Rock drill

A rock drill comprises a shaft having a leading and a trailing end, a shank connected to the trailing end, and a drill head connected to the leading end of the shaft. Means for transporting drilling from the leading end toward the trailing end of the shaft are provided which include at least one channel extending parallel to the shaft from the drill head toward the shank. A shell coaxially surrounds the shaft and bounds the channel, which shell has an open front end adjacent the drill head, a closed rear end facing the shank and at least one transverse bore adjacent the rear end of the shaft and open at the outer surface of the shell.

BACKGROUND OF THE INVENTION 
The present invention relates to a rock drill. More particularly, it 
relates to such a rock drill which comprises a shaft, a shank connected to 
a trailing end of the shaft, a drill head connected to a leading end of 
the shaft and a channel for transporting drillings extending substantially 
parallel to the shaft from the drill head toward the shank. 
Rock drills of this type connected to a portable power unit such as a 
drilling machine or a hammer drill are already known in the art. Such 
drills are used for drilling large holes suitable for mounting wall 
switches therein, or for drilling large bores for extending pipes 
therethrough. 
Drillings generated during the drilling process soils the working place and 
the operator which is especially undesirable when such work is performed 
in furnished rooms. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide an 
improved rock drill which avoids the afore-mentioned disadvantages. 
More particularly, it is an object of the present invention to provide an 
improved rock drill, having an efficiency not less than that of 
conventional rock drills, and which at the same time transports the 
drillings generated during a process of drilling securely out from the 
working zone and without soiling the surroundings. 
With these objects in mind and with others which will become apparent 
hereafter, the rock drill, in accordance with the present invention, 
briefly stated, comprises a shell coaxially surrounding a shaft of the 
rock drill and having an open front end adjacent a drill head, a closed 
rear end adjacent a shank and at least one substantially transverse bore 
adjacent the rear end of the shell and open at the outer surface of the 
latter. 
The transverse bore is connected to a suitable suction device, and 
drillings generated during drilling are sucked out from the drill head. It 
is desirable that the transverse bore communicates with a pipe connected 
to a conduit of the suction device. In another embodiment of the invention 
the rock drill comprises a swivel member rotatably mounted on the shell 
and secured against an axial displacement relative thereto, which swivel 
is provided with the above-mentioned suction pipe communicating with a 
conduit of the suction device. In a further embodiment of the invention 
the rock drill is formed of separate members which are connected to each 
other by means of a connecting member engaging with and supporting the 
inner surface of the shell. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a rock drill configurated as a cross bit. The rock drill has a 
centering drill bit 3 connected to a leading end of a shaft 2 and a shank 
1 connected to a trailing end of the shaft 2. The shank 1 may be connected 
to a portable power unit by means, for example, a splined connection for 
transmitting torque thereto. Four radially projecting blades 4 enclosing 
with one another an angle of 90.degree. are provided at the leading end of 
the shaft 2 carrying the centering drill bit 3. Carbide-tipped elements 
having cutting edges 5, 6 are mounted on the front faces of the respective 
blades 4 by means of soldering. The cutting edges 6 on the outer portion 
of the blades 4 project radially outwardly beyond the outer surface of the 
blades 4. The cutting edges 5 are mounted on radially inner portion of the 
blades 4. In a cross bit of a small diameter the cutting edges 5 may be 
omitted. 
A shell 7 is provided which axially surrounds the shaft 2 and extends from 
the rear side of the blades 4 toward the shank 1. The shell 7 has a 
funnel-shaped part rearwardly of a front open end 8 of the shell, which 
part has, at the open end, a diameter equal to twice the radial dimension 
of each of the blades 4. At the same time the outer diameter of the 
funnel-shaped part of the shell 7 is smaller than the outer diameter of a 
drill head, that is than the maximum diametral dimension of the cutting 
edges. The shall 7 bounds a channel extending from the drill bit 3 towards 
the shank 1. 
