CA2075710A1 - Form drilling or turning device - Google Patents

Abstract

(57) Abstract The invention concerns a special device for producing by machining a multi-plicity of shaped bores or shaped external surfaces, such as squares, hexagons, el-lipses, polygons. This is done by superimposing a forced radial motion, produced by purely rolling-action elements (12, 13, 14, 15), on the rotational motion of a tool hol-der (3) in such a way that the cutting edge of a tool (23) inserted in the tool holder (3) follows the required path as the tool holder rotates. Unlike other methods, such as broaching and floating-tool broaching as well as erosion machining and milling, the device proposed enables shaped bores and external surfaces to be produced not only cleanly and to the required tolerances, but also very rapidly and simply. The form drilling and turning device proposed can be used on normal drilling and mill-ing machines and machining centres, as well as on turning machines with powered tools.

Description

2~ 7~) WO ~2J10330 PC:T/DE91/00~3 Form dril ling or turninq device The in~ention relatec to a form drilling or turning device co~ei~ting of a drive sha~t, a fixed housing and a tool holder which ls constructed to accom-modate a tool ha~ing at lea~t one cut~ing edge, the drive sha~t and ~ool holder ~eing mounted rotatably in the housing and connected i~ such a way that during operation a rotational force compo~ent is transmitted from the drive shaft onto the tool holder ~ut the tool holder can ~imultan~ou~ly be deflecte~ in the radial plane, this deflectio~ being controllable for the purpoge of ~ontour production by means of control elemen~s as~igned to the hou~ing and the tool holder. This d~vice can be used for the produ~ion by machining o~ shaped bores or external con~ours of ~pecial sh~pe, or example ~quare, hexagonal, oval, elliptical or polygonal ~hapes.
Such ~hapes in bores or on belt~ are u6ed in eng~neering ~or the mo~t varied applications and in very wid~ly differing geo~etries. The ~ocket hexagon in ~he heads of screw~, for example, axe generally known and wide~pread. Onl~ m~tal-orming processes, such as cold-LmpaCt or hot-impact extrusion, for example, come into consideration for the mass productLon of such scr~ws, because such processes achieve e~ectively u~able surface~ in conjunction with t~e lowest co~ts per piece.
Matters look otherwise when smaller numbers o~ piece~ are required, or when the particular component doe~ not permit such a metal-orming process. In general machine building, above all, there is the need for the most varied shaped bore6 or external contour~ o~ components to be produ~ed by machinlng. Here, it i~ usual with reference to ~haped bore~ to have recour~e to broaching or shaping, and in ~ome case~ also to ero~ion machining or to fo~m drilling by mean~ of a template, while for the producti~n of externa~ contour~ con~lderation is U~UA11Y

