Welding

Welding is basically the process of joining same or different materials , not just metals . The Basic Idea is to use a Heat source in order to melt the two joining faces and place them together , and as the materials cools down they form a single piece.One of the most earliest and the most commonly used Welding technique is the Arc Welding . The electric arc was first described by Davy in England , in the year 1809, but the arc welding could only be possible with some improvements in the electric dynamos or generators between 1877 and 1880 . Arc welding is a group of welding where coalescence is produced by heating with an electric arc , with or without the use of a filler metal  . Pressure is usually not applied in these cases . The Basic Parts of an Arc Welding Equipment would be an electrode connected to the -ve terminal of the power supply and the work piece which is connected to the +ve . The Arc is struck by touch

-ing the  electrode with the job momentarily and then taking way the the electrode a definite distance apart( approx. 15 mm) . The arc is allowed to impinge in the surface to be welded until a molten pool is formed and then the electrode is steadily moved along the joint in definite predefined patterns.
 In Most of the cases a filler material is used to weld the two materials .It forms an integral part of the electrode . Thus filler metals comes in forms of sticks which when gets used have to be replaced with new ones .This filler material also melts and as in it melts in it takes up the gap between the two pieces to be joined. Fluxes are the next important thing in the welding process. The metals or materials being welded can contain impurities. Upon melting they tend to move in to the molten puddle . The Flux prevent this from happening and forms slag which floats at the top of the molten puddle , which have to be scrapped off later after cooling. When at high temperature and molten state the metals tends to react with various gases present in the surrounding air . Thus another function of the Flux being used is to form a protective covering for the molten puddle of metals.Fluxes can be either directly applied to the weld surface before the process or it comes as another layer over the filler metal electrode , which would melt as the electrode gets used up .

As the technology has developed over the period of time more and more kind of welding techniques have been invented . Today Welding Technology can be divided into six main kinds:
1. Arc Welding
2.Gas Welding
3.Resistance Welding
4.Solid State Welding
5.Thermo-Chemical Welding
6.Radiant Energy Welding

The above described is the basic and thus one of the most crude from of welding which comes under the classification of Arc Welding.  In the article to come we'll discuss more about the different types of welding and the latest innovations in the fields of welding and few exciting careers it can provide.

Vapour Absorption Refrigeration

 Even though confusing by its name an Absorption Refrigerator is one which uses a heat source to drive its cooling unit.. sounds crazy enh?,.. a refigerator tht uses heat to cool things .. well thts the way it works...

  One of the most commonly use Absorption Refrigeration system is the one usein Ammonia , water and Hydrogen mixture.......   at normal atmospheric pressure ammonia is a gas  which liquidifies at a temp of -33°C... in this system ammonia is pressurized to its liquid form an is mixed with water and a very small amount of Hydrogen... Ammonia acts as REFRIGERANT and Hydrogen being light in weight act as TRANSPORTING agent which takes up the vapour .

The mixture will be present in the bottom most chamber. the external heat source liberates ammonia from the solution and an hydrogen takes this vapours of ammonia up to the condenser , where ammonia condenses into liquid form( Condeser is the FINNED part tht we ususally get to see behind the refrigerators) . This liquid  ammonia now enters the evaporating chamber ( in form of Pipes lining the area to be cooled). there the heat from the freezer is absorbed by the ammonia to evaporate in to gaseous form, thus cooling our required area. this vapour along with the hydrogen enters the bottom tank again, where it is mixed with water again to form strong solution and the Cycle goes on .

  This kind of refrigeration systems are usually used where electricity is not continuously available. A a solar heat absorbing device can be coupled to this system as a heat source, which would be very efficient . ONE such system was made by me and my friends for our final semester projects ( B.TechMechanical).

Escalator

  Escalator is a device , a moving staircase used to transport normally people from one floor of building to another. Most us would have definitly used a elevator at some point of time ...Might be at airport, metro station or at a shopping mall... Though it reduces our effort to get up there , have u ever wondered how doe sit work..... Escalators are nothin much but an advanced for of a conveyor belt....

 

                                                                                                                                     

Taking a look at the parts and working of an elevator:

1. Landing platforms
2. Truss 
3. Tracks
4. Steps
5. Handrails

        The Landing Platforms house the the gear systems, motor drive , idler sprocket(  free rotating gear acting as support) ,the curved section of the track etc.. It has pltes that merges with the floor , that helps the passengers to stand before stepping foot on the steps.. in the recent models , these plates have sensors which automatically switched ON & OFF the escalator according to the presence of a user . this system usually works on weight sensing switches which operates with weight of the passenger standing on these plates ..

     The Truss is the frame work provided at the sides of the escaltor which bridges between the upper nd the lower landing gears. It imparts strength to the whole sturcture, usully made of steel. it will have aluminum sheet covering on the outer sides.

   The track system is usually built between  the truss to guide the step chain.It continuously pulls the steps from the bottom platform and back to the top in an endless loop.

   Step are usually made by the process of die casting of aluminium or steel.They are joined end to end using hinges which allow them to form a loop , like a chain.. the track systems are attached to step chain as well.. the rotating power drive motor moves the track system which in turn moves the the step chain....

   

The Handrail is also a vital part of the escalator system which provides suppport to the passengers. this is also a loop of flexible strong fibre like material which moves wid the  same speed as that of the escaltor 

  Even though many claim patents on various escalators designs being used today , Nathan Ames is considered to be the inventor of this wonderful machine.....

                                                                                    

                                           COURTESY: WIKIPEDIA

Where it all started....

Today , the engineering world is very vast . And it might take years for one to explore , understand and accept the things that he might discover out there. As this is Mechanical Engineering Blog, I thought the first post should be on where it all started. What would have been the first MACHINE that Mankind discovered.?.... well no one knoes the exact answers but we have evidences n theories n hypothesis n lots more.... Before answering that we must understand " what is or can be called a machine?"...

Any thin that reduces human effort is machine.. i would say an automobile , a boiler or even a ceiling fan would a complex example.... looking simpler examples , we can say that spoon is machine... two pieces of stone if rubbed together can produce a spark, is a machine.... list goes on ...

In this blog , being a mechanical engineer, I will try to bring in front of u what ever mechanical i can find..... discoveries..... inventions... facts.. theories... troubles and also their shootings.... I would humbly request my readers to come forward n post ur comments n suggesions... for am just trying to discover a new hobby .....

So together , lets blog.... LETS MECHBLOG......