User talk:Sagar062

Introduction of Resistance welding - Resistance welding (RW), invented in 1886 by Professor Elihu Thomson, is conceptually one of the simplest and most commonplace of welding processes. When an electric current flows through a conductive material, such as a pure metal or alloy, there is some inherent resistance to the free flow of electrons through the conductor. Mathematically stated, the thermal power (dQ/dt) produced when current (I) flows through a conductor of resistance R is given by dQ/dt = I2R, where the unit of power is watts (or Joules/second). This production of thermal energy is formally known as Joule heating, or informally as I2R heating. The process is most commonly used to weld two overlapping sheets or plates… या प्रतिरोध (आरडब्ल्यू) वेल्डिंग, प्रोफेसर एलीहू थॉमसन द्वारा 1886 में आविष्कार, धारणा है, एक सरल और सबसे सामान्य वेल्डिंग प्रक्रियाओं की. एक प्रवाहकीय सामग्री के माध्यम से एक बिजली जब वर्तमान एक शुद्ध धातु या मिश्र धातु के रूप में बहती है, वहाँ कंडक्टर के माध्यम से इलेक्ट्रॉन के मुक्त प्रवाह के लिए कुछ निहित प्रतिरोध है. गणितीय ने कहा, थर्मल पावर (dQ / dt) का उत्पादन वर्तमान (आई) के प्रतिरोध आर के एक कंडक्टर के माध्यम से बहती dQ / dt = I2R, जहां शक्ति की इकाई वाट (या Joules / 2) द्वारा दिया जाता है. तापीय ऊर्जा के इस उत्पादन जौल हीटिंग, या अनौपचारिक रूप I2R हीटिंग के रूप में औपचारिक रूप से जाना जाता है.प्रक्रिया को सबसे अधिक दो अतिव्यापी चादरें या प्लेट वेल्ड करने के लिए प्रयोग किया जाता है ... Advantages of Resistance Welding: 1).High welding rates;   2).Low fumes; 3). Cost effectiveness;   4) .Easy automation; 5). No filler materials are required;   6).Low distortions. Disadvantages of Resistance Welding: 1).High equipment cost; 2).Low strength of discontinuous welds; 3).Thickness of welded sheets is limited - up to 1/4” (6 mm);

Type of Resistance welding 1).Spot welding;- In resistance spot welding, two or more sheets of metal are held between electrodes through which welding current is supplied for a definite time and also force is exerted on work pieces. The principle is illu-strated in Figure 11.2.

Fig 11.2: Principle of Resistance spot Welding The welding cycle starts with the upper electrode moving and contacting the work pieces resting on lower elec-trode which is stationary. The work pieces are held under pressure and only then heavy current is passed between the electrodes for preset time. The area of metals in contact shall be rapidly raised to welding temperature, due to the flow of current through the contacting surfaces of work pieces. The pressure between electrodes, squeezes the hot metal together thus completing the weld. The weld nugget formed is allowed to cool under pressure and then pressure is released. This total cycle is known as resistance spot welding cycle and illustrated in Figure 11.3

Fig 11.3: Resistance Spot Welding Cycle Spot welding electrodes of different shapes are used. Pointed tip or truncated cones with an angle of 120° - 140° are used for ferrous metal but with continuous use they may wear at the tip. Domed electrodes are capable of withstanding heavier loads and severe heating without damage and are normally useful for welding of nonferrous metals. The radius of dome generally varies from 50-100 mm. A flat tip electrode is used where minimum indentation or invisible welds are desired. Fig 11.4: Electrode Shapes for Spot Welding Most of the industrial metal can be welded by spot welding, however, it is applicable only for limited thickness of components. Ease of mechanism, high speed of operation and dissimilar metal combination welding, has made is widely applicable and acceptable process. It is widely being used in electronic, electrical, aircraft, automobile and home appliances industries.

2).Projection welding:- Projections are little projected raised points which offer resistance during pas-sage of current and thus generating heat at those points. These projections collapse under heated conditions and pressure leading to the welding of two parts on cooling. The operation is performed on a press welding machine and components are put between water cooled copper platens under pressure. Figures 11.8 and 11.9 illustrate the principle of resistance projection weldi

Fig 11.8: Resistance Projection Welding Machine These projections can be generated by press working or machining on one part or by putting some external member between two parts. Members such as wire, wire ring, washer or nut can be put between two parts to generate natural projection. Insert electrodes are used on copper platen so that with continuous use only insert electrodes are damaged and copper platen is safe. Relatively cheaper electrode inserts can be easily replaced whenever these are damaged..

Fig 11.9: Formation of Welds from Projections on Components Projection welding may be carried out with one projection or more than one projections simultaneously. No consumables are required in projection welding. It is widely being used for fastening attachments like brackets and nuts etc to sheet metal which may be required in electronic, electrical and domestic equipment. 3).Seam Welding:- In seam welding overlapping sheets are gripped between two wheels or roller disc electrodes and current is passed to obtain either the continuous seam i.e. overlapping weld nuggets or intermittent seam i.e. weld nuggets are equally spaced. Welding current may be continuous or in pulses. The process of welding is illustrated in Figure 11.5                                                      Fig 11.6: Type of Seam Welds

Seam Welding is high speed and clean process, which is used when continuous tight weld is required    (fuel tanks, drums, domestic radiators). 4).Butt Welding:- Resistance Butt Welding is a Resistance Welding (RW) process, in which ends of wires or rods are held under a pressure and heated by an electric current passing through the contact area and producing a weld.

The process is similar to Flash Welding, however in Butt Welding pressure and electric current are applied simultaneously in contrast to Flash Welding where electric current is followed by forging pressure application.

Butt welding is used for welding small parts. The process is highly productive and clean. In contrast to Flash Welding, Butt Welding provides joining with no loss of the welded materials...

November 2012
Hello, and welcome to Wikipedia. This is a message letting you know that one of your recent edits has been undone by an automated computer program called ClueBot NG.


 * ClueBot NG makes very few mistakes, but it does happen. If you believe the change you made was constructive, please read about it, [ report it here], remove this message from your talk page, and then make the edit again.
 * For help, take a look at the introduction.
 * The following is the log entry regarding this message: Article (grammar) was changed by Sagar062 (u) (t) ANN scored at 0.932592 on 2012-11-01T03:22:59+00:00 . Thank you. ClueBot NG (talk) 03:23, 1 November 2012 (UTC)

Please refrain from making unconstructive edits to Wikipedia, as you did at Article (grammar) with this edit. Your edits appear to constitute vandalism and have been reverted or removed. If you would like to experiment, please use the sandbox. Thank you. Lugia2453 (talk) 03:23, 1 November 2012 (UTC)

Please stop your disruptive editing. If you continue to blank out or remove portions of page content, templates or other materials from Wikipedia, as you did to Article (grammar) with this edit, you may be blocked from editing. Lugia2453 (talk) 03:25, 1 November 2012 (UTC)

This is your last warning; the next time you disrupt Wikipedia, as you did at Article with this edit, you may be blocked from editing without further notice. Lugia2453 (talk) 03:28, 1 November 2012 (UTC)