Abstract:
An ultra light but resistive ball device for exercise is provided comprising: a flexible sheet with least one preliminary broken section of collapse for allowing contraction of the sheet under bias about at least one flex point in response to an exertion of hand grip. The sheet has two free ends extending substantially half the circumference of the ball and partially folded back on the sheet. Two lateral apertures are located at opposite ends of the free ends to permit an uninterrupted collapse of the sheet. A sheath envelopes the sheet to provide a slip resistant exterior surface for grasping the ball.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    A. Field of the Invention 
         [0002]    The present invention relates to an exercise device. More particularly, the present invention relates to safe impact ball for exercising hand grip as well as practicing ball skill between players. 
         [0003]    B. Description of the Prior Art 
         [0004]    Traditional balls used in recreational games and competition sports are closed spheres or ovoids inflated with air. Besides being hit, kicked, thrown and rolled between multiple players, when the balls are used as an individual&#39;s exercise tool they can improve the exerciser&#39;s muscle power, responsiveness and speed through catching and squeezing among other activities. 
         [0005]    For this purpose, different materials have been introduced to simulate the flexibility, bounce or texture of the conventional inflated balls in the category of novelty balls. They are gel-filled squeeze balls, ball shaped foam or simply a tennis ball that yields to a rather high strength hand squeeze. Gelatinous balls and foam balls have been considered more desirable in that they can be made solid simply by pouring the respective materials into a round mold cavity or through cutting and are carefree from maintaining a hollow center to fill. 
         [0006]    Gel-filled balls in the size of a baseball for example may provide an effective resistance to make a good grip exerciser, but in the hands of young ones they could easily become throwing objects that may hit someone hard resulting in injury. In contrast, a solid foam ball may be almost as light as air due to its perforated structure but lacks the material resistance to give a meaningful muscular improvement to the exerciser. Also, foam balls are normally made into a larger volume to gain a throwing momentum for old and new ball throwing games with less concern for injuries. 
         [0007]    Furthermore, conventional squish balls locally yield to applied forces but do not actually change their volumes in an intuitive manner to effect shrinkage and expansions in response to contracting and spreading hands during exercise. 
         [0008]    Therefore, an object of the present invention is to provide a new concept of a hand exercise device with the curvature of a ball and the lightness of thin layers but carries the resistance of an inflated ball to interact with hand muscles. 
         [0009]    Another object of the present invention is to provide a low cost exerciser device made of a single piece of thin expanded sheet molded into a spherical shrinkable surface. 
       SUMMARY OF THE INVENTION 
       [0010]    According to the present invention, an ultra light but resistive ball device for exercise is provided. The ball device comprises a flexible sheet with least one preliminary broken section of collapse for allowing contraction of the sheet under bias about at least one flex point in response to an exertion of hand grip. The ball device is of a ball shape which could resemble a baseball, a football, or a basketball. The term ‘ball shape’ therefore refers to shapes of commonly known balls. 
         [0011]    The sheet has two free ends extending substantially half the circumference of the ball and partially folded back on the sheet. Two lateral apertures are located at opposite ends of the free ends to permit an uninterrupted collapse of the sheet. A sheath envelops the sheet to provide a slip resistant exterior surface for grasping the ball. The sheet may be made of steel, plastic or other material that is suitable to provide an excellent spring bias as well as structurally reliable shape of the ball. The sheath is preferably made of silicon for its heat resistance and good grip. 
         [0012]    The two free ends may be are positioned diametrically opposite locations of the circumference of the ball. In one embodiment, the sheet has two hemispherical sections and an integral bias bridge for internally joining the hemispherical sections in diametrically opposite postures into a spherical form. The sheet is preferably either spherical or ovoid although other shapes may adapt well to embody the present invention. 
         [0013]    In a simpler embodiment of the present invention, the two free ends are overlapped over a predetermined circumferential area of the ball and have a common flex area in between the free ends. The resistive ball further comprises a tracking means having a number of grooves extending circumferentially and internally of the sheet from an outer one of the free ends down to the bottom of the sheet and elongated raised treads near the other inner free end for mating with the grooves so that the treads may follow the grooves in linear fashion to guide the ball contract and expand in straight response to gripping forces. 
         [0014]    Embodiments of the invention will now be described by way of example with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of a crushing squish ball according to one embodiment of the present invention. 
           [0016]      FIG. 2  is a side view of the squish ball of  FIG. 1 . 
           [0017]      FIG. 3  is a schematic side view of the squish ball compressed under a grasping force. 
           [0018]      FIG. 4  is a side view of the squish ball at an initial process of forming the major components in a single step. 
           [0019]      FIG. 5  is a side view of the squish ball with one of two hemispherical sections inverted with respect to a middle connection in a second step. 
           [0020]      FIG. 6  is a plan view of the squish ball of  FIG. 5 . 
           [0021]      FIG. 7  is a perspective view of an ovoid squish ball according to an alternative embodiment of the present invention. 
           [0022]      FIG. 8  is a view showing a spring cage of the ovoid ball with the covering removed. 
           [0023]      FIG. 9  is a cross sectional view of the squish ball taken along line  9 - 9  of  FIG. 8 . 
           [0024]      FIG. 10A  is plan view of a preliminary blank of the spring cage at an initial process of forming the major features in a single step. 
           [0025]      FIG. 10B  is a side view of the cage blank at a process of rolling the cage and positioning a prepared sheath. 
           [0026]      FIG. 10C  is a side view of the cage blank under a blow molding process using an injected high temperature air. 
           [0027]      FIG. 10D  is a side view of a full-blown ball device of the invention ready for use in exercising. 
       
