EP4076786B1

EP4076786B1 - Machine for melting and injecting metal material into a mold for manufacturing lost wax casting objects and relative method

Info

Publication number: EP4076786B1
Application number: EP19856420.5A
Authority: EP
Inventors: Gianluigi BARETTONI
Original assignee: Unicast Srl
Current assignee: Unicast Srl
Priority date: 2019-12-16
Filing date: 2019-12-16
Publication date: 2023-10-25
Anticipated expiration: 2039-12-16
Also published as: WO2021124360A1; EP4076786A1

Description

. Field of the invention

. The present invention refers to a machine for melting and injecting metal material in a mold for the manufacture of lost wax casting objects and relative method.

. Background art

. Machines are known, also named "melters", for the microcasting by die-casting a metal material (e.g. silver, gold, platinum, bronze, brass) and the successive injection of the molten metal material into a mold for manufacturing objects by lost wax casting, e.g. in the field of jewelry and costume jewelry but also dentistry.
. "Mold" means a block of refractory material, typically cylindrical in shape, laterally lined with a steel coating and having an injection cone on the top, which is the inlet of a so-called injection or casting cavity formed inside the mold itself.
. Typically, such a casting cavity has a "cluster" structure consisting of a conical-frustum-shaped conveying element ("sprue bottom") and a central channel ("main sprue") which extends vertically along the longitudinal extension axis of the cylinder and a number of secondary casting cavities, each of which extends from the central channel along a downward inclined direction so as to facilitate filling with the molten metal.
. The shape of the free end of each secondary casting cavity corresponds to that of an object to be manufactured.
. The junction part between the free end of each secondary casting cavity and the central channel is a secondary channel ("feeding sprue").
. A machine or "melter" typically consists of an upper chamber and a lower chamber in which the upper chamber is arranged above the lower chamber.
. The upper chamber contains a graphite crucible in which the metal material to be melted, e.g. by induction or electrical resistance, is housed.
. The upper chamber is provided with a hermetically sealed cover following the application of which pressure is created inside it by means of inert gas.
. The crucible has a hole on the bottom, the opening and closing of which is obtained by means of a movable shutter.
. The opening of the crucible hole promotes the passage of molten metal from the upper chamber to the lower chamber.
. The lower chamber is adapted to house the mold inside and to be put under vacuum so as to promote the injection of the molten metal into the mold, by creating a pressure difference with respect to the upper chamber.
. In this regard, the mold is housed in the lower chamber so that the respective injection cone of the casting cavity is positioned coaxially to the crucible hole of the upper chamber.
. In this manner, the molten metal material can be injected directly from the crucible of the upper chamber into the mold housed in the lower chamber.
. Once the injection of the molten metal material into the mold has been completed and the solidification of the molten metal material has been completed, the mold is removed from the lower chamber, the refractory material is destroyed so as to release the "tree-shaped cluster" structure and the jewelry objects detached therefrom move onto the subsequent steps of processing which will complete the manufacture.
. The metal material solidified inside the central channel ("main sprue") and each secondary channel ("feeding sprue") is waste material.
. While the known type of machine described above allows a high productivity, due to a large number of objects which can be mounted on the tree, on the other hand, this machine has the limitation of having to use a large amount of metal, which is sometimes very precious, which is in all cases considered waste because it is the feeding metal needed to create the objects.
. Furthermore, the waste of valuable metal material at the end of solidification is apparent due to the structure of the casting cavity (injection cone, central channel and feeding sprues).
. Furthermore, in the microcasting machine of the known type, the casting temperatures of the metal and the mold play an important role in the quality of the cast objects, because they depend on the type of objects to be manufactured, which can have a significantly different mass from one another to the extent of requiring adequate temperature management.
. Indeed, the tree-like structure of the casting cavity may create problems in controlling the casting temperature because objects which require different temperatures of the metal material can be mounted, some pieces having a large mass or other pieces having a small mass, therefore with different temperature requirements.
. A difficult control of the casting temperature may further lead to an incomplete filling of the mold with the risk of compromising the quality and the homogeneity of karats of the precious metal material.
. It is worth noting that karats of a precious metal material means the mixing of pure metal (e.g. gold) with other metals, named alloys. According to the percentage of alloy mixed with the precious metal material, it is possible to obtain karats ranging from 9 karats (kt) to 18 karats (kt).
. Furthermore, the injection of large masses of metal into the casting cavity can create and generate turbulence and shrinkage inside the casting cavity due to the large quantity of the injected mass which, upon solidification, draws metal from objects which are external and normally of a lower mass than the main sprue.
. There are also a number of drawbacks to the manufacturing of the mold.
. First of all, the construction of the tree-shaped structure in wax to be embedded inside the refractory material takes a long time which inevitably impacts on the manufacturing time of the mold itself and requires specific skills on how to position and secure the objects through the feeding sprue onto the central main sprue.
. Subsequently, a very important step is coating the tree-shaped structure and the consequent curing of the refractory material itself.
. Afterwards, the extraction of the tree-shaped structure made of wax from the mold (also called dewaxing), once the refractory material has cured, is a delicate procedure because it is necessary to avoid burning the wax itself so as not to create oxides or carbon residues inside the refractory material.
. This problem is particularly felt when resins made by 3D prototyping machines, which have a casting temperature of about 70 °C, are used instead of wax.
WO 00/51761 A1 discloses a system for producing cast components from molten metal.
US 3,470,941 A discloses an apparatus for casting metal into each of a series of molds.

. Summary

. It is the object of the present invention to devise and make available a machine for melting and injecting metal material in a mold for the manufacture of lost wax casting objects which makes it possible to overcome at least partially the problems described above with reference to the prior art and in particular which guarantees a reduction of waste material, a reduction of execution times with consequent energy savings, greater reliability and quality of the finished objects despite a lower use of wax with consequent reduction in pollution and the emission of unpleasant odors and carbon residues inside the mold.
. Such an object is achieved by a machine according to claim 1.
. It is a further object of the present invention a method for melting and injecting metal material in a mold for the manufacture of lost wax casting objects. Such an object is achieved by the method of claim 16.
. It a further object of the present invention a mold which can be used on such a machine and a method for manufacturing such a mold. Such an object is achieved by the mold of claim 11 and the method of claim 15.

. Brief description of the figures

. Further features and advantages of the machine and the relative method according to the invention will be apparent from the following description which illustrates preferred embodiments, given by way of indicative, non-limiting examples, with reference to the accompanying figures, in which:

figures 1a, 1b and 1c show a perspective view, a front view and a front cross-section view of a machine for melting and injecting metal material in a mold for the manufacture of lost wax casting objects, according to an embodiment of the present invention, respectively;
figures 1d, 2 and 3 show a perspective view, a front view and a side view of a machine for melting and injecting metal material in a mold for the manufacture of lost wax casting objects, according to an embodiment of the present invention, respectively;
figures 4, 5 and 6 show a perspective view, a front view and a side view of the machine of figure 1d free of some components, respectively;
figures 7, 8 and 9 show a perspective view, a front view and a side view of the machine in figure 4 in which a mold is housed, respectively;
figure 10 shows an enlargement of figure 7;
figure 11 diagrammatically shows a component of the machine of figure 1d on which a mold is housed, according to an embodiment of the present invention;
figure 12a diagrammatically shows a component of the machine in figure 1d on which a mold is housed, according to a further embodiment of the present invention;
figure 12b diagrammatically shows a component of the machine in figure 1d on which several molds are housed, not according to the present invention;
figure 12c diagrammatically shows a component which can be used to manufacture the mold shown in figure 12a or one of the molds shown in figure 12b;
figure 13 diagrammatically shows an assembly for manufacturing a mold which can be housed in the machine shown in figure 1d, according to an embodiment of the present invention;
figure 14 shows a component which can be used for manufacturing a mold which can be housed in the machine shown in figure 1d, according to an embodiment of the present invention;
figures 15, 16 and 17 show a perspective view, a top view and a side view of the component of figure 14 with which are associated further components which can be used for manufacturing of a mold which can be housed in the machine of figure 1d, according to an embodiment of the present invention, respectively;
figure 18 shows a further component which can be used for manufacturing a mold which can be housed in the machine shown in figure 1d, according to an embodiment of the present invention;
figures 19 and 20 show a perspective view and a side view of an assembly in which the further component of figure 18 is associated with the component of figure 14 to which the further components shown in figures 15, 16 and 17 are associated in turn, respectively;
figure 21 shows a side view of the assembly in figures 19 and 20 in which a refractory material is inserted to obtain the mold which can be housed in the machine of figure 1d, according to an embodiment of the present invention;
figures 22 and 23 diagrammatically show a perspective view and a side cross-section view of a portion of the assembly of figure 21 in which the component of figure 14 has been removed and the other components associated with the component of figure 14, illustrated in figures 15, 16 and 17;
figures 24a, 24b, 24c and 24d diagrammatically show a perspective view, a side view, a side cross-section view and a top view of a component of a machine for melting and injecting metal material in a mold for the manufacture of lost wax casting objects, according to an embodiment of the present invention, respectively;
figures 25a, 25b, 25c and 25d diagrammatically show a perspective view, a side view, a side cross-section view and a top view of a component of a machine for melting and injecting metal material in a mold for the manufacture of lost wax casting objects, according to an embodiment of the present invention, respectively;
figure 26 shows, by means of a block chart, a method for melting and injecting metal material in a mold for the manufacture of lost wax casting objects, according to an embodiment of the invention.

