Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FlFLD OF THE NVENTION
The invention relates to an apparatus and method
for manufacturing a three-dimensional body, such as a body
having an upper surface topology reproduced from
electronic data inforDIation, derived from o-ther sources
sl.lch as from a drawing, or another article, and is of
particular interes-t for use in the foundry pattern
in~ustry, but has many other uses.
BACKGROUND OF TEIE INVENTION
Foundry pattexn craftsmen require many years of
careful training, and must exercise a high degree of
.skill. The accuracy of the firlished casting is dependen-t
entirely on the accuracy of the pattern itself, and
conse~uently the work cannot be undertaken by unskilled
-trades people. The training of such pattern makers in
~act represents such a considerable investment that few
companies are willing to undertake it. In addition, it is
becoming difficult -to find new recruits to enter the
trade.
In addition, since the trade or craf-t is highly
skilled, and is relatively slow, the cost of foundry
patterns is becoming excessive.
Usually, the patterns are made of soli.d wood,
usuall.y sections of wood Joined together, so as to provide
the desired exterior -topology of the finished casting.
There are many other instances when it is
desired to reproduce a surface or topology using
elec-tronic data information. For example, topologs~ models
may be made from topographical map information, or from
EDP information derived ~rom stereo photographs, the
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infol^mation being used -to ma~,e a three-dimensional
-topology model. Similaxly, architectural drawi.n~s, or
marine drawings may al.so be compiled as E~P information.
In addition, there are many manufacturing techniques and
articles which should ideally be modelled prior to
finalizing the design, but in many cases are not possible
due to the difficulty of making satisfactory patterns or
mode].s at an economical price.
For all of the.se reasons it is, therefore,
desirable to pro-~id.e a machine capable of reproducing a
predetermined topology, on -the upper surface of a 'body. In
part;icular, i-t is desirable that such a machine shall be
capa'ble of reproducing the three-dimensional topographical
sur~ace of an article, from a drawing of that article.
: It is also desixable that such a machine should
be capable of reprodu~ing the topology of an article
itself.
~RIEF SUM~ARY OF T~E INVENTION
The invention therefore seeks to overcome the
foregoing problems, and to achieve the general objective
set out above, and. comprises apparatus having an extruder
and extrusion head, operable intermittently to extrude
predetermined quantities of a fast set-ting plastic
material, a mounting arm on which said extrusion head is
mounted, a carriage bar on which said mounting arm is
mounted, a base defining a surfaces extrusion head drive
means for driving said extrusion head carriage bar drive
means for driving said carriage bar, and control rneans for
contrc)lling said extrusion head, said extrusion head drive
means and said carriage bar drive means, separately and
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independen-tly from one another 3 whereby to procure three
a~es of movement Oe said extrusion head. to progress.ively
er~trude and deposit port.ions of a three-dimellsional body
having a predetermined topology on said surface of said
base.
More par-ticularly, it is an objective of -the
inventiorl to provide such an apparatus including data
storage means, commun.icating with said control means,
whereby data relating to the -topology of such a body may
be stored and processed, and reproduced for a programmed
operation of said control means.
More particularly, it is an objective of the
invention to provide a method for the manufacture of a
solid body having a precletermined three-dimensional upper
surface -topology and comprising the steps of deposi-ting a
strip of a settable plastic material from an extrusion
head, along a predetermined linear path, moving at least
par-t o said extrusion head in a vertical plane, while
moving the same along said linear path, moving said
cxtrusion head laterally of said predetermined linear path
by a predetermined increment, again traversing said
extrusion head along said linear path, and extruding
another strip of said material, and again varying the
vertical position o said part of said ex-trusion head
while moving the same along said path, and repeating said
steps a sufficient number of times, to develop a solid
body having the desired topology.
More particularly, -the invention seeks to
provide such a method wherein topology information is
input into a data storage means, and such information is
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t.herl accessed to control the movement of such ex-trus.ion
head to reproduce the topology of the article from such
topology information.
