CA1063397A - Self-drilling screw - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
SELF-DRILLING SCREW
Disclosed is a self-drilling screw including an elongated shank, and an enlarged head at one end with means cooperable with a tool for turning the screw, the elongated shank including a threaded portion intermediate the enlarged head and an entering end portion of the shank. A drill tip is formed on the entering end portion and includes a pair of oppositely disposed, generally longitudinally directed flute means extending upwardly from and intersecting a pair of flat bevel surfaces formed on either side of a terminal ridge edge which intersects and is substantially perpendicular to the longitudinal axis of the shank. Each of the flute means comprises first and second intersecting, substantially longitudinally extending surfaces, the surfaces intersecting both of the bevel surfaces with the major lateral extent of the first surface extending at an angle not greater than 45° to the terminal ridge edge and thereby forming laterally extending cutting edges. The first surfaces comprise a pair of intersecting flat surfaces linear in both longitudinal and lateral directions and both of the pair of intersecting flat surfaces are inclined to the longitudinal axis of the fastener with the lowermost of the surfaces being inclined to a lesser amount than the uppermost of the surfaces. The second surfaces comprises a pair of intersecting surfaces, arcuate in the longitudinal direction with the intersection of the arcuate surfaces forming an upstanding ridge spaced axially from the cutting edges and extending generally laterally to the longitudinal axis. The first and second surfaces are disposed at from 92° to 97° to one another to insure proper relief behind the laterally extending cutting edges.

Description

1~363397 . ~ `

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SELF-DRILLING SCREW
This application is a division of Canadian Serial No. 275,479, ~ d April 4~ 1977.

~ackground of the Invention ~.

The present invention relates generrally to milling machines for producing drill screws and rnethods for producing such products ` : ~.
through successive operations of rotary-type saws on a scr ew blanli.

Cqrtain prior art apparatus and methods ha~e been s~lggestcd and utilized for producing drill screws and while tlley hav~ beetl g~enerally `:~ucceissful ancl have enablecl a commerc:ially acci~tecl clrill scr~v to be provided, the presetlt application contemplates fur ther improvemellt~
for facilitating production, minimi~,ing manufacturing costs and providing ig(`I`l',Wi~3 hE~Vitlg a mc)re e~ icient driL`ling action. Tll~ d~vice clescribecl in , .. . .

:. .. , . ., ,. ~ , , ~633~
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~: 1 u~ s. I~c'~ent 3,125,!):~ typi~ies Lh( pre~enl; com1nercially .s~lccessfu1 ,' clrill scre-v. 'I'he inc,reasing and varying demands for drill screw products requires methods and equiprment that are e~;treInely versat;le.
For e~;alllple, cuxrcnl driLI screw appLications inc:lude those requiring a long flute length, to be capable of properly drilli~l~ into thick ,rnaterials.
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, Prior art methods and apparatus for forming drill screws ' ~ typically utilize saws with a predetermined minimum diameter. For example, a three inch diameter saw is commonly used. This relative ~, .: .
~, size of saws is preferred since the saws themselves are expendable ' I O items and are contribu-tory to the cost of production of the drill screws.
i' Furthermore, the saws must periodically be sharpened ancl it has been ~`
" found that the particular size saws currently utilizec1 are most efficiently ,.. .
~' sharpened.

,However, the use of such convéntional rotary saws cre~ates ,, ,:
~5 certain inherent limitations in the methods and apparatus lcnown hereto-fore. The operations performed to mill the flutes in the blanl;~ include 1'` the formation of intersecting arcuate flute surfaces ancl flat flute surfaces ,~
,~ for each flute, l,vith the length of the arcuate sureace determinin~r the ', effective flute lcngth o~ the drill screw. To rnaximize the flute Icngth p~ 20 l~or a ~iv~n ~avv c1ta~net~r, th~ ~aw must substantial1y p~netrat~ the transverse cross sec-tion OI the blank. This substant,ial penetration obviously weakens the clril1 point behind the cutting edges due to the , ov~rl~pping of saws whe,n forrning oppositely disposed flutes. This ~; condition is amplified when a positive a~ial rake angle is required behind the laterally extending cutting edges. The penetration of each ,~ .

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~ 63397 ~:' I flllti.ng cut al-l anlount gre.-lter thatl llalr the diameter ol~ ihe blatllc at ,' the re~ion of intersection of the positive :rake ang'Le surf'aces will '; ereclte a throug~l transvelse hc~'le in the sh.lnli which is h.i~lll,y '. ulldcsirable.
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Currently successful prior art methods anc~ machinery contem- -.' plate either intermittently indexing blanks along a cireular path or ., ;~i eontinuously moving blanhs along a cireular path. In the intermittent . i ,.
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type me-thods, as typified in U. S. :Patent 3, 280, 412, the blanks are elampingly seeured in elreumferentially spaeed poclcets in a turret, .,. 10 preventing the blanks from rotating about their own a~is as they are ~. indexed to three different work stations surroundin~ the c:i:r cular path.
,", A first work station performs fluting euts on both si.des of the blanl~
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,: simllltaneous:ly. Second and third worlc stations create b~vel surfaees ~';, ' ' ,~ " .
.';' on the~ o~;tremity of the blanlc to form laterally e~;tellding cutting edges '` ' ,," 15 interseetirtg the f'lute surfaces.
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~', The continuous feed apparatus as typi~ied in U. S. Patent~,l 3, 422, ~72 utilizes a pair of fluting saws at different positions abollt a eireula.r path ereated by a tur.ret but eontemplates the enga~ement of .: :
the fluting saws with the blanlc as the blanlcs thermselves are fecl past ,'. 20, the work xtation. ~ pair o:~ pointing saws are also aeeur~tely positioned abou-t the eireular path to form bevel surfaees on the.extr emity of the blank, and the blanks themselves are rota-ted about their own aA~;is s between the work stations just deseribed.
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; .; , . , ','` Certain other methods have been devised in an ef.~ort to , 25 produee an improved pe:rformanee drill serew through the use of a ,.
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1~;)6339'7 .

rotary n~illing cutter appar~tus. }~or e~alnple, tJ. S. Patcllt 3, 780~ 3~9 COIlt~m~ tCS Lhe oL~ientation of the rotary milling cutter rel.ltive to ti blank in such a malmer so that the generally arcuate flute surEaces ,~ extencl above an~l form Lhe laterally e~;tendillg c~ltting edge. 'rhis design enables a positive ral;e to be formed bellind the cutting edge ~vithout Eear ~-of overlapping cutters but clecidedly limits the effective flute length ~vhich can be produced for a commonly used and conventional cutting saw.

The performance and efficiency of drill screl,vs rnanufactured with the abovementioned milling operations are measured and evaluated . by a number o-E parameters, including the followin~: the amount oE
axial pressure required to efEect a dr;lling operation, the time requ;recl to drill a hole, the length of flu-te requircd to properly exhaust Cllip material, the configuration and length of the chips produced during Y 15 driLling, the thickness of the web or column of material remaining , between the flute surfaces at a given distance behind a chisel edge, the length of the chisel edge itself, the axial rake angle provided by the flute behind the cutting edge, -the amoun-t of r elief behind the cutting edge as defined by the location of intersection of -the flat bev~ led surfaces with the El~lte s-lrfaces opposing~ the cut~in~ ed~r,es. Whilc the ~ri(.)r art methods have produced commercialLy acceptable drill screws in an effiFient ahd cornmercially sound manner, in many cases, a compromise oE one or rnore oE the aboYe listed pnrameters has been required because of the lack of versatility of prior art methods and/or machines.

