US2810992A - Automatic drill pointer - Google Patents

Description

Oct. 29, 1957 J. A. ElNHlPLE 2,810,992

AUTOMATIC DRILL POINTER 4 Sheets-Sheet 1 Filed Jan. 27, 1956 v INVENTOR;

John -A. Einhiple Oct. 29, 1957 J. A. ElNHlPLE 2,810,992

AUTOMATIC DRILL POINTER Filed Jan. 27, 1956 4 Sheets-Sheet 2 John A. Einhiple BY Oct. 29, 1957 J. A. EINHIPLE'. 2,810,992

AUTOMATIC DRILL POINTER 4 Sheets-Sheet 3 Filed Jan. 27, 1956 Fig. 6

INVENTOR.

John A. Einhiple g ozw Oct. 29, 1957 J. A. EINHIPLE 2,810,992

AUTOMATIC DRILL POINTER Filed Jan. 27, 1956 4 Sheets-Sheet 4 Johh. A. Einhiple United States Patent .iohn A. Einhiple, Kenmore, N.

Gypsum Company, Buflalo, Delaware Y., assignor to National N. Y., a corporation of Application January 27, 1956, Serial No. 561,752

8 Claims. (Cl. 51-92) This invention relates to an apparatus for sharpening or pointing drills, or more specifically to a novel automatic drill pointer. Although not limited to such use, the invention is directed to an apparatus for rapidly resharpening drills for use in drilling perforated acoustical tiles, the manufacture of which tiles requires a very large number of drills maintained sharp and of identical or equal overall length. The ambodiment of the present inven tion set forth herein is particularly adapted for resharpening the drill described and shown in my earlier United States Patent 2,675,841.

Due to the accuracy required in resharpening drills for acoustical tile both in providing a properly formed drilling end, without any burning of metal, and in providing a large plurality of drills all of equal length, it will be apparent that the heretofore largely manual operation has been an expensive md time consuming operation.

It is, therefore, an object of the present invention to rovide a novel apparatus which requires only a relatively rapid insertion and locking in of each individual drill prior to the automatic resharpening, individually, of a large plurality of drills, free of burning, all to an identical, selected length.

These and other objects and advantages will appear more fully when considered in connection with the fol lowing detailed description of a preferred embodiment of the invention and the accompanying drawings in which:

Fig. 1 is a side View of an automatic drill pointer built in accordance with and embodying the present invention.

Fig. 2 is a front view of the drill holding and advancing portion and the reciprocal drive of the machine of Fig. 1, parts being broken away.

Fig. 3 is a top view of the drill holding portion of Fig. 2.

Fig. 4 is a sectional view through the guide pins taken along line 4-4 of Fig. 3.

Fig. 5 is a sectional view of the drill holding and advancing portion of Fig 2 taken along line 5-5 of Fig. 3, certain portions being shown in full.

Fig. 6 is an exploded view of the machine chuck of Fig. 5, portions thereof also shown in Fig. 2.

Fig. 7 is a sectional view of the machine stop-start switch.

In the drawings, the reference numeral 20 complete automatic drill-pointer machine. Briefly, the machine 20 includes, first, a rotary grinding wheel and drive assembly A providing a continually rotating, profiled grinding means for resharpening drills. Machine 20- ineludes, second, a combination upper-frame and wheel dressing assembly B. Third, a drill receiving and holding assembly C is laterally slidably mounted on the front of frame assembly B. Fourth, a reciprocal drive assembly D causes the lateral reciprocation of assembly C. Assembly C holds and slowly advances a drill to be resharpened by passingcontact with the profiled grinding means of assembly A, the passing contact being provided refers to the by the reciprocation of assembly C caused by the operation of assembly D.

