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Патент USA US2406299

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'Aug- 20,1945»
M. KouLlcovrrcH
2,406,299
.MACHINE TOOL WITH PHO'TOELECTRIC POSITIOYNING LOF THE WORK TABLE
Filed Feb. 11,v 1942
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2 sheets-sheet 2
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Patented Aug. 20, 1946
2,406,299 I
.UNITED ¿STATES PATENT OFFICE
¿2,406,299
MACHINE TOOL WITH BHOTOELECTRIC
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I 'Ifosrriomndor THE WORK TABLE
@Maurice "Koulicovitch, Geneva, Switzerland, vas
Asignor »to "Societe '.Genevoise yd’lnstruments de
4flihysique, `v(ternera,
:rgSwvitzuer-land
Switzerland, , a ¿firm of
lApplication "February 11, m42, Serial No. 430,458
"«IiliîSwîtìzveiflalil‘d December-2%
„neiging (ci. 25o-41,5)
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»grid :I ¿is vdiminished, -«the .resulting reaction of
@The .object „of -1th@ ¿present Í:invention «,- is Ii a gma
-chineratool 1 with ¿photo ¿electric positioning ~ ¿of :the
¿the :cell `5 „producing :a :change »in -the l currentjof
work table. It will be used with advantage .for
.instance .to determine~=the ...position .'of .sliding
¿tables lof. measuring Jnachines r¿and ¿of precision l.;
:either .directly,ias,shown in.»full^lines,f.or ¿by Zmeans
tool machines such as center punching machines
and precision.drillinglmaclii?es .
‘the ¿outer relectrica1 .circuit `'L yThis circuit «1,
.of ¿a .relay~:8,‘ as shown in .dotted lines, 'operates
-the;signaling‘zapparatus'fii.` represented in_ithe _form
>.of :a îmeasuringwinstrument, ¿and whichr could îbe
replaced by a control apparatus intended for any
The usual method for determining a position
function, such as for instance to stop the mov
consists in observing with a microscope the divi
able object.
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sions of a scale carried by the movable object
Two other embodiments, in which the grad
and to bring the image of a given division to
uation is traced in black on a reflecting or a
correspond with a reticle provided in the micro
transparent scale, are shown in Figs. 2 and 3.
scope. This method has the drawback that the
Fig. 2 shows the case of a surface lighting of
precision of the reading depends on the skill of
the operator and that the latter has to look in 15 the scale and Fig. 3 that of a transparence light
tently into the ocular, which operation is fati
guing.
The apparatus according to the present inven
ing through the scale, with the same graduation.
Lighting, in both embodiments is secured by a
source of light 3 with its optical condenser I0
sending its light into the field of the apparatus,
tion is characterized by a photo-electric cell fac
by means of a mirror II, or directly. In
lng the scale, by a grid inserted between said cell 20 either
both cases, an objective I2 projects the image
and said scale, and by a source of light arranged
of the graduation 2 on the grid’I; 5 is the photo
in such a way as to send its beams onto the scale.
electric cell. n Elements 1, 8 and 9 are the same
The grid presents spaces open to light (openings
as in the previous figure.
or transparent zones) . The beams of light com
It is possible to superpose a graduation traced
ing` from the scale and passing through the grid
impress the photo-electric cell, except when the `
divisions yof the scale cover the open spaces of
in dark on a bright background or in bright on a
dark background, or the image thereof, onto a
grid provided with slits or with full spaces cor
respondingI to the tracing; in place of slits, one
In this latter case, there is a corresponding re 30 could use full transparent spaces. One will
action of the cell.
choose in each particular case the most conven
The current variations of the photo-electric
ient combination, depending also whether one v
the grid and intercept the light feeding the cell.
cell, amplified if necessary and transmitted fur
ther, can control the operations involved in the
applications of the apparatus.
In this way, the necessity to look into an ocular
and the fatigue resulting therefrom are avoided.
The attached drawings show, by way of ex
ample, four embodiments of the object of the
present invention.
Each one of the Figures 1 to 4 shows schemat
ically, and with sectional views, one of these em
bodiments.
.
In the embodiment shown in Fig. l, the grid I
represented partly in sectional view is superposed
on a graduated scale 2 which is movable and onto
which an electric lamp.3 throws its light. The
graduation is traced in black on a transparent
will characterize the superposition of the grad
uation and of the grid by a decrease or by an
' increase of the light received by the photo-elec
tric device.
'I'he graduation 2, the position of which is to
be determined, can be composed either of equi
distant straight lines, as shown in Figs. 1 to 3,
or else of groups of lines, or even of figures, re
peating themselves at every unit interval of the
graduation. This arrangement has the advan
tage to permit greater variations of the amount
of light passing through a grid made in accord
ance, and at the same time to obtain a high de
gree of precision, because each element of the
tracing can be thinner and its superposition onto
the corresponding element of the grid will be
background. The grid I presents a, few slits 4a,
better defined.
4b, 4c, 4d, 4e, by which the light passing through
If the graduation is composed of groups of
the lighted background of scale 2 can excite a 50 parallel lines, there is advantage to arrange that
photo-electric cell 5 enclosed in a housing 6. The
the components of a same group of lines be not
shape of the slits of the grid I is such that for
equidistant, in order that their exact and total
the determined positions of scale 2, in which
superposition into the grid can only obtain 1n a
these slits superpose themselves onto the grad
single
,position deiined for each group of lines.
uation of the scale, the light passing through the
2,406,299
.
The embodiment shown in Fig. 4 is based on .
this principle. In this iigure, one sees the objectives I 2, the groups of lines Ma, |417, |40, etc.,
separating the unit intervals of the graduation,
groups in which the lines are not equidistant be
tween themselves, the grid I provided with the
slits I5a, |5b, |5c, etc. . . . corresponding to theKV
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parts interposed between said scale and said
`
cell, the transparent parts of said grid being
spaced apart in correspondence with and being t
inv less number than said graduations, and means i Y
for directing an illuminated image .of> several of
said graduations through the grid‘to said cell.
2. In a machine-tool With photo-electric posi
`tioning of the work-table, in combination, a work
table carrying at least one scale having precision
shown on this figure, neither the other. parts of 10 graduations .arranged in succession at spaced
method of graduation of the scale, and the photo?
electric cell 5. The lighting, however, is not
the electrical circuit.
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The graduation 2 neednot be made necessarily
' points- inthe direction of movement of said table,
a photo-electric ycelljfacing said graduations, a
grid having transparent and opaque parts inter
Y with more complex tracings of any` shape'which
posed between said scale and saidcell, the trans
can be used in the same way in cooperation with 15 parent parts of said grid being spaced apart in
a grid made in accordance.
correspondence withA and being in less number
The object of the invention having thusbeenîu .thansaid graduations, and an optical device for
described and illustrated in the accompanying ,_ f projecting an illuminated image Vof several of
drawings, need not beexplained further.>>said graduations through said grid to said cell.
What is claimed to be new is:
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3. An arrangement Las claimed> in claim 1,
1. In a machine-tool with photo-electric posi
wherein' said graduationsare arranged-in groups
tioning of the work-table, in combination,- a
and the graduations of eachgroup'arenofdi's
work-table carrying yat least one scale having
precision graduations arranged in succession at
V4f. An arrangement'A as claimed in claim *1, '
spaced points in the direction of movement of 25 wherein said grid is’ stationary with respect to
said ~table, a photo-electric cell facing said gradu
ations, a grid having transparent and opaque
with parallel straight lines, but can be realized
sirnilar'form.>VA
said'cell.
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