Claims:We claim:
1. A method for manufacturing an extrusion die using a 3D printing process for thin wall ceramic products, the method comprising the steps of:
designing and fabricating an extrusion die such that the extrusion die has thin wall intricate cell shape and high slenderness ratio of each cross section of the 3D printed extrusion die;
slicing a solid model of extrusion die into a number of sections or layers along its length using a software technique;
feeding information to a3D printing machine which works on the DMLS technique;
wherein the 3D printing machine has laser power source and melting a powder material layer by layer as per the solid model of the extrusion die.

2. The method as claimed in claim 1, wherein the extrusion die is designed and fabricated by using a direct metal laser sintering (DMLS) or powder bed technique of a 3D printing process.

3. The method as claimed in claim 1, wherein thickness of each slice of the extrusion die is around 25 microns.

4. The method as claimed in claim 1, wherein the powder material is stainless steel powder.

5. The method as claimed in claim 3, wherein the stainless steel powder is very fine in the size of around 20 microns.

6. The method as claimed in claim 1, wherein the slenderness ratio of each cross section of the 3D printed extrusion die is at 1:20.
, Description:
A METHOD FOR MANUFACTURING EXTRUSION DIE USING 3D PRINTING PROCESS FOR THIN WALL CERAMIC PRODUCTS

