Note: Descriptions are shown in the official language in which they were submitted.
CA 02555118 2006-08-01
METHOD OF FORMING AN EXPANSION MOUNTING
SLEEVE
AND THE PRODUCT THEREOF
FIELD OF THE INVENTION
The present invention relates to an expansion inounting sleeve,
and mot=e particularly to an expansion tnounting sleeve that can
be driven or mounted in a hole on a wall and be expanded to
firmly locate in the hole when a matching ready-made bolt is
screwed thereinto.
BACKGROUND OF TI-IE INVENTION
The currently cominercially available expansion bolt
assemblies and associated niounting nuts are manufactured in
diffei-ent manners, such as injection molding plastic -naterials,
casting zinc, lead, or aluminum alloys, turning cutting rods to
form bolts and cold forging pipes to form expansion sleeves,
and cold forging rods to fornl bolts and stamping sheet inetal to
form expansion sleeves.
All these conventional expansion bolt assemblies and mounting
nuts require complicate processing apparatus and a lot of parts,
2 5 as well as relatively high quantity of material to produce them.
And, the conventional expansion bolt assemblies or mounting
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nuts tend to fail in fastening because the expansion sleeves
thereof fail to expand as desii-ed, causing the bolts or the
mounting nuts to idle without being tightened against the
expansion sleeves.
Fig. I shows a first conventional expansion mounting screw
assembly formed from a plastic mater-ial. The plastic
expansion screw assembly has the advantages of low material
cost and resistant to rust, but requires high cost foi- molds and
has low production speed. The plastic expansion screw
assembly also has low rigidity as well as small engaging
friction with wall, and accordingly, weak tensile strength and
bearing strength. Therefore, the expansion sleeve of the
plastic expansion mounting screw assembly tends to be easily
pulled out of the wall.
The conventional expansion inounting nuts cast by alloys
requii-e longer tiine to produce and involve a lot of tools and
processing procedui-es, including tapping, assembling, etc.
2 0 The major disadvantages of the cast alloy expansion mounting
nuts include a limiteci range of' usable inaterials and a
mechanical strength lower than the pi-oducts made of a
cold-rolled metal sti-ip inaterial.
Fig. 2 shows a conventional turning cut expansion sleeve or
moutiting nut for an expansion bolt assembly, which requires
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longei- time to produce a pi-imary body and form gi-ooves on the
primary body in secondary processing. A lot of material is
waste in turning cut. The turning cut expansion sleeve must
be used with a taper-headed bolt to achieve the expansion of
the sleeve. Another disadvantage is the tuning cut expansion
sleeve is often made of high speed steel, which has ai-esistance
too high to allow successful expansion of the sleeve, resulting
in idling of the bolt or the nut against the expansion sleeve
without effectively achieving the fastening operation. This
type of expansion bolt asseinbly is therefore not suitable for
use in assembling work pieces, erecting construction works, or
assembling DIY (do-it-yourself) products.
A conventional expansion bolt assembly includirig a
cold-for-ged metal bolt and a tui-ning cut nietal sleeve is
currently most widely used in civil works, restoration, hanging,
equiptnent installation and positioning, etc. The bolt is
taper-headed, and the sleeve is processed to foi-m slits thereon.
This type of expansion bolt asseinbly also includes a flat wash,
an expansion washer, and a nut, and may be handled in two
ways. In the first way, first moves the nut to a rear end of the
bolt, then, drive the expansion bolt assembly into a hole
pre-drilled on a wall surface, and then tighten the nut, so that
the taper-headed bolt expands the foi-ced forward slit sleeve.
The sleeve of this type of expansion bolt assembly frequently
fails to expand due to a high resistance, i-esulting in idling
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when the nut is tightened against the bolt. In the second way,
fit-st move the nut to a rear end of the bolt, then, drive the
expansion bolt assembly into a hole pre-dt-illed on a wall
surface, and then release the nut and the expansion washei- from
the bolt. Thereafter, use a sleeve larger tlian the bolt to force
the slit metal sleeve forward, so that tapered head of the bolt
forces the slit metal sleeve to expand and achieve the purpose
of tightly fastening the expansion bolt assembly to the wall.
