FIELD OF THE INVENTION:
The present invention relates to a method of welding of leaded phosphor bronze (containing 5% Lead with 15% Tin) and brass (4% Lead and 3.6% Tin) casting used as Bell for Temple and more particularly the invention relates to a set of parameters and techniques required in welding of leaded phosphor bronze and brass casting/ material of temple Bell.
BACKGROUND OF THE INVENTION:
Temples generally have one metal bell hanging at the entrance and devotees ring the bell while entering the temple. Priest and devotees ring bells during the puja. There are bells specially made to produce the long strains of the sound. The sound of the bell is considered auspicious which welcomes God. The sound of the bell is said to disengage mind from ongoing thoughts thus making the mind more receptive. Bell ringing during prayer is said to help in controlling the ever Wandering mind, and focusing on the deity. The bell is generally made out of brass and bronze by casting, both are alloy of copper. Casting is a manufacturing process, in every bell a clapper is attached to the inside and the bell makes a high pitched sound when ring. The clapper is made to the bell on its inside surface to produce sound and that is how the bell rings. The clapper (as shown in Fig 2) when made to hit the bell at the same place on its inner surface of the bell for longer time, the bell in subjected to mechanical loading due to which the bell material goes through plastic deformation and hence develop cracks most of times. “Cracks are linear separation”. Due to these cracks the bell doesn’t ring properly. The discontinuity in the form of Crack in the bell dampens the vibrations that is caused by the bell ringing (when clapper hits the liner Surface). After all it is the sustained vibrations that brings the rhythm to the bells ring tone. With cracks it reaches shorter reaches less loud and gets dampened in no time. The bell no longer rings like a bell (as given in figure 1). The reason for the cracks in bell could be anything like small defects in the casting especially opening up, wear and tear of the material in addition

to the impact at the same spot, as mentioned above. There are many bells in temples around Tamilnadu. And there are many villagers staying around these famous temple, they wake up to the ringing of bell and time their daily routine to the toll of the bell. When such bell stops ringing due to crack/defects. The people find themselves less alive. Hence at WRI we took the decision of restoring (repair welding) the bells (Putting the Bell back into its ringing tone).
The bell casting being from the non-industrial era, is subjected to modern way of metallurgical studies. At this stage the challenges were to identify all the surface defects, followed by knowing the chemical composition, arriving at the correct preheat and inter pass temperature suitable as per chemistry for given bell thickness & filler wire and welding process.
Hence, there is always a need for developing a method which can heal the crack easily and bring back the rhythmic sound effectively.
The present invention needs the long felt need.
SUMMARY OF THE INVENTION:
A welding method of bell comprises the steps of: i) holding the bell in fixture depending upon the geometry of the casting; ii) preheating the bells by keeping it in the furnace at certain temperature for a suitable soaking time along with filler wire depending on the chemistry of the bells; iii) after preheating, the bell is taken out in the grove volume and subjected to heating with gas torches while maintaining the inter pass temperature and the grove is filled completely with stirring the weld puddle; iv) covering of the bells casting immediately after the welding with insulating cloths like glass wool and subjected to post weld heat treatment (PWHT) at an appropriate temperature; v) after post weld heat treatment (PWHT), the extra weld metal is grounded and the bell is brought back to shape and subjected to some checking for weld integrity and sound quality by x-ray inspection and hitting with clapper.

OBJECTS OF THE INVENTION:
It is therefore, the primary object of the present invention is to provide a novel welding technique for bells, which can heal cracks into it.
Another object of the invention to provide a novel welding technique for bells, which uses leaded phosphorous bronze alloy casting with 5% Pb and 15% Sn and brass casting with 4.4% Pb.
Yet another object of the invention to provide a novel welding technique for bells, which uses filler wire to carry out weld with OFW process (please provide the full form) depending on the chemistry of the bells.
Further object of the invention to provide a novel welding technique for bells, which simple yet effective.
Another object of the invention to provide a novel welding technique for bells, which is environment friendly.
Yet another object of the invention to provide a novel welding technique for bells, where the inter pass temperature is maintained during welding by gas cutting torches and manipulating the movement of flame to lay the bead differently in a fashion to obtain less entrapment in the weld metal.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
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. Some embodiments of system or methods 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:

Fig. 1 illustrates the Bronze Bell, which has developed due to prolong hitting of clapper to the bells inside surface. ‘a’ in figure 1, indicates the grounded crack. ‘b‘ in figure 1, indicates backing plate to support the liquid weld during welding.
Figure 2 illustrates the restored and repaired Bronze Bell, ‘c’ in figure 2, indicates the repaired bell, ‘d’ in figure 2, indicates clapper used to hit the bell and a rope is tied to the clapper.
Figure 3 illustrates the Brass Bell. The figure clearly describes the crack orientation and geometry.
Figure 4 illustrates the repaired and restored Brass Bell.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
The present subject matter relates to a welding technique of cracked bells through a leaded phosphorous bronze and brass castings.
The bronze casting consists of 15% Sn and 5% Pb whereas the brass casting consists of 4% Pb and 3.6%Tin.
The method comprises the steps of
i) holding the bell in fixture depending upon the geometry of the casting;
ii) preheating the bells by keeping it in the furnace at certain temperature for a suitable soaking time along with filler wire depending on the chemistry of the bells;
iii) after preheating, the bell is taken out in the grove volume and subjected to heating with gas torches while maintaining the inter pass temperature and the grove is filled completely with stirring the weld puddle;
iv) covering of the bells casting immediately after the welding with insulating cloths like glass wool and subjected to post weld heat treatment (PWHT) at an appropriate temperature;
v) after post weld heat treatment (PWHT), the extra weld metal is grounded and the bell is brought back to shape and subjected to some

