Abstract:
An apparatus for curing cylindrical shaped elements having a liner, especially a liner of a rocket motor sleeve, where the cylindrical shaped elements are cured during rotation in a horizontal orientation. Horizontal rotation produces a liner with a substantially uniform thickness. The apparatus is mobile, compact, and has built-in robust safety mechanisms not compromised by the heat used to effect a cure. The cylindrical rollers are easily cleaned with minimal cross-contamination of one lot to another. Dripping of elastomeric materials from one assembly of rollers onto a stackable assembly of rollers below is eliminated. Each stackable assembly of rollers is independently controlled where each assembly is driven by its own motor, so rotation of one assemble does not affect another assembly of rollers.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefore. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a roller assembly, and in particular to an apparatus that is a portable assembly of stackable drawers of cylindrical rollers, where the apparatus is suitable for rotating, for example, a liner of a rocket motor sleeve and other cylindrical shaped elements during curing. 
     2. Description of the Prior Art 
     The background teaches that assemblies of rotating cylindrical rollers can be used to uniformly heat hot dogs. U.S. Pat. No. 6,800,314 to Evans et al. teaches an offset multi-tier rotary grill for grilling and heating food items such as hot dogs, sausages, melts and similar food items. The rotary grill includes heated rollers that are arranged in vertically spaced apart roller tiers. The prior teaches that assemblies of rollers are fixed, and offset multiple tiers. In cooking, the food is typically visible at all times, presumably to entice a customer visually. 
     SUMMARY OF THE INVENTION 
     The invention is an apparatus for curing cylindrical shaped elements having a liner, especially a rocket motor sleeve with a liner of a rocket motor sleeve, where the cylindrical shaped elements are cured as they are rotated in a horizontal orientation. Horizontal rotation during curing generally produces a sleeve having a liner with a more uniform thickness. 
     An aspect of the invention is that the apparatus can accommodate a production lot of motor tubes. Another aspect of the invention is that the apparatus is mobile, compact, and has built in robust safety mechanisms that are not compromised by the heat used to effect a cure. 
     Another aspect of the apparatus is that the cylindrical rollers used to rotate a production lot of motor tubes are easily cleaned, and that there is minimal cross-contamination of one lot to another lot of materials generated during a cure cycle. For instance, cross-contamination caused by the dripping of elastomeric materials from one assembly of cylindrical rollers on a stackable assembly of cylindrical rollers below an upper assembly, which, may be loaded with a production lot of motor tubes, is substantially eliminated. 
     A further differentiating aspect of the invention is that each stackable assembly of cylindrical rollers is independently controlled, that is each assembly is driven by its own motor, so that rotation of one assemble does not affect another assembly of cylindrical rollers. Independent control has the benefit that production lots can be started and stopped independently. If there is a failure by one assembly, it generally will not affect adjacent assemblies. 
     An advantage of the disclosed anti-tip safety mechanism, beyond the advantage that tip-over is eliminated, is that the mechanism may be tested by simply pulling out a drawer containing an assembly of cylindrical rollers. If the mechanism is working properly, there will be some resistance tension on the drawer to pull the drawer back to the closed, stacked position. The tension also does not increase as the drawer is pulled out further. However, the tension will dramatically increase when the anti-tip safety mechanism reaches the stop position. This dramatic increase in tension is accompanied by preventing more than one drawer from being capable of being pulled out. 
