Abstract:
A method of constructing footwear includes providing a mold having an inner cavity, injecting an expandable material into the inner cavity, removing the expandable material from the inner cavity such that the material expands to form a footwear-shaped shell having an inner cavity and at least one recessed area offset from an inner surface of the shell, and inserting a chassis within the inner cavity of the expanded shell. The chassis has one or more components adapted to protect a user&#39;s foot from injury. The insertion of the chassis within the shell permanently affixes the one or more components within the at least one recessed area of the shell.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of U.S. application Ser. No. 14/208,037, filed on Mar. 13, 2014, which claims the benefit of U.S. Provisional Patent Application No. 61/779,054, filed Mar. 13, 2013, the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention(s) relates, in general, to safety footwear for use in harsh conditions, such as in a variety of agricultural, food processing, energy exploration, industrial, and/or hazmat environments. 
         [0003]    Footwear developed to withstand harsh conditions, such as conditions in which the wearer is subject to constant exposure to water, chemicals, hot or cold temperatures, or natural corrosives, must be constructed to withstand those conditions while maintaining comfort for the wearer. A common area in which certain footwear is subject to one or more of the foregoing environments is, for example, in the oil drilling industry. Currently, drilling platforms may be in an environment in which the ground or working area is constantly muddy, laced with chemicals or corrosive additives used during drilling, or both. Fracking (or hydraulic fracturing) is a practice in the drilling industry in which the aforementioned conditions are commonly present. In such harsh working conditions, footwear often degrades or deteriorates entirely within a short period of time, subjecting the user to unnecessary costs in purchasing footwear at short intervals. For example, certain footwear available in the current market may only last for a period of two (2) or three (3) weeks in such conditions. 
         [0004]    It is also the case that, with working conditions such as those encountered in the drilling industry, safety is paramount. Indeed, certain standards (e.g., those prescribed by the American Society for Testing and Materials (ASTM), CSA, or EN-ISO) require that footwear used within these industries meet numerous safety requirements. As an example, any safety components introduced into the footwear must be integral to the construction of and non-removable from the footwear; or in other words, the user cannot remove the safety components once the footwear is purchased. Other safety requirements are also present, of course. 
         [0005]    Further, solid elastomer and/or rubber footwear currently used in the above-noted environments tend to be heavy; and, since footwear weight and flexibility are factors that impact human ambulation efficiencies and/or the amount of energy expended during normal work shifts, these considerations may be significant. For example, heavy and/or non-flexible footwear may increase worker fatigue as compared to if lighter and/or more flexible footwear was used. 
         [0006]    Particular methods of manufacturing footwear are also known in the industry, one of those being a method in which expandable polymeric materials (e.g., polyolefin elastomers (PE), ethylene-vinyl acetate (EVA), or other such materials) are used. In short, expandable polymeric materials may be placed into an injection mold and formed into various footwear-type components. However, to date, incorporating such expanding footwear with industry and government regulated safety footwear performance features, as outlined in recognized Occupational Standards Bodies (ASTM F2413 and CSA Z195, for example), has not been possible. 
         [0007]    Given the foregoing, there exists a need for lightweight footwear that can withstand harsh environments while providing ample safety for the user in those environments. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    Aspects of the present invention(s) provide footwear that can withstand harsh environments while providing ample safety for the user in those environments. 
         [0009]    As an example, a first aspect of the invention(s) includes a footwear system comprising a shell having an inner cavity and at least one recessed area offset from an inner surface of the shell, and a chassis having one or more components adapted to protect a user&#39;s foot from injury, the chassis being insertable into the inner cavity of the shell, such that the one or more components of the chassis are permanently affixed within the at least one recessed area of the shell. In variants of this aspect, each recessed area also includes a set of stop surfaces arranged at an angle to the inner surface of the shell, and each component includes corresponding stop surfaces adapted to engage with the stop surfaces of the shell to retain the component within the recessed area. In some cases, the shell may also be composed of a corrosive-resistant material, or a material selected from the group consisting of a polyolefin elastomer, ethyl vinyl acetate, an expandable polymer, or a co-polymerized material suitable for cross-link foaming in a post-injection expandable foaming process. Further, the chassis may include a toe cap composed of rigid material, a heel counter, an insole board engaged to the top cap and heel counter, and/or a metatarsal guard. 
