U.S. patent number 3,865,200 [Application Number 05/307,573] was granted by the patent office on 1975-02-11 for burrowing apparatus.
This patent grant is currently assigned to Tracto-Technik Paul Schmidt. Invention is credited to Paul Schmidt.
United States Patent |
3,865,200 |
Schmidt |
February 11, 1975 |
BURROWING APPARATUS
Abstract
A pneumatic burrowing apparatus comprising a tubular housing
with a percussion tip mounted at the leading end of said housing
and including a rearwardly directed portion extending interiorly of
said housing, said tip being arranged for axial movement relative
to said housing. A percussion piston is mounted for reciprocal
motion within the housing and arranged to strike said percussion
tip to impart a forwardly directed force thereto. Spring means
mounted between the percussion tip and the housing are arranged to
be compressed therebetween when the tip is driven forwardly by said
percussion piston. A displacement cone mounted proximate the
leading end of the housing moves forwardly with the housing during
a burrowing operation but is loosely slidable relative to said
housing when the housing is withdrawn from a burrowed opening.
Inventors: |
Schmidt; Paul (Saalhausen,
DT) |
Assignee: |
Tracto-Technik Paul Schmidt
(Saalhausen, DT)
|
Family
ID: |
5825481 |
Appl.
No.: |
05/307,573 |
Filed: |
November 17, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Nov 18, 1971 [DT] |
|
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2157259 |
|
Current U.S.
Class: |
175/19; 173/133;
173/99 |
Current CPC
Class: |
E21B
7/26 (20130101); E21B 4/145 (20130101) |
Current International
Class: |
E21B
7/26 (20060101); E21B 7/00 (20060101); E21B
4/14 (20060101); E21B 4/00 (20060101); E21b
011/02 () |
Field of
Search: |
;175/19,73,94,92
;173/20,91,181,133,139 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Purser; Ernest R.
Assistant Examiner: Favreau; Richard E.
Attorney, Agent or Firm: Toren, McGeady and Stanger
Claims
What is claimed:
1. Pneumatic burrowing apparatus particularly suitable for earth
drilling comprising a tubular housing including a leading end
adapted to act as the anterior of said apparatus during a burrowing
operation, a percussion tip mounted in said housing at said leading
end and including a rearwardly directed portion extending
interiorly of said housing, said tip being arranged for axial
movement relative to said housing, a percussion piston mounted for
reciprocating motion within said housing and arranged to strike
said percussion tip to impart a forwardly directed force thereto,
pneumatic means including an energy source for imparting a striking
force to said piston, spring means mounted between said percussion
tip and said housing and arranged to be compressed therebetween
upon relative movement of said tip forwardly of said housing, and a
displacement cone mounted proximate said leading end for forward
movement with said housing during a burrowing operation, said
displacement cone being loosely slidable relative to said housing
in a direction forwardly thereof.
2. Apparatus according to claim 1 including an adjustable stop
member axially displaceable relative to said housing engaging said
spring means for enabling adjustment of the spring force
thereof.
3. Apparatus according to claim 1 including stop means engaging
said percussion tip to limit movement of said tip relative to said
housing.
4. Apparatus according to claim 1 wherein said displacement cone is
mounted upon said percussion tip.
5. Apparatus according to claim 1 wherein said displacement cone is
mounted upon a portion of said housing proximate said leading
end.
6. Apparatus according to claim 1 including profile grooves
arranged upon the outer surface of said tubular housing and
extending transversely to the longitudinal direction of said
housing.
7. Apparatus according to claim 1 including a protective tube
attached to the rear end of said housing taken relative to the
working direction of said percussion tip.
8. Apparatus according to claim 1 including a guide body attachable
alongside of said tubular housing and extending generally parallel
thereto.
9. Apparatus according to claim 1 including steering wings
adjustably attachable to the exterior of said housing.
10. Apparatus according to claim 1 including a curved stiff
protective tube attachable to said housing.
11. Apparatus according to claim 1 including an intermediate piston
arranged in the line of action between said percussion piston and
said percussion tip and being displaceable in the direction of
movement thereof.
12. Apparatus according to claim 11 wherein said intermediate
piston is resiliently mounted within said housing.
