FIELD OF THE INVENTION
5 The invention relates to knocking out clusters of
lost-pattern metal castings.
TECHNOLOGICAL BACKGROUND
The lost-pattern (or lost wax) casting method is a
10 well-known casting method that is used in particular for
fabricating turbine blades, in particular for
aeroengines, in particular gas turbine engines. By way
of example, the method is described in Document
15
20
wo 2014/049223.
When performing that casting method to fabricate a
cluster of castings, a cluster of castings is obtained
that is formed in an "investment" or shell. This shell
is typically made of ceramic. It is referred to herein
either as a "shell" or as a "shell mold".
In order to finalize fabrication of castings, it is
therefore necessary to extract them: this operation is
known as "knocking out".
Traditionally, knocking out is performed by knocking
against the shell with a hammer so as to break it and
25 detach it from the cluster of castings.
That technique nevertheless suffers from two
drawbacks: firstly, it is tedious and tiring for the
operators performing those operations; and secondly it
can lead to mechanical stresses in the castings. During
30 subsequent heat treatment, such mechanical stresses can
give rise to the appearance of metallurgical defects
known as ''recrystallized grains". Such grains of
recrystallized metal are zones of weakness that reduce
the lifetime of the parts that are obtained and that can
35 lead to them being rejected.
2
SUMMARY OF THE INVENTION
The object of the invention is to propose a knockout
method for clusters of lost-pattern metal castings, in
which the two above-mentioned drawbacks are eliminated,
5 or at least reduced.
According to the invention, this object is achieved
by a knockout method for knocking out a cluster of lostpattern
metal castings, the cluster of castings being
formed in a shell, wherein at least one knife is moved by
10 means of a machine without making contact with the
cluster in such a manner that the knife engages the
shell, breaks it into a plurality of fragments, and
detaches at least a portion of the shell from the
cluster. The term "knife" is used to mean a tool surface
15 designed to engage an external body, and in particular in
the present situation the shell of the cluster.
Below, in order to simplify explanation, the
description refers to "a" knife; nevertheless, it should
be understood that the explanations also cover the
20 situation in which the method is performed with a
plurality of knockout knives.
In the method of the invention described above, the
movement of the knife (or knives) for knocking out the
cluster of castings preferably takes place at a speed
25 that is slow; for example a speed of less than 0.2 meters
per second (m/s) or indeed less than 0.05 m/s. This thus
reduces the impact between the knife and the shell and
reduces the risk of the castings being degraded.
Optionally, the invention may be performed without
30 any impact against the shell; that is to say on first
contact between the knife (or knives) and the shell, the
speed of the knives is practically zero.
Conversely, in another implementation, the knockout
knife (or knives) may move without stopping. The travel
35 speed of the knife (or knives) may for example be
substantially constant.
3
Advantageously, in the absence of impact at high
speed between the knife and the shell, there is no
formation of stress starters where recrystallized grains
might appear during heat treatment applied to the
5 castings.
The method is performed by means of a machine in
order to ensure that the knife (or knives) move(s) under
the specified conditions (in particular no contact with
the cluster in the vicinity of the castings). The
10 machine advantageously avoids the tiring operation of
knocking out clusters with a hammer.
The effectiveness of the method results from the
fact that the shell formed around the castings is a
fragile part with relatively little adhesion to the
15 castings constituting the cluster. Also advantageously,
even if the knife (or knives) of the tooling do not make
contact with all of the portions of the shell (far from
it), by engaging certain projecting portions or
"protuberances" of the shell they succeed in breaking the
20 shell almost completely, thereby knocking out the
castings.
25
The projecting portions or protuberances via which
the shell mold is broken may for example be formed around
a heat shield provided in the shell mold.
Such a heat shield serves to improve the cooling of
the cluster during and after casting (an example of a
heat shield is described in Document FR 2 874 340). It
serves in particular to keep the solidification front as
horizontal as possible (i.e. to keep the solid/liquid
30 interface during cooling of the cluster of castings in
the mold as horizontal as possible).
