Apparatus for forming expanded mesh

An apparatus for gripping, guiding and transporting opposite longitudinal side edges of slit, deformable strip for forming expanded mesh sheet. One chain of each of two pairs of opposed endless chains has a longitudinal recess adjacent a longitudinal planar side edge of the strip for receiving the planar edge of the strip therein and the opposed chain of each of said pairs has a plurality of equispaced sharp projections for penetrating the longitudinal planar side edge of the strip whereby the said edge is effectively gripped between the opposed chains during expansion.

BACKGROUND OF THE INVENTION 
(i) Field of The Invention 
This invention relates to the production of expanded metal strip and, more 
particularly, relates to an apparatus for gripping opposite longitudinal 
side edges of slit metal strip and advancing said longitudinal side edges 
in diverging paths for progressively laterally expanding the strip. 
(ii) Description of the Related Art 
A method and apparatus for forming expanded mesh sheets from deformable 
metal strip in which the strip is slit and pre-formed and then laterally 
expanded to form expanded mesh sheet is disclosed in U.S. Pat. No. 
4,315,356 granted to Cominco Ltd. on Feb. 16, 1982, incorporated herein by 
reference. This patent discloses the forming of an upturned edge on each 
lateral side edge of strip to be expanded, engaging said upturned edge on 
each side of said strip between a pair of opposed endless chains having an 
internal longitudinal slot formed therein for receiving said upturned 
edge, and advancing said edges in laterally diverging paths by travel of 
said endless chains whereby the strip is progressively laterally expanded. 
More recently, preform protrusions have been formed adjacent each 
longitudinal side edge for engagement in internal longitudinal slots in 
the opposed endless chains. Once expansion of the metal strip is complete, 
a major portion of each outer longitudinal side edge of the strip 
containing the upturned edges or preform protrusions becomes superfluous 
and must be slit and discarded as scrap in order to leave a minimum width 
of border, if desired, for the final product. This necessitates an 
undesirable ancillary chopping and trimming operation and recycle of scrap 
with attendant losses due to creation of dross because of the presence of 
contaminants such as lubricating oils which must be skimmed and discarded. 
It is a principal object of the present invention to provide a method and 
apparatus for expanding slit metal strip by gripping, guiding and 
transporting the opposite longitudinal side edges of the strip in 
diverging paths for progressively laterally expanding the strip without 
the need of upturned side edges, flanges, or preformed protrusions formed 
in the longitudinal side edges of the strip, thereby obviating an edge 
preforming operation and an edge slitting operation which will not only 
reduce equipment requirements and costs for slitting, guiding, chopping, 
conveying, storing and remelting steps but will also result in a reduction 
of about 50% or more of scrap material, depending on grid design, with a 
significant reduction of metal losses in lead dross. 
Another important object of the invention is quick and easy access to 
apparatus components in a production environment for replacement of 
components to compensate for changes in handling characteristics of lead 
alloys ranging from soft low strength alloys to hard high strength alloys. 
SUMMARY OF THE INVENTION 
In its broad aspect, the apparatus of the invention for expanding slit 
metal strip having opposite, longitudinal planar side edges in which 
gripping and guiding means engage the opposite longitudinal side edges of 
the strip and advance said edges in diverging paths for progressively 
laterally expanding the strip comprises two spaced apart pairs of 
diverging, opposed endless chains, one chain in each pair of opposed 
endless chains having a longitudinal recess adjacent a longitudinal planar 
side edge of the strip for receiving the longitudinal planar side edge of 
the strip therein, and the opposed chain in the said pair of opposed 
endless chains having a plurality of spaced sharp projections extending 
partially into the longitudinal recess for penetrating and gripping the 
longitudinal side edge of the strip whereby the longitudinal planar side 
edges of the strip are advanced in diverging lateral paths for expanding 
the strip. 
Each chain in each pair of opposed endless chains is a multiple link chain, 
preferably having six or eight parallel side-by-side links. The 
longitudinal recess for receiving the planar side edge of the strip may be 
one or two links wide or more depending on grid design and size. For 
example, large industrial grids may require a longitudinal recess three 
links wide. 
The spaced sharp projections preferably are equispaced and may be in the 
shape of v-shaped teeth having an acute included angle of about 45.degree. 
to about 60.degree., or may be in the shape of teeth having a knife edge. 
The teeth are shorter than the depth of the opposed recess to provide a 
clearance between the teeth and opposed chain. For a 3/8 inch pitch chain, 
a clearance of at least 0.010 inch is required, the teeth preferably 
having a length of about 0.060 inch and the recess having a depth of about 
0.070 inch. Larger chain pitches required for industrial grids may have a 
larger clearance between the teeth and the opposed chain. 
