GB140305A - Improvements in broaches - Google Patents

Abstract

140,305. Oakley, J. July 29, 1919. Tools.-A broach for cutting or widening slots comprises a. shank 1 of same contour as original apertures in stock with peripheral chip-clearing spaces 8 axially of the shank and cutting-teeth 5 secured by screws to the part of the shank between the spaces. When widening a groove, a pilot tooth 9 is used to guide the broach, but when cutting a primary groove, this pilot is omitted and chip-cleavers 18 are employed at the front of each tooth with passages 17 leading to the main chip-clearing passages 8. The cutting-edges may be flat or convex, and two sizes of cutting teeth may be employed, the narrower 20, Fig. 9, being secured in transverse passages 21 in the tool leading to a chip-clearing groove 23 at the side opposite the teeth. In a further modification, Fig. 11, the teeth are formed in three sets with three main clearing-grooves, and are shaped like arrowheads with transverse lugs to enter slots in the tool; the tool has also a V-shaped groove at the front of each tooth to lead the chips to the main groove. In a further modification, the cutting-teeth 31 are arranged in spiral formation, Fig. 14, and, in another modification, Figs. 16 and 18, the teeth are formed in opposite sides of a bar 41 secured in a transverse slot in the holder, and the alternate teeth are of different width.