DESC:FIELD OF THE INVENTION
[0001] The present invention relates to the field of manufacturing of aerospace components. Particularly, the present invention relates to the field of additive manufacturing of aerospace components.

[0002] More particularly, the present invention relates to an exhaust nozzle of jet engine and a method of manufacturing the exhaust nozzle.

BACKGROUND OF THE INVENTION
[0003] Gas turbine engines typically include an air intake section, a compressor, a combustor, a turbine, and an exhaust nozzle. The combustion products such as hot exhaust gases flow through the turbine which extracts energy to power the compressor. The exhaust gases leave the turbine flow through the exhaust nozzle and provide propulsive thrust for the engine and set the mass flow rate through the engine.

[0004] Traditionally, exhaust nozzle is made by sheet metal forming followed by spinning and precision joining process or machining from a solid block.

[0005] CN104227344A discloses method of producing a GH5188 square exhaust nozzle used for an aircraft engine. The production method comprises the steps of blanking, heating, heading, punching, rolling and the like, wherein a ring blank obtained by rolling is extruded into a square billet by adopting a squaring process, and a mandrel supporter and a square saddle are adopted to form the exhaust nozzle finally.

[0006] These traditional manufacturing processes have following drawbacks:
? Heavier and more powerful equipment with special tooling’s are required.
? Several different tools need to be used and applied correctly (straightforward face milling to 4- to 5-axis profiling) in machining from a solid block. In this approach, large amount of material volume need to be removed from the solid block, it results enormous material waste (in terms of chips), very high power and cutting tool consumption.

[0007] Accordingly, there is a need for a method of manufacturing the exhaust nozzle

OBJECTS OF THE INVENTION
[0008] It is an object of the present invention to provide an additive manufacturing process for producing exhaust nozzle parts.

[0009] It is another object of the present invention to provide a manufacturing process which results in elimination of drawbacks of existing manufacturing methods as applied to making exhaust nozzle parts.

[00010] It is yet another object of the present invention to provide an additive manufacturing process which can produce desired shaped exhaust nozzle parts with precision and less material waste.

[00011] It is a further object of the present invention to eliminate number of manufacturing processes required to produce the exhaust nozzle assembly.

[00012] It is a further object of the present invention to provide an optimised support for holding the exhaust nozzle parts being printed and dissipating heat to surrounding.

[00013] Other objects and advantages of the present disclosure will be apparent from the following description which is not intended to limit the scope of the present disclosure.

SUMMARY OF THE INVENTION
[00014] According to this invention, an additive manufacturing process is provided for manufacturing of exhaust nozzle assembly. The additive manufacturing is found to be hitherto unknown process for manufacturing exhaust nozzle. In the present manufacturing method, exhaust nozzle parts i.e. inner cone and outer cone are made by using digital model and layer by layer material build-up approach. This tool-less manufacturing method can produce uniform exhaust nozzle parts in a short time with high precision; said additive manufacturing comprises the following steps:
? providing metal powder as a raw material wherein the metal powder is selected from a group consisting of Nickel based alloy, Titanium alloys, Steel and the like;
? providing a 3D printing device;
? spreading said metal powder layer by layer on a predetermined platform;
? selectively fusing said metal powder using at least one energy source at predetermined conditions to perform a printing operation to obtain an inner cone and outer cone separately with a build platform;
? heat treating said inner cone with the build platform and said outer cone with the build platform in a furnace at a predetermined temperature to obtain heat treated inner cone and outer cone with build platform;
? subjecting said heat treated inner cone with a build platform and said outer cone with build platform to wire cutting operation to separate the inner cone and the outer cone from their respective build platforms, followed by shot blasting to generate compressive residual stresses on the surfaces of the inner cone and the outer cone, and buffing operation to obtain the inner cone and the outer cone with predetermined surface finish;
? subjecting said polished inner cone and said outer cone to X-Ray tomography to ensure crack free surface and other surface qualities as well; and
? bolting the inner cone and the outer cone together with the help of supporting rods to obtain the exhaust nozzle assembly.