The apparatus of the invention includes a pair of opposed, spaced-apart 
guide bars mounted on each side of a frame for receiving a pair of said 
diverging, opposed endless chains for guided travel, means for rigidly 
mounting one of said guide bars on the frame, and means for resiliently 
mounting the other of said guide bars on the frame for biasing one of the 
said guide bars towards the other. The means for resiliently mounting the 
other of said guide bar comprises a stationary guide member rigidly 
mounted on the frame spaced from and parallel to the resiliently-mounted 
guide bar, said stationary guide member having a guide wall extension for 
laterally positioning and supporting the resiliently-mounted guide bar and 
having a plurality of holes equispaced along the length of the stationary 
guide member, and a cap mounted on the stationary guide bar member having 
a plurality of holes, matching the holes equispaced along the stationary 
guide member. A bolt loosely mounted in each hole is threaded into the 
guide bar and a compression spring positioned in each said hole concentric 
with the bolt abuts the cap at one end, whereby the resiliently-mounted 
guide bar is normally biased by the compression spring towards the 
stationary guide bar upon loosening of the bolts, and the 
resiliently-mounted guide bar is retracted away from the stationary guide 
bar by screwing of the bolts into the said resiliently-mounted guide bar. 
The cap is removable for external access to and for replacement of the 
compression springs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference first to the prior art shown in FIG. 1 of the drawings, 
lateral side edges 10 of strip 12 have narrow, upturned flanges 14 or 
double pitch edge preform protrusions, not shown, adapted to be engaged by 
internal slots or recesses in the links of multiple link chains of a pair 
of opposed endless chains. Trimming of the deformed side edges of the 
strip at the completion of strip expansion necessitates the installation 
and use of trimming and chopping equipment and constitutes a significant 
waste of strip material as scrap with attendant costs of trimming, 
conveying and chopping the scrap for recycle. 
Turning now to the embodiment of the invention shown in FIGS. 2 and 3 of 
the drawings, two pairs 20 of opposed multiple link endless chains 21, 22 
of the present invention are mounted for continuous linear travel at each 
longitudinal side edge of strip 23. Chains 21, 22 are supported on frame 
24 by upper and lower hardened tool steel guide bars 25, 26 respectively 
for accurate alignment and tracking of the chains, and are driven by a 
drive motor, not shown, with a phase adjuster for synchronous travel of 
the upper chain 21 relative to lower chain 22. 
With particular reference now to FIGS. 3 and 5, chains 21, 22 travel in 
guide bars 25, 26 respectively, preferably with one of the chains, upper 
chain 21 in this embodiment, resiliently urged downwardly against lower 
chain 22 by a plurality of normally equispaced coiled die compression 
springs 30, one of which is shown, biased against the back side of upper 
guide bar 25. Teeth 32, normally depending downwardly from the link 34 of 
chain 21, are biased to project downwardly into a recess 36 defined by 
opposed shortened link 38 of chain 22. 
Lower guide bar 26 is positioned by dowel reference pin 37 and is rigidly 
fixed to frame 24 by bolts 39 (FIG. 2). Upper stationary guide member 40 
having guide wall extensions 42 for laterally positioning floating guide 
bar 25 is secured to frame 24 by bolts 43. Bolts 44 (FIG. 3) project 
downwardly loosely through equispaced holes 41 having shoulders 45 formed 
in cap 46 and through fixed guide-member 40 concentric with springs 30 for 
threading into guide bar 25. Bolts 44 normally are retracted sufficiently 
from guide bar 25 to allow the guide bar to float under the downward bias 
of springs 30. Bolts 44 can be screwed inwardly into guide bar 25 whereby 
the heads of bolts 44 abut hole shoulders 45 to retract the guide bar to 
release upper and lower chains 21, 22 from the longitudinal recesses 48, 
49 in guide bars 25, 26 respectively for servicing or replacement. 
With reference now to FIGS. 5 through 8, embodiments of gripping and guide 
teeth are illustrated schematically. FIGS. 5 and 7 illustrate sharp, 
V-shaped teeth 32 formed in upper inner link 34 of chain 21 with a mating 
recess 36 formed in opposed lower link 38 of lower chain 22 to receive 
teeth 32. Each V-shaped tooth 32 is sharpened to define an acute included 
angle between about 45.degree. and about 60.degree. terminating in a 
sharp-edged point positioned slightly above the opposed face 42 of lower 
link 38 to ensure clearance of the opposed links if the chains are 
operated without the presence of strip. In practice, by way of 
illustration, for a 3/8 inch chain pitch, the V-shaped teeth 32 can have a 
length to extend about 0.060 inch downwardly beyond the plane of upper 
chain 21 and the opposed shortened guide link 38 can define a recess of 
about 0.070 inch below the plane of the adjacent links of the lower chain 
22 to provide a clearance of about 0.010 inch between the links. Each link 
38 for a 3/8 inch pitch chain has a width of 0.060 inch, allowing a 0.030 
inch bite (FIGS. 5 and 6) of each tooth 32 into planar edge 50 of strip 23 
from the outside edge thereof. 