         [0010]    A second aspect of the invention(s) is a method of constructing footwear comprising the steps of: (1) providing a mold having an inner cavity; (2) injecting an expandable material into the inner cavity; (3) removing the expandable material from the inner cavity, such that the material expands to form a footwear-shaped shell, the shell having an inner cavity and at least one recessed area offset from an inner surface of the shell; and (4) inserting a chassis within the inner cavity of the expanded shell, the chassis having one or more components adapted to protect a user&#39;s foot from injury, wherein insertion of the chassis within the shell permanently affixes the one or more components within the at least one recessed area of the shell. In embodiments of this aspect, inserting the chassis within the inner cavity of the shell comprises positioning a stop surface of the one or more components so that it interferes with a stop surface arranged adjacent the at least one recessed area. The shell may also comprise a material impermeable to water or other solutions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    A more complete appreciation of the subject matter of the present invention(s) and of the various advantages thereof can be realized by reference to the following detailed description in which reference is made to the accompanying drawings in which: 
           [0012]      FIGS. 1A-C  are cross-sectional views of a footwear system, according to one embodiment of the present invention(s). 
           [0013]      FIGS. 2A-C  are cross-sectional views of a variant of the footwear system of  FIGS. 1A-C . 
           [0014]      FIGS. 3A-C  are cross-sectional views of yet another variant of the footwear system of  FIGS. 1A-2C . 
           [0015]      FIGS. 4A-C  are cross-sectional views of the shell of yet another variant of the footwear system of  FIGS. 1A-3C . 
           [0016]      FIGS. 5A-B  are cross-sectional views of the shell and chassis of still yet another variant of the footwear system of  FIGS. 1A-4C . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    In describing certain features of the present invention(s), specific terminology will be used for the sake of clarity. However, the invention(s) is not intended to be limited to any specific terms used herein, and it is to be understood that each specific term includes all technical equivalents, which operate in a similar manner to accomplish a similar purpose. 
         [0018]    Referring to  FIGS. 1A-C , such depicts footwear  10  being composed of a number of components, namely an outer shell  20  and an assembled chassis  50  inserted and secured into the shell  20 .  FIGS. 1A-B  depict, in detail, outer shell  20  and chassis  50 , the latter of which may itself include a number of components, particularly: (1) a safety toe box or cap  52 ; (2) a puncture resistant insole board  66 ; (3) a shock diffusion plate  76 ; and (4) a heel counter  86 . Other components may also form part of chassis  50 , as set forth in additional embodiments discussed below. Nonetheless, in each embodiment, chassis  50  may be inserted into shell  20  and secured thereto so that a user may not remove chassis  50 . In this manner, footwear  10  may provide safety for a user in certain dangerous or harsh environments (e.g., in the drilling industry). 
         [0019]    As shown in  FIG. 1B , in one embodiment chassis  50  may include a toe cap  52  having inner and outer surfaces  54 ,  56 , the toe cap  52  being arrangeable over a user&#39;s forefoot region to protect the user&#39;s toes from injury due to an impact or other event. Indeed, toe cap  52  may be formed of rigid material, such as a hard polymer, metal, or other material, and include a section  58  overlying a user&#39;s toes. Toe cap  52  may also include a lower protruding section  62 , in this embodiment, that is connected at its inner surface  54  to insole board  66 , as discussed below. Lastly, toe cap  52  may include stop surfaces  60 ,  64  for engaging with certain stop surfaces in outer shell  20 . 
         [0020]    Referring still to  FIG. 1B , chassis  50  may include, as alluded to above, an insole board  66  that in some cases is puncture resistant. Insole board  66  may have inner and outer surfaces  68 ,  70  and ends  72 ,  74 , which are connected at their outer surface  70  to toe cap  52  and heel counter  86 , respectively. 
