BACKGROUND OF THE INVENTION 
     Golf cages require framing as well as netting and the frames contribute in many cases more than 50% of the cost of manufacturing the cage. 
     Golf cage systems in the garage have been increasingly popular because they enable the golfer to practice during inclement weather. Because these cages are designed for outdoor use, they frequently create an errant ball hazard when erected and used in the garage. 
     It is a primary object of the present invention to ameliorate these problems in garage located golf cages and provide a lower cost golf cage system for the garage. 
     SUMMARY OF THE PRESENT INVENTION 
     In accordance with the present invention, a golf cage system is provided that uses the customer&#39;s garage door tracks as the frame for the cage. The cage is oriented to transfer loads from ball impact through the tracks into the frame of the door in a perpendicular direction to minimize track twisting. The cage has a ball striking drop panel suspended from a shaft mounted on rollers or end caps that ride in the rails and fastened to the tracks in their active position. Side panels and a top panel are also supported on the rollers at their forward ends and supported on another set of rollers in the tracks at the distal ends of the tracks. Low profile tie-downs are epoxied to the concrete garage floor to facilitate unobstructed foot and tire traffic. 
     The cage system is stored by rolling the panels around the shaft and shifting the rolled panels rearwardly to the distal ends of the tracks. A linkage assembly is provided that enables the shaft and main rollers to swing downwardly from the tracks so the shaft clears the door operator hardware. 
     There are two embodiments disclosed herein. The first is a commercial quality golf cage that uses locking roller sets and the second is an economy model that can be sold to many more customers at a price of as low as about $19.00 US at today&#39;s dollar value. 
     The economy model includes a forward panel supporting telescopic tube that adjusts axially to accommodate limited side track spacing variations. The tube is supported on end caps that are locked to the side rails by threaded fasteners in the range of ½ inch in diameter. 
     This cage system can be used as well for other sports such as batting cages. 
     Other objects and advantages will appear more clearly from the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a typical garage interior with the present golf cage system installed in its active operable position; 
         FIG. 2  is a fragmented perspective of the left door track of a typical garage door installation showing the roller mechanism for the golf cage system in its operative position including the stowage linkage assembly and the distal roller for supporting the ends of the side panels and the top panel along with the low profile tie-down assembly shown mounted on the garage floor. Note that in  FIG. 2  the horizontal and the vertical portions of the track are broken away to facilitate the enlarged part view in  FIG. 2 ; 
         FIG. 3  is a cross section of the left door track with the left main roller assembly shown in cross section and locked to the door track in its active position; 
         FIG. 4  is a sub-assembly illustrating the stowage linkage assembly for the left door track; 
         FIG. 5  is a fragmented perspective view of the left door track similar to  FIG. 2  with the golf cage system shown in its stowed position; 
         FIG. 6  is an enlarged top view of the low profile tie-downs illustrated in  FIG. 2 : 
         FIG. 7  is a front perspective of the tie-down illustrated in  FIG. 6  with a snap hook attached thereto, and; 
         FIG. 8  is a perspective partly segmented view of an economy model golf cage system according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings and initially to the perspective of  FIG. 1 , a golf or sports cage system is generally designated by the reference numeral  10  and is seen to be supported in a standard garage door opening and dosing system  11  including a left track  12 , a right track  13 , a torsion spring assembly  14  permitting a segmented door assembly  16  to open and close from its closed position illustrated in  FIG. 1 . The tracks  12  and  13  are supported by brackets shown in  FIGS. 2 and 5  on a door frame  18 . The tie-downs for the golf cage system  10  are permanently affixed to the concrete garage floor  20 , as will be seen from the following views. 
     The golf cage system  10  is supported on the horizontal portion of the side tracks  12  and  13  and is seen to include a forward ball striking double panel  22 , a left side panel  24 , a right side panel  26 , and a top panel  28 . 
     It should he understood that the panels  22 ,  24 ,  26  and  28  can be constructed of a netting material common in the golf net industry, which applies to other sports industries such as baseball, and can also include panels that are canvas or vinyl reinforced, for example, and possibly other panel materials. The forward double panel  22 , as will be seen in the other views, consists of a rear panel that is preferably a net material and a forward ball striking panel that can be canvas or a nylon reinforced vinyl material. The forward panel  22  is affixed to the floor by tie-down assemblies  30 , and the side panels  24  and  26  are fixed to the floor  20  by tie-down assemblies  31  and  32  below the distal ends of the door side tracks  12  and  13 . 
     Referring to  FIG. 2 , which is a fragmented perspective view of the left door track  12 , it should be noted that the track is fragmented at  36  and  38  so that  FIG. 2  can be shown larger to aid in the clarity of the parts. 