Referring now to Fig. 1, there is, shown the automatic drill pointer machine 20, built in accordance with and embodying the present invention. A table 21 having a fore and aft extending,raised and dovetailed top 22, provides a support for an adjustably movable framework 25, slidably mounted thereon. Framework 25 includes a dovetailed groove 26 in slidably mounted upon dovetailed top 22, for adjustable movement of framework 25 fore and aft. A threaded frame positioning bolt 30, having a handwheel 31 at the front end, is rotatably mounted, longitudinally fixed, in framework 25, and extends into and is threadedly engaged in threaded hole 32 in table 21. Thus, rotation of handwheel 31 and bolt causes framework 25 to slide fore or aft relative to table 21, such action being for repositioning the assemblies B and C of the machine relative to assembly A for the wheel and the subsequent grinding operation following redressing, to be discussed further below,

Mounted behind table 21 is a grinding-wheel motor 35 with a shaft 36 having a pulley 37. Belt 38, on pulley 37, is disposed and extends upward between the table and motor 35, and is mounted also on a pulley 40 which is on grinding shaft 41. Grinding shaft 41 is rotatably mounted in bearings 42 fixed on and above table top 22. Pulley 40 is fixed at the rear end of shaft 41 and a hollow, cylindrical, grinding wheel 45 is fixed at the forward end of shaft 41.

As will be seen in Pig. 1, grinding wheel 45 is rotatably disposed within the confines of framework 25, and a forward bearing 42 is shown disposed partially therewithin. Grinding wheel 45, bearings 42 and shaft 41 are stationary relative to table 21, excluding rotation, whereas framework 25 is slidable fore and aft, relative to table 21, and thus also relative to grinding wheel 45.

Briefly, framework 25 includes two grinding dressing units, namely an upper, and a lower, face dressing unit 51. Framework 25 further includes on the front side thereof a downwardly facing, frame-extension having a laterally extending dovetailed groove 56 in the bottom face thereof, for the laterally-slidable, hanging support therein of the reciprocating drill receiving and holding assembly C of machine 20, to be fully discussed further below.

Wheel- dressing units 50 and 51, each consist of a hand-crank 60 on a very steadily held, rotatable, threaded shaft 61 extending parallel to an adjacent surface of grinding wheel 45. A diamond-holding block 62 is slidably held against rotation in each unit 50 and 51 and is threadedly engaged with shaft 61. A diamond 63 projects outwardly from each block 62 in the direction of grinding wheel 45. In the present embodiment, the hollow cylindrical grinding wheel 45 includes two faces involved in the grinding operation, namely, an annular, front face 65 in a plane perpendicular to shaft 41 and an annular, outer, front corner outwardly and rearwardly from front face 65 at an angle in the order of 45, in accordance with the angle of upper angular dressing unit 59. By rotation of each of the two hand cranks 60, diamonds 63 in each of units 50 and 51, are caused to move adjacent and relative to grinding wheel faces 66 and 65 respectively.

Thus, it will be seen that when grinding wheel redressing is desired, a slight measured rotation of hand crank 31 will cause framework 25 to slide rearward in the order of thonsandths of an inch, whereat the framework is locked in position. Wheel dressing units 50 and 51 are wheel position, preparing a new grinding face, properly disposed Patented Oct. 29, 1957 the base complimentary to and redressing of the grinding angular, dressing unit 50.

face 66 extending radially.

relative to the'drill-receiving and holding assembly C which were moved rearward simultaneously with the framework 25.

D pose a ove, a o t e, i h s e indin -W e 'motor 35 is a reciprocal-drive motor 7 0. haying alfor'wardly extending, telesc opic shaft 71, inelndinga rear, hollow,

internally-slotted ,shaft"7 2 .and aforward, inner-fitting,

complementarily-keyed shaft 73, providing a positive rotary drive motion to an eccen'tric'wheel 75; Fig.2, fixed.

on the forwardend of 'shaft73; Shaft 73' is rotatablyj 10 supported'in a bearing 7Q rearward of eccentric wheel weirdly-extending lever-arm 82, pivotallyfconnected at itslower end to a reciprocating. cross-arm 8 3 which cross arm at its opposite .end, islinked to the reciprocating,

