CASTING TREE AND METHOD OF ASSEMBLY1
Background of the invention
I
The present invention relates to the field of
5 casting, and more particularly to a casting tree for lost
pattern casting, and also to methods of fabricating shell
molds and to casting methods using such a pattern.
In the description below, terms such as "top",
"bottom", "horizontal", and "vertical" are defined by the
10 normal orientation of such a mold while metal is being
cast into its inside.
So-called lost wax or lost pattern casting methods
have been known since antiquity. They are particularly
suitable for producing metal parts with shapes that are
15 complex. Thus, lost pattern casting is used in
particular for producing turbine engine blades.
In lost pattern casting, a first step normally
comprises making a pattern out of a material having a
melting temperature that is comparatively low, :e.g. out
20 of a wax or a resin. The pattern is then incorporated in
a casting tree that is then coated in a refractory
material in order to form a mold. Among the various
types of mold that can be used in lost pattern casting,
so-called shell molds are known in particular, which are
25 formed by dipping the pattern or a cluster of patterns in
a slip, and then dusting the slip-coated pattern or
cluster with refractory sand in order to form a shell
around the pattern or the cluster, followed by firing the
shell in order to sinter it so as to consolidate the
30 assembly. Several successive dipping and dusting
operations may be envisaged in order to obtain a shell of
thickness that is sufficient before it is fired. The
term "refractory sand" is used in the present context to
mean any granular material of sufficiently fine grain
35 size for complying with the desired production
1 Translation of the title as established ex officio.
5
2
tolerances, that is capable in the solid state of
withstanding the temperatures of the molten metal, and
that can be consolidated into a single piece while firing
the shell.
After emptying or eliminating the material of the
pattern from the inside of the mold, whence the "lost
pattern" name of such methods, molten metal is cast into
the mold so as to fill the mold cavity left inside the
mold by the pattern after it has been emptied out or
10 eliminated. Once the metal has cooled and solidified,
the mold can be opened or destroyed in order to recover a
metal part having the shape of the pattern. In the
present context, the term "metal" covers both pure metals
and also, and above all, metal alloys.
15 In addition to at least one pattern, the casting
tree normally comprises a part support comprising a
distributor that is to form at least one casting channel
in the mold, that is used to deliver molten metal into
the molding cavity during casting. In order to be able
20 to produce a plurality of parts simultaneously, it is
possible to incorporate a plurality of patterns as a
cluster in a single casting tree.
In order to increase rates of production, it is
possible to fabricate not only the patterns but also the
25 various elements of the part support by injection
molding. Nevertheless, with the increasing complexity of
individual patterns and of clusters of patterns in
casting trees, the ability to assemble casting trees from
a plurality of separate elements is becoming
30 simultaneously more necessary and more difficult to
perform. Typically, the various elements of a casting
tree are assembled together manually and adhesively
bonded together. However, given the increasing complexity
of the tree and the ever-tighter tolerances for
35 positioning and alignment, in particular when performing
monocrystalline casting, that leads to ever-increasing
costs and time for assembly.
3
Object and summary of the invention
The present invention seeks to remedy those
drawbacks. In particular, this disclosure seeks to
5 propose a casting tree for lost pattern casting that
includes at least one part support, and at least one
pattern, with assembly of the casting tree being
simplified and easier to automate.
This object is achieved by the fact that the casting
10 tree also comprises at least a first male-female
connection connecting said pattern to the part support
and comprising an orifice, a peg at least partially
inserted into the inside of the orifice, and a film of
meltable material interposed between an outside surface
15 of the peg and an inside surface of the orifice. The peg
may in particular be secured to the pattern and the
orifice may be formed in the part support, or vice versa.
Because of the male-female connection, assembly of
the casting tree can be simplified and automated, while
20 still ensuring that the various elements are accurately
positioned. Simultaneously, the film of meltable
material interposed between the outside surface of the
peg and the inside surface of the orifice serves to
secure them to each other and to maintain this first
25 male-female connection.
In order to ensure accuracy of the relative
positioning between the peg and the orifice in this first
male-female connection in at least one direction that is
substantially orthogonal to an axis for inserting the peg
30 into the orifice, the first male-female connection
presents at least two points of direct contact between an
outside surface of the peg and an inside surface of the
orifice, which points are mutually offset in the
direction that is substantially orthogonal to the
35 insertion axis for inserting the peg into the orifice.
