Claims:WE CLAIM:
1. A fixture to automate the welding process of Hydro End Cover plate, the fixture comprising a face plate (1) to support work piece, in which the face plate is provided with a coupler (2) at center thereof so as to connect the face plate (1) to universal joint (3) thereunder, wherein said universal joint is connected to spline shaft (4) connecting spline shaft casing (5) with the universal joint, and wherein the fixture is driven by means of a driving system.

2. The fixture to automate the welding process of Hydro End Cover plate as claimed in claim 1, wherein the coupler has atleast two set of fastener holes one to connect the coupler (2) to the face plate (1) and the other connects the coupler (2) to the universal joint (3), in which the universal joint transmits motion from the spline shaft (4) assembly to the face plate.

3. The fixture to automate the welding process of Hydro End Cover plate as claimed in claim 1 or 2, wherein the spline shaft casing (5) is supported by means of bearing housing (6) and drive shaft support plate (7) in which the bearing housing (6) and drive shaft support plate (7) are supported by supporting studs (8) and taper roller bearing (9).

4. The fixture to automate the welding process of Hydro End Cover plate as claimed in any of the preceding claims, wherein the driving system includes sprocket teeth wheels (20) that are connected by chain drive (19) and mounted on reduction worm gear box unit (16) placed on base plate (21) with the help of reduction gear box holder (14) and reduction gear box mounting bolt & nuts (15).

5. The fixture to automate the welding process of Hydro End Cover plate as claimed in any of the preceding claims, wherein the reduction worm gear box unit (16) is coupled to A C Motor (18) through double end bored hub universal Joint (17).

6. The fixture to automate the welding process of Hydro End Cover plate as claimed in any of the preceding claims, wherein the face plate (1) is supported by a plurality of supporting pillars (10) through ball transfer unit (13) accommodated in groove (23) of said face plate.

7. The fixture to automate the welding process of Hydro End Cover plate as claimed in any of the preceding claims, wherein said pillars (10) are mounted on the base plate (21) supporting pillars mounting fasteners (11).

8. The fixture to automate the welding process of Hydro End Cover plate as claimed in claim 7, wherein the pillars (10), one of which is provided with height adjustment nut (12) to provide inclination to the face plate (1) facilitating removal of slag.

9. The fixture to automate the welding process of Hydro End Cover plate as claimed in any of the preceding claims, wherein the base plate (21) is located on supporting stand (22).

10. The fixture to automate the welding process of Hydro End Cover plate as claimed in any of the preceding claims, wherein the pipes with variable diameter can be mounted on face plate (1) by work piece adjusting screws (25) and can be clamped with the help of work Piece mounting clamp (24) and can be supported by work piece supporting clamp (26), in which the work piece mounting clamp (24) is secured firmly on the face plate (1) by means of work piece mounting fasteners (27).
, Description:A fixture to automate the welding process of Hydro End Cover plate
FIELD OF INVENTION
[001] The invention relates to a fixture to automate the welding process of Hydro End Cover plate. This avoids manual welding and reduces time for the welding. The process of welding the Hydro End Cover plate which was being carried out manually encountered so many difficulties. In the present invention, Design and Development of fixture for carrying out the welding almost eradicated /minimized the difficulties encountered in the past.

[002] Thus, the present invention introduces Semi Automation of Hydro End Cover Plate with pipe Welding in Submerged Arc Welding (SAW) Machine in which the Welding fixture is designed to avoid manual welding by SMAW and to reduce the time consumed for completion of the welding.

