IT201800009779A1 - PROCESS FOR FINISHING OBJECTS PRODUCED BY SINTERING BY THREE-DIMENSIONAL PRINTERS BY STRATIFIED ADDITION AND LIQUEFACTION OF INCOHERENT MATERIAL AND COMPACT RESOLIDIFICATION, OBJECTS FINISHED WITH THIS PROCESS OBTAINED - Google Patents

Description

DESCRIPTION

accompanying the patent application for industrial invention concerning e

TITLE

PROCEDURE FOR FINISHING PRODUCED OBJECTS

FROM THREE-DIMENSIONAL PRINTERS FOR SINTERING

BY STRATIFIED ADDITION AND LIQUEFACTION OF MATERIAL

INCOERENT AND LOCK RESOLIDIFICATION,

OBJECTS FINISHED WITH THIS PROCEDURE OBTAINED

SUMMARY

Process for finishing objects produced by three-dimensional printers by sintering by layered addition and liquefaction of incoherent material and re-solidification in bulk, in which beams of electromagnetic waves and / or diffusers of inhibitory chemical agents and / or thermal catalysts draw and fuse areas of layers consecutively of incoherent materials, thermoplastic or metallic, deposited in succession to form masses, within which the solid object embedded in the volume remains gradually defined positively and remains inconsistent with the consecutive re-formation of the fused layers, including perimeter expansions (11) with respect to the design dimension of the fusion area (3) of the final top layers (13) of the upper surfaces (12) of the object (2), so as to displace externally to the upper surfaces (12) of the object (2) on wing appendages (11 ) protruding peripherally the perimeter deformations (10) by surface tension de l previous liquid state residual to solidification, so that with the removal of these wing appendages (11) the deformations (10) from the surface tension memory are removed and the object (2) no longer bears any trace; objects (2) finished with this process obtained including peripheral wing appendages (11) of the upper surface (12) with perimeter deformations (10) from surface tension memory which can be removed so as to residue the object (2) net from said deformations (10 ) from memory of surface tension.

DETAILED DESCRIPTION

Scope of the technique

The techniques of so-called three-dimensional addition molding are known, by means of which the localized drafting and liquefaction, under computerized logic control, of successive layers of an incoherent mass in most polymeric applications, usually in powder form, allows to define in the mass, to then obtain through extraction from the residual incoherent such, three-dimensional objects, which initially found mainly their application in prototyping.

The developments of this technology have come to the adoption of synthetic and also metallic materials whose characteristics allow in various sectors to go beyond the functions of manufactured products as mere prototypes, to arrive at real functional realizations, so that this three-dimensional molding technique arrives at a production system, which makes it convenient when it is a question, at present, to produce series of small and not necessarily small objects, rather than facing the costs of making molds, as per the classical known production technique, subject to further developments that may make the competitive three-dimensional printing even for large series, especially in view of the possibility of making structural changes to the objects as they evolve through simple changes to computer programs, where the known technique requires, conversely, the radical remaking of the molds.

The three-dimensional molding technology by layered addition and localized liquefaction in the state is implemented, depending on the materials:

through generators of coherent electromagnetic light waves (lasers) which, in implementation of programmed computerized logic, draw the contours and blend the drawn area;

or through diffusers of two different catalyst inks: a detail agent that draws the contours of the geometry according to the instructions of the file and a fusion agent that enhances the effects of a thermal source within the drawn area, while conversely the agent in detail it inhibits the thermal effects themselves;

in both cases, areas of superimposed micro-layers of incoherent material, deposited in succession, are drawn and fused consecutively at each deposition, to form masses within which the object is gradually defined positively and gradually the learning and solidification of the fused layers, that is the worked layers melt in the succession and progression in which they are spread and gradually harden one on top of the other, merging into a monoblock.

The fact that the upper layers are liquid and remain so until the gradual solidification implies capillarity phenomena due to the interaction between the molecules of the incoherent material that liquefy and those that remain in the solid state, in particular the existence of surface tension in the liquid that is resolved in the definition of a concave meniscus geometry between the liquid and what acts as a container, i.e. the non-liquefied layers beyond the object's fluidification perimeter that remain solid, creating the typical lenticular shape that wets the walls of the container in the interface between container and content at a height higher than the liquid level.