In the present context, the term "substantially
orthogonal" is used to mean an orientation close to a
4
right angle, within the limits of fabrication tolerances
and measurement. By way of example, this orientation may
correspond to an angle of 90°±5°. At least one of said
contact points may be formed by a protuberance that is
5 radial relative to said insertion axis on the outside
surface of the peg and/or on the inside surface of the
orifice, thereby also making it possible to maintain
radial spacing between the outside surface of the peg and
the inside surface of the orifice, which radial spacing
10 contains said film of meltable material.
In order to ensure accurate positioning and
orientation of the pattern relative to the part support
over a plurality of axes, the casting tree may further
comprise a second male-female connection connecting said
15 pattern to the part support and also comprising an
orifice and a peg at least partially inserted inside the
orifice with a film of meltable material interposed
between an outside surface of the peg and an inside
surface of the orifice, said first and second male-female
20 connections presenting insertion axes for inserting the
pegs into the respective orifices that are substantially
parallel and that are offset from each other in a
direction orthogonal to said insertion axes. In the
present context, the term "substantially parallel" means
25 an orientation that is parallel or nearly parallel within
the limits of fabrication tolerances and measurements.
This orientation may thus correspond to an angle of
0°±5°, for example. In particular, said first malefemale
connection may present at least two direct contact
30 points between the outside surface of the peg and the
inside surface of the orifice, which direct contact
points are mutually offset in at least a first direction
that is substantially orthogonal to the insertion axes
for inserting the pegs into the orifices, and said second
35 male-female connection presents at least one direct
contact point between the outside surface of the peg and
the outside surface of the orifice, said contact points
5
of the second male-female connection being offset
relative to said contact points of the first male-female
connection at least in a second direction that is
substantially orthogonal to the first direction and to
5 the insertion axes for inserting the pegs into the
orifices. Thus, with at least three contact points that
are not in alignment, it is possible to obtain accurate
positioning and orientation for all three axes of the
pattern relative to the part support~
10 In order to further facilitate assembly, said first
male-female connection may present at least three direct
contact points between the outside surface of the peg and
the inside surface of the orifice, so as to fix a
position of the pattern relative to the part support, and
15 said second male-female connection may present two direct
contact points between the outside surface of the peg and
the inside surface of the orifice, said two contact
points of the second male-female connection being
mutually offset in at least one direction that is
20 substantially orthogonal to a plane containing said
insertion axes, so as to fix the orientation of the
pattern relative to the part support.
In order to block the pattern better relative to the
part support, the casting tree may include another
25 connection of the pattern to the part support opposite
from the first male~female connection in the direction of
an insertion axis for inserting the peg in the orifice of
said first male-female connection. This other connection
may be a simple adhesively bonded connection, but it
30 could also include physical markers for ensuring the
positioning and the orientation of the pattern relative
to the part support.
Said part support may comprise a distributor for
forming at least one casting channel in a mold, said
35 first male-female connection connecting said pattern to
said distributor. In addition, the casting tree may have
6
a plurality of patterns connected in a cluster to the
part support.
The present disclosure also provides a method of
assembling a casting tree for lost pattern casting, the
5 method comprising at least the following steps: at least
partially inserting at least one peg in at least one
corresponding orifice so as to create at least a first
male-female connection between at least one pattern and a
part support, said male-female connection presenting at
10 least two direct contact points between the outside
surface of the peg and the inside surface of the orifice,
the contact points being mutually offset in the direction
substantially orthogonal to the insertion axis for
inserting a peg into the orifice; infiltrating a meltable
15 material in the liquid state between at least one outside
surface of said peg and an inside surface of said orifice
in the first male-female connection; and solidifying the
meltable material infiltrated between the outside surface
of the peg and the inside surface of the orifice so as to
20 form a film of meltable material interposed at least
between an outside surface of the peg and an inside
surface of the orifice in order to consolidate the first
male-female connection. In particular, the infiltration
step may be performed by dipping at least the first male-
25 female connection in a bath of said meltable material in
the liquid state. This "dip sealing" method enables the
male-female connection to be consolidated quickly in a
manner that is easy to automate.
The present disclosure also relates to a method of
30 producing a casting mold, comprising assembling a casting
tree using the above-mentioned assembly method, coating
said casting tree in a refractory material in order to
form the mold, and emptying the casting tree out from the
inside of the mold. In particular, the casting tree may
35 be made of a material that melts at a temperature lower
than said refractory material and it can be emptied from
the mold in the liquid state. In addition, the coating
7
may be implemented by dipping said casting tree in a
slip, dusting the casting tree with a refractory sand in
order to form a shell around the casting tree, and
sintering the shell in order to consolidate it. It is
5 possible to envisage using a plurality of successive
dipping and dusting operations in order to obtain a shell
of suffi~ient thickness prior to sintering.
