Field of Invention
The present invention relates to Combustion liner bodies used in gas turbines. More particularly, the present invention relates to a process for manufacturing combustion liner bodies used in Gas Turbine.
BACKGROUND OF THE INVENTION
Combustion liners are generally used in the combustion section of a gas turbine engine which is located between the compressor and turbine sections of the engine. The combustion liner of the Gas Turbine encompasses the flame zone where the fuel air mixture undergoes a chemical reaction that produces the required power for extraction in the downstream turbine.
Gas turbine engines often have a dilution air zone in the combustor immediately downstream of a flame zone. Dilution air is injected into the combustor to control the temperature of the hot gases before they enter the nozzle on their way to the turbine blades. A very stringent Controlled flow of air for combustion and dilution from the compressor discharge casing into the liner is essential both for effective combustion and for providing the necessary dilution and cooling of flue gases before they enter the turbine section. The liner ripples play an Important role in gas turbine combustion system, Liner ripples allow compressed air through dilution holes, approximately 25 – 30 percent to attain the desired fuel-air ratio and rest is used to form an air blanket around the burning gases, if the liner ripples are not uniform an un-even temperature distribution exist in side surface of liner body and will cause to reduce the life of liner. If the hot gas temperature is not diluted evenly, the turbine section will be going to destroyed by excessive heat.

US 5413647 A teaches a Method for forming a thin-walled combustion liner for use in a gas turbine engine. This invention relates to a method for manufacturing a thin-walled generally cylindrical-shaped member, suitable for use as a combustion liner within a gas turbine engine. manufacture of combustion liner is made by using vacuum centrifugal casting techniques.
US 6553767 B2 describes a Gas turbine combustor liner with asymmetric dilution holes machined from a single piece form. This invention includes a method for making the annular gas turbine engine combustor liner and the method includes forming a single piece integrally formed near net shape form for the axially extending single piece annular shell circumscribed about the first axis of revolution then machining the annular shell having a hot side and a cold side and the annular dilution hole section of the shell, and then drilling the plurality of asymmetrical cylindrical dilution holes extending through the section.
Thus, the known prior art, teaches and suggests the combustion liners which are fabricated by using Jaws with expander method: In such known methods, the Jaws are expanded to required diameter and the jaws are rotated to form rippling on circular body. Profile of ripples are pre-machined on radial surface of the Jaws. Due to this method of formation, the following difficulties are noticed in prior process: -
•Ripple profile is not uniform throughout surface of liner body.
•Lot of lines and jaws impression marks were formed on surface of liner body during manufacturing.
•Due to non-uniformness of Ripples, profile template is not matching.
•Utmost care to be taken while shifting of jaws from one row of ripple to next row, if any mistake has happened while shifting, the complete job need to be scrapped.
•Profiles of one Ripple to other ripple is not uniform

•Due to high spring back of Haste alloy material lot of iteration are needed to get required profile.
•To manufacture one liner body takes 16 hours of time
•Post Correction on the ripples are not possible (once ripples are formed)
•Jaws impressions are evitable on liner surface at gap between jaws.
•Aesthetic look of job worse
•Four to five steps are required to complete the one job.
•Concentricity's of ripples are not uniform. (it was observed more than 7mm instead of 2.5 mm)
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a process for manufacturing of combustion liner bodies used in Gas Turbine, which eliminates the problems of prior art.
Another object of the invention is to propose a process for manufacturing combustion liner bodies used in Gas Turbine which constitutes a convolute roller technique reducing the manufacturing time and ease the complexity of manufacturing process.
A still another object of the invention is to propose a process for manufacturing of combustion liner bodies used in Gas Turbine, which improves Quality and aesthetic ripples (without jaws impression).
Yet another object of the invention is to propose a process for manufacturing of combustion liner bodies used in Gas Turbine, which allows formation of the liner

