Stock material or miscellaneous articles – All metal or with adjacent metals – Foil or filament smaller than 6 mils
Reexamination Certificate
2000-09-22
2002-09-24
Koehler, Robert R. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Foil or filament smaller than 6 mils
C029S623300, C118S718000, C118S724000, C118S725000, C118S050000, C118S600000, C118S075000, C118S506000, C148S516000, C148S527000, C148S530000, C148S536000, C228S018000, C228S176000, C228S221000, C427S124000, C427S251000, C427S255500, C427S294000, C427S295000, C428S615000, C428S674000, C428S675000, C428S680000, C428S681000, C428S938000
Reexamination Certificate
active
06455172
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a laminated ribbon comprising ribbons strongly welded to each other, and a method and apparatus for efficiently producing such a laminated ribbon.
DESCRIPTION OF PRIOR ART
Japanese Patent Laid-Open No. 7-55384 discloses a method for producing a laminated metal ribbon by pressure-welding metal ribbons by rolling in a vacuum chamber, in which the metal ribbons are activated by ion-etching in a vacuum atmosphere at a room temperature, and the pressure welding is carried out at a low draft ratio in rolling. The first feature of this conventional method is that because the pressure welding is carried out at a room temperature, an alloy layer (diffusion layer) is not easily formed in pressure-welded boundary regions, making it suitable for the production of an extremely thin laminated metal ribbon whose properties are extremely deteriorated by the formation of such an alloy layer (diffusion layer). The second feature of this conventional method is that because the pressure welding is carried out in vacuum, there is no welding defect due to inclusion of a gas and the formation of metal oxides, resulting in a laminated metal ribbon having high welding strength between metal ribbons. Thus, the laminated metal ribbon is excellent in workability.
However, the ion-etching is slow in an etching speed, and etching should be conducted to a degree more than the thickness of an oxide layer o achieve strong welding, resulting in poor in productivity. Further, this method is limited to the production of a two-layer laminated metal ribbon made of the same metal or alloy, failing to produce a laminated metal ribbon having a three or more layer structure.
Japanese Patent Laid-Open No. 1-133689 discloses a hot-rolling method comprising the steps of heating stacked sheets of different metals at a temperature between a room temperature and 1400° C. in vacuum or in a controlled atmosphere, and rolling them to provide the laminated metal ribbon. This conventional method provides high welding strength at a high speed without requiring a welding step, enjoying high productivity. Also, it needs a relatively simple apparatus, thus advantageous in low cost in facility. However, because heating is performed before pressure welding, crease may occur in such a thin metal foil as a copper foil of 10 &mgr;m in thickness due to the softening of a thin metal foil and difference in expansion coefficient from another metal foil. Also, it cannot be used without difficulty for the production of coils, poor in productivity.
Also proposed is a low-pressure diffusion welding method. For instance, Japanese Patent Laid-Open No. 60-27481 discloses a method for welding joints comprising the steps of conveying Al and Ti to a cleaning chamber; removing oxide layers formed on their welding surfaces by sputtering (dry etching); conveying them to a position opposing a target means; coating them with Zn, Mg, etc. by sputtering; further forming a coating layer of Si, etc. for preventing the vaporization of Zn, Mg, etc. by sputtering; and conveying them to a diffusion treatment furnace where Al and Ti are welded. Though this method is suitable for the welding of relatively small articles such as joints transportable by a conveyer, it is poor in productivity, because oxide layers are removed from articles to be welded, and two coating layers are formed by sputtering with targets exchanged at least once, and further welding is conducted in a diffusion furnace to which the articles are conveyed. Accordingly, this method is poor in productivity, and it fails to produce continuous laminated metal ribbons without difficulty.
Further, Japanese Patent Laid-Open No. 7-214344 discloses an apparatus for producing a laminate, in which active thin metal layers are formed on a part or all of welding surfaces of three or more sheets simultaneously by sputtering, or contamination layers are removed from them by irradiating beams of an inert gas or metal particles, and the welding surfaces of the sheets are welded to each other. This method is suitable for welding relatively small sheets. However, it is not suitable for the production of continuous laminated metal ribbons.
OBJECT OF THE INVENTION
Accordingly, an object of the present invention is to provide a laminated ribbon constituted by two or more ribbons strongly welded to each other.
Another object of the present invention is to provide a method and apparatus for producing such a laminated ribbon at a low draft ratio efficiently.
SUMMARY OF THE INVENTION
As a result of research on the production of a laminated ribbon having a three or more layer structure by pressure welding in a vacuum chamber, the inventors have found that the productivity of a laminated ribbon is greatly improved by forming a dry-formed film layer on at least one welding surface of ribbons to be welded by a dry film-forming method (vapor deposition method), and that a higher welding strength can be achieved by a heat treatment for thermal diffusion. The present invention has been completed based on these findings.
Thus, the first method for producing a laminated ribbon according to the present invention comprises the steps of (a) forming a dry-formed film layer on at least one welding surface of a first ribbon and a second ribbon in a vacuum chamber, the dry-formed film layer being made of the same material as or a different material from those of the first and second metal ribbons; and (b) pressure-welding the first ribbon to the second ribbon.
In a specific embodiment, the first method for producing a laminated metal ribbon comprises the steps of (a) vapor-depositing a third metal layer on at least one welding surface of a first metal ribbon and a second metal ribbon in a vacuum chamber, said third metal being the same as or different from a metal or an alloy of said first and second metal ribbons; and (b) pressure-welding said first metal ribbon to said second metal ribbon.
The second method for producing a laminated metal ribbon according to the present invention comprises the steps of (a) forming a third metal layer on at least one welding surface of a first metal ribbon and a second metal ribbon by a dry film-forming method in a vacuum chamber, the third metal being the same as or different from a metal or an alloy of the first and second metal ribbons; (b) pressure-welding the first metal ribbon to the second metal ribbon; and (c) subjecting the resultant laminate to a heat treatment for thermal diffusion.
The dry film-forming method is preferably physical vapor deposition method.
The laminated ribbon according to the present invention has a dry-formed film layer between a first ribbon and a second ribbon. In a specific embodiment of the present invention, the laminated metal ribbon has a dry-formed film layer (vapor deposition layer) between a first metal ribbon and a second metal ribbon.
In a preferred embodiment, a diffusion layer is formed in a boundary region between the dry-formed film layer and the first metal ribbon and/or between the dry-formed film layer and the second metal ribbon.
The apparatus for producing a laminated ribbon by pressure-welding ribbons in a vacuum chamber according to the present invention comprises a vacuum chamber comprising (1) a plurality of winding reels for the ribbons; (2) a dry-film-forming means for forming a dry-formed film layer on at least one welding surface of the ribbons taken from the winding reels; (3) rolls for pressure-welding the ribbons with their welding surfaces facing each other; and (4) a winding reel for winding the resultant pressure-welded laminate ribbon.
Guide rolls are preferably disposed at a position opposing the dry-film-forming means. The apparatus for producing a laminated ribbon preferably further comprises a heating means for carrying out a heat treatment for thermal diffusion of the pressure-welded laminate ribbon.
REFERENCES:
patent: 4011982 (1977-03-01), Marancik
patent: 5895723 (1999-04-01), Utz
patent: 60-27481 (1985-02-01), None
patent: 1-133689 (1989-05-01), None
patent: 1-224184
Hanai Noboru
Yano Kentaro
Hitachi Metals Ltd.
Koehler Robert R.
Sughrue & Mion, PLLC
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