Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a hot chamber pressure
die casting machine of the type, hereinafter referred to as
the type described, comprising a reservoir for molten metal,
a gooseneck, one end of which is adapted to be immersed in the
molten metal and the other end of which provides a nozzle
having an end surface adapted to be brought into engagement
with a back surface of a die set from which a feed passage
extends to a die cavity defined by the die set and into which
a shot of molten metal is injected by a pump in the gooseneck,
the die set being mounted on a back plate and comprising a
plurality of dies movably mounted on the back plate between a
closed position in which the die cavity is defined and an
open position in which an article cast within the cavity can
be ejected.
An object of the invention is to provide a new and
improved die casting machine of the type described.
According to the present invention we provide a
die casting machine of the type described wherein the back
plate is provided with a track along which a die closure means
is adjustable.
The machine may include a plurality of adjustable
die closure means and the track may comprise a single die
closure means and the track may comprise a single circular
track lying in the plane of the back plate.
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Hitherto a separate back plate for each die set
to be used with the machine has been required, or, the back
plate has been provided with a predetermined number of
locations at which the dies of a limited number of die sets
can be located. Thus, it has not been convenient to change the
die sets where different numbers of dies and or different
directions of movement of the dies has been required. The
present invention overcomes these problems since one, more than
one, or all, of the die closure means may be made adjustable
along a track of the desired extent and preferably all the die
closure means are mounted on a continuous circular track so
that they can be orientated in any desired angular position
around the back plate.
Preferably the die closure means is operable to
reciprocate the die between the open and closed position by
a linkage from a drive means, the axes of pivot of the linkage
lying in a plane parallel to the plane of the back plate and
the drive means may comprise a fluid operated piston and
cylinder device.
By providing that the linkage and drive means of
the die closure means are orientated in this fashion the
area covered by these means in the plane of the back plate is
minimised thus permitting closer proximity between adjacent
die closure means than has hitherto been possible since
conveniently the axes of the linkage have been in a plane
normal to the plane of the back-plate.
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As a result a core member for the die set may be
provided with a closure means between one or more pairs of
dies.
Clamping means may be provided to permit of securing
the die closure means in a desiredposition along the track.
Although a single continuous circular track is
preferred if desired separate tracks may be provided for each
or for only one or more than one of the closure means and
the tracks may extend in any desired direction.
Although in the preferred embodiment the back plate
lies in a vertical plane the present invention may be applied
to a die casting machine in which the back plate does not lie
in a vertical plane.
According to a broad aspect, the invention relates
in a pressure die casting machine comprising a back plate, a
reservoir for molten metal, at least one gooseneck, one end
of which is adapted to be immersed in the molten metal and
the other end of which terminates in a nozzle having an end
surface adapted to be brought into engagement with a back surface
of a die set from which a feed passage extends to a die
cavity defined by the die set, said gooseneck further having a
passage communicating said one end with said other end and
pump means for drawing molten metal into said gooseneck through
said one end with said other end and pump means for drawing
molten metal into said gooseneck through said one end and
injecting same being movably mounted on said back plate between
a closed position in which the die cavity is defined and an
open position in which an a~ticle cast within the cabity can
be ejected, the improvement comprising adjustable
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closure means for said die, and a track on said back plate,
said closure means being adjustable along said track.
One example of the invention will now be described
with reference to the accompanying drawings wherein:-
FIGURE 1 is a front elevation of a die casting machineembodying the invention,
FIGURE 2 is a side elevation of the machine of
Figure 1 looking in the direction of the arrow A in Figure 1,
FIGURE 3 is a section on the line 3-3 of Figure 2,
FIGURE 4 is a plan view of the machine of Figure 1,
FIGURE 5 is a fragmentary longitudinal cross-
sectional veiw, to an enlarged scale, through the gooseneck
nozzle of the machine of Figure 1,
FIGURE 6 is a fragmentary longitudinal cross-
sectional view~ to an enlarged scale, through the gooseneck
closure means of the machine of Figure 1,
FIGURE 7 is a section on the line 7-7 of Figure
2, and
FIGURE 8 is a section on the line 8-8 or Figure 1.
1.
