Note: Descriptions are shown in the official language in which they were submitted.
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ADAPTER FOR A SELF-DRILLING, CHEMICALLY ANCHORABLE
FASTENING ELEMENT
100011 This claims the benefit of German Patent Application DE 10 2009 001
464.0, filed March 11,
2009, and hereby incorporated by reference herein.
(00021 The present invention relates to an adapter for a self-drilling,
chemically anchorable fastening
element.
BACKGROUND
[00031 Self-boring fastening elements, such as rock anchors and in particular
chemical shear connectors,
and suitable drills having rotary tool receptacles, as well as the use thereof
in mining and tunneling have
been known to those skilled in the art for quite some time. These fastening
elements are primarily used to
stabilize walls in cavities, such as in tunnels, mine shafts, or the like. In
the production of cavities, the
mechanical properties and in particular the load-bearing capacity of the rock
layers are decreased. With the
aid of the fastening elements, i.e., chemical shear connectors, these rock
layers are anchored and therefore
secured to undamaged rock layers located farther away.
[00041 The shank of the fastening elements is used on the one hand as a
drilling rod, and on the other
hand, in the case of a chemical shear connector, as the receptacle for the
compound to be pressed out. A
drill bit head is mounted on the first end of the shank situated in the
setting direction. The second end of the
shank is inserted into a rotary tool receptacle of a drill which is used to
drill the fastening element into the
substrate.
[00051 An adapter for a self-drilling, chemically anchorable fastening element
is known from
DE 103 36 040 B4. The fastening element has a shank which has a first end with
a drill bit head and a
second, free end, the second end of the shank being provided in places with a
threadlike outer profile. The
adapter is situated on the second, free end of the shank, and on one end has
external engagement means for
a rotary tool receptacle of a drill which is to be used, a base section
provided on the other end at a distance
from the engagement means, and a hollow cylindrical connecting sleeve section
which connects the base
section and the engagement means. The connecting sleeve section has a
threadlike, i.e. threaded, inner
profile in places which corresponds to the threadlike outer profile on the
shank. The connecting sleeve
section is provided with perforations for producing predetermined breaking
points on the adapter.
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[0006] The adapter is screwed onto the second, free end of the shank of the
fastening element, and then
the rotary tool receptacle of the drill is mounted on the engagement means
designed as a quick-engagement
device, for example. After the intended drilling depth is achieved, a curable,
for example quick-curing,
compound is applied. When the curable compound reaches a given degree of
hardness the drill is started up
again, and after a specified torque is exceeded, the predetermined breaking
points break, and the portion of
the adapter having the external engagement means, rotationally driven by the
drill, is moved along the
shank in the direction of the substrate or in the direction of the drill bit
head in order to brace the fastening
element anchored in the substrate.
[0007] Using the known adapter greatly simplifies the setting process for the
self-drilling, chemically
anchorable fastening element, the disengagement torque being clearly definable
within a certain tolerance
range.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide an adapter for a
self-drilling, chemically
anchorable fastening element, having a narrower tolerance range for the
disengagement torque.
[0009] The present invention provides an adapter for a self-drilling,
chemically anchorable fastening
element, having a shank with a first end on which a drill bit head is
provided, and with a second, free end,
the second end of the shank being provided, at least in places, with a
threadlike outer profile, the adapter
which may be placed on the second, free end of the shank having external
engagement means or device on
one end for a rotary tool receptacle of a drill which is to be used, a base
section provided on the other end at
a distance from the engagement means, and a hollow cylindrical connecting
sleeve section which connects
the base section and the engagement means, at least the connecting sleeve
section having a threadlike inner
profile, at least in places, which corresponds to the threadlike outer profile
on the shank.
[0010] According to the present invention, the adapter is formed by a first
element part and a second
element part which are detachably connected to one another via a clutch
device.
[0011] The disengagement torque may be precisely defined as a result of the
design of the clutch device
located between the two element parts which are separate from one another.
