Mitsubishi Evolution X. Manual — part 1
9-1
GROUP 9
BASE OF BODY
REPAIR
CONTENTS
GENERAL . . . . . . . . . . . . . . . . . . . . .
WELDING. . . . . . . . . . . . . . . . . . . . . .
WELDING . . . . . . . . . . . . . . . . . . . . . . . . . .
ELECTRIC RESISTANCE SPOT
WELDING . . . . . . . . . . . . . . . . . . . . . . . . . .
GAS SHIELD ARC WELDING . . . . . . . . . .
OTHER TYPES OF WELDING . . . . . . . . . .
BODY REPAIR. . . . . . . . . . . . . . . . . .
STANDARD BODY REPAIR
PROCEDURES. . . . . . . . . . . . . . . . . . . . . .
THEFT PROTECTION . . . . . . . . . . . . . . . .
ATTACHMENT OF SILENCERS . . . . . . . .
POSITIONING DIMENSIONS FOR
OPENINGS . . . . . . . . . . . . . . . . . . . . . . . . .
STANDARD PROCEDURES FOR
SHEET METAL WORK . . . . . . . . . . . . . . . .
USING A FRAME STRAIGHTENER . . . . . .
FRAME REPAIR PROCEDURES . . . . . . . .
NOTES REGARDING REPAIR WORK . . . .
HEAT-WITHSTAND TEMPERATURES
OF RESIN-PLASTIC PARTS . . . . . . . . . . .
HOW TO DISTINGUISH TYPES OF
PLASTICS . . . . . . . . . . . . . . . . . . . . . . . . . .
CORROSION PROTECTION . . . . . . .
ANTICORROSION TREATMENT AT
THE FACTORY . . . . . . . . . . . . . . . . . . . . . .
ANTICORROSION TREATMENT AT
THE TIME OF BODY REPAIR WORK . . . .
REPAIR OF SYNTHETIC-RESIN
PARTS . . . . . . . . . . . . . . . . . . . . . . . .
SYNTHETIC-RESIN PARTS REPAIR
PROCEDURES . . . . . . . . . . . . . . . . . . . . . .
GENERAL
TSB Revision
BASE OF BODY REPAIR
9-2
GENERAL
M4090000100018
Group 9 is applicable for all models.
WELDING
WELDING
M4090001000058
Welding is the partial joining of two or more metals
by deposition; the welding methods used for body
maintenance and repair can be classified into the fol-
lowing methods.
FUSION WELDING
Fusion welding is a method of welding in which the
weld connection is made by forming or supplying the
weld metal at the part where the weld is to be made.
PRESSURE WELDING
Pressure welding is a method of welding in which the
weld connection is made by applying external pres-
sure while the part where the weld is to be made is in
a molten or semi-molten condition.
BRAZING
Brazing is a method of welding in which the weld
connection is made by supplying a filler metal (which
is molten at a temperature lower than the melting
temperature of the base metal) at the place where
the joining is to be made without melting the base
metal itself.
Welding methods
Fusion methods
Shielded arc welding
Gas welding
Electric resistance spot welding
CO
2
gas arc welding
Pressure methods
[Temperature approximatery 1,500˚C (2,732˚F) or higher at weld area]
Brazing methods
Brazing
Soldering
Temperature: 620
–
950˚C
(1,148
–
1,742˚F)
Temperature: 183
–
310˚C
(361
–
590˚F)
Temperature: 1,130
–
1,550˚C
(2,066
–
2,822˚F)
AB301447AB
WELDING
TSB Revision
BASE OF BODY REPAIR
9-3
ELECTRIC RESISTANCE SPOT WELDING
M4090002000040
Electric resistance spot welding is a method for fus-
ing metal parts together. Two or three metal sheets
are positioned between two copper-alloy electrode
tips, and pressure and a large current are then
applied, thus causing the contacting surfaces to heat
up and fuse together because of the electric contact
resistance.
ADVANTAGES OF ELECTRIC
RESISTANCE SPOT WELDING
• Because the time required for welding at each
point is brief, the work can be done quickly and at
reduced cost.
• Because both metals are fused and pressure
applied to make the weld, the strength and reli-
ability are both high.
• Because the time required to make the welds is
short, there is little occurrence of distortion of the
panel due to heat.
.
PROCEDURE
There are three basic stages in electric resistance spot weld-
ing.
1. Initial pressure application stage
This stage precedes the current application. Applying
pressure to the steel panels through the electrode tips
ensures a uniform contact resistance and a smoother
current flow.
2. Current application stage
While an ample amount of pressure is being applied, the
current is sent through the electrode tips. The contact
resistance causes the contact surfaces of the steel panels to
heat up and fuse together.
3. Holding stage
When the current application is finished and a nugget (a
solidified piece of molten metal) forms at the weld, the
pressure application is continued in order to strengthen the
weld. This is the most important stage of electric resistance
spot welding in ensuring the strength of the weld.
.
AB200026
AB200027
AB200028
WELDING
TSB Revision
BASE OF BODY REPAIR
9-4
NUGGET FORMATION
Generally speaking, the size of the nugget will
increase as the welding current increases, and as
the size of the nugget increases, the strength of the
weld will also increase.
Nugget formation will not begin until the current level
reaches a certain point; however, once this welding
current level is passed, the strength will increase rap-
idly (between points A and B).
As the current level increases further, the weld
strength for thick panels [more than 1.6 mm (0.063
inch)] continues to increase proportionately (between
points B and C); however, for thin panels [1.6 mm
(0.063 inch) or less], the weld strength reaches a
peak very quickly and will increase only slightly, even
if the current level increases (between points B' and
C').
Then, for both thick panels and thin panels, the mol-
ten metal will scatter if the current level increases
past a certain point.
.
AB301468
Small
← Welding current → Large
W
eak
←
Shear strength per point
→
Strong
Cooling water
Cooling water
Elect-
rode
Elect-
rode
Nugget
Steel
panel
Water
temperature
540
(1,000)
1,095
(2,000)
1,650˚C
(3,000)˚F
Max. Heating temperature
Melting point
A'
B'
D
B
D'
C'
1.6 mm (0.063 in)
or less
More than
1.6 mm
(0.063 in)
C
A
C Is The Scatter Point
AD
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