Referring to the drawings a die casting machine for
producing pressure die castings of zinc is illustrated
generally at 10 and comprises a base part 11 which carries a
crucible 12 which in use contains molten zinc and thus
provides a reservoir for the zinc. The base part 11 also
carries a circular back plate 13 having a central opening
14 through which a nozzle 15 of a gooseneck 16 projects
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so that an end surface 17 of the nozzle 15 can be engaged
with a back surface 18 of a die set indicated generally at
19 in Figure 5 so as to be in metal transmitting relationship
with a feed passage 20 which extends from the back surface 18
to a cavity defined by the dle set.
The die set 19 comprises four dies mounted in die
carriers 21 mounted on the back plate 13 so as to be slidable
in the plane of the back plate at 90 to each other by means
of die closing means indicated generally at 22.
Referring now particularly to Figure 3 the gooseneck
16 is mounted for pivotal movement about an axis 23 so as to
move the end surface 17 of the gooseneck nozzle 15 into and out
of engagement with the back surface 18 of the die set. This
movement is caused by a drive means 24 connected to the
gooseneck through a toggle mechanism 25.
The gooseneck 16 is mounted on the base part 11 by
means of an axle member 26 having end bearing portions which
are received in bearing apertures 27 formed in brackets 28
conencted to arms 29 which are themselves carried at the upper
ends of threaded rods 30. The rods 30 are mounted on the base
part 11 and the arrangement is such that rotation of a rod
permits vertical adjustment of the bracket 28 connected thereto
and thereby permits adjustment of the position of the end
surface 17 of the nozzle 15 relative to the back surface 18 of
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the die set.
The gooseneck 16 contains, within the part 31,
thereof a conventional pump arrangement whereby molten zinc
contained within the crucible 12 is drawn from the crucible
into the interior of the gooseneck and is then injected in
the die cavity through the feed passage 20 by means of an
internal passage 32 formed in the gooseneck and a passage 33
fromed in the nozzle 15. The major length of the passage 33
in the gooseneck i.e. the part indicated at 34 extends in a
horizontal direction when the end surface 17 and back surface
18 are in engagement as shown in Figure 5. A minor part 35
of the passage extends from the outer end of the major part 34
to the end surface 17 in a direction which is inclined
upwardly from the path 34 to the end surface 17. at angle of
25.
This is done to avoid molten zinc dribbling from the
end surface 17 when the gooseneck is withdrawn out of contact
with the back surface 18 which would otherwise be the case.
The arrangement is such that the part 34 of the passage full of
molten metal is nevertheless below the bottom of the aperture
in the end surface 17.
By providing that the major part 34 of the passage
33 extends in a horizontal direction then the general extent
of the nozzle can also lie horizontally and the end surface 36
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can lie in a vertical plane thereby permitting the fitting
of a conventional electrical heating jacket 37 to the nozzle
without interference with the die set 19 or back plate 13.
It will be appreciated that the precise angle of
the minor part 35 and the relative extent of the parts 34 and
35 may be varied from that described hereinbefore whilst still
achieving the objects described hereinbefore.
Referring to Figures 3 and 4 the gooseneck 16 is
pivoted into and out of engagement with the die set about the
axis 23 by means of a pneumatic piston and cylinder device 38
the cylinder of which is connected to the base part 11 of the
apparatus whilst the piston rod of which is pivotally connected,
at 39, to a toggle mechanism 25 which comprises a first link
40 one end of which is solidly connected, at 41, to a rod 42
connected to the gooseneck 16 whilst the other end is connected
to the piston rod at 39 and a second pair of links 43 one end of
which is pivotally connected at 44 to the base part 11 of the
apparatus through an air spring 45 and the other end of which is
connected to first link at 40.
Referring now particularly to Figure 6 the links 43
are connected, at 44 to a piston rod 46 of the air spring 45
which extends through a nose part 47 of the cylinder 48 of the
air spring. The piston rod 46 has a shoulder 49 with which a
washer 50 is engaged. Slidably mounted on a reduced diameter
part 51 of the piston rod 46 is a piston 52 having a boss 53
apertured to receive the part 51 and extending through a rear
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wall 54 of the cylinder 48. Conventional O-ring seals 55 are
provided between the wall 54 and the boss 53 and between
the wall of the passage in the boss 53 and the reduced
diameter part 51. Air under pressure is fed via a connector
56, axial passage 57, radial passages 58 and circumferential
groove 59 in the part 51 of the piston rod 46 and a radial
passage 60 in the boss 53 to the region 61 so as to act on one
side 62 of the piston 52 and via a bleed aperture 63 to act
on a reduced area part 64 of the other side 65 of the piston 52.