When the liquid is formed, this conformation remains and in the final layers it results in a perimeter prominence on all the upper surfaces of the object, more or less perceptible depending on the materials and geometries involved, but still present.

In many cases this prominence does not interfere with the functionality of the object by interfering with correct interfacing and coupling, but even where there are no functional contraindications, it still constitutes a sort of detectable imperfection and imperfection, which negatively discriminates objects produced with three-dimensional printers compared to objects produced with traditional matrix molds.

Aims of the invention

The main object of the present invention is in this framework to provide a method for eliminating said defect in the objects produced with three-dimensional molding techniques, i.e. eliminating the perimeter memory prominence from solidification of the concave meniscus of surface tension between the contained liquefied portion and the inconsistent portion of containment in the objects produced by sintering from three-dimensional photo / thermo operative printers for liquefaction, of the type in which thermo-excited thermo-catalyst diffusers or electromagnetic wave beams draw and consecutively fuse areas of layers of incoherent material deposited in succession to form masses, within which the object is gradually defined positively for the consecutive re-learning and solidification of the fused layers.

Another object of the present invention is to achieve the preceding object by means of a method which does not distort and does not excessively complicate the three-dimensional printing processes according to the known art.

Another purpose of the present invention is to achieve the previous purposes through a method suitable for adapting to three-dimensional printers of any type they are, as well as being able to be incorporated into machines designed for this purpose to adopt it.

Another object of the present invention is to achieve the previous aims and to provide a product as smooth as possible and in any case conforming to the project and design on all its faces, which does not have perimeter projections and in any case elements of memory for solidification on any of them. of the concave meniscus of surface tension between the contained liquefied portion and the incoherent containment portion in the objects produced by sintering from three-dimensional photo / thermo-polymerizing printers for liquefaction, of the type in which diffusers of thermo-excited thermo-catalysts or electromagnetic wave beams consecutively design and merge areas of polymeric layers deposited in succession to form polymeric masses, within which residual object is gradually defined positively upon the consecutive re-forming and solidification of the melted layers.

A further object of the present invention is to achieve the preceding objects by means of a simple and effective method and product, safe in operation and relatively cheap in cost in consideration of the results practically achieved with them.

Abstract summary of the solution concept

These and still other purposes are all achieved with the process for finishing objects produced by three-dimensional printers by sintering by stratified addition and liquefaction of incoherent material and block resolidification, in which electromagnetic wave beams and / or diffusers of inhibitory chemical agents and / o thermal catalysts draw and consecutively fuse areas of layers of incoherent materials, thermoplastic or metallic, deposited in succession to form masses, within which the solid object embedded in the volume gradually defined residual, remains inconsistent with the consecutive re-formation of the melted layers, comprising perimeter expansions (11) with respect to the design dimensioning of the fusion area (3) of the final top layers (13) of the upper surfaces (12) of the object (2), so

to be placed externally to the upper surfaces (12) of the object (2) on wing appendages

(11) peripherally projecting the perimeter deformations (10) from surface tension

of the previous liquid state residuals to solidification, so that with the removal of these

wing appendages (11) deformations (10) from memory of surface tension remain

removed and the object (2) no longer bears any trace; as well as with finished objects (2)

according to the present invention as defined by the claims with this method

obtained, including wing appendages (11) peripheral of the upper surface (12)

with perimeter deformations (10) from memory of surface tension removable of tal

to residue the object (2) net of said deformations (10) from surface tension memory.

