Improvements in Combined Drilling and Percussive Hand Tools, and Means for Actuating them.
Year: 1892

page_text: Date of Application, 10th Nov., 1892-Accepted, 4th Feb., 1893
537
MLAY
Improvements in Combined Drilling and Percussive Hand Tools,
and Means for Actuating them.
I, ROBERT TELSCHOW, M.D. of Charlottenstrasse, Berlin, German Empire,
Court Councillor, 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 :-
The principal object of this invention is a machine tool for the use of dentists,
sculptors, engravers &c.
When applied to machine tools my invention is mainly characterized by the
machine tool carrying a drilling apparatus, or other mechanism operated by rapid
rotation, and at the same time a pneumatic hammer striking against a stamp
carrying a chisel or other tool operated by an oscillating double acting air pump
arranged on the frame of the machine; both tools may be used at the same time,
or only one or the other.
Further, the pneumatic hammer may be so arranged that its working part
receives automatically an intermittent rotary movement.
The rebound of the pneumatic tool may be weakened by the partial escape of
compressed air, which may be utilized to blow away the dust formed by the
working of the tool on the article operated upon.
In order that my invention may be the better understood I now proceed to
describe the same in relation to the accompanying drawings, reference being had to
the letters and figures marked thereon.
Figure 1 is a front elevation of the machine.
Figure 2 is a side view of the machine showing the double acting air pump in
section and the connection of the drilling or boring tool to the rigid driving
axle.
•
Figure 3 is a sectional view of the flexible drill drawn to a larger scale.
Figure 4 is a sectional view of the pneumatic hammer.
Figure 5 is a sectional view of the pneumatic hammer with mechanism to
produce an intermittent rotary movement of the tool.
Figure 6 shows an adjustable pin on the driving disc to disconnect the air
pump.
In Figure 1, c is the frame of the machine tool, a² a' and 6¹ are the driving
mechanism, a is a rigid axle, carrying at one end the disc or sheave a¹ with the
adjustable pin a, the other end having a square recess to receive the square
connecting piece 6 of the flexible axle c, Figure 3. is the cylinder of the air
pump situated in the ring d' so as to enable it to oscillate. e¹ is the piston of the
air pump fitted closely into the cylinder c² in which it moves up and down.
Sand S¹ are short tubes for the attachment of the tubes carrying the pneumatic
hammer W.
Figure 3, as before mentioned, shows in section the ordinary flexible axle c to
which is attached at B the tool e. The flexible axle c is carried at A in the
tube d provided with metallic protecting pieces.
This flexible axle c is connected to the rigid axle a by means of any suitable
coupling, which in the drawings is shewn as a square piece b. The connection is
secured by screwing the tube d surrounding the flexible axle c to the frame c¹ by
means of the sleeve L.
Figure 4 is a section of the pneumatic hammer and working tool. H is a
handle, C is a hollow cylinder with connections or short tubes M and M' by means
of which the pneumatic hammer is connected to the tubes of the air pump. f is a
cylinder or piston closely fitted into the hollow cylinder C. The cylinder facts as

