US2232563A - Machine for pointing drills - Google Patents

Description

Feb. 18, 1941; H. c. SCHUMACHER 2, 56

MACHINE FOR POINTING DRILLS Filed Jan. 30, 1939 3 Sheets-Sheet 1 FIG]. FIG.2. FIG.3.' FIG.4. 4 r l4 :2 2 l 2o 5 9 I3 22 INVENTOR HARRY\ C.SCHUMACHER imim M w HEM ATTORNEYS v Feb. 18, 1941.

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HQC. SCHUMACHER MACHINE FOR POINfIING DRILLS Filed Jan. 30, 1939 s Sheets-She et 2 INVENTOR HARRY C. SCHUMACHER ATTORNEYS Fb. 18, 1941. Q SQHUMACHR 2,232,563

MACHINE FOR POINTING DRILLS Filed Jan. 30, 1959 5 Sheets-Sheet 3 mammal E--i E;

K7 K6 K K3 mag INVENTOR. HARRY C. SCHUMACHER ATTORNEYS Patented Feb. 18, 1941 UNITED STATES PATENT OFFICE 10 Claims.

The invention relates to machines for grinding twist drills, and more particularly to a construction adapted to accurately form the cutting edges of the drill so as to be exactly centered in the axis of rotation.

In the manufactureof twist drills the body of the-drill isformed with helical grooves therein separated from each other by a web portion which unites opposite segmental cylindrical portions. The strength of the-drill depends upon thethic'kness of this web portion,but thegreater the thickness thefarther the main cutting edge at the end of the drill will be removed from the axis of rotation. -It is, therefore, necessary in forming the cutting end of the drill to cut away the rear side of *the Web for the double purpose of forming auxiliary cutting edges and providing a necessary clearance. The accuracy of operation of the drill depends upon forming these auxiliary 2O cutting edges so as to extend exactly to the axis of rotation, but such accuracy in construction is It is the object of my invention to obtain a construction adaptedior the accurate pointing of 25 twist drills of any size within predetermined. limits and ofany variation in helical angle. To this end, the invention consists in the construction as hereinafter set forth.

In the drawings: 30 Figures 1 to 4 inclusive are diagrams illustrating twist drills inaccurately and accurately pointed;

Figure 5 is a plan View of the completed drill;

Figure 6 is a side elevation of the machine;

Figure '7 is an enlarged view of a portion of Figure 6, showing the grinder wheel in position for finishing one-half of the drill;

Figure 8 is a plan view partly broken away of a portion of Figure 6;

Figure 9 is a section taken on line 9-9 of Figure 8;

Figure 10 is a section taken on line 10-! of Figure 9;

Figure 11 is a cross section on line Il--II of Figure. 9;

Figure 12 is a section on line lZ-l 2 of Figure 8;

Figure 13 is a section on line |3--l3 of Figure 8;

Figure 14 is a section on line l4--l4 of Figure 8;

Figure 15 is an elevation of the trimming mechanism viewed in the same direction as Figure 6;

Figure 16 is a side elevation of the trimming mechanism viewed from the left of Figure 8.

To better illustrate the functioning of my improved machine, I have diagrammatically represented in Figures 1 to 4 the cutting end of twist drills accurately and inaccurately formed. Figure 1 illustrates the "endof the drill before the cutting away of the web portion. to form the auxiliary cutting edges and clearance. Figure 2 is a similar view showing the web partly cut away, but with the auxiliary cutting edges not extending completely to the axis of rotation. Figure 3 is a similar view showing the web cut away more on one side than the other, so that one of the auxiliarycutting edges extends beyond the axis of rotation. Figure 4 is a. similar View showing the web cut away to center both auxiliary cutting edges exactly in the axis of rotation.

