阅读说明：本技术 用于熔融金属三维打印的打印头 (Printing head for three-dimensional printing of molten metal ) 是由 安德烈·瓦卡瑞 于 2019-01-24 设计创作，主要内容包括：本发明记载的用于熔融金属三维打印的打印头(1),包括空心的主体(2),主体(2)包括：-第一腔室(3),适于容纳熔融金属(4),在第一腔室(3)中形成有至少一个分配开口(5)；-第二腔室(9),适于容纳工作流体(10)并且连接至压力改变装置(11),压力改变装置(11)适于限定第一腔室(3)与第二腔室(9)之间的压力差；以及-分配组件(12、13),包括将第一腔室(3)和第二腔室(9)隔开的柔性的薄片元件(12),薄片元件(12)可通过第二腔室(9)中的压力变化而变形,薄片元件(12)的变形确定熔融金属(4)从分配开口(5)的流出。(The invention relates to a print head (1) for three-dimensional printing of molten metal, comprising a hollow main body (2), the main body (2) comprising: -a first chamber (3) suitable for containing a molten metal (4), at least one distribution opening (5) being formed in the first chamber (3); -a second chamber (9) adapted to contain a working fluid (10) and connected to pressure varying means (11), the pressure varying means (11) being adapted to define a pressure difference between the first chamber (3) and the second chamber (9); and-a dispensing assembly (12, 13) comprising a flexible sheet element (12) separating the first chamber (3) from the second chamber (9), the sheet element (12) being deformable by pressure variations in the second chamber (9), the deformation of the sheet element (12) determining the outflow of the molten metal (4) from the dispensing opening (5).)

1. Printhead (1) for three-dimensional printing of molten metal, characterized in that it comprises at least one hollow body (2), said body (2) comprising:

-at least one first chamber (3) suitable for containing at least one molten metal (4), at least one dispensing opening (5) being formed in said first chamber (3);

-at least one second chamber (9) adapted to contain at least one working fluid (10) and connected to pressure variation means (11), said pressure variation means (11) being adapted to define a pressure difference between said first chamber (3) and said second chamber (9); and

-at least one dispensing assembly (12, 13) comprising at least one flexible laminar element (12) separating a first chamber (3) and a second chamber (9), said laminar element (12) being deformable by pressure variations in said second chamber (9), the deformation of said laminar element (12) determining the outflow of said molten metal (4) from said dispensing opening (5).

2. Print head (1) according to claim 1, characterized in that said dispensing assembly (12, 13) comprises at least one dispensing element (13) housed in said first chamber (3), said dispensing element (13) being associated with said sheet element (12) and comprising at least one thrust portion (19) immersed in said molten metal (4) and arranged in proximity to said dispensing opening (5), the deformation of said sheet element (12) occurring between a first configuration in which said thrust portion (19) is arranged away from said dispensing opening (5) and a second configuration in which said thrust portion (19) is close to said dispensing opening (5), wherein the proximity of said thrust portion (19) to said dispensing opening (5) defines the outflow of said molten metal (4) from said dispensing opening (5) itself.

3. Print head (1) according to one or more of the preceding claims, characterized in that said laminar element (12) comprises at least one first face (14) facing said first chamber (3) and at least one second face (15) opposite said first face (14) and facing said second chamber (9) and is associated peripherally, in a non-removable manner, with at least one lateral wall (16) of said body (2) by welding means, said first chamber (3) and said second chamber (9) being isolated from each other in a fluidic manner.

4. A print head (1) according to claim 2 or 3, characterized in that the movement of the laminar element (12) between the first configuration and the second configuration is substantially periodic, the pressure varying means (11) being adapted to vary the pressure in the second chamber (9) substantially periodically at a predetermined frequency.

5. Print head (1) according to one or more of claims 2 to 4, characterized in that in the second configuration the laminar element (12) is substantially flat and in that in the first configuration the laminar element (12) is deformed to have a substantially curved shape.

6. Print head (1) according to one or more of claims 2 to 5, characterized in that said dispensing element (13) extends along at least one main direction (A) substantially perpendicular to at least one main plane (A-A) defined by said laminar element (12) in said second configuration, and is provided with at least one proximal portion (13b) associated with said first face (14) and at least one distal portion (13a) defining said thrust portion (19).