given to production u~ins mil~in~ techn.i~ue~ Z~7 Generally ~pea~ing, the ~tarting point in the broaohing or ~hapin~ o~ ~haped bores, and in floating-tool broaching, aB well, i6 a more or le~ ~trongly fluted ~urface of the shaped bore. The dimen~ional ~tabllity o~ a bo~e produced in thi~ way is moderate.
Increa-~ed ~ear of the internal broach occur~ in the case o~ mat~rials of higher strength~ In addition, with blind bores there i8 the disadvantage of the occurrence of rubbing chip~ that have xolled in.
The erosion machining of shaped bores lead~ to excelle~ resultc, ~ven in hardened materials~ ~owever, the expenditure on time ~or thi~ production is v~ry high, 80 that this pro~es8 i5 excluded for ~o~t ca6es on 1~ ground~ af cost.
~ the other hand, an apparatu~ for producing shaped bores by rotational machinin~, which es~entiall~
consists of a speaial drill which can be clamped in a machine spindlo by means of a floating holder and which i~ guided du~ing the drilling operatio~ by ~ean~ of ~
hardened template which is to be arranged above the workpiece ~nd ha~ the re~pective contour de~ired. The functioning of the abo~ementioned device i~, however, d~fective in that it~ application ~ay only be very limited. A ~ubstantial di0a~vantage of the apparatu~ is the faat that for ~eometri~al rea~ons alon~ the polygonal drill doe~ not describe a unique path in~ide th~ tem-plate, so that the contour produced departs in a variable fashion from ~he contour of t~e te~plate. Owin~ to the wobblin~ rotation of the external drill edge3 inside the template, the edges become round~d with time in 8UC~ a way that whe~ the end face of the drill is reground the internal di~ensions of the bore to be produced become ~mallex and the drill wobble~ around even more in the templa~e. ~he drill, which is produced f rom HSS, is not only expensive t~ procure and diffi~ult to regrind, but al~o has a decidedly unfavourable cuttin~ edge geometry.
It i~ not po~si~le to mount exchangeable cutting tips. It ~ 5~7~7 i~ disadvantageou~, furthermore, that ~efore the st~rt of drilling the templates mu~t be mounted above the work-piec~, and the drill ~annot be in~ert~d into the template until th~ spindle is stationary, with ~h~ reYul~ that this produce~ a decidedly complicated mode of proaedure which, for example, cannot be ca~ried out on an auto-matically operating maahine.
There are at pregent a number of technical pos~ibil~tie~ with reference ~o the production by ma~hining of e~ternal contours, of which milling ma~ well be the mo~t o~vioU8. H~wever, it i~ known that by compari~on with turning, milling proceeds from a lower metal-cutting rate per unit time. Special device~, for example ~o-called multi-edged milling devices t ar~ al~o ~nown her~, which exhibit very good re~ults on milling maahines. Such mult~-edged m~lling devices do not, however, per~it thR production of rounded contours ~uch a~ ellip~es or three-lobed 6hapes, for examplet and also C~hnot ~e u~ed on a CNC turning machine wi~h powered ~0 tool~.
A ~evice ~or producing polygonal hole~ iY dis-closed in Ger~an Pat~nt 813,~10. Thi3 d~ice has a cyli~drical housing which i8 prevente~ by means, for example an arm mounted on it, ~rom rotating about it~
verti~al central axis. Mounted rotatably i~ thi~ ho~si~g i~ a Morse taper which can be, for example, plugged into the drill ~huck of a drilling machine. ~he Mor~e taper carries with it a f~ceplate body which ha~ a radial slot ~or a~commodating a workpiece holding bar, in which slot the holding bar ~an be radially displaced in addition to it~ rotational motion imparte~ by the Morse taper.
Arran~ed in the ba~eplate body is a spring, the tension of which can be adjusted and which pres~es the workpiece holding ~ar r~ially outward~, so that the latter bear~
with an edge which i~ ~haped like a blade ln this r~gion again~t a ma~ter templaté, which i6 arranged in the lower p~rt of ~he housing and who~e contour corresponds ~o ~he polygonal bore to be produced. If the Morse taper now 4 ~ ~7 ~J7 ~) rotates, ~he workpiece holding bar rotate~ in ~ympathy and is pres~ed by the spring again~t the rim of the master template. ~n thi~ proce~, it ~lides to and fro in the ra~ial slot in accordance with th~ rotation of the baseplat~ body. A workpiece clamped in the workpiece holding bar iB i~ten~ed in thi~ way to hore a predrilled hole to ~orm a polygonal hole correspondin~ to the contour of the master template.
The essen~ial ~ig~dvant~ge of this device i~ that ~0 the ~ucce~s aimed for will oCcur only in a very defective fashion, if at all. The rea~ons for this are to ~e Been in the ~riction forces occurrin~ betwee~ the ~lade-~haped edge of the workpiece hol~in~ bar an~ ~he master t~m-plate, and in th~ large angular variation~ to be noted between the la~ter during ~ revolution. A perfect revolu~ion of the tool i~ possible only ~iven appropriately small fricti~ forc~s bctween the workpiece ~olding bar and master templat~, that is to say the ~pring must be correspondingly weak or be adjusted to be 2Q weak. Thi~ leads, automatically to a wo~bling revolution, the "vibra~ion ~y~tem" of the device builds up in the proce~ and sprin~ flutter occurs. A proper working procegs is therefore not po~ible. A perfe~t bore corre~pondi~g to the desired contour can be produced only 25 ~f the blade-shaped edge of the workpiece ho~ding bar bea~ firmly again~t the rim~ of the ma~ter template in all phase~ of the revolution. ~owe~er, thi~ i6 po~si~le onl~ in a correspondingl~ ~tron~er, or more strongly adju~ed spring. This re~ults, however, in very hi~h fxiction forces, which in conjunction with the angular vaxiations and acc~l~ration values to be noted, in partlcular in the corner regions of the template~/ would lead to a seizure of the workpie~e holdin~ bar and to a destruction, p~ssi~ly re~ulting therefro~, of part~ of 35 the d~ice.
The above ~atements al~o hold analo~ously for device~ which are similar in pxinciple and were chie~ly inven~d in t~e first half of our century ~ut did not ~ 7 furnish ~he ~ucces~ desired i they were realised at all.
For this reason, in form drilling recourse still continue~ to be had today to the template drilling method de~pite the indie~ted defi~lencie~.
Th~ t~k therefore exi~ted of providing a special de~i~e for the production o~ differ~nt shaped bores or different external contours for the cases where low and average nu~ers of pi~ces are required in conjunction with increased d~mands on the cleanline~s of the ~urface and the dimen~ional stabilit~ of the contour without the disadvantaqes describe~ abo~e, such a ~evice ~eing required to oper te in a~ exceptionally eoonomic~l ~aghion.
~hi~ object i~ achieved by mean3 of a form lS drilling or turning device which has a drive shaft, a f~xed hou~ing. and a tool holder ~hich i8 conatructed to ac~ommodate a tool having at lea~t one cutting edge, the drive shaft and tool holder being mounted rotatabl~ in the houxing and connected to one anothex in such a way ~0 that during operation a rotational force component i8 trans~itted from the drive shaft onto the ~ool holder but the ~ool holder can ~imultaneou~ly be deflected in the rad.ial plane, this deflection b~ing controllable for the purpose of contour production by means of control elements a~igned to the housing and ~he tool holder~
Accordi~g to the invention, the control elements consi~t ~f at least two ca~ discs which are firmly connected to the ho~sing, arran~ed ~bove one another and rotated with respeat to one another by a specific angular amount in the direction of rotation, a~ well as rolling member~
whic~ roll on these cam discs and are assigned to the tool holder, ~here being at least three contaat points betwe~n the rolling members and the cam discs, and the loci of the cam disc~ de8cribing an equidistant line, corresponding to half the diameter of the rolling member~, of the enlarged contour of the ~haped bore or the external ~ontour.

