U.S. patent application number 12/995793 was filed with the patent office on 2012-01-12 for drill head.
This patent application is currently assigned to Tracto-Technik GmbH & Co. KG. Invention is credited to Volker Boike.
Application Number | 20120006597 12/995793 |
Document ID | / |
Family ID | 41396526 |
Filed Date | 2012-01-12 |
United States Patent
Application |
20120006597 |
Kind Code |
A1 |
Boike; Volker |
January 12, 2012 |
DRILL HEAD
Abstract
A drill head, particularly for a horizontal drilling device,
includes a housing and a radar unit disposed within the housing.
The radar unit generates electromagnetic waves that exit the
housing. The housing of the drill head is made of a dielectric
material at least in the region where the electromagnetic waves
exit the housing.
Inventors: |
Boike; Volker; (Lennestadt,
DE) |
Assignee: |
Tracto-Technik GmbH & Co.
KG
Lennestadt
DE
|
Family ID: |
41396526 |
Appl. No.: |
12/995793 |
Filed: |
June 3, 2009 |
PCT Filed: |
June 3, 2009 |
PCT NO: |
PCT/EP09/03959 |
371 Date: |
December 2, 2010 |
Current U.S.
Class: |
175/45 |
Current CPC
Class: |
E21B 7/205 20130101;
E21B 47/09 20130101; E21B 7/046 20130101; G01S 13/885 20130101;
E21B 7/26 20130101 |
Class at
Publication: |
175/45 |
International
Class: |
E21B 47/02 20060101
E21B047/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 2008 |
DE |
10 2008 026 456.3 |
Claims
1.-7. (canceled)
8. A drill head, comprising: a housing; and a radar unit arranged
within the housing and constructed to produce electromagnetic waves
which issue out from the housing, wherein the housing is made of a
dielectric material at least in a region in which the
electromagnetic waves issue out therefrom.
9. The drill head of claim 8 for application in a horizontal
drilling device,
10. The drill head of claim 8, wherein a remainder of the housing
is made of a metallic material.
11. The drill head of claim 10, wherein the metallic material is
steel.
12. The drill head of claim 8, wherein the region of dielectric
material is located in an area of an end face of the drill
head.
13. The drill head of claim 8, wherein the dielectric material is a
ceramic material.
14. The drill head of claim 8, wherein the ceramic material
includes an oxide ceramics.
15. The drill head of claim 8, further comprising a plate of
dielectric material connected to the housing for covering an
opening in the region of the housing.
16. The drill head of claim 15, wherein the plate is constructed
for detachable connection with the housing.
17. The drill head of claim 15, wherein the plate is arranged in a
depression of the housing so that an outer surface of the plate is
flush or recessed in relation with a surface of the housing.
Description
[0001] The invention relates to a drill head, and in particular to
a drill head for a horizontal drilling device.
[0002] Obstacles in front of the drill head of the drilling device
pose a problem in the horizontal drilling technique. Such obstacles
may for example involve boulders of hard rock that oftentimes
cannot be crushed by the used drilling devices. Furthermore, water,
gas, telephone, or power lines can be located in regions near the
earth's surface and may not be destroyed during drilling.
[0003] This problem led to the development of steerable horizontal
drilling devices. Such drilling devices, designated HDD (Horizontal
Directional Drilling), render it possible to navigate around
obstacles. It is further known to sort obstacles by means of
georadar survey in order to enable to circumnavigate obstacles in
view of the location determination.
[0004] U.S. Pat. No. 7,143,844 B2 discloses a horizontal drilling
device with a radar unit which is integrated in a sensor housing of
the drill head. Obstacles in the earth are normally detected
reliably by the radar unit in that electromagnetic waves radiating
from the radar unit are reflected from electrically conductive
parts of the obstacles and received again by the radar unit. By
analyzing the received electromagnetic waves, it is possible i.a.
to determine the position, i.e. the direction of the obstacle in
relation to the drill head, and the distance thereto, and to use it
for a course correction of the drilling device.
