US3056237A

US3056237A - Drill grinding machine

Info

Publication number: US3056237A
Application number: US49790A
Authority: US
Inventors: Sr Anthony T Comiskey
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-08-15
Filing date: 1960-08-15
Publication date: 1962-10-02
Anticipated expiration: 1979-10-02

Description

OCL 2, 1962 A. T. coMlsKEY, sR 3,056,237

DRILL GRINDING MACHINE 3 Sheets-Sheet l Filed Aug. l5, 1960 'E' jfl/wf; M, MEV/59M Oct' 2, 1962 A. T. coMlsKEY, sR 3,056,237

DRILL GRINDING MACHINE Filed Aug. l5, 1960 3 Sheets-Sheet 2 OCU 2, 1962 A. T. coMlsKEY, SR 3,056,237

DRILL GRINDING MACHINE Filed Aug. l5. 1960 3 Sheecs-SheevI 3 United States Patent Utilice 3,056,235? Patented Oct. 2, 1962 3,056,237 DREI. GRINBING MACIHNE Anthony T. tConisl-zey, Sr., 6134 Cornelia Ave., Chicago, lll. Filed Aug. 15, 1960, Ser. No. 49,790 Claims. (Cl. :5l- 33) The invention relates lgenerally to the grinding of drills. More particularly, the invention relates to an improved drill point formation. The invention also particularly relates to apparatus adapted for sharpening drills with either a conventional point or with an improved drill point formation, as `disclosed herein.

The problem of accurately sharpening drills to obtain optimum performance has existed for many years. In most cases, drills are still manually held against a grinding wheel when sharpened. It is only natural that the formation of the drill points thus produced will vary depending upon the person sharpening the drill as well as from drill to drill and hour to hour. The vast majority of drill points thus sharpened will not be sharpened for optimum performance. Accordingly, one of the principal objects of the invention is the provision of apparatus for reliably sharpening and resharpening drills to obtain the optimum in drill point formation.

Another problem which has existed for a long time in machine shops and elsewhere relates to the break-through of a drill when passing transversely through a cylindrical rod and the frequently occurring chattering which takes place. This chattering is symptomatic of excessive wear on the drill and of tearing of the metal in the rod, which tearing produces a hole having a rough entrance rather than a smooth entrance.

This problem can be overcome and, at the same time, the power required for drilling operations can be reduced when using a drill having a point formed in accordance with the invention. Accordingly, an object of the invention is the provision of an apparatus for grinding drill points with the novel point formation disclosed herein.

Other objects and advantages of the invention will become apparent by reference to the following description and the accompanying drawings in which:

FIGURE 1 is a plan view of an apparatus embodying various features of the invention for sharpening drill point formations;

FIGURE 2 is an end view of a conventional drill point formation;

FIGURE 3 is an end view of a drill point formation formed in accordance with the invention;

FIGURE 4 is a fragmentary side View of the drill point formation shown in FIGURE 3, the View being taken along line 4 4;

j FIGURE 5 is a side elevational View of the apparatus shown in FIGURE l;

FIGURE `6` is a sectional View of the apparatus, taken along the line 6 6 in FIGURE l, with the drill holder rotated in order to more clearly show the construction; and

FIGURE 7 is a sectional View, taken along line 7-7 of FIGURE 5.

j For purposes of clarity in the description, a conventional drill point 2.7.1,` such as that shown in FIGURE 2, will first be briefly described, so as to permit orientation of the various parts of the drill with respect to the apparatus subsequently to be described. As shown, the drill point 21.is formed from a drill having a generally cylindrical body which includes a pair of spiralling, generally diametrically opposed flutes 23 and which is ground to provide a `generally conical formation including a pair of cutting edges or lips 25 and a central web 27 joining the cutting lips 25. Of course, the ground faces 29 of the drill point incorporate the usual clearance angle which is increased as the web is approached.

