thermal resistance

Observations indicate that in system involving flow of fluid , heat & electercity, the flow quantity is directly proportional to the driving potential & inversaly proportional to the flow resistance. In a hydroullic circuit , the preassure along the path is the driving potential & the voltage potential & electric resistance of the materia. Likewise, temprature diffrence constitutes the driving force for heat conduction through a medium. From ohm's law:- Current(i)= voltage potentia(dV)/electrical resistance(Re) & from fourier's law:- Heat flow rate =temprature potential/thermal resistance Q=dt/(dx/kA) Note:- »Electric current is analogous to thermal heat flow rate (kj/hr.) »volts corresponds to thermal temprature diffrence(°k) »electric resistance(ohms) is analogus to quantity dx/kA this quantity calledTHERMAL RESISTANCE.

grinding valve seats

The valve seat grinder rotates a grinding stone of copper shape an valve seat. A pilot installed in the valve seat . This permits the stone to clear itself of grit & dust by centrifugal force . A steel scale can be used to measure measure seat width. When a new valve is installed it may too high above the seat . Then grind the seat slightly with a stone of the same seat angle

software used by mechanical engineer

Well, im still persuing my degree but ive learnt learnt, solidworks, autocad ,ms office ,ms word, inspite of this c++ software with those im preety fimiliar are ,first of all" auto cad" in my concern its the basic software of creating 2D & 3d image of an objects in our computer. if you have leaened autocad then you can learn solidworks & CATIA. There are lots of other software like pro-E, matlab, ansys , If you want to learn these by yourself so you can learn about these on youtube.

checking of leakage of valves

1. Check valve guides for wear, clean replace & ream for same size valve steam if necessary. 2. Check valves & valve seats. Clean valve heads & steam an a wire wheel. 3. Refinish valve seats. 4. Check rocker arms for wear. Service or replace as necessary. 5. Replace valves & springs in head. 6. Check & adjust valve clearence as necessary

replacing valve seat inserts

A valve seat insert may be badly worn or it may be refinished previously so that there is insufficient metal with either condition, the seat must be replace the old seat removed with a speacilal . An electric drill is then use to drill holes almost through the insert . Then an over size insert installed . It may be necessarly to chill the seat & heat the head before the seat is driven into place. After instalation the valve seat should be ground

valve seat grinding

For effective valve seating & sealinf , the valve face is must be concentric with the valve stem . The valve seats are of two types , 1. The integral type. 2. The insert type.

valve refacing

If the valves are good enough to reuse them. This requires a valve refacing machine. The valve refacer has a grinding wheel coolant delivery system & a chuck which holds the valve for grinding set the chuck to grind the valve face at specific angle to start the operation , align the coolant feed so that it sprays coolant on the rotating valve face. Do not take heavy cuts , if so much metal must be removed that margin is loss , discard the valve.