Sleeve anchor

A sleeve anchor for use in a pre-drilled hole in concrete, masonry and the like includes a bolt with threaded outer end for receiving an internally threaded pressure member, e.g., a nut. The inner end defines a shank terminating in a head of diameter greater than the shank. The head has a tapered wedge-forming shoulder adjoining the shank. A sleeve is disposed concentrically upon the bolt and includes a collar extending along a threaded portion of the bolt at its upper outer end is disposed for receiving longitudinal pressure toward the inner end of the bolt generated by tightening of the nut. An inner portion of the collar is of petalform configuration, having three petals extending along the shank in closely-spaced side-by-side relationship. The petals are joined at proximal ends to the collar by respective pillars each of narrow arcuate extent, providing windows between the pillars of greater arcuate extent. The pillars have distal ends which contact and ride up the shoulder for radially outward expansion of the sleeve upon tightening of the pressure member. The distal ends of the petals each have a lobular prominence whereby together they form in section an enhanced hexagon or trilobular configuration. Further, each petal forms at its proximal end a singular ear along a leading side edge, formed by an outwardly extending corner portion, for providing gripping antirotational engagement of interior surfaces of the hole upon insertion of the anchor. The sleeve is formed of resilient, ultimately deformable metal to permit torsional distortion of the pillars upon tightening of the pressure member, causing foreshortening of the sleeve to provide pre-loading of the anchor within the hole.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention relates generally to expansion-type bolts, and more 
particularly, to a sleeve anchor of the type having a bolt and an 
expansion sleeve longitudinally shiftable upon tightening of the bolt to 
wedge the sleeve anchor within a hole or recess in rock, concrete, solid 
concrete block, hollow concrete block, grout-filled hollow concrete block, 
mortar joints, brick, masonry or other like material. 
A sleeve anchor is a species of anchor bolts, wherein a metal sleeve 
extending along a bolt is caused to shift upon tightening of the bolt for 
tightly expanding within a hole bored into concrete, concrete blocks, 
masonry and various materials of this character. The anchor is thus used 
for securement of extrinsic structures, such as building materials, 
shelving, structural members and so forth. Such devices are customarily 
employed in many fields, including construction as well as for the 
fastening of machinery and equipment to masonry or rock structures. 
As conventionally configured, the bolt includes a wedge-defining portion 
which causes outward expansion of the sleeve upon tightening of the bolt. 
An example is disclosed in Lerich U.S. Pat. No. 3,750,526. Also 
representative of the prior art are Lerich U.S. Pat. No. 3,750,519 and 
Oettl U.S. Pat. No. 4,334,813. 
The key element in a sleeve anchor is the expansion sleeve which compresses 
the concrete, or other hard material as the bolt or so called stud is 
partially withdrawn from the hole upon tightening of a nut, inasmuch as 
the expansion sleeve configuration is determinative of the performance 
character of the anchor in the areas of setting of the anchor within the 
hold, tensile performance (i.e., the anchoring capability or ultimate 
tensile strength when secured), and ultimate failure mode. 
Heretofore, conventional sleeve anchors have exhibited difficulties in 
enabling the sleeve anchor to be installed and to be "set" in the hole. 
Conventionally, the sleeve provides a springy slip fit in a typical hole 
and such does not provide enough friction to prevent the sleeve from 
rotating within the hole upon tightening, as well as sometimes permitting 
the anchor to slide out of the hole. Further, in hollow concrete block 
installations, where little of the exposed surface material of the sleeve 
will bear against the internal surfaces of the hole, slippage is 
frequently encountered, resulting in substantial installation 
difficulties. Matters are rendered more difficult by the need to provide 
for both resistance to rotation as well as withdrawal for the anchor when 
originally inserted into the hold, prior to tightening. 
