Abstract:
A ball ( 10 ) comprising a discontinuous ball surface layer ( 12 ) formed by spaced elastic beams ( 18 ) curved about a ball center, the beams having ends thereof joined in nodes ( 26, 26 ′) distributed along the discontinuous ball surface layer. According to the invention, the beams ( 18 ) are also curved to establish lateral deflection thereof in the discontinuous ball surface layer ( 12 ) along the discontinuous ball surface layer between opposite beam ends for imparting yielding radial resiliency to the ball.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a ball comprising a discontinuous ball surface layer formed by spaced elastic beams curved about a ball center, said beams having ends thereof joined in nodes distributed along the discontinuous ball surface layer. 
       BACKGROUND 
       [0002]    Balls used for playing, sports and leisure may have different desired characteristics such as
       Good bouncing ability, also against yielding non-stiff surfaces   Predictable bounce-back characteristics   Minimized risk of injury to person and property, when used   Simple to manufacture   Possibility of compact delivery in parts       
 
         [0008]    The table tennis ball, having a stiff but still elastic surface layer, fulfills most of the above desired characteristics to a substantial degree. Regarding the desire to have a good bounce also against resilient and yielding surfaces, this ability is absent. 
         [0009]    The reason for the bouncing ability against resilient and yielding surfaces being absent is that the spherical ball surface layer, or shell, in itself constitutes a structurally very stiff geometry. Also the material of the elastic shell, celluloid or other plastic with similar characteristics is not an elastomer but is instead quite stiff. For balls with a stiff surface layer, a bouncing effect is obtained only against non-yielding quite stiff surfaces. 
         [0010]    There exist balls comprising a discontinuous ball surface layer, with holes being distributed along the discontinuous ball surface layer. These kinds of ball configurations can be conditioned by producibility or other reasons, exemplified as follows:
       Material and weight can be spared when not homogenously distributed over the ball surface   When playing, the ball can be received and caught with a finger in any one of the holes   The air resistance is affected   The appearance is changed       
 
         [0015]    One example of a ball exhibiting breached holes is the floorball ball which consists of a spherical ball surface layer provided with a number of round holes distributed along the ball surface. 
         [0016]    Interwoven balls constitute another group of balls exhibiting a breached surface layer. The so-called Tak Raw ball is a braided ball, originally produced from natural organic fibers, today often produced in plastic. One example of a modern design is disclosed in U.S. Pat. No. 5,566,937. Other examples of interwoven balls are shown in U.S. Pat. Nos. 6,568,982 B2 and 5,224,959. 
         [0017]    A further group of balls are constructed from a number of loops, each loop surrounding a hole. The loops are joined to one another along their respective periphery over a spherical surface, together forming a ball. One example is disclosed in U.S. Pat. No. 6,729,984 B2. This ball is sold under the trade mark O-ball®. 
         [0018]    Another variant of a ball having a similar structure is disclosed in US Patent Application 20080090486 where segments of loops extend between two opposite ends of the ball. 
         [0019]    U.S. Pat. No. 3,889,950 describes a ball of the aforementioned kind, where flexible strips extend along a spherical surface and connect to each other in connecting points which are evenly distributed along the surface of the ball, the resulting discontinuous surface exhibiting open holes in-between the flexible strips. The claims of U.S. Pat. No. 3,889,950 define a geometry that positions the strips in a way that results in a stiff ball surface. Also, the U.S. Pat. No. 3,889,950 defines the ball in such a way that a desired substantial distance is maintained between the strips, the intention being to have a resulting low air resistance. Due to the large openings between the strips, a design in accordance with the U.S. Pat. No. 3,889,950 will therefore automatically imply a ball exhibiting a non-predictable bounce. 
       DISCLOSURE OF THE INVENTION 
       [0020]    An object of the invention is to further develop a ball of the type initially described. A ball in accordance with the invention should primarily consist of a discontinuous, mainly spherical, elastic surface layer, the surface layer being discontinuous by being formed from beams defining holes or slots therebetween. Important is, however, that the ball surface layer should exhibit a pronounced radial yielding resiliency, whereby the ball will bounce not only against stiff surfaces but also against more yielding, non-stiff surfaces. It is desirable that other important ball characteristics are maintained, especially that the bounce shall be predictable. 
         [0021]    Another object of the invention is to create a ball posing a reduced risk and hazard for people and property by exhibiting a yieldably resilient ball surface. 