         [0021]    Heel counter  86  may likewise include inner and outer surfaces  88 ,  90 , and a lower protruding section  92  for engaging with insole board  66 . Heel counter  86  may also provide rigidity to chassis  50  at that section so that, when a user inserts his/her foot into footwear  10 , stability is provided in the heel region. As with toe cap  52 , heel counter  86  also has stop surfaces  94 ,  96  for engaging with corresponding stop surfaces in shell  20 . 
         [0022]    Chassis  50  further includes a shock diffusion plate  76  in this embodiment ( FIG. 1B ) that overlies insole board  66 . Shock diffusion plate  76  may, if desired, take the form of tuck board-type material (e.g., standard footwear cellulose, or entangled non-woven or woven-type materials, with or without stiffening agents) that is rigid in nature so as to absorb any shock or force impacted on insole board  66 . In an alternate embodiment, shock diffusion plate  76  may be any of the shock diffusion plates shown and described in U.S. Pat. No. 6,205,683 to Clark et al., owned by The Timberland Company, the disclosure of which is hereby incorporated herein by reference. Together, the aforementioned components create one embodiment of chassis  50  that is insertable into shell  20  in the manner discussed below. 
         [0023]    Shell  20 , as shown in  FIG. 1A , may include several aspects common to typical footwear, such as an outsole  22 , an upper  24 , and heel  26 , forefoot  28 , and instep  30  sections. In one embodiment, shell  20  is also impermeable to certain substances, such as water, mud, or other solutions or corrosives. Shell  20  may also include an inner cavity  21  shaped to accommodate a user&#39;s foot, which has various recessed areas or cutouts  31 ,  32  for receiving a portion of chassis  50 . In one embodiment, recessed areas  31 ,  32  may be bounded by stop surfaces  34  on either side to receive and securely hold a portion of chassis  50  within the relevant recessed area  31 ,  32 . In a particular embodiment, as shown in  FIG. 1A , shell  20  may include two (2) recessed areas  31 ,  32  for accommodating toe cap  52  and heel counter  86  therein, although more or less recessed areas may be employed. 
         [0024]    As shown in  FIG. 1C , to construct footwear  10 , chassis  50  may be inserted into shell  20 , such that toe cap  52  is situated in recessed area  31  of shell  20 , and heel counter  86  is likewise situated in separate recessed area  32 . Once so inserted into shell  20 , stop surface  64  of toe cap  52  and stop surfaces  94 ,  96  of heel counter  86  may contact respective stop surfaces  34  surrounding recessed areas  31 ,  32  of shell  20  so that toe cap  52 , heel counter  86 , and thus chassis  50  are securely retained within shell  20 . While not shown in  FIG. 1C , in one embodiment stop surface  60  may also contact an alternate stop surface  34  within shell  20  (e.g., recessed area  31  may be made to be smaller so that a stop surface  34  of recessed area  31  contacts stop surface  60  to retain toe cap  52  within shell  20 ). 
         [0025]    To ensure that chassis  50  is not removable from shell  20 , in compliance with safety standards, it is possible to cement or otherwise adhere certain portions of chassis  50  to shell  20  (e.g., the whole of chassis  50  or, for example, only insole board  66  may be cemented or adhered to shell  20 ). Alternatively, it is contemplated that chassis  50  may snap into place within shell  20  so that chassis  50  is non-removable therefrom. In other words, during insertion of chassis  50  within inner cavity  21  of shell  20 , a user may press-fit toe cap  52  and heel counter  86  within recessed areas  31 ,  32 , such that chassis  50  is retained within shell  20  due to interference between stop surfaces  34 ,  64 ,  94 ,  96  (and in an alternate embodiment, stop surface  60 ). This may be achieved by manufacturing chassis  50  so that a dimensional interference is created between chassis  50  and shell  20  (e.g., certain portions of chassis  50 , such as toe cap  52  and heel counter  86 , may be arranged so that such portions can be press-fit into recessed areas  31 ,  32 ). As an example, stop surface  64  on toe cap  52  and stop surface  94  on heel counter  86  may be separated by a first distance, which is slightly less than a second distance separating stop surfaces  34  of recessed areas  31 ,  32  that contact stop surfaces  64 ,  94 . In this manner, once chassis  50  is inserted into shell  20 , stop surfaces  64 ,  94  may be forced past stop surfaces  34  of recessed areas  31 ,  32  to securely lock chassis  50  in place (e.g., via a dimensional interference). 
