Patent Publication Number: US-2019168475-A1

Title: Sole Assembly Formed of Multiple Preforms

Description:
RELATED APPLICATION DATA 
     This application is a continuation of U.S. patent application Ser. No. 14/252,045 filed Apr. 14, 2014 and entitled “Method of Manufacturing Sole Assembly Formed of Multiple Preforms.” U.S. patent application Ser. No. 14/252,045 is entirely incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     Aspects of this invention relate generally to a method of manufacturing a sole assembly, and, in particular, to a method of manufacturing a sole assembly formed of multiple preforms having different colors. 
     BACKGROUND OF THE INVENTION 
     Conventional articles of athletic footwear include two primary elements, an upper and a sole assembly. The upper provides a covering for the foot that comfortably receives and securely positions the foot with respect to the sole assembly. In addition, the upper may have a configuration that protects the foot and provides ventilation, thereby cooling the foot and removing perspiration. The sole assembly is secured to a lower portion of the upper and is generally positioned between the foot and the ground. In addition to attenuating ground reaction forces, the sole assembly may provide traction, control foot motions (e.g., by resisting over pronation), and impart stability, for example. Accordingly, the upper and the sole assembly operate cooperatively to provide a comfortable structure that is suited for a wide variety of activities, such as walking and running. An insole may be located within the upper and adjacent to a plantar (i.e., lower) surface of the foot to enhance footwear comfort, and is typically a thin, compressible member. 
     The sole assembly may incorporate multiple layers. Some footwear include only a midsole, while others may also include an outsole secured to a bottom surface of the midsole. The midsole, which is conventionally secured to the upper along the length of the upper, is primarily responsible for attenuating ground reaction forces. The midsole may also form the ground-contacting element of footwear. In such embodiments, the midsole may include texturing, such as projections and recesses or grooves, in order to improve traction. The outsole, when present, forms the ground-contacting element and may be fashioned from a durable, wear-resistant material. 
     The midsole may be primarily formed from a resilient, polymer foam material, such as ethylvinylacetate (EVA), that extends throughout the length of the footwear. The properties of the polymer foam material in the midsole are primarily dependent upon factors that include the dimensional configuration of the midsole and the specific characteristics of the material selected for the polymer foam, including the density of the polymer foam material. By varying these factors throughout the midsole, the relative stiffness and degree of ground reaction force attenuation may be altered to meet the specific demands of the activity for which the footwear is intended to be used. In addition to polymer foam materials, conventional midsoles may include, for example, one or more fluid-filled bladders and moderators. 
     The sole assembly may be formed of multiple portions, with some or all of the portions having different colors. When EVA is formed in a mold assembly the color lines between the different colored portions may bleed, decreasing the aesthetic appeal of the footwear. 
     It would be desirable to provide a method of manufacturing a sole assembly for an article of footwear that reduces or overcomes some or all of the difficulties inherent in prior known processes. Particular objects and advantages will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain embodiments. 
     SUMMARY 
     The principles of the invention may be used to advantage to provide a method of manufacturing a sole assembly formed of multiple preforms. In accordance with certain embodiments, the preforms have different colors. 
     In accordance with a first aspect, a method of forming a sole assembly includes positioning a plurality of preforms having different colors together to form a sole assembly preform and placing the sole assembly preform in a recess in a first portion of a mold assembly. The sole assembly preform is subjected to heat for a predetermined amount of time such that the plurality of preforms bond to one another to form a sole assembly. 
     In accordance with another aspect, a method of forming a sole assembly includes positioning a first preform having a first color, a second preform having a second color, and a third preform having a third color together to form a sole assembly preform. The sole assembly preform is placed in a recess in a first portion of a heated mold assembly. The mold assembly is closed such that a second portion of the mold assembly is above and in contact with the first portion. The sole assembly preform is subjected to heat for a predetermined amount of time such that the first, second, and third preforms bond to one another to form a sole assembly. The mold assembly is opened the sole assembly is removed from the mold assembly 
     In accordance with a further aspect, a method of forming a sole assembly includes forming a first preform having a first color in a recess of a first mold assembly, with a bottom surface of the recess including surface irregularities. A plurality of second preforms having a second color are formed in first recesses of a second mold assembly. A third preform having a third color is formed in a second recess of the second mold assembly. The first preform, the second preforms, and the third preform are positioned together to form a sole assembly preform. The sole assembly preform is placed in a recess in a first portion of a heated third mold assembly. The third mold assembly is closed such that a second portion of the third mold assembly is above and in contact with the first portion. The sole assembly preform in the third mold assembly is subjected to heat for a predetermined amount of time such that the first, second, and third preforms bond to one another to form a sole assembly. The third mold assembly is opened and the sole assembly is removed from the third mold assembly. The sole assembly is allowed to cool, and is then trimmed. 
     Features and advantages of manufacturing sole assemblies for footwear as disclosed here will be further understood from the following detailed disclosure of certain embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevation view of an article of footwear including an upper and a sole assembly. 
         FIG. 2  is a plan view of a bottom of the sole assembly of  FIG. 1 . 
         FIG. 3  is a perspective view in exploded form of the sole assembly of  FIG. 1 . 
         FIG. 4  is a perspective view of a first mold assembly used to form a core portion of the sole assembly of  FIG. 3 . 
         FIG. 5  is a perspective view of a second mold assembly used to form inserts and a perimeter portion of the sole assembly of  FIG. 3 . 
         FIG. 6  is a section view of the bottom plate, sidewall plate, and core plate of the mold assembly of  FIG. 5  seen in a closed position and abutting relationship. 
         FIG. 7  is a section view of the bottom plate, sidewall plate, core plate, and top plate of the mold assembly of  FIG. 5  seen in a closed position and abutting relationship. 
         FIG. 8  is an elevation view of a third mold assembly having a top plate and a bottom plate, shown in exploded form with a preform prior to its positioning in the bottom plate. 
         FIG. 9  is an elevation view of the third mold assembly of  FIG. 8 , shown with the preform in a recess in the bottom plate. 
         FIG. 10  is an elevation view of the third mold assembly of  FIG. 8 , shown in a closed condition. 
     
