close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2410510

код для вставки
vNov._5, 1946.
N_ LESTER
‘
I
2,410,510
MOLDING THERMOSETTING MATERIAL
Filed July 4, \1942
INVENTOR.
N ATHAN LESTE R
ATTORNEYS
Patented Nov. 5, 1946
2,410,510‘
UNITED ‘STATES PATENT OFFICE
2,410,510
MOLDING THERMOSETTING MATERIAL '
Nathan Lester, Cleveland Heights, Ohio, assignor
to Lester Engineering Company, Cleveland,
Ohio, a corporation of Ohio
Application July 4, 1942, Serial No. 449,758
14 Claims. (Cl. 18-30)
1
2
The present invention relates to the pressure
molding of thermosetting plastic material, 1. e.,
the formation of such material into desired shape
in a molding die cavity by the application of
proper pressures and temperatures thereon.
Thermosetting Or “hot-set” plastic materials un
mittal of a given quantity or charge of the plastic
material in its initially, ?nely divided solid form
from a pressure chamber into the mold proper in
one continuous operation, and wherein the ma
terial is plasticized during its travel from the
such as that of a powdered or granulated mate-g
rial, the second plasticized form wherein the ma? '
terial enters the plastic or sufficiently fluid state
to be caused to ?ow into and‘ completely ?ll the
pressure chamber to the mold cavity, and all of
the so plasticized material is incorporated into
the mold body and removed from the pressure
molding machine at each and every stroke. The
temperature conditions imposed upon the material
to be molded, during its transmittal from the in
itial and solid to the plasticized and ?nally to
the infusible state, are such that if there is any
mold cavity, and thirdly, the permanently solidi
excess material present over and above that nec
?ed or infusible state wherein the material under
latter phase change is usually referred to in the
essary to completely ?ll the mold proper, such
excess will be maintained in its original granular
or powdered form when in the pressure Cylinder
practice as “the cure.” The thermosetting or hot
and will not operate to cause a clogging of the
dergo, during the pressure molding operation,
phase changes involving three different phases or
physical forms, namely: The initial solid form,
goes a chemical change or polymerization, which I
latter.
set molded plastic materials are exempli?ed by the
phenolic and urea resinoid condensation products. 20 Additional objects and advantages of the in
vention shall become apparent as the following
Heretofore the thermosetting plastic materials -'
description proceeds.
have been molded by means of the compression
To the accomplishment of the foregoing and
molding and the transfer molding processes. In
the ?rst, the material is loaded directly into the
related ends, said invention, then, consists of the
mold cavity wherein an initial pressure and heatv .25 means hereinaftenfully described and particu
is applied until plasticization occurs, and then '
larly pointed out in the claims, the annexed draw
ing and the following description setting forth
additional pressure exerted during the curing
in detail certain means and one mode of carrying
stage. In the transfer molding method the ma
terial is plasticized by heat at a point removed,
out the invention, such disclosed means and mode
or outside of the mold body itself, and then as a :30 illustrating, however, but one of various ways in
plastic, it is transferred through an ori?ce into" ' which the principle of the invention may be used.
In said annexed drawing:
'
the mold cavity Where it becomes cured or solidi
?ed. Compression molding has been subject to
Fig. 1 is a sectional view taken through the
the disadvantage of requiring a relatively long
pressure plunger cylinder and die blocks of a
period of time for the performance of the molding.
machine embodying the principle of my inven
cycle, two to ten minutes being necessary for the " tion and‘ adapted to perform the novel process
polymerizing or curing stage alone. The transfer
thereof;
molding method is more rapid, but is subject to
Fig. 2 is an elevational view of Fig. 1 but show
the disadvantage of producing an over-heating
ing the die blocks in open position;
’
or over-curing of the material retained in the 40 ~Fig'. 3 is an enlarged, perspective view of that
plasticizing chamber. Quite frequently, a hard- " part of the die blocks forming the plasticizing
ened and infusible slug will form in the plasticiz
runners or gates of the mold cavity and also the
ing chamber of the transfer molding apparatus,
removable discharge end wall of the pressure
thus interrupting the operation of the process and
7
45 plunger cylinder;
apparatus until such slug can be removed.