         [0026]    With chassis  50  inserted into shell  20 , as discussed above, toe cap  52  may adequately ensure that a user&#39;s toes are not injured due to an impact event (e.g., an object striking the toes), insole board  66  may provide puncture resistance, shock diffusion plate  76  may diminish or absorb any impact forces borne on the foot, and heel counter  86  may provide support for a user&#39;s heel during use. In addition, shell  20  may provide corrosion resistance and/or impermeability with respect to several substances (e.g., water, mud, corrosive liquids/chemicals, etc.) 
         [0027]    It is also contemplated that shell  20  (or any of the alternate shells described below) may be manufactured from particular corrosion-resistant materials, such as cross-linking post-injection expansion polyolefin elastomers. As an example, shell  20  may be manufactured through an injection-molding process that uses expandable polymers, such as EVA. In short, during such a process, a mold may be injected with EVA or EVA-type material to form shell  20 , and once appropriately cured, shell  20  may be released from the mold into the configuration shown in  FIG. 1A  (or any of the remaining figures depicting alternate embodiments of shell  20 ). The curing process may be controlled by subjecting shell  20  to engineered expansion (e.g., controlling ambient conditions, temperature, time, etc.) 
         [0028]    Stated differently, as injected into the mold, shell  20  may be relatively smaller than in its final configuration ( FIG. 1A ), and once released, shell  20  may expand to its final state. Then, after shell  20  has been released from the mold and allowed to expand to its final form ( FIG. 1A , or the other figures depicting the shell), chassis  50  may be inserted into and secured within shell  20  in the manner discussed previously. As such, through this process, it is possible to manufacture footwear  10  meeting the various requirements mandated in certain industries (e.g., the non-removability of safety components), such as in the drilling industry. In addition, footwear  10  utilizing the aforementioned features not only provides comfort for the user, along with safety, but also lasts far longer in corrosive environments than other existing arrangements. As such, within these industries, the consumer is not forced to purchase footwear  10  at exceedingly short intervals of time. 
         [0029]    An alternate version of footwear  10  is shown in  FIGS. 2A-C , in which chassis  50  and shell  20  are slightly modified. Here, like numerals refer to like elements, except where indicated (although reference numerals are in the 100-series instead of, as an example, the 10-series). 
         [0030]    Referring to  FIG. 2B , chassis  150  is generally the same as chassis  50 , except that chassis  150  includes a metatarsal guard  198 . Metatarsal guard  198  may have respective inner and outer surfaces  200 ,  202  and an end  206  that connects with toe cap  152 . In one embodiment, end  206  includes an L-shaped groove that connects with toe cap  152  so that both components are an integral unit forming part of chassis  150 . In some cases, metatarsal guard  198  may take the form of any of the metatarsal guards shown or otherwise described in U.S. patent application Ser. No. 13/648,839 (the &#39;839 Application), entitled “Protection Devices for Use in Shoes or Other Products,” the disclosure of which is hereby incorporated by reference herein. As taught in the &#39;839 Application, a metatarsal guard, such as metatarsal guard  198 , may be positioned over the metatarsal region of a user&#39;s foot to protect the same from injury. In particular, as shown in  FIG. 2C , metatarsal guard  198  may be positioned within instep  130  of shell  120  to overlie the metatarsal region of the user&#39;s foot. 