Carriage 85 is the general frame portion of the drill receiving and holding assembly C of machine 20, men

tioned above. Forassembling purposes discussed further ment 91 and lower segment 92, however, for clarity, car'- riag'e 85 may be considered and will be generally de-, scribed as a single element. an upper-face 86 having a laterally-extending, dovetailed, raised portion 87, second, a rear-face 88 and, third, for: wardly-extending, side- walls 89 and 90. Cross-arm 83 is linked to carriage 85 at. an upper part of. side-wall 90.

Rotation of eccentric wheel 75 will be seen to cyclically 3 pivot pivot-arm 77 causing .reciproeatingaarm 83 to reciprocate, slidably reciprocating carirage 85 and all its-assok ciated parts, discussed further herebelow.

Generally centered in the rearface 88 of carriage '85,

ing engagement between se ments 91 and 92, held to; gether by bolts 106, Fig. 4.

105 includes meansfor receiving a drill 110, the present. embodiment of machine 20 being adapted for. pointing or resharpening a twist drill as more fully disclosed-and shownin my U. S. Patent 2,675,841. Drill 110 is formed of. a cylindrical body having a generally plain shank end;

formation 113 with an inner inclinedrplane 1 14. 7 Since carriage 85, the axis of hole 100, andthus the axis of chuck 105, extends, in the present embodimenfiupwardly and outwardly at.an angle of 17 from thehorizontal, Fig. 5, and at an angle of 7? plane through the axis 0 grinding wheel 45, Fig. 3; Chuck 10 5, includes, the, fourteen partsshown in the exploded view 6, substantially all ofwhich can be shankrpofliori churk 95 inner. -end-portion of slotted Carriage includes, first, 30

' remaining axially stationary in view in Fig. 6( Chuck 50 112 and 114, resulting from horizontal reciprocation of 65 to alverticalfore and aft:

the entire axial length of chuck 105, although in the sectional view the axially outer extent is hidden by the axiallyextending legs 121 of the dual-armed cam-follower 122, slidably inserted within two diametrically-opposed, axial slots 123 in the larger-diameter body-portion 124 of sleeve 120.

The entire axial lengthjof shank-portion 101 of sleeve is disposed in, hole .100, and, thus, the inner end of 7 the larger-diameter body-portion 124 abuts an inner, fiat urfac fip q rw l'8 Su a 1 is in a Plane p pendicular to, the chuck .axisiand extends, radially outward beyond the periphery of the body-portion 124.. A compression spring13ll is disposed about the periphery of body-portion 124, axially inwardly abutting the radially outer portion of surface. 128;.'

Spring 130, under compression, abuts at the axially outer end thereof, the axially inner edges of radially-out wardly-extending follower-arms 181 ofcarn-follower-122, constantly urging clam-follower'122 axially outwardly. The axially outwardtur ging, of cam-follower 122 causes arms 131 to follow the annularly-disposed, circumferem tially-spaced, series of ramp-like cams 134 projecting axially inward on the axially inner side of an annular cam-ring 135, which ring 135 is rotatably mounted about body-portion 124'. 7

An internally-threaded, annular, retainer-ring 138 is screwed onto an externally-threaded end 1 39 of outersleeve 120, and-with axially-outer-faces of ring 138 and sleeve 120 flush, ring 138 is locked to sleeve120 bya set-screw 14!) extending radially through ring 138.

Thus, retaine ring 138 prevents the outward movement of cam-ring 135-which is urged by spring pushing against follower 122 and cam-ring 135, earn-ring abutting relation to "re,- Cam-follower 122 is restrained against 122 cyclically reciprocates in conformance'with the cams is urged, when cam-ring 135 [is One complete reciprocation slowly in:

ward, then instantaneously'outward, occurs in the sharp-' ening of each drill, as discussed further below.