7. Printhead (1) according to one or more of claims 2 to 6, characterized in that said laminar element (12) in said first configuration substantially projects and bulges from the side of said second chamber (9) of said main plane (A-A), the dispensing element (13) being entrained in translation along the main direction (A) due to the deformation of said laminar element (12) in said first configuration.

8. Print head (1) according to one or more of the preceding claims, characterized in that said first chamber (3) is provided with heating means adapted to keep the temperature of said molten metal (4) substantially equal to a predetermined value.

9. Print head (1) according to one or more of the preceding claims, characterized in that said first chamber (3) contains an inert gas (8).

10. Print head (1) according to one or more of the preceding claims, characterized in that the transverse width (18) of the cross section of the dispensing opening (5) is between 1 μm and 50 μm.

11. Printhead (1) according to claim 10, characterized in that the lateral width (18) is between 10 μ ι η and 30 μ ι η.

12. Printhead (1) according to claim 10, characterized in that the lateral width (18) is equal to 20 μ ι η.

Technical Field

The invention relates to a printing head for three-dimensional printing of molten metal.

Background

It is known to use three-dimensional printheads mounted on special printing apparatus. These print heads allow for the creation of three-dimensional objects of various shapes without the use of a die.

Three-dimensional printing is done from a number of materials, even though in most cases, three-dimensional printers use polymeric materials that can be made into objects of interest by a special print head designed from a three-dimensional digital model in a molten state.

However, products require the use of materials other than polymers, such as metals, and therefore, in recent years, three-dimensional printing apparatuses designed for the use of metals have become increasingly popular.

In particular, such an apparatus is equipped with a special print head, allowing the molten metal to be distributed on a support surface according to a pre-established numerical model.

One example of a printhead for three-dimensional printing of molten metal is discussed in US9616494, which shows a printhead comprising a chamber containing a liquid conductive material surrounded by an electromagnetic coil.

The electromagnetic coil is electrically charged and determines the radial force on the conductive material towards the interior of the chamber.

The force applied causes a droplet to be ejected from the orifice, and a series of pulses causes a plurality of droplets to be ejected according to the program model, thereby forming an object.

However, this type of digital printing metal head does have a number of disadvantages.

The main drawback is related to the constructional complexity of the known print heads.

In fact, the above-mentioned print heads are characterized by a rather complex structure, since they are assembled from various components which cooperate with each other to distribute the molten metal.

However, the complexity of the structure negatively impacts the time required for assembly and routine maintenance, with a corresponding increase in cost.

Furthermore, the structural and operational complexity of the above-mentioned print heads for molten metal leads to a higher risk of failure, thus requiring special maintenance or replacement of the print heads.

Moreover, the operating temperatures are high and must be higher than the melting temperature of the metal used, so that it is necessary to use gaskets and sealing devices made of particularly high-temperature resistant materials.

However, the deterioration of the gasket is rapid, resulting in frequent replacement of the gasket, requiring disassembly and reassembly of the head, which increases the time and cost of maintenance operations.

Also, the known type of print head does not allow to control and dispense low flow rates, and therefore the precision of the deposition of the molten metal is limited.

Disclosure of Invention

A primary object of the present invention is to provide a three-dimensional printhead for molten metal having a simple structure.

Among the above objects, one of the objects of the present invention is to obtain a three-dimensional printing head for molten metal which allows to reduce the incidence of faults and therefore the specific maintenance costs associated therewith, compared to printing heads of known type.

Furthermore, it is an object of the present invention to make a print head for three-dimensional printing that allows to reduce the costs related to the assembly and the routine maintenance of the assembled printer.

Another object of the present invention is to obtain a print head for three-dimensional printing of molten metals which allows to make three-dimensional objects with high definition and precision.

Another object of the present invention is to provide a print head for three-dimensional printing of molten metal which is capable of overcoming the above-mentioned drawbacks of the prior art within the ambit of a simple, rational, easy, effective to use and cost-effective solution.