2 ~ ~ ~7 Thu~, for the purpo~ of controllin~ the tool holder the invention hqs recour~e to purely rolling-action ~lement~ r a8 a re~ult of which the riction forces between these element3 and the cam di6cs are in practice 5 ne~ligibly small~ The interaction accor~in~ to the in~ention of th~ rolling element~ and cam disc~
repre~nt~ a forced control by means of whioh a radial or pivotin~ motion is ~uperi~po~ed on ~he tool holder rotating in the housing.
~n es~ential point of t~e invention i~ th~
realisation that radial def lection~ lying in a radial plane and ~upe~impo~ed on the rotational motion o~ a ~ember can be produ~ed pa~ticularly favourably in ~a positive ~orced) fa~hion by means of purely rolling-action ele~ent~ by arr~nging the control elements, ~on~isting fox example of a r~npec~ively ext~rnal c~m di~a and internally running ro~lin~ ~embers, stacked above one another at least twice in the axial direction and ~imultaneously rotated with respect to one another ~y ~0 a speaifia an~ular amount. A further point of e~phasis of the invention is, howe~er, the realisation that with increasing enlargement the loci xequired on such cam discs change increasingly away from the contour to be drilled or turned toward~ a circular 3hap~.
~5 ~he~e reslisations are used with the invention in auch a way tha~ at least two cam di~c~ which are offset in the axial direction and arxanged rotated with respect to one another by a speci~i~ amount in the direction of ro~ation are proposed for the control unit of the de~ic~.
~he direction of action o~ th~ rolling member~ a~socia~ed with the tool holder, which are offset axially with re~pect to one another in a ~ynchxonous fashion relative to the cam discs i~ tuned to ~he loci of the cam di~cs.
Furthermore, an equidistant line, corresponding to hal~
the diameter of the rollin~ members, of the enlarged contour o~ the shaped bore or of the external contour is de~cribed by mea~s of the loci of the cam di~c6. The invention provides here~ fur~hermore, the possi~ility of - 7 ~ 7~ ~
choosing between a purely radially oscillating or an eccentrically oscillating or eccentrically rotating mo~ion superimpo~ed on the rotational motion of the tool holder, thi~ de~ign ~and-wid~h ~anging ~ro~ a relatively constant cutting ~p~ed o~ the cutting edg~ in the ca3~ of stxon~ly fluatua~ing cutting angle~ of the tra~l edge to ~trongly fluctuating outting ~peed~ of the cuttin~ edge in the ca~e of slightly varying cutting angles of the trail edge~ In thi~ reqard, the loc~ of a ~am di~c lQ pxeferab~y describe3 a lead cam a~signed to the cutting edge o~ the tool, while the two other cam disc~ have the complementary cam~ to be e~ta~ ed. When e~tabli~hing complement~ry camc it must be en~ured that the loai do not have any inside radii smaller th~n ~he radii of the rolling member~, nor any undercut~ or ~o-called loop~.
Furthermore, ~he configuration of the loci has an e~fect on the smooth runn~ng or the wear o~ the device. Thu~, in~teAd of sharp-edged corners it will ~e ~avourable to provide gentle corner radii or to configure the lead-in and runout at ~he corner of a contour element with a ~o~t transition ~imilar to a parabolia curve, ~or example) even ~iven the use of a corner radiu~.
As to the number of the cam di~c~ and the number o~ the rolling member~ rotating in~ide a cam disc, there 25 i~ a cextain degree of freedom with re~ard to th~ doslgn of the de~Lce aaaording ~o the invention. Thus, for example, it iæ po6~ible for a ~et o~ cam discs to consist of four cam disa~, with the po~ibility o~ ~electing an eq~al angular off~et o~ the r~spect~ve loci, or with t~e 30 repetition o~ a locus ( Ior ex~mple fir~t and ~ourth cam disc wit~ the ~ame locus and the ~ame angular position).
It is e~sential for t~e~e to be at least three contact points present between the available rolling member~ and cam di~cQ, or fo~ contact lines ~o be present if a line contact approach i~ adopted. Thu~, for example, it i~
po3sible to work with two ~am di~c~, it then bein~ the ca~e th~t two rolling member~ rotate in one cam di~c and one rolling member rotate~ in the other cam di~c.