13. Apparatus according to claim 1 wherein said percussion tip is
formed as a hollow chisel.
14. Apparatus according to claim 13 wherein said percussion tip is
arched inwardly in the form of a spherical cap at the respective
end face thereof extending toward the leading end of said apparatus
in the working direction thereof.
15. Apparatus according to claim 13 wherein said percussion tip
chisel comprises a circular cross sectional configuration, wherein
said displacement cone is mounted upon said chisel and is arranged
at a distance from said chisel tip which is a multiple of the
diametral dimension of said chisel.
16. Apparatus according to claim 1 including a control sleeve
mounted within said housing and having an internal bore designed as
a compressed air inlet and being provided at its circumference with
at least one air channel, said percussion piston being hollow at a
rear end thereof taken in the working direction of said piston,
said piston sliding by its hollow rear end in the space between
said control sleeve and the inner wall of said housing and
simultaneously forming a seal on said control sleeve and on the
inner wall of said housing, there being provided in the hollow rear
end of said percussion piston an opening which extends over at
least one channel to the front end face of said percussion piston
taken in the working direction thereof, said channel corresponding
during the working stroke of said percussion piston with the
channel in said control sleeve alone and during the return stroke
of said combustion piston with the internal bore of said control
sleeve alone.
17. Apparatus according to claim 16 wherein said control sleeve is
displaceably arranged within said housing, with the displacement
path of said control sleeve being limited by stop means, with a
force exerted on said housing by said percussion piston in the
working direction thereof being greater in one fixed position and
smaller in another fixed position than the force exerted on said
housing in the opposite direction.
18. Apparatus according to claim 1 including a mounting assembly
adapted to have said burrowing apparatus mounted therein for
guiding said apparatus during a burrowing operation.
19. Apparatus according to claim 18 wherein said mounting device is
provided with a return barrier consisting of two jaws held in a
pair of spring loaded parallel links which are at the areas of
contact with said housing in a vertical position of said parallel
links arranged at a distance from each other which is greater than
the outside diameter of said housing.
20. Apparatus according to claim 18 wherein said mounting device
includes a bubble level enabling positioning of said mount at a
desired location.
21. Apparatus according to claim 18 wherein said mounting device
includes an aiming frame with a plumb line device enabling
positioning of said mount.
22. Apparatus according to claim 18 wherein said mounting device
includes sighting means enabling desired orientation of said
mount.
23. Apparatus according to claim 18 wherein said mounting device
includes a bottom plate and a cardan joint interconnecting said
mounting device with said bottom plate, said mounting device being
adjustably positionable relative to said bottom plate to enable
fixation thereof in the earth.
Description
The invention concerns a self-driven, pneumatic burrowing device,
in particular for ground drilling, having a percussion tip and a
percussion piston reciprocating in the housing. Such devices are
also known under the designation ground rocket, percussion hammer
or percussion drill and serve primarily to install supply lines,
such as water pipes, electric or telephone lines under streets or
sidewalks without requiring that the pavements or the sidewalks be
broken open.
In known devices, the housing of the burrowing apparatus is
subjected to very high loads, so that its life is normally at most
500 hours of operation. Moreover, the diameter of such devices is
135 mm and more, although in the practice 50 mm are usually
sufficient as diameter for the bores. The large housing diameter
entails high friction, which greatly reduces the advance of the
device. Furthermore, there is greater danger of damage to the
street pavement due to cross ripples, because the subsoil under
streets, already compacted to a large extent, is also displaced
upward against the pavement by the advance of the drill, so that
the pavement rises slightly.
Other disadvantages of conventional driving drills reside in the
high consumption of compressed air due to the large pressure
surfaces, the danger of deviation from the desired drilling
direction because of the large housing diameter, as well as the
high production costs resulting from the fact that the interior of
the housing is worked out of the solid material.
It is, therefore, the object of the invention to provide a
burrowing apparatus which is free from the aforementioned
disadvantages and in particular one which has a longer life than
the conventional drills.