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` ~)633~7 ~ Summary of the Invention I Disclosed generally is an apparatus for producing ~ drill screws which includes a rotatable turret having a , '~ plurality of blank receiving pockets circumferentially spaced thereabout. A plurality of, preferably six, milling saw stations are spaced in predetermined locations around the turret and clamping rotatable spindle devices are located and fixed axially above the pockets in the turret for engage-.. . . .
ment with the heads of the blanks situated therein. The -` 10 turret is intermittently indexed to present the blanks to each successive work station with the reciprocating cutting ~S:l , : .
engagement of the saws at each work station being timed to be synchronous with~the dwell period of the turret. In :.~ . . .
addition, the means indexing the turret also synchronously controls the rotation of the spindles to effect rotation oE
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the blanks about their own axis as they are conveying from one work station to the other in order to present the desired, predetermined surface of the blanks at the next Eluting or ` pointing station.
The method disclosed herein incorporates the formation of two longitudinally overlapping flute surfaces .,., , . . ~ , ; on each side of the blank with ~uch fluting opera-tions .': .
accomplished at four distinct cutting stations.
~he two overlapping fluting cuts on each si~e o~ the bLank will provide a drill screw w:ith a greatly increased effective flute length while not compromising the back of point strength, chisel edge, length optimization or rake angle requirements for the application.
In its broader aspects, the self-drilling screw `; 30 ofthis invention and to which this divisional application is ., : .
directed includes an elongated shank, and an enlarged head `
" at one end with means cooperable with a tool for turning the ,, .

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-- ~.Q6339~
, screw, the elc)ngated shank including a threaded portion ~;
intermediate the enlarged head and an entering end portion of the shank. A drill tip is formed on the entering end portion and includes a pair of opposi-tely disposed, generally , 5 longitudinally directed flute means extending upwardly from , and intersecting a pair of flat bevel surfaces formed on ;~
either side of a terminal ridge edge which intersects and is substantially perpendicular to the longitudinal axis of the shank. Each of the flute means comprises first and second intersecting, substantially lor~gitudinally extending surfaces, ~ the surfaces intersecting both of the bevel surfaces with the i major lateral extent of the first surface extending at an ' angle not greater than 45 to the termlnal ridge edge and thereby forming laterally extending cutting edges. The first '' 15 surfaces comprise a pair of intersecting flat surfaces linear in both longitudinal and lateral directions and both of the pair of intersecting flat surfaces are inclined to the longitudinal axls of th~ fastener with the lowermost of the surfaces being inclined to a lesser amount than the uppermost , 20 of the surfaces. The second surfaces comprises a pair of intersecting surfaces, arcuate in the longitudinal direction with the intersection of -the arcuate surfaces forming an upstanding ridge spaced axially Erom the cuttincJ edges and extending generally laterally -to the lonc3itudinal axis.
The Eirst and second surfaces are disposed at from 92 to 97 to one another to insure proper relief behind the ~; laterally extending cutking edges.
The fluting operations are performed with techniques which maximize saw life and provide a clean and burr free drill .~, ~ -6-.

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- ~363;~7 point conf iguration . For examp1e, the f1uting saws are fed into the blank at a sl:iglltly slcewed catlgle to -the direction of tl~e feecl, thereb~
producing a :rlute which has a pair of surEaces interxecting at an angle slightly gre~ate~r l:harl 90. The ~;kewe(l feed of the snw will . .
provide adequate relief behind the cutting edge of the sa~v. The increased included angle o-E the flute surfaces reduces -the probability that the heel~ or region on the flat beveled sur:Eace circumferentaiall~ .
behind the cutting edge, will drag during the cutting operation. ~uch a sl~ewed fluting cut will also result in a much cleaner removal of ~: . 10 material .

In addition to the skewed cut Oe the fluting saws, the present inv~ntion contemplates rotating the uppermost :Elute CUtt:illg snw so as to cut downwarclly on-the shank. The lowermost Elute Clltt:illg saw is rotated so as to cut upwardly on the shank. This secjuence and relative r otation between the saws and the blanl; elirninates the l~urrs that would be forrned in the critical regions of the drill pOitlt.
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The fluting and pointing operations accomplishecl by the .rnethod and appara-tus described he:rein ancl utilizing the accl.lratel~
timed relationship be-tween the rotation o:E the blank between the F~tation~ and the~ loe~tion ~E the ~tat:ion~ .relative to the tllrret prodllcesa dri].1 screw which is stronger than and capable of e~hausting chip ;;
material eor thieker .materials.more e:eeiciently -tha.n prior art scr~,vs.
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~ n upstandillg transverse ridge in the flute surface opposing the cutting edge serves as a chip breaker surface. The drill screw ' .
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~C.~ " rt O~ t~lod c~nd a~ t~l.3 Or tl~ ve~ltioll al~
ha~-e a millilrli~,cd chisel cclge ~,vhich reslllts in a rllore ef~icient drilling ., o~ r~ioll.

Other oùjects and advantages vf the inventionl,~,-ill become app~rcnt from the following description and thc accor(ll~anying dr~wings.

~3rief Description of the l~ra~,vil~s ... .

Fig. 1 is a schernatic plan view showing the manner in vhich ~' screw blanks are advanced Erom a loading station to a plurality of ;~' worl; stations.
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,'', Figs. 2-5 are clev~tiolla1 view~s of thc l)lanks as they are confi~,~uled following several work ~slatiolls.
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is an cnlarged fragmentary schematic vie-v as taken ,', alQng~ thc litles 6-~; of Ei`ig. 1 and showinK the manner in whicll the ., .
~,~ upper fluting saw engages the scl~ew blank.
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~; Fig. 7 is all enlarged fragmentary schematic vic~v as tal;en ,, 15 along lhe lines 7-7 oE ~ . 1 showing t}le manller in which lllc lo~ver ~, fluting saw e~ngages the screw b'lanlc. ~' ig. ~3 is an enlarged fragrnentary schernatic view as tal;en ;' a1Ong~ li,nes ~-SI of I~'ig. 6 sho~ving~ the sl;ewed feecling motion of the ,, ',~ fl~ lg ~aw~, appearing with ~iyures 1 to S.

', 20 l~ . 9 is an clllarged fragmentary clevational vicw sho~ving thc drill til) rcsultillg from the ~nctllod and al)paratus o~ the ;nvention, ;' ' .

633~7 :- -~i'ig. 10 is an end view Or the drill til~ shown in 1~
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Fig. 11 is a simpliL`ied top plan v;ew c)-t` t~le appalatlls incoxporat;ng the ~features of this invetltiotl.with Figures 6 and 7.

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Fig. 12 is a simplifieà elevation vie~,v of the apparatus as taken in the dircction OI lines 12-12 of Fig. 11 alld deleting the stations intermediate -the loading station 22 and pointing station ~6.
.' , , , l;'ig. 13 is a simplified cross-sectional view as ta~;en along lines 13-13 of Fig. 11.
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Fig. 14 is an enlarged partial sectional view as taken along . , - 10 lines 14-14 of ~ig. 11 showing the driver and clamping means at th~
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loading sta-tion. `
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~ig. 15 is an enlargeà partial sectional view as taken along ~ :
lines L5-15 of l~'ig. 11 sho~ving detaiLs of the driver and clarnping :` :
' means.

Fig. 16 is a serni-diagrammatic view of the drive ~nt~challistn and timing cams associatecl wlth the inverltion.
:' ~ig. l7 is a ~ragmcntary partial cLevational vi~w o~ l:h~ cam plate at the loading station and as talc~n in the direction of lines 17-17 ~j o~ ig. l L.
., , I;'i~. 18 is a schernatic elevational vie~v o~ a rluting station as taken in l:he direction of lines 18-18 of Fig. 11.
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6~3~

] l~ . 19 is a scllclnatic elevational view of a pointi station as tal;en in the direction of lines 19-19 of Fig. 11.
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.I;'.ig~. 20 is a schematic elevclt;orlal view of a pointing . station clS taken in the direction of lines 20-20 of Fig. 1].
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Fig. 21 is a schematic elevational view of a holcl down mechani~;m at a pointing station as taken in the direction o~ lin~s ' 21-21 of Fig. 11.

E~ig, 22 iS a schematic elevational view of the hold down ,. mechanism of the point as taken in the direction o lines 22-22 of Fig. 11.

.: Fig. 23 iS an enlarged sche.matic elevat;onal view of a fluting station, as in Fig. 17, showing a hold down mechanisrn.

., Fig. 24. is a schema-tic elevational view of the loading mechanisrn of the invention and as taken in the direction oE lines 23-23 of Fig. 11. .

:~igs. 25 ancl 26 are top pLan ~cllernatic vie~vs. of tlle lo~ding ... .
mechanism shown ;in :Ei';i.g, 24 i.n a holdbaclc and feeding position, ; r~pectiv~ly.