Fig. 4 is an enlarged cross sectional view taken
It is therefore the general object and nature
substantially along line ll—4 of Fig. 2; and
of my invention to provide a process and appara
Fig. 5 is an enlarged, perspective view of the
tus for molding thermosetting material wherein
end of the gate or runner slug of the casting, illus
the complete molding operation or cycle can be
performed at a relatively rapid rate and wherein 50 trating the occurrence at that point of both the
cured and the unplasticized molding material.
the pressure chamber is discharged or evacuated
The pressure molding process embodying the
of the entire charge of material at each stroke, so
principle of my invention involves the following
that there is no opportunity for the solidi?cation
detailed steps, wherein those having to do with
or curing of a slug of excess material therein.
Brie?y outlined, my process involves the trans 55 the phase change of the thermosetting plastic
3
4
to the interior of the insert 12 at a point im
tinuous operation:
mediately behind the end Wall 13. This is ac
1. Charging of given quantity of solid, ?nely
complished by means of the concentric Water
divided thermosetting material into the pressure
tubes léi and 55 which terminate at the inner
chamber.
.
5 bore or space it inside the insert 12 and are
2. Evacuating material under pressure from
connected at their outer ends by means of the
material are conducted, in e?ect, as one con
pressure chamber.
3. Maintaining temperature of material, While
in pressure chamber, at below the plasticization
?ttings It and i8, respectively, to ?exible water
line conduits (not shown). Cooling water ducts,
seen at 28 and ill in Fig. 1 are also provided in
point.
1-9 the wall of the pressure cylinder 1 immediately
4. subjecting material in elongated gates or
adjacent its left hand or discharge end. The
runners to a temperature sui?cient to produce
cooling water, or other coolant medium is circu
plasticization thereof (in the case of phenolic
lated through the concentric tubes 14 and I5
thermosetting plastic material, about 350° R). .
and the ducts "2H and 2| at a temperature and
5. subjecting plasticized material in mold cavi
rate sufticient to'maintain the outer surface of
ties to further curing heat and pressure to cure
the Wall 13 and the interior of the pressure cyl
or hot set the material.
inder ‘i at'a'point below that at which plasticiza
6. Opening die blocks and evacuating entire
tion of the material M, under the pressure ap-}
body of material in the form of castings proper,
plied, might occur.
runners and gate slug.
.
An electrical resistant heating coil 22 is mount
20
Steps 2 -toi5 as delineated above are conducted
ed in the insert 52 exteriorly of'the cooling tubes
in ‘what is in practical effect one continuous
ill and 15. The heat produced and generated
operation, ‘wherein the material is transformed
from the heating coil 22' is transmitted through
from its ‘initially solid to its ?nally cured or
the body of the insert I2, and also through the
solidi?ed state in a relatively short period of 25 body of the die block 4, so as to heat the runners
time, i. e., less than one minute. .This is to be
ii.
Such heat in the runners H is maintained
compared to the 2’ to 10 minutes of curing time
at'a temperature (viz. about 350ml“. in the case
alone required in the compression molding meth
of phenolic thermosetting material) su?icient to
produce av plasticization of the ‘material as it
od as heretofore practiced. Furthermore,‘ since
none ‘of the material is subjected to a plasticizing 30 passes‘ therethrough under pressure, and into the
temperature in the pressure chamber, there is
mold cavity portions 19.‘ ‘Additional ‘electrical
heating elementsl23 and 2d ‘are provided in the
. no opportunity for'the'formatio'n of a set slug
'in the'ilatter, as compared to the transfer mold
ing method.
, die blocksii and ii,’ respectivelyfat points adjacent
the mold cavity ‘ portions "it which ‘form the
35 castingsproper. lt‘is‘at this latter 'point‘that
the ‘plasticia‘ed material is‘ subjected to‘ the‘?nal
performance-of the above process, and a detailed
cure or additional 'heat and‘ pressure’ treatment
description of such'apparatus will serve to fur
sumcient itofp'olymer'iz'e‘ and “hot set” the plastic
The apparatus as illustrated in the accom
panyingdraiving is’pa'rticul‘arly designed ‘for the
ther illustrate the practice of such process.
material "to its ?nal‘solidi?ed 'or infusible state.
