Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to apparatus for connecting
steel reinforcing rods, such as are used for structural '~
purposes, in end to end relationship, ;
Reference is made to related co-pending Application -~
Serial ~o. 204,507, filed on July 10, 1974 and issued to
Patent ~o, 1,017,129 on September 13, 1977 and assigned to
the present assignee,
When structural steel reinforcing rods are positioned `
prior to casting concrete around them, it is a common practice
to overlap the adjacent ends of rods which are disposed so
that their longitudinal axes are substantially co-planar.
The object is, of course, to minimize the risk of a weakness
in the junction zone. This practice is, however, wasteful
of steel,
To obviate this disadvantage, it has been proposed
to accommodate adjacent rod ends in a steel sleeve and to
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crimp the sleeve onto the rods in a number of different ;~
parallel transverse zones by means of a hydraulic press. The
chief disadvantage of this proposal lies in the fact that the
necessary hydraulic equipment is usually bulky with the re-
sult that in many cases it cannot be manoeuvred into the re-
quired poaition because other reinforcing rods block access,
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It will be understood that the equipment must be positioned
transversely with respect to the longitudinal axes of the
rods.
It has also been proposed to effect a joint by com-
pre~-sing a steel sleeve onto adjacent rod ends by means of an
explosive charge. This proposal suffers from the disadvantage
that it is noisy and is liable to damage or displace adjacent
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formwork and concrete. ~
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If welding is resorted to, the operation is relatively
o slow and it requires a skilled welder to produce a good joint.
Furthermore, he must necessarily use bulky equipment.
One object of the present invention is to provide new
or improved apparatus for fastening a ~teel connecting sleeve
to adjacent rod ends which overcomes or minimises the disadvantages
hitherto inherent in the use of such sleeves.
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The type of rod with which the invention is concerned is
that which is either formed with surface deformations or which ~ i
has such deformations introduced as, for example, by interposing
a steel wire helix between the rods and the sleeve.
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Another object of the invention is to provide porta~le
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apparatus for the purpose stated which can be used in relatively
confined s~aces.
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A further object of the invention is to provide
apparatus which will be capable of fastening the sleeve to rods
which may differ in cross-section within the range of permis-
sable tolerance which may be as much as 12 per cent in some
cases.
A still further object of the invention is to provide
apparatus which will effect a satisfactory joint with relatively
low power requirements. `
According to the above objects, from a broad aspect,
the present invention provides an apparatus for fastening to
adjacent substantially co-axially disposed reinforcing rod ends
a sleeve of uniform external cross-section throughout its length ~-
~and having internal cross-sectional dimensions to enable it to
receive and embrace both rod ends. The apparatus comprises
at least two fluid pressure operated jack units each having a
cylinder, a piston and a piston rod. Latching means is pro-
vided for releasably securing the jack cylinders together in -
parallel spaced relationship to one another around one of the
reinforcing rods in a zone not occupied by the sleeve. At
least two die segments, which collectively provide an axial
bore at least part of which is dimensionally smaller in cross-
section than the external cross-sectional dimension of the
sleeve, are loosely mounted on the free ends of the piston
rods so as to be capable of limited rotational movement relative
thereto in a longitudinal direction. Die segment retaining
means are provided at the extremities of the piston rods.
Pusher means are associated with the jack cylinders extending
in the direction towards the die segments which engage one end
of the sleeve and prevent it from moving axially relative to
the rods. Ring-shaped locking members are provided for
temporarily securing the die segments in operative relationship
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one to the other and which permit the aforesaid limited
rotational movement thereof. Complementary formations are
provided on the die segments for receiving the ring-shaped
locking members.
Other objects, features and advantages of the inven-
tion will be apparent from the specification, the drawings
and claims.
In the drawings, wherein like reference numerals
indicate like parts, and wherein an illustrative embodiment
of the invention is shown;-
Fig. 1 is an exploded perspective view of apparatus
for fastening a sleeve onto adjacent rod ends
constructed in accordance with th~ invention.
Fig. 2 is a part sectional elevation on a reduced
scale of the apparatus of Fig. 1 a~sembled
to the rod ends.
