Optical gauging system for monitoring machine tool alignmen

Boissevain, A. G.

Nelson, B. W.

English

NASA Technical Reports Server

' , \ \  ;-- - 
4 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION. 
Whs~~notan, 0.G aO:QS16 0 
* 
I 
~~I /Sc ien tLdic  & Technical Infomation b~vimion 
Attention8 Hism Winnim H. Morgan 
FROM: ~ ~ / 0 f f i c e  of Ass i~fapt  General Counsel for 
Patent Matters 
SUBJECTS. Announcement of NASA-Owned U. 8. Patent8 i n  STAR 
In accordance with the procedure6 agreed upon by Code GP 
and Cods GSX, the attached NASA-0wned.U. S.'Patent ie being 
forwarded for  abstracting, and announcement i n  NASA S%!AR. 
. . 
6 .  
Thcr dollowing information i e  provided1 
\ 
U. S. Patent No. 8 
Government or 
Corporate Employee 
Supplementary Corporate 
Source (if  applicable) 
NASA Patent Case No. a ' 
SOTE - If  this patent covers an invention made by a corporate 
employee sf  a NASA Contractor, the following 3.8 applicable8 
yes 0 NOET 
3ursuant t o  Section 305(a) of the National Aeronautics and 
Lpace Act, the name of the Administrator of NASA appear8 on 
the fkrst page of the patent; however, the name of the actual 
inventor (author) appears at the heading of Column No. 1 Of 
- 
.the Specification, following the words *. i witjr reopect to 
a an invention of . . . 
.. 
d 
zlizabeth A, Carter . -  
. . .  
~ncl0s;tre PI 
co2y of Patent aited abwe 
I 
, f  ' 1 
. . . I  
- 4 (NASA CR OR TMX OR AD NUMBER) (CATEGORY) 
Y 
https://ntrs.nasa.gov/search.jsp?R=19710017197 2020-03-17T03:07:26+00:00Z
Feb. 23, 1971 A. G. BOISSEVAIN ET AL 3,565,530 
OPTICAL MACHINE TOOL ALIGNMENT INDICATOR 
Filed Dec. 28, 1967 2 Sheets-Sheet 1 
INVENTORS 
ALFRED G. BOlSSEVAlN -.-,- 
BYRON W. NELSON 
BY -4 G.-A 
ATTORNEYS 
Feb. 23, 1971 A. G. BOISSEVAIN ET AL 3,565,530 
OPTICAL MACHINE TOOL ALIGNMENT INDICATOR 
Filed Dec. 28, 1367 2 Sheets-Sheet 2 
INVENTOE 
A L F R E D  6. BOlSSEVAlN 
BYRON Vd. NELSON 
C 
- 
3 565,530 a P United States Patent Ofice ,,,, , ,,, 23$ 
3,565,530 
BbP'1[Pb;rPLk MAC TOOL ALIGNMENT 
IIBTIDICATOR 
Alfred 6. Boissevain, Palo Alto, and Byron W. Nelson, 
Samta Clara, Calif., assignors to the United States of 
America as represented by the Administrator of the 
National Aeronaufics and Space Adnniniseadon 
Filed Dec. 28, 1967, Ser. No. 694,246 
Hnt. aCI. G0lb 11/26,11/02,9/08 
U.S. C1. 356-154 5 Claims 
while the element is in place on the machine and v\lRi:ib 
apparatus does not interfere with nolrnai machine o p  
eration. 
An object of this invention is the provision of a.rl ap- 
tical gauging system for projecting a magnified shadov~ 
of a machine element such as an electrode on a scrcen, 
the magnifica!ion of which shadow is ieadlly vatiablc 
over a wide range. 
An object of this invention is the provision of an op- 
tical gauaing system for alignment of tlre electrode of 
an electrical discharge machine by means of which sys- 
ABS'$IRACT OF THE DISCLOSURE tem the position of-an adjusting- tool on the electrode is also viewable to facilitate the alignnicnt process. 
An optical gauging instrument for checking the align- The above and other objects and advantages of the in- 
ment of a machine element such as the electrode of an 1s vention are achievec; bv means of an oatical syrtem corn- 
-- 
electrical discharge machine, comprising a light source ~ris ing a light source for providing a beam of rrght ~ h i c k  
which provides a beam of light projected along a path to is projected along a light path to fall upon a viewing 
fall upon a viewing screen. The electrode is located in surface such as a screen. The machrne electrode is lo- 
the path of the beam whereby an image thereof is pro- cated in the path of the bean1 whencby an rrnagc of tile 
jected on the screen. A lens, or lenses, are positioned 20 electrode is projected onto the screen. A lens or lens 
between the light source and electrode to concentrate system, is included between the light soi~rce and electrode 
the beam on the electrode, and a projection lens may be to concentrate the beam on the electrode and a prom- 
positioncd between the electrode and screen for produc- tion, or image forming lens, is included between the e!ec- 
ing an enlarged image on the screen. The screen pref- trode and screen for producing an 1111age of tllc e1eciroi.I;: 
erably is movable and may be positioned at an oblique 25 on tlie screen. The screen is adjustably aos~iioned and 
angle with the optical axis of the system for further en- may be positioned at an oblique angle with respect to 
largement of at least one dimension of the electrode image the optical axis af the system to provide added magnifica- 
on the screen. tion of the image in one dimension witilorrt fuithcr mag- 
nifying the image in a dimension at light angles thc~cto 
30 In particular, the lateral dimension of the electrode image 
