US2252303A

US2252303A - Drill grinder

Info

Publication number: US2252303A
Application number: US260344A
Authority: US
Inventors: Edd C Oliver
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-03-07
Filing date: 1939-03-07
Publication date: 1941-08-12
Anticipated expiration: 1958-08-12

Description

E. C. OLIVER I DRILL GRINDER Aug. 12, 1941.

8 Sheets-Sheet l Filed March 7, 1939 ATTORNEY.

Aug. 12, 1941. c, o vg 2,252,303-

DRILL GRINDER Filed March 7, 1932 8 Sheets-Sheet 2 INVENTOR ATTORNEY. I

E. C. OLIVER DRILL GRINDER Aug. 12,1941.

Filed March '7, 1939 8 Sheets-Sheet 4 INVENTOR.

Afig. 12, 1941. Q QUVER 2,252,303

DRILL GRINDER Filed March 7, 1939 8 Sheets-Sheet 5- vim g INVENTOR. I1. 5.2. 50 4 a o/n e/ ATTORNEY.

Aug. 12, 1941. E. c. OLIVER 0 DRILL GRINDER Filed March '7, 1939 8 Sheets-Sheet 6 ATTORNEY.

1941- l E. 'c. OLIVER 2,252,303

' DRILL GRINDER Filed March 7, 1939 8 Sheets-Sheet 7 INVENTOR. 3 50 0 6. a l

ATTORNEY.

E.- C. OLIVER DRILL GRINDER Aug. 12, 1941.

Filed March 7, 19:59 8 Sheets-Sheet a INVENTOR. Er/o/ 6. O/I'V/ BY ATTORNEY.

Patented Aug. 12, 1941 UNITED STATES ATENT OFFICE DRILL GRINDER,

. Edd 0. Oliver, Adrian, Mich.

Application March 7, 1939, Serial No. 260,344

Claims.

This invention relates to variable point drill grinder, the object of the invention being to provide a machine of such structure as to permit grinding the points of twist drills to various chisel point angles and also involving means providing for variation in clearance on the lands of the drill and thus adapting the machine for use in grinding drill points for different characters of metal to be drilled.

there being a positive relation between the position of the lands of the drill during rotation in respect to the position of the grinding wheel as is hereinafter described irrespective of the angle of presentation of the drill.

A further feature and object of the invention is to provide a mechanism for grinding a drill to provide a slightly rounded chisel point hereinafter termed the point of web intersection to more readily permit the drill to enter a center punch mark than has heretofore been secured with the older type of drills.

The character of the drill point to be formed by the machine is shown and described in my U. S. Patent No. 1,467,491 of September 11, 1923 and the machine embodying the invention herein described is similar to the drill point grinder shown in my U. S. Patent No. 1,546,453 of July 21, 19 26 but differs therefrom in many respects, principally in that it is adapted. to grind two, three or four lipped drills having points within the full range of point and clearance angles.

These and various other objects and novel features of the invention are hereinafter more fully described and claimed, and a machine embodying my invention is shown in its preferred form in the accompanying drawings in which-- Fig. 1 is a plan view of the machine.

Fig. 2 is a front elevation of the machine.-

Fig. 3 is a vertical section of the machine taken on line 33 of Fig. 4.

Fig. 4 is a sectional View of the head of the machine taken on line- A--4 of Fig. 3.

Fig. 5 is a face elevation of a cam adjuster.

Fig. 6 is a. side elevation thereof.

Fig. '7 is a face view of a circular cam for varying the clearance angle.

Fig. 8 is a side elevation thereof.

Fig. 9 is a diagrammatic view showing the cam face laid out in a straight line.

Fig. 10 is a face view of a twist drill as formed by the machine.

Fig. 11 is a section taken on line Iill of Fig. 4. i

Fig. 12 is an enlarged section through the cam adjuster taken on line 3-3 of Fig. 4.

Fig. 13 is a face elevation of the chuck showing the gauge for the drill point and associated parts in the plane of line l3-l 3 of Fig. 1.