[00015] In one preferred embodiment, the process comprises a pre-step of printing a support having predetermined configuration meant for holding said exhaust nozzle parts and transferring heat from the part/s being 3D printed to the platform during printing operation, wherein said printing operation comprises spreading metal powder layer by layer on a predetermined platform followed by fusing said powder using at least one energy source at predetermined conditions.

[00016] In another aspect of the present invention, there is provided an exhaust nozzle assembly for a jet engine; said exhaust nozzle assembly (100) comprises 3D printed outer cone (10), supporting rods (20) and 3D printed inner cone (30) wherein the outer cone and the inner cone are bolted by using supporting rods (20).

[00017] In one embodiment, the outer cone (10) comprises a convergent nozzle (12) and an outer shell (14); said convergent nozzle comprises a structured slot (16) adapted to install EGT (exhaust gas temperature) thermocouple on said outer cone (10), through which exhaust gas temperature is monitored; said outer shell (14) comprises different size holes to support the said inner cone (30) by using said supporting rods (20) and connect said exhaust nozzle assembly (100) to the rear flange of a turbine case, wherein the inner cone (10) comprises insertion holes (26) for said supporting rods (20).

BRIEF DESCRIPTION OF DRAWINGS
[00018] The invention will now be described in relation to the accompanying drawings, in which:

[00019] Figure 1 illustrates the three dimensional image of 3D Printed exhaust nozzle assembly (100) in accordance with one embodiment of the present invention;

[00020] Figure 2 illustrates the exhaust nozzle assembly parts (10 and 30) printed by additive manufacturing method of the present invention; and

[00021] Figure 3 illustrates the flow chart of an invented process for exhaust nozzle manufacturing.

DESCRIPTION OF THE INVENTION
[00022] 3D printing, also known as additive manufacturing, refers to a process used to create a three-dimensional object in which layers of material are formed under computer control to create an object. This tool-less manufacturing method can produce fully dense metallic parts in a short time period with high precision.

[00023] According to this invention, there is provided an additive manufacturing method for making exhaust nozzle parts. There is also provided exhaust nozzle assembly made by the method of additive manufacturing.

[00024] In one embodiment, the exhaust nozzle assembly (100) comprises a 3D printed outer cone (10), supporting rods (20) and 3D printed inner cone (30) bolted by using supporting rods (20) with the 3D printed outer cone (10). The exhaust nozzle assembly is illustrated in Fig. 1.

[00025] In one embodiment, the outer cone (10) comprises a convergent nozzle (12) and outer shell (14); said convergent nozzle (12) is the convergent section or taper at the rear end of the said outer cone (10) with an integrated features, through which relatively high pressure, low velocity combustion gas flow accelerates to the sonic or supersonic speed; structured slot (16) on said convergent nozzle (12) is used to install EGT (exhaust gas temperature) thermocouple on said outer cone (10), through which exhaust gas temperature is monitored; said outer shell (14) comprises different size holes to support the said inner cone (30) by using said supporting rods (20) and connect said exhaust nozzle assembly (100) to the rear flange of turbine case as well; structured holes (18) on said outer shell (14) acting as insertion holes for said supporting rods (20); structured purging holes (22) on said outer shell (14) acting as connecting media between said exhaust nozzle assembly (100) and the rear flange of turbine case; structured round hole (24) on said outer shell (14) acting as insertion hole for EGT (exhaust gas temperature) thermocouple. Fig. 2A and 2B illustrate the details of exhaust nozzle assembly parts.

[00026] In one embodiment, the inner cone (10) comprises insertion round holes (26) for said supporting rods (20). The inner cone (10) collects the exhaust gases discharged from the turbine assembly and gradually convert them into a solid jet.

[00027] In at least an embodiment of this invention, the exhaust nozzle assembly comprising these above-mentioned features are designed and rendered using a rendering software. The 3D models of inner cone and outer cone are then used as an input for the additive manufacturing process.

[00028] In one embodiment, the outer cone comprises complex geometry with pre-defined and structured features. With the use of this additive manufacturing process, there is reduction in tooling for making holes and for welding of thin wall.