The invention described herein was made by an em- may be greatly n~agnified without increasing the image 
ployee of the United States Government and may be in the longitudinal direction of the e~cctrode. 111 this way, 
manufactured and used by or for the Government for the screen does not have to be placed at a g e a t  di~lance 
governmental purposes without the payment of any royal- from the electrode to obtain the deslred magnification of 
ties thereon or therefor. 35 lateral deviations of the electrode image or shadow 
This invention relates to an optical gauging system and The invention will be better understood from the fnP- 
more particularly to a non-contacting system for gauging, lowing description when taken in conju~ction with th:: 
inspecting and monitoring the alignment of a machine accompanying drawings. In the drawings, wsleiein like 
element. Although the invention is described hereinbelow reference characters denote the same parts in the stv- 
for use with an electrical discharge machine for checking 40 era1 views: 
alignment of a wire electrode carried thereby, it is not FIG. 1 is a perspective view d an clcctr;cal clicchai SL 
limitcd to such use, and may be used in checking the machining apparatus showing the cove! optical align- 
position and alignment of other machine tool parts, and ment system of this invention applied thereto; 
the like. FIG. 1A is a front view of the viening screen ac 
The electrode used in a machine for electrical dis- 45 taken along line IA-lA of FIG. 1; 
charge machining of metal stock must be straight for FIG. 2 is a diagrammatic representation of iEie optical 
accurate machining. Prioring art arrangements require alignment system shown in FIG. I ;  
that the electrode be removed from the machine and FIG. 3 is a simplified diagrammatic iepiesectaiion 
checked for straightness either by use of a flat plate which is similar to that of FIG. 2 bat showing the view- 
or by use of a contour projector. Disadvantages of such 50 ing screen at an oblique angle lo the optrcai axis of the 
prior art methods of alignment include the fact that the system for magnifying the lateral drmensions of the 
methods require much time, and that the electrode may electrode image: 
be bent when installing or reinstalling the same in the FIG. 4 is a re~resentation which is similar to ha'. of 
machine thereby necessitating removal and realignment. FIG. 3 and including an erecting lens for p~ovid~ng  2111 
Further, with some contour projectors only a portion of 55 upright shadow of the electrode on the viewing screen, 
the electrode may be viewed at any one time. Furthermore, and 
there is no positive method of checking the alignment with FIG. 5 is a view which is similar to that of F-XG 3 i?:,c 
the electrode in place on the machine with these prior showing a curved viewing screen positioned at an obliqac 
art methods and apparatii which require removal thereof angle to the optical axis. 
from the machine. 60 Reference is now made to FIG. 1 whereir?. tiere 1s 
An object of this invention is the provision of an align- shown an electrical discharge machining zpparatus !0 o: 
ment apparatus for checking the alignment of machine conventional design. As shown in FIG. 2, a typicaS eEec- 
elements such as electrodes, which apparatus avoids the trical discharge machining device includes a bed 12 upon 
above-mentioned disadvantages of prior art means. which the workpiece of metal stock I$ to be rnach~i~ed by 
An object of this invention is the provision of an 65 electrical discharge is mounted. A tank 316 (FIG. 1) sui- 
optical alignment apparatus by means of which the align- rounds the stock 14 at the sides thcreoC and contarns a 
n~ent  of a machine element may he checked with the ele- dielectric fluid in which the workpiece is .rorrnclly sub- 
ment in place on the machine. merged in the machining process. 
An object of this invention is the provision of an op- The electrode 18 for machining the s t s ~ k  is carried 1711 
tical a l ig~~n~ent  apparatus which allows for the checking 70 a chuck 20 which is both rotatably and ~ - 1 t ~ c a i 1 ~  rl~ov- 
and adjusting of the alignment of a machine element able (as illustrated by the arrows 21 and 22, ~cspc~trvcly 
3 4 
in FIG. 2) .  As diagrammatically shown in FIG. 2, a ously, the greater the screen angle departs from a posi- 
power supply 23 is connected to the electrode BO and tion normal to the optical axis, the greater the transverbe 
stock I2 to provide the necessary potential for spark dimensions of the electrode image. 
macbning the stock. In operation, the spark erodes the The invention having been described in detail in ac- 
workpiece to produce a hole, or cavity therein of slightly cordance with the requirements of the Patent Statutes, 
greater size than the electrode but of a corresponding various changes and fodifications may suggest themselves 
