Note: Descriptions are shown in the official language in which they were submitted.
The present invention is directed to a dowel assembly
including an expansion sleeve, an expanding body which ~s pulled
into the expansion sleeve by means of a tie rod, and an end support
on the tie rod for holding members against the receiving material
into which the dowel assembly is anchored. More specifically,
the invention concerns an axially deformable spacer ring bearing
against the trailing end of the expansion sleeve so that, after
the sleeve is anchored, the spacer ring deforms in the axial
direction due to the appllcatio~ ~ to~ue to wor~ing surf~ces
on the end support.
Expansion dowels of the type to which the invention
is directed, are anchored in a borehole in a receiving material by
pulling the expanding body into the leading end of the expansion
sleeve with the sleeve bearing at its trailing end on the end support
of the tie rod. The expanding body can be formed integrally with
the tie rod or it can be attached to the tie rod over a threaded
connection. In one type, the tie rod can be in the form of a
stud threaded on its trailing end so that a nut threaded on the
trailing end acts as the end support. In addition, the tie rod
can be in the form of a bolt where the bol~ head provides the end
support and the expanding body is screwed onto a thread on the
leading end of the tie rod~
These various dowels have the advantage that they can
be anchored in the receiving material independently of any stops.
However, once anchored, the end support cannot be moved in the
axial direction which is sometimes necessary for fastening a
member to the receiving material. If a member, such as a beam,
a plate or similar element, is to be fastened on the surface of
the receiving material, once the expansion sleeve is anchored,
there is no further axial force component available for secuxely
f~
holding the member against tha receiving material.
In the past, attempts have been made to overcome this
problem by using a plastic sleeve positioned between the end
support and the expansion sleeve with the plastic sleeve being
so rigid that it braces the expansion sleeve against the end
support during the anchoring operation and ~hen is deformable
in the axial direction after the predetermined anchoring values
have been reached. This permits the end support to be moved
axially toward the surface of the receiving material for secuxing
a member against its surface. This solution has various draw~
backs so that its use is not completely satisfactory. The
relatively great rigidity of the plastic sleeve, which is
necessary because of the forces absorbed during the anchoring
operation, has the effect that very considerable forces are
required for commencing the deformation of the sleeve.
These forces increase with increasing deformation to
such an extent that the torque to be applied on the end support
no longer suffices to tighten the member to be fastened on its
entire periphery against the receiving material. Moreover, these
plastic sleeves are unsuitable for absorbing the shearing
forces acting on the member being fastened. These shearing forces
must be absorbed bv the trailing end portion of the
expansion sleeve or by the tie rod itself and, therefore, can
lead to overstressing of these elements.
The primary object of the present invention is to
provide a dowel assembly which permits axial movement of the
...... .... .
end support on the tie rod toward the receiving material after
the expansion sleeve has been anchored and also to afford a
structure suitable for guiding and absorbing shearing forces
developed in the range of the end support.
In accordance with the present invention, the dowel
assembly incorporates a spacer assembly arranged betwe0n the
trailing end of the expansion sleeve and the end support on the
tie rod with the spacer assembly consisting of an annular distance
separator, having a diameter corresponding to the diameter of
the expansion sleeve, extending from the end support toward the
.. .. .
expansion sleeve, and with an axially deformable spacer ring
extending between the adjacent ends of the expansion sleeve and
the distance separator. After the expansion sleeve is anchored,
the application of further torque on the end support develops an
initial deformation force which starts the axial deformation
of the spacer ring after which subsequent further deformation -
requires a smaller deformation force.
The deformable spacer ring embodying t~e present
invention, braces the expansion sleeve against the end support
to achieve a sufficient anchorage of the dowel assembly in the
receiving material and, further, it permits aufficient axial
movement of the end support toward the receiving material after
the sufficient anchoring value of the dowel has been reached.
The initial deformation force for commencing the collapse of
the spacer ring is greater than the force required to attain the
required anchoring value. After the axial deformation of the
. . .
spacer ring has commenced, the force needed for further deformation
drops to a value which can be between one-tenth to one-fifth
of the initial deformation force. In this way, only a fraction
of the torque initially applied to the end support is necessary
for the further axial deformation of the spacer ring. The
major part of the torque is available for tightening the member
ayainst the surface of the receiving material. The remaining
deformat:ion force acting on the ring spacer ensures a permanent
frictional connection between the end support and the expansion
- 3 -
sleeve.