Identification of the attached drawings

Further characteristics and advantages of the process and product according to the

present invention will become more evident from the detailed description that

follows of a preferred but not exclusive embodiment, shown alone

exemplary and non-limiting title in the number three tables of drawings attached, in

Which:

Figure 1 shows a schematic paradigmatic side section view of a

mass of inconsistent material being processed in a three-dimensional printer

by photo / thermo sintering addition by liquefaction implementing the second procedure

the present invention;

Figure 2 shows a detail of Figure 1;

Figure 3 shows a schematic side sectional view of an exemplary simplified object produced with a three-dimensional printer

photo / thermo sintering agent for liquefaction implementing the procedure according to the present

found in its conformation resulting in the immediacy of the relative print;

Figure 4 shows a detail of Figure 3 in an implementation step of the

method;

Figure 5 shows a schematic perspective view of an exemplary simplified object produced with a three-dimensional photo / thermo printer

The sintering agent for liquefaction implementing the process according to the present invention in its shape resulting from the implementation of the method.

Static description of the examples of realization

With reference to these figures, and in particular to figure 1, 1 indicates an incoherent microgranular or powdery mass, for example consisting of powdered thermoplastic material, such as a polyamide or a thermopolymer, made according to the known technique, by means of a micrometric spreader not illustrated, by deposition in succession of superimposed microlayers, indicated with 3 and drawn in emphasized dimensions to capture the structure, as well as identified limited to the sintering area as better illustrated below, to constitute an object 2 which in the example is represented as a simple parallelepiped 2, increased on a larger base 5, where 4 indicates the lateral interfaces between the object 2 and the residual incoherent mass 1.

The mass 1 must be considered constituted and deposited on a work surface 6 and enclosed within a closed controlled environment 7, to be understood as constituted by the molding chamber inside a three-dimensional printing machine for addition and sintering of a known type, of which it is schematically illustrated only a diffuser 8, of the kind operating through diffusers of two different catalyst inks: a detail agent that draws the contours according to the instructions of a file, processed by an electronic computer as per known technique, and a fusing agent that enhances within the area drawn the effects of a thermal source of a known type, not illustrated, while on the other hand the detail agent inhibits the thermal effects themselves.

The superimposed microlayers 3 identified in the sintering area 2 are by way of example graphically defined with a thicker line 9, where they must be schematically understood in the still liquid state.

The same superimposed microlayers 3 are represented with the perimeter elevations 10 deriving from the lenticular shape for surface tension assumed in the liquid phase by the superimposed microlayers 3 themselves in the lateral interfaces 4 by capillarity from interaction between the molecules of the liquefied material and those of the material that remains at the solid state.

With 11 are indicated some planar overhangs at the top of the design geometry of the object, or higher perimeter expansions of the object 2 itself deriving from perimeter expansion with respect to the design dimensioning of the fusion area of the final top layers 12 of the upper surfaces 13 of the object 2 itself, or again from the enlargement therein of the liquefaction and sintering area; constituting wing appendages 11 protruding peripherally all around the upper surface of object 2 or the upper surfaces of object 2 if there are a plurality of them uneven on different planes, for the functions that are illustrated below.

Dynamic description of the embodiment examples Having thus statically described an embodiment example of a product according to the present invention within an exemplary three-dimensional printer for addition and sintering according to the prior art, the implementation steps corresponding to the method according to the present art are illustrated below. found.

The method according to the present invention constitutes an improvement and integration of the known methods of selective melting of a molded medium in an incoherent, granular or powdery bed, with the spreading of the material in successive superimposed microlayers, where the non-fused medium serves to support the protrusions and the walls of the object produced.

For the sintering of the medium and the definition of the solid, a point-like approach can be adopted, through generators of beams of coherent light electromagnetic waves (lasers), which in implementation of programmed computerized logic draw the contours and blend the drawn area, which is particularly suitable for the sintering of metals, or, as in the example described, an approach for surfaces can be adopted, developing the process with the deposition of chemical agents, so-called inks, on the layers of incoherent material to be printed laid superimposed in succession, in particular two inks different: a fusion agent and a detailing agent, the former is a catalyst that promotes the heating of the material, the latter defines the area of the catalyzed material according to the instructions in the file.

The fusion agent allows the powder to solidify in the points where it is necessary to melt the particles, the detail one is deposited in correspondence with the contours of the object, allowing a better surface finish.

