The principle of shell objects creation

Abstract

The principle of shell objects creation Method of controlled sintering in the volume of powdered technical materials - especially polymers, metal materials, glasses and ceramics - to achieve the desired volume structure. Preferably, this technical solution is intended to produce objects with the occurrence of thin walls (shells), the construction of which is significantly easier on the basis of this invention than with the existing methods of additive technologies building volume by layers - e.g. no support structures are required. This physical principle enables the creation of a primary temperature field through several mutually intersecting beams of penetrating coherent radiation (1), through which cohesion is created between the particles of the powder material. The primary temperature field (3) is moved in a determined manner in the working space to achieve the construction of the desired object (4) by transformation from the powder material. The powder material is used for processes in two forms: (i) loose powder, in which the volume loss of the transformation from the powder state to liquid and solid is supplemented by gravitational forces from the stock located above the place of the process; (ii) powder compacted by pressing, in which the purposeful production of an object with the required porosity is assumed. The transformation from the powder material to the desired object is, in principle, carried out by the action of the primary temperature field (3) in two ways: (i) Melting, during which the particles of the powder material intended for fusion metallurgy processes are melted, mixed in a liquid state and subsequent cooling to create a compact volume of the manufactured object; (ii) By sintering the powder in a solid state, in which the particles of the powder material intended for the powder metallurgy processes are interconnected by the processes of atomic diffusion leading to the joining of the powder particles, increasing the density, recrystallization and grain growth. The resulting product in this case is a powder compact After creating the compact and its separation from the powder material, usually takes place further processing with a primary temperature field - final sintering - in order to significantly reduce the porosity and increase the mechanical properties. In all phases of the described processes, it is advantageous to use a secondary temperature field formed by several mutually intersecting beams of penetrating coherent radiation, through which the temperature gradient between the created and created volumes is reduced and the material structure of the created objects is homogenized.

Description

[0001] The principle of shell objects creation

[0002] Technical field

[0003] The technical solution refers to controlled sintering in the volume of powdered technical materials to achieve the required volume structure. The main typical representatives of powder materials - without limitation to the listed - are polymers, metal materials, glasses and ceramics. Preferably, this technical solution is intended for producing objects with the appearance of thin walls (shells), the construction of which is significantly easier based on this invention than with the existing methods of additive technologies - e.g. no support structures are required.

[0004] The invention falls into the industrial areas of additive manufacturing of objects from powder materials and production through powder metallurgy.

[0005] Background art

[0006] Currently, one of the most used principles in additive manufacturing technologies is the layer- by-layer sintering of powder material from metal, plastic, glass and ceramic materials (Powder Bed Fusion - PBF). The principle of this technology is that the material in powder form is spread in a thin layer on the printing plate. The desired shape of the product is hardened in this layer by sintering the material. After one layer is completed, the printing plate is moved to the next level and another layer of powder is applied, in which a layer is cured by sintering, following the layer cured in the previous step. The formation of shell structures can in many cases be ensured only through the simultaneous construction of the supporting structures of those shells. After completion, the supporting structures must be removed from the building.

[0007] The second most important principle of additive technologies is based on the fact that the powder material is transported to the surface of the solid base material (most often in the flow of a carrier gas medium) in thin layers under the simultaneous action of an energy carrier - e.g. laser, plasma, electron beam, kerosene, etc.). Melted powder particles fuse with the solid base on the surface. A typical representative of this principle is Powder Deposition (PD). Coherent radiation sources (lasers) and an electron beam are most often used as an energy source for the above-mentioned principles. A smaller part of the energy source is represented by plasma, electric arc and flammable gases. The creation of shell elements in this method is burdened by significant dimensional and shape inaccuracies, which must be removed by additional machining. This principle is described in document US20180221950A1, which describes a method of 3D printing of composite metal or ceramic materials that are applied layer by layer.

[0008] The disadvantage of the above-described additive technologies for the creation of objects is the complexity consisting in the gradual application of layers of powder material, the mostly complicated creation of shell elements and the low productivity and energy consumption of production.

[0009] A significant negative of classic additive technologies is the large temperature difference between the fused layer and the carrier layer (a layer of solid material on which the applied powder is immediately fused), which causes significant internal stresses in the thus-created object through thermal shrinkage. These internal stresses must be removed by annealing as soon as possible after the building of the object is completed.

[0010] Due to the growing demands of customers, complex geometries of products and new types of materials, these production technologies are reaching the limits of their possibilities. This creates space for the development of new production principles.