Detailed Descri.ption of the Preferrec1 Embocliment Referring now to the drawings more in detail wherein lilce numerals have been employed to designate similar parts throughout the various views, it will be seen that the disclosed embodiment ` .

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~ . ~Q633~7 includes a fi~;ed s-lpportirlg~ structure upon ~vtlicil a rotary turrc:t is rnounted lor intern~ittently conveyirlg a succession of blanlis to work stations rnounted on the support structure. I`he rnethod ~, .
descril)ed hcrein and the apparatus contemplated to perform the method utili~es two longitudillally overlapping saw cuts on opposed peripheral regions on the blank, creating a relative]y long flute area.
The longitudinally overlapping flutes are forrned by four fluting stations while the remainder of the drill point configuration is formed ~;
by the remaining two pointing stations.

Method and Sequence of Cutting Operations . .
Referring now to E~`ig. 1 it will be seen that a rotary turret 20 is provided with 12 equally spaced pockets 30 opening~ to the periphery of the turret and adapted to receive a succession of screw ' blanks ~0. The turret 20 is intermittently inde~ed in a manner to be described in more detail herein so as to present the pockets at a succession of seven operating stations. Statiolls 22, 23, 2~, 25, 2O, 27 and 2~3 arc located adjacent the eircular path of -travel oE the turret at precletermilled eireumferentially spaeed po9itions on the strueture supporting the lurret. Station 22 Lneorporate~ the leeding uncl loading .. .
rnechanisms designed to place a succession of blanks in the pockets 30.
A flrst station 23 creates a first, generally longitudinally direeted fluting eut on a sel~ew blank. Static)n 24 ereates a beveled pointing eut on the extremity o~ the serew blank. Station 25 erea-tes a generally , longitudinally extending fluting cut in the same a~ial location o~ the blank as that performed by station 23 but on the opposite peripheral segment .' .

1~3397 oE tlle bl<llll;. Stat;oll 2G creates a l)evel~l pointing cut on tll:? e~lrenlity oE the blank 1'ormlng an cqual but oppositel~ e~;tending~ fla-t surface rclat;ve to that formecl by station 2~L. Statiolls 27 and 28 ~'orrn a final flutitlg cut longitudinally over]apping witll the first fluting cuts S on each side of the l~lanl;. Region 2~) intermediate station 2~ ancl loading station 22 effects the unloading of the i`inished blanlcs into an appropriate receptacle.
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The successive configurations of the e.Ytremities of the blanks 40 as they are inde~ed around the circular path is shown in Figs. 2-5. Each blank has a radially enlarged head ~2 and an elongated shank. Work s-tation 23 will include a rotary cutting saw 33 mourlted for reciprocation into and out o~ intersection with the rotary path created by the turret 20. ~luting saw 33 is inclinecl a predetermined angle with respect to the axis of the screw. An angle of inclination <~f 12 has been fo~nd to be acceptable for saws 33 and "
35. The cutting engagement of the rotary saw 33 with -the exposed extremity of the blank is shown in Fig. 6. This first fluting cut creates a pair of intersecting flute surfaces 44 and 45 with the generally flat surface 'L5 inclined at-the predcter-mined ang'le to the vertical axis of the h'lanlc. The cLrcular conEiguration of the saw 33 cr~cltes general'ly arcuate surEace 44 intersectirl~ the flat surfaces. 't`he slot resultillg '~ from the first worlc station 33 IS shown in Fig. 3. The worl; station ~5 ;~ with saw 35 is identical to station 23 with tlle same configuration of '~ ,......... .
flute surface being Eormed oh the peripheral segment opposing the surface expose~l to first station 21.
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.. ` 1~633~7 ,, ~ 'ointin~ static)lls ~4 and 26 crcate equal, inter~ecting flat beveled surfaces 48 at the extremity of the l~lank. 'I'lle blank con-Eiguratioll as showll in I~ig. 4 is that immediately ~ollowing the last pointirlg cutting ope~ration at worl~ station 2G.
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Work stations 27 and 28 perform another Eluting cut on the blanlc which longitudinally overlaps and is generally a longihlclinal eontinuation of the fluting cut performed at worl~ stations 23 and 25.
;; However, the sal,vs 37 and 38 are inclined at an angle less than that `
of the saws 33 and 35. For example, an angular inclination of 9 ;' 10 has been found to be sufficient at the lower fluting stations 27 and 28.
, A representation ôf the cut perEormed at the lower Eluting stations ,,.: , .
by saws 37 and 38 is shown in Fig. 7. As at the upper Eluting stations 23 and 25, the rotary saws 37 and 38 create a substantially flat flu~e ,;~ surEaee ~7 interseeting with an areuate surface 4~;.
~ , ,~^ 15 In aeeordanee with a fur-ther aspeet o~ the inventiorl, the ~' ' . ,, ,i, rotary saws 33 and 35 ereating the uppermost fluting~ cuts are rotated '~ in a eounterclockwise direction or in a direction that cuts clownwardly ' ~, on the shank. This eutting aetion is shown in Fig. 6. ln contrast to -this downward eutting aetion, the Einal or lower fluting euts perEormed ZO by saw.~ 7 and '3~ own in ll'ig. 7, are er~ated cluring eloc~;wise rotation o~ these saws eutting upwardly on the shanl;. This colnbination ., ~
,'. Oe euttingr actions results in a drilling tip whieh is relatively Eree o~
burrs which wo~Elcl ordinarily be ereated by the milling or sa~ving euts ` using eonventional drill serew manuEaeturing teehniques. The eritieal ! 25 eutting edge regions are burr free in the drill serews produeed ~y this invention.

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1 ~ -~0633~'7 .~
''' 1 A furthcr, important relationship o~ the flutillg saws "~J
3!j, 37 ~ncl 38 to the C;crew blank is shown in Fig. 8. Each of the fluting saws i~; moullted at a work ~tatiorl Ifor reciproc.-ltin~s, movelllent into and out of cutting engagement ~vith the l~lanks. This mo~-ement is in a path as shown by the arrow ~ in Figs. l'and 8. The disc- `' like rotary cutting saws, however, are mounted to be disposed at an acute angle to an imaginary plane B which extends through the central ': axis of the turret and through the central a~is of each of the blanks 40.
Planes A and B are parallel and Fig. 8 shows a skew angle ~ of 2-5 forrned between the side surface of the saw and imaginary plane B, Fluting saws 33, 35, 37 and 38 are slightly skewed relative to their .' path of reciprocal travel and to the radia'l plane extendincP, -througsh the axis of the blank. It should be apparent that the slot crec ted by this cutting act;on will be such -that intersecting flute surEaces ~ 5 as well as 4B, 47 are disposed at an angle greater tharl 90 to one another.
More importantly, the flat side surface o~ the cutt;ng saw 33 ~,vill be ; relieved an angle c~ as it plunges into the blank. lt has l~een i'ound ; ' that such a cutting action results in a prolonged saw life as ~vell as a much cleaner cut. This skewecl relationshlp, of course, may be ,' utilized in both the upper and 'lower Eluting cu-l:ting ~:tations wi-thout af~ecting~ the inclination of the ~;lutin~ saws to the longi-tudinaL a~xis of the blanks.

ln order I;o accuratel~ form the various surfaces comprising ` '~
an effective clrill point, the proper predetermined segment of the blank '' 25 must be exposed to the appropriate work station. lt has been found -that the blanks should be securely clamped Erom movernent durings, ~ '' `' .

-.1 1 . , 1~i33~

eacll of the cutting operations wllile tlle turret is in a dwell collclitioll but must L~e rotated about their axis during movement from one worh statioll to the ne~;t.
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In tlle present invention, the work stations are positioned to be cir cumferentially spaced from each other by 30 or multiples of 30 around the eircular path created by the turret. In the preferred . embodiment, shown sehematieally in E;ig. 1, the first, upper, fluting station 23 is located 60 frorn the loading station 22; the ~irst pointing station 24 is loca-ted 90 from the loading station; the second, upper, fluting station 25 is loeated 150 from the loading station; the second -,i ~
pointing station 26 is located 180 fro~n the loading station; the first, ,:,, lower, fluting station 27 is loeated 240 from the loacling statioll and 7', the seeoncl lower fluting station 28 is loeated 330 from the loacling station. In eon;jurletion with the above preferred relative loeation o all of these work stations,j it is important that the rotation of tlle blanks about -their axis be aecurately timed and coordinated with the loeation ~ , ,, of these work stations. In the preferred embodiment of the invention,the blanlcs are rotated`an arnount equal to 300 in a given clirection for eaeh 30 inerement oE rotation of the turret. It has l)een found that a ~un ancl planetar~ ~ear a-rrangement with a 10 to 1 rakio wiLl prod~lee the required aeeurate relative rotation of the blanks to aehieve the desired surfaee exposed at eaçh work station.