As shownin Figure 1, l is the web portion of the twist drill and 2 and 3 the helical grooves on opposite sides thereof. If such a construction without further formation, were used for drilling then assuming the direction of rotation as indicated by the arrow, there would be a cutting edge extending from 4 to 5 on the side of the webadjac'eiit to the groove 2, and a cutting edge extending from 6 to I on the side of the web adjacent to the groove3. As neither of these cutting edges extends to the axis of rotation, this would leave an undercut areadefined by the circle 8. In Figure 2 the rear portions of the web on opposite sides of the axisare cut away as indicated at 9 and III to form auxiliary cutting edges II and I2, which however, do not extend completely to the axis of rotation. This would leave an undercut area indicated by the smaller circle l3. In Figure 3 theyweb is cut away at I4 to form a cutting-sedge l5 which extends through and beyond the axis of rotation, while on the opposite side the Web is cut away at IE to form a cutting edge ll extending to the edge I5. This also would leave an uncut area defined by the small circle l8. Finally; in Figure 4 the web is cut away at l9 and illto form cutting edges 2| and 22 terminating exactly in the axis of rotation. Such a construction will remove all of the material from the axis to the periphery'of the drill, and the cutting edges upon opposite sides of the axis will he so exactly balanced as to avoid tendency to deflect thedrill in any direction. Figure 5 is a plan view of the cutting end of the drill as formed in Figure 4, 23 and 24 being the main cutting edges formed on opposite sides of the web, and 2| and 22 the auxiliary cutting edges. The cut away portions extend at substantially the helix angle so that while the web is reduced in thickness its rear face25 is substantially parallel to the front face 26 of the helix. This gives the maximum .of said member relative thereto.

clearance without unnecessarily weakening the strength of the web.

In designing my machine to be universal in the pointing of drills, the variables to be considered are: first, the peripheral diameter of the drill; second, the thickness of the web; and third, the helical angle. It is also essential that with all variations in these factors the drill blank should be mounted so that its finished center will be exactly positioned with respect to the line of relative movement of the grinder wheel, which I accomplish by the following construction.

My improvements may be either embodied in a machine particularly designed for the purpose or may be used as attachments to any standard form of tool grinding machine. Such machines include as essential factors: first, a rotary grinder wheel and means for trimming the same to a predetermined cross sectional contour; second, a work support, and third, means for relatively reciprocating said grinder wheel and work support along a predetermined path. Usually the direction of reciprocation is rectilinear and provision is made for adjusting the .work or the grinder wheel transversely with respect to the path of movement.

Figure 6 illustrates a machine particularly designed for pointing drills in which A is a suitable base provided with an upwardly extending column B for supporting an electric motor C, and D is a grinder wheel mounted upon the motor shaft. This grinder is shown as a cupped wheel, which is enclosed within a guard housing E, the latter being cut away at the bottom for exposing the operating portion of the wheel.- Supported on the base A are guide rails F extending parallel to the plane of rotation of the grinder wheel with their opposite ends secured in bracket members F. G is a carriage slidable upon the guide rails F, and as shown is formed of a hollow member embracing said rails and having bearings G for engaging the same. Upon the carriage G is mounted a transversely movable carriage H. This also is preferably formed of a hollow member having parallel guide rails H extending thereacross at right angles to the direction of the rails F. The rails H engage bearings H mounted upon the carriage G,-said bearings being arranged within the hollow member H and so spaced as to provide the necessary movement For moving the carriage H with respect to the carriage G the latter is provided with an upwardly extending bracket bearing G having a detachable cap G I is a rotary member grooved to engage and to be swiveled in the bearing G and internally threaded to engage a correspondingly threaded rod I. This rod is secured'at its inner end to the member H by means of a screw I which also holds it against rotation. I is a second nut member. engaging the threaded rod I and I is a collar member sleeved upon the rod I intermediate the members I and 1 This collar is held from rotation while being free to move axially of the rod I, by means of a, spline I engaging a spline way I in the rod. The arrangement is such that .by rotation of the member. I the rod I and carriage H will be moved upon the guideways H, while the member I forms an adjustable stop for limiting the amount of such movement.

