US 3885925 A
Apparatus for grinding drill faces. Two grinding wheels having different grained surfaces are adapted to operate on the drill either together or with only one wheel so operable.
Claims available in
Description (OCR text may contain errors)
D United States Patent 11 1 1111 3,885,925 Tatar May 27, 1975 METHOD FOR THE SHARPENING OF  References Cited FOUR FACES DRILLS AND SHARPENING UNITED S A PATENTS MACHINE FOR CARRYING OUT THIS 2 309 016 1 1943 Ryan 51/209 R METHOD 2,594,137 4/1952 Doermann 51/207 2,600,815 6/1952 Turner 51/209 R  Inventor a a i: R gf of 2,749,684 6/1956 Schuhmann 1 51/209 R a 2,932,135 4/1960 Tatar 51/124 R France 3,067,551 12 1962 Maginnis 51 207 22 Filed: Oct. 17 1973 3,626,436 12/1971 Lhomme 51/124 R ] Appl' 407131 Primary Examiner-Al Lawrence Smith 7 Assistant ExaminerK. J. Ramsey 30 Foreign Application p i i Data Attorney, Agent, or FirmSilverman & Cass Ltd.
Oct. 23, 1972 Switzerland 15461/72  ABSTRACT  US. Cl 51/122; 51/124 R; 51/288; Apparatus for grinding drill faces Two grinding 51/327 wheels having different grained surfaces are adapted  Int. Cl B24) 5/36 to perate on the drill either together or with only one 0f Search R, 124 R, 122, 288, wheel so operable 5 Claims, 5 Drawing Figures METHOD FOR THE SHARPENING OF FOUR FACES DRILLS AND SHARPENING MACHINE FOR CARRYING OUT THIS METHOD BACKGROUND OF THE INVENTION The object of the present invention is to provide a method for sharpening four faced drills by means of two grinding wheels of two different grains, and to provide a sharpening machine for carrying out of said method.
SUMMARY OF THE INVENTION The method according to the invention is characterized by the fact that, for each pair of faces of a four faced drill to be sharpened, the drill having cutting and clearance faces, one may urge the drill to pass a first time opposite two grinding wheels, one of which, having the thinnest grain, is then situated back from the alignment of the working plane of the other grinding wheel, such that only the last named wheel which has the roughest grain, contacts the drill and shapes the clearance face thereof; thereafter, the drill may be urged to'pass anew opposite the two grinding wheels, during a reverse movement, after a relative movement between the drill and the grinding wheels has been effected, such that the grinding wheel then contacts the cutting face of the drill after the two grinding wheels have been brought into a same plane. During this reverse displacement of the drill, the grinding wheel having the roughest grain shapes first the cutting face of the drill and the grinding wheel having the thinnest grain finishes the operation on this same face.
The machine constructed in accord the invention is characterized by the fact that it comprises two grinding wheels having different grains mounted in such a way as to be able to effect a relative movement such that they can occupy a position in which only the grinding wheel having the roughest grain is able to work, and a position in which both are able to work. Means are provided to permit the drill to move opposite to the said grinding wheels and means synchronizing the movements of the grinding wheels and of the drill are provided so that, in one direction of the displacements of the drill opposite the grinding wheels, only the grinding wheel having the roughest grain makes contact with the ,drill while, in the reverse direction, the two grinding wheels operate successively, the one having the roughest grain first attacking the drill and the one having the thinnest grain then finishing the work.
The drawing shows, by way of example, one embodiment of apparatus constructed in accordance with the invention, and one modification thereof.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial axial sectional view of a sharpening machine for four faced drills.
FIGS. 2 and 3 are sectional views of a detail, in two different working positions, showing the sharpening processes, and
FIGS. 4 and 5 are sectional views of a detail of a modification, corresponding respectively to FIGS. 2 and 3 of the embodiment of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT The present machine, the only elements of which are shown in the drawing are those necessary to the understanding of the invention, comprises a quill 1 adapted to rotate in a headstock 2. Quill l carries at one of its ends, a pulley 3 driven by a belt 4 which is itself driven by a motor not shown. The quill l carries, at its opposite end, the hub 5 of a bell shaped grinding wheel 6.
The hub 5 carries, freely mounted thereon, a plate 7 which itself carries a bell shaped grinding wheel 8, the grain of which is thinner than that of the grinding wheel 6. Three coil springs 9, only one of which is visible in the drawing, urge the plate 7 to maintain the same in bearing engagement against a ring 10 screwed on the hub 5, in a position in which the working plane 11 of the grinding wheel 8 is situated back from the alignment therewith of the working plane 12 of the grinding wheel 6. A driving finger 13 carried by the hub 5 and which is engaged in a hole of the plate 7 renders the plate angularly rigid with the hub 5, in such a way that the two grinding wheels are rotatably driven by the quill 1.
