US3266194A

US3266194A - Machine for grinding conical drill points

Info

Publication number: US3266194A
Application number: US301697A
Authority: US
Inventors: James C Winslow
Original assignee: WINSLOW PRODUCT ENGINEERING CO
Current assignee: WINSLOW PRODUCT ENGINEERING CO; WINSLOW PRODUCT ENGINEERING Corp
Priority date: 1963-08-05
Filing date: 1963-08-05
Publication date: 1966-08-16
Anticipated expiration: 1983-08-16

Description

g- 15, 1966 J. c. WINSLOW BQMJQQ MACHINE FOR GRINDING CONICAL DRILL POINTS Original Filed Dec. 21, 1961 5 Sheets-Sheet 1 ill Aug. 16, 1966 J c, w s ow 3,266,194

MACHINE FOR GRINDING CONICAL DRILL POINTS Griginal Filed Dec. 21. l9l 5 Sheets-Sheet 2 INVENTOR. (74/1755 6. %/v540n Aug. 16, 1966 c. WINSLOW 3,266,194

MACHINE FOR GRINDING CONICAL DRILL POINTS Original Filed Dec. 21, 1961 5 Sheets-Sheet 3 556W ae/A/p/A/a 62 645 a F/A/ZL GRIND/N6 POSITION o1fl& INVENTOR.

United States Patent 3,266,1M MACHINE FOR GRINDING CONECAL DRILL POHNTS James C. Winslow, Sierra Madre, Calif, assignor to Winslow Product Engineering Corporation, Arcadia, Calif., a corporation of California Continuation of application Ser. No. 161,175, Dec. 211, 1961. This application Aug. 5, 1% Ser. No. 301,697 17 Claims. (Cl. 51-94) This application is a continuation of my copending application Serial No. 161,175 filed December 21, 1961, and entitled Machine for Grinding Conical Drill Points, now abandoned.

This invention relates generally to drill pointing machines and, particularly, to an improvement in the drill pointing machine disclosed in US. Patent No. 3,040,480 issued June 26, 1962, for Drill Pointer, for adapting the latter to grinding so-called conical drill points.

The drill pointing machine in the above patent is provided with a frame on which is mounted a support for the drill to be pointed and a rotary grinding wheel having a beveled peripheral grinding surface terminating at one side face of the wheel in a circular grinding edge. This drill support is synchroniously oscillated and reciprocated in such a way that the tip of the drill in the support is periodically moved across the grinding surface in contact with the latter with a compound motion involving axial movement of the tip toward the grinding surface and simultaneous lateral movement of the tip toward and finally across the grinding edge. The drill is rotated in the support in synchronism with oscillation and reciprocation of the support. These several motions of the drill tip are so timed and the beveled peripheral grinding surface is disposed at such an attitude that the leading edge of each land is ground to the proper tip angle and the land, behind the leading edge, is relieved or hollow ground as the tip moves across the circular grinding edge of the grinding wheel to provide the finally sharpened drill with a so-called undercut drill tip.

While an undercut drill tip of this character has been found to be superior in many drilling operations, so-called conical drill tips are required in certain other drilling operations and/or are preferred by many drill users. A conical drill point is well known in the drilling art and is one in which the tip angle progressively increases from the leading edge of each land on the drill to the trailing edge of each land to provide the drill with the proper relief. The drill tip is not hollow ground or relieved as are the undercut drills described above.

A general object of this invention is to provide an improvement in the drill pointing machine of the aforementioned patent for adapting the latter to grinding so called conical drill points.

A more specific object of the present invention is to provide a drill pointing machine of the character described having a modified drill support which introduces a rocking motion to the drill being ground, whereby the angle between the drill axis and the grinding surface is progressively changed during movement of the drill tip across the surface to obtain a non-undercut, conical drill point.

A further object of the invention is to provide a drill pointing machine of the character described which can be used to grind either undercut or conical drill points.

Other objects, advantages, and features of the invention will become readily apparent as the description proceeds.

Briefly, the objects of the invention are attained by providing a drill pointing machine equipped with an improved drill support having a first part mounted on the machine frame for oscillation on and reciprocation along a first axis, a second part pivotally supported on the first 3,26%,194 Patented August 16, lghfi part for rocking on a second axis transverse to the first axis, a rotary drill chuck on the second part for gripping the drill to be pointed and rotating the drill on an axis approximately coincident with the axis of the drill and transverse to and offset from both said first and second axes, and means for synchronously oscillating and reciprocating the support and causing the second part to rock on its second axis in such a way that the rotating drill tip is moved along a defined path. Also mounted on the frame is a grinding wheel having a grinding surface positioned to contact the tip of the drill during movement of the tip from one point to another point along its defined path. The several motions of the drill tip are timed so that the lands of the drill are ground successively with the leading edge of each land initially contacting the grinding surface at a predetermined angle between the axis of the drill and the grinding surface to provide the correct tip angle at the leading edge. During subsequent movement of the drill between said points along the path and across the grinding surface, the drill is r0- tated to bring successive trailing portions of each land into contact with the grinding surface and the angle between the axis of the drill and the grinding surface is progressively changed to progressively increase the tip angle ground on the drill toward the trailing edge of each land.

