DESC:SYSTEM FOR PRODUCING OBJECTS USING THREE-DIMENSIONAL PRINTING AND METHOD THEREOF

Field of the invention:

The present invention relates to manufacturing of objects from variety of materials and more particularly, to a system for manufacturing of object from variety of materials including, but not limited to ceramic, metals, alloys and polymers using three-dimensional printing.

Background of the invention:

ASTM standard (ISO/ASTM 52900-15, 2015) defines additive manufacturing (AM) or 3D printing as process of manufacturing object layer by layer from the CAD data available in the STANDARD TESSELLATION LANGAUAGE (.STL) file format.

Recently AM technology is popular among industrialist, researchers, artists and designer as it can produce parts with same quality as that of parts manufactured by traditional techniques like subtractive, forming or joining. AM has played role of game changer in prominent industries like aerospace, biomedical, automotive, electronics and architecture when direct manufacturing of higher value parts with lower number is needed. It allows user to manufacture complex geometry objects with reduced cost, energy, material consumption, lead time, chemical waste, process steps and human resources. This technology can process variety of materials like metals, polymers, ceramic, metal, glass, food, resin, biomaterials and sand etc.

General steps followed in AM technology are as follows:

3D modeling: Replica of an object to be printed can be created either using CAD software, scanning tangible object using 3D scanner or directly can be downloaded from online product market. Further STL data creation and model optimization is carried out before proceeding to second stage.

Data Preparation: In this stage data is created in the form of set of instruction called G-code. Various printing parameters are set in the slicing software which is an intermediate software between AM machine and model making tool. Most of the software tools have provision to simulate the actual printing process. Particularly support structure if any are needed will be created. Object being printed is oriented as per need and sliced into number of layers. Slicer software will generate, G-code which will be input for AM machine to manufacture tangible object.

Manufacturing on AM machines: Actual product will be produced in this stage. Various machine control parameters will be set using machine control panel and machine is set to build product layer upon layer. Machine control module run the programme as per G-code with the help of servomechanism of machine.

Post processing: This is final stage where post processing if any needed on the printed object is performed. Normally cleaning, washing, sanding, painting, sintering and heating will be done as per the specific AM process, material type and product application.

American Society for Testing and Materials (ASTM-F42) has classified AM technology into seven groups as listed in Table 1. Although this technology handles variety of materials and utilizes different forms of energy, growth is apparent across all classes. Despite the number of advantages offered by this technology and growth across all classes there is wide scope to innovate/upgrade AM machine hardware and software, develop new composites and alloys and development of hybrid processes by utilizing advantages of one or more process.

Below table shows the seven AM process categories by ASTM F42.

Process Type Brief Description Related Technology Companies Materials
Powder Bed Fusion Thermal energy selectively fuses regions of powder bed Electron Beam Melting (EBM), Selective Laser Sintering (SLS), Selective Heat, Sintering (SHS) And Direct Metal Laser Sintering (DMLS) EOS (Germany)
3Dsystem (US), Arcam (Sweden) Metals, Polymers.
Direct Energy Deposition Focused thermal energy is used to fuse material by melting as the material is being deposited Laser Metal Deposition (LMD) Optomec (USA),
POM (USA) Metals
Material Extrusion Material is selectively dispensed through a nozzle or orifice Fused Deposition Modeling (FDM)
Stratasys (Israel), Bits from bytes Polymers
Vat Photo
Polymerization Liquid photopolymer in a vat is selectively cured by light-activated polymerization Stereolithography (SLA), Digital Light Processing (DLP) 3D system (USA),
Envisiontec (Germany) Photopolymers
Binder Jetting A liquid bonding agent is selectively deposited to join powder material Powder Bed and Inkjet Head (PBIH), Plaster Based 3D Printing (PP) 3D system (USA), ExOne (USA) Polymers, foundry sand, metals.
Material Jetting Droplets of build material are selectively deposited Multi-Jet Modeling (MJM) Objet (Israel), 3D system(USA) Polymers, waxes.
Sheet Lamination Sheets of material are bonded to form an object Laminated Object Manufacturing (LOM), Ultrasonic Consolidation (UC) Fabrisonic (USA), Mcor (Ireland) Paper, metals.

Metal AM technology has attracted industry/researchers attention as it offers unique applications in various sectors for customization or replacement of parts with complex geometries, internal structures and functionally graded properties. In metal AM technique powder feedstock gets converted into solid object by either of the powder processing AM technique. Electron beam melting (EBM), Selective laser melting (SLM), Selective laser sintering (SLS) are prominent powder bed fusion AM techniques which processes powder material. Basically heat source (laser or electron beam is traced along an X & Y plane across a powder bed of evenly spread material laid down by a leveler or roller on a build tray. The powder particles selectively melted/sintered or fused at specific location only by a heating source and allowed to solidify. After first layer of object the build platform is lowered down equal to layer thickness and fresh layer of powder is spread. This cycle of heating, spreading continues until the 3D object completes. The unbound powder acts as a support structure to the overhangs, which can be reused after post processing (cleaning) process.