     The track  12  is channel-shaped in cross section as shown in  FIG. 3 , and is supported on the door frame by brackets  40 ,  41  and  42  that are arranged generally perpendicular to the door frame  18 . The orientation of the double ball striking panel  22  parallel to the door  16  and spaced from but adjacent the door  16  and door frame  18  enables the ball impact forces on the double panel  22  to be transferred axially through the tracks  12 ,  13 , through the brackets  40 ,  41 , and  42  into the door frame  18  in a direction perpendicular to the door frame  18  to minimize the twisting forces at ball impart imposed by the double wall  22  on the tracks  12  and  13 , which is an important aspect of the present invention. 
     The tracks  12 ,  13  have a horizontal portion  45 , a 90 degree bend portion  46 , and a vertical portion  47 . The golf cage system  10  is supported in the horizontal portion of the tracks  12 ,  13  so that the double ball striking wall  22  is positioned approximately three feet from the door  16 , but the door spacing can be varied depending upon the integrity of the double wall  22 . Note that the double wall  22  includes a forward netting panel  22   a  and a rear ball striking panel  22   b  that may be canvas or nylon reinforced vinyl for example. 
     As seen in  FIGS. 2, 3 and 4 , the golf cage system  10  is supported at its forward ball striking end by a double roller linkage assembly  50  that includes a main roller assembly  51  and a link  52 , and a stowage roller  53 . 
     The main roller assembly  51  supports a cross shaft  55  that supports all the forward ends of the netting panels and extends between the tracks  12  and  13  where a mirror image of the roller linkage assembly  50  is supported in the right door track  13 . A rear roller assembly  58  is mounted in the rear end of the side tracks  12 ,  13  and supports the upper reaches of the side panels  24  and  26  and the top panel  28 . 
     The sides of the double front panel  22  are fixed on concrete floor  20  by a pair of tie downs  30  that include snap hooks  60  shown in  FIG. 7 , and as noted the rear end of the side panels are tied to the floor  20  by the low profile tie-down  31  and an identical snap hooks  62  to snap hooks  60 . 
     The rear ends of the top panel  28  and the side panels  24  and  26  are tied to the rollers  28  by snap hooks  64  and  65  as seen in  FIG. 2 . 
     The main roller assembly  51  illustrated in  FIG. 3  is shown mounted in the channel-shaped left rail  12  and fixed thereto by a threaded fastener  68 . The channel track  12  is a mirror image of the channel track  13  and is seen to include horizontal wall  70 , top wall  71 , and cup-shaped lower wall  72  in which the roller assembly  51  is locked by bolts  68 , which requires the user to drill holes in the tracks  12 ,  13  at the proper locations. 
     Viewing  FIG. 3 , the roller assembly  51  supports the cross shaft  55  and is seen to include a cylindrical base  74  having a threaded aperture  75  therein that threadedly receives the bolt  68  and as the bolt  68  is threaded into aperture  75  it draws rod portion  74  against the interior of the rail wall  70  firmly locking the roller assembly  51  to the rails  12 ,  13 . The roller assembly includes annular outer tread  76 , a race  76   a , a plurality of ball bearings  77 , an inner annular race  78  that rides against the ball bearings  77 , and a side race assembly  80 . 
     The main roller assembly includes a cylindrical rod portion  81  that fits in an elongated bore  82  in the ends of the shaft  55  that with cross rod  83  permits an axial adjustment in the length of the rod  55  to accommodate limited variations in the spacing between the side tracks  12 ,  13 . Other arrangements besides the bore  82  and cross rods  83  can accommodate the same axial length adjustment for the shaft  55  as will appear to those with engineering skills in the mechanical arts. 
     The roller assemblies  53  are not locked to the tracks  12 ,  13 , while the roller assemblies  58  are lacked to the rear end of the rails  12 ,  13  in the position illustrated in  FIG. 2  with bolt fasteners such as fastener  68  illustrated in  FIG. 3 , requiring the customer to drill suitable apertures in the side rails  12 ,  13  to accommodate and permit the rollers  58  to be fixed to the rails. 
     The fixation of the roller assemblies  58  keeps the side panels  24 ,  26  and the top panel  28  in a taut position as shown in  FIG. 1 . 
     Viewing  FIG. 1 , the golf cage system is stowed by releasing the tie-downs  31 ,  32 ,  30  and snap hooks  64 ,  65 , folding the side panels  24 ,  26  against the double wall panel  22 , then folding the top panel downwardly against the folded panels, and then rolling the four panels around the shaft  55  into a bundle  86  illustrated in  FIG. 5  which is larger in diameter than illustrated in  FIG. 5  for simplicity. 
