Note: Descriptions are shown in the official language in which they were submitted.
~193~
BACKGROtlND OP T~ INVENTION
This invention relates to die casting machines and
in particular to a system including a die ca~ing machine
of the balanced, dual movement type that incorporates two
pair~ of spaced, parallel cylinder assemblies each of which
support a mold half, the pistons of the cylinders being
~ecured to the machine frame and the cylinders moving thereon.
In a conventional die casting machine a frame is
provided and a fixed or stationary plate upon which one-half
of the mold for making the p~rt is mounted on the frame. The
other half of the mold is unted upon a moving plate which
allow6 the cast part to fall out of the machine when in the
open position and the moving plate is clamped shut with
~ufficient force to contain the molten metal while the mold
is being filled. In operation, the part separates from the
half mold on the fixed plate (the cover half) and is retained
on ~he half mold of the moving plate (the ejector half) as it
moves open following solidification of the molten metal which
was injected into the mold cavity. The pArt which was
retained on the moving or ejector half of the mold must then
be ejected from it to fall out or be transferred out of the
machine. ~he one-sided motion described above is one of the
major causes for the various and complicated types of auto-
matic part-transfer mechanisms associated with sonventional
casting machines which have been retrofitted with some sort
of part-transfer. The s~me problem then arises as the part ~s
indexed to a secondary operation ~uch ~s trimming wherein a
similar one-sided machine is used. ~he part-transfer carrier
i~ required to h~ve both an indexing function and a lateral
movement to match ~he plate closing and opening stroke as the
part i5 ~rought into a fixed pos~ tion for the des~red operati on.
This conventional form of mach~ne was greatly ~mproved
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1119376
upon by the ~achine shown in the U.S. Patent to Perrella,
4,013,116 which issued on March 22, 1977. This machine is
much simpler than conventional devices in that ~he part was
cast, indexed ~nd removed from the machine 40r trimming without
any lateral movement of the part. Dur~ng processing the part
is in a fixed plane and i~ transferred in that-plane. ~he
casting machine has balanced forces in which both plates and
mold halves or dies are moved equal aistances to and from the
part plane and this balanced movement of ma6s cancel~ out
the normal shock of starting and stopping hea~y pl~tes and
tools, equalizes thermal expansion differences ~nd automatically
centers load deflections.
SU~ARY OF THE INVENTION
The balanced, centred, single plane machine principle
of U.S. Patent 4,013,116 is the ba6is for the present invention
but on which numerous improvements and additional features
have been added such as a cable conveyor of low mass and simple
design for transfer of the parts out of the mach~ne, a &imple
part carrier finger at the center line of the mold, metal-
injection on the mold parting line, one balf the normal strokefor plate mv~ement and thus one half the non-productive time
for machine opening and closure, a top core pin position
on the mold psrting line to stabilize the part pos~tion during
mold-opening and eliminate the need for e~ector pins on some
types of parts, opportunity to add intern~l cores in both mold
halve~, and automatic loadiny clearance during installation of
the mold and trim dies. The machine of the present invention
i6 designed as a total integrated casting unit which will
deliver a guality part cast and tr~mmed automatically at a present
rate of production. As such it i6 one unit incorporating
numerous features.
The main machine consist~ of a frame, mold mounting
376
plates and hydraulic closing and opening cylinders havin~ a
simple deceleration system to eli~inate closing shock. A
standard and uniform ~asic mold con~iguration is provided and
is adaptable to a large variety of part styles and is of
pre-deter~ined registry in the machine plates so as to
eliminate mold miss-match because o~ thermal expansion or
poor die set practices. Metal-in~ection of the machine is
provided with an infinitely variable control capable of
presetting to any desired speed or pressure, together with a
self-contained molten metal supply with electric resistance
heaters therein.
A self contained hydraulic power system is incor-
porated, using fire-resistant fluid. Provision is made to
pre-heat the molds prior to the first shot. The machine
features a self-contained heat unit for cooling the molds
and eliminating lime deposits in the cooling passages all of
which is automatically connected to the mold during
installation without hoses or pipes. A cable transfer
conveyor is also provided to carry the part on a finger to
other secondary operations with adequate time before trimming
for natural non-distortion cooling of the part prior to
trimming, together with a complementary trim machine and
basic trim die designs to push the part through the die to
a carry-away conv,eyor.
In accordance with a broad aspect, the invention
relates to a transfer s~stem for carrying cast parts from a
casting machine to a secondary operation comprising an endless
conveyor cable trained between the dies of a die casting
machine and said secondary operation; a plurality of fingers
adjustably mounted on said cable for sequential positioning
between said dies to receive a casting therearound; sprockets
for driving said cable; and adjustable link means on said
cable for engagement by said drive sprocket.
The abo~e and other features will be understood
from the following disclosure and accompanying drawings
wherein:
Figure 1 is a plan view of the die casting machine;
Figure 2 is a cross-sectional view of the machine
taken along the line 2-2 of Figure l; .
Figure 3 is a schematic, cross-sectional view taken
along the line 3-3 of Figure 2;
Figure 4 is a schematic layout of the heat transfer
system for cooling the dies of the machine;
Figure 5 is a cross sectional view of the metal
supply pot and heating means;
Figures 6 and 7 are schematic illustrations of the
2~ metal injection;
Figures 8a and 8b are cross sectional views of the
metal injection unit;
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1~93~
Figure 9 is ~n enlarged cross ~ectional view of
the valve mechanism of the injection unit;
Figure 10 is a side elevation view of the injection
unit;
Figure 11 are elevation and end view of the swAn's
neck joint;
Figure 12 i8 a cross sectional view taken along the
line 12-12 of figure 8a.