Adjacent a closed rear end 9 of the shell 7 a transverse bore 10 is 
provided which is open at the outer surface of the shell 7. The transverse 
bore 10 communicates with a pipe 11 adapted for connection with a conduit 
of a suction device, not shown in the drawing. 
In this embodiment the shaft 2 is provided with an annular groove 13 and a 
ring-shaped flange 12 formed on the inner surface of the shell 7 adjacent 
the rear end of the latter and extends with small clearance into the 
groove 13 so as to enable the shaft 2 to be rotated relative to the shell 
7, while maintaining a fixed axial position of the shell 7 relative to the 
shaft 2. 
The core bit, in accordance with the present invention, can be connected to 
a portable power unit, for example, it can be mounted in a clamping device 
of a hammer drill. This can be performed by means of a splined connection 
of the shank 1 with a working head of the hammer drill. The section pipe 
11 is connected to a suction device by means of a conduit. During 
drilling, the centering drill bit 3 and the cutting blades 5 and 6 cut 
stone or other material to be drilled. Drillings generated during the 
process are sucked into the channel bounded within the shell 7. The 
drillings are sucked into a front portion of this channel formed within 
the funnel-shaped part of the shell 7, then move through a circular space 
formed between the inner surface of a cylindrical part of the shell 7 and 
the shaft 2, and thereafter are sucked out through the transverse bore 10 
into the suction device. 
For easy dismounting of the shell 7 from the shaft and replacing it by a 
new one in case of a breakage or wear of the shell, the latter is 
constituted of plastic material, such as polyamide, and the ring-shaped 
flange 12 of the shell 7 is received in the groove 13 of the shaft 2 so as 
to form a snap lock. 
FIG. 2 shows a second embodiment of the rock drill, in accordance with the 
present invention, which is also configurated as a cross bit. This cross 
bit differs from the construction of the first embodiment in that a shell 
27 is mounted on a shaft 22 for joint rotation therewith. The cross bit 
comprises a centering drill bit 23, blades 24 at the leading end of the 
shaft 22 and a shank 21 at the trailing end thereof, as clearly described 
in connection with the first embodiment of the invention. A front open end 
18 of the shell 27 is similarly funnel-shaped and located rearwardly 
adjacent the blades 24. A ring-shaped flange 32 provided on the inner 
surface of the shell 27 adjacent the rear end 29 thereof engages in an 
annular groove 33 of the shaft 22 so as to form a snap lock and to provide 
joint rotation of the shell 27 with the shaft 22. Two transverse bores 30 
located opposite to one another extend through the wall of the shell 27 
and are open at the outer surface thereof. A swivel member 34 is coaxially 
mounted on the shell 27 rotatably relative thereto. The swivel member 34 
is secured to the shell 27 by means of a further ring-shaped flange 36 
formed on the inner surface of the swivel member 34 and received in a 
further annular groove 35 provided on the outer surface of the shell 27 so 
as to prevent an axial displacement of the sivel member 34 relative to the 
shell 27. The swivel member has an annular recess 37 which communicates, 
on the one hand, with the bores 30 and, on the other hand, with a suction 
pipe 31 projecting laterally from the swivel member 34 and connectable to 
a suction device, not shown in the drawing. The suction pipe 31, similarly 
to that of the first embodiment of the invention, serves to transport 
drillings generated during the drilling operation from the drill head 
toward the shank through the channel bounded by the shell 27. 
The above described rock drill in accordance with the second embodiment of 
the invention shown in FIG. 2 differs from that of the first embodiment 
only in that the shell 27 rotates jointly with the shaft 22, and at the 
same time the shell 27 together with the shaft 22 rotate relative to the 
swivel member 34. 
