DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a serrated and pinned drill tip and drill shank interface of the disclosure;
FIG. 2 is another perspective view of a serrated and pinned drill tip and drill shank interface of the disclosure;
FIG. 3 is a profile view of a drill tip of the disclosure;
FIG. 4 is an end view of the drill tip of FIG. 3, in the direction of the arrows 4-4 in FIG. 3;
FIG. 5 is an end view of the drill tip of FIG. 3, in the direction of the arrows 5-5 in FIG. 3;
FIG. 6 is a profile view of the drill tip of FIG. 3, in the direction of the arrows 6-6 in FIG. 3;
FIG. 7 is a profile view of a machine tool tip of the disclosure;
FIG. 8 is an end view of the machine tool tip of FIG. 7, in the direction of the arrows 8-8 in FIG. 7;
FIG. 9 is a profile view of an alternate embodiment of a machine tool tip of the disclosure, and
FIGS. 10A-10C are end, profile and perspective views, respectively, of an alternate embodiment of the machine tool tip of the disclosure.
DETAILED DESCRIPTION OF PREFERRED AND ALTERNATE EMBODIMENTS
FIGS. 1 and 2 illustrate an exchangeable drill tip 10 in combination with a shank 50, such as a drill shank or other shank of a machine tool. Although illustrated as a drill tip, the principles and concepts of the invention are equally applicable to all types of shank-mounted machine tools and bits, as further described. The drill tip 10 has a body 12 which in this particular form has a generally cylindrical configuration with generally opposed arcuate sides 14 and generally helical chip flutes (“flutes”) 16 disposed radially and helically between the helical arcuate sides 14. The radially opposed and helical arcuate sides 14 and flutes 16 define a bowtie axial profile to the drill tip 10 and shank 50, as shown for example in FIGS. 4 and 5.
The drill tip 10 has a boring surface 18 which extends from an apex point 20 to upper edges 24 of the arcuate sides 14 and upper edges 26 of the flutes 16. The boring surface 18 can have multiple surfaces 181, 182, the angles of which may vary, as measured relative to a longitudinal axis of the drill tip 10. In one embodiment, an interface of the multiple surfaces 181, 182 forms a ridge line 183 on the boring surface 18.
The arcuate sides 14 and flutes 16 intersect at edge 30 which extends from the boring surface 18 to a bottom surface 36 of the drill tip 10. The edge 30 can be configured to function as a milling cutting edge (“leading edge 30”) in several respects with the drill tip 10 rotated about its longitudinal axis in the direction indicated in FIG. 4. The trailing edge 32 is at the opposite side of flute 16 at the intersection with arcuate side 14. The leading edge 30 may be formed with a chamfered cutting edge 34 which improves the milling function of the drill bit 10. The chamfered edge 32 may be formed at one or both of the leading edges 30.
As shown in FIGS. 3, 5, 7 and 8, a channel 40 is formed in the bottom 34 of the drill tip 10 and is oriented to extend transversely across the body 12 perpendicular to the longitudinal axis of the drill tip 10. In one form the channel 40 extends from the surface of one flute 16 across the bottom 36 to the surface of the opposing flute 16. However, different orientations of the channel are possible. The depth of the channel 40 along the longitudinal axis may be varied according to the total axial length of the drill tip 10.
With further reference to FIGS. 2 and 5, the bottom 36 of the drill tip 10 is formed with a plurality of serrations 42, such as a series or set of teeth or notches and/or grooves, which as shown are arranged in parallel and extend across the bottom 36 of the drill tip 10. In this particular form, the serrations 42 extend generally from one arcuate surface 14 to the opposing arcuate surface 14, and intersect the channel 40. In other words, the serrations 42 are not parallel to the channel 40 and vice versa. In the embodiment shown, the serrations 42 and channel 40 are at a relative angle in an approximate but not limited range of 20 to 60 degrees, and in fact can be arranged at any relative angle so long as they are not exactly parallel or aligned, i.e. at 0 degrees.