    
    
       [0028]    Similar reference numbers denote corresponding features throughout the attached drawings. 
         [0000]    
       
         
               
               
               
             
           
               
                   
               
             
             
               
                 10: Ball Device 
                 11: Elastic Cover 
                 12: Cage 
               
               
                 14: Cage Upper 
                 16, 26: Free End 
                 18: Equitorial Plane 
               
               
                 20, 28: Proximal End 
                 22: Cage Lower 
                 24: Bridge 
               
               
                 30: End Hook 
                 32: Rounded Edge 
                 33: Raised Wall 
               
               
                 34: Axial Aperture 
                 36, 38: Semicircular Recess 
                 40, 42: Curved End 
               
               
                 43: Cage Blank 
                 45: Cage Half 
                 46: Cage Section 
               
               
                 100: Ball Device 
                 102: Cage 
                 104: Outer Edge 
               
               
                 106: Inner Edge 
                 107: Rolled End 
                 108: Groove 
               
               
                 110: Tread 
                 112: Sheath 
                 116: Tubular Form 
               
               
                 118: Blower Head 
                 A: Axis 
               
               
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    With reference to  FIG. 1 , an exercising ball device  10  according to the present invention is a spherical hand spring with rounded walls that are smooth and easy surfaces to touch. Ball device  10  comprises an elastic cover  11  with a gripping surface finish and a spherical cage  12  that may be resiliently compressed by hands grip. Cage  12  may be made of a light and sturdy sheet material such as thermoformable plastic or sheet metal. Such sheet material may be either solid or perforated as long as it provides the necessary spring for a grip exercise. Being a modified spring mechanism of solid walls, cage  12  has a range of motion under its own bias within the confinement of a dynamic sphere. Cage  12  is a ball, which is open along two diametrically opposite circumferential sections where free distal ends trail its opposite proximal ends. 
         [0030]    Referring to  FIG. 2  of a side view of cage  12 , this embodiment is an S-shaped double spring in which one of two hemispherical spring levers forms a cage upper  14  that starts from a free end  16  extending along approximately one half of the circumference of cage  12 . Normally, free end  16  may fall on an imaginary equatorial plane  18  intersecting the center of the sphere of cage  12  but the opposite proximal end  20  spanning approximately the rest circumferential half may extend past the equatorial plane  18 . This stepped profile may assist in fully interconnecting cage upper  14  always with a hemispherical cage lower  22 , which is formed diametrically symmetrical to cage upper  14 . Formed integral to cage upper  14  through an internal connection bridge  24 , the cage lower  22  has a free end  26  in the equatorial plane  18  encircling distal end  20  of cage upper  14  and a proximal end  28  terminating cage lower  22  inside free end  16  of cage upper  14 . Therefore, two cage halves  14  and  22  constantly maintain a secure interconnection by the oppositely protruding proximal ends  20  and  28 , which are received in opposite distal ends  16  and  20  on the same equatorial plane  18 . In addition, to help cage  12  maintain its sphere, a stop means may be provided to limit sliding movement of cage halves  14  and  22  away from each other. For this purpose, the free ends  16  and  26  may be slightly convoluted to form inward end hooks  30  while providing rounded exterior edges  32 . Facing end hooks  30 , proximal ends  20  and  28  have raised walls  33  for abutting against free ends  16  and  26  to complete the stop means. 