[00029] Example embodiments will now be described more fully with reference to the accompanying drawings. The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[00030] Figure 1 illustrates the three dimensional image of 3D printed exhaust nozzle assembly. This is referenced by numeral 100;

[00031] Figure 2 (A & B) illustrates the exhaust nozzle parts printed by additive manufacturing method of the present invention; and

[00032] Figure 3 illustrates the flow chart of an invented process for exhaust nozzle manufacturing.
[00033] In one of the preferred embodiments of the present invention, the manufacturing method for producing the exhaust nozzle assembly for jet engines comprises a selective laser sintering process. The inventive feature of this invention is the design and development of the exhaust nozzle assembly and the manufacturing process to make the same.

[00034] In accordance with another aspect, the present invention provides a process for manufacturing of exhaust nozzle assembly. The process involves additive manufacturing of exhaust nozzle assembly. The additive manufacturing according to the present invention involves the following steps:

[00035] In the first step, metal powder as a raw material and a 3D printing device is provided or kept ready. In the second step, the metal powder is spread layer by layer on a predetermined platform of 3D printing device. Typically, the temperature of said platform is set in the range of 80 to 160 °C. In one preferred embodiment, the temperature is set at 120 °C.

[00036] Typically, the layer has a thickness in the range of 0.02 to 0.08 mm and a laser strip width in the range of 5 to 10 mm. Typically, the strip overlap between the layers is in the range of 0.10 to 0.15 mm.

[00037] In one embodiment, the spreading comprises controlled deposition of the layers of metal powder to form holes, apertures and slots in the said inner cone and said outer cone. In one embodiment, the spreading comprises depositing layers of a metal powder sequentially one upon the other to form features.

[00038] After spreading, the powder is selectively fused using at least one energy source at predetermined conditions to perform a printing operation to obtain an inner cone with a build platform and outer cone with a build platform separately. Typically, the energy source is selected from the group consisting of laser beam and electron beam. The energy source has a scanning speed of about 800 to 1400 mm/second and has power of 80 to 400 watt. In one embodiment, the build platform for the inner cone and the outer cone is same or different.

[00039] In the third step, the inner cone with build platform and the outer cone with build platform are heated in a furnace at a predetermined temperature followed by cooling to room temperature to obtain heat treated inner cone with build platform and outer cone with build platform.

[00040] In one preferred embodiment, the heat treatment step involves the following steps:
[00041] Step a: annealing the inner cone with build platform and the outer cone with build platform at a temperature ranging from 900 to 1200 °C for a period ranging from 30 minutes to 120 minutes in an inert Argon atmosphere followed by cooling to room temperature. The output of this step is annealed inner cone with build platform and annealed outer cone with build platform
[00042] Step b: ageing the annealed inner cone with build platform and the annealed outer cone with build platform by holding the parts at a temperature ranging from 700 to 800 °C for a time period ranging from 5 to 10 hours in an inert Argon atmosphere followed by cooling to a temperature ranging from 625 to 675 °C in 1 to 3 hours and holding at a temperature ranging from 625 to 675 °C for 6 to 10 hours in an inert Argon atmosphere.

[00043] Step c: air cooling said parts with a build platform to room temperature. The output of this stage is heat treated inner cone with build platform and heat treated outer cone with build platform.
[00044] In the fourth step, the heat treated inner cone with build platform and the heat treated outer cone with build platform are subjected to wire cutting operation to separate the inner cone and the outer cone from their respective build platform. The output of this step is separated inner cone and separated outer cone.
[00045] In the fifth step, the separated inner cone and the separated outer cone are subjected to shot blasting to generate compressive residual stresses on the surfaces of the inner cone and the outer cone. The output of this step is shot blasted inner cone and shot blasted outer cone.
[00046] In the sixth step, a buffing operation is performed on shot blasted inner cone and shot blasted outer cone to obtain buffed inner cone and buffed outer cone with pre-determined surface finish.
[00047] In the seventh step, an X-Ray tomography is performed on buffed inner cone and buffed outer cone to ensure crack free surface and other surface qualities as well.
[00048] In the eighth step, the inner cone and the outer cone are bolted together with the help of supporting rods to obtain the exhaust nozzle assembly.