         [0031]      FIG. 2A  depicts shell  120  as having a recessed area  131  that extends from a portion of a floor  136  of shell  120  adjacent forefoot end  128  to a section of shell  120  adjacent instep  130 . Thus, in this embodiment, recessed area  131  may be designed specifically to accommodate metatarsal guard  198  and toe cap  152 , in combination. Recessed area  132  may be of the same configuration and shape as recessed area  32  of the previous embodiment of shell  20  so that heel counter  186  may be received within such recessed area  132 . Metatarsal guard  198  may also include a stop surface  204  ( FIG. 2B ) that engages with stop surface  134  bordering recessed area  131  upon insertion of chassis  150  within shell  120 . 
         [0032]    Much like the previous embodiment, to assemble footwear  110 , chassis  150  may be inserted within inner cavity  121  of shell  120  so that heel counter  186  is received within recessed area  132 , and metatarsal guard  198  and toe cap  152  are received within recessed area  131 . In particular, stop surfaces  194 ,  196  of heel counter  186  may engage with stop surfaces  134  of recessed area  132  to secure heel counter  186  within recessed area  132 , and stop surface  164  of toe cap  152  and stop surface  204  of metatarsal guard  198  may engage with stop surfaces  134  of recessed area  131  to secure toe cap  152  and metatarsal guard  198  within recessed area  131 . In one embodiment, the aforementioned components of chassis  150  (e.g., heel counter  186 , toe cap  152 , and metatarsal guard  198 ) may also be cemented or adhered within recessed areas  131 ,  132  so that chassis  150  may be non-removable from shell  120 . Alternatively, it is contemplated that chassis  150  may simply snap into place within recessed areas  131 ,  132 , such that chassis  150  is not removable from shell  120 , as detailed more fully above. Indeed, as an example, a distance between stop surface  164  of toe cap  152  and stop surface  204  of metatarsal guard  198  may be greater than a distance between stop surfaces  134  of recessed area  131 , such that toe cap  152  and metatarsal guard  198  may be press-fit into recessed area  131 . The same may be true for heel counter  186  and recessed area  132 , in one embodiment. 
         [0033]    Referring to  FIGS. 3A-C , an alternate embodiment of footwear  10 ,  110 , namely footwear  310 , is shown. As with above, like numerals refer to like elements in this embodiment, although in the 300-series instead of, as an example, the 10-series. 
         [0034]    As shown in  FIG. 3B , chassis  350  is generally the same as chassis  50  ( FIGS. 1A-C ), except that chassis  350  may include an insole  410  that is specifically configured to be puncture resistant (e.g., via being composed of rigid material(s), such as metal, hard plastics or composites, etc.) Thus, although insole board  366  may have puncture-resistant characteristics as well, insole  410  may provide yet additional puncture resistance to chassis  350 . Referring to  FIG. 3B , insole  410  may have inner and outer surfaces  412 ,  414  and respective toe and heel ends  416 ,  418 , the outer surface  414  of such ends  416 ,  418  being bonded, respectively, to lower protruding section  362  of toe cap  352  and lower protruding section  392  of heel counter  386 . As such, insole  410  may overly the inner surfaces  354 ,  388  of lower protruding sections  362 ,  392  of toe cap  352  and heel counter  386 , respectively. 
         [0035]    Referring now to  FIG. 3A , shell  320  in this embodiment may be generally identical to the previous shells  20 ,  120  so as to accommodate chassis  350 . Thus, the assembly of footwear  310 , as shown in  FIG. 3C , may proceed substantially as discussed above with respect to footwear  10  of  FIGS. 1A-C  (with the addition of added puncture resistance via insole  410 ). As such, chassis  350  may be non-removable from shell  320 , as in previous embodiments, so that footwear  310  satisfies certain safety requirements of various recognized regulatory bodies. 
         [0036]    A further variant of footwear  10 ,  110 ,  310  may be provided, the shell  520  of which is shown in  FIGS. 4A-C . In this embodiment, as shown in  FIG. 4A , the footwear shell  520  may include an opening  538 . Opening  538  may be shaped to accommodate an outsole  522  ( FIG. 4B ) that is applied to shell  520  after manufacture thereof. Thus, opening  538  may be specifically configured to accommodate outsole  522 . 