     The naming convention employed in this disclosure utilizes the accepted notation that articles “a” and “an” can denote one or more, and are not limited to a single number. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing invention will become readily apparent by referring to the following detailed description and the appended drawings in which: 
         FIG. 1  is a perspective view of an embodiment of the apparatus illustrating a vertical rack carrying multiple stackable drawers, where each drawer has an assembly of driven cylindrical rollers; 
         FIG. 2  is a frontal view of the apparatus illustrating a pair of miniature screw jacks, where all eight drawers are closed and all CPC plugs are plugged into their respective receptacles; 
         FIG. 3  is a perspective view of an embodiment of the apparatus with all the drawers removed exposing the components of the cart, which include a vertical rack mounted on the base with an anchor shackle, where the base is substantially a rectangular I-beam assemblage and the rack provides support and movement for the drawers, the vertical components of the rack have portals to channel air flow across the cylindrical rollers and the sleeves/tubes rotating on the cylindrical rollers; 
         FIG. 3   a  is an enlarged partial view of the rack shown in  FIG. 3 , that illustrates components of the anti-tip safety mechanism and the track for the bottom drawer, where the track is a C-channel shape, which abuts the left rear support, to provide support for the tray rollers  135 ,  138  and  139 . Air flows over channel  14  thru the motor tubes on the cylindrical rollers to cure the sleeves while the sleeves are being rotated by the assembly of cylindrical rollers. Air may also flow between angles  168   a ,  168   b , support base  12  and covers  16   a  and  16   b  shown in  FIG. 10  and  FIG. 1 ; 
         FIG. 3   b  is an enlarged partial view of the rack shown in  FIG. 3 , that illustrates a weight constraint cable path around the V-grooved roller  22  attached to the base; 
         FIG. 3   c  is an enlarged partial view of the rack shown in  FIG. 3 , that illustrates how the miniature screw jack enables the cart to be elevated and substantially locked into position, where the base of the jack is hexagonal, and therefore easily turned with a wrench; 
         FIG. 4  is a schematic illustration of the anti-tip safety mechanism, where the safety mechanism insures that only one drawer is open at a time, therein insuring that the apparatus does not become unbalanced, and tip over; 
         FIG. 5  illustrates how the schematic shown in  FIG. 4  can be incorporated in the apparatus, where in  FIG. 5  the drawer actually is able to move a distance that approaches or is greater than the height of the apparatus, the track rollers at the front of a track indicating the extent of possible movement, where to lengthen horizontal movement of the drawer and shorten movement of the weight, the drawer cable is looped multiple times around V-groove rollers from the cross bar to the weight resulting in a pulley-like system that creates a mechanical advantage; 
         FIG. 5   a  is an enlarged partial view illustrating how the counter weight  220  is positioned on the cable, with a wire rope grip fitting  224 , which locks the weight at a specific position on the cable and joins ends of the weight constraint cable; 
         FIG. 5   b  and  FIG. 5   c  are essentially mirror images of each other, and they illustrate how the ends of the drawer constraint cable  203  is generally connected to a left and right side of the rack or base (not shown), where the connection is effected using swivel leveling mount fitting, hex locknuts, and wire rope grip fittings, where the drawer constraint cable and the weight constraint cable  205  is routed through a plurality of V-grooved rollers; 
         FIG. 6  is an enlarged partial view of the guard support shown in  FIG. 1 , where the guard support, which is mounted to the right handle mount, supports the gear motor and the CPP Plug, wherein the illustrated guard support is a single piece, having a guard base section for mounting the guard support to the handle mount  144 , a substantially cylindrical section for mounting the gear motor, a substantially linear section for supporting a chord for the CPP plug, and a substantially rectilinear section with a circular opening for mounting the CPP plug; 
         FIG. 7  is a perspective view of a cylindrical roller sprocket, where the sprocket has teeth on a hub with a bore, where the bore has an inside diameter that will accommodate a bolt; 
         FIG. 7   a  is a planar view of the cylindrical roller sprocket illustrated in  FIG. 7 ; 
         FIG. 7   b  is a cross-sectional view of the cylindrical roller sprocket illustrated in  FIG. 7   a , taken along sectional line  7   b - 7   b;    
         FIG. 8  is a diagrammatic view of an assembly of driven cylindrical rollers which are rotating a partial production number of rocket motor tubes/sleeves fitted with flanged ring shaped masks. 