EBM: This process makes use of high temperature electron beam generated by an electron gun to locally melt metal powder layer by layer inside vacuum chamber. The electron beam follows 2D cross section of object as a consequence melting of powder takes place and solid layer forms. Eventually fresh layer of powder deposited and cycle repeats subsequently until job completes. EBM creates fusion of particles using high energy electron beam. EBM produces less distortion in the parts due to less residual stresses. This method can produce fully dense metal parts with no property compromise. EBM uses less energy and can produce layer faster than SLS.

Selective Laser Sintering (SLS) and Selective Laser Melting (SLM) are laser-based 3D printing process that works with powdered materials. In SLS process laser is used to sinter or coalesce powdered material layer by layer. Generally, SLS is used to print object from polyamide (Nylons), Alumide (a blend of gray aluminum powder and polyamide) and rubber-like materials. SLM is also known as Direct Metal Laser Sintering (DMLS) but there is thin line between them. SLM achieves full melt of powder and it uses metal whereas DMLS sinters the powder and is restricted to alloys.

Disadvantages of the powder bed fusion techniques:
1. High Cost of initial set up.
2. Need for high power.
3. Safety Challenges in the system.
4. High Cost of production.
5. Low speed of production.
6. Residual stress in the parts.

Accordingly, there exists a need to provide system and method for three dimensional object printing, that overcomes the above mentioned drawbacks in the prior art.

Objects of the invention:

An objective of the present invention is to provide a system for producing objects using 3-dimensional printing.

Another object of the present invention is to provide a method for producing objects using 3-dimensional printing.

Summary of the invention:

Accordingly, in one aspect, the present invention provides a system for three dimensional objects printing that comprises a powder deposition unit, a leveling blade, a curing lamp, a printer head, a build box and a machine control module. The powder deposition unit comprises a hopper with attached rotary screw arrangement. The leveling blade is attached to the bottom of the powder deposition unit. The curing lamp is fixed opposite to the leveling blade. Further, the build box is placed at the bottom part of the system. The build box is provided with a build platform. In an embodiment, the build platform is a stationary platform with up-down sliding arrangement. The printer head is placed above the object “O”. The printer head comprises plurality of tinny nozzles that eject liquid binder as per the requirement at the required time.

In another aspect, the present invention provides a method for printing three dimensional objects using the system. In first step, a build platform, a powder deposition unit and a printer head are placed at their home position. In second step, filling a hopper with desired quantity of powder material is performed. In third step, a “G code file” of the part to be printed such as desired object is loaded into a machine control module. After loading of the “G code file” into the machine control module, the powder deposition unit moves from left to right initially. In the fifth step, the powder deposition unit spreads fine layer of powder across the build platform while returning from right to left. Next, the leveling blade ensures uniform powder distribution and powder layer formation. In the sixth step, the printer head travels over the layer from right to left in X, Y plane to selectively deposit fine droplets of binder as per cross section of object. In seventh step, droplets of binder percolate into the interstitial spaces between powder particles and glue them together. In eighth step, the build platform is lowered down by height equal to the thickness of the layer. Next, in the ninth step, the powder deposition unit moves from right to left, this time IR light hardens the previously printed binder. Further, steps 5 to 8 are repeatedly performed till the completion of entire 3D object layer by layer. After creation of the object, the object can be post processing at de-powdering, curing and sintering stations as per need to enhance the object properties.

Brief description of the drawings:

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein

Figure 1 shows a schematic of a 3-Dimensional object printing set-up, in accordance with the present invention;

Figure 2 shows a perspective view of a 3-Dimensional object printing set-up, in accordance with the present invention; and

Figure 3 shows a method to print 3-Dimensional object in accordance with the present invention.

Detailed description of the embodiments:

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The present invention provides a system for producing objects using 3-dimensional printing and a method thereof. The system produces object by 3-dimetional printing and the method produces the object by binding ceramics, metals or alloy powder particles using binding fluids. The present invention can manufacture object from variety of materials including, but not limited to ceramic, metals, alloys and polymers.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring now to figure 1 and figure 2, there is shown a system (100) for producing objects using 3-dimensional printing (hereinafter, referred as “the system (100”)). For better understanding of the invention the object is denoted by “O”, and loose powder is denoted as “P”.

The system (100) comprises of a powder deposition unit (10), a leveling blade (20), a curing lamp (30), a printer head (40), a build box (50) and a machine control module. The powder deposition unit (10) comprises a hopper with attached rotary screw arrangement. The leveling blade (20) is attached to the bottom of the powder deposition unit (10). The curing lamp (30) is fixed opposite to the leveling blade (20). In an embodiment, the curing lamp (30) is an infra-red (IR) tube to cure binder temporarily. Further, the build box (50) is placed at the bottom part of the system (100). The build box (50) is provided with a build platform (51). In an embodiment, the build platform (51) is a stationary platform with up-down sliding arrangement.