Cam-follower 12-2 further includesfan axially-forward small-diameter ;internally-threaded ringf1 42, from dia;

metrically opposite sides'of which arms 121 extend axially inwardly. Ring 142 is slidably disposed withinbody portion 124 of'outensleeve 120, there being a relatively large diameter bore therefor at the outer extent of, outersleeve 12 0, seeFigfG; I i

An inner-sleeve 144 is slidably disposed Within sleeve 120. Inner-sleeve 144, having an,externally=threa ded,

of follower 122.

positioning-pin 14; at position therealong; Pin

projecting portion: bfpin ment other than a threading in accordance with the pitch the resultant relation between the drill projecting-knife flute 111, sharpened drill.

Considering; further the cam-ring- 135,; the radially outer-periphery, includes; a relatively larger diameter, toothed annulus and axiallyputward thereof a .relaa tivelysmaller diameter, smooth ,periphery,'shoulder 151--.. n fitaali; ri ay n n;. ppenannuiamin 1s4,;is slid-. lee e- .0- earrings; Bis; 5 75 mounted outwardly from carriage Ring 154, having an axial thickness only slightly less than the axial length of shoulder 151, is loosely held axially between annulus 150 and retainer-ring 138. Extending downward from ring 154 is a crank-arm 155, having an internally-threaded pawl-retaining-bolt hole 158, further therebelow a pull-rod-socket-pin hole 159, and to the side thereof a spring-receiving hole 160.

A pawl-retaining belt 165 extends through and has pivotally mounted thereon a driver-pawl 166, and further extends and is threadedly affixed in hole 158 in crankarm 155. threaded end 169 extending through hole 159, thence through a spring-holder clip 170. Nut 171 is screwed tightly onto end 169 aifixing pin 168 and clip 170 to crank-arm 155. Tension-spring 173 is hooked at its lower end to clip 170 and at its upper end to a rear lug 174 on pawl 166, pivotally urging the diametricallyopposite tongue 175 of pawl 166 upward into constant abutment and engagement with toothed-annulus 150 of cam-ring 135.

Referring now to Fig. 2, a stationary-pawl 180 is pivotally mounted on a fixed pin 181 projecting outward from rear-face 88 of carriage 85. Pawl 180 is disposed relative to toothed-annulus 150 such that a tension-spring 183, hooked to carriage 85 and the rear-lug 184 of pawl 180, constantly urges the diametrically-opposed tongue 185 of pawl 180 against the toothed-annulus 150 restraining counter-clockwise rotation of cam-ring 135.

An adjustable-length rod 188, having a socket-head 190 pivotally afiixed to pin 168, on arm 155, extends laterally from pin 168 through a hole 192 in a fixed bar 194. Bar 194 is mounted on the side of front, frame-extension 55, extending downwardly therefrom, and remaining fixed and stationary during reciprocation of carriage 85, chuck 105, and rod 188. Rod 188 has an enlarged head 195 incapable of passing through hole 192. A tension-spring 196 is attached to crank-arm 155 at hole 160 and to a flange 198 extending outward from rear-face 88 of carriage 85. Spring 196 constantly urges crank-arm 155 to turn counter-clockwise.

A boss 200 extends outward from rear-face 88 and has threaded therethrough an adjustable stop-screw 201, the butt end 202 of screw 201 being adjustably disposed in the path toward which crank-arm 155 is urged by spring 196.