         [0031]    A round axial aperture  34  may be made cooperatively by two sets of semicircular recesses  36  and  38  formed at the transitions between free ends  16 ,  26  and basal ends  20 ,  28 . These transitional apertures  34  allow upper and lower cage halves  14 ,  22  to crisscross while accommodating forced deflections of cage halves  14 ,  22  over each other. Like the rest of cage  12 , bridge  24  is flexible in connecting the upper  14  and lower  22  and thus it may deform to absorb a crushing force exerted unto cage  12 . Bridge  24  is connected to proximal ends  20  and  28  of cage upper and lower  14  and  22  via oppositely curved ends  40  and  42  to initiate a linear yielding deformation of bridge  24  in direct response to hands squeezes. 
         [0032]    As shown in  FIG. 3  where ball  10  is halfway squeezed, bridge  24  may be deformed into large “S” and both cage halves  14 ,  22  recede to make a smaller diameter of cage  12  under bias. In this state of contraction, cage  12  may be wrapped by elastic cover  11  that has at least one opening corresponding to aperture  34 . Then, an appropriate surface pattern of irregularities may be applied by a coating or printing method to enhance the grip of ball  10 . 
         [0033]      FIGS. 4 and 5  illustrate steps of making the cage  12  where overhangs are substantially precluded from the structure of a preliminary cage blank  43 , which may be an injection molded plastic member. Alternatively, a shaped plain sheet metal may pressed under a single deep drawing to provide the same structure of unfinished cage  43 . A preformed cage half  45  is an inverted shape of cage upper  14  of finished cage  12  while an opposite cage section  46  provides cage lower  22  when it is inverted easily as depicted in  FIG. 5  by hands or a mechanical pusher (not shown). In shaping cage  12 , bridge  24  and curved ends  40 ,  42  need no machining or reshaping and may be held firmly by a stable support.  FIG. 6  shows the half finished cage of  FIG. 5  in plan view where bridge  24  is clear to see. 
         [0034]      FIG. 7  shows a squish ball structure according to an alternative embodiment of the present invention. In this embodiment, a ball  100  resembles a football, which is ovoid. Besides sphere and ovoid, other various polyhedral shells may work equally well to implement the present invention. Compared to the double flex ball  10  that has two separate contraction sections, this ball  100  includes a cage  102  that shrinks at one side by a curved outer edge  104  overlaying an involuted inner edge  106  both of which extend in the direction of the longer axis A of cage  100  as well as along the surface curvature of cage  102 . At both lateral sides, rolled ends  107  connect adjacent outer and inner edges  104 ,  106 , respectively. 
         [0035]    The cage  102  is enveloped by a sheath  112  made of a thin elastic material, which may comprise a generally smooth inner surface and an outer traction surface that has a good grip even in a wet hand. A separately formed silicone skin may provide sheath  112  sized to encapsulate cage  102  under a slight compression to keep the sheath  112  free of a slack. However, in order for the sheath  112  to accommodate a wide range of volume changes of cage  102  to under, say  50  percent of the normal girth of ball  100 , a number of creases  112  may be formed in the overlapping wall area of cage  102  between edges  104  and  106 . Sheath  112  may be locally fixed to cage  102  where least deformations take place such as the diametrically opposite area of the overlapping cage walls. To prevent undesirable movements between cage  102  and sheath  112 , a mechanical fastening may be made by forming one or more projections from inner walls of sheath  112  and corresponding bores on cage  102  so that they mate securely at assembly. 