The a`bove cleseribed arrangment will permit the driver bits to properly seat or matingly engage with any eonfiguration of driving surfaee on heads 42. The rotation of the drivers and blanlis about their ax;s an amount greater than 360 prior to the operative engagement of the first eutting saw is an important feahlre in controllirlg the aeeuracy - ;
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c>~ the T)oint~i collfigured .accordillg to tllis invention SillCC' tlliS l`e~turc will illSU~`e firm matillg interenga~cnlent of the driver ~)its witll the ~Irivin~ sur~aces of the heads.
1i'igs. 9 ancl lO w;l'l clescribe more in detail the drill t;p configuration resulting ~`rorn the methocl just described. ~ach flute thus con~igured will have a pair o~ intersecting generally longitudinally extending flat surfaccs with the lowermost surface 'L7 tlis~osed at a predetermined angle, for example 9, to the vertical axis of the blanl;, and the uppermost -fla-t surface 45 disposed at a gre~ter predetermined angle, for èxample 12. The arcuate flute surfaces 44 ancl 46 will ,' , longitudinally merge creatin~ an upstanding transverse rid~,re 51 ~' '- disposed above the laterally extending cutting edges 52. The Elat bevel ,' surfaces 48 formed on either side oE a chisel terminal edge 50 create . . .
'' the proper re1ief behind cach of the cutting edges. It shoulcl be notccl ~j, , .
-that each flat .surface 47 and cutt;ng edgcs 52 f'orrnecl thereby, transverse ,,;: ' ,, the chisel 50 so as to intersect both bevel surfaces 9;8. The cut-ting ~' edges will extend at an angle of not greater than 45 to the chisel edge 50.
," P.idge 51 will create a chip breaking eEfect which becomes irnportant in going through thicker materials. In contrast with the drill tip ,; 20 typified by the 3,125, 923 patentJ the eEEective ~lute length~ oE the screw produc~d ~or El given blanlc size by this invention ~vill be~ lon~er ~ncl the drill tip stronger .c;ince tlle incxeased lengthoEfl-lte does not compromise the web thickness or thickcness of the column of material between flute .
surfac~s at a given axial location ahove the point. ~s noted in the haclcground of the inventioll, ,prior art screws tended to be weak behind the point when a positive rake or a longer flute was desired. As shown in the end view of Ei`ig. 10, the intersecling surfaces ~G and ~17 ~orming e~ach of the flutes adjacent tht? cutting edges are arranged at an angle ,-, .
. -Iri-(3633~7 of approYimatel~ -97 to one anotllcr. This relations}lip has t~le effect of reducillg Illc telldency of the lleel areas 63 to hind~r eE~icient;
dxilling by not providing -the proper relief bchind the cutting eclges.
In addition, the lowermost fluting cut producing surfaces 47 and ~L6 in each flute effectively reduces the length of the chisel 50. Thus, an accurately conEigured long fluted drill point is procluced without compromising the many parameters considered to produce an efficient drill scre~

Goneral ~ssembly of the Apparatus .tl apparatus 10 as shown in Figs. 11-14 of tlle drawings , :
10 incorporatcs a fi~ed table-like struchlre 12 upon which is mounted the ~
,;, .
loading station 22, upper fluting stations 23 and 25, pointing stations

2~L ancl 2~ and lowcr fluting ~tations 27 and 28. ~n unloacling station ) locatecl between station 28 and station 22 is shown in Fig. 1 but not shown in detail because a l;nown construction for ofl-1Oading blanlcs 15 can be utilized with this invention. A turret 20 is mounted for rotation relative to the fixed support and is conElgurecl so as to present an outer peripheral surface frustoconical in configuration. The outer periplleral surfQce oE the turret is p;ro~,~icled with a plurality oE, preferably 12, equally spaced bLank receivirlg pocket rneans 30. Each 20 of these pockets will include a generally elongated seat surface for rec~iving ancl supportirlg one side of the shanlc oE a blanlc alld e~{posing j~ the opposite sicle for engagernent by rotary cutting saws positioned at -`
various stations spaced about the turret. The elongated seat surfaces Eormecl by the pocket mcalls 30 ~,vill l)e SUCIl as to clispose the a:;is of .

.

1 [)6339~ ~
" 1 tl~ Sh~ i ollt~r~/lr~ly rclati~e to the vertieal a~; Or t~l{? turret th~ls utilizing the force oE gra~,-ity to seat and retain the blanl;s at cacll ~Yorlc station. l\ stationary support pedestal 54 is fixeclly mounted to the table 12 sllpportitlg th~ rotary turret structurc ancl a rotatable -table or support housing 88 is mounted on the support pedestal 5~L through the use of ~earing members 89 and 87. An index drive plate 102 .
is fixedly mounted to the tubular stem of the rotatable table 88 for ' --:: , a purpose to be described later herein. An upper housing structure , , 106 is fixedly mounted to the top face of the rotary turret 20 and this , ~. .
10 top structure 106 supports and carries a plwrality of clamping and i~ . , blank rotating spindle devicesi 16. The number of spindles 16 should r.l ' :.
" be equal to the number of pockets 30 and disposed axially above each of the associated pockets so that clriver bit 116 can be operatively mated with the heads of each blank. E~ach of the cutting ~tntions will typically include a rotary cutting saw mounted on i~ spirldle whicll is driven by a suitable electric motor device. The saw, saw sl~indle, associated rrlotor and interconnecting drive machanisms are all mounted on a supporting base structure which is pivotally mounted -to the work table 12 to effect a reciprocating movement o~ the r otating saw alo a given path into ancl out of contact with a blank at eacll station.
,, . ~ , e Figures ll-14 and the more detailed discussions of the mechanisms of each s-tation in the assembly are schematic in nature ;~ and are not intended to be cletailecl engineering drawings and it should be apparent -that one skilled in the art could readilly understand the ,1 25 structure described herein as the description of the invention is consi :leretl, .; .~
, . ~, "
:., .

-1 ~
:, ;

o~339~
, ,' 1 'rlle Loading stat;on 22 l,vilL ;ncludc a feecl rail device 56 which is inclined so as to he perpendicularly disposed to the periplleral surface of the frustoc:onical turret 2n allcl to the blank-recc-~ivirlg pocl;ets30. Thus, the loa~ing of the blanks ;ntO -the pock~ts is accomplished witho~lt requiring that they be cocked in the transition from tlle rail to the pockets. ~n appropriate escapemellt device in the forrn of holdbacl;
and feeding mecllallism 58 is providecl at the e~it e~trernity of the inclined feed rail 56.
':
The first ~ork station 23 includes the rotary fluting saw 33 ~ 0 for forming the upper fluting cut on one side of each blank. This saw - is mounted on an appropriate support structure 61 carrying the spindle for the saw. The base 60 carries botll tlle saw supportillg structul~e 61 and the associated motor 70 and is pivotally mo~lnted on the table 12 in a manner to be described ;n detail herein.

The second station 24 will include a poin-ting sa-v 34 mounted on a supporting structure 65 carrying the spindle for the saw. A base 64 carries both the saw supporting structure and associated motor 66 and is pivc)talLy mounted on table 12 in a manner to be descrlbecl in ,, ~
detail later herein, 'rhe third station 25 including a second, upper flllting saw 35 with the associa-ted saw mounting structure 69, base 6~ and motor 70 i~ iclcn-tical to l~le ~irst station 23.

,, .
. .

, . .

