[0001] The object of the invention is a main gating assembly and use thereof for casting
thin-walled products, especially from materials based on Fe, including Fe alloys with
nanobainitic structure, characterised by high dimensional accuracy and increased strength.
[0002] From US patent application No.
US3401737 A, a wax cup and handle for model casting is known, for use in investment casting,
comprising a cup-shaped wax sprue that is internally threaded. The application also
discloses a rod fitted with a spiral and a handle. One end of the rod loosely enters
the cup, through the aforementioned open base, with the spiral fitting into the threaded
inner surface of the cup.
[0003] In turn, From US patent application No.
US3604496 A, a reusable sprue-forming pattern is known, for use with an investment casting disposable
pattern, comprising: a generally frustoconical, cup-shaped metallic member having
a smooth outer surface, an annular flange extending outward from the open end thereof,
and a relatively thick base; a stud member located in the base of the cup-shaped member
and having a threaded portion extending a short distance into the open interior of
the cup-shaped member and terminating well below the open end thereof; and an elongated
hollow handle having one end extending down into the open interior of the cup-shaped
member and including internal threads to engage the threaded portion of said stud
member.
[0004] The main gating assembly for casting thin-walled products using lost wax technology
is obtained by pouring wax material or wax into the cavity of an appropriate mould
in which a sleeve and a rod are preferably located, and a foot may also be placed.
The mould for producing the main gating assembly has recesses corresponding in shape
to these parts, as well as additional recesses. Once the wax material has solidified,
the parts placed in the mould are connected to each other with the wax material in
a shape that was determined by the shape of the mould recesses. The process of casting
metal parts uses models of these parts, made of wax or wax material, attached to the
main gating assembly to form a model set. Such a model set is immersed in a ceramic
binder and covered with a ceramic backfill, after which, under special environmental
conditions (such as temperature, humidity, time, etc.), the layer thus formed is dried
and these operations are repeated several times until a sufficiently thick ceramic
shell is obtained on the model assembly. The wax material from the inside of the shell
is then melted in a dedicated device to create a spatial shell mould which is then
flooded with a liquid metal after being properly roasted at a specific temperature
and for a specific time. Often, the process of creating the shell mould is carried
out by a machine or a robot.
[0005] One technical problem is to develop a new main gating assembly for thin-walled castings
of such a design that will allow the correct and reproducible process of applying
individual layers of the ceramic mould to the model set to be carried out and a mould
to be obtained that, in the process of gravitational, bottom-up vacuum casting, will
enable the correct, coaxial within the assumed tolerance, positioning of the mould
in the machine chamber. Another technical problem is to ensure a stable connection
between the components of the main gating assembly and the wax material.
[0006] The essence of the main gating assembly according to the invention is that it comprises
an elongated rod and a sleeve, the rod being provided at one end with a thread, preferably
a metric triple taper thread, and at the other end with a handle provided with a circular
hole with an axis perpendicular to the axis of the rod and with a hexagonal tip, and
the sleeve having the shape of a truncated cone turned with its wider end upwards
and being provided with a flange located at the upper edge of the sleeve.
[0007] Preferably, the rod is provided with a flange located below the handle.
[0008] Preferably, the rod is provided with a rim located above the thread.
[0009] Preferably, the sleeve flange has a top surface perpendicular to the axis of the
sleeve.
[0010] Preferably, the lateral surface of the sleeve has transverse grooves and vertical
ribs.
[0011] Preferably, the main gating assembly is provided with a foot, preferably in the shape
of a truncated cone provided with flat supports.
[0012] The object of the invention is also the use of the so structured main gating assembly
for casting thin-walled products, especially from materials based on Fe, including
Fe alloys with nanobainitic structure, characterised by high dimensional accuracy
and increased strength.
[0013] The main gating assembly in embodiments is shown in the drawing, wherein:
Fig. 1 shows the rod in an isometric view, provided with a rim,
Fig. 2 shows the rod in an isometric view,
Fig. 3 shows the sleeve in an isometric view,
Fig. 4 shows the main gating assembly in its first embodiment,
Fig. 5 shows the main gating assembly in its second embodiment,
Fig. 6 shows the main gating assembly in its first embodiment in a broken cross-sectional
view,
Fig. 7 shows the main gating assembly in its second embodiment in a broken cross-sectional
view.