. It is worth noting that equal or similar elements in the figures will be indicated by the same numeric or alphanumeric references.

. Description of some preferred embodiments

. With reference to figures 1a-1d and 2-10, reference numeral 100 indicates as a whole a machine for melting and injecting metal material in a mold for the manufacture of lost wax casting objects, hereinafter also simply melting and injecting machine or simply machine, according to an embodiment of the present invention.
. The objects that can be manufactured by lost wax casting with the machine 100 may be, for example, in the field of jewelry and costume jewelry but also in that of dentistry.
. It is worth noting that hereafter in the following description "objects that can be manufactured by lost wax casting (microcasting)" will also be simply called "objects".
. In this regard, the metal material may be chosen according to the applications, e.g. silver, gold, platinum, bronze, brass for jewelry and costume jewelry, gold for dentistry.
. The machine 100 comprises a controller 1, e.g. a programmable logic controller PLC (from the acronym, Programmable Logic Controller).
. The controller 1 is diagrammatically shown by a square in the figures and placed, for simplicity and greater clarity of the figures, outside the machine 100.
. The controller 1 comprises a central processing unit 2, e.g. a microcontroller or a microprocessor, and a memory unit 3, which is operationally connected to the central processing unit 2.
. The memory unit 3 may be internal (as diagrammatically shown in figures 1c-9) or external to the central processing unit 2 (embodiment not shown in figures).
. The controller 1, by loading and executing, by the central processing unit 2, of one or more program codes, stored in the memory unit 3, is configured to automatically control the operation of the machine 100.
. According to an embodiment, diagrammatically shown in figures 1a, 1b, 1c, the machine 100 further comprises an operator panel 3', operationally connected to the controller 1, adapted to allows an operator to interact with the machine 100, e.g. to impart commands and/or to set operating parameters and display information representative of the machine 100 and such parameters, e.g., before, during and/or after operation.
. By way of example, the operator panel 3' may be a touchscreen display.
. According to the invention, the machine 100 further comprises a melting chamber 4, operationally connected to the controller 1.
. In more detail, with particular reference to figures 4-10, the melting chamber 4 comprises a crucible 5 adapted to contain metal material (the latter is not shown in the figures).
. The crucible 5 comprises at least one dispensing hole 5' of the molten metal material (e.g. see figures 24a, 24c and 25a, 25c).
. In this regard, the melting chamber 4 further comprises an induction generator 4', also diagrammatically shown by a square in the figures and placed, for the sake of simplicity and greater clarity of the figures, outside the machine 100.
. The induction generator 4', operationally connected to the controller 1, is adapted to melt, controlled by the controller 1, the metal material present inside the crucible 5 at a set casting temperature.
. The controller 1 is configured to control the melting temperature, which depends on the metal material to be melted.
. The temperature inside the melting chamber 4 is controlled by the controller 1, e.g. by using a thermocouple, not shown in the figures, operationally associated with the melting chamber 4 and to the controller 1.
. By way of example, values of the set melting temperature can generally be between about 980 °C - 1300 °C and, in the case of platinum, exceptionally from 1700 °C.
. The induction generator 4' may be of the low-frequency type, for most metal materials with melting temperatures from 980 °C to 1300 °C, or of the high-frequency type for metal materials, such as platinum, which require temperatures above 1700 °C to be reached.
. An operating frequency range of the low-frequency induction generator is, for example, 7.5 to 21.5 kHz or 19.5 to 53.5 kHz.
. Turning back to the controller 1, it is configured to regulate the dispensing of the molten metal material from said at least one dispensing hole 5' of the crucible 5 of the melting chamber 4.
. It is worth noting that the crucible 5 is made of conductive material, e.g. graphite, which, in turn, is immersed in refractory material, e.g. ceramic material.
. The choice of the conductive material and the choice of the refractory material depend on the metal material to be melted.
. In the case of metal materials with melting temperatures from 980°C to 1300°C, the induction generator 4' is of the low-frequency type and the low-frequency induction makes the graphite of the crucible 5 incandescent, which transmits the temperature to the metal material by contact.
. In the case of metal materials, such as platinum, with a melting temperature above 1700 °C, the induction generator 4' is of the high-frequency type and the high-frequency induction will directly heat the metal material inside the crucible 5, which will be made of ceramic material.
. With reference now to the embodiments shown in figures 24a-24d and 25a-25d, the crucible 5 comprises a first portion 6a of substantially cylindrical shape delimited by a respective first side wall 6a' and a second portion 6b of substantially cylindrical shape delimited by a respective second side wall 6b'.
. The diameter of the first portion 6a is greater than the diameter of the second portion 6b.
. The first portion 6a and the second portion 6b are connected to each other by a connecting portion 6c having, along the longitudinal development axis of the crucible 5, indicated by a dotted line and by reference G, a decreasing trend from the diameter of the first portion 6a of the crucible 5 to the diameter of the second portion 6b of the crucible 5.
. The second portion 6b of the crucible 5 is closed below by a flat lower wall 7, which is substantially transverse to the longitudinal development axis G of the crucible 5.
. The first portion 6a of the crucible 5 is instead open at the top so as to define a feeding opening 8 for introducing the metal material to be melted inside the crucible 5.
. The at least one dispensing hole 5' of the molten metal material is defined in the flat bottom wall 7 of the crucible 5.
. The at least one dispensing hole 5' has a set diameter, e.g. 1.5 mm, chosen according to the molten metal material to be dispensed.
. It is worth noting that the at least one dispensing hole 5' is fundamental to determine the dispensing times of the molten metal material.
. In an embodiment, shown in figures 24a-24d, the at least one dispensing hole 5' is defined directly on the flat lower wall 7 of the crucible 5.
. In a further embodiment, alternative to the preceding one and shown in figures 4-10, 25a-25d, the at least one dispensing hole 5' is defined in a nozzle 9 which extends parallel to the longitudinal development axis G of the crucible 5, starting from the flat lower wall 7 of the crucible 5.
. According to an embodiment, in combination with the preceding one, the nozzle 9 is conical-frustum-shaped adapted to taper away from the flat lower wall 7.
. Turning back to the crucible 5 in general, in an embodiment, in combination with any of the preceding ones, the first portion 6a, the connecting portion 6c and the second portion 6b have an inner profile having, along the longitudinal development axis G of the crucible 5, a conformation such as to guarantee a maximum dispensing speed of the molten metal material from said at least one dispensing hole 5', and thus the same pressure of the molten metal material inside the crucible 5 during the dispensing, when the metal material itself decreases.
. With reference again to figures 1d-3, according to an embodiment, in combination with any of those described above, the melting chamber 4 comprises a respective side wall 10 and a respective cover 11 suited for hermetically sealing the melting chamber.
. In an embodiment, in combination with any one of those described above, the controller 1 is further configured to control the atmosphere in the melting chamber 4 by releasing neutral gas, e.g. argon.
. This advantageously makes it possible, on the one hand, to eliminate possible oxidations of the molten metal material and, on the other hand, to create a set pressure inside the melting chamber 4 to control the dispensing of the molten metal material from at least one dispensing hole 5' of the crucible 5.
. Turning back to the machine 100 in general shown in figures 1a-10, it also comprises an injection chamber 12, operationally connected to the controller 1, of the molten metal material.
. "Injection" of molten metal material means both the actual injection and the simple casting of molten metal material.
. Hereinafter, reference will therefore be made to "injection" of molten metal, bearing in mind that it means the injection itself or the casting.
. With particular reference to figures 4-10, the injection chamber 12 is adapted to receive the molten metal material which can be dispensed from the melting chamber 4 into an injection point 13 associated with a mold 14 of objects for lost wax casting (microcasting) which can be housed inside the injection chamber 12.
. For the purposes of the present description, it is reiterated that "mold" means a block of refractory material, typically cylindrical in shape, laterally lined by a steel coating and having one or more injection cones on the top, each of which represents the inlet of a so-called injection or casting cavity formed inside the mold itself.
. A mold 14 of objects for casting will be described below according to different embodiments.
. In an embodiment, the injection chamber 12 comprises a casing 15 with an associated opening 16 to allow housing the mold 14 inside the injection chamber 12.
. The injection chamber 12 further comprises a respective cover 17, which is adapted to hermetically seal the injection chamber 12.
. In an embodiment, in combination with any of those described above, the controller 1 is configured to control the atmosphere in the injection chamber 12 by releasing neutral gas, e.g. argon.
. In an embodiment, in combination with the preceding one, the controller 1 is configured to control the temperature inside the injection chamber 12 in order to maintain a set temperature of the mold 14 which can be housed inside the injection chamber 12.
. In this regard, in an embodiment, in combination with the preceding one, the injection chamber 12 comprises heating resistors (not shown in the figures).
. Turning back to the machine 100 in general in figures 1a-10, the injection chamber 12 comprises a support 18, operationally connected to the controller 1, configured to house one mold 14 of objects for lost wax casting, each with associated one or more injection points 13 defining a plurality of injection points 13.
. The support 18 is adapted to rotate about a respective rotation axis A1, diagrammatically illustrated by a dashed line in some figures.
. The controller 1, for each injection point of the plurality of injection points 13, is configured to:

actuate the rotation of the support 18 of said one or more molds 14 of objects about said rotation axis A1 to position in succession an injection point of said plurality of injection points 13 coaxially to said at least one dispensing hole 5' of the crucible 5 of the melting chamber 4;
block the rotation of said support 18;
enable the dispensing of the molten metal material from the crucible 5 of the melting chamber 4 to the said injection chamber 12.

