SINE BAR

                              SINE BAR 

Sine bar is a accurate instrument for measu-ring angle. Sine bar consist of a rectangular bar made of high quality steel and having steps at the end . A roller is fitted into each step which touch the roller. The Sine bar is specified by the distance between center of two rollers ,i.e. 100 mm , 200 mm , 250 mm and 300 mm . The roller must be of the same diameters. The roller are so fixed that when sine bar is placed on surface plates the sur-face of the bar is exactly parallel to surface plate. 

When component is small size-:

For checking the angle of a component of small size a sine bar is set-up at nominal angle on a surface plates by situable combi-nation of the slip gauge . The component to be checked is pressed over the surface of the sine bar. A dial gauge is carried with surface gauge is move along the upper surface of the component.

When component size is large-:

 The component is placed over a surface plate. The sine bar is placed over the com-ponent. The heights on the rollers are meas-ured by means of vernier height gauge. A dial gauge is used to check the measuring pressure. 

The angle can be found by this formula-:

SINE Ө = H / L

Where, H = Height made by slip gauge.

              L = Distance between roller.

DROP FORGING

 Drop forging-: In drop forging utilizes  a closed impression apply to obtain a desire shape of the component. The shaping is done by the repeated hammering given to the material in the die-cavity. The drop forging sis consist of two-half the lower half of the die is fixed to the anvil of the machine. While the uppr half is fixed to the ramp the heated stock is kept in the die while the ramp 4-5 blows in pick-succession so that a metal spread and completely fill the die-cavity. When the two die half closed the completely cavity form.

The barrier passes used are the following-:

1. Fullering impression 

2. Edging impression 

3. Bending impression 

4. Blocking impression

5. Finishing impression 

1. Fullering impression -: Since drop forging involves only a reduction in cross-section with no up-setting , the very first step is to reduce the stock to the desire size.

2. Edging impression -: This stage is required together the expect amount of material required at each cross-section of the finishing component.

3. Bending impression -: This is required for those parts which have a bend shape. 

4. Blocking impression-: It is very difficult for a material to flow to deep pockets,  Sharp corners etc. Hence before the actual shape obtained the material is allowed to have one or more blocking impressions. Where it requires the shape very near to the final shape.

5. Finishing impression -: This is a final impression there the actual shape required is obtained. 

Cooling tower MCQ -:02

 Q.1 Filling or decking in a cooling tower increases the rate of heat transfer by providing ____.

A. Increase flow of air

B. Increase flow of water

C. A large amount of wetted surface 

D. All of the above 

Ans -: C

Q.2 Which type of fan drive generally cooling towers employ ?

A. Two speed fan drive

B. Multi speed fan drive 

C. Single speed fan drive 

D. Variable speed fan drive 

And-: A

Q.3 The minimum temperature to which water can be cooled in a cooling tower is __.

A. The wet bulb temperature of air

B. The dew point temperature of air 

C. Room temperature 

D. Dry bulb temperature of air

And-: B

Q.4 The performance of an evaporator condenser largely depends on ____.

A. Wet bulb temperature 

B. Dew point temperature 

C. Room temperature 

D. Dry bulb temperature 

Ans-: D

Q.5 In which type of refrigeration system solar energy can be directly used?

A. Vapour absorption 

B. Air refrigeration system 

C. Vapour compression 

D. All of the the above 

Ans -: A

Q.6 What is the means of amount of heat thrown away by the cooling tower in kcal/hr ?

A. Heat load of cooling towers 

B. Drift of cooling towers 

C. Approach of cooling towers 

D. None of the above 

Ans -: A

Q.7 What is mean of cooling range in cooling tower?

A. Amount of heat thrown away by the cooling tower in kcal/hr

B. Difference in temperature of cold water and atmospheric temperature 

C. Difference in temperature of hot water entering and cold water leaving. 

D. None of these

Ans-: C

Q.8 The most commonly used design method for duct size is ?

A. Equal friction method

B. Velocity reduction method

C. Double duct method

D. Static regain method

Ans-: B

Q.9 The process of mixing two or more streams of moist air is called ___.

A. Isothermal 

B. Constant volume 

C. Constant pressure 

D. Adiabatic 

Ans-: D

Q.10 Which type of refrigerating plants not require electricity?

