US 12,485,494 B2
Spade drill bits
Paulo Sergio Dos Santos Pelentir, Caxias do Sol (BR); and Ricardo Casagranda Dendena, Garibaldi (BR)
Assigned to BLACK & DECKER INC., New Britain, CT (US)
Filed by BLACK & DECKER INC., New Britain, CT (US)
Filed on Mar. 17, 2022, as Appl. No. 17/697,042.
Claims priority of provisional application 63/165,379, filed on Mar. 24, 2021.
Prior Publication US 2022/0305570 A1, Sep. 29, 2022
Int. Cl. B23B 51/00 (2006.01); B27G 15/00 (2006.01)
CPC B23B 51/0095 (2022.01) [B27G 15/00 (2013.01); B23B 2260/104 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A spade drill bit comprising:
a shank extending along an axis from a rear end to a front end, the rear end configured to be coupled to a tool holder of a power tool;
a blade including a paddle extending along the axis with a front portion and rear portion coupled to the front end of the shank;
a tip coupled to the front portion of the paddle and extending along the axis; and
first and second primary cutting edges disposed on a front edge of the front portion of the paddle and extending radially outward from the tip,
wherein the paddle includes a first face with a first concave surface and a first convex surface on opposite sides of the axis, and a second face opposite the first face with a second concave surface and a second convex surface on opposite sides of the axis, the first concave surface opposite the first convex surface and the second concave surface opposite the second convex surface,
wherein the first concave surface has a first portion closer to the first primary cutting edge with a first radius of curvature and a second portion closer to the rear portion with a second radius of curvature that is greater than the first radius of curvature,
wherein the rear portion of the paddle is composed of a first steel alloy, and
wherein the front portion of the paddle is composed of a second steel alloy that has a greater hardness than the first steel alloy.