A better understanding of the invention may be had from the following detailed description thereof, taken in connection with the annexed drawings, wherein:

FIG. 1 is a view of the present drill pointing machine illustrating the improved drill support of the machine partially in vertical section and diagrammatically illustrating the mechanism for moving the support;

FIG. 2 is a section taken along line 2-2 in FIG. 1, with one of the diametrically opposed chucking cams and grooves rotated through to appear in the plane of this section;

FIG. 3 is an enlarged section taken along line 33 in FIG. 1;

FIG. 4 is an enlarged section taken along line 44 in FIG. 1;

FIG. 5 is an enlarged section taken along line 55 in FIG. 2;

FIG. 5a is an enlarged section taken along line Sta-5a in FIG. 5;

FIG. 6 illustrates the manner in which the angle of the drill being pointed changes during the grinding operation of the machine; and

FIGS. 7 through diagrammatically illustrate the motions of the drill support which occur during the grinding operation of the present machine.

The drill pointing machine 10 illustrated in these drawings comprises a frame 12 (FIG. 1) mounting a drill sup port 14. This drill support includes a part 116 having a vertical tubular post 18 which is supported for rotation and axial movement on the frame 12.- Bolted to the upper end of the post 18 is a bracket or yoke part 20 having vertical,

upstanding arms

22 and 24. Located between these bracket arms is a second part 26 of the dnil l support 14. Part 26 is provided with two

bosses

28 and 30 opposite the

bracket arms

22 and 24, respectively, having conical sockets 3 2. These sockets receive the conical ends of a pair of

pivots

34 and 36 carried by the

bracket arms

22 and 24, respectively. Part 26 is, therefore, supported on part 16 for pivoting on an axis 38. This axis intersects the axis 40 of post 18 at 42 and is normal to the axis 40. Axis 40 is vertical when the machine is upright.

Rotatably supported on part 26 of the drill support 14 is a rotary drill chuck 44. This rotary chuck is contained within a recess 4-6 (FIG. 2) opening through one side of the part 26 and, in operation of the drill pointer, ro-

fates a drill to be pointed Within a bushing 48 fixedly mounted on the part 26. The axis of this bushing is disposed in a plane normal to the pivot axis 38 of part 26 and parallel to but offset from the axis 40 of post 13. Bushing 48 is externally tapered and held within a bushing adapter 52 bolted to the part 26. The bushing is held in the adapted 52 by means of a lock screw 54 releasably engageable in an external circumferential slot 56 in the bushing. The drill bushing 48 can thus be removed for replacement by a bushing of different size or by a new bushing by loosening the lock screw 54.

Rotary chuck 44 comprises a worm whee-l 58 which is rotatably supported on an internal cylindrical shoulder 60 on part 26 centered on the axis 50 of bushing 48. Fixed to this worm wheel by screws 62 are a circular plate 64 and a generally cylindrical chuck adapter 66. Chuck adapter 66 is formed with a central bore 68 centered on the axis 50 of the bushing 48 and with two generally radial grooves 70 of rectangular cross section at diametrically opposite sides of and opening to the bore 68 (see FIG. 5 Grooves 70 are closed by the circular plate 64 to form two rectangular guideways in which are slidably fitted rectangular chucking earns 72. It should be noted that the diametrically opposed. grooves 70 and the chucking cams 72 therein are shown in their actual relative positions in FIG. 5, but that in FIG. 2, in order for a groove and chucking cam to be seen therein, the plane of the section has been rotated through 90 about axis 50. That is to say, contrary to the conventionalized illustration of FIG. 2, there are two grooves 70' and chucking cams 72 in diametrically opposed position, as in FIG. 5; and there are actually two later-mentioned diametrically opposed ball plungers 104, also as shown in FIG. 5, one of these being replaced by a groove 70 and chucking cam 72 in FIG. 2. The chucking earns 72 are transversely slit, as illustrated, to afford them with a degree of axial resiliency. Slidably fitted within the central bore 68 in the chuck adapter 66 are two cooperating chuck jaws 74 having opposing semicircular grooves which cooperate to define a circular opening 76 through the chuck jaws approximately on the axis 50 of the drill bushing 48. A retaining ring 78 within an internal annular groove in the chuck adapter 66 retains the chuck jaws 74 in the bore 68 of the chuck adapter.

The flat, opposing faces of the chuck jaws 74 are disposed in a plane normal to the direction of radial movement of the chucking earns 72. Accordingly, the two chuck jaws are urged toward one another, to grip the shank of a drill extending through the chuck jaw opening 76 in the drill bushing 48, by inward movement of the chucking cams 72. The two chucking cams 72 are forced inwardly against the chuck jaws to close the latter, as follows: Slidahly fitted on the outside of the chuck adapter 66 and Within a cylindrical flange 80 on the worm wheel 58 is a chucking sleeve 82. This chucking sleeve is provided with an internal beveled camm-ing surface 84 which engages cooperating inclined camming surfaces 86 on the outer ends of the chucking earns 72. Accordingly, forward movement of the chucking sleeve 82 in part 26 (i.e., upward movement of the chucking sleeve 82 as the latter is viewed in FIG. 2), forces the chucking earns 72 radially inwardly against the chuck jaws 74.

