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Патент USA US3046612

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July 31, 1962
3,046,600
E. F. LINHORST
MOLDING METHOD AND APPARATUS
Filed May 15, 1961
2 Sheets-Sheet 1
INVENTOR
Erwin F. Linhorsi
8Y9
ATTOR EY
July 31, 1962
E. F. L'INHORST
3,046,600 '
MOLDING METHOD AND APPARATUS
Filed May 15, 1961
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i United States Patent?
3,046,600. '
Patented July 31, 196,2.
.2
new and improved method of and apparatus for molding
3,046,600
,
MOLDING METHOD' ‘AND APPARATUS
Erwin F."Linh0rst, Paterson, NJ., assignor. to United
States Rubber Company, New York, N.Y., a corpora
tion at New- Iersey
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'
UK
a new and improved’ method of and apparatus ‘for ‘more;
ing rubber and rubber-like articles that can be relatively
Filed May 15, 1961, Ser. No. 109,965 a
14'Clai1nsL‘
(,Cl.“18,-,'-—5)
‘
rubber and rubber-like‘articles wherein the ?ash ‘pro-E
duced
mum, toduring
thereby
the‘keep
niOlding.
the production
operation costs
-is held
relativelylow.
to a
Another object of this invention‘ is the provision of
i
easily mechanized or automated.
This invention relates generally to a method of and
apparatus’ tfoij'molding rubber, and rubber-like articles.
‘Molding operations, presently carried out by known
molding'i’inethods and apparatus, ‘are generally beset by
a number of di?iculties which result in relatively large
wastes‘ of material'and eifo'rt. These difficulties occur
to ‘a ‘greater or lesser'degr'ee in such common molding
10
channel, compressing the compound against the‘ mold’
ofrnor’e-than one of the ‘foregoing, such as, for example,
within the con?ned portion of ‘the channel so that the,
'
cmnpoundv ?ows. into the cavities of ‘the mold and the
Molding scrap" losses in both the bottomless cylinder
type of molding and the compression type 'of molding
aie of particular concern "to the molde‘r‘in' that they
represent‘ an appreciable percentage of the cost of the
?nished article. In the former case, an injection piston
or plunger engages a mass of molding compound which is
excess compound forms a layer. adjacent to the mold,
thereafter providing communication between the excess‘
compound layer and the space surrounding tha channel,
to allow the excess compound tobe squeezed out‘of the,
channel, and then curing the compound in the mold cavi
ties.
located ‘in Q'substantially bottomless cylindrical cavity
injection piston in conventional bottomless cylinder mold
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~
'
v
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An apparatus in accordance with one embodiment of
so as to force the compound against the sprite plate of a
the moldf:A_lthtiugh a large amount of this molding
compound actuallyenters the cavities to form the molded
article, there always remains a sheet or pad of the com
pound ‘between the piston and’ the sprue plate at the end
of the injection stroke. Inasmuch 'as'the cylinder and
become apparent as' the following description proceeds,
. Brie?y stated, and. in accordance with one embodiment,
operations as compression‘ molding, transfer molding, in
mold, through the sprue openings, and into’the cavities of
'
of this invention, the method of this’invention is pracr
ticed by placing a cavity containing mold in a channel.
having at least a portion thereof con?ned, adding a pre-,
determined amount of. molding compound adjacent a,
surface of the mold within the ‘con?ned portion of the’
jection molding, and molding'operations having ‘aspects
“the bottomlesscylinder” type of molding.