‘ 71_‘n?§F-igs. -1 and’2 there are shown a pair or 40 . Ejector fpins’fz?, connected’to the ejector plate
separable platens 'l and 2, such as heretofore
'Ztfrhbve outwardly ‘and operate to'eject the'en
found'in an injection molding machine for the
pressure molding of thermoplastic. plastic ma
terials. ~The-platen I is‘?xed or stationary and
tire castingincluding the casting portions proper
l6’, runners H’ and gate slug [3’, as the die
blocks‘ 3 anew: are moved into open position.
,the- platen 2 ‘is'movable with respect thereto. 45 ‘Simultaneously, the'pressurefplunger-ii is moved
to a‘position slightly outwardly of the face or
;D_ie blocks 3 and ‘4 are carriedby ‘the'plat‘ens I
parting line of the “die block '3 to completely
and 2; respective1y,and ‘insulated therefrom 'by
the‘. respective layers" 5' and 6"of insulating'ma
’ terial- ‘Apres'sure cylinder ‘Lin Which'the'pr'es
evacuate'the press'ure'cy'linde‘r ‘l and clean all
of the materialv out of it.
sure plunger 8 is adapted to reciprocate, is mount 50 "As illustrated in Fig. \5,"the material'found in
"e‘d in‘the platen I 'a’nd'has its left‘hand‘or dis
the gate slug 13’ is partially solidi?ed and par
.chargeend terminating in the die block 3._ A
tially in its‘original'unplasticized state, ‘such as .
v"feed "opening 9' is provided for the introduction
that indicated at 'Z'I'in'the central portion of the
s1ug‘l3'.
‘of the'powdered-or-granular thermo'setting plas
tic ‘material ‘s‘uch‘as that illustrated at Min 55
Thus,‘ ‘it‘will be seen, ‘that as the 'pressure
"Fig. 1.
plunger moves ifrorn‘itsfposition 8 to ‘So in Fig.
The die blocks 3 and 4 form a mold cavity
1 1,, that ‘the initially" ‘?nely divided,‘ ‘solid material
comprising the portions 10 which 'formtlie cast
M‘is forced ‘throughi’the "elongated runners H
ing proper, and ‘the ‘relatively’ narrow or elongated
where ‘it’ is simultaneously plasticized under the
runners or 'gatejchannels v‘I! leading from the 60 application of heat and pressure-and thence to
cavity portions It‘! 'to the'dischargeend of the
the mold’cavi-ty portions in where’ itis subjected
‘ pressure cylinder 1.
Themovable die block 4 has a central insert
I2 which ‘projects outwardly therefrom and is
' adaptedto form the removable lefthand end wall 65
!3 oftheip're'ssuré' cylinder 1‘ when'the die blocks
'are'ini_closedlposition as ‘shown in Fig, 1. The
to a further curing heat and'pres'sure; and that
as the v?nishedcasting‘is. ejected from the ‘dies,
and the plunger‘ 8 moved out'throu‘gh the end ‘of
the pressure cylinder 1; all ‘of'the original charge
of material Miis likewise removed from the ma
chine and the latter is ready to perform a ‘repeat
- ‘outer diameter of the end wall i3 is substantially
cycle of} operations. " Thus, there is no opportu
‘equal to‘ the inner diameter of the pressure cyl
nity for any excess of material becomingc'ured or
inder 11,80 that it can‘make a slight re-entrant 70 set-in the pressure ‘chamber, or of contamination
or telescopic ?t into the end thereof. The pro
of one casting with material left over from a'pre
~ jectin'g insert !2 also has the channels II which
vious ‘fshot” or operation.
fform'aportion of the runners leading to the
My‘ above described ‘method ‘andfapparatus ren
ldersllit possible to obtaina high rate of operation
mold cavity‘ portions l0.