Ho~vever, since the pre-drilled liole is often incorrect in depth,
lo or biased, or too soft at the bottom thereof, the metal sleeve
tends to inove too inuch forward oi- the bolt tends to idle. In
addition, tliis type of expansion bolt assembly includes a lot of
associated parts and t-equires good skill to handle it to avoid
failut-e in rnoutiting it.
Fig. 3 shows a further conventional expansion bolt assembly
that is an iinproved version of the above-desci-ibed type of
expansion bolt assembly, and mainly includes a cold-forged
bolt and an expansion sleeve fortned by stamping. Forrnitig
the expansion sleeve by statnping may advantageously reduce
the tnanufactut=ing cost and lower the resistance to expansion so
as to increase the engaging friction of the sleeve with the wall.
The stamped expansion sleeve is expanded by forcing or
sct-ewing the taper-headed bolt into the sleeve. Tliis improved
type of expansion bolt assembly still has the drawbacl<s of
including too many parts and requit-ing longer time to assemble
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the parts together.
It is therefore tried by the inventor to overcome the drawbacks existed in the
conventional expansion bolt asseinblies by developing an independent
expansion mounting sleeve formed by stamping using progressive dies through
simple and less processing procedures, so that the expansion mounting sleeve
has the advantages of requiring less material to form it, having an internally
threaded bore to ensure tight screwing of a matching ready-made bolt into it
to
expand the sleeve without the risk of idling, having a plurality of
differently
sized and shaped and outward protruded engaging teeth to ensure fiim and
frictional contact of the expanded sleeve with the wall without the risk of
becoming loosened or being pulled out, and largely reducing the tools and
costs
for manufacturing it.
SUMMARY OF THE INVENTION
It is desirable to provide an expansion mounting sleeve that can be quickly
manufactured using a variety of materials with reduced material quantity
through simple processing procedures.
It is also desirable to provide an expansion mounting sleeve that can be
conveniently used with a ready-made bolt having matching length, size, and
screw threads; so that the apparatus and tools needed to produce the expansion
mounting sleeve can be largely simplified.
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It is further desirable to provide an expansion mounting sleeve that can be
easily handled by a person with general skill to successfully coinplete the
fastening work within a shortened time period.
It is still further desirable to provide an expansion mounting sleeve that
could
be efficiently driven into or mounted in a wall without the risk of becoming
loosened.
To achieve the above and other objects, the expansion mounting sleeve
described herein includes a forward tapered cylindrical body formed by
stamping and pressing a cold-rolled metal strip to define an internally
threaded
tapered bore. A plurality of engaging teeth having different heights and
shapes
are formed to project from the cylindrical body. After the sleeve has been
driven into or mounted in a hole pre-drilled on a wall, a ready-made bolt
having
length, size, and screw threads matching the threaded bore of the cylindrical
body may be screwed into the bore and thereby expands the forward tapered
cylindrical body of the sleeve, causing the engaging teeth to extend outward
and tightly engage with the wall in the hole, so as to firmly hold the
expansion
mounting sleeve in place in the hole.
The expansion mounting sleeve described herein is formed by stamping and
pressing using progressive dies. A method of manufacturing the expansion
mounting sleeve includes the following steps:
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(a) preparing a piece of material having dimensions needed to manufacture the
expansion mounting sleeve, forming at least two tapered areas on the material,
and defining thread forining areas on the material;
(b) pressing the material to form more than one slot in the thread forming
areas,
such that the slots are parallel to an axis of the material;
(c) pressing the material to form at least one barb and/or more than one
outward protruded engaging teeth in each of the tapered areas, the engaging
teeth have heights that increase toward a front end of the material;
(d) pressing the material to form screw threads of a desired size in the
thread
forming areas;
(e) pressing the material to form at least one degree of bending at the
tapered
areas;
(f) pressing the thread forming areas to form a U-sectioned shape;
(g) further curling the thread forming areas into a circular cross section;
and
(h) trimming off unnecessary temporary connecting material belt to complete
one unit of the expansion mounting sleeve.