Mounted upon the carriage H is a Work holder J. This includes a supporting and clamping bearing for the drill to be operated upon, a stop for the pointed end of the drill, and positioning members for holding the drill with its main cutting edges at a predetermined angle to the plane of rotation of the grinder wheel. There is further provision for adjusting the holder to correspond to the particular helical angle of the drill, while in each position of adjustment the axial point of the drill will remain in a fixed plane :parallel to the plane of rotation of the grinder wheel, the construction being as follows.

The base portion J of the work holder J rests upon a horizontal plane surface H on the carriage H and is pivotally connected thereto by a pivot post J The latter is threaded at its lower end to engage the member H; has a cylindrical portion engaging a corresponding bearing in the member J, and a threaded upper portion for engaging a clamping nut J. A second post J similar to the post J extends through a set;- mental slot J in the base member J which slot is concentric with the axis of the post J A clamping nut J similar to the nut J serves to hold the base member J in any position of angular adjustment about the axis of the post J Rising from the base member J is a portion J of the member J having at its upper end a clamping bearing K for the drills. This bearing is so located that the axis of the drill which lies in a horizontal plane will intersect the vertical axis of the post J The bearing is preferably in the form of a split cylinder and to adapt it for holding drills of different diameters it is provided with a series of exchangeable bushings K, externally fitting the bearing K and internally the particular drill to be operated upon. The bushings K are slotted on one side as indicated at K for the passing therethrough of a clamping tongue K directly contacting with the drill. The tongue is operated by a revoluble rod K which has a pivotal engagement K with a central socket in the tongue, and is threaded to engage a nut K secured in a recess in the member J". At the outer end of the rod is an operating handle K which when revolved will move the rod axially, carrying with it the tongue K Thus, after the drill is positioned it may be clamped to securely hold the same. The bushings K are held from displacement by a set screw K.

As has been stated, the point of the drill must be accurately positioned and also the drill must be angularly adjusted about its axis into a predetermined postion. These functions are performed by the following construction.

Secured to one side of the member K in a vertical plane transverse to the axis of the drill is a casing L which is longitudinally slotted to form guideways for the shanks L and L of cooperating locating members. The jaws of these locating members project beyond the casing L,

and are so fashioned as to bear against the main I cutting edges at the end of the drill on opposite sides of the axis thereof and to properly position the same angularly about said axis. The end of the upper jaw L bears directly against thecutting edge, while the jaw L is in the form of a hook, the inner face of which bears against the other cutting edge. Also, the inner face of the shank L forms a stop for the end of the drill which is located in the vertical axis of the post J The shanks L and L are partly cut away at L and L to receive coil springs L bearing at their rear ends against the shoulders on said shanks, while their forward ends bear against a pin L extending vertically through the casing L. Thus, these springs resiliently urge the shanks L and" L rearward in mar guideways in the casmg I The rear portion ofthe casing L is cut" awayto forma recess in which is located an adjustable bl-ock- M. The forward face of this block has-cam-surfaces M and M which incline oppositely from the center of the block and are adapted to respectivelyengagecorresponding inclined faces'L 'and L at'the rearends of the shank s L and L The blockM is provided with a'threaded a-perturefor engaging the threaded portion M of a rotary member M extending vertically through the casing L and swiveled therein.- As shown,- this member has a head portionlVI bearing on-the top of the casing and a collar M at its lower endbearing against the lower face of the casingythereby holding it from vertical movementwhile permitting freerotation.

In the central position of the block M the shanks L and L will be held so that the clamping faces of the jaws L and L will be inalignment with their adjacent endsinuthe-vertical axis of the post J When, however, the member M is revolved to move the block M in a downward direction, the-cam'face M will move the shank L 'outward, while the cam face M will be withdrawnfromtheshank L to permit the latter to moverearward under-the actuation of its spring ciently for theengagementof the drill, after whichan'opposite rotation of the member M willmove the-jaws intocontact with the main cuttingedges of the drill. The drill is thus properlylocated, after which it is clamped by the operation-ofthe handle 'K actuating the tongue K thereby rigidlysecuring the drill for operationthereuponby the grinder wheel.