This state of thermo-fusion of superimposed micro-layers 3 has been graphically rendered in the attached drawings with a more marked line, which conventionally indicates the still liquid part, which is solidifying layer by layer, so that the upper layers 3 last deposited they are the most liquid, while liquidity decreases according to the deposit priority and the lower 3 layers are all solidified;

obviously the subdivision of the deposited layers is only indicated for explanatory purposes because in the incoherent mass 1 and in the melt 2 the layers are, obviously, in reality unrecognizable, as in the consecutive deposition they are merged into a single object 2, for which specific in the end everything is preordained.

However in the process the top layers 3 being deposited, or better, the upper levels of the mass 2 being sintered, are in the molten state and this inevitably involves capillarity phenomena due to the interaction between the molecules of the incoherent material 2 liquefaction and those of the permanent incoherent material 1 in the solid state, which results in the definition of a concave meniscus geometry by surface tension between the liquid and what acts as a container, i.e. the non-liquefied layers beyond the object perimeter of fluidization, creating in the interface between the container and contained the typical lenticular shape that wets the walls of the container at a height higher than the liquid level.

When the liquid is formed, this conformation remains and in the final layers it results in a perceptible perimeter prominence 10 on all the upper surfaces 12 of the object 2,

In this framework, according to the invention, this perimeter projection 10 of the upper surfaces 12 of the object 2 is moved beyond the upper perimeter of the object 2 itself, providing a programmatic modification on the graphic file which, limited to the last top layers 13 of the 'object, in a number to be defined contingently and optimized according to the geometries and materials, widens the point-like intervention area of the electromagnetic beam or the surface where the catalyst agent is spread, depending on the type of machine / three-dimensional printing technique for addition and sintering adopted, so as to create on the whole perimeter of contingent upper finishing of the object 2 the perimeter expansions or wing appendages 11, on which liquefaction spreads and the consequent perimeter rise 10 from surface tension.

When the object 2 solidifies in all its mass and is extracted from the incoherent bed 1, the perimeter expansions or wing appendages 11 remain with the solidified rise 10 outside the real or design perimeter of the object, so that, by removing the perimeter expansions or wing appendages 11, possibly with an operation favored by pre-breaking lines which can always be obtained by operating on the file.

Implementation alternatives

It is obvious that in further alternative embodiments, still falling within the concept of innovation underlying the example of embodiment illustrated above and claimed below, the process and product according to the present invention can be implemented with technical and mechanical equivalents, or equipped with further supplementary measures. , as well as all the modalities of the related procedural steps can be varied in a manner suitable for the purpose.

In particular, objects with upper faces arranged on different levels can be imagined, in such eventualities the perimeter protrusions from surface tension memory are also produced on the upper residual faces buried by the incoherent during the construction of higher portions which in turn will be defined by upper faces parallel to the first ones; in this case the files will have to be modified to implement the displacement expansions of the projections to be removed at all levels in which a plan is implemented.

Advantages of the invention

As is evident from the above detailed description of a preferred embodiment example and from the reference to alternative embodiments, the process and product according to the present invention offer the advantages corresponding to the achievement of the intended purposes and others besides, in fact they integrate a simple and immediate solution to eliminate the typical imperfections from capillarity memory and surface tension of objects produced with any type of three-dimensional printing technique by addition and sintering, whatever the processing technique and the plastic or metal material processed.

Scope of the protection invoked

Having thus described the process and product according to the present invention with reference to their preferred embodiment, it will be obvious to want to protect all the possible embodiments with variants of normal implementation for those skilled in the art, which do not modify the invention without exit from the purposes envisaged by the same; by this it is meant, both in the foregoing description and in the following claims, to protect all the embodiments and variants that fall within the concept of solution, in the spirit and in the purposes of the invention itself.