         FIG. 9  is a substantially frontal view of a tilted drawer, wherein the drawer is tilted so as to make the track cylindrical rollers and V-groove cable rollers mounted on the drawer extensions more easily seen; 
         FIG. 9   a  is an end-on left side view of a drawer; 
         FIG. 9   b  is an end-on right side view of a drawer; 
         FIG. 10  is a perspective rear of the apparatus shown in  FIG. 1 , where the drawer constraint cable loops four times from the cross bar to the weight, and all of the drawers are closed so the start position for the weight is around the sixth drawer; and 
       In  FIG. 11  is a perspective frontal overhead view of the apparatus positioned inside and flush with an integral oven  50 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is an apparatus that is an assembly of cylindrical rollers, where, in one exemplary embodiment, the assemble is in a frame, where the frame constitutes stackable drawers of cylindrical rollers that are individually driven. The apparatus is suitable for rotating and may be used for curing a liner of a rocket motor sleeve and other cylindrical shaped elements during curing. Generally, rocket motor sleeves are substantially case bonded grain sleeves that are grit blasted, and lined with a curing fire retardant liner. In one case, the liner has an oligomeric material, such as hydroxypolybutadiene, (sometimes referred to as R45-HT and was made by ARCO) or carboxypolybutadiene that is cured into a polymeric material. The curing process is augmented through the application of heat, where the temperature is generally on the order of 150° F.-200° F., and more particularly about 165° F. As shown in  FIGS. 1 and 8 , the ends of the sleeves are fitted with flanged ring shaped masks forming a doughnut-shaped surface, which serves to exclude the liner from the ends of the cylindrical shaped element and elevate the sleeves so that the sleeves need not actually come into contact with cylindrical rollers  102 . Therefore, the diameter of the masks generally define the design diameter such that adjacent masks do not contact each other upon rotation. A gear motor  124  with a powered sprocket  112  drives a chain  114 , which is connected to a sprocket  108  (shown as either  108   b  motor/right or  108   a  opposing/left) on a cylindrical roller  44 . In the illustrated embodiment each cylindrical roller  44  has a pair of sprockets, where a sprocket on one end is connected to the cylindrical roller on the right, and on the other end the sprocket is connected to the cylindrical roller on the left. As shown, the second cylindrical roller is connected to the third cylindrical roller, and on the other end the second cylindrical roller is connected to the first cylindrical roller. The first cylindrical roller is driven by the motor  124 . The net effect of this sequential assembly is that all cylindrical rollers turn in the same direction, there are no long lengths of chain, and the cylindrical rollers rotate at substantially the same speed as established by the gear motor with the gear sprocket. 
     This arrangement may alternately be described as having a first sprocket on one end and a second sprocket on an opposing end, where the first sprocket on the first cylindrical roller is connected with a first chain to the driven sprocket on the gear motor. The second sprocket on the first cylindrical roller is successively connected through a second chain to a second sprocket on a next roller, such that the next roller is driven by the first cylindrical roller. Subsequently, therein making the next cylindrical roller a second driven cylindrical roller, which has a first sprocket that successively drives a following cylindrical roller, where the pattern repeats until all cylindrical rollers are driven and all rotate in the same direction. The chain length is limited to two sprockets, therefore the profile (height) of a drawer may be kept low as there is minimal chain sag, no intervening gears are necessary, little contamination, fewer parts, less weight and the assembly is capable of being easily reconfigured to handle larger diameter motor sleeves. 
     As shown in other drawings, each drawer of assembly of cylindrical rollers has its own individual gear motor. This configuration enables individual drawers to be processed at different rotational speeds. 
     In the illustrated exemplary embodiment, the cylindrical rollers are substantially parallel and separated by a distance that is sufficiently wide to ensure that the masks  30 , which have a known OD diameter  34  on one sleeve  36 , do not contact the masks on an adjacent sleeve. The masks may be selected so they fit the sleeve ID  38  and OD  40 . The ID  38  of the mask may be a consideration as it may influence air through the sleeve  36  during curing. The distance separating the cylindrical rollers must be sufficiently close to retain the sleeves when rotated. The cylindrical rollers  44 ,  102  are generally covered by a protective coating  106  (Heat shrink PTFE tubing), and this feature needs to be considered in determining the distance that the cylindrical rollers are separated. 