When this defined
disengagement torque is exceeded, the clutch device is disengaged and the
second element part having the
engagement means is available in a freely rotatable manner for pretensioning
the fastening element, which
is already anchored in the substrate. The disengagement torque of the clutch
device is set in such a way that
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during the drilling process the two element parts remain in a coupled state
for transmitting drilling torque.
[0012] The adapter has a small number of parts, which are connected to one
another. The two element
parts are easily manufacturable and may have a robust design, which represents
an important economic
advantage in particular for a mass-produced product, as is the case for the
adapter according to the present
invention.
[0013] At the start of the drilling process, the adapter does not have to be
screwed in until it appears at
the free end of the shank. During operation of the drill, the adapter rotates
until it contacts the screw stop on
the second, free end of the shank. The shank is then drilled into the
substrate, via the adapter, with the aid
of the drill until the intended drilling depth is reached. The base section of
the adapter provides a screw
stop for the adapter.
[0014] For a fastening element in the form of a chemical shear connector, the
shank has a hollow
cylindrical design, the interior space formed by the shank being used to
conduct the curable compound or
to accommodate a curable compound in the shank. The base section on the first
element part of the adapter
may be used as a retaining device for the compound, situated in the shank, to
be pressed out. The
compound to be pressed out is packaged in a film bag, for example, and is
situated in a receptacle, for
example in an interior tube, in the shank. This is particularly advantageous
for overhead applications, since
due to the base section the compound to be pressed out is not able to slide
out of the hollow cylindrical
shank. A preferably central opening is advantageously provided in the base
section which allows a pressing
mechanism to be inserted in order to apply the compound to be pressed out,
situated in the shank, without
having to remove the adapter from the free end of the shank for this work
step.
[0015] The shank, for example an anchor tube, may be provided as piece goods
which are cut to the
required or desired length on site. Because the drill bit head is mounted only
on the shank, this preassembly
step may also be carried out on site. To improve the extraction parameters of
fastening elements such as
rock anchors, the shank is often provided with exterior profiling along its
entire length. The inner thread of
the adapter is preferably matched to the outer thread, which is provided as
profiling. If the shank does not
have an outer thread on its exterior, a suitable thread may be provided, for
example cut, on site on the free
end of the shank for connecting the adapter. Generous tolerances may be
present between the inner thread
on the adapter and the outer thread on the shank without greatly limiting the
functioning of the connection
of these two parts. As a result, for a shank cut to size on site, deburring of
the cut surfaces may usually be
dispensed with.
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[0016] The quick-engagement device advantageously has a wrench connection. A
bihexagonal or
polygonal design, for example, is used as the wrench connection, thus
minimizing the angle of twist for
finding the geometries for connecting the rotary tool receptacle of the drill
to the fastening element. In
addition, a tool may be placed on the wrench connection, if necessary, for
screwing and unscrewing the
adapter on the shank.
[0017] The clutch device preferably includes an axially extending stop surface
situated on the first
element part and an axially extending counterstop surface situated on the
second element part for
transmitting the drilling torque. In the case of a clutch device having
elements which shear or break off, a
disengagement torque of the clutch device may be easily defined via the size
of the contact surfaces of the
stop surface and counterstop surface which may be brought into contact with
one another.
[0018] For a drilling process having a reverse rotation of the drive of the
drill, first the fastening element
is drilled into the substrate, the stop surface and the counterstop surface
being in mutual contact for
transmission of the drilling torque. After the anchoring depth is reached and
the curable compound is at
least partially cured, the drill is started up again, the rotational direction
of the drive being reversed with
respect to the drilling rotational direction. The second element part is then
freely rotatable, and in order to
pretension the fastening element which is already anchored in the substrate,
may then be moved by the drill
in the direction of the substrate or in the direction of the drill bit head,
for example, until contacting an
anchor plate provided on the substrate.
[0019] On one of the element parts the clutch device preferably includes at
least one cam which projects
beyond a free edge, and at least one recess provided on the free edge of the
other element part, the at least
one cam engaging in the at least one recess for transmission of torque. For
transmission of drilling torque,
the side face of the cam extending in the rotational direction comes into
contact with the corresponding side
face of the recess. When the fastening element already anchored in the
substrate is braced, the cam, for
example, slides out of the recess on the other element part, and the element
part having the engagement
means may be moved along the shank in a freely rotatable manner.
