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Патент USA US2404314

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July 16, 1946.
H. G. ROGERS
2,404,314‘
MOLDING APPARATUS
Filed May 25, 1943
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éfgwrdz. ‘
ATTORNEY
Patented July 16, 1946
2,404,314 ‘
UNITED "STATES PATENT mace *
:MOLDING APPARATUS '
Howard‘ G. Rogersiwellesley"Hills;Mass.,.assi'gnor
‘ to ’ Polaroid " Corporation, ‘ ‘Cambridge, \“Mass'., "a
"corp oration 'o‘fsDe'laware
.Appli‘catiomMay 25, 1943,.- Serial. No. 1488;375 ‘
:5 Claims. , (01.“18-39)‘
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" .l'lfhisg-inyention. relates tot-apparatus 'formold
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in .one of the . members. is movably . mounted and
.ing accurately surfacedand/or shaped members,
is permitted tomove. freely during the hardening
vof .the tmoldable .material to compensate for the
such as optical elements, from organic plastics
andresins.
shrinkage.’ :Accordlng .to the present invention
One objectof thepresent invention isto pro
videa novel mold apparatusfor accurately form
ing optical elements,such as optical lenses, from
include means .for accurately pre-setting-the
.moldable materials Which'are subject to an vap
Referring to Fig. 1,, there viseshowna base mem
novel. mold means of this-type areiprovided which
initial position of- the mold parts.
.preciable shrinkage during hardening.
‘
her» “having a central recess ll vand a pair .of
.Another object .of the invention is tov provide a 10 longitudinally extending ‘parallel grooves 12
mold-apparatus of the above character which‘ is
opening into .said recess, .said‘recess and said
particularly adapted for forming optical ele
grooves being ~>adapted to receive and guide a
ments .from plastics such as styrene, :cyclohexyl
pair of-mold supports l3 .and H in longitudinal
methacrylate, or methyl .methacrylate.
A .‘further object is to provide molding appa
movement. .The latter- are .slidably- supported by
15 the bottom wall "of said recess and (are provided
laws‘ of the abovetype wherein thereisembodied
withsu-itable ?anges whicharein dove-tailre
lation-with said grooves, thereby constraining
means vfor accurately adjusting the .moldparts
prior to the introductiontherein of the moldable
said supports to the :desired .movement.
.For
adjusting .the relative-position of support .13, a
Still another object isto providerapparatus for .20 screw member l5, whichhas one end journalled
molding rigid elements havingahigh degree :of
.for free .rotationxin said support and is ?xed
accuracy . and surface smoothness.‘ from; polymer~
against "axial movement relative thereto, ‘is
izable materials, said apparatus [embodying .a
threaded into-a bracket 16 whichrzis “rigidly se
novel means for operatively assembling the mold
zcured to-memberlll.
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parts.
. .25
To accurately predetermine' the. longitudinal or
The above and other objectsand novel fea
zaxi-al separation of support H relative-‘to support
tures of this invent-ion will more .fully appear
13 after .thelatter :‘has been ?xed, a rod 18 is
from :the following a detailed description ?- whenv the
axially ?xed atone end in "support 14 for .free
same .isread in connection with the-accompany
rotary movement. The other end of said ‘rod
.30
ing drawing. It is to be expressly understood,
constitutes .or is secured to the »-axially. movable
however, that the drawing .is for ith'epurposes
element j. of. a - micrometer . t9, or other devicefor
material.
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of illustration only and is ‘not .intendedsas a
accurately measuring the - linear displacement of v
de?nition .of the limits-of itheinvtentionprefer
.encelbeing primarily had for this latter, purpose
‘ Supports-l 3 and i-M'arejprovided with V-shaped
grooves: 2?-.;and-.-2 I,.respectiv.e1y, which ‘are adapt
~ to the appended claims.