[0011] The proposed method of volume additive production of powder materials according to the invention increases the productivity and efficiency of the additive production of objects with shell elements while simultaneously reducing internal stresses in the manufactured object.

[0012] Disclosure of Invention

[0013] In an effort to achieve an easier directed distribution of heat into the volume of the surrounding powder material and to achieve a reduction of the temperature gradient leading to a reduction of internal stresses in the manufactured object and thus to achieve the production of complex, shape-complex parts while maintaining low material requirements, a method of volumetric additive manufacturing was created, which is implemented in the volume of powder material itself, in contrast to the existing principles of additive manufacturing from powder materials, where this process takes place in steps formed by the application and sintering of thin layers of material.

[0014] The invention is mainly based on the physical principle of transforming the energy of penetrating coherent radiation into thermal energy in the volume of the powder material leading to the creation of cohesion between the powder particles.

[0015] Within the DIN8580 standard, the processes taking place when using the invention are included in group 1. Primary shaping, subgroups 1.4 Primary shaping from the powdery or granular state. The effect of transforming the energy of penetrating rays into thermal energy is described in several materials - e.g. Jangwoo Kim, Ki Hyun Nam: X-ray-Induced Heating in the Vicinity of the X-ray Interaction Point, Applied Sciences, 2023,13, 717, https: / / doi.org / 10.3390 / appl3020717, or Krygier A. et al: X-ray source characterization and sample heating on x-ray diffraction experiments at the National Ignition Facility, Physics of Plasmas, AIP Publishing,

[0016] The second important physical principle used in the invention is the use of penetrating coherent radiations working with ultrashort pulses. In the case of ultra-short pulse sources of coherent radiation, energy transfer does not take place based on the knowledge of classical physics, but the principles of quantum mechanics are applied. During the interaction of an ultra-short pulse of coherent radiation with a high energy density with the material, the energy transformed into heat does not spread primarily based on the laws known from classical physics, but the energy transfer takes place to a significant extent through the non-equilibrium transport of electrons. (Wenqian Hu et al: Energy transport analysis in ultrashort pulse laser ablation through combined molecular dynamics and Monte Carlo simulation, Phys. Rev. B 82, 094111 - Published 17 September 2010).

[0017] Another important physical principle used in the invention is the fact that penetrating coherent radiation shows several local extremes of the absorption spectrum of the processed materials - with non-penetrating coherent radiation, only one maximum is observed because the transformation of radiation energy into other forms of energy takes place on a very limited volume of the surface of the interacted material. This principle is for coherent radiation impenetrable in technical materials described when they are used in a transparent material, e.g. in the publication Molly Subhash H., Wang R.: Optical Coherence Tomography: Technical Aspects, ISBN 978-3-642-28390-1. Springer-Verlag Berlin Heidelberg, 2013, DOI 10.1007 / 978-3 -642-28391 -8_5.

[0018] The essence of the method of producing objects through volume creation of cohesion (melting, sintering, etc.) between particles of metal, ceramic, glass or plastic powders according to the invention is characterized by the following steps:

[0019] - material provision in powder form,

[0020] - ensuring the protection of the powder material from atmospheric oxygen and reactants during all steps of the process,

[0021] - placing the powder material in the mould to create the working volume,

[0022] - creating a primary temperature field in the working volume by applying penetrating coherent radiation in the volume of penetration between two or more primary beams with a wavelength in the range of 0.15 - 10 nanometres reserved for melting / sintering, while each of the beams delivers a subcritical amount of energy (ensuring that in the path of the individual beams it supplied energy that is not able to cause the melting of powder particles) and while the penetration volume of the primary beams is completely contained in the part of the working volume that is filled with material,

[0023] - heating the powder material to the required temperature by combining (the sum of) the energy of the primary beams intended for melting / sintering in the working volume to achieve a supercritical amount of energy for sintering in the entire volume of penetration of the primary beams,

[0024] - subsequently, the creation of a compact volume formed by sintered powder particles through processes of diffusion and momentum,

[0025] - solidification of the liquid alloy after subsequent cooling,

[0026] - the possibility of using a secondary thermal field to reduce the temperature gradient between the volumes being built and the volumes created.