From the above, it will be seen that the lateral reciprocation of carriage 85 and chuck 105 by cross-arm 83, will cause rod 188 to reciprocate in hole 192. To obtain the desired minute advancement of drill 110 toward grinding-wheel 45 once each reciprocal cycle, rod 188 is adjusted to such a shortened length that head 195 contacts bar 194 prior to the completion of the motion of carriage 85 toward the right. Thus, during the balance of the carriage right motion, spring 196 is forced to spread; crank-arm 155 is caused to pivot clockwise; pawl 166, engaged with toothed-annulus 150, rotates cam-ring 135; and cam-follower 122 is forced inward by relative motion of cams 134. When the carriage again moves left, spring 196 pulls crank-arm 155 back against stopscrew 201; pawl 166 slides back along toothed-annulus 150, which is held stationary by pawl 180. The amount of inward movement of follower 122 each cycle, or the number of cycles required for follower 122 to progress to the innermost position, will be dependent upon the amount of rotation of cam-ring 135 each cycle, or the number of teeth advanced each cycle. This amount may be altered by a machine operator by varying the length of rod 188.

Referring to Figs. 2, 3, 4 and 5, a drill-holder 205, is shown removably clamped in an abutting relation to chuck 105 by a clamping-jig 206 which is slidably 85 on two shafts 208. Shafts 208 are press fit into holes in carriage side-walls 89, and extend outwardly therefrom in a direction paral- A pull-rod-socket receiving pin 168 has a lel to the axial direction of chuck 105. Jig 206 includes two bearing-sleeves 210 which are slidably mounted on the shafts 208. Each shaft 208 has an enlarged outerhead, preferably a washer 212 and bolt 214 aflixed to the outer end of the shafts. Compression springs 216 are disposed on shafts 208 between each bearing sleeve 210 and the respective side-wall 89 and also between each bearingsleeve 210 and the respective washer 212, to maintain the disposition of jig 206 when tool 205 is removed therefrom.

Iig 206 has a central groove 218 extending thereacross parallel to bearings 210, for the reception of the cylindrical drill-holder 205, groove 218 having a depth slightly less than the diameter of holder 205. Holder 205, thus, projects slightly above the top surface of jig 206. A flexible locking-bar 220 is held firmly against the top surface of jig 206 at one end thereof by a press fit within a slot 222 in a raised, jig-end block 224. Bar 220 extends substantially across groove 218 and is locked downwardly, firmly holding drill-holder 205 by means of an eccentrically, pivotally mounted locking-arm 226 mounted thereabove. Locking-arm 226 is pivotally mounted on two raised bosses 228 extending upwardly from jig 206.

Drill-holder 205, Figs. 3 and 5, includes a cylindrical hollow body 230, an inner end, cylindrical, tightening ring 232, a long, knurled-head, drill-depth-adjusting, bolt 234, and an adjusting-boltlocldng set-screw 236. Adjustingbolt 234 is threadedly adjustably disposed in the outer end of hole 238, which hole extends axially and centrally through body 230. Body 230 is internally threaded adjacent the outer extent of hole 238 for the threaded reception of bolt 234. An axially-outer end-portion 240 of body 230 is partially separated from body 230 by a semi-circular radial groove 242 perpendicular to the body axis. End-portion 240 also includes a radial groove 244 parallel to the body axis extending radially outward in one direction along the base of groove 242. Grooves 242 and 244, thus, make yieldable a segment of end portion 240 adjacent both grooves, whereby set-screw 236, extending generally centrally and perpendicularly through groove 244 and threadedly engaged only below groove 244, when tightened, locks the adjusting-bolt 234 in a fixed position.

The inner end of body 230 has an end taper 248 extending from the end to a threaded cylindrical portion 250, and further includes preferably two opposed axially and radially extending slots 252, extending inward from the end preferably further than the extent of taper 248.

Ring 232 has an inside taper 254 and internal threading 256 complementary to taper 248 and threaded cylindrical portion 250, whereby tightening of ring 232 on body 230 locks drill disposed therein.

As discussed above, regarding chuck 105, cam-follower 122 and inner-sleeve 144, threadedly affixed together, are the two elements of chuck 105 subject to axial motion caused by follower 122 riding against the rotating cam surfaces of ramp-like cams 134. When fully assembled and operating, drill holder 205 is held in abutment with the outer end of sleeve 144 and bolder 285 and drill move axially with sleeve 144. Fig. 5 shows, in full, the axially moving elements in the inward position. Several broken line portions are shown in an outward position, to clarify the axial movement.