Fig. 14 is an enlarged section taken on line i4l4 of Fig. 3.

Fig. 15 is an enlarged view showing the train of gearing for driving the drill rotating mechamsm.

Fig. 16 is an elevation showing the grinding wheel and relationship of the drill point thereto in the grinding operation.

Fig. 17 is a diagrammatic View of certain pulleys and the motor driven belt for driving the same.

Fig. 18 is an enlarged sectional view of the change speed. mechanism.

Fig. 19 is a section of a clutch mechanism.

Fig. 20 is a section taken on line 20-28 of Fig. 19.

Fig. 21 is an elevation of a convenient means for operating the cam adjuster.

Fig. 22 is a section taken on line 22-22 of Fig. 20.

Fig. 23 is an elevation of a cam sleeve.

Figs. 24 and 25 are respectively an end and a side elevation showing the lands of the drill formed with more than two concentric areas at different angles to the longitudinal axis of the drill.

Figs. 26 and 2 7 are respectively an end and a side elevation of the lands of the drill having the surface ground to provide two concentric areas at different angles to the longitudinal axis of the drill.

The machine, according to this invention, is so designed and constructed as to form the cutting end of a twist drill, a face view of a two lipped drill being shown in Fig. 10 but, as hereinafter shown, the machine is adapted to form two, three or four lipped drills as may be desired. In the drill indicated in Fig. 10, the angle of the chisel point to the cutting edge of the lip is shown as being about degrees but this angle may vary. As hereinafter described, the machine is adapted to form a point angle of from 82 to 160 degrees and thus to secure a drill of the desired cutting action for metals of various characters.

In the construction herein shown, the chuck I for carrying the drill is swingable on an are about a vertical axis cutting the point I2 of Fig. 1, it being carried by a base plate 2 having a tongue riding in an undercut slot II) of arcuate form in the carriage or table 2. This table with the chuck therein is movable in a straight line by means of a screw 3 operable by a handle 4 by rotation of which in one direction or the other, the drill is moved toward or away from the grinding wheel 5.

The grinding wheel, shown in the enlarged view Fig. 15, is of the ring type and the drill is rotated by mechanism hereinafter described in the direction shown by the arrow and the drill is positioned with the cutting edge of the land 6 of the drill in engagement with the wheel and the point of web intersection is practically at the inner edge of the wheel so that as the drill is rotated the land is cut away to the rear from the cutting edge on an oblique helicoid to provide clearance practically of equal extent clear to the point except that the point itself is not ground away. Thus a hollow indicated at I in Fig. 10 is produced in front of the chisel point 8 which increases in depth toward the rear of the land due to the turning of the drill and the feeding in movement of the grinding wheel. This form of drill point is fully described in my U. S. Patent No. 1,467,491 of September 11, 1923.

The chuck I is mounted on a table that is movable on. a straight line parallel with the axis of the shaft 9 of the grinding wheel as will be understood from Figs. 1 and 2 while the chuck is swingable through the are formed by the way I in the carriage 2 as heretofore stated. This swinging of the chuck varies the angle of the longitudinal axis of the drill relative to the face of the grind ing wheel'and by varying the angle of the presentation of the drill to the grinding wheel the point angle may be varied.

By means of the hand wheel 4, the carriage 2 is movable to bring the face of the drill to cutting position and for the purpose of correctly positioning the drill, a movable gauge I I is provided, the upper end I2 of which lies between the face of the grinding wheel and the chuck (which 1 may be freed from its driving mechanism as hereinafter described) is turned by the handle [2a to position the cutting edge of the lip parallel with the gauge end I2. When so positioned, the plate 2 is then moved to position the drill in engagement with the grinding wheel and the mechanism for rotating the chuck operates to turn the drill to bring the successive lands to proper position for the grinding operation by the wheel.