         [0022]    Another object of the invention is to create a ball which can be put together by modules, whereby production and transport is simplified. 
         [0023]    Another object of the modular configuration is that the ball can be delivered to the customer in parts, and that the ball can be put together by the customer before use, resulting in a combination of practical aspects and enjoyable puzzle activity. 
         [0024]    The above objects are obtained by features of the appended claims. 
         [0025]    According to an aspect of the invention, in the ball of the initially defined category, the beams are also being curved to establish lateral deflection thereof in the discontinuous ball surface layer along the discontinuous ball surface layer between opposite beam ends for imparting yielding radial resiliency to the ball. 
         [0026]    The discontinuous ball surface layer is formed by the beams and holes or slots defined therebetween, and the beams are consequently located in, and extending along, the discontinuous ball surface layer. By the wording that “the beams are also being curved to establish lateral deflection thereof in the discontinuous ball surface layer” it should be understood that each beam is not aligned with a geodetic curve, also known as an orthodrome, between both ends of the beam along the generally spherical curve along the discontinuous ball surface layer, but instead forms sideways, i.e. laterally, deflecting curves in the discontinuous ball surface layer along the discontinuous ball surface layer. 
         [0027]    Consequently, a ball in accordance with the invention comprises a mainly spherical, discontinuous ball surface layer consisting of beams curved about the ball center, the beams also being appreciably curved into a substantial lateral deflection along their running length in the discontinuous ball surface layer between its two endpoints, and also comprises rather narrow, breached slots located in-between the beams. As the beams are curved and spaced, adjacent beams define such slots therebetween, which are curved in various embodiments of the invention. 
         [0028]    The wording “spherical plane” is herein to be understood as the locus of all points of a surface having a given radius R. 
         [0029]    Each beam is in its one end, or in its vicinity, joined to the one end of at least two other beams to form a node, and some of the beams which are joined in their one end in this common node, extend out from this node to arrive in other and separate nodes with their second end, and a number of nodes exist that are substantially uniformly distributed along the discontinuous ball surface layer. 
         [0030]    The joining of beam ends in nodes can be made rigidly so that no relative movement can take place between the beam ends, but can also be made so that relative rotation can take place between the beam ends. 
         [0031]    In the case that the beam had been drawn the shortest distance in the mainly spherical discontinuous ball surface layer between its both ends and thereby followed the so called geodetic line, the discontinuous ball surface layer of the ball had been stiff and not yieldingly resilient in the radial direction of the ball. 
         [0032]    A ball in accordance with the invention is however characterized by the arrangement that the beams, forming the discontinuous ball surface layer, are not extended over the shortest distance along the mainly spherical discontinuous ball surface layer between beam ends, but instead curved laterally in the discontinuous ball surface layer, in a significantly anti-geodetic manner along their length. 
         [0033]    By this arrangement is accomplished the necessary geometric degree of freedom that allows the elastic but comparatively stiff properties of the beams to transform into a desired yieldably resilient deformation of the discontinuous ball surface layer as a result of external compressive mechanical load. This desired effect can be achieved even when the selected beam material possesses a rather high stiffness, as defined by the E-modulus of the used material. 
         [0034]    A reason for using rather stiff material in the elastic beams, is that the characteristics of such materials are desirable for spring applications by being springy with low internal damping, in this application implying a potential for good bouncing ability. 
         [0035]    Examples of suitable materials are different plastics materials, non-filled or filled with glass, carbon or other fibrous filler materials. 
         [0036]    Other suitable materials are different metals, for instance metallic spring materials. Other suitable materials can be wood or glass. 
         [0037]    The discontinuous ball surface layer of a ball in accordance with the invention can along its discontinuous surface consist of alternating elastic beams and cut-through slots. 
         [0038]    In one embodiment of the invention, the cut-through slot has such an extended shape that considering the total discontinuous surface of the ball, the sum of all slot areas divided by the sum of the square of all slot lengths is less than 0.25, more strictly defined as Σ(each slot area)Σ(each slot length 2 )&lt;0.25, whereby is achieved that the beam-separating slot is not too wide. As a ball in accordance with the invention exposes a discontinuous ball surface, an excessively wide slot might imply an unwanted risk of unpredictable bounce. 
         [0039]    In one embodiment of the invention, adjacent beams extend from one common node, laterally deflecting mutually uniformly in the discontinuous ball surface layer along the discontinuous ball surface layer. This arrangement allows for a repetitive pattern with a relatively uniform bouncing behavior of the ball for different points of contact against the surface to bounce against, along the discontinuous ball surface layer. 