More par-ticularly, it is an objective of the
invention to provide such a method wherein the
three-dimensional topology surface o such body is
subsequently subjec-ted -to a smoothing and finishing
operation, and is thereafter coated wi-th a wear resistant
metal coating, whereby the same may be used as a pa-ttern
or die.
More par-ticularly, it is an objective o -t,he
inverl-tion to provide an apparatus having the foregoing
advantages wherein said extrusion head incorporates a gate
means, which may be moved vertically to vary the height of
the strip of material being ex-truded, and wherein the gate
means may be tilted, so as to provide the upper edge of
said ex-truded material with an angled surface, and
including means ~or tilting said gate means to provide a
desired angle, for each said strip.
It is a further and ralated objective of the
i~vention to provide a method and apparatus for forming a
body, by extruding a series of flat strips of a settable
compound one above the other, and by ofsetting successive
strips from one another as required, to form an upper
surface topology of predetermined shape.
The various fea-tures of novelty which
characteri~e the invention a.re poin-ted out wit,h
particularity in the claims annexed to and forming a par-t
of this diselosure. For a better understanding of -the
invention, its operating advantages and specific objects
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attained by its use, reference should be had to the
ac~companying drawings and descriptive matter in which
there are illustra-ted and described preferred embodimen-ts
of the inven-tion.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspecti~e illustration showing
an apparatus according to the in~ention toge-ther with a
con-trol centre and information input keyboard;
Figure 2 is a section along 2-2 of the aE)paratus
of Figure 1 with certain parts omitted;
Figure 3 is a fragmentary perspective view of an
alternative form of extruder;
Figure 4 is a -top plan view of a partially
formed topology body from the embodiment of Figure 3; and,
Figure 5 is a sectional side elevation along 5-S
of the body of Figure 4; and,
Figure 6 is an enlarged fragmentary perspective
view of an extruder head of the apparatus shown in Figure
D:@SCR PTION OF PREF'E R_D EM DIMENTS
As best shown in Figures 1 and 2, the apparatus
according to the invention will be seen to comprise the
two main assemblies comprising the three-dimensional
topology forming apparatu.s 10, and the control console 12.
The topology forming apparatus 10 will be seen
to comprise a cabinet 20, which in this embodimen-t
provides the base of -the apparatus on which it stands on a
floor. It is of course ~uite apparent that the base need
not be in the form of a cabinet, but can be in the form of
l~gs or any suitable support frame.
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A work platen 22 is supported on the upper end
of the cahinet 20, and defines a flat workin~ surPace 24,
on which the three-dimensional body B accordirlg -to the
invention will be formed.
Typically the platen 22 will be of .s-teel, and
have a gxound and polished surface 24 to ensure that such
ar-ticles are produced with a flat undersur~ace.
If desired, the surface may be treated with a
suitable "release" material such as is well known in the
ar-t. Along one side of cabinet 20, adjacen-t to the edge
of platen 22, there is provided a horizontal linear track
26. In the embodiment shown, the track 26 consists of
upper and lower channels 2~ formed in a massive solid
member. However, it will be appreciated that the design
and details O:e such -track may vary widely dependin~ upon
ths engineering re~uirements of the particular machine.
An upright carriage arm 30 is provided, having
lower bearing means 32 engaging in the track 26, and such
carriage arm 30 may thus run to and fro along the li.near
pa-th described by the track.
Suitable powered movement means are provlded, in
the form of, for example, a motor 34, arld continuous drive
screw 36, of known d.esign, such as are well known iII the
art and require no ~urther description. Such a rnotor 34
may be either elec-trically powered or hydraulically
powered or powered in any other suitable way, and provided
wlth suitable ~orward and reverse selectors (not shown).
Preferably the motor 34 is a "stepper" motor
such that its actual position can be incrementally
controlled, and its posi.tion is known at any given moment.
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Varia-tions may include a posi-tional detector and
feed back 35 to achieve -the same general purpose.