According to the invention, this is achieved in that the percussion
tip is arranged in the housing of the driving drill and is
displaceable in the axial direction thereof being supported on the
housing in the working direction via a spring member. As a result
not only is much less percussion energy required than in comparable
conventional driving drills, but also the load on the housing is
greatly reduced. This is attributed to the unique movement
conditions effected in the driving drill according to the
invention. Due to the displaceable arrangement and the elastic
support of the percussion tip, the speed with which the percussion
tip is moved after the impingement of the percussion piston is much
greater, and that of the housing much smaller, than in conventional
driving drills. Due to the improved advance, a smaller piston
surface can be selected for admission with compressed air, and the
housing diameter can be reduced considerably. The result of this
is, besides a great reduction of the frictional resistance in the
soil, an appreciable reduction of the production costs.
The present invention will be better understood by reference to the
following detailed description of the preferred embodiments
thereof, taken in connection with the accompanying drawing, in
which:
FIG. 1 shows a longitudinal section through a driving drill
according to the invention;
FIG. 2, is a detailed sectional view of another driving drill
according to the invention;
FIGS. 3 to 6, are longitudinal sectional views showing equivalent
details of a third driving drill according to the invention, in
different operative positions, with a control device;
FIG. 7, is a perspective view of a mount for introducing the
driving drills according to FIGS. 1-6 into the soil;
FIG. 8, is a sectional view of a driving drill according to the
invention for opening up or widening an existing earth bore;
FIG. 9, shows a side elevation an aiming frame for aligning the
driving drills;
FIG. 10, is a schematic view showing a driving drill according to
the invention in tandem arrangement; and
FIGS. 11 and 12, are partial views showing in detail steering
devices for a driving drill according to the invention.
According to FIG. 1, the housing 1 of a driving drill according to
the invention consists of a honed commercial hydraulic tube,
chromed for protection against corrosion and to reduce wear, having
an outside diameter of between 65-95 mm, and provided at both ends
with an internal thread. A bushing 2 is screwed into one end of
housing 1. In the center the bushing 2 has a collar 3 of the same
diameter as housing 1, with the collar 3 being provided with bores
4 to enable engagement by a hook wrench for turning of the bushing
2. The bushing 2 includes external threads located axially
rearwardly of the collar 3 configured to engage the internal thread
of housing 1.
A threaded porof bushing 2 located axially forwardly of the collar
3 is configured to engage a housing front portion 5, which has the
same diameter as the collar of bushing 2 and as the housing 1. On
its side opposite the bushing 2, the portion 5 embraces by a collar
6 a pin 7 of a conical percussion tip 8, which again has the same
outside diameter as collar 3 of bushing 2 and as the housing 1 and
which embraces the housing portion 5 at an offset 9 with a collet
10.
Onto the free end of pin 7 a collar 11 is attached, for example, by
screw threads or the like, which guides the percussion tip 8 in the
housing front portion 5 and which has bores 12 extending axially
rearwardly thereof to enable engagement by a socket wrench. Between
collar 6 of the housing front portion 5 and collar 11 of the pin 7,
there is provided a compression spring 13 held in tension about the
pin 7 by the collar 11. The adjustable initial tension of spring 13
assures that in the starting position shown the percussion tip 8
bears with its housing-side end face against collar 6 of the
housing front portion 5. Direct contact is prevented, however, by
an elastic disk 14 arranged between the percussion tip 8 and the
housing front portion. All screwed parts are secured against
detachment by locking plates.
In operation, by way of an intermediate piston 15 which in the
starting position shown bears against pin 7 of the percussion tip
8, a pneumatically moved percussion piston 16 is caused to strike
against pin 7 of percussion tip 8, so that the percussion tip
lunges forward from the housing front portion 5 into the soil. The
intermediate piston 15 contributes to the crushing, for example of
stones which cannot be pushed aside, by the vibrating percussion
tip preceeding the housing, and for this purpose it is arranged in
bushing 2 for displacement in axial direction and is supported in
bushing 2 by a collar 17 on elastic buffers 18 arranged in the
axial direction before and behind the collar. As the percussion tip
8 lunges forward, the housing 1 follows this movement under the
pressure of spring 13 and of the elastic buffers 18. The buffers 18
are held in the bushing 2 by another collar 19 of bushing 2 and by
a disk 20 secured in bushing 2 by a spring ring 30. The
intermediate piston 15 forms a sub-assembly with bushing 2 and the
elastic buffers 18, as does also the housing tip 5 with the
percussion tip 8, collar 11 and plate springs 13. In operation, the
condition of the spring member formed by the springs 13 is such
that the amount of its compression, in what in the operating
direction is the frontmost position of the percussion tip in the
housing, is equal to or smaller than the maximum permissible
amount.
