Buoys – rafts – and aquatic devices – Swimming aid to increase stroke efficiency – Foot attached
Reexamination Certificate
2000-03-10
2001-05-01
Sotelo, Jesus D. (Department: 3617)
Buoys, rafts, and aquatic devices
Swimming aid to increase stroke efficiency
Foot attached
Reexamination Certificate
active
06224443
ABSTRACT:
BACKGROUND OF THE INVENTION
Swim fins used by swimmers, body surfers, divers, and others in water are artificial fins, typically, of material like a resilient molded rubber or thermoplastic material, like ethylene-vinyl acetate (EVA), to improve propulsion speed and water agility. Swim fins may be prepared of synthetic materials, but one existing practice in the swim fin industry is to employ a swim fin having differential stiffness characteristics.
U.S. Pat. No. 5,290,194, issued Mar. 1, 1994, hereby incorporated by reference, discloses a swim fin which includes shoe and blade portions divided into longitudinal plural regions, each region representing an area of the fin formed from a particular material and of predetermined durometer range, so that the instep and toe region have different stiffness properties.
European Patent No. 0 436 927, published Jul. 17, 1991, as well as an improvement U.S. Pat. No. 5,435,764, issued Jul. 25, 1995, discloses a swim fin with a composite, partially multilayered blade section with a separate soft shoe section and an attached blade section composed of a base layer of a fairly rigid thermoplastic material, like ethylene-vinyl acetate (EVA) and a partial or full outer or top layer of a more resilient material, like a soft thermoplastic rubber.
It is desirable to provide a new and improved multilayered swim fin of controlled and selected durometer hardness and method of manufacture of such swim fins.
SUMMARY OF THE INVENTION
The invention relates to a swim fin and method of manufacture. In particular, the invention concerns a multilayer swim fin composed of layered materials of different durometer hardness, to improve swim fin performance, comfort, and appearance.
The invention comprises a swim fin having a foot section with a foot cavity, an extended blade section having a one and other end, and a base surface and a top surface. The blade section of the swim fin is designed for propulsion of the swimmer. The swim fin comprises a blade section which longitudinally increases in durometer hardness from the foot section to the other end of the blade section and generally perpendicularly from the base surface to the top surface. The swim fin comprises a plurality of overlapping, bonded, blade section layers of sheet materials of different durometer hardness.
The method of manufacture of the swim fin comprises a method of preparing an integral, molded swim fin having a foot section with a foot cavity and an extended blade section.
It has been discovered that a swim fin composed of longitudinal layers of materials of different durometer hardness (e.g., 20 to 120 durometers) and optionally, different durometer hardness perpendicularly, e.g., 20 to 120 durometers, as opposed to the prior art practice of defined differential stiffness regions along the longitudinal axis and perpendicular axis, provides a swim fin with a smooth, controlled flex or curve to the blade section as pressure is applied along the flutter-kick motion by a user. The integral molded swim fin with integral shoe and blade sections, as constructed and used, results in more powerful and smoother kick properties.
The layering of hard and soft rubber or elastomeric materials, to include thermoplastic materials, as well as curable materials, rather than the use of defined longitudinal regions of different stiffness and covered rigid blade sections, creates a swim fin with a more comfortable swim fin foot pocket, for example, of soft rubber or other material, with or without a fabric liner material with durometer hardness below 30, and yet provides a strong foot pocket and an integral, extended blade section, due to the layering effect of the materials from the one to the other end of the swim fin.
In addition, it has been discovered that layering the materials to form the swim fin also provides the opportunity for the creation of a design section or different colored (e.g., manufacturer) logos or other designs in the swim fin body. Typically, the layering of the rubber strap materials enables the top area of the swim fin forward of the foot pocket and toward the other end to be molded, not only of a different colored rubber, but of rubber of different, typically greater durometer hardness, e.g., 80 to 100 durometers.
The invention permits forming a soft foot pocket on a last from a moldable material, like soft gum rubber, and then blending-molding the foot pocket into the foot cavity of the swim fin.
The swim fin of the invention and the method of manufacture overcome some of the disadvantages of the prior art swim fin and manufacture techniques. Prior art multiple stiffness swim fins with selection regions tend to change properties abruptly in each region, while the swim fin of the invention provides the advantage of resiliency and flexibility, particularly and gradually along the blade section, where overlapping, multiple material layers are used in the body of the blade section extending from the foot section.
The swim fin of the invention, which may be symmetrical or asymmetrical in shape, provides a comfortable foot pocket which is molded and integral within the foot cavity section. The swim fin provides for a gradual, selected change in durometer hardness from the one to the other end of the swim fin and also perpendicular to the axis of the swim fin, by the use of layered materials.
The swim fin may vary in design and in materials used, but generally is formed of a solid or foam-moldable material, like a rubber or other elastomeric material, like a urethane elastomer, which materials may contain various fillers; stiffeners; additives; curing agents; fibers; modifiers; and other materials to provide selected properties, as required.
The materials used may vary in density, which usually varies with durometer hardness. The layers of materials used may vary in thickness; material; construction, e.g., solid or foam; and length and width. Generally, the layers include two or more layers which are of different hardness and will be stacked and at least partially overlap at the ends with other layers, so that there is no sharp break in the stiffness properties between the longitudinal axis regions. This layering provides, optionally, for a selected variation in durometer hardness in a direction perpendicular to the longitudinal axis, for example, a soft pocket outwardly to a harder external material and a soft internal material within the blade section end adjoining the foot section and a hard external material, while the blade section tip is typically composed of a single durometer material.
The swim fin is prepared by placing a plurality of selected separate layers of elastomeric or curable sheet materials, the same material or different materials, on a swim fin shoe last or shoe-blade last and then compression molding, under heat and pressure, the layers together in a mold, in a molding operation, to produce a molded, unitary, integral-formed swim fin.
The swim fin employs layers of sheet materials, e.g., 10 to 300 mils in thickness, such as 50 to 200 mils, to form a swim fin of selected design with a foot section and foot cavity and a blade section with a propulsion fin. Optionally, side reinforcing ribs, blow or drain holes, or other features may be formed or molded into the swim fin, and the trailing fin edge may be formed and shaped, as desired.
The sheet materials comprise thermoformable or curable moldable sheet materials of the same or different but compatible sheet materials, which on molding or blending are bonded or cured together to form a unitary fin. Optionally, but preferably, the foot cavity should have a fabric lining or have inserted a fabric to provide an integral, in-situ, soft foot pocket for foot comfort. The layers of sheet materials may be selected of different shapes, lengths, and thicknesses, and importantly, of varying durometer hardness, so that the application of overlapping layers of a selected sheet material, e.g., a heat-curable rubber, provides a swim fin with varying durometer hardness, but with no sharply defined regions of durometer hardness, which wo
Mehrmann Charles
Pekar Scott
Crowley Richard P.
Earth & Ocean Sports, Inc.
Sotelo Jesus D.
LandOfFree
Multilayer swim fin and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multilayer swim fin and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multilayer swim fin and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2434789