5. , :
How are the workpieces melted in arc welding?
How is the arc created?
What is the transformer used for?
Why must the electrode be moved across the joint continuously? What will happen if the earth clamp is not securely attached?
a. For supplying the necessary current.
b. By an electric arc.
c. An arc will appear between the clamp and the workpiece.
d. By a powerful electric current.
e. Otherwise neither the electrode nor the workpiece will melt.
6. , :
1. In arc welding the work- a) by a flame, pieces are melted...
b) by an electric arc.
c) by gas.
2. In arc welding the arc is created by... a) a combustible gas.
b) fusion.
c) a powerful electric current.
3. If the earth clamp is not securely attached to a) between the electrode and the workpiece.
the workpiece, an arc will appear... b) between the transformer and the earth clamp.
c) between the clamp and the workpiece.
4. The electrode must be moved continuously, a) either the electrode or the workpiece will
otherwise... melt.
b) neither the electrode nor the workpiece will melt.
c) both the electrode and the workpiece will melt.
21
1. :
1. non-detachable joining a.
2. to replace b.
3. arc welding c.
4. laser welding d. ,
5. application e.
6. to weld f.
7. pulsed laser g. ()
8. joint h.
9. correspondingly i.
10. to permit j.
11. dissimilar .
12. plasma arc welding 1.
13. particularly m.
14. with the exception n.
2. :
process, metal, mechanical, type, laser, practical, form, industry, physical, plasma, steel, titanium, nickel, aluminium, structure, electronic, intensity.
3. :
LASER AND PLASMA WELDING
1. Welding is a process which provides a non-detachable joining of two like metal pieces by heating them till melting condition or fusion without or with mechanical pressure.
2. Laser welding is quickly becoming a practical welding process. In its present stage of development, the laser can form welds up to about 1/32 inch deep.
3. Pulsed lasers are often used in industry today. The laser's heat input is very small, so the heat-affected zone around a joint is correspondingly small.
The laser's high power intensity permits welds between dissimilar metals of widely varying physical properties.
4. Plasma arc welding is efficient for fusion welding stainless steels, titanium, nickel from 0.001 to 0.030 inch thick. The process is particularly well suited for repairing delicate parts, for joining thin structures, and for welding electronic components. With the exception of aluminium any metal or combination of metals can be welded with plasma arc process.
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1,3 4.
5. , :
1. What kind of joining does welding provide?
2. What type of welding can replace arc welding?
3. What is the advantage of laser welding?
4. What metals is plasma arc welding efficient for?
5. Where is the process of plasma arc welding used?
a. Laser welding.
b. A non-detachable joining.
c. For fusion welding stainless steel, titanium and nickel.
d. The laser's high power intensity permits welds between dissimilar metals of widely varying physical properties.
e. In repairing delicate parts, for joining thin structures and for welding electronic components.
6. , :
1. Welding is a process which provides...
a) a detachable joining of two unlike metal pieces by heating them till melting condition.
b) a detachable joining of two like metal pieces by heating them till melting condition.
c) a non-detachable joining of two like metal pieces by heating them till melting condition.
2. The laser's high power intensity permits welds...
a) between similar metals having the same physical properties.
b) between dissimilar metals of widely varying physical properties.
c) between dissimilar metals of similar physical properties.
3. The process of plasma arc welding is efficient for fusion welding....
a) aluminium.
b) combination of aluminium and nickel.
c) stainless steel, titanium, nickel.
4. Plasma arc welding is particularly suited for....
a) repairing aluminium parts.
b) repairing delicate parts.
c) repairing massive and thick parts.
METALS ()
according to ,
alloy
alloy steel
alloying element
aluminium
berillium
bismuth
braking
branches of industry
brittle
capacity
carbon
carbon steel
cast iron
coat
coating (film) ()
compression
comprise ,
consist (of) ()
content
copper
corrosion resistant barrier -
corrosive environment
current
ductility
effect
elastic ,
electrical conductivity
employ
ferrous metals
gold
hard(-ness) ()
heat conductivity
important ,
in addition to ,
in order to
include
increase
iron
load
lustre
machinability ()
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majority
malleability
meet up-to-date demands (requirements)
palladium
platinum
poor conductor
precious metals
prepare
property
protect
purpose
quantity
resist
resistance
resistance to wear
rocket engineering
rupture
rust
rust-resistant
same (the)
semimetal
silicon
silver
similar
soft(-ness) ()
solid state
stainless steel
strength
stress
substance
sulphur
tension
titanium
tough(-ness) ()
undergo
zinc