[0027] The sintering method described above can be carried out in four different methods, based on the characteristics of the powder material preparation for sintering:

[0028] I. AMF (Additive Manufacturing from Free formed powder) Melting of powder freely poured in a suitable cavity (mould) with a sufficient height, preventing the access of atmospheric oxygen. This method requires the use of powders suitable for additive technologies, i.e. powders suitable from the point of view of the principles of melt metallurgy, which will go through a full cycle of melting and solidification. Due to the need to supplement the loss of volume of powdered metal after melting and solidification, the height of the mould must be at least 50% - 100% higher than the height of the part - it depends on the type of material, shape and dimensions of the powder particles. To make replenishment of the decrease in the volume of the powder material by gravitational force during the building of the object without problems, building this object from the bottom of the mould has proven itself. With this method, the created objects are characterized by almost zero porosity, and the mechanical properties approach the values typical for the type of material used. To achieve manufactured objects with minimization of internal stresses, it is recommended to apply a secondary temperature field during the process to reduce the temperature gradient between the volumes being built and the volumes created.

[0029] II. PMF (Powder Metallurgy from Free formed powder) Sintering of free powder in a suitable universal cavity (mould) with free-flowing powder, preventing the access of atmospheric oxygen. With this method, the processes are fundamentally the same as the processes taking place in powder metallurgy - the essential physical principle is the achievement of a high degree of diffusion dynamics between individual types of the mixed powder mixture without the need to melt all types of materials that make up this mixture. The powder used for this method must meet the requirements of powder metallurgy - it must consist of a combination of powders of several materials, where at least one type of material fulfils the role of a binder during sintering. This method creates a sintered volume that is not limited by the mutual solubility of the individual materials (materials from which it is not possible to prepare alloys by melt metallurgy procedures can be combined). This object is characterized by a high degree of porosity and low resistance to mechanical stress. This object must then be subjected to further sintering through a secondary temperature field, or in an oven. Through the sintering process, the porosity value is significantly reduced, dimensions shrink in all directions and mechanical properties typical for the combination of used powders are achieved.

[0030] III. AMP (Additive Manufacturing from Press-formed powder) Melting of powder pressed in a suitable cavity (mould) with the prevention of access of atmospheric oxygen. This method requires the use of powders suitable for additive technologies, i.e. powders suitable from the point of view of the principles of melt metallurgy, which will go through a full cycle of melting and solidification. Due to the dimensional characteristics of the part, powder pressing into the cavity must be carried out at the height of the individual pressed layers according to the recommendations valid in powder metallurgy, in order to achieve a uniform compaction value of the powder material in the entire volume of the cavity. With this method, the created object is always characterized by a certain degree of porosity (porosity is controlled by the parameters of the compaction of the powder material into the mould) and the mechanical properties approach the values typical for the type of metal or alloy used. To achieve manufactured objects with minimization of internal stresses, it is recommended to apply a secondary temperature field during the process to reduce the temperature gradient between the volumes being built and the volumes created.

[0031] IV. PMP (Powder Metallurgy from Press-formed powder) Sintering of powder pressed in a suitable cavity (mould) with the access of atmospheric oxygen prevented. An essential physical principle is the achievement of a high degree of diffusion between individual types of mixed powder mixture without the need to melt all types of materials forming this mixture. The powder used for this method must meet the requirements of powder metallurgy - it must consist of a combination of powders of several materials, where at least one type of material fulfils the role of a binder during sintering. With this method, a sintered volume is created that is not limited by the mutual solubility of individual materials (materials from which it is not possible to prepare alloys by melt metallurgy procedures can be combined), characterized by a high degree of porosity and low resistance to mechanical stress. This object must then be subjected to further sintering in the oven, where the porosity value is significantly reduced, the dimensions shrink in all directions and the mechanical properties typical of the combination of used powders are achieved. Due to the dimensional characteristics of the part, powder pressing into the cavity must be carried out at the height of the individual pressed layers according to the recommendations valid in powder metallurgy, in order to achieve a uniform compaction value of the powder material in the entire volume of the cavity. With this method, the created object is characterized by a certain degree of porosity (porosity is controlled by the parameters of compaction of the powder material into the mold). The subsequent process of sintering with a secondary temperature field or in a furnace achieves mechanical properties approaching the values typical for the type of metal or alloy used.

[0032] In order to achieve a reduction in the temperature gradient between the melted and cold areas of the powder particles, during sintering according to the patent, it is recommended to create a secondary temperature field in the working volume in order to reduce the temperature gradient around the sintered volume.

[0033] To create a secondary temperature field, the penetration between two or more secondary beams of penetrating coherent radiation with a wavelength in the range of 0.15-10 nanometres in volume is used. The volume of penetration of the rays of the secondary temperature field is greater than the volume of penetration of the rays of the primary temperature field.

[0034] The heat created by the secondary temperature field can also be used to supply the energy required for sintering taking place in the primary temperature field.