FIG. 3 shows a rock drill in accordance with a third embodiment of the 
present invention, which rock drill is configurated as a cross bit having 
blades 44. The rock drill of this embodiment has a construction similar to 
the constructions of the previous embodiments, and differ only in that a 
front open end 48 of a shell 47 is not configurated as a funnel-shaped 
part. In this embodiment the shell 47 is also connected to a shaft for 
joint rotation therewith so that a swivel member 34 has to be used, as in 
the second embodiment of the invention. The shells 27 and 47 can be 
constituted of plastic material such as polyamide. The swivel member 34 
can be constituted of the same material as the shells 27 and 47. 
FIG. 4 shows a further embodiment of the present invention, where a rock 
drill is of a multi-partite construction, comprising a shank 51, at least 
two shaft parts 52 and a drill head 53, each constituted by a separate 
member. The shank 51 is connectable to a portable power unit by means, for 
example, a splined connection for transmitting torque. A front part of the 
shank 51 is provided with an internal bore 55 for receiving therein a rear 
end portion of the rear shaft part 52. Fastening means are provided on the 
inner surface of the internal bore 55 of the shank 51 and on the outer 
surface of the rear end portion of the rear shaft part 52 for transmitting 
torque and axial impact therebetween, which means can be constituted by 
threads on the respective surfaces and can include additional means such 
as rivets. It is understood that other fastening means also can be 
provided. 
The other end portion of the rear shaft part 52 spaced from the shank 51 is 
received in a bore 57 of a nut-shaped connecting member 56 having a 
cylindrical outer surface. The rear end portion of the front shaft part 52 
is received in the bore 57 of the connecting member 56 from the other end 
of the latter. The front end portion of the rear shaft part and the rear 
end portion of the front shaft part are received in the connecting member 
56 so as to be coaxial relative one another. The outer surfaces of the 
above mentioned portions of the shaft parts 52 and the inner surface of 
the connecting member 56 are provided with fastening means similar to that 
provided on the rear end of the rear shaft part and the shank 51, which 
fastening means are adapted to transmit torque and axial impact between 
the parts of the shaft. A front end portion 69 of the front shaft part 52 
spaced from the connecting member 56 is received in an axial internal bore 
58 of the drill head 53. Further fastening means similar to the above 
mentioned fastening means are provided on the respective surfaces of the 
front end portion of the front shaft part and the bore 58 to transmit 
torque and axial impact from the front shaft part and the drill head 53. 
The drill head 53 has at least two cutting edges 59. A duct 60 transporting 
drillings from the drill head 53 is provided which extends between the 
cutting edges substantially parallel to the axis of the shaft 52. 
A shell 61 coaxially surrounds the shaft 52 of the rock drill and has a 
diameter corresponding to the diameter of the drill head 53. The front end 
portion 69 of the shell 61 tightly surrounds a reduced diameter portion of 
the drill head 53. The inner diameter of the shell 61 corresponds to the 
outer diameter of the connecting member 56 so that the connecting member 
56 is engaged with and supports the inner surface of the shell 61. At 
least one duct 68 is provided on the outer surface of the connecting 
member 56 for providing communication between recesses formed between the 
inner surface of the shell and outer surface of the respective shaft parts 
52 to opposite sides of the connecting member 56. This duct 68 is formed 
as a longitudinal groove extending substantially parallel to the axis of 
the connecting member 56. 
The shell 61 is connected to the shaft 52 for joint rotation therewith by 
means for a ring-shaped flange 63 provided on the inner surface of the 
shell 61 adjacent the rear end 70 thereof, which flange engages the outer 
surface of a front part 54 of the shank 51 and clamps the latter with a 
snap lock. The above-mentioned snap lock is constituted by an O-ring 62 
engaging the front part 54 of the shank 51 and an annular notch formed in 
the ring-shaped flange 63 of the shell 61 housing the O-ring. Two 
transverse bores 64 located opposite one another extend through the wall 
of the shell 61 adjacent the rear end thereof and are open at the outer 
surface of the shell 61. A swivel member 65 is coaxially mounted on the 
shell 61 rotatably relative to the latter. The swivel member 65 is secured 
to the shell so as to prevent an axial displacement relative to the latter 
by means of a snap lock similar to that shown in FIGS. 2 and 3. This snap 
lock also comprises an O-ring 66 at an inner part engaged in a notch 
provided on the outer surface of the shell 61 and at an outer part engaged 
in an annular groove formed in the inner surface of the swivel member 65. 