Since the knife (or knives) engage(s) the
protuberances of the shell mold, and only its
protuberances (excluding the cluster itself), there is
35 therefore no need for the knife to come close to the
castings that are to be knocked out. On the contrary, in
order to reduce the mechanical stresses applied to the
4
surfaces of the castings to as little as possible, it is
even preferable for the movement of the knife and its
contact with the shell to take place at a certain
distance away from the castings.
5 Because of these relatively easy requirements, the
method of the invention may advantageously be performed
with a knife (or knives) and/or with movements of the
knife (or knives) that are extremely simple.
Thus, as mentioned above, the speed of the knife may
10 optionally be constant.
Advantageously, in an implementation of the method,
the movement of said at least one knife for knocking out
the cluster of castings is constituted solely by a
movement in translation. This movement may in particular
15 be carried out in a direction parallel to the axis of the
cluster (the casting axis, or axis of symmetry of the
cluster) This axis generally extends vertically while
the cluster is being cast.
Nevertheless, in other implementations of the
20 invention, this movement of said at least one knife may
equally well comprise movement that is not parallel to
the axis of the cluster, e.g. a movement in rotation. It
may thus optionally be constituted solely by a movement
in rotation.
25 More generally, the movement may be any kind of
movement, as a function of the capabilities of the
machine on which the knife is fastened (number of degrees
of freedom and number of axes), and as a function of the
shape of the cluster.
30 In an implementation, the movement of said at least
one knife comprises passing between every pair of
adjacent castings among said castings. Specifically, for
a pair of adjacent castings, passing a knife between the
two castings of the pair of adjacent castings makes it
35 possible to ensure that the portion of the shell
potentially connecting together these castings is broken,
5
thereby facilitating separation of the shell from the
cluster.
In particular, when the parts of the cluster are
distributed around a casting axis, the parts are arranged
5 in a circle around the casting axis. They are then
adjacent in pairs around the circumference of said
circle.
In an implementation, said at least one knife is
constituted by a plurality of knives, and during the
10 movement of said plurality of knives, all of said knives
come into contact with the shell at substantially the
same time. This makes it possible to detach the shell
more effectively from the cluster.
In addition, the invention also provides a method of
15 fabricating castings, the method comprising the following
steps: fabricating a cluster of lost-pattern castings,
the cluster of castings being formed in a shell, then
knocking out at least a portion of the shell by the
above-defined method of knocking out a cluster of
20 castings.
In addition, the invention also provides a knockout
machine for knocking out a cluster of lost-pattern
castings, the cluster of castings being formed in a
shell, the machine comprising:
25 a frame having means for rigidly fastening the shell
to the frame;
at least one knife; and
at least one actuator suitable for moving said at
least one knife relative to the frame in a space provided
30 for fastening the cluster.
35
Preferably, the actuator is designed to move said at
least one knife relative to the frame in the space
provided for fastening the cluster at a speed of less
than 0.2 m/s, or indeed less than 0.05 m/s.
The machine may be a relatively simple press.
The actuator(s) may include an actuator suitable for
moving at least one blade for knocking out the cluster of
6
castings solely by a movement in translation or solely by
a movement in rotation.
The actuator(s} may in particular comprise a jack.
The jack can move said at least one knife, in particular
5 in translation.
Said at least one knife is preferably not rotatable
(i.e. it is not a drill bit nor a milling cutter}.
In an embodiment, said at least one knife is
constituted by a plurality of knives incorporated in a
10 single tool.
The knives may also be rigidly fastened to one
another within the tool.
In particular, they may extend in directions that
are substantially perpendicular to the travel direction
15 of the tool.
In particular, they may occupy a common plane.
In particular, they may be elongate and formed on
portions of a tool, e.g. in the form of fingers, that are
directed in directions that are radial relative to the
20 center of the tool.
The machine is designed for knocking out a cluster
of castings formed in a shell.
