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 deEined by the die set and into which
a shot of molten metal is injected by a pump in the gooseneck,
10 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.
In order to facilitate ejection of a cast article on
the die set when the dies are in their open position we desire
that the back plate should lie in or near (i.e. within 25
and preferably within 10 or 5) of a vertical plane. However
we have found that if we adopt a vertical or near vertical
20 back plate, which results in the back surface of the dies
from which the feed passage extends also lying in or near a
vertical plane, with a gooseneck having a nozzle in which
the passage for metal, adjacent the die set engaging end
surface, extends in or near a horizontal plane then metal
25 tends to run out of the nozzle passage at the end surface
when the end surface is moved out of engagement with the die
set.
It is accordingly an object of the invention to provide
a die casting machine of the type described from which cast
30 articles can be easily ejected and in which the above-
mentioned problem of metal dribble- is overcome or is reduced.
According to the invention we provide a die casting
machine of the type described wherein the back plate lies in
or near a vertical plane and the gooseneck nozzle has a
35 passage, part of which lies in or near a horizontal plane,
when the nozzle end surface is engaged with the back~surface
of the die set, and an end portion which is incline~ upwardly
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from the major part to the end surface of the nozzle.
This arrangement avoids metal dribbling out of the
nozzle when the nozzle end surface is moved out of engagement
of the back surface of the die set and also permits the
provision of nozzle heating means including a conventional
electrical heating jacket which is relatively bulky and
which could not be provided if the whole of the nozzle were
to be inclined upwardly.
One embodiment of the invention will now be described
in more detail by way of example with reference to the
accompanying drawings wherein:
Figure 1 is a front elevation of a die casting machine
embodying 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
view, to an enlarged scale, thxough the goose-neck nozzle
of the machine of Figure 1,
Figure 6 is a fragmentary longitudinal cross sectional
view, to an enlarged scale, through the goose-neck 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 of Figure 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 ll also
carries a circular back plate 13 having a central opening
14 through which a nozzle 15 of a gooseneck 16 projects
so that an end surface 17 of the nozxle 15 can be engaged
with a back suxface 18 of a die set indicated generally at
19 in Figure 5 so as to be in metal transmitting relation-
~ ship with a feed passage 20 which extends from the back
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surface 18 to a cavity defined by the die set. In the
example illustrated the back plate lies in a vertical plane
but may lie in other planes. For example the invention
claimed in claim 1 of this application can be utilized when
the back plate is inclined to the vertical at up to 25.
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. If desired
the dies may be slidable in directions other than 90.
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
connected to arms 29 which are themselves carried at the
upper ends of threaded rods 30. The rods 30 are mounted
on the back plate 13 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 the die set.
The gooseneck 16 contains 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 formed in the nozzle lS~ 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
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in a direction which is inclined upwardly from the path 34
to the end surface 17 at angle of 25. When the back plate
is inclined to the vertical the major part 34 may also be
inclined to the horizontal, for example, by an angle equal
S to the inclination of the back plate to the vertical.
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 could otherwise be the
case. The arrangement is such that the injection pump
closes the passage 32 before the nozzle is withdrawn from the
back of the die thereby preventing metal drawing back and
keeping 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 can lie in a vetical 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 ri~idly 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 pair
of second links 43 one end of which are pivotally connected
at 44 to the base part 11 of the apparatus through an air
spring 45 and the other ends of which are connected to the
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~L43~a
piston rod at 39.
Referring now particularly to Figure 6 the link 43 is
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. Rotatably 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 41 and
extending through a rear wall 54 of the cylinder 48. Conven-
tional 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 micro-
switch 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 relation
ship 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
t~e 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 prevented 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 piston 52 to the left. This has two effects. One effect
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is that the air acting on the reduced cross sectional area
part 64 of the piston 62 is permitted to move past an O-ring
seal 71 and hence to be exhausted to atmosphere through the
exhaust passage 66. As a result the wholeof the side 65 of
the piston will be subjected to o:nly atmospheric 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 herein-
before 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 Il since the
pressure is determined by the force exerted by the air on the
piston 52.
The second thing which happens is that to cause the
plunger 69 to operate the micro-switch so that it sends a
signal to a control mechanism of the machine to permit the
pump in the gooseneck to operate 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.
As best shown in Figures 1 and 3 the back plate 13 is
provided with a continuous circular track 72 the centre of
3~ 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 only one
closure means is shown in its entirety the other three being
shown schematically but they are, in fact, identical to that
shown in detai:L. 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
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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 86so 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 in conventional manner merely by moving the
shoes 76 circumferentially of the track to the desired
position. Also, if desired, addition~l closure means
may be provided intermediate the four described hereinbefore;
also a closure means may be provided for one or more core
members wnich may be required with 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.
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