[0035] The essence of the invention is based on the creation of cohesion between particles in any part of the volume of materials in the powder state by sintering in the required areas by generating a suitably controlled primary thermal field with energy supplied through penetrating coherent radiation.

[0036] An appropriately controlled primary thermal field is defined by the following characteristics:

[0037] - Energy is delivered through penetrating coherent radiation by two or more beams;

[0038] - Each of the beams delivers an amount of energy in a value that is subcritical in terms of the ability to melt powder particles;

[0039] - The beam group for creating the primary heat field is reserved for sintering purposes; - By combining the energy of the beams of the primary heat field intended for sintering in the focusing volume, a supercritical amount of energy is created, which melts the powder particles and subsequent cooling of this fused volume leads to the creation of a solid element of the material;

[0040] - The determined spatial movement of the focal volume of the primary thermal field in relation to the volume of the powder material leads to the gradual joining of solid elements of the material leading to the creation of the required volume of the object;

[0041] - By melting / sintering, the volume of the powder is reduced to a product volume;

[0042] - In the sintering process, a secondary temperature field formed by a group of secondary beams of penetrating coherent radiation can be used;

[0043] - The secondary temperature field is intended for (i) reducing the temperature gradient in the built-up volume to ensure a significant reduction of the internal stresses of the created product and ensuring higher values of the achieved accuracy of the created object, and (ii) final sintering of the product for processes carried out by powder metallurgy procedures for objects whose the structure will not cause mechanical damage due to the natural shrinkage of the object

[0044] The basic characteristics of the course of the physical principle include:

[0045] - powder materials for additive manufacturing, i.e. usable for the application of the principles of melt metallurgy (materials capable of melting and forming a solid volume by subsequent cooling) are available in a wide range of materials - from a species point of view, these are mainly polymer, metal and ceramic materials;

[0046] - powder materials for powder metallurgy, i.e. usable for the application of the principles of this metallurgy (materials capable of creating compact volumes without the need to melt all the components forming the powder) are available in a wide range of materials - from a species point of view, these are mainly metal and ceramic materials;

[0047] - a suitable cavity (mould) in which the powder material is placed in loose or compacted form;

[0048] - protection of the space in which the volume building process takes place (cavity - mould) against the access of oxygen and other reactive gases;

[0049] - the wavelength of radiation usable for sintering and for reducing the temperature gradient is in the range of 0.15 (ceramics, heavy metals) to 10 nanometres (plastics);

[0050] - Heat flux of the penetrating coherent beam of the primary temperature field (intended for sintering) is in the range of 104Wcm2(plastics) to 108Wcm2(ceramics) - metal materials and glasses are located in the middle of the mentioned limits; - Heat flux of the penetrating coherent beam of the secondary temperature field (intended to reduce the temperature gradient) is in the range of 103Wcm2(plastics) to 107Wcm2(ceramics)

[0051] - metal materials and glasses are located in the middle of the mentioned limits.

[0052] The advantages of the method of volume building of powder materials according to the invention are apparent from its effects, which are manifested externally. The novelty of this approach lies in the two most prominent principles of different inventions of the current state of the art:

[0053] - The use of the first principle - the penetrating coherent building of radiation of multiple beams for the structure of the structure from material in powder form of the primary temperature industrial field enables a significant step in two areas of the object: additive manufacturing from powder technical materials and in powder metallurgy. As part of additive manufacturing, it ensures a transition from the current approaches to building the volume of the object by successive sintering by individual layers to volume creation. As part of powder metallurgy procedures, it enables the creation of powder compact (green compact) without the need for special tools. In both cases, the process takes place in universal cavities (moulds) ensuring efficient use of input materials.

[0054] - The second principle - the use of penetrating coherent radiation of multiple beams of the secondary temperature field - (i) in powder procedures intended for work on the principle of melt metallurgy (additive manufacturing) ensures a significant reduction of the temperature gradient between the built volumes and cold volumes in the workspace. It shortens the additive manufacturing process, taking into account the temperature gradient during the process, increasing energy efficiency and significantly increasing the productivity and efficiency of existing additive manufacturing methods, (ii) When produced through powder metallurgy processes - it allows final sintering after powder compact (green compact) producing directly at the same workplace.