[0005] The integration of a radar unit in a horizontal drilling
device represents however a major problem. Since the radar unit
normally is used to monitor the region in front of the drill head,
it is sensible to arrange the radar unit in the drill head in order
to preclude the horizontal drilling device itself from interfering
with the electromagnetic waves.
[0006] In a horizontal drilling device, the drill head represents
however a component that is subject to most intense stress because
it transmits to the earth the static and dynamic (when a percussion
device is involved) drilling forces, generated by a drive unit of
the horizontal drilling device. As a consequence of the high stress
to which the drill head is subject during drilling operation, the
drill head is virtually exclusively made of high-alloy steel
because this material has the required properties as far as
hardness, strength, wear-resistance, and ductility are concerned
and is also inexpensive.
[0007] Steel constitutes however an electrically conductive
material so that electromagnetic waves which radiate from the radar
unit are reflected. Integration of a radar unit in a drill head of
a horizontal drilling device poses a great challenge because the
radar unit should be integrated into the housing of the drill head
in order to protect it, but the use of steel or also a different
electrically conductive, in particular metallic material for the
housing prevents the electromagnetic waves from radiating through
the housing wall as a consequence of a reflection on the inner
housing side.
[0008] Even though U.S. Pat. No. 7,143,844 B2 mentions the
integration of a radar unit into the housing of a drill head of a
horizontal drilling device, there is no disclosure that allows
solution to the afore-described problem.
[0009] Starting from this prior art, the invention is based on the
object to provide an advantageous possibility to integrate a radar
unit in a drill head.
[0010] This object is solved by a drill head according to patent
claim 1. Advantageous embodiments are the subject matter of the
dependent patent claims.
[0011] The essence of the invention resides in the manufacture of
at least the one region of the housing of a drill head according to
the invention in which the electromagnetic waves radiating from a
radar unit that is integrated in the drill head emerge from the
housing, from a dielectric, i.e. electrically non-conductive,
material. Such a material does not reflect the electromagnetic
waves so as to enable a nearly uninhibited emergence from the drill
head.
[0012] A drill head according to the invention, provided in
particular for a horizontal drilling device, thus includes at least
a housing as well as a radar unit arranged within the housing to
produce electromagnetic waves that are capable of issuing out of
the housing, wherein the housing is made at least in part of
dielectric material at least in the region in which the
electromagnetic waves exit therefrom.
[0013] A basic construction of a radar unit and in particular of a
georadar unit designed for application in a drilling device is
sufficiently known in the prior art, whereby for sake of
completeness it should be noted that such a radar unit includes at
least a transmitter unit for sending out electromagnetic waves, a
receiver unit for receiving electromagnetic waves, in particular
the electromagnetic waves previously transmitted and reflected from
an object. Furthermore, the radar unit can include a transmission
device for transmitting signals of the receiver unit to an
evaluation unit, wherein the evaluation unit may be arranged within
the drilling device as well as also outside thereof and in
particular in a control device positioned at ground surface. The
evaluation unit may further be connected to a display unit to
indicate information about obstacles situated in the earth and
detected by the radar unit, in particular about distance, location
(i.e. direction in relation to the drilling device), size and
shape. The evaluation unit may further be connected with a control
unit which is able to automatically execute a course correction for
the drill head of the drilling device to prevent a collision with
the detected obstacle.
[0014] The configuration of a drill head according to the invention
enables further the manufacture of the housing of the drill head
from a material especially suitable for this, in particular steel,
and the manufacture of only a defined region, preferably of a size
large enough to allow electromagnetic waves of the radar unit to
unimpededly issue out of the housing of the drill head, from a
material which optionally may satisfy to a lesser degree the
demands required from a material for the housing of a drill head,
but has dielectric (and therefore does not reflect electromagnetic
waves of a radar unit) characteristics.
[0015] According to a preferred embodiment of the present
invention, it is provided to make a region of the end face of the
drill head of dielectric material. This configuration permits a
targeted transmission of the electromagnetic waves of the radar
unit in the drilling device because the region of the earth should
normally be monitored for obstacles in drilling direction, i.e. in
the area in front of the drill head.