The quill is traversed by two sliding rods 14 connected at their rear ends by a yoke 15 and which are engaged, at their front ends, in a ring 16 which is in contact, by the intermediary of roller bearing 17, with the plate 7. A pusher 18 is controlled by an electromagnet, the coil 19 of which (diagrammatically shown), acts on the yoke 15 for moving it towards the right side of FIG. 1. Yoke 15 operates rods 14 to move ring 16 and bearings 17 against plate 7 to force plate 7 toward the right as viewed in FIG. 1, against the action of the springs 9, bringing the grinding wheel 8 into a position in which its working plane 11 coincides with the working plane 12 of the grinding wheel 6.
The machine disclosed and represented operates as follows:
A four faced drill, such as drill 20 of FIG. 2 and 3, is moved opposite the two grinding wheels in the direction of the arrow 21 of FIG. 2 while the grinding wheels occupy their relative position in which the grinding wheel 8 is eclipsed and only grinding wheel 6 is able to work. The axis of the drill then occupies the position indicated by I in FIGS. 2 and 3. During this movement of the drill, the grinding wheel 6, the grain of which is rougher than that of wheel 8 shapes one of the clearance faces of the drill, which face is designated by 22.
The drill is then rocked or pivoted with respect to the working plane of the grinding wheel so that the axis of the drill occupies the position indicated at II in FIGS. 2 and 3, while the grinding wheel 8 is advanced so that its working plane coincides with that of the grinding wheel 6. The synchronisation of the movements is obtained, for instance, by means of a micro-switch feeding the coil 19 of the electro-magnet controlling the pusher 18, which microswitch is itself operated for instance by the carriage, not represented, which carries the drill 20 and which produces its movements opposite the grinding wheel.
During the reverse movement of the drill, in the direction of the arrow 23 of FIG. 3, one of the cutting faces 24 of the drill is first shaped by the grinding wheel 6, the grain of which is rougher than that of wheel 8, then polished by the grinding wheel 8 the grain of which is thinner than that of wheel 6.
it is to be noted that the relative movement between the grinding wheel and the drill which is effected after the first displacement of the drill, so as to present its cutting face after its clearance face into contact with the grinding wheels. can be effected instead of being obtained by a rocking movement of the drill by rocking the two grinding wheels. This rocking is possible if the headstock 2 of the quill l is articulated on the frame of the machine.
ifhe modification described above is represented in FIGS. 4 and 5 in which. as it can be seen, the axis of the tirill maintains its direction unchanged while, on the contrary. the grinding wheels 6 and 8 have their worktng plane situated in a position l in FIG 4 and in a position ll in FIG. 5. the passage from one to the other peing obtained by a rocking movement through the grinding wheels. of an angle equivalent to the angle be tween the two positions l and II of the drill 20 in FIGS. l and 2.
What I claim is:
l. Method for sharpening a four faced drill having pairs of cutting and clearance faces. the sharpening being effected with two grinding wheels respectively having grinding surfaces of different grain roughnesses, 581d method comprising the steps of: positioning the grinding wheels relative to each other such that only the wheel with the rougher grain is operable on a drill tace, positioning the drill relative to the wheels to present a clearance face thereof for sharpening, urging the drill to pass opposite the two grinding wheels in one direction such that the clearance face thereof contacts only the rougher grain wheel, next positioning the wheels relative to each other such that both wheels are operable on a drill face, re-positioning the drill relative to the wheels to present a cutting face thereof for sharpening, and moving the drill in a direction opposite to said one direction such that the cutting face of the drill contacts first the rougher grain wheel and immediately thereafter the thinner grain wheel to finish the sharpening of the cutting face of the drill.
2. Method as claimed in claim 1 in which said repositioning of the drill after sharpening of the clearance face is achieved by rocking movement of the drill.
3. Method as claimed in claim 1 in which said repositioning of the drill after sharpening of the clearance face is achieved by rocking movement of the two grinding wheels.
4. Machine for sharpening a four faced drill comprising, two grinding wheels respectively having grinding surfaces of different grain roughnesses. said wheels being cooperatively mounted for movement one relative the other to alternatively occupy a first position in which only the grinding wheel having the rougher grain surface is operable on the drill and a second position in which both wheels are so operable, means for moving the drill opposite said wheels, and means for synchronizing the movement of the grinding wheels and the drill, whereby in one direction of displacement of the drill opposite the grinding wheels only the grinding wheel having the rougher grain surface makes contact with the drill and in the reverse direction of displacement of the drill the two wheels operate successively on the drill such that the wheel having the rougher grain surface first makes contact with the drill and immediately thereafter the wheel having the thinner grain surface makes contact with the drill to finish the sharpening of the drill.
5. Machine is claimed in claim 4 in which said grinding wheels are of generally bell-shaped configuration and are mounted concentrically one with the other, the wheel with the thinner grain surface being positioned surrounding the wheel with the rougher grain surface and being moveable axially relative to the wheel with the rougher grain surface between a first eclipsed position in which the working plane of the thinner grain grinding surface is positioned behind the working plane of the wheel with the rougher grain grinding surface and a second position in which the grinding surfaces of the two wheels are in the same working plane.