[0055] The use of both of the above-mentioned principles enables significant progress in building the volume of objects through additive manufacturing procedures, the transition from piece additive manufacturing of components with complex shapes to more efficient serial production using all the principles of additive manufacturing known to date and a completely new powder metallurgy procedure without the need to prepare an expensive specialized compaction tool to a single type of manufactured object. Brief Description of Drawings

[0056] The method of volume building from powder materials according to the invention is clear from the drawings

[0057] Fig. 1 shows a diagram of volume building through the energy of the primary temperature field. Wherein, l is a system of more (in this picture three) not parallel arranged primary penetrating coherent beams intersecting each other in the working volume (2) - each of the beams delivers a subcritical amount of energy, 2 is a working volume (cavity of the mould with powder material), 3 is the primary temperature field created by the sum of the energies of the individual primary beams arranged in system (1) ensuring the transformation of the powder material into the desired object, 4 is a part of the shell object under construction, the construction of which continues through the transformation of the powder material from the working volume (2) through the primary temperature field (3).

[0058] Fig. 2 shows an example of a schematic diagram of a process using both a primary and a secondary temperature field. Wherein, l is a system of more (in this picture three) not parallel arranged primary penetrating coherent beams, 2 is a working volume (cavity of the mould with powder material), 3 is a primary temperature field, 4 is a part of the shell object under construction, 5 is a system of more (in this picture three) not parallel arranged secondary penetrating coherent beams intersecting each other in the volume including the built object(4) - each of the beams delivers a subcritical amount of energy, 6 is a secondary temperature field created by the sum of the energies of individual secondary beams arranged in system (5) ensuring the reduction of the temperature gradient between the volumes being built and the volumes created.

[0059] Fig. 3 represents an overview of the four basic methods of creating objects by gradually building up in the volume of powder material through a primary temperature field.

[0060] Fig. 4 shows a diagram of a possible mutual arrangement of the primary temperature field intended for sintering the powder material and the secondary thermal field intended for reducing the temperature gradient of the sintering process. Wherein 1 is a part of the shell object under construction, 2 is a primary temperature field, 3 is a system of primary penetrating coherent beams, 4 is a secondary temperature field, 5 is a system of secondary penetrating coherent beams, 6 is a scheme of a possible spatial arrangement of the trajectory of the primary temperature field, 7 is a scheme of a possible spatial arrangement of the trajectory of the secondary temperature field. Fig. 5 shows the design characteristics of the cavities (forms) for the placement of powder materials for the course of the process according to the patent. Wherein l is a mould with the cavity for powder material, a - angle of inclination of the mould cavity walls, H - mould cavity heigh, W - characteristic dimension of the form in the direction perpendicular to the direction of construction of the object, 2 is a built object, h - height of the built object, w - characteristic dimension of the built object in the direction perpendicular to the direction of its built, 3 is a powder material in mould cavity, 4 is a top cover - its use depends on the method of protection of the powder material against atmospheric oxygen and other reactants, 5 is a vibration generator firmly connected to the mould.

[0061] Modes for Carrying Out the Invention

[0062] It is understood that the individual embodiments of the invention are presented for illustration and not as limitations of the solutions. Those skilled in the art will be able to ascertain equivalent arrangements of the invention using no more than routine experimentation. Even such equivalents fall within the scope of patent claims.

[0063] Example 1

[0064] In this example of a specific embodiment, the method of additive production of the volume of the object from polymer powder materials according to the invention by method I. (AMF) is described, as illustrated in fig. 3. The method includes steps:

[0065] - provision of non-metallic material - thermoplastic polymer in powder form,

[0066] - ensuring the protection of the powder material from atmospheric oxygen during the entire process,

[0067] - placement of the powder material by pouring it into a mould with sufficient dimensions to create a working volume - in addition to the dimensions of the sintered object, a sufficient height of the mould is important, ensuring the gradual replenishment of the powder material through gravitational forces to the place of the primary heat field, in which the powder material melts and thus the volume loss occurs,

[0068] - creation of a primary temperature field in the working volume by applying penetrating coherent radiation in the penetration volume between three primary beams with a wavelength of 8 to 10 nanometres reserved for sintering, each of the beams supplying a subcritical amount of energy and the penetration volume of the primary beams being completely contained in the part of the working of the volume that is filled with powdered material, while the highest point of the volume of powdered metal in which the primary temperature field will be applied must not exceed 50% of the height of the column of powdered material in the form. The upper 50% of the height of the column of powder material serves as a supply for replenishing the change in volume of powder to solid material,

[0069] - gradual melting of partial volumes of powder material by means of a primary temperature field (individual beams of penetrating coherent radiation work with an energy density of 105Wcm2) so that a compact volume is created by diffusion and momentum processes,

[0070] - by gradually connecting partial volumes, the required total volume of the object is created,

[0071] - creation of a secondary temperature field in the working volume by applying penetrating coherent radiation in the penetration volume between three secondary beams with a wavelength of 8 to 10 nanometers with an energy density of 103Wcm2(plastics) to 105Wcm2, while each of the beams delivers a subcritical amount of energy and while the penetration volume of the secondary beams is completely contained in the cavity (form) with the powder material,

[0072] - in the case of additive manufacturing from polymer powder materials, the secondary temperature field serves to reduce the temperature gradient between the created and created volumes and to homogenize the created objects

[0073] An alternative solution concerns the use of powder materials based on metals, glasses and ceramics.