         [0040]    In another embodiment of the invention, each beam changes its direction of lateral curvature, extending from a node. It is not excluded that the beams for a part of their length may follow the geometry of a great circle along the discontinuous ball surface layer. 
         [0041]    In further embodiments of the invention, the beam is laterally curved to extend in a spiral shape from one or both of its nodes in the discontinuous ball surface layer along the discontinuous ball surface layer, also with a possibility to have the beam adopt an S-shape. 
         [0042]    These embodiments having repetitive and partly spirally shaped lateral curvatures imparts several advantages, as described below. 
         [0043]    The width of the beam-separating slot can be controlled to be suitably and sufficiently narrow, thereby minimizing the risk for unpredictable bounce as a consequence of excessive discontinuity of the discontinuous ball surface layer. 
         [0044]    This continuous, slowly changing radius of curvature prevents transiently varying bouncing characteristics along the discontinuous ball surface layer. 
         [0045]    The spiral shape also allows the local beam coverage ratio—the relation between the area of the beams as part of the discontinuous ball surface layer, and the area of the discontinuous surface including also the slots, both considered within the same chosen limited area in the vicinity of a chosen point on the discontinuous ball surface—to be kept relatively uniform, regardless of chosen position along the surface of the ball, whereby also the continuous variation of resilience along the discontinuous ball surface layer can be restricted. 
         [0046]    The risk of unpredictable bouncing behavior is reduced also by keeping this continuous variation of resilience within restrictions. 
         [0047]    A ball in accordance with the invention can exhibit a remarkably yielding radial resilience even if the material of the beam in itself is quite stiff. Given an E-modulus of the material of the beam, the resulting yielding resilience is dependent on the extent of the lateral curving of the beam. In accordance with the invention, the beam is curved laterally along the discontinuous ball surface. This means that the beam, along its length from one node towards the second node, changes its direction. The maximal developing lateral directional change between two chosen points along the ball surface constitutes a measure of the extent of the lateral curving of the beam. 
         [0048]    In one embodiment of the invention, the maximal developing lateral directional change between two chosen points along the ball surface is a geometrical angle in excess of 60 degrees in order to achieve the desired sufficiently yielding radial resilience of the ball surface. 
         [0049]    To obtain an increased radial yielding resilience of the discontinuous ball surface layer, the maximal developing lateral directional change of the beam is increased. 
         [0050]    If the beams of the ball are made from a material with a higher E-modulus (stiffer material) compared to a reference ball, but given that both balls should possess a similar level of radial yielding resiliency, the ball with a stiffer beam material should exhibit a larger maximal developing lateral directional change than the reference ball, given that other geometrical characteristics are maintained. 
         [0051]    The spaced beams create openings in the discontinuous ball surface layer in the shape of slots, separating adjacent beams from each other along their length. 
         [0052]    The existence of these slots is a consequence of the fact that the discontinuous ball surface layer is built up from laterally curved beams. Had this not been the case, but instead the ball surface had been more or less continuous, the resulting inventive qualities by using beam elements would have been lost, and the desired functionality in accordance with the invention could not have been achieved. 
         [0053]    The beam-separating slot also has the function of decreasing the bounce-reducing mechanical friction between the beams. 
         [0054]    In one embodiment of the invention, the beam-separating slot is partly or wholly filled with a material that is significantly more flexible and deformable than the material of the beam, for instance a soft and yielding foam. With such an arrangement, a smoothing of the discontinuity of the ball surface layer can be obtained, with possible gains in the performance of the ball. 
         [0055]    Another embodiment of the invention incorporates a radially wavy shape of the beams along their length between their nodes, superimposed on the curvature about the ball center of the beams, across the discontinuous ball surface layer. With such an arrangement, it can be achieved to have an adjustment of the radial yielding resilience of the discontinuous ball surface layer, even though other geometrical dimensions are unchanged. 
         [0056]    The ball can be produced in one single part. One way to achieve this is to produce a spherical shell in which slots are cut out. 
         [0057]    Due to for instance producibility, it can be advantageous to divide the beam structure of the ball into separate parts. In different embodiments of the invention, one share of the beams making up the ball are joined together in their one end, thereby forming a modular spring element consisting of a number of beams including their common node. The modular spring element is referred to as “spring element” in the following. 
         [0058]    In their other end, the beams can be joined with the ends of other beams, which in turn belong to other spring elements. This process can be repeated for all non-connected beam ends to form a complete and user-ready ball. 