Figures 13 and 14 are concept illustrations of the
nozzle arrangement of the invention;
Figures 15 and 16 are views of a preferred nozzle
arrangement;
Figure 17 is an elevation view of a typical mold
cavity;
Figure 18 is a cross sectional view of the rotary
ejection mechanism;
Figure 19 illustrates the cam and follower of the
rotary ejection;
Figure 20 a, b and c show various positions of the
rotary ejection during its operation;
Figure 21 i8 a cross ~ectional view showing the
core pin withdrawal sy~tem;
Figure 22 is an elevation view of one end of the
part transfer mechani6m;
Figure 23 is an elevation view of another end of the
tran~fer mechanism;
Figure 24 is a cross sectional view taken ~lons the
line 24-24 of ~igure 23;
Figure 25 i8 a 6ect~0nal view of the t~ansfer finger;
Figure 26 1~ a cro6s sectional view taken alo~g the
line 26-26 o~ Figure 22;
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lil9376
Figure 27 i8 a ~ectional v~ew of the kicker mechanism;
Figure 28 i~ an elevation view partly in cross ~ectionof the trimming npparatus; and
Figure 2~ i5 a cross sectional view taken along the
line 29-29 of Figure 28.
Figure 30 is an elevation view of a cas~ part as it
enters the trimming apparatus;
Figure 31 is ~ plan view of a punch of the trlmming
apparatus, and
Figure 32 is a sectional ~iew of the punch and die of
the trimmer.
GENERAL DESCRIPTION
Referring to Figures 1-3 a die casting system according
to the invention includes a die casting machine 10 having a
frame 12 with two pairs of spaced, parallel cylinder assemblies
14, 16 mounted thereon. Each pair of assemblies 14 support
a mold half 18, as shown in Figure 3, and is opposed to the
other pair of assemblies 16 which carries the other mold half
20. As seen best in the general layout of Figure 3, each
cylinder assembly of each pair comprises a stationary piston
22 secured to the frame 12, a piston shaft 24 secured
coaxially ~t one end to, and axially aligned with the piston
22, the shaft 24 extending across the centre of the machine
to a connection at it~ other end ~ith ~n opposed piston 26
of the other cylinder as~embly 16.
As illustrated in Figure 3, each cylinder assembly
14, 16 compri~es cylinders 28, 30 re~pectively mounted on
the plston6 22, 26 and shafts 24 for reciprocal movement nf
the cylinders thereon in response to hydraulic fluid injected
on the crown or ~kirt end~ 62, 64 respectively of the pistons
whereby the n~3emblles 14, 16 and their assoclnted ~old halves
are moved to open or closed (a~ Ehown) positlon~.
.
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376
A more detailed description of the basic concept of the
m2chine 10 may be had from the disclosure of U.S. ~atent
4,013,116.
Turning to Figure 1, a plan view of the machine 10
shows the mold clamping ~ylinders 14, 16, platens 32, die
~eparation and ejection cylinders 34, ~nterference block~ 36
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37~i
for preventing accidental cylinder movement and the drive
mean~ 38 for the transfer mechanism.
Figure 2 illustrates the in~ectox ~ssembly 40
comprising the furnace 42 gooseneck 44 with shot and ~elector
valves 46, 48; and shot valve locking sy~tem 50. Nozzle 5~
directs the zinc shot into the mold 54 to provide a casting 56
that is cAst onto a carrier finger 58 on the transfer mechsnism
60 that transports the cast part to a trimming stetion.
A die casting machine requires only a small, nominal
force to advance the molds to their closed position shown
in Figure 3 but this must be followed by a strong clamping
force to retain high internal pressures developed in the
mold when the casting metal is injected therein. Therefore,
a cylinder large enough to clamp the die would require an
excess volume to fill it during the closing stroke. As seen
in Figures 1-3, the machine of the present invention is of
the two-tie bar type with each end of the two ~hafts 24
extending through the hollow centre of the two stationary
pi&ton8 22, 26 on each side of the machine. As seen in
Figure 3, the pistons hs~e rod exten~ions 22a and 26a on
their skirt ends but the extensions are of a smaller di~meter
than the crown ends of the pistons and therefore form a
slightly different pressure area at each end of the ~urround-
ing cylinders 28, 30 which are the moving ~embers and which
are integral with the m~chine platen~ 32 on each side of the
machine centre. Accordingly, by pressurizing both the crown
end 62 ~nd skirt end 64 of each cylinder and provid~ng an
internal flow psssage from the smsller pre~sure area 64 to
the larger 62, the fluid volume th~t is required for a ~ylinder
stroke ~n one direction 18 only the difference between the
two areas 62, 64, t~me~ the ~troke. When closed as in Figure
3, the pre~sure to the smaller area 64 is dumped to t~nk
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3~
allowing all the force on the larger area 62 to clamp the
die closed.
The above de~cribed ~yste~ works only for die closing
and therefore the ejector cylinder 34 i~ used for die opening.
Cylinder 34 is also of a double-rod type utilizing a relat~vely
6mall net force area and thus requiring ~ minimal hydraulic
flow volume. Cylinder 34 pushes agninst $ixed outer 6tops
35, Figure 3,to open the machine and ~ubsequently retracts
to withdraw a stripper pin plate (Fig. 21). We have ~ound
that substantial saving in fluid volume is realized
frcm thi~ ~ystem.
HEAT TRANSFER
Die casting in a permanent mold involves the process
of transferring heat from a molten metal alloy to the walls
of the die cavity nnd from the cavity to a heat exchange
medium. Accordingly, certain specific para~eters must be
maintained to attain the heat flow rate desired.
In the system of the pre~ent invention, the heat
exchange medium is water and electric immerfiion heater~ are
used only to preheat the die to operating temperature and
thereafter the temperatures above the boiling point of water
are reached by controlling the internal prefisure of the die
cooling cavity, the actual heat removal being accompli~hed by
evaporation of the water as it flows through the ~ystem in a
metered quantity.
