US2520647A - Apparatus for grinding drills and the like - Google Patents

Description

Aug. 29, 1950 P. H. NEEDHAM 2,520,647

APPARATUS FOR GRINDING DRILLS AND THE LIKE Filed Nov. 28, 1947 I5 Sheets-Sheet l INVENTOR.

P/WL H NEEDHAM Aug. 29, 1950 P. H. NEEDHAM APPARATUS FOR GRINDING DRILLS AND THE LIKE 3 Sheets-Sheet 2 Filed Nov. 28, 1947 INVENTOR. QWL H. NEEDHAM 3 Sheets-Sheet 3 Aug. 29, 1950 P. H. NEEDHAM APPARATUS FOR GRINDING DRILLS AND THE LIKE Filed Nov. 28, 1947 R m m H H m w W H m J M A Q p M. E S 2 a7472 Z4 W a g a w 6 Patented Aug. 29, 1950 APPARATUS FOR GRINDING DB ANn rHELIn 4 v Paul H. Needham, Beverly Hills, Calif. Aipplication November as, ie n's ri mo; 788,491

. This-invention relates to apparatus for grinding. the-points of tools andi mplements, such as twistdrill's, having generally conical end faces f-which the coning angle mustbe accurately maintained at a determined value and, in addition, a predetermined clearance must be accurately ground from a reference line such as the V cuttingedge of a twist drill, back=toa rear area such as'the heel of a twist drill. In-the grinding of dril1s,' it is desirable that'this clearance angle vary from the cutting edge back to the heel, starting. with, e. g.'-three degrees at the cutting edgeand ending with, e. g; fifteen degrees at the heel. It isalso necessary that the clearance be I the same for each lip-of the drill 'and that the two cutting edges be exactlysymmetrical so that, in rotating, :they will describe the same conical surfaceofrevolutioni The clearance angle at the cutting edge should be within the range from two-to four degrees.

A general object of my'invention is to pro-" vide a mechanism by the use of which the several lips of a twist drill may be consecutively ground On-theirend faces with identical coning angle and clearance, and with the clearance varying gradually and uniformly from a predetermined minimum angle at the cutting edgeto a predetermined maximum angle at theheel. Such gradual variation'of clearance angle produces a' clearance; which in cross section is curved graddurability.

.A furtheriobject of my invention is to provide anapparatus-rby theme ,of which'the desired coning a'ngle'andclearance can be ground quickly and expeditiously. A further object is to provide anapparatus which may be used by a relativelyunskilled operatorto grind drill points to exactly the desired shape, ..To thisend, the invention provides an" apparatus which will. hold and guide a drill so that it: is practically impossible for the drill to be improperly? ground, the only requirement being that the operator follow a few simple operative steps. v

In. order to attain a. clearance angle startin immediately at the cuttingedge; it is necessary tog-avoid rotating the ;drill through a complete revolution while in contact with the grinding wheel. Accordingly, a further object of the in vention is to provide a grinding apparatus which may-beoperated so as to presentth'edrill-to thegrinding wheel with the cuttingedge in-exactly.

to then swingthe drillarcuately througha sum cient angle-to proceed from the initial clearance angle to the final clearanceangle while continuously rotating the drill, shifting the line of contact from the cutting edge to the heel, and maintaining the proper coning angle, and, finally,

to Withdraw -the drill from the grinding wheeland "to-indexfl the drill 'soas to bring the other lip of the drill-into position for a similar oper-' ually from .thecutting edge to the heelw This provides for maximum-cutting edge strength and l the-proper position for. the grinding of the initial j clearance angle andthe proper. coming: angle,

Another object of the invention is to provide a 'nov'el and improved quick acting chuck mechan'isn'i f or holding I the drill.

Other objects will become apparent -in the ensuing specifications and appended drawings in whichz i r Fig; I is a front viewof'a grinding mechanism embodying my invention; r

Fig. -2 is a' front endview, partially in section, ofthechuck' andindexing mechanism and associatedparts;-

"Fig. miss a secthnahiew Of a mod f ed for th a e;' 1

Fig. 3 is fan'end view-of the apparatus, with the base'portions thereof shown'in section as in dicated by the line 33-of -Eig. 1;

Fig.4 s a'diagrammatic end view ofthe grindj in'g wheel and drill indicating how the arcuate" relief angle is ,produced'bythe swinging of the drillabout' theai'zis of the' chuck arbor;

Fig.14a is anend lines of grinding;

Fig. 4b is a side view of the drill indicating'the j .crovvningffii e., relief curvature) of thefend ur du i rin n Fig. 5*is' a perspective view of the operating 7 Fig.1}; isfa transversie sectional view ofthei Fig. 9 is a perspective view. of the "inner as smbly of the chuck;

Fig lQisanend view o f the assembly shown in Fig. 9; and

Fig.- ll'is a persp jaws.--p.