It-is essential to the proper functioning ofthe machinethat the grinder wheelshould be fashioned toa cross'sectional contour corresponding to'the clearancerecess in the finished tool. This fashioning of the-grinder is accomplished by a trimming mechanism which is mounted on the carriage H'and'whioh is of the following construction. N is a post projectingvertically upward from one side of the carriage H so as to be spaced from the post J N is a bracket member havingaportion N sleeved entire post Nand a depending'portion N bearing "against'the side of the' carriage H'to preventrotation on the post. The bracketN' is formedwith a segmental portion N having a T-shaped segmental slot N therein. N is a head member having a segmental rib N' engaging the slot N and N is a clamping bolt passing through the head N providedatits innerend with aT-head N in the slot'Ni, and ,at'its outer endengaginga clamping nut N The construction is such that the head N may be adjusted around to anydesired position on the segment N and held in this position by tightening the clamping nut N Journaled within the head N is a rockshaft having on one end a; rock arm 0 and on its opposite end an actuating crank handle 0 At the free end of the rock arm 0' is a cylindrical socket O for the. reception of a dresser or trimmer bar 0 extending obliquely in relation to the plane of the rock arm. 'An adjustment screw 0 will move the dresser bar axially and when properly positioned the cutting surface of the end of this dresser bar should be located at the center of theysegment N Operation i To set-the machine ready for operation in pointingia drill, a bushing K is first selected having an internal diameter correspondingto theparticular drill to bemounted; This bushing is then engaged with the split clampingbe'a-ringK and secured therein by the set screw K. The drill-is then inserted through the bushing and 5 its end adjusted until it contacts with the inner face of-the shank L the jaws;L and L being' first separated: sufficiently forthe reception 1 of the drill. The rotary member M is then revolved in adirection to movethe jaws L and L toward each other until" they engage with the main cutting edges "of the drill to holdthe latter against rotation.- The handle K is then turnedto project the'tongue K through-the slot K and to clamp the drill rigidly within the bushing. The work holder J J is then adjusted-about the pivot J to correspond to. the helical angle of the drill, andwhen properly adjusted is clampedin" this position by tightening the clampingnuts J andJ;

Trimming of the grinder It being assumedthat the dresser bar 0 has. been properlyposit-ioned in its socket 0 the head N is adjusted around the segment N to an 5-- angular position corresponding to the angle of the jaws L andL or any suitable angle, and then clamped in this position by the nut N The carriage G is then moved to position thedresserin the vertical axial plane of the grinder 36 wheel, after which thecrank handle 0 is oscil lated to move thedresser upward and downward across the outer face of the grinder wheel. At. the same time, the member I is revolved to adjust the carriage H transversely toward the: 5 grinder as fast as necessary to perform the trimming. When the face P of the grinder wheel; has been properly trimmed, the nut I is rotatively adjusted upon the threaded red 1' until;

' it bears against the collar I with the latter bear- 0* ing against the rotary adjustment member I. The member I will then constitute a stop which definitely locates the position of .the carriage-H;

at the point designated 0r axis of the pivot J Subsequent or priorto the trimming of theface; 52' P the peripheral face Q of the wheel may be. trimmed by first adjusting the head N aroundthe segment N so that the dresser O is substantially in the plane of rotation of said wheel. The crank handle 0 is then oscillated to move the dresser back and forth sufficiently to dress the periphery of the wheel. At the completion of both of these operations the apex of the angle in the cross sectional contour of the grinding wheel:- will be in exact alignment with the center'of the 5 5i positioned drill.