- 8 - ~ ~7~7-~
~owever, it is prefe~able to u~e three ca~ diRcs haviny at lea~t one rotating rolling member in ~ach ca~e.
The drivR shaft ~erves to i~troduce the torque required for th~ drilling an~ turning, and i~ mounted rotatably in the housing ~y mean~ of anti~riction bear-ings, It ~an be confi~ured on the machine ~ide in ~uch a way that the accommodation of the device is possible by mea~ of tall ~andardi~ed or commercially available ~y~tem~, for example a cylindrical shaft, a Morse taper, a steep taper or front toothing, 80 that a form drill can be u~ed universally on all bench and pillar dIilling machine~, milling ~achine~, machining centre~ or turning machines with powered tools.
~he housing, which remain~ fixed durlng op~ration, i~ d~si~ned, for exa~ple, eith~r such that i~
ca~ ~e moun~ed on the tu~ret plat~ of a turning machine with powered ~ool~, the connection for the coolant i en~aglng 6imultaneou~1y, or that the co-rotation of t~e houRing i~ pr~vented by means of a ~eparately mounted or integrated ~top when then the form drill i~ directly connected to a ~otating ~p~ndle. The hou~ing include~ the control unit, which co~ ts of cam discs that are firmly connected to khe hou~ing and are preferably exchangea~le.
Mou~ted in the housing i~ a tool holder w~ich i8 connected to the drive ~haft ~ia a ~pecial coupling ~for example Oldham coupling, Schmidt coupling, univer~al joint, helicoflex coupling, metal spiral, ~orrugated bellow~ or the like) such that a rotational force c~mponent is tran~mitted fro~ the drive ~haft to the tool holder, even if the tool holder i8 located in a radially deflected po~ition. ~he tool holder is s~lgned elements (for ~xample ball ~earings, needle bearingg, rolling ~leeves, rol~in~ members) rolling on the cam disc~. On its lower e~d, the tool holder ha~ elther a direct ~5 re~eptaale for an exchange~ble cut~in~ tip or ~or a milling drill, or ~ recep~acle for a tool ~hank. Tn the case of an ins~rte~ tool shank, it i~ po~sible to mount thereon an exchange~ble cutting tip, pre~erably made from 2 ~ J7~ ~