The adjustment of rod 188 is preferably such that approximately six reciprocal cycles of carriage 85 are required to rotate cam-ring one-sixth of a revolution, which is one full cycle of each of the follower arms 131 of follower 122 over respectively one of the six ramp-like cams 134. Thus, at the end of each of five reciprocations, drill 110 is moved axially inward toward grinding-whee; 45 and there held during the following reciprocation of carriage 85 and drill 110 past the grinding-wheel. At the end of the sixth such reciprocation, the further rotation of cam-ring 135 removes cams 134 from axially outward ofifollower-arms 134. Spring 130, thus, moves follower 122 axially outward to its outermost starting'position.

' .This outward movement of follower-.122 simultaneous: ly and abruptly stops the reciprocation operation of carriage 85 as will now be discussed. A double bent stop-rod 260, Fig. 2, has a laterally extending, upper-arm 262.1:otatably mounted in and extending outward from each end of ajhole 264 in the side-Wall 90 of carriage 85. Inward of side-wall 90, rod 260 includes a short centralarm 266 extending generally downward at 90 from the inner extent'of upper-arm 262. A. lower-arm 268 of rod 260 extendslaterally inward from the lower extent of central-arm 266 and parallel to. upper-arm 262. The innermost extent of lower-arm 268- is disposed axially in- 7 Ward of the lower' of the two follower-arms 131, Fig. 5.

A coil-spring 270, Fig. 2, is: disposed around upper-arm 262 immediately inward of side-wall 90, having one end held abutting carriage rear face. SSaand-the opposite end wrapped about central-arm 266 whereby central-arm 266.

and'lowerarm 268 are urged to'turn about rotatably mounted upper-arm 262, andlower-arm 268 is urged cn-' stantly outward against lower follower-arm 131.

Upper-arm 262, outward. of side-wall 90, hasa switcharm 272 fixed. thereon and extending upward therefrom. Arm 272 engages a start-stop switch 274 mounted on side-wall 90. The further-above discussed outward movementof follower 122 to its'outermost starting position, following six reciprocal cycles,

to, rotate lower-arm 268 outward, simultaneously. pivoting switch-arm 272 which opens an electrical circuit 275,

stopping motor 70; Motor 70 is. preferably of the instantaneous braking type, stopping immediately upon opening of the electrical circuit. Switch 274, constructedfor example as shown in Fig. 7, provides for man.- ual starting by depressing a. tension spring pulled lever by the operators finger, which lever is subsequently engaged and returned to reopen thejcircuit by arm 272 at-the end of the subsequent cycle. This restarting will ordinarily be performed after the insertion of an unsharpened drill 110. 3

7 Operation The automatic drill-pointer 20, built in accordance with the invention, is capable of resharpening a large plurality of drills in very rapid succession, free of burning by too rapid feeding into the grinding wheel and'with assurance of a proper ground angle of the drill end face relative to the drill axis and relative to the drill flutes.

Two drill-holders 205 will ordinarily be used witn-each machine inserted by a machine operator, at the same time that the allows spring 270.

20, one drill-holder having a drill shank end second drill-holder with a drill therein is clamped in jig 206 of machine 20, as shown grinding operation in process.

Prior to resharpening one set of a large number of drills, all of which are already of substantially equal length, the two drill-holders to be used are adjusted, identically, so that a'predetermined extent of drill 110 extends outward from the drill-holder. By using'drillin the drawings, with the holders with only certain given sets of drills, adjustment for each subsequent resharpening of the set consists of loosening set-screw 236, turning bolt 234 inward *a measured distance, and retightening set-screw 236 which-locks bolt 234. e

When drill-holder 205 is empty, tighteningring-232 isdisposed only loosely screwed onto body 230. The shank end of a drill is inserted into drill-holder 205 until bottomed against the inner end of bolt 234. Tighteningring 232 is tightened onto body 23%) by a quick tightening rotation thereof. Tightening of ring 232 causes inner taper 254 to depress taper 2480f body 230, whereby, due to the presence of groves 252, body 230 grasps andlocks drill 110 therein.

