Improvements in Automatic Feed-mechanism for Drilling-machines.
Year: 1898

page_text: Date of Application, 17th Feb., 1898-Accepted, 2nd Apr., 1898
Improvements in Automatic Feed-mechanism for Drilling-machines.
I, PER ANTON CRELIUS, of Smedjebacken, in the Kingdom of Sweden, Mechanical
Engineer, 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 invention relates to automatic feed-mechanism for drilling-machines and
more especially for rock-drills.
In the accompanying drawing I have shewn my invention applied to a rock
drill-
Figure 1 is a section on the line x-x of Figure 2:
Figure 2 is a section on the line y-y of Figure 1; and,
Figure 3 is a sectional view similar to that of Figure 1 and showing the adapta-
tion of the rock-drill for drilling to greater depths in loose rock.
In the frame 1, which by means of journals 2 is movably fitted to a suitable
support or standard to allow of adjusting the drill to different positions, there is
mounted a driving shaft 3 the two ends of which project beyond the frame of the
machine so as to admit of attaching a crank at each end of the shaft when the
machine is to be driven by hand. In driving by machine-power, a belt-pulley or
the like is attached to the shaft. The latter carries a cylindrical screw-gear wheel 4
suitably secured to it and engaging with another screw-gear wheel 5 which is fixed
to a sleeve 7 journalled in the frame and surrounding the drill-bar 6. The sleeve
is provided with a feather 8 which enters a slot in the drill-bar, thus compelling the
latter to take part in the rotation communicated to the sleeve by the wheels 4, 5
whilst at the same time allowing of its being moved to and fro in the sleeve. The
wheels 4 and 5 are so made that they can replace one another in order to give
another velocity ratio.
The
On the drill-bar, which is screw threaded, there is fitted another sleeve 9 which,
unlike the sleeve 7, engages with the drill-bar or forms a nut for the same.
sleeve 9 is provided with a flange, against which abuts one end of a spiral spring 10,
Figure 1, the other end of which bears against a collar 12 running on a ball-
bearing 11 on the opposite side of the flange of the sleeve 9 with respect to the
drilling-tool. The sleeve 9 passes freely through the collar 12, the ball-bearing, the
frame, and a cap or cover 13 secured to the latter. Outside the said cap the sleeve 9,
which is also screw threaded externally, is provided with a nut 14, forming a
shoulder on the same, and with a lock-nut 15. Between the nut 14 and the frame,
or cap 13, the drawing shows a disc of leather or other suitable material, the object
of this arrangement being hereinafter described. The screw-gear wheel 5 and
sleeve are preferably made to run on a ball-bearing 17.
The feed-mechanism above described and shown in Figure 1 operates as follows.
Suppose that, when the drill is in contact with the rock, the nut 14 is at a slight
distance from the frame of the machine or from the disc 16. Neglecting the
weight of the drill-bar and drill-tubes, the pressure of the tool against the rock will
then evidently depend upon the tension of the spring 10. While the drilling-tool
is entering the rock, the nut 14, which together with the sleeve 9 takes part in the

