[OOOIFUtf^fiTARY gSAR UNIT ANP METHbP FOR PROPUCfNQ A P^^NETARY SEftR UNiT
[0002]
(0003]
[0004] The present invention relates to a planatary 0«8r unit according to the
preamble of Patent Ciaim 1 as wail as a method for pradudng a planatary gear unit
according to the preamfate of Patent Claim 9.
10005]
[0006] A planetary gear unit, also called a pianataiy gasir set in general consists of
a planet carrier (planetary gear oariier). a planet pin (ptenetary gear pin) mounted In the planetfiry carrier, as well as planets (planttary g^rs) which are mounted on the planet pins. The planetary canier may be constructad from a fonning part with angled amis and a guide disc or from two parallel guiding washers which am connected to one another via rivet bote. A planet cafrier of this type has been l Immediately batora blanking, a knife edge ting Is praaaad Into the work plsiod (mataJ Sheet) at a small distance ftom the cutting line, as a reault of which ioompresslon stiMses are
a

superimposed in the shear tone. The final outcome will be a smooth and fiesure-free cut surface.
[0008] From EP 1 266 154 B1 by the applicant a mathbd has been known for an
accurately positioned assembiy of a planetary gear unit, whersby the planet pine are
peered with the guide discs In a almiiar manner as the above mentioned rivet bolts.
The Planet pins have shoulders and Journals on the end ilde whioh ens inserted with
a radial ciaarance into the perforatlona of tho guide diSoa. The journala are then
peened and the radial gap filled by the material of the journal that has beer
displaced outward. Tha material of the guide discs is clampad in the area of the
perforations by the mashing knifa edge rings. ',
[0009) Another method for tha accurately poaitbned asaembiy of a pianotaiy gear
unit has been known fmm DE 10 2004 057 576 A1 byithe applicant, whereby the planet pins are centered and algned opposite to Qie |guida discs prior to being peened. The planet pins have open lengthwise boras Ion tha end side with which conical tips of opposed d«a mesh and thus achieve an alignment
[0010] The problem with the known methods for the assembly of a planetary gear
unit is the exact centering and alignmentof the planet piri such that optimal meshing of the teeth of the planetary gears with the correspor^dlhg sun and ring gear is ensured. Potential solutions still result nonethekras.
[0011]
[0012] The ottiact of the present invention is to so improve a planetary gear unit of the
above mentioned type as regards its design, that accurate centarlng and alignment of the pins, in particular of the planet pins, is achieved. Moraover, tt is the otijact of the present invention to aooompiish a method lor producing a planetary gear unit of this type, which allows for an accurately posttionad assembiy of the components of the planetary gear unit.
[0013] The object of the present invention is attained byithe characteristics of daim
1. Advantageous embodiments result fjiom the subdairhs.
[0014] Aooording to the present invention, it is provldad that the pins have
circumferential cutting edges and are cut into the guidia discs by means of theee cutting edges. The pins have a diameter in tha area of the circumferential cutting
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edges that Is greater than the pre-drllled aperture in th^ guide discs, e.g. the pins are oversized relative to the diameter of the perforations. By cutbng the pins Into the guide discs, a deararoe^iea fit and smooth suifiacs 's achiesfSd for the transmieaion of ftroes tjetweenthe pin and the guide dtece. The pine may be partially or totally out into the guide discs; a ring-sheped waste dipping tMutts from the 'cutting through".
[0015] The planetary gear unit preferably comprises a ptimet canrierwhich is formed
by two goide discs that are connected ID one another by ffvet bolts. A planet canier is, ho\fvever, also possible that has no rivet bolts, but ihftt»ad a forming part with arms replacing the rivet bolts which are connected to a guide disc. The pins may preferably be contigured as planet pins, as rWet bolts; or also as rivet bolts and planet pins which thus satisfy the function of a planet pin as well as a rivet bolt. By cutting the pins into the guide discs.the advantage is aleo achieved that only smaii foroes are introduced radially into the guide discs - In contrast to the prior art, where a radial widening occurs as a result of the peening.
[0016] A preferred embodiment of the present inventton provides ihat tfie depth of
the indeicn. I.e. the path of the cutting edges into the rhsteriai of the guide diecs, approximately con^ponds to half the thickness of the guide discs. The material of the guide discs that is displaced by the cutting edges abuts on the shoulders end journals of the pins after ending the cutting process. The outer side of the guide discs thus remains flat. The ring of displaced materfa! hence forms en axial abutment of the planet pins in the guide discs,
[0017] The otject of the present bventlon is also ettalmed by nfieans of a method
according to the characteristics of claim 9; advantageous embodiments are found in the subclaims.
(0018] /\ccoiding to the inventive method, guide discs are first pre-drtlted. which may
be accomplished by fine->blanidng. The dlametsr of the bore Is significantly larger than the outer diameter of the journals, so that the journals of the pins may be inserted with radial dearanoe into the perforations. On the other hand, the outer diameter of the pins in the area of the drcumfiBrentol cutting edges is larger than the inner diameter (bore diameter) of the perforation, i.©. It is oversized relative ID the bore. The planetary gear unit is completed before the second guide disc is placed on the pins, i.e. the necessary components are entfrely assembled, for example
h