BACKGROUND OF THE INVENTION

[003] Boiler constitutes a steam generator which is used to generate steam by applying heat energy to water. A typical 600 MW boiler weighs around 14000 Tons in which Pressure parts weight is around 6000 Tons. The product Lines & Links (Pressure parts) contribute to 1850 Tons in a boiler. The working temperature & pressure of the product Lines & Links is 566.8 degree centigrade (max.) & 281.2 kg/sq.cm (max.). The Lines & Links form the circulation system of a boiler (i.e. like arteries and veins in a human body). They are provided to connect different assemblies in a boiler and carry fuel/water/steam/ vapour /mixture of all the above across all systems. Hydro end cover plates are welded at the end of the circuits that act as either drain points or circuit closing points. Hydro End covers (Site Hydro Test Pipe) are fabricated with pipes of Outer Diameter (OD) 219, 273, 323, 368, 406, 457, 508, 558, 610, 660, 711, 762 mm with thickness ranging from 25 mm to 105 mm. The pipes are bored inside to seat the hydro end cover plate. These pipes are welded with hydro end cover of thickness ranging from 60 mm to 110 mm. The hydro end cover plates are welded inside the inner bored diameter of pipes. Fabricated Hydro End covers are welded at thermal power plant erection site at Circuit closing points, Circuit connecting with turbine, Circuit connecting with steam & water piping lines and at drain points.

[004] During hydro testing of the entire boiler structure, the scrap materials and the metallic wastes accumulated during the erection of boiler, are collected at the end points. Since the hydro test is carried out at 1.5 times of the boiler operating pressure, the metallic wastes hit the closing points and drain points violently with the huge force. In order to withstand such a high pressure and huge impact load (sudden loading), plates of higher thickness are welded inside the pipes.

[005] After hydro test, the collected metallic wastes are removed by cutting these plates and the circuits are connected to the respective water line and the turbine circuits.

[006] Presently the pipes of Hydro End covers are heated for about 15-20 minutes by LPG Burner to obtain pre-heat for the welding which is 200 deg. C. and the inter pass temperature during welding is 150 deg. C. Thereafter, the groove is welded by Shielded Metal Arc Welding (SMAW) – manual welding process. After welding, post heating is carried out at 200 deg. C for 2 hours. Continuous manual welding is not possible due to the heat experienced by the welder because of Pre heating. Hence welding is carried out intermittently. Due to the discontinuous welding, pre- heating is required every time for 15-20 minutes. Owing to the higher thickness of the plate and the pipe, it is very difficult to maintain the heat at the weld region. Hence the job and weldment cools faster because of which crack occurs in the weld.

[007] The difficulties encountered in Shielded Metal Arc Welding (SMAW) – manual welding process can be discussed hereinuder:

? Development of Weld Crack due to rapid cooling
? Slag inclusion and porosity occurs due to the narrow groove and manual welding.
? Continuous heating to the job leads to more LPG consumption.
? More electrode wastage since shorter length electrodes do not go deep into the groove (100 mm deep groove).
? More weld repairs due to manual welding and non-uniform heating.
? Removing the weld repairs (cracks) is laborious and unsafe.
? More fatigue to workmen due to exposure to high temperature, rework and incessant welding.
? Ununiform Surface finish of the final welding layer for Ultrasonic Testing (UT) requiring laborious grinding.
? Time consuming welding.

[008] The major shortcoming of this process is the formation of cracks in the weld, which is a result of a wide variety of factors like brief intervals between shifts and variance in temperatures over the brief duration of the welding process. The majority of the factors involved in the formation of cracks if analysed are workforce oriented and the major reason being attributed to fatigue as a result of prolonged weld duration. Hence the need was felt to develop an apparatus so as to complete the welding of Hydro End covers pipes with plate in automated mode in Submerged Arc Welding (SAW) Machine instead of the present manual Shielded Metal Arc Welding (SMAW) process to reduce time drastically.

OBJECTS OF THE INVENTION

[009] The object of the present invention is to provide a fixture to automate the welding process of Hydro End Cover plate which addresses issues of the prior arts.

[010] Another object of the present invention is to provide a fixture to automate the welding process of Hydro End Cover plate which holds the job in vertical axis and positions it to carry out the welding in submerged arc welding (SAW) machine.

[011] Still another object of the present invention is to provide a fixture to automate the welding process of Hydro End Cover plate having a rotating mechanism to rotate the job and the job holding unit.
[012] Yet another object of the present invention is to provide a fixture to automate the welding process of Hydro End Cover plate having a motor for speed transferring coupled with the speed governing mechanism.

