Note: Descriptions are shown in the official language in which they were submitted.
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J2 81021
~thod and ipparatur for griadiag oroskpiec~r haviag
aeat~rs ~rhich hav~ ~rrors og fvrsa
The invention relates to t1 1L~(; shod and an apparatus for
grind~.nc~ workni.RrRS having eQnters which have error3 of
form.
The prioz a~ L imvluc3e5 precision machining, in
partirn~lar the grinding of workpiocAS, the latter being
aeconunodated between locating o~silLdi'S of a headstoCk
and a fiail~t-n~k_ Tn this mounting, in particular such
workpieces which are very thin-wall~c~ in the region of
Z5 the mc»ni-ing center cause difficulties. Such workpiocc3
are often not pramachined in a geometrically accurate
manner or h~vw in~nrn~rariess of form, suah as
concentricity errors, xolated Lu c~lstortiOrl CauBed by a
heat treatment applied ~ftRr th~a premachining. The
removal of these distortion-related cituuldttl,y errors
of thin-walled workpiPC:PS mm~_)_y cannot be corr~ct~d
by $ubsoquent grinding on the outside rl.iaum~et~ oL l.he
workpieces, i . P . r_hP ri rrn~'I a r. tty errors of th~ center
are tran3mit~ted as dimensional or conc~rz~tic;ll.y errors
during external Cylindrical grinding. '
bescribed in US 2.595, 858 is an axle l,~t.ha in which an
axle-shaped workpieco aan bo mounted between a
tallsLock and a headstock for turning. The tailstoek
:i(7 and thQ hoadstock era Qach provided With a retaining
fla~~c~c, the flange on the tailstock side hai.nr~ provided
with friction surfaoes at its end face for holding the
axle to be around. Furthermore. spring-loaded 1ai-.hR
r.Anters are provid~d on the tailstook and headstvck
aide, these lathe centers, rCr the centering, engaging
in cenr.RrinO hnres of the axles to be ground. A
disadvantage with this lathe is that erteCtive
centering is not possib.l a~ c~mri ng the machining of
. workpiece3 having centers.
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The object of tho invention is thereforr~ Lc prvvlde a
mothod and an apparatus with whi.rh inaccuracies of
form, such ae conacntricity errors, Of tllc~ c;~ilCering
region of ~Che workpiecP ~rc~ not transmitted to the
finished part during the machining, Im l.tila way, the
c:~mplicated operation of center grinding before the
finish grinding of the workpiece is L~ be dispensed
wiL~l. Furthermore, a high production ~,.~ality is to be
lU achiovad by the workpiocc having a faultle~~
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Mathcd and apparatus for grinding ~rork~ioeos having
caa~rs ~rhioh haw errors of fosia '
The invention relates to a method and an apparatus of
grinding workpieces having centers which hwa err .~ of
form.
The prior art includco precision ma fining, in
parti ~n I ~ r fihP gri ndi ng of workpi PnRS, th J.attRr hai ng
accommodated between locating centers f a headstock
and a zailstock. 1n this mounting, i particular such
workpiecea which are very thin wall in the region of
the mounting center cause difficul i~a. such worxpieces
urc often not premachincd in a eometrically accurate
manner or have inaccuracie of form, such as
concentricity erroro, relate to di3tortion cau3ed by a
heat treatment applied a- er the premachininQ. The
removal of thcoc distort n-related circularity error3
of thin-walled workpie s usually cannot be corrected
by subsequent grindin on the outaido diameter of the
workpieces, i.e. th circularity errors of the center
are transmitted as 'dimensional or concentricity crrora
during external r~°lrindrical grinding.
The ob-~ect of the invention is therefore to provide a
method a.nd an apparatus with which inaccuracies of
form, sucl as concentricity erroLa, uL l.)ie c:eiil.eriue~
r.Pgion o the workpiscs ar~ not transmitted to th~
finishe part during the machining. Im Lt~i~ way, ~W
:iI) ~~mrl sated operation of cQntQr grinding before the
fin'sh grinding of the workpiece is W L~ disp~ci~~sc~
w _h. FnrthRrmnr~, ~ hi gh prn~mti nn quality is to bs
w a au ~ ouL~s~
circumference. The comp.Lete outer r_nntnmr i ~ tn ha
perfectly ground in a single mounting.
This object is achiev~d by th~ features of patent
~ld,iiu 1 related to the method and of patent claim 2
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related to the appnratuo for carrying out the method.
The f~sal.ures of patent claim 3 devwlnp the apparatus ae
al~i.med in claim 2 in terms of de3ign.