~ he ~ystem is shown ~chematically in Figure 4 which
fihows immer6ion heaters 66 situated in the nold manifold 68
adjacent the cavity face 70 and where they preheat the die
to operating temperature, say 400F. ~he water pas~ges 72
3~ in which the heaters are immersed are in co~munic~tion with
cooling passageway~ 74 which interconnect inlet ~nd outlet
valves 76, 78 re~pectively.
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3l11~33~
The surface area in the die cavity that is exposed to
the molten metal casting alloy is in proportion to the area of
cooling surface exposed to the water and the dis~ance between
the t~o surfaces is sized according to the heat-transfer rate
of the die cavity material.
The heat transfer from the die block to the water is
by evaporative cooling only. The t2mperature of the water
within the cooling passages 72 of the die is maint~ined at an
elevated point which is conductive to making good casting
finishes during the metal injection. Subseguently, when the
part is cast the excess heat is carried away as boiling occurs
only where an overtemperature condition exists. Therefore, no
circulation or flow of water is re~uired within the die passages
72. As steam is generated in direct proportion to the heat
removed from the molten metal it is only necessary to inject
a make-up water volume slightly in excess of the steam escaping
through the pressure relief valve 78.
As 6hown schematically in Figure 4, water from a
holding tank 80 is injected by pump means 82 into the cooling
passage 72 through the inlet valve 76 at a pressure slightly
in excess of the water being evaporated. As the heat trans-
ferred to the pas6ages 72 from the die 70 cause the water
in the passageway 72 to boil, the valve 78 opens under the
pressure of the ~team to allow it to escape via a manifold
passageway 84 and line 86 where the ste~m ~ondenses and
returnc to the tank 80.
It will be appreciated that the heat transfer system
is an integral part of the mold design and function and
provides for precision flow adjustment built for and adaptable
in design to ~ variety of mold re~uirements. It completely
eliminates the use of hose att~chments and ha8 the feature
of flow ~djustment retention fr~m one run to the next.
_ g _
3~
METAL INJECTION UNIT
The metal in~ection unit of the present invention,
indicat,ed at 40 in Figuse 2 is different in principle in
numerous ways from conventional systems and which effect both
performance and safety ~spects. In effect, the only sLmilarity
to conventional systems is that it employs a force to drive a
piston which in turn creates an hydraulic pre~sure to fill the
mold cavity.
The injection unit 40 is suspended in the supply pot
42, Figure 5, which comprises a double steel wall construction
having an inner wall 106 and outer wall 108 spaced by web~ 110.
This structure gives the strength effect of a continuous large
H-beam to resist the ~nternal force of the molten metal and
also provide an air-~pace form of insulation. The interior of
the pot 42 is lined with a suitable insulator such as ~ermiculite
board 112 to which a castable refractory lining 114 is applied.
The temperature of the molten metal in the pot 42 is
maintained at the desired level by a plurality of electric
immersion heaters 116 (as shown al~o in Figure 8a) spaced
throughout the pot 42. Each heater 116 comprises an element 118
encased in stainless steel tubing 120 to protect the heaters
against corrosion, enlsrge the ~urface area exposed to the
ca~ting alloy and thus reduce the watt-density.
The injection of casting metal into the die cavity is
effected by the injection assembly indicated generally at 40
in Figure 2. As shown in detail in Figures 8a, 8b and 10, the
assembly 40 comprises ~ steel body 122 suspended within the
~onfines of the furnace pot 42 by ~eans of ~rms 88 which
support the crown 90 of the as~mbly from the n~chine frame 12,
the crown 90 being connected to the body 122 ~y long studs 92.
~he body 122 lncorporate~ a large d~eter cyllnder
124 to accommodate the piston 128 of the ~hot v~lve ~ssembly 46
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376
and a small diameter cylinder 126 to accommodate the valve 130
of the selector assembly 48.
As shown conceptually in Figures 6 and 7, piston 128
intensifies the pressure of casting metal going to the die
and ~alve 130, depending on its vertical positioning, selects
A flow path from the pot supply to fill the pressure intensifier
chamber 132 at the bottom of cylinder 125 (Figure 6) or selects
a flow path to the die from the pi~ton 128 (Figure 7~.
Chamber 132 is connected to the selector cylinder
126 by a passageway 134 and conduit 136 in the gooseneck 44.
As shown in large scale in Figure 9, selector valve 130 -
has an upper head 100 and a lower head 102 interconnected by a
stem 104 of reduced diameter. Upper head 100 mates with valve
seat 140 and lower head mates with seat 142, depending on the
operative mode. It will be noted that the spindle has upper
and lower arms 144, 146, which slidably engage the
portions of the cylinder 126, thereby leaving ample room
between the cylinder wall and the spindle body for passage of
casting metal the~eby.
During the interval between machine cycles, selector
valve 130 is maintained in its 6hut-off position to the nozzle
conduit 136 but open to the pot 42. Th~s position would be that
r at the top of its ~troke "S" with head 100 engaging seat 140,
or the "hold and refill" position indicated in phantom line in
Figure 9. In this shut-off position, valve 130 constitutes
A positive ~afeguard against acciden~al flow to ~he machine
nozzle. At the next cycle - sequence signal, the v~lve 130 is
shifted to its ~ottom poq~tion shown in Figure 9 and the
~hot mode, ~rrow A, is ready.
Valve 130 is vertic~lly actuated by a ram 148 connected
to the valve through a frame comprising piston rod 150
7~
secured to a frame made up of upper and lower horizontal cross
~rms 152, 154 and vertical arms 156.
The shot cylinder 96 and in particular piston 94
therein i8 actuated by an external supply, infinitely variable
pneumatic pressure volumetrically sized to the underside of
piston 94. Briefly, the shot cylinder 12~ i~ cycled 80 a~ to
fill the mold cavity and instantaneously withdraw the pres~ure.
