Improvements in Feeding Mechanism for Drills.
Year: 1894

page_text: Date of Application, 6th Mar., 1894-Accepted, 7th Apr., 1894
COMPLETE SPECIFICATION.
Improvements in Feeding Mechanism for Drills.
I, BIRGER LJUNGSTRÖM of Grefgatan, 44", Stockholm, in the Kingdom of
Sweden, Instrument Maker, 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 :-
This feeding mechanism consists substantially of a bottom-piece in two parts
gripped in a clamp against which bottom-piece the feeding screw, likewise gripped
by the clamp, rests by means of its pointed ends, while it constitutes itself the
point or centre by means of which the drill in the usual way rests against some firm
object.
By the pressure of the feeding screw the bottom portions are wedged apart and
the clamp opened, so that the feeding screw becomes free and does not feed, or,
inversely, the feeding screw is held fast by the clamp which is adjustable with
respect to its pressure upon the screw, so that feeding takes place.
In the accompanying drawing,
Figure 1 represents a ratchet-brace provided with the improved arrangement.
Figure 2 shows a section of the clamp and the divided bottom.
Figure 3 is a plan of the same.
Figure 4 is a detail view of the divided bottom and
Figures 5 and 6 show two modifications.
The outer end of the feeding screw A is provided with the clamp B which can
be tightened over the end of the said feeding screw by means of the screw C at the
end of the clamp. An arm D passing through the other end of the clamp and
resting against some firm object prevents the said clamp from turning round with
the screw.
In a groove in the clamp is also fixed the bottom-piece serving as a
step bearing for the end of the screw A. This bottom-piece consists of two parts F
and G of which the one F forms the outer resting point or pivot for the whole
brace and bas a recess on the inner side, in which the other part G is located.
With respect to the screw the two parts form a divided bottom-piece, between the
halves of which the point of the screw enters a little. With a greater pressure on
the point of the screw the two parts F and G separate and expand the clamp.
The screw then partakes in the rotatory motion of the brace, and consequently
does not feed. When boring the pressure after a time decreases and the two
parts F and G are pressed together by the clamp. Finally the clamp grips the
screw so firmly as to hold it fast, so that it is screwed out of the brace and will
feed until it is disconnected by the increased pressure upon the parts F and G, and
The more the screw C is tightened, the greater will be the pressure upon
the parts F and G necessary for the disconnection and the greater will be the
feed which in this way may be regulated.
so on.
The modification shown in Figure 5 consists therein that the outer point consists
of the one end of a double cone H the other end of which together with the point
of the screw is gripped by a divided ring or bottom-piece I introduced in the
clamp in the same way as the parts F and G abovementioned. In order that the
cone H may be retained in place it is provided with a conical extension / which is
also clamped by the ring and for which there is a flat portion on the end of the
screw. The said flat part is sufficient to allow the screw to approach the cone
during which approach the halves of the ring are separated and the clamp is
opened. The mode of action will be easily understood by the preceding
description.

page_text: The modification shown in Figure 6 consists only therein that the screw A and
the parts resting against the end of the same are located at the end of the
clamp.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. Feeding mechanism for drills having a feeding screw projecting from the
brace in line with the bit, consisting of a clamp which can be tightened by means
of a clamping screw and in which is located a bottom-piece made in two parts,
resting against the pointed end of the screw gripped by the clamp, and constituting
a pivot pin for the brace, with the object that a pressure as constant as possible
upon the drill may be obtained by the clamp tightening more around the screw,
when the pressure against the bottom-piece decreases, but opening a little, when the
pressure is increased thus effecting a uniform feed.
2. The modification of the feeding mechanism specified in the first claim, in
which the bottom-piece does not directly constitute a pin or pivot point but
consists of a divided ring in which is clamped a double cone as described with
reference to Figure 5.
Dated this 6th day of March 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.