The general arrangement of the parts is shown more clearly in Fig. 3 in which there is a base or column I3 and in the bottom thereof is a motor I4 on the shaft of which is a pulley I5 having a belt I5 rotatable in the direction shown by the arrows in Fig. 17 and riding over a pulley I'I thence under a pulley I8 and over a pulley I9 driving the grinding wheel shaft 9, the pulley I8 driving the shaft 28 and the pulley I'I driving the shaft 2 I.

In the construction shown, there is an arm 23 attached to the base and supporting a tray 24 on which the head of the machine is mounted and which carries a support 25 for the slide 26 on which the carriage 2 supporting the chuck is slidable by the screw 3. It is to be noted that the shaft for the screw passes through a bearing member 2'! and has a ring flange 28 on the inside of the bearing member and the hub of the wheel contacts the outer face thereof thus fixing the screw shaft from longitudinal movement in the member 2'? which in turn is fixed to the carriage 2 carrying the chuck and also to a cover plate 28a on the under side. Thus rotation of the screw in respect to the fixed nut 29 secured in the slide 25 moves the chuck. The drill 30 is placed in the chuck so that the land of the drill lies across the V of the chuck jaws 3i and 32 as shown in Fig. 13 and as the cutting edge of the lip may not be in correct relation to the wheel, means is provided permitting manual revolution of the chuck to bring the cutting edge to proper relation with the gauge. The clutch 53 is then engaged with the driving mechanism hereinafter described and by the positioning of a drill at the inner periphery of the ring grinding wheel as indicated in Fig. 15, the drill is turned so that the drill runs off the inner face of the grinding wheel and this action causes the chisel point of the web intersection to be slightly rounded thereby permitting the drill to enter a center punch mark more readily than is the case with the drill formed by the machine shown and described in my U. S. Patent No. 1,546,453.

The chuck jaws are rotatable within the outer case shown at I in Fig. 1 and there is an arm 33 extending from the rear end of the casing on which is an adjustable bracket 34 carrying an adjustable center point 35 engaging the rear end of the drill 3S and thus drills of different lengths may be mounted in the chuck. The jaws are driven by a telescoping shaft 36 having universal joints 3'! therein to secure flexibility. A portion of this shaft is shown in Fig. 1 and has a stub 38 connected with a driving gear 39 at the one end as shown in Fig. 14 and the opposite end has a stub shaft portion 40 in a housing 4I supported by the chuck casing and on which is a beveled gear 42 driving a beveled gear 43 mounted in the rear end of the casing for the chuck as shown in Fig. 15. Thus rotation of the shaft 35 will rotate the drill during the grinding operation. This telescoping shaft and universal joint structure permit the chuck to be swung in the groove It in the carriage 2. The shaft is driven by the gear 39 as previously stated which meshes with an intermediate gear 44.

The driving element in Fig. 15 has the gears laid out in a line so that the drive for the telescoping shaft 36 will be readily understood. In Fig. 14, it will be noted that the gear 44 has a short shaft 45 supported in the head casting and the gear 44 meshes with a gear 46 mounted on the shaft 41 which is integral with an enlarged portion 48. Fixed on the enlarged shaft portion 48 are the stepped gears 49, 50 and BI.

Also fixed on the shaft 48 is one member 52 of a jaw clutch, the other member 53 of which is slidable longitudinally of the shaft 48, it having a pin 54 extending through a slot provided therefor in the shaft 48. The pin 54 passes through a shaft 55 slidable within the hollow end of the shaft 48 and extends therefrom to engagement with an eccentric cam 55. Rotation of the cam by the handle 51 and shaft 58 causes the clutch members 52 and 53 to be engaged or disengaged and by disengagement of the clutch elements the jaws of the chuck may be rotated to properly position the drill point relative to the gauge and then the clutch may again be engaged. This operation of the eccentric element 56 is by means of an operator handle 51 extending to one side ofthemachine shown in Fig. 14 whereby the shaft 58 carrying the eccentric 56 may be moved to release the clutch against the tension spring 59 which, when free to act, holds the clutches in engagement. The engagementof the chuck with the driving means is thus positive.