Consequently, the actuator(s} is/are designed, as a
function of the configuration of the cluster, so as to
25 move the knife (or knives} without impact relative to the
cluster and without contact with the blades in order to
separate at least a portion of the shell from the
cluster.
Consequently, the invention also provides an
30 assembly comprising a knockout machine as defined above
and a cluster of lost-pattern castings, the cluster of
castings being formed in a shell; the knockout machine is
suitable for enabling said cluster to be fastened to the
frame; and said at least one actuator is suitable, when
35 the cluster is fastened to the frame, for moving said at
least one knife relative to the cluster and without
making contact with the cluster in such a manner that
7
said at least one knife engages the shell, it breaks the
shell into a plurality of fragments, and detaches at
least a portion of the shell from the cluster.
In an embodiment, the shell includes at least one
5 protuberance in the vicinity of each casting of the
cluster, and said at least one knife engages the
protuberance during said movement. This or these
protuberances constitute one or more portions of the
shell that do not contain any portions of the cluster;
10 thus, the knife (or knives) can engage the
protuberance(s) without any risk of striking the cluster.
15
The or each protuberance preferably lies at least
6 millimeters (mm) and preferably at least 8 mm from the
casting in the vicinity of which it is located.
In an embodiment, at least one of the protuberances
surrounds at least one of the castings of the cluster
over 360° when seen looking along the axis of the
cluster. The protuberance may in particular be a heat
shield serving to improve the cooling of the cluster
20 during casting and cooling of the metal.
In an embodiment, said protuberances are arranged
substantially in a plane.
In an embodiment, at least some of the protuberances
are formed around or from a part in the form of a plate
25 perforated by holes.
This part is usually designed to form a heat shield.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention can be well understood and its
30 advantages appear better on reading the following
detailed description of embodiments given as non-limiting
examples. The description refers to the accompanying
drawings, in which:
- Figure 1 is a diagram of the steps of a method of
35 the invention for fabricating parts by lost-pattern
casting;
8
Figure 2 is a diagram of a wax core suitable for
use in performing the Figure 1 method for fabricating
blades;
- Figure 3 is a side view of a shell mold and of
5 tooling used in the Figure 1 method of fabricating
blades;
- Figure 4 is a diagrammatic perspective view of a
knockout machine in a first embodiment of the invention,
used for performing the method shown in Figures 1 to 3;
10 - Figure SA is a half-view in axial section of the
15
shell mold and of the tooling shown in Figure 3;
Figure 58 shows a detail of Figure 5A;
- Figure 6 is a perspective view of the tooling used
in the method shown in Figures 1 to 58;
- Figure 7A is an axial section showing a detail of
a shell mold containing a casting cluster, together with
the tooling of a knockout machine in a second embodiment
of the invention;
Figure 78 is a cross-section of the tooling shown
20 in part in Figure 7A; and
25
- Figure 7C is a diagrammatic axial section of the
knockout machine shown in Figures 7A and 78.
DETAILED DESCRIPTION OF THE INVENTION
An example of a knockout machine and method in a
first implementation of the invention is described with
reference to Figures 1 to 5. The knockout machine and
method are described in the context of a method in
accordance with the invention for fabricating blades.
30 The blade fabrication method described is a lostpattern
casting method (Figure 1).
The first step Sl of the method consists in
fabricating a cluster pattern 21 out of wax (Figure 2),
also referred to as a ''non-permanent cluster''.
35 Thereafter, a shell mold 1 is made around the wax cluster
pattern, in conventional manner.
9
The cluster pattern 21 comprises a plurality of
blade patterns 22 connected together by auxiliary
portions 23. These auxiliary portions 23 include two
additional parts 14 of disk shape, both made of wax.
5 Each of these additional parts 14 is in the form of a
plate pierced by holes through which the blade patterns
22 pass.
The blade patterns 22 are all identical with one
another. They are arranged in a circle in axisymmetric
10 manner around an axis X, referred to as the casting axis.