[00049] In accordance with a preferred embodiment of the present invention the process comprises a pre-step of printing a support having predetermined configuration meant for holding said exhaust nozzle assembly parts and transferring heat from the part/s being 3D printed to the platform during printing operation, wherein said printing operation comprises spreading metal powder layer by layer on a predetermined platform followed by fusing said powder using at least one energy source at predetermined conditions.

[00050] The 3D printing or additive manufacturing process consists of making a part layer by layer. The required amount of a layer of powder is fused using an energy source. Each new layer of fused powder requires support from layer beneath it (formed previously). Exhaust nozzle parts have overhang or bridge thus needs use of 3D printed support structures to ensure a successful print. The support structures are found to have both positive as well as negative effects on the 3D printing process. On the one hand the support structures help in transfer of heat, prevent extreme powder inclusion, support the overhanging part of the product and secures the part against detachment during the building process. On the other hand the support structure leads to waste of material, may affect the surface finish of the product and leads to requirement of post processing operations to remove it. Hence, it is found that the selection of type and geometry of support structure is critical for defect less manufacturing, ease of manufacturing and economic manufacturing.

[00051] According to the present invention several types of supports which can be used during the 3D printing are tried. The type of support to be used is decided based on the quantity of material required for supports, heat dissipation of product to surrounding, geometry of model etc. Different types of supports which are tried include Block type, Line type, Point type, Web Type, Contour type, Gusset type, Hybrid type and Volume type etc. The support structure with different features like hatching, hatching teeth, fragmentation, borders, border teeth, perforations, gusset borders etc. are experimented.

[00052] Based on the considerations and experimentations, during the manufacturing of the exhaust nozzle assembly, the preferred type of supports used are combination of block support with hatching teeth and perforation type support, volume support and hybrid support.

[00053] Figure 1 illustrates exhaust nozzle assembly printed in an additive manufacturing process. According to the present invention, the manufacturing process starts with providing metal powder as a raw material. The material (metal powder) includes but is not limited to steel, Titanium alloys, Nickel based alloys (IN718, IN713C, IN625 etc.) and the like. Said metal powder is spread on a bed (which is its build platform), layer by layer, and selectively fused by using an energy source like a laser or an electron beam. After completion of the print, the parts are transferred to a furnace, wherein heat treatment is conducted, according to pre-determined parameters, and required properties are achieved. Final heat treated parts are separated from their respective build platforms by using a wire cutting operation. After that, the shot blasting and buffing operations are conducted on the resultant exhaust nozzle parts. Then, the X-ray tomography i.e. NDT test is conducted on the exhaust nozzle parts for surface crack detection and quality inspection. Finally, the inner cone and the outer cone are bolted together with the help of supporting rods to obtain the exhaust nozzle assembly.

[00054] The exhaust nozzle manufacturing process is described, in detail, as below.

[00055] As shown in Figure 2, the manufacturing process, of the current invention, typically, involves the following steps:

[00056] CAD Model generation:
Producing a digital model of the part (i.e. the exhaust nozzle assembly) is the first step in the additive manufacturing process. The digital model is produced by using computer aided design, refer fig. 1. Then, this CAD model is converted into a stereo lithography / Surface Tesselation Language / Standard Triangulation Language file (STL) (STL) which is used by further portions and processes of this invention.

[00057] Additive Manufacturing program generation:
Once an STL file is generated, the file is imported into MAGICS MATERIALISE software. MAGICS is used for defining part orientation and generating support. Then, STL file is sent to the slicer software for slicing. After slicing, the file is imported in EOSPRINT software. EOSPRINT software is used for assigning the build parameters and these further are optimized for CAD data. Then parameters such as laser power, scanning speed, hatch distance and layer thickness are designed. Finally, the file is exported to the 3D printing machine for producing the part.