633~7 'l'he ~ourth s-tation 2~ is a poinling station incl~ding a .:
. pointing sa~/ 36 w:ith associated saw mounting struclLlre 73, base 72 ancl motor 7~i alld is identical to the second station 24, ~:

~:. The fifth and sixth stations 27 and 28 per~orm the lower .: .
fluting cuts and are substantially identical to upper fluting stations 23 and 25. Station 27 includes a fluting saw 37 mounted on a support structure 77. A ba;,e 76 carries both the SQ~v supporting structure ~
and associated motor 78. Base 76 is pivotally mounted on the -table ;.:
12 in a manner to be described in detail later herein. Station 28 is ~ :
; . ~ .
identical to station 27 and includes a rotary saw 38 with associated :
saw mounting structure 81, base 80 and motor 82.

~n appropriate blank unLoading station 29 is util;ize~l .in thc : .
invention but the cletails of this sta-tion are not shown. in that it should be apparerlt :Erom the prior art how such a loading station is conEigured ' 15 in an apparatus of this type.
,............................ . . .
Turret Indexing and Work Station Control .. . ..
~, . .
~s best shown in :Fig. 13, the turret 20 and spindle carrying structure 106 arc aclaptecl to be intermit-tently indexecl through the use :;
. . of a driving barre~l ca.m element 100 and a driven index plate 102 carry-ing a plurality of cam followers 104~ Such right angle. indexing mechanisms are conventionally used to produce intermittent motion about a driven ~;haft. Index plate 102 is fixedly secured to a tubular portion of rotary .
support table 88 and disposed generally perpendicularly to the vertical axis of the turret. The turret 20 may thus be accurately intermittently '., ' '''.

... . .
' i .. ~
'~
- 2 ~ - .

. ~6339'7 ' :rotat~d to ~ ~;ucc~ssion Or peri~h~r~l wo.rl; stations througrh th~ i~lt~`f'-engagelnerlt o.f cam 100 and cam followers lO~L. The driving and timing~
,, .
control Inechanisnls for the turret ancl the work stations are a series of accurately interrelated rotary cam surfaces mounted on a common s 5 cam sha~t. Reference to ~'ig. 16 will show that a primary energy source, such as an engine 31, provides rotary input power~ to a shaft - 32 which is transmitted to a primary drive shaft 146 through a right ~ angle beveled gear set 142 and 143. ~ suitable brake 140 may be provided externally OI the structure for safety purposes. An over-load clutch 148 is disposed between the primary power input and the local drive elements. Power drive chain 152 interconnects sprocl;et 150 with sprocket 121 mounted on a carn sha~t 120 antl ~he rotary power is tllereby transferre(l frorn the prirnary sha~'t 1'L6 to the cam ~,. . shaft 120. The d:riv.ingr baxrel cam 100 is secured to the primary ~, 15 drive shaft l~LG for its operative assoc;ation with the indexing plate ~;~
102.
.. . .
Each of the six sawing stations is controlled to move its associated saw into cutting engagemerlt with the blanli duringr the dwell per.iod of the intlexing turret. In addition to timing the reciprocating 2t) movernetlt o~ the ~w sllppo.t~ting ~tructures, the commotl calrl shaet 120 also carries several rotary cams which time the increase in , .~ .
elamping pressure exertecl by the drivers at each 5tation, control the blank loading apparatus, as well as control the mechanisms designed .;
to create a lateral hold down pressure on the blanks at the pointing :.
stations. In the embocliment described herein 10 di:f~erent cams are '~ ' .
. ' : . ~:'. ~

~33~7 ~:
.~...

shown, eacll c:olltrolling a se~arate rnechanism in thc apparatus. For exarnple, cam 1~2 controls a cam plate 14 which perioclically creatcs additiotlal axial clarnping pressure on the blanl;s. Cams 12~.~ and 126 .:; . control the activat.ion of the ~Ipper fluting stations 23 ancl 25. Cams .. ~ ::
., : :
128 and 130 control the activation of the lower fluting stations 27 and 28. Cams 132 and 134 control the activation of the pointing saw stations 34 and 36. Cam 136 controls the escapement or loading .' device and cams 138 and 140 control the hold down devices which .. provide lateral pressure applied to the blanks at the pointing stations. :
.: ' ' ,',' ' ~ Blank Clamping Rotation and Hold Down Mechanisms . . .
.~ ' .
A. better understanding of the devices utilized in this invelltion .. l to sccure the blanlcs in their respective pockets and to orient the proper ?redeterminecl segment of the blank extremity to the associated work , station can be obtained with reference to :Figs. 13-15, 1'7, 21-23, :,5, ;:
'.! . I , .. Upper housing section 106 carries a plurality of, pre~erably `:
; 15 12, driver or spindle units 16. Each of the drivers 16 is positioned .
~, to be in longitudinal aligmnent with the pockets 30. The a~es of the drivcr units 16 are genera:l.ly parallel to -the longit~ldinal a~i~; o.~ the turret while the b.lank suppor t ,~urface crea-ted by th~ pockets. ~0 ~
inclined. I'his arrangement allows the spinclles to e:cert for ce on the yl 20 head o~ the blanl;s in a direct.ion which inherently aicls in holding the k?lank ag'ainst theinclined seat surface.

.
The driving bit 116 associated with each driver unit 16 is in constant contact ~,vith the head of the blanks as they are conveyed ' , . . . .

.: - 2~-.. .. ,~ . , . . , , . . ~ . . , about t~le circ~ r p~Ltll. :Dr:iving b:i.t 1:L~; is stlowrl as including ~ (~ross ,.~ blacle configuration adaptecl to be complcmentary to a gerlercllly cr uci-form intern~Ll clriving sur.Eace in the head 42. IIowever~ lt shoulcl be . apparent that any type of clriving bit can be utilizecl to accommodate any one OI a variety of heacl configurations. ~ variable clamping pressure is exerted do~,vm,vardly Oll the blanks through a cam controlled mechanism shown in Fig, 13. A substantially circular cam plate 14 is secured at i :
an upper extremity of a shaft 90 which extends through the vertical axis ,~ of the turret 20 and support pedestal 54. The shaft 90 and ca.rn plate 14 ~ r ~'i 10 are fixed from rotary mo-tion but are adapted to reciprocate in an up and .. down axial motion rela-tive to the turret. The reciprocable motion isprovided throu~h the use o.E a rotary plate cam ~ 22 secured to the common cam shaft 120. ~ linlc 92, which is p:ivotally .mounted at one encl to a ,, `~
v fixed pivot structure 94 and associated with the :Eree ex-tremity of shaft ., 15 90 at its o-ther end with a U-shaped yoke 93 and carries cam follower 91 cooperating with cam 122. As the cam shaft 120 rotates, the carn 122 wilI periodically pull the shaft 90 and canl plate 1~ down relnti~e to the ,'X table 12 due to the ~ownl,vard fo.rce exerted on roller ~S fi~;ed to shaft 90 by yoke ')3. ~ large circular sun gear ')6 is nonrotatably mounted on 8haft 90 so as to be eoncentr;e with the turret for simul-taneo-ls driving :~ ene~é~gemerlt wlth al:l of tlle sma:llcr planetar,y gears 98 rr.tounted on each of the spindle units 16. The sha-ft 90 is secured frorrt rotation by bar means 97 secur~cl to a flat re~ion of slla:~t 90. :E~ar means 97 is fixecl to a square clowel 99 mounted for reciprocation in bearing means 101 in : 25 table 12.
'~ `.
Each of the 12 spindle units cor~prises a cam follo~ver 108 :~ rotatably mounted on the upper extremity of a shaft 109, I'he upper " :.