15
20
The axis X is arranged in a vertical direction during the
casting operation when molten metal is cast into the
shell mold 1 (an operation that is described in greater
detail below) .
The blade patterns 22 are arranged parallel to the
axis X.
During fabrication of the shell mold 1 (Figure 2):
- the blade patterns 22 are used to form mold
cavities 7 for molding blades 32;
- the additional parts 14 serve to provide a top
heat shield 13 and a bottom heat shield 13'; and
- the other functional parts 23 serve in particular
to provide a pouring bush 5, feed channels 8, stiffeners
20, and selectors 9.
25 In a second step S2, the shell mold 1 is made
starting with the wax cluster 21 (this step is described
in greater detail in Document WO 2014/049223). While
making the shell, two additional shell portions are
obtained directly from the additional parts 14 added to
30 the cluster pattern 21.
The last operation of step S2 consists in
eliminating the wax of the cluster pattern from the mold.
The wax is eliminated by placing the shell mold in an
autoclave mold (or the like) and raising it to a
35 temperature higher than the melting temperature of the
wax.
10
After this operation of eliminating the wax, the
additional shell portions define cavities referred to
herein as "additional'' cavities.
Two implementations may be envisaged: either the
5 original cavities are in communication with the main
cavity comprising the feed tree connected to the cavities
formed by the blade patterns 22 (before eliminating the
wax), or else the additional cavities are not in
communication with the main cavity.
10 In a third step S3, the cluster 30 of blades 32 is
formed in the shell mold 1 by casting molten metal into
the shell mold 1.
The result of the casting differs depending on
whether or not the additional cavities are connected to
15 the main cavity:
In a first implementation, the additional cavities
are not in communication with the main cavity;
communication between these cavities and the main cavity
may for example be closed off deliberately. These
20 cavities then remain empty during casting and they do not
become filled with metal.
25
In a second implementation, the additional cavities
are in communication with the main cavity. They
therefore become filled during casting.
In a fourth step S4, after the metal has cooled and
solidified in the shell mold 1, the cluster 30 is knocked
out from the shell mold 1.
In both implementations, knocking out consists in
fragmenting the shell by acting on the additional shell
30 portions. During this step, it is appropriate to avoid
any contact with the solidified metal.
Finally, in a fifth step S5, each of the blades 32
is separated from the remainder of the cluster 30 and is
finished by various finishing methods, e.g. machining
35 methods.
The invention relates in particular to the knockout
method used during the above-mentioned fourth step S4.
11
The knockout method is performed by means of a
knockout machine 40 (Figure 4).
The machine 40 comprises a frame or structure 42,
tooling 50, and an actuator 46. The frame 42 has
5 fastener tabs or tenons 44 (of the bench dog type),
serving to fasten the shell mold 1 containing the blade
cluster 30 securely to a perforated plate 41 of the frame
42. The perforated portions of the plate serve to pass
fragments of the shell mold during the knockout
10 operation, and they are not shown.
The tenons 44 serve to fasten the shell mold 1 in
such a manner that the axis of symmetry (X) of the mold
extends in the vertical direction.
The actuator 46 is a linear jack. It is arranged so
15 as to move the tooling 50 vertically in the downward
direction, along the axis X of the shell mold 1.
20
25
The tooling 50 (Figure 6) is in the shape of a cage,
with a top disk 54 and a bottom disk 52 fastened to the
disk 54 by four vertical metal bars 56.
The tooling 50 is fastened to the outlet shaft 48 of
the jack 46 by a sleeve 58 fastened to the outside top
surface of the disk 54, in which the end of the shaft 48
is secured. The top disk 54 is thus the driven portion
of the tooling 50.
The bottom disk 52 is the working portion of the
tooling 50, i.e. the portion that includes the knife 64
that engages the shell mold 1 in order to knock out the
blade cluster 30.
The disk 52 has a large opening 60 of generally
30 circular shape in its central portion (Figure 6) . At the
35
periphery of this opening 60 there are provided knockout
fingers 62. These fingers are disk portions that extend
from the peripheral ring 61 of the disk 52 in a radially
inward direction towards the axis X of the machine 40.