     As will become further evident, the invented apparatus is compact, having high product density; there are numerous aspects that reduce cross contamination; and a safety cable system prevents tip over by allowing only one drawer to be opened fully at a time. 
     A perspective view of an embodiment of the apparatus  10  is illustrated in  FIG. 1 , which includes a vertical rack  162  on a cart  160  carrying multiple stackable drawers  100 , where each drawer has an assembly of driven cylindrical rollers  102 . In the illustrated embodiment there are eight stackable drawers. The drawers are loaded in the vertical rack stack in a manner similar to drawers in a chest-of-drawers. As seen in the open drawer  100 , the assembly of driven cylindridal rollers  102  may, in an exemplary embodiment, include twenty six driven individual cylindrical rollers  104  in the drawer  100 . A pair of adjacent cylindrical rollers rotate one cylindrical sleeve  36 , and therefore, the assembly of cylindrical rollers  102  in one drawer may, in an exemplary embodiment, turn thirteen rocket motor sleeves  28 . Assuming, in an exemplary embodiment, all eight drawers have thirteen cylindrical sleeves  36 , the apparatus may have the capacity to rotate and cure one hundred and four solid rocket motor sleeves  36  or a comparable number of similar sized cylindrical elements. 
     The illustrated open drawer  100  has a catch tray  120  to contain any generated material (such as curing polymer) to a single drawer; and a face plate  140  with a left handle mount  142 , a right handle mount  144 , and a handle  148 . On an outside surface of the face plate  140  is mounted a guard support  122  to which is attached an explosion proof CPP plug  128 , and a gear motor  124  with a motor sprocket (not visible), where the gear motor  124  has a gear motor screen  126 . 
     The guard support  122  is shown in  FIG. 1  and in detail in  FIG. 6 . The guard support  122  is mounted to the right handle mount  144  which is mounted to the face plate  140 . The guard support  122  supports the gear motor  124  and the CPP Plug (explosion proof)  128 . The illustrated guard support  122  is a single piece, having a guard base section  122   a  for mounting the guard support  122  to the handle mount  144 . The guard support  122  further includes a substantially cylindrical section for mounting  122   b  the gear motor  124 , a substantially linear section  122   c  for an electrical chord for the CPP plug  128 , and substantially rectilinear section with a circular opening  122   d  for storing the CPP plug  128 . 
     As shown when the second drawer is opened the CPP plug  128  has been turned to the unlock position and unplugged from the corresponding receptacle  186  mounted on the vertical rack. When the drawer is closed the CPP plug  128  is handy, and it can be plugged back into the receptacle. An explosion proof switch box  180  with a switch  182  and a pilot light  184  is mounted proximate to the receptacle  186 , connected by conduit  188 . When all drawers are closed, the face plates cumulatively form a thermal barrier, isolating the gear motors  124  from exposure to heat. The face plates function as a door to retain heat and move air. The top cover  16  (shown in  FIG. 1 ) includes panels  16   a  and  16   b , which also function to protect the contents within the apparatus and to provide some degree of insulation. 