[0016] According to a preferred embodiment of the present
invention, the dielectric material is ceramics, in particular oxide
ceramics because these materials are characterized by a very high
wear resistance that is advantageous for a material for
manufacturing the housing of a drill head, and have of course the
required dielectric property.
[0017] Advantageously, the integration into the housing of the
drill head may include the manufacture thereof from a suitable
material, e.g. steel, and the provision of an opening in the region
which should be made of a dielectric material, with the opening
being covered subsequently by a plate of such a dielectric
material.
[0018] According to an especially preferred embodiment, it can be
provided to detachably secure the plate on the remainder of the
housing of the drill head so that replacement, for example for
repair purposes, is rendered possible in a simple manner. This can
be of advantage because even though ceramic materials for example
exhibit a very high wear resistance, they still have a relative low
ductility so that it may happen that the plate cracks in the event
of an impact. Of course, it may also be provided to mount the plate
on the remainder of the housing in a non-detachable manner.
[0019] The plate may, for example, be connected with the remainder
of the housing of the drill head through bonding, whereby the
connection may be detachable or non-detachable depending on the
selection of the adhesive. A bonded joint that is detachable can be
loosened by heating the adhesive for example.
[0020] It may further be suitable to arrange the plate of
dielectric material in a depression of the housing so that the
outer surface thereof is flush or recessed in relation to the
surface of the remainder of the housing. As a result, the plate of
dielectric material can be substantially protected by the remainder
of the housing of the drill head.
[0021] Exemplary embodiments of the invention will now be described
in greater detail with reference to the drawings.
[0022] It is shown in the drawings:
[0023] FIG. 1 a horizontal drilling device with a drill head
according to the invention,
[0024] FIG. 2 a first embodiment of a drill head according to the
invention, and
[0025] FIG. 3 a second embodiment of a drill head according to the
invention.
[0026] FIG. 1 shows by way of a simplified illustration the
application of a steerable horizontal drilling device which is also
called a HDD drilling device. HDD is short for "Horizontal
Directional Drilling". The horizontal drilling device includes a
drill head 1 which involves a drill head 1 according to the
invention. The drill head 1 is mounted to the leading end of a
drill rod 2, with the drill rod 2 comprised of a plurality of rod
sections 3 that are connected to one another via screw threads. The
trailing end of the drill rod 2 is connected to a drive unit 4 by
which forces in longitudinal direction of the drill rod 2 as well
as a torque can be transmitted to the drill rod. By means of the
drive unit 4, the drill rod 2 including the attached drill head 1
can be driven in thrust direction and pull direction as well as
rotated.
[0027] The drill head 1 involved is a so-called steerable drill
head having an end face 5 which is slanted at least in some areas
in relation to the own longitudinal axis and thus in relation to
the drilling direction. The slanted surface causes a deflective
force that is directed to the side during propulsion and results in
curved drilling pattern when the drill head 1 is driven statically,
i.e. does not rotate. A drilling in a straight line is possible
with such a controlled drill head by operating the drill head in
propulsion direction as well as rotating it so that the deflective
forces compensate over a complete revolution.
[0028] In the horizontal drilling device of FIG. 1, the drive unit
4 is placed stationary on the earth's surface. The drilling
operation thus starts also from the earth's surface, whereby
initially it is drilled at a slant into the ground and after
reaching the desired depth, the course of drilling is changed until
reaching the horizontal, and then drilling continues in a
substantially horizontal manner.
[0029] Deviations from the straight-lined drilling course may
become necessary when obstacles (not shown) are encountered in the
earth that cannot be drilled through (e.g. bedrock) or must not be
drilled through (e.g. power, gas, or water lines). To detect such
obstacles in the ground, the drill head is provided with a radar
unit 6 which radiates electromagnetic waves and receives these
waves after the latter have been reflected from an electrically
conductive object, so as to be able to calculate distance, shape,
size, and location of the object.
[0030] FIGS. 2 and 3 show two embodiments of a drill head 1
according to the invention with integrated radar unit 6 and useable
in a horizontal drilling device as shown in FIG. 1.