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Accordingly, in one aspect of the invention there is provided a method of
forming an expansion mounting sleeve by stamping using progressive dies,
comprising the steps of
preparing a material having dimensions needed to form said expansion
mounting sleeve, forming at least two tapered areas on the material such that
the at least two tapered areas extend longitudinally in a common direction
along a single axis of the material, and defining thread fonning areas on the
material;
pressing the material to form more than one slot in said thread forming areas;
pressing the material to form at least one barb and engaging tooth in each of
said tapered areas;
pressing the material to form screw threads of a desired size in said thread
forming areas;
pressing the material to bend said tapered areas;
pressing said thread forming areas to form a U-sectioned shape;
further curling said thread forming areas into a cylindrical body having a
circular cross section; and
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trimming off unnecessary temporary connecting material belt to complete one
unit of said expansion mounting sleeve.
According to another aspect of the invention there is provided an expansion
mounting sleeve, comprising a cylindrical body defining an internally threaded
bore; said cylindrical body and said bore being tapered from near a rear end
toward a front end, and said cylindrical body including at least one engaging
tooth at the tapered portion of said cylindrical body, each engaging tooth
protruding away from an outer wall surface from a bend lying on an axis
extending away from the rear end toward the front end along the bore.
BRIEF DESCRIPTION OF THE DRAWINGS
The structure and the technical means adopted by the present invention to
achieve the above and other objects can be best understood by referring to the
following detailed description of the preferred embodiments and the
accompanying drawings, wherein
Fig. 1 is a perspective view of a conventional expansion mounting screw
assembly;
Fig. 2 is a perspective view of a sleeve of another conventional expansion
bolt
assembly;
Fig. 3 is a perspective view of a further conventional expansion bolt
assembly;
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Fig. 4 is a pei-spective view ol- an expansion inountinb sleeve
accoi-ding to a preferred einbodiment of the present invention;
Fig. 5 is a perspective view of the expansion mounting sleeve
of Fig. 4 with a bolt screwed thei-einto;
Figs. 6 to 9 show the manner of screwing a bolt into a wall
surface via the expansion n-iounting sleeve of the pc-esent
invention;
Figs. IOA to IOH show the steps included in a method of
forming the expansion mounting sleeve of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS
Please refer to Fig. 4 that is a perspective view showing an
expansion mounting sleeve 10 according to a preferred
embodinlent of the present invention. A bolt 40 having
suitable length, size, and screw threads for screwing into the
expansion mounting sleeve 10 is also shown in Fig. 1. Fig. 5
is a perspective view showing the expansion mounting sleeve
10 with the bolt 40 sci-ewed thereinto. As shown, the
expansion mounting sleeve 10 includes a substantially straight
cylindrical body fornied by curling a metal material. A
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locking means 60 is formed at a joint of two edges of the curled metal
material
near a rear end of the cylindrical body of the expansion mounting sleeve 10 by
way of stamping. The locking means 60 includes an ear section 61 protruded
from one of the two joining edges, and a recess section 62 formed on the other
joining edge opposite to the ear section 61 for engaging with the latter and
thereby lock the two joining edges together (also refer to FIG. l0A). The
cylindrical body of the sleeve 10 defines a bore 12, which is internally
provided
with a plurality of screw threads 14. The cylindrical body and the bore 12 of
the sleeve 10 are tapered toward a front end the sleeve 10, and at least one
engaging tooth 16 is projected from an outer surface of the sleeve 10. In the
illustrated embodiment, a plurality of engaging teeth 16, 17, 18 having
different
lengths and shapes are projected from the outer surface of the sleeve 10. As
shown in the figures, each one of the engaging teeth 16, 17, 18 protrudes away
from an outer wall surface of the cylindrical body from a bend lying on an
axis
extending away from the front end toward an opposite rear end along the bore
Moreover, one or more stopping tooth elements 20 are forrned on the
cylindrical body of the sleeve 10 (see FIG. 6).