[0074] The sequence of method steps is maintained with the exception of

[0075] - use of thermoplastic polymer material - in this example, it is possible to alternate with powder materials based on metals, glasses and ceramics;

[0076] - the wavelength of the beams of coherent penetrating radiation of the primary temperature field

[0077] (reserved for sintering) - for the sintering of metal, glass and ceramic materials, radiation with smaller wavelengths is used;

[0078] - energy density (Heat flux) of beams of coherent penetrating radiation of the primary temperature field (intended for sintering) for melting in the entire volume of penetration of the primary beams - radiation with a higher energy density is used for sintering of metal, glass and ceramic materials.

[0079] Example 2

[0080] In this example of a specific embodiment, the method of volumetric sintering of powder materials according to the invention by method II is described. (PMF) as illustrated in fig. 3. The method includes steps: - provision of material in powder form - a mixture of powders suitable for powder metallurgy - most often based on metals and ceramics,

[0081] - ensuring the protection of the powder material from atmospheric oxygen and reactants during the entire process (e.g. vacuum, protective atmosphere of inert gases, etc.)

[0082] - placing the powder material by pouring it into a mould with sufficient dimensions to create a working volume,

[0083] - creating a primary temperature field in the working volume by applying penetrating coherent radiation in the penetration volume between three primary beams with a wavelength of 0.3 to 5 nanometres reserved for sintering, each of the beams delivering a subcritical amount of energy and while the penetration volume of the primary beams is completely contained in part of the working volume, which is filled with powder material,

[0084] - gradual sintering of partial volumes of powder material through a primary temperature field

[0085] (individual beams of penetrating coherent radiation work with an energy density of 105to 107Wcm2) so that there is no massive melting of powder particles, but only their adhesion through the processes of dynamic diffusion and momentum,

[0086] - by gradually connecting the partial sintered volumes, a porous volume of the object is created with sufficient mechanical properties for manipulation within the following technological operations

[0087] - Final sintering of the prepared powder compact, for which the compact is removed from the mold and the final sintering (without melting a substantial part of the components forming the powder mixture) results in a decrease in porosity, a reduction in dimensions and an increase in the values of mechanical properties, which can take place: (i) Through secondary thermal fields according to the invention, (ii) In a sintering furnace.

[0088] An alternative solution concerns the use of powder materials based on polymers and glasses.

[0089] The sequence of method steps is maintained with the exception of:

[0090] - use of metal and ceramic materials - in this example, it is possible to alternate with powder materials based on polymers and glasses;

[0091] - the wavelength of the rays of the coherent penetrating radiation of the primary temperature field (reserved for sintering) - for the sintering of glass and glass materials, radiations with longer wavelengths are used;

[0092] - energy density (Heat flux) of beams of coherent penetrating radiation of the primary temperature field (intended for sintering) for melting in the entire volume of penetration of primary beams - radiation with a lower energy density is used for sintering polymer and glass materials. Example 3

[0093] In this example of a specific embodiment, the method of additive production of the volume of an object from a mixture of powder material based on metals according to the invention by method III is described. (AMP) according to Figure 3. The method includes the steps:

[0094] - provision of material in powder form - powder suitable for additive manufacturing (melting metallurgy processes),

[0095] - ensuring protection against atmospheric oxygen during the entire process from powder preparation to sintering (e.g. vacuum, protective atmosphere of inert gases, etc.),

[0096] - placement of part of the powder material in the mould (with sufficient dimensions to create the desired final object) with a maximum ratio of the height of the poured powder to the largest dimension of the mould cavity plan of 1 : 10,

[0097] - compaction of the powder layer by pressing - pressing parameters affect the porosity of the final volume created by sintering,

[0098] - repeating the previous two steps until the form is filled with compacted powder to the required height,

[0099] - creation of a primary temperature field in the working volume by applying penetrating coherent radiation in the penetration volume between three primary beams with a wavelength of 0.3 to 5 nanometres reserved for fusing, each of the beams delivering a subcritical amount of energy and while the penetration volume of the primary beams is completely contained in part of the working volume, which is filled with powder material,

[0100] - gradual melting of partial volumes of powder material by means of a deterministically moving primary temperature field (individual beams of penetrating coherent radiation work with an energy density of 107Wcm2) and creating the volume of the object by solidifying these partial volumes,

[0101] - by gradually connecting partial sintered volumes in a determined sequence, an object volume with low porosity and sufficient mechanical properties is created.