The aforementioned objects are achieved by a print head for three-dimensional printing of molten metal according to claim 1.

Drawings

Further characteristics and advantages of the invention will become better apparent from the description of a preferred but not exclusive embodiment of a printhead for three-dimensional printing of molten metal, illustrated by way of an illustrative but non-limiting example. In the drawings:

FIG. 1 is a schematic cross-sectional view of a printhead according to the present invention in an original configuration;

FIG. 2 is a cross-sectional view of a printhead according to the present invention in a first configuration;

fig. 3 is a cross-sectional view of a printhead according to the present invention in a second configuration.

Detailed Description

With particular reference to these figures, reference numeral 1 generally designates a print head for three-dimensional printing of molten metal.

The print head 1 for three-dimensional printing of molten metal comprises at least one hollow body 2, the hollow body 2 comprising at least one first chamber 3, the first chamber 3 being suitable for containing at least one molten metal 4, at least one dispensing opening 5 being formed in the first chamber 3 for dispensing the molten metal itself.

The print head 1 is suitable to be assembled on at least one apparatus for three-dimensional printing, not shown in the figures, for distributing molten metal 4 on at least one support 6 according to a three-dimensional digital model in order to make a three-dimensional object or a part thereof.

In the preferred embodiment illustrated, the print head 1 comprises a melting device 7, the melting device 7 being adapted to produce molten metal 4 from solid metal by heating, which is connected to the first chamber 3 by at least one drain tube, in order to convey the molten metal itself to the first chamber 3.

However, the possibility of solid metal melting inside the first chamber 3 by means of a specific melting device 7 integrated in the body 2 of the printhead 1 cannot be excluded.

Preferably, the molten metal 4 contained in the first chamber 3 is aluminium, which is used for the manufacture of various products, although the possibility of using different types of molten metal or alloy is not excluded.

Usefully, the first chamber 3 is provided with heating means, not shown in the figures for the sake of simplicity, suitable for maintaining the temperature of the molten metal 4 substantially at a predetermined value.

In particular, the temperature inside the first chamber 3 must be higher than the melting temperature of the metal used, which in the case of aluminium is approximately equal to 660 ℃, in order to keep it molten and prevent it from solidifying inside the print head 1 before dispensing.

In a preferred embodiment of the invention, the heating means used comprise at least one electric heating element associated with the body 2, suitable for heating the first chamber 3 and the molten metal 4 contained therein.

However, the use of different types of heating devices, for example the use of a liner placed outside the body 2 and conveying inside a heating fluid, for example supersaturated steam compatible with the required operating temperature, cannot be excluded.

The body 2 is made of a material resistant to high temperatures, such as special steel, in view of the high temperatures required.

Advantageously, the first chamber 3 contains an inert gas 8 in contact with the molten metal 4 and occupying the free volume of the first chamber 3 itself.

It should be noted that, within the scope of the present invention, "inert gas" means a gas that does not react chemically with the molten metal 4, or in any case reacts negligibly, and therefore does not change its chemical-physical properties.

Preferably, in the particular case where the molten metal 4 is aluminium, the inert gas 8 consists of at least one of argon and nitrogen, since aluminium is susceptible to oxidation in the presence of oxygen in the air and consequent irreversible changes in the chemical-physical characteristics, although the possibility of providing different types of inert gas 8 components cannot be excluded.

Still according to the invention, the body 2 of the printhead 1 comprises at least one second chamber 9, the second chamber 9 being adapted to contain at least one working fluid 10 and being connected to pressure varying means 11, the pressure varying means 11 being adapted to define a pressure difference between the first chamber 3 and the second chamber 9.

Preferably, the working fluid 10 is air, although the possibility of using a different working fluid 10, for example a liquid, cannot be excluded.

Furthermore, the type of pressure variation means 11 used depends on the type of working fluid 10 provided in order to correctly vary the pressure inside the second chamber 9 with respect to the pressure in the first chamber 3.

Preferably, if the working fluid 10 is air, the pressure varying means 11 comprises at least one of a vacuum pump and a compressor, although the possibility of providing different types of pressure varying means 11 cannot be excluded.

