Drilling - Rohm Norm RN 1391 Informaciones Y Directivas Generales Para El Empleo De Instalaciones De Sujeción Accionadas Por Fuer

2 | Reference Speed and Clamping Force Calculation
2.1.4

Drilling

Ÿ Drilling in solid material (top lip twist drill - point angle ≥ 120°)
For a) (see Determining the Required Clamping Force of a Power Chuck
[} 40])
The clamping force required is determined by the type of work to be per-
formed. The calculation described below applies to freely chucked work-
pieces, i. e. workpieces which are not axially seated against the jaws. The
components working on the workpiece here, cutting force F
F produce the resulting force F
vax
The cutting force F
F = s ∙ t ∙ k
sbo
where:
s = feed mm/rev.
t = depth of cut mm =
k = specific cutting force kN/mm²
c
The Feed force F
directly obtained from Table 4.
6.3
4.0
2.5
1.6
0.80
Fig. 4: Feed force F
50 / 138
can be calculated from:
sBo
(4)
c
bit diameter
bears a given relationship to the cutting force and can be
vax
1.25 2.0 3.15 5.0
Cutting force FsBo [kN]
vax
which defines the clamping force.
R
8.0 12.5
Schnittkraft F [kN]
sBO
and feed force
sBo
31.5
RN-1391