Thi s objoet is achieved in that the lvcatitty center of
the tail~L~c:k, this locating rtanter being mounted on
the tailstock quill, i~ dcaigned with a pressure pin
which is jJLUVl,(,i~d with a spring element . Th! workpieco
he machin~d is thus prcosed axially against the
opposite loc:dLiitc~ center of the work spindle of th~
headstcnk. In this case, the workpicce is supported >ay
a $toadyzdsl. ltt such a way as to be ti xad in position.
J:n an PmbodimQnt of the invention, the pressure ~ln
consists ct a piston part and a roh part; thQ prosaure
pi n i s mounted in th~ interior of the basic l:~u~iy uL the
tailstock lvcr~Lltty center. The 'Cailsto~k will with
tailqtnc-k locating center can be retractt~d i:u dtt
intermediate positiutt. Thus the workpiec:P, fir thQ
machi ni nr~, is accommoda.t~d in an oxactly crtnl,~wed
manner in the hesad~ Luck-side centeririQ rPgi cn and in
the haws ot~ i-.ha steadyrest.
The inv~ntion ig axrlainsd in more detail in terms of
th~ method and the apparatus im Lhe drawings anc:nrc~i.ng
to figs 1 to 4.
Fiy. 1 shows a parr.ial plan view of a grinding machine
with a partial sectional repwesentatiorr of the work
m~uuting,
fib- 2 shows a further partial plan view of the
grinding machine according to fig. 1 wll.h a partial
aectiomdl representation of the work mounting in an
operating position.
FiQ. :i ahnws the tailstock-aide work mountii~y in
sectional representation, with the tailstock ln~ating
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center in a ccrnt.ac;l. Wasition with set steadyr_Pgt-.,
which, h~wRVer, is not shown.
~'ig. 4 shows the tailstock-side work mounting in a
acctional reprosantatiux~, wll.h pressure pin in a
retrarr.~ad intermediate position of tho tailstock quill
with the tailatock locating ~aWcr.
The mounting of a workpi~sc;e 5 on a grinding machine,
for example, i~ ~hnwn in fig. 1. The workpicec 5 is
mounted between the locating r:aiiLer 4 of the work
spindle :if) ~f the headstock 1 and thw locating vcnter 6
with the cantor 11 of the tailst~c:k 3. The mounting and
release of the warkpia~a hetwsan the locating coaster 4
of the work spindle 30 and the luC:a~.i,flc~ center 6 of the
quill 13 is made possible by the tailstock quill 13
being retracted into a r~ar posilluci by traverse of the
tailstock.
The headstock 1 and the t~ilstnc.k 3 are mountQd on s
grinding tablo 2 (only partly slm~1) which is
travez~sable in Lhe G-direc:fi i nn _ The haadstack 1 has a
work spindle 30 which 13 driven via a moLUL' ar.Lve (not
shcrwti) . The tailstock 3 is pravided with a traveling
25, tailstock quill 13 which is axially disYlac:edble inside
thd lmusinq of 'Che tailstoCk 3. The ~antPr axes of the
work spindle 30 of the hendstoak 1 and ut lie quill 13
of Lhe Lailstock 3 ar~ oriented exarf-.1y in alignmQnt
with r~na another. The workpicce 5, with its
longitu~lii~al axis likewise in aliqnmeni-., i :~ mr~untad in
between. A staadyrest 7 with movable jaws 9 is arranga~7.
on the grinding LnLle 2. The grinding spindle 15 with
the grinding wheol I6 is arranged ao that it can be se~i.
in an axially paialldl manne7r rela'Cive to the
arrangement of hPadstock l and tailatock 3 of the
machine tool in the diLe~c:t,iaii of the X-axis
p~sjyendicular to the work momnt i,ng _ In addition, the
- grinding apindlo 15 i3 arxanged in a~~ axially parallel
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manner relative to the Z - axis of the iudvhine tool . The
giiiidinq wheel 16 is set in the direction of the X-axis
at right angles to the workpiccc.
h According to fig, 2, the workpiece is mounted Lelween
the luc;al.inc~ center 4 of thA haadstock 1 aad the
locating center 6 of the tailstock 3. Sliic:e the
wozkYiecr~ 5 in the center 11, which hr~ars against the
locating center 6 of the tailstock 3, 15 very thin-
walles, a centering deformation of the thin-walled
rqgion of the workpiece 5 takcc place as a result uL
this c:aiupressive Iorces applied during t-hP mounting; For
t-he tailstoek-side region of the mounting center of l.li~
wow kpiece 5 is pressed into a rounh share by the axial
rnmpressive force originating from the lvcatiixy c:auLGr
G of Llia l.dllstock 3 in COmbinat~ cn wi th the
fr~.tstoconical locating center 6 of the tnilstock 3.