The bottom surface of the disk 52 (under the fingers
62 and also under the peripheral ring 61) constitutes the
knife 64. This knife 64 is designed to engage the shell
12
mold 1 when the jack 46 moves the tooling 50 downwards
(arrows A, Figure 3).
The jack 46 is designed to move the tooling 50 - and
thus the knife 64 - in translation relative to the frame
5 at a constant speed of less than 0.2 m/s. The choice of
a fairly slow speed serves to avoid creating excessive
accumulations of stresses on the casting cluster while
knocking out the blades, thereby avoiding creating
mechanical stresses that might generate recrystallized
10 grains during heat treatment.
Furthermore, the knockout machine 40 is designed in
such a manner that during the downward movement of the
tooling 50, the jack 46 moves the knife 64 (and more
generally the tooling 50) without making contact with the
15 cluster 30, and in particular without making contact with
the blades.
For this purpose, the disk 52 is arranged in such a
manner that the blade cluster 30 can pass through its
opening 60 without making contact.
20 The knockout machine 40 is designed in such a manner
that during the downward movement of the tooling 50, the
knife 64 engages different portions of the shell mold 1,
referred to as protuberances, and detaches the major
portion of the shell from the cluster 30.
25 In the example described, these protuberances are
constituted by the additional shell portions forming the
heat shields 13 and 13'.
It can thus be understood that the disk 52 is
designed to come into contact with the shell mold 1 via
30 the protuberances (the heat shields 13 and 13').
Nevertheless, the disk 52 (and thus knife 64) must not
come into contact with the (metal) cluster 30.
Particular care must be given to the contact between
the disk 52 and the protuberances. The protuberances are
35 constituted by the additional portions of the shell, i.e.
the heat shields 13 and 13'. Depending on the
13
implementation, these additional portions are either
empty, or else filled or partially filled with metal.
In the above-mentioned first implementation of the
method, the protuberances are empty. Under such
5 circumstances, in order to enable the disk 52 to move
downwards without corning into contact with the cluster
30, it suffices for the disk 52 to engage or interfere
with the additional shell portion while remaining at a
sufficient safety distance from the cluster 30. Under
10 such circumstances, the disk 52 can come largely into
contact with the additional shell portions (heat shields
13 and 13').
In the above-mentioned second implementation of the
method, shown in Figure 5B, the protuberances or heat
15 shields 13, 13' are filled in full or in part with metal.
In this implementation, the radial interference zone
between the disk 52 and the heat shield 13 can extend
over only a small distance dl between the disk 52 and the
shell mold 1. The path followed by the disk 52 is
20 designed to ensure that there is no contact under any
circumstances between the disk and the cluster 30; for
this purpose, a safety distance d2 is provided lying at
all times between the disk 52 and the cluster 30.
Furthermore, the shape of the disk 52 is designed in
25 such a manner that contact between the disk and the shell
mold takes place initially via the top heat shield 13.
This implies in particular that the disk 52 is arranged
conversely so as not to come into contact with the mold
portions 1 that are situated above the heat shield 13,
30 such as in particular the top projections 38 of the shell
mold 1 (Figure 5B).
The shield 13 constitutes a ''protuberance'' that the
knife 64 engages while the tooling 50 is being moved in
accordance with the invention; this does not apply to the
35 projections 38.
Advantageously, since the heat shield 13 is situated
at a certain distance from the blades, the mechanical
14
stresses applied to the blades during contact between the
knives 64 and the shell mold are relatively small and do
not create zones that might create recrystallized grains.
When the tooling 50 moves downwards under the action
5 of the jack 46, the disk 52 comes into contact with the
shell mold 1.
The knife 64 then bears against the surface of the
shield 13 (acting as a protuberance) delivering a force
that tends to break the ceramic of the shell into
10 fragments; rupture lines propagate going from the
protuberance towards all of the remainder of the shell.