The present disclosure also provides a casting
method comprising producing a casting mold using the
10 above-mentioned production method, casting a molten metal
material into the inside of said mold, solidifying the
metal material in the mold, and removing the mold.
Brief description of the drawings
15 The invention can be well understood and its
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:
20 · Figure 1 is a diagrammatic perspective view of a
25
30
casting tree in an embodiment;
Figure 2 is a section view of two adjacent malefemale
connections connecting a pattern to a distributor
in the Figure 1 casting tree;
Figure 3 is a diagram showing a first step in
assembling the Figure 1 casting tree;
· Figure 4 is a diagrammatic perspective view
showing a second step of assembling the Figure 1 casting
tree;
· Figure 5 shows the distributor of the Figure 1
casting tree with orifices corresponding to said malefemale
connections;
Figure 6 is a detail view of one of the patterns
incorporated in the Figure 1 casting tree, showing in
35 particular two pegs corresponding to said male-female
connections;
8
· Figure 7 is a diagrammatic perspective view
showing a third step of assembling the Figure 1 casting
tree;
· Figure 8 shows pegs being inserted in the
5 corresponding orifices to form said male-female
connections;
· Figures 9A and 9B show two alternative
arrangements for the male-female connections between each
pattern and the part support;
10 · Figure 10 shows a bottom end of the pattern being
inserted in a concave depression in a base of a part
support;
· Figure 11 is a diagrammatic perspective view
showing a fourth step of assembling the Figure 1 casting
15 tree;
Figure 12 is a diagram showing a fifth step of
assembling the Figure 1 casting tree;
· Figure 13 is a diagram showing a sixth step of
assembling the Figure 1 casting tree;
20 · Figure 14 is a diagrammatic perspective view
showing a seventh step of assembling the Figure 1 casting
tree;
· Figure 15 is a diagrammatic perspective view
showing a seventh step of assembling the Figure 1 casting
25 tree;
· Figure 16 is a diagram showing a liquid film
infiltrating into the interstices of one of the malefemale
connections;
Figure 17 is a diagrammatic perspective view
30 showing an eighth step of assembling the Figure 1 casting
tree; and
Figure 18 shows a shell mold formed around the
Figure 1 casting tree.
35 Detailed description of the invention
Figure 1 shows a casting tree 1 in an embodiment of
the invention. The casting tree 1 is made of material
9
having a comparatively low melting point, in particular a
wax or a resin, and it is designed to form the internal
cavities of a casting mold that is obtained by the lost
wax or lost pattern method, in which the casting tree is
5 initially coated in refractory material in order to form
the mold, and then the casting tree in the liquid state
is emptied out from the inside of the mold. The casting
tree 1 shown thus comprises a plurality of patterns 2
arranged in a cluster around a descender 3 supported by a
10 base 4 and a riser 5 and surmounted by a distributor 6 in
the form of a ring and a cup 7. Together, the riser 5,
the base 4, the descender 3, the distributor 6, and the
cup 7 form a part support 8 for the patterns 2, each of
which reproduces the shape of a casting that is to be
15 produced. In the example shown, the patterns 2 thus
reproduce the shape of turbine engine blades, although
other applications are equally possible. The distributor
6 is for shaping casting channels in the mold to bring
the molten metal to the molding cavities shaped by the
20 patterns 2, from a funnel constituted by the cup 7.
Each of the elements of the casting tree 1 can be
produced separately, e.g. by injection molding. In order
to produce these elements, and in particular those of the
part support 8, it is also possible to envisage using a
25 recycled material, resulting from emptying previouslyproduced
molds. It is nevertheless important to ensure
that the elements are accurately positioned in the
casting tree 1, in particular when performing difficult
casting methods, such as monocrystalline casting.
30 Thus, in the casting tree 1 shown in Figure 1, each
pattern 2 is connected to the distributor 6 by a pair of
male-female connections 9, 10. As shown in Figure 2,
each of these male-female connections 9, 10 comprises a
peg 11, 12 and an orifice 13, 14 in which said peg 11, 12
35 is received. In this embodiment, in order to make the
pegs 11, 12 easier to insert into the corresponding
orifices 13, 14, each peg 11, 12 presents an outside
10
surface 11a, 12a that is frustoconical and converging in
the peg-insertion direction, and each orifice 13, 14 also
presents an inside surface 13a, 14a that is likewise
frustoconical and converging in the peg-insertion
5 direction. Depending in particular on the options for
fabricating these elements, other converging shapes, e.g.
stepped shapes, could be considered as alternatives or in
addition to these frustoconical shapes.