A further requirement and desirability for structural anchors is the 
ability to pre-load; that is, to positively clamp a fixture to the 
substrate or base material in which the hole is provided. Without 
pre-loading with development of clamping force for so affixing the fixture 
to the substrate, any tensile load upon the structure will result in 
immediate fixture looseness and/or strain. When pre-loading is to be 
provided, the tensile force developed or exerted by the structure upon the 
anchor, as tightened, must exceed the pre-load in order for looseness 
and/or strain to occur. The ability to pre-load beyond the normal working 
load of a sleeve anchor ensures that it will provide proper structural 
performance. In other words, there should not result any looseness or 
strain at normal working loads. 
Accordingly, among the several objects of the present invention may be 
noted the provision of an improved sleeve anchor; the provision of such an 
anchor which, when inserted in a hole in concrete, masonry or other 
building materials, will set reliably therein to prevent rotation or 
withdrawal until tightening of the anchor; the provision of such an anchor 
which provides pre-loading upon tightening to positively clamp a fixture 
to the substrate or base material, namely the concretee, masonry, or other 
building material receiving the anchor, and providing pre-loading beyond 
the normal working load of the sleeve anchor so that tensile forces must 
exceed the pre-load capability for looseness and/or strain to occur; the 
provision of such a sleeve anchor which provides pre-loading such as 
heretofore normally associated only with stud anchors; the provision of 
such a sleeve anchor having far greater pre-loading than heretofore 
possible; the provision of such a sleeve anchor which has a higher 
ultimate tensile strength than other sleeve anchors, and particularly 
through use of an expansion sleeve that develops the full strength of the 
substrate material, such as concrete, masonry and so forth, and the 
provision of such a sleeve anchor having a sleeve uniquely configured for 
development of maximum compressive forces for confirmation with the 
circumference of the stud thereof for reliable and secure maintenance 
within the substrate hole upon tightening; and the provision of such a 
sleeve anchor which is not prone to catastrophic anchor failure, reliably 
providing ultimate tensile value even under strain. 
Briefly, a sleeve anchor in accordance with the invention for use in a 
pre-drilled hole in concrete, masonry and the like, comprises a bolt 
including a threaded outer end for receiving an internally threaded 
pressure member, such as a tightening nut, and an inner end defining a 
shank extending from the outer end and terminating in a head of greater 
diameter than the shank. The head has a tapered wedge-forming shoulder 
adjacent to the shank, the head constituting the leading edge of the 
anchor for being inserted in the hole with the threaded outer end 
extending from the hold for receiving the tightening nut for tightening by 
its rotation. A sleeve is disposed concentrically on the bolt. The sleeve 
is formed to include a collar positioned concentrically around the bolt 
and extending along a portion of its threaded portion at the upper end 
thereof. The collar is disposed for receiving longitudinal pressure toward 
the inner end of the bolt generated by tightening of the tightening screw. 
The collar includes an inner portion of petalform configuration comprising 
three petals extending along the shank and closely-spaced side-by-side but 
separate relationship to surround the shank. The petals are joined at 
proximal ends to the collar by respective pillars, each of narrow arcuate 
extent, to provide windows between the pillars. Such windows are of 
arcuate extent greater than each pillar. Distal end of the petals contact 
the end of the shoulder such that upon tightening of the pressure 
tightening screw, the petals are caused to ride up the shoulder for 
radially outward expansion of the sleeve within the hole. The distal ends 
of the petal each form in section a central arc and straight portions 
extending from opposite ends of the arc thereby to provide for each petal 
a vee-shaped lobal prominence of approximately 90.degree. included angle, 
whereby the distal ends of the petals together form in section an enhanced 
hexagon of trilobular configuration. Each petal forms at its proximal end 
a single ear disposed along the leading side edge thereof, the ear being 
constituted by an outwardly extending corner portion of the respective 
petal. The ears provide gripping anti-rotational engagement of interior 
surfaces of the hole upon insertion of the anchor into the hole to prevent 
rotation of the sleeve therein upon rotation of the tightening screw. The 
sleeve is formed of resilient ultimately deformable metal to permit 
flexing of the ears and the distal ends of the petals to permit torsional 
distortion of the pillars upon continued tightening of the tightening 
screw caused by pressure between the opposite ends of the sleeve. Such 
causes pre-loading of the anchor within the hole. 