The distance separator extending axially between the
end support and the spacer ring permits movement of the spacer
ring within the borehole inthe receiving material. The spacer
ring is completely protected against any outside influences.
Furthermore, the movement of the distance separator into the
interior of the borehole is advantageous for visual observation
of the anchoring operaticn. The distance separator of the
present invention affords an effective guide for the member
being secured to the receiving material. Since the outside
diameter of the expansion sleeve is substantially the same as
the outside diameter of the distance separator, the dowel can
be inserted in a simple manner through a recess or opening in
the member to be fastened to the receiving material. Moreover,
the shearing surface of the distance separator is added to that
of the tie rod whereby considerably hiqher shearing forces
acting on the member to be fastened to the recei~ing material,
can be absorbedO
Preferably, the spacer ring is formed as a stepped
sleeve with one part having a different range of diameters than
the other part and with the parts having approximately the same
axial length and about the same wall thickness. The outside
diameter of one part of the stepped sleeve corresponds
substantially to the inside diameter of the other part. Such
ring parts forming a stepped sleeve can be telescoped one into
the other to afford an axial deformation of the sleeve.
Initially rup~uring the parts of the stepped sle~ve at their
junction requires a certaininitial deformation force which is
larger than the forces needed to be effect the telescoping action
of the parts once the initial rupturing has been accomplished.
The orce required for telescoping the sleeve parts can be controlled
by the constructional design of the sleeve.
As with the spacer ring just described, the parts can
be formed integrally. Other possibilities are available for
connecting the two different diameter sleeve parts, such as by
cementing them together over a short telescoping range or by
joining them toge~her by a press fit. Each of these types of
spacer ring sleeves can be axially shortened by telescoping the
two parts with different diameters, one into the other, with the
initial deformation force commencing the telescoping action.
Either plastic or metal can be used as the material for forming
the stepped sleeves. With parts of different diameters connected
to one another by cementing or pressed fit, different materials
can be used to form the same sleeve. In another embodiment of
the invention, the spacer ring can be formed of two sheet metal
sleeves in partly telescoping relation with the inner sleeve having
a much smaller outside diameter than the inside diameter of the outer
sleeve. With such an arrangement,an annular space is provided
between the two sleeves in which a rubber layer is vulcanized.
This spacer ring can be axially shortened by telescoping the two
sheet metal sleeves spaced apart in the axial direction with the
initial deformation being equivalent to that mentioned above. The
initial i deformation force causes the gripping contact between
the rubber layer and one of the sheet metal sleeves to be interrupted.
The elasticity of the rubber layer ensures that a force is required
for further telescoping of the sleeves which can be controlled
by the suitable selection of the material forming the rubber layer
and also by the dimensioning of the sheet metal sleeves.
Still another embodiment of the spacer ring includes a
sleeve-like arrangement of brittle material which disintegrates
into small parts under compressive stress. PreferablyO such a
sleeve is enclosed by a metal or plastic jacket which protects
the brittle matarial sleeve against forces which can occur
during shipping or when the dowel is inserted into a borehole.
Further, the jacket ensures the frictional connection between the
expansion sleeve ~nd the distance separator after the brittle
material sleeve has disintegrated into small parts due to the
compressive stress corresponding to the initial deformation
force. The jacket can be deformed by a smaller force than the
initial deformation force.
The noticeable collapse of the brittle material sleeve
serves as an indication that the sufficient anchoring values of
the dowel have been attained. The same effect can be obtained
with a ring-shaped body designed as a compound body which
includes the above-mentioned properties.
The brittle material sleeve can be formed of ceramic
material or glass. Ceramic material has the advantage that an
anti-corrosive agent, for example, one having an oil or fatty
base, can be incorporated into the sleeve as in sintered bearings.