Furthermore, in each of the male-female connections
10 9, 10, a film 15 of meltable material is interposed
between the outside surface 11a, 12a of the peg 11, 12
and the inside surface 13a, 14a of the orifice 13, 14.
This film 15 that adheres both to the outside surface of
the peg 11, 12 and to the inside surface of the orifice
15 13, 14 serves to consolidate each male-female connection
9, 10.
Figure 3 shows a first step in assembling the
casting tree 1, in which the descender 3 is connected to
the base 4. As can be seen in this figure, the base 4
20 includes individual raised supports 16 for each pattern
2, each of these supports 16 presenting a concave
depression 17 at its top with an outline that is
complementary to the outline of the bottom end of each
pattern 2. Thus, the concave depression 17 is designed
25 to facilitate properly positioning and orienting the
pattern 2 in the casting tree 1.
Figure 4 shows a second step in assembling the
casting tree 1 in which the distributor 6 is placed on
the descender 3. A central rod 18 projecting vertically
30 from the descender 3 serves to fasten the distributor 6
horizontally relative to the descender 3, while
continuing to allow a certain freedom to move vertically.
As shown in Figure 5, in this embodiment, the
orifices 13, 14 of the male-female connections 9, 10 are
35 orifices formed in the distributor 6 and passing through
it vertically. Thus, the complementary pegs 11, 12 are
formed on the patterns 2, as shown in Figure 6.
11
Nevertheless, it is equally possible to envisage
inverting this arrangement either for only one of the
male-female connections, or else for both of them.
As can be seen in particular in Figure 6, in this
5 embodiment, the patterns 2 are for producing turbine
engine blades and they thus reproduce the shape of such
blades. Nevertheless, it is also possible to envisage
using a casting tree and an assembly method of the
invention for producing other parts, and the shapes of
10 the patterns would then be adapted accordingly. In this
embodiment, each pattern 2 points downwards, thus with a
bottom end 2a in the form of a blade tip, and a top end
2b in the form of a blade root, with the pegs 11, 12
being incorporated thereon and pointing along insertion
15 axes Z1, Z2 that are substantially parallel and offset
from each other along an orthogonal direction X. The
outside surface 11a of the peg 11 of the first malefemale
connection 9 has four protuberances 11b, 11c, 11d,
and 11e arranged on different axes that are radial
20 relative to the insertion axis Z1. Each of these
protuberances 11b to 11e is in the shape of a spherical
cap, although it is possible to envisage other shapes as
well. Furthermore, the outside surface 12a of the peg 12
of the second male-female connection 10 presents two
25 protuberances 12b, 12c facing in opposite directions
along an axis Y2 that is orthogonal to the insertion axis
Z2 and to the direction X along which the two insertion
axes Z1 and Z2 are offset.
Figure 7 is a diagram showing a first pattern 2
30 being put into place between the base 4 and the
distributor 6. While it is being put into place, with
the pattern initially slightly inclined, the pegs 11, 12
are inserted into the orifices 13, 14 along the insertion
axes Z1, Z2, as shown in Figure 8. During this
35 insertion, the protuberances 11b, 11c, 11d, and 11e and
also 12b and 12c form points of direct contact between
the outside surfaces 11a, 12a of the pegs 11, 12 and the
12
inside surfaces 13a, 14a of the orifices 13, 14 so as to
maintain radial spacing elsewhere between the outside
surfaces 11a, 12a of the pegs 11, 12 and the inside
surfaces 13a, 14a of the orifices 13, 14 while
5 maintaining each pattern 2 accurately in position and in
orientation relative to the distributor 6. This radial
spacing is in turn intended to be filled at least in part
by infiltration of a meltable material in the liquid
state during a subsequent step, thereby forming the film
10 15. Although in the embodiment shown, all of these
protuberances are formed on the outside surfaces of the
pegs, it is also possible as an alternative or in
addition thereto, to form contact points with radial
protuberances on the inside surfaces 13a, 14a of the
15 orifices 13, 14. Furthermore, the number of
protuberances may also be varied: thus, it is already
possible to obtain accurate positioning for the first peg
11 with only three radial protuberances 11b, 11c, 11d, as
shown in Figure 9A, or indeed accurate positioning and
20 orientation of the pattern 2 relative to the distributor
6 with only two radial protuberances 11b, 11c on the
first peg 11 and only one radial protuberance 12b on the
second peg 12, as shown in Figure 9B, providing the
points of contact are not in alignment on a plane
25 containing the insertion axes Z1, Z2, or parallel
thereto.