~olid carbide. In th~ case of a design of the devic~ to produce ~haped bore~, it i8 pa~ticularly ad~antageous to mount the cutting tip by means of a central ~olt, which can be turned a~ially in~o the tool shank, and of ax~al toothtng locat~d on both part~
Furtharmore, it i~ provided according to the in~ention to provide ~h~ tool holde~ with a flow path for a liquid ~oolant, it being possible to connect thi~ flow path in ~ ~eal~hle fQshion to the m~chine-~ide inlet, for example by m~ans of a co-rotating, elastomerlc ho~e between the tool holde~ and dri~e shaft.
I~, for example, the devi~e accordin~ to the inven~ion i8 to ~ usod to produ~e a hexagonal contour, lt fol~ow8 t~t huch a contour can be di~ided into ~ix id~ntical element~. In other words: a si~ilar contour ele~enk i~ repe~ted after each ~otation ~ngle of 60-. If a larger ~orn~r radiu~ ~ 8 permitted ~or the contour, the reguired control unit of the form d~ill can be realisod u~ing a plur~lity of cam discs of iden~lcal contour. If~
~n this ca~e, use i8 made, for example, of three cam discs ~tacked axially above one another, it iB sensible to arran~e ~he latter offset by thQ angular amount 60 ~ 3 = 20~ with respec~ to one another in the direc-tion of rota~ion, ~hile the respec~i~Q directions of Z5 action of the rolling member8 a~ociated with the tool holder ar~ swi~ellod in the ~elected example by in each ca~e 360 ~ 3 - 120 with re~pect to one ano~he~ in ~he co~responding axially o~f~et plane~ and in a manner co~r~ponding to the ~irection o~ rotation of the Qam disc~.
If such a contour i~ provided, for example, as ~
he~agonal bore for a key of 10 mm, and assumin~ a dimension of 10.2 mm as ~idth acrosR flats of the shaped bore, ~he re841t i8 a COrner di~en~on of approximately 11.78 mm in ~he caRe of sharp po~n~ thtnning of the corners. It follow~ from the corresponding radii, of 5.1 and 5.89 mm re~pectively, that during its rev~lution t~e cutting edg~ of the form d~ill mu~t ~e moved res~tiv~lv q~ ~