Because the gate thicknes~ of a casting mold i8 thinner than
the casting cross-sectionr the gate thickness is the first to
solidify and does so in a fraction of a se~ond. Therefore, an
instantaneous reversal of the pressure does no harm to the
casting but does permit the unsolidified metal in the large
inlet runner sections to drain out and thereby leave only a
slush-molded tubular runner section Attached to the part, as
will be illustrated further on. There are several advantages
to this runner-drain principle of operation. First, valuable
cycle time is not lost waiting for heavy runner sections to
solidify. Secondly, the tubular 6ection of the casting is
very s~rong and provides a light frame for tr~nsfer of the part
out of the mold; the runner and part emerge at the same
temperature which favors dimensional stability prior to
trimming; much less heat is imparted to the runner area of
the mold and the hollow runner~ cost less to remelt. Also,
the casting metal drained from the runner i5 held at a point
just inside the nozzle tip thus minimizing the volume of air to
be expelled from the mold cavity.
~ urning to Figure B~, piston 128 i5 sbown at its
maximum shot position at the bottom of its ~troke ~S~ of the
ram rod 96. When a cast~ng is completely filled, piston 128
will stop, the flow of molten metal having pasced through the
open port of valve 130, arrow A, Figure 9. A irac~ion of a
second after the $njection ls completed and the ~sting gates
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:.,
.~
~ 37
are solidified, piston 128 is displaced upward by pressure on
the underside of piston ~4. This supply is volumetrically
equal to the amount of metal contained in the runner system
of the casting die to a point just inside of the nozzle tip.
At this moment, piston 128 is arrest~d in its upward movement
long enough for selector valve 130 to shift and hold the
column of metal in the nozzle and gooseneck conduit 136 in ~ ¦ ;
static position and simultaneously open the valve 130 to the
"hold and refill" position of Figure 9 so that there is
communication from the supply in the pot 42 into the chamber
132. Piston 128 is th~n signaled to return to its topmost
position enabling the cylinder 124 to fill.
A pressure accumulator may be provided for the shot
cylinder 98 to include a variable pressure pneumatic pre-charqe
system to provide a constant source of pressure to the cylinder
98 but being infinitely variable as required for the particular
casting being made. A casting shot is made when the opposing,
hydraulic pressure is released to drain and the pi~ton 94 is
returned to its starting position of Figure 8a when the
hydraulic pressure is re-applied. However, the first movement
of the shot-return nction is ~ccomplished by an auxiliary
hydraulic displacement cylinder having an ad~ustable stro~e to
inject a controlled amount of fluid into the shot-return
circuit. This action serves to withdraw the shot piston 128
and in turn provides space for the unsolidified casting metal
in the runners of the die to drain out leaving A shell molded
hollow section ~s mentioned previously.
An accumulator type receiver is provided to accept the
fluid discharged from the shot cylinder. The fluid so
discharged is in the order of 500 g.p.m. and the receiver
subsequently discharges the fluid ~lowly ts drain to tan~
during the ~a~hine ~ycle period.
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111~33~6
A safety restraint or n scotch~ sys~em i8 6hOWn
generally at 141 in Figure 8a and in detail ~n Figure 12. This
appar~tus prevents actuation of the ~hot when m~k~ng machine
adiustments and when the 'shot n mode i8 not selected.
Ram rod 96 is provided with a c2mmed flange 143
adapted to engage and momentarily displace a p~;r of locking
collars 145, 147 when the ram 96 and piston 94 ~re on their
upward stroke so that flange 143 then nests in the socket 149.
Collars 145, 147 ~re malntained ln their closed positlon of
Figure 12 by a ~pring 149 and are opened against the spring
pressure by the upward movement of the flange 143. Once in the
socket 149, piston 94 and ram 96 cannot progress downward as
the closed collars engage the underside of the flange 143. As
shown in Figure 12, collars 145, 147 are pivotally mounted on
pins 151 and geared together by teeth 153.
Collar 147 has a wing 15S held to the closed position
by the spring 149 on a pin 156 slidably positioned in a me~ber
157.
An actuator 158 has a rod 159 actins on ~he other
side of wing 155. It will be appreciated th~t ~hen actuator
158 di~places rod lS9, collars 145 and 147 ~111 be opened
to allow the r~m rod 96 to progress downwardly~
The entlre injection assembly is su6pended and
supported by a cantilever frame made up of the arms 88 and
cross plAte 89 bolted to the frame 12 of the ca~ting ~achine.
Alignment ad~u6t~ent of the a~sembly i8 accomplished by ~crews
160 for linear mDvament along the axis or centreline of the
goo6eneck 44, and by ~crew6 162 for verti~al and 164 for
horizontal riyht and left movement. For alignment of the nozzle
tip tG the ~a6ting die ln the plane of x-x, Flgure 8b, the
ball and ~ocket plvot 166, whlch i5 61ightly loo~ened during
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37~ `
the alignment procedure, permits a 3-axis movement to ~e made
to loc~te the nozzle tip in line and ~qunre with the casting
die.
It will be seen from Figure 10 that cantilever ~rms
88 have Rurfaces 168, 169 which when extended to lines A
and B are parallel to the centre line of the gooseneck 44.
Crown 90 has shoes 170 that ride on susf~ces 168 and 169 so that
adjustment of the screws 160 moves the assembly linearly correct.
The sequential operation of the ~etal in~ection
system is as follows.
A signal from the mold clamping action causes the shot
6elector valve 130 to move to it~ downward position of Figure
9 and thereby contact a positional sensor.
~he positional sensor ln turn ~ignals the restraint
system to withdraw, effecting movement of the actuator 59 and
releasing the collars 145, 147 from the ram flange 143.
The restraint sensor gives signals to activate the
metal in~ection shot piston 94 and to initiate a timer which
signals the partial retract ~ystem ~ter a fraction of ~ second
delay to give time for the metal in the mold gate~ to solidify
and thereafter drain out the runner cores. At ~he completion
of the time delay the ~hot ~elector valve 130 returns to its
upward posltion.
