Patent Application
20080157549
This invention relates to protectors and, in particular, an edge protector for use with industrial slings designed to lift heavy loads.
Industrial slings are designed to lift, transport and move extremely heavy loads. Thirty years ago, the vast majority of industrial slings were made of metal (either chains or wire rope). More recently, non-metal or synthetic slings have gained popularity and are replacing metal slings in many circumstances.
Synthetic slings are usually comprised of a lifting core made of twisted strands of synthetic fiber and an outer cover that protects the core. The outer cover plays an important role in synthetic slings. The cover is designed to move with respect to the inner core in order to reduce the likelihood of wear points. Also, the outer cover provides a means for protecting the inner core from the elements (e.g., heat, cold, chemicals, etc.). Therefore, once the cover is damaged the probability that the load-bearing inner core will be exposed and damaged increases dramatically.
When a metal sling was used to lift an abrasive load/object (e.g., one made of concrete) or any object having a sharp edge, there was little concern that the metal sling would be damaged. However, with the advent of synthetic slings, the damage that may be done to the outer cover by an abrasive or sharp object is of particular concern. The size and/or shape of the load/object may require that the sling be placed next to an abrasive surface or, more commonly, against an edge (e.g., an elongated stretch where two pieces of metal are joined to form a 90° angle) of the load to be lifted. The tremendous force applied to the sling at the point of contact with the load being lifted may damage the sling.
Some large objects that have particularly sharp edges or which are particularly unwieldy undergo the additional manufacturing step of attaching ring bolts, eye bolts or lifting loops in order to accommodate the slings needed to move the objects. If the object being lifted is made of metal, the eye bolts are attached by welding ring-shaped pieces to the object. For example, large pipe sections, cargo ship sections, structural steel for a sky scraper or bridge section may be manufactured with multiple eye bolts.
It should be noted that the eye bolts cannot be placed just anywhere on the object to be lifted. The eye bolts must be placed at points accessible by the slings, so that during a lift the load is stable. In addition, the load must be properly oriented once it is lifted or moved into position. Specifically, the eye bolts must take into consideration the center-of-gravity of the object so that the object does not drop into an odd position or begin to spin uncontrollably as it is being lifted.
Once the object is moved to its final destination and placed in its permanent position, the eye bolts may be removed from the object by cutting, burning or unwelding. Clearly, the extra steps of calculating the object's center-of-gravity, attaching the plurality of eye bolts in an appropriate location and then removing the eye bolts after the object has reached its final destination increases the time and cost of a lifting operation. Moreover, if the load is not made of iron it is much more difficult to attach eye bolts.
For shipping purposes, it is known to manufacture protectors by forming angular pieces of cardboard to abut against various goods/objects. Also, foam inserts that are custom designed to fit against the edge of a particular object serve a similar purpose. The protectors are designed to absorb some of the force to which the object will be exposed during normal shipping and handling. For example, televisions, filing cabinets, furniture, computers, washers, refrigerators and similar appliances are shipped inside cardboard boxes, with protectors placed along several edges, thereby providing a measure of protection. These types of protectors are designed to protect the object during shipping and handling. As long as the goods are protected, the destruction of the cardboard boxes and the foam protectors are irrelevant since they are disposed of once the goods are unpacked.
U.S. Pat. No. 6,470,637 to Jeffrey Gratz discloses a corner protector made of molded pulp that protects goods/objects such as windows during shipments. The corner protector disclosed in U.S. Pat. No. 6,470,637 is inexpensive to manufacture. Since it is disposed of once the window reaches its destination and is unpacked, the corner protector disclosed in U.S. Pat. No. 6,470,637 is designed to be biodegradable.
The aforementioned cardboard and foam protectors are specifically designed and shaped to protect the contents (i.e., the object being shipped or moved). They are not designed to protect the means used to lift the object (e.g., a sling, rope, fork-lift, overhead crane, etc.). Furthermore, the cardboard and foam protectors would provide negligible protection when used under the conditions in which industrial slings are used. Accordingly, there is a need in the industry to develop an apparatus that could be quickly and safely (and preferably releasably) secured to an industrial sling, lifting or towing chains, wire rope, etc. that would protect the sling, towing chain, wire rope, etc. from abrasive or sharp edges at the points where the sling contacts its load.
The present invention is a reversible edge protector designed for use with industrial slings. Industrial slings are designed to lift heavy and usually bulky loads. Such heavy loads may not be intended to be lifted or moved very often and, many times, are unique (e.g., a section of a bridge); therefore, there is usually little consideration given to the rigging needed to ship and place the load into its final position.
Industrial slings used to lift heavy loads must come in contact with the load at one or more places. Further, depending on the shape and center-of-gravity of the load, the sling must be positioned at specific points. It is not uncommon for the load to have sharp corners or other features that may damage the cover of the sling. Even relatively simple-shaped loads (e.g., container boxes having a box shape), have edges that can damage a sling. Accordingly, there may be little choice other than to have the sling abut the load at a place that will cause damage to the sling (or cause damage to the load) during lifting or moving.