FIGS. 6 to 9 are sectional views and partially sectioned views showing the
manner of fastening a bolt to a hole 51 on a wall 50 via the expansion
mounting
sleeve 10, and the state in which the expansion mounting sleeve 10 is firmly
pressed against an inner surface of the hole 51. As shown, the wall 50 is pre-
drilled to provide the hole 51 for fitly receiving the expansion mounting
sleeve
10 therein. Then, a bolt 40 having length, size, and screw threads matching
the
internal screw threads 14 is screwed into the bore 12 of the sleeve 10. When
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bolt 40 is moved forward along the screw threads 14, it also pushes against
the
forward tapered bore 12, and thereby forces the forward tapered cylindrical
body of the sleeve 10 to expand outward. At this point, the engaging teeth 17,
18, 19 are caused by the altered taper of the sleeve 10 to move outward like a
stretched umbrella and therefore tightly engage with the wall of the hole 51
and
hold the sleeve 10 in place in the hole 51.
The expansion mounting sleeve 10 of the present invention is formed by
stainping using progressive dies. FIGS. 10A to 10H show in concrete the steps
of forming the expansion mounting sleeve 10. First, prepare a material having
dimensions required to produce the expansion mounting sleeve 10, and then
form two or more tapered areas 22 on the material extending parallel to one
another along an axis of the material in a common direction from a portion of
the material interconnecting the tapered areas 22, as shown in FIG. IOA. Then,
press the material in pre-defined thread forming areas 24 to form one or more
slots 26 parallel to the axis of the material, as shown in FIG. I OB. Then,
press
the material again to form a barb 30 and/or more than one engaging tooth 16,
17, 18 in the tapered areas 22. It is noted the engaging teeth 16, 17, 18 have
different heights which increase toward a front end of the tapered areas. The
engaging teeth 16, 17, 18 are then bent toward an outer side of the material,
as
shown in FIG. 10C. Thereafter, press the material at the thread
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forming areas 24 to form screw threads 14 having a required
size, as shown in Fig. IOD. The material is then pressed at the
tapered areas 22 to form at least 1 degree of bending, as shown
in Fig. 10E.
After the above steps are completed, the material is further
stamped, so that the thread forming a--eas 24 are pressed into a
U-sectioned shape, as showri in Fig. 10F. Then, the thread
forming areas 14 are further curled, so that the whole material
1o has a cross section appi-oximate to a circle, as shown in Fig.
IOG. When the thread forming areas 24 ai-e fully curled to
form a cylindrical body having a circular cross section, a
locking structure 60, which consists of an ear section 61 and a
recess section 62 correspondingly formed at two opposite edges
of the material near a rear end thei-eof, is locl:ed to hold the
curled material in the formed cylindrical body, as shown in Fig.
IOH. Finally, trim off the temporary connecting belt of
material to obtain a finished product of'the expansion mounting
sleeve 10.
F1-om the above desci-ibed steps, it can be found that the
expansion mounting sleeve 10 of the present invention is
integrally foi-med by employing the existing well matured
stamping and press forming techniques and designing
high-precision pr-ogressive dies, and using the widely available
matei-ials. The expansion mounting sleeve 10 has the
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following advantages:
(1) The loclcing structure 60 effectively prevents the rear end
of the cylindrical body of the sleeve 10 from being
expanded and becoming loosened when the bolt 40 is
sci-ewed into the screw thi-eads 14 froin the rear end of
the sleeve 10.
(2) The one or inore stopping tooth areas 20 effectively
prevent the sleeve 10 mounted in the hole 51 from
rotating when the bolt 40 is initially screwed thei-einto.
(3) Since the bore 12 of the sleeve 10 is internally threaded,
and the bore 12 and the cylindi-ical body of the sleeve 10
ai-e forward tapered, the bolt 40 of right size screwed into
the sleeve 10 along the tlzi-eads 14 would finally expancl a
front portion of the sleeve 10 into a fully straight
cylindrical shape, and cause the engaging teeth 16, 1 7, 18
to move outward like a stretched umbrella to tightly
engage with the wall 50 in the hole 51, and thereby firinly
liold the sleeve 10 in place in the hole 51.