Thus, as the tooling 50 continues to move downwards,
it strikes the shell mold 1 (at moderate speed) and
continues its downward movement while exerting a force on
15 the shell mold. The shell mold 1, which is brittle,
breaks into a large number of fragments; under the effect
of gravity, most of these fragments become detached from
the cluster 30 and fall away. The major portion of
knocking out the cluster is thus performed in a single
20 operation that is simple and fast.
After striking the heat shield 13 constituting the
top protuberance, and by continuing to move downwards,
the knife 64 strikes the heat shield 13', which
constitutes a bottom protuberance. It then breaks the
25 remaining portions of the shell mold and thus finishes
off knocking it out (apart from a few portions that might
possibly remain) .
The tooling 50 described above has the advantage of
being operated using a simple movement in translation.
30 This is made possible by the fact that the shape of the
shell mold 1 enables the tooling to move past as it moves
downwards in the vertical direction (axis X) .
Nevertheless, a knockout machine that is more
complex, in particular having different knockout tooling,
35 might be necessary when the shape of the shell mold does
not make it possible to knock out the cluster by moving
tooling merely by a simple movement in translation.
15
An example of such a situation is shown in
Figures 7A, 7B, and 7C. In the example shown, the blades
of a cluster 130 that is to be knocked out form a shell
mold 101 presenting projections 138 that are very
5 proeminent. These projections 138 are incompatible with
tooling moving downwards vertically without striking the
shell mold 101 in register with these projections, and
while also engaging the heat shield 113 (Figure 7A) .
Under such circumstances, it is therefore necessary
10 for the tooling to move with movement that is more
complex than simple movement in vertical translation.
15
This movement may be executed by means of a machine
140 shown in Figures 7B and 7C, which constitutes another
embodiment of the invention.
The portions of the machine 140 or of the mold 101
that are of structure and or function identical or
similar to the structure and or function of the
corresponding portions of the machine 40 or of the mold 1
are given the same references as the corresponding
20 portions, plus 100.
The knockout machine 140 comprises a frame 142 with
a perforated plate 141 on which the shell mold 101 can be
fastened, tooling 150, and actuators 146.
The tooling 150 is not constituted as a single rigid
25 portion as the tooling 50, but rather as four portions
(it could naturally be made using some arbitrary number
of portions other than four) . Each of these four
portions comprises a plate 152 generally in the form of
one-fourth of a disk, and these four plates are
30 identical.
In order to move the plates 152 and consequently
knock out the blade cluster, the knockout machine 140 has
four rotary actuators 146 that are identical to one
another. Each actuator 146 is a rotary jack suitable for
35 turning one of the plates 152 about a horizontal axis.
16
For this purpose, each of the plates 152 has a
flange portion 158 designed to enable the plate 152 to be
fastened to a respective one of the actuators 146.
During the operation of knocking out the blade
5 cluster 130 from the shell mold 101, the actuators 146
drive the four plates 152 to turn simultaneously. During
this movement, the plates 152 engage the shell mold 101
via its top heat shield 113, thereby fragmenting the mold
101 into a large number of pieces and thus separating a
10 large portion of the mold 101 from the blade cluster.
15
In another embodiment, the various portions of
tooling may naturally be moved not simultaneously, but in
any appropriate sequence, e.g. one after another or
successively in diametrically opposite pairs, etc.
The plates 152 perform turning movements in such a
manner that they do not come into contact with the
cluster 130. Such turning movement enables the ends of
the fingers 162 of the tooling 150 to move towards the
axis X of the shell mold 101 (arrows in Figure 7B). As a
20 result, the fingers 162 pass between each of the pairs of
adjacent blades, thereby ensuring that the shell mold 101
is fractured between all of the adjacent pairs of blades.
By fragmenting the shell mold 101 in this way into at
least as many fractions as there are blades 132, the
25 tooling 150 thus ensures that a very large portion of the
portions a 101 is knocked out.