Conventionally pointed drills, such as shown in FIG- URE 2, as well as the drill point to be hereinafter disclosed, can be readily and repeatedly obtained by use of the apparatus shown in FIGURES l and 5 through 7. Basically, this apparatus comprises a universally adjustable holder 41 for clamping a drill 45 in a desired position, and a grinder 42 including a grinding wheel 43 carried for grinding action against the drill 45 by a mechanism which is operable to move the grinding wheel 43 along a predetermined path having components parallel to each of three planes disposed at right angles to each other, Le., a horizontal plane, a first vertical plane, and a second vertical plane perpendicular to said first Vertical plane, so as to sharpen the desired -drill point formation.

Considering the apparatus in greater detail, it comprises a base 47 (see FIGURES l and 5) including a generally rectangular plate 49 which is mounted in outrigger fashion on a pair of cross-members 51 and 52 supported at their opposite ends on four feet, feet 53, 55, and 57 being shown, each of adjustable length, which adjustability feature provides for leveling of the apparatus.

As shown best in FIGURES l and 5, the grinding wheel 43 is supported, in part, by a frame 61 (see especially FIGURE 5) carried pivotally by a stud 63|` which extends through one end of the plate y49 and constitutes a vertical axis for swinging the frame 61. The frame is generally U-shaped, having as seen best in FIGURE l, a pair of spaced

upright legs

64 and 65 which, adjacent their upper ends, are connected by a bolt 67 which serves as a horizontal pivot or axis for a sleeve 69 carried between the

legs

64 and 65. Fixed to the sleeve 69 in transverse relation thereto is a bar 71 which, in turn, has bolted adjacent its ends a pair of downwardly depending rods 73. Each rod 73 is connected at its lower end to a collar 75 which is fastened in surrounding relation to an elongated support beam 77 extending generally over the length of the plate 49. As will be explained, the support beam 77 carries the grinder 42.

From the structure thus far described, it will be seen that the support beam 77 is free to pivot about the stud 63 which acts as a vertical axis, thereby accommodating movement of any point on the support beam in a horizontal are. In addition, the support beam 77 is free to pivot about the bolt 67 which serves as a horizontal axis, thereby permitting movement of any point on the support beam in a vertical arc.

The support beam 77 is pivotally swung about a bolt 67, which serves as a horizontal axis, by a linkage 79 which interconnects the U-shaped frame 61 and an arbor 81 carried by the support beam 77 for transverse rotation thereto. More specifically, the arbor 81 is journalled in a bracket 83 fixed to the support beam 77 and has fixedly joined thereto at one end a first link 85 of the linkage 81. This link 85 rotates with the arbor 81, has a handle part 87 at its free end, and is swngably connected to one end of a second link 91 of the linkage 79 by a pivot 89 which is located intermediate the ends of the first link 85 and parallel to the horizontal bolt 67. This second link 91 is of adjustable length and is pivotally connected at its other end to adjacent the bottom of the leg 64 of the U-shaped frame 61 about a pivot 93 parallel to the horizontal bolt 67.

Thus, when the handle part 87 is rocked clockwise, as seen in FIGURE 5, the support beam 77 is swung clockwise about the horizontal pivot 67, i.e., generally downwardly. At the same time, the support beam 77 also swings counterclockwise, as seen in FIGURE l, about the stud 63 as a result of engagement of the other end of the support beam 77 with a camming member 101.

apenas? In this connection, there is mounted adjacent one corner of the plate 49 at the other end of the base, as seen especially in FIGURE 6, a stanchion 103 which, at its upper end, carries a support bracket 105 which is pivotable around a horizontally extending pivot 106 disposed longitudinally of the base plate 49. The support bracket 105 includes an arm 107 which is connected at one of its ends to the stanchion 103 and is joined at its other end to a generally quarter-round cylindrical section 109 having, at its lower end, a tangential extension 111 which is substantially horizontal. The cylindrical section 109 is mounted on the bracket 105 to position its axis horizontally and in longitudinal relation to the base plate 49.

The bracket 105 is swingable upwardly about the pivot 106 from a lower limiting position defined by engagement of the extension 111 of the cylindrical section 109 with the head of a post 113 carried by the base plate 49. In this regard, the post 113 includes a handle 115 which facilitates threading of the post 113 in and out of the base plate 49 to adjust the height of its head and thereby determine the lower limit of the possible pivotal movement of the bracket 105. Normally, the bracket is in this lower limiting position during grinding operations. The post 113 can be clamped with its head' located at any desired height by use of a locking nut 117 having a handle bar 119.