         [0037]    For example, as shown in  FIG. 4B , outsole  522  may include a set of flanges  540 ,  542  and stop surfaces  544 ,  546  adjacent such flanges  540 ,  542 ; and, to fully construct shell  520 , outsole  522  may be inserted through opening  538 , such that flanges  540 ,  542  engage corresponding flanges  547 ,  548  of shell  520  ( FIG. 4A ) and stop surfaces  544 ,  546  engage respective stop surfaces  543 ,  545  formed adjacent flanges  547 ,  548  of shell  520 . The engagement between shell  520  and outsole  522  is shown in detail in  FIG. 4C . Thus, outsole  522  may be securely retained within shell  520  post-manufacture of shell  520 . Indeed, in one embodiment, outsole  522  is cemented to shell  520 , or adhered via an adhesive, chemical bonding, etc. 
         [0038]    Once adhered to shell  520 , outsole  522  may serve to create the same configuration as the previously-described shells  20 ,  120 ,  320 . Indeed, referring to  FIG. 4C , a portion of outsole  522  adjacent flange  540  may create a stop surface  534  forming part of recessed area  531 , and a portion of stop surface  546  of outsole  522  may act as a stop surface  534  for recessed area  532 , as shown. As such, once outsole  522  is attached to shell  520 , any of the aforementioned chassis  50 ,  150 ,  350  may be inserted into and secured within shell  520  in the manner described previously. In other embodiments, it is also contemplated that the size of opening  538  and the configuration of outsole  522  may be modified, if desired. 
         [0039]    Yet an additional variant of footwear is shown in  FIGS. 5A-B . In this variant, as with the others, like reference numerals refer to like elements unless otherwise indicated (although in the 600-series instead of, as an example, the 10-series). 
         [0040]    Referring to  FIG. 5A , an alternate shell  620  is shown. Shell  620  may be made of any of the materials and according to any of the processes as set forth above for shells  20 ,  120 ,  320 ,  520 . Shell  620  includes an internal cavity  621 , an upper  624 , an outsole  622 , and heel  626 , forefoot  628 , and instep  630  sections, as with shells  20 ,  120 ,  320 ,  520 . Shell  620  differs from shells  20 ,  120 ,  320 ,  520 , however, in that it has a different arrangement for engaging with its corresponding chassis  650 , shown in  FIG. 5B . Indeed, shell  620  includes a set of recesses  606 ,  607  for engaging with certain sections of chassis  650  (described in more detail below) to retain chassis  650  within shell  620 . Recesses  606 ,  607 , in a preferred embodiment, extend substantially entirely or entirely around the perimeter of shell  620 , as shown in  FIGS. 5A-B , although it is contemplated that recesses  606 ,  607  may alternatively be formed along only certain sections of the perimeter of shell  620  and not along other sections. In one embodiment, recess  606  may be stepped to engage with a correspondingly-shaped section of chassis  650 . 
         [0041]    Chassis  650  is shown in  FIG. 5B  (and represented in outline in  FIG. 5A ). Chassis  650  includes a chassis body  601  and, in some cases, an optional puncture device  605  overlying a section of chassis body  601 . Puncture device  605  may protect a user&#39;s foot from damage due to a sharp object puncturing through chassis body  601 , and thus, puncture device  605  is constructed of a rigid material adapted to block the object from puncturing through device  605  and injuring the user&#39;s foot. Chassis  650  also includes an optional safety toe  652  (not shown). Although safety toe  652  is not actually shown in the figures, it is represented by a cavity in the area of chassis  650  where safety toe  652  would be located. In one embodiment, safety toe  652  may be press-fit, adhered, or otherwise secured within that cavity of chassis  650 , if desired, so that chassis  650  includes a safety toe  652  for protection. Safety toe  652 , as with the previous toe caps  52 ,  152 ,  352 , may be formed of rigid material, such as a hard polymer, metal, or other material, and include a section overlying a user&#39;s toes to protect the toes from injury (e.g., due to a heavy object falling on the user&#39;s toe area). 