. In an embodiment, in combination with the preceding one, the controller 1, for each injection point of the plurality of injection points 13, before actuating the rotation of the support 18, is configured to disable the dispensing of molten metal material from the crucible 5 of the melting chamber 4 to said injection chamber 12.
. In an embodiment, in combination with any one of those described above, the support 18 is adapted to translate along a direction parallel to the rotation axis A1 of the support 18.
. The controller 1, for each injection point of the plurality of injection points 13, before enabling the dispensing of the molten metal material from the crucible 5 of the melting chamber 4 to said injection chamber 12, is configured to move the support 18 along the direction parallel to the rotation axis A1 of the support 18 to take the injection point of the plurality of injection points 13 to said at least one dispensing hole 5' of the crucible 5.
. In this manner, it is advantageously possible to reduce as much as possible the distance between the at least one dispensing hole 5' of the crucible 5 and the injection point of the plurality of injection points 13 associated with the mold 14.
. If the crucible 5 is according to the embodiment in figures 24a-24d, the translation takes place to take the flat lower wall 7 of the crucible 5 into contact with the edge of the injection point of the plurality of injection points 13 so that at least one dispensing hole 5' of the crucible 5 faces the injection point, avoiding any contact between the crucible 5 and the inner part of the injection point.
. If, on the other hand, the crucible 5 is according to the embodiment of figures 25a and 25b, the translation takes place by bringing the flat lower wall 7 of the crucible 5 into contact with the edge of the injection point of the plurality of injection points 13 so that the nozzle 9 present in the flat lower wall 7 of the crucible 5 is inside the injection point, possibly coming into contact with the inner part of the injection point.
. The use of the crucible 5 in the embodiment in figures 24a-24d, compared to the embodiment in figures 25a-25d, advantageously makes it possible to avoid the contact between the crucible and the inner part of the injection point, reducing possible problems which may be due to the accidental presence of molten metal material between the nozzle 9 and the inner wall of the injection point which could make it difficult to move away between the crucible 5 and the injection point.
. Furthermore, in a further embodiment, in combination with the preceding one, the controller 1, for each injection point of the plurality of injection points 13, before activating the rotation of the support 18, is configured to translate the support 18 along the direction parallel to the rotation axis A1 of the support 18 to move the injection point of the plurality of injection points 13 away from said at least one dispensing hole 5' of the crucible 5.
. In this manner, it is advantageously possible to promote the successive rotation of the support 18 of said one or more molds about the respective rotation axis A1.
. As mentioned above, the controller 1 is configured to regulate (enable/disable) the dispensing of the molten metal material from said at least one dispensing hole 5' of the crucible 5 of the melting chamber 4 to the injection chamber 12.
. In particular, according to an embodiment, the melting chamber 4 comprises a movable element 13' (shutter or stopper, visible and diagrammatically shown in figures 24c-24d and 25c-25d) for opening/closing the at least one dispensing hole 5' of the crucible 5, operationally connected to the controller 1.
. In greater detail, the machine 100 comprises a mechanism 13" (solenoid) (diagrammatically shown in the figures), operationally connected to the movable element 13' and to the controller 1, capable of moving the movable element 13'.
. In this regard, the controller 1, by acting on the mechanical 13" is configured to control the movement of a movable element 13' for opening/closing the at least one dispensing hole 5' of the crucible 5, to allow/block the dispensing of molten metal from the crucible 5 to the injection point of said plurality of injection points 13 associated with said one or more molds 14, respectively.
. As will be reiterated below, the controller 1, by acting on the mechanism 13", is also configured to time the movement of the movable element 13' for opening/closing the at least one dispensing hole 5' of the crucible 5 to allow/block the dispensing of molten metal material from the crucible 5 to the injection point of said plurality of 13 injection points associated with said one or more 14 molds for a set opening/closing time, respectively.
. The opening/closing times of at least one dispensing hole 5' of the crucible 5 may be the same or different for each injection point.
. According to the embodiments in figures 24a-24d and 25a-25d, the movement of the movable element 13' is a translation parallel to the longitudinal development axis G of the crucible 5.
. According to an embodiment, in combination with any of those described above, the controller 1 is configured to set an opening time of at least one dispensing hole 5'.
. In particular, the opening time of at least one dispensing hole 5' is set according to the dosage of molten metal material (i.e., the quantity of molten metal material) to be dispensed to an injection point of said plurality of injection points 13 with a single injection.
. For each injection point of the plurality of injection points 13, at the end of the opening time of the at least one dispensing hole 5' of the crucible 5, the controller 1 is further configured to actuate the rotation of the support 18 of said mold 14 of objects about said rotation axis A1 to position in succession an injection point of said plurality of injection points 13 coaxially with said at least one dispensing hole 5' of the crucible 5 of the melting chamber 4.
. In an embodiment, in combination with any one of those described above, the controller 1 is configured to determine the dosage of the molten metal material (i.e. the amount of molten metal material) to be dispensed into the mold 14 in a single injection, according to the features of the objects to be manufactured, such as size and weight.
. Furthermore, according to an embodiment, in combination with any one of the preceding ones, the controller 1 is configured to set, within the same cycle of successive injections, different opening times of at least one dispensing hole 5' of the crucible 5 for dispensing a set amount of molten metal material in the respective injection point of the plurality of injection points 13, necessary for a single injection.
. Furthermore, according to an embodiment, in combination with any of the above, the controller 1 is configured to set, within the same cycle of successive injections, a set dosage of molten metal material (i.e., the amount of molten metal material) to be dispensed in the mold 14 for each single injection.
. Such a set dosage may be different for each single injection or the same for some single injections but not for others.
. Furthermore, according an embodiment, in combination with any one of the preceding ones, the controller 1 is configured to enable, within the same cycle of successive injections, the dispensing of the molten metal material from the crucible 5 of the melting chamber 4 to said injection chamber 12 at set injection points of said plurality of injection points 13.
. For example, the controller 1 is configured to enable, within the same cycle of successive injections, the dispensing of the molten metal material from the crucible 5 of the melting chamber 4 to said injection chamber 12 at set injection points of said plurality of injection points 13 so as to alternate between injection points in which the injection takes place and injection points in which no injection takes place.
. Turning back to the support 18 in general, according to the invention, the support 18 is shaped to receive and retain a single mold 14 (e.g. see figures 10, 11, 12a, 13 and 22).
. The mold 14 comprises the plurality of injection points 13.
. It is worth noting that the plurality of injection points 13 is associated with the mold 14 so as to be mutually equidistant and have a distribution along a circumference.
. In this manner, a step-by-step rotation of the support 18 makes it possible to associate each injection point of said plurality of injection points 13 coaxially to said at least one dispensing hole 5' of the crucible 5.
. According to an embodiment not according to the invention, shown for example in figure 12b, as an alternative to the preceding one, the support 18 is shaped to receive and retain a plurality of molds 14.
. In this embodiment, each mold of said plurality of molds 14 comprises at least one injection point 13.
. Said at least one injection point 13 of each mold of the plurality of molds 14 defines the plurality of injection points 13.
. It is worth noting that the support 18 is configured to receive and retain, e.g. by means of special flanges defined in the support 18, the plurality of molds 14 so that the plurality of injection points 13 are mutually equidistant and have a distribution along a circumference.
. In this manner, the rotation of the support 18 makes it possible to associate each injection point of the plurality of injection points 13 coaxially to said at least one dispensing hole 5' of the crucible 5.
. According to an embodiment, in combination with any of those described above, shown in the figures, the support 18 comprises a plane 19 transverse to the rotation axis A1 of the support 18 and a respective containing edge 20, e.g. annular-shaped, extending from the plane 19 parallel to the rotation axis A1 of the support 18.
. The containment edge 20 of the support 18 is shaped so as to receive and retain mold 14 which can be housed on the support 18.
. This advantageously prevents said mold from moving and/or falling off the support 18.
. In greater detail, in an embodiment, the containing edge 20 of the support 18 comprises a notch 20', e.g. V-shaped (e.g. see figures 1d, 2, 4, 5, 7, 8, 10, 11, 12a).
. The notch 20' is designed to receive and retain (e.g. by means of a snapping connection) a respective relief of complementary shape (described below) protruding laterally from a hollow containment cylinder (described below) of the mold 14.
. In this manner, during the rotation of the support 18 about its rotation axis A1, the relative movement between the support 18 and the mold 14 housed in is advantageously inhibited.
. Furthermore, the engagement of the relief protruding laterally from the hollow containment cylinder of the mold 14 inside the slot 20' on the containment edge 20 of the support 18 advantageously makes it possible, from the moment in which a mold 14 is housed on the support 18, to associate one of the injection points of said plurality of injection points 13 coaxially to said at least one dispensing hole 5' of the crucible 5.
. In an embodiment, shown in the figures, in combination with any of those described above, the support 18 further comprises a rotating shaft 21 operationally connected to an electric motor 22 controllable by the controller 1 to turn the rotating shaft 21 about the rotation axis A1 of the support 18, thus the support 18 itself.
. According to an embodiment, shown in figures 1c-9, in combination with any of those described above, the machine 100 further comprises an air suction device 12', e.g. a vacuum pump, equipped with a valve (not shown in the figures), e.g. a solenoid valve, operationally connected to the controller 1.
. The air suction device 12' is operationally associated with the rotation shaft 21 of the support 18, below the support 18.
. In this embodiment, the controller 1, when the dispensing of the molten metal material from the crucible 5 of the melting chamber 4 to said injection chamber 12 is enabled, is configured to actuate the air suction device 12' under the support 18 of one or more molds 14 when molten metal material is dispensed to an injection point of the plurality of injection points 13.