The cylindrical section of the bracket also includes a clamping means 121 (see especially FIGURE 5) by which the camming member 101 can be fastened to the bracket 105 for cooperation with a follower 123 at the free end of the support beam 77 so as to assist in determining the path of travel of the grinding wheel 43.

The camming member 1 in the disclosed construction takes the form of a short tube of non-circular, contiruous cross section, such as an oval, the inside wall surface of which constitutes a camming surface 125. The use of an oval shaped camming member 101 and the clamping means 121, as disclosed, permits mounting of the camming member 101 to the cylindrical section 109 in various positions so as to vary, as desired, the path of movement of the support beam 77.

In this latter regard, the support beam 77 is biased for engagement of the follower 123 at its free end with; the camming surface 125 `by connection to one end of a spring 127 which, at its other end, is connected to a fixedly upstanding extension 129 of the base leg 57.

From the foregoing description, it will be understood that as the support beam 77 is rotated by the linkage 79 through a vertical arc about its horizontal axis, i.e., the bolt 67, engagement of the follower 123 with the camming surface 125 during this movement causes concurrent horizontally swinging movement of the support beam 77 about its vertical axis, i.e., the stud 63. Specifically, when the handle part 87 is thrown forwardly, i.e., to the right in FIGURE 5, the support beam 77 will rock clockwise about its horizontal axis 67 and will swing to the left, as seen in FIGURE 6, i.e., counterclockwise about its vertical axis 63.

Thus, movement back and forth of the handle part 87 imparts compound movement to the support beam 77, together with the grinder 42, in each of the three planes mentioned previously, i.e., the grinder moves longitudinally of the base plate 49, transversely of the base plate, and vertically with respect to the base plate.

The grinder 42 is carried by the support beam 77, as will be explained, and comprises, as seen especially in FIGURE 1, a mounting plate 131 supporting an electrical motor 133 which is controlled through a switch box 135 carried on the support beam 77. Secured to the forward end of the rotor shaft 137 of the motor 133 is the grinding wheel 43 which can be of any conventional construction but which is preferably formed with an outwardly convex, radial cross section. The mounting plate 131 is fixedly secured to the transverse arbor 81 to locate the rotor shaft 137 in radially perpendicular relation to the axis of the transverse arbor 81. Thus, any abrasive plane, i.e., any plane tangential to the grinding wheel, is rotated about the arbor 81 incident to rotation of the arbor by movement of the handle part 87.

When the handle part 87 is swung clockwise, as seen in FIGURE 5, the grinder 42 also swings clockwise and, at the same time, is caused by the linkage 79 to move downwardly and toward the end of the base plate 49 about which the support beam 77 is pivoted, i.e., to the left in FIGURE 5, and is simultaneously caused to move to the left in FIGURE 6 by engagement of the follower 123 at the end of the support beam 77 with the camming surface 125. Thus, the grinding wheel 42 travels in a predetermined path around the end of the drill 45 clamped in the holder 41, which path will provide a tapering drill point with a clearance angle which increases toward the web of the drill point.

When the grinding wheel 43 has an outwardly convex radial cross section, the cutting edge of the resultant drill will, as shown in FIGURE 3, be concave in radial outline, i.e., will provide a concave outline when viewed along a line of sight generally normal to the margin of the fluted area adjacent the cutting edge. In addition, the use of such a grinding wheel 43 in combination with the described path of movement provides a drill point in which the web 27a (see FIGURE 2) is angularly spaced from the cutting edge at an angle which is less than the usual degrees and which approaches 90 degrees. This configuration results in a longer cutting edge 25a having a projection in a plane perpendicular to the axis of the drill approaching the length of the drill radius. Thus, the length of the cutting edge is increased in two ways, because of the arcuate form and because of the change in angle with respect to the web of the drill point. In addition, there is provided an undercut area in the iiute, indicated by the numeral 139 in FIG- URE 3, which area provides improved cutting characteristics at the end of the cutting lip adjacent the web. The undercut areas 139, as seen in FIGURE 2, extend inwardly toward the web 27a from a line 141 projecting in alignment with the cutting edges 25a when viewed along the axis of the drill. This configuration permits the portions of the web 27a next to the cutting edges 25a to cut through the material being drilled, rather than merely dragging behind the cutting lip, as in the usual drill point formation.