(4) The sleeve 10 is integrally formed by stamping through
easy and duick processing procedures_ A variety of
usable matel-ials may he selected for manufacturing the
sleeve 10 without unnecessarily wasting the material.
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The associating bolt 40 inay be an easily accessed
ready-made bolt to facilitate 100% successful fastening
operation using the bolt 40 and the expansion rnounting
sleeve 10 within shortened tiine period at reduced pr-oduct
and labor costs.
(5) The expansion mounting sleeve 10 inay be integrally
formed by stamping a cold-rolled metal strip using
liigh-precision progressive dies at high productivity.
(6) The material for the expansion mounting sleeve 10 may
be selected according to diffet-ent applications. Ainong
others, the widely available metal matel-ial can be
conveniently used.
(7) The expansion mounting sleeve 10 is integrally formed
by stamping a cold-i-olled inetal sti-ip to simplify the
manufacturing procedures and largely save the material,
compared to various kinds of n-ietal expansion bolt
2 o asseinblies or mounting nuts manufactured using
conventional p--ocessing techniques, such as turning, cold
forging, etc. For example, in the tiu-ning cut expansion
bolt assembly, a round bar must be turning cut and then
subjected to a secondary processing of grooving to form
2 5 an expansion sleeve, and a taper-headed bolt is colcl
forged to use with the sleeve; and in the cold forged
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expansion bolt assembly, a rouild bar must be cold forged
to foi-in a taper-headed bolt, which is then used with other
parts; and in the turning cut mounting nut, a round bar
must be turning cut.
(8) The expansion mounting sleeve 10 is made to use with
t-eady-inacle bolts anci screws. All bolts or screws
having lenQ,th, size, and sci-ew threads matching the
internal ly thi-eaded bor-e 12 of the sleeve 10 inay be
selected for use. The sleeve 10 of the present invention
is therefoi-e superior to the conventional expansioti bolt
asseinblies in tei-ms of the compatibility of the sleeve
with the bolt.
(9) It is ver-y easy to use the expansion mounting sleeve 10 of
the pi-esent invention to fasten a bolt oi- scl-ew to a wall.
To do so, simply drive the sleeve 10 into the hole 51
predrilled on the wall 50, and select a matching bolt oi-
screw 40 to screw into the sleeve 10. A person of
2 o general skill inay handle the sleeve 10 and the bolt 40 to
complete the fastening operation within a shoi-t time.
( 1 0) The expansion mounting sleeve 10 is firmly mounted in
the hole 51 on the wall 50 wllen the bolt 40 is screwed
into the threaded bor-e 12 of the sleeve 10 to expancl the
tapei-ed front poi-tion of the sleeve 10, which in turn
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causes the engaging teeth 16, 17, 18 to move outwar-d and
tightly engage with the wall 50 to hold the sleeve 10 in
place in the hole 51. The sleeve 10 mounted in the hole
1 in this manner is absolutely pi-evented from idling or
5 loosening in the hole 51.
(11) Since the sleeve 10 is in the form of a female member,
the matclling bolt 40 in the for-m of a male membei- does
not project from the rear end of the sleeve 10 when the
fastening operation is completed, giving the wall a
visually pleasant sLu-face and ensuring the tiglit
attachmetlt of the expansion moLUZting sleeve 10 and the
bolt 40 to the wall 50.
In brief, the expansion mounting sleeve 10 of the present
invention can be manufactured by integral stamping through
simple and quick processing proeedLn-es. And, a variety of
usable matei-ials inay be selected for manufacturing the sleeve
10. The bolt 40 for Lising with the sleeve 10 may be easily
accessed from the ready-macle products. And, the sleeve 10
may be efficiently driven into oi- mounted in a wall without the
risl: of becoming loosened frorn the wall.
~F~