The printer head (40) is placed above the object “O”. The printer head (40) comprises plurality of tinny nozzles (not shown). These tinny nozzles eject liquid binder as per the requirement at the required time. The printer head (40) binder ejection function is controlled using piezoelectric principle.

Now referring to figures 1 to 3, in an aspect of the present invention, a method to produce 3 dimensional objects comprises of binding of ceramic, metals or alloy powder particles using binding fluid is described. The method is described in conjunction with the system (100). The 3 dimensional object undergoes to a sintering process. The sintering process provides higher or equivalent mechanical strength compare to other methods disclosed in prior art.

Following steps describes the method to operate the system (100) in order to produce 3-dimensional objects. In first step of the method, a build platform (51), a powder deposition unit (10) and a printer head (40) are placed at their home position. In second step, filling a hopper with desired quantity of powder material is performed. In third step, a “G code file” of the part to be printed such as desired object is loaded into a machine control module. After loading of the “G code file” into the machine control module, the powder deposition unit (10) moves from left to right initially.

In the fifth step, the powder deposition unit (10) spreads fine layer of powder across the build platform (51) while returning from right to left. Next, the leveling blade (20) ensures uniform powder distribution and powder layer formation. In the sixth step, the printer head (40) travels over the layer from right to left in X, Y plane to selectively deposit fine droplets of binder as per cross section of object. In seventh step, droplets of binder percolate into the interstitial spaces between powder particles and glue them together. In eighth step, the build platform (51) is lowered down by height equal to the thickness of the layer. Next, in the ninth step, the powder deposition unit (10) moves from right to left, this time IR light hardens the previously printed binder. Further, steps 5 to 8 are repeatedly performed till the completion of entire 3D object layer by layer.

After creation of the object, the object can be subjected to additional post-processing at de-powdering, curing and sintering stations as per need to enhance the object properties such as to improve the surface finish and strength of the final three dimensional object.

Advantages of the invention:

1. The system (100) does not require expensive high power heating/melting source.
2. The system (100) does not need build substrate or support structure.
3. The system (100) does not require environmentally controlled chamber during green part fabrication.
4. Zero/minimal residual stresses in printed parts/object as there is no rapid heating and cooling of melt pool.
5. The system (100) is compatible with highly reflective materials in contrast to other powder based AM process.
6. Relatively high build rate compare to other techniques.
7. Lower cost of initial set up of the system (100).
8. Safety can be easily achieved.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the scope of the claims of the present invention.

,CLAIMS:We claim:

1. A system (100) for producing objects using three-dimensional printing comprises:
a powder deposition unit (10) having a hopper with attached rotary screw arrangement;
a leveling blade (20) attached to the bottom of the powder deposition unit (10);
a curing lamp (30) fixed opposite to the leveling blade (20);
a printer head (40) placed above the object “O”, the printer head (40) having a plurality of tinny nozzles that eject liquid binder as per requirement at required time using piezoelectric principle;
a build box (50) placed at the bottom part of the system (100), wherein the build box (50) is provided with a build platform (51); and
a machine control module.

2. The system (100) as claimed in claim 1, wherein the curing lamp (30) is an infra-red (IR) tube to cure binder temporarily.

3. The system (100) as claimed in claim 1, wherein the build platform (51) is a stationary platform with up-down sliding arrangement.

4. A method for producing objects using three-dimensional printing, by the system (100) as claimed in claim 1, comprising steps of:
placing a build platform (51), a powder deposition unit (10) and a printer head (40) at their home position;
filling a hopper of the powder deposition unit (10) with desired quantity of powder material;
loading a “G code file” of the part to be printed into a machine control module;
moving powder deposition unit (10) moves from left to right intially;
spreading fine layer of powder across the build platform (51) by the powder deposition unit (10) while returning from right to left, wherein the leveling blade (20) ensures uniform powder distribution and powder layer formation;
moving/traveling the printer head (40) over the layer from right to left in X, Y plane to selectively deposit fine droplets of binder as per cross section of object, wherein the droplets of binder percolate into the interstitial spaces between powder particles and glue them together;
lowering down the build platform (51) equal to the thickness of the layer;
moving the powder deposition unit (10) from right to left, wherein the IR light hardens the previously printed binder;
repeating the above mentioned steps to create the complete three dimensional object layer by layer;
subjecting the three dimensional object part to additional post-processing at de-powdering, curing and sintering stations as per need to enhance the object properties such as to improve the surface finish and strength of the final three dimensional object.

Dated this 01st day of July 2021

Prafulla Wange
(Agent for Applicant)
(IN/PA-2058)