         [0059]    In other embodiments of the invention, the beam structure is divided into separate beams, or parts of beams. The separate beams, or parts of beams, are joined in their ends to form a complete and user-ready ball. 
         [0060]    In different embodiments of the invention, the pattern of nodes on the surface of the ball, and when applicable also the pattern of connecting points where beams are parted, is created by radially projecting characteristic geometrical features of an circumscribed imaginary polyhedron onto the surface of the ball. Examples of geometrically characteristic features are the corners and the centers of the polygons constituting the faces of the circumscribed imaginary polyhedron. 
         [0061]    A polyhedron of the type called Platonic solid consists of regular polygons which are all identical, a polyhedron of the type called Archimedean solid consists of two or more types of regular polygons. 
         [0062]    To generate the pattern of nodes to be found on the discontinuous surface of the ball to be built, the following or other polyhedrons can be used: Dodecahedron, icosahedron, truncated icosahedron, icosidodecahedron, cuboctahedron and rhombicuboctahedron. 
         [0063]    In different embodiments of the invention, the discontinuous ball surface layer is partly or completely provided with some layer, coating or covering, whereby can be achieved that the initial dynamic contact between the ball and the surface to bounce against is softer, whereby the bouncing characteristics of the ball can be influenced. 
         [0064]    In one embodiment of the invention, the volume within the discontinuous ball surface layer is partly filled with some kind of body to limit the maximum radial compression of the ball. By these means, it can be prevented that the ball is broken when for instance being stepped upon by mistake. 
         [0065]    The cross-section of the elastic beam making up the discontinuous ball surface layer can have different shapes, and the shape can also change along the beam between its opposite ends. 
         [0066]    In one embodiment of the invention, the beam consists of a wire of circular or of any other cross-section. 
         [0067]    Other objects, characteristics and advantages of the invention may be apparent from the claims and the following description of exemplary embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0068]      FIG. 1  is a view of an embodiment of a ball in accordance with the invention. The interior surface of the discontinuous ball surface layer is partly visible through the exterior face of the discontinuous ball surface layer. To improve the perception, the interior surface is provided with a distinguishing pattern. 
           [0069]      FIG. 2  is another view of the same embodiment of the invention, where one spring element is disengaged from its normally mounted position to clarify how the spring elements including the connection elements are assembled and cooperate in the ball. To improve the perception, the majority of parts at the rear side of the ball, which in reality would be partly visible through the discontinuous ball surface layer, are not shown. 
           [0070]      FIG. 3  shows two spring elements mounted together as portion of a ball, in accordance with the embodiment of the invention. 
           [0071]      FIGS. 4 ,  5 ,  6 , and  7  diagrammatically show different embodiments of the invention. For clarity purposes, only outlines of only the parts facing the viewer are shown. 
           [0072]      FIG. 8  shows a section cut through a beam, the beam being part of a single spring element viewed separated from the ball. 
           [0073]      FIGS. 9A and 9B  show the above mentioned sectioned beam in two different embodiments. 
           [0074]      FIG. 10  shows how an imaginary polyhedron, in this case a dodecahedron, circumscribed by the discontinuous ball surface layer can be used to generate a pattern of nodes on the discontinuous surface of the ball. 
           [0075]      FIG. 11  shows an embodiment of the invention where the spring element is formed by a single beam which together with other similar spring elements and connection elements can be mounted together to a ball in accordance with the invention. 
       
    
    
       [0076]    Throughout the drawings, elements having similar or same function are designated by same reference numbers. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0077]      FIGS. 1-3  show an exemplary embodiment of the invention consisting of twelve identical spring elements  14  and twenty identical connection elements  32 , which together form a generally spherical, discontinuous ball surface layer  12 , resulting in a complete, radially yieldingly resilient ball  10 . 
         [0078]    As is clearly shown in  FIG. 2 , the spring element  14  is composed by five identical beams  18  which in their one end  20  are joined in a central region  22 , and the center  24  of the spring element  14  coincides with a node  26 . 
         [0079]    Located in the generally spherical plane of the discontinuous ball surface layer  12 , each beam  18  belonging to a group of five beams  18 , extends laterally curved in a spiral shape  28  from the common node  26  at the one end  20 . 