Other features will be in part apparent and in part pointed out 
hereinbelow.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, indicated generally at reference numeral 10, the 
new sleeve anchor comprises a bolt 12 including a threaded outer end 14 
and an inner end 16 defining a shank extending from the outer end and 
terminating in a head 18 of diameter greater than shank 16, the head 
having a tapered wedge-forming shoulder 20 adjoining the shank. Head 18 
constitutes the leading end of anchor 10 for being inserted into a hole. 
Referring to FIG. 2, such a hole of a substrate material is designated at 
22, being a bore, for example, as drilled into a concrete block, masonry, 
brick, or any of various hard substrate materials 23 in which sleeve 
anchors of the type with which the invention is concerned are utilized for 
the purpose of anchoring a structure, such as that designated at 24, to 
the substrate by tightening of a pressure member such as a nut 26 threaded 
upon the outer end 14 of bolt 12. For this purpose, threads are provided 
over a majority of the length of the bolt 12 to accommodate a relatively 
wide latitude for movement of bolt 26 upon tightening, and as 
conventional, a washer as at 28 may be used, as well as spacers (not 
shown) or the like for providing suitable accommodation between the bolt 
26 or other pressure member, the structure 24 and the elements of the 
sleeve anchor. 
Fitted upon the bolt 12 is a sleeve 30 which, as explained below, will be 
caused to shift longitudinally upon bolt 12 and to be expanded by movement 
upwardly onto shoulder 20 for pressure engagement of the interior surfaces 
of hole 22. Such engagement tightly locks the sleeve anchor 10 within the 
hole for permitting the development of high tensile forces upon the sleeve 
anchor and for tightly affixing the structure, as indicated at 24, to 
substrate material 23. 
For this purpose, shoulder 20 is formed at an angle of preferably about 
15.degree. to the longitudinal axis of bolt 12. Sleeve 30 is disposed 
concentrically upon bolt 12, being formed from a single blank, as stamped 
from a sheet of strong, resilient, ultimately deformable material such as 
steel alloy and then rolled into a cylindrical configuration. Such results 
in a seam 32 between adjacent edges, and such seam does not require 
closure or other union of the opposing edges of the material. In any 
event, there is provided for the sleeve a collar 34 extending along a part 
of the bolt threaded portion 14 and disposed for receiving longitudinal 
pressure toward the inner end of bolt 12 upon tightening of nut 26. The 
sleeve is also provided with an upper portion 36. It is of petalform 
configuration, being comprises of three petals 38 which extend along shank 
16 in closely-spaced side-by-side but separate relationship to thereby 
surround shank 16. Petals 38 are joined at proximal ends to collar 34 by 
respective pillars or stauchions 40 each of narrorw arcuate extent and 
rectangular section (FIG. 5). As viewed in FIG. 5, such pillars provide 
windows, as at 42. Such windows are of arcuate extent greater than each of 
the pillars. Distal ends of petals 38 contact the shoulder 20 when sleeve 
30 is urged toward head 18 of the bolt, whereby upon tightening of nut 26 
or other pressure member, petals 38 are caused to ride up on shoulder 20 
for radially outward expansion of the sleeve within the hole 22. 
The distal ends of the petals are uniquely configured. Referring to FIG. 4, 
the distal end of each such petal 38 forms in section a central arc 44 and 
straight portions 46, 46' extending from opposite ends of the arc portion 
thereby to provide for each petal 38 a vee-shaped lobal prominence of 
approximately 90.degree. included angle. Further, an angle of 30.degree. 
is formed between proximal, adjacent straight portions of the adjacent 
petals. Accordingly, as viewed in section in FIG. 4, the distal ends of 
the petals 38 together form in section an enhanced hexagon of trilobular 
configuration. This provides for each of petals 38 distal corners, as at 
48, 48', serving to provide gripping antirotational engagement of surface 
of shoulder 20 to prevent rotation of bolt 12 upon tightening of nut 26. 