planetary gears, starting discs, etc. Subsequently, the guide dtsos are n^oved toward one another by opposed dies suoh that the cutting edges of the pins out into the core of the guide discs and radially displace this material in the cutting directions as well 36 transversely to the cutting direction. Thus the previously existing radial gap between the journals and perforations is filled.
t0019] According to a prefen-ed embodiment, the dies have knife edge rings that dig
Into the outer side of the guide discs or mesh with praf^bricated grooves, produce compression stress and prevent tha matarlal from moving outwftrd in the radial directior\. The material of the guide disc is consequently clamped between the knife edge Ungs of the spinning tool and ^e ctrcumfarential cutting edge of the pin whtoh thus acta as a cutSng die. The superimposed compression stress produces a cutting process similar to fina-bianklng which results In a smooth, fissure-free cut surface in the guide disc This advantageously results In a clean seat of the pin on the guide disc and a defined transmission of tangential forces. The depth of the indslon is also a function of the admisBible contact surface praasure between pin and guide disc.
[0020] Accordingioaprafiarradprocessstep,itispiovfdadthatthepinsarscemeredand
aligned before the kntfe edge rings mesh or cut in. This may be carried out by conrespondingiy aligned dies provided wHh conical tips which mesh with end-elds centering apertures of the pins and thus achieve the desired oentering. After the centering process, ihe knife edge rings hoMing the guide disc mesh and subsequently or simultaneously cut in the cutting edges.
[0021]
[0022] An exemplary embodiment of the preeent inventkm ie iliuslratsd In the drawings
and vM be e^tpWned in more detail in the following section. THe drawings shovy;
[0023] Fig. 1 a cross section of a planetary gear unit afat a first prooaas ai«p,
[0024] FQ. 1 a a detail X fhom Fig. 1,
[0025] Fig. 2 a cross secHon a planetary gear unit after a second process step, and
[0026] Fig. 3 a cross section of a planetary gear unit after the last process step, I.e.
in finished conditbn.
(0027]
S