The up position of seiector valve 130 then signals
the ~hot cylinder 94 to return to ~t~ top position and again
the restraint system moves to its locked po~ition.
NOZZLE
-
A~ ~hown in Figure 8b ~ nozzle extension ~ B provi~ed
to bridge the dlstan~e from the pressure intenslfler 128 to
the casting die 54 tFigure 2). Referri~g to Figure 11, the
extension includes ~n ad~ustable ~oint coupllng ln~icated
generally ~t 184 wh~ch connect~ t~e termlnal end 186 of the
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1119376
gooseneck with the extension 188, The end 186 of ~he gooseneck
riser is machined to provide a peripheral flnnge 190 and
adjacent groove 192. The extension 188 terminates ~n a
epherical end 194 and, when the end 194 and the end 186 are
properly aligned the conduit 136 ~ completed. The two ends
are held in aliqnment by mean~ of a pair oi clsmps 196, 198
secured together by bolts 200 as Ehown. The clsmping blocks
196, 198 are al~o provided with n plurality of cartridge heaters
202 to m2intain the proper temperature level in the connection.
~s mentioned in the preamble of the present disclosure,
the die casting machine of the present invention utllizes a
~parting line" injection where the entry of the molten casting
metal into the die passes through the conduit 136 which is
centred with the parting line of the mnld and at the periphery
thereof on one side. There must of course be a leak-proof
fluid tight seal with the nozzle when the mold is closed and yet
there must be freedom for the mold to open without dragging or
sticking. With known nozzle tips of circular shape, the mold
has to have two half round shapes to close about it whereby a
condition exist~ of zero olearance angle at the parting line
where the two corners of the half circle are t~ngent to the
di~meter and, since a leakproof ~eal requires an interference
fit, it is impossible to not have some opening friction. ~o
obviate this and other associated problems, a square, diamond
sh~ped nozzle ls utilized as sh~wn conceptually in Figures 13
and 14. A s~milar configuration i~ u6ed or the cnrrier finger
58 (Figure 22) the purpose of which will be subsequently
d~scloQed.
AB shown in Figures 13 and ~4, the mold halves 68 are
provided wlth lnserts 20~ and ~ile not illustratea, the square
nozz~e 204 1~ ~llght~y larger than the squ~re hole that ~s
formed ~or it ~hen the mold halves 68 ~re close~ about the
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1119 ~7
nozzle. The parting line variations in the nozzle to machine
alignment might be in the area o~ plus or ~inus 0.20-0.30 inch
and these dimension6 are absorbed by the ela~tic ~ovement of
the injection ~ssembly. The in~ert~ provide opportunity
for precision fitting of the parts concerned. It will be
appreciated that all of the surfaces of the nozzle and the mold
will be subject to the s~me unit force upon closing as well A8
providing a very accurate camming means to bring the two
mold halves into proper alignment.
A preferred emboa~ment of the nozzle having a
multi-faceted design is shown in Figures 15 and 16 where the
nozzle 208 has slightly rounded or cut off corners 210 but
does have flat surfaces 212 for lateral alignment by inserts
206 provided on both mold halves 68. In addition, as shown in
Figure 16 the nozzle has ~ngul~ted faces 214 ~nd 2~6 in side
view which mate with simllar faces in the mold half inserts
206 to effect the proper linear alignment.
Figure 16 al80 illustrates a cross-sectional view of a
flash-guard 236 which is formed by surface 220 of reduced
di~meter and the adjacent ~urved ~houlder 222 in combination
with the poc~et 226 and its offset ~urface 228. If for any
reason molten metal should leak under pre~sure from the nozzle
tip, the resulting flash would follow the ~rrow F, being directed
into the pocket 226 by the shoulder 222.
The de~ired temperature of the nozzle 208 i8 maintained
by a nozzle cover 248 enclosing suitable insulation 250 which in
turn ~urrounds elec~ric henter~ 252.
MOLD
Figure 17 illustrates the ~old of the present machine.
One of the ~asic advantages of the pre~ent machine over the
prior art i5 the ~early perfect thermal ~alance between the ~old
halve6 68 ~oupled w~th die 6eparation 6imultaneou~1y away fr~m
.
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1119376
the casing. In situations having no core ping and adequate
draft ~ngles, parts can be produced without any ~ripper pins.
~owever, e~ther wlth or without 6tr$ppers the part i~ supported
at three points around the periphery of the ~rame in which it
is cast. These three points form n plane of reference from
~hich the part i~ subsequently trangferred out of the machine.
As shown in Figure 17, the nozzle has ~ade a casting ~n t~e
mold and the inlet runner 254 extends between the gate area 256
~nd that portion of the mold 258 whlch will provide a casting
around the transfer finger 58 6hown in Figure 22. Further
gates 260 extend from the inlet runner into the casti~g proper
262 (in this case a logo DBM and frame therearound) and hn outlet
runner extends upwardly to surround a top core sl~de 264.
Therefore when the die halves 68 are simultaneously sep~rated
the ca8ting is held by a) the top core slide 264, b) the nozzle
entry 256, ~nd c) the transfer finger 258, the part 262
~ubsequently being tran~ferred out of the machine by f$nger 58
as will be subsequently described in relation to Figure 22.
In addition, when the top ~upporting core 264 becomes a core
for forming ~ section of the casting, it al80 serves as the
third point of support durlng opening of the die~ nnd virtually
eliminates the need for ~ny 6~ripper pins.
EJECTOR PIN RELEABE AND RETR~CT MECHANISM
In conventional die casting ~achines the cast p~rt
usually follow~ the ejector half of the mold a~ it pu118 away
from the cover half. Then, upon nearing the end of the opening
stroke6, e~ector pins extend and push the part away from the
~old face. In order to en6ure th~t the part i8 released ~rom
the pin ~ces a f~rther device ~ used to aisturb lt6 tendency
to 6tick on t~e plns and thi~ devire ~8 commonly called a
~quick e~ector~ and it actually tips the part out o~ the
origin~l worklng pl~ne.