Bolted to the lower face of part 26, as the latter is viewed in FIG. 2, are a cylinder 88 in the form of a ring of rectangular cross section and an annular end plate 90. End plate 90 is formed with an inner coaxial, cylindrical flange 02 between which and the inner surface of ring 88 is formed an annular hydraulic cylinder 94. Slidable in this cylinder is an annular piston 96. Chucking sleeve 82 and piston 96 are connected 'by a ball bearing 98 which causes the chucking sleeve 82 to move axially with the piston 06 and permits rotation of the chucking sleeve with respect to the piston.

During operation of the machine, hydraulic fluid under pressure is delivered from a source in the frame 12, to

be discussed shortly, through a hose 100 to urge the piston 96, and, therefore, the chucking sleeve 82, forwardly in part 26 and thereby close the chuck jaws 74. The chucking sleeve 32 and the piston 96 are returned by a normally conical spring 102 (substantially flat in the position of FIG. 2) positioned between the end face of the chucking sleeve 82 and the worm wheel 58 to relieve the pressure of the chucking earns 72 against the chuck jaws 74. In order to assure separation of the chuck jaws when the clamping pressure of the chuckin-g cam against the chuck jaws is relieve-d by retraction of the chucking sleeve 82 under the action of the conical spring 102, the chuck adapter 66 is provided with two spring-urged ball plungers 104 contained in two diametrically opposed bores 106 in the chuck adapter 66 in line with the separation between the chuck jaws. The edges of the chuck jaws are beveled, as illustrated at 108 in FIG. 5, and the ball plungers 104 are urged between these beveled edges to earn the chuck jaws apart. As shown in FIG. 5a, the beveled edges 108 extend for only a portion of the length of the chuck jaws and provide shoulders 110 at their inner ends which engage the ball plungers 104 to limit insertion of the chuck jaws into the bore 68 in the chuck adapter. Hydraulic and dirt seals are placed in the rotary chuck structure, as shown.

From this description, it is evident that when hydraulic fluid under pressure is admitted to the chuck cylinder 94, with a drill positioned in the chuck, the drill shank is gripped by the chuck jaws 74. Rotation of the worm wheel 58 then rotates the drill in the drill bushing 48 and on an axis, i.e., axis 50 of the drill bushing 48, coincident with the axis of the drill. Worm wheel 58 is driven in rotation by a worm 112 meshing with the worm wheel. Worm 112 is rotatably supported in part 26 and axially restrained by bearings 114. Extending axially through the post 18 of the drill support 14 is a drive shaft 116. The upper end of this drive shaft is drivably connected to the worm 112 by a universal joint 11%. The intersection of the pivot axes of this universal joint is coincident with the intersection 42 of the pivot axis 38 of part 26 on part 20 and the axis 40 of the post 18. The universal joint 11%, therefore, accommodates pivoting of part 26 about its pivot axis 38 while the worm 112 is being driven by the drive shaft 116 to rotate the chuck 44.

Bolted to the bracket arm 22 on the pivot bracket 20 of drill support part 16 is a bracket 120 which parallels the plane of the

pivot bracket arms

22 and 24 and confronts a projecting arm 122 (FIG. 4) on the drill support part 26. Arm 122 is bored at 124 to form a seat for one end of a compression spring 126. The other end of spring 126 engages in a bore 128 in bracket 120 and seats against the end of a spring-retainer bolt 130 threaded in the bore 128. Spring 126 urges the drill support part 26 in one direction on its pivot axis 38. Pivoted on the upper end of the pivot bracket arm 22 for swinging in a plane parallel to the plane of the

pivot bracket arms

22 and 24 is a stop bracket 132. This stop bracket has an arm 134 engageable by an adjustable stop screw 136 threaded in a boss 138 on the drill support part 26. Engagement of the stop screw 136 with the stop bracket arm 134 limits pivoting of the drill support part 26 under the action of the compression spring 126. Stop screw 136 is adjusted so that when it engages stop bracket arm 134, the axis 50 of the fixed drill bushing 48 is normal to a plane containing the pivot axis 33 of part 26 and the axis 40 of post 18. The reason for this will be described shortly.

Within the frame 12 of the machine, adjacent the lower end of the post 18 of drill support part 16, are means 140 (FIG. 1) for synchronously oscillating the drill support 14 on the axis 40' of post 18, reciprocating the drill support along this axis, and rotating the rotary chuck 44 through the drive shaft 116. This means is iden tical to that disclosed in the aforementioned US. Patent No. 3,040,480 and, for this reason, has been only schematically illustrated and will only be briefly described here in. Means 148 comprises two

disc cams

142 and 144 driven in synchronism from a motor 146. The peripheral cam surface of cam 142 is engaged by a cam follower 148 on one end of a bell crank 150. The other end of the bell crank 158 engages an abutment 152 on the lower end of the post 18. The cam 142 is shaped to rock the bell crank lever 150 in one direction on its pivot axis during rotation of the cam and thereby rotate the drill support post 18 in one direction on its axis 48. A spring 154 urges the post 18 in the opposite direction on its axis 46 so that during continuous rotation of the cam 142 by the motor 146, the post 18, and, therefore, the entire drill support 14, is oscillated on the axis 48.