page_text: :
motion of the drill-bar, gradually approaches the disc 16, the tension of the spring 10
simultaneously relaxing somewhat. As soon as the nut 14 comes in contact with
the disc 16, the rotation of the said nut and of the sleeve 9 will be retarded owing
to the friction on the disc. The continued rotation therefore, of the drill-bar 6 in
the direction indicated by the arrow in Figure 1 produces a relative motion between
the drill-bar and the sleeve 9 and, as the latter moves more slowly than the drill-
bar, the sleeve will be screwed slightly upwards so as to increase the tension of the
spring 10 to the pressure required for feeding the drill forward, the velocity of
rotation of the sleeve 9 being at the same time increased. When the nut 14, during
the downward motion of the drill-bar and the sleeve 9, is again brought to bear
sufficiently hard upon the disc 16, the rotary motion of the sleeve will again be
retarded, the sleeve will be screwed slightly upwards and the tension of the spring 10
increased once more. The fluctuations in the velocity of rotation of the sleeve 9
will evidently be quite small, provided that the friction of the nut 14 on the frame
is slight, and therefore the sleeve can be regarded as rotating at a constant velocity
which is slower than that of the drill-bar. The tension of the spring 10, and con-
sequently the pressure of the latter on the drill-bar, may also be regarded as
constant. When the friction of the nut 14 on the frame is very great, the nut and
sleeve are liable to be altogether stopped until they have become screwed up the
rod 6 sufficiently far to cause the nut to loosen its hold. The sleeve is then again
carried along until the nut is again stopped by the frame. The sleeve will thus be
revolved intermittently; if, however, the movements follow closely upon one
another, the tension of the spring 10 will still be constant, or practically constant.
The disc 16 merely serves to increase the friction on the nut 14 and it may be dis-
pensed with.
The tension of the spring 10 may evidently be adjusted, to suit the
quality of the rock etc. being drilled, by tightening the nut 14. In lieu of a spiral
spring, it is evident that spring discs, leaf-springs, etc. may be employed.
When the depth of the bore-hole becomes such, or the consistency of rock is
such, that in vertical drilling a pressure on the drilling-tool less than the weight of
the drill-bar is required, the spring 10 is so arranged that it will support a greater
or less portion of the weight of the drill-bar. For this purpose the spring 10 is
placed below the sleeve 9, as shown in Figure 3, so that one end of the spring
bears against the underside of the flange of the sleeve. The ball-bearing 11 and
collar 12 are also located below the sleeve 9 on a support projecting from the
casing 1, that is to say, on the flange 18. In order to give proper guidance to the
ball-bearing 11 and the collar, a sleeve 19 is fitted over the drill-bar. In lieu of
this arrangement, a ball-bearing may be employed which fits around the drill-bar
and is directly guided by the latter. The mode of operation is identical with that
of the apparatus shown in Figure 1, the spring 10 being kept at a constant tension
and always sustaining a certain portion of the weight of the drill-bar or drill-tubes.
The rock-drill shown in Figure 1 may thus, by simply changing the position of the
spring 10 and the corresponding ball-bearing, be adapted for drilling at greater
depths or in loose rock. Instead of the spring being in contact with the flange 18
by means of a ball-bearing it can be made to abut, by means of the ball-bearing,
against the screw-gear wheel 5, but the arrangement with the flange 18 is more
suitable since, with the alternative arrangement mentioned, the weight of the
drill-bar and drill-tubes as well as the pressure due to the screw-gear wheel 4 would
have to be sustained by the ball-bearing 17 alone.
The frame is made in two parts or as a case. One of the said parts is movable
on hinges so that the case can be opened on loosening the screw 20.
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
1. Automatic feed mechanism for drilling machines, comprising a screw-threaded
drill-bar 6 actuated by means of screw-gearing, a sleeve (or nut 9) which is in
engagement with the said drill-bar and passes freely through a hole in the frame of

page_text: the machine or in a fixed part attached to the latter and forming an abutment for
a shoulder (or nut 14) on the sleeve 9 and situated on the other side of the above
mentioned fixed part with respect to the drilling-tool, and a spring-arrangement
actuating the sleeve 9, for the purpose of causing the sleeve 9 to be rotated on the
drill-bar, when the shoulder 14 comes in contact with the aforesaid abutment, and
to be thereby operated in such a manner that the spring-arrangement will be kept
at a constant tension so that its pressure on the sleeve, and therefore on the
drill-bar is maintained constant substantially as hereinbefore described and
illustrated.
2. In drilling-machines of the kind described in Claim 1, the arrangement
whereby the spring-device is caused to act upon the sleeve and drill-bar in the
direction of the drilling-tool or the piece of work operated on for the purpose of
causing the said spring-device to regulate the pressure of the tool, substantially as
hereinbefore described.
3. In drilling-machines of the kind described in Claim 1 and designed for
vertical drilling and wherein the weight of the drill-bar and drill-tubes is too great,
the arrangement whereby the spring-device is located so as to act upon the sleeve
and drill-bar in a direction away from the drilling-tool so as to regulate the
pressure by supporting a portion of the weight of the drill-bar and drill-tubes,
substantially as hereinbefore described and illustrated.
4. The feed devices for drilling machines hereinbefore described and illustrated
respectively in Figures 1 and 2; and 3 of the accompanying drawing.
Dated this 17th day of February 1898.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.