     Each drawer  100  has a left angle element  150  and a right angle element  152 . The left and right angle elements  150 ,  152  are oriented such that they cover the sprockets and chains, as well as support the drawer. The back of the drawer has a drawer cross bar  146  (not visible in  FIG. 1 , see  FIG. 9 ). As illustrated in  FIG. 9 , the drawer cross bar  146  is supported by a left extension  130  on the opposing side projecting from the left angle element  150 , and a right extension  132  projecting from the right angle element  152  on the motor side. The right extension  132  has a V-grooved retaining roller  22  and a stud mounting track wheel  138  that is corrosion resistant. Likewise, the left extension  130  has a V-grooved track retaining roller  22  and another stud mounting track wheel  139  that is corrosion resistant. As may become apparent in forthcoming drawings, the V-grooved retaining rollers  22  intersect a constraint cable assembly  205  that is a component of an anti-tip mechanism  200 . Other elements of the drawer are best viewed in  FIGS. 9   a  and  9   b , which are end-on side views. Substantially, each individual cylindrical roller  104  has two sprockets, a motor side sprocket  108   b  and an opposing side sprocket  108   a . The sprockets on each side are connected in pairs with a chain  114 , such that all cylindrical rollers are driven by a motor sprocket  112  (shown in ghost with dashed lines) and all cylindrical rollers  102  rotate in the same direction. The illustrated chain has a connecting link and is typically composed of a polymeric material, such as acetal. The composition of the chain is not a limitation. 
     In an exemplary embodiment, a sprocket is shown in  FIGS. 7 ,  7   a  and  7   b . As previously stated substantially each cylindrical roller  104  has two sprockets  108 , which are substantially identical, differing only in their location. A sprocket on the motor-side or right is numbered  108   b , and those sprockets on the opposing or left side are numbered  108   a .  FIG. 7  is a perspective view of an exemplary sprocket  108 . The sprocket  108  includes teeth  109  on a hub  115  with a bore  111 . The bore  111  includes an inside diameter  113 . The sprocket is generally mated with an end of a cylindrical roller  104  with a bolt. Generally, the sprocket  108  does not also serve as a bearing for the cylindrical roller, but it is anticipated that this configuration may be possible. 
     Referring again to  FIGS. 1 and 9 , each of the cylindrical rollers  104  of the cylindrical roller  102  is covered with heat shrink PTFE tubing  106  (one tube is shown as a pair of dashed lines). The tubing is transparent-trimmed to cover the cylindrical roller  104 . PTFE is a synthetic fluoropolymer of polytetrafluoroethylene. The PTFE protects the cylindrical rollers, and makes them easy to clean and cleaning is less frequent as PTFE is a low stick material. Additional low stick material are anticipated. 
     The front of the apparatus  10 , as shown in detail in  FIG. 2 , has a of pair miniature screw jacks  190 , 192  with a fixed saddle (generally 3 ton capacity, 4″ max height). The screw jacks enable the cart to be elevated and substantially locked into position. Miniature screw jack  (Right)    190  extends from a lift plate  (Right)    194  (front motor side), and miniature screw jack  (Left)    192  extends from a lift plate  (Left)    196  (front opposing side) that is respectively attached to a right front angle  166   b  and a left front angle  166   a  (best seen in  FIG. 3 ). The base  12  is largely hidden by the front skirt plate  176 . Note, that in  FIG. 2  all drawers  100 , and in an exemplary embodiment eight drawers, are closed, and all CPC plugs  128  are plugged into their respective receptacles  186 . 
     As shown partially in  FIG. 1 , and in greater detail in  FIG. 3 , the cart  160  has a mechanism to facilitate movement. The exemplary embodiment includes four swivel casters  198  attached to a base-plate  199 , where the casters have a hard rubber tread such as, Nylon, or polyurethane or another tough elastomeric material that is non-abrasive. The caster  198  may also have a stop  197  that sets the direction and freedom of the caster to move. It is anticipated that in some exemplary embodiments casters may not be used. For instance, the apparatus may be loaded on a heavy duty pallet and moved with a fork lift, or the apparatus may be on a rail carrier. 
     In  FIG. 3 , all the drawers are removed exposing the components of the cart  160 , which includes a vertical rack  162  mounted on the base  12  with an anchor shackle  158 . The shackle is used to tow the apparatus, and is generally covered by front plate skirt  176  (shown in  FIG. 2 ). 