. In greater detail, the controller 1 is configured to operate the air suction device 12' by controlling the valve of the air suction device 12'.
. This aspect advantageously promotes the filling of each cavity (described below) defined in the mold 14 at each injection point, because it allows to firstly release each cavity from the creep resistance of the molten metal material due to the compression of the air and to accelerate the filling times of each cavity by promoting the draught of the molten metal material inside each cavity.
. In an embodiment, in combination with the preceding one, shown by dashed lines in the figures, the machine 100 can comprise a plenum 12" (diagrammatically shown in figures 1d, 4, 7) between the air suction device 12' operationally associated with the rotation shaft 21 of the support 18, under the support 18.
. The plenum 12", operationally associated with the valve of the suction device 12', is configured to guarantee immediate and maximum vacuum.
. This allows the air suction device 12' to be conveniently in operation at all times.
. In this embodiment, the controller 1 is configured to operate the plenum 12", thereby ensuring maximum vacuum by controlling the valve of the air suction device 12'.
. In an embodiment, not shown in the figures and in combination with the preceding one, the rotation shaft of the support 18 is advantageously water-cooled in order to avoid the passage of heat, which is sometimes dangerous, to the suction device.
. With reference now in particular to figures 14-23, the components which can be used for manufacturing a mold which can be housed in the machine 100 are now described and, consequently, the manufacturing of a mold which can be housed in the machine 100, such as that shown in figure 11.
. Figure 14 shows a supporting base 30 made of flexible material, e.g. rubber, for manufacturing a mold.
. The supporting base 30 comprises a containment edge 31, e.g. annular-shaped.
. The supporting base 30 comprises a plurality of mutually equidistant conical-frustum-shaped elements 32 distributed along a circumference.
. Each conical-frustum-shaped element 32 has a corresponding hole 33 which extends longitudinally to the conical-frustum-shaped element.
. It is worth noting that each conical-frustum-shaped element 32 has a shape substantially complementary to that of the nozzle 9 present in the flat lower wall 7 of the crucible 5 of the melting chamber 4 according to the embodiment in figures 25a and 25b.
. The supporting base 30 further comprises a peg 31' extending vertically from the containment edge 31 of the supporting base 30.
. The peg 31' is arranged on the containment edge 31 of the supporting base 31 so that it is aligned, along a radial direction of the supporting base 30, with one of the elements of the plurality of elements 32.
. The peg 31' is adapted to engage with a respective relief protruding laterally from a hollow containment cylinder (described below) of the mold 14 so that, with the mold made, an injection point of the plurality of injection points 13 is radially aligned with the relief protruding laterally from the hollow containment cylinder of the mold 14.
. In this manner, as mentioned above, the successive engagement of the relief protruding laterally from the hollow containment cylinder of the mold 14 inside the slot 20' on the containing edge 20 of the support 18 advantageously makes it possible, from the moment in which a mold 14 is housed on the support 18, to associate one of the injection points of said plurality of injection points 13 coaxially to said at least one dispensing hole 5' of the crucible 5.
. With reference to figures 15, 16 and 17, each hole 33 is adapted to receive and retain a wax element 34, the shape of which corresponds to one or to a combination of objects that can be manufactured by casting.
. In the embodiment in figure 15, each wax element 34 has a shape corresponding to an object (e.g. a ring) with a pin 34' (also known as feeding sprue) for inserting into a respective hole 33 of the supporting base 30.
. In the embodiment in figure 13, each wax element 34 has a shape corresponding to several objects (e.g. three rings) with a pin 34' (also known as feeding sprue) for inserting into a respective hole 33 of the supporting base 30.
. In an embodiment, in combination with the above and shown for example in figures 15, 16 and 17, the supporting base 30 comprises an annular-shaped groove 35, arranged in the part of the base within the containment edge 31 of the supporting base 30 and substantially adjacent thereto.
. Figure 18, instead, shows a hollow containment cylinder 36, e.g. made of steel, which can be inserted into the supporting base 30.
. The diameter of the hollow containment cylinder 36 is such that it can be inserted into the supporting base 30 within the containment edge 31 of the supporting base 30 so that it is substantially adjacent thereto (e.g. see figures 13, 16 and 19).
. Furthermore, the hollow containment cylinder 36 comprises a relief 36' projecting laterally from said hollow containment cylinder 36.
. The shape of the relief 36' is complementary to the respective notch 20' defined on the containing edge 20 of the support 18' so that it can be received and withheld (e.g. by snap fitting) within said notch 20' (e.g. see figures 10 and 11).
. Furthermore, the shape of the relief 36' is such to be able to receive and retain therein the peg 31' present on the containment edge 31 of the supporting base 30 (e.g. see figures 16, 19 and 20).
. Turning back to figure 18, the height of the hollow containment cylinder 36 is preferably smaller than the diameter.
. In an embodiment, the hollow containment cylinder 36 can be punctured radially in order to facilitate the passage of air.
. In an embodiment, shown in the figures, the thickness of the hollow containment cylinder 36 is such that it can be partially inserted into the groove 35 defined in the supporting base 30.
. Figures 19 and 20 show an assembly in which the hollow containment cylinder 36 is inserted into the supporting base 30, particularly into the groove 35 defined in the supporting base 30.
. Furthermore, the hollow containment cylinder 36 is inserted inside the supporting base 30 so that the peg 31' present on the containment edge 31 of the supporting base 30 is received and withheld (e.g. by snap fitting) by the relief 36' protruding laterally from the hollow containment cylinder 36.
. The assembly shown in figures 19 and 20, the hollow containment cylinder 36 and the supporting base 30 with an associated plurality of wax elements 34, is adapted to be filled with coating material 37 of the mold 14, as shown in figure 21.
. The coating material 37 is a refractory material, e.g. a material in powder form (gypsum) based on cristobalite or quartz mixed under vacuum with water or other chemical components which, once inserted into the assembly of figures 19 and 20, is susceptible to curing and subsequently can be fired with a suitable thermal cycle at a temperature within the range of 700 °C - 900 °C.
. With reference to figures 14-23, it is now described a method 200 for manufacturing a mold 14 which can be used in a machine 100, like the one described above according to different embodiments.
. The method 200 comprises a step of providing 201 a supporting base 30 comprising a plurality of conical-frustum-shaped elements 32 mutually equidistant and distributed along a circumference, each conical-frustum-shaped element 32 having a respective through-hole 33 extending longitudinally with respect to the conical-frustum-shaped element (figure 14).
. It is worth noting that each conical-frustum-shaped element 32 has a shape substantially complementary to that of the nozzle 9 present in the base wall 7 of the crucible 5 of the melting chamber 4 (figure 14).
. The method 200 further comprises a step of inserting 202 in each through-hole 33 of each conical-frustum-shaped element 32 associated with the supporting base 30, a wax element 34 having a shape corresponding to one or to a combination of objects that can be manufactured by lost wax casting (ringshaped, for example, in figures 15-17).
. In the example in figure 15, each wax element 34 has a pattern with a pin 34' (feeding sprue) inserted in its respective through-hole 32.
. A method 200 further comprises a step of inserting 203 a hollow containment cylinder 36 into the support base 30 (figures 16, 18, 19, 20).
. In an embodiment, the hollow containment cylinder 36 is inserted into an annular-shaped groove 35, arranged in the part of the supporting base 30 within the containment edge 31 and substantially adjacent thereto (figures 17 and 20).
. Furthermore, in this embodiment, the hollow containment cylinder 36 is inserted inside the supporting base 30 so that a peg 31' present on the containment edge 31 of the supporting base 30 is received and retained (e.g. by snap fitting) by a relief 36' protruding laterally from the hollow containment cylinder 36 (figures 19 and 20).
. In an embodiment, the hollow containment cylinder 36 can be punctured radially in order to facilitate the passage of air.
. In an embodiment, shown in the figures, the thickness of the hollow containment cylinder 36 is such that it can be partially inserted into the groove 35 defined in the supporting base 30.
. Figures 19 and 20 show an assembly in which the hollow containment cylinder 36 is inserted into the supporting base 30, particularly into the groove 35 defined in the supporting base 30.
. The method 200 further comprises a step of filling 204 the assembly comprising the hollow containment cylinder 36 and the supporting base 30 with the plurality of wax elements 34 associated therewith, with an coating material 37 of a mold (figure 21).
. An example of coating material 37 has already been described above.
. The method 200 further comprises a step of removing 205 the supporting base 30 (figure 22).
. The plurality of wax elements 34 remains within the coating material 37.
. The removal of the supporting base 30 makes it possible to make available a plurality of conical-frustum-shaped recesses 38, complementary to the plurality of conical-frustum-shaped elements 32 present on the supporting base 30, representative of the plurality of injection points 13 which can be defined on the mold 14.
. It is worth noting that the plurality of conical-frustum-shaped recesses 38, i.e. the plurality of conical-frustum-shaped elements 32, may also have mutually different taper ratio.
. Subsequently, the method 200 comprises a step of melting 206 the plurality of wax elements 34 within the coating material 37 (figures 22 and 23).
. The step of melting 206, also known as step of dewaxing, takes place, for example, by subjecting the assembly comprising the hollow containment cylinder 36 and the coating material 37 with the plurality of wax elements 34 inside to further steaming or to a set temperature, for example of 200°C.
. Such a set temperature is suited to promote the most uniform and complete melting of the wax and the exiting from the through holes to eliminate carbon residues inside the mold 14.
. It is worth noting that the wax is evacuated from the coating material 37 from the plurality of conical-frustum-shaped recesses 38 associated with the coating material 37.
. Following the melting of the wax elements, the coating material 37 comprises inside a plurality of cavities 39, each of a shape corresponding to an object which can be manufactured by lost wax casting and associated, by means of a respective duct 40, with a conical-frustum-shaped recess of the plurality of conical-frustum-shaped cavities 38.
. It is worth noting that the plurality of conical-frustum-shaped recesses 38 represents the plurality of injection points 13 of the mold 14 for dispensing the molten metal material.
. Once the plurality of wax elements 34 have been melted, the method 200 comprises a step of firing 207 the coating material 37 with a thermal cycle at a set temperature, e.g. in the range of 700 °C to 900 °C (figures 22 and 23).
. The combination of the coating material 37 and the hollow containment cylinder 36 defines the mold 14 which can be used in the machine 100 which is the object of the present invention, e.g. shown in figures 22 and 23, but also visible in figures 10, 11, 12a, 12b and 13.