In particular, in the case where the pressure of the working fluid 10 must be reduced to a value lower than atmospheric pressure, it is advisable to use a vacuum pump, whereas if such a pressure value is higher than atmospheric pressure, it is useful to use a compressor.

In a preferred embodiment, the pressure varying means 11 comprises a vacuum pump.

Furthermore, the pressure difference defined between the first chamber 3 and the second chamber 9 may be positive, i.e. the pressure inside the second chamber 9 is lower than the pressure inside the first chamber 3, or negative, i.e. the pressure inside the second chamber 9 is higher than the pressure inside the first chamber 3.

Preferably, the pressure difference defined between the chambers 3, 9 is positive, although the possibility of providing a negative pressure difference cannot be excluded.

Furthermore, according to the invention, the body 2 of the printhead 1 comprises at least one dispensing assembly 12, 13 comprising at least one flexible sheet element 12 separating the first chamber 3 from the second chamber 9.

In particular, the laminar element 12 is deformable by the pressure variations in the second chamber 9, and the deformation of the laminar element 12 determines the outflow of the molten metal 4 from the dispensing opening 5.

Advantageously, the sheet element 12 comprises at least one first face 14 facing the first chamber 3 and at least one second face 15 opposite the first face 14 and facing the second chamber 9 and is peripherally associated in a non-removable manner with at least one lateral wall 16 of the body 2 by welding means.

Usefully, the fact that the sheet element 12 is provided in association with the side wall 16 by welding means allows for the absence of the need to provide gaskets or other sealing means.

Furthermore, due to the presence of the laminar element 12, the first chamber 3 and the second chamber 9 are isolated from each other in a fluidic manner, so as to ensure a pressure difference between the two chambers 3, 9 and to ensure that the working fluid 10 and the inert gas 8 do not come into contact with each other.

As described above, the operating temperature of the print head 1 is high, and therefore, it is impossible to perform the assembly of the main body 2 by inserting a rubber packing, which cannot sufficiently withstand high temperatures.

Preferably, therefore, after assembly of the dispensing assemblies 12, 13, the body 2 is made as a single body by at least two parts assembled together and welded, so as to obtain a single block which does not require gaskets or other sealing means.

Still according to the invention, the distribution assembly 12, 13 comprises at least one distribution element 13 housed in the first chamber 3, the distribution element 13 being associated with the sheet element 12 and comprising at least one thrust portion 19 immersed in the molten metal 4 and arranged in proximity to the distribution opening 5. The deformation of the sheet element 12 takes place between a first configuration in which the thrust portion 19 is arranged away from the dispensing opening 5 and a second configuration in which the thrust portion 19 is close to the dispensing opening 5.

In particular, the proximity of the thrust portion 19 to the distribution opening 5 limits the outflow of the molten metal 4 from the distribution opening 5 itself.

In fact, the molten metal 4 contained in the first chamber 3 has a very high viscosity, and therefore it is not possible to dispense it through the dispensing opening 5 by gravity alone, but rather a force must be applied to push the molten metal 4 out of the print head 1.

Thus, the deformation of the distribution assemblies 12, 13 allows to exert a thrust force on the molten metal 4 through the thrust portion 19, pushing it through the distribution opening 5 and letting it flow out.

In a preferred embodiment, the thrust portion 19 in the second configuration is arranged to close the dispensing opening 5, although it cannot be excluded that in the second configuration the possibility is provided that the thrust portion itself remains separated from the dispensing opening itself.

In other words, in the embodiment shown in the figures, during the movement between the configurations, the thrust portion 19 abuts against the dispensing opening 5.

In other words, the pressure variations inside the second chamber 9, compared to the first chamber 3, cause the deformation of the sheet element 12, which is flexible, changing its configuration, thus pulling the dispensing element 13 associated therewith.

Furthermore, the displacement of the distribution element 13 involves a subsequent movement of the thrust portion 19, which thrust portion 19 moves alternately between the first configuration and the second configuration, pushing out from the same distribution opening a thin layer of molten metal 4 located in the vicinity of the distribution opening 5.

As mentioned above, in the preferred embodiment, the pressure change inside the second chamber 9 occurs by means of a reduced pressure, although it cannot be excluded to provide the possibility of an increase in the pressure inside the second chamber itself.

