ENGINEERS CUTTING TOOLS

Abstract: An engineers cutting tool comprises a shank (20) having helical flutes (22, 23) and helical face pieces (32, 33) brazed thereto. The larger flute (23) functions as a roughing flute in drilling and extends radially from a periphery of the tool to beyond the axis. The smaller flute (22) is a finishing flute and set behind the roughing flute (23).

Description: TITLE : Engineers Cutting Tools TECHNICAl, FIELD - The invention relates to engineers cutting tools for metal working, which are particularly suitable for use in machine tools in which the tool spindle rotates . • THE INVENTION A tool according to the invention comprises a shank having two or more helical flutes, a helical flute face piece secured to each flute, one of the face pieces having a cutting edge extending radially from a periphery of the tool to beyond the longitudinal axis of the tool. Such a tool both produces and finishes a hole by cutting, and can also be used for boring spot facing, plunging or ramping in, drilling and reaming, milling, key-seating, and die-sinking, for example. The flute face pieces can automatically be re-ground to shape owing to the flutes b * eing helical and at least one face piece being -completely radial. The helical form of the flutes effectively permanently builds in a radial rake from the outside diameter through to'.the centre at least. The tool shank is preferably of alloy steel. The flute pieces are preferably of tungsten carbide, ceramic or a specialist cast alloy such as those known by the Trade • Marks STELLITE and TANTUNG, or high speed steel and secured in position on the flute faces by welding or bra2ing. The face pieces may be castellated at least at the tip to help break up the metal chips produced in use, and optionally also to provide coolant channels. - DRAWINGS:•- Figure 1 is a side view of a tool according to the invention ' ; Figures 2 to 5 are end viewsof the tool of Figure 1 - and other similar tools; Figures 6 to 9 are side viewsof the tips of tools « similar to that of Figure 1; Figure 10 illustrates typical two-flute tip sets for use on tools according to the invention; Figure 11 illustrates typical tool periphery geometry; and ' •• - Figure 12 shows schematically on an enlarged scale the tip of the tool of Figure 1 advancing into a work piece. ' BEST MODE- With particular reference to Figure 1, the tool comprises a shank 20 of alloy steel having flutes 22, 23 (Figure 2). The flutes 22,23 respectively have helical tungsten carbide face pieces 32,33 brazed thereto. The (larger) flute 23 functions as a roughing flute in drilling and extends radially from a periphery of the tool at the top of Figures 1 and 2 to beyond the axis of the tool Cbelow the centre in Figures 1 and 2) . The (smaller) flute 22 is a finishing flute and set behind the xoughing flute 23 in the axial direction of the tool advance in drilling as best shown in Figure 12. In the upper part of Figure 12, the roughing face piece 33 is shown advancing to the right into a workpiece; in the lower part its position 180° of rotation earlier is shown by .a broken line to emphasize the relative (leftward) position of the face piece 32. The tips of th-e tools in Figures 1 to 9 are varied according to the use for which they are intended, that is whether primarily for dilling, traversing, or producing a flat bottomed surface. The corner edges of the face pieces axe chamfered as at 39 to produce a size-finished hole due to the relative positions of the ground angles. The tips in Figures 3 and 5 have a roughing face piece 32 and two finishing face pieces 33,34 equally spaced radially about the tool axis, and set one behind .- another in the axial direction of tool advance. The • extra finishing flute cuts a smoother internal finish. The tips in Figures 4 and 5 have castellations on the face of the roughing face piece 32.

Claims: CLAIM 1. An engineers cutting tool comprising a shank 20 having helical flutes 22,23 and a helical flute face piece 32,33 secured to each flute ' characterised by one of the flute face pieces 32 having a cutting edge extending radially from a periphery of the tool to be beyond the longitudinal axis of the tool.

Inventors: WALE D
Applicants: MARWIN CUTTING TOOLS LTD, WALE D
Application year: 1981
Main classification: B23B51
IPC codes: B23B51, B23C5