Unique pre-form design for two-step forming of stainless steel fuel cell bipolar plates
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
H01M-008/00
H01M-008/02
H01M-008/10
출원번호
US-0724505
(2012-12-21)
등록번호
US-8778567
(2014-07-15)
발명자
/ 주소
Xu, Siguang
Spencer, Steven J.
Bradley, John R.
Fly, Gerald W.
Morales, Arianna T.
출원인 / 주소
GM Global Technology Operations LLC
대리인 / 주소
Dinsmore & Shohl LLP
인용정보
피인용 횟수 :
1인용 특허 :
2
초록▼
A bipolar plate used in a fuel cell and a method of making a bipolar plate. The sheet is made from a ferritic or austenitic stainless steel, and defines an undulated surface pattern such that the patterned sheet may be formed into the bipolar plate. In one configuration, a stamping or related metal
A bipolar plate used in a fuel cell and a method of making a bipolar plate. The sheet is made from a ferritic or austenitic stainless steel, and defines an undulated surface pattern such that the patterned sheet may be formed into the bipolar plate. In one configuration, a stamping or related metal forming tool operation will further deform the patterned sheet into the bipolar plate shape such that the wall thickness is substantially uniform throughout the surface. In this way, there is a substantial reduction in stretching/thinning/necking at an intersection between bends and side walls that define the undulations of the pattern. In one form, the pattern defines a repeating serpentine shape. In a particular embodiment, the bends may include surface modifications to reduce the effects of sheet-to-tool misalignment.
대표청구항▼
1. A method of preparing a stainless steel bipolar plate for a fuel cell, said method comprising: configuring a bipolar plate forming apparatus to progressively form said bipolar plate, said progressively forming comprising: using a first shaping step to pre-form a sheet of stainless steel such that
1. A method of preparing a stainless steel bipolar plate for a fuel cell, said method comprising: configuring a bipolar plate forming apparatus to progressively form said bipolar plate, said progressively forming comprising: using a first shaping step to pre-form a sheet of stainless steel such that a portion of the material making up said sheet is selectively moved, said pre-formed sheet defining a nominal thickness and a plurality of undulations representative of bipolar plate reactant channel flowpaths therein; andusing a second shaping step to change the shape of said pre-formed sheet such that a maximum deviation from said nominal thickness as a result of said first and second shaping steps is substantially reduced relative to formation of a bipolar plate from a single-step forming process; andproviding said sheet to said bipolar plate forming apparatus such that upon operation of said bipolar plate forming apparatus on said sheet, the shape of said sheet is substantially converted into that of said bipolar plate. 2. The method of claim 1, wherein said stainless steel used in said bipolar plate comprises an austenitic stainless steel. 3. The method of claim 1, wherein said stainless steel used in said bipolar plate comprises a ferritic stainless steel. 4. The method of claim 1, wherein said selectively moved material corresponds to discrete portions of said sheet that substantially coincide with locations therein where at least one of a land and said channel are subsequently formed. 5. The method of claim 4, wherein said discrete portions will, upon formation by said first shaping step, define a substantially V-shape. 6. The method of claim 5, wherein said substantially V-shape defines a flattened region at the apex thereof. 7. The method of claim 4, wherein an angle defined at the apex of said substantially V-shape is between about 114 degrees and 120 degrees. 8. The method of claim 3, wherein a depth of draw of said changing the shape is at least about 350 microns. 9. The method of claim 8, wherein said pre-formed sheet defines a pre-form draw depth sufficient to substantially match a final form depth. 10. The method of claim 1, wherein said maximum deviation from said nominal thickness is less than about twenty percent. 11. The method of claim 1, wherein said reduced maximum deviation corresponds to an attendant decrease in thinning and necking in regions of said sheet that correspond to said channel. 12. A method of preparing a bipolar plate for a fuel cell, said method comprising: using a first shaping step to form a substantially planar sheet of ferritic stainless steel into a substantially non-planar serpentine pattern shape, wherein said substantially planar sheet defines a nominal thickness substantially throughout the portion of its surface that defines said bipolar plate; andusing a second shaping step to form said serpentine pattern into a bipolar plate such that upon creation thereof, it defines a substantially constant wall thickness with a substantial reduction in deviation from said nominal thickness relative to formation of a bipolar plate from a single-step forming process. 13. The method of claim 12, wherein each of said first and second shaping steps comprise stamping. 14. The method of claim 13, further comprising reducing the likelihood of misalignment between said serpentine pattern and a tool used to perform said stamping by providing a flattened region around the apex of each of a plurality of substantially V-shaped peaks that are formed in said serpentine pattern. 15. The method of claim 14, wherein said reducing the likelihood of misalignment comprises self-adjusting said serpentine pattern prior to said second shaping step by placement of a flattened bend region therein into a bipolar plate forming apparatus with a lateral misalignment of up to about 400 microns. 16. The method of claim 12, wherein said reduction in deviation from said nominal thickness relative to formation of a bipolar plate from a single-step forming process is at least about 50%. 17. The method of claim 12, wherein a depth of draw associated with at least one of said serpentine pattern and said bipolar plate is between about 300 microns and about 400 microns. 18. A method of preparing a fuel cell, said method comprising: arranging a membrane electrode assembly to comprise an anode, a cathode and a membrane disposed between said anode and cathode such that a respective anode reactant and cathode reactant may be placed in fluid communication therewith; andplacing a stainless steel bipolar plate that defines a plurality of flow channels therein in adjacent each of said anode and said cathode such that upon operation of said fuel cell, reactants introduced from a fuel source and an oxygen source respectively can be delivered to said anode and said cathode through said flow channels, said bipolar plates formed by: shaping a pre-formed sheet of stainless steel such that it defines a nominal thickness and a plurality of reactant channel flowpaths therein; andchanging the shape of said pre-formed sheet such that a maximum deviation from said nominal thickness is substantially reduced relative to formation of a bipolar plate from a single-step forming process. 19. The method of claim 18, wherein said shaping said pre-formed sheet and said changing the shape of said pre-formed sheet is performed by a bipolar plate forming apparatus. 20. The method of claim 19, wherein said substantial reduction in said maximum deviation is at least about 50%. 21. The method of claim 19, further comprising reducing the likelihood of misalignment of said pre-formed sheet and said bipolar plate forming apparatus by providing a flattened region about an apex formed in each of a plurality of substantially V-shaped peaks that define a serpentine pattern in said pre-formed sheet. 22. The method of claim 18, wherein said stainless steel used in said bipolar plate comprises a ferritic stainless steel.
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이 특허에 인용된 특허 (2)
Erikstrup, Niels, Interconnect for a fuel cell, a method for manufacturing an interconnect for a fuel cell.
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