The machine is now in condition for the performance of the grinding operation, it being only necessary to first adjust the rotary member I to withdraw the carriage I-Iaway from the grinder 60" wheel sufficiently to clear the drill. The work holder and grin'der wheel are then relatively. reciprocated while at the same time the member I is rotated to gradually feed the carriage toward the wheel, this effecting the progressive grinding of the side of the drill above itsaxis. This grinding will be completed when the member I -is stopped from further movement by the member I The drill is next released in its clamping bearing K, so as to permit of rotating it through an angle of after which it is again clamped. The grinding operation is then. repeated to grind the clearance in the opposite side of the drill. Thus, at the completionof both grinding operations the drill'will be properly ground, the tw'o nl auxiliary cutting faces being exactly centered in the axisof the drill. What I claim as my invention is: 1. The combination of a grinder wheel formed to a predetermined angular cross sectional contour, a carriage mounted for relative reciprocation, a work holder pivotally mounted on said carriage to be adjustable about an axis perpendicular to the direction of reciprocation, means for clamping upon said work 'holder a tool to be ground with its rotational axis in a plane parallel to the direction of movement of said carriage and intersecting said perpendicular axis, said plane being tangent to the apex of the angular cross ,sectional contour of said grinder wheel, a stop for locating the end of said tool at the point of intersection of saidaxes, means for locking said work holder in an adjusted position about said perpendicular axis corresponding to the particular helical angle, of the tool to be ground, and

means for moving said work holder transversely to the direction of reciprocation to gradually feed said grinder wheel into the work and to finally bring said point of intersection into the path 5 of the apex of the angular cross sectional contour 0 -tion, a work holder pivotally mounted on said carriage to be adjustable about an axis, perpendicular to the direction of reciprocation, means for clamping upon said Work holder a tool to be ground with its rotational axis in a plane parallel to the direction of movement of said carriage and intersecting said perpendicular axis, said plane being tangent to the apex of the angular cross sectional contour of said grinder wheel, a stop for locating the end of said tool at the point of intersection of said axes, means for locking said work holder in an adjusted position about said perpendicular axis corresponding to the particular helical angle of the tool to be ground, means for moving said work holder transv versely to the direction of reciprocation to gradually feed the work into the path of said grinder wheel, and means for limiting said transverse movement to the position where said point of intersection lies in the path of the apex of the cross sectional contour of said grinder wheel.

3. The combination of a grinder wheel formed to a predetermined angular cross sectional contour, a main carriage mounted for relative reciprocation, a transverse carriage mount-ed on ,said main carriage, a work holder pivotally mounted on said transverse carriage to be adjustable about an axis perpendicular to the direction of reciprocation, means for clamping upon said work holder a tool to be ground with its rotational axis lying in a plane parallel to the direction of movement of said carriage and tangent to the apex of the angular cross sectional contour of the said grinder wheel, said rotational axis intersecting said perpendicular axis, a stop 65 for locating the end of the tool at the point of intersection of said axes, means for locking said work holder in an adjusted position about said perpendicular axis corresponding to the particular helical angle of the tool to be ground, and

70; means for limiting the movement of said transverse carriage ata point where said point of intersection lies in the path of said apex.

4. The combination with a grinder wheel and a main carriage mounted for relative reciproca- 75 tion, of a transverse carriage mounted on said main carriage, a work holder pivotally mounted on said transverse carriage to be adjustable about an axis perpendicular to the direction of reciprocation, means for clamping upon said work holder a tool to be ground with its rotational axis intersecting said perpendicular axis and its end located at the point of intersection, means for locking said work holder in an adjusted position about said perpendicular axis corresponding to the particular helical angle of the tool to be ground, means for trimming said grinder wheel to an angular cross sectional contour, such that in the relative reciprocation of said main carriage and grinder wheel said point of intersection will lie in the path of the apex of said angular cross sectional contour, and a stop for limiting the movement of the transverse carriage with the parts in such relation, whereby said transverse carriage when withdrawn to clear the work from said grinder wheel may be gradually fed toward said stop and limited by the latter when aid apex reaches the exact rotational center of the tool.