     The base is substantially a rectangular I-beam assemblage. The rack  162  provides support and movement for the drawers and the vertical components of the rack have portals  189  to accommodate drawer extensions  130 , 132  (see  FIG. 9 ). Air can flow can easily move side-to-side across the cylindrical rollers  102  and the sleeves  28  rotating on the cylindrical rollers (previously identified in  FIG. 1 ). The vertical rack  162  is largely built on the base  12 , which support a rack of tracks  14  based on a C-channel or C-shaped channel. In an exemplary embodiment, there are eight C-channel tracks on the left and eight C-channel tracks on the right. The top and bottom tracks are numbered. The rack includes a left front angle  166   a , a right front angle  166   b , a left rear angle  168   a , a right rear angle  168   b , a rack cross bar  178 , a left rear support  170   a , a right rear support  170   b , a top front angle  174 , a left front support  172   a , a right front support  172   b , multiple V-grooved track rollers  22   a ,  22   b , and front plate skirt  176  (shown in  FIG. 2 ). The left rear support  170   a  and the right rear support  170   b  and formed so as to be contiguous with the channel, therein forming portions of the rack of tracks. 
     The V-grooved track rollers  22   a ,  22   b  are permanently lubricated, and function as bearings for a drawer  100 , providing support for an lower edge of drawer angle elements  150 , 152  (shown in  FIGS. 5 and 9 ). The track wheels  138 , 139  (see  FIG. 9 ) on the drawer extensions  130 , 132  move through the C-channel track  14 , through the support portions and in the illustrated variation through portals  189  (more of this later  FIG. 10 ,  189 -right and  189 -left). The same V-grooved rollers  22  also function as guide pulleys  22  for the cable in the anti-tip mechanism  200 . The adaptation of the same element, such as V-grooved rollers  22 , to perform multiple tasks demonstrates consideration and inventiveness that makes the apparatus more commercially viable and a conservation of inventoried items. 
     Referring to  FIG. 3   a , which is an enlarged partial view of the rack shown in  FIG. 3 . There is no drawer, and the cable in the anti-tip safety mechanism  200  has not been strung. The view is of the track for the bottom drawer. The track is C-channel  14 , which abuts the left rear support  170   a . The left rear support  170   a  is mounted on the left rear angle  168   a . The left rear angle  168   a  has a portal  189  for each track, which provides an opening to accommodate drawer extensions  130 , 132 . A drawer constraint cable  203  has been added to the drawing to illustrate its path around the V-grooved roller  22  on drawer extensions  130 , 132 , as illustrated in  FIG. 9 . Access to the track from the back of the vertical rack, in this embodiment, the eighth track, is marked by an upper V-grooved roller  22 -U 8  and a lower V-grooved roller  22 -L 8  mounted on the left rear support  170   a . The extension V-grooved roller shown in ghost is labeled  22 -E 8 , to differentiate its closed drawer position between the upper V-grooved roller  22 -U 8  and a lower V-grooved roller  22 -L 8 . When the drawer is opened, the cable is extended and the V-grooved roller  22 -E 8  moves to a new position. 
     Referring to  FIG. 3   b , a weight constraint cable  205  has been added to the drawing to illustrate its path around the V-grooved roller  22  attached to the base  12 . The drawing furthermore illustrates the relative close proximity of the weight constraint cable  205  to the right rear angle  168   b  and the right rear support  170   b.    
     Referring to  FIG. 3   c , the miniature screw jack  190  enables the cart to be elevated and substantially locked into position. The base  191  of the jack may be, in an exemplary embodiment, an hexagonal shaped jack, and therefore easily turned with a wrench. Miniature screw jack  (Right)    190  extends from the lift plate  194  (front motor side). Lift plate  194  is fasten to the bottom front of the right front angle  166   b . A similar arrangement is on the left side with right front angle  166   a  (see  FIG. 2 ). 