six times by 0.7g mm outward~ and back again. If the mid point o~ a rolling member o~ the tool holder were to coincide with the ~utting e~e o~ the milli~y drill, thi~
would result ~or the corre~ponding cam di~c in a con~our whi~h e~sentially aorresponded to a line offse~ outwards by the radius of the rolling member in a manner eq~idi~tant from the hexag~n. In the ~aid example, in the case of a rolling member radiu~ of, for example, 4 mm the width acro~ flats of the cam path would then be 18.2 mm and the corner dimension 19.78 mm. Such a design ha~ ~h~
disadvanta~e that only a little space is available for the (internal) tool holder and the rolling mem~ers. On thP other hand, it would ~e un~avourable to rever~e the arrangement (cam discs inside, work holder and rolling member~ out~ide ), becau6e then the moving ma~es become lar~e. ~he enlargement according to the invention of the c~m path has the advantage here that the radial motion~
to be superimposed remain ab~olutely identi~al and decrea~e relative to the diameter of revolution, so that the t~ol holder rotates relatively softly. The application of this triak ~imultaneously creat~s the ~pace requir~d f or th~ tool holder and permits the in6tallation of larger rolling members.
It will be favourable in practice to offer a plurality o~ housi~g ~izesr for example ~ize 1 from 4 to 1~ mm, size 2 from 10 to 25 mm, 9i2e 3 from 20 to 50 mm, ~or the diameter range to ~e covered by ~haped bores or external contours. In the ca~e of the larger contours, it i~ provided acaording to the invention tha~ in addition ~0 to the ~inishing cutting edge the cutting tip or the ~orm miller be advantageously equipped with at least one roughi~g cu~ti~g edge reduced in diameter and arran~ed with an angular twi~t wi~h re~pect to the finishing cutting edge, in order to divide the volume to be machined and ~imultan~ou~ly tQ produce smaller chips.
Furthermore, the ~odular ~e8ign of the form drill according to the in~ention is ~dvantageous, the con~rol units or the cam disc~ being exehangeable in a ~imple way in order to be able to u~e the ba~ic device to machin~
both different conto~r~ and diffe~ent ~ize~.
In the prac~i~al appli~ation a~ form drill o~ ~he d~viae a~cording to the invention, a pilo~ b~r~ ttap hole~ whose diameter i8 tuned to the æmallest diameter of the ~haped bore is pro~uced conventionally. The drillin~
depth of the pilo~ bore must correspond at least to the depth of the shaped hore. ~he ~haped boring by meanfi of ~he ~evice according to the inventio~ is sub~equently aarried out in one operation using t~e ~peed matched to the diameter an~ a feed corresponding to the material. ~n ~h~ proc~ss, the feeding of coolants, prefera~ly via internal duct~, is very important, chief~y in ord~r to wa~h the bore free ~rom chip~.
Wh~n the devi~e ~ccording to the invention i~
embodied a~ a turnin~ devic~, the shank, assigned to the t~ol holder for the cutting tip i~ mounted eccent~ically.
There i~ the possibility of adju~ting the ~hank radially.
The cutting edge of ~he cutting tip then points inwards, in order to turn the desired exte~nal conto~r. Xn ~hi~
~a~e, ju~t a~ with for~ drilling, it i~ only conto~r~
located at the en~ of a workpiece that can be produced.
It is propcsed for the production o~ contoure having radially strongly fluc~uatin~ dimensions, ~uch a~
2S in ~h~ aase of very lar~e ~quares, for ex2mple, firstly to carry ou~ by mean~ of a device accordin~ to the invention a rou~hing operation with a reduced machining volume, a corre~pondingly modified ~et of cam dl~cs re~uiring to ~ u~ed. ~his ~hould be followed by the finis~ing ope~ation with the fini~hed con~our.
Suah a machining ta~k can be carried out u~ing a ~ingle device in a ~imilar way by, for example, pxoducing a 20 mm square hole by machining with ~he aid of a set of cam di3c~ for an 18 mm ~uare hole in the central posi-tion, at fir~t. Subsequ~ntly, the finished contour canthen be produced by multiple radially off~et tracing using the C axi~ in the ca~e o~ production on the ~NC
turning machine.

