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;
annealing said junction to avoid formation of a flaw or incipient fracture along the junction;
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, and where the flat strip of metallic material is heated prior to passing said strip through the slit opening, and, further, where the die is heated to a temperature substantially from 500 to 700 degrees Fahrenheit; and
where the metallic material is selected from the group comprising chromium, nickel, carbon, and iron.
2. The method of claim 1 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.
3. The method of claim 1 where the strip passes through the die at a rate substantially from 100 to 200 linear feet per minute.
4. 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;
annealing said junction to avoid formation of a flaw or incipient fracture along the junction;
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, and where the flat strip of metallic material is heated and the die is simultaneously heated as the flat strip of metallic passes through the slit opening; and
where the die is heated to a temperature substantially from 500 to 700 degrees Fahrenheit.
5. The method of claim 4 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.
6. The method of claim 4 where the strip is steel and passes through the die at a rate substantially from 100 to 200 linear feet per minute.
7. The method of claim 4 where the metallic material is selected from the group comprising chromium, nickel, carbon, and iron.