Abstract:
A unitary spring system end cap packaging unit, for protecting a fragile article contained within a shipping carton, including a platform portion dimensioned to support at least a portion of a shock/vibration sensitive article, and a sidewall structure. The sidewall structure includes an inner wall with a distal edge joined to the platform portion, an outer wall and at least one spring system integrally joined to a proximal edge of the inner wall and an upper edge of the outer wall. The spring system spaces the inner wall from the outer wall. The spring system includes at least one flexible harmonic bellows forming a flexible ridge that has an arcuate shape along the length of the sidewall structure. The outer wall extends below the distal edge of the inner wall so that the platform portion is supported above the lower edge of the outer wall.

Description:
This is a continuation-in-part application of a copending design application 29/052,650, filed on Apr. 2, 1996, abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to packaging used for shipping articles, and more particularly to flexible plastic packaging units of unitary construction for supporting and protecting a shock or vibration sensitive article inside a shipping carton. 
     BACKGROUND OF THE INVENTION 
     Shock and/or vibration sensitive articles, such as computers, monitors, TV&#39;s, VCR&#39;s, radios, computer tape and disk drives, and other sensitive electronic equipment, require special packaging when shipped inside shipping cartons. Conventional carton packaging used to protect such articles includes paper, nuggets of expanded foam, preformed polystyrene foam or beads, etc. Ideally, the packaging absorbs and dissipates shocks and vibrations impinging the shipping carton to minimize the shocks and vibrations experienced by the fragile article. 
     More recently, manufacturers of shock/vibration sensitive articles have developed stringent shock dissipation requirements for packaging used to ship their products. For example, some manufacturers use &#34;drop test&#34; requirements, which dictate the maximum amount of g force that the article packaged inside a carton can experience when the carton is dropped from a certain height. The drop test requirements typically include several g force values, depending upon which carton side, edge, and/or corner lands on the drop surface. Therefore, the carton packaging needs to adequately dissipate shocks induced from many directions. 
     As shock dissipation requirements become more complex, so too must the carton packaging. The performance of the carton packaging design must not only satisfy the shock dissipation requirements, but ideally should also be easily adaptable to change the shock dissipation performance since shock dissipation requirements can change for any given article, or are different from article to article. 
     To complicate the problem of selecting appropriate carton packaging, many articles now require protection against vibration as well. Therefore, shipping carton packaging should not only absorb shock forces to meet the above mentioned drop test requirements, but must also sufficiently absorb vibrations typically experienced by shipping cartons in transit. 
     Conventional carton packaging materials have proved inadequate to meet the more stringent shock and vibration absorption requirements for modern articles of commerce. In order to satisfy such requirements, large volumes of conventional carton packaging is required around the article. Voluminous packaging materials are expensive and take up excessive warehouse space before use and trash/recycling space after use. Further, larger shipping cartons are necessitated by the voluminous carton packaging, which are more expensive to purchase and to ship. The shock/vibration dissipation performance of paper, nugget and bead packaging materials can depend in large part on how the user actually packages the particular article. If a particular conventional carton packaging is deemed to provide inadequate shock/vibration protection, there is no predictable way to modify such packaging material to meet such shock/vibration dissipation requirements, except for adding more packaging material and increasing the shipping carton size. 
     More recently, unitary packaging structures have been developed that are made of flexible polymeric materials to allow shocks to dissipate through flexing of the structure walls. Examples of such unitary structures can be found in U.S. Pat. Nos. 5,226,543, 5,385,232, and 5,515,976. However, these unitary packaging structures are typically designed to dissipate shocks primarily in one direction and/or fail to provide adequate shock/vibration protection under the more stringent performance specifications from fragile article manufacturers. Further, such unitary packaging structure designs are not easily adaptable to predictably change their shock/vibration dissipation performance to meet new and/or changing specifications. For example, if a drop test indicates there is insufficient shock dissipation in one direction, there is no easy modification that can be made to predictably change the shock dissipation performance in that direction without unpredictably affecting shock/vibration dissipation performance in other directions. 
     There is a need for carton packaging that predictably meets the most stringent shock/vibration dissipation requirements without necessitating large volumes of material and/or excessively large shipping cartons. Further, there is a need for such carton packaging to be easily modifiable to predictably meet a wide range of shock/vibration dissipation requirements, and changes to those requirements. Lastly, there is a need for such carton packaging to use minimal storage space before and after use, and to use minimal packaging material to reduce cost and shipping weight. 