[0014] The main gating assembly according to the invention and as shown in the accompanying
drawing comprises a rod 1 and a sleeve 2. The rod 1 is an elongated element made of
a durable material, preferably a metal or its alloy, and is provided with a thread
3 at one of its ends and with a handle
4 at the other end, as well as with a flange
5 located near the handle
4, and may be provided with a rim
6 located near the thread
3. The thread
3 is a metric triple taper thread. The handle
4 of the rod
1 is in the form of a thickening
7 provided with a circular hole
8 with an axis perpendicular to the axis of the rod
1 and with a hexagonal tip
9. The hole
8 allows a pin to be inserted therein. Such a structure of the rod
1 allows the model set to be securely fixed in the fixing head of the unshown robot
which is located at the stand for applying ceramic layers of the shell mould to the
model set. The use of the rod
1 provided with the handle
4 of such a structure ensures secure fixing of the model set during the process of
applying and drying the ceramic layers of the shell mould in the machine carrying
out this process, while at the same time ensuring a permanent connection between the
rod
1 and a wax material
16 by means of the thread
3. The thread
3 also allows the rod
1 to be unscrewed from the wax material
16 prior to the operation of melting the model assembly from the shell mould, so that
the wax material
16 can be melted from the ceramic shell mould in a reverse-mould system and the unscrewed
rod can be used to build another model set.
[0015] The sleeve
2 is in the shape of a truncated cone turned with its wider end upwards, is preferably
ceramic, and acts as a pouring basin for the wax material
16 and metal - during the mould pouring process. It is provided with a flange
10, preferably with a top surface
17 perpendicular to the axis of the sleeve
2, located on its upper (longer) edge
11, as well as transverse grooves
12 and vertical ribs
13 on its lateral surface
18. This structure of the sleeve
2 allows a stable connection to the wax material
16, in particular when carrying the main gating assembly and fixing it on a robotic line
for applying ceramic coatings. The transverse grooves
12 on the outer surface of the sleeve
2 prevent the sleeve from falling out of the wax material
16 during lifting, and the vertical ribs
13 prevent the sleeve
2 from possible rotation. The shape of the sleeve
2 allows for an appropriate flow of the liquid metal stream into the produced ceramic
shell mould in both gravity and vacuum casting processes. The shape of the sleeve
2 also allows the main gating assembly to be fixed to the producing mould.
[0016] The main gating assembly can be provided with a foot
14, preferably made of ceramic or wax material. The foot
14 provides support for the main gating assembly in cases where it is particularly important
that the model set produced on the basis of this main gating assembly allows the shell
mould to be made thereon with accurate concentricity and verticality and thus perpendicularity
of the axis with respect to the plane of the ground, e.g. in the vacuum casting process
in apparatus with small dimensional tolerances. The maintenance of verticality and
concentricity is important in this case since deviation could result in the mould
hitting the wall of the furnace chamber. The obtained tolerances of concentricity,
deviations of position and perpendicularity thus ensure that the process of applying
individual layers of the ceramic mould is carried out correctly and reproducibly and
that a mould is obtained which, in the process of bottom-up vacuum casting, ensures
correct, concentric within the assumed tolerance, positioning of the mould in the
machine chamber. In other cases, the main gating assembly according to the invention
can be shaped in such a way that it does not topple, tilt or deviate from its axis
in the furnace by appropriately shaping the mould for receiving the main gating assembly.
The foot 14 in the embodiment has the shape of a truncated cone provided with three
flat supports 15.
1. A main gating assembly comprising an elongated rod (1) and a sleeve (2), characterised in that the rod (1) is provided at one end with a thread (3), preferably a metric triple
taper thread, and at the other end with a handle (4) provided with a circular hole
(8) with an axis perpendicular to the axis of the rod (1) and with a hexagonal tip
(9), and the sleeve (2) has the shape of a truncated cone turned with its wider end
upwards and is provided with a flange (10) located at the upper edge (11) of the sleeve
(2).
2. The main gating assembly according to claim 1, characterised in that the rod is provided with a flange (5) located below the handle (4).
3. The main gating assembly according to claim 1, characterised in that the rod (1) is provided with a rim (6) located above the thread (3).
4. The main gating assembly according to claim 1, characterised in that the flange (10) of the sleeve (2) has a top surface (17) perpendicular to the axis
of the sleeve (2).
5. The main gating assembly according to claim 1, characterised in that the lateral surface (18) of the sleeve (2) has transverse grooves (12).
6. The main gating assembly according to claim 1, characterised in that the lateral surface (18) of the sleeve (2) has vertical ribs (13).
7. The main gating assembly according to claim 1, characterised in that it is provided with a foot (14), preferably in the shape of a truncated cone provided
with flat supports (15).