'
. ‘Further objects and advantages of this, invention will
this invention comprises a frame, a structure, forming av
channel. carried by the frame and adaptedto receive at an
inlet'ther'eof a‘ plurality of mold, members which form a
30 column within the channel, means forv adding ‘uncured.
molding compound between at least two adjacent mold
. mémbeifs 'Withi'n' the channel, meansito comrtessthe Q01:
mm; of molds! and. means‘ "to. €°i1?P¢ Within. at least. a
pontion of said channel thetwo adjacent mold, members
ing operations cannot be retracted from the mold with 35
the compound therebetween
compression of _
out permitting the molding compound to new out of
the: column while at‘leasta'portion of the remainder of
the mold cavities, because it may result in “dimpling”
the channel remains uncon?ned so that ‘the compound
at'the‘ sprue openings and objectionable ?ash at the mold
flows into the’ cavity of'at'leastione of the'itvvo ialdjaiceint'
plate parting lines, the aforesaid pad of molding com
mold members while thev excess uncured adamant“ in
pound'is usually cured with the injected portion of the
compound. and represents a- complete waste.
40
Similarly, in compression molding, there is also pres
larly "pointing "out and distinctly claiming the subject
ent an inherently‘ high ratio‘ of waste. scrap to utilized
compound. “In this~ cas_e,'the, cavities of an open mold
are eachv generally individually pre-loaded with “biscuits” 45
of compound, each biscuit being in excess of the amount
required, to, ?ll its associated cavity to insure that the
cavities will be completely ?lled. when, the, mold is closed
FIG, 1 is a side elevatioual view of a channel typev
waste'?ashwhen the mold is closed and compressed, and
2-—-2 of FIG. 1;
..
..
.
.
.
.
.
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tion. Although the selectedaptparatus has been illustrated,
as'being positioned at’ an inclined angle to the horiiontal, .
60
..
vision'jofa new and improved- method, and apparatus
for substantially decreasingv molding scrap losses in the
‘
vision ofv anew and improvedme'thod of and, apparatus
for 'moldin'grubbe'r andrrubber-lilge articlesinjwhich ex
cesfs, mating compound’, which wculdgnoml‘ally be. cured
" '
‘
A related object. of this inventioniis the provision of a
by ‘making slight modi?cations to the illustrated embodn
merit, For purposes of description, the apparatus Will be
considered as one employed in‘ the manufacture of-bottle
' ‘ 65
along with ‘the compound“ in the: cavities‘of a- mold. is
it may equally Well be horizontally‘ or vertically disposed? ‘_
stoppers, however, numerous other articles may 'bemade ‘
‘A further object. of, ‘the present invention. is the pro
reindved more wine
"
4-4 of FIG. 1.
Referring to the drawings, there has been illustrated‘ a
preferred apparatus for putting thisinventionyinto opera- ‘
Another object of the present. invention is the pro
moldingpof rubber and. rubber-like ‘articles.
i
line 34-3 of FIG. 2; and,
FIG. 4‘ is a sectional end elevation taken along the line -
‘Accordingly, therefore,’ an important object at the pres-p
..
i
FIG. 3 is a'sect‘ional elevational view taken ‘along the
in the cavities. The compression molding operation re
sults not only in laige scrap losses but in time and labor
losses necessitated by the pre-loading of'the cavities and
the trimming of. cured-flash ‘from’ the ?nished article.v
..
description taken in connection with ltheaccompanying
molding apparatus embodying features of, this invention;
vFIG. 2 is a sectional plan view taken, along the line
this stock is cured along with the molding compound
ap?arait?s;
matter regarded as this’invention, it'isvbeliieved'that the
invention‘ will be better‘ understood from the following
drawings in which; '
andput,undercompression. As a result, a large amount
of excess molding compound ?ows out of the cavities as
ent inventionl'isto provide a new and improved molding
mathod, and‘ apparatus. which, is free of. the drawbacks
anddis'advantagesof many. presently used. methods and
the portion’of the'remainder of the"channel‘flows~ out.
of the channel toybe recovered.
‘While the speci?cation concludes with claims particu:
by employing molds with suitably designed cavities.
The molding apparatus comprises. a base ortrame 1
having an inclined supporting. surface}. and?rst and;
secondspaced vertical supportlegsS» and 4, respectively.
A channel forming vstructure, shown generally at 5, is,s.ui,t_~, .
