Automation in Nondestructive Examination for Thrust Chamber Assembly of Vikas Engine. Ramdas M Shinde Project Manager, Aerospace TRIGO QUALITY PRODUCTION SERVICES PVT LTD,

http://www.ndt.net/?id=21244 Email: [email protected]

Shakti Singh Deputy Manager NDT, Godrej Aerospace Godrej & Boyce Mfg Co Ltd,Mumbai Email: - [email protected]

More info about this article: Abstract

The Vikas Engine is a liquid fueled rocket engine built by Indian Space Research Organization (ISRO). It was developed at the Liquid Propulsion Systems Center during the 1970s. It is used in the Polar Satellite Launch Vehicle (PSLV) and the Geosynchronous Satellite Launch Vehicle (GSLV) series of expendable launch vehicles for space launch use.

The engine is used as the second stage of both the PSLV and the GSLV launch vehicles, with four strap-on boosters. The engine is also capable of gimballing. The GSLV MK-3 rocket uses two Vikas engines in its L110 core stage. The propellant loading for GSLV Mk-3 Vikas engines is 55 tons compared to 40 tons for regular GSLV Mk-2 and PSLV rockets

The Vikas engine has main element known as Thrust Chamber Assembly in which the actual firing happens & thrust gets developed.The construction of the chamber is welded & has 12 numbers of cirseams.

As its required to carry out Non Destructive for each of the cirseams & the circumference goes on varying thus time consumed is high for adjusting SFD& each film positioning. Thus the fixture was designed for carrying out penetration grinding, dye penetrant testing and positioning divergent assembly on the rotating trolley for carrying out radiography.

Motorized arranged made for the same with separate operator pendant keeping in mind operator safety and ergonomics.

Now further automation is planned as now digital radiography equipment will be synched with the rotating fixture so that the indexing will not be required as well as the digital imaging plate will be deployed to reduce the cycle time of developing the films as imaging plate can be reused.

Scope:

Automation of the Contour and Conical version divergent assembly for rotating, while taking the radiographic exposure. Reducing the cycle time for radiography, reducing fatigue of operator, deskilling the process of rotating divergent assembly manually, and most important is safety during handling.

Historical Information: -

Divergent assembly is the exit portion of the Vikas engine thrust chamber as seen in Sketch-1 Contour version and Conical version chambers are required for the PSLV & GSLV mission of ISRO.

[COMBUSTION CHAMBER] [COMBUSTION (2944 REF.) (2944 [NOZZLE WELD ASSLY] WELD [NOZZLE

Ø1750

Sketch-1 Schematic diagram of Contour version Vikas Engine Thrust Chamber Assembly

Divergent assembly consist of 4 divergent cones.

Si.no Component details CONTOUR VERSION CONICAL VERSION 1 Divergent-1 7 mm 7mm 2 Divergent-2 3.5mm 6mm 3 Divergent-3 2mm 5mm 4 Divergent-4 2mm 2mm

Material of divergent is Stellite (KC20Wn) Cobalt based alloy. Contour divergent assembly weighs 225kg, &Conical divergent assembly weighs-185kg approximately. Refer sketch -2 and sketc-3 for details.

Sketch-2 Contour Divergent Assembly Sketch-3 Conical Divergent Assembly

The cones i.e. divergent-1 to divergent-2, CS 103 and divergent-2 to divergent-3 CS102, Divergent-1 to divergent-3 is CS101 welded circeams.

Si.no Component details CONTOUR CONICAL VERSION VERSION 1 Divergent-4 to divergent-3 CS 102 CS 101 2 Divergent-3 to divergent-2 CS 102 CS 102 3 Divergent-2 to Divergent-1 CS 103 CS 103

After welding penetration grinding is to be done and after flushing, dye penetrant test is conducted. Problem faced was when kept on ground on rubber mat to rotate the assembly 2 persons required to rotate for each sector i.e. for penetration grinding, dye penetrant test as well as while taking radiographic test. Thus to solve all the problem a concept of rotating fixture got realized.

The rotatory fixture ref sketch-4 which gives a schematic representation of fixture.

Sketch-4 Divergent Assembly Fixture for radiography exposure

Salient points of fixture

1) Fixture is on 4 self-aligning Teflon wheels for ease in movement of assembly form one work station to other. 2) Adjustable wheels for Contour version and Conical version for resting of divergent assembly. 3) Stopper provided to ensure divergently remaining in same position while rotating i.e. should not topped down due to swirling motion. 4) For rotator motion a A/C motor drive with chain pulley mechanism given to rotate in controlled manner and slow speed with a pendant. 5) Ease in handling by Penetration grinder, NDT inspector that is for taking dye penetrant test and for NDT radiographic technician. Benefits of the fixture for operators.

1) Light in weight 2) Easily to transport form grinding station to Dye penetrant station and then to radiographic station. 3) Efforts drastically reduced to rotate the assembly. 4) Safety of operator taken by having a stopper at minor end of divergent Assembly and emergency stop on pendant. 5) Faster operation, rather than waiting for other operators for lifting and shifting.

Comparative statement for all 3 process, all the before and after columns are in minutes

PENETRATION GRINDING PROCESS

SI NO Cirseam details Contour version Conical version Before After Before after 1 Penetration grinding of CS 101 150 120 120 100 2 Penetration grinding of CS 102 120 100 100 70 3 Penetration grinding of CS 103 100 80 90 60 Total cycle time reduction in % 20% 25%

 Main advantage for grinding person was that he himself can rotate, rather than calling one more person for rotating, when 1 segment of penetration grinding is over out of balance segments. DYE PENETRATION TESTING PROCESS

Contour version SI NO Cirseam details Before After Before after 1 Dye penetrant test of CS 101 50 40 45 30 2 Dye penetrant test of CS 102 45 30 40 20 3 Dye penetrant test of CS 103 45 30 40 20 Total cycle time reduction in % 23% 40%

 Main advantage for grinding person was that he himself can rotate, rather than calling one more person for rotating, when 1 segment of dye penetrant testing grinding is over out of balance segments. RADIOGRAPHY TESTING PROCESS

Contour version SI NO Cirseam details Before After Before after 1 Dye penetrant test of CS 101 120 60 100 50 2 Dye penetrant test of CS 102 100 50 90 45 3 Dye penetrant test of CS 103 100 50 90 45 Total cycle time reduction in % 50% 50%

 Main advantage for radiography technician was that he himself can rotate, rather than calling one more person for rotating, when each segment of radiography is over out of balance segments. Approximately 50% reduction in cycle time was noticed in radiographic testing.

Fixture cost was approximately – 1.5lakhs

The saving for all above totaled for grinding, Dye penetrant test and radiographic test for year on year basis i.e. 4 engines per year amounts to approximately 2lakhs per year and on goingly. Major focus is ergonomics, reduction in fatigue of operator and then cycle time reduction.

Conclusion: -

After the fixture is conceptualized, designed, drawn and fabricated and implemented major benefits received by organizations are reduction in cycle time for Dye penetrant, penetration grinding, Radiographic testing.

Most fundamental and critical was operator safety i.e. while handling(rotating) probability got reduced to zero due to motorized arrangement. Then as the complete fixture is on trolley thus reduction in cycle time for transporting form one location to other location.