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Dumbbell having secured assembly

Dumbbell having secured assembly description/claims

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1. Field of the Invention

The present invention relates to weight lifting equipment and more particularly pertains to devices used for weight lifting and weight training, such as barbells and dumbbells. The present invention also relates to weights for weight lifting equipment, and more particularly to a novel design for manufacturing and inserting a dumbbell handle into weighted heads, and efficiently and simultaneously attaining a secure assembly.

2. Description of Related Art

Due to increased concerns about overall health and appearance, strength training has become a popular method of increasing ones anaerobic endurance and building larger muscles. Strength training is defined as creating a resistance to the natural contraction of a muscle. One of the most popular forms of strength training is weight training, which uses the force of gravity to create a resistance against the natural contraction of muscles. Weighted objects are used to increase the magnitude of the force of gravity, thereby causing the muscle to work harder in performing a natural contracting movement.

Dumbbells and barbells with weights attached at opposing ends, also known as free weights, are one of the most common equipment types used in weight training and are detailed extensively throughout the prior art. In the current popular form, dumbbells are made by the attachment of weighted discs to opposing ends of the handle. The disks may be permanently attached, unitarily formed to the handle, or they may be attached by locking collars. The method of using locking collars in attaching weighted disks to a handle creates a dumbbell that is unnecessarily wide and difficult to balance.

One of the most critical factors in both designing and manufacturing a dumbbell is ensuring that a tight tolerance exists between the weighted discs and the handle. Without a tight tolerance, the weighted discs can wear out leading to a looser tolerance. As the tolerance becomes looser, the weights move laterally on the end of the handle and eventually rotate completely around the handle. The lateral movement and rotation of the weighted discs continues to worsen over time as the tolerance tightness decreases. Eventually the weights may even fall apart and injure the user. Even if the weighted discs are not an actual danger, they may cause apprehension or serve as a distraction to the user. In distracting the user attention and focus are taken away from the task of contracting the muscles to counteract the resistance of the weight, thus the user will not be able to obtain the full benefit from performing the weightlifting exercise.

As stated previously, weight lifting exercise equipment and particularly barbells and dumbbells are described extensively throughout the prior art. Specifically, U.S. Pat. No. 5,484,367 to Martinez illustrates a toy barbell set with a polycarbonate material bar that simulates the bending characteristics of steel. A key extends from the bar, and the weights and locking collars have a corresponding hole formed therein. One disadvantage of this invention, is that the barbell is meant for child use and not designed to support the amount of weight routinely used in an adult weightlifting exercise.

U.S. Pat. No. 4,529,197 issued to Gogarty describes a dumbbell with longitudinal groves on opposing sides that extend towards the middle of the dumbbell. The grooves are each of different lengths allowing the dumbbell to receive a series of additional weighted discs until the final desired weight is achieved. The additional weighted discs are secured to the barbell through a locking collar. The disadvantage of the present invention is that it uses a locking collar, thus making the resulting weighted equipment that is wide and difficult to balance.

U.S. Pat. No. 6,120,420 to Pearson et al. discloses a unitary exercise device with a light shell surrounding a denser core that are both attached at opposing ends of a handle. The use of a dense core in the weighted discs reduces the size of the overall exercise device. Furthermore, by monolithically incorporating the dense weighted disc as an extension of the handle, the problems associated with a tight tolerance between the weighted disc and handle is avoided. However, the disadvantage of this invention is by utilizing a dense core that is monolithically attached to the handle creates a device that is both expensive and timely to manufacture.

U.S. Pat. No. 7,048,678 issued to Technical Knockout, Inc., the Applicant Company in the instant case, and is entitled Dumbbell Having Interlocking Components. This design relates to a handle having rectangular opposing ends which mate with an interior member or insert of a complementary geometric shape. The interior member receives the end of the handle, and the insert itself is secured within a central bore or void in the weight head.

The instant invention constitutes an improvement over the designs disclosed and claimed in the '678 patent by employing an improved method of manufacturing a piece of exercise of equipment with a tighter tolerance between the weight and the handle.

Consequently, there is a need for taking advantage of efficient product designs, manufacturing and assembly techniques in the production of safe and cost effective exercise equipment, particularly dumbbells and barbells. There is also a need for a dumbbell and barbell design that inherently secures the weight to the handle with and extremely tight tolerances. This connection means must retains its structural integrity and maintain a tight tolerance throughout prolonged and extensive use. Finally, there is a continued need for exercise devices that do not require locking collars.

The present invention provides improved designs for manufacturing and assembling superior dumbbell exercise weights and in particular to an improved connection between the weights and handle. The designs eliminate unnecessary components, utilize press-fit manufacturing techniques for structurally sound products, provide a superior safe, secure and cost effective exercise device. The dumbbell design's improved connection greatly eliminates the lateral movement and rotation of the weights around the handle, thereby improving the structural integrity and increasing the lifetime of the product.

The present invention is an improved and inexpensive to manufacture exercise device with secure, extremely tight tolerance, non-rotating weights, that are attached to opposing ends of a central handle. The opposing ends of the handle have a cylindrical geometric shape that extends into the outer non-rotating weights. The handle can be of any geometric shape, rectangular, hexagonal, cylindrical, etc. The ends, in a primary embodiment, can be cylindrical, but in other embodiments can be rectangular or other geometric cross-sectional shapes.

The key inventive contribution relates to a series of generally parallel lateral grooves in opposing ends of the handle. These grooves receive the metal shavings that are generated during the press-fit manufacturing and assembly techniques, as hereinafter described.

The opposing ends of the metal handle are press-fit into steel inserts housed within, or integrally formed in, the weight heads. Because of the extremely tight tolerances and product specifications, metal shavings are produced as the handle end is forced (press-fit) into the complementary geometrically shaped aperture or void within the weight head or steel insert with the weight head. As the end of the handle is forced into the receiving void, the relatively thin metal shavings are created and pushed into the series of lateral grooves located on the ends of the handle. Because the shavings are removed from the press-fit surfaces (by falling into the grooves) a superior assembly is achieved. Without the presence of grooves to collect the metal shavings, irregular and pitted surfaces are created along the walls of the void as the metal shavings are force into the void along with the end of the handle. An irregular and pitted void wall surface make it impossible to create a perfectly flush fit of the handle against the wall of the void. Overtime, as the dumbbell is operated, the inner void surface becomes even more irregular and pitted as the existing marks continue to grow as the handle moves within the void. As the void surface becomes more irregular, the tightness of the tolerance between the handle and the receiving void decreases.

Without the grooves or channels of the instant invention, the shavings also remain between the outer surface of the handle and the wall of the void as an undesired foreign object. The metal shavings act as spacers and prevent a surface-to-surface flush fit between the outer surface of the handle ends and the walls of the weight receiving aperture.

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