The

gears

49, 50 and are respectively in mesh with the gears 66, BI and 62 rotatable on a hollow shaft 63 and a clutch device is provided for engaging one or the other of the gears to the shaft which consists of the operating rod 64 slidable in the shaft 63 and having notches therein for engagement with the spring pressed pin 65, shown in Fig. 3, there being a notch for each gear.

This rod 64 has a pivoted latch member 66 at its inner end and has an endriding in a slot in the shaft 63 to engage a keyway provided in the hubs of the gears. By sliding the rod 64 one or the other of the gears may be fixed to the shaft by the latch. This arrangement adapts the machine for the grinding oftwo, three or four lipped drillsbut in the grinding of any one of the drills, the cutting edges are brought consecutively to similar position for operation by the grinding wheel. The structure of the control means for the gears 69, 6I and 62 -is shown more clearly in Fig, 14 from which it will be realized that the pawl or latch member 66 is pivoted to the end of the shaft 64 and as will be seen in Fig. 18,.the latch member 66 has an angular face engaged by the spring pressed element 61 which tends to hold the latch member in position. There is a spacing ring 6i] between the gear 69 and 6| and a similar spacing ring 69* between the gear 6| and 62. These rings have an inside diameter fitting the shaft 63. This arrangement permits the latch element to be depressed by the inner edge of the spacing rings at the notches in the gear in moving from engagement with its way in one gear to position within the center of the other gear and to engage in the notch therein. Means may be provided to indicate the position of the clutch element through movement of the rod 64 as, for instance, by gauge marks 66 on the projecting end of the shaft 64.

While the grinding wheel is carried by the shaft 9 and rotates on the shaft axis, the said shaft is mounted in bearings II. The seats for these hearings are eccentric to the axis of the shaft 9 and mounted within the quill 19. In other words, while the grinding wheel rotates on an axis, the wheel, as a whole, is caused to re- .volve about a center eccentric to its axis of rotation. Rotation of the quill therefore causes an oscillation of the shaft 9 and consequent movement of the grinding wheel relative to the drill point. which is held by the chuck to rotate on a fixed axis. This oscillatory movement of the grinding wheel is illustrated somewhat diagrammatically in Fig. 16.. In locating the lands of the drill, as heretofore stated, across the jaws of the chuck, the cutting edge of the land is located by the gauge and the grinding wheel is then set into operation and as hereinafter shown, the grinding wheel feeds toward the drill as the drill is being rotated and, thus the point of web intersection, due to the oscillation of the grinding wheel, is relatively moved in respect to the inner edge 5 of the grinding wheel asthe wheel is moved into the work to the full extent. This causes the drill to be undercut to the rear of the land and adjacent the web intersection as indicated at I in Fig.10.

The feed of the grinding wheel is secured by means of an adjustable cam 99 which is of ayring form and is mounted on the quill I9 as shown in Fig. 3. This adjustable cam is shown in Figs. 7, 8, 9, 11 and 12. This cam consists of a split ring 9| shown in face view in Fig. 7 having a peripheral' face portion 92 shaped as indicated in the diagram Fig. 9, it having a straight portion 93 parallel with the base from A to D,.a sharp outwardly inclined face portion 94 from D to C and an inwardly inclined portion 95 of less angle than 99 extending from C to B and then from B to A a sharply inclined portion 96. This cam is secured to the quill as by screws or pins 91, 98

- and 99, the screw 99 being some distance peripherally from the slot I 09 between adjacent ends of the cam. Thus, as the quill is rotated, it rides in engagement with an adjustable plug IliI, the location of which is shownin Fig. 3. This plug, as shown in Fig. 3, is adjustable by having a threaded end I92 in the casing part therefor and has a slot I63 in which there is a pin I99 to hold the same from rotation and a set screw I65 to hold the same from longitudinal movement. The grinding wheel is spring pressed to the right in Fig. 1 by the spring I01 engaging the pin I96 which in turn engages the'side face of the gear E99 secured to the quill. This spring holds the cam face 99 in engagement with the adjustable plug Hit and due to the configuration of the cam shown in Figs. '7, 8 and 9 the grinding Wheel is moved into the work and against the tension of the spring I91 which retracts the wheel from the Work when the portion 93 of the cam is in engagernent with the plug It". An adjusting screw I96 is provided to secure the desired spring tension.