Cam 144 engages a cam follower 156 intermediate the ends of an arm 158 which is pivoted at one end on a vertically shiftable rod 161], as indicated at 160a. Rod 160 occupies the position shown during grinding operations and is shiftable downwardly from that position by a hydraulic drill support elevating mechanism 16Gb. When rod 160 is shifted downwardly, arm 158 rocks on the cam 144, about the cam follower 156 as a center, and thereby elevates the drill support 14. The other end of arm 158 forms a fork which carries rollers 162 (only one shown) on which the post 18 is rotatab-ly supported. The peripheral cam surface of cam 144 is shaped to rock the arm 158 in one direction on its pivot axis to elevate the post 18. The post is returned downwardly under the action of its own weight.

Motor 146 drives the rotary chuck drive shaft 118 through a drive connection indicated at 164 and the

cams

142, 144 through a connection 165. During operation of the motor 146, then, the

cams

142 and 144 and the drive shaft 118 are driven in unison to synchronously oscillate and reciprocate the drill support 14 on the axis and rotate the chuck 44.

Mounted on the front side of the pivoted drill support part 26 (i.e., the left-hand side in FIG. 3) at a position some distance above and to the right of the .drill bushing axis 50, as the machine is viewed in FIG. 1, is a cam follower 166. Rigidly mounted on the machine frame 12 in front of the part 26 and in line with the cam follower 166 is a cam 168. The vertical edge face 178 of this cam facing the drill support 14 forms a cam surface parallel to the oscillation and reciprocation axis 40 of the drill support and engageab-le by the cam follower 166.

Rotatably mounted on the machine frame '12 at the forward side of the drill support 14, for turning on an axis parallel to the oscillation and reciprocation axis 48 of the drill support 14 (i.e., a vertical axis), is a rotary grinding wheel 172 having a coaxial beveled peripheral grinding surface 172a terminating in a circular edge 172b. This grinding wheel and the drill support 1 4 are so relatively disposed that in one angular position of the drill support on its oscillation and reciprocation axis 40 (i.e., the angular position shown in FIGS. 2, 7 and 9a) the axis of the drill support bushing 48 is coplanar with and intersects the rotation axis of the grinding wheel at right angles. In this angular position of the drill support, hereinafter referred to as its initial angular position, the cam follower 1166 engages the cam surface 170, and the axis 50 of the drill support bushing 48 is parallel to the plane of the grinding wheel and normal to a plane containing the oscillation and reciprocation axis 48 and the rocking axis 38 of part 26.

From the description thus far, it is evident that when the drill support 14 is reciprocated on the axis 40 by rotation of the cam 144, the cam follower 166 on the drill support slides up and down the cam surface 178. Further, referring to FIGS. 8a, 8b, 9a, 912, 10a and 1012, it is evident that when the drill support .14 swings in a clock- Wise direction (as the drill support is viewed from above as in FIGS. 8a, 9a and 10a) from its initial angular position of FIG. 9a, the cam follower 166 is held against the cam surface 178 by action of the biasing spring 126 for drill support part 26 so that the latter part rocks in a clockwise direction on its pivot axis 38, as it is viewed in FIG. 8b. Similarly, when the drill support 14 swings in a counterclockwise direction on its axis 40, from its initial angular position of FIG. 9a, engagement of the cam follower 166 with the cam surface 170 causes the part 26 of the drill support to rock in a counterclockwise direction on its pivot axis 38, as illustrated in FIG. 10b. Thus, during continuous oscillation of the drill support by rotation of the cam 142, part 26 of the drill support rocks back and forth on its pivot axis 38 through an angle on each side of its angular position of FIG. 9a. The drill .at the same time rocks through an angle of a on each side of the vertical axis 40 of the drill support 14. As mentioned earlier, the universal joint 118 between the drill chuck drive shaft 116 and the drill chuck drive worm 112 permits part 26 of the drill support to thus rock back and forth on its axis 38.

Referring to FIG. 1, it will be seen that when the drill support r14-is oscillated on its axis 40, to cause rocking of the drill support part 26 on its pivot axis 38, the rocking motion thereby imparted to the axis 50 of the drill support bushing 48, and, therefore, to the axis of a drill in the bushing, effectively occurs about an effective rocking axis 174 passing through the intersection point 42 of the

axes

38 and 40 and of the pivot axes of the universal joint 118 and through the point of contact of the cam 166 with the cam surface 170. Reciprocation of the drill support 14 by rotation of the cam 144, simultaneously with oscillation of the drill support, obviously causes vertical translation of the rocking axis 174.

The operation of the illustrated drill pointing machine will now be described with reference primarily to FIGS. 7 through 10b.