FIELD OF INVENTION
[001] The present invention relates to a method for manufacturing an extrusion die for extruding thin wall ceramic products using direct metal 3D printing process where dimensional accuracy requirements are stringent and also has intricate internal passages having high cell density. In more particularly, to the manufacture of ceramic products, the raw material with proper material composition is prepared and the same is forced through the extrusion die to provide extruded green bodies of complex shape which are then dried and fired. Thin-walled ceramic structures thus produced are used in a variety of applications. For example, such structures are used as substrates for the support of catalysts in automotive exhaust gas treatment systems, as well as for other catalyst carriers, filter bodies, and thermal regenerators or heat exchangers.
BACKGROUND OF THE INVENTION
[002] Generally, to manufacture the extrusion dies in conventional methods drilling, core drilling, Electro Chemical Machining (ECM), Electrical Discharge Machining(EDM) and wire EDM are typically used. The conventional methods have got several process limitations, such as the straight and prismatic passages are only possible, not the varied cross sectional passages, which gives the best flow conditions. The dimensional accuracy achieved with these processes is not consistent, machining cycle time is high. When the machining process is carried out using EDM and ECM process, the accuracy levels are mostly affected with the erosion of the electrodes being used. Alighting the plurality of internal passages generally from front and back end of the die using different or same machining process is very difficult and results in serious cumulative deviations. We cannot make dimensionally controlled inward or outward tapered cross sections with these conventional methods. These varied cross sections help in easy material flow across extrusion die and maintaining the required rheology of the material while flowing through the interior of the extrusion die, as shown in figure 1a and 1b.
[003] In accordance with the production of these finer thin wall ceramics requires the extrusion dies with finer structure to be used. Dies used for the extrusion of finer ceramics are typically machined on metal plates or blocks having shallow, crisscrossing and interconnecting discharge slots on one face of the die from which the ceramic raw material is forced to get the end product with desired shape and structure.
[004] Fig. 2 and Fig. 3 illustrate both sides of conventional extrusion die for ceramic products. The extrusion die is an important and often most critical tool to make complicated ceramic products. The extrusion die has been designed to produce the desired end shape of the ceramic product, with the desired defect-free throughput, when the ceramic raw material is passed through it. Generally, the extrusion die is formed with thin walled and intricate shapes, very small opening and web net shape of construction. The figure 2 shows of one side of the conventional extrusion die for ceramic products, also the figure 3 shows the opposite side of the conventional extrusion die for ceramic product, as shown in X-Y axis.
[005] The extrusion dies are made of steel in order to with stand extrusion pressures and also erosion caused due to ceramic material flow against them without getting the shape distortion. In the conventional machining methods of extrusion dies, EDM and ECM processes are extensively used. Graphite/Copper electrodes are used to make the small openings of the die, as shown in Fig. 3. Accordingly, the dimensional accuracy for all openings are not guaranteed as the electrode becomes eroded during the machining process. Drilling such small openings where the wall thickness is very less compared to the length of the component (slenderness ratio: 1:20) is very difficult. It is difficult to maintain the perpendicularity and cylindricity across the length of the component in the drilling process.
[006] In conventional machining methods, the cell walls are made straight as inward/outward taper machining is very difficult. Due to this straight walls, flow obstructions or non-uniform material flow occurs during the ceramic raw material is passed through the extrusion die while making the ceramic end products.
[007] The patent search has been carried out on this subject, but the complete information related to this invention is not directly available. The following patents (US20080220633A1, US20180093912A1, US2979973A, US5865983A, WO/2016/085782 etc.) related to the present subject matter were checked and found discrete information either related to manufacturing of extrusion dies using other processes like LYCA (Lithography Electroplating and molding), hard faced extrusion die manufacturing methods or making of optical fiber using extrusion dies etc.
[008] The US Patent No. 20180093912 uses a 3D printed die to use glass preform at high temperature for making fiber optic pre-form. This die is used for making long flexible optical fiber similar to tube extruding die which typically uses die pins where the passages inside the die need not be so intricate in comparison with those are used for manufacturing large cross-section ceramic Honeycomb at room temperature.
[009] Accordingly, the purpose of the die as described in the US patent 20180093912disclosures is to introduce the hot glass directly between the die pins is difficult to fabricate using conventional methods hence they use 3D printing route. However, no patents or literature surveyed by us discloses the use of metal 3D printing concept for novel design and unique fabrication method to improve the honeycomb extrudate quality and throughput which is not possible by using the prior art as practiced in the ceramic industry. Therefore, the challenges of shear thinning rheological controlled ceramic paste for honeycomb extrusion is different than the flowable glass extrusion at very high temperatures.
[0010] In order to overcome the above mentioned issues, first time direct metal 3D printing process has been adopted to manufacture such complicated extrusion dies. The material used is stainless steel. The extrusion die has been designed keeping in view of the easy flow ability of the ceramic material. Then the extrusion die has been manufactured by using Direct Metal Laser Sintering (DMLS) or powder bed technique. Therefore, the manufacturing time has been reduced by 80% compared to conventional machining process and complicated patterns with precise dimensional accuracy has been achieved. The overall cost of the extrusion die has been reduced drastically to 20%.
[0011] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
OBJECTS OF THE INVENTION
