze joint.

Claims16

Dependent claims

A combined cycle manufacturing method for making an annealed, multisheet part having braze joints between adjacent sheets at selected locations, the metal being formable superplastically in a superplastic forming temperature range, a braze alloy used to form the braze joints having a melting point, comprising the steps of:

(a) assembling a pack of a plurality of sheets of sheet metal having braze alloy affixed to at least one sheet at selected locations corresponding to the location of braze joints in the part;
(b) loading the pack to a press;
(c) heating the pack to a first superplastic forming temperature within the superplastic forming range;
(d) superplastically forming the pack at the first superplastic forming temperature to define a selected core geometry for the part and to define the braze joints;
(e) heating the pack above the first superplastic forming temperature to the melting point of the braze alloy to allow the braze alloy to flow in the areas of the braze joints;
(f) annealing the part at a second, annealing temperature above the first superplastic forming temperature;
(g) cooling the part at a controlled rate from the annealing temperature to below the first superplastic forming temperature and to below the superplastic forming temperature range (1) to obtain a desired microstructure, (2) to freeze the braze alloy in the braze joint, and (3) to finish the part;
and
(h) removing the finished part from the press.

6 more elements

Dependencies are inferred from the claim text.

Combined heating cycles to improve efficiency in inductive heating operations

Life of this patent

Combined heating cycles to improve efficiency in inductive heating operations

Life of this patent

Abstract

Claims16