Prior to actual grinding operation of the machine, the drill support elevation mechanism 1611b is actuated to shift the rod downwardly and thereby elevate the drill support 14 to its loading position of FIG. 7. In this position, the drill support occupies its initial angular position referred to earlier and the axis 50 of the drill support bushing 48 is located above the upper surface of the grinding wheel 172. A drill D to be pointed is now inserted, tip first, through the released chuck jaws 74 and the bushing 48 from the rear to engage the drill tip with a drill locator 176 on the machine frame 12. This locator positions the drill D in a predetermined angular position and a predetermined axial position in the drill support 14. Hydraulic fluid under pressure is now admitted to the chuck cylinder 94 to effect clamping of the drill shank by the chuck jaws 74. The drill support elevating means 16012 is now operated to raise the drill support elevating rod 160 and thereby lower the drill support 14 toward its grinding position, and the motor 146 is simultaneously energized. These operations are effected automatically by a control system schematically illustrated at 176 and described fully in the aforementioned patent.

Energizing of motor 146 drive the chuck 44, and, therefore, the drill D, in rotation on the axis 50 and synchronously rotates the cams v142 and 144. Cam 142 is so shaped and its rotation is so tirned that as the drill support 14 is lowered from its loading position of FIG. 7 toward its phantom line position of FIG. 8b, wherein the drill tip just clears the grinding wheel, the drill support 14 is rotated in the clockwise direction on its oscillation axis 46 to incline the drill tip downwardly with respect to the plane of the grinding wheel. Continued rotation of cam 142 now causes counterclockwise rotation of the drill support part 26 on its oscillation axis '40, and, therefore, counterclockwise rocking of drill support part 26 on its rocking axis 38. Since the drill D is located between the rocking axis 38 and the cam follower .166, this counterclockwise rotation of the drill support 14 and *7 counterclockwise rocking of the drill support part 26 advances the drill tip toward and into contact with the grinding surface 172a. The above motions are so timed and the parts .are so positioned that the drill tip is advanced into initial contact with the grinding surface 172a FIGS. 8a, 8b) when the rotation axis 50 of the drill D is inclined downwardly toward the drill tip and at an initial predetermined angle to the grinding surface 172a.

The drill D is initially angularly positioned in the drill support 14 by drill locator 176 in such a way and its rotation is so timed that in the position of initial contact of the drill tip with the beveled grinding surface 172a, shown in FIG. 8b, the angular position of the drill on its axis is as shOWn in FIG. 80, wherein the leading edge of one land L of the drill is generally vertically disposed for initial contact with the grinding surface 172a. The angle of the beveled grinding surface 172a is such as to grind the appropriate tip angle on the leading edge of the land L when the drill axis is inclined at the aforementioned initial predetermined angle to the grinding surface.

After initial contact of the drill tip with the grinding surface 172a, in FIG. 8b, continued rotation of the

cams

142 and 144 imparts simultaneous continued counterclockwise rotation to the drill support 14 on its axis 40, and thereby continued counterclockwise rocking to part 2.6 on its axis 38, and upward movement of the drill support along its axis 40. These combined motions of the drill support are so timed that the drill support moves through its position of FIGS. 9a and 9b, wherein the axis 50 of the drill D is horizontal, to the final grinding position of FIGS. 10a and 10b, wherein the tip of the drill is inclined upwardly toward the drill tip with respect to the plane of the grinding wheel. The rotation of the drill D in the drill support 14 which occurs simultaneously with the above motions of the drill support is so timed that successive portions of the land L of the drill are rotated into the vertical plane (i.e., the vertical plane passing through the longitudinal axis of the drill) for contact with the grinding surface 172a. In FIG. 90, for example, an intermediate portion of the drill land L is vertically disposed for contact with the grinding surface 172a and in FIG. 10c, the extreme trailing edge of the land L is rotated into the vertical plane for contact with the grinding surface.

From the above discussion, it is evident that as the drill is rotated to bring successive portions of the land L into the vertical plane for contact with the grinding surface 172a, the angle between the axis of the drill and the grinding surface is changed, by rotation of the drill support on its axis 40, in a direction such that a progressively greater tip angle is ground on the drill toward the trailing edge of the land.

The counterclockwise rocking of the drill support part 26 on its axis 38 and the upward translation of the drill support 14 along its axis 40 which occur during the above grinding of the drill tip result in movement of the latter, as it is being ground, across the grinding surface 1721a and toward the grinding wheel edge 1721) to the final grinding position of FIGS. 10a and 10b.

Cams

142 and 144 are shaped so that after the final grinding position of FIGS. 10a and 10b is reached, the drill support is rotated in a clockwise direction on its axis 40 and simultaneously lowered to return the drill support through its phantom line position to its initial grinding position of FIGS. 8a and 8b in such a way that the drill tip remains out of contact with the grinding wheel until the initial grinding position is reached. Rotation of the drill in the drill support during return of the latter to its initial grinding position is so timed that when the latter grinding position is reached, the leading edge of the second drill land L is disposed for contact with the grinding surface 172a. At this time, the

cams

142 and 144 will have returned to their original positions to repeat the above grinding cycle for the second land of the drill, During the next following grinding cycle, the first drill land L is reground. This successive grinding of the drill lands is continued until 8 the drill tip is properly pointed. The drill support is then returned to its loading position of FIG. 7, the drill removed, and a new drill is inserted into the drill support.

