Hitachi WH 14DM, Технические данные и руководство по обслуживанию

Страница: 11 / 31

--- 8 ---
7-2. Tightening Torque
7-2-1. Tightening torque characteristic comparisons
Thanks to the high-power rare-earth magnet motor and the larger hammer inertia, the Model WH 14DM can
provide greater tightening torque.
Test conditions
Bolt: M12 x 45 mm (15/32" x 1-3/4")
(strength grade: 12.9)
Steel plate: Mild steel
Thickness = 25 mm (1")
Accessory tool: Hexagon socket ass'y
7-2-2. Screw diameter and appropriate tightening torque
Generally speaking, the appropriate tightening torque for a screw can be determined by the strength grade of the
screw and the material tightened. Tables 1 and 2, and Fig. 3 below list data relative to the strength grade of
various screws and the appropriate tightening torque. For further reference, appropriate tightening torque is
calculated with the following formula. Study and use this formula for accurate selection of tightening torque.
T= 9.8 k
•
d
•
p/100
T: Appropriate tightening torque (N
•
m)
k: Torque coefficient (0.17)
d: Nominal diameter for the screw (mm)
p: Recommended axial tightening force to be applied to the screw (kgf)
p=rated axial stress (kgf/mm 2 ) x 0.8 x effective sectional area of the thread (mm 2 )
•
Strength grade and rated axial stress of threads
Strength grade
Rated axial stress (kgf/mm 2 )
Material
Heat treatment
4.8 6.8 8.8 12.9
29.1 43.7 58.2 95
Mild steel Alloy steel including Ni, Mn, Cr, etc.
None Processed-hard material
•
Diameter and effective sectional areas of threads
Kind of thread (x pitch)
Effective sectional area
of thread (mm
2
)
M5 x 0.8 mm
(3/16")
14.2
M6 x 1 mm
(1/4")
20.1
M8 x 1.25 mm
(5/16")
36.6
M10 x 1.5 mm
(3/8")
58.0
M12 x 1.75 mm
(15/32")
84.3
M14 x 2 mm
(9/16")
115
Table 1
Table 2
Fig. 2
160
40
80
140
0
1600
(1389 in-lbs.)
1200
(1042 in-lbs.)
800
(694 in-lbs.)
400
(347 in-lbs.)
0
kgf
•
cm N
•
m
Tightening torque
60
100
120
20
0 0
1
2 3 (sec.)
1400
(1215 in-lbs.)
1000
(868 in-lbs.)
600
(521 in-lbs.)
200
(174 in-lbs.)
Tightening time
P
C
WH 14DM
WH 12DM