With the grinding-wheel-motor ordinarilyrnnning continuously, the' loaded drill-holder is mounted into 1 wide variation. of

place infiniachine 20; The drilland drill-holder are fed through groove 218 in jig 206, and the exposed extendingportion of drill is inserted in inner-sleeve 144' offchuck 105.: During such insertion, drill will encounter pin- 146. of inner-sleeve 144. Rotation of drill and drill holder .will allow the pin 146. to engage in flute 111 of drill- 110 andthe further insertion of drill 110 will be by a screwing of flute 111 on pin 146 until body 230 of drillholder 205. is tightly abutting the outer face of sleeve 144 of chuck 105.. drill is precisely positioned relative to grinding wheel 45 to. obtain the desired end profile after any predetermined removal of drill end by grinding; 1 i .Drill-holder 205 is. then locked in jig 206 by a quick. downward rotation of locking-arm 226, pressingbar. 220 lockingly againstthe drill-holder, restricting. any rota"- tion of. drill-holder relative to chuck 105. .Thexautomatic resharpening'operation' is commenced by activation of the reciprocal-drive-motor 70, by means of switch.274, the operation thereof proceeding automatically to'completion, in substantially the time requiredfor an operator to unload a prior used drill-holder and reload:for.a..subsequent resharpening operation.

Uponactivation of reciprocal-drive-motor 70, shaft 71: rotates, driving eccentric-wheel 75. Rotation of. wheel 75, Fig. 2, is clockwise, which, in'the resultant reciprocating of carriage 85, causes a'relatively slower motion to the left and a relatively faster return stroke. Theileft: stroke. occurs just subsequent to the previously discussed axially inward advancement of drill 110 and provides-a relatively slower grinding stroke. The faster right stroke, with the drill: no further ing stroke. By a flattened top portion on ramp-like: cam, 134;.Fig. 5,'there will belittle or no advancement of thedrill prior to the lastreciprocal cycle and both the left and right strokeofthe last reciprocal cycle providevery complete. polishing of 'theresharpened drill. a On completion of the last reciprocal cycle, the. drill is axially retracted to the. starting position and rod 260:

turns causing switch 274 to stop and brake. reciprocaldrive-motor 70. Locking-,arm'226 is then manually raised and drill-holder; 205 is.removed from jig.206. Grinding: wheel-motor 35; continues todrive grinding-wheel 45 andj machine 20:is in conditiontoreceivefthe alternateloadedj. drill-holder.for the next resharpening operation.

Machine 20; thus, provides anovelimeans for. automaticallyresharpening very rapidly, numerous twistdrills, all to'an exactly identical length, as is critical forusein. gangdrillheads. The novel machine "is adapted for at. rates of feed of drills andamountofi drill end material to be removed by grinding: It. is

readily capable of modifications in type of feed by; change) of cam-ring, and in type of reciprocation by'changeof: eccentric-wheel. ables; dependent maybe automatically and very rapidly resharpened, free of any'human errors ;in end profile, free of; burning by. improper feeding, smoothly, polished, andall of exactly. equal length.

Having completeda detailedadisclosure of the: preferred embodiment of my invention so that those skilled in the artmay practice the same, I contemplate that variations may 'bernade withoutfdeparting from the. essenceof the invention-or the scope of the appended claims.

I claim: 0 V V 1 1. An automatic drill pointer compn'singa grinding element, a removable drill for the predetermined depth reception of a drill shank for holding adrill, a chuck for the reception of the drill bit endprojecting from said drill holder, said drill holder with said drill thereinbeing.readily'mountabletoa fixed position relative to said chuck, means for'reciprocating In such disposition of drill 110, 1 the advanced, provides a fastpolish- By proper; determination of-;these.-vari-- on the drills tobe, sharpened, all drills.

holder having adjustablemeans means providing a controlled progressive feed whereby an improved, non-burning, resharpening is obtained.