[0028] Fig, 1 shows a cross sedMonal view of a pre-assembied planetary unit 1 of
whic^ a first guide disc 2 and a seoond guide disc 3 are partly illustrated. Beth guide discs 2,3 may be connected to one another by a rivet bolt, \which is not lllustirated, or one of both guide discs may be configured as a pot-shaped fbrmlng part with amis which assume the function of rivet bohs. A plantt pin 4, which has journals 5, 6 on the end side is an-anged t)etween both guide disce 2, 3. Bores 7, 8 (pertorations) are arrarvged in the guide discs 2, 3. which boras are preferably -similarly to all guide discs 2, 3 - produced by flne-bianking, as a result of which smooth and fiesure-free cut surfaces are obtained. The planet pin 4 has an outer diameter D1 between the guide discs 2,3, the bore 8 has an Inner diameter 02 and the Journal D2 > D3.
[0029] The outer diameter D1 of the planet pin 4 Is recessed relative to the journals
5,6 via a shoulder 9,10 which is configured as a cinjumfereatial cutting edge 11, 12 In Its outer radial area and is shown enlarged in Pig. 1a. The planet pin 4 has a lengthwise bore 4a which is open toward the end side of ^ journal 6, as well as a coaxially arranged blind hole 4b which Is open toward the end side of the journal 5.
[O03O] Rg. 1 further shows a device 13 for accomplishing the method according to
the present invention, in particular for an accurately positioned assembly of the planetary gear unit 1. The device 13 has a bottom part 13a and an upper part 13b which respectively consist of a sleeve»shaped pressing tool 14,15 and an axially dispiaceabie die id, 17 guided therein. The sleeve^shaped pressing tools 15,16 have 3 circumferential knife edge ring 14a, 15a at their end surfaces which engage in a ring-shaped groove za, 3a of the guide discs 2,3. Thedlee IS, 17 have tnAicated conicai tips 16a, 17a on their end sides which mesh wth the lengtfiwise bond 4a and/or the bNnd hole 4b. TTte position of the device 13 iOustrated in Fig. 1 shows the meshed bottom part 13a, whereas the uppr part 13b te etUt outof ntesh. The planetaty gear unit 1 rests upon the eleev&^haped pressing tod 15 with Us lower guide disc 3, whereas the VIVKB edge ring ISa meehes with the ring grooMe 3e. The centering journal 17fl further meshes with liie blind hole 4b and tiius already centere'the lower part of the planet

pin 4 inside tl>e bore 7. The planetary gear unft 1 is already oompletely In tliis position, which is not illustrated, i.e. all components like planet gears, starting discs, rivet bolts to be arranged between the guide discs 2, 3, are eomptetely pre-assembiod.
[0031] Fig. 1a shows the detail X from Fig. 1 as an enlarged view of the
circumferential cutting edge 12 of the shoulder 10. The cutting edge 12 % essentially fbrnied by two surfaces, namely the cylhdrtcal lateml surfiMi 4e of the planet pin 4 and a conical or concave cut surlace 4d MvNeh comprises a cutting ai^te a virith the lateral surface 4c that prsfisfably is smaller than 90°. The culting edge 11 Is similarly configured.
[Ooszi ^^' 2 shows the planetary gear unit 1 aooordkigtDFig. 1 as vi^ as th« device 13
in a second prc>cess step. The earns refarance numeialB as tn the previous dnmiri^ used Ibr the same pads. The upper part 13b of the d»vioe 13, (X>nsi8ting of the sleeve-«haped pressing tool 14 and the die 16 guided therein, has been driven down so far that the centering tip I6d mashes with the bore 4a and the knife edge ring 14a meshes with the groove 2a. This way, on the one hand, the planet pin 4 is centered relative to both guide plates 2,3 and, on the other hand, the gukie discs 2, 3 are clamped relative to the cutting edges 12,11. The distance of the inner surfaces of both guide discs 2. 3 is designated with a1 and oorresponds to the distance of both dnajmferential cutting edges 11,12 in the longitudinal direction of the planet pin 4.
[0033] Fig. 3 shows the planetary gear unit 1 as well as the device 13 after the last
process step, i.e. the connectton between planet pin 4 and gurde discs 2, 3, is completed, AS a result of further pressure, the sleeve-shaped pressing tools 14,15 have driven against one another and In this process have moved the guWe discs 2. 3 toward one another so that they now have a distance a2 which Is smaller than the previous distance a1 according to Fig, 2. At the same time, the planet pin 4 has cut into the material of the guide plates 2,3 with Its cutting edges 11,12, namely up to an indsion depth s/2, where s is the thickness of a guide disc 2, 3. The material of the guide discs 2, 3 displaced by the cutting process forms a ring-shaped ams 18, 19, designatsd hereafter as displacement ring 18,19 which is rsspeoHvely located in the cutting direction in front of the cutting edges 11,12 encompassing the journals