The percussion piston 16 is guided in housing 1 by means of two
guide rings 32, 33 arranged at an axial distance from each other on
its shell 31 and is provided with slide rings 34 at the guide rings
32 and 33 to reduce the friction at housing 1. The guiding of the
percussion piston 16 with the rings 32 and 33 insures sufficient
freedom of movement for the percussion piston 16 even if housing 1
is twisted to a relatively high degree. Besides, the percussion
piston 16 slides with its bored rear end, viewed in the direction
of the percussion tip, sealing engaged on a control bushing 35,
which is held with a collar 36 in an offset of the internal bore of
the housing by a sleeve 37 screwed into the respective housing end
and having a slightly larger diameter, in the portion protruding
from housing 1, than the housing 1.
At the end away from the percussion piston 16, the control sleeve
35 has a connecting piece 33 designed as a flexible tube for
connection to a compressed air line of a compressor (not shown).
The compressed air coming from the compressor passes, in the
operative state, through an internal bore 39 of the control sleeve
35 into the bored end of the percussion piston 16, so that the
percussion piston is accelerated in the direction of the percussion
tip 8. Owing to this, the percussion piston 16 moves in the housing
1 against the intermediate piston 15. The air present in housing 1
before the percussion piston 16--in the direction of
movement--escapes along the generated surface of the percussion
piston. For this purpose, the percussion piston 16 is provided
between the guide rings 33 and 32 at the shell 31 with an external
recess which at the front guide ring 33--in the direction of
movement--is connected via an axial groove 40 with the housing
cavity present between percussion piston 16 and intermediate piston
15 and via a bore 41 in shell 31 with a recess 42 at the outer
circumference of the control sleeve 35 extending as an external
opening. However, the connection with recess 42 in control sleeve
35 is interrupted by a suitable limitation of recess 42 or
respectively a suitable arrangement of bore 41 in shell 31 of the
percussion piston 16 approximately after one half of the distance
traveled up to the intermediate piston, and the housing cavity
lying before the percussion piston 16--in the direction of
movement--is closed. Consequently, if the pressure of the
compressed air supplied by the compressor continues to act at the
bored end, there builds up in the housing cavity before the
percussion piston 16 an air pressure which accelerates the
percussion piston 16 in the opposite direction after impingement on
the intermediate piston 15 and after transfer of the kinetic energy
causing the advance of the percussion tip 8 and of the housing 1 to
the intermediate piston 15. Simultaneously with the impingement of
the percussion piston 16 on the intermediate piston 15, if the
length of the control sleeve 35 is adequate, there results via the
bore 41 in shell 31 of the percussion piston 16 a connection of the
housing cavity lying between percussion piston 16 and intermediate
piston 15 with the internal bore 39 of the control sleeve 35, and
in addition to the admission in the bored end the percussion piston
is pressurized at the other end with the compressed air coming from
the compressor. As the area at the other end--which in the working
direction of the percussion tip 8 is the front end--is greater than
the pressurized area at the rear end, the percussion piston 16
returns to its starting position under the differential pressure of
both areas. Before it reaches its starting position, in which the
percussion piston 16 bears against collar 36 on the control sleeve
35, there results again a connection of the housing cavity lying
between the percussion piston 16 and the intermediate piston 15
with the recess 42 of the control sleeve 35 extending externally,
so that the air pressure in this housing cavity decreases and the
percussion piston 16 is decelerated by the pressure of the
compressed air coming from the compressor now acting only in the
bored percussion piston end. After reaching its starting position,
the percussion piston 16 is again propelled forward without
interruption for a new strike against the intermediate piston 15 at
continued pressurization in the bored end and admission of air to
the housing cavity lying before the other end.