~n tree canter region of the workpiece 5, a atoadyres~L
coat 0, aga.irm~ wtllc;h a steadyrest 7 with mnv~hl a haws
9 is pat, is ground with the grinding wheel 1G, which
can be sdl. a!. riyh~ angles 'CO the workpiPC:~ a~rnrding
to i=hR X-axis and displaced in an axially parallel
mann~r to the ~-axis an~i is arranged on r.hA car. inding
25, spindly 15_ The Workpiece 5 is then rcoet and finish-
maahined in order to ~Ll.din, iri this way,
geometric:~tly accurate workpiece S, i.c. a workpiece 5
free of circularity csrrurs .
Shown in fig. 3 is the emLucil~cmut for the frustoeonias 1
conriguraLion of the I cn~ti ng center 6 of the quill 13
of the tailatock 3, the locating cenLdr 6 being tipped
with carbide bodies bA tnr reasons of wear and being
arranged on z guide element 24, which is 1n alignment
~rith Lhe longitudinal axis oi= the qt~i 1 1 13 _ Tho guide
elc~mant 2d has a central longitudinal bore whlcai is
stepped in dia~ud~c~w, with bore sections hRC~.oming
Smaller, toward the end of the locating oenter. At the
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opposite end of the guide element 24, Ltie bore is
deslyjied with its largest diamRfiar in order to
ar-commodata an adjustable Ecrcw 23. The followixy kwre
secllon has a smaller diameter. Arr~angecl, in this born
section is a spring element 22 which is adaptesc3 ~~ l.tila~
diameteL dixd which bears on the Ana side against th~
and face of an adjustable screw 23 and on tlle~ V~tle.c
side agaim~ ~tm enc~ face oL a cylindrir.~1 piston part
~6 of a pressuro pin 21 having the name dianiatd~. Ttie
other en ~l ~i l.tie cylindrical piston pa rt ~ 6 has an
axially running rod part 27 having a substantially
smallew altimeter. The rod part 27 is pa~garl through the
outlet bore of the guide element 24. The pressure piiz
21 prrslvdded with the spring element: 72 aPplias an
axial. ford 32 to th~ workpiece 5.
In fig. 4, the quill 13 of the tailotock 3 is retracted
to an interm~sdia~c~ p~5.t~ion according to arrow p~.~ition
10, so that the taper of the locating center G of thr~
tailatock 3 is no lu~~yer~ in pressure contact wi th thR
workpiecP 5, arr_.ording to position 1111. However, the
pressure-pin rod 27, wl~ti the spring force of thw
spring elPmPni-. ~~, PrPSSps the workp~.ece 5 against the
locating center 4 of the wuwk spindle 30 of. r.ha
headstock 1.
The SteadyregT 7 wnSmrca~ the radial orientation of the
workpiocc 5 with regard to the luudl.lnq center 4 or 'Che
work spindle 30 and the lnr.~ti ng canter 6 of the quill.
13. The locating center 6 oL l.he tailstock 3 can
c:ujisequently be retracted 1-.~ an intorm~diate position
10 without impairing tho centering, ebtal~~ed during the
mou~Wiciq, of the workpiece 5. Thi s travol must at least
bP ~n large that the workpinec 5 no longer ouum5 Into
contact wi~W.rie locating center 6 of the quill 13, so
that thR workpiace 5 is given a contact-fr$e c~uLew
111. It is therefara surricient for the amount of
travel to th;~ intermediate position 10 to be just a
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few tenths of a millimei:e~ . Slttce the ZorQue of the
rotary mcv~mant. of. the workpiace 5 is transmitted by
the locating center 4 of the hea~;la L~c:k l, the workpieCe
must ba pras~w~1 ar~ainst th~a locating canter 1 of the
5 work spindle 30 by a force 32. Tlte pressure pin 21
provides this tri.c-.tional connection via the rod part
27. In this way, the workpiece 5 is driven in a
rotational manner and ig hw1 ri in thQ conterod position
by the ateadyreat 7, so that cmuplel,e machining of the
workpieCe 5 aft the oot.Rr rircumferenc~ is made
possible. In this way, the outer ciZCm.ureremce of the
tailsZOCk-side end oi~ i-.hR wr~rkpiaca 5 can also be
machined without inaccuracies, i.e. circ:ularlLy errors,
being transmitted to the w~rkriere 5_
Wlth the method according to the invention and the
apparatuo for carrying out the matho~l, dL least one
sequence of operations on another machine tool with
another mounting system can be disperm~sd wlLh, as a
result of which the machining angts ran be reduced. Tho
method according to the invention and the aYpdLaLus
developed for it are on no account rRstrictmd to the
grind~Lng of workpieoe$: on the contrary, oth~s~
precislcit tadchining operations can ,~ 1 :~~ he carried out
~5, accordingly.
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