Further, there is provided between each central arc portion of the petal 
38 and bolt 12 a slight spacing, as shown for example at 50, serving to 
create for each distal portion of the petals a lobular prominence of 
springy character for more tightly gripping of the interior surfaces of 
hole 22 upon insertion of the sleeve anchor. 
Each petal 38 is provided with means for providing gripping antirotational 
engagement of interior surfaces of the hold upon insertion of the sleeve 
anchor therein. For this purpose, each petal 38 is provided with an ear in 
the form of an outwardly extending corner portion 52 on its leading edge, 
i.e., the edge of the petal in the direction of advancing rotation of nut 
26 upon tightening, such as would tend inherently to urge rotation of 
sleeve 30 within the hole, and which rotation will be resisted by such 
ears 52 as the sleeve anchor is inserted in the hole such by tending to 
force each such ear 52 into the substrate material. Each ear 52 is created 
by an upsetting of the sleeve material upon a line of fold 54, which is 
skewed from the longitudinal axis of the sleeve anchor. Insertion of the 
bolt thus will intrinsically tend to force a slight resilient deflection, 
at least, of each such ear 52 upon its respective line of fold 54 as the 
anchor is inserted. In FIGS. 2 and 3, representative digging into the 
substrate material 23 is illustrated in at least slightly exaggerated 
fashion. 
Similarly also, there is flexing of each petal 38 upon the narrow pillars 
40 as tightening of nut 26 forces the distal ends of the petals up onto 
the surfaces of shoulder 20. 
Accordingly, it is seen that, upon tightening of nut 26, the sleeve anchor 
may be caused to be affixed securely in the substrate hole 22 by rotation 
of nut 26 or other tightening member, and the wedging action of shoulder 
20 causes the distal ends of sleeve 30 to be forced radially outwardly, as 
well as longitudinally toward head 18, until the distal ends of the 
petals, such as shown in FIG. 2 at 56, until wedged tightly against and/or 
into the substrate material as shown. 
FIG. 2 illustrates that such tightening of the sleeve anchor may occur even 
though the structure 24 to be secured upon tightening of the sleeve anchor 
is not touching the substrate material. For purposes of illustration, 
therefore, there is shown at 58 a gap between structure 24 and substrate 
23, such as would occur if structure 24 were loaded with weight, or were 
flexed outwardly from the substrate. 
Upon tightening, the new sleeve anchor provides that is termed pre-loading 
for positively clamping the structure or other fixture 24 tightly to the 
substrate or base material 23. Flexion of petals 38 and wedging by 
shoulder 20 tightly compresses the distal portions of the petals for 
locking the anchor reliably in place within hole 22 to set the anchor. 
However, upon continued tightening of nut 26 or other tightening means, 
sleeve 30 is compressed by washer 28 (and spacers may be use if desired) 
for providing longitudinal pressure toward the inner end of the sleeve 
anchor. Such pressure beween the opposite ends of the sleeve, the inner 
end being tightly clamped within the bore as illustrated, and the other 
end being compressed by tightening of nut 26, causes selective torsional 
distortion of pillars 40 as shown in FIG. 3 and with resultant 
foreshortening of sleeve 30 to permit nut 26 to draw structure 24 tightly 
against substrate 23, as illustrated. In this regard, pillars 40 do not 
simply collapse, but rather are caused to twist or undergo torsional 
distortion into an S-shaped, serpentine form, as illustrated, as torque is 
applied through the washer 28 tending to cause rotation of collar 34. Such 
torisonal distortion is progressive. 