     SUMMARY OF THE INVENTION 
     The present invention solves the aforementioned problems by providing a light, inexpensive unitary spring system end cap packaging structure that efficiently dissipates shocks and vibrations while using a minimal amount of carton space during use, and a minimal amount of storage space before and after use. The present invention has a design that is easily adapted to meet a wide range of the most stringent shock/vibration dissipation requirements without using voluminous amounts of material. 
     The unitary spring system end cap of the present invention includes a platform portion dimensioned to support at least a portion of a shock/vibration sensitive article, and a sidewall structure. The sidewall structure includes an inner wall having proximal and distal edges, where the distal edge is joined to the platform portion, an outer wall having upper and lower edges, and at least one spring system integrally joined to the proximal edge of the inner wall and the upper edge of the outer wall. The spring system spaces the inner wall from the outer wall. The spring system includes at least one flexible harmonic bellows forming a flexible ridge that has an arcuate shape along the length of the sidewall structure. The outer wall extends below the distal edge of the inner wall so that the platform portion is supported above the lower edge of the outer wall. 
     Other objects and features of the spring system end caps of the present invention will become apparent by a review of the specification, claims and appended figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a perspective view of the spring system end cap of the present invention. 
     FIG. 1B is an end view of the spring system end cap of the present invention. 
     FIG. 1C is a side view of the spring system end cap of the present invention. 
     FIG. 1D is a cross-sectional end view of the spring system end cap of the present invention illustrating the harmonic bellows in the sidewall structures. 
     FIG. 1E is a cross-sectional side view of the spring system end cap of the present invention illustrating the harmonic bellows in the sidewall structures. 
     FIG. 1F is a cross-sectional end view of a sidewall structure illustrating the radius of curvature of the top of the ridges of the harmonic bellows. 
     FIG. 2 is a perspective view of a shock sensitive article supported by a pair of spring system end caps within a shipping carton. 
     FIG. 3A is a cross-sectional end view of the spring system end cap of the present invention illustrating the compression/expansion of the harmonic bellows upon horizontal displacement of the platform. 
     FIG. 3B is a cross-sectional end view of the spring system end cap of the present invention illustrating the compression/expansion of the harmonic bellows upon vertical displacement of the platform. 
     FIG. 4A is a perspective view of a first alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4B is a perspective view of a second alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4C is a perspective view of a third alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4D is a perspective view of a fourth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4E is a perspective view of a fifth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4F is a perspective view of a sixth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4G is a cross-sectional end view of a seventh alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4H is a perspective view of an eighth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4I is a cross-sectional end view of a ninth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4J is a perspective view of a tenth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 4K is a cross-sectional end view of an eleventh alternate embodiment of the spring system end cap of the present invention. 
     FIG. 5A is a perspective view of a ninth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 5B is a perspective view of a tenth alternate embodiment of the spring system end cap of the present invention. 
     FIGS. 6A and 6B are perspective views of an eleventh alternate embodiment of the spring system end cap of the present invention. 
     FIGS. 6C and 6D are cross-sectional side views of the eleventh alternate embodiment of the spring system end cap of the present invention. 
     FIG. 7A is a perspective view of a twelfth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 7B is cross-sectional side view of the twelfth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 8A is a perspective view of a thirteenth alternate embodiment of the spring system end cap of the present invention. 
     FIG. 8B is cross-sectional side view of the thirteenth alternate embodiment of the spring system end cap of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is a multiple spring system end cap packaging structure of unitary construction for supporting and protecting a shock/vibration sensitive article inside a shipping carton by dissipating shocks and vibrations experienced by the carton using a plurality of spring systems. The spring system end caps are nestable for space efficient storage before and after use, utilize minimal carton space to dissipate such shocks and vibrations, are lightweight, and have a structural design that can be easily modified to predictably meet a wide range of shock/vibration dissipation requirements. 
     The preferred embodiment of the spring system end cap 2 of the present invention is illustrated in FIGS. 1A-1F, and includes a platform 4 supported by sidewall structures 6 and 8. 