         [0042]    In one embodiment, chassis body  601  also includes specific geometries for engaging with shell  620 . For instance, chassis body  601  includes a set of flanges  602  for engaging with recesses  606 ,  607  in shell  620 , and a set of projections  603  for receiving optional puncture device  605  and/or contacting a section of recess  606  (e.g., in the case of the right-side projection  603  in  FIG. 5B ). Flanges  602  may be formed entirely or substantially entirely around the perimeter of chassis  650 , as shown in  FIGS. 5A-B , so that, once engaged, chassis  650  is not removable from shell  620  (e.g., during ordinary use by the user). In alternate embodiments, flanges  602  are formed only along certain sections of the perimeter of chassis  650 , but not along other sections. Chassis body  601  also includes a stop surface/end  604  for engaging with a separate stop surface  634  of shell  620 . 
         [0043]    To insert chassis  650  within shell  620  so that the combined unit is usable as footwear, shell  620  may first be produced according to the methods discussed above and allowed to expand to its final state (e.g., by using expandable EVA materials inserted into a mold). Then, chassis  650  may be inserted into cavity  621  of shell  620 , such that its flanges  602  are arranged within recesses  606 ,  607 , as shown in outline in  FIG. 5A . This acts to at least partially retain chassis  650  within shell  620 , such that chassis  650  cannot be removed by a user. In other words, since flanges  602  are engaged with recesses  606 ,  607  about substantially or the entire perimeter of chassis  650  and shell  620 , as shown in outline in  FIG. 5A , chassis  650  is securely retained within shell  620 . 
         [0044]    During insertion of chassis  650  into shell  620 , stop/end surface  604  of chassis  650  may also come to rest on stop surface  634  of shell  620  to assist in securing chassis  650  relative to shell  620 . In one embodiment, a step is also formed in chassis body  601  and shell  620  adjacent instep region  630  for even further enhanced engagement between chassis  650  and shell  620  at that area. With chassis  650  secured in shell  620 , for example through press-fitting, adhering, cementing, or otherwise securing chassis  650  into shell  620 , as described in more detail with reference to the previous embodiments, the user may utilize the footwear of this embodiment in applicable industrial or other environments and obtain adequate protection. 
         [0045]    In the devices depicted in the figures, particular structures are shown that are adapted for use in footwear, such devices serving to protect the foot of a user and provide compliance with certain safety standards. The use of alternative structures for such purposes, including structures having different lengths, shapes, and configurations is also contemplated. As an example, while the disclosed footwear is described above in connection with use in the drilling industry, such footwear is equally usable in other industries in which corrosive environments and/or safety hazards are encountered. For instance, the footwear may be equally usable in the context of the hazmat, food processing, environmental clean-up, or other such industries. Put simply, the footwear has applicability in any area in which the working environment includes the presence of corrosive materials and/or safety dangers. 
         [0046]    As another example, it is contemplated that stop surfaces  34 ,  134 ,  334 ,  534 ,  634  of respective shells  20 ,  120 ,  320 ,  520 ,  620  may be angled in certain embodiments to better retain chassis  50 ,  150 ,  350 ,  650 ; and that, if necessary, the respective stop surfaces of chassis  50 ,  150 ,  350 ,  650  that engage stop surfaces  34 ,  134 ,  334 ,  534 ,  634  of shells  20 ,  120 ,  320 ,  520 ,  620  may be angled as well. In other words, in one embodiment, stop surfaces  34 ,  134 ,  334 ,  534 ,  634  of respective shells  20 ,  120 ,  320 ,  520 ,  620  may be arranged so that an acute angle is formed at the junction of the inner surface of shells  20 ,  120 ,  320 ,  520 ,  620  and the relevant stop surface  24 ,  134 ,  334 ,  534 ,  634 . In this manner, the respective component of chassis  50 ,  150 ,  350 ,  650  (e.g., toe cap  52 ,  152 ,  352 ,  652 , heel counter  86 ,  186 ,  386 , and/or metatarsal guard  198 ) may be more securely retained within shell  20 ,  120 ,  320 ,  520 ,  620  via the interaction between the stop surface(s) of those components, and the angled stop surfaces  34 ,  134 ,  334 ,  534 ,  634  of shells  20 ,  120 ,  320 ,  520 ,  620 . Of course, in some cases several of stop surfaces  34 ,  134 ,  334 ,  534 ,  634  of shells  20 ,  120 ,  320 ,  520 ,  620  may be arranged at an acute angle while others are arranged as shown in the figures and described above. Thus, varying combinations are possible. It is also the case that the stop surface(s) on certain components of chassis  50 ,  150 ,  350 ,  650  (e.g., toe cap  52 ,  152 ,  352 ,  652 , heel counter  86 ,  186 ,  386 , and/or metatarsal guard  198 ) may be angled as well to mate with the acute angle of stop surfaces  34 ,  134 ,  334 ,  534 ,  634 . 