A generally horizontal support arm 38 extends
laterally from the upper end of carriage arm 30. The
inboard end of the support arm is preferably permanently
attached to the upper end of the carriage arm. However,
deperldin~ upon the engineering of the apparatus, it is
conceivable that the inboard end of the support arm might
be movable laterally relative to the top of the carria~e
arm so that it may traverse inwardly and ou-twardly with
relation to the carriage arm along a linear path normal to
the linear path of track 26.
In this latter case, it would of cou.rse be
provided with suitable powered movement means (not shown)
:~ and controls by means of which its lateral movement may be
controlled in a manner described below.
While reference is mada to such a support arm
38, being "generally horizontal" it will of course be
appreciated that the aGtual configuration of the arm could
be in the form of an arch, or a more complex framework,
the principal function of wkich is merely to extend
la.terally over -the work platen.
In the embodiment shown, the support arm 38 is
joined by bolts 40, to the upper end of carriage arm 30.
: On its underside, it is provided with a
transverse horizontal track 42.
An extruder arm 44 is movably mounted on arm 38.
Extruder arm 44 has, at its upper end, suitable bearings
(not shown) running in track 42, by means of which
-~ extruder arm 44 may be traversed to and fro along the
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length of arm 38. The lower end of arm ~4 extends
downwardly onto surface 24 of pla-ten 22.
Movement of arm 44 is controlled by means of
motor 46 and typically a driv~ screw 48 i.ndicated partly
in phantom.
Motor 46 will preferably be similar to mo-tor 34,
CO that the drive screw 48 can be moved in increments, and
its position is known.
A position detector for extruder arm ~4 can also
be used, with a feed back 47 for similar purposes.
Extruder arm 44 supports an e~truder head 50.
E~truder head 50 is shown in more detail in E'igures 2 and
6. It is connected to a container 52, con-taining a
sllitable settable plastics material, by means of, for
eY.ample, flexlble hose 5~. Container 52 is shown mounted
O}l arm 38. It will, however, be appreciated that -the
mounting and location of the container 52 will depend upon
a number of factors, and it could be supported
independently. Preferabl~, in accordance with known
practice in the art, it may also comprise a heating
element, a power-operated screw conveyor and the like, and
it may be adapted either for use with granular solid
plastic material, or powdered material or other form~ of
material depending upon the par-ticular design of the
apparatus in each case. The container 52, thereore, is
merely a schematic representation of a source of settable
pla~tics material and is not -to be regarded as definitive.
Head 50 comprises opposed side walls 50A and 50B, forming
a generally inverted U-shaped structure7 open a-t the
bottom and one end 51~
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The extruder head 50 contains wi~hin it a
vertically movable doctor blade or gate 56, con-trolled,
for example, by means of rod 57 and cylinder 58. In -this
way, the blade 56 may be moved upwardly and downwardly
within extruder head 50 for reasons to be described below.
Again, the represerltatiorl o a doctor blade 56 and
cylinder 58 are representative of a v~riety of different
means whereby the end result may ~e achieved.
A position detector 60 is preferably mounted on
cylinder 58, to indi.cate the position of gate 56. A feed
back circuit (not shown) connects to the controls
(described below) so that the location, or heigh-t, of gate
56 is known at all times.
The purpose of the extruder head 50 is to
extrude successive relatively thin sections of settable
ma-terial, wherein the upwardly directed surface or profile
varies in height above the level work surface 24. One
side wall 50A of extruder head 50 i.s o reduced width,
terminating at 53 short of the end 51 to allow material to
be extruded therefrom, directly into contact with the
previously ~xtruded section.
An air jet assembly 62 (shown fragmentaxily in
Figure 1), is preferably mounted on extruder head 50 to
direct air Jets -through appropriate openings 63 i.n the
wal.]. 50B onto the material as it i5 extruded. The jet is
50 directed so as to deflect the material into contact
with the previously extruded section.
The undersurace of the blade or gate 56 will
define the top surface of the extruded body. I-t will be
appreciated that the hose 54 is adapted to supply the
ma-terial to -the ex-truder 50 below the blade 56.