The spring, as the revolution is completed, moves the grinding wheel away from the drill at the completion of the grinding at which time the sharply inclined portion 96 of the cam rides the adjustable plug IiiI. This portion 99 of the cam provides for a quick retraction of the grinding wheel thus preventing engagement of the next land of the drill therewith. During the time the cam portion 93 engages the plug IIJI the drill has been turned to position the next land of the drill for grinding. This portion 93 of the cam permits the grinding wheel to remain in retracted position and the cam is so rotatively positioned that the portion 94 begins to feed the grinding wheel forward into the work. The end of the cam ring at 99 is free to be adjusted to vary the position of the angular face 95 to thereby increase or decrease the extent of the feeding movement of the wheel as it passes off the land in forming the hollow 1 at the point of web intersection. This end 96 of the cam is adjusted by a cam element I09 rotatably supported in a recess provided in the flange of the gear 12. This cam member I99 has apertures in the enlarged head thereof to receive an adjusting pin for the turning of the same and the inner face of the head portion has a circular cam face IIEI on which a pin III engages at one end, the opposite engaging end 96 of the cam ring 99 as will be understood from Figs. 9 and 11.

Adjustment of the cam is provided through removal of the cap plate I I3 at the top of the head and the gear 72 has an aperture therein through which the pin I I2 may be introduced to rotate the member I69 and thus to vary the angle of the face portion 95 of the cam ring 99.. The rotatable adjusting cam I 09 is held in the adjusted position by a spring pressed centering pin I99 on the under side directly opposite the point of introduction of the adjusting element H2 which is introduced through the aperture I I9. of the gear "I2 as in Fig. 12. The clearance angle may thus be varied by use of the cam 93 and likewise the depth of the cut of the wheel as the point of web intersection of the drill moves off the inner face of the grinding wheel by reason of oscillation of the quill.

Thus a lip or land of the drill is ground through one revolution of the quill and a new land is brought to grinding position at each revolution of the quill. The wheel is rotated at comparatively high speed due to its belt drive by the pulley I9 while the quill is rotated at a slow speed and so timed in its movement that the point of web intersection passes off the inner periphery of the grinding wheel. The position of the portions A, D, C and B of the cam 90 in respect to the drill point are indicated in Fig. 10 from which it will be seen that the angle A, D, etc., of the cam is twice the same angle on the drill so that each land is formed by a complete revolution of the cam. In a three lipped drill, the angles A to D to C on the cam would be three times and with a four lipped drill four times the same angle on the drill diagram.

It is thus to be seen that a drill of a two, three or four lipped type may, by choice of the driving gears 60, 6| or 62 through the

respective gearing

49, 50 or be rotated at a speed to bring the successive lips of the drill to the starting position in respect to the grinding wheel and in timed relation with the feed of the grinding wheel toward the drill in order that each land may be ground with the proper clearance.

It will be realized that the chuck, while adapted to rotate the drill, holds the drill during the grinding in a fixed position in respect to the grinding wheel and that the grinding wheel requires to be fed into the work as the work is turned. This feed-in movement of the grinding wheel is provided by a cam which is variable as hereinafter shown in order that the face of the drill may be formed with different clearances for drills required for different characters of metal.

The grindin wheel is mounted on the shaft 9 which is rotatable by the pulley I9 by means of a belt I6 which, as previously stated, also drives the pulleys I! and I8. Incidentally, it is pointed out that the pulley I1 is here shown as driving the water pump 69 which is only used with what is known as wet machines. The pulley, however, may be used for other than the wet machines. The quill has the bearings 1| at opposite ends of the quill for supporting the shaft 9 and the quill is driven by a gear I2 which is bolted to a flange provided on the quill as shown and the gear I2 is in mesh with a gear I3 keyed to the shaft 63 which supports the stepped gears 60, 6I and 62.