The admission of air to the housing cavity via recess 39 in the
control sleeve 35 occurs due to the fact that axially extending
bores 43 are present in collar 36 of control sleeve 35 and housing
1 is open at what in the direction of the percussion tip 8 is the
rear end, into which the bores 43 open, or respectively that it is
provided with a protective tube 44 of plastic through which air can
escape from housing 1 also when housing 1 is completely embedded in
the soil, and which protectively embraces the compressed air line
38 leading to housing 1. The protective tube 44 is fastened to the
housing 1 by a cutting ring screw connection. Specifically the
cutting ring screw connection is composed of: a ring 45 which is
located within the protective tube 44; a ring 46 which extends
externally about the protective tube 44, is press-fitted with
protective tube 44 into the internal bore of sleeve 37, and in so
doing becomes clamped between sleeve 37 and in the outer side of
protective tube 44; and a cap nut 47 screwed onto sleeve 37, to
press the ring 46 with the protective tube 44 into sleeve 37.
Alternatively, a simple clamping ring may be provided instead of
the ring 46, i.e., the protective tube 44 may be drawn into sleeve
37 while being clamped between the ring 45 and the similarly
clamping ring which may be additionally slit in the axial
direction.
In the embodiment of the invention according to FIG. 2, the housing
front portion 61 is screwed directly into the housing 60 and
comprises a percussion tip 62 in the form of a round chisel, which
at the front end--taken in the working direction--is designed as a
hollow chisel by an inward arch equal to the arch of a spherical
surface. Integrally formed at the other end of the tip 62 is a
piston 66 and a pin 63. Pin 63 forms the strike surface for the
respective percussion piston and is present, in the starting
position shown, in the internal bore of a ring 64 which is
attached, for example by screw threads or the like, with the
housing front portion 61 into the housing 60. Ring 64 limits the
movement of piston 66 against the working direction of the
percussion tip 62. The movement in the working direction, during
which the percussion tip 62 is guided on the one hand directly in
the housing front portion 61 and on the other hand with piston 66
in the housing front portion 61, is limited by an offset 65 of the
piston bore formed in the housing front portion 61 within which
piston 66 is slidably movable. During this movement, the percussion
tip 62 is supported on the housing front portion 61 by way of
piston 66 and plate spring 67, which move the percussion tip 62
back into its starting position from its--in working direction in
the housing front portion 61--frontmost position after each
percussion.
While in the example according to FIG. 1 the intermediate piston 15
with its elastic suspension insures that the percussion tip 8 does
not execute a movement inadmissible for the plate spring 13 despite
a mass which is small in relation to the mass of the percussion
piston 16, i.e. while in FIG. 1 the intermediate piston 15 prevents
an inadmissible compression of the compression spring 13, an
inadmissible compression of the plate spring 67 according to FIG. 2
is prevented by the offset 65.
Upon impingement of the percussion piston on pin 63 of the
percussion tip 62, the latter, like the percussion tip 8 of FIG. 1,
is driven forward out of the housing front portion 61, and via the
plate spring 67 in the working direction of the percussion tip 62 a
pressure is exerted on the housing front portion 61 and on the
housing 60. At sufficient spring force of plate spring 67 this
pressure is so strong that the housing 60 with its housing front
portion 61 follows the percussion tip 62, just as under the
pressure of plate spring 13 and of the elastic buffer 18 the
housing 1 follows the percussion tip 8. Otherwise the friction in
the soil, opposing a movement of the housing, and the housing
movement possibly resulting from a previous return of the
percussion piston to its starting position counter to the working
direction of the percussion tip 62 will be overcome only with the
impingement of the piston 66 on the offset 65 of the housing front
portion. In any case, and in the same manner as the device of FIG.
1, a leading of percussion tip 62 relative to housing front portion
61 and to housing 60 in the form of a vibratory movement results,
which improves the advance over conventional driving drills.
Furthermore, the advance according to FIG. 2 is further increased
by a ring 68 placed on the housing front portion 61, whose diameter
is larger than housing 60 and housing front portion 61. Ring 68
tapers in adaptation to the housing front portion 61 in the working
direction of the percussion tip 62 and pushes the soil aside so
that a bore is formed in the soil whose diameter is greater than
the housing diameter, and that the friction of housing 60 with the
soil is considerably reduced.