         [0080]    The five beams  18  of the spring element  14  extend in the spiral shape  28 , out of the joining central region  22  so that each beam  18  at an opposing second end  30  connects to, and is joined or mounted to a connecting element  32 . A center  34  of the connecting element  32  coincides with another node  26 ′. Three spring elements  14  are connected in each connection element  32 . 
         [0081]    Adjacent beams  18  are spaced apart in a manner so as to define rather narrow curved slots  36  therebetween. 
         [0082]    Combined, the spiral shape  28  of the beams  18  and the rather narrow curved slots  36  therebetween provide a bounce-promoting and relatively uniform beam coverage ratio along the discontinuous ball surface layer  12 . 
         [0083]    With reference also to  FIG. 10 , the configuration of the ball  10  in accordance with this exemplary embodiment of the invention has its number and location of nodes  26 ,  26 ′ generated and patterned by radially projecting the corners  66  of an imaginary dodecahedron  72  and the centroids  64  of the regular pentagons  74  composing the imaginary dodecahedron  72 , circumscribed by the ball  10 , onto the spherical discontinuous ball surface layer  12 , thereby relatively evenly positioning and distributing a total of thirty-two nodes  26 ,  26 ′ along the discontinuous ball surface layer  12 , whereby also a corresponding bounce-promoting uniformity in bouncing behavior regardless of ball  10  attitude, is achieved. 
         [0084]    The beam  18 , as part of the ball  10  in accordance with this exemplified embodiment of the invention, extends from a node  26  in such a way that at a defined point  38  along its length, it changes its direction of lateral curvature, thereby adopting an S-alike shape  40  between its both ends  20 , 30 . This shape  40  of the beam  18  creates favorable conditions for achieving a yieldingly resilient deformation of the discontinuous ball surface layer  12 , promoting the bouncing behavior of the ball  10 . 
         [0085]    Of course, the beam can alternatively be drawn laterally spirally curved in one direction only, exhibiting this spiral shape approaching the node at one beam end, while being mainly devoid of lateral curvature towards the other node (this embodiment not shown here). 
         [0086]    In this shown exemplification of the invention, each beam  18  is in its second end  30  radially inwards deflected and extended and formed to join with the connection element  32 , the joining taking place by pushing the inwards pointing extension of the second end  30  of the beam  18  inwards into the connection element  32 . This procedure is repeated for the second end  30  of all beams  18 , whereby the ball  10  is completed. 
         [0087]    As made apparent by the drawings and the descriptions, this embodiment of the invention allows for producing the ball  10 , in accordance with the invention, in separate parts which when convenient can be mounted together to form the complete ball  10 . 
         [0088]      FIG. 3  shows in detail two next to another interfacing spring elements  14 , joined to each other with two connection elements  32 . The beam mean line  42 , the length of which equals the length of curved beam  18  itself, extends between the one end  20  and the second end  30  of the beam  18 . The corresponding but significantly shorter geodetic line or orthodrome  44  is approximately drawn in  FIGS. 3 ,  4  and  11 . 
         [0089]    The lateral deflection of the beam  18  in the discontinuous ball surface layer  12  between its both ends  20  and  30  is shown by the deviation d from the geodetic line  44 . 
         [0090]    The maximal developing lateral directional change between two chosen points along the discontinuous ball surface is set by the sum of the angles (α 1 +α 2 ) as shown in  FIG. 3 . 
         [0091]    The length  46  of the mean line of the cut-through slot  36 , the area  48  of the cut-through slot  36  as defined by the closed broken boundary line  50 , as well as the slot width  52  and the beam width  54 , are all shown in  FIG. 3 . 
         [0092]      FIG. 4  diagrammatically shows a view of an alternative embodiment of the invention. 
         [0093]    As shown, the ball  10  consists of twelve identical five-beamed spring elements  14 , twenty identical six-beamed spring elements  14 ′ and sixty connection elements  32 . 
         [0094]    The pattern of nodes  26 ,  26 ′ is generated from a circumscribed imaginary truncated icosahedron (not shown). 
         [0095]    The corners and the centroids of the regular pentagons and hexagons constituting the imaginary truncated icosahedron circumscribed by the ball  10  are radially projected onto the mainly spherical discontinuous ball surface layer  12 , thereby defining the positions of the nodes  26 ,  26 ′, the total number of nodes being ninety-two. 
         [0096]    In this exemplification, as shown in  FIG. 4 , each beam  18  extends laterally spirally curved out from its node  26  at its one beam end. Towards the node  26 ′ at the other beam end, coinciding with the connection element  32 , the beam  18  is, however, mainly devoid of lateral curvature. 