.
- 18 ~
~1193~
A "quick ejector" arrangement ~annot be used with the
machine of the present ~nvention as the part must be retained
in it6 original working plnne. Additionally, the part must be
held in a fixed plane a~ both halve~ of the mold are opening.
Accor~ingly, the die casting machine of the prese~t ~nvention
require~ a completely different type of part ejection device
to loosen the part ~rom the mold ~nd hold it ~n thi6 desired,
fixed position. Therefore, means are provided to both loo~en
and retract the pins to leave the part retAined At the
centre line of the machine and attached to the carry-out finger
58 at one edge ~nd the nozzle impression at the other.
Figure 18 is a cross-6ectional view of the ejector plate
and its ~s60ciated mechanism for rotating the ejector pins.
Such mechani6m is provided from both 6ides of the cavity.
The ejector pin 228 is mounted at one end in the
ejector plate 230 and extends through to the die face 232. To
this end, the pin 228 has an extension piece 234 ~ecured in
coaxial alignment with pin 228 by means of a tube 238 h~ving
pair of helical channels 240 formed therein ns shown in Figure
19. Pin 228 and extension 234 are welded to the tube 238 and
it6 free end iB thread~bly engaged in a bushing 242 yieldably
mounted against rot~tion in a pocket 246 under pres~ure o~
bellville wa~hers 266.
The ~old plate 268 i6 provided with ~ shoulaered
sleeve 270 having a p~ir of diametrically opposed pt n
follower6 272 thereon and which ride in the helical channel~
240 ~6 ~hown in F$gure 18. Sleeve 270 i6 provided with a
~pline 274 ~see ~n~et) which engages ~ ~pline 276 on ~ tubular
~pring lock 278 when release pin 280 i6 retracted.
As the machine close the mold halves together, pin 228
i6 in the posi~ion of ~gure 20a, it~ termin~l end extending
~ust beyond the die part~ng line. A~ the mold6 close, F$gure
937~
20b, pin 228 is linearly retracted against washer~ 266, under
pressure of about 300 lbs. ~elease pin i5 retracted allowing
~pring 282 to slide lock 278 forwardly, engaging the spl~nes
274, 276~ preventing rotation of sleeve 270. As the mold
plate 268 i~ pulled back towards the position of Figure 20c,
the follower pins 272, acting in the channels 240, rotate the
tube 238 and pin 228, the extension 234 ~hreading it6elf into
bushing 242. When the plate 268 reaches the position of
Figure 20c, the pin is then linearly retracted against the
washers 266 to nbout a 400 lb. load, pulling the pin 228 back
from the casting by a di~tance ~Bn, about .008 inch.
Returning the plate 268 to it~ olosing posltion of
Figure 20a the tube 238 is rotated back to its Figure 18
position, release 280 disengaging the spline~ 274, 2?6.
Rotation of the pin face in relztion to the casting
disturbs its attachment thereto caused by tbe pressure of the
ca6ting proce6~. Secondly, as shown in Figure 20, lt withdraws
the pin a precise distance depending upon the chosen design
of the helix ~40 on the tube 238. Thus, pin 228 is both
loosened and withdrawn leaving the cast part completely free
but ~till contalned within the small clearance between pins
extending from both halves of the mold.
CORE PIN WI~HDRAWAL
Means are provided for primary core pin withdrawal
prior to opening of the die and immediately following the
solidus condltion of the cast metal. Thi6 permits a true
~tripping action with~ut distortion of the casting as well as
for le~s 6train on the core pin ltself because the casting
ha6 not had time to cool ~nd 6hrinX tight around the core.
As cores are to have at lea6t .0005 inch per inch t~per per
6ide it i~ only neoessary to withdr~w the core enough to exceed
the ~mount of cnsting ~hrlnk~ge durlng the ~rief interval
- 20 -
376
between the solidus time ~nd withdrawal t~me. The advantage is
significant in respect to scrap reduction, pin breakage and
lack of di~tortion $n the casting because the cores are entirely
free of the ca~tinq when the die is open.
Referring to Figure 21, the machine ejector plate 284
supports an air cylinder 286 which linearly actuates ~ rod
2~8 that is coupled at its terminal end to further plates 290
that retain a plurality of core pins (only 1 of which is ~hown),
each core pin being positioned w~thin a tubular stripper pin 294.
Actuation of air cylinder 286 serves to advance or retract
pi~ton rod 288, plates 290 and pin 292 within the stripper 294.
TRANSFER MECHANISM
As indicated generally in Figure 2, the finger 58 of
the part transfer mechani~m 60 carries the cast part from the
die cavity to secondP~y operations such as trimming. When a
part is c~st from molten metal in ~ permanent mold it must
remain in the mold after solidification for a long enough period
to attain sufficient strength to be self supporting from its
own weight. However it is of course also desirable to open
the mold as soon as possible in the intere~t of a short cycle
time and to minimize shrinkage onto the male cores. In pract$ce,
the casting emerges several hundred degrees above ambient
temperature and if cooled by the conventional practice of water
quenching, severe strain~ are built up in the part wh~ch can
ma~e it dimensionally unstable, particularly in reqions where
heavy ~ections ~re ~djacent to thin ~ections.
In the system according to the present invention, a
con~eyor is provided whi~h transfer~ the part which has been
ca8t onto a finger 58 out of the ~old 60 and through a ~equence
of indexe~ until it has been air ~ooled 810wly to near ~mbient
temperature. ~he slow coollnq greatly reduces strain in the
part and presents it to secondary machining operations with
- 21 -
~1937~i 1
great,er accur~cy.
