Hitachi WH 14DSL Bedienungsanleitung Seite 12

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3. Tightening torque
Refer to Fig. 16, 17 and 18 for the tightening torque of bolts (according to size).
Please use this example as a general reference, as tightening torque will vary
according to tightening conditions.
NOTE:
If a long striking time is used, screws will be strongly tightened. This may
cause the screw to break, or may damage the tip of the bit.
If the unit is held at an angle to the screw being tightened, the head of the
screw may be damaged, or the specified torque may not be transmitted to the
screw. Always 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 material and size
of the screw, and the material being screwed etc., so please use a tightening
time suitable for the screw. In particular, if a long tightening time is used in
the case of screws smaller than M8, there is a danger of the screw breaking,
so please confirm the tightening time 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 with material and
size of the nuts or bolts. An excessively large tightening torque for a small
bolt may stretch or break the bolt. The tightening torque increases in
proportion to the operaton time. Use the correct operating time for the bolt.
6. Holding the tool
Hold the impact wrench firmly with both hands. In this case hold the wrench
in line with the bolt.
It is not necessary to push the wrench very hard. Hold the wrench with a
force just sufficient to counteract the impact force.
(Battery: BSL1430)
For WH14DSL
kgf·cm N·m
1500
1000
500
11
Save mode
150
100
High tension bolt (M12)
50
Ordinary bolt (M12)
0 0
0 0 1 2 3
Tightening time: sec.
(Steel plate thickness t = 25 mm)
7. Confirm the tightening torque
The following factors contribute to a reduction of the tightening torque. So
confirm the actual tightening torque needed by screwing up some bolts
before the job with a hand torque wrench. Factors affecting the tightening
torque are as follows.
(1) Voltage
When the discharge margin is reached, voltage decreases and tightening
torque is lowered.
(2) Operating time
The tightening torque increases when the operating time increases. But the
tightening torque does not increase above a certain value even if the tool is
driven for a long time. (See Fig. 16, 17 and 18)
(3) Diameter of bolt
The tightening torque differs with the diameter of the bolt as shown in Fig. 16,
17 and 18. Generally a larger diameter bolt requires larger tightening torque.
(4) Tightening conditions
The tightening torque differs according to the torque ratio; class, and length
of bolts even when bolts with the same size threads are used. The tightening
torque also differs according to the condition of the surface of workpiece
through which the bolts are to be tightened. When the bolt and nut turn
together, torque is greatly reduced.
Power mode
kgf·cm N·m
1500 150
1000 100
500 50
Ordinary bolt (M12)
0 0
0
0 1
Tightening time: sec.
(Steel plate thickness t = 25 mm)
Fig. 16
High tension bolt (M14)
High tension bolt (M12)
Ordinary bolt (M14)
2 3