An exhaust passage 66 extends from the interior of
the cylinder 48 adjacent the washer 49 to atmosphere. A
microswitch 67 is mounted on a bracket 68 fixed to the end of
the piston rod 46 and the operating member 69 of which is
adapted to engage a surface 70 of the cylinder 48.
In use, when it is desired to move the end surface
17 of the gooseneck nozzle 15 into metal transferring
relationship with the back surface 18 of the die set 19 the
pneumatic piston and cylinder device 38 is actuated to move
the piston rod thereof outwardly of the cylinder so as to tend
to move the links 40 and 43 into axial alignment thereby moving
the rod 42 to the left in Figure 3 and thus pivoting the
gooseneck 16 about the axis 23. When the end surface 17
engages the back surface 18 so that the movement of the
gooseneck 16 is prevénted then whilst movement of the piston
rod of the device 38 continues this causes only movement of
the piston rod 46 of the air spring 45 to.the left in Figure 6
thus engaging the washer 50 with the piston 52 to move the
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piston 52 to the left. This has two effects~ One effect
is to cause the plunger 69 to operate the microswitch so that
it sends a signal to a control mechanism of the machine to
permit the pump in the gooseneck to operat.e to feed a shot
of metal since movement of the piston rod 46 to the left will
have meant that the surfaces 17 and 18 are in metal transferring
relationship. The second thing which happens is that the air
acting on the reduced cross sectional area part 64 of the piston
62 is pe.rmitted to move past an ~-ring seal 71 and hence be
exhausted to atmosphere through the exhaust passage 66. As
a result the whole of the side 65 of the piston will be subjected
to only atmosphere pressure whilst the whole of the side 62
will be subjected to air under pressure fed via the connector
56 and passages 57, 58, groove 59 and passage 60. As a result
whilst the piston and cylinder device 38 is permitted to carry
out its full stroke since the piston 52 can move to the left
against the pressure of the air acting in the region 61 the
force exerted by the drive means on the gooseneck is increased,
once contact between the surfaces 17 and 18 has taken place,
due to the air acting on the piston 52 as described hereinbefore
and also the pressure pressing the surface 17 and 18 into
contact can be maintained constant irrespective of any variation
in the dimensions between the gooseneck and the connection
of the toggle mechanism to the base 11 since the pressure is
determined by the force exerted by the air on the piston 52.
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As best shown in Figures 1 and 3 the back plate 13
is provided with a continuous circular track 72 the centre
of the track being the centre of the opening of the passage
part 35 in the end surface 17. Mounted in the track 72 are
four die closure means 22. In Figures 1 and 2 onl~ one
closure means is shown in its entirety the other three being
shown schematically but they are, in fact, identical to that
shown in detail. Each die closure means comprises a pneumatic
piston and cylinder device 73 pivotally mounted at 74 on a
bracket 75 fixed to a shoe 76 engaged with the track 72 and
provided with means such as clamping bolts to clamp it in a
desired position circumferentially of the track. The piston
rod 73a of the device 73 is pivotally connected at 77 to one
end of a first link 78 of a toggle mechanism, the other end of
the link 78 being connected at 79 to a die. A pair of second
links 80 are connected at 81 intermediate the points 77 and 79
to the first link 78 and at 82 to an adjustment member 83
having a threaded rod 84 in threaded engagement with
an adjustment member 85 which abuts the end of a housing 86
so that rotation of the member 85 moves the rod 84 axially and
hence the pivot 82 so that the closure position of the die can
be adjusted.
The dies are mounted for sliding movement in a cross
head 87. It will be appreciated that the position of the die
closure means can be easily and conveniently adjusted to suit
any particular die head which is clamped to the backing plate
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in conventional manner merely by moving the shoes 76 circumferen-
tially of the track to the desired position. Also, if desired,
additional closure means may be provided intermediate the
four described hereinbefore; also a closure means may be
provided for one or more core members which may be required wlth
any particular die set.
If desired the track or tracks can be provided on a
member separate from the remainder of the back plate and
fixed thereto.