5. The combination with a grinder wheel and a main carriage mounted for relative reciprocation, of a transverse carriage mounted on said main carriage, a work holder pivotally mounted on said transverse carriage to be adjustable about an axi perpendicular to the direction of reciprocation, means for clamping upon said work holder a tool to be ground with its rotational axis intersecting said perpendicular axis and its end located at the point of intersection, means for locking said work holder in an adjusted position about said perpendicular axis corresponding to the particular helical angle of the tool to be ground, trimming mechanism also mounted on said transverse carriage adapted to trim said grinder wheel to an angular cross section such that in the same position of said transverse carriage during reciprocation of said main carriage the apex of said angular section will pass through the point of intersection of said tool axis and perpendicular axis, and a stop for said transverse carriage in this same position limiting its movement toward the grinder Wheel while permitting withdrawal of the carriage in the opposite direction.

6. In a machine of the character described, a work holder including a cylindrical bearing, an exchangeable bushing secured Within and fitting said cylindrical bearing having concentric inner and outer surfaces and an internal dimension corresponding to the tool to be ground, said bushing being longitudinally slotted in one side thereof, and clamping means for the tool including a tongue member extending longitudinally of and. through said slot into direct engagement with the tool whereby the latter is clamped with its axis coincident with the axis of said cylindrical bearing.

7. In a machine of the character described, a work holder comprising a cylindrical bearing, an exchangeable bushing for said bearing having an. internal diameter corresponding to that of the tool to be ground, said bushing having a slot extending through one side thereof, a tongue member extending longitudinally of and through said slot, and a screw centrally pivotally engaging said tongue member to move the same into clamping contact with the tool while permitting accurate alignment therewith of its clamping face whereby said tool is clamped with its axis coincident with the axis of the cylindrical bearing.

8. In a machine of the character described,

pivotally mounted on said carriage to be adjustable about an axis perpendicular to the direction of movement of said carriage, means for locking said work holder in different positions of angular adjustment, means on said work holder for clamping a tool with its rotational axis intersecting said vertical axis, a pair of members slidably secured on said work holder to extend perpendicular to said rotational axis and in a plane of said vertical axis, jaws on said members fashioned to engage the main cutting edges of the tool and to position the same about said rotational axis, and means for adjusting said members to move said jaws equally on opposite sides of the point of intersection of said vertical and rotational axes.

9. In a machine of the character described, the combination with a carriage, of a work holder pivotally mounted on said carriage to be adjustable about an axis perpendicular to the direction of movement of said carriage, means-for locking said work holder in different positions of angular adjustment, means on said work holder for clamping a tool with its rotational axis perpendicular to and intersecting said vertical axis, a pair of members slidably mounted on said work holder to extend perpendicular to said rotational axis in the plane of said vertical axis, jaws on said members fashioned to engage the main cutting edges of the tool on opposite sides of the axis thereof and to position the same about said rotational axis, one of said members forming a stop for the end of the tool, and means for adjusting said members to move said jaws equally and oppositely upon opposite sides of the point of intersection of said rotational and vertical axes.

10. In a machine of the character described, a work clamping and positioning means comprising a supporting head, a cylindrical bearing, an exchangeable bushing secured within said cylindrical bearing and having an internal diameter corresponding to the tool to be operated upon, said bushing having a slot in one side thereof,

a tongue engaging said slot, a screw mounted on said head for adjusting said tongue to directly engage the same with the tool to be clamped, a pair of members slidably mounted on said head to extend perpendicular to the rotational axis of the tool, jaws on said members fashioned to engage the cutting edges of the tool on opposite sides of the axis thereof, and means for simultaneously adjusting said members to move said jaws equally and oppositely on opposite sides of the axis of said tool.

HARRY C'. SCHUMACHER.

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