Improvements in Twist-drills, Broaches, and the like..
Year: 1895

page_text: Date of Application, 21st Jan., 1895
Complete Specification Left, 9th Oct., 1895-Accepted, 23rd Nov., 1895
PROVISIONAL SPECIFICATION..
Improvements in Twist-drills, Broaches, and the like..
I, EDUARD BRESLAUER, Engineer, of Göthestrasse 1, Leipzig, in the Empire.
of Germany, do hereby declare the nature of this invention to be as follows:
In the manufacture of twist drills and broaches it is especially of importance
that the groove for the chips be made as spacious as possible in order that the
chips may be easily removed without however weakening the drill or the like to
such a degree that it yields under pressure in lateral direction, or that even the-
This is attained in. the
cutting or guiding ribs are in danger of breaking away.
present invention by a low reinforcing rib arranged between the two cutting or
guiding-ribs.
Fig. 1 of the annexed drawing shows the simplest form of this profile or cross
section. It may be regarded as a flat steel, which is provided with two low
reinforcing ribs R¹ and R². Another form of construction is shown in the section.
in Fig. 2. In this latter the cutting or guiding ribs S1 and S2 taper toward, the
axis of the tool.
From
In order to diminish the work of grinding the twisted tool, the two cutting
ribs S1 and S2 may be rounded off on their outer faces as shown in Fig. 3.
this section immediately originates that illustrated in Fig. 4, in which the
cutting or guiding ribs are cut hollow in order to produce on the one hand a
sharper cutting-edge and on the other hand a larger channel for removal of the
chips. Fig. 5 sbows a further modification of the section illustrated in Fig. 4, in:,
which only the front-cutting-edges are hollowed whilst the rear faces of these ribs..
are curved outwardly for the purpose of strength.
All these sections have the same advantage, since such steel, when twisted,.
forms a boring tool with very large chip-removing-groove without endangering
the solidity of the tool. The low reinforcing ribs R¹ R³ are ground away in front
at the point of the drill.
Where narrow cutting or guiding-ribs are required with a large pitch of twist.
such drills are liable to have a defective seating or grip in their holders. Fig. 6.
shows an arrangement in which this defect is obviated by the shaft of the drill,
that is to say the portion from B to C, being twisted to a considerably_smaller
pitch than the drill proper, that is the part from A to B. The end C D of the
shaft is set-off flatly. The shaft may be turned off conically or cylindrically and.
will under these conditions offer sufficient surfaces for the grip of its holder.
T
1903
F
.
I EDUARD BRESLAUER Engineer of Göthestrasse 1, Leipzig in the Empire of
Ụ Germany do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement :-
In the manufacture of twist drills and broaches it is especially of importance

page_text: that the groove for the chips be made as spacious as possible in order that the
chips may be easily removed without however weakening the drill or the like to
such a degree that it yields under pressure in lateral direction or that even the
cutting or guiding ribs are in danger of breaking away. This is attained in
the present invention by a low reinforcing rib arranged between the two cutting
or guiding ribs. Fig. 1 of the drawing filed with my Provisional Specification
shows the simplest form of this profile or cross section. It may be regarded as a
flat steel which is provided with two low reinforcing ribs R¹ and R2. Another
form of construction is shown in the section in Fig. 2. In this latter the cutting
or guiding ribs S1 and S2 taper towards the axis of the tool.
In order to diminish the work of grinding the twisted tool the two cutting
ribs S1 S2 may be rounded off on their outer faces as shown in Fig. 3. From
this section immediately originates that illustrated in Fig. 4 in which the cutting
or guiding ribs are cut hollow in order to produce on the one hand a sharper
cutting-edge and on the other hand a larger channel for removal of the chips.
Fig. 5 shows a further modification of the section illustrated in Fig. 4 in which
only the front cutting edges are hollowed whilst the rear faces of these ribs are
curved outwardly for the purpose of strength.
All these sections have the same advantage since such steel when twisted forms
a boring tool with very large chip removing groove without endangering the
solidity of the tool. The low reinforcing ribs RI R2 are ground away in front
at the point of the drill. Where narrow cutting or guiding ribs are reuired. with
a large pitch of twist such drills are liable to have a defective seating or grip in
their holders. Fig. 6 shows an arrangement in which this defect is obviated by
the shaft of the drill, that is to say, the portion from B to C being twisted to a
considerably smaller pitch than the drill proper that is the part from A to B.
The
end CD of the shaft is set off flatly. The shaft may be turned off conically or
cylindrically and will under these conditions offer sufficient surfaces for the grip of
its holder.
re
Having now particularly described and ascertained the nature of this said inven-
tion and in what manner the same is to be performed declare that what I
claim is :-
1. An improved drill or broach consisting of a helically grooved or twisted steel
of a section having between its two cutting ribs S1 and S2 two low reinforcing
ribs R 1 and R2 in order to permit of the production of spacious chip grooves
without the resistance and solidity of the section being impaired.
2. A form of construction of drills and broaches as described in Claim 1, in
which the shaft is provided with helical twist or grooving of considerably less
pitch than that of the drill itself in order to obtain an improved seating and
gripping of the drill in its holder.
Dated this 9th day of October 1895
"HERBERT HADDAN & Co.,
18 Buckingham Street, Strand, London, W.C., Agents TO Applicant.