~' , ' . ' ' ~' "` ~, 633~7 ~ ~

llousing str~lchlre ~06, which carries each driver abo-lt the circular path with the~ turret, includcs a lower abutment surface~ and an ~ ;
upper stoI~ sl1rface 107, A radially extending flange 112 Integr~al with shaft 109 i9 positioned intermediate the shaEt 109 and the Ciilln follower 103, A relatively strong compression spring liO is positioned about the .,,~ ,~ .
shaft lO9 anci into abutting engagement with flanges 112 and 114 to exert '. a strong upward force on the spindle relative to the support structure.
The spring 110, thus, acts as the force which returns the shaft 90 and cam plate 14 to its upward position when the low profile of the rotary cam 122 is aligned with the link 92. In operation, the cam plate 122 ,. rotates in timed relationship with the rotation of the turret so that at each dwell period of the turret the carn plate 14 is pullecl downwarclly causing the spinclle lff to move downwarclly, incre~sing the clamping '.'1 . ' ' ' press~lre between tIle bi-ts 116 and thc heads of the blanks at each worlc ' 15 station.
~' ' ` ' ` .
As the turret is rotated between work stations, upper support structure 106 carries the spindles around the vertical a~is of the fixed sun gear 96. The interengagement of gear 96 with each oE the planetary ., gears ~9~3 causes the spinclles to rotate about their OWII axis clurin~ :

20 movement rrom one static)n to the ne~ct. Xt has he~en ~ouncl tI-I~t a e~eRr ~ ~ ratio Or lo to 1 between gears 9û ancl ~6 creates the desired 300 .; rotation of the blank relative to a 30 rotation of the turret. Since the incle?xin~ m~?chéIn-l~m 100 ~nd 102 provid~s a dwell period at each worl;

A';'. station, the blarlks will be locked against rotation at the work stations.

;,, .
A more detailed description of a preferred embodiment of the spinclIcs will be obtained with reference to Fig. 15. Since each of ` ~
` ' ,~ ., ' :
' '`

_ ~>, l ~- ~063397 ., .; 1 -thc s~in~lLes is idcntical, only onc unit ~vill be descrii~ed in detail. The shaft IO~J describecl broaclly above may comprise an outer sleeve 156 fi,Yecl to the upper support structure 106 artd a reci~rocable tubul~r ~, body 15~l integral ~vith the flangc 112 and cam follotv~r securem~nt ,` 5 head. Tubular body 154 is telescopically moun-tecl with outer sleeve 156. A shaft 158 is axially positioned with and .~ecured to the tubular '. portion and extends downwardly for operative compressive engagement with a plunger 162, The plunger is reciprocabl~y mounted ~vithin a lower s tubular memher 98. Lower tubular member 98 includes a plurality of axially extending splines on its external surface creating the planetary ~,, gear in operative engagement with sun gcar 96. The lower end of .' tubular gear member 98 is provided with a bore for receiving the shank of a driver bil: 116 retained therein by a set scrcw. 131elnc:nt ~$ is mount~d for rotat:ion relative to the support structure 106 and shaft 15() by bearings lG4 ancl lff6 and is a~;ially secured to support structure .', 106 by retainer nuts 172. A shaft 160 extends do~vnwardly from the plunger head 16~ and is encircled by a pair of springs. An innermost light, spring 168 and a heavier outer spring 170 is positioned betvween the head Or the p:lung~er arld the ba~e o-t' thc tllb~llar bit carryitlg clev;ce 98, ~tl aclju.c3ttrtcnt ecc,ent.ric 118 car.r~yin6r the fol:lower 10~ perm.its the '~ ' pre'load on sprillg' 170 to be adju~tecl.

,. .
.. :
.The borc: 173 in retainer nut l72 is of a cliameter sufficient lo a'llow a cer tairl amount of 'lateral movernent o:t` the tubular member 98 ,. relative to the f.ixed structure. This structure in conjunction ~ ith the ,, 25 point contact provided by ball bushing 166 permit9 the bit to center itself to com~ensate for tolerances in the head conEigurations. l~ig. 15 sho~vs .; -the spindle at thc dwell period oE the turret.
, . .

106339~7 ~
Thc a~ial posilioning o~ cam plate 14 ancl control ~haft 90 is timed to l~e in an upward position during the indexing of blanks Erom one 30 incremcnt to the next. During tllis indeAYingr period, the inner- `~
most spring lG8 in tile lower tubular member exerts a slight a~ial S pressure on the bit carrying structure 9~3 which facilitates the rotation of the blanks about their axis between stations. When the turret is m its dwell period with a blank opposing a wcjrk station, the control cam 122 forces the cam plate 14 to move downwardly which, through ;
.~, . .
the interaction of shaft 15S and plunger 162, causes the heavy spring < ~ -170 to exert a much greater force on the driver bit 116 to rigidly and securely retain the blank against rotation and against the pockets during the cutting operation. It has been found that an inner spring ;i! with a force of five pounds and an outer spring with a Eorce ot two hundred and fifty pounds accomplishes the purposes of this invention.
;:, Cam plate 14 with a flat undersurface 176 acts on the spindle 16 through cam followers 108 to exert a longitudinal clamping pressure on the blanks at all positions along the circular path. Mow-everJ it ~hould be notecl tha-t the carn p~a-te 14 is configured to have a ', di~continuity in the region immediately above the loacling ~t~tion 22.
.. . .
ao ~s shown in L;'ig. 17, the~ ~ide view of' thc cam plate in this area comprises a tapered camming surface 174 leading to an aperture or .slo-t 175 in the plate 14. '.rhe dotted line configuration of F'ig. 17 shows this regrion of the cam plate during tlle indexing period of the turret. ~;
As shown in Fig. 14, this permits the driver spindle 16 ta be forced upwardly under the compressive force of the spring 110 so that the ., ~ .

. .
- 2~-, . , ; , . ~.

- 1~6339~
~,;
.. 1 drivel bit ]l6 ck?ats the b]ank receivillg pocket 30 at the loac~itlg ., statiol~ 22, permitting cntry o~ blalLl;s into the rotary path. Snap ring 167 and l)earing 164 coopera-te to properly retract the driver bit 11 G, ,.... .

In additlon to the a~ial or longitudinal clamping pressure ii provided by the spindles at each work station, it may be advisable to r~;
provide a laterally directed hold down pressure against the shanks during each cutting operation. At each o~ the pointing stations 2~1 :
and 26, the blanks are laterally retained by a mechanism such as ,:
that described in Figs. 21 and 22. The hold down mechanisms at these point;ng stations are again timed to be synchronous with the :"
. . - cutting engagement of the cutting saws 34 and 36 during the dwell period of the turret. For this puFpose, a pair of rotary plate carns 138 and 1~0 are secured to the common cam sha~Et 120. Since both . 15 of the poi.nting hold down stations are identical, only one o them will be described here:in in detail, .; A hold down Einger 204 is mounted, in a manner which would facilitate longitudinal adjustment Eor different shanl; lengths, at the upper-~` most extremity o:E an oscillatory shaft 206 whicLl extend~ througtl the , 20 table structllte 12 and is supported tllereitl b~ a ~;lee~ve beari~ 0~, The oppositc or :lower ~.?xtremity of the~ shaft 206 is operatively secured to a laterally extending l.inkage 210 which in-turn is secured to a generally ho:ri~ontally extend;rlg l;nkage 212 which is pivotally secured to ~ cam ., fo:llower linka~s,e 21~ e linlcage 214 is pivotally secured to a stationary structure by a support means 216 so that the cam follower 21~ is mounted ... .
i . . ..
., ~
.' .

. ~
'.' ' . : . ~
. .