70
ably supported between the‘spaced vertical‘ support» legs,
3 and 4, astiavrednrqcalmeansl Shawn seasrallyat?.
and carried by the inclined supporting?snrfface; 2, co,
8,046,600
3
4
operates with one end of the channel forming structure
steel block 42. The gap 45 allows for a limited amount
5 during operation of the molding apparatus.
of longitudinal movement of the entire channel forming
Reciprocal means 6 comprises a power cylinder 7 having
a piston 8 movable therein. A pressurized ?uid pumped
from a source (not shown) is led to either end of the
facilitate removal of the mold plates from the channel.
As previously indicated, the channel type molding of
cylinder 7 through a conduit 9, stop valve 14}, four-Way
reversing valve '11, and either one or the other of con
duits 12 and 13. A return line 13a connects the inactive
side of the cylinder 7 back to the ?uid source. Reciprocal
structure 5 between the vertical support legs 3 and 4 to
this invention has been illustrated in an embodiment suit
able for making bottle stoppers. In this connection a plu
rality of two-plate molds are employed, the exact number
required being dependent on the size of the article being
means 6 also includes a piston rod ‘14 having one end 10 made, the thickness of the mold plates, and the length of
rigidly connected to the piston 8 and its other end movably
mounted within the channel forming structure 5.
A heated enclosure, shown generally at 15, is provided
about a portion of the longitudinally extending channel
structure 5. The heated enclosure 15 comprises ?rst and
second sidewalls 16 and 17, respectively (FIG. 4), a top
wall 18, and a bottom wall 19. Conventional electrical
heating elements 20 and 21 are supported by the side
the channel. In the example shown, eleven molds, com
prising a total of twenty~two mold members or plates, are
employed in the molding operation. Each mold includes
an imperforate mold member or plate 46a through 46k,
and a perforate four cavity mold member or plate 4711
through 47k.
.
Inlet portion 22 of the channel forming structure is
provided with an aperture 48 through the sidewall 35
thereof through which the various mold plates 46a—k and
walls 16 and 17, respectively, and extend therealong for
curing the molding compound as it progresses through the 20 47a-k may be introduced into the con?ned portion of the
channel. Similarly, the opposite sidewall 36 of the inlet
channel forming structure 5, within the heated enclosure
portion 22 is also provided with an aperture 49, upstream
15.
The longitudinally extending channel forming structure
of the aperture 48, through which molding compound 50
may be introduced into the con?ned inlet portion of the
5 may be conveniently broken down into three sections
for purposes of description. The structure comprises a N) 01 channel ‘between various of the mold plates therein. The
inlet portion 22 of the channel forming structure 5 is also
con?ned inlet portion 22, an uncon?ned curing portion 23,
provided with a third aperture 51 (FIG. 3), in the bottom
and a con?ned outlet portion 24. The inlet portion 22
wall 38 thereof, through which excess uncured molding
of the channel forming structure is connected with the
compound to be removed from the channel may pass in a
outlet portion 24 thereof by means of a plurality of longi
tudinally extending angle members 25, 26, 27 and 28 (see
30 manner to be described.
30, a top wall member 31 and a bottom wall member 32.
Provision is made in the con?ned outlet portion 24 of
the channel forming structure 5 for removing the various
mold members or plates from the channel after they have
progressed therethrough. As may be seen in FIG. 2,
The bottom wall 19 (FIG. 1) of the heated enclosure
15 is provided with spaced openings 33 and 34 there
the sidewall member 29 includes an aperture 52 which is
of su?icient size for the various mold plates to pass
through. A ?rst receptacle 33a, positioned beneath the
through the wall. Similarly, sidewall member 30 in
cludes an opening 53, in alignment with aperture 52,
through which an operator may project a rod (not shown)
FIG. 4). The angle members 25 through 28 are inter
connected and held in spaced relationship at the outlet por
tion 24 by means of a pair of sidewall members 29 and
opening 33, serves to accumulate uncured molding com
pound that is discharged from the channel forming struc
ture 5 prior to curing. Similarly, a second receptacle 34a, 40 to force the various mold members or plates out of the
positioned under the second opening 34, serves to ac
channel. A parts ejection ?xture, shown generally at 54,
cumulate cured molding compound discharged from the
may be provided adjacent the outlet portion 24 of the
channel forming structure 5 during operation of the mold
molding apparatus to remove the cured articles, in this
ing apparatus.
