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3771221
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Patent number 3,771,221
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Issue date Nov 13, 1973
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B21 - MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL PUNCHING...
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3390563
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Patent number 3,390,563
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Issue date Jul 2, 1968
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B21 - MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL PUNCHING...