in a single step and enables post correction on ripples and improvement in Concentricity's of the ripples.
A further object of the invention is to propose a process for manufacturing combustion liner bodies used in Gas Turbine, which reduces the cost of manufacturing at least by 40%.
SUMMARY OF THE INVENTION
The combustion liner according to the invention is made by convolute roller technique. This manufacturing process has successfully eliminated the prior art difficulties like, combustor liners are manufactured through precision casting or centrifugal casting or single piece. In such case 80% of the original starting material may have to be removed in order to achieve the desired internal/External contour. Accordingly, such prior art machining methods have been found to be both extremely time consuming and wasteful.
convolute roller technique has improved the quality and aesthetics, Concentricity's of the ripples, flexibility in post correction on ripples and reduce the cost.
BRIEF DESCRIPTION OF THE ACCOMANYING DRAWINGS
The proposed invention will be better understood from the description with reference to accompanying figures/drawings in which.
Figs. 1 to 3 – shows the various steps performed in the process of manufacturing according to the invention.
Fig 4 Shows an alloy-sheet cylinder
Fig 5 Shows ripple formation on the cylinder by re-starting rollers

Fig 6 – Shows formation of ripples on the cylinder surface Fig 7 – Shows checking of the liner body by a profile template.
DETAIL DESCRIPTION OF THE INVENTION
•Base stand (item no 1) used as base stand for Convolute roller machine (SPM).
•Inner profile roller (Item no 2): This Roller is machined according to inner profile of the Liner body and checked with a suitable template. Later, the roller is hardened to minimize the wear/ Tear loss. This roller doesn’t move up and down, and rather permanently fixed at one position with bearings disposed at both ends.
•Outer profile roller (Item no 3): This Roller is machined according to outer profile of the Liner body and checked with a suitable template. Later, the outer profile roller is hardened to minimize the wear/ Tear loss. This roller moves up and down by a hydraulic cylinder and limit switch.
•Control cabinet (Item no 4): Control cabinet is used to perform following functions.
•Control supply to a motor
•Emergency stop
•power supply to coil and etc…
•Limit Switch (Item no: 05): Limit switches are used to provide pressure input/cut off to outer profile roller.
•Motor (Item no: 06): this motor allows rotation of the inner profile roller.
Manufacturing procedure: the following steps are used for manufacturing the ripples on liner body.

1. Cut a plate to suitable length and roll to a cylindrical shell, Seam weld, and expand such that the cylinder shall have the outer diameter and axial length equal to an outer diameter and axial length of desired final cylindrical structure. This cylinder body is placed in a restraining cylindrical roller (Item 2 & 3) (both Cylindrical roller are pre-machined to desired ripple profile and axial length). The entire assembly is thereafter rolled between a forming roller die.
2. External pressure is applied on the outer profile roller and simultaneously rolled the liner body till the desired contours of both internal and external profile formed on the Job.
3. Axial growth of the starting cylinder during the contouring operation is inhibited with the help of flanges on a forming machine.
4. By restraining the radial and axial growth during contouring, a high degree of accuracy in the dimensions of the contoured structure is achieved. The resulting structure maintains an inside and outside contour profile exactly matching with desired drawing requirements.
5. Since Haste Alloy-X material generally have a high spring back, which is overcome by repeated rolling of the liner body in the restraining roller.
The following major advantages achieved by adopting convolute roller method for manufacturing the combustion liner body:
I. Quality of Ripples of liner body was increased drastically
II. No jaw impression marks and lines on liner body
III. Ripples Profile templates are exactly matched with job
IV. Easy to manufacture
V. Less time was taken to manufacture the one-line body (30 minutes)

VI. After correction on ripples possible through this technique
VII. Aesthetic look of job was improved drastically
VIII. In a Single step liner body was manufactured

IX. Concentricity’s of ripples are matched with drawing requirement
X. Cost reduced by 40%

We Claim:
1. The proposed process i.e. convolute roller technique for manufacturing of combustion liner bodies used in Gas Turbine, this process comprising of the following steps: -
- Cut a plate to suitable length and roll to a cylindrical shell, Seam weld, and expand such that the cylinder shall have the outer diameter and axial length equal to an outer diameter and axial length of desired final cylindrical structure.
- Pre-machining at-least two cylindrical rollers with desired ripple profile and axial length;
- Planning the cylindrical structure on the cylindrical rollers and the assembly being rolled between a farming roller die;
- Applying external pressure on outer profile roller and rolling the cylindrical body simultaneously to form desired contours on both internal and external profile; and
- Inhabiting axial expansion of the cylindrical body, by using flanges on the forming machine drawing the contouring operation,
Wherein a high degree of accuracy in the dimensions of the contoured structure is achieved by restraining the radial and axial expansion during the contouring operation.