case the bottle stoppers 55, from the cavity mold plates
Reference may now be had to FIGS. 2 and 3 wherein
47a through 47k.
the details of the inlet and outlet portions of the channel
The curing portion 23 of the channel forming structure
forming structure have been more clearly illustrated. The
5 is generally uncon?ned. In this portion of the structure
con?ned inlet portion 22 of the structure includes ?rst and
the various molds are supported and guided in the channel
second spaced sidewalls 35 and 36, respectively, a top
due to the engagement of rabbets or slots formed in the
wall 37, and a bottom wall 38, all of which are rigidly 50 angle members 25 through 28 (FIG. 4) with the corners
interconnected to each other and to the longitudinally ex
of each mold member or plate. Thus, the heat generated
tending angle members 25 through 28 to form the longi
by the heating elements 20 and 21 within the enclosure
tudinally extending generally square channel or passage
15 may act directly on the molds to facilitate curing of
way through which the bottle stopper mold plates may be
the compound therein as the molds progress through the
passed.
curing portion 23 of the channel.
The inlet portion 22 of the channel forming structure
Assuming that the channel forming structure 5 has
5 is slidably supported for limited longitudinal movement
been previously loaded with the various mold plates 47a
by the vertical support leg 3 in a recess 39 formed for
through 47j and 4611 through 46k, and that the apparatus
that purpose. The piston rod 14 extends through an
is in the condition shown in FIGS. 2 and 3, the operator
aperture 40 in the support leg 3 and carries a plunger 41 60 ?rst inserts a push rod through opening 53 to force im
at the end thereof. The plunger 41 slidably and fric
perforate mold plate 46k out of the channel, and then he
tionally engages the inlet end of the channel forming
actuates the reversing valve 11 of reciprocal means 6
structure 5 during its forward and return strokes and abuts
(FIG. 1) to cause plunger 41 to commence a compression
hooks 41a near the end of its return stroke for purposes
stroke and start extending forwardly into the channel.
which will become more apparent hereinafter.
During the initial portion of the compression stroke
The outlet portion 24 of the channel forming structure
or forward movement of the plunger 41, cavity mold plate
5 is also slidably supported for limited longitudinal move
47a is pushed to the right, and friction between the
ment on a steel block 42 which enters the interior of the
plunger 41, mold plate 47a and the inner peripheral sur—
channel forming structure 5. Block 42 is in turn sup
face of the channel forming structure 5 causes the entire
ported by the vertical support leg 4, with a steel plate 43
structure 5 to shift to the right until the upstream end face
and an insulating plate 44 being provided to separate the
24a of the outlet portion 24 abuts the shoulder 42a on
steel block 42 from the support leg 4 to which it is bolted.
steel block 42, thereby closing the gap 45. As the for~
The spacing between the vertical support legs 3 and 4 is
ward movement of plunger 41 continues, cavity plate 47a
such that a gap 45 is provided between the end face 24a
comes into abutment with imperforate mold plate 46b
of the outlet portion 24 and a shoulder 42a formed in the v 75 and then the entire mold column moves to the right with
3,0 cacao
7
here downstream of said inlet is uncon?ned; and means
to compress said column to cause the compound adjacent
the inlet to ?ow into the cavities of an adjacent mold
member and the compound downstream of the inlet to
?ow out of the channel.
5. Molding apparatus, comprising: a frame; a longi
O
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0
heating means adjacent the curing portion of said channel
for curing the compound in the mold cavities during move
ment of the molds through said curing portion.