[0031] The drill heads 1 of FIGS. 2 and 3 have a cylindrical shaft
7 which is formed on its trailing end in drilling direction with a
locking system by which it can be secured to the leading end of the
drill rod 2. Provided on the leading end of the drill head 1 is a
drill head front 8 having a shape configured for maximum
propulsion. For this purpose, the drill head front includes various
hard metal elements 9 which provide for a good cutting action in
the earth and moreover are extremely wear-resistant. The
afore-mentioned slanted surface 10 produces during propulsion in
the earth a laterally directed deflection that allows steerability
of the horizontal drilling device. Integrated in the slanted
surface 10 are in addition two nozzles 11 for bentonite flushing by
which bentonite, conducted to the drill head 1 via an external feed
(not shown) and via the interior of the hollow drill rod 2, exits
under high pressure from the drill head and improves the drilling
propulsion by the hydraulic cutting action on one hand and a
softening of the earth in front of the drill head 1 on the other
hand.
[0032] The radar unit 6 is arranged in the cylindrical shaft 7 of
the drill head 1 and includes a transmitter unit 21 for emitting
electromagnetic waves, a receiver unit 12 for receiving the
reflected electromagnetic waves, as well as a transmission device
13 for transmission of signals from the receiver unit 12 to an
evaluation unit 14 which is connected with the drive unit 4. The
evaluation unit 14 includes a display device 15 which can indicate
information about distance, location, size, and shape of obstacles
located in the earth. The evaluation unit 14 is further connected
with a control unit 16 which enables navigation around the
obstacles by respectively operating the drive unit 4.
[0033] The radar unit 6 sends out the electromagnetic waves in a
defined direction, whereby the region of the housing of the drill
head 1 from which region the electromagnetic waves emerge, is
covered by a plate 17 which is made of oxide ceramics, a dielectric
material. In contrast thereto, the remainder of the housing of the
drill head 1 is made of steel and thus of electrically conductive
material. The plate 17 of oxide ceramics ensures a sufficient
passage of the electromagnetic waves through the housing of the
drill head 1 so as to enable a monitoring of the earth in front of
and/or to the side of the drill head 1. As can be best seen in
FIGS. 2 and 3, the plate 17 is arranged in a depression of the
housing so as to be flush-mounted with the housing.
[0034] An essential difference between the drill heads 1 of FIGS. 2
and 3 is the location of the plate 17 of oxide ceramics. In the
configuration of FIG. 2, the plate is arranged within the slanted
surface 10 and thus directly in drilling direction, whereas in the
configuration of FIG. 3 the plate is located in a section of the
cylindrical casing of the shaft 7. The arrangement illustrated in
FIG. 2 has the advantage that the electromagnetic waves are able to
emerge from the housing of the drill head 1 directly in drilling
direction. A drawback is however that the slanted surface 10
belongs to those regions of a drill head that are exposed to
greatest stress so that the risk is greater that the plate 17 which
is made of oxide ceramics and thus has a low ductility is
destroyed. The arrangement selected in the configuration of FIG. 3
better protects the plate because it is shielded by the drill head
front that is greater in diameter.
[0035] The drill heads 1 illustrated in FIGS. 2 and 3 are
configured essentially in three parts, comprised of a shaft end 18
(not shown in FIG. 2) for attachment to the leading end of the
drill rod 2, the drill head front 8 whose shape is designed for
optimum drilling propulsion, as well as a radar housing 19 arranged
between these components of the drill head and forming part of the
shaft 7 of the drill head 1. The radar unit 6, and also the plate
17 of oxide ceramics according to the drill head 1 of FIG. 3, is
arranged in the radar housing 19. The connection between the three
parts of the drill head 1 is implemented by a quick-acting closure
system with locking elements 20. The three-part configuration of
the drill head 1 allows optional installation of the radar unit 6
so that the drill head front 8 can also be directly connected with
the shaft end 18. Depending on the earth in which drilling takes
place, there may be situation in which radar monitoring may not be
required and since the radar unit is also fairly expensive, the
optional installation of the radar unit 6 serves only to improve
effectiveness because in some cases fewer radar units may be
purchased than drill heads.
* * * * *