[0102] - creation of a secondary temperature field in the working volume by applying penetrating coherent radiation in the penetration volume between three secondary beams with a wavelength of 8 to 10 nanometres with an energy density of 103Wcm2(plastics) to 105Wcm2, while each of the beams delivers a subcritical amount of energy and while the penetration volume of the secondary beams is completely contained in the cavity (form) with the powder material,

[0103] - in the case of additive manufacturing from polymer powder materials, the secondary temperature field serves to reduce the temperature gradient between the created and created volumes and to homogenize the created objects An alternative solution concerns the use of powder materials based on polymers, glasses and ceramics.

[0104] The sequence of method steps is maintained with the exception of:

[0105] - use of material based on metals - in this example, it is possible to alternate with powder materials based on polymers, glasses and ceramics;

[0106] - the wavelength of the beams of coherent penetrating radiation of the primary temperature field (reserved for sintering);

[0107] - energy density (Heat flux) of beams of coherent penetrating radiation of the primary temperature field (intended for sintering) for melting in the entire volume of penetration of the primary beams.

[0108] Example 4

[0109] In this example of a specific embodiment, the method of volumetric sintering of a mixture of powder material according to the invention by method IV is described. (PMP) The advantage of this process is the possibility of producing objects from materials typical for powder metallurgy without the need for sintering in a furnace. The method includes the steps:

[0110] - provision of material in powder form - powder suitable for powder metallurgy processes

[0111] (mixture of powder materials, the composition of which is not suitable for production by fusion metallurgy due to limitations in the mutual solubility of the individual components),

[0112] - ensuring protection against atmospheric oxygen during the entire process from powder preparation to sintering (e.g. vacuum, protective atmosphere of inert gases, etc.),

[0113] - placing part of the powder material in the mould (with sufficient dimensions to create a working volume) with a maximum ratio of the height of the poured powder to the largest dimension of the mould cavity plan of 1 : 10,

[0114] - compaction of the powder layer by pressing - pressing parameters affect the porosity of the volume created by sintering,

[0115] - repeating the previous two steps until the form is filled with compacted powder to the required height,

[0116] - creating a primary temperature field in the working volume by applying penetrating coherent radiation in the penetration volume between three primary beams with a wavelength of 0.3 to 5 nanometres reserved for sintering, each of the beams delivering a subcritical amount of energy and while the penetration volume of the primary beams is completely contained in part of the working volume, which is filled with powder material, - gradual sintering of partial volumes of the powder material through the primary temperature field (individual beams of penetrating coherent radiation work with an energy density of 107Wcm2) so that the powder particles are melted,

[0117] - by gradually connecting partial sintered volumes, an object volume with low porosity and sufficient mechanical properties is created,

[0118] - The final sintering of the powder metallurgy product (without melting a substantial part of the components forming the powder mixture) can be performed directly in the mould by means of a secondary temperature field according to the patent, or with a furnace intended for sintering.

[0119] - The decision on the type of final sintering used depends mainly on the shape characteristics of the manufactured object - during sintering, the dimensions of the object are significantly reduced, and if there are holes or cavities in the structure of the object, the compacted but not sintered powder will prevent the reduction of dimensions and will cause mechanical damage to the manufactured object.

[0120] Industrial Applicability

[0121] The industrial applicability of the volume sintering method of powder materials according to the invention is in the areas of:

[0122] 1. Additive production from powder materials, where the possibility of building the volume of the manufactured object significantly eliminates the physical limitations of the previously used volume building technologies layer by layer (the main representatives of which are mainly Powder Bed Fusion technology and Powder Deposition technology).

[0123] 2. Powder metallurgy, where the possibility of building the volume of the powder compact of the manufactured object significantly eliminates the need to use a special tool for each manufactured object and the need to use additives to improve the mechanical properties of powders during mixing and compaction. This principle significantly increases the economic efficiency of the production of parts by powder metallurgy processes in piece and small-batch production.

[0124] 3. Powder metallurgy for the final sintering of the prepared powder compact into the final sintered product by means of a secondary thermal field according to the patent.

[0125] 4. Heat treatment directly in the process of building the volume of the manufactured product to prevent the formation of internal stresses in the finished product.