     The sidewall structures 6/8 each include an inner wall 10 and outer wall 12 which are connected together by one or more spring systems 14. The lower edge 16 of the inner walls 10 joins with and supports platform 4. The outer walls 12 extend below platform 4 to define a cushion space 19 (shown in FIG. 1E) between the lower edge 18 of outer walls 12 and platform 4. Dimples 21 are formed protruding from inner walls 10 to create a friction fit between the article and the inner walls 10. Each spring system 14 includes one or more parallel arced harmonic bellows 20 extending along the length of each sidewall structure 6/8. Bellows 20 are each formed by two elastic plates 22 attached together at an angle α to form a ridge 24 with a cross-sectional radius of curvature r. Ridges 24 extend in, and have an arcuate shape in, the longitudinal (lengthwise) direction of sidewall structures 6/8 to form arcs 27. If a spring system 14 contains more than one harmonic bellows 20, the bellows 20 are formed side by side with the bottom edges of elastic plates 22 from adjacent .bellows 20 being joined together to form a channel 26 between the ridges 24. Channel 26 also extends in, and has an arcuate shape in, the longitudinal (lengthwise) direction of sidewall structures 6/8. If a sidewall structure 6/8 has more than one spring system 14, the ridges from the spring systems 14 are formed end to end resulting in a plurality of arcs 27 connected end to end along the length of that sidewall structure 6/8. 
     For each spring system 14, the innermost elastic plate 22 joins with the inner wall 10, and the outermost elastic plate 22 joins with the outer wall 12. The embodiment illustrated in FIGS. 1A-1F includes sidewall structures 6 having three spring systems 14 each with three harmonic bellows 20, and sidewall structures 8 having one spring system 14 with three harmonic bellows 20. 
     FIG. 2 illustrates the manner in which a pair of end caps 2 support a fragile article 28 inside a shipping carton 30. The end caps 2 support opposing ends of the article via the inner walls 10 and platform 4. The end caps 2 are supported inside the shipping carton by outer wall lower edges 18 and outer walls 12, which abut the inside surfaces of the shipping carton 30. The above described end caps 2 provide optimal deceleration of the article supported thereby when an external shock force is applied to the shipping carton, as described below. 
     Shock forces impinging the shipping carton and translated to each end cap 2 can be broken down into two horizontal components X and Y, and one vertical component Z, as illustrated in FIGS. 1A, 3A and 3B. The horizontal components of any shock force or vibration are dissipated by the sidewall structures 6/8 by inducing a stretching and compression of the harmonic bellows 20. FIG. 3A illustrates a Y component force and its effects on sidewall structures 6. A shock force in the direction of arrow A causes the platform 4 to displace in direction of arrow B, which causes the harmonic bellows 20 on the left of the platform 4 to compress together, and the bellows 20 on the right of the platform 4 to expand. During such bellows compression/expansion, the material that forms the ridges 24 and the channels 26 is stressed, thus absorbing the energy of the force. After the energy of the shock is absorbed by harmonic bellows 20, the bellows 20 on the left of the platform 4 resiliently expand and the bellows 20 on the right of platform 4 resiliently contract back to their natural uncompressed/ unexpanded form, thus restoring the platform 4 to its original position. A similar bellows compression/expansion occurs for platform displacements in the direction of arrow A, as well as in sidewall structures 8 for X component forces. Vibrations are also similarly absorbed by sidewall structures 6/8, but with only minimal platform displacement in the X and Y axes. 
     The vertical components of any shock force or vibration are dissipated by the both sidewall structures 6 and 8, as illustrated in FIG. 3B. A shock force in the direction of arrow C causes the platform 4 to displace in direction of arrow D, which in turn causes the harmonic bellows 20 in both sidewall structures 6/8 to rock inward and expand toward platform 4 while outer wall 12 deflects inwardly. The material that forms the ridges 24 and the channels 26 is stressed, thus absorbing the energy of the force. After the energy of the shock is absorbed by harmonic bellows 20, the bellows 20 resiliently contract back to their natural unexpanded form, thus restoring the platform 4 to its original position. The corners of the end caps 2 are formed so that when all the bellows 20 rock inwardly, the bellows 20 on either side of each corner do not interfere with each other during the downward deflection of the platform 4. A similar bellows compression/expansion occurs for platform displacements in the direction of arrow C (to the extent that the article can pull up on inner walls 10). Vibrations are also similarly absorbed by sidewall structures 6/8, but with only minimal platform displacement in the Z axes. 