Fig, 3 is a sectional elevation of the die segments
on an enlarged scale.
Fig. 4 is an end elevation, also on an enlarged scale,
of the die segments of Fig. 3 showing the rneans
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by which they are ~onnected together. ;
Fig. 5 is a cross-section, also on an enlarged scale-,
on the line V - V in fig. 4.
Fig. 6 is an exploded perspective view of the means
for connecting the die segments together.
Fig. 7 is a perspective view showing a sleeve assemblea ;~
to two adjacent rod ends before deformation of ;
the sleeve.
Fig. 8 is a perspective view showing la sleeve assembled
to two adjacent rod ends after deformation of the
sleeve.
Fig. 9 is a longitudinal section on the lineIX ~ I~
in fig. 8 on an enlarged scale.
Re~erring to the drawings, the apparatus is constructed
in two separate halves which may be secured together around
ribbed rods 1 and 2 and their embracing cylindrical sleeve 3.
Each half includes a die segment 4 having holes 5 to
permit of its being mounted on the free ends of piston rods ,
6 of hydraulic jacks. It is emphasised that the die segment
is not a tight fit on the piston rods and that it is capable
of a limited rotational movement relative thereto in a longi- ~
tudinal direction. The piston rods 6 carry circlips 7 on one ;-
side of the die segment 4 and retaining nuts 8 on the other.
The jack cylinders 9 are secured to a mounting plate 10 disposed f
in parallel spaced relationship to the die segment 4 and through
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which the piston rods 6 pass. The pla~e 10 is formed with
a recess 11 which partially embraces the peripheral surface
of the rod 2. .
The mounting plates 10 are provided with.spigot elements
12 which are adapted to bear against one end of the sleeve 3 and ~.
prevent it from moving longitudinally with respect to the rod
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ends. Furthermore, the spigot elements are tapered in a
direction towards the die so as to permit them to pass into .-
the bore o the die and so enable the sleeve to be deformed
throughout its length. :-
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One pair of jack cylinders 9 is provided with bored
lugs 13 through which.a hinge pin 14 passes. The pin 14 carries
strap members 15 which are adapted to be swung over lugs 16
carried by the other pair of jack cylinders~and.locked by means
of. bolts 17. By this mean~s the two halves of the apparatus are
removably connected together at the:end remote from the die
segments 4. The positioning of the connecting means described ~ ~ :
above at the cylinder ends remote from the die segments enables .`
the out of balance forces which will be encountered to be ~ .;
resisted.
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.~ The die segments 4 collectively provide a bore 18 at least .
part of which is dimensionally smaller than the external dimension
~', of the sleeve 3. This part is denoted by the numeral 19. . .
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As shown more particularly in Figs. 3, 4 and 5, the
die segments 4 are adapted to be assembled to the rod 1 in ..
spaced relationship to one another. This relationship is
maintained while the die segments are not under load by
means of spacer bars 20 which are inserted between the two
halves of the composite die. The bars 20 are bored to house
spring-loaded ball clips 21 whLch engage with corresponding
recesses 22 in the opposed faces of the die segments 4.
The two die segments 4 are held together when assembled :
around rod l by ring members 23 which are engaged over flanges
24 on the ends of the die segments 4. It will be noted that
the ring members 23 have circular portions 25 and a central
portinn 26 which is defined by the tangent to the circles.
The sp~cer bars 20 are located in this central portion 26 and ;
are held in position by locking bars 27 and screws 28 so that the
spacer bar and ring can be manipulated and snapped into position
as a single unit.
Mention has been made ear:Lier of the fact that the die :
segments 4 are capable of limLted rotational movement relative
to the piston rods 6. This movement is not prevented by the
ring members.23 because the circular formations of the latter
engage with the correspondingly shaped flanges 24 on the die
- segments.