2. An automatic drill pointer as defined in claim 1 wherein said chuck is mounted on a reciprocally mounted carriage and said removable holder is tightly held in a jig which is mounted on said carriage, said jig being slidable relative to said carriage in a direction axially of said drll.

3. An automatic drill pointer as defined in claim 2 wherein a positioning pin is disposed in said chuck for engaging the flute of said drill whereby said drill is restrained against rotation therein.

4. An automatic drill pointer as defined in claim 1 wherein said means for progressively advancing said drill include means for activating said advancing intermittently at the completion of reciprocations.

5. An automatic drill pointer as defined in claim 1 having means for intermittent progressive advancement of said drill and means for relatively slow grinding reciprocation movement mittent advancing and a subsequent relatively fast polishing reciprocation movement all prior to the next intermittent advancing.

6. An automatic drill pointer comprising an abrasively surfaced grinding element, a carriage reciprocally mounted relative to said grinding element, means for reciprocating said carriage, a chuck mounted on said carriage, said chuck having an outer sleeve fixedly mounted on said carriage, an inner sleeve axially slidably mounted Within said outer sleeve, cam follower radial arms fixed to said inner sleeve, projecting radially outward through axial, radial slots in said outer sleeve, a cam ring rotatably mounted and axially fixed on said outer sleeve having an axially projecting, annular cam profile adjacent said radial arms, means for rotating said cam ring simultaneously with said reciprocation, spring means urging said radial arm against said cam profile, whereby said radial arms and said inner sleeve are moved axially in accordance with said cam profile, providing means for a predetermined advancement of said drill relative to said grinding element during operation.

7. An automatic drill pointer comprising an abrasively surfaced grinding element, a carriage reciprocally mounted relative to said grinding element, means for reciprocating said carriage, a chuck mounted on said carriage, said chuck having an outer sleeve fixedly mounted on said carriage, an inner sleeve axially slidably mounted within said outer sleeve, cam follower radial arms fixed to said immediately following said interouter periphery,

inner sleeve, projecting radially outward through axial, radial slots in said outer sleeve, a cam ring rotatably mounted and axially fixed on said outer sleeve having an axially projecting, annular cam profile adjacent said radial arms, means for rotating said cam ring simultaneously with said reciprocation, spring means urging said radial arms against said cam profile, whereby said radial arms and said inner sleeve are moved axially in accordance with said cam profile, said cam ring having a toothed a stationary pawl and a reciprocally driven pawl cooperative therewith, activated by the reciprocation of said carriage, mounted for engagement with said toothed periphery, providing means for a predetermined advancement of said drill relative to said grinding element during operation.

3. An automatic drill pointer comprising an abrasively surfaced grinding element, a carriage reciprocally mounted relative to said grinding element, means for reciprocating said carriage, a chuck mounted on said carriage, said chuck having an outer sleeve fixedly mounted on said carriage, an inner sleeve axially slidably mounted within said outer sleeve, cam follower radial arms fixed to said inner sleeve projecting radially outward through axial, radial slots in said outer sleeve, a cam ring rotatably mounted and axially fixed on said outer sleeve having an axially projecting, annular cam profile adjacent said radial arms, means for rotating said cam ring simultaneously with said reciprocation, spring means urging said radial arms against said cam profile, whereby said radial arms and said inner sleeve are moved axially in accordance with said cam profile, providing means for a predetermined advancement of said drill relative to said grinding element during operation, said chuck further including means for returning said inner sleeve and radial arms to an axially outer position after reaching an innermost position, and a stop switch activated by said return movement to deactivate said reciprocation.

References Cited in the file of this patent UNITED STATES PATENTS

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