It is now clear that during each pass of the drill tip past the grinding wheel 172, the drill tip is laterally moved across the grinding surface 172a toward the grinding wheel edge 172b, the drill synchronously rotated on its axis to bring successive portions of each drill land into contact with the grinding surface, and the angle of the drill axis is progressively changed in the manner illustrated in FIG. 6 to progressively increase the tip angle ground on each drill land toward the trailing edge of each land. These motions obviously generate a conical drill point.

During the above grinding operation, the stop bracket 132 is disposed in its phantom line retracted position of FIG. 1 to permit rocking of the drill support part 26 on its axis 38. When the stop bracket is disposed in its operative solid line position of FIG. 1, the drill support part 26 is retained in its upright position wherein the drill bushing axis 50 is normal to a plane containing the oscillation and reciprocation axis and the rocking axis 38. In this position of the drill support bracket, the machine is adapted for grinding the undercut drill points discussed in the aforementioned patent.

Clearly, therefore, the invention hereinbefore described and illustrated is fully capable of attaining the several objects and advantages preliminarily set forth.

I claim:

1. A drill pointing machine comprising a frame; a drill support on said frame including a first part mounted on the frame for oscillation on and reciprocating along a given axis, a second part pivotally supported on said first part for rocking on an axis transverse to said given axis, and a rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and transverse to said given axis and said pivot axis; means for synchronously oscillating and reciprocating said first part; cooperating engageable means on said frame and said second part for causing the latter to rock on said pivot axis between positions in which the drill axis is transverse to said given axis and in synchronism with oscillation and reciprocation of said first part, whereby the tip of the drill in said chuck moves along a defined path; a rotary grinding wheel on said frame having a coaxial grinding surface positioned to contact the drill tip during movement of the latter between a first point and a second point along said path and to clear the drill tip during movement of the latter along said path from said second point to said first point, said rotation axis being disposed at a predetermined angle to said grinding surface when the drill tip is at said first point and rocking of said part on said pivot axis causing the angle between said rotation axis and said grinding surface to change during movement of the tip across the grinding surface to said second point; and means for rotating said chuck in synchronism with movement of the drill tip along said path.

2. A drill pointing machine comprising a frame; a drill support on said frame including a first part mounted on the frame for oscillation on and reciprocation along a given axis, a second part pivotally supported on said first part for rocking on an axis transverse to said given axis, and a rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and transverse to and offset from said given axis and said pivot axis; means for synchronously oscillating and reciprocating said first part; cooperating engageable means on said frame and said second part for causing the latter to rock on said pivot axis between positions in which the drill axis is transverse to said given axis and in synchronism with oscillation and reciprocation of said first part, whereby the tip of the drill in said chuck moves along a defined path; a rotary grinding wheel on said frame having a coaxial grinding surface positioned to contact the drill tip during movement of the latter between a first point and a second point along said path and to clear the drill tip during movement of the latter along said path from said second point to said first point, said rotation axis being disposed at a predetermined angle to said grinding surface when the drill tip is at said first point and rocking of said part on said pivot axis causing the angle between said rotation axis and said grinding surface to change during movement of the tip across the grinding surface to said second point; and means for rotating said chuck in synchronism with movement of the drill tip along said path.

3. A drill pointing machine comprising a frame; a drill support on said frame including a first part mounted on the frame for oscillation on and reciprocation along a given axis, a second part pivotally supported on said first part for rocking on an axis transverse to said given axis, and a rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and disposed in a plane normal to said pivot axis and offset from said given axis and said pivot axis; means for synchronously oscillating and reciprocating said first part; cooperating engageable means on said frame and said second part for causing the latter to rock on said pivot axis between positions in which the drill axis is transverse to said given axis and in synchronism with oscillation and reciprocation of said first part, whereby the tip of the drill in said chuck moves along a defined path; a rotary grinding wheel on said frame having a coaxial grinding surface positioned to contact the drill tip during movement of the latter between a first point and a second point along said path and to clear the drill tip during movement of the latter along said path from said second point to said first point, said rotation axis being disposed at a predetermined angle to said grinding surface when the drill tip is at said first point and rocking of said part on said pivot axis causing the angle between said rotation axis and said grinding surface to change during movement of the tip across the grinding surface to said second point; and means for rotating said chuck in synchronism with movement of the drill tip along said path.