If each thickness of e~txuded material is
extremely thin, then a body would be built up by extruding .
successive strips, the upper edges of whi.ch de.fine an
upper s~rface which would approximate very closely to the
desired surface of the ar-ticle to be modelled.
Howe~er, as a practical matter, it is desirable
to extrude the material in strips which are somewhat
thicker, and, as a result, the upper surface of the body
will define a series of stepped ridges.
Whi:le these may be finished off with a filling
or polishing opera-tion, it is desirable as far as possible
to reduce this to a minimum.
Accordinglyl the invention provides that the
gate 56 may be tilted, i.e.l rotated about a longitudinal
axis. The degree of tilt or rotation will define the
angle of slope along the upper edge of the extruded strip.
Typically, using suitable EDP techniques, this
angle may be calculated automatically in the program for
each strip, or indeed corltinuously along the length of
each strip, so as to op-timize -the angle of the gate 56 at
all points.
~ The mechanism whereby the angle of tilt of the
;~ gate 56 may be adjusted is shown in Figures 1, 2 and 6.
This will be seen to comprise a pivot mounting 64, on the
upper surface of blade 56, connecting it to the l.ower end
of the cylinder rod 57.
The rod 5'7 is extended upwardly through -the
position detector B0 as extension 59 and thus moves up and
down in unison wi.th the up and down movement of the gate
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56.
At a suitable height on rod 57, a clamp 66 is
fastened. Clamp 66, in turn, supports a cylinder 68,
from which extends a rod 70~ The lower end of rod 70 is
connected by means of a crank lever 72 to the upper
surface of gate 56. A suitable vertical slot 74 is
provided i.n side wall 50B of extrusion head 50 to receive
the crarlk lever.
A posi-tion detector 76 is also mounted on the
cylinder 68, so as to sense the angular position of the
gate .56.
It will of course be appreciated that, the
mechanism whereby gate 66 is raised and lowered, and is
til-ted to and fro, may vary depending upon the design of
thc machine. The mechanism shown is merely exemplary for
the purpose of understanding the invention.
The console 12 will consis-t of any suitable type
control devices. In this embodiment there is shown a
table ~l and a computer terminal 82 (and screen)
connected to the apparatus l0 by a suitabls cord ~4.
In operation, an OperAtOr will first of all
program the computer 82 by inputing the data relating ~o a
body having a predetermined topology. Such data will
essentially be the coordinates of the topology of the hody
along three reference axes. The information will, of
course, simply be -the height of a particular point of the
body above ths surface 24 (one axis) at any particular
coordinates of length and breadth (the other two axes).
With this information, and given a suitable
program in the computer, the computer will then issue
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commands to the apparatus 10.
By movement of -the motors 34 and 46, arms 30 and
~4 will be mo~ed to the approPriate coordinates at which
to commence extrusion. The doctor blads 56 will be. moved
to the appropriate height, and the extruder head 50 will
commence ex-trusion of a thin upright section of settable
material. The material will be extruded with its base
directly onto surface 24. The motor 34 will then move arm
30 along surEace 24 a predetermined distance, during which
the doctor blade 56 will be moved to the appropriake
height by cylinder 53 in accordance with instructions from
the computer.
The blade or gate 56 will also be tilted about
its longitudinal axis, so as to optimize the angle of
slope on the upper surface of -the extruded s-trip, in the
manner described above.
There will thus be extruded a thin continuous
section of settable material, the upper surface of which
has the topology of the article to be reproduced, along
that particular coordinate.
During this first pass, the air ~ets may be off
so as to avoid deflecting the first section. In some
cases it may be desirable, however, to erect a
perpendicular flat wall panel (not shown) on surface 24.
The first section would then be extruded, and deflec-ted
onto such wall panel, for temporary support.
Arm 30 then reverses in order to commence
extrusion of the next section.
In each case, after the completion of one
traverse moment of arm 30, arm 44 will of course have to
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be sornewhat retracted away from the body B by operation of
motor 46, so that arm 30 can re.turn to the start position
for extrusion of the next section.