A cooling medium, such'as water, is introduced '
‘
‘
and increased quantity'of production in‘ the pres
2,410,510
5
'6
sure molding'of thermosetting material, while at
the same time eliminating certain‘de?nite di?icuL
ties and disadvantages heretofore encounteredin
6. The injection molding method for thermo
settingv plastic material, consisting in the steps of
transmitting a quantity of ?nely dividedsolid
the pressure molding of such materials, My in
material ‘from _ a pressure injection chamber
vention has rendered possible the practical and 5 through a connecting passage to'a mold cavity,
operative adaptation of injecting molding prin
maintaining ‘such material, while in said pres
ciples to the thermosetting plastic material ?eld.
sure chamber, at a temperature low. enough to
Other modes of applying the principle of the
retain it in said state, and subjecting said mate
invention may be employed, change being made
rial, while passing through said passage, to a tem
as regards the details described, provided the
perature su?icient to cause a plasticization there
features stated in any of the following claims
of.
or the equivalent of such be employed.
‘.
7. Themethod of molding thermosetting plas
I therefore particularly point out‘ and distinctly
tic material, consisting in the steps of providing
a quantity of ?nely divided solid material to be
molded, forcing such material under pressure
from a pressure chamber into a molding cavity,
maintaining the temperature in said pressure
chamber su??ciently low to retain such material
pressure chamber and While in the solid state
therein in the solid state, applying heat to such
educting the material from the pressure chamber 20 materialsu?icient to cause a plasticization there
toward a molding cavity, and applying heat to
of at a point between the pressure chamber and
claim as my invention:
;
,
'i. The method of molding thermosetting plas
tic material, comprising the steps of providing a
quantity of ?nely divided solid material to be
molded, applying pressure to such material in a
the molding cavity, and subjecting such plasti
such material sufficient to cause a plasticization
thereof at a point between the pressure chamber
cized material when in said cavity, to further
heat and pressure su?icient to produce s0lidi?ca—
2. The injection molding method for thermo 25 tion thereof.
8. The injection molding method for thermo
setting plastic material, consisting in the steps
setting plastic material, consisting in the steps of
of charging a quantity of ?nely divided solid ma
transmitting a quantity of ?nely divided solid
terial into a pressure ejection chamber, dischar material from a pressure injection chamber
ing said material from said injection chamber
and maintaining said material While within the 30 through a connecting passage to a mold cavity,
maintaining such material, while in said pres
con?nes of said chamber, in such ?nely divided
and the molding cavity.
solid state, passing said material through a con
necting passage to a mold cavity, and heating
‘ sure chamber, at a temperature low enough to
said material, while passing through said passage,
while passing through said passage, to a tem
perature suf?cient to cause a plasticization there-=
to a temperature suflicient to cause a plasticiza
tion thereof.
’
3. The method of molding thermosetting plas
tic material, comprising the steps of providing a
quantity of ?nely divided solid material to be
molded, applying pressure to such material in a
pressure chamber and while in the solid state,
educting the material from the pressure chamber
toward a molding cavity, applying heat to such
material sufficient to cause a plasticization there
of at a point between the pressure chamber and 45
the molding cavity, and subjecting such plasti
cized material when in said cavity, to further
heat and pressure sufficient to produce solidi?ca
tion thereof.
retain it in said state, subjecting said material,
of, and subjecting such plasticized material When
in said cavity, to further heat and pressure suffi
cient to produce solidi?cation thereof.
9. The method of molding thermosetting plas
tic material, comprising the steps of providing a
quantity of ?nely divided solid material to be‘
molded, forcing said material under pressure and
while in the solid state from a pressure cham
ber to an elongated passage and thence into a
mold cavity, cooling the entrance end of said
passage and heating its remaining portion to a
temperature suf?cient to cause plasticization of
material traveling therethrough, and subjecting
said material while in said mold cavity and while
4. The injection molding method for thermo 50 in the heated portion of said passage, to further
heat and pressure su?icient to cause solidi?ca
setting plastic material, consisting in the steps of
tion of such material therein.