[0020] Alternatively, the at least one cam breaks off when the disengagement
torque of the clutch device
is exceeded, so that the element part having the engagement means may be moved
along the shank in a
freely rotatable manner. The height of the at least one cam of the
corresponding element part which
projects beyond the free edge of the corresponding free edge is selected in
such a way that the center of
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gravity of the sheared or broken-off cam element is situated within the
recess. This ensures that the at least
one sheared or broken-off cam element remains within the recess after the
clutch device is disengaged.
[0021] At least one of the side walls of the at least one recess preferably
extends at an angle relative to
the center of rotation of the corresponding element part. The side wall
extending at an angle relative to the
rotation, i.e., obliquely or transversely with respect to a radius, may be
used, depending on the orientation
of the inclination, on the one hand as a securing surface for retaining a
sheared or broken-off cam element,
or on the other hand as a guide surface to facilitate sliding of the at least
one cam from the at least one
recess when the disengagement torque of the clutch device is exceeded.
[0022] If the fastening element is set in a reverse rotation process, the side
wall of the recess lying or
extending in the drilling direction advantageously has an inclination which
extends axially and essentially
in the direction of the center of rotation, so that at this location the
entire contact surface is available for
transmitting the drilling torque. The side wall of the recess located opposite
and trailing the side wall
situated in the drilling direction advantageously extends at an angle relative
to the center of rotation of the
corresponding element part, the angle relative to the center of rotation being
selected according to the
requirements, for example for retaining a section of the at least one cam, or
to facilitate sliding of the at
least one cam from the at least one recess.
[0023] Retaining means are preferably provided in the region of the clutch
device which advantageously
hold the two element parts together in the installed state of the adapter.
This allows the adapter to be
situated as a unit on the free end of the shank, so that the two element parts
do not have to be separately
assembled on the free end of the shank. The retaining element also ensures
that, for example, a sheared or
broken-off cam element remains in the recess. The retaining means are
advantageously flexible, and also
advantageously produce a radially inward pretension on the corresponding edges
of the element parts, thus
ensuring simple installation. The retaining means are made of plastic or
metal, and are also advantageously
designed as a closed ring. Alternatively, the retaining element is made of
multiple interconnected tab
elements which join the two element parts together in places in their contact
region.
[0024] A radially circumferential depression is preferably provided in each
case on the free edges of the
element parts, and the retaining means are situated in this depression, thus
ensuring simple installation of
the adapter.
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100251 The first element part is preferably secured on the second end of the
shank in a rotationally fixed
manner, thus preventing the first element part having the base section from
accidentally coming loose
during the setting process for the fastening element. In particular for a
setting process for the fastening
element using reverse rotation of the drill drive, the first element part
which is secured on the second end of
the shank in a rotationally fixed manner ensures simple anchoring and
pretensioning of the fastening
element. During the drilling process, the second element part having the
engagement means is moved in the
direction of the free, second end of the shank, the first element part which
is secured on the second end of
the shank in a rotationally fixed manner preventing the adapter from twisting
off from the shank of the
fastening element. In the subsequent reversed rotation, the second element
part is moved away from the
first element part which is secured in a rotationally fixed manner. The type
of securing of the first element
part is advantageously selected in such a way that the first element part is
able to sufficiently absorb the
forces which arise in the drilling process.
[00261 The first element part is preferably secured on the second end of the
shank in a positive-fit
manner, which ensures that the first element part is adequately secured on the
second end of the shank.
Axially extending bore holes are advantageously provided in the first element
part and the shank of the
fastening element, which together form a receptacle for a connecting pin. The
bore holes advantageously
extend starting from the base section of the first element part, and are
externally accessible for installation
of the connecting pin. Alternatively, the section of the bore hole extends, at
least in the first element part,
starting from the end facing the second element part, in the direction of the
base section of the first element
part, it being possible to similarly insert the connecting pin from this end
for securing the first element part
on the second end of the shank in a rotationally fixed manner. In a further
alternative, a bore hole oriented
radially inward is provided in the first element part, and a connecting pin
which engages in the end region
of the second end of the shank is inserted into the bore hole.