In fact, arm 44 will have to be retracted in
most cases a distance somewhat grea-ter than the thickness
of the material to be extruded, and once it is at the
start position, arm 44 will then have to be extended until
the extruder head 50 is just in contact wi-th the
previously extruded section.
It will thus be .seen that by the progresive
extrusion of successive thin vertical sections of
material, a body B can be built up which has a 1at under
surface, and has an upper topology which is a reproduction
of -the topology information in the computer.
It will of course be appreciated that the
informa-tion to the apparatus 10 could be developed in ways
other than inputing the inormation into a computer.
; For example, i-t will be possible to set up in a
jig an existing article having ~ desired topology, and
then simply have a copier head traversing along successive
axes o that article. Information thus developed could be
passed directl~ to the apparatus 10 for reproduction.
In practice, however, it i5 believed that the
information would be first of all be inpu-tted into the
computer for processing in-to suitable form for use in the
apparatus 10.
In a great majority of cases however it will be
possible to program the computer directly from drawings of
an article, and withou-t having first o all to make the
article itself.
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In this way, the -topology and profile of a
variety of different products may readily he developed'by
machine directly from working drawings, without the
necessity of making models.
I-t will also of course be appreciated that the
body B is particularly suitable for use as a foundry
pattern.
Conceivably it can also be used to make a metal
working die.
In the majority of cases, some form of surface
finishing steps will be re~uired. These may include
either grindin~ down any ridges on the surface, which may
be left by the ex-trusion of successive vertical sections
of material.
In other cases, i-t may consist simply of filling
the surface with a suitable filler and polishing i-t. In
order to provide a metal-working die or at least a surface
having a longer life, it may be desirable to apply some
form o metal or me-talized coating layer.
Various moldable and settable materials may be
used. Synthetic plastic materials o this -type are well
known. Natural products such as clay may also be
suitahle. Some metal compounds and alloys could also be
used in some cases.
A further embodiment of -the invention is
illustrated in Figures 3, 4 and 5. In this form of the
invention, the settable compound is extruded in the form
of a thin band or tape. The extruded band of material has
a predetermined thickness representing a predetermined
he,ight of the body to be -formed. Successive bands or
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tapes are extruded and laid one upon the other, with the
path on which the band is extruded, being varied slightly
from one band to the next. In effect, each band or tape
which i.s extruded will represent a common height of the
body above the surface of the base plate, somewhat in the
same way as contour lines on a map represent areas of
common above sea level.
Referring first of all to Figure 3, the
apparatus bv which this procedure is carried out comprises
an. extrusion head indicated generally as 100 replaces the
extruder arm 44 and head 50 of the embodiment o Figure 1.
The extruslon head 100 is mounted on the support arm 38,
arlcl may be moved to and fro along the support ar~ 38 by
means of the screw 48, in -the same way as screw 48 moved
the extruder arm 44.
The extrusion head 100 comprises an extru.sion
duct 102, defining a downwardly open extrusion outlet 104.
The duct 102 is connected to a suitabla flexible hose 105
~or conducting extrudable material to the duc-t 102. The
flexible hose 105 is connected to any suitable source of
extrudable ma-terial such as the container 52 of Figure 1.
The duct 102 is movable upwardly and downwardly
in a vertical plane, on the threaded shat 106. Shaft 106
passes through a bracket assembly 107 connected to arm 42,
and through nut 108 on sleeve 110. A motor 112 mounted on
br~cket assembly 107 drives sleeve 110 and nut 108. A
positional feed back indicator 114 is also connected to
the shaft 106, providin@ a readout of the position of the
duct 102.
The outlet 104 of the duct 102 defines a
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predetermined heigh-t, which if desired may be made
~djustable.
One side edge of the duc-t 102 indicat;ed as 116
is pivotally mounted, and is provided wi-th an operating
means such as a motor 117 connected by -threaded shaft 118,
and the threaded sleeve 119, fastened to connecting rod
lZ0 A positional readout 122 is also provided for
indicating the angular posi-tion of side edge 116.