As noted, the drill 45 is xedly held by the holder 41 for grinding by the wheel 43. The holder is mentioned earlier is adjustably positionable to permit location of the end of the drill 45 in any relation to the path of movement of the grinding wheel 43 and is mounted on a bar 161 which extends from adjacent the other end of the plate 49, the bar 161 being fixed to the plate 49 for angular adjustment about a vertical axis by the bolted connection indicated by the numeral 163. Pivotally mounted adjacent the free end of the bar 161 is an upright post 165 which can be vertically adjusted and can be locked at any desired angular relation to the bar 161 by means of a locking nut 167. Also provided is an angularly graduated scale 169 fixed to the bar 161 and an indicator 171 which swings with the post 165.

The upper end of the post 165 is bifurcated to provide a trunnion 173 carrying a vise 175 on a horizontal pivot formed by a bolt 177. The vise 175 includes a rectangular block 179 which is generally square in transverse cross section and which is mounted on one edge on a bracket 181 extending into the trunnion in pivotal surrounding engagement to the bolt 177. Thus, the vise 175 can be positioned about a vertical axis by swinging either the mounting bar 161 or the post 165 and can be positioned at any angle to the horizontal by swinging the vise about the bolt 177. Locking of the vise 175 at any desired angle to the horizontal can be accomplished by tightening a nut 183 threaded on the end of the bolt 177 to clamp the bracket 181 tightly within the trunnion `173.

Seated on the upper faces of the block 179 is a pair of spaced bars 185 having aligned cross-shaped cross sections providing an upwardly facing V-shaped bed 187 (see especially FIGURE l) for receiving the drill 45 to be sharpened. The bars 185 are xedly retained on the block 179 by a pair of U clamps 189 (see FIGURE 6). The drill 45 is held in the bed 187 of the cross shaped bars 185 for grinding by a clamping block 191 and a U clamp 193 with the usual pressure screw 195.

Before fixed clamping in the vise 175, the drill 45 can be moved lengthwise of its axis and angularly rotated relative to its axis to present the point to be sharpened at any desired relation to the grinding wheel y43 for grinding action.

Lengthwise movement of the drill 45 in the bed 187 of the vise 175 is facilitated by an adjusting screw 197 which is threaded through an upright arm 199 extending from the rear of the block 179 and which includes at one end a drill engaging head -1 and, at the other end, a knurled knob 203. The adjusting screw 197 can be locked in any desired position by a wing nut 205 engageable against the upright arm v199.

Proper angular positioning of the drill 45 relative to its axis is facilitated by use of a feeler device 207 and a conventional tap wrench 209 which functions in cooperation with a guide device 211. The feeler device 207 constitutes a shaft 213 which is threaded in slightly offset, upright relation to the bottom of the V-shaped bed 187 through a bracket 215 projecting from the U-shaped clamp 193. The feeler shaft 213 is biased against unwanted rotation by a spring 217. In use, the drill 45 is rotated while loosely held in the vise 175 until the lower end of the feeler shaft 213 contacts the at margin of the flute adjacent the cutting edge. In this position, the cutting edge lies substantially in a horizontal plane. When thus located, the handle `bars 219 of the tap wrench 209 are manipulated to tightly grip the drill 45, the guide device 211 is adjusted to engage one of the handle bars 219' of the tap wrench 209, and the drill 45 is tightly clamped in the vise 175 by the clamp 193 and clamping block 191.

