Textiles: weaving – Fabrics – Materials
Reexamination Certificate
2000-12-05
2001-10-23
Falik, Andy (Department: 3765)
Textiles: weaving
Fabrics
Materials
C404S070000, C140S107000, C052S664000, C245S002000
Reexamination Certificate
active
06305432
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to metal wire mesh. In particular, this invention relates to an improved structure for metal wire mesh to avoid the problem of curvature set when wire mesh is bent or wound in rolls.
BACKGROUND OF INVENTION
Many metal wire mesh products comprise a plurality of round longitudinal wires and a plurality of round transverse wires forming a plurality of rectangles. These products include welded wire meshes or wire laths, or other meshes that are twisted or fastened together in some manner at the intersections of the longitudinal and transverse wires. Examples of the first type are welded concrete reinforcing mesh, welded utility mesh, or welded stucco reinforcing lath. An example of the latter type is wire fencing.
For wire meshes of lighter wire sizes, it is common to wind these products into rolls. Rolls provide the advantage of a convenient package containing a considerable length of continuous material. Rolls can provide a compact and dense package, which is important for warehousing and shipping considerations. Further, wire mesh products formed into rolls can easily be placed on pallets for handling.
However, one of the drawbacks of rolling metal wire mesh products into rolls is that the longitudinal wires can take on a curvature set. For the user, such curvature set often presents a problem. When unrolling the product, the longitudinal wires retain a memory and a tendency to spring back to the rolled position. As most products are intended to lay or run flat, or in a straight line, the user must work against the tendency of the mesh to spring back to its rolled condition. This can be dangerous for the user, and makes it difficult to flatten the product as it is being applied or while the wire mesh is being further processed.
The curvature set is caused when the longitudinal wires are bent into the roll shape. The resulting curvature stretches the outside fibres of the metal wires beyond their elastic limit. The metal at the outer side of each wire becomes plastically deformed and retains the memory of this deformation. The curvature set is primarily a function of the wire size, the ductility of the metal and the radius of the roll.
To partially counter the problem of curvature set, some manufacturers have produced rolls having larger core diameters. This approach can reduce the problem to some extent but will not eliminate it entirely, unless inordinately large roll core diameters are used. This approach also results in larger outer roll diameters for the same length of product and therefore, the advantages of a dense package are not fully achieved.
Producing and packaging metal wire mesh in sheets avoids the curvature set that is created in the roll formation process but this approach loses some of the benefits which rolls provide. Wire mesh products in sheet form require additional packaging to protect the product and to create a package that can be handled by a forklift. Another disadvantage of sheets is that they can be more difficult for the user to handle in the field. A further disadvantage for certain applications such as wire stucco reinforcement is that sheets require additional end overlaps in the construction of a wall. This reduces both the efficiency of application and the quality of installation in comparison to rolls which contain longer continuous lengths.
U.S. Pat. Nos. 3,632,054, 3,688,810, 3,814,144, 4,077,731, 4,557,633, and 5,009,545 all acknowledge the problems associated with wire meshes in rolls and disclose various apparatus and methods for straightening, backbending, decontouring the web and flattening the roll, so that when it is unrolled the tendency of the wire mesh to reassume a rolled position is substantially eliminated. These approaches compensate for the problem of curvature set but they do not avoid the introduction of curvature set in the first place.
The object of the present invention is to reduce the curvature set of longitudinal wires in metallic wire meshes that are wound into rolls for packaging or transport and are intended to be unrolled prior to use.
The present invention has application to wire mesh comprising a plurality of longitudinal strands and a plurality of transverse strands forming a plurality of rectangles, where the longitudinal strands are continuous and the transverse strands are either continuous or segmented, and the mesh or fencing is held together by welding or mechanical fastening at each intersection.
SUMMARY OF THE INVENTION
According to the invention, the longitudinal wires of a metal wire mesh are shaped so that instead of their cross section being round, the cross section is relatively shorter in one direction than in the other. For a round shape, the moment of inertia is the same around the horizontal and vertical neutral axes. The objective of the invention is to change the profile of the longitudinal wires so that the moment of inertia around the horizontal axis is less than the moment of inertia around the vertical axes (for the purpose of defining horizontal and vertical, the above description is based on the mesh laying in a horizontal plane). This includes a flattened profile, an oval profile, a convex profile, or any other profile that generally reshapes the round wire to a degree sufficient to meet the desired objective.
This shaping of the wire from drawn round wire, either coated or uncoated, or from a hot rolled wire rod can occur either before, during or after manufacturing of the wire mesh. The shaping of the wires can also be continuous or intermittent along the length of each longitudinal wire or in relation to adjacent longitudinal wires.
By reducing the moment of inertia of the longitudinal wires in the direction as described, the wire mesh can be rolled into a roll and some, or all, of the product in the roll can be wound up without acquiring curvature set. Thus, when the product is unrolled the wire mesh can easily be returned either to the flat state or have a desired amount of curvature.
It is a further object of the present invention to provide metal wire mesh that can be packaged in rolls and then subsequently unwound and that will then substantially flatten itself without the need for separate apparatus.
The factors that determine whether the longitudinal wires of a metal wire mesh take on any circular memory is the roll diameter and horizontal moment of inertia of the longitudinal wires. The manufacturer has the option of changing these attributes to either totally eliminate circular memory, or use some other combinations to both reduce circular memory and obtain other packaging benefits.
With minimal curvature set, greater density of rolled product can be achieved for warehousing and shipping.
The invention also provides an advantage in certain applications of providing a product that is more supple, such being an important feature for products such as stucco wire reinforcement lath or concrete reinforcing mesh in sheet form that need to be temporarily bent to get around corners. It will therefore be appreciated that the wire mesh structure of the invention will have application not only to metal wire mesh product which is intended to be packaged in rolls, but also to product in sheet form that is likely to be subject to temporary bending.
This invention can be applied to wire meshes made of any metallic material including bright, galvanized, plated or coated iron, carbon or alloyed steel; or from aluminum, stainless steel, brass, or other non-ferrous metals.
In one aspect, the invention is a metal wire mesh consisting of a plurality of longitudinal wires and a plurality of transverse wires, said wire mesh being wound into rolls along the length of said longitudinal wires and intended to be unrolled prior to use. The longitudinal wires have shaped areas wherein the moment of inertia of said shaped areas about the neutral axis parallel to the plane of the mesh is 90 percent or less of the moment of inertia of the shaped areas about the neutral axis vertical to the plane of the mesh. In another aspect, the invention is such wire mesh i
Davis Harold R.
Rugina Narcis
Sacks Abraham
Sacks Jeffrey L.
Spilchen William
Falik Andy
Oyen Wiggs Green & Mutala
Sacks Industrial Corp.
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