         [0097]    The lateral deflection of the beam  18  between its ends in the discontinuous ball surface layer  12  is shown by the deviation d between the beam mean line  42  and the geodetic line  44  between corresponding nodes  26 ,  26 ′. 
         [0098]    Of course, the beam can alternatively be laterally curved in an S-shape also for this embodiment (not shown here). 
         [0099]      FIGS. 5-7  diagrammatically show three different exemplary embodiments of the invention, all having the same pattern of nodes. 
         [0100]    The pattern of nodes is generated from an imaginary icosidodecahedron (not shown) circumscribed by the ball  10 . The centroids of the twelve regular pentagons forming part of the icosidodecahedron are radially projected onto the mainly spherical discontinuous ball surface layer  12 , thereby defining the positions of the nodes  26 , the total number of nodes  26  being twelve. 
         [0101]    Each beam  18  is laterally spirally curved towards both of its ends, changing its direction of curvature in the center thereof, thereby forming an S-shape. 
         [0102]    Different embodiments of the invention can comprise beams  18  that are divided along their length.  FIGS. 5 and 6  show such exemplifications with the corresponding connection points  56  for joining the divided beams  18 . A ball in accordance with these embodiments consists primarily of twelve identical spring elements connected to each other in the connection points  56 , the total number of these connection points  56  being thirty. 
         [0103]    The total number of thirty corners of the icosidodecahedron are radially projected onto the mainly spherical discontinuous ball surface layer  12 , thereby defining the positions of the connection points  56 . 
         [0104]    The joining of parted beam ends can be accomplished using a connection element  32  (shown in  FIGS. 2-4 ). 
         [0105]      FIG. 6  shows an exemplification where the lateral spiral curvature of the beam  18  is adjusted in shape to result in a near-constant width of the beam-separating through-cut slot  36  over its entire length. 
         [0106]      FIG. 7  shows an exemplification where the beam  18  for part of its length is divided 58 into two branches. 
         [0107]      FIG. 8  shows schematically a view of the major part of one spring element  14  cut loose from a ball  10 , in accordance with the invention. The denoted section  2 - 2  is cut along a part of the length of one beam  18 . 
         [0108]      FIGS. 9A and 9B  shows a section  2 - 2 , denoted in  FIG. 8 , in two different embodiments. 
         [0109]    In the embodiment as shown by  FIG. 9A , the beam  18  is curved about the ball center with its mean line mainly consistently coinciding with the mainly spherical plane of the discontinuous ball surface layer, as defined by a constant radius R. 
         [0110]    In the embodiment as shown by  FIG. 9B , the beam  18  exhibits a radially wavy curvature  60 , across the discontinuous ball surface layer  12 , superimposed on the beams  18  curvature about the ball center with the radius R. 
         [0111]      FIG. 10  diagrammatically shows how the pattern of nodes  26 , 26 ′ is generated when the centroids  64  and the corners  66  of the polygons  70  defining a polyhedron  68  circumscribed by the ball are projected in the radial outwards direction, represented by the radii  82 , onto the mainly spherical plane of the discontinuous ball surface layer, represented by the contour line  78 . In this example a dodecahedron  72  has been chosen as a representative of a general polyhedron. 
         [0112]    In the intersection points  76  with the imaginary spherical plane  78  representing the discontinuous ball surface layer, cylindrical domains  80  are shown. All points within any of these relatively small volumes are close to the corresponding true intersection point  76  and within these volumes  80  it is preferable to position the nodes  26 ,  26 ′. 
         [0113]      FIG. 11  shows an exemplification of a separate spring element  14  formed by a single beam  18 , which together with other similar or identical beams  18  can be joined in their respective one end  20  by a connection element  32 ′ to form an aggregated spring element. 
         [0114]    This aggregated spring element can then, as described earlier, together with other aggregated spring elements be assembled to a complete ball  10  by joining the second end  30  of each beam  18  with an interfacing second beam end  30  of another aggregated spring elements (not shown), and the joining can be done with connection elements  32  (not shown). 
         [0115]    This process can be repeated for all non-connected beam ends to form a complete and user-ready ball. 
         [0116]    The lateral deflection of the beam  18  between its ends in the discontinuous ball surface layer is shown by the deviation d between the beam mean line  42  and the geodetic line  44  between corresponding nodes  26 ,  26 ′. 
         [0117]    The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom. Modifications will become obvious to those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention or the scope of the appended claims.