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CA-3150815-C - DRILLING UNIT

CA3150815CCA 3150815 CCA3150815 CCA 3150815CCA-3150815-C

Abstract

A drilling unit for drilling a hole, wherein the drilling unit comprising a drilling head (1). Said drilling head (1) further comprising pulling means (2) for pulling a casing (7) into the hole, a pilot bit (3) for drilling a center hole, connecting means and a ring bit assembly (4) for reaming the center hole for the casing (7). Said ring bit assembly (4) being connected to said pilot bit (3) by the connecting means and to said casing (7) by the pulling means (2). Said ring bit assembly ( 4) comprising a carrier (5) comprising carrier coupling means (23) and a plurality of ring bit segments (6) movably attached to said carrier coupling means (23).

Inventors

  • Joseph Purcell

Assignees

  • MINCON NORDIC OY

Dates

Publication Date
20260505
Application Date
20200825
Priority Date
20190826

Claims (11)

  1. CLAIMS 1. A drilling unit for drilling a hole, wherein the drilling unit comprises a drilling head, wherein said drilling head further comprises pulling means for pulling a casing into the hole; a pilot bit for drilling a center hole; connecting means; and a ring bit assembly for reaming the center hole for the casing; wherein said ring bit assembly being connected to said pilot bit by the connecting means and to said casing by the pulling means, and wherein said ring bit assembly comprises a carrier comprising carrier coupling means; and a plurality of ring bit segments movably attached to said carrier coupling means, wherein the pilot bit being connected to the ring bit assembly by the ring bit segments, wherein the carrier coupling means comprises a plurality of carrier holes and carrier ribs, and the ring bit segment comprises a segment impact shoulder and a segment reamer shoulder, wherein said segment impact shoulders are attached into the carrier holes, and wherein said segment reamer shoulders and the segment impact shoulders are arranged to attach the ring bit segments to said carrier ribs from the inside of the carrier when said ring bit segments are in the extended position.
  2. 2. A drilling unit according to claim 1, wherein the carrier is uncoupled from the pilot bit.
  3. 3. A drilling unit according to claim 1 or 2, wherein the ring bit segments are radially extendable and retractable, and wherein said ring bit segments are arranged in an extended position when reaming the center hole for the casing and in a retracted position when removing the ring bit assembly from the hole.
  4. 4. A drilling unit according to any one of claims 1-3, wherein said ring bit segments are arranged in the extended position located further out than an outer diameter of the casing when reaming the center hole for the casing; and in the retracted position located further in than an inner diameter 11 of the casing when removing the ring bit assembly from the hole.
  5. 5. A drilling unit according to any one of claims 1-4, wherein said pulling means comprises a casing shoe at the head of the casing for coupling the casing and the ring bit segments movably together allowing the ring bit assembly to rotate freely around the longitudinal axis of the casing.
  6. 6. A drilling unit according to any one of claims 1-5, wherein the connecting means comprises first locking means located on a circumferential outer surface of the pilot bit; and second locking means located on a surface of the ring bit segments; wherein said first locking means are arranged to receive said second locking means for locking the ring bit assembly and the pilot bit together.
  7. 7. A drilling unit according to claim 6, wherein the first locking means comprises longitudinal grooves, wherein the grooves are arranged to receive the ring bit segments for locking the ring bit assembly and the pilot bit together when reaming the center hole for the casing.
  8. 8. A drilling unit according to claim 6, wherein the first locking means comprises circumferential grooves and the second locking means comprises a first cavity on the surface of each of the ring bit segments, wherein the circumferential grooves are arranged to receive the ring bit segments and the first cavities for locking the ring bit assembly and the pilot bit together when reaming the center hole for the casing; and the first locking means further comprises longitudinal grooves and shoulders and the second locking means further comprises a second cavity on the surface of each of the ring bit segments, wherein the longitudinal grooves and the shoulders are arranged to receive the ring bit segments and the second cavities for removing the ring bit assembly from the hole.
  9. 9. A drilling unit according to claim 8, wherein the pilot bit is arranged to be rotated in relation to the carrier. 12
  10. 10. An arrangement for drilling a hole, comprising the drilling unit according to any one of claims 1–9 and further comprising a lifting tool for removing the ring bit assembly from the hole.
  11. 11. A method for producing ring bit segments of any one of the claims 1–9, wherein the method comprises preparing a ring billet; forming segment impact shoulders and segment reamer shoulders; and cutting the formed ring billet to smaller pieces for forming ring bit segments.