checking for weld integrity and sound quality by x-ray inspection and hitting with clapper.
Once the right weld integrity is achieved by verifying with x-ray examination, the original sound and vibration of the bell can be achieved.
The temperature used for preheating is 250°C, whereas the inter pass temperature is 350°C to 400°C
Th temperature requirement for post weld heat treatment (PWHT) is 260° to 600°C for 1 hour.
Fig 2 and 4 indicate the restored and repaired bronze bell and brass bell respectively.
The bell is tested for its sound in front of the temple authority/people from temple council of the respective villages where the Bell belongs. The repaired bell is cleaned with brass powder to get back its shining lusture. The quality of finished and polishing is such that there is no contrast between welded metal and parent metal. The repaired/restored bell can be seen is figure 2 and figure 4. The bell is then handed over to the temple council. The bell then is again mounted in the temple after its (Kumbhabhishekam) puja in the village. The clapper is attached/linked to the rope to make it approachable to the devotees. The rope is pulled to hit the clapper to the bell’s inside surface to produce vibrations and sound, to serve the purpose henceforth.
EXAMPLE:
The LPI (Liquid Penetrant Inspection) is carried out for the cracked bells to detect surface defect/discontinuities. LPI is carried out as per the procedure in non-destructive standards available widely. The LPI results of bells/castings are noted/observed carefully and indication of crack/defects were marked, here the bell discussed have these physical parameters, the bronze bell is 200kg, H= 60 cm, OD at bottom=45 cm and maximum thickness of 4 cm varying throughout the height and the brass bell has physical parameters of 300kg, H=

90 cm OD at bottom=75 cm and maximum thickness of 6.5 cm. The Bells being vintage 100-200 years old, make the restoration very challenging, as there is no literature available which could be of any help by welding for these old era materials.
In accordance with the embodiment of the present invention, the filler wire is chosen corresponding to the chemistry of the two Bells to carry out weld with OFW process. Copper being very good thermal conductor acts as heat sink when heated. Here higher thickness and larger size of the bell makes copper alloy more effective heat sink.
Following the above steps any casting of this chemical composition can be welded successfully. This method can be used to repair weld temple bells and automobile components of this chemistry type.



Further, before proceeding with repair welding, the crack in bell body are identified by NDT techniques. The crack are removed by grinding and groove are formed on the bell surface. The grooves are backed with backing plates and the bell is supported with fixtures (fixtures are not discussed in this patent). Following some set of parameters (mentioned in the Table 5.0) and selecting the right filler wires, the leaded materials of the Bell can be successfully welded by Oxy fuel welding process.
Non-limiting advantages of the invention:
1. Set of parameters which when followed strictly can only successfully weld a leaded phosphor bronze casting with 5% Pb and 15% Sn and brass casting with 4%Pb and 3.6% Sn. The parameters for this composition of bells are mentioned above in table 3.0.

2. Local heating and shining during welding is to be carried out to achieve good weld integrity and hence better sound quality of the bell / casting.
3. The leaded phosphor bronze and brass casting alloy having (5% lead, 15 % tin) and (4%Lead, 3.6%Tin), can be welded successfully with OFW process.
4. The preheat and inter pass ranges from 250 to 350 degree centigrade are used during welding.
5. PWHT as in table 5.0 above (maximum casting thickness nearly 6.6 cm with this lead and tin content typically) carried out.
6. Weldments declared crack free (successful fusion), but few entrapped pores were indicated in radiography examination which is attributed to the nature of Oxy-fuel welding.
7. V Groove preparation and joint fit up as per the chemistry and weldability is designed successfully.
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 are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the method 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.

WE CLAIM:
1. A welding method of bell comprises the steps of:
i) holding the bell in fixture depending upon the geometry of the casting;
ii) preheating the bells by keeping it in the furnace at certain temperature for a suitable soaking time along with filler wire depending on the chemistry of the bells;
iii) after preheating, the bell is taken out in the grove volume and subjected to heating with gas torches while maintaining the inter pass temperature and the grove is filled completely with stirring the weld puddle;
iv) covering of the bells casting immediately after the welding with insulating cloths like glass wool and subjected to post weld heat treatment (PWHT) at an appropriate temperature;
v) after post weld heat treatment (PWHT), the extra weld metal is grounded and the bell is brought back to shape and subjected to some checking for weld integrity and sound quality by x-ray inspection and hitting with clapper.
2. The method as claimed in claim 1, wherein the bell casting is possible with
bronze casting with 5% Pb and 15% Sn and brass casting with 4% Pb and 3.6%
Sn.
3. The method as claimed in claim 1, wherein the temperature of said preheating maintained at 250°C to 275°C
4. The method as claimed in claim 1, wherein the inter pass temperature is 350°C to 400°C
5. The method as claimed in claim 1, wherein the post weld heat treatment occurs at a temperature range from 260°C to 600°C for a duration of 1 hour.

6. The method as claimed in claim 1, wherein the maximum thickness of the casting is 6.6 cm.