         [0047]    As yet another example, while metatarsal guard  198  is not shown in connection with chassis  350  of  FIG. 3B , it is contemplated that guard  198  may be situated on chassis  350  in much the same manner as chassis  150 . Thus, certain components from one of chassis  50 ,  150 ,  350 ,  650  may be substituted or added to another of chassis  50 ,  150 ,  350 ,  650 , although not depicted in the figures. 
         [0048]    Further, it is also contemplated that the various components of chassis  50 ,  150 ,  350 ,  650  may be arranged differently than shown in the figures. For example, while puncture-resistant insole  410  is shown as being attached to inner surfaces  354 ,  388  of toe cap  352  and heel counter  386 , respectively, insole  410  may be arranged to overlay toe cap  352  and heel counter  386  (e.g., be attached to outer surfaces  356 ,  390  thereof). In such an embodiment, shell  320  (in particular recessed areas  331 ,  332 ) may also be reconfigured so that chassis  350  is securely retained within shell  320 . Thus, a number of different configurations are contemplated in which the various chassis  50 ,  150 ,  350 ,  650  may be rearranged and accommodated, securely, within one of shells  20 ,  120 ,  320 ,  520 ,  620 . 
         [0049]    As yet another example, it is contemplated that any of chassis  50 ,  150 ,  350 ,  650  may be composed of expandable materials (like shells  20 ,  120 ,  320 ,  520 ,  620 ) so that, once inserted into shell  20 ,  120 ,  320 ,  520 ,  620 , the chassis  50 ,  150 ,  350 ,  650  may expand and be more securely retained within recessed areas  31 ,  32 ,  131 ,  132 ,  331 ,  332 ,  531 ,  532 . The expandable materials that could be utilized to compose chassis  50 ,  150 ,  350 ,  650  are set forth above. 
         [0050]    It is also the case that shells  20 ,  120 ,  320 ,  520 ,  620 , while described above as being formed via the use of expandable materials, may alternatively be formed with non-expandable materials (e.g., traditional rubber materials, other composites, etc.) In short, the concepts of the present invention(s) have applicability with non-expandable shells  20 ,  120 ,  320 ,  520 ,  620  in that such shells  20 ,  120 ,  320 ,  520 ,  620  may receive any of chassis  50 ,  150 ,  350 ,  650  securely therein to adequately comply with the aforementioned safety standards. The chassis  50 ,  150 ,  350 ,  650 , once inserted within the particular shell  20 ,  120 ,  320 ,  520 ,  620 , however, would likely be non-removable from such shell  20 ,  120 ,  320 ,  520 ,  620  to meet those standards. 
         [0051]    Although aspects of the invention(s) herein have been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of aspects of the present invention(s). It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention(s) as set forth in the appended claims. 
         [0052]    It will also be appreciated that the various dependent claims and the features set forth therein can be combined in different ways than presented in the initial claims. It will also be appreciated that the features described in connection with individual embodiments may be shared with others of the described embodiments.