9. A method of molding including the steps of placing
a cavity containing mold having at least one mold mem
her in a con?ning channel, adding a predetermined
amount of molding compound adjacent to a surface of
tudinally extending structure forming a channel having
said mold member within the con?ning channel, com
inlet and outlet openings carried by said frame and
pressing the compound against the mold member within
adapted to receive therein a column of mold members,
certain ones of which are separated by molding com 10 the con?ning channel so that the compound ?ows into and
fills said mold cavities within said channel and excess com
pound, the components of said column being movable
pound forrns a layer adjacent to said mold member, there
through said channel from said inlet to said outlet open
after providing communication between the excess com
ing; means for con?ning molding compound between a
pound layer and the space surrounding the channel to al'
?rst pair of mold members and within said channel adja
low the excess compound to be squeezed out of the chan
cent the inlet opening thereof; means to compress said
nel, and then curing the compound in the mold cavities.
column so that the con?ned compound flows into the
10. A method of molding including the steps of as‘
cavities of at least one mold member of said ?rst pair
sembling a pair of mold members separated by a prede
of mold members, there being at least an uncon?ned
termined amount of molding compound in a con?ning
second pair of mold members in said channel down
channel to form a column, compressing said column while
stream from said ?rst pair of mold members so that dur
the compound is in the con?ning channel so that the com
ing compression of the column excess uncured compound
pound ?ows into and ?lls the cavities of at least one of
?ows out of said channel from between said second pair
the mold members and excess compound remains between
of mold members.
the mold members, thereafter providing communication
6. Molding apparatus as described in claim 5 and
between the excess compound and the space surrounding
further including means to heat at least a portion of said
the channel to allow the excess compound to be squeezed
column for curing the compound in the mold cavities;
out from between the mold members during compression
and means positioned along the channel and adjacent the
of the column, and then curing the compound in the mold
outlet opening thereof for removing from the peripheral
cavities.
surfaces of said molds such cured compound as flows out
11. A method of molding including the steps of as
of the mold cavities due to thermal expansion of the com
sembling a pair of mold members separated by a prede
pound during curing thereof.
termined amount of molding compound in a con?ning
7. Molding apparatus, comprising: a frame; a longi
channel to form a column, compressing said column within
tudinally extending structure forming a channel mounted
the con?ning channel to squeeze part of the compound into
on said frame and adapted to movably carry therein a
the cavities of at least one of the mold members adjacent
plurality of molding compound ?lled molds in the form
thereto while excess compound forms a layer between the
of a column; means to heat said channel for curing the
mold members, moving the mold members along the
compound during movement of the molds therethrough;
cianncl to an uncon?ning portion thereof where the ex
means to insert additional molds and uncured compound
cess compound between the mold members communicates
into said channel; means for moving the additional molds
towards the mold column and compressing the compound 40 with the space surrounding the channel, compressing the
column again to squeeze the excess compound out of the
therebetween so that said compound ?ows into the cavi
channel, and then curing the compound in the mold cavi
ties of an adjacent mold; means for con?ning molding
ties.
compound between molds in one portion of the channel
12. A method of molding including the steps of form
and removing excessive compound from between molds
ing a column of molds in a channel having a portion of
in another portion of the channel while the moving means
its length con?ned from the space surrounding the chan
is actuated and maintains the column under compression;
nel, adding a predetermined amount of molding compound
and means for removing molds from said channel while
to the con?ned portion of the channel, compressing the
said moving means is de-actuated.
compound Within the con?ned portion of the channel and
8. Molding apparatus, comprising: a frame; a longi
tudinally extending structure forming a channel carried 50 against the column to cause a portion of the compound to
?ow into and ?ll the cavities of a mold in the column while
by said frame and having aninlet portion, a curing por
the excess compound forms a layer adjacent to said mold,
tion, and an outlet portion extending therealong, said inlet
moving the components of the column along the channel
and outlet portions each including a plurality of wall
to an uncon?ned portion thereof so that the excess com
members forming enclosures about their respective por
pound layer communicates with the space surrounding the
tions of said channel, said inlet wall members having ?rst,
second, and third openings spaced ?ierealong for, respec
channel, compressing the column to squeeze the excess
tively, inserting molds comprising at least two mold mem
bers into said channel, inserting uncured molding com
pound between predetermined adjacent mold members in
compound layer out of the channel, and curing the com
pound in the ‘mold cavities along the column.