     This manipulation can be affected by attaching a crank, not shown, to the reduced rod portion  81  of the main bearing assemblies  51  and rotating the crank to facilitate this maneuver. Otherwise, it can also be done simply by hand grasping the bundle  86  and rotating it to roll up the panels onto the singular shaft  55 . 
     After the bolt fasteners  68  are removed, the roller assemblies  51  with the linkage assembly  50  are shifted to the rear end of the tracks  12 ,  13  and when the roller assemblies reach  53  reach the distal end of the tracks  12 ,  13  as seen in  FIG. 5 , the linkage assembly is swung downwardly to the position illustrated in  FIG. 5  with the linkage assembly vertical and the roller assemblies  51  suspended and supporting the rolled panels  86  as shown. The purpose of the linkage assembly  50  is to locate shaft  55 , roller assemblies  51 , and the material  86  out of the way of door operating linkages  90  commonly found in automatic door openers and closers in today&#39;s technology. 
     The rollers  53  may be locked in the position illustrated in  FIG. 5  to prevent the inadvertent misplacement of the golf cage system in its stowed position. 
     An important aspect of the present invention is that the tie-down assemblies  30  are low profile to permit both tire traffic and human traffic on the garage floor  20  without any significant impediment. 
     As seen in  FIGS. 6 and 7 , the tie-down assembly  30  is circular in configuration and has a major diameter of about 2 to 3 inches and a height of less than 0.500 inches and preferably closer to 0.250 inches. The snap hook assembly  60  is conventional and used throughout the present golf cage system at the four locations illustrated in  FIG. 1 , as well as the upper locations as indicated at  64  and  65  in  FIG. 2 . It should be understood that the snap hook assemblies are connected to loops  86  tethered to the panels  24 ,  26 ,  28  and the double panel  22 . 
     The low profile tie-down assembly  30  includes a one-piece circular annular stamping  92  having a frusto-conical portion  93  with an included angle of about 30 degrees to facilitate tire traffic and to not impede foot traffic. An inner portion of the circular tie down assembly  30  circular portion  94  is recessed from the upper surface of the frusto-conical portion  23  so that a pivoting ring  96  is seated in the recess portion  94  and is flush with the upper surface thereof when the tie down assembly  30  is in its inactive position shown in  FIG. 6 . 
     The tie-down assembly  30  includes a looped ring support  97  welded to the upper surface of the recess portion  94  and the assembly includes holes  100  and  101  to receive screws  102  and  103  to affix the tie-downs  30  to the garage floor. The securement of the tie downs  30  to the garage floor may be enhanced by abrading the upper surface of the concrete floor in the area of installation, and applying epoxy to the lower surface of the pleat  92  and at the same time drilling holes for the screws  102  and  103  in the floor and permitting the epoxy to cure overnight. The epoxy is preferably an RT cure epoxy material that is easy for the customer to use. It is also possible that depending upon the loads on the golf cage system to affix the tie-downs  30  to the concrete floor with epoxy only, although it is preferably done in an ambient environment above 50 degrees F. 
       FIG. 8  is a perspective partly segmented view of an economy model golf cage system according to the present invention. 
     This golf cage system is generally designated by the reference numeral  210  and is seen to include a net supporting telescopic metal tube  215  supported on door tracks  212  and  213 . Tube  215  has sections  216  and  217  adjustable axially to accommodate limited track spacing variations. 
     The ends of tube  215  are fixed into the hollow end caps  218  and  219  which are fixed into the tracks  213  and  212  by heavy threaded fasteners  221  and  222  that extend through holes  214  in the tracks  212  and  213  into threaded apertures  220  in the caps  218  and  219 . 
     Ball striking net  225  is suspended from tube  215  by a plurality of loops and the lower end of the net is tethered to the concrete floor by tie-downs  227  and  228  identical to those in the  FIGS. 1 to 7  embodiment.
A golf cage system that uses the customer's garage door tracks as the frame for the cage. The cage is oriented to transfer loads from ball impact through the tracks to the frame of the door in a perpendicular direction to minimize track twisting. The cage has a ball striking drop panel suspended from a shaft mounted on rollers or end caps that ride in the tracks and fastened to the tracks in their active position. Side panels and a top panel are also supported on the rollers at their forward ends and supported on another set of rollers in the tracks at the distal ends of the tracks. Low profile tie-downs are epoxied to the concrete garage floor to facilitate unobstructed foot and tire traffic.