As seen especially in FIGURES 6- and 7, the guide device 211 is carried on a xed arm 221 extending from the trunnion 173 and includes a link 223 of adjustable length which is carried for angular adjustment on a threaded stud 225 extending lfrom the arm 22.1 and which can be clamped by a nut 227 in any angular disposition. Fixed to the top end of the link 223 is a guide blade 229 which is preferably located at the same inclination as the bed 187 and with its rearward end slidably engaged within the bifurcated top of an upright guide post 231 fixed on an arm 233 extending from the trunnion 173.

Location of the guide blade 229 at the same inclination as the bed 187 permits lengthwise adjustment of the drill 45 Without affecting the angular` disposition of its cutting edge. This arrangement also facilitates quick and accurate positioning for grinding of the second or generally diametrically opposed cutting edge.

In this regard, when the drill 45 is properly located in the -bed 187 of the vise 175 with the cutting edge in the desired relation to the grinding wheel 43, the tap wrench 209 is tightened around the drill 45 while one of the handles 219 is in engagement with the guide blade 229. Thus, after the first cutting edge has been ground, the drill 45 can be unclamped from the vise 175 and rotated around its axis about 180 degrees without unclamping the tap wrench 109, so that the other handle of the tap wrench will engage the guide blade 129 to locate the other cutting edge in substantially the same relation to the grinding wheel 43 as the first cutting edge. The drill can then be again tightly clamped in the vise for grinding of the second cutting edge.

The disclosed apparatus permits repeated and uniform sharpening of drills to provide an optimum drill point formation, while the disclosed drill point provides irn- 6 proved cutting action with reduced power requirements. Moreover, the apparatus incorporates many adjustability features to permit its use with drills of various sizes and to provide drill points of various configurations.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

l. The combination in drill grinding apparatus of a base, a support rod carried at one end by said -base for swinging movement about a vertical axis and for swinging movement about a horizontal axis, a camming surface supported on said base and engaged by the other end of said support rod, said camming surface having a curved outline in a plane disposed transversely of said support rod, a horizontally disposed rotatable arbor carried by said support rod intermediate its ends and in transverse relation thereto, a grinder xed to said arbor for rotation therewith, said grinder including a grinding wheel rotatable about an axis fixedly located with respect to said arbor, said axis being swingably movable in a plane perpendicular to said arbor incident to rotation of said arbor, means interconnecting said base and said arbor for vertically swinging said support rod, whereby said support rod is simultaneously horizontally swung by engagement of said support rod with said camming surface, and for rotating said arbor so as to swing the axis of said grinding wheel in said plane perpendicular to said arbor, and means on said base for holding a drill to be ground during vertical swinging of said support rod.

2. The combination in drill grinding apparatus of a base, a support rod carried at one end by said base for swinging movement about a vertical axis and `for swinging movement about a horizontal axis, a camming surface supported on said base and engaged by the other end of said support rod, said camming surface having a curved outline in a plane disposed transversely of said support rod, a horizontally disposed rotatable arbor carried by said support rod intermediate its ends and in transverse relation thereto, a grinder fixed to said arbor for rotation therewith, said grinder including a grinding wheel rotatable about an axis ixedly located with respect to said arbor, said axis being swingably movable in a plane perpendicular to said arbor incident to rotation of said arbor, said grinding wheel having an outwardly convex grinding surface, means interconnecting said base and said arbor for vertically swinging said support rod, whereby said support rod is simultaneously horizontally swung by engagement of said support rod with said camming surface, and for rotating said arbor so as to swing the axis of said grinding wheel in said plane perpendicular to said arbor, and means on said base for holding a drill to be ground during vertical swinging of said support rod.

