U.S. patent application number 09/829284 was filed with the patent office on 2002-04-25 for tubular anchor.
Invention is credited to Leibhard, Erich, Ludwig, Wolfgang.
Application Number | 20020046535 09/829284 |
Document ID | / |
Family ID | 7638218 |
Filed Date | 2002-04-25 |
United States Patent
Application |
20020046535 |
Kind Code |
A1 |
Ludwig, Wolfgang ; et
al. |
April 25, 2002 |
Tubular anchor
Abstract
A tubular anchor to be inserted into a bore formed in a
constructional structure and including a hollow anchor body (1),
and a trapezoidal thread-shaped profile (2) provided on at least a
portion of an outer surface of the anchor body (1) and having a
crest region (3) and a root region (4) both extending parallel to a
longitudinal axis of the anchor body (1), with the at least flanks
of a trapezoidal cross-section of the profile (2) remote from an
end of the anchor body (1) facing in a setting direction being
inclined with respect to the longitudinal axis of the anchor body
(1) at an angle (.alpha.) from 10.degree. to 45.degree..
Inventors: |
Ludwig, Wolfgang;
(Schwabmunchen, DE) ; Leibhard, Erich; (Munich,
DE) |
Correspondence
Address: |
DAVID TOREN, ESQ.
SIDLEY, AUSTIN, BROWN & WOOD, LLP
875 THIRD AVE
NEW YORK
NY
10022
US
|
Family ID: |
7638218 |
Appl. No.: |
09/829284 |
Filed: |
April 9, 2001 |
Current U.S.
Class: |
52/698 |
Current CPC
Class: |
E21D 21/0026
20130101 |
Class at
Publication: |
52/698 |
International
Class: |
E04B 001/38; E04C
005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2000 |
DE |
100 17 761.1 |
Claims
What is claimed is:
1. A tubular anchor to be inserted into a bore formed in a
constructional structure, comprising a hollow anchor body (1); and
a trapezoidal thread-shaped profile (2) provided on at least a
portion of an outer surface of the anchor body (1) and having a
crest region (3) and a root region (4) both extending parallel to a
longitudinal axis of the anchor body (1), wherein at least flanks
of a trapezoidal cross-section of the profile (2) remote from an
end of the anchor body (1) facing in a setting direction are
inclined with respect to the longitudinal axis of the anchor body
(1) at an angle (.alpha.) from 10.degree. to 45.degree..
2. A tubular anchor according to claim 1, wherein an axial extent
(a) of the root region (4) corresponds to from 0.04 to 0.1 times of
a diameter (d) of the anchor body (1).
3. A tubular anchor according to claim 1, wherein an axial extent
of the crest region (3) corresponds to from 0.04 to 0.1 times of a
diameter (d) of the anchor body (1).
4. A tubular anchor according to claim 1, wherein an axial extent
(b) of the crest region (3) corresponds to an axial extent (a) of
the root region (4).
5. A tubular anchor according to claim 1, wherein an the profile
(2) has, in a direction transverse to the longitudinal axis of the
anchor body (1), a height (h) corresponding to from 0.25 to 0.75
times of a wall thickness of the anchor body (1).
6. A tubular anchor according to claim 1, wherein the trapezoidal
thread-shaped profile (2) has a pitch from 10 mm to 40 mm.
7. A tubular anchor according to claim 1, wherein profile-forming
trapezoidal thread is a double thread.
8. A tubular anchor according to claim 1, wherein the trapezoidal
thread-shaped profile (2) extends over an entire length of the
anchor body (1).
9. A tubular anchor according to claim 1, wherein the trapezoidal
thread-shaped profile (2) has an anti-stick coating (5) for
preventing adhesion of a mortar mass to the profile (2).
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a tubular anchor, in
particular, for mine and tunnel construction for insertion in a
bore formed in a mine or tunnel gallery, with the tubular anchor
having a hollow anchor body, and a trapezoidal thread-shaped
profile provided on at least a portion of an outer surface of the
anchor body and having a crest region and a root region both
extending parallel to a longitudinal axis of the anchor body.
[0003] 2. Description of the Prior Art
[0004] Tubular anchors are generally known. They function primarily
as roof bolts for stabilization of walls of hollow spaces such
tunnels, galleries and the like. They are used primarily for
securing to each other following each other, in a direction
transverse to the wall, the wall-forming strata. In many cases, the
mechanical characteristics of the layers, which lie in immediate
vicinity of the wall surface, in particular, their supporting
resistance, changes as a result of formation of a hollow space.
Therefore, these layers need be secured to further located,
undamaged or unaffected layers or strata. The tubular anchor is
primarily secured in a bore with a mortar mass. As a mortar mass,
e.g., a two-component adhesive, in particular, an epoxyacrylate
resin with a hardener, is used. The mortar mass is intermixed and
hardens, anchoring the tubular anchor in the bore. The end of an
anchor rod, which projects from the bore, is, in most cases,
provided with a thread. A constructional component is secured on
the projected end of the anchor rod with a nut.
[0005] A tubular anchor of the type discussed above is disclosed,
e.g., in German Utility model DE 29 501 638. The known tubular
anchor is formed of an anchor body provided with a shaped profile.
The shaped profile is formed as a single trapezoidal thread. This
insures the possibility to use the tubular anchor with a
conventional drilling tool.
[0006] The drawback of the known tubular anchor consists in that
the holding value of the known anchor is substantially reduced in
case fissures or cracks are present in the bore region.