In order that ring 68 will not hinder a backward movement of
housing 60, the seat of ring 68 on the housing front portion 61 is
selected so that it detaches from the housing front portion 61
when, for example in the case of a bore hole extending in an
undesired manner, the driving drill is to be positioned anew and
the housing is, for this purpose, moved backward out of the soil by
reversal of the respective percussion piston.
Further improvement of the advance is brought about by profile
grooves which, extending crosswise to the longitudinal direction of
the housing, largely prevent retraction of the housing 60 during
the return stroke of the percussion in piston. In this connection,
a sawtooth profile, such as that shown in FIG. 2 on the outer
surface of housing 60 with teeth pointing backward in relation to
the percussion tip, has proved particularly advantageous.
The reversal of the percussion piston for a backward movement
occurs, according to FIGS. 3 to 6, in another driving drill
according to the invention, by means of a cable line 69. Through
the cable line 69 a sleeve 143 is moved.
The sleeve 143 cooperates with a control sleeve 135, a spring 136,
and a ring 137. The control sleeve 135 is designed as a tube which
is mounted for sliding movement in the ring 137, fastened in the
housing and provided with passage openings 101 for the air escaping
from the housing. Ring 137 has a sleeve type prolongation 138, in
which are present, at two different points, on a circular
circumference, a number of radial bores for balls 139. In the
operative position of the control sleeve 135 for backward running,
shown in FIGS. 5 and 6, the balls 139 engage in two annular grooves
140 and 141 of the control sleeve 135. In the operative position
for forward running shown in FIGS. 3 and 4, the balls engage in
groove 141 and another annular groove 142 of the control sleeve. By
the engagement of the balls 139 the control sleeve 135 is fixed in
the respective operative position.
The result of the change of the control sleeve 135 from the
operative position Forward Running to the operative position
Backward Running is that the period during which the space--in the
direction of the percussion tip--before the percussion piston is
pressurized is substantially shortened, at constant time for a
cycle of the percussion piston, whereas the period during which a
pressure difference from bilateral admission with compressed air
counter to the direction of the percussion tip acts on the
percussion piston is lengthened accordingly. Thereby the movement
of the percussion piston against the percussion tip is decelerated
at an early time and possibly an impingement of the percussion
piston on the percussion tip is prevented altogether and the
movement of the percussion piston in the opposite direction is
decelerated much less, so that the percussion piston impinges
against ring 137 and imparts a backward movement to the
housing.
The balls 139 are held in the fixed position by the spring-loaded
sleeve 143 which slides in the housing of the driving drill. On
actuating the cable line 69 to switch from backward running to
forward running, sleeve 143 slides from the shown starting position
with recesses 144 over the balls 139, which release the balls 139
to the extent that they can just slide out of the annular grooves
140 and 141 when the compressed air supply is interrupted and
spring 136 pushes the control sleeve into the operative position
for forward running. In the operative position for forward running,
the fixing of the control sleeve 135 now occurs automatically after
release of sleeve 143 by the return thereof into the starting
position, in that sleeve 143 now pushes the balls 139 into the
grooves 141 and 142 of the control sleeve 135. The switching of the
driving drill from forward running to backward running requires
another actuation of the cable line. Then, at suitable design of
the spring 136 and with continued supply of compressed air, the
control sleeve 135 moves back into the starting position shown in
FIG. 6 under the compressed air pressure counter to the spring
force.
A protective tube (not shown) may be selectively screwed to the
housing end of the driving drill, the screw connection taking place
on the sleeve with which ring 135 is clamped in the housing and
which is provided with several grooves extending in axial direction
and interrupting the screw thread for the protective tube. The
grooves give the sleeve the effect of a screw tap, that is, by the
grooves the protective tube can be screwed onto the sleeve without
prepared thread and the sleeve cuts into the protective tube with
its screw thread. Also a so-called wire grip can be used for the
attachment of the protective tube. The protective tube can moreover
be provided with openings and be used for drainage if it remains in
the soil.
