Exercise devices – User manipulated force resisting apparatus – component... – Utilizing weight resistance
Reexamination Certificate
2001-09-11
2004-05-04
Mulcahy, John (Department: 3739)
Exercise devices
User manipulated force resisting apparatus, component...
Utilizing weight resistance
C482S106000, C482S107000, C482S108000, C206S501000, C206S509000, C215S384000, C215S308000, C220S370000, C220S771000
Reexamination Certificate
active
06730004
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to exercising equipment, specifically to barbells and dumbells, more specifically to those designed to be filled with a ballast, such as water, by the user, and those facilitating other types of exercises, such as situps, pushups, and aerobic stepping routines.
2. Description of the Prior Art
It has long been recognized that one of the most effective methods for enhancing physical fitness is through the use of free weights, such as barbells and dumbells. Interestingly, the names for these devices came about when early foundries, a large part of whose business was making bells, would turn out a cracked or otherwise unsatisfactory bell. With the clapper removed, such a bell was silent, or “dumb”, yet still had great utility as a weightlifting device. Thus the one-handed free-weight came to be called a “dumbell.” Obviously two such bells attached to a bar became a “barbell”. The basic requirements of a barbell or dumbell are simple enough: a substantial mass, or ballast, which may be easily gripped by one or both hands in a balanced, comfortable way, with a shape facilitating weightlifting exercises. And in the past, the traditional central iron bar served admirably as a rigid frame for the barbell, contributing to the overall weight, and providing a long, convenient handle. Since even the very name “barbell” would not exist without the “bar”, it may be hard for us to imagine the real article without its cylindrical namesake precursor. But in fact if we reexamine the above characteristics which a barbell must have, (a substantial mass, or ballast, which can be easily gripped by both hands in a balanced, comfortable way, with a shape facilitating weightlifting exercises) the word “bar” does not appear. And so the venerable bar is in fact not part of the invention which I will set forth here, although this invention will still occasionally be referred to as a “barbell”.
It is a well-established fact that one of the cheapest, most convenient, and universally available sources of ballast is water. Over the years many attempts have been made to utilize the weight of water in a barbell. These attempts have largely utilized water filled weights attached to the traditional bar. (See U.S. Pat. No. 1,019,584 to Balston) With today's technology, the most economical, durable, versatile, and convenient way to contain and attach a handle to a volume of water happens to be with a plastic container. While plastics have certainly been incorporated into many modern barbells, it's usually the same old timeworn design, disk shaped weights on cylindrical iron bar. Normally the weights are a cast concrete disk, with a thin plastic shell providing merely a cosmetic exterior and a short-lived insurance against complete disintegration when the concrete cracks. Even when molded plastic water-fillable containers were introduced as weights, they were still attached to the ubiquitous iron bar. (See U.S. Pat. No. 4,199,140 to Ferretti.)
This is understandable since barbells have been around for such a long time, basically a relic of the iron age, and a mature technology with its reliance on a central cylindrical iron bar was in place long before the era of modern plastics. Barbells have achieved a certain traditional status, becoming in fact, an icon for the whole idea of weightlifting. The very maturity of this technology, however, is now what is holding it back; When an old technology works well enough, little need is seen for change. But times have changed, and materials have changed, and the new materials have different physical properties than the old, requiring new approaches to the design and engineering of products. Would you go out and buy a gallon of milk in a glass bottle, when a lighter, safer, easier to carry plastic alternative is available? How about a metal gasoline can, when a plastic one that won't rust, or bang around in your trunk is on the shelf next to it? Even the permanent gas tank on your car is probably plastic, because it's strong, durable, and economical.
Surely if plastics are such a versatile and durable material for containing and carrying liquids, and water is such a universally available source of ballast, a way to combine the two in the design of a modern barbell can be found. There are several methods of molding plastic into the shape of a closable container, including vacuum forming, injection molding, blow molding, and rotational molding. For our purposes, producing a large one-piece plastic container with a narrow threaded neck, the latter two show the most promise:
Rotational molding would offer the greatest design freedom. Using this process, virtually any shape or size of hollow plastic container can be formed, as long as the mold can be separated from the finished part. A threaded spout, or neck, can be easily formed into a part as long as it is exactly centered on the parting line, with its longitudinal axis perpendicular to the direction in which the two halves of the mold open and close. The finished parts are strong, thick walled, and durable. And the mold itself is not overly expensive to produce. If we could design the product, rotational molding could undoubtedly be used to produce a closable container, which when filled with water, would have a substantial mass, or ballast, easily gripped by one or both hands in a balanced, comfortable way, with a shape facilitating weightlifting exercises. But rotational molding is slow, requiring extended heating and cooling periods and large, cumbersome machinery to rotate many molds at a time. Why so many molds? Because each one can only turn out a few parts per day, due to the long cycle time. For these reasons rotational molding is used mainly to turn out short runs of large, heavy-duty products such as kayaks and children's swimming pools.
If we only needed a few hundred, or even a few thousand of this newly designed barbell, rotational molding might well be the way to go. But in this case we have to think bigger. The health and fitness movement has taken the world by storm, with just about everyone aware of the importance of exercise to good health. A truly revolutionary new product for the fitness market might easily sell into the millions of units. Of all the techniques for forming durable plastic containers in numbers of this magnitude, by far the most economical is blow molding. This is the technique whereby almost all modern plastic jugs and bottles are made. Even though the mold itself is very expensive, requiring special liquid-cooling channels, blow molding is fast, with a single mold able to turn out thousands of parts per day. It is well suited to our application, since a threaded spout, or neck can be handily formed into a blow-molded part. (provided that, as with rotational molding, such a threaded spout is exactly centered on the parting line, with its longitudinal axis perpendicular to the direction in which the two halves of the mold open and close.) If an ergonomic water-fillable barbell can be designed which can be efficiently produced by the technique of blow molding, it will be possible for almost anyone to personally own a complete set of barbells and dumbells having different weights, which in the past may have been cost-prohibitive. (Having a complete graduated set of freeweights is what commercial gyms and professional bodybuilders prefer; The convenience of being able to choose a barbell or dumbell of a given weight and begin using it immediately, without the delay of having to add or subtract plates, is important for continuity in a workout.) Blow molding offers economy of production, and great design freedom, but also has some constraints, which we will discuss, not found in other molding applications. Overcoming those constraints will turn a good idea into a great idea.
During the development of this invention, in concentrating upon the balance, ergonomics and manufacturability of a blow-moldable container for weightlifting, the concepts discovered and put forth here
Mulcahy John
Selsam Douglas Spriggs
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