30
Each actuator 146 is controlled in such a manner
that is moves the end of the plate 152 that it drives,
i.e. the end of the finger 162, at a speed that is
substantially constant and less than 0.2 m/s.
Naturally, a knockout machine or method of the
invention may be provided in numerous embodiments and
implementations other than those described above.
Numerous possibilities exist as to how the knockout
35 knives may be arranged and how the tooling that supports
them may be arranged, concerning the speeds or travel
paths of the knife (or knives).

CLAIMS
1. A knockout method for knocking out a cluster (30, 130)
of lost-pattern metal castings (32, 132), the cluster of
castings being formed in a shell (1, 101), wherein at
5 least one knife (64) is moved by means of a machine (40,
140) without making contact with the cluster in such a
manner that the knife engages the shell, breaks it into a
plurality of fragments, and detaches at least a portion
of the shell from the cluster.
10
15
2. A knockout method according to claim 1, wherein said
movement of said at least one knife (64) for knocking out
the cluster of castings takes place at a speed of less
than 0.2 m/s.
3. A knockout method according to claim 1 or claim 2,
wherein the movement of said at least one knife (64) for
knocking out the cluster of castings is constituted
solely by a movement in translation or solely by a
20 movement in rotation.
4. A knockout method according to any one of claims 1 to
3, wherein the movement of said at least one knife (64)
comprises passing between every pair of adjacent castings
25 among said castings (32, 132).
5. A knockout method according to any one of claims 1 to
4, wherein said at least one knife is constituted by a
plurality of knives, and during the movement of said
30 plurality of knives, all of said knives come into contact
with the shell at substantially the same time.
6. A method of fabricating castings, the method
comprising the following steps: fabricating a cluster
35 (30, 130) of lost-pattern castings (32, 132), the cluster
of castings being formed in a shell (1, 101), then
18
knocking out at least a portion of the shell by the
method according to any one of claims 1 to 5.
7. A knockout machine (40, 140) for knocking out a
5 cluster (30, 130) of lost-pattern castings, the cluster
of castings being formed in a shell (1, 101), the machine
comprising:
a frame (42, 142) having means (44) for rigidly
fastening the shell to the frame;
10 at least one knife (64); and
at least one actuator (46, 146) suitable for moving
said at least one knife relative to the frame in a space
provided for fastening the cluster.
15 8. A knockout machine (40, 140) according to claim 7 for
knocking out a cluster (30, 130) of castings, wherein
said at least one actuator is suitable for moving said at
least one knife relative to the frame at a speed less
than 0.2 m/s.
20
9. A knockout machine (40, 140) according to claim 7 or
claim 8 for knocking out a cluster (30, 130) of castings,
wherein said at least one actuator includes an actuator
suitable for moving at least one blade for knocking out
25 the cluster of castings solely by a movement in
translation or solely by a movement in rotation.
10. An assembly comprising a knockout machine (40, 140)
according to any one of claims 7 to 9, and a cluster (30)
30 of lost-pattern castings, the cluster of castings being
formed in a shell (1, 101); the knockout machine is
suitable for enabling said cluster to be fastened to the
frame (42, 142); and said at least one actuator is
suitable, when the cluster is fastened to the frame (42,
35 142), for moving said at least one knife (64) relative to
the cluster and without making contact with the cluster
(30, 130) in such a manner that the knife engages the
19
shell, it breaks the shell into a plurality of fragments,
and detaches at least a portion of the shell from the
cluster.
5 11. An assembly according to claim 10, wherein the shell
(1, 101) includes at least one protuberance (13, 113) in
the vicinity of each casting (32) of the cluster (30,
130), and wherein said at least one knife engages the
protuberance during said movement.
10
12. An assembly according to claim 11, wherein said
protuberances (13, 113) are arranged substantially in a
plane.
15 13. An assembly according to claim 11 or claim 12,
wherein at least some of said protuberances (13, 113) are
formed around or from a part (14) in the form of a plate
perforated by holes.