After the pegs 11, 12 have been inserted in the
orifices 13, 14, the pattern 2 is tilted towards the
vertical while being lifted a little so as to bring its
30 bottom end 2a into alignment with the concave depression
17 on the support 16 in order to be inserted therein, as
shown in Figure 10.
The remaining patterns 2 are subsequently inserted
in succession in analogous manner between the base 4 and
35 the distributor 6, as shown in Figure 11. The concave
depressions 17 in the supports 16 on the face 4 are
substantially shallower than the pegs 11, 12 and the
14
exposed surfaces and in the interstices between the
elements that were dipped, including between the outside
surfaces 11a, 12a of the pegs 11, 12 and the inside
surfaces 13a, 14a of the corresponding orifices 13, 14,
5 so as to consolidate each male-female connection 9, 10
between a pattern 2 and the distributor 6. The
interstices between the distributor 6 and the patterns 2,
the descender 3, and the cup 7 are also filled in at
least in part by this film 15, thus also contributing in
10 this way to consolidating the casting tree 1 that is
being assembled. This assembly method is finalized by
bonding the riser 5 under the base 4, as shown in
15
Figure 17 in order to obtain the casting tree 1 as shown
in Figure 1.
This casting tree 1 can then be used for producing a
shell mold 20 as shown in Figure 18. For this purpose, a
sequence comprising dipping the casting tree 1 in a slip
and subsequently dusting the casting tree with refractory
sand is initially repeated several times. Thereafter,
20 the shell made of refractory and slip as formed in this
way is sintered by firing in a kiln. The meltable
material forming the casting tree 1 melts at the high
temperatures in the kiln, and can easily be removed in
the liquid state from the shell mold 20 as created in
25 this way.
In the shell mold 20, the patterns 2 have created
mold cavities 21, the cup 7 has created a casting funnel
22, and the distributor 6 has created casting channels 23
connecting the funnel 22 to the cavities 21. The mold 20
30 can thus be used in a casting method that comprises a
step of casting a molten metal material into the inside
of the mold 20, in which step the molten metal material
fills the cavities 21 via the funnel 22 and the channels
23, followed by a step of causing the metal material in
35 the mold 20 to solidify, which solidification may be
directed, e.g. for the purpose of obtaining
monocrystalline parts. Finally, the naturally friable
15
mold 20 can be removed in order to release the parts that
have been formed in this way within the mold cavity 21,
which parts then reproduce the shape of the patterns 2.
Although the present invention is described with
5 reference to specific embodiments, it is clear that
various modifications and changes may be made to those
embodiments without going beyond the general ambit of the
invention as defined by the claims. In addition,
individual characteristics of the various embodiments
10 mentioned may be combined in additional embodiments.
Consequently, the description and the drawings should be
considered in a sense that is illustrative rather than
restrictive.

CLAIMS
1. A casting tree (1) for lost pattern casting, the tree
including at least one part support (8), at least one
pattern (2), and at least one first male-female
5 connection (9) connecting said pattern (2) to the part
support (8), said first male-female connection (9)
comprising an orifice (13), a peg (11) at least partially
inserted inside the orifice (13), and a film (15) of
meltable material interposed at least between an outside
10 surface (11a) of the peg (11) and an inside surface (13a)
of the orifice (13), the tree being characterized in that
said first male-female connection (9) presents at least
two points of direct contact between an outside surface
(11a) of the peg (11) and an inside surface (13a) of the
15 orifice (13), which points are mutually offset in at
least one direction that is substantially orthogonal to
an insertion axis (Z1) for inserting the peg (11) into
the orifice (13).
20 2. A casting tree (1) according to claim 1, wherein at
least one of said contact points is formed by a
protuberance (11b, 11c, 11d, 11e) that is radial relative
to said insertion axis .(Z1) on the outside surface of the
peg (11) and/or on the inside surface of the orifice
25 (13).
3. A casting tree (1) according to claim 1 or claim 2,
further comprising a second male-female connection (10)
connecting said pattern (2) to the part support (8) and
30 also comprising an orifice (14) and a peg (12) at least
partially inserted inside the orifice (14) with a film
(15) of meltable material interposed between an outside
surface (12a) of the peg (12) and an inside surface (14a)
of the orifice (14), said first and second male-female
35 connections (9, 10) presenting insertion axes (Z1, Z2)
for inserting the pegs (11, 12) into the respective
orifices (13, 14) that are substantially parallel and
17
that are offset from each other in a direction (X)
orthogonal to said insertion axes (Z1, Z2).