[00058] Additive Manufacturing or 3D printing:
Different types of materials can be used for manufacturing exhaust nozzle parts which include but not limited to Steel, Titanium alloy, Nickel Based alloys (IN718, IN713C, IN625 etc.) and the like. Material is provided in the form of powder. Metal powder is spread on the platform layer by layer with a layer thickness of 0.020 mm. During this activity, platform temperature is maintained at 120 ºC throughout the process. After spreading each layer, powder is selectively fused by using a laser with a scanning speed of 1100 mm/Sec for parts and 500 mm/Sec for support in an Argon environment. The output of this process is the exhaust nozzle parts with a build platform i.e. the inner cone with build platform and the outer cone with build platform. The summary of parameters used to produce the exhaust nozzle parts in additive manufacturing is mentioned in table 1.

Table 1
Parameters Exhaust Nozzle
Part
Layer thickness 0.020 mm
Platform temperature 120 ºC
Chamber environment Argon
Skip layer 0
Scanning speed 1100 mm/Sec
Laser Power 200 Watt
Strip Width 5 mm
Beam offset 0.015
Strip Overlap 0.12 mm
Support
Layer thickness 0.020 mm
Platform temperature 120 ºC
Chamber environment Argon
Skip layer 1
Scanning speed 1100 mm/Sec
Laser Power 200 Watt

[00059] Heat treatment:
Heat treatment is carried out on the inner cone with build platform and the outer cone with build platform to achieve the mechanical properties and destress the parts. In one illustrative embodiment firstly, the inner cone with build platform and the outer cone with build platform are solution annealed at 1065 °C for one hour in an inert Argon atmosphere, followed by air cooling to room temperature to obtain an annealed inner cone with build platform and an annealed outer cone with build platform. The second heat treatment is ageing. In this treatment, the annealed inner cone with build platform and the annealed outer cone with build platform are held at 760 °C for ten hours in an inert Argon atmosphere, after that they are furnace cooled to 650 °C in two hours and then held at 650 °C for eight hours in an inert Argon atmosphere. Finally, the inner cone with build platform and the outer cone with build platform are air cooled to the room temperature to obtain heat treated inner cone with build platform and heat treated outer cone with build platform. The above heat treatment is performed for IN718. The mechanical properties achieved after heat treatment are summarised in table 2. The below provided properties and values are illustrative and not considered as limitation to scope of the present invention.

Table 2
Mechanical properties Value
Tensile strength Min 1241 MPa
Yield strength 1150 MPa
Elongation 12 %
Hardness 47 HRC

[00060] Wire cutting and support removal:
The heat treated inner cone with build platform and the heat treated outer cone with build platform are separated from the build platforms by using wire cutting operation. Finally, the supports formed during the 3D printing operation are machined off. The output of this operation is separated inner cone and separated outer cone.

[00061] Shot Blasting and Buffing
In this step, shot blasting is performed on separated inner cone and separated outer cone to generate compressive residual stresses on the surfaces of the exhaust nozzle parts, and buffing operation is performed to obtain the exhaust nozzle parts with pre-detrmined surface finish.

[00062] NDT (Non-destructive testing)
In this step, the exhaust nozzle parts are tested for surface quality and cracks by X-Ray tomography, as the step of NDT in accordance with another implementation of the present invention.

[00063] Assembly
Finally, the inner cone and the outer cone are bolted together with the help of supporting rods to obtain the exhaust nozzle assembly.

[00064] In accordance with another aspect of the present invention there is also provided an exhaust nozzle assembly made by 3D printing method of the present invention. Said exhaust nozzle assembly is characterized by predetermined structural configuration and desired properties. In one embodiment, the exhaust nozzle assembly is illustrated in figure 1.
[00065] In accordance with the present invention there is provided a system for 3D printing of exhaust nozzle assembly. Said system comprises a printing device and at least one support means.