Besides there is shown in FIGS. 3 to 5 a percussion tip 109 which,
though being designed as a hollow chisel like the percussion tips
according to FIG. 2 and being mounted displaceably and elastically
in the housing, has a displacement cone 110 with a collet 111
which, like the collet of percussion tip 8 according to FIG. 1,
cooperates with the housing tip. The displacement cone 110 is
mounted on a conical intermediate piece of the percussion tip 109,
and as the cone tapers in the working direction of the percussion
tip 109, it is thereby firmly connected in the working direction
with the percussion tip without additional aids, while being easily
releasable counter to the working direction.
In FIG. 7, a mount 75 is shown, with which the driving drill
according to the invention is introduced into the soil at the
beginning of each drilling operation and brought into the starting
position required for a desired earth drilling. The mount 75 has
two jaws 76 and 77 adapted to the contour of the housing, which
receive the housing of the driving drill between them and give the
housing a position parallel to the longitudinal axis of the mount.
The jaws 76 and 77 are fastened to the mount 75 for pivotal
movement by means of parallel links 78 and 79, and at the area of
contact with the housing they have a greater distance from the
housing diameter when the parallel links 78 and 79 are in the
vertical position or at right angles to the longitudinal axis of
the mount. Due to the geometry of the parallel links 78 and 79, at
each movement of the parallel links 78 and 79 out of their vertical
position the jaws 76 and 77 move toward each other, i.e. they
close. Conversely the jaws 76 and 77 open when their parallel links
78 and 79 are moved from an inclined position into the vertical.
Due to an extension spring 80 articulated to one parallel link 79,
the jaws 76 and 77 always strive to close. This tendency is
countered when inserting the housing of a driving drill with a
parallel link 79 prolonged in the form of a lever, i.e. the
pivoting of the parallel links 78 and 79 by hand counter to the
force of the extension spring 80, required for insertion of a
housing, is facilitated by a prolongation of the parallel link 79
and pivoting of this parallel link 79. After insertion of the
housing and release of the parallel link 79, the jaws 76 and 77
close around the housing automatically. At the same time, and with
a suitable arrangement of the extension spring 80 or insertion of
the housing, the jaws 76 and 77 and the parallel links 78 and 79
move oppositely to the working direction of the percussion tip
belonging to the housing. After the driving drill has been set in
operation, that is, after pressurization with compressed air, the
percussion piston moves back and forth in the housing forces and
forces equal in sum act on the housing in each axial direction of
the housing. As a result of the clamping of the housing between the
jaws 76 and 77 and their pivotal arrangement, the force acting on
the housing in the working direction of the percussion tip leads,
with adequate design of the extension spring 80, to a pivotal
movement of the jaws 76 and 77 counter to the force of the
extension spring 80. The jaws 76 and 77 then open, and the housing
slides through between them by its residual energy. The force
acting on the housing in the other axial direction, that is, in the
pulling direction of the extension spring 80, leads instead to an
intensified clamping between the jaws, which prevents movement. In
this respect the jaws 76 and 77 form with the parallel links 78 and
79 a return barrier which, after sufficient anchoring of the mount
75 in the ground, insures that the driving drill penetrates into
the soil.
For anchoring in the ground, the mount 75 is connected with a
bottom plate 88, which is anchored in the soil with bottom nails 81
before alignment of the mount 75. For its alignment the mount 75 is
pivoted about a horizontal and a vertical axis. For this purpose
mount 75 is connected with the bottom plate 88 via a cardan joint
formed by a turntable 89 arranged for rotary movement on the bottom
plate 88 and a pivotable suspension of mount 75 in lugs 90 of
turntable 89. After aligning, i.e. after pivoting about the
vertical axis, turntable 89 can easily be fixed in its pivoted
position with an adjusting screw 91. The same applies to the
pivoting of the mount 75 in the lugs 90, i.e. to the pivoting of
mount 75 about the horizontal axis. In this case the fixing is done
with screws 92 designed as thumb screws, which also permit an
extremely accurate pivoting about the horizontal axis. According to
FIG. 7, when fixing mount 75 with the thumb screws 92, two thumb
screws 92 arranged on both sides of the horizontal pivot axis
cooperate, bracing mount 75 against the bottom plate 88.