;, ,:,.
Oll one side of the su~port n-leans and the connection with linliage 2l2 is on the op~osite sicle oE thc pivot support structure 21~ tension spril1g 220 is operatively connected to the extremity of linhclge 21~
! ~ opposite the cam follower 218, and resiliently secures linkage 214 ,' ~ 5 to a stationary structure. In operc~tion, the cam 138 is timecl so that the low profile of the cam contacts the cam follower at the same time as the d~vell period of the turret. Tension spring 22û thus causes the linkages to assume the positions shown in Figs. 2l and 22 which create a lateral compressive force against the shank of the blank. During the . . -indexing of the turret, the cam l38 causes the linkages to rotate -the finger 204 outwardly from the turret permitting the next blank to be indexed for pointing operations hy saws 34 and 36.
.,, :.
~t each of the four described fluting stations, a blank hold do~n clevicc may be mo-lnted on the support structure caxrying tlle saws 33, 35, 37 or 38. Since such a hold down structure may be identical in each oE these four stations, only one such struct-lre will be described in detail. With reference to Fig. 23, it will be shown that a stationary block 228 may be providecl on saw support structures `
61 so as to be located grenerally above th~ saws. The block is providecl wL~h a throll~h bor~ int~ which El slla~t 22~ is pc~sitionecl alld carried.
The hold down shoe 222 is secured to the extremity of the shaft closest to the saw and a compression spring 230 positioned between the block 22~ ancl the sho~. l'he opposite e~ctrernity of the shaft extends through '; the block and may be provided with an adjustable nut member 2~6 to control the point at which the shoe engages each blanlc for di~ferent saw ~f '''' ''' ;, .
~ ' .
~ 2 ~ -1~i33~7 ":, .~. 1 diameters or bl~nk diarneters. In operation, t~le outcrlllost e.~:trerni-ty '... o:E the shoe 222 prccecles the associatecl cutting saw in engagenlt!nt wil:h ~'. the blanl;, prov.iding a resilient lateral clamping force on the blank :,: prior to ancl increc~sirl~f during the cutting operation o~ the saw.
,,,; .
Fluting Saw Stations .. . .
' ~ 5 Worl; stations 23, 25, 27 and 28 are provided respectively with rotary cutting saws 33, 35, 37 and 38 mounted on an appropriate reciprocating structure. Each of the Eluting stations are substantially identical and thus only one station will be described in suhstantial ^' , ',~ deta;l. Upper fluting stations 23 and 25 differ from lower fluting '.
''~ 10 stations 27 and 28 only in that the upper fluting stations dispose the ,... .
,. eutting saws at a greater,angle with respect to the axis ol the screw ., , . .
"" than the angle at which lower fluting saws 37 and 38 are disposec'l.
."
Fluting station 23, shown in schematic form in Fig. 18, includes basically a 'bas,e 60 which is pivotally mountecl to the table ,;.
support 12 by a piuot bracl;et 178. The base 60 includes an upstanding ,,~ support structure 61 which carries the spindle for rotary saw 33. The, motor 62 is not shown in Flg. 18 since the means for mol.lnting and ,~
operatively associating the motor with the saw is well ,known in eonv~ntionl'l corlstr~letion. It ~ufeie~s -to ~tate that the motor will be ~:
:... 20 structurally mounted to the base and ~,vill be movable therewith. The ,, ,... . .
,. pivotally moun-ted base 60 enables the rotary eam 12~ moutlted on cam ~.
~haet 120 to eEfeet the reciproeating :motion of the saw into and out of cutting engagement with the blanks. A :linl;age 18~ is pivotall~ mounted ,',; to a support structure by a br~aeket l~L. One e~;t~emily o~ lhis pivol ., , s , , ' ,'. .

~C~63397 ? I linl;age carrie~ a cam ~ollower 18f) and -the otl-er e~;tremity i.: p;votally connected to an up.standi.ng linkage 180 which is in turn pivotally secured to base 60 at a position laterally spaced frorn the pi.vot structure 178.
A strong compression spring ~88 is interposed between the base 60 and the supl)ort table 12 thus provid:ing the force for moving the saw in~vardly into cutting engagement with the blank durlng the dwell period of the turret 20 which is synchronous with the engagement of the cam follower . 186 with the low proEile on the cam 124. The engagSement of the high :.:
~; profile of the cam 124 with the follower retracts the saw support ,.. ~,; .
`. 10 structure 60 against the compressive force of the spring 188 to the -`~: position generally shown by the dotted line in Fig. 18. The profile of .: :
.~, cam 12~ should preferably be designed so that the inEeed velocity of tlle .j,; ` .
sa~-~ is sul~stantially constant during cutt;ng to proclucc constant ch;p .; siY.e. The infeed velocity should be reclucecl near the erld of the strolce to ,.. . . . .
.;: 15 providc a smooth cut and a clwel:L should ~e provided so that at least one full revolution of the saw is accomplished to cancel an effect the - .
~;~ eccentricity of the saw may have on the cuts.
~'' ' .
; In order to facilita-te accurate positionment o~ the saws vertical and lateral adjustment means (not shown) may be provided . 20 at each :fluting ~tation using Icnown construc-tion ~or such mea ~r :.: Pointing Stations , . . .
.i,~. .
Thc two ~)ointin~ stations 24 and 26 are shown schematically .~................................................................. .
in Figs. 19 and 20. Since the pointing saw s tations are identical only ,;~,. .
~; station 24 will be described in substantial detail. ~ach pointing stcltion ;.

~' ... ........................................................................ .
~ .
., .
:.,:, ~ :

- 3 O-~S~633~7 :
~,~,ill incluc]e a support bclse 64 whicl~ is pivotally mounted to the worli table l~ y a br~lcket 190. ~n upstanding support structure 65 rnounts and carries the si~indle for pointing saws 3~ so as to dispose the saw at the precise angle required to create the desired ~eveled surface 48 at the extremity of the blank 40. I'lle motor G6 is not shown in ~'igs.
19 and 20 since the means for mounting and operatively associating a motor vith a saw is well hnown in converltional construction. ~t suffices to state that the mo-tor will be structurally mounted to the base and ~vill be movable therewith.
:

As in the flutlng stations, the pointing stations are timed to pivotally reciprocate into and out of CUttitlg engagement ~vith the path created by the turret 20. However, due -to the cutting action de~ired ¢ at the pointing stations, they are con~igured to rocl~ the saw structure .,~ , . :
`, back and forth into and out of tangential relationship with the worli path.
15 The roclcing motion of the saw support structure is again controlled ,~ ! .
by a rotary cam 132 af~ixed to -the common cam shaft 120 and by a compressive spring 202 interposed between the support base 64 and the support table 12. Linkage 194 is pivotally mounted to a s~lpport , bracliet 19~ to the f;xed structure 12 and carries a cam follower 192 20 at one extremity cand i~; secured to an ~Ip~;tandln~ linlit~e 1~36 tlt tlle other e~;tremity. Linkage 19G is pivotall~ securecl to the ~Indersurface of suppor~ structure 64. Again it w;ll be apparent that the low profile Oe the cam 132 is timed to oocur during the clweLl period of the inde~ing ~`
turret. ~t this moment, compression spring 202 forces the support ;~
structure 64 to pivot into cutting engagernent with the blanli Ll'O~ The support structure is in essence a bell cranl; type mechanism ~,vith base 64 cxtendin~ in one direction from pivot 190 and saw support 65 , ` ' .
I ................................. .

. ' . ' . ' ' . ' , " . .' ' ' " ' ,' " '.' ' . ' ' ' ' ' -' ~063397 . 1 e~tendin~ in anotiler directioll. Wl~ile thc turret is l)eing in(le~ cl .. from one dwe:l1 to the ne~s-t, the higher profiles o~ the cam take eLfect .
~.......... and pull tllc s-1pport table 64 down, wllich in turn rernoves tlle c~ltting : .
,,~ saw frorn engagernerlt ancl frorn tht? :rotary worlc path as shown in .j,, . ~, . !
': 5 dotted lines of F'ig. 20. The saw 34 passes the blank completely ,........................................................................ .
. ' and waits for the turre-t to index to avoid cutting the same s~lrface on its return s-trol;e. .

As in the fluting saw stations, the pointing saw stati~ s may .~. be provided with vertical and lateral adjustment means (not shown) to .~ 10 facilitate accurate positionment of the saws. . ~`;
." . ,~ .

., Blank Loading Station succession of screw blanks ~0 may be ef.Eicierltly ancl ~, synchronously loaded from a hopper (not shown) inlo successive poclcets ~, 30 on the t~lrret with a feed track 5~ and an escapement rnechanism 58.
The hopper and feeding track may be of various and kno~,vn construc-tions ~'$,,~,' 15 and thus need not be described in detail herein. The escapement .mechanism 58 is shown schematically in Figs. 2.~-26.