The serrations 42, including ridges 43 and valleys 44 are configured to fit with corresponding parallel serrations 45 (including ridges 46 and valleys 47) formed on an end 49, such as a distal end of shank 50. The engagement of serrations 42 and 45 prevents any shifting or lateral movement of the drill tip 10 relative to the shank 50 in any direction other than the aligned direction of serrations 42, 45. Helical flutes 56 are formed in the shank 50 to helically align with flutes 16 in drill tip 10 when the drill tip 10 is positioned on the drill shank 50 with the serrations 42 and 45 engaged. Similarly, arcuate sides 54 are formed on the drill shank 50, intermediate flutes 56, to helically align with the arcuate sides 14 of the drill tip 10 when engaged with the drill shank 50.
A dowel pin 60 protrudes from end 49 of shank 50, through serrations 45 and aligned with longitudinal axis of the shank 50. The extent of the dowel pin 60 past the serrations 45 in end 49 of shank 50 is approximately equal to or less than a depth of channel 40, so that the dowel pin 60 extends into channel 40 when the serrations 42 and 45 are engaged with the drill tip 10 in position upon shank end 49 and axially aligned with shank 50. The presence of the dowel pin 60 within channel 40 prevents any shifting or lateral movement of the drill tip 10 relative to the shank 50 along the engaged serrations 42, 45. By the engagement combinations of the serrations 42 and 45, and dowel pin 60 within channel 40, lateral movement of the drill tip 10 relative to the shank 50 is prevented in any direction.
The drill tip 10 is axially secured to the shank 50 by fasteners 66 which are installed through through-bores 62 in the drill tip 10 which are aligned with taps 64 in the end 49 of shank 50 with the drill tip 10 in the installed position upon the shank 50.
FIG. 9 illustrates an alternate embodiment of a drill tip 10 with the same general configuration as those previously described, but further having a back chamfer 70 around substantially the circumference of the body 12, and extending from the arcuate sides 14 to the bottom surface 36. The back chamfer 70 is highly effective in cleaning and finishing borings as the edge 72 between the chamfer 70 and arcuate sides 14 provides an additional cutting and polishing contact. The back chamfer 70 can be incorporated into any of the drill tip designs of the disclosure.
FIGS. 10A-10C illustrate a further variation of a drill tip 10 similar to those previously described but with the addition of double margin flutes 76 formed in the arcuate sides 14 intermediate the helical flutes 16. The double margin flutes 76 provide, in combination with the leading edges 30 of flutes 16, four point cutting/boring contact by the action of the additional cutting lines 78 formed at the intersection with the arcuate sides 14 and are highly effective in burnishing and polishing interior surfaces of borings, particular with aluminum or cast iron. The double margin flutes 76 are preferably formed on radially opposite sides of the drill tip 10 and follow a helical or angularly swept path as shown.
FIGS. 11-13 illustrate a further embodiment of the replaceable drill tip of the disclosure wherein a central longitudinal axis of the through-bores 62 in the drill tip 10 are not aligned with a central longitudinal axis of the corresponding taps 64 in the drill shank 50. Stated alternatively, the longitudinal axes of the through-bores 62 are located at a greater radius from the central longitudinal axis of the drill tip 10 than the longitudinal axes of the tips 64, with the longitudinal axes of the drill tip 10 and shank 50 aligned. As illustrated, chamfered ends 661 of fasteners 66 distort the fasteners 66 from alignment with the through-bores 62 to alignment with the corresponding taps 64, creating a laterally binding engagement of the drill tip 10 with the shank 50, in combination with the respective engaged serrations 42 and 45 and creating lateral pressure against the segment of the dowel pin 60 within channel 40 in the drill tip 10. The mis-alignment of the through-bores 62 with the taps 64 prevents the fasteners 66 from loosening from vibration and further maintains perfect axial alignment of the drill tip 10 with the shank 50.
Patent Application
20070274795