[00066] In one embodiment, the supports used to build this part consist of grooves/ teeth. The arrangement of grooves/teeth enable easy removal of support. Support height is optimised for better heat transfer (heat dissipation) between build platform and job at the time of part building. It also avoids distortion of in the part. The amount of support required to build the part is based on the orientation of part. The optimized orientation is selected based on least amount of material required for support generation, minimum laser travel time for generating the support, support free critical areas of the component and height of support that dissipates better heat transfer to build platform from job. Based on above factors for optimized orientation of exhaust nozzle assembly parts i.e. inner cone and outer cone, the preferred type of supports used are combination of block support with hatching teeth and perforation type support, volume support and hybrid support and the height of supports is selected from the range of 7 to 2 mm.

[00067] While this detailed description has disclosed certain specific embodiments for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
,CLAIMS:We claim:
1. An additive manufacturing process for manufacturing an exhaust nozzle assembly; said method comprises the following steps:
a) providing metal powder as a raw material, wherein the metal powder is selected from a group consisting of Nickel based alloys, Titanium alloys and Steels;
b) providing a 3D printing device;
c) spreading said metal powder layer by layer on a predetermined platform;
d) selectively fusing said metal powder using at least one energy source at predetermined conditions to perform a printing operation to obtain an inner cone with build platform and outer cone with build platform separately;
e) heat treating said inner cone with build platform and said outer cone with build platform in a furnace at a predetermined temperature followed by cooling to room temperature to obtain heat treated inner cone with build platform and heat treated outer cone with build platform;
f) subjecting said heat treated inner cone with build platform and said heat treated outer cone with build platform to wire cutting operation to separate the inner cone and the outer cone from their respective build platform, followed by shot blasting to generate compressive residual stresses on the surfaces of the inner cone and the outer cone, and buffing operation to obtain the inner cone and the outer cone with pre-determined surface finish;
g) subjecting said inner cone and said outer cone to X-Ray tomography to ensure crack free surface; and
h) bolting the inner cone and the outer cone together with the help of supporting rods to obtain the exhaust nozzle assembly.

2. The process as claimed in claim 1, wherein the build platform for the inner cone and the outer cone is same or different.

3. The process as claimed in claim 1, wherein the process comprises a pre-step of printing a support having a pre-determined configuration meant for holding said exhaust nozzle parts and transferring heat from the exhaust nozzle parts being 3D printed to the platform during printing operation.

4. The process as claimed in claim 1, wherein the metal powder is IN718 and the temperature of the platform is set in the range of 80 to 160 °C, preferably 120 °C.

5. The process as claimed in claim 1, wherein the exhaust nozzle assembly is designed and rendered using a rendering software, from which the 3D Models of inner cone and outer cone are used as an input for the additive manufacturing process.

6. The process as claimed in claim 1, wherein the layer has a thickness in the range of 0.02 to 0.08 mm, preferably 0.02 mm and a laser strip width in the range of 5 to 10 mm, preferably 5 mm.

7. The process as claimed in claim 1, wherein the overlap between the layers is in the range of 0.10 to 0.15 mm, preferably 0.12 mm.

8. The process as claimed in claim 1, wherein the spreading comprises depositing layers of a metal powder sequentially one upon the other to form features.

9. The process as claimed in claim 1, wherein the energy source is selected from the group consisting of laser beam and electron beam, wherein the energy source has a scanning speed of about 800 to 1400 mm/second, preferably 1100 mm/second and has power of 80 to 400 watt, preferably 200 watt.

10. The process as claimed in claim 1, wherein the heat treating step involves the following steps:
? annealing the inner cone with build platform and the outer cone with build platform at a temperature ranging from 800 to 1200 °C for a period ranging from 30 minutes to 120 minutes in an inert Argon atmosphere followed by cooling to room temperature;
? ageing the inner cone with build platform and the outer cone with build platform by holding the inner cone with build platform and the outer cone with build platform at a temperature ranging from 700 to 800 °C for a time period ranging from 5 to 10 hours in an inert Argon atmosphere followed by cooling to a temperature ranging from 625 to 675 °C in 1 to 3 hours and holding at a temperature ranging from 625 to 675 °C for 6 to 10 hours in an inert Argon atmosphere; and
? air cooling said the inner cone with build platform and the outer cone with build platform to room temperature.