page_text: a hammer and is reciprocated by compressed air. g is a stamp carrying the
working tool connected to it at t by a bayonet joint. This stamp g has a square
guiding piece z¹ guided in v. w is an opening in the working cylinder C which
can be regulated by the ring X adjustable by the screw y and which tightly
surrounds the cylinder at this part. The ring X has a tube R which makes
connection with the orifice w of the cylinder C. is an orifice or perforation of
the partition so that the compressed air may pass from the chamber F of the
working cylinder C into the chamber E.
Figure 5 shows the same pneumatic hammer provided with mechanism for
producing a simultaneous intermittent rotary movement. 9 and g¹ are the divided
stamp provided at t with the working tool.
The stamp g in Figure 5 is formed of greater diameter at r than in Figure 4 in
order to receive part of the stamp g¹; it is provided at m with a crown ratchet
wheel n.
The stamp g¹ can slide and revolve in u; at p it is formed with spiral
grooves, on which can move up and down a corresponding piece K as in a twist
drill. The piece K also has a crown ratchet wheel s corresponding to the crown
ratchet wheel n, with which it engages continuously, because the piece K is
pressed against it by the spring N¹.
The machine is operated as follows:-
The wheel a² is set in motion and actuates by a rope b¹ and a disc a¹ the double
acting air pump, which has no valves, because the air in the pump, pneumatic
hammer and connecting tubes is not connected with the outside air, its motion
being only reciprocating. The air compressed on one side of the piston of the air
pump drives the hammer with great force against the stamp 9, which thus
receives a blow operating the tool h. Now commences the second stroke of the air
pump, the air compressed on the other side of the piston drives the hammer f back,
which strikes against the spring cushion N and the tool is forced back into its
former position by the tension of the spring N¹. During this action part of the
compressed air has escaped through the opening z w. and the pipe R into the open
air, thus weakening the rebound against the hand holding the hammer.
tube R is conveniently arranged so that the escaping air blows away any dust
that may be formed by the tool working on the article to be manufactured, which
is of great importance to the operator. The orifice w can be regulated by the
ring X and the hammer works without any governor. The hammer is now driven
against the stamp g again, and the operation is repeated.
The
If the tool is to receive a rotary motion simultaneously with the forward
movement, the arrangement is used as illustrated in Figure 5. The operation is
the same as in Figure 4, but during the forward movement of the stamp g the
grooved piece K is prevented from rotation by the connection between the ratchet
wheels n and s. In consequence the stamp g with the tool must make the twisting
movement prescribed by the spiral grooves. At the return of the hammer f the
spring N¹ forces the piece K and with it the stamp g into the former position.
However as the friction of the stamp in its guide and the action of the tool on
the article operated on prevent their backward movement, the piece K must
necessarily rotate around its axis, its backward movement being prevented by the
ratchet coupling n and s. The same operation is now repeated as before,
therefore the tool receives an intermittent rotary movement simultaneously with
the forward movement.
If it is intended to use only the hammer, it is only required to disconnect the
drill, which is rotated by the flexible axle c. On the other hand if only the drill
is to be used the pin of the disc a' is adjusted by the screw P., see Figure 6, so
that the radius of the pin d² on disc a' is reduced to zero, thus taking the air
pump and also the pneumatic hammer out of action.
Of course according to this invention the operator is able to work with both
tools, i.e. with the drill and the pneumatic tool, simultaneously as described.
As the pneumatic hammer as well as the air pump work without any governor,
their operation is even and continuous.

page_text: Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1st. A machine tool operated by compressed air for drilling and hammering,
having a double acting air pump moving a piston f to and fro in the cylinder of
the tool, and which operates a stamp or tool g as a hammer or as a drill, as
desired.
2nd. In the apparatus claimed in Claim 1 the combination of the air pump and
the tool in such a manner that two tubes S and S' attached to the stroke ends of
the piston supply the tool with compressed air and allow of the exit of the latter
respectively.
3rd. In the tool claimed in Claim 1 the division of the stamp 9 into two parts so
that by the application of a piece K, having spirally twisted grooves internally, on
the part of the stamp having corresponding spiral grooves, effects the rotation
of the tool simultaneously with its forward movement.
p
4th. In the apparatus claimed in Claim 1, for the purpose of weakening the
rebound at the ascent of the piston f, the arrangement of an adjustable orifice w
in the cylinder C by means of which part of the motive air may escape and be
utilised for the removal of the dust formed by the working of the tool.
5th. In the apparatus claimed in Claim 1 the arrangement of a tube coupling so
that one end of the flexible axle formed as a square piece engages in a corre-
sponding square recess of the axle a, resting in the frame, and connected to the
air pump in any convenient manner.
Dated this 9th day of November 1892.
FELL & WILDING,
Agents for the Application.