U.S. patent application number 10/534365 was filed with the patent office on 2006-05-11 for reamer assembly.
Invention is credited to Stefan Virtanen.
Application Number | 20060096788 10/534365 |
Document ID | / |
Family ID | 20289490 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060096788 |
Kind Code |
A1 |
Virtanen; Stefan |
May 11, 2006 |
Reamer assembly
Abstract
A reamer assembly for widening a drilled pilot hole or for
widening a hole that has been widened in a first step in a
down-the-hole drilling operation, includes a shank (14) for
attachment of the reamer to the end of a down-the-hole hammer drill
and a conical drill bit or crown (15). The conical bit (15) of the
reamer is divided into at least three segments (18) which are
terminated with a transverse end surface (21) that directly
connects the conical segments and at least three of the segments
(18) include drill buttons (16) that are disposed equidistantly
from the centre axis of the drill bit (15).
Inventors: |
Virtanen; Stefan; (Norberg,
SE) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET
2ND FLOOR
ARLINGTON
VA
22202
US
|
Family ID: |
20289490 |
Appl. No.: |
10/534365 |
Filed: |
September 24, 2003 |
PCT Filed: |
September 24, 2003 |
PCT NO: |
PCT/SE03/01485 |
371 Date: |
December 5, 2005 |
Current U.S.
Class: |
175/406 ;
175/415 |
Current CPC
Class: |
E21B 10/26 20130101 |
Class at
Publication: |
175/406 ;
175/415 |
International
Class: |
E21B 7/28 20060101
E21B007/28 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 2002 |
SE |
0203286-0 |
Claims
1. A reamer assembly (11) for widening a drilled pilot hole or for
widening a hole that has been widened in a first step in a
down-the-hole drilling operation, wherein the reamer assembly
includes a shank (14) for attachment of the reamer to the end of a
down-the-hole hammer drill and a conical drill bit or crown (15),
characterised in that the conical bit (15) of the reamer is divided
into at least three segments (18) which are terminated with a
transverse end surface (21) which directly connects said conical
segments; and in that at-least three of said-segments (18) include
drill buttons (16) that are disposed equidistantly from the centre
axis of the drill bit.
2. A reamer assembly according to claim 1, characterised in that
each segment (18) includes a plurality of drill buttons
(16a-16e).
3. A reamer assembly according to claim 2, characterised in that
the drill buttons (16a-16e) are placed in mutually the same pattern
in each of said segments (18).
4. A reamer assembly according to claim 2, characterised in that a
plurality of drill buttons (16) in one and the same segment are
disposed equidistantly from the centre of the drill bit (15).
5. A reamer assembly according to claim 1, characterised in that
the drill buttons (16a-16e) of one segment are disposed so as to
lie close to or to slightly overlap each other in a common plane
projection. (FIG. 3).
6. A reamer assembly according to claim 1, characterised in that
drill buttons (22) are provided in the transverse end surface (21)
of the drill bit (15).
7. A reamer assembly according to claim 3, characterised in that a
plurality of drill buttons (16) in one and the same segment are
disposed equidistantly from the centre of the drill bit (15).
Description
[0001] The present invention relates to a reamer drill assembly,
i.e. a drill for widening a drilled pilot hole or for widening a
hole that has been widened in a first step in a down-the-hole
drilling operation.
[0002] Reamers, of this kind include a shank for attachment of the
drill to the end of a down-the-hole hammer drill, a conical drill
bit, and to a pilot body disposed on one end of the drill bit. The
pilot body has a somewhat smaller outer diameter than that of the
pre-drilled pilot hole, so as to enable the pilot body to slide
down in the pre-drilled pilot hole and therewith guide the drill to
follow the pilot hole.
[0003] One problem with such reamers is that if the drill bit, or
crown, is slightly oblique and therewith causes the pilot body to
contact the edge of the pilot hole, there is a risk that the shank
will break or fracture, resulting in operational breakdowns and
stoppages. Such breakages can also lead to other complications, for
instance the need to fish up the drill bit lost down the drill
hole.