11. The process as claimed in claim 1, wherein the support is selected from Block type, Line type, Point type, Web Type, Contour type, Gusset type, Volume support and Hybrid support, preferably, the support is combination of block support with hatching teeth and perforation type support, volume support and hybrid support, wherein the height of said supports is selected from the range of 7 mm to 2 mm.

12. A process for manufacturing an exhaust nozzle assembly, said process comprising the following steps:
a. generating a CAD model using computer aided design;
b. converting the model into a Stereolithography / Surface Tesselation Language / Standard Triangulation Language file (STL);
c. generating additive manufacturing program by importing STL file into a MAGICS MATERIALISE software adapted to define part orientation and generate support;
d. transferring the STL file to a slicer software for slicing;
e. importing the file in an EOSPRINT software adapted for assigning the build parameters which are further optimized for CAD data;
f. designing parameters selected from laser power, scanning speed, hatch distance and layer thickness;
g. exporting the file to the 3D printing machine for producing the exhaust nozzle parts;
h. spreading metal powder layer by layer on a predetermined platform;
i. selectively fusing said metal powder using at least one energy source at predetermined conditions to perform a printing operation to obtain an inner cone with build platform and outer cone with a build platform separately;
j. heat treating said inner cone with build platform and said outer cone with build platform in a furnace at a predetermined temperature followed by cooling to room temperature to obtain heat treated inner cone with build platform and heat treated outer cone with build platform
k. subjecting said heat treated inner cone with build platform and said heat treated outer cone with build platform to wire cutting operation to separate the inner cone and the outer cone from their respective platform, followed by shot blasting to generate compressive residual stresses on the surfaces of the inner cone and the outer cone, and buffing operation to obtain the inner cone and the outer cone with pre-determined surface finish;
l. subjecting said inner cone and said outer cone to X-Ray tomography to ensure crack free surface; and
m. bolting the inner cone and the outer cone together with the help of supporting rods to obtain the exhaust nozzle assembly.

13. The process as claimed in claim 12, wherein the heat treatment comprises solution annealing the inner cone with build platform and the outer cone with build platform at 900 to 1200 °C for one hour in an inert Argon atmosphere, followed by air cooling to room temperature; holding the inner cone with build platform and the outer cone with build platform at 700 to 800 °C for 5 to 10 hours in an inert Argon atmosphere followed by furnace cooling to 625 to 675 °C in 1 to 3 hours, holding at 625 to 675 °C for 6 to 10 hours in an inert Argon atmosphere and air cooling to the room temperature.

14. An exhaust nozzle assembly (100) for a jet engine; said exhaust nozzle assembly comprises a 3D printed outer cone (10), 3D printed supporting rods (20) and a 3D printed inner cone (30), wherein the 3D printed outer cone and the 3D printed inner cone are bolted by using supporting rods (20).

15. The exhaust nozzle assembly as claimed in claim 14, wherein said outer cone (10) comprises a convergent nozzle (12) and an outer shell (14); said convergent nozzle comprises a structured slot (16) adapted to install EGT (exhaust gas temperature) thermocouple on said outer cone (10), through which exhaust gas temperature is monitored; said outer shell (14) comprises different size holes to support the said inner cone (30) by using said supporting rods (20) and connect said exhaust nozzle assembly (100) to the rear flange of a turbine case, wherein said inner cone (10) comprises insertion holes (26) for said supporting rods (20).

16. The exhaust nozzle assembly as claimed in claim 14, characterized in that said exhaust nozzle exhibits a tensile strength of >1241 MPa, a yield strength of about 1150 MPa and a hardness of about 47 HRC.

17. A system for manufacturing exhaust nozzle assembly by 3D printing method, said system comprises a 3D printing device and a support, wherein the support comprises teeth/grooves adapted to enable easy removal of supports, wherein height of support corresponds to height of build platform in order to dissipate heat between build platform and job at the time of part building and avoiding distortion of exhaust nozzle parts.

Dated this 31st day of March, 2019

CHIRAG TANNA
of NOVO IP
APPLICANT’S PATENT AGENT