     It should be noted that spring systems 14 in the sidewall structures 6 can be made to operate more independently from spring systems 14 in the sidewall structures 8 by making the bellows thicknesses on either side of the corners equal. This will ensure the least amount of operational interference across the end cap corners. 
     Each bellows 20 of each spring system 14 operates independently during a shock or vibration. Therefore, if a shock force has both horizontal and vertical (X, Y, and Z) components, then each spring system 14 works independently to absorb the energy of that shock force. 
     The arcuate shape of the bellows 20 provides superior strength along the length of each sidewall structure 6/8, and prevents the bellows 20 from buckling during large deflections of the platform 4. 
     The maximum g force and vibration experienced by the article is dictated by the overall stiffness of the end cap 2 in the direction of the force/vibration. If the spring systems 14 are too soft, then the bellows 20 will completely collapse together so the platform will hit the outer wall 12, and/or the platform 4 will be deflected beyond outer wall lower edge 18 to contact the side of the shipping carton, either of which will increase the maximum force experienced by the article. If the spring systems 14 are too stiff, then the bellows 20 will not sufficiently compress and expand to absorb and dissipate a sufficient amount energy from the shock or vibration, which will also increase the maximum force/vibration experienced by the article. Therefore, each spring system 14 needs to have a certain stiffness, so the overall stiffness of the end cap 2 in any given direction will result in the maximum amount of shock/vibration absorption and dissipation, without the platform contacting the outer walls 12 or the shipping carton. 
     The overall end cap stiffness in any given direction is a function of a number of end cap design parameters. Generally, overall end cap stiffness is increased by increasing, either individually or in combination, any of the following end cap design parameters: the number of spring systems 14 in each sidewall structure 6/8 (i.e. the number of arcs 27), the radius of curvature of the spring system arcs 27, the number of bellows 20 in each spring system 14, the ridge angles α between the elastic plates 22 of the various bellows 20, the cross-sectional radius of curvature r of the ridge, the length of the elastic plates 22, and the flexibility/thickness of the material used to form the end cap 2. Also, decreasing the area of the platform 4 can increase stiffness for vertical platform deflections because the inner walls 10 better engage the article to resist the bellows 20 from rotating inwardly during platform deflection. In addition, increasing the cushion space 19 will provide additional distance for platform displacement, thus preventing the platform 4 from contacting the sides of the shipping carton. It should be noted that these end cap design parameters can differ from sidewall structure to sidewall structure, spring system to spring system, and even from bellows to bellows within the same spring system. 
     Each of the above design parameters can be individually adjusted to provide the desired end cap stiffness in any given direction, and at any location in end cap 2. Therefore, if a particular end cap design satisfies most of the shock/vibration dissipation requirements, it is easy to predict what end cap design parameters need adjusting to achieve those remaining requirements not yet satisfied. Further, the end cap design can be customized to provide different stiffness support for different portions of the article. For example, if an article is heavier at one end of the platform 4 than the other, then the spring systems 14 near the heavier end can be designed to accommodate the extra weight (i.e. by changing the ridge angles α on one or more the bellows 20 closest to that heavy end, or by adding an extra bellows 20 to those spring systems 14 supporting the heavy end, etc.). Each spring system 14 can have a unique stiffness, and each bellows 20 within that spring system 14 can embody different end cap design parameter values to achieve that unique stiffness. Because these design parameters operate relatively independently and predictably upon the stiffness of the end cap, these design parameters can be changed individually to fine tune the performance of the end cap to meet any given shock/vibration absorption requirement. 
     The preferred material used to make end cap 2 is high density polyethylene because it is has good tensile and tear properties at low temperatures as well as being recyclable. Other materials that can be used to make the end cap 2 include: polyvinyl chloride, polypropelene, low density polyethylene, PETG, PET, styrene, and many other polymeric materials. 
     The spring system end caps of the present invention are fully nestable for efficient stackability to minimize storage space before and after use. Further, because of the resiliency of the end cap 2 material and spring system design, these end caps can be re-used repeatedly. The bellows design of the end caps results in minimal space requirements inside the carton for maximum cushion effect, thus reducing the carton size needed to safely ship any given article. End caps 2 are also lightweight to minimize shipment costs both of the end caps before use, as well as during shipment of the articles utilizing the end caps. 