In the illu6trated embodiment of the present invention
the c,~st part is tr~nsferred from the mold~ 60 to a trimming
operation, Figure 22 illustr~ting the ~casting" end of the
transfer mechanism and F~gure 23 illustrating the utrimming"
end of the trans~er mechanism.
Referring to Figures 22 and ~3, the transfer mechanism
generally indicated a~ 60 comprises a frame 296 which c~rries
prockets 298 and 300 on the casting end of the mechanism ~nd
sprockets 302 and 304 on the trimmlng end. The 6pro~kets are
interconnected with upper run ~ide plates 306, 308, sprockets
302 and 304 having their own side plates 310 for a purpose
which will be described. Other side pl2tes 312 are provided
between but are ~ot connected with ~prockets 304 and 298 for
the return lower run of the transfer mechanism.
As shown clearly in Figures 25 and 26, a multi-strand
wire cable 314 is provided around the 6prockets and cRble 314
has much greater tensile strength than is required for the
working load. Cable 314 forms the basis of the transfer 6ystem
60 and to that end is provided w$th a plurality of metal fingers
58 which are loosely ~ttache~ to the cable 314 to carry the
casting 56 from the mold 68. As described in relation to
Figure 17, the casting or "part shot" consists of the casting
supported within the frame whlch includes the metal inlet
runner~ 254 and 260, the part 262 ~nd the gates, overflows
~tripper pads etc. ~nd the Eocket end 258 which i~ cast onto
the conveyor tr~nsfer ~inger 58 a~ well ns the socket 264 which
may be cast onto the centre mold. As shown in Figure~ 25 ~nd
26, flnger 58 ocnsists of an upper body member 316 terminating
in a 6quare, diamond shape thpered end 318. Body 318 has
a lower socket 320 for ~he reception of plug 322 which $8
detachably secure~ to the cable 314 by a set screw 324. Plug
- 22 -
376
322 locatec the body of the finger on the cable which i8
attached thereto by end retainers 326. ~t will be Iseen from
Figure 25 that there :L8 ~uf~lcient clearance proviaed between
the interior socket of the flnger ~nd the plug 322 to provide
for ~inger movement. The c~ble 314 is also provided with
plurality of links 328 which are mov~bly secured to the cable
by set screws 330, each end of the link 32B having a t~pered
bore 332 to allow for flexibllity in cable movement when
training the links Around the sprockets of the mechani~
It will al~o be noted from the full view of the finger
58 in the right-hand portion of Figure 25 that the body me~er
316 has flat portions providing lower and upper tr~ck engaging
shoulders 334 and 336 respectively, the function of which will
~ubsequently be described.
The sprockets 298 ~nd 300 ~re rotat~bly mounted w~thin
side pl~tes 338 which in turn are interconnected to the 6ide
rail6 306 by connecting pl~tes 340 80 that the plates 338 and
side rail~ 306 are oo-pl~nar ~nd co-extensive with respect to
one another. Additionally, the ~ide rail6 306 support sp~cea
track ~e~Dbers 342 as shown in Figure 26 ~nd which support the
finger 58 and ~pecifically the shoulders 334 thereof. It will
be noted that the track members 342 are spaced to receive the
~ide ~urfaces 335 of fingers 58 as shown in the right hand side
of Figure 25 ~nd Flgure 26. Moreover, the 6prockets al60
lnclude an arcuate me~er 3~4 which is co-extensive with the
trnck member 342 on the r~ils 306 80 that the finger S8 and
~pacers 328 i~ continuous both in the ~ ight ~ections and
arous~d curves 60 IIE; not to pre~ent any shear points or wedge
entrles where debris c:ould be tr~pped ~nd ~top the indexing
movement.
It will al80 be seen from the bottom portion of Figure
22 th~t on it~ ret~rn run, the cable 314 carrie~ the figure 58
23 --
~i~9376
along the lower run 312 where the upper shoulder6 336 of the
finger engage track member~ 342.
It will al60 be noted from the upper left hand portion
of Figure 22 that sprocket 300 ha6 6paced indentations 346
to receive and drive the spacer6 32B ~nd further ~ndent~tions
348 which are provided with contours to receive an~ drive the
lower shapes of the fingers 58.
A~ seen in Figure 26, rail 306 i8 seoured to the frame
12 of the die casting machine by means of a plate 350 ~nd cap
screws 352.
Looking now at Figure 23, the finger 58a whi~h would
carry a cast part is indexed along the upper run 308 of the
track to its position at a trimming mechanism as ~hown generally
at 354 and after the trimming operation, the cable 314 draws
the finger over sprocket 302 onto track 310. Track 310 together
with the sprocket 302 which it carrie~ i~ pivoted about the
centre of lower sprocket 304 and track 310 (which i6 ~n effect
a long arm) i~ used as a fulcrum ~bGut the centre of .procket
304 to maintain the cable 314 in proper ~enslon through the
action of a spring tensioning member 356 which iB connected at
one end 358 to the arm 310 and at its other end 360 to the
frame 296 of the tr~nsfer mechanism. ~ take-up spring 362
applie6 outward pres~ure on the arm 310 which is allowed to
pivot about the centre of a sprocket 304 through the slidable
~onnectlon between ~he upper portion 364 of the arm between
fiide plate6 366 secured to the upper track 308. The constant
lo~d on the cable 314 ~l~o ~erve~ to maintain ~ const~nt
overall length to the ~able in re3pect to its ela~tlc stretch
properties and any mlnor dlferences in position of the fingers
SB from one to ~nother ~re ~b~orbed by the purposeful loo~eness
of those f~ngers p~UB or minu~ of the position of lts fixed
attachment to the cn~le a6 shown ln the relationship to lts
- 24 -
76
mounting ~n Figure 25.