[0004] Another problem is that larger drill cuttings may find it
difficult to fall down in the pilot hole and therewith leave the
drill location. Large cuttings that are able to fall down in the
pilot hole despite their large size are liable to fasten in and
block the hole, so as to present an obstacle to the pilot body,
which lacks a cutter, and therewith halt drilling until the
cuttings can be removed.
[0005] Another drawback with such reamers is that a reamer must be
made available for each size of pilot hole, so that the pilot body
will be able to pass down through the hole and therewith guide the
reamer during the reaming process.
[0006] Accordingly, one object of the present invention is to
provide a novel reamer assembly which allows all of these problems
and drawbacks to be avoided.
[0007] This object is achieved in that the conical configuration of
the drill bit of the reamer is divided into at least three segments
which are terminated with a transverse end surface which directly
connects said conical segments, and in that a drill button is
provided in at least three of said segments with said buttons
disposed equidistantly from the centre axis of the drill bit.
[0008] The invention will now be described in more detail by way of
example only, with reference to the accompanying drawings, in
which
[0009] FIG. 1 is a schematic illustration of a known reamer
assembly used in rock drilling operations;
[0010] FIG. 2 is a corresponding view of an inventive reamer
assembly for use in rock drilling operations;
[0011] FIG. 3 is a schematic illustration of a common plane
projection of the drill buttons in one segment of the reamer;
[0012] FIG. 4 illustrates schematically andin perspective a reamer
constructed in accordance with the invention; and
[0013] FIG. 5 is an end view of the reamer shown in FIG. 4, as seen
from the side of the drill.
[0014] FIG. 1 thus shows a reamer assembly 1 used to drill in rock
2 in order to widen a predrilled pilot hole 3. The reamer 1
includes a shank 4 and a conical drill bit 5 attached to the shank
4. Attached to the conical surfaces of the drill bit are a number
of drill buttons 6 which are adapted to carry out the actual rock
drilling and rock removing operation.
[0015] Arranged on the end of the bit or crown 5 distal from the
shank 4 is a generally cylindrical pilot body 7 which projects
slightly outwards from the conical drill bit 5. The pilot body 7
has an outer diameter that is slightly smaller than the inner
diameter of the pilot hole 3, therewith enabling the pilot body to
guide the reamer 1 so that said drill will cut away or otherwise
remove rock 2 symmetrically around the centre of the pilot hole and
so that the widened hole will follow the earlier drilled pilot hole
3.
[0016] FIG. 2 illustrates a reamer assembly 11 constructed in
accordance with the present invention. The main difference between
this drill and the earlier known drill 1 shown in FIG. 1 is that
the novel inventive reamer assembly 11 lacks a guide pilot body.
Instead, the drill buttons 16 are relied upon to guide the reamer
in the pilot hole. In the case of reamers designed in accordance
with the present invention, the drill buttons 16 are given precise
positions in the drill bit 15 of the reamer 11 so that combined
action of said buttons will ensure that the reamer 11 is guided in
the pilot hole 3 when drilling in rock 12. In other respects the
reamer 11 has generally the same design as the reamer shown in FIG.
1, in other words includes a shank 14 and a generally conical drill
bit 15.
[0017] According to the present invention, the conical surface of
the drill bit 15 of the reamer 11 is divided into a plurality of
segments 18 each containing a plurality of drill buttons 16. These
buttons 16 have mutually the same positions in respective segments
18, in other words each segment contains buttons that are situated
at mutually the same distance from the centre axis of the drill
bit/reamer as the buttons in other segments. Thus, the button 16a
in the segment 18 is the same distance from the centre axis of the
reamer as the button 16a' in the segment 18'; see FIGS. 4 and 5.
Similarly, the button 16c in the segment 18 is situated at the same
distance from the centre axis of the reamer as the button 16c' in
the segment 18'.
