Forum Replies Created
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Chetankumar MohaneMember
@I n I : Its my Pleasure…
Dec 02, 2011 at 7:36 am
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Chetankumar MohaneMember
@Dinesh: Ok I wants to say that I am not too good in this Forming section but still I will try to solve this; Lets see how much can I help you !!!
Say, Original c/s Area = O.A.
Final c/s Area = F.A.
Area After First Die = A1
Original Length = O.L.
Final Length = F.L.
Now O.A. = (pi/4)*(10^2) = 78.5398 mm2
A1 = (1-0.35)*(O.A.) = 0.65*(O.A.) = 51.0508 mm2
Similarly for the area after 7th die
= 0.65*0.65*0.65*0.65*0.65*0.65*0.65*(O.A.) … .. (For 7 dies)
= (0.65)^7 * (O.A.)
= 3.8502 mm2 = F.A.
Now, as True strain is instantaneous % of change in length of specimen & it is given by,
True strain (TS) = Natural log of (O.A./F.A.)
= ln (78.5398/3.8502)
= 3.0155 ———————————–ANS
Final length can be calculated by using constant volume principle as,
Initial Volume = Final Volume
(O.A.)*(O.L.) = (F.A.)*(F.L.)
78.5398 * 100 = 3.8502 * F.L.
F.L. = 2039.8888
= 2040 mm ————————————-ANS
Now, For force we have to calculate a Draw Stress after first die,
using uniform energy deformation method,
Draw Stress (D.S.) = Y * ln(O.A./A1) …… … (Y = Yield Strength)
(Note this formula can be used for only Ideal Conditions i.e. neglecting friction and redundant work)
Hence, D.S. = 200 * ln (78.5398/51.0508)
= 86.1568 N/mm2
Now, Drawing Force through first die is,
Drawing Force (F) = (D.S.)*(A1)
= 86.1568 * 51.0508
= 4398.3735 N
= 4.4 kN ———————————ANSNote: Please check the answers & do notify in reply. If possible then mention the answers (options) along with the questions.
Dec 02, 2011 at 7:32 am
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Chetankumar MohaneMember
Check out the NPTEL video lectures on Thermal Engineering by PK Das. The video lectures are really very good giving out basic knowledge of Thermal Engg.
Here are the links:
Lecture 1 : Introduction & Definition
Lecture 2 : First Law of Thermodynamics (Open System)
Lecture 3 : First Law of Thermodynamics (Closed System)
Lecture 4 : Second Law of Thermodynamics
Lecture 5 : Second Law & carnot Principle
Lecture 6 : Properties of Pure Substances
(Guys do use InI community regularly)
Nov 29, 2011 at 1:57 pm
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Chetankumar MohaneMember
first of all sorry for such long delay 🙁
Anyway I think the data given is incomplete in this question that’s why now I am giving u only formulas:
a) For Latent heat calculate “B” from the formula as:
t = B * [(Casting modulus)^n]
where,
t = Solidification Time (given)
B = Mold Constant
n = 1.5 to 2 (Take 2 if not given)
Then after finding “B” calculate Latent heat as:B = {[(ρm*L)/(Tm-T0)]^2}*{[3.1428/(4*K*ρ*C)]}*{1+[(Cm*ΔTs)/L]}
Where,
Tm = melting or freezing temperature of the liquid
To = initial temperature of the mold
ΔTs = Tpour − Tm = superheat
L = latent heat of fusion
K = thermal conductivity of the mold
ρ = density of the mold
C = specific heat of the mold
ρm = density of the metal
Cm = specific heat of the metalb) For Fluidity of Short Freezing Range Alloys the formula is,
Fluidity Distance, Lf = V * twhere,
V = flow velocity
t = solidification timeIf the data is not given in the problem then take any appropriate material & take respective data & put it in formula… 🙂
Well I don’t think this kind of question can be asked in GATE; if asked then it should be deserve 10 marks lol …
Hope this could satisfied you a bit…. … .. .Nov 21, 2011 at 4:51 pm
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Chetankumar MohaneMember
yes u can focus on your strong subjects but beware u should be 100% prepared on what u wants to study by the time of exam !!! U have a time now but don’t waste ur time much on deciding the subjects !!!!
It is good enough to prepare 60 to 80% of the whole syllabus…Nov 03, 2011 at 2:42 pm
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Chetankumar MohaneMember
if u don’t have some books as mentioned in “inspirenignite – link” then u can try these ones (some of the books are same)
1. Engg. Thermodynamics – P.K. Nag
2. I.C. Engine – M.L. Mathur, RP Sharma
3. Gas Turbine and Propulsive Systems – P.R. Khajuria & S.P. Dubey
4. Fluid Mechanics – Modi & Seth, R.K Bansal
5. Compressible Flow – S.M. Yahya
6. Heat and Mass Transfer – JP Hollman, R.C. Sachdeva
7. Refrigeration and Air Conditioning – CP Arora, Domkundwar
8. Fluid Machinery – Jagdish Lal , RK Bansal
9. Theory of Machines – RS Khurmi, Malik & Ghosh
10. Mechanical Vibration – Grover
11. Machine Design – Shigley, VB Bhandari
12. Material Science – WD Callister, IP Singh
13. Production Engg. – Kalpkjian Schmid, Amitabh Ghosh & AK Malik
14. Industrial Engg. – O P Khanna, Buffa & Sarin
15. Operations Research – Kanti Swarup
16. Strength of Materials – Timoshenko, B.C. Punamia, Rama MurthaNov 01, 2011 at 6:47 am
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Please suggest me books that contains problems on manufacturing processes like forming, forging, drawing, casting, punching etc. I have P N Rao’s book which elaborates very good theory but it does not have enough no of solved problems 🙁 Please suggest me any book name or if anybody has a soft-copy then give me link….