As the finger 58a iB dr~wn along arm 310 with the
frame sf the cast~ng remain~ng after~the trimming operation,
it reaches a klcker station 368 where the part-shot frame is
kicked off the carrier finger 58 onto a belt conveyor (not
shown) for return to thé casting metal meiting pot.
The kicking station 6hown ~n cross ~ection in Figure
27 includes a palr of slippers 370 mounted on either side of
the track or arm 310 and which are connected by bolts 372
acting in slideways 374 with ~ plate 376 connected to a linear
actuator 380. As geen in Figure 24, finger 58 with the
remainder of the casting frame is drawn downwardly between the
confine~ of the ~rcuate end~ 382 of the slippers 380 which
effectively lie under ears 384 on the casting as ~hown in Figure
30. When finger 58 and the casting frame reaches the position
of Figure 27 by indexing, the linear actuator 380 iE activated
which moves the plate 376, bolts 372 and slippers 370 outwardly
(to the left ~n Figure 23 or Figure 27~ thereby kicklng off the
remainder of the cast on part which will drop down onto the
oonveyor and be returned to the melting pot. The finger 58 then
return~ to the casting end of the transfer mechanism along the
lower run of tr~ck 312 as shown in Figure ~3.
TRIMMING MACRINE
_
Referrlng to Figures 2B ~nd 29, the trimming machine
354 provides ~ locatlon midway between the two platen~ for
6upport of the tr~nsfer conveyor track 30B which csrries the
part6 to the trlm die and on through as reguired. In effect,
a8 ~hown ln Flgure 2a the tr~mming m2chine straddles the
conveyor 308 and finger 58 and the part that ~t carrles.
The concept of the trimming machine features two moving
platens 386 ~n~ 388 ~hich c~rry the trim di~ 390 that i8
c~rried on pl~ten 386 and a trim punch 392 that i8 c~rried by
- 25 -
~1~9~7~
platen 388. The two platens adv~nce towards one another to
close about the stationary, pre-positioned castlng 394 within
the carrier frame. The timing of the two ~ovements i`~ such
that t;he die 390 reaches its final po~it~on while the punch
392 i~l still advancing and accordingly it acts as a back-up
to the preliminary advance of final-position loc~tors
396 ~ust before the punch encounter~ the part to shear
it frcm the carrier frame.
The trim machine 354 i8 a two tie ~ar type with
upper and lower prestressed bars 398 and 400 mounted wlthin
tubular compression members 402, 404 to provide ~ubstantial
rigidity. A8 Been in Figure 29, bars 398 and 400 ~re tilted
off a vertical ~ine to facilitate loading o~ the die while
suspended from an overhead lift. A pnir of ~hort ~troke
hydraulic shock ab~orberk 406, 408 are positioned in 180
opposite to one another and on a plane of the machine centre
line and serve to absorb the unloading ~hock when the punch
392 breaks through the sheared ~ection of the part.
One form of the trimming machine utili~es a 6$ngle
hydraulic cylinder 410 and 412 driving each of the platen~ 388
ana 386 respectively along the centre line of the machine axis.
Another form of the m~chine features hydraulic cylinders 414
and 416 which operate ~8 an integral part of t~e platen bearing
~upports which permits having an open aperture through the die
platen for automatlc xe~e~pt of the part as it i~ pu6hed
through the die in ~ sub~equent transfer.
The punch 392 and die 390 are self-al$gnlng.
Referring to Flguse 30, n cast part 394 ha6 8 pair of
apertures 420 therein and peripheral flash 422. The part
is ~arried by finger 58 in~o trlmmlng ~pparatus 3~ sho~n
in Figure 28. The die 390, a6 sho~n in Flgure 32, has a
- 26 -
~1~9376
peripheral coll~r 424 which surrounds the part and supports ~t
behin~ the flash.
Die 390 i6 secured to the platen 386 by a pa~r of
cap sc~rews 426 and ~pring washers 428. While only one cap
s~rew is 6hown $n F~gure 32, n pair of the~e ~crews are provided
and are located diagonally from one another. The ~ie 390
h~s a bore 430 for each cap screw 426, the di2meter of the bore
being slightly ~arger than the body of the cap 6crew to thereby
allow limited movement of the die 390 on its mounting beneath
the spring washers 42~.
As shown in Figures 31 and 32, punch 392 i~ ~imilarly
mounted to a riser 432 by cap screws 434 and spring wa~hers
436, the bore 436 being slightly larger than the diameter of the
cap screws 434 to allow movement of the punch 392 on its
mounting. ~he punch 392 and die 390 can therefore ~float~ on
their mountings nnd with respect to one ~nother.
Punch 392 is provided with a pair of diagonally
positioned locator pins 396 for engagement in apertures 438
of the die 39~ ~nd platen 386. Punch 392 Also includes a
second pair of locating pins 440 whi~h correspond to the
apertures 420 in the part 394.
In operation, the conveyor 308 and flnger S8 oarry
part 394 to its Figure 28 position. The die 390 i~ advanced to
its Figure 32 posltion to ~upport the part, the floating die
adjusting to ~ts position on the part in response to the
contour~ thereof. The punch 392 $8 then advanced toward the
die 390 nd part 394, the apertures 420 in the part receiving
the pins 440 of the punch and effecting align~ng ~ovement of
the punch on its c~p ~crew6 434 80 that, a~ the punch and ~ie
clo6e, locatorG 396 will be rece$ved ln apertures 438.
- 27 -
9 37 ~
While the invention has been descrlbed in connection
with a specific embodiment thereof and ~n a ~pecific use,
various modifications thereof will occur to those ~killed
in the art without departing from the 8pirit and scope of the
invention as set forth in the appended claims. I
The terms and expressions employed in this
disclosure are used as terms of description nnd not of
limitation and there i~ no intention in their use to exclude
any equivalents of the features shown and described or
portions thereof, but it is recognized that various modifications
are possible within ~he scope of the invention cla~med.
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