The present invention is designed to protect slings (in particular, synthetic slings) from the relatively sharp corners and edges of the objects to be lifted. In a preferred embodiment, the edge protector utilizes a pair of attachment straps having hook and loop strips (i.e., Velcro® fasteners) for easy application on and removal from a sling.
It should be noted that both metal and non-metal slings can be damaged by the load. In addition, the force on the sling applied by the load is equal to the force on the load applied by the sling. Therefore, there is a significant chance that the load will be damaged by the sling during the lift.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and, together with the following description, serve to explain the principles of the invention. For the purpose of illustrating the invention, embodiments are shown in the drawings which are presently preferred, it being understood, however, that the invention is not limited to the specific instrumentality or the precise arrangement of elements or process steps disclosed.
In the drawings:
In describing a preferred embodiment of the invention, specific terminology will be selected for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.
Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings in which an edge protector in accordance with the present invention is generally referred to as referenced numeral 10.
In this disclosure, an edge is defined as the elongated seam or corner formed when at least two sides of an object meet. The most familiar type of edge is the 90° angle formed by two sides of a rectangularly-shaped object. However, an edge can be formed by joining two sides at virtually any angle. In fact, if an angle formed from two sides of an object is less than a right angle, the edge tends to be sharper. The present invention may be used to protect a sling from any sharp edge or surface on the load to be lifted.
The number of edge protectors used will depend on the shape of the load to be lifted and the number of slings used to lift the load. It is desirable to use an edge protector 10 in every location where the sling will come in contact with an edge/corner of the load.
Referring now to
In an alternative embodiment illustrated in
Referring again to
It is important to note that the edge protector 10 is reversible. That is straps 14a and 14b may be wrapped first around the sling 55 so that the hook fasteners 40 face away from the sling, then straps 24a and 24b may be wrapped around the sling allowing the loop-type fasteners 41 to link up and engage the hook-type fasteners. This feature will extend the operational life of the edge protector.
The length of the body portion 12 will generally depend on the shape/design of the load to be lifted. The width of the body portion 12 will generally depend on the width of the sling 55 used to lift the load. In a preferred embodiment, a nine-inch length for body portion 12 protects most loads. Also, the width of body portion 12 is preferably about two inches wider than the sling.
The spacers 18 may be of any of a number of geometric shapes; however, they must be thick enough to prevent the corner of the load 99 from engaging the sling 55 as illustrated in
It has been found that six cylindrically-shaped spacers 18, each having a diameter of ¾ inch, and a length slightly less than the width of the body section 12, are the preferred dimensions. However, the shape and weight of the load will determine the physical dimensions of the cylindrically-shaped spacers 18. The cylindrically-shaped spacers 18 may be made of any material that will not readily compress under the force needed to lift the load; some common materials include steel, aluminum and, most commonly, nylon.
Referring again to
The spacers 18 are designed to provide a larger surface area against which the sling 55 engages the load 99. By moving the point of contact during a lift from the edge/corner of the load and distributing the force over a larger surface area, damage to the sling 55 is prevented. (Moreover, damage to the load is also prevented.)
In a preferred embodiment, the edge protector 10 does not just provide an additional material insert between the edge/corner and the sling, but is designed to form a tunnel 30 around the sharp edge of the load 99 thereby preventing the edge/corner of the load 99 from engaging and damaging the edge protector and the sling. The distribution of the weight of the load over a larger surface area and the formation of the tunnel are important features of the subject edge protector 10.
In a preferred embodiment, the body section 12 is stitched in half to form two separate “half-pockets.” Each half-pocket 27 and 28 holds one or more spacers 18. The stitching 29 helps to separate the spacers 18 and ensures the formation of tunnel 30 when the edge protector 10 engages the load 99. In a preferred embodiment, each half-pocket 27, 28 holds three spacers as illustrated in
The Velcro® straps 40, 41 of the securing means 14a, 14b, 24a, 24b allow the edge protectors 10 to be quickly moved from one sling or lifting chain to another. If the edge protectors need to be moved or repositioned, loosening the Velcro® straps allow the edge protector 10 to slide or releasably attach the edge protectors 10 to a new position on the sling. In other words, the edge protector 10 does not need to be tight (only snug) against the sling 55.
It should be noted that when using metal slings (or towing chains), the sling may damage the object that is being lifted. The subject edge protector will also protect the load from being damaged by dispersing the force over a larger surface area.
It will be apparent to one skilled in the art after reading this disclosure that the means for securing the edge protector 10 to the sling or towing chain is not necessary. For example, when the load is in its rest position, one or more edge protectors may be inserted as the sling is being tightened against the load. The weight of the load 99 as the sling 55 begins its lift will keep the edge protectors 10 in place without the need of the Velcro® straps.
Although this invention has been described and illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made which clearly fall within the scope of this invention. The present invention is intended to be protected broadly within the spirit and scope of the appended claims.