Description

WO 2021/038131 1 PCT /FI2020/050550 DRILLING UNIT FIELD OF THE INVENTION The present invention relates to drilling a hole in the ground. More particularly, the present invention is directed to a drilling unit and an 5 arrangement for drilling a hole, and a method for producing ring bit segments. BACKGROUND OF THE INVENTION A drilling device is used when drilling a hole in the ground. Conventionally the drilling device comprises a drilling unit that is fed into the hole to be drilled. The drilling device has a casing inside of which there is the 10 drilling unit. The drilling unit has a drilling head, which comprises pulling means for pulling a casing into the hole and a pilot bit for drilling a center hole. The drilling device comprises also a ring bit connected to the casing for reaming the center hole for the casing. After drilling and installing a casing into the hole, the pilot bit is pulled out of the hole through the casing. Because the ring bit is 15 connected to the casing, it is left into the hole with the casing. This means that the ring bit is not reusable and a new ring bit is needed every time a hole is drilled. This increases cost of the drilling. There is also used a drilling device comprising a casing inside of which there is a drilling unit that is fed into the hole to be drilled. The drilling unit 20 comprises a drilling head having a pilot bit with a plurality of wings and pulling means for pulling a casing into a hole during the drilling. When the wings are in an extended state, they are drilling a larger hole to the casing and when they are in a retracted position, they are drilling a smaller hole. The pilot bit wings can be either feed activated or rotation activated. When drilling a hole in the ground, the 25 feed activated pilot bit is pushed against the bottom of the hole and the wings are pushed out with an internal mechanism and locked to this position. After drilling and installing a casing into the hole, the wings are retracted by pulling out the pilot pit. The rotation activated pilot bit is activated by pushing the pilot bit against the bottom of the hole and rotating it to the one direction to turn or slide 30 wings to an extended position. With reverse rotation, the wings are retracted to an original position. After drilling, the pilot bit with the retracted wings are pulled up and out of the hole through the casing. When using a drilling device where wings are attached to a pilot bit body, several drawbacks has been discovered, mainly relating to the construction 35 of the arrangement. First, designing wings that can be extracted and retracted in WO 2021/038131 2 PCT /FI2020/050550 challenging conditions in the ground is very complicated. Furthermore, complicated locking means are used to lock the wings to the pilot bit and in many cases; replacing or repairing the wings is difficult or even impossible. In addition, locking the wings to the extracted or retracted position tends to fail causing 5 unintentional closing and opening of the wings and unnecessary breaks to the work. BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is, thus, to provide a new apparatus and an arrangement for drilling a hole, and a method for producing ring bit 10 segments to solve the above problems. The objects of the invention are achieved by a method and an arrangement, which are characterized by what is stated in the independent claims. Some of the preferred embodiments of the invention are disclosed in the dependent claims. The invention is based on the idea of providing a new kind of drilling 15 unit for drilling a hole wherein ring bit segments are removable attached to a carrier. An advantage of the arrangement and method of the invention is that ring bit segments are separated from a pilot bit body and attached to a carrier, thus making the design very simple. With the apparatus and the method of the 20 invention, it is easy to replace the ring bit segments and the ring bit assembly. In addition, locking of the ring bit segments to an extracted or retracted position is simple. After drilling and installing a casing into the hole it is easy to take the ring bit assembly out of the hole with the pilot bit. Thus, the ring bit assembly is reusable decreasing drilling costs. Other advantages of the solution are explained 25 in connection with the description. BRIEF DESCRIPTION OF THE DRAWINGS In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which Figure 1 illustrates a drilling head according to an embodiment; Figure 2 is an exploded view of the drilling head according to figure 1; Figure 3a is an exploded view of a ring bit assembly according to an embodiment; Figure 3b illustrates the ring bit assembly according to figure 1 when 35 the ring bit segments are in an extended position; WO 2021/038131 3 PCT /FI2020/050550 Figure 3c illustrates the ring bit assembly according to figu