. The mold 14 comprises a plurality of injection points 13 mutually equidistant and distributed substantially along a circumference.
. Each injection point 13 is defined by a recess of a plurality of recesses 38, e.g. conical-frustum-shaped, associated with a cavity of a plurality of cavities 39, via a respective main duct 40.
. In an embodiment, in combination with the preceding one, shown in figures 11, 22 and 23, each cavity of the plurality of cavities 39 has a shape corresponding to an object which can be manufactured by lost wax casting.
. As mentioned above, it is worth noting that a wax element 34 which can be used for manufacturing a mold 14 may have a shape corresponding to one or a combination of objects to be manufactured by lost wax casting.
. In figures 15-17, according to an embodiment, each wax element 34 has a shape corresponding to an object to be manufactured by lost wax casting, e.g. a ring.
. Consequently, the mold 14 which can be manufactured from such a plurality of wax elements has a plurality of recesses 38, e.g. conical-frustum-shaped, each associated with a cavity of a plurality of cavities 39, having a shape corresponding to an object which can be manufactured by lost wax casting, through a respective main duct 40 (e.g. see figures 11, 22, 23).
. According to a further embodiment, one or more wax elements 34 can have a shape corresponding to several objects to be manufactured by lost wax casting.
. Consequently, the mold 14, which can be manufactured from such a plurality of wax elements, has a plurality of recesses 38, e.g. conical-frustum-shaped, each associated with a cavity of a plurality of cavities 39, having a shape corresponding to several objects that can be manufactured by lost wax casting, through a respective main duct 40.
. Furthermore, the mold 14 which can be manufactured from an aforesaid plurality of wax elements may have a plurality of cavities 38, e.g. conical-frustum-shaped, each associated with a cavity of a plurality of cavities 39, wherein some cavities may have a shape corresponding to an object which can be manufactured by lost wax casting, by means of a respective main duct 40, while other cavities may have a shape corresponding to multiple objects that can be manufactured by lost wax casting, by means of a respective main duct 40.
. An example of such a mold can be obtained from an assembly as shown in figure 13.
. According to a further embodiment, either alternatively or in combination with the preceding one, in order to obtain the mold shown in figure 12a, each wax element 34 has a structure comprising a main element (main sprue) to which a plurality of secondary elements are fixed in a "tree" or "cluster" shape, each with a shape corresponding to one or to a combination of objects that can be manufactured by lost wax casting.
. Each secondary element of said plurality of secondary elements is fixed to the main element or to another secondary element of said plurality of secondary elements by means of a respective pin (feeding sprue).
. Following removal of the supporting base and of the melting of the wax, the mold 14, in the coating material 37 coated by the hollow containment cylinder 36, comprises a plurality of recesses 38, e.g. conical-frustum-shaped, each associated with a cavity of a plurality of cavities 39, through a main duct 40.
. Each cavity of said plurality of cavities 39 comprises a plurality of secondary cavities 39', each having a shape corresponding to an object which can be manufactured by lost wax casting, each connected by a respective secondary duct 40' to the main duct 40.
. It is worth noting that, again, in this case, the plurality of conical-frustum-shaped recesses 38 represent the plurality of injection points 13 of the mold 14 for dispensing the molten metal material.
. It is reiterated that, if the crucible is according to the embodiment of figures 24a-24d, the flat lower wall 7 of the crucible 5 will come into contact with the upper edge of each recess of the plurality of recesses 38 thereby avoiding any contact between the crucible 5 and the inner part of each recess of the plurality of recesses 38, advantageously promoting the moving of the crucible 5 away from each conical-frustum-shaped element 32 after injection occurred.
. If the crucible 5 in the embodiment of figures 25a and 25b is used, it is instead the nozzle 9 of the flat lower wall 7 of the crucible 5 which will come into contact with the inner part of each recess of the plurality of recesses 38.
. It is reiterated that the coating material 37 with the hollow containment cylinder 36 defines the mold 14 which can be used in the machine 100 which is the object of the present invention, according to a further embodiment, shown in figure 12a.
. In an embodiment, in combination with any of those described above, the mold 14 has a substantially cylindrical shape with a diameter greater than the height.
. With reference to figure 12b, not according to the invention, the manufacturing of a mold of the plurality of molds 14 shown in such a figure provides the use of a supporting base with a single central conical-frustum-shaped element placed in the middle of the base.
. The conical-frustum-shaped element has a corresponding through-hole which extends longitudinally to the conical-frustum-shaped element.
. It is worth noting that each central conical-frustum-shaped element has a shape substantially complementary to that of nozzle 9 present in the flat lower wall of the crucible 5 of the melting chamber 4 if the crucible 5 of the embodiment shown in figures 25a and 25b is used.
. The through-hole of the central conical-frustum-shaped element can receive and retain a wax structure comprising a main element (main sprue), which extends substantially vertically from the central truncated-cone element, to which a number of secondary elements are attached in a "tree" or "cluster" shape, each having a shape corresponding to one or to a combination of objects that can be manufactured by lost wax casting.
. Each secondary element of said plurality of secondary elements is fixed to the main element or to another secondary element of said plurality of secondary elements by means of a respective pin (feeding sprue).
. A hollow containment cylinder is associated with the supporting base for manufacturing of one of the molds shown in figure 12b.
. Such a hollow containment cylinder has a diameter such that it can be inserted into the supporting base and preferably has a height greater than the diameter.
. The assembly comprising the hollow containment cylinder associated with the supporting base with the wax frame described above inserted is filled with mold coating material.
. The supporting base is removed by making accessible a central conical-frustum-shaped recess 50 complementary to the central conical-frustum-shaped element present on the supporting base (injection point 13 defined on the mold 14, figure 12b).
. The wax structure is melted within the coating material (dewaxing).
. In this case, the evacuation of the wax from the coating material occurs through the central conical-frustum-shaped recess associated with the coating material.
. Following the melting of the wax structure, the assembly comprising the hollow containment cylinder and the coating material is fired with a thermal cycle at a set temperature.
. At the end of firing, the coating material comprises a main cavity 51, corresponding to the main element of the wax structure, and a number of secondary cavities 52, each of a shape corresponding to an object which can be manufactured by casting and associated, through a respective duct 53, with the main cavity 51 or another secondary cavity of said number of secondary cavities.
. It is worth noting that the central conical-frustum-shaped recess 50 represents the injection point 13 of the mold 14 for the dispensing of the molten metal material.
. The assembly comprising the hollow containment cylinder and the coating material defines the mold 14, not according to the invention, which can be used in the machine 100, shown in figure 12b.
. Such a mold 14 comprises an injection point 13.
. Such an injection point 13 is defined by a central recess 50, e.g. conical-frustum-shaped, associated with a main cavity 51 with which a number of secondary cavities 52 are associated, each having a shape corresponding to an object which can be manufactured by casting, by means of a respective duct 53 (figure 12b).
. In this case, the mold 14 has a substantially cylindrical shape with a diameter smaller than the height.
. It is worth noting that if the crucible 5 used is the one of the embodiment in figures 24a-24d, the flat lower wall 7 of the crucible 5 will come into contact with the edge of the central recess 50 so that at least one dispensing hole 5' of the crucible 5 will face the central recess 50, thereby avoiding any contact between the crucible 5 and the inner part of the central recess 50 of the mold 14.
. If, on the other hand, the crucible 5 is used in the embodiment in which figures 25a and 25b are produced, the flat lower wall 7 of crucible 5 will come into contact with the edge of the central recess 50 so that the nozzle 9 of the crucible 5 comes into contact with the inner part of the central recess 50 of the mold 14.
. With reference to the preceding figures and also to figure 26, a method 60 for melting and injecting metal material into a mold for manufacturing objects by lost wax casting (microcasting), hereinafter also simply melting and injecting method or simply method, according to an embodiment of the present invention will be described.
. The method 60 comprises a symbolic step of starting ST.
. The method 60 comprises a step of providing 61 a controller 1, e.g. a programmable logic controller PLC (from the acronym, Programmable Logic Controller).
. The controller 1 was described above.
. The method 60 further comprises a step of providing 62 a melting chamber 4, operatively connected to the controller 1.
. The melting chamber 4 comprises a crucible 5 adapted to contain metal material (not shown in the figures).
. Examples of metal material were described above.
. The crucible 5 comprises at least one dispensing hole 5' of the molten metal material.
. The melting chamber 4 further comprises an induction generator 4', already described above, operationally connected to the controller 1.
. The method 60 comprises a step of melting 63, by the induction generator 4' of the melting chamber 4, under the control of the controller 1, the metallic material inside the crucible 5 of the melting chamber 4 at a set melting temperature.
. The melting chamber 4 and the crucible 5 were described in detail above, according to different embodiments.
. As mentioned above, the controller 1 is configured to control the melting temperature, which depends on the metal material to be melted.
. The temperature inside the melting chamber 4 is controlled by the controller 1, e.g. by using a thermocouple, not shown in the figures, operationally associated with the melting chamber 4 and the controller 1.
. Numerical examples of melting temperatures have already been provided.
. The method 60 further comprises a step of providing 64 an injection chamber 12, operatively connected to the controller 1.
. The injection chamber 12 is adapted to receive the molten metal material which can be supplied from the melting chamber 4 in an injection point 13 associated with a mold 14 of objects that can be manufactured by lost wax casting, which can be housed in the injection chamber 12.
. The method 60 further comprises a step of housing 65 one or more molds 14 of objects that can be manufactured by lost wax casting, each one associated with one or more injection points 13 defining a plurality of injection points 13, on a support 18 in the injection chamber 12, operatively connected to the controller 1.
. The support 18 is adapted to rotate about a respective rotation axis A1, diagrammatically illustrated by a dashed line in some figures.
. The method 60, for each injection point of the plurality of injection points 13, comprises steps of:

activating 66, by the controller 1, the rotation of the support 18 of said one or more molds 14 of objects about said rotation axis A1 to position in succession an injection point of said plurality of injection points 13 coaxially to said at least one dispensing hole 5' of the crucible 5 of the melting chamber 4;
blocking 67, by the controller 1, the rotation of said support 18;
enabling 68, by the controller 1, the dispensing of the molten metal material from the crucible 5 of the melting chamber 4 to the said injection chamber 12.

. The method 60 thus ends with a symbolic step of ending ED.
. In an embodiment, in combination with the preceding one, shown by dashed lines in figure 26, the method 60 comprises, for each injection point of the plurality of injection points 13, before the step of activating 66 the rotation of the support 18, a step of disabling 69, by the controller 1, the dispensing of molten metal material from the crucible 5 of the melting chamber 4 to said injection chamber 12.
. In an embodiment, in combination with any one of those described above, shown with dashed lines in figure 26, in which the support 18 is adapted to translate along a direction parallel to the rotation axis A1 of the support 18, the method 60 further comprises, for each injection point of the plurality of injection points 13, before the step of enabling 68 the dispensing of the molten metal material from the crucible 5 of the melting chamber 4 to said injection chamber 12, a step of translating 70, by the controller 1, the support 18 in a first direction along the direction parallel to the rotation axis A1 of the support 18 to take the injection point of the plurality of injection points 13 to said at least one dispensing hole 5' of the crucible 5.
. If the crucible 5 is according to the embodiment in figures 24a-24d, the translation takes place to take the flat lower wall 7 of the crucible 5 into contact with the edge of the injection point of the plurality of injection points 13 so that at least one dispensing hole 5' of the crucible 5 faces the injection point, avoiding any contact between the crucible 5 and the inner part of the injection point.
. If, on the other hand, the crucible 5 is according to the embodiment of figures 25a and 25b, the translation takes place by bringing the flat lower wall 7 of the crucible 5 into contact with the edge of the injection point of the plurality of injection points 13 so that the nozzle 9 present in the flat lower wall 7 of the crucible 5 is inside the injection point, possibly coming into contact with the inner part of the injection point.
. The use of the crucible 5 in the embodiment in figures 24a-24d, compared to the embodiment in figures 25a-25d, advantageously makes it possible to avoid the contact between the crucible and the inner part of the injection point, reducing possible problems which may be due to the accidental presence of molten metal material between the nozzle 9 and the inner wall of the injection point which could make it difficult to move away between the crucible 5 and the injection point.
. In a further embodiment, in combination with the preceding one, shown by dashed lines in figure 26, the method 60 comprises, for each injection point of the plurality of injection points 13, before the step of activating 66 the rotation of the support 18, a step of translating 71, by the controller 1, the support 18 in a second direction opposite to the first direction along the direction parallel to the rotation axis A1 of the support 18 to move the injection point of the plurality of injection points 13 away from said at least one dispensing hole 5' of the crucible 5.
. In an embodiment, in combination with any one of the those described above, shown by dashed lines in figure 26, the method 60 comprises a step of adjusting 72, by the controller 1, the dispensing of the molten metal material from said at least one dispensing hole 5' of the crucible 5 of the melting chamber 4 to the injection chamber 12.
. In particular, according to an embodiment, in combination with the preceding one, shown by dashed lines in figure 26, the step of adjusting 72 comprises a step of controlling 73 the movement, by the controller 1, of a movable element 13' (shutter or stopper) for opening/closing the at least one dispensing hole 5' of the crucible 5, operationally connected to the controller 1, associated with the melting chamber 4, to allow/block the dispensing of molten metal from the crucible 5 to the injection point of said plurality of injection points 13 associated with said one or more molds 14, respectively.
. According to an embodiment, in combination with the preceding one, shown by dashed lines in figure 26, for each injection point of the plurality of injection points 13, at the end of the opening time of the at least one dispensing hole 5' of the crucible 5, the method 60 comprises a step of activating 14, by the controller 1, the rotation of the support 18 of said one or more molds 14 of objects that can be manufactured by lost wax casting about said rotation axis A1 to position in succession an injection point of said plurality of injection points 13 coaxially to said at least one dispensing hole 5' of the crucible 5 of the melting chamber 4.
. At the end of the injection of molten metal material into each injection point of the plurality of injection points 13 associated with one mold (figure 11 or 12a) or with more molds (figure 12b) 14, until all the cavities present in the one or more molds are filled, one or more molds 14 are removed from the injection chamber 12 of the machine 100.
. At the end of the cooling of the injected molten metal material, the coating material is destroyed to release the metal structures inside from which the single objects to be subjected to the subsequent polishing and finishing processes will be obtained.
. In this regard, if a mold is used according to the embodiment in figure 11, 22 or 23, each structure made of metal material released from the mold will consist substantially of the object because, as waste material, there will be the conical-frustum-shaped base ("sprue bottom") and the pin ("feeding sprue") connecting the object to the conical-frustum-shaped base.
. Therefore, in this embodiment, the fact of not having a main pin (known as "main sprue") to which a plurality of objects are connected, through the respective pin, advantageously makes available, after the destruction of the coating material, the single objects already separated from one another which may be more quickly subjected to the subsequent steps of processing to obtain to the finished product.
. The hollow containment cylinder may be reused for another processing cycle once released from the coating material and the objects inside it.
. If a mold is used according to the embodiment in figure 11, 22 or 23, each structure made of metal material released from the mold will consist substantially of the object, a conical-frustum-shaped base ("sprue bottom") and a pin (feeding sprue) connecting the object to the conical-frustum-shaped base.
. Each pin (feeding sprue) and conical-frustum-shaped base represent the waste material in the manufacturing of the component which can be manufactured by lost wax casting.
. If, on the other hand, the mold in the embodiment of figure 12a or the molds not according to the invention in figure 12b is used, each structure made of metal material released from the single mold, an example of which, indicated by reference numerical 80, is shown in figure 12c, comprises a central conical-frustum-shaped base 81 (also known as "sprue bottom"), a main pin 82 (known as "main sprue") connected to the central conical-frustum-shaped base 81, a plurality of objects 83 and a plurality of secondary pins 84 ("feeding sprues"), each of which is capable of connecting an object 83 to the main pin 82.
. Each secondary pin 84 ("feeding sprue"), the main pin 82 ("main sprue") and the central conical-frustum-shaped base 81 is the waste material in the manufacturing of the component which can be manufactured by lost wax casting.
. The extremely small amount of waste material is a significant advantage of the use of the mold 14 according to the embodiment in figures 11, 22 or 23 in a manufacturing process of objects that can be manufactured by lost wax casting using the machine 100 which is the object of this invention, compared to the use of a mold such as the one shown in figures 12a and 12b.
. This clearly makes it possible, especially in the case of precious metal material, to have a significant advantage from the point of view of cost containment.
. Furthermore, the mold according to the embodiment of figure 11 has further advantages compared to the mold according to the embodiment in figures 12a and 12b.