~ -Eeed lever 232 and hold back or gate lever 2S~ are each ~'; , ' ' ;' ~, indepe~ndc.nt.ly pivot11ly mounted to a common pivot bracket i46 on the tab:le~ 12. Tlle fe~ed levcr 232 comprises an uppermost feecl finger 2~8 . 20 e~tending laterally of the upstanding lever, a oot 254 extending laterally in the same direction a~; tlle finger 238 and creating a ~ell cra~ arrange- .
,, ,~ " ' ment in conjunction with lever 232. ~n intermediately positioned :~
abutment surface 244 extends from lcver 232 toward the opposing hold ;.~. baclc lever 234. :EIol.d back lever 234 includes a ga-te-like finger 23G
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; . 1 at the ul)l)ernlost e~tremity and whicil is positioned hetween the ,uocl;et . .
30 an(l tlle inwardly extending extrernity o~ the feed finger 240. As shown in 1~'ig. 25, the llold back finger is positioned to retain the .: blanlcs from moving into the rotary patll until the escapement mechanism is activated by thé rotary plate cam 136. ~t the dwell period of the ~ turret, the low profile of cam l36 allows a tension spring 266 to pivot :~
.i a bell crank elemen-t 264, 25~ which carries a cam ~ollower 262 at one . , , arm extremity and pivotally carries an upstanding linkage 25G on the :~
.... i .
other arm adjacent the spring connection. Spring 266 is connected to .,.~ .
a stationary structure, such as table 12, so that w~len the low profile ~,. of cam 136 is in interengagement wi-th the cam follol,ver 262 tlle spring .~.; creates a downward force on link 256 and thus the foot portion 254 of ~`
i. the feed lever. At this period in the cycle of the apparatus, the feed ,................................................... . .
', finger is pivoted clockwise as shown in :E~ . 24. This pivotal move- `.
~r 15 ment causes the hold back lever 234 -to move in the same d;rection '~.' -through the engagement of the abutment surface 244 with adjustment ~;~ screw 242. The motion o:f the hold back lever 234 is against the bias . . .
~: of a hold back spring 2.52 connected to pivot bracket 246. The relative ~
, , lateral locatio.n of the hold back lever to the pivo-ting braclcet when in ,; , ~ 20 the hold back mode of I~ig. 25 i~; controlled by adjustable abutment .:
.'.j screw 2~8. Lilcewlse, the rel;~tive lateral :loeation spaclng ~etween .. lcver elernent~ 232 arld 234 alldJ in erfect, the overlappirlg extent of ' . cam~:ning surface 240 and pocket 23t6, is controlled by adjustment se.rew 2~2. At the clwell pe:riocl o:f the turr~t, the eamming ~ur.face .; I . :
~ 25 2~0 on finger 233 forces the ne~t blank into the pocket 30 as shown ., ~
;. . ~
clearly in ~lig. 2G. Upon the return cycle, -the gage member 236 will '';: .~ ,', .. . receive the ne,Yt gravity :fecl blank for subsequent similar operations. .. -:

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~s suggestc(l ear1ier~ tl~e driving spinclle 16 m~lst bc r~tractc~l up~vardly at ttle loading s.tation 2~ so the blanl;s may be ,.' properly seated in the pockets 30. ~gain referring to ~-'igs. 14 and 17, it wil~ be secn that spindle 16 is resiliently urge~ upwardly into ,: :
', 5 the slot 175 formed in the cam plate l~L, permitting the free entry of ', ,'. the blanlcs into the pocl~ets at loading station 22. , :;.; :
blank removal station 29 is positioned between the loading r.': :
~,' station and the last fluting station 28. The structure of s~ch an off- ., loading devicc is not shown as any varie-ty of known construction for .'.
',., lOsuch devices can be util,ized within the spirit and scope of this invention.
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1., Summary of ~pparatus and Method ., . ~
'~.' The appa:rah~s and method just describecl utilizes a rotary ' turret with a plurality of blank receiving poclcets spaced dircumferentially , ~, about the periphery thereof. The blanks are clarnpingly retainecl from ~; movement at each clwell period of -the indexing turret. The blanks are lS also rotated about their own axes during movement from one dwell ~, station to the next to accurately e~pose the appropr;ate 1~1ank peripheral ,, . .;,' surface to a rotary cutting s-tation. A first gcnerally longitudinally `
fluting cut :Ls made on each ,side OI the blank at a predetermined ,' ' inclinatioll rc'lative to the ax:i~ o~ the b:lanlc. S~cond, lowe;r, fluting cuts are made on each side of the 'b'lanlc at a di~':ferent' and lesser .,1 , . . .
,'1` incl,inations to the vertical axis of the blanlc than -the first fluti.ng cuts '' .l ancl lon~ituclina~L'ly ovcr'lapping the first cuts. :Pointing stations are '' located about tlle circu:lar path to form intersecting flat beveled :
'; surfaces wh;ch cooperate with the fluting cuts in a ~no~,n manner and - 3 ~L -,.

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create a properly desi~nccl clr;1l point. rl~he advant~ges of the rnethod descril)ecl by lhis invention are the capabilities of obtaining an effectivc ,. ~ flute lengtll which is longer -tl~an prior art and yet provide a strong and ,i carefully engineered point s-truct-lrc. Thé method just dcscr.ibed also ;~1 "
provides a highly versatile and efficient productiol-l apparcltu~ for producing cril:ically en~ineered drill screws which do not require a compromise o:E any parame-ters tracli-tionally used to define the geometry ~.,.,~ .
., of the drill screw. -~'~,; ;
;, The rotation of the uppermost fluting saws in a downward direction on the blank and the subsequent rotation o~ the lol,vermost :.
,.;~ fluting saws upwardly on the blank create a flute and cutting edge which . is substantially free of burrs. In addition, the skew angle at whicll the fluting saws engage the blanlc produces a clean cut and lcngthcns the saw life by providing a clearance angle betwecn thc cutting edge .. j , .
and side of the saw and provides an intersection of :f.lute sur~aces at ...
~ ' an angle of between 92~and 97 whicll is beneficial in reducing the `.~.' drag on the drill screw.
.,~ '~
While the apparatus has been.described in subs-tclntially ';, schematic for.m, it should be apparent frorn one skilled in the art that ~.
" 20 there are various well known constructions ancl engineerin~ techniques `~
;~ I wh.ich could be util-.iæecl to make the apparatus, but fox purposes of . . .
`;.:, clarity ancl ease oE understanding, s-lch details are no-t deerned necessary.
.,., ~ . .
.. ,,~ . . . .
~n advarltageous .Eeature of the structure described herein is the cam and spring relationships in each of the si~c sawing stations `, 25 as well as the clamping mechan;sms and hold down stations. Each o~

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`' 1 these C:arll actival(cl stations and rm(!cllanisms utili~e a resilicnt spring force to ploduce the ~vorking portion of l;he reciprocating strol~e and :.-,' uti:lizes the rigid mecllanical cam to return the stcltion or,device out !~ of operative engageament with-the b'Lanks. I'his will insurc that jamming, ', 5 cocking or other misalignrnen-t problcrns will not seriously damage or ; harm the elements comprising the apparatus.
.~ . ,.
.` It should be apparent that the angular relationship of the ,. :
~, rake angles produced by the four fluting cuts may be varied to suit .~,',~ particular require~nents and still be contemplated by this invention.
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While the preferred embodiments of the present invention have been shown and described herein, i-t is obvious that .many s-truct~lral . details may be change(l without departing fronn the spirit and scop~ of ~,', the appended clai.ms.
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Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A self-drilling screw comprising an elongated shank, an enlarged head at one end with means cooperable with a tool for turning the screw, the elongated shank including a threaded portion intermediate the enlarged head and an entering end portion of the shank, a drill tip formed on said entering end portion including a pair of oppositely disposed, generally longitudinally directed flute means extending upwardly from and intersecting a pair of flat bevel surfaces formed on either side of a terminal ridge edge which intersects and is substantially perpendicular to the longitudinal axis of the shank, each of said flute means comprising first and second inter-secting, substantially longitudinally extending surfaces, said surfaces intersecting both of the bevel surfaces with the major lateral extent of said first surface extend-ing at an angle not greater than 45° to the terminal ridge edge and thereby forming laterally extending cutting edges, said first surfaces comprising a pair of intersecting flat surfaces linear in both longitudinal and lateral directions, both of the pair of intersecting flat surfaces being inclined to the longitudinal axis of the fastener with the lowermost of said surfaces being inclined to a lesser amount than the uppermost of said surfaces, said second surfaces comprising a pair of intersecting surfaces, arcuate in the longitudinal direction, the intersection of the arcuate surfaces forming an upstanding ridge spaced axially from the cutting edges and extending generally laterally to the longitudinal axis, said first and second surfaces disposed at from 92° to 97° to one another to insure proper relief behind the laterally extending cutting edges.

2. The self-drilling screw of Claim 1, wherein the lowermost of said first flute surfaces are inclined backwards from the cutting edge approximately 9° and the uppermost of said first flute surfaces are inclined backwards approximately 12°.