The various features of novelty which characterize the
invention are pointed out with particularity in the claims
annexed to and forming a part of this disclosure. For a better
understanding of the invention, its operating advantages and
specific objects attained by its use, reference should be had to
the accompanying drawings and descriptive matter in which there
are illustrated and described preferred embodiments of the
invention.
In the Drawing:
Figure 1 is a longitudinal cross-sectional view of a
dowel assembly embodying the present invention, anchored into
a borehole in a receiving material at the minimum anchoring
-- 6 --
values, and with the spacer ring in the undeformed condition;
Figure 2 is a cross-sectional view similar to Figure 1
but with the spacer ring deformed; and
Figures 3 - 6 are longitudinal sectional views of other
embodiments of the spacer ring.
In the embodiment shown in Figures 1 and 2, a member 2
such as a plate, a bar, a beam or the like is secured by means of
a dowel assembly 1 to a receiving material 3. To effect the
attachment of the member 2, it has a bore ox opening 5 aligned
with the blind borehole 5 in the receiving material so that the
dowel assembly can be inserted through the opening 5 into the
borehole 5.
Dowel assembly 1 consists of an axially elongated bolt 6
with its bolt head 7 serving as an end support with a conventional
washer 8 positioned between the bolt head and the surface of
the member 2. The bolt has a thread at: its leading end, that is li
the end inserted first into the borehole and the leading end has
a thread 9 on which an expanding body 10 is screwed. Laterally
surrounding the leading end part of the tie rod or bolt 6 i5 an
expansion sleeve 11. sy pulling the expansion body 10 in the
direction of the ~railing end of the sleeve, that is, the end
adjacent the end support or head 7, the body forces the expansion
sleeve radially outwardly into anchored engagement with the
surface of the borehole 5. To facilitate the radial expansion
of the sleeve 11 it is provided with axially elongated slots 12
extending from its leading end toward its trailing end. The
trailing end of the expansion sleeve 11 is located midway between
the ends of the bolt ~ within the borehole 5 and a spacer
assembly extends from the trailing end of the expansion sleeve
to the end support provided by the washer 8 and the bolt head 7.
-- 7 --
The spacer assembly consists of a spacer ring 13 in the form of
a stepped sleeve. The stepped sleeve 13 can be formed of plastic.
Extending rearwardly from the sleeve 13 is a distance separator
14 with a leading end contacting sleeve 13, and a trailing end
operatively engageable by head 7 in this case through the medium of
.. . .. .... . .. .
washer 8 such as is well known in the art.
To attain the condition of the dowel assembly shown in
Figure 1, it is inserted through the opening 4 in member 2 into
the boreholP 5 of the receiving material 3. By applying torque on
the lateral working surfaces of head 7 of the bolt 5, the
expanding body 19 is displaced rearwardly into the expansion
sleeve, that is, from its leading end toward its trailing end,
with the expansion sleeve bearing on the end support or head 7
over the spacer ring 13 and the distance separator 14 along with
the washer 8. As represented in Figure 1, the expansion sleeve 11
has been widened in the radial direction and is anchored in the
borehole 5 of the receiving material 3. As shown in Figure 1, the
anchorage of the expansion sleeve is independent of the bearing
of the dowel assembly 1 on member 2 or receiving material 3.
AS indicated in Figure 1 a small interval "z" still remains
between the ~uxtaposed surfaces of the receiving material 3 and
the member 2. This separation is due to exterior influences,
. . .
such as unevenness of the receiving material 3 or sagging of
the member 2.
The application of torque to the head or end support of the
bolt 6, after the predetermined anchoring value of the expansion
sleeve has been reached, has the result that the spacer ring or
stepped sleeve 13 is axially shortened after an initial deformation
force is achieve. Such deformation permits the distance separator
14 to move axially into the borehole 5 toward the expansion sleeve 11
3LV~ A.~
~hus permitting the head 7 to bear against member 3 through the
washer 8. Further application of torque to the head 7 further
telescopes the stepped ring 13 and progressively presses the member
2 against the receiving material 3 as displayed in Figure 2.
Only a fraction of the initlal deformation force is required for
further deformation of the spacer ring 13 to obtain further
: telescoping of the two different diameter portions of ~he stepped
sleeve 13. As soon as member 2 bears tightly against the receiving
material 3, the tor~ue applied to the head 7 has the effect of
pulling the expanding body further into the expansion sleeve 11
with the force being absorbed mainly by member 2.