[0007] Accordingly, an object of the present invention is to
provide a tubular anchor with such a profile that would insure a
high holding value even in a cracked constructional component.
[0008] Another object of the present invention is to provide a
tubular anchor that can be easily and rapidly set in a bore.
SUMMARY OF THE INVENTION
[0009] These and other objects of the present invention, which will
become apparent hereinafter, are achieved by providing a tubular
anchor with trapezoidal thread-shaped profile in which at least the
flanks of a trapezoidal cross-section of the profile remote from an
end of the anchor body facing in a setting direction are inclined
with respect to the longitudinal axis of the anchor body at an
angle from 10.degree. to 45.degree..
[0010] The foregoing profile of the thread insures a secondary
expansion of the inventive tubular anchor. The secondary expansion
takes place, in particular, when the tubular anchor is provided
with an anti-stick coating or the mortar mass is so formed that no
adhesion occurs between the mortar mass and the anchor. Further,
the foregoing inclination of the profile flanks favorably
influences the setting process. The inclination of the flanks,
together with high cohesion of the mortar mass insures retention of
the inventive tubular anchor in a bore of a constructional
component during the setting process. Thereby, the holding time,
during which the tubular anchor should be stably held in the bore
until the mortar mass becomes almost completely hardened, is
eliminated. An optimal secondary expansion is obtained when the
flanks are inclined at an angle of about 20.degree.. To insure a
simple formation of the trapezoidal thread, advantageously, both
opposite flanks have the same inclination.
[0011] In order to insure a sufficiently high holding value, the
axial extent of the root region is so selected that it corresponds
to from 0.04 to 0.1 times of the diameter of the anchor body. With
the tubular anchor being set, the mortar mass fills the space
between the flanks. Upon application to the anchor of a load, which
acts in a direction opposite to the setting direction, shear forces
act on the mortar mass. Therefore, the cross-section of the mortar
mass, which fills the space between the flanks, plays a decisive
role in insuring a lasting connection between the tubular anchor
and the mortar mass. This cross-section is determined to a
significant extent by the axial extent of the root region, which
axial extent is determined by the diameter of the anchor body. The
diameter of the anchor body, in turn, depends on the applied
maximal load.
[0012] The axial extent of the crest region is also so selected
that it corresponds to from 0.04 to 0.1 times of the anchor body
diameter. Thereby, the profile of the anchor can withstand
sufficiently high shear forces generated by the load resulting from
tightening of the nut or the like.
[0013] The height of the profile in the radial direction,
advantageously, corresponds to from 0.25 to 0.75 times of the wall
thickness of the anchor. This insures an economical manufacturing
of the profiled tubular anchor.
[0014] The threaded profile has, preferably, a pitch from 10 mm to
40 mm. This insures a uniform distribution of the mortar mass
between the bore wall and the profile of the tubular anchor. In
addition, the profile formed according to the present invention,
increases the holding value, with which the inventive tubular
anchor is held in the constructional component, insuring, at the
same time, an adequate removing rate with which the drilling dust
is removed. Optimally, the thread pitch should be about 15 mm.
[0015] Advantageously, the profile thread is formed as a double
thread. This further increases the removing rate, with which the
drilling dust is removed, which rate is substantially higher than
with a single thread profile. Furthermore, the undercut surface,
which the mortar mass engages, also increases twofold in comparison
with a single thread profile. When the inventive tubular anchor has
to meet particularly stringent requirements, a triple or multiple
thread profile can be used.
[0016] Advantageously, the profile extends over the entire length
of the anchor body. In this case, the thread profile serves as
holding means for a mortar mass and as load application means for,
e.g., a nut. This permits to avoid the use of a separate thread for
forming the load application means.
[0017] The novel features of the present invention, which are
considered as characteristic for the invention, are set forth in
the appended claims. The invention itself, however, both as to is
construction and its mode of operation, together with additional
advantages and objects thereof, will be best understood from the
following detailed description of preferred embodiments, when read
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Single FIGURE of the drawings shows a longitudinal,
partially cross-sectional view of a tubular anchor according to the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] A tubular anchor according to the present invention, which
is shown in the drawing, has a hollow tubular anchor body 1
provided on its outer surface, at least partially, with a
thread-like profile 2. The thread-like profile 2 is formed as a
trapezoidal thread with a crest region 3 and a root region 4
extending both parallel to the longitudinal axis of the anchor body
1. Each root region 4 is connected with two adjacent crest regions
3 by respective flanks. The length of each of the crest region 3
and the root region 4, which is measured in the axial direction,
corresponds approximately to 0.04-0.1 of the diameter d of the
anchor body. The inclination angle .alpha. of each flank with
respect to the axial direction amounts approximately to
10.degree.-45.degree..
[0020] The thread is formed as a double thread with a pitch of
about 15 mm. The thread extends over the entire length of the
anchor body 1 and functions as retaining means for a mortar mass,
on one hand, and as load application means for, e.g., a nut, on the
other hand. The height h of the thread measured in a direction
transverse to the axial direction corresponds approximately to
0.25-0.75 of the thickness of the anchor body wall.
[0021] Though the present invention was shown and described with
references to the preferred embodiments, such are merely
illustrative of the present invention and are not to be construed
as a limitation thereof, and various modifications of the present
invention will be apparent to those skilled in the art. It is,
therefore, not intended that the present invention be limited to
the disclosed embodiments or details thereof, and the present
invention includes all variations and/or alternative embodiments
within the spirit and scope of the present invention as defined by
the appended claims.
* * * * *