. First of all, such a mold allows an injection of the metal material from the crucible substantially directed into a cavity having the shape of an object which can be manufactured by lost wax casting, thereby avoiding the channeling of the metal material through a main cavity and the subsequent ducts to reach the plurality of secondary cavities each having the shape of an object which can be manufactured by lost wax casting.
. The fact that the main channel and the corresponding recess have been removed drastically saves metal material since it is no longer necessary to form the main channel ("main sprue") and the corresponding central truncated-conical base ("sprue bottom") is minimized.
. In this regard, it has been calculated that the saving of metal material in the use of the mold of the embodiment of figures 11, 22 or 23 and of a mold according to the embodiment of figures 12a or 12b, equal to a value between 30% and 50% with the same number of objects to be manufactured by lost wax casting.
. As mentioned above, the waste material obtained when using the mold according to the embodiment of figure 11, 22 or 23 is significantly lower than the waste material obtained when using the mold according to the embodiment of figures 12a or 12b.
. The reduction of waste of metal material, also of precious metal material, is also obtained by the fact that less so-called feeding metal material is needed, i.e. the metal material which guarantees the necessary thrust to the filling of the cavity having a shape of an object which can be manufactured by lost wax casting.
. The reduction of waste material makes it possible to proceed with injection and melting in a mold with little recycling of the previously molten metal material which is part of the waste material.
. This also makes it possible to advantageously avoid possible problems on subsequent meltings, precisely due to impurities from carbon residues as from coating residues incorporated in the melting or on the surface.
. The cause of poor melting due to the recycling of waste metal material is also the loss of the properties of the alloy that constitutes the melting.
. In the case of a precious metal material, e.g. gold, this results in a change of the so-called precious metal material title.
. Furthermore, in the mold according to the embodiment of figure 11, 22 or 23, the fact of having eliminated the main element makes it possible to avoid or at least reduce the faults and imperfections (porosity) caused by the shrinkage of the metal material that while cooling is attracted by the components of greater volume, and therefore possibly by the main element ("riser").
. Furthermore, by reducing the overall mass of metal material which can be used and by distributing the injection points, the quality problems associated with melting, which occur in the case of a single injection of a large mass of metal material, are reduced.
. Furthermore, the mold according to the embodiment of figure 11, 22 or 23, makes it possible to reduce problems regarding the temperature of the metal material to be injected.
. Indeed, if there are one or more main channels ("main sprues") to be filled, such as in the mold according to the embodiment in figure 12a or in the molds according to the embodiments in figure 12b, one is forced to keep the metal material at very high temperatures in order to be able to fill properly even cavities having very fine shape of objects which can be manufactured by lost wax casting (microcasting) (e.g. in the field of jewelry and costume jewelry).
. It is worth noting that very high temperatures can cause problems on very large objects at the surface level. Indeed, it has been shown that an excessive temperature can create major problems of micro-pores on bulky objects.
. In the mold according to the embodiment of figure 11, 22 or 23, there are separate cavities to be filled which can also be of different sizes.
. The fact that the molten metal can be injected into a single cavity at a time make it possible to adjust the melting temperature of each injection.
. Furthermore, the absence of a main channel and the substantial reduction in the size of a central recess make it possible to obtain a reduction of in the metal material due to turbulence which would be created, precisely, inside the main channel ("main sprue") and in the ducts ("feeding sprues") associated with it.
. Furthermore, the size of the mold, which has a larger diameter than the height, makes it possible to allow the temperature of the mold itself to be controlled at lower temperatures than those required for casting into a mold of the type shown in figure 12a or figure 12b, thereby reducing the problems of delayed cooling of the metal.
. Again, with reference to the shape of the mold according to the embodiment of figure 11, 22 or 23, having a diameter greater than the height, allows the reduction of waste of the coating material as it is possible to reduce the overall mass of the coating material itself.
. Furthermore, the shape of the mold according to the embodiment of figure 11, 22 or 23, offers a greater mass of the coating material to the heating, allowing a faster firing of the coating material, consequently reducing production time and costs.
. Furthermore, it is worth noting that the shape of the mold 14 according to the embodiment of figures 11, 22 or 23, essentially cylindrical with a diameter greater than the height, allows the possibility of subjecting to firing the refractory coating material with the axis of the hollow containment cylinder parallel to the support surface of the mold 14, therefore from both bases of the cylinder, reducing the firing time of the refractory coating material.
. According to an embodiment, the mold 14 can be housed in the support 18 so as to be subjected to a vertical upward and downward translation to allow the use of the center of the mold for the manufacture of objects even of large dimensions.
. It is worth noting that the object of the present invention is fully achieved.
. Indeed, the machine 100, according to the present invention, makes it possible to carry out several successive injections on the same mold inside the injection chamber, thus avoiding that an operator needs to submit one mold at a time to a single injection, which must be handled with caution both during positioning on the support and during withdrawal from the support.
. Furthermore, it is possible to control the temperature of the molten metal material inside the crucible over time in order to ensure adequate injection of the molten metal material into the mold, thereby preventing the formation of porosity or other defects in the solidified metal material.
. Furthermore, the machine 100 makes it possible to obtain a reduced consumption of a crucible in the light of the fact that the casting and the injection of the molten metal material take place continuously, with the possibility to inject multiple molds with a single charge of metal material.
. Being able to avoid as much as possible opening the melting chamber to feed the crucible with metal material to be melted, the possibility of the crucible consuming rapidly due to graphite oxidation at high temperatures is reduced, thereby improving the reliability of the machine and extending its operating life.
. Another advantage is related to the reduced firing time of the coating material (refractory material).
. Another advantage is related to the dewaxing, which is much faster and more efficient, even when resins or other plastics are used.
. Indeed, the resins tend to sublimate not to be poured.
. In traditional systems, sublimation is difficult because of the arrangement of the objects and the distance of the evacuation hole.
. In the present invention, the fact of having a cylinder with a diameter greater than the height makes it possible to overcome the drawbacks due to the dewaxing.
. In traditional systems, the large metal containment cylinder containing the refractory material acts as a screen and forces very long firing times (10 hours).
. According to the present invention, it is possible to orient the cylinder and irradiate towards the refractory material in order to reduce the firing times inside a firing kiln by up to 30% compared to the firing process with a traditional cylinder.
. A person skilled in the art may make changes and adaptations to the method and respective system described above or can replace elements with others which are functionally equivalent to satisfy contingent needs without departing from the scope of protection of the appended claims. All the features described above as belonging to one possible embodiment may be implemented independently from the other described embodiments, within the scope of the claims.