In con~unction with the proposed detailed 801ut i ons, the de~ice according to the invention make~
a~aila~le a tool which h~ a range of out~tanding ad~antages:
S - exact contour geom~try - very narrow ~nufacturing tole~nces - clean borQ bottom in the ca~e of blind ~ores - scarcely any w~ar of the ~echani~m - exchangeablQ carbide tip - high cutting speed - ~nternal coolant feeding - automakic operation on all types of machine - multiplicity of bore geometries The invention is explained in more detail below lS with the aid of an ~xemplary e~bodiment. In the drawings Pigure 1 ~hows a form drilli~g device according to the invention for producing relatively small ahaped bores, ~n a 81ightly simplie~, partially cut-away and ~pp~oxLmately true-to-~û 8cale representat~ on, and Figure8 2, ~how in each case a disc of a set of cam 3 a~ 4 di8cS for the form drilling device represented in F1~4re 1.
The dri~e ~haft 1 of the devico ~h~n ln Figu~e 125 iB designed on the machine s~de as a ~teep taper S~ 30.
It is mounted in the hou~ing 2 by mean~ o~ the anti-~iction bearings 4, 5. The lower ~earing 5 i~ secu~ed by means o f ~he retaining rings 6, 7. ~he drive ~haft 1 i8 pro~ided on the output end with iournals which engage in longitudinal slots of the coupling qisc 8, but which are not visible in t~ r~presentation, be~au~e their position i~ rotated by 90~ he radial plane . ~he coupling disc 8 is mounted on the tool holder 3 by mean~ of a wea~ing di~c 9 and secured ~y mean~ of a retaining rin~ 10. The hausi~g 2 i8 a8signed three c~m discs 1~, 13, 14 which are mounted in the blind tbread~ 11 on the ho~ing 2 b~
mean~ of bol~ tno~ ustrated) and are ~ecured against rotation ~ith respect to one another and wit~ respect to 2`~7~ ~1 the housin~ 2 with the aid of fitting pins (not illu~trated). The ~oltQ ~imultaneously mount a radial stop 15 on the hou~ing 2 whbse function i~ to prevent coxotation of the hou~ing 2. R~essed into the cam discs 12, 13, 14 are grooves 1~ for O-rings which serve the purpose of ~ealing again~t the es~ape of oil or grease.
For th~ ~ake o~ s~mplicity, the internal contour o~ the c~m di~c~ has been drawn uniformly æmooth, that is to say no account has been ~aken of the respective offset produced by the contour and the rotational angle. The tool holder 3 e~a~es by ~an3 of two fitting pins 17, 1~
which are located oppo~ite one another at 180 in the longitudinal ~lot~ of the ~upling di~ 8. One of the fitting pln~ 18 ~imultaneously ~ervee ~s journal for the rolling member 19, which corresponds to the central cam disc 13. No~ r~presented in the drawing, or covered therein, are two further fittin~ pin~, which have rolling members that ~re arranged rotated by 120 with respect to the fitting pin 18 in the radial plane of the tool holder in each case, and who~e rolli~g member~ correspond to ~he ~am disc~ 12 and 14. The tool holder i8 mounted by means o a coll~r o~ the ~nd face of the lowermost cam digc 14, in order thu~ to lead away the axial forces ocaurring during drilling. It i~ pos~ibl~ to integrate a face seal ~5 ring or a ball rim, at the ~ame ~ite, in order to minimise the friction that occurs~ It is also po~sible to take up ~he axial force~ in the caæe of a corre~pondin~
design (width~ o~ the rolling member~ 19 and the cam disc~ 12, 13, 14 by inserting thin plates between the cam di~s which project ~lightly beyond the internal circum~
~erence of the cam dis¢s. In this ca~e, the ~olling members 1~, for example ball bearing~, then run on the~e plates on their outermost rLm region. It iæ then posæible to eliminate the 6upport on the collar of the tool ~5 holder. A tool shank 20 i~ inserted into the tool holder and tighten~d with the aid of a grub ~orew 21~ An exchan~eable cutting tip 22 made ~rom car~ide i~ ~rewed onto the tool shank 20. The cutting tip 22 is equipped 2g:~7S7~ ~0 wi~h a cutti~g edge 23 whose angular position on th~ tool h~lder corre~pond~ to the rolling member 19 and the cam di~c 13. ~he tool holder i~ bored throug~ centrally in order to open up a duct fo~ the ~oolant. The extension of the bore in~i~e the tool holder and the outlet in the vicinity of the cutting tip have ~een omitted for reasons of 6i~plific~ion in the ~ame way a~ the connection le~ding further upward~ ~nternally.
Repre&ented in section to ~he same scale !in the radial plane in Figures 2, 3 and 4 are th~ three individual cam discs 12, 13, 14 of the ~et of cam di~cs that i~ a~sociated with the exemplary embodiment shown in Figure 1. For the purpose of simplifying the drawing, the fitting bore~ fQr the fitting pins have been omitted, as lS have the through bores for the mou~ti~g ~crews. The 8et of cam di~cs ~hown is provided ~or producing a soçket hexagon w~th a width acros~ f lat~ of 11 mm~ ~he individual cam discs are open at their cen~re, the walls of these openings bein~ formed with the configuration of a re8peative locus 24, 25, 26. The central cam disc 13, whic~ ~or~e~ponds ~n the exemplary em~odiment to that rolllng member which i~ aq~igned to the cutting edge 23 of the ~utting tip 2~ has the lead cam 25. The upper ~nd lower cam disa~ are ~rovided respectively with the complemen~ary cam~ 24, 26~ It is clearly to be 6een that owing to the enlarged contour and the formation o~ the equidi~tant lines the lead cam thus f~rmed in the selected de~ign i~ already very noarly circular in shape~
Nev~rthele~ r th~ hexagonal basic shape is still indic~t~d. It may also clearly be seen that the two complementary cam~ 24, 26 have loci which depart from the lead cam 25. Although all the loci have a ~oft and rounded characteri~ic in common, during revolution of the tool cutting edge 2 3 a perf ect and ~harp-edged 35 contour i~ actually described.