In the . drawing, (wherein like reference .char
:ed , to slidably mount a ipairaof cylindrical mold
acters refer to like parts ‘throughout the several
views:
’
members, ~22 and 23 .respectively, the latter-be
ing coaxially ‘aligned by said ll-grooves. ‘ Each'of
.
, ‘Figure 1 is a perspective view of one typeoi
members 22 and 23.5lSrS11fflCl8I1tlY long to provide
apparatus embodying the invention;
4.0 =argood bearing .surface'ior engagement with the
Fig. 2 is a sectional View with'parts'broken
walls of said grooves. Adjoining ends or‘f-aces
away illustrating the method of assembling the
mold prior to the introduction therein of :the
moldable material; and
.z-zaand 23a of said members-serve to de?ne the
light-transmitting surfaces of the optical ele
ment being cast >which,lin1the present embodi
Fig. 3 is a perspective view ofa .deviceziorv ' ment,» is a double concavelens.
voperatively mounting the moldparts :during the
.molding.
I
For the purpose.ofi?xingemem-bers 22 and 13
:relative to supports 20 ‘and .ZI rrespectively, each
of 2 saidwsupports is .provided- with .a *suitab'l'eihold
.ing .mechani'sm comprising a rod 24, fixedly
.
The formation of accurate :e1ements,-:such..as
lenses, from organic resins and plastics has re
.quired' the provision vof 'methods vand apparatus
.50 mountedon tsaidrsupport and operatively engaged ‘
whereby suitable compensation .-is_ made . for .j-the
shrinkage which takes place when polymeriza- ‘ '
tion of a plastic is advanced through theihard
ening stage. It hasbeen .proposed to provide .a
‘mold comprising .a plurality of .memberswhere
.55
.byr an»_arm=2:5 whichhassthe rreerendthereofsup
'porting‘a' screw clamp =26. Arm 25-‘is adapted-to
be in locking engagement ‘Wlllh‘lfOd :24 when’held
inclined thereto. Accordingly, when clamp126 is
axially displaced, 1'.‘ ;e., when screwed into: locking
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arm 25 is simultaneously inclined into locking en
gagement with rod 24. The release of clamp 26 _
releases said arm for‘movement relative to said
rod.
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be used to predetermine theseparation between
the mold surfaces instead of, ‘or in conjunction
with, micrometer I9, particularly when a product
engagement with the mold member held thereby,
having at least one convex surface is to be mold
ed. In the latter event, it is desirable to use a
?at gauge which can be withdrawn edgewise from
'
In operation, support I3 is adjusted by screw l5
between. the, mold surfaces after the separation
to a suitable centralpositionrelative to member
10. Mold .22 is rigidly?xed in groove 20 of ‘said
of ‘the’ mold ‘memberssis properly adjusted. It
is also to be understood that the separation of_
support by clamp 26 so that a marginal portion
of said element extends beyond the face of said‘
support (Fig. 2). ‘Thereafter support M with
10,, surfaces 22a and 23a,may be effected ,by employ
ing a suitable jig, said jig having stops which
.bear' against the ends of the mold members to
element 23 clamped therein in a similar-'manner
is moved in the direction of support l3 until sur
determine their separated positions.
‘There is thus provided a novel apparatus em_
face 231; is in contact with surface 22a. , ‘Element, ‘
,15. bodyingnovel vmeans for positioning and adjust
23 is then separated by micrometer ' l9. from ele
ment 22 by a distance equal to the desired thick, 1 ing mold parts so that the latter can be readily
ness of .the molded product ‘plus, the necessary 7 and accurately assembled in operative relation
allowance for shrinkage during molding. _ This; to eachother. The apparatus comprises means
for slidably supporting the mold members, said
separation can be accurately measured by said
micrometer.
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V.
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20
For con?ning'the 'moldable' material between
surfaces 22a‘ and 23a, a sheetjof vdeformable ma
terial 21,‘such as polyvinyl alcohol, is wrapped
around the marginal portions of said mold mem
bers and is secured thereto. It has been found
means being in turn slidablyand adjustably sup
ported so that accurate adjustment of the mold
members can be readily effected before the latter
are freed for movement during hardening.“ .