The entire train of gearing is not shown in Fig. 3 due to the varying location of the gears but the drive for the gear, shaft 63 and shaft 36 leading to the chuck is laid out in line in Fig. 15. From this View it will be seen that the quill I9 has its gear I2 meshing with the gear I3 on the shaft 63 and there is a companion gear I3 loose on the shaft 63 and driven by a pinion I4 on the shaft point when the cutting edge of a land of the drill is'presented for the grinding operation at which time the grinding wheel is again fed into the work. It 'is thus important that the position of the cam rotatively be in timed relation with the rotation of the drill and further it will be realized that as one drill has been ground, the ground drill must be removed from the chuck and a new drill positioned therein and that the chuck be then turned to position the cutting edge of the land in respect to the gauge end I2 shown in Fig. 13.

To so manually rotate the chuck elements to properly position the drill for the grinding operation, it is necessary that the chuck be freed from the driving mechanism and when it again is to be driven it must be in timed relation with the rotation of the cam. For this purpose, I provide a clutch member 11 by means of which the gear I3 may be connected or disconnected with the gear I3. The clutch mechanism is shown in Figs. 19, 20, 22 and 23 in which the gear I3 is shown. The arrow adjacent the toothed periphery indicates the direction of rotation and the gears I3 and I3 in Figs. 19, 20 and 22 which views are taken on the opposite side from that shown in Fig. 15. The clutch means includes a spring pressed lever H4 carried by a shaft H5 mounted below the cap H6. The operating lever H1 is attached to a shaft H8 and this shaft has a cam end I I9 within the cap. The cam end H9 has opposed flat surfaces I20 and I2I at a right angle one to the other and the distance of the center of rotation of the cam end is nearer to the flat face I2I than to the flat face I20 at a right angle thereto. In the position shown in full lines in Fig. 19, the flat face I2I is in engagement with the end I22 of the lever H4 and when the lever I I1 is turned to the dotted line position the face I29 of the cam H9 engages the face of the portion I22 of the lever H4. By the turning of the lever I I! to the full line position the cam plate I23 carried by the lower end of the lever I I4 as shown in Fig. 22 is in position to ride into the cam slot I24 in a sleeve I25 slidably supported in the hub I26 of the gear I3.

There is a pin I21 which extends through the hub and slots I28 in the sleeve I25 and holds the sleeve from rotation. This sleeve has a circular end portion I29 adapted to fit into a recessed plate I39 secured in the gear 13 There is a spring I3I in the central recess I32 of the sleeve supported at one end by the pin I21 and in the bottom of the recess at its forward end. This spring therefore normally tends to move the sleeve longitudinally to insert the end I29 into the recess in the plate I30 to lock the gears 13 and I3 together. In the revolution of the gear I3 the cam plate I23 will, when the lever H4 is in the position shown in Fig. 1-9, ride into the slot I24 at the wider forward end which has an inclined face I33 and then into engagement with the face I34 and move the sleeve I25 to the right of the position shown in Fig. 20 and thus release the gear I3 from the gear 13 This is what is termed a one revolution clutch and it stops the operation of the gear train, the chuck, and the drill carried thereby always in the same rotative position and likewise stops the quill I0. Thus the position of the grinding wheel in its movement toward or from the drill is maintained in constant operative relationship with the lands of the drill. Upon release of the clutch plate 52 from the plate 53, the clutch plate 53, shaft 48 and gears 46, 44 and 39, the shaft 36 and gear 43 may be manually turned to rotate the chuck to accurately position the lands of the drill in respect to the grinding wheel.

- are therefore co-related to produce the desired.

face of the land. When the drill has been located in its desired position relative to the gauge, the lever I ll isturned from the full line position to the dotted line position shown in Fig. 19 withdrawing the cam plate from possibility of being engaged by the cam face of the slot I24 in the sleeve I25.