Claims (8)

Patent claims

1. The invention relates to a form drilling or turning device consisting of a drive shaft, a fixed housing and a tool holder which is constructed to accom-modate a tool having at least one cutting edge, the drive shaft and tool holder being mounted rotatably in the housing and connected to one another in such a way that during operation a rotational force component is trans-mitted from the drive shaft onto the tool holder but the tool holder can simultaneously be deflected in the radial plane, this deflection being controllable for the purpose of contour production by means of control elements assigned to the housing and the tool holder, charac-terised in that the control elements consist of at least two cam discs (12, 13, 14) which are firmly connected to the housing (2), arranged above one another and rotated with respect to one another by a specific angular amount in the direction of rotation, as well as rolling members (19) which roll on these cam discs (12, 13, 14) and are assigned to the tool holder (3), there being at least three contact points present between the rolling members (19) and the cam discs (12, 13, 14), and the loci (24, 25, 26) of the cam discs (12, 13, 14) describing an equidistant line, corresponding to half the diameter of the rolling members (19), of the enlarged contour of the contour of the shaped bore or the external contour.

2. Form drilling or turning device according to Claim 1, characterised in that the locus (25) of a cam disc (13) is constructed as lead cam (25), when at least one further cam disc (12, 14) has a complementary cam (24, 26) that is to be established in accordance with the lead cam (25).

3. Form drilling or turning device according to Claim 1, characterized in that the tool holder (3) is constructed to accommodate a milling drill or a tool shank (20), an exchangeable cutting tip being mountable on the tool shank (20).

4. Form drilling or turning device according to Claim 3, characterised in that the cutting tip is radially adjustable.

5. Form drilling or turning device according to Claim 3, characterised in that the milling drill or the exchangeable cutting tip has a finishing cutting edge and at least one roughing cutting edge which is radially reduced and arranged with an angular twist with respect to the finishing cutting edge.

6. Form drilling or turning device according to Claim 1 or 3, characterised in that the tool holder has at its disposal a flow path for a liquid coolant, and this flow path can be sealingly connected to an inlet on the machine side.

7. Form drilling or turning device according to Claim 1, characterised in that the tool holder (3) is connected to the drive shaft via a special coupling (for example Oldham coupling, universal joint, Schmidt coupling, metal spiral, corrugated bellows or the like), in order despite the respective deflection, located in the radial plane, of the tool holder (3) to transmit a rotational force component from the drive shaft to the tool holder (3).

8. Form drilling or turning device according to Claim 7, characterised in that the special coupling according to the Oldham principle consists of a disc (8) which has two groups of longitudinal holes each of which extends radially and which are diametrically opposite one another, the groups being arranged offset at a right angle with respect to one another.