Claims

A machine (100) for melting and injecting metal material into a mold (14) for manufacturing lost wax casting objects, comprising:
- a controller (1);

- a melting chamber (4), operationally connected to the controller (1), comprising a crucible (5) adapted to contain metal material, the crucible (5) comprising at least one dispensing hole (5') for the molten metal material, the melting chamber (4) further comprising an induction generator (4'), operationally connected to the controller (1), the induction generator (4') being adapted to melt, controlled by the controller (1), the metal material inside the crucible (5) of the melting chamber (4) at a set melting temperature, the controller (1) being configured to adjust the dispensing of the molten metal material from said at least one dispensing hole (5') of the crucible (5) of the melting chamber (4);

- an injection chamber (12) operationally connected to the controller (1), adapted to receive the molten metal material which can be dispensed from the melting chamber (4) into an injection point (13) associated with a mold (14) of objects that can be manufactured by lost wax casting, which can be housed in the injection chamber (12), said injection chamber (12) comprising a support (18) configured to house one mold (14) of objects that can be manufactured by lost wax casting, associated with injection points defining a plurality of injection points (13) said support (18) being adapted to rotate about a respective rotation axis (A1);

- the controller (1), for each injection point of the plurality of injection points (13), is configured to:
- actuate the rotation of the support (18) of said one or more molds (14) of objects about said rotation axis (A1) to position in succession an injection point of said plurality of injection points (13) coaxially to said at least one dispensing hole (5') of the crucible (5) of the melting chamber (4);

- block the rotation of said support (18);

- enable the dispensing of the molten metal material from the crucible (5) of the melting chamber (4) to said injection chamber (12),

said machine (100) being characterized in that the support (18) is shaped to receive and retain only one mold (14), the mold (14) having a substantially cylindrical shape, the mold (14) comprising the plurality of injection points (13), the plurality of injection points (13) being associated with the mold (14) so as to be mutually equidistant and have a distribution along a circumference.
A machine (100) according to claim 1, wherein for each injection point of the plurality of injection points (13), the controller (1) is configured to disable the dispensing of molten metal material from the crucible (5) of the melting chamber (4) to said injection chamber (12) before actuating the rotation of the support (18).
A machine (100) according to any one of the preceding claims, wherein the support (18) is adapted to move along a direction parallel to the rotation axis (A1) of the support (18), the controller (1), for each injection point of the plurality of injection points (13), before enabling the dispensing of the molten metal material from the crucible (5) of the melting chamber (4) to said injection chamber (12), being configured to move the support (18) along the direction parallel to the rotation axis (A1) of the support (18) to bring the injection point of the plurality of injection points (13) to said at least one dispensing hole (5') of the crucible (5), the controller (1), for each injection point of the plurality of injection points (13), before actuating the rotation of the support (18), being configured to move the support (18) along the direction parallel to the rotation axis (A1) of the support (18) to move the injection point of the plurality of injection points (13) away from said at least one dispensing hole (5') of the crucible (5).
A machine (100) according to any one of the preceding claims, wherein for each injection point of the plurality of injection points (13), the controller (1) is configured to unlock the rotation of the support (18) before actuating the rotation of the support (18).
A machine (100) according to any one of the preceding claims, wherein the melting chamber (4) comprises a movable element (13') for opening/closing the at least one dispensing hole (5') of the crucible (5), operationally connected to the controller (1), the controller (1) being configured to control the movement of the movable element for opening/closing the at least one dispensing hole (5') of the crucible (5) to enable/disable the dispensing of molten metal from the crucible (5) to the injection point of said plurality of injection points (13) associated with said one mold (14).
A machine (100) according to any one of the preceding claims, wherein the controller (1) is configured to set an opening time of the at least one dispensing hole (5') as a function of the amount of molten metal to be dispensed in an injection point of said plurality of injection points (13) with a single injection, for each injection point of said plurality of injection points (13), at the end of an opening time of at least one dispensing hole (5') of the crucible (5), the controller (1) being configured to actuate the rotation of the support (18) of said one mold (14) of objects that can be manufactured by lost wax casting about said rotation axis (A1) to position in sequence an injection point of said plurality of injection points (13) coaxially with said at least one dispensing hole (5') of the crucible (5) of the melting chamber (4).
A machine (100) according to any one of the preceding claims, wherein the controller (1) is configured to set, within the same cycle of successive injections, different opening times of at least one dispensing hole (5') of the crucible (5) for the dispensing of a set amount of molten metal material in the respective injection point of the plurality of injection points (13), necessary for a single injection.
A machine (100) according to any one of the preceding claims, wherein the controller (1) is configured to set, within the same cycle of successive injections, a set dosage of the molten metal material to be dispensed into the mold (14) for each single injection, such set dosage being different for each single injection or the same for some single injections and different for others.
A machine (100) according to any one of the preceding claims, wherein the controller (1) is configured to enable, within the same cycle of successive injections, the dispensing of the molten metal material from the crucible (5) of the melting chamber (4) to said injection chamber (12) at set injection points of said plurality of injection points (13).
A machine (100) according to any one of the preceding claims, wherein which the controller (1) is configured to enable, within the same cycle of successive injections, the dispensing of the molten metal material from the crucible (5) of the melting chamber (4) to said injection chamber (12) at set injection points of said plurality of injection points (13) so as to alternate between injection points in which the injection takes place and injection points in which no injection takes place.
A mold (14) which can be used in a machine (100) for melting and injecting of metal material, the machine (100) being according to any one of the preceding claims from 1 to 10, the mold (14) having a substantially cylindrical shape, the mold (14) comprising a plurality of injection points (13) mutually equidistant and distributed substantially along a circumference, each injection point (13) being defined by a recess of a plurality of recesses (38) associated with a cavity of a plurality of cavities (39) through a respective duct (40).
A mold (14) according to claim 11, wherein the shape of each cavity of the plurality of cavities (39) corresponds to that of at least one object which can be manufactured by lost wax casting.
A mold (14) according to claim 11, wherein each cavity of said plurality of cavities (39) comprises a plurality of secondary cavities (39'), each having a shape corresponding to an object which can be manufactured by lost wax casting, each connected by means of a respective secondary duct (40') to the main duct (40).
A mold (14) according to any one of the preceding claims from 11 to 13, wherein said mold (14) has the substantially cylindrical shape having a diameter greater than the height.
A method (200) for manufacturing a mold (14) according to any of the preceding claims from 11 to 14, the method (200) comprising the steps of:
- providing (201) a supporting base (30) comprising a plurality of conical-frustum-shaped elements (32) mutually equidistant and distributed along a circumference, each conical-frustum-shaped element (32) having a respective through-hole (33) extending longitudinally with respect to the conical-frustum-shaped element;

- inserting (202) a wax element (34) having a shape corresponding to one object or to a combination of objects that can be manufactured by lost wax casting, in each through-hole (33) of each conical-frustum-shaped element (32) associated with the supporting base (30), each wax element (34) having a shape with a pin (34') inserted in the respective through-hole (32);

- inserting (203) a hollow containment cylinder (36) into the supporting base (30);

- filling (204) the assembly comprising the hollow containment cylinder (36) and the supporting base (30) with the plurality of wax elements (34) associated therewith, with a coating material (37) of a mold;

- removing (205) the supporting base (30).

- melting (206) the plurality of wax elements (34) in the coating material (37);

- firing (207) the coating material (37) with a thermal cycle at a set temperature.
A method (60) for melting and injecting metal material into a mold (14) for manufacturing objects that can be manufactured by lost wax casting, comprising steps of:
- providing (61) a controller (1);

- providing (62) a melting chamber (4), operationally connected to the controller (1), the melting chamber (4) comprising a crucible (5) adapted to contain metal material, the crucible (5) comprising at least one dispensing hole (5') of the molten metal material;

- melting (63), by an induction generator (4') of the melting chamber (4), controlled by the controller (1), the metal material inside the crucible (5) of the melting chamber (4) at a set melting temperature;

- providing (64) an injection chamber (12) operationally connected to the controller (1), the injection chamber (12) being adapted to receive the molten metal material which can be dispensed by the melting chamber (4) in an injection point (13) associated with a mold (14) of objects that can be manufactured by lost wax casting, which can be housed in the injection chamber (12);

- housing (65) on a support (18) in the injection chamber (12), operatively connected to the controller (1), one mold (14) of objects that can be manufactured by lost wax casting, associated with injection points (13) defining a plurality of injection points (13), said support (18) being adapted to rotate about a respective rotation axis (A1), the support (18) being shaped to receive and retain only one mold (14), the mold (14) having a substantially cylindrical shape, the mold (14) comprising the plurality of injection points (13), the plurality of injection points (13) being associated with the mold (14) so as to be mutually equidistant and have a distribution along a circumference; the method (60), for each injection point of the plurality of injection points (13), comprising steps of:

- actuating (66), by the controller (1), the rotation of the support (18) of said one or more molds (14) of objects about said rotation axis (A1) to position in succession an injection point of said plurality of injection points (13) coaxially with said at least one dispensing hole (5') of the crucible (5) of the melting chamber (4);

- blocking (67), by the controller (1), the rotation of said support (18);

- enabling (68), by the controller (1), the dispensing of the molten metal material from the crucible (5) of the melting chamber (4) to the said injection chamber (12).