configuration. Generally, the electrode is of a non-cy- to those skilled in this art. For example, as shown in 
lmdrical shape for  producing a llole or cavity of a corre- FPG. 4, an erecting lens 52 may be located between the 
sponding shape. The chuck, of course, is Lowered, but lens 40 and screen, to provide an upright image of the 
not rotated, during the machining process. It will be a p  electrode on the screen. 
parcnh that the electrode 18 must be positioned in axial Also, it will be apparent that a sharp image of the elec- 
aiig~lment with the vertically movable chuck to provide trode is obtained on a flat screen, such as the screen 42, 
lor accurate location of the electrode as the chuck is only if the lenses are properly formed or corrected for 
lowzred during the machining process. Any misalignment aberration, astigmatism, and other such defects. With in?- 
or cuavature of the electrode would result in an unde- I j perfections in the lenses, the image is blurred; 
srred, overslze aperture in the workpiece. at the upper and lower opposite ends thereof which are 
The novel optical alignment system of this invention at the greatest distance from the optical axis. To compen- 
lacludes a hght source 26 which may comprise a pro- sate for such defects (and permit the use of less costly 
jector of conventional design. As seen in FIG. 2, the pro- lenses) a curved screen may be employed, such a? the 
jactor includes a lamp 28 energized from a source of 20 screen 42A shown in FIG. 5. The screen is generally in 
power, not shown, Light from the lamp 28, and reflected the form of a section of a cylinder to bring the upper and 
light frorn a concave m i ~ r o r  30 behind the lamp, is di- bwer ends of the electrode image into better focus there- 
rected to a condeils~ng lens 32 (or lens system). The rays on. As with the flat screen one or more g~liclelines 43 ale 
from the contiensing lens 32 converge at the projection formed thereon for detecting lateral excursions of the 
or enlarging, lens 34, and are directed to a condensing 23 electrode image. Also, the curved screen may be posi- 
lens 36 intermediate the projector 26 and electrode 18. tioned at  an oblique angle to the optical axis, as illus- 
The condensing lens 36 (or lens system, if desired) may trated, in the same manner as the flat screen, in order to 
be of any 5ilitable type, including a lens of the Fresnel magnify lateral excursions of the electrode image. It is 
type. intended that the above and other such changes and 
Substantially all of the light available from the projec- 30 modifications shall fall within the spirit and scope o i  the 
tor 26 is directed onto the condensing or enlarging lens invention as defined in the appended clain~r. 
40. The chuck 20 may be raised to a position wherein the We claim: 
entire exposed portion of the electrode 18 and preferably I. An optical gauging system for checking the align- 
a portion of the chuck 20, are included in the cone of ment of an elongated electrode of an electrical discharge 
rays frorn the condensing lens 36. The optical system in- 33 machining device comprising: 
~liiding the lenses 36 and 40 are arranged such that the a light source, 
electrode occupies substantially a maximum possible a viewing screen upon which light from the source is 
cross-sectional area of the light cone for maximum illu- directed, said electrode being disposcd in the path of 
rnina1h-i thereof. That is, the electrode is arranged to light from the source whereby a shadow of the elec- 
subtend a maxin~um possible portion of the light from the 40 trode is cast upon the viewing screen, wherein said 
condensing lens 36. path of light corresponds with the optical axis of the 
Substantially all of the light which passes the electrode system, 
and chuck also passes through the projection lens 40 (or said viewing screen having a fiat viewing surface at an 
lens system 2f d c ~ i ~ c d )  from whence it is directed upon oblique angk with the optical axis of the system for 
a viewing surface 42, such as a screen. The shadow 44, 43 increased magnification of the electrode image on 
which comp-ises an enlarged image of the electrode is the screen in the transverse dimension of the elec- 
illereby projected on the screen. By using a projection lens trode and of lateral deviations thereof, and 
system 40 instead of a single lens thereat, improved image projection lens means between the electrode and view- 
resoSution is provided. ing screen to provide an image of the electrode on 
In the illerstraied arrangement the screen is provided 50 the screen, said viewing screen having at least one 
with a base 46 Eor suppolting the screen in an upright calibration line thereon extending in the direction of 
position. The base simply may rest upon the flat upper the longitudinal axis of the electrode image. 