2 Although only a single embodimentof the in‘
25
'to be satisfactory to adhesively secure sheetIZ‘l
vention has been illustrated and‘ described, iifiis
to be expressly understood that the same is not
by coating the mold surfaces to be engaged there
by’ with‘ a dilute polyvinyl alcohol solution prior
to the? application of said sheet. In order to obvi:
limited‘ thereto. 7
of sheet 21, it is desirable to overlap the edge
portion of said sheet with a suitable adhesive tape
28, such as Scotch tape. In order to provide for
the admission of moldablematerial into the mold
illustrated for holdingthe mold membersinrthe
7 that a suitable gauge may be pivotally mounted
example, ‘by cutting away a part of pellicle 27.
bers. Moreover, Support I3 may be rigidly ‘se
cured to base member Ill'instead of being slidably
For example, it will nowbe ap
parent to ‘those skilled. in the art that other
- clamping devices of a conventional nature may
ate any leakage due to the wrinkling of the edges 30 be employed in lieu of the clamping'arrangement
supports therefor. It is also to be understood
on base I0 50 that it can be pivoted into an opera’
‘ chamber thus formed, a recess 29'is provided, for 35 tive position to ?x the positions of themold menu?
Clamps 26 are then released to free ‘mold ele
ments 22 and 23' and the latter together with dia
phragm 2'i4a're removed asa ‘unit to amernber 3,0 I
v(Fig.3) and'posit'ionedin a :V-shaped groove'3l
in said member, care being taken not to change
r-thejaxial separation or the co-axial relation ‘be
tween said elements. ‘This’removal can be satis
mounted relative thereto.
.
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,
Sincecertain changes in the constructions;set
forth which embody the invention may be 'made'
without departing from its'scope, it is intended
that all matter contained in the above descrip
tion, or shown in the accompanying drawing,
shall beinterpreted as illustrative and not in a
factorily accomplished manually if both 'm'old,
‘member's arev gripped and raised together. Pelli 45 limiting
‘It is also
sense.
to be understood
7 »
that the .following
'
vole 2'! with tape 28 provide a su?iciently rigid
,connection between the mold'memb‘ers to make
possible the transfer without unusual precau
tions‘.
Y.
QThe’mold ‘chambejr'or cavity 'de?nedby sur
faces 22a and 23a and sheet'ZT is thereafter'?lled
' with the moldable material, as for example, a
_ ‘claims are intended to cover all of the generic
and speci?c features of the invention herein de
scribed, and all statements of the scope of the
50 invention which, as a matter of language, might
be said tofall therebetween.
What is'claimed is:
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a
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partially polymerized solution of styrene orcyclo
1. In apparatus of the character described, a
‘plurality of cylindrical mold elements, a plurality
thereof may then'be subjected to heat in order 55 of supports having grooves for receiving said mold
elements and maintaining the latter in coaxial
to advance the polymerization of -' the moldable
< hexyl'methacrylate. ~ The mold'and the contents
solution contained therein and‘as the solution
alignment, said mold elements being free for slid- .
hardens and shrinks, elements" 22 ‘and 23 “are
ing movement relativevto said supports and for
drawn together'by the adhesion between {surfaces
ready removal as a unit from said supports,'hold
22a and 23a‘ and the hardened product, thereby
compensating for the shrinkage and obviating the
undesirable effects thereof. Because of the ac
' ing means carried by each of said supports for
curate separation of ‘mold surfaces 22av and ‘23a
sliding coaxial movement relative to one another,
which includes an allowance for the shrinkage,
and means comprising a micrometer mechani
65 cally associated with said last named mounting
the length of the molded product along its opti
cal; axis is accurately predetermined.