[00271 Further options for securing the first element part on the second end
of the shank in a rotationally
fixed manner include providing an adhesive or a clamping connection, for
example by deforming the
corresponding contact surfaces between the first element part and the end
region on the second end of the
shank. A further option includes, but is not limited to, shrink-fitting the
first element part on the second end
of the shank.
[00281 The adapter is advantageously manufactured in a casting process.
Subsequent machining of the
cast adapter may be dispensed with on account of the allowable tolerances.
Besides this economical
manufacturing method, the adapter may also be manufactured in a
casting/milling process, for example.
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[0029] The present invention is explained in greater detail below with
reference to exemplary
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 shows a self-drilling, chemically anchorable rock anchor in a
side view;
[0031] Figure 2 shows a first exemplary embodiment of an adapter in an
enlarged side view;
[0032] Figure 3 shows the first element part of the adapter according to
Figure 2 in a partial section;
[0033] Figure 4 shows the adapter according to Figure 2 in a longitudinal
section;
[0034] Figure 5 shows a second exemplary embodiment of an adapter in a side
view;
[0035] Figure 6 shows the adapter in a first longitudinal section according to
line VI-VI in Figure 5;
[0036] Figure 7 shows the adapter in a second longitudinal section offset by
90 relative to the first
longitudinal section, according to line VII-VII in Figure 5; and
[0037] Figure 8 shows the adapter in a cross section according to line VIII-
VIII in Figure 5.
[0038] Identical parts are basically provided with the same reference numerals
in the figures.
DETAILED DESCRIPTION
[0039] Chemically anchorable fastening element 11 illustrated in Figure 1, in
the form of a rock anchor,
has a hollow cylindrical shank 12 or anchor tube which is provided with a
drill bit head 16 on a first end 13,
and which has a second, free end 14 situated opposite first end 13. Shank 12
is provided with a threadlike
outer profile 15 in places at an end region on second end 14. Threadlike outer
profile 15 advantageously
extends over the entire longitudinal extension of shank 12. A curable compound
17 packaged in a film bag
is provided in the receptacle formed by hollow cylindrical shank 12.
[0040] An adapter 21, illustrated in detail in Figures 2 through 4, is
provided on second, free end 14 of
shank 12. Adapter 21 is formed by a first element part 22 and a second element
part 32 which are
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detachably connected to one another via a clutch device 41.
[0041] First element part 22 has a base section 23 with a central opening 24,
and has a first hollow
cylindrical connecting sleeve section 25 which projects from base section 23
on one side of base section 23.
A sealing element 27 is situated in opening 24 in base section 23. The
interior of first hollow cylindrical
connecting sleeve section 25 is provided in places with a threadlike inner
profile 26 which may screwed
onto threadlike outer profile 15 at the end region on second end 14 of shank
12.
[0042] Two bore holes 28 situated opposite each other extend, starting from
base section 23, and in
places each bore hole merges into a groove 18 on second, free end 14 of shank
12. Two connecting pins 29
may be inserted into these bore holes 28, thus allowing first element part 22
to be secured on second end 14
of shank 12 in a rotationally fixed and positive-fit manner.
[0043] Second element part 32 has a hollow cylindrical design, and on one end
33 has a radially
outwardly projecting collar 34 which adjoins exterior engagement means or
device 35, having a polygonal
design, for a rotary tool receptacle of a drill which is to be used. The
section adjoining engagement means
35 forms second hollow cylindrical connecting sleeve section 36. The interior
of second element part 32 is
provided in places with a threadlike inner profile 37 which may be screwed
onto threadlike outer profile 15
of shank 12.