surface of a supporting table 48 extending from the ma- 2. An optical gauging system for checking the align- 
chine. As seen in FIG. lA, one or more vertical calibra- - -  ment of an elongated electrode of an electrical discharge 
",on lines 43 are included on the screen to serve as a machining device comprising: 
guide ~ r r  detecting lateral excursions of the electrode a light source, 
image. 11- desired, a guideline may be drawn on the screen a viewing screen upon which light from the source is 
by marking the screen at the center line of the electrode directed, said electrode being disposed in the path of 
fiolder image as the electrode holder is lowered or raised. light from the source whereby a shadow of the elec- 
Wltb the ~llustratcd arrangement, the image of any 60 trode is cast upon the viewing screen wherein said 
tool, not shown, used for straightening the electrode 18 screen is curved in the form of a section of cylinder 
while it is carried by the machine also will be projected to provide a sharper electrode image on the screen, 
on the viewing surface 42 to facilitate locating the tool wherein said path of light corresponds with the op- 
with respect to the electrode. By rotating the chuck, devi- tical axis of the system, and 
atlons of the electrode from the chuck axis in any lateral 65 projection lens means between the electrode and view- 
direction may be detected, and corrected. Since there is ing screen to provide an image of the electrode on 
no physical contact with the electrode by the optical sys- the screen, said viewing screcn having at least one 
tern, the measuring technique does not affect the position calibration line thereon extending in the direction of 
of the electrode. the longitudinal axis of the electrode image. 
In accordance with one feature of this invention the 70 3. The optical gauging system as defined in claim 2 
screen may be mounted, or positioned, at an oblique wherein said curved screen is positioned at  an oblique 
angle wlth the optical axis of the systcm, suck as illus- angle with the optical axis of the system for increased 
trated in FIG. 3, whereby the transverse dimensions of magnification of the electrode image in the transverse 
tile electrode image are further magnified thereby further dimension of the electrode aacl of lateral deviations 
magnifying any Lateral excursions of the image. Obvi- 75 thereof. 
3,565,530 
5 
4. An optical gauging system for checking the align- 
6 
oblique angle with the optical axis crf tile sysbeni f ix  
nlent of an element of a machine or the like, said system increased magnification of the elcct~ ode image on the 
comprising: screen in the transverse dimension of the e l e c t ~ o i ? ~  
a light source, and of lateral deviations thereof, 
a viewing surface upon which light from the source is projection lens means between the cleclroJe a17d viea - 
directed, said light being directed along a path which ing screen to provide an image of thc elcct:ode ci? tt:e 
corresponds to the optical axis of the system, screen, said viewing screen havicg dl( Eeii5t 01-c cati- 
said viewing s~lrface being positioned at an oblique bration line thereon extending in the i l l r  ection of tile 
angle to the optical axis of the system for enlarge- longitudinal axis of the electrode  ria 'ge, and 
ment of the lateral dimensions and deviations of the condensing lens means between tbc Erl-ii iourcc d n i i  
machine element without further naagnification of the electrode to form a cone of the i l i~nt ~ I O ~ I I  !he I zht  
longitudinal dimensions thereof, source in which cone said elc~iiode n ~ a y  b,: po,r- 
said machine element being disposed in the path of tioncd 
light from the light source and the shadow of the References Cited 
nmachine element falling upon the viewing surface 16 
to provide an image of the machine element on the 
viewing surface. 
5. An optical ganging system for checking the align- 
ment of an elongated electrode of an electrical discharge 
machining device comprising: 20 
a light source, 
UNlTED STATES PATENT S 
10/1949 Brennan ------ --_. 356-FC.4"; 
10/1952 Polk et al. ------_- 3 56-1 h4X 
4/1962 Jacksoit ------_----- 353-8OX 
7/1957 Fuller 35R- 16.5 
2/1963 Coakley ----------- 356-165X 
- 
a viewing of the screen upon which light from the 
source is directed, said electrode being disposed in the RONALD L. WPBERT, Primary Exaanitter 
path of light from the source whereby a shadow of P. I<. GODWIN, JR., Assistant Examiner 
the electrode is cast upon the viewing screen, wherein 25 
said path of light corresponds with the optical axis U.S. Cl. X.R. 
of the system, 356-171.164, 172; 350-9 
said viewing screen having a flat viewing surface at  an 


Optical machine tool alignment indicator Patent

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server