3. Apparatus for grinding a drill comprising a base, means carried lby said base for 'xedly holding a drill, and means carried by said base for grinding said drill, said grinding means including a support rod carried at one end by said base for swinging movement about a vertical ax-is and for swinging movement about .a horizontal axis, a camming surface supported on said base adjacent the other end of -said support rod, means biasing said other end of said support rod against said camming surface, a horizontally disposed rotatable arbor carried by said support rod intermediate `its ends and in transverse relation thereo, a grinder `fixed on said arbor for rotation therewith, said grinder including a grinding wheel rotatable about an axis 4fxedly located with respect to said arbor in a plane perpendicular to said arbor incident lto rotation of said arbor, `a linkage interconnecting said `anbor and said lbase for vertically swinging said support rod and for rotating said arbor, 'said linkage including a first link iixedly connected to said arbor -for rotation therewith, said first link having a handle part, and a second link connected at one end to said base and at its other end to said first link, said second link being pivotally connected to said base for movement about a horizontal axis and about a ver-tical axis and being pivotally connected to said iirst link about a horizontal axis at a point spaced from the connection of said arbor and said -first link, whereby, when said arbor is rotated by said handle part, the axis of said grinding wheel is swung in said plane perpendicular to said arbor, said -support rod is swung ver-tically by said linkage and, at the same time, is swung horizontally by engagement of said support rod with sa-id camming surface.

4. Apparatus for grinding a drill comprising a base, means carried by said base for ixedly holding a drill and means carried by said base for grinding said drill, said Igrinding means including a support rod carried at one end by sai-d base for swinging movement about a vertical axis and for swinging movement about a horizontal axis, a camming surface supported on said base adjacent the other end of said support rod, said camming sur-face having a curved outline in a plane disposed transversely to said support rod, means biasing said other end of said support rod against said camming surface, a horizontally disposed rotatable arbor carried by said support rod intermediate its ends and in transverse relation thereto, a grinder lixed to said arbor for rotation therewith, said grinder including a grinding wheel rotatable about an axis tixedy located with respect to said arbor, said 4grinding wheel having Van outwardly convex grinding surface, a linkage interconnecting said arbor and -said base for vertically swinging said `support rod and for rotating said arbor, said linkage including a first link xedly connected to said arbor for rotation therewith, said first link having ya handle part, and a second link connected at one end to said base and at its other end to said tirst link, said second link being pivotally connected to said base `for movement about a horizontal axis and about a vertical axis, and being pivotally `connected to said first link about a horizontal axis at a point spaced from the connection of said arbor and said lirst link, whereby when said arbor is rotated by said handle part, the axis of said grinding wheel is swung in said plane perpendicular to said arbor and said support rod is swung vertically by said linkage and, at the same time, is swung horizontally by the engagement of said support rod with said camming surface.

5. Apparatus for grinding a drill comprising a base, a holder for the -drill supported by said base, and means carried by said base for grinding said drill, said holder being adjustably positionable vertically and relative to a horizontal axis and to a vertical axis, said holder including means for axially positioning the drill relative to said holder, said grinding means including a support rod carried at one end yby said base for swinging movement about a vertical axis and for swinging movement about a horizontal axis, a camming surface supported on said base adjacent the other end of said support rod, said camming surface having a curved outline in a plane disposed transversely to said support rod, means biasing said other end of said support rod against said camming surface, a horizontally disposed rotatable arbor carried by said support rod intermediate its ends and in transverse relation thereto, a grinder iixed to said arbor for rotation therewith, said grinder including a grinding wheel rotatable about an axis ixedly located with respect to said arbor, said axis being swingably movable in a plane perpendicular to said arbor incident to rotation of said arbor, a linkage interconnecting said -arbor and said base for vertically swinging said support rod and for rotating said arbor, ysaid linkage including a iirst link ixedly connected to said arbor for rotation therewith, said iirst link having a handle part, and a second link connected at one end to said bas'e'and at its other end to said lirst link, said second link being pivotally connected to said base for movement about a horizontal axis and about a vertical axis and being pivotally connected to said first link about a horizontal axis at a point spaced from the connection of said arbor and said first link, whereby when said arbor is rotated by said handle part, the axis of said grinding wheel is swung in said plane perpendicular to said arbor and said support rod is swung vertically by said linkage and, at the same time, is swung horizontally by the engagement of said support rod with said camming surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,072,868 Monils Sept. 9, 1913 1,750,504 Brougher Mar. 11, 1930 2,795,085 Rosenblom June l1, 1957 2,858,649 Scheubeck Nov. 4, 1958 2,859,645 Emmons et al Nov. 11, 1958 2,903,922 Ernst et al Sept. 15, 1959 FOREIGN PATENTS 299,640 Great Britain Nov. 1, 1928