DESC:Field of the invention:
[001] The present invention relates to a divergent nozzle and a method of manufacturing a divergent nozzle.

Introduction:
[002] Convergent-divergent exhaust nozzles are generally used in the jet engines of aircraft. It mainly comprise a convergent passage or portion which is narrowing down from a wide diameter to a smaller diameter in the direction of the flow which serves to accelerate the exhaust gas to sonic velocity and a divergent passage or portion which is expanding from a smaller diameter to a larger one which expands the exhaust gas to supersonic velocity. The nozzle further comprises the nozzle throat area between the convergent portion and the divergent portion and a nozzle exit area at the end of the divergent portion.

[003] Convergent-divergent nozzles are described in few prior art patent documents. For instance, US3004385 discloses variable nozzle structure which provides a variable nozzle throat or convergent portion, variable exit portion which may vary from substantially uniform diameter to a considerably divergent condition, and a variable fairing which streamlines the exhaust end of the engine and changes diameter in accordance with the variation of exit area of the nozzle.

[004] Further, the applicant’s international application, WO2014200402 discloses a variable-geometry convergent-divergent exhaust nozzle for a jet engine which comprises a fixed structure, a first cross sectional area, a second cross sectional area, a plurality of first flap means being pivotally connectable to the fixed structure and a plurality of second flap means being pivotally connected to the plurality of first flap means.

[005] These documents do not provide suggestions or teachings as to forging method to manufacture divergent nozzle. Further, the known conventional method of manufacturing the divergent nozzle involves rolling of metal sheets followed by folding and welding operations to obtain the divergent nozzle.

[006] The methods disclosed in the prior art documents are associated with several drawbacks such as reduced strength of resultant nozzle, high cost, more energy consumption, significant material loss, higher cycle time and the like.

[007] Accordingly, it is desired to provide a forging method which is capable of forming near net shape complex components such as divergent nozzle with reduction in input material, cycle time and cost.

Objects of the invention:
[008] It is an object of the present invention to provide a forged divergent nozzle of better strength /flow properties characteristics.

[009] It is another object of the present invention to provide a forging method for manufacturing a divergent nozzle.

[0010] It is still another object of the present invention to provide a simple and cost effective method for manufacturing a forged divergent nozzle.

[0011] It is yet another object of the present invention to provide a method which reduces cycle time as well as machining time and input material.

[0012] These and other objects, features and advantages will be readily apparent upon consideration of the following detailed description of the invention in conjunction with the accompanying drawing.

Brief Description of Drawings:
[0013] Figure 1 illustrates an invented method for manufacturing a divergent nozzle in accordance with one embodiment of the present invention.

[0014] Figure 2 illustrates an invented method for manufacturing a divergent nozzle in accordance with an additional embodiment of the present invention.

[0015] Figure 3 illustrates an invented method for forging a pre-form to manufacture the divergent nozzle in accordance with another embodiment of the present invention.

Summary of the Invention
[0016] The present invention provides a method of manufacturing a nozzle of a predetermined profile, the method comprising:
? providing an ingot of predetermined size & shape;
? performing a series of operations at least once on the ingot to obtain a pre-form, the series of operations including, pin forming, drawing, upsetting; and stock sizing;
? piercing the pre-form to obtain a pierced pre-form;
? forging the pierced pre-form to obtain a forged pre-form, wherein the pierced pre-form is taper forged; and
? machining the forged pre-form to obtain the nozzle of predetermined profile.

[0017] The present invention also provides a forged divergent nozzle obtained by the method of the present invention.
[0018] In one embodiment, the predetermined profile of the nozzle is trapezoidal shape and the ingot is a fluted ingot.

Description of the invention:
[0019] In accordance with the present invention there is provided a method and system of manufacturing a divergent nozzle by open die forging of ingot in order to provide a near net shape nozzle. In accordance with one embodiment of the present invention the open die forging comprises taper forging operation. In an implementation the present invention manufactures complex, large and critical components such as divergent nozzle using less input material and less machining operation. Further, the method of the present invention provides technical advancement over the known manufacturing methods as it reduces the cycle time, energy consumption. Still further, the method is economically significant as it reduces the manufacturing cost and it can be carried out on a low capacity forging equipment (hydraulic/mechanical).

[0020] In one embodiment, the method of manufacturing a nozzle of a predetermined profile, in accordance with the present invention involves the following steps.
? providing an ingot of predetermined size & shape;
? performing a series of operations at least once on the ingot to obtain a pre-form, the series of operations including, pin forming, drawing, upsetting; and stock sizing;
? piercing the pre-form to obtain a pierced pre-form;
? forging the pierced pre-form to obtain a forged pre-form, wherein the pierced pre-form is taper forged; and
? machining the forged pre-form to obtain the nozzle of predetermined profile

[0021] In one embodiment, the predetermined profile of the nozzle is trapezoidal shape and the ingot is a fluted ingot. Typically, the upsetting is performed by a Forging press. In one embodiment, the the stock sizing further comprise cutting the pre-form to obtain at least two equally sized pre-forms. Further, in one embodiment the piercing further comprises piercing in equally sized pre-forms.