[0044] Second hollow cylindrical connecting sleeve section 36 also has an
exterior threadlike outer
profile 15 in places for mounting fastening means, such as a lock nut. Since
adapter 21 for the most part
remains on shank 12 even after fastening element 11 is set, adapter 21 may be
used, for example, for fixing
a pad to the wall of the cavity to be secured. Such pads are, for example,
reinforcing mats or mesh pads
made of metal or plastic which provide protection from unsecured falling rock.
These pads are
advantageously situated in an overlapping manner in the region of the set
fastening element 11. As the
result of providing fastening means on adapter 21, in a first step a first pad
may be secured as such to
adapter 21. A second pad is then placed over adapter 21 and is secured using
the same or other fastening
means.
[0045] For transmitting the drilling torque, clutch device 41, which
detachably connects first element part
22 and second element part 32 to one another, includes two axially extending
stop surfaces 42 situated
opposite each other on first element part 22, and two axially extending
counterstop surfaces 46 similarly
situated with respect to one another on second element part 32. The free end
of first hollow cylindrical
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connecting sleeve section 25 of first element part 22 extends in a spiral
manner between stop surfaces 42,
the pitch being designed to be greater than the pitch of threadlike outer
profile 15 of shank 12. The free end
of second hollow cylindrical connecting sleeve section 36 of second element
part 32 likewise extends in a
spiral manner between counterstop surfaces 46, the pitch being designed to be
greater than the pitch of
threadlike outer profile 15 of shank 12.
100461 After adapter 21 is placed on free end 14 of shank 12, a drill is used
to set fastening element 11 in
rotation in drilling direction 49 via adapter 21. After the intended drilling
depth is reached, the drill is shut
off and curable compound 17 is pressed out, for example with the aid of a
pressing device inserted through
opening 24 in base section 23 of first element part 22. When curable compound
17 reaches a specified
degree of hardness, the drill is started up again, this time a rotation being
exerted on adapter 21 in bracing
direction 50, in the opposite direction of drilling direction 49. Second
element part 32 is moved in a freely
rotatable manner in the direction of drill bit head 16, along threadlike outer
profile 15 of shank 12, until
fastening element 11 is braced. Due to the spiral design of the free ends of
first connecting sleeve section
25 as well as second connecting sleeve section 36, counterstop surfaces 46 are
able to slide past stop
surfaces 42 of first element part 22, which is on free end 14 of shank 12 in a
rotationally fixed manner,
when element part 32 is axially displaced.
[0047] Adapter 51 illustrated in Figures 5 through 8 differs from previously
described adapter 21
essentially in the design of clutch device 71 which detachably connects first
element part 52 to second
element part 62. First element part 52 is advantageously secured on the free
end of the shank of the
fastening element in a rotationally fixed manner. Clutch device 71 includes
two cams 76 situated opposite
each other which project beyond free edge 63 of second connecting sleeve
section 66 of second element
part 62. Clutch device 71 also includes recesses 72, provided on free edge 53
of first connecting sleeve
section 55 of first element part 52, corresponding to the orientation of cams
76; for transmitting torque,
cams 76 engage in the recesses.
[00481 Also provided on free edge 63 of second connecting sleeve section 66 of
second element part 62
are two spacing cams 64 situated opposite each other, which in the installed
state of adapter 51 lie against
free edge 53 of first connecting sleeve section 55 of first element part 52.
Spacing cams 64 prevent free
edges 53 and 63 from making surface contact with one another, thus preventing
adhesion between these
free edges and therefore preventing the free edges from influencing the
disengagement torque of clutch
device 71.
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[0Q49] Leading side wall 73 of recesses 72, which is situated in rotary
drilling direction 78, essentially
extends in the direction of center of rotation 56 of first element part 52.
Trailing side wall 74 of recesses 72,
which is situated in bracing rotary direction 79, extends at an angle relative
to center of rotation 56 of first
element part 52, the inclination of these side walls 74 being oriented to
retain a broken-off cam section in
recess 72.
[0050] In the region of clutch device 71, first element part 52 as well as
second element part 62 are
provided with a radially circumferential depression 81 in which flexible
retaining means 82 designed as a
circumferentially closed ring are provided.
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