[013] Further object of the present invention is to provide a fixture to automate the welding process of Hydro End Cover plate that facilitates removal of slag with a collecting unit to recycle the unused flux.

SUMMARY OF THE INVENTION

[014] It has been principally decided to utilize Submerged Arc Welding (SAW) machine in order to carry out the welding on the job instead of the present cumbersome manual welding process. Submerged Arc Welding (SAW) machine facilitates the holding of the job in horizontal axis only. Hence in order to hold the job in vertical axis, a face plate (1) is provided with concentric circles to support the job. Face plate coupler (2) joins face plate with universal joint (3). The universal joint is connected to spline shaft (4). The spline shaft is fitted with sprocket wheel to receive drive through Chain Drive (6). The sprocket wheel and chain arrangement gets drive from AC motor (8) through reduction gear box (7), which helps to regulate the rotational speed of the face plate which in turn rotates the Job.

[015] The A.C. motor transmits power to the reduction worm gearbox Unit. The AC Motor is used to power the system and the speed is regulated by the servo motor control system. The reduction worm gearbox Unit reduces the speed in the ratio of 60:1 and transfers the rotary motion to the sprocket teeth wheels of the chain drive. The chain drive connects the reduction worm gearbox Unit and the bearing housing. It also transfers power from the reduction worm gearbox Unit to bearing housing. The Spline Shaft is connected to the face plate via the universal joint which in turn rotates the face plate. The servo control unit regulates the speed with which the face plate rotates. The work piece centred and held on the face plate is prepared for welding. The Submerged Arc welding machine is set to the required parameters and the welding is carried out.

[016] Supporting pillars carry the load of the face plate and support it. They are mounted on the Base plate and two of the three pillars have fixed length and one of the pillars has variable length adjustment. This variable length of the pillar facilitates better area of contact during welding and provides easy slag removal. The ball transfer unit has a spherical roller that runs along the groove of the face plate and it transfers the load from the face plate to the supporting pillars. Taper roller bearings are used to position the spline shaft vertically and facilitates rotary motion of the shaft. Bearing Housing is used to support the top bearing and holds it to the Drive Shaft support plate assembly. This shaft supports the entire drive train assembly and is connected to the base plate by fasteners. Reduction gearbox holder holds the reduction worm gearbox unit to the base plate.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[017] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein:-

Fig. 1 shows: The isometric view of apparatus to carry out the welding of Hydro End covers pipes with plate in semi-automated mode in accordance with present invention.
Fig. 2 shows: The elevation of the isometric view in Figure 1 and sectional view thereof along A-A according to invention.
Fig. 3 shows: The Work Pieces (Hydro End Cover Plate, Plate) to be welded and placed in face plate in position and sectional view thereof along B-B in the present invention.
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED EMBODIMENTS

[018] The present invention makes a disclosure regarding an invention pertinent to a fixture to automate the welding process of Hydro End Cover plate.

[019] Now, reference may be made to fig. 1 illustrating the proposed apparatus. There is provision of a face plate (1) so as to support work piece, wherein the plate is preferably having a circular section made of cast Iron without restricting scope of the invention to the same. Thus, other profile and materials readily apparent to a person skilled in the art are understood to be within purview of invention.

1. The plate is provided with concentric circles to centre the work piece. Face plate coupler (2) is used to connect the face plate (1) to the universal joint (3). It has two set of fastener holes one to connect the coupler (2) to the face plate (1) and the other connects the coupler (2) to the universal joint (3). The universal joint transmits motion from the spline shaft (4) assembly to the face plate of the fixture. The spline shaft (4) is in connection with the universal joint (3) and also connects the spline shaft casing (5) with the universal joint (3). The spline shaft casing (5) is supported by bearing housing (6) and drive shaft support plate (7). The bearing housing (6) and drive shaft support plate (7) are supported by supporting studs (8) and taper roller bearing (9). This arrangement receives power via multiple sprocket teeth wheels (20). The fixture is driven by means of a driving system. Said driving system includes the sprocket teeth wheels (20) connected by chain drive (19) and mounted on reduction worm gear box unit (16). This reduction worm gear box unit (16) is mounted on base plate (21) with the help of reduction gear box holder (14) and reduction gear box mounting bolt & nuts (15). This reduction worm gear box unit (16) is coupled to A C Motor (18) through double end bored hub universal Joint (17).