13. A method of molding including the steps of adding
said channel, and allowing excess uncured compound to
flow out of said channel, said second and third openings
molding compound and molds to one end of a column
of molds in a channel and removing molds from the other
being spaced apart by a distance greater than the depth
end of said column, compressing the added molding com
pound against the column of molds in a con?ning portion
of each of the molds inserted into said channel, said outlet
wall members having a fourth opening for removing
molds from said channel; reciprocal means positioned ad
jacent to said inlet enclosure and movable therein for
moving the molds inserted in said ?rst opening towards
said fourth opening and applying a compressive force to
the entire column of molds in said channel so that the un
of the channel to cause a portion of the added compound
to flow into and ?ll the cavities of an adjacent mold while
the remainder of the added compound is con?ned within
the channel and forms a layer of excess compound adja
cent to said mold, moving the column of molds within
said channel so. that the excess compound layer reaches
cured compound enclosed by a pair of mold members 70 an uncon?ning portion of the channel, again compressing
located between the second and third openings in the inlet
said excess compound to squeeze the excess compound out
portion is squeezed into the cavities of one of said molds
of the channel, and heating the channel to cure the com
and the excess compound between a pair of mold mem
pound in the mold cavities as the molds progress through
bers at the third opening of the inlet enclosure is squeezed
the channel from one end to the other end of said col
out of the channel during compression of the column; and 75 umn.
3,046,600
9
14. A method of molding including the steps of (1)
10
jacent mold plates and within the con?ned portion of the
channel; (10) repeating steps 2 through 9 so that the ex
cess compound layer of step 9'moves into communica4
tion with the uncon?ned portion of said channel and
other portion thereof uncon?ned and heated, at least
one of the plates of each mold including one or more Cit is squeezed out of the channel during the compression of
the column; (11) again repeating, steps 2through 9 a pre
cavitites for receiving and shaping molding compound
determined number of times to advance the mold plate of
to a desired con?guration; (2) removing at least the ?rst
step 9‘ having compound ?lled cavities (a) through the ’
mold plate in said column and adding at least one mold
heated portion of the enclosure to cure said compound,
plate adjacent the last mold plate in said column; (3)
moving said added mold plate into contact with said last 10 and (b) into the position of the ?rst mold plate in said
column; (12) removing said last named mold plate from
mold plate; (4) moving the entire column of mold plates
said channel; and (13) thereafter ejecting and collecting
a distance equal to the depth of the removed mold plate;
the cured articles removed from the cavities of said mold
(5 ) again removing at least the ?rst mold plate in said
forming a column of multi-plate molds in a channel having
at least an inlet portion thereof con?ned and at least an
column and adding at least one mold plate adjacent the
last mold plate in said column; (6) adding a predeter 15
mined amount of molding compound between said added
mold plate and the last mold plate in said column; (7)
moving said added mold plate toward said last mold plate
to thereby form a layer of compound between said added
mold plate and said last, mold ‘plate; (8) moving the en 20
plate.
'
References Cited in the ?le of this patent
UNITED STATES PATENTS
131,626
Noyes et al. _________ __ Sept. 24, 1872
1,548,537
McDonald ____ __' _____ __ Aug. 4, 1925
1,677,200
Oakley _____________ __ July 17, 1928
71,677,207
2,169,281
2,347,600
2,873,475
into the cavities of at least one of its adjacent mold plates 25 2,939,173
and form a layer of excess compound between said ad
2,943,353
Rett ________________ __ July 17, 1928
Pfanstiehl ___________ _._ Aug. 15,1939
Goode _____________ __ Apr. 25, 1944
Linhorst ____________ __ Feb. 17, 1959
Linhorst ______________ _._ June 7, 1960
Fraula et al. __________ __ July 5, 1960
tire column of mold plates and compound a distance equal
to the depth of the mold plate removed in step 5'; (9)
compressing the entire column of mold plates and com
pound to thereby force a portion of the added compound
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