Claims

Claims1. A method of volume creation of cohesion between particles of powder materials, characterized by the fact that it includes the steps:- provision of material in powder form,- providing protection of the powder material against atmospheric oxygen and other reactants during all process steps,- placing the powder material in the cavity (mould) to create the working volume,- creation of a primary temperature field in the working volume by applying penetrating coherent radiation in the volume of penetration between two or more beams of the primary temperature field with a wavelength in the range of 0.15 nanometres to 10 nanometres reserved for melting / sintering, while each of the beams delivers a subcritical amount of energy from the point of view of heating to the melting temperature of the powder and while the penetration volume of the primary beams is completely contained in the part of the working volume that is filled with powder material,- creating cohesion between the particles of the powder material at the point of intersection of all primary beams by combining their energies in the working volume to reach a temperature enabling the activation of the conditions for the creation of this cohesion,- subsequently, the creation of a compact volume of material by metallurgical processes in the liquid state, or powder metallurgy processes by adhesion between powder particles through dynamic processes of diffusion and momentum,- subsequent cooling of the volume-created structure of the solid object.

2. The method of volumetric creation of cohesion between particles of powder materials according to claim 1, characterized in that the placement of the powder material in a mould with dimensions suitable for creating a working volume for the building object is done by free pouring to at least twice the height of this object.

3. A method of volume creation of cohesion between particles of powder materials suitable for fusion metallurgy processes according to claims 1 and 2, characterized by the fact that the built object is created in its determined volumes from the bottom of the mould upwards, so that melting of powder particles occurs in the volume of the primary temperature field and the subsequent solidification of this melt creates the body of thebuilt object, and the volume loss of the transformation from powder material to solid is replenished from the upper parts of the mould by the action of gravitational forces.

4. A method of volumetric creation of cohesion between particles of powder materials suitable for powder metallurgy processes according to claims 1 and 2, characterized by the fact that the built object is created in determined volumes so that in the volume of the primary temperature field, the particles are joined by physical processes of dynamic diffusion and momentum without melting a substantial part of the powder material and subsequently the body of the powder compact of the built object is created.

5. The method of volumetric creation of cohesion between particles of powder materials according to claim 1, characterized in that the placement of the powder material in a mould with dimensions suitable for creating a working volume for the object being built is done by successive pressing in individual layers so that the powder is placed in successive steps into a mould with a maximum ratio of the height of the poured powder to the largest floor plan of the mould cavity of 1 : 10 and then it is compacted by pressing. These steps of providing powder and pressing are repeated until the total height of the compacted column of powder is at least 10% higher than the construction height of the object being built.

6. A method of volumetric creation of cohesion between particles of powder materials suitable for metl metallurgy processes according to claims 1 and 5, characterized by the fact that the built object is created in its determined volumes located in a mould so that the primary temperature field causes the melting of powder particles and subsequent solidification the body of the built object is created from this melt.

7. A method of volumetric creation of cohesion between particles of powder materials suitable for powder metallurgy processes according to claims 1 and 5, characterized by the fact that the built object is created in determined volumes so that in the volume of the primary temperature field the particles are joined by physical processes of dynamic diffusion and momentum without melting a substantial part of the powder material and subsequently the body of the powder compact of the built object is created.

8. A method of volume creation of cohesion between particles of powder materials suitable for powder metallurgy processes according to claims 1 and 3, or 1 and 6, characterized in that during the construction of the object by means of the primary temperature field, a secondary temperature field is applied between several mutually intersecting secondary beams with a wavelength of 0.3 to 5 nanometers, while each of the beams delivers a subcritical amount of energy, and while the penetration volume of the secondary beams is completely contained in a part of the working volume in order to reduce the temperature differences between the volume of the primary temperature field and the remaining working volume of the cavity (mould), and / or for heat treatment of the material of the built-up volume of the manufactured body.

9. A method of volumetric creation of cohesion between particles of powder materials suitable for powder metallurgy processes according to claim 3 or 6, characterized by the fact that during the creation of the object, ultrasonic oscillation is applied to the mould filled by the powder material during the entire process of building the object to achieve an improved microstructure of the created volumes manufactured object and to simplify the transport of powder particles to the location of the primary temperature field.

10. A method of volume creation of cohesion between particles of powder materials suitable for powder metallurgy processes according to claims 4 and 7, characterized in that the built-up powder compact is separated from the loose powder and subjected to a sintering process through a secondary temperature field in which the processes of diffusion and momentum reduces the porosity, and the desired mechanical properties of the product are achieved.

Images