[020] The face plate (1) has groove (23) for ball transfer unit (13). The face plate (1) is supported by multiple supporting pillars (10) through ball transfer unit (13), wherein the pillars (10) are mounted on base plate (21) supporting pillars mounting fasteners including bolt & nut (11). One of the supporting pillars (10) is provided with height adjustment nut (12) to provide slight inclination to the face plate (1). This inclination of the face plate (1) facilitates removal of slag. The base plate (21) is strengthened by fixture supporting stand (22) thereunder. Different diameter of the pipes (work Piece) can be mounted on face plate (1) by work piece adjusting screws (25) and can be clamped with the help of work Piece mounting clamp (24) and can be supported by work piece supporting clamp (26). The work piece mounting clamp (24) is secured firmly on the face plate (1) by means of work piece mounting bolt & nut (27).

[021] Operation of the automatic hydro end cover welding fixture involves the following steps:

[022] The A.C. motor (18) transmits power to the reduction worm gearbox Unit (16). Here, the AC Motor is used to power the system and the speed is regulated by the servo motor control system. The reduction worm gearbox Unit (16) reduces the speed in the ratio of 60:1 and transfers the rotary motion to the sprocket teeth wheels (20) of the chain drive (19). The chain drive (19) connects the reduction worm gearbox Unit (16) and the bearing housing (6). It also transfers power from the reduction worm gearbox Unit (16) to bearing housing (6). The Spline Shaft (4) is connected to the face plate (1) via the universal joint (3) which in turn rotates the face plate (1). The servo control unit regulates the speed with which the face plate (1) rotates. The work piece (29 & 30) centred and held on the face plate (1) is prepared for welding. The Submerged Arc welding machine is set to the required parameters and the welding is carried out. Supporting Pillars (10) carry the load of the face plate (1) and support it. They are mounted on the Base plate (21) and two of the three pillars (10) have fixed length and one of the pillars has variable length adjustment. This variable length of the pillar facilitates better area of contact during welding and provides easy slag removal. The ball transfer unit (13) has a spherical roller that runs along the groove (23) of the face plate (1) and transfers the load from the face plate (1) to the supporting pillars (10). Taper Roller Bearings (9) are employed to position the spline shaft (4) vertically and facilitates rotary motion of the shaft. The bearing Housing (6) is used to support the top bearing and holds it to the Drive
Shaft support plate (7) assembly. This shaft supports the entire drive train assembly and is connected to the base plate by fasteners. Reduction gearbox holder (14) holds the reduction worm gearbox unit (16) to the base plate.

[023] The semi-automatic conventional welding process is carried out instead of manual welding using the developed apparatus and thereby the drawbacks discussed under the background are obviated with substantial saving in manpower and cost.

[024] Welding by the developed apparatus in Submerged Arc Welding (SAW) machine instead of the present cumbersome manual welding process results in the following advantages:-

• No Welding Cracks
• Significant time reduction (from 8 Shift to Single shift) to complete the Job
• Reduction in LPG consumption from 579 Kg to 99 Kg for heating
• Reduction in Continuous heating to the job considerably
• Reduction in electrode wastage
• Elimination of welding consumable wastage.
• Removal of Slag inclusion and porosity which occurs due to the narrow groove and manual welding
• Drop in weld repairs due to manual welding and non-uniform heating
• Eradication of weld repairs (cracks) and rework
• Prevention of Health Hazard to employees like radiation exposure, fumes and particulate generation, thermal burns, occupational heat stress
• Considerable reduction in Fatigue to workmen due to high temperature, rework and continuous welding
• Reduction in number of activities
• Improved Surface finish.

[025] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.

[026] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-