[0022] In one the embodiments, the forging operation further comprises:
? setting the pierced pre-form for forging by performing simultaneous operations, the simultaneous operations including holding the pierced pre-form, rotating the pierced pre-form, and pressing the rotating pierced pre-form against an anvil surface; and
? taper forging the rotating pierced pre-form to generate taper on inner portion of the pierced pre-form to obtain the nozzle of pre-determined shape.

[0023] In one preferred embodiment, the forging is carried out by open-die forging and the pressing is performed using a forging press.
[0024] The method of the present invention characterized in that the piercing comprises piercing the pre-form using at least one pre-formed die or at least one mandrel which is being pressed in the centre of the pre-form.

[0025] In one embodiment, the inner portion of the pierced pre-form is tapered using a rotary mandrel or preformed die.

[0026] In another embodiment, the piercing operation comprises pressing preformed mandrel or die using a second mandrel or die to perform effective piercing.

[0027] In still another embodiment, the method the method comprises the following steps:

- holding and pressing one end of said pre-form and rotating said pre-form; and
- piercing and tapering said pre-form using a preformed mandrel or die while said pre-form is in a rotating motion, said tapering adapted to taper an inner portion of said pierced pre-form to obtain a divergent nozzle.

[0028] Figure 1 and 2 illustrate methods for manufacturing a divergent nozzle of a predetermined profile, according to an implementation of the present subject matter.

[0029] Referring to Fig. 1, at block 102, a fluted ingot of a predetermined size is obtained. The fluted ingot obtained at block 102 is used to manufacture the divergent nozzle of predetermined profile. Figure 2 at block 2a illustrates the fluted ingot obtained.

[0030] At block 104, a plurality of serial operations is performed on the fluted ingot, obtained at block 102. The plurality of serial operations is performed to obtain a pre-form.

[0031] In accordance, with an embodiment the plurality of serial operations may be pin forming, drawing, upsetting, and stock sizing. Figure 2, illustrates the serial operations at blocks 2b – 2i.

[0032] In accordance with another embodiment the plurality of serial operations may be performed on the fluted ingot at least once.

[0033] In accordance with an implementation the plurality of serial operations may be performed on the fluted ingot more than once, as illustrated in figure 2 at blocks 2b-2i.

[0034] At block 2b pin forming and drawing operation is performed on the fluted ingot obtained at block 2a. The fluted ingot is subjected to upsetting at block 2c. Again at block 2d, pin forming and drawing operation is performed, and at block 2e, upsetting is performed on the fluted ingot. After yet another pin forming and drawing operation at block 2f, stock sizing of the fluted ingot is performed at block 2g. In an example, the fluted ingot is divided into three stock parts at block 2g as a part of stock sizing operation. In an example, hot cutting operation is performed to obtain three stock parts.

[0035] In accordance with an embodiment, each stock part obtained after stock sizing at 2g may be worked upon as an individual fluted ingot.

[0036] At block 2h upsetting of each individual fluted ingot obtained at block 2g is done, before pin forming and drawing at block 2i. As, a result of pin forming and drawing at block 2i, a pre-form is obtained at block 2i.

[0037] The pre-form is subjected to piercing at block 106. Piercing of pre-form results in formation of pierced pre-form. In one of the preferred embodiments of the present invention the piercing operation comprises piercing the stock using at least one preformed die or mandrel (first die) which is being pressed in the center of the pre-form. In another embodiment an additional die (second die ) or r mandrel may be used to press the first die or mandrel to perform piercing effectively.

[0038] The pierced pre-form is forged at block 108 of figure 1 and block 2j of the figure 2, to obtain a forged pre-form. In an implementation the forging may be taper forging. Also, details of process of forging shall be explained with description of figure 3.

[0039] The forged pre-form is subjected to machining at block 110 of figure 1 and block 2k of figure 2, to obtain the divergent nozzle of predetermined profile.

[0040] In one embodiment of the present invention the method of manufacturing a divergent nozzle comprises the following steps:
- providing an fluted ingot of pre-determined size;
- subjecting said fluted ingot to pin forming; drawing; upsetting; drawing; upsetting; stock sizing; and upsetting to obtain a pre-form;
- piercing said pre-form to form pierced pre-form; and
- taper forging said pierced pre-form and machining to obtain a divergent nozzle of a pre-determined size.