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The bore of the composite die is formed with four
axially disposed inwardly extending ribs 29 and the diameter
measured between the opposed pairs of ribs is less than the
external diameter of the sleeve 4. In the circumferential
zones between adjacent ribs the die has axially disposed
recesses 30. The distance ~etween the opposed recesses is great-
er than the external diameter of the sleeve 4. ~
When a die as described above is used, the sleeve will ~`
be caused to adhere firmly to the rod ends in the longltudinal
zones defined by the ribs 29. At the same time, surplus materialfrom the sleeve is displaced into the recesses 30. In the
result, an initially cylindrical sleeve will, after the die has
passed over it, have a substantially ~quare cross-section with
rounded corners.
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When the die is under load, the segments 4 are forced -
slightly outwards relative to one another until further movement
is arrested by the ring members 23.
The die is drawn over the sleeve 3 by admitting pressure ;
fluid into the cylinders 9 and the ribbed configuration of the
rods l & 2 housed within the sleeve sets up an oscillating
rotational movement of the die segments 4 relative to one another `
as the die moves over the sleeve and compressos it onto the rods.
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Within the restrictions imposed by practical con-
siderations of weight and size, the apparatus is not capable of
forcing the sleeve down into intimate contact with the rods over
the entire length of the compression plane since if it were re-
~uired to do so, the force applied would be unnecessarily large
and would have to be sufficient to cause the slPeve material
to flow i.e. extrude. `
What actually happens ls illustrated in fig. 9. The
sleeve is only forced into firm contact with the rods in the t
zones of the ribs 31 on the rods. In the intermediate zones
the inner peripheral wall of the sleeve is out of contact with
the rods. In the result, the peripheral surface of the sleeve
ln the zon~s of the die ribs 29 is corrugated as shown in
fig. 9-
In Fig. 9 :-
ds is the inner diameter of the deformed sleeve
and it varies from d5(min.) to ds (max.). , `
db is the diameter of the rod core i.e. excluding
the ribs 31 and it will vary from db(max.) to db !'
(min.) with any given rod in accordance with ¦
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manufacturing tolexances.
h is the height of the ribs 31.
Dl is the outer diameter of the deformed sleeve
in a zone which does not include a rlb. -
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D2 is the outer diameter of the deformed sleeve
in a zone which does include a rib.
The desired joint is effected by a combinat1on
of :-
a. The folding away of surplus sleeve material
by the die design. This }s achieved by
having four die compression planes corres-
ponding to the die ribs 29 and the relieved
or non-contact area of the die in the circum-
ferential zones between the ribs 29. ;~
b. Having a correct relationship between ds and
db. This relationship is calculated from ~ -
the db (max.), h relationship and varies from
d8 = db (max.) to ds = db tmax.) + a where a
is a variable and is empirically establlshed
after consideration of db (max.) + 2h, the
yield stIess of rod and sleeve, and the hoop
strength of the sleeve cross-section.
c. Having a controlled link between the die
segments to accommodate the difference
between Dl and D2. This is brought about
by the ring members 23 which are designed to
withstand the ultimate bursting orces of the
die and which operate within the "elastic"
characteristic of the material using the `~
material elasticity to accommodate the -
diference between D1 and D2, in conjunction ~
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with limited die rotation which is controlled
by the spacer bars 20 which are also used to
position the ring members 23 when the die is
not stressed.
It h~s been found highly advantageous to cause the sleeve ~`
to grip the rod ends only in a plurality of longitudinal zones
whlch are circumferentially spaced from one another. ~mong the
advantages flowing from this method of operation the following are
of special significance ~
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(i) The joint is of adequate mechanical strength.
Tests to destruction have shown that, provlded
the sleeve is suitably dimensioned, the rods
will break outside the zone of the sleeve while
the joint itself remains intact.- In other words
the rod will not pull out of the sleeve.
(ii~ Less thrust is required to force the die over the
sleeve.
(lii) There iæ a lo~er bu~sting forced imposed on the
die.
(iv~ There is a smaller elongation of the sleeve. ,
(v) Less metal is required for the sleeve than would
be required to o~tain the same cross-sectional `
area after deformation if the sleeve were caused ~o
; grip the rods over their enti~re circumference.
(vi~ - There is probably less wear on the die.
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