|
Main Technical Conditions Of Twist Drill
Drill diameter
The values indicated in the relevant dimensional standards
apply in respect of the diameter of Twist Drills.
Test point: On the lands at the corners,(see Fig.l)
Testing equipment: micrometer
Tapering of diameter
The diameter of twist drills usually reduces from the drill
tip towards the shank in the area of the flutes.
Test values:The taper on diameter amounts to 0.02 to 0.08mm
over a length of 100mm.
Test point: At the outside diameter on the land.
Testing equipment: micrometer and indicating measuring
instruments.
Parallel shank
Tolerance for shank diameter f11,Tolerance for roundness and
parallelism 0.02mm for the shank length.
Concentricity tolorance(Tr.)
The concentricity tolerance(Tr.) of the Twist Drill
is calculated from the equation.
Tr=O.03+O.O11/d
In which I is the total length and d the diameter of the
drill (all dimensions in mm)
Length
The tolerance of length for the total length corresponds for
the degree of accuracy very coarse according to DIN 7168
part 1.The flute lengths given in the relevant dimensional
stands are minimum dimensions.
Point angle
Test value:σ=118°;σ135°
Test point: At the cutting edges(See Fig.2)
Testing equipment: Universal bevel protractor indicating
measuring instruments.
Materials and
hardness
Materials
M2; M35i M42; F4341; 93410r4341;
Hardness
HSS HRC63-66
HSSCO HRC64-68
Test point: On outside diameter on the land or adjacent
relieved land.
Test equipment: Hardness Tester.
Making
Twist drills with diameter 3mm and upwards shall be marked
with:
Diameter
Material:(HSS;HSSCO;)
Name or mark of manufacturer.
Additional and/or differing marking by agreement.
Twist Drill
with parallel shank
Twist Drill
with taper shank
General
dimensions of morse taper shanks
|
Morse Taper Shank |
A mm |
B mm |
C(h13) mm |
D mm |
E mm |
F(max.) mm |
G mm |
H(max.) mm |
α/2 |
|
No.1 |
12.065 |
9 |
5.2 |
12.2 |
62 |
13.5 |
3.5 |
8.7 |
1°25’43 |
|
NO.2 |
17.780 |
14 |
6.3 |
18.0 |
75 |
16 |
5 |
13.5 |
1°25’50 |
|
NO.3 |
23.825 |
19.1 |
7.9 |
24.1 |
94 |
20 |
5 |
18.5 |
1°26’16 |
|
NO.4 |
31.267 |
25.2 |
11,9 |
31.6 |
117.5 |
24 |
6.5 |
24.5 |
1°29’15 |
|
NO.5 |
44.399 |
36.5 |
15.9 |
44.7 |
149.5 |
29 |
6.5 |
35.7 |
1°30’26 |
|
NO.6 |
63.348 |
52.4 |
19 |
63.8 |
210 |
40 |
8 |
51 |
1°29’36 |
Cutting portion
σ= Point angle (sigma)
ψ = Chisel edge angle(psi)
*)In the context of cutting technology, land width b is the
body clearance land width which is to be by bfan
see DIN 6581.
Angle at the cutting edges
The corner has been
adopted as the observed edge point
αx=Side clearance angle (alpha)
αxe=Effective side clearance angle
βx=Side wedge angle(beta)
γx=Front rake angle(gamma)
γxe=Working front rake angle
η=Resultant cutting speed angle(eta)
Clearance angle α,wedge angle β and
rake angleγare measured in the tool orthogonal plane. For
details, see DIN 6581, definitions of metal-cutting
technology; geometry at the tool edge.
Web thickness
K
Test values:The web
thickness according to Fig.1 shall not be less than the
minimum value kmin indicated in Fig.2.
Test point: At the point of the drill.
Testing equipment:Slide gauge with
measuring points.
|