The machine will continue to operate in timed relation with the lands of the drill as they are presented in sequence through rotation of the drill for the grinding operation and the grindin operation is automatic and continuous through the forming of the lands on either a two, three or four lipped drill, in that the speed of rotation of the drill is dependent upon which of the gears ASL-d, Ell-Bl, 5l62 are operated and this choice of the change speed gears last mentioned is secured by the mechanism shown in Fig. 18 heretofore described.

The foregoing description has been confined to the formation of the lands of the drill with surfaces at a uniform angle to the drill axis. It is possible to provide a drill as shown in Figs. 26

and 27 with an angular surface Ml] at the periphery of the land at a less angle to the longitudinal axis of the device than the surface at l4! This may be accomplished with the machine as disclosed by setting the drill at the angle with the axis thereof as indicated at the left side of Fig. and after the lands have been ground at the said angle then, by turning the chuck in the arcuate slot I!) to a less angle relative to the face of the wheel, grind the surface Hill. A drill having the lands ground in the stated manner is often desirable in that the surface Mil serves to maintain the drill centered.

The drill may also be ground as shown in Figs. 24 and 25 to form the surface I42, the surface I43 and the surface I44, By changing the angle of presentation of the drill to the face of the grinding wheel and making three successive grinds, first to provide a land at the angle of the surface IM and next to cut the remaining surface at the angle Hi3 and finally in the third grinding operation to form the surface M2 thereon. Drills as indicated in Figs. 22 to 25 inclusive are desirable in some classes of metal in that the drill is more firmly supported during the drilling operation.

It is believed evident from the foregoing description, that the various features and objects of the invention are attained by the structure described namely, that the machine is adapted to form a variable point in respect to angle of cutting edges to web intersection, variation in the form of the face of the land in providing various clearance angles and the formation of a drill at various point angles for varying characters of work, and that various changes may be made in the structure and relationship of parts forming the machine Without departing from the spirit and scope of the invention as set forth in the appended claims.

Having thus fully described my invention, its utility and mode of operation, what I claim and desire to secure by Letters Patent of the United States is-- 1. In a machine for grinding twist drills having two or more lands provided with cutting edges at a predetermined angle to the web of intersection, a holder for the drill, a grinding wheel for grinding the same,meansfor varying the angle of presentation of the lands to the face of the wheel to vary the point angle, means for turning the drill during the grinding movement, means for causing the grinding wheel to feed into the work as the drill is turned whereby the land is ground at a predetermined clearance angle, and means for moving the wheel laterally of its axis of revolution during the grinding of a land in such man- ,ner that, as the web intersection passes off the cutting face of the grinding wheel, the wheel is moved to its full extent into the work at the rear of the land to thereby grind the face of the land to a predetermined depth from the axial point of the drill forward of the web intersection at the time the wheel reaches the limit of its lateral movement in one direction and reaches the limit of lateral movement in the opposite direction as the next land through rotation of the drill is presented for the grinding operation.

2. In a machine for grinding twist drills, a chuck having jaws for holding the drill, a grinding wheel for grinding the same, said chuck being mounted to swing on an arc to present the .drill point at various angles to the face ofthe grinding wheel to thereby vary the point angle of the drill, a-gear for driving the chuck jaws to rotate the drill, a rotatable shaft for the grinding wheel, driving means for the shaft, .a rotat able holder for the shaft, the axis of rotation of the holder being eccentric to the axis of rotation of the shaft, a gear for rotating the holder, means whereby rotation of the holder for the grinding wheel shaft causes a reciprocation of the holder and shaft to move the grinding wheel toward the drill during the grinding of a land to secure a predetermined form of land and to retract from, grinding position as the next land is brought by rotation of the drill to grinding position, a gear train through which the gear rotating the chuck jaws and gear for reciprocation of the holder for the grinding shaft are actuated in timed relation, a driving gear for the gear train, means for releasing the gear train from the driving gear to permit rotation of the drill holding jaws to rotatively position a land of the drill with the cutting edge in predetermined relation to the face of the grinding wheel, said releasing means being operable to connect the gear train with the driving gear in such manner that subsequent rotation of the holder for the grinding wheel shaft and reciprocation thereof is in timed relation to present the successive lands of the drill for the grinding operation when the grinding wheel is in retracted position.