[0018] By placing the buttons 16 in the drill bit 15 in this way,
the buttons are themselves able to guide the reamer 11 when
drilling in rock 12, so as to cause the drilled hole to follow the
pilot hole 13.
[0019] The various buttons 16 of each segment 18 are positioned so
as to lie at different radial distances from the axial centre of
the drill bit, so that at least one button of each segment will be
able to guide the reamer towards the edge of the pilot hole. As
will be seen from the common plane projection shown in FIG. 3, the
buttons 16 will lie adjacent one another or overlap each other to
some extent. This will ensure that at least one button 16 of each
segment 18 will always be able to support against the edge of a
pilot hole and therewith guide the reamer along the hole.
[0020] With the aid of different vertical chain lines 19a, 19b and
19c, FIG. 3 shows how different buttons 16a, 16b and 16c will be
those buttons that function as guides in a pilot hole whose wall
follows the lines 19a, 19b or 19c. Thus, as a result of the
close-by or overlapping relationship of respective buttons 16,
there will always be one button in each segment 18 that is able to
guide the reamer in the pilot hole. Also shown are those buttons
16d and 16e that lie further out towards the edge 20 of the drill
bit 15. These latter buttons do not normally have a guiding effect,
but are always those buttons that cut or remove rock irrespective
of whether the edge of the pilot hole follows the line 19a, the
line 19b or the line 19c.
[0021] Those buttons that are furthest in towards the centre of the
drill bit on its conical segments, i.e. the buttons 16a, are those
which determine the smallest size of the pilot hole with which the
reamer can be used. For example, it has been possible with the aid
of the present invention to widen a pilot hole with a diameter of
from about 150 mm to about 205 mm with one and the same reamer.
[0022] The buttons 16 are preferably placed in mutually the same
pattern in each of the segments. Moreover, several buttons may be
placed equidistantly from the centre of the drill bit in one and
the same segment. See in particular FIG. 5.
[0023] The drill bit 15 must include at least three segments 18, in
order to achieve correct guidance of the reamer 11. There are four
segments in the case of the illustrated embodiment, although this
number may be greater depending on the size of the drill 11.
[0024] The segments 18 are joined together at the end of the drill
bit 15, by a planar or slightly concave transverse end surface 21.
Drill buttons 22 are also provided in the transverse end surface 21
of the drill bit. The function of these latter buttons is not to
cut away rock, but to grind down any cuttings that may have fallen
down and fastened in the pilot hole. When drilling a blind hole,
these buttons 22 will also support against the bottom of the hole
so as to prevent material damage to the drill bit 15.
[0025] Thus, an inventive reamer assembly enables one and the same
reamer to be used with pre-drilled pilot holes of mutually
different sizes, although within certain limits of course, as
distinct from the earlier case where it was necessary to use
different reamers adapted to the size of respective pilot
holes.
[0026] Because an inventive reamer lacks a pilot body, there is
less risk of the drill being subjected to bending loads that result
in breaking of the drill shank.
[0027] The design of the inventive reamer also lowers the risk of
the drill being stopped by cuttings that remain in the pilot hole,
by virtue of the fact that the buttons 22 situated on the end 21 of
the drill bit 15 are able to grind away said cuttings. Drill
cuttings can move past the drill bit and fall down through the
pilot hole more easily than was previously the case, due to the
absence of an obstructive pilot body.
[0028] The inventive reamer is also better than prior art reamers
when reaming blind holes, since the risk of material damage to the
drill bit is considerably less than in the case of prior art
reamers that include a pilot body. Another advantage afforded by
the invention is that a drill bit that does not include a pilot
body is lighter than one that does.
[0029] As will be apparent from the above description, the
inventive reamer may be divided into more than three segments,
wherein buttons in at least three segments are placed at mutually
the same distance from the axial centre of the drill bit, as
defined in the accompanying claims, so as to obtain the necessary
stability in guiding the drill bit. The buttons in remaining
segments may conveniently be positioned differently.
* * * * *