       FIG. 4  is a schematic illustration of the anti-tip safety mechanism  200 . The safety mechanism insures that only one drawer is open at any time, therein insuring that the apparatus does not become unbalanced, and tip over. The safety mechanism has a counter weight  220  that is guided by a weight constraint cable assembly  205  (indicated by the dotted line). In the schematic illustration the apparatus has two drawers  100 , an upper drawer  100 -D 1  which moves on the top track, track 1; and a lower drawer  100 -D 2  which moves on the lower track, track 2. As previous discussed and shown in FIGS.  9 , 9   a , 9   b , each drawer has extensions  130 , 132  fitted with V-grooved rollers  22 . In  FIG. 4 , these V-grooved rollers are labeled  22 -D 1  and  22 -D 2  to differentiate them as to drawer #1 or drawer #2. The drawers engage a drawer constraint cable assembly  205  (indicated by the dashed line), and the counter weight  220  through the cable assembly  205  generates tension on V-grooved rollers  22 -D 1  and  22 -D 2 , as the force of the counter weight is conveyed over the auxiliary V-grooved rollers  22 , which act as pulleys or simply a guide to guide the cable  203 . In the schematic illustration, the Drawer  100 -D 1  is pulled open. Pulling the drawer open raises the counter weight from an unsupported start position by a length that cable  203  is extended when the drawer is opened. The drawer may be raised until it raises the weight to where it stops. Tension on the cable  203  prevents the second drawer from being opened, as the weight can no longer move up. The weight is guided up and down by the weight constraint cable assembly  205 . 
       FIG. 5  illustrates how the schematic shown in  FIG. 4  may be incorporated in the apparatus. Note that, in  FIG. 5 , the drawer actually needs to move open a distance that approaches or is greater than the height of the apparatus. The rollers  22   a , 22   b  at the front of a track  14  indicate the extent of possible movement. To lengthen horizontal movement of the drawer and shorten movement of the weight  220 , the drawer cable is looped multiple times around V-groove rollers from the rack cross bar  178  to the weight  220 . This configuration reduces the distance that the counter weight has to move with the resulting pulley-like system creating a mechanical advantage. In the current exemplary embodiment, the mechanical advantage is two fold. First, the length the drawer may move is twice as long as the distance the weight may move before encountering the stop. A second advantage is that the weight of the counter weight may be increased, thereby increasing the force needed to produce tip, which makes the system more safe. Once the counter weight  220  reaches the stop, another drawer cannot be opened without closing the open drawer. In an exemplary embodiment, the cable  203  or  205 ? may be a stainless steel 9×7 rope having 1500# break strength. 
     Referring to  FIG. 5   a , the counter weight  220  is positioned on the cable, with a wire rope grip fitting  224 , which locks the weight at a specific position on the cable and joins ends of the weight constraint cable (assembly)  205 . The wire rope grip fittings  224  also are used to tension the weight constraint cable  205 . The wire rope grip fittings  224  are separated by “A”, the width of the counter weight  220 . 
     Referring to  FIG. 5   b  and  FIG. 5   c , which are essentially mirror images of each other. The ends of the drawer constraint cable  203  is generally connected to a left side and a right side of the rack or base (not shown). In an exemplary embodiment, the connection is effected using swivel leveling mount fitting  226 , hex locknuts  228 , and wire rope grip fittings  224 . The drawer constraint cable  203  and the weight constraint cable  205  is routed through a plurality of V-grooved rollers. 
     The apparatus  10  is shown from the rear in  FIG. 10 . The drawer constraint cable  203  loops, in an exemplary embodiment, four times from the cross bar  176  to the weight  220 . All of the drawers are closed so the start position is around the sixth drawer. The sixth drawer portals are labeled  189 -right,  189 -left, accommodating extensions  130  and  132 . When a drawer is opened, the counter weight  220  moves through a vertical path defined by the weight constraint cable  205 . The upper most wire rope grip fittings  224  on the weight constraint cable  205  will eventually impact the V-grooved rollers  22  on the rack cross bar  178  as the counter weight  220  moves up. This point of impact is a stop position as there is no further vertical distance for the counter weight  220 . 