4. A drill pointing machine comprising a frame; a drill support on said frame including a first part mounted on the frame for oscillation on and reciprocation along a given axis, a second part pivotally supported on said first part for rocking on an axis normal to said given axis, and a rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and disposed in a plane normal to said pivot axis and offset from said given axis and said pivot axis; means for synchronously oscillating and reciprocating said first part; a cam on said frame having a cam surface parallel to said given axis; a cam follower on said second part in a position offset from said pivot axis engageable with said cam surface during oscillation and reciprocation of said first part to cause rocking of said second part on said pivot axis in synchronism with oscillation and reciprocation of said first part, whereby the tip of a drill in said chuck moves along a defined path; a rotary grinding wheel on said frame having a coaxial grinding surface positioned to contact the drill tip during movement of the latter between a first point and a second point along said path and to clear the drill tip during movement of the latter along said path from said second point to said first point, said rotation axis being disposed at a predetermined angle to said grinding surface when the drill tip is at said first point and rocking of said part on said pivot axis causing the angle between said rotation axis and said grinding surface to change during movement of the tip across the grinding surface to said second point; and means for rotating said chuck in synchronism with movement of the drill tip along said path.

5. A drill pointing machine comprising a frame; a drill support 011 said frame including a first part mounted on the frame for oscillation on and reciprocation along a given axis, a second part pivotally supported on said first part for rocking on an axis transverse to said given axis, and a rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and transverse to said given axis and said pivot axis; means for synchronously oscillating and reciprocating said first part; cooperating engageable means on said frame and said second part for causing the latter to rock on said pivot axis between positions in which the drill axis is transverse to said given axis and in synchronism with oscillation and reciprocation of said first part, whereby the tip of the drill in said chuck moves along a defined path; a rotary grinding wheel on said frame having its axis of rotation parallel to said given axis and a peripheral grinding surface positioned to contact the drill tip during movement of the latter between a first point and a second point along said path and to clear the drill tip during movement of the latter along said path from said second point a) said first point, said l'Oll'iElrilOll axis 'being disposed at a predetermined angle to said grinding surface when the drill tip is at said first point and rocking of said part on said pivot axis causing the angle between said rotation axis and said grinding surface to change during movement of the tip across the grinding surface to said second point; and means for rotating said chuck in synchronism with movement of the drill tip along said path.

6. A drill pointing machine comprising a frame; a drill support on said frame including a first part mounted on the frame for oscillation on and reciprocation along a given axis, a second part pivotally supported on said first part for rocking on an axis transverse to said given axis,

and a rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and transverse to said given axis and said pivot axis; means for synchronously oscillating and reciprocating said first part; cooperating engageable means on said frame and said second part for causing the latter to rock on said pivot axis between positions in which the drill axis is transverse to said given axis and in synchronism with oscillation and reciprocation of said first part, whereby the tip of the drill in said chuck moves along a defined path; a rotary grinding wheel on said frame having its axis of rotation parallel to said given axis and a beveled peripheral grinding surface positioned to contact the drill tip during movement of the latter between a first point and a second point along said path and to clear the drill tip during movement of the latter along said path from said second point to said first point, said rotation axis being disposed at a predetermined angle to said grinding surface when the drill tip is at said first point and rocking of said part on said pivot axis causing the angle between said rotation axis and said grinding surface to change during movement of the tip across the grinding surface to said second point; and means for rotating said chuck in synchronism with movement of the drill tip along said path.

7. A drill pointing machine comprising a frame; a rotary grinding wheel on said frame having a beveled peripheral grinding surface terminating at one side face of the wheel in a circular grinding edge; a drill support on said frame including a first part mounted on the frame for oscillation on and reciprocation along a given axis parallel to the rotation axis of said grinding wheel, a second part pivotally supported on said first part for rocking on an axis intersecting and normal to said given axis, and s rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and disposed in a plane normal to said pivot :axis and offset from said given axis; means for synchronously oscillating and reciprocating said first part; a cam on said frame adjacent said grinding wheel having a cam surface parallel to said given axis; a cam follower on said second part engageable with said cam surface to cause rocking of the latter on said pivot axis between a first position in which said rotation axis is disposed at a first predetermined angle with respect to a plane normal to said given axis and a second position in which said rotation axis is disposed at a second predetermined angle with respect to said latter plane, whereby the tip of a drill in said chuck moves along a defined path during oscillation and reciprocation of said first part, said beveled grinding surface being disposed to contact the drill tip during movement of the latter between a first point along said path wherein said rotation axis is disposed at one angle with respect to said peripheral grinding surface and a second point along said path wherein said rotation axis is disposed at another angle with respect to said grinding surface, whereby the angle between said rotation axis and said grinding surface changes during movement of the drill tip across said grinding surface between said first point and said second point along said path; and means for rotating said chuck in synchronism with movement of the drill tip along said path.

