Tape measure device and method of manufacturing blade therefor
View Patent ↗A tape measure device has an elongated blade with a central concave-convex segment with at least one planar segment adjoining edgewise the central concave-convex segment to form a junction that extends substantially along the entire length of the elongated blade. During formation of the blade the junction is annealed to avoid formation of a flaw or incipient fracture along the junction.
1. A method of manufacturing an elongated blade for a tape measure device from a substantially flat strip of metallic material, said elongated blade having a predetermined cross-sectional curved configuration comprising a concave-convex segment and at least one planar segment adjoining edgewise the concave-convex segment to form a junction that extends substantially along the entire length of the elongated blade, said method comprising
passing a substantially flat metallic strip through a slit opening in a die, said slit opening having a configuration substantially conforming to said predetermined cross-sectional curved configuration, and
annealing said junction to avoid formation of a flaw or incipient fracture along the junction.
2. The method of claim 1 where the annealing comprises passing said flat metallic strip lengthwise through the slit opening and heating to a temperature substantially above ambient temperature but below melting point of the metallic material.
3. The method of claim 2 where the predetermined cross-sectional curvature of the extended blade portion has predetermined dimensions and the slit opening has dimensions that are slightly less than said predetermined dimensions of the cross-sectional curvature of the extended blade portion.
4. The method of claim 3 where the strip is steel and passes through the die at a rate substantially from 100 to 200 linear feet per minute.