In Figure 3 the deformable spacer assembly consists of
a ring or sleeve body 16 enclosed by a jacket 17 with the ring
body 16 formed of a material which disintegrates into small parts
after the initial deformation force has been reached. ~he ring
body 16 can be formed of glass, ceramic material or a like substance.
In Figure 4 the deformable spacer assembly consists of
two sheet metal sleeves 18, 19 each of a different diameter and
arranged with sleeve l9 telescoped for a portion of its axial
length into sleeve 18. The differences in diameters between
the two sleeves 18, l9 provides an annular open space between
the two in which a rubber layer 20 is vulcaniæed. After the
initial deformation force has been xceeded, the contact of the
rubber layer 20 with the outer sleeve 18 or the inner sleeve l9
is interrupted so that the sleeves can be telescoped in the
axial direction relative to one another~
In Figures 5 and 6 the deformable spacer assemblies are
constructed as in Figures l and 2 as stepped sleeves 21 (Figure
5) and 22 (Figure 6). As distinguished from the stepped sleeve 13
in Figure l which has the stepped parts formed monolithically, the
_ g _
respective sleeves 21 and 22 are formed of separa-te sleeve parts
23, 24 (Figure 5) and 25, 26 (Figure 6). As can be noted, the
diameters of the sleeve parts in each case are sized so that one
fits into the other. The sleeve parts in each case, are in~er-
connec-ted where they interfi-t by cementing or by a press fit.
The interconnection between the sleeve parts can be broken by
exceeding the initial deformation force permitting the sleeve
parts to -telescope, that is, with the smaller sleeve part rnoving
into the larger sleeve part. In Figure 5, the sleeve parts 23,
24 are Eormed of plastic. In Figure 6, however, the sleeve parts
25, 26 are formed of metal. The connection of the individual
sleeve parts can be combinea at random with the material selection
and con~inations are even possible in the connection of the
s~eeve parts, that is, using a cementing action and a press fit.
~aving described what is believed to be the best mode
by which the invention may be performed, it will be seen that
the invention may be particularly defi.ned as follows:
A dowel assembly for insertion into a prepared borehole
in a receiving material ~or securing a member to the surface of
the receiving material, said dowel assembly comprising an axially
extending expansion sleeve having a leading end inserted first
into the borehole and an oppositely directed trailing end, a
tie rod extending into said sleeve and having a leading end
inserted into said sleeve and a trailing end extending outwardly
from the trailing end of said sleeve, an expanding body attached
to the leading end of said sleeve in the direction toward the trail-
iny end thereof for radially expanding said sleeve into anchoring
engagement with the surface of the borehole, an end support located
on said tie rod adjacent the trailiny end thereof, said end support
extending radially outwardly from said tie rod and having working
-- 10 --
sur:Faces thereon for engagement by a tool ~or applying torque to
said end support, a spacer assembly laterally enclosing said -tie
rod and having a leading end in contact with the trailing end of
said expansion sleeve and a tra:iling end operatively engageable by
said encl support, wherein the :improvement comprises that said spacer
asse~bly comprises an annular distance separa-tor laterally encirc-
ling said tie rod and having an outside diameter generally corres-
ponding to -the outside diameter of said expansioll sleeve, in its
unexpanded sta-te said distance separator having a trailing end
operatively engageabl~ by said end support and a leading end
closer to but spaced from the trailing end of said expansion
sleeve, and an axially deformable spacer ring disposed between
said expansion sleeve and said distance separator and having a
leading end in contact with the traillng end of said expansion sleeve
and a trailing end in contact with the leading end of said
distance separator, said spacer ring being deformable in the axial
direction after said expansion sleeve is expanded and anchored
into th~ borehole, said spacer ring requiring a first deformation
and a smaller second deormation force for con-tinuing -the axial
deformation.
While specific embodiments of the invention have been
shown and described in detail to illustrate the application of
the inventive principles , it will be understood that the
invention may be embodied otherwise without departing from such
principles.