         [0036]    The sheath  112  could be made of a microfiber elastic fabric material. The sheath should be light, stretchable and fitting over the cage  102 . 
         [0037]    Referring to  FIGS. 8 and 9 , cage  102  may have a tracking means comprising a number of tracks or grooves  108  extending on the inner surface from outer edge  104  about the axis A down to the bottom of cage  102  and elongated raised treads  110  near inner edge  106  for mating with grooves  108 . Treads  110  may follow the linear grooves  108  to help cage  102  contract and expand in straight response to gripping forces. In addition, by reducing contact surfaces of folded ends of cage  102 , the tracking means provides slick and fast actuations of ball  100  by the exerciser. 
         [0038]    A method of making ball  100  is illustrated in  FIG. 10  which is subdivided into  FIGS. 10A through 10D . In  FIG. 10A , deep drawing is used where a generally rectangular blank of either plastic or sheet metal is thermal pressed to obtain a deep hemispherical form  114  complete with the depressed grooves  108  and the embossed treads  110 . Thus formed blank  114  may be rolled into a tubular form  116  as in  FIG. 10B . Separate sheath  112  may be slipped over tubular form  116 , which is then grasped by round blower heads  118  for injecting pressurized air of high temperature through laterally open rolled ends  107  to blow mold cage  102  as shown in  FIG. 10C . During this thermal forming process, sheath  112  of silicon can withstand the high temperature as it limits the forced expansion of cage  102  to a predetermined volume. With certain amount of cooling time, blown cage  102  may set its target form.  FIG. 10D  shows the resultant exercise ball device  100 . 
         [0039]    It is also possible to form an integral sheath over cage  102  in two steps of wrapping a liner with an inner surface for maintaining the folding movements of cage  102  and an outer grip layer molded to cage  102  through the liner. First, cage  102  is prepared to take the final form shown in  FIG. 8 . The liner may be a thin elastic sleeve that is tightly wrapped on cage  102 , which has enough bias to retain its shape overcoming the sheath enclosure. 
         [0040]    A wide variety of plastic construction methods are available for constructing the sheath enclosure. One such method is to form the sheet as a flat sheet and thermoform the sheet over a mold. 
         [0041]    A mold is prepared to form a durable outer layer. Into the mold cavity, cage  102  is introduced and suspended by lateral openings  107  held and blocked by the mold wall areas to limit the resin from entering inside of the cage  12 . Then, with injection of silicon or other resin and upon curing of the resin in the mold the cage  12  coated by the thin stretched elastic skin may be retrieved for the next step. This second layer may have a surface pattern transferred from the mold to the resultant outer skin of finished ball in order to give the necessary grip for the exerciser&#39;s hands. 
         [0042]    Generally, a squish ball may be crushed under resistive bias through pushing away internally capsized air or yielding deformation of a semisolid foundation material like an elastic foam or jelly. However, in this invention, the thin and light cages described are formed to simulate the crushing effect of conventional grip exercisers. Different from conventional grip exercisers, the squish ball  10 ,  100  of the present invention looks like ordinary spherical or ovoid balls and one can easily immerse ones self in grip exercising while watching a game using that respective ball. Because the present invention ball  10 ,  100  itself has a very low mass throwing it to others is not harmful physically. 
         [0043]    Therefore, while the presently preferred form of the crush ball has been shown and described, and several modifications thereof discussed, persons skilled in this art will readily appreciate that various additional changes and modifications may be made without departing from the spirit of the invention, as defined and differentiated by the following claims.