3. In a machine for grinding twist drills, a chuck having jaws for holding the drill, a grinding wheel for grinding the same, said chuck being mounted to swing on an arc to present the drill point at various angles to the face of the grinding wheel to thereby vary the point angle of the drill, a gear for driving the chuck to rotate the drill, a rotatable shaft for the grinding wheel, driving means for the shaft, a rotatable holder for the shaft, the axis of rotation of the holder being eccentric to the axis of rotation of the shaft, a gear for rotating the holder, means whereby rotation of the holder for the grinding wheel shaft causes a reciprocation of the holder and shaft to move the grinding wheel toward the drill during the grinding of a land to secure a predetermined form of land and to retract from grinding position as the next land is brought by rotation of the drill to grinding position, a gear train through which the gear rotating the chuck and gear for reciprocation of the holder for the grinding shaft are actuated in timed relation, a driving gear for the gear train, means for releasing the gear train from the driving gear to permit rotation of the drill holding jaws to rotatively position a land of the drill with the cutting edge in predetermined relation to the face of the grinding wheel, said releasin means being operable to connect the gear train with the driving gear in such manner that subsequent rotation of the holder for the grinding wheel shaft and reciprocation thereof is in timed relation to present the successive lands of the drill for the grinding operation when the grinding wheel is in retracted position, and means for varying the speed of rotation of the chuck.

4. In a machine for grinding twist drills, a chuck having jaws for holding the drill, a grinding wheel for grinding the same, said chuck being mounted to swing on an arc to present the drill point at various angles to the face of the grinding wheel to thereby vary the point angle of the drill, a gear for driving the chuck jaws to rotate the drill, a rotatable shaft for the grinding wheel, driving means for the shaft, a rotatable holder for the shaft, the axis of rotation of the holder being eccentric t the axis of rotation of the shaft, a gear for rotating the holder,

'a cam rotated by the holder for the grinding wheel shaft to cause reciprocation of the holder and shaft to move the grinding wheel toward the drill during the grinding of a land to secure a predetermined form of land and to retract from grinding position as the next land is brought by rotation of the drill to grinding position, a gear train through which the gear rotating the chuck jaws and gear for reciprocation of the holder for the grinding shaft are actuated in timed relation, means for varying the throw of the cam to thereby increase or decrease the extent of feed of the grinding wheel toward the drill, a driving gear for the gear train, means for releasing the gear train from the driving gear to permit rotation of the drill holding jaws to rotatively position a land of the drill with the cutting edge in predetermined relation to the face of the grinding wheel, said releasing means being operable to connect the gear train with the driving gear in such manner that subsequent rotation of the holder for the grinding wheel shaft and reciprocation thereof is in timed relation to present the successive lands of the drill for the grinding operation when the grinding wheel is in retracted position, and means for varying the speed of rotation of both the chuck jaws for the drill and the holder for the grinding wheel shaft in timed relationship.

5. In a machine for grinding drill, a rotatable holder for the drill, a grinding wheel for grinding the same, a shaft for the grinding wheel, a r0- tatable holder for the grinding wheel shaft, means for simultaneously rotating the holder for the drill and holder for the grinding wheel shaft in timed relationship, a cam rotatable by the holder for the grinding wheel shaft arranged to reciprocate the said last named holder to cause the grinding wheel to feed into the work and to retract therefrom as the successive lands of the drill are brought to grinding position, and means for Varying the throw of the cam to thereby increase or decrease the extent of feed of the grinding wheel toward the drill.

EDD C. OLIVER.