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US 3,996,832 AGranted
Punch for producing holes in foamed thermoplastic containers
AssigneeStandard Oil Company (Indiana)
InventorsJohn C. Schubert, Charles B. Case
Life of this patent
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Abstract
A hole punch having a curved cutting edge of generally the same contour as the surface being punched produces clean holes in wall of foamed plastic containers.
Claims1
A hole punch for use in the production of foamed thermoplastic containers comprising a generally concave blade edge with a reverse curvature near each edge of the blade, said blade edge having generally the same contour as the surface into which it is punched.
Dependencies are inferred from the claim text.