[0012] The principal object of the present invention is to adopt a direct metal 3D printing process to manufacture extrusion dies for thin wall intricate shaped ceramic products by maintaining dimensional accuracy across all the sections of die.
[0013] Another object of the present invention is to establish a manufacturing method whereby perfectly aligned large number of varied cross section internal pathways can be fabricated.
[0014] Yet another object of the present invention is to provide the new capability of machining intricate internal passages of the extrusion die has opened up huge opportunities of large number of favorable internal passages designs.
[0015] Yet another object of the invention to achieve identical dimensional accuracy of each cell of the entire die with required surface finish, in uniform extrusion across cross section thereby improving quality and yield of extrudate products.
[0016] Further object of the present invention is to reduce the manufacturing cycle time and cost in an efficient manner.
[0017] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION
[0018] One or more drawbacks are overcome through the processes claimed in the present invention along with the additional advantages. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[0019] The present subject matter relates toa method for manufacturing an extrusion die using a 3D printing machine for thin wall ceramic products. The method comprising the steps of: fabricating an extrusion die using a laser sintering technique in a 3D printing machine such that the extrusion die has complicate shape and high slenderness ratio of each cross section of the 3D printed extrusion die. A solid model of extrusion die is sliced into a number of sections/layers along its length using a software technique. The information is fed to the 3D printing machine which works on the laser sintering technique, wherein the 3D printing machine has laser power source and melting a powder material layer by layer as per the solid model of the extrusion die.
[0020] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0022] FIG. 1a and 1b illustrate conventional process for making thin wall ceramic products using extrusion die process;
[0023] FIG. 2 illustrates one side of conventional extrusion die for ceramic products;
[0024] FIG. 3 illustrates other side of conventional extrusion die for ceramic products;
[0025] FIG. 4a and 4b illustrate top view of actual model and solid model of 3D printed extrusion die, in accordance with a present subject matter;
[0026] FIG. 5 illustrates bottom side view of actual model and solid model of 3D printed extrusion die, in accordance with a present subject matter;
[0027] FIG. 6 and FIG. 7 illustrate perspective view of fine wall thickness and inward taper wall of a cell in the extrusion die, in accordance with a present subject matter;
[0028] FIG. 8a and 8billustrate view of intricate cell shapes of the extrusion die, in accordance with a present subject matter; and
[0029] FIG. 9 illustrates particulars of varied cross sectional passage of individual cell for the extrusion die; in accordance with a present subject matter. (The front holder of the die assembly is not shown in the above figures)
[0030] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0031] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0032] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0033] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0034] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0035] Fig. 4a and 4b illustrate top view of actual model and solid model of 3D printed extrusion die, in accordance with a present subject matter. The extrusion dies are generally manufactured by using drilling, core drilling, Electro Chemical machining (ECM) and Electrical Discharge Machining (EDM) processes, conventionally. However, the conventional machining processes are highly cumbersome, laborious, expensive and individual skill dependent. The dimensional accuracy across the extrusion die is not guaranteed. The complicate shape and high slenderness ratio of each cross section of the 3D printed extrusion die. In the top view of 3D printed extrusion die is shown in axis of X, Y, Z axes.
[0036] Fig. 5a and 5b illustrate bottom view of actual model and solid model of 3D printed extrusion die, in accordance with a present subject matter. In this bottom view of the 3D printed extrusion die is shown in axis of X, Y, Z axes.
[0037] In accordance with an embodiment of the present subject matter relates to this process, a design of the extrusion die is very intricate shapes, and manufacture the same without any manufacturability problems. Therefore, the process is to achieve very fine cell wall thickness and also straight or Inward taper or Out ward taper, as shown in the figures 6 and 7.
[0038] Fig. 6 and 7 illustrate perspective view of fine wall thickness and inward taper wall of a cell in the extrusion die, in accordance with a present subject matter. The direct metal 3D printing process uses stainless steel powder as raw material. The extrusion die is made of stainless steel powder which is very fine in the size of around 20 microns by using the 3D printing process such that the 3D printing process is used to direct metal laser sintering (DMLS)technique for producing the extrusion die. In this process, no cutting tools or machining is involved. A solid model of the designed extrusion die is sliced into number of sections or layers along its length using a software technique, where each slice is around 25 microns’ thickness of the extrusion die. The information is fed to the 3D printing machine which works on the DMLS technique. The 3D printing machine has a laser power source and melting the powder material layer by layer as per the solid model of the extrusion die. The fine wall thickness and inward taper wall of cell in the extrusion die are clearly shown in X, Y and Z axes.
[0039] Fig. 8a and 8billustrate view of intricate cell shapes of the extrusion die, in accordance with a present subject matter. The process isto achieve required surface finish and also the dimensional accuracy can be maintained for all cells across the die. The very intricate shapes of extrusion die and finer wall thicknesses as shown in X, Y axes figures 8a and 8b.
[0040] Fig. 9 illustrates particulars of varied cross sectional passage of individual cell for the extrusion die; in accordance with a present subject matter. In particularly, to the direct metal 3D printing process, the manufacturing cycle time has been reduced by 80% compared to conventional techniques. The quality has been improved and cost has been reduced drastically to 20% as compared with the conventional techniques.
[0041] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0042] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0043] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.