The resultant pre-loading is such that any tensile force applied to the 
anchored sleeve anchor, as transferred through the load or structure 24, 
must exceed the pre-load force thus provided in order for looseness and/or 
strain to occur. The new sleeve anchor thereby assures the ability to 
pre-load beyond the normal working load of the fastened sleeve anchor to 
ensure proper structural performance and to preclude looseness or strain 
at normal working loads. The relatively narrow pillars 40, in relation to 
windows 42, gives assurance that such pre-loading is selective and 
controlled, so that it may occur in a progressive manner to accomodate a 
substantial variation in spacing between the load or structure 24 and 
substrate 23 as may be found in practice. In effect, a pre-loading 
distance is created which is equal to the height (transverse to the 
arcuate extent) of the window 42 adjacent to each pillar, less the width 
(arcuate extent) of the pillar. Such a pre-loading characteristic is 
thereby achieved for the first time in a sleeve anchor. Heretofore, it has 
been conventional to regard only stud anchors as capable of providing of 
pre-loading. 
A further advantage is apparent from consideration of FIG. 4, wherein the 
enhanced lobular characteristic of each petal 38 is illustrated. The 
lobular prominences for each petal provide a unique cross-section in the 
area where the anchor sleeve must expand when tightened, and thereby in 
the area where compression will occur within the concrete or other 
substrate material 23. The lobal prominences, with their 90.degree. 
included angle, are believed to require additional force when being forced 
into conformation with the circumference of shoulder 20 and head 18 upon 
tightening, thereby causing increased radial pressure and compression 
within the material, such as concrete, and so resulting in increased 
ultimate tensile strength. There is, accordingly, less tendency for the 
petals to "iron out" upon tightening, such as may occur with conventional 
anchors. 
Upon insertion, the ears 52 of the sleeve also provide an additional 
advantage since they act, in effect, like barbs and flex and fold upon the 
lines of fold 54 so that they enter and travel into the hole easily as the 
sleeve anchor is inserted. When such ears bite into the material, they not 
only prevent rotation of the expansion sleeve about the longitudinal axis 
but also act to prevent withdrawal of the sleeve anchor from the hole. 
Such feature is especially important and advantageous when the new sleeve 
anchor is used for hollow masonry block applications where the rear side 
of the hole may tend to be blown out or enlarged by the impact of a hammer 
drill bit, providing a cone-shaped hole rather than the uniform bore 
illustrated in the drawings. In practice, it is sometimes found that the 
damage to such a hole in hollow masonry block installations is sufficient 
to leave only enough material to be engaged by ears 52 by which the new 
anchor is thereby held sufficiently affixed within the hole to permit 
subsequent tightening to occur. 
In the failure mode, the new sleeve anchor provides higher ultimate tensile 
strength than conventional anchors. Such performance is verified by ASTM 
testing. The performance is due in larger part to the provision of 
expansion sleeve 30 which develops the full strength of the substrate 
material, such as concrete, and obviates pull-through failures. The 
ultimate failure mode provided for the new sleeve anchor is the most 
desirable, namely a spall cone failure, where concrete is the substrate 
material. This type of failure demonstrates the maximum holding power 
possible, namely the full strength of the substrate material. Heretofore, 
maximum holding power in this type of failure was associated only with 
stud type anchors. In general, the new sleeve anchor provides little slip, 
if any, prior to failure. Such no-slip performance permits the use of the 
new sleeve anchor as a structural anchor, whereas heretofore only stud 
type anchors characteristically have been used for structural anchoring. 
In view of the foregoing, it will be seen that the several objectives of 
the invention are achieved and other advantages are attained. 
Although the foregoing includes a description of the best mode contemplated 
for carrying out the invention, various modifications are contemplated. 
As various modifications could be made in the constructions herein 
described and illustrated without departing from the scope of the 
invention, it is intended that all matter contained in the foregoing 
description or shown in the accompanying drawings shall be interpreted as 
illustrative rather than limiting.