The mode of operation of the rock drill of this embodiment is similar to 
that shown in FIG. 3. Drillings generated during the drilling operation 
are successively sucked from the cutting edges 59 through the duct 60 in 
the drill head 53, through the annular recess between the outer surface of 
the front shaft part 52 and the inner surface of the shell 61, through the 
duct 68 on the outer surface of the connecting member 56, through the 
annular recess between the outer surface of the rear shaft part 52 and the 
inner surface of the shell 61, and then through the transverse bores 64 
and the suction pipe 31 into a suction device, not shown in the drawing. 
The annular recesses between the inner surface of the shell 61 and the 
outer surfaces of the shaft parts 52 are dimensioned so as to provide a 
minimum necessary speed of flowing air assuring transportation of the 
drillings. This speed is of about 3 meters per second. 
A further embodiment of the invention is shown in FIG. 5. In this 
embodiment a rock drill is again multi-partite. A shaft part 52' has a 
length larger than each part of the shaft 52 shown in FIG. 4 and is 
connected to a shank 51. A connecting member 56 is located in this 
embodiment adjacent to a drill head 73 of the cross bit. The drill head 73 
is identical to the drill head shown in FIG. 3. The rock drill in 
accordance with this embodiment does not differ from that shown in FIG. 4 
in function, mode of operation, and manner of transporting of drillings. 
FIG. 6 shows a rock drill substantially corresponding to the rock drill 
shown in FIG. 4. It comprises a shank 51, two shaft parts 52 connected to 
one another by a connecting member 56, and a drill head 53, each 
constituted by a separate member. 
A shell 81 is rotatably mounted on the rock drill and is prevented against 
an axial displacement by means of a snap lock. A ring-shaped flange 82 is 
formed on the inner surface of the shell 61 and engaged with the outer 
surface of a front part 54 of the shank 51. The snap lock for preventing 
the axial displacement of the shell comprises an O-ring 73 engaged with 
and housed in a notch provided on the outer surface of the front part 54 
of the shank 51, and engaged with play in a groove provided in a 
ring-shaped flange 82. 
A front portion 84 of the shell 81 in this embodiment, in contradistinction 
to the construction of the previous embodiments, is constituted of a 
wear-resistant material, for example, hardened steel. The front portion 84 
of the shell 81 has a rear section 85 and the rear portion thereof of 
plastic material, a front section 85, respectively, of a reduced thickness 
(FIGS. 7 and 8). In this embodiment the thickness of each of the sections 
is equal to half of the thickness of the shell portions. The sections 85 
overlap one another. To improve a connection between the front metallic 
portion 84 of the shell and the rear portion thereof of plastic material, 
the outer surface of the section of the front portion 84 can be provided 
with longitudinal grooves extending parallel to the generatrix of this 
portion. It is understood that another means also can be provided to 
improve the mechanical connection of the above mentioned portions. The 
rear portion of the shell can be connected to the front portion 84 by 
using, for example, a process of extrusion so that the rear portion is 
extruded and molded onto the front portion of the shell. 
The rock drill shown in FIG. 6 does not differ in a mode of operation from 
that shown in FIG. 1. The shell with the wear-resistant front portion has 
a longer life-time that a shell consisting of plastic material. It is 
understood that the shell with such front portion can also be used in the 
rock drills which have the funnel-shaped front part as shown in FIGS. 1 
and 2. 
The rock drill in accordance with the present invention provides for highly 
advantageous results. The rock drill carries out drilling of rock with a 
high efficiency and, at the same time, transports drillings generated 
during the process of drilling out from the working zone without 
contamination of the surrounds and soiling of the operator. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.