     Also shown in  FIG. 10  is a left v-grooved roller  22 -left on the top rack cross bar  178 , another left v-grooved roller  22 -left near a bottom of the left rear angle  168   a , a left wire rope grip fitting  224 . (see  FIG. 5   a ) The left wire rope grip fitting  224  locks a left end of the counter weight at a specific position on the cable and joins ends of the weight constraint cable so that the joined left weight constraint cable  204 -left is a left taut closed loop. The left taut closed loop circles the left v-grooved roller on the top rack cross bar and the left v-grooved roller near the bottom of the left rear angle, where the left end of the counter weight is guided by the left taut closed loop. A right v-grooved roller  22 -right on the top rack cross bar  187 , a right v-grooved roller  22 -right near a bottom of the right rear angle  168   b , and a right wire rope grip fitting  224 . (see  FIG. 5   a ). The right wire rope grip fitting  224  locks a right end of the counter weight at a specific position on the cable and joins ends of the weight constraint cable so that the joined right weight constraint cable  204 -right is a right taut closed loop. This right taut closed loop circles the right v-grooved roller on the top rack cross bar and the right v-grooved roller near the bottom of the right rear angle, where the right end of the counter weight is guided by the right taut closed loop. 
     The anti-tip safety mechanism  200  is a robust mechanical system, that can easily withstand, and anticipates, curing temperatures of about 150° F.-about 200° F. Furthermore, the anti-tip safety mechanism  200  works independent of the drawer of rollers, whether the rollers are turning or stationary. If there is failure in one of the drawers, the anti-tip safety mechanism  200  is unaffected. Based on this mechanism, it is relatively simple to take a drawer out-of-service, and install a replacement drawer. For instance, to replace drawer two, one would simply disengage the drawer&#39;s constraint cable  203  from the V-grooved rollers  22 -d 2  on extensions  130 ,  132 . One would slide in the replacement drawer and reengage the drawer constraint cable  203  onto the replacement drawer&#39;s V-grooved rollers  22 -d 2  on extensions  130 , 132 . The anti-tip safety mechanism  200  may be tested, by simply pulling out a drawer. If the mechanism is working properly, there will be some pulling tension on the drawer to draw the drawer back to the closed, stacked position. The tension does not increase as the drawer is pulled out further. However, the tension may dramatically increase when the counter weight reaches it stop position, which generally corresponds to more than one drawer being pulled out. 
     It is anticipated that the drawer configuration and the anti-tip safety mechanism  200  may be modified so that more than one drawer may be pulled out. For instance, the vertical rack  160  and anti-tip safety mechanism  200  may be configured to hold four drawers, and these racks may be stacked on each other, or stacked side-by-side. 
     In  FIG. 11 , the apparatus  10  is positioned inside and flush with an integral oven  50 . Cumulatively the face plates  140  function as a door to the oven  50 . The front angle top  174 , the left front angle  166   a , the right front angle  166   b  and the front plate skirt  176  serve as flashing. When the whole apparatus is rolled into place in the oven, the swivel mount fittings  226 -left,  226 -right mounted on left rear angle  168   a  and right rear angle  168   b  (also shown in  FIGS. 5   b  and  5   c ) hits a stop with hard point in the oven (not shown on any drawing). 
     The apparatus may be on a floor  500 , where the floor  500  may be in a temperature and humidity controlled room. If the room may attain sufficiently high temperature, then the room may be used as the oven, enabling greater production, where no integral oven  50  will be required. 
     It is to be understood that the foregoing description and specific exemplary embodiments are merely illustrative of the best mode of the invention and the principles thereof, and that various modifications and additions may be made to the invention by those skilled in the art, without departing from the spirit and scope of this invention, which is therefore understood to be limited only by the scope of the appended claims. 
     Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the embodiments of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.