Hitachi WH 12DAF2 Bedienungsanleitung Seite 13

NOTE:
If a long striking tim e is used, screw s w ill be strongly
tightened. This m ay cause the screw to break, or m ay
dam age the tip of the bit.
If the unit is held at an angle to the screw being
tightened, the head of the screw m ay be dam aged, or
the specified torque m ay not be transm itted to the
screw . Alw ays keep the unit and the screw being
tightened in a straight line.
4. Use a tightening time suitable for the screw
The appropriate torque for a screw differs according
to the m aterial and size of the screw , and the m aterial
being screw ed etc., so please use a tightening tim e
suitable for the screw . In particular, if a long tightening
tim e is used in the case of screw s sm aller than M 8,
there is a danger of the screw breaking, so please
confirm the tightening tim e and the tightening torque
beforehand.
5. Work at a tightening torque suitable for the bolt
under impact
The optimum tightening torque for nuts or bolts differs
w ith m aterial and size of the nuts or bolts. An
excessively large tightening torque for a sm all bolt
m ay stretch or break the bolt. The tightening torque
increases in proportion to the operaton tim e. Use the
correct operating tim e for the bolt.
6. Holding the tool
Hold the im pact w rench firm ly w ith both hands. In
this case hold the w rench in line w ith the bolt.
It is not necessary to push the w rench very hard.
Hold the w rench w ith a force just sufficient to
counteract the im pact force.
7. Confirm the tightening torque
The follow ing factors contribute to a reduction of the
tightening torque. So confirm the actual tightening
torque needed by screw ing up som e bolts before the
job w ith a hand torque w rench. Factors affecting the
tightening torque are as follow s.
(1) Voltage
When the discharge m argin is reached, voltage
decreases and tightening torque is low ered.
〈 WH12DAF2 〉
kgf cm N m
• •
M 8 × 30
1000 100
800 80
High tension bolt
600 60
400 40
200 20
Ordinary bolt
0 0
0 1
Tightening tim e: sec.
(Steel plate thickness
t = 10 m m )
kgf cm N m
• •
1000 100
High tension bolt
800 80
600 60
400 40
200 20
0 0
2 3 0
Tightening tim e: sec.
(Steel plate thickness
t = 10 m m )
(2) Operating tim e
The tightening torque increases w hen the operating
tim e increases. But the tightening torque does not
increase above a certain value even if the tool is
driven for a long tim e. (See Fig. 18 and 19)
(3) Diam eter of bolt
The tightening torque differs w ith the diam eter of the
bolt as show n in Fig. 18 and 19. Generally a larger
diam eter bolt requires larger tightening torque.
(4) Tightening conditions
The tightening torque differs according to the torque
ratio; class, and length of bolts even w hen bolts w ith
the sam e size threads are used. The tightening torque
also differs according to the condition of the surface
of w orkpiece through w hich the bolts are to be
tightened. When the bolt and nut turn together, torque
is greatly reduced.
(5) Using optional parts (WR12DAF2)
The tightening torque is reduced a little w hen an
extension bar, universal joint or a long socket is
used.
(6) Clearance of the socket (WR12DAF2)
A w orn or deform ed hex. or a square-holed socket
w ill not give an adequate tightness to the fitting
betw een the nut or anvil, consequently resulting in
loss of tightening torque.
Using an im proper socket w hich does not m atch to
the bolt w ill result in an insufficient tightening torque.
(7) Tightening torque varies, depending on the battery's
charge level. (WR12DAF2)
Fig. 21 show exam ples of the relationship betw een
tightening torque and the num ber of tightenings, for
WR12DAF2. As show n, tightening torque gradually
w eaken s w i t h t h e i n cr ease i n t h e n u m b er o f
tightenings. In particular, as the torque decreases
very close to the com plete discharge (" a" m argin in
graph), the unit's im pact w eakens, the num ber of
tim e im pacts declines and tightening torque drops
off abruptly. If this occurs, check torque level, then
recharge the battery if necessary.
kgf cm
•
1200
M 10 × 30
1000
800
600
400
Ordinary bolt
200
1 2 3
Fig. 18
English
N m
•
M 12 × 45
120
High tension bolt
100
80
60
Ordinary bolt
40
20
0 0
0 1 2
Tightening tim e: sec.
(Steel plate thickness
t = 25 m m )
3
12