FIG. 6 shows one of a plurality of upstanding equispaced lower V-shaped 
teeth 60 formed in lower inner link 62 of chain 38 with mating recesses 64 
formed in opposed upper inner link 66 of chain 21 to receive teeth 60. 
FIG. 7 illustrates schematically an embodiment of our invention in which a 
pair of lower links 38, 48 are shortened to allow planar edge 50 of strip 
23 to extend deeper between the opposed chains to provide a bite of 0.090 
inch. Although a pair of links 38, 48 are shown shortened, it will be 
understood that one, two or three or more links may be shortened depending 
on the desired bite. 
FIG. 8 illustrates a further embodiment of our invention in which a pair of 
lower links 38, 48 are shortened to allow the planar edge 50 of sheet 23 
to be gripped by chisel-shaped teeth 54 of links 56. A bite of 0.060 " is 
provided. 
With reference now to the embodiment of the invention shown in FIGS. 9 and 
10, upper guide bar 25' has a downward side extension 27 for providing 
lateral support to chain 21 during expansion of the strip. Lower guide bar 
26' may have an upward side extension 28 for providing lateral support to 
lower chain 22 if the embodiment shown in FIG. 6 is used. Upper stationary 
guide bar 40' has an elongated guide wall extension 42' to laterally 
support side extension 27. 
In operation, and with particular reference to FIGS. 2, 3, 4, 8, 9 and 10, 
strip 23 is centered between the spaced-apart merging pairs of opposed 
chains 21, 22 at the entry of the expander by pressure engagement between 
opposed endless chains 60, 61 positioned centrally between the two pairs 
of opposed chains. Strip 23 has a longitudinally-extending central ridge 
62 adapted to seat in mating longitudinal recess 64 in upper chain 60 for 
accurate locating of strip 23 between the outer sets of expansion chains 
21, 22. 
The opposite longitudinal side edges 50 of strip 23 are slightly penetrated 
by teeth 32 (or teeth 54), under the bias of upper guide bar 25, or 25' 
and the side edges 50 of the strip are progressively spread apart for 
expansion of the strip into an open mesh pattern as the strip is advanced 
through the expander. 
FIGS. 11 and 12 illustrate conventional link spacing, FIG. 11 showing links 
70 of upper chain 72 in phase with and opposed to links 74 of lower chain 
76 and FIG. 12 showing links 70 of upper chain 72 out-of-phase with links 
74 of lower chain 76. Each tooth 78a of teeth 78 depending downwardly from 
links 70 are opposite spaces 80 between links 74, possibly causing the 
strip gripped by teeth 78a to be depressed into spaces 80, thereby 
deforming the edges of the strip and causing an undesired wavy edge which 
will become the bottom frame of a finished battery plate. 
It has been found that narrowing of the spaces between links 74 to form 
gaps 82 narrower than the width of teeth 78, such as depicted in FIG. 13 
by numeral 84, prevents teeth 78 or 78a from deforming the strip. This is 
particularly significant for soft metal alloys which are prone to 
deformation. 
FIG. 14 illustrates a sprocket wheel 90 mounted for rotation on shaft 92 
journalled in machine 94 for driving an endless chain having links 70. 
With reference to FIG. 15, sprocket wheel 90 comprises toothed rim 96 
affixed to intermediate hub 98 by a plurality of equispaced bolts 100 
which pass through angular slots 102 in hub 98 into threaded holes 104 in 
sprocket wheel 90. Hub 98 is adjustably mounted on sprocket wheel 90 for 
angular adjustment thereon by bolts 108 and 108' bearing against stop pin 
110 extending from sprocket wheel 90. Rotation of bolt 108 in one 
direction and bolt 108' in the other direction cause sprocket wheel 90 to 
rotate relative to hub 98 by exerting pressure on stop pin 110 by bolts 
108 and 108' in wings 112, 112'. Hub 98 is keyed onto shaft 92 by key 116 
in keyways 118, 120. 
The angular adjustment of sprocket wheel 90 thus can be effected by 
loosening of bolts 100 for rotation of hub 98 relative to toothed rim 96, 
within the limits of slots 102. The upper chain thus can be synchronized 
with the lower chain by means of angular adjustment of sprocket wheel 90. 
The present invention provides a number of important advantages. The need 
for side-edge upturned flanges or preformed protrusions which must be 
severed from the strip after expansion into mesh is obviated. This not 
only avoids the need for the step of trimming the side edges, and its 
attendant costs, but substantially reduces the undesirable production of 
scrap material which must be chopped and recycled. Quick and facile 
external access to the die springs on the upper guide bars is permitted, 
allowing replacement of die springs when changing between soft low 
strength lead alloys to hard high strength lead alloys. 
It will be understood, of course, that modifications can be made in the 
embodiments of the invention illustrated and described herein without 
departing from the scope and purview of the invention as defmed by the 
appended claims.