_
charging a quantity of ?nely divided solid ma
10. The injection method of molding plastic
terial into a pressure injection chamber, dis
material which transforms from initially solid
charging said material from said injection cham
55
to plastic and ?nally to infusible state during the
ber and maintaining said material while within
molding operation, consisting in the steps of in
the con?nes of said chamber, in such ?nely divid
jecting a ?nely divided body of such material in
ed solid state, passing said material through a
the initial solid state from a pressure injection
connecting passage to a mold cavity, heating said
chamber into a forming mold, maintaining the
material, while passing through said passage, to co temperature
of said material throughout its trav
a temperature sul?cient to cause a plasticization
el through said chamber at a point su?iciently
thereof, and subjecting such plasticized material
low to remain in such solid state subjecting all
when in said cavity, to further heat and pressure
but a small fraction of such body of material,
sufficient to produce solidi?cation thereof,
after passing through said chamber, to a, tem
5. The method of molding thermosetting plas 65 perature
sufficient to transform the material into
tic material, consisting in the steps of providing
the plastic state, further subjecting such ma
a quantity of ?nely divided solid material to be
terial when in said mold to su?icient heat and
molded, forcing such material under pressure
pressure to transform it into the infusible state,
from a pressure chamber into a molding cavity,
and evacuating the entire body of the originally
maintaining the temperature in said pressure 70 providedmaterial from the injection chamber on
chamber su?iciently low to retain such material
each stroke of operation.
therein in the solid state, and applying heat to
11. In a pressure molding machine having a
such material su?icient to cause a plasticization
pressure chamber, separable die blocks forming
thereof at a point between the pressure/chamber
a, plurality of mold cavities with a plurality of
and the molding cavity.
75 runners for said cavities located in their parting
2,410,510
a
7
line, the improvement which comprises a pro
parting line, the improvement which comprises
jection mounted on one of said die blocks and
an insert ?xed in one of said die blocks and pro
entrant into the discharge end of said pressure
jecting into the discharge end of said cylinder,
said insert having an outer diameter substantially
equal to the inner diameter of said cylinder, and
‘chamber, and divergent runners in the outer sur
face of said projection forming a continuation
of said ?rst-named runners, heating means lo
cated adjacent said mold cavities and said run
ners for heating the surfaces thereof, and cool
ing means adjacent said discharge end of said
pressure chamber for cooling the interior of the
latter.
12, In a pressure molding machine having a
pressure chamber, separable die blocks forming
a plurality of mold cavities with a ‘plurality of
runners for said cavities located in their parting
line, the improvement which comprises a pro
jection mounted on one of said die blocks and
entrant into the discharge end of said pressure
chamber, and curved runners in the outer sur
face of said projection forming a continuation
of said ?rst-named runners, heating means lo
cated adjacent said mold cavities and said run
ners for heating the surfaces thereof, and cooling
means adjacent said discharge end of said pres
sure chamber for cooling the interior of the lat
ter.
13. In a pressure molding machine having a
curved runners in the outer surface of said in
sert leading from the parting line of said die
blocks and each forming a, continuation of said
?rst-named runners, heating means located ad
10 jacent said mold cavities and said runners for
heating the inner surfaces thereof, cooling means
located in said insert for cooling the surface of
the latter, and a, second cooling means located in
the wall of said cylinder for cooling the interior
15 thereof.
14. Apparatus for molding heat plasticizable
material, comprising in combination cooperating
dies providing molding cavities, one of said dies
having a bore extending from the outer face
20 thereof to the parting line between the dies, a
cylinder having an open end extending into said
bore, a plunger movable within said cylinder to
force said material as a cylindrical mass in the
direction of said dies, a nose secured in the die
25 beyond the parting line in alignment with said
bore and extending into the cylinder‘ and means
for supplying heat to said nose to raise the same
to a temperature above the temperature of the
material injection cylinder and a pressure plung
er reciprocable therein, separable die blocks
material Within said cylinder.
forming a, plurality of mold cavities with a plu 30
rality of runners for said cavities located in their
NATHAN LESTER.
Документ
Категория
Без категории
Просмотров
0
Размер файла
673 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа