Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
2000-02-02
2001-11-06
Koehler, Robert R. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C148S516000, C148S530000, C148S531000, C148S532000, C148S534000, C428S653000, C428S671000, C428S676000, C428S677000, C428S679000, C428S925000, C428S926000, C428S940000
Reexamination Certificate
active
06312834
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a readily drawable clad material having excellent tensile strength and other mechanical strength characteristics and to a manufacturing method therefor and, in particular, makes it possible to provide a clad material for the anode cases or cathode cases of button-type microbatteries, cases for quartz oscillators, cases for various other electronic components, and other types of miniature electronic equipment that require deep drawability.
BACKGROUND ART
Clad materials obtained by bonding a plurality of metals through rolling are integrated materials that preserve the characteristics of individual, metals, and are hence extremely useful in applications in which a plurality of characteristics must be provided at the same time.
For example, cases for button-type microbatteries must have the desired mechanical strength, drawability, corrosion resistance, low contact resistance, and the like. CU/SUS (stainless steel)/Ni, Cu/Fe/Ni, and other clad materials are used for anode cases; and Ni/SUS, Ni/SUS/Ni, Al/SUS/Ni, and other clad materials are used for cathode cases.
In addition, Ni/Fe/Ni, Ni/SUS/Ni, Cu/SUS/Ni, Cu/Fe/Ni, and other clad materials are used for the cases of various electronic components that have specific requirements concerning mechanical strength, drawability, corrosion resistance, weldability, and the like.
Clad materials that function as base materials for such cases are commonly obtained by superposing a plurality of metal sheets constituting a clad material, bonding these sheets by cold rolling, homogenizing the sheets, and subjecting them to finish cold rolling or a combination of finish cold rolling and final annealing. The product may be optionally cut into prescribed lengths.
Clad materials obtained by the aforementioned manufacturing method are molded into cup shapes by conventional deep drawing, making it possible to obtain cases designed for various applications and fashioned to specific dimensions.
For example, miniaturization of cases for the aforementioned button-type microbatteries becomes crucial because of the need for smaller and lighter devices in the field of electrical equipment.
Specifically, demand for thinner clad material increases because of the need to design cases for smaller button-type microbatteries that have higher capacity and longer life. Conventionally at about 0.2~0.3 mm, device thickness is currently being reduced to about 0.1~0.15 mm.
It has been confirmed that conventional manufacturing methods make it difficult to perform deep drawing as desired even when the goal is limited to obtaining a thin clad material. Specifically, the inventors have performed experiments and confirmed that an attempt to obtain a clad material by a conventional manufacturing method results in a high Lankford value, or a considerable difference between r values (which characterize the plastic anisotropy between the rolling/bonding direction and a direction at a prescribed angle to the rolling bonding direction). In addition, deep drawing produces low roundness and yields an oval shape whose major axis is oriented in the rolling/bonding direction. In particular, cracks and ruptures form and a cup shape is difficult to obtain when a thin clad material is formed.
SUMMARY OF THE INVENTION
With the foregoing problems in mind, it is an object of the present invention to provide a readily drawable clad material having excellent tensile strength and other mechanical strength characteristics, and an manufacturing method therefore and, in particular, to a clad material suitable for use as an anode case or cathode case for button-type micro batteries and for other applications involving miniature electronic devices and requiring deep drawability and the use of comparatively thin sheets, and a manufacturing method therefor.
As a result of repeated experiments aimed at attaining the stated object, the inventors perfected the present invention upon discovering that the difference between r values (which characterize the plastic anisotropy between the rolling bonding direction of a clad material and a direction at a prescribed angle to the rolling/bonding direction) can be reduced by performing cold rolling at a rolling reduction of 30% or lower in addition to performing a conventional method for manufacturing a clad material, making it possible to substantially enhance the mechanical strength of the clad material and to mass-produce clad materials that have low reduction anisotropy.
Specifically, the present invention resides in a clad material characterized in that metal cladding is rolled/bonded to at least one principal surface of a metal substrate, and a value of less than 0.6 is set for the maximum difference between the r values (measured under 5% elongation) expressing the plastic anisotropy between the rolling/bonding direction, a direction at 45° to the rolling/bonding direction, and a direction at 90° to the rolling/bonding direction.
Another feature of the above-described clad material is that a value of 0.7 or greater is set for the r values that express the plastic anisotropy between the rolling/bonding direction, a direction at 45° to the rolling/bonding direction, and a direction at 90° to the rolling/bonding direction.
Yet another feature of the above-described clad material is that the combined thickness is set to 0.5 mm or less, and the thickness of the metal cladding is set to between 2 and 20% of the thickness of the metal substrate.
Still another feature of the above-described clad material is that the metal substrate is stainless steel and that the Goss {110}<100>-oriented accumulation in the plane in which bonding with the metal cladding is achieved is less than that observed when no metal cladding is rolled/bonded. An additional feature of the clad material is that the metal cladding is at least one material selected from copper and nickel.
The manufacturing method for obtaining the above-described clad material is characterized in that a clad material obtained by the rolling/bonding of metal cladding to at least one principal surface of a metal substrate is subjected to cold rolling at a rolling reduction of 30% or lower, and preferably 5 to 25%.
REFERENCES:
patent: 5576113 (1996-11-01), Hirofumi et al.
patent: 62-124229-A (1987-06-01), None
patent: 06-336619-A (1994-12-01), None
patent: 07-268462-A (1995-10-01), None
patent: 08-141754-A (1996-06-01), None
Ishio Masaaki
Takai Yoshiki
Dykema Gossett PLLC
Koehler Robert R.
Sumitomo Special Metals Co. Ltd.
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