LEGEND OF THE NUMBERS

1) incoherent microgranular or powdery mass

2) sintered object

3) superimposed thermofused microlayers

4) lateral interfaces between the sintered object and the incoherent mass 5) greater base of the sintered object

6) work surface of the machine

7) machine molding chamber

8) diffuser

9) liquid portions of the layers

10) perimeter elevations from surface tension of the layers 11) perimeter expansions or wing appendages

12) upper surface of the object

13) final top layers of the object

Claims (8)

CLAIMS 1) Process for finishing objects produced by three-dimensional printers by sintering by stratified addition and liquefaction of incoherent material and re-solidification in block, in which beams of electromagnetic waves and / or diffusers of inhibitory chemical agents and / or thermal catalysts draw and consecutively melt areas of layers of incoherent materials, thermoplastic or metallic, deposited in succession to form masses, within which the solid object embedded in the volume which remains inconsistent with the consecutive re-formation of the fused layers, characterized by the fact that it includes expansion of at least a perimeter portion (11) with respect to the design dimensioning of the fusion area (3) of the final top layers (13) of the upper surfaces (12) of the object (2), so as to displace externally to the upper surfaces (12) of the 'object (2) on wing appendages (11) peripherally projecting the defo perimeter rmations (10) from the surface tension of the previous liquid state residing upon solidification, so that with the removal of these wing appendages (11) the deformations (10) from the surface tension memory remain removed and the object (2) does not bear more trace. 2) Process for finishing objects produced by three-dimensional printers by sintering by stratified addition and liquefaction of incoherent material and re-solidification in bulk, in which beams of electromagnetic waves and / or diffusers of inhibitory chemical agents and / or thermal catalysts draw and consecutively merge areas of layers of incoherent materials, thermoplastic or metallic, deposited in succession to form masses, within which the solid object embedded in the volume remains gradually defined positively and remains inconsistent with the consecutive re-formation of the fused layers as per the first claim, characterized by the fact of comprehend: expansion on at least one perimeter portion (11) with respect to the design sizing of the fusion area (3) of the singularity or plurality of the final top layers (13) of the upper surfaces (12) of the object (2), external dislocation of the upper design surfaces (12) of the object (2), on peripherally projecting wing appendages (11), of the perimeter deformations (10) from the surface tension of the previous liquid state residual to solidification; removal of said wing appendages (11) with the residual surface tension memory deformations (10) removed with them. 3) Process for finishing objects produced by three-dimensional printers by sintering as per the first or second claim, characterized in that it comprises: planar expansion (11) with respect to the functional design dimensioning of the object (2) of the fusion area (3) of the final top layers (13) of the upper surfaces (12) of the object (2) over the entire perimeter or part of it or on all or part of the perimeters; consequent constitution of wing appendages (11) protruding peripherally on the entire perimeter or part of it of the upper face of the object or on all the perimeters or part of them of the upper faces of the object; consequent formation and distal formation / solidification on the wing appendages (11) of the perimeter deformations (10) from the surface tension of the previous liquid state residual to solidification; extraction of the finished solidified object (2) from the incoherent residual mass (1); removal of the wing appendages (11) with the residual surface tension memory deformations (10) located thereon; consequent elimination of shapes and memory projections of surface tension menisci. 4) Process for finishing objects produced by three-dimensional printers by sintering as per any of the preceding claims, characterized in that it is applied to any type of three-dimensional printer by addition and sintering, both of the type with a point-like thermal approach operating thermo-sintering through generators of beams of coherent electromagnetic light waves (lasers), as well as of the thermal approach type for superimi operating by depositing a chemical fusion agent and a detail chemical agent with a diffused heat source, as well as of any other type. 5) Process for finishing objects produced by three-dimensional printers for sintering as per any of the previous claims, characterized in that it is implemented by modifying the graphic files that oversee the design of the object (2) to be sintered. 6) Process for finishing objects produced by three-dimensional printers by sintering according to any one of the preceding claims, characterized in that it is carried out with any plastic or metal material and in any case suitable for the purpose. 7) Finished objects obtained with the process as per the preceding claims and each of them, characterized by the fact of comprising peripheral wing appendages (11) of the upper surface (12) with perimeter deformations (10) from removable and removed surface tension memory such as to residue the object (2) net of said deformations (10) from surface tension memory. 8) Finished objects obtained as per the preceding claim characterized in that they comprise pre-fracture lines to facilitate the detachment of said peripheral wing appendages (11) of the upper surface (12) with perimeter deformations (10) from removable surface tension memory.