I .In the machine which is. shown herein as an illustrativeexample-ofone*form in which theinvention may be. embodied; a: grinding wheel 15 V is mount'cdi-for rotationinza hoodi IS which-is supported upon a base l1, and is provided with viewof .a' drill showing the ctive view of. one of the chuck annular bead 53d'on the post. 53a so: as toxretain the post against axial 'movementin the :sleeve. The other end of the. sleeve 53b is formed with a pair of ears .53e between which is hinged, on a pin 53f, a lug on the end of a universal coupling member 56a. The member 56a. is pivotedyat 6|| on an axis at rightangles to the hinge pin- 53 to .the arm 55.... .5

The fork 52'embraces" the arm 31' oftheyoke 36 and is connected :thereto :by; diametrically opposed pivots. |i|.'v The heel -62 of the-fork 52, where it joins the arbor 24', is provided with a lug 63 which is embraced by a pair of links 64,- pivoted thereto at 65. The links 64 also embrace the bridging portion 66 of the yoke 36, which bridging portion is provided with a longitudinally extending slot.6'|. A bolt.68 extends through each of the arms 64 and the slot. 61 and has a headedthumbnut 69 threaded upon its upper end; By' 5 tightening the thumbnut 69,- the links 64" may be clamped against the sides of the bridging portion 66 of the yoke 36 so as'tolocklthe yoke 36 in a selected position of adjustment. By loosening the thumb nut 69, the entire chuck and yoke assembly may be swung about the axis of the pivot 6|, relative to the fork 52, therebyto'change the angle subtended between the chuck:axis and the plane of the grinding wheel (and to vary the coning angle 0 of the drill point).

During the adjustment of the coningangle, the arms 54 and 55 may separate or move together in order to permit the chuck to be shifted horizonta11y,while maintaining the vertical level of the socket 56. a j 1 The heel 62 of the fork 52 is provided with a lug which moves between the extremities of a notch 1| in a stop member 12,.carried by the bearing 25.- The stop member 12 is, arched to conform to the curvature of the outer surface of the bearing and is provided with a slot 13 through which a screw 14 is threaded into .the bearing 25, to secure the stop member against the bearing. By loosening the screw" the stop mem ber- 12 may be adjusted to selected positions,

within the limits provided by the slot". Thusthe limits of downward swinging movementof the chuck can be varied. Ordinarily, such adjustment will be effected for the purpose ofsetof ,the angle is concerned. Thejheel 62 provides a shoulder 15 (Fig. '7) which bears against one end of the bearing 25. A washer 16, secured to the end of the arbor 24 by a cap screw'll, bears against the other end of the bearing 25, to securely hold the arbor against longitudinal movement. 7 1

Translatory movement of the arm 21 so as to move the chuck past the periphery of the grinding wheel, is provided for, by a screw shaft 18 which is mounted for rotation in bearings 19 on the base [.1 and which is threaded through alug 6. attached: to the ring- 32 and projecting up wardly throughv a longitudinal slot 8| in the shaft 28. The lug80 also functions as a. key, operating in theslotB ,to hold the ring 32 against rotation. Theshaft 21.8 may be provided with suitable heads 82 at its respective ends, bearing against the hearing '|9-to hold the shaft against endwise movement, and with a1hand1e 83 by means of which the shaft to the ring 32 and from it may be rotated. Movement is transmitted from the ring 32 to the arm 21. 1 :In my. improved chuck mechanism, the jaws 40iare pivotedwithinthe' quill 39 by :means' of trunnions' 84 and.85 on each jaw, pivotally'received in..bearings 86 in the quill 39. The trun-' nions 84 and 95 extend in the same direction so that 'a jaw may be inserted or removed fromthe quill'by endwise movement of the jaw; The trun-l nions 84, are located at one side of a jaw while thebiting edge 81 thereof is at the opposite sides of the. jaw. Consequently, the biting edges'i8'l maysswing inwardly'toward the center ofthe quill,to engage the periphery of a drill or other tool inserted into. the chuck. The jaws are provided with fingers .88 which extend outwardly through slots 89 in the quill and cooperate with operating rings 98 which are keyed into the operating barrel 4| 'by means of cylindrical keys 92. The keys 92 are engaged in key slots in the peripheries of the rings 99, and in slots in the annular inner wall of the barrel 4|. Spacer rings 93 are interposed between operating rings 98. The ring 93 at one end of the chuck is retainedby a rolled'edge on the peripheral wall oflthe barrel and cooperates with an integral bottom 93" of the barrel to confine the other rings 93' and 90. 7

Each operating ring Sithas an internal cam face 94 of helical shape and, at the outer end thereof, a reentrant finger 95. The cam surfaces 94 define cut out spaces in the rings 90, in which the respective levers 88 are received, and extend through 360 degrees. I

In the operation of the chuck, rotation of the operating barrel 4| in the counterclockwise direction as viewed in Fig. Swill cause the cam surfaces 94 to bear against the outer ends of the levers 88, moving them inwardly and causing the jaws to move" into clamping engagement with a tool embraced therebetween. During such move-' ment, the'quill'39 may be held against rotation by holding the handle 46,- 41 while it is latched into the collar 42. When it is desired to release the chuck, the operating sleeve is rotated in the counterclockwise direction, and the jaws will be moved outwardly by the action of small mouse trapsprings 91 encircling the trunnions 84 and bearing against-' the inner wall of the quill and against the jaws respectively. Movement of the operating ring in the opening direction is limited by engagement of the finger levers 88. I

' In a drill grinding operation, adrill is first inserted into the chuck and the chuck fastened as described above, after it has been presented to 95 against the the periphery -ofthe grinding wheel to determine its proper location lengthwise of the chuck.

The chuck is then. rotated, with the shaft"- unlatchedfrom the quill, and the'handle 46in the raised position, until one of the cutting edges of the drill is disposed substantially horizontally and in contact with the periphery of thegrindin'g wheel." The arm .2! is then retracted and the grinding wheel is rotated. The arm Z'l-is then advanced,:.whi1e. the handle. is held. in the

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