4. A casting tree (1) according to claim 3, wherein said
5 first male-female connection (9) presents at least two
direct contact points between the outside surface (11a)
of the peg (11) and the inside surface (13a) of the
10
orifice ( 13), which direct contact points are mutually
offset in at least a first direction that is
substantially orthogonal to the insertion axes ( z 1, Z2)
for inserting the pegs (11, 12) into the orifices (13,
14), and said second male-female connection (10) presents
at least one direct contact point between the outside
surface (13a) of the orifice (13) and the inside surface
15 (14a) of the orifice (14), said contact points of the
second male-female connection (10) being offset relative
to said contact points of the first male-female
connection (9) at least in a second direction that is
substantially orthogonal to the first direction and to
20 the insertion axes (Z1, Z2) for inserting the pegs (11,
12) into the orifices (13, 14).
5. A casting tree (1) according to claim 3, wherein said
first male-female connection (9) presents at least three
25 direct contact points between the outside surface (11a)
of the peg (11) and the inside surface (13a) of the
orifice (13), and said second male-female connection (10)
presents two direct contact points between the outside
surface (12a) of the peg (12) and the inside surface
30 (14a) of the orifice (14), said two contact points of the
second male-female connection (10) being mutually offset
in at least one direction (Y2) that is substantially
orthogonal to a plane containing said insertion axes (Z1,
Z2) .
35
6. A casting tree (1) according to any one of claims 1 to
5, including another connection of the pattern (2) to the
5
18
part support (8) opposite from the first male-female
connection (9) in the direction of an insertion axis (Zl)
for inserting the peg (11) in the orifice (13) of said
first male-female connection (9).
7. A casting tree (1) according to any one of claims 1 to
6, wherein said part support (8) comprises a distributor
(6) for forming at least one casting channel (23) in a
mold (20), said first male-female connection (9)
10 connecting said pattern (2) to said distributor (6).
15
8. A casting tree (1) according to any one of claims 1 to
7, having a plurality of patterns (2) connected in a
cluster to the part support (8).
9. A method of assembling a casting tree (1) for lost
pattern casting, the method comprising at least the
following steps:
· at least partially inserting at least one peg (11)
20 in at least one corresponding orifice (13) so as to
create at least a first male-female connection (9)
between at least one pattern (2) and a part support (8),
said first male-female connection (9) presenting at least
two direct contact points between the outside surface
25 (11a) of the peg (11) and the inside surface (13a) of the
30
orifice (13), the contact points being mutually offset in
at least one direction substantially orthogonal to the
insertion axis (Z1) for inserting a peg (11) into the
orifice (13);
· infiltrating a meltable material in the liquid
state between at least one outside surface (11a) of said
peg (11) and an inside surface (13a) of said orifice (13)
in the first male-female connection (9); and
solidifying the meltable material infiltrated
35 between the outside surface of the peg and the inside
surface of the orifice so as to form a film (15) of
meltable material interposed at least between an outside
19
surface (11a) of the peg (11) and an inside surface (13a)
of the orifice (13) in order to consolidate the first
male-female connection (9).
5 10. An assembly method according to claim 9, wherein the
infiltration step is performed by dipping at least the
first male-female connection (9) in a bath of said
meltable material in the liquid state.
10 11. A method of producing a casting mold (20), the method
comprising the following steps:
· assembling a casting tree (1) using the method of
claim 9 or claim 10;
· coating said casting tree in a refractory material
15 in order to form the mold; and
· emptying the casting tree (1) from the inside of
the mold (20) .
12. A method of producing a casting mold according to
20 claim 11, wherein said casting tree (1) is made of a
material that is meltable at a temperature lower than
said refractory material and is emptied from the mold
(20) in the liquid state.
25 13. A method of producing a casting mold (20) according
to claim 11 or claim 12, wherein said coating step is
performed by dipping said casting tree (1) in a slip,
dusting the casting tree (1) with a refractory sand in.
order to form a shell around the casting tree, and
30 sintering the shell in order to consolidate it.
14. A casting method comprising at least the following
steps:
producing a casting mold (20) using the method
35 according to any one of claims 11 to 13;
· casting a molten metal material into the inside of
said mold (20);
20
solidifying the metal material in the mold (20);
and
· detaching the mold (20).