This invention relates generally to safety hooks, and more particularly to safety hooks that comprise a novel configuration to improve strength and reduce weight without any adverse impact to the safety features that are critical to safety hooks.
It is not uncommon in the construction and building repair industries, and in other related industries, for individuals to work at elevated work positions, such as for example during the construction or repair of the upper floors of a multistory building. A number of safety devices are used in such situations. For example, safety harnesses and lanyards are devices that are designed to allow an individual to operate safely at what would otherwise be dangerous or deadly heights without risk of harm. Safety harnesses and lanyards are attached to each other and to support structures with safety hooks.
Safety hooks of various types are a cornerstone of fall-protection technology. Due to recent, more stringent ANSI standards over the last ten years, there have been a lot of changes to traditional safety hook designs. In the early phases of implementation, higher strength requirements were met by increasing the amount of material used and incorporation of larger cross-sections and reinforced locking mechanisms. The unintended consequence of these design changes has been that many fall-protection products have become substantially heavier. In addition, product interconnectivity compounds this problem. That is, the combination of various safety equipment components results in a corresponding increase in weight to the overall unit. For example, a typical lanyard utilizes two to three safety hook connectors, each of which has its own designed-in weight increases.
In addition, compact, personal self-retracting devices have proliferated during this same period of time, and each such device requires the use of 1-3 connectors (such as safety hooks). As a result of these multi-component trends, there has been an increased sensitivity to the weight of products, and most manufacturers and OEM hardware suppliers have been on a campaign to utilize lighter materials with simpler mechanisms to reduce the weight of their products. There has therefore been a recent push in the safety equipment industry to reduce the weight of safety equipment, including safety hooks, in order to reduce the burden on workers who may be carrying as much as 50 pounds or more of tool and safety equipment while elevated a substantial height above the ground. In the past, the focus of design for safety products, including safety hooks, was on maximizing product strength and ease of production.
Where safety hooks are concerned, a common strategy has been to forge hook and carabiner bodies out of aluminum alloy or other light-weight materials. The disadvantage of this strategy is that while these alloys can have a high tensile strength, they can be unacceptably brittle and may not adequately yield under eccentric loads. In order to address these shortcomings, a paradox is created in that a great deal of high grade aluminum must be used in the alloy to yield acceptable attributes, which results in minimal weight savings and increased costs.
One recognized approach for decreasing weight while maintaining structural strength of physical products is to incorporate a web and flange configuration across areas of high stress or load. For example, one way to increase the strength of a beam is to place as much stress-bearing material as far from the beam's neutral axis as possible, the neutral axis being the centroid of the mass moment of inertia of the beam. This approach traditionally imposes a requirement for symmetrical cross sections so that the compression and tensile stress fibers under load are equal. Hence, maintaining the neutral axis of the material cross section at its geometric center allows for the reduction of material thickness (and weight) in those areas while maintaining adequate overall strength. However, if the cross sections have asymmetrical cross-sections, dynamic loads applied to the beam can cause a differential stress distribution among the stress fibers in the beam that can result in a catastrophic failure.
Owing to the variation and dynamic nature of the stress loads placed upon them, safety hooks have not traditionally been constructed with symmetrical cross-sections and therefore have not been designed with web and flange components. Nonetheless, it would be desirable to design and incorporate a web and flange configuration that could be incorporated into a safety hook in order to reduce the weight while maintaining adequate strength to withstand the anticipated stress loads for which the hook is designed. As will become evident in this disclosure, the present invention provides benefits over the existing art.
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