In the preferred embodiment shown in the figures, the laminar element 12 is substantially flat in the second configuration, whereas in the first configuration the laminar element itself is deformed into a substantially curved shape.

The possibility of providing an alternative embodiment, not shown in the figures, in which the laminar element 12 in the first configuration is substantially flat, while in the second configuration it is deformed into a substantially curved shape cannot be excluded.

As shown, the dispensing element 13 extends along at least one main direction a substantially perpendicular to at least one main plane a-a defined by the laminar element 12 in the second configuration, and is provided with at least one proximal portion 13b, which proximal portion 13b is associated with the first face 14 of the laminar element 12 and with at least one distal portion 13a defining a thrust portion 19.

However, the possibility of providing the distribution element 13 with a shape different from the one described cannot be excluded.

As also shown, the sheet element 12 in the first configuration substantially projects and bulges from the side of the second chamber 9 of the main plane a-a, although the possibility of manufacturing the sheet element 12 cannot be excluded, so that in at least one of said configurations the sheet element 12 projects and bulges laterally from the main plane a-a of the first chamber 3.

During the deformation of the dispensing assemblies 12, 13, the dispensing element 13 is translated by the gripper in the main direction a, due to the deformation of the sheet element 12 in the first configuration, moving the thrust portion away from the dispensing opening 5.

During the printing operation, the dispensing assemblies 12, 13 are deformed only according to the printing instructions provided by the digital model.

It is useful to keep the distribution assemblies 12, 13 in the original configuration, at the point where no deposition of the molten metal 4 is provided and at the plant stop stage, with the thrust portion 19 arranged to close the distribution opening 5 in an abutting manner, so as not to risk accidental distribution of the molten metal 4.

Advantageously, the movement of the laminar element 12 from the first configuration to the second configuration is of a substantially periodic type, and vice versa. This is because the pressure varying means 11 is adapted to vary the pressure in the second chamber 9 substantially periodically with a predetermined frequency.

The periodic movement of the sheet element 12 allows the molten metal 4 to be dispensed through the dispensing opening 5 into small droplets 17, which droplets 17 are deposited on a suitable support 6 according to a predetermined three-dimensional numerical design, so as to form the desired object.

It is useful that the dispensing opening 5 has a cross section with a lateral width 18 of between 1 μm and 50 μm in order to deposit some droplets 17 of molten metal 4 with a very small diameter, which guarantees a high precision in the manufacture of three-dimensional objects.

In particular, the lateral width 18 is between 10 μm and 30 μm.

In a preferred embodiment, the lateral width 18 is equal to 20 μm, although the possibility of providing different values for the lateral width 18 cannot be excluded.

Preferably, the cross-section of the dispensing opening 5 has a substantially circular shape, which is devoid of edges, so as to minimize friction due to the intersection of the molten metal 4, and in this case the transverse width 18 corresponds to the diameter of the cross-section, although the possibility of having different shapes of the dispensing opening 5 cannot be excluded.

In practice it has been found that the described invention achieves the intended aim.

In this respect, the fact is underlined that the particular solution to provide the above-mentioned print head for three-dimensional printing of molten metal, allows to considerably simplify the structure of the print head itself compared to known types of print heads.

Thus, the simplicity of the printhead structure greatly simplifies the operation of making three-dimensional metal objects.

Furthermore, the particular solution provided for the three-dimensional printing of print heads with a simple structure allows to reduce the incidence of faults and therefore also the associated special maintenance costs, compared with print heads of known type.

Furthermore, the particular solution of providing a print head for three-dimensional printing with a simplified structure makes it possible to simplify the disassembly and assembly operations required for routine maintenance, while reducing machine downtime and the related costs.

Again, providing a particular solution for a printhead body made by welding two parts to form a single body part in which to weld the dispensing assembly, may avoid the need to provide a sealing arrangement that is substantially incompatible with high operating temperatures.

Furthermore, the particular solution of providing a dispensing opening with a very small transverse width allows dispensing very small quantities of molten metal and obtaining a three-dimensional object of high definition and precision.