The aligning itself is facilitated by a bubble level, a type of
water level, and by a sight 82. The sight 82 includes a rod 83 at
eye level which is inserted into the mount 75 perpendicular to the
longitudinal axis thereof and carries at the upper end, on a cross
beam 84, a rear sight 85 and a front sight 86 with sighting line
parallel to the longitudinal axis of the mount for sighting a
reference point.
Besides, the housing of the driving drill rests in mount 75 in the
jaws 76 and 77 and on a shell type support 87 arranged at a
distance from the jaws 76 and 77. The support 87 not only improves
the parallel position of the housing between the jaws 76 and 77, as
it reduces the bending load of the jaws 76 to a negligibly small
amount, but it also facilitates the insertion of the housing
between the jaws 76 and 77 and the provision of a protective tube
embracing the compressed air line to the housing and possibly the
cable line.
FIG. 8 shows a driving drill according to FIGS. 3 to 5 converted
for the boring open (widening) of an existing earth bore. According
to FIG. 8, instead of the displacement cone 110 a displacement cone
120 is arranged on the percussion tip 109 and the housing of the
driving drill is surrounded with an additional shell 121. At its
tip the displacement cone 120 has a cylindrical piece of the same
or a slightly smaller diameter than the existing earth bore. The
outside diameter of the displacement cone 120 equals that of the
shell 121 and determines the diameter of the earth bore during the
widening thereof.
Also for the widening of an existing earth bore exact aligning of
the driving drill is important. There are, however, difficulties in
the use of a bubble level when the driving drill must be brought
into a certain inclination. Such an inclination can easily be
adjusted with an aiming frame 122 shown in FIG. 9. In addition to a
sighting device consisting for example again of a front sight and
rear sight, for the sighting of a certain target, the direction
finding frame 122 has a plumb line 123 and is set for aligning,
with feet 124 adapted to the housing of the driving drill, on the
housing of the driving drill indicated in dash-dot lines in FIG. 9.
By means of a plumb line 123 and a suitable scale, any position of
the driving drill can then easily be determined.
This is possible also when the driving drill is connected in tandem
arrangement according to FIG. 10 with a parallel lying guide body
125. After making a first earth bore, the guide body 125 is
connected, for example by screwing, with the housing of the driving
drill, which in FIG. 10 is marked 126, and is introduced into the
existing bore with its front portion protruding relative to the
percussion tip of the driving drill, to make a second earth bore,
parallel to the first, at the same outside diameter as the housing
of the driving drill. The driving drill having been set in
operation, it drills a second bore parallel to the first, of the
same diameter. The first bore suffers no adverse change due to the
protrusion of the guide body 125 and its length from the driving
drill, i.e. by the displacement work thereof.
For the steering of the driving drill there are provided lastly
also wings 127 or 128 according to FIGS. 11 and 12. The wings 127
are disposed at any point of the housing of the driving drill lying
diametrically opposite in pairs, are connected with the housing
rigidly or articulatedly, and steer the driving drill according to
its inclination to the longitudinal axis of the housing
automatically in a certain arc through the soil, so that for
example traversal beneath streets of low crown can also be
accomplished with the driving drill at sufficient depth without any
excavation of earth for positioning the driving drill. The wings
127 have a form tapering in the working direction of the driving
drill and are connected with the housing of the driving drill
either rigidly or articulatedly. The articulated connection permits
the adjustment of the wing inclination to the longitudinal axis of
the housing and hence a selection of the arc on which the driving
drill moves through the earth, or respectively it makes possible an
adaptation to the nature of the ground to be traversed.
The articulated connection of the wings 127 includes a pin 129
fastened to the housing of the driving drill, on which is mounted
for rotary movement a hub 130 which is welded, for example, to one
end of the respective wing 127. In the other end of wing 127 is
mounted a trunnion screw 131, which extends by its trunnion into
one of several bores 132 arranged in the housing on a corresponding
circular circumference around the pivot axis of the wing 127.
Instead of the wings 127 fastened to the housing of the driving
drill, or in addition to the wings 127, there may be used for the
steering of the driving drill a curved stiff protective tube 44a
which, like the housing in FIG. 11, is shown in detail in FIG. 12
and is provided selectively with wings 128. The wings are
preferably curved in the same amount as the protective tube and
arranged lying opposite in pairs at the protective tube, parallel
to the longitudinal axis thereof.
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