[0041] In one exemplary embodiment, a hydraulic press is used for manufacturing a divergent nozzle by open die forging. The ingot is bottom poured and subjected to heating in an EAF (electric arc furnace)-LF -VD (vacuum degassing) at a temperature of about 500-7000C. The temperature of the ingot is raised with rate of about 1000C per hour to get the temperature of 1230-12600C. After achieving the desired temperature, the ingot is brought to the forging press and subjected to open-die forging.

[0042] The ingot is subjected to pin forming, drawing, upsetting, drawing, and upsetting. After upsetting. Each stock piece is then subjected to upsetting , piercing and taper forging operations.

[0043] Figure 3 illustrates a method of forging a pierced pre-form to obtain a divergent nozzle of pre-determined shape, in accordance with an embodiment of the present subject matter.

[0044] At blocks 302-306, setting of the pierced pre-form for taper forging by performing simultaneous operation is performed. The simultaneous operations consist of holding the pierced pre-form, block 302; rotating the pierced pre-form, block 304; and pressing the rotating pierced pre-form, block 306.

[0045] In an implementation the pressing of the rotating pierced pre-form performed by a preformed die or mandrel.

[0046] At block 308, taper forging of the set rotating pierced pre-form to taper an inner portion of the pierced pre-form is performed to obtain the divergent nozzle of pre-determined shape.

[0047] In accordance with another aspect of the present invention there is provided a forged divergent nozzle obtained by the method of the present invention.

[0048] Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0049] The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

[0050] Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

[0051] The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

[0052] While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

,CLAIMS:We claim:
1. A method of manufacturing a nozzle of a predetermined profile, the method comprising:
? providing an ingot of predetermined size & shape;
? performing a series of operations at least once on the ingot to obtain a pre-form, the series of operations including, pin forming, drawing, upsetting; and stock sizing;
? piercing the pre-form to obtain a pierced pre-form;
? forging the pierced pre-form to obtain a forged pre-form, wherein the pierced pre-form is taper forged; and
? machining the forged pre-form to obtain the nozzle of predetermined profile.

2. The method as claimed in claim 1, wherein the predetermined profile of the nozzle is trapezoidal shape.

3. The method as claimed in claim 1, wherein the ingot is a fluted ingot.

4. The method as claimed in claim 1, wherein the upsetting is performed by a Forging press.
5. The method as claimed in claim 1, wherein the stock sizing further comprise cutting the pre-form to obtain at least two equally sized pre-forms.

6. The method as claimed in claim 1, wherein the piercing further comprises piercing in equally sized pre-forms.

7. The method as claimed in claim 1, wherein the forging operation further comprises:
? setting the pierced pre-form for forging by performing simultaneous operations, the simultaneous operations including holding the pierced pre-form, rotating the pierced pre-form, and pressing the rotating pierced pre-form against an anvil surface; and
? taper forging the rotating pierced pre-form to generate taper on inner portion of the pierced pre-form to obtain the nozzle of pre-determined shape.

8. The method as claimed in claim 1, wherein the forging is open-die forging.

9. The method as claimed in claim 7, wherein the pressing is performed using a forging press.
10. The method as claimed in claim 1, wherein said method characterized in that the piercing comprises piercing the pre-form using at least one pre-formed die or at least one mandrel which is being pressed in the centre of the pre-form.

11. The method as claimed in claim 7, wherein the inner portion of the pierced pre-form is tapered using a rotary mandrel or preformed die.

12. The method as claimed in claim 1, further comprises i) bottom pouring of the ingot followed by heating in an EAF (electric arc furnace)-LF -VD (vacuum degassing) at a temperature of about 500-7000C; ii) raising the temperature of the ingot with a rate of about 1000C per hour to achieve the temperature of 1230-12600C; iii) bringing the heated ingot onto the forging press; iv) subjecting said ingot to pin forming, drawing, upsetting, drawing, and upsetting to obtain a piece; v) hot cutting said piece to obtain three equal size stock pieces; and subjecting each stock piece to upsetting, piercing operation and taper forging.

13. The method as claimed in claims 1 to 12, wherein piercing operation comprises pressing preformed mandrel or die using a second mandrel or die to perform effective piercing.

14. The method as claimed in claim 1, wherein the method comprises the following steps:

- holding and pressing one end of said pre-form and rotating said pre-form; and
- piercing and tapering said pre-form using a prefornmed mandrel or die while said pre-form is in a rotating motion, said tapering adapted to taper an inner portion of said pierced pre-form to obtain a divergent nozzle.

15. A forged divergent nozzle obtained by the method as claimed in any of the claims 1 to 14.

Dated this 19 August 2017

Applicant’s Patent Agent