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;,The ‘above molding operation may be carried
out with mold members 22 and 23 freely mounted ~
for vslidable movement in‘ grooves 20' and 2l,;re'—
releasably securing the mold elements to said-sup
ports, means, for mounting 1 said supports‘for ‘
means and one of said supports‘for adjusting'_jand
measuring accurately the separation betweenlthe '
faces'of the mold elements carried by‘ saidls'np_
ports.
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spectively. However, it'is preferable to use‘the 70 2. In a device of the character described, aplif
rality' of mold elements, a plurality of supports
pre-setting mechanism I0, I73, I4 only for opera
providing a plurality of aligned grooves the ad'
tively assembling the moldparts and -to carry
outlthe actual molding in the more'simple mem
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~berf30.
' “It is toV be
I understood
I’ ' that
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‘ a suitable
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gauge may
jacent ends of which are open and adaptedito
receive and slidably mount said’ mold’ elements,
75 the side walls of said grooves maintaining‘the
2,404,314
5
6
a
to receive and slidably mount one of said ele
mold elements in coaxial alignment, means op
ments, the walls of said grooves maintaining said
erative to releasably secure said mold elements
to said supports, said securing means ‘comprising
mold elements in coaxial alignment, means oper
ative to releasably secure said mold elements to
mold-holding elements adjacent the open ends of
each groove for holding said mold elements in Cl said supports, said securing means comprising a
pivoted mold-holding element adjacent the open.
operative engagement with said groove walls and
ends of each groove and holding each said mold
against axial movement within said grooves, said
mold-holding elements being movable to inopera
element against axial movement within said
grooves, said mold-holding elements being piv
tive position to permit removal of said mold ele
ments as a unit from said supports, means for 10 oted to inoperative position to permit removal of
said mold elements as a unit from said supports,
mounting said supports for coaxial movement
relative to each other, and means cooperating
means for slidably mounting both of said sup
with said last-named mounting means and said
ports for coaxial movement relative to one an
supports for adjusting accurately the separation
other, and means cooperating with said last
named mounting means and said supports for,
between the faces‘of the mold elements carried
by said supports.
3. In a device of the character described, a plu
adjusting accurately the separation between the
faces of the mold elements carried by saidsup
rality of mold elements, a plurality of supports
providing a plurality of aligned grooves the ad
5. In a device of the character described, a
plurality of mold elements, a plurality of sup
jacent ends of which are open and adapted to
ports providing a plurality of aligned grooves the
receive and slidably mount said mold elements,
adjacent ends of which are open and adapted to
the walls of said grooves maintaining the mold
elements in coaxial alignment, means operative
receive and. slidably mount said mold elements,
the walls of said grooves maintaining the mold
to releasably secure said mold elements to said
supports, said securing means comprising mold 25 elements in coaxial alignment, means carried by
said supports and operative to releasably secure
holding elements adjacent the open ends of each
of said grooves for holding said mold elements in
said mold elements to said supports, said secur
ing means comprising a pivoted mold-holding ele
operative engagement with said groove walls and
ment adjacent the open ends of each groove 'for
against axial movement within said grooves, said
holding said mold elements against axial move
mold-holding elements being movable to inop
ment within said grooves, said mold-holding ele
erative position to permit removal of said mold
ments being pivoted to inoperative position to
elements from said support, means for mounting
permit removal of said mold elements as a unit
said supports for coaxial movement relative to
from said supports, means for mounting said sup-v
one another, and means comprising a microm
eter mechanically associated with said supports
ports for coaxial movement relative to one an
for adjustingaccurately the separation between
other, and means cooperating with said last
named mounting means and said supports for
the faces of the mold elements carried by said
adjustingv accurately the separation between the
supports.
faces of the mold elements carried by said sup
‘ 4. In a device of the character described, apair
ports.
.
of mold elements, a pair of supports each pro
v
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HOWARD GJROGERS.
viding a groove, said grooves being aligned andv
“having the adjacent ends thereof open and adapted
ports.
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