8. A drill pointing machine comprising a frame; a rotary grinding wheel on said frame having a beveled peripheral grinding surface terminating at one side face of the wheel in a circular grinding edge; a drill support on said frame including a first part mounted on the frame for oscillation on and reciprocation along a given axis parallel to the rotation axis of said grinding wheel, a second part pivotally supported on said first part for rocking on an axis intersecting and normal to said given axis, and a rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and disposed in a plane normal to said pivot axis and offset from said given axis; means for synchronously oscillating and reciprocating said first part; a cam on said frame adjacent said grinding wheel having a cam surface parallel to said given axis; a cam follower on said second part engageable with said cam surface to cause rocking of the latter on said pivot axis between a first position in which said rotation axis is disposed at a first predetermined angle with respect to a plane normal to said given axis and a second position in which said rotation axis is disposed at a second predetermined angle with respect to said latter plane, whereby the tip of a drill in said chuck moves along a defined path during oscillation and reciprocation of said first part, said beveled grinding surface being disposed to contact the drill tip during movement of the latter between a first point along said path wherein said rotation axis is disposed at one angle with respect to said peripheral grinding surface and a second point along said path wherein said rotation axis is disposed at another angle with respect to said grinding surface, whereby the angle between said rotation axis and said grinding surface changes during movement of the drill tip across said grinding surface between said first point and said second point along said path; and means for rotating said chuck in synchronism with movement of the drill tip along said path including a rotary shaft extending through said first part on said given axis, rotary means in said second part for driving the chuck in rotation, and a universal joint between said shaft and said rotary means located at the intersection of said given axis and said pivot axis.

9. The subject matter of claim 7 including means on said drill support for releasably retaining said second part in a position on said first part wherein said rotation axis is normal to a plane containing said given axis and pivot axis.

10. A drill pointing machine comprising a frame; a drill support on said frame including a first part mounted on said frame for oscillation on a first axis, a second part pivotally supported on said first part for rocking on a second axis transverse to said first axis, and a rotary drill chuck on said second part for gripping a drill to be pointed and rotating the drill on an axis coincident with the axis of the drill and transverse to said first and second axes; means for oscillating said first part on said first axis; means for rocking said second part on said second axis in synchronism with oscillation of said first part; means for rotating said drill chuck in synchronism with said oscillation and rocking, said oscillation, rocking, and r0 tation of said drill chuck in synchronism causing the tip of a drill in the chuck to move along a prescribed path as it rotates and the angle between the drill axis and the direction line of movement of the drill tip to change as the tip moves between a first position and a second position along said path; and a grinding wheel having a coaxial grinding surface disposed to be engaged by the drill tip during movement of the latter between said first and second positions.

11. The subject matter of claim it wherein said means for rocking said second part of said drill support on said second axis comprises means on said second part offset from said second axis and cooperating means on said frame engageable by said last-mentioned means upon oscillation of said second part toward said grinding wheel to rock said second part in one direction on said second axis against an opposing force for returning said second part toward said grinding wheel.

12. In a pointing machine for a fluted drill whose point has lands provided with a leading cutting edge and a trailing edge, the combination of: a drill chuck adapted to receive and hold a drill with the forward end thereof protruding a given distance from the chuck; a drill chuck holder receiving and supporting said chuck for rotation on the axis of said drill; a frame; means supporting said chuck holder from said frame for swinging movement about an effective axis which is spaced to one side of the drill axis and which is in a plane that is perpendicular to the drill axis in all positions of the drill and is spaced rearward of the drill point; means for rocking said chuck holder about said effective axis through a predetermined angle, whereby the point of the drill in the chuck undergoes movement in a prescribed path; a grinding wheel having an operative grinding surface area that is contained at least in part in a plane making an acute angle with said effective axis, said operative grinding surface area being engaged and swept by said drill point travelling generally forwardly and laterally in said movement; and means for rotating the drill through a portion of a turn simultaneously with said movement of said point of said drill from a beginning position in which a leading edge of a land on the drill point is in contact with the grinding surface area to a final position in which the trailing edge portion of said land is in contact with said grinding surface area.

13. The subject matter of claim 12, wherein said means supporting said chuck holder for swinging movement about said effective axis comprises a support rotatable on said frame about a fixed axis, and means mounting said chuck holder on said support for pivotal movement about a second axis intersecting said fixed axis at right angles thereto, the drill axis being offset from both said fixed axis and said second axis, and said second axis being contained in a plane at right angles to the drill axis.

14. The subject matter of claim 13, including also means synchronized with the rocking of said chuck holder and acting simultaneously with said movement of said drill point in said prescribed path for moving said support axially along said fixed axis.

15. The subject matter of claim 13, in which said grinding wheel surface area is on a beveled, circular periphery of said wheel and wherein said wheel has an axis substantially parallel to said fixed axis.

16. The subject matter of claim 15, wherein said rotary grinding wheel has a beveled, peripheral grinding surface converging toward the wheel axis as the surface approaches one side face of the wheel, and wherein said chuck holder is constructed and arranged to position said drill first with its axis at a predetermined angle to said beveled grinding surface and at an acute angle to one side of the plane of said side face of said grinding wheel, and thereafter to cause relative movement of the drill tip diagonally along and across said beveled grinding surface toward said side face and through an intermediate position in which the drill axis is parallel to said side face, and finally to a position in which the drill axis is at a second predetermined angle to said grinding surface and at an acute angle to the opposite side of the plane of said face.

17. The subject matter of claim 13, wherein the means for rotating the drill comprises a rotary shaft extending through said support along said fixed axis, rotary means in said chuck holder for driving said chuck in rotation, and a universal joint between said shaft and said rotary means located at the intersection of said fixed axis with said second axis.

References Cited by the Examiner HAROLD D. WHITEHEAD, Primary Examiner.