Field of the Invention
The present invention relates to a ball, in particular a soccer ball, and a method of manufacturing such a ball.
Background Art
Balls, in particular balls for ball sports such as soccer, are usually sewn together from either single pieces of leather or synthetic leather. Balls may also be made with panels manufactured mostly from plastic that are glued on a bladder or on a carcass arranged onto a bladder for reinforcement. The latter kind of balls are also called laminated balls.
A sewn ball is manufactured from a plurality of pieces of leather or synthetic leather, the edges of which are folded inwardly and are sewn together by a needle. By corresponding choice of geometry of the pieces of leather or synthetic leather, an approximately spherical shape is provided by the sewing together. For reinforcement, fabric is usually glued on the backside of the pieces of leather or synthetic leather. A bladder of, for example, rubber providing the necessary airtightness is mostly inserted into the hand-sewn ball. The bladder also comprises a valve for inflating the ball. Between the bladder and the pieces of leather or synthetic leather, a carcass made of fabric or of one or more circumferential threads can be arranged for reinforcement and for protection of the bladder.
For such a sewn-together ball, the edges of the pieces of leather or synthetic leather are folded against the inside and thus are sewn with adjacent, i.e. adjoining pieces of leather or synthetic leather. In this way, a seam in the form of a groove is formed on the outside of the ball between adjacent pieces of leather or synthetic leather. Such a seam generally comprises a width at the top (i.e., at the side turning away from the center of the ball) of approximately 2.5 mm and a depth of approximately 2.0 mm.
It has been proven that the seams of sewn-together balls positively affect the aerodynamic properties by reducing the drag and accordingly allowing further flight distances. As a cause therefore, small turbulences on the surface of the flying ball are considered. Moreover, the seams contribute positively to the gripping properties of the ball, i.e., the ball can be gripped and controlled more easily.
Because the ball has a three-dimensional shape it, however, cannot be sewn by a machine, but has to be sewn by hand. The disadvantage is that such hand-sewn balls are subject to big fluctuations in production, which on the one hand can affect the quality and on the other hand imply variations in weight, size, spherical shape, flight, and gripping properties. Another disadvantage of hand-sewn balls is the considerable time of their manufacturing.
These disadvantages are partly overcome with laminated balls as the panels do not have to be sewn by hand for these balls. The usual fluctuations in production for hand-sewn balls are thus found in laminated balls to a lesser extent. Moreover, a laminated ball may at least partly be manufactured by corresponding machines. As a result, and by the elimination of sewing by hand, laminated balls can essentially be manufactured more quickly.
However, laminated balls have worse flight and gripping properties as the groove between the different panels comprises a lower depth (usually approximately 1 mm). Furthermore, there are no, or at best limited, possibilities for conventional manufacturing methods of laminated balls to influence the geometry (e.g., depth, width, cross-sectional profile, etc.) and the surface properties (e.g., static friction, haptics, roughness, etc.) of this groove.
U.S. Pat. No. 6,398,894 B1 shows a method of manufacturing a basketball which comprises among other things the following steps of: (a) supplying a sheet of rubber material; (b) folding, compressing and cutting the rubber material to make the rubber material into a bladder; (c) mounting a valve in the bladder; (d) inflating the bladder with air and curing the bladder; wrapping at least one thread on the inflated bladder; (f) gluing the rubber arches on the surface of the lagged layer; (g) making a groove at each junction between adjacent rubber sheets; (h) bonding a thinner and narrower strip than the rubber sheets at each junction of adjacent rubber sheets; (i) heating and curing the relatively large multiple rubber sheets together with the strips in a mold having multiple protruding ribs defined therein to make a basketball, whereby the basketball possesses multiple, relatively concave depressions having two slanting walls defined therein.
U.S. Pat. No. 3,887,416 relates to a method of manufacturing a soccer ball covered with leather. The soccer ball is made by taking a bladder that has been wound with nylon cord and is covered with a layer of rubber, all of which is conventional, and covering it with several rubber segments, including strips at the seams, built up areas adjacent to the seams and a shaped element at each end.
U.S. Pat. No. 5,541,662 relates to a sports ball and a corresponding method of manufacturing. An inflatable tube is inserted into a top layer formed by a thin rubber pocket manufactured from a material which does not allow a solution of a bonding agent to penetrate through the top layer and an inorganic lubricant is arranged between the tube and the top layer.
EP 1 080 745 B2 relates to a laminated ball with a bladder and a plurality of pieces of leather arranged thereon, wherein the pieces of leather are bonded together at the discontinuities. The pieces of leather are directly bonded together so that there are no gaps between the pieces of leather when applying adjacent pieces of leather onto the bladder.
U.S. Pat. No. 8,574,104 relates to an inflatable sports ball structure and a manufacturing method thereof. The inflatable sports ball structure comprises an inner bladder, a reinforced carcass, and an exterior material layer. The reinforced carcass covers the surface of the inner bladder, and has a thread wound layer. Part of the thread wound layer is embedded in the reinforced carcass and provides a constricting force towards the inner bladder, and a small remaining part of the thread wound layer may be exposed on the outer surface of the reinforced carcass.
The primary object of the present invention is therefore to provide a hail, in particular a soccer ball, which on the one hand is manufactured relatively quickly, easily, and cost-effectively, and on the other hand, comprises very good flight and gripping properties approaching those of a hand-sewn ball, but without the usual quality fluctuations for hand-sewn balls. In addition, the flight and gripping properties of the ball should be adjustable individually.