5,6, i.e. the previous ring gap 7,8 (cf. Fig. 1} i& at least partially filled up. Since the material displaced by the cutting process, in particular aleo by the Inclined cut surfaca 4d illustrated in Fig. 1a, is not only dieplaoed upward but also nadiatly inward, the outer surfaces of the guide disoa 2,3 remain relatively even. The upper part 13b of the device may now be retmoted, and the planetary gear unit 1 may be removed from the device 13 as e completely assembled part.
[0034] The method acoofding to the pneaent invention for cutting the planet pins into
the guide disc is very similar to the known fine-bianklng process, in particular because of the use of the knife edge rings which auperimpoae a ocmpression stress on the shear stress in the shearing zone of the guide disc, thus causing the material to flow. This results in a smooth cut surface in the guide disc which ie less notch-sensitive and prevents the appearance of fissures.
[0035] The above mentioned method may likewise b» usad on rivet bolts or pins
which function a$ a planet pin as weil as a rivet bolt.
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Raferenne Numerals
1 Planetary gear unit
2 Guide disc
29 Groove
3 Guide disc
3a Groove
4 Planet pin
4a LengttMuisebore
4b BlMhoie
4c LateFBl surface
4cl Cut surface
5 Journal
6 Journal
7 Bore
8 Bore
9 Shoulder
10 Shoulder
11 Cutting edge
12 Cutting edge
13 Device
13a Bottom part
13b Upper part
14 Pressing tool
14a Kniliaedgaiing
15 Prssi^gtod
15a Knife edge ring
16 Die
IGa centering tip
17 Die
17a Centering tjp
18 Diftplacament rtng

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D1 Outer diameter pin
D2 Inner diameter bore
D3 Outer diameter journal
a1 Distance of the guide dl&cs before cutting in
a2 Distance of the g uide discs after cutting in
s Wall thidcness of the guide discs
)o

We claim:
1, A planetary gear unit (1) having two parallel guide discs (2,3} with perfbrafions (7,8) an'anged parallel to one amther fcr accommodating pins (4) which have jounials (5.6) and shoulders (9,10) ananged on the end side, characterize in that the shoulderB (9,10) have drcumferentiei cutting edges (11,12) and that the pins (4) are cut Into the guide discs (2, 3) by mean$ of the cutting edges (11,12).
Z The planetary gear unit according to claim 1, charaderlzed in that the pins are c»nftgured as planet pins (4) for mounting planetary gears.
3. The planetary gear unit according to daim 1, characterized in that the pins are configured as rivet bolts for Iceeping daarance and for the transmission of forces between the guide discs (2,3).
4. A planetary gear unit aocordlng to any one of dalms 1,2 or 3, characterized in that the pine are configured as planet pins and rivet tx>lis.
5. A planetary gear unit according to any one of claime 1 to 4, diaraderized in that the pins (4) are at least hardened in the area of the cutting edges (11.12).
6. A planetary gear unit according to any one of ciaims 1 to 5, characterized in that the guide discs (2,3) have a thickness s in the area of the perforations (7, 8), and that the cutting edges (11, 12) are cut in up to a fraction of the thicltness s, prefierably approxlmatdy up to half the thickness s.
7. A planetary gear unit according to any one of ciaims 11o 6,
characterized in that the shouidars (9,10) are supported against a ring (18,
19) of displaced material of thegufde discs (2,3) generated by the cutUna process.
W

8. A planetary gear unit according to any one of the preceding c^ims^
characterized in that ring-ehaped groovae (2a, 3a} ara arranged on the guide
disce (2,3) concantrieaRy to the perfbrationfi (7,8)fbrme8hing with knife edge
rings (14a, 15a) of spinning tools (14,15).
9. A method for producing a planetary gear unit (1) acconiling to at least one of
the preceding daims, charactarlzad in that
- the guide discs (2.3) contain a device with apertures (7,8) for receiving the journals (5,6).
- the pianetaiy gear unit (1) is completed with regard to tha components to t>e an-anged between the guide disos (2,3),
- the guide disca (2,3) are moved against one another by mearia of opposed spinning tools (14,15),
- the cutting edges (11,12) of the pine (4) cut into the guide dieoa (2.3) and existing material from the guide discs is displaced in the area of the apertures.

10. The method according claim d. characterized in that the epinning loois (14,15) mesh with the ring-ahaped grooves (2fi, 3a) before cutting In with a icnife edge ring (14a, 15a).
11. A method according to any one of claims 9 or 10, characterized in that the pins (4) are centered belbre cutting and/or meshing with the Knifs edge rings {14a, isa).

Dated this 24 day of April 2009

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\X

(ARINDAM PAUL)
Of De Penning & De Penning
Agent for the Applicants