     FIGS. 4A to 4H illustrate various embodiments of the present invention, utilizing different combinations of some of end cap design parameter values discussed above. For example, FIG. 4A illustrates an end cap 2 with one spring system 14 per sidewall structure 6/8, and one bellows 20 per spring system 14. FIG. 4B illustrates an end cap 2 with a plurality of spring systems 14 per sidewall structure 6/8, and one bellows 20 per spring system 14. FIG. 4C illustrates an end cap 2 with two spring systems 14 per sidewall structure 6 and one spring system 14 per sidewall structure 8, and a plurality of bellows 20 per spring system 14. FIG. 4D illustrates an end cap 2 where the sidewall structures 8 have more bellows 20 but fewer spring systems 14 than the sidewall structures 6. FIG. 4E illustrates an end cap 2 with one sidewall structure 8 having more bellows 20 than the other sidewall structure 8. FIG. 4F illustrates an end cap 2 with one sidewall structure 6 having more spring systems 14 than the other sidewall structure 6. FIG. 4G illustrates an end cap 2 with one sidewall structure 6 having different ridge angles α, plate lengths, and number of harmonic bellows 20 than the other sidewall structure 6. FIG. 4H illustrates an end cap 2 with sidewall structures 6 containing spring systems 14 having arcs 27 of different radius&#39; of curvature. FIG. 4I illustrates an end cap 2 with a sidewall structure 6 having one ridge (with a cross-sectional radius of curvature r 1 ) that is stiffer than an adjacent ridge (with a cross-sectional radius of curvature r 2 ) because r 1  &gt;r 2 . FIG. 4J illustrates an end cap 2 with flat ridges (no arcs) but a plurality of harmonic bellows 20 in each sidewall structure 6/8. FIG. 4K illustrates ridges 24 with a flat top portion 32. 
     As made evident from FIGS. 4A-4K, the present invention embodies spring system end cap designs that include any combination of end cap design parameter values. 
     It should be noted that the present invention is not limited to rectangular (or square) platforms 4, but also includes platforms of other shapes as well, such as triangular (as illustrated in FIG. 5A), circular (as illustrated in FIG. 5B), oval, etc. The platform dimensions and shape can be changed to best fit the shape of the article while providing the desired shock/vibration dissipation. Further, end caps of different platform shapes and end cap design parameter values can be used to support different portions of the same article. 
     FIGS. 6A and 6B illustrate another embodiment of the end cap of the present invention. Complimentary end caps 34 and 36 are ideal for supporting a small article therebetween. End cap 34 has sidewall structures 38 that extend above platform 4 and sidewall structures 40 that are formed below platform 4. Likewise, end cap 36 has sidewall structures 42 that extend above platform 4 and sidewall structures 44 that are formed below platform 4. When a relatively small article is supported between platforms 4 of end caps 34/36, sidewall structures 38 are positioned opposite sidewall structures 44, and sidewall structures 40 are positioned opposite sidewall structures 42. This configuration allows the platforms 4 of end caps 34/36 to be positioned closer together without the sidewall structures 38 and 40 interfering with sidewall structures 42 and 44 respectively. 
     FIGS. 7A and 7B illustrate an embodiment of the end cap of the present invention having an open ended platform 4 for holding just a portion of an article. Platform 4 terminates on two sides with adjacent sidewall structures 46 that extend above platform 4, and with adjacent sidewall structures 48 that are formed below platform 4. This end cap embodiment is ideal for supporting a portion of the article, such as one corner, that extends beyond the platform 4. 
     FIGS. 8A and 8B illustrate an embodiment of the end cap of the present invention having sidewall structures 50 on all sides of the platform that are formed entirely below the platform 4. This embodiment is ideal for supporting a flat area portion of an article that is much larger than the area of the platform 4. The article can extend beyond the platform 4 without interfering with the sidewall structures 50. 
     It is to be understood that the present invention is not limited to the embodiments described above and illustrated herein, but encompasses any and all variations falling within the scope of the appended claims. For example, the end caps described herein can be used to ship any kind of article, whether it is fragile or not. Further, the name &#34;end cap&#34; does necessarily mean the end caps of the present invention hold the &#34;ends&#34; of the article.