The lower end of shaft 106 is mount,ed in a
rotary bushing 124 on duct 102 so as to permi-t rotation of
duct 102 in a horizontal plane. A gear wheel 126 is
attached to shaft 106 by a sleeve 128 around bushing 124.
A worm gear 130 i5 mounted on duct 102. Gea~ 130 is
driven by motor 132 and monitored by feedback 134.
The operation of -this form of the invention is
best illustlated with relation to Figures 4 and 5. A
first tape or band Bl of the material is extruded directly
on to the base 22. The band Bl will have the same height
all along its length, and will define a regular width
which will typically not vary along its length. The path
along which -the band is extruded is varied by means of
moving the extrusion head 100 along two polar coordinates
simultaneously. This is achieved by s.imultaneously
~;~ operating the motor 46, to drive -the screw 48, and also
the motor 34 to dri~e the arm 30.
As -the head 100 moves around i-ts path or track,
the open end of the opening 104 of duct 102 must face
rearwardly at all times 50 as to feed the band of ma-terial
smoothly.
This is achieved by motor 132, which is operated
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to rotate duct 102 and maintain it i71 -the correct
orienta-tion.
Conceivably~ where the successive bands are all
laid out along straight lines, on a common axis, then
rotation of the extrusion duct would not be required.
However, it is believed that this would be of limited
application in practice.
As an alternative to rotating the duct 102, it
would be possible to mount the platen 22 on a rotatable
mount, and rotate the platen 22 progressively. Such
rotation means are not illustrated herein, for the sake of
clari.ty. Rotatable platforms or mounts are well known in
the machine tool industry and require no special
description.
In this way, by moving both the arm and the
extrusion head simultaneously, with respect to the two
polar coordinates, the strip or band can be laid out along
any desired path.
After the extrusion head has moved on a first
complete path and laid a continuous strip or band, the
extrusion head is then moved upwardly in a predetermined
indexing movement by a distance equal to the thickness of
the band. Thi;s is achieved by means of the motor 112.
Motor 132 is then operated in the reverse
direction so as to ro-tate duct 102 back to its original
position.
The extrusion head is then again moved around a
continuous path, in the same manner as before and deposits
band B2. However, assuming the body is of a simple shape
where the body tapers inwardly as its height increases,
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then the path or trac.k around which the second band B2 is
laid will be of~se-t inwardly with repect to the -first
band.
These steps will be repeated (eg. band B3) until
the top o~ the body i 5 formed.
Obviously, bodies of much more intricate shape
can be formed by this method.
In addition, it is possible to shape the profile
of the outside edge of the strip or band as indicated at X
and V, by tilting the movable wall 116 of the extrusion
duct lrJ2.
In this way it is possible to provide for a
smooth convex or concave curvature (Figure 5).
It will of course be apparent that the finished
body in this case will be a hollow structure.
If desired, wherl it has been ~ormed and set, 1;he
body can slmply be turned upside down and filled with
another se-ttable compound, i~ a solid body is required.
On the other hand, if all that is required is a
topographical model~ then this step may not be nece.ssary.
In any event however it will be appreciated that
this system has certain advantages over the system
described in relation to Figures 1, 2 and 6.
In the body illustrated generally in Figure 1,
in which the successsive strips of material all are formed
with their lower edges ~lat on the base, the s-trips of
material would vary in height quite substantially.
Some settable materials may exhibit a certain
degree o~ shrinkage upon setting. In this case, the
degree of shrinkage will depend upon the height of the
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strip, so that a greater degree of shrinkage will occur
and strips of greater height.
It is of course possible that in this case a
compu-ter program could bs written which would
automatically compensate for the degree of shrinkage.
However, by the practice of the method shown in
Figures 3, 4 and 5, it will be apprciated that the
shrinkage problem is very largely eliminated altogether,
since each strip or band is of the same width and the same
height.
Thus only one degree of shrinkage need be
programmed in-to the computer in this case.
The foregoing is a description of a preferred
embodiment of the invention which is given here by way of
example only. The inve,ntion is not to be taken as limited
to any of the specific features as described, but
comprehends all such variations thereof as come within the
scope of the appended claims.
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