A. Vapour absorption 

B. Vortex tube

C. Air refrigeration 

D. All of the above 

Ans -: A

ROLLING PROCESS

 Rolling process-: The rolling process is a metal forming process in which stock of the material pair of rollers   is passed between one or more pairs of rollers in order to reduce and to maintain the uniform thickness. In other words, it is a process In metal passing through a gap between the rollers rotating in opposite direction. This process is mainly focused on the cross-section of the it not or the metal which is forming.  

 

There are two types of rolling process -:

1. Hot rolling

2. Cold rolling

1. Hot rolling -: Those process working above the recrytalization temperature are termed  as " hot rolling " process.

2. Cold rolling -: Those process working below the recrytalization temperature are termed as cold rolling process. 

Under the action of heat or force when the atom is which a certain higher energy level the new crystal starts forming which is termed as recrytalization. Recrytalization destroy the old grain structure deforming by mechanical working and antaily new crystal which are strain free are formed. In hot working the process may be carried about of the recrytalization temperature with or without actual heating. 

For example-: The recrytalization temperature is below the room temperature and hence working of this metal at room temperature is always hot working. A simple heating is shown in fig. Where the grain start growing after the metal process the recrytalization temperature.  When it is cooled without any hot working the final grain size would be larger then when starts in hot working process.

MACHINE FORGING PROCESS

 Machine forging -: This is also known as up-set forging. Both drop and press forging are also done by machines only up-set forging is reffered as machine forging. Up-set machines are generally horizontal acting. The die-set consist of a die and a corresponding punch. The die consist of two parts one called the stationary greeper die which is fixed to the machine frame and other part is moveable greeper die which moves along with the die slide of the up-setter. The stock help between two greeper die by frition. 

                The two dies when in close position forward the necessary die cavity then the having tool advances against the stock and up-set it to completely fill the die cavity. Having completed the upsetting the heading tools moves back to it's back position. Then the moveable greeper die release the stock by sliding member.

Advantages of machine forging -:

1. High production rate up to 4500 parts per hour.

2. The process can be fully automated.

3. Elimination of the forging draft and flash.

4. High efficiency of material utilization, as the process involves little or no waste

PRESS FORGING

 PRESS FORGING -: In press  forging process die is similar to drop forging die as also the process. In this forging process the metal is shape not by means of a series of load as in drop forging. But by means of a single continuous squeezing action. This squeezing is obtained by means of hydraulic presses. Because of the continuous action of the hydraulic presses the material gets uniformly deformed throughout it's intire gap. More hammer is likely to be transmitted to the machine from in drop forging.

The pressure may have capacites ranging from 5 MN to 50 MN for normal applications. For special applications higher capacities press of the order of 150 MN are required. 

WELDING MCQ-:01

 Q. 1 The point at which the two pieces to be joint known as _____ .

A. Root

B. Weld point

C. Joint

D. Base point

And-: A

Q.2  The portion of the bent joint i.e. melted by the heat of welding is called  ___.

A. Puddle 

B. Melting point

C. Weld point

D. None of the above 

Ans -: A

Q.3 Acetylene also known as _____.

A. C3H4

B. C3H8

C. C2H2

D. C3H3

Ans-: C

Q.4 What is the proportion of the oxygen and acetylene in the natural flame?

A. 1:2

B. Equal 

C. 2:5

D. 1:3

Ans-: B

Q.5 In carburating flame the proportion of oxygen is ____%.

A. 22

B. 35

C. 50

D. 25

Ans-: D

Q.6 In welding process ,the colour of oxygen cylinder is ____.

A.  Black

B. White

C. Green

D. Yellow

And-: A

Q.7 In which type of welding process, the welding torch should be held at an angle of 30 to 40 ° .

A. Forehand welding

B. Backhand welding 

C. Electric arc welding 

D. All of the above 

Ans -: A

Q. 8 Electrods are two types ___.

A. Non-comsumerabl 

B. Non- corrosive 

C. Comsumerabl 

D. A+C

Ans -: D

Q.9 Non-comsumerabl electrod are made up of ___.

A. Copper

B. Carbon

C. Graphide 

D. Tungsten 

E. All of the above 

Ans-: E

Q.10 Which type of electrod is used in the " metal inert gas welding " process?

A. Comsumerabl 

B. Non-comsumerabl 

C. Aluminium electrod 

D. None of the above 

Ans-: A