    
    
     The figures referred to above are not drawn necessarily to scale, should be understood to provide a representation of particular embodiments of the invention, and are merely conceptual in nature and illustrative of the principles involved. Some features of the mold assemblies used to manufacture a sole assembly have been enlarged or distorted relative to others to facilitate explanation and understanding. The same reference numbers are used in the drawings for similar or identical components and features shown in various alternative embodiments. Mold assemblies for a sole assembly and methods of manufacture for such a sole assembly as disclosed herein would have configurations and components determined, in part, by the intended application and environment in which they are used. 
     DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS 
     An article of footwear  10  is depicted in  FIG. 1  as including an upper  12  and a sole assembly  14 . For purposes of reference in the following description, footwear  10  may be divided into three general regions: a forefoot region  16 , a midfoot region  18 , and a heel region  20 . Regions  16 - 20  are not intended to demarcate precise areas of footwear  10 . Rather, regions  16 - 20  are intended to represent general areas of footwear  10  that provide a frame of reference during the following discussion. Although regions  16 - 20  apply generally to footwear  10 , references to regions  16 - 20  also may apply specifically to upper  12 , sole assembly  14 , or individual components within either upper  12  or sole assembly  14 . 
     Upper  12  defines a void or chamber for receiving a foot. For purposes of reference, upper  12  includes a lateral side  22 , an opposite medial side  24 , and a vamp or instep area  26 . Lateral side  22  is positioned to extend along a lateral side of the foot (i.e., the outside) and generally passes through each of regions  16 - 20 . Similarly, medial side  24  is positioned to extend along an opposite medial side of the foot (i.e., the inside) and generally passes through each of regions  16 - 20 . Upper  12  may also include a closure mechanism, such as lace  28 . Upper  12  also includes an ankle opening  30  that provides the foot with access to the void within upper  12 . 
     Upper  12  may also include an insole (or sockliner, not shown), which is generally a thin, compressible member located within the void for receiving the foot and proximate to a lower surface of the foot. Typically, the insole, which is configured to enhance footwear comfort, may be formed of foam, and optionally a foam component covered by a moisture wicking fabric or textile material. Further, the insole or sockliner may be glued or otherwise attached to the other components of footwear  10 , although it need not be attached, if desired. 
     Sole assembly  14  may be directly secured to upper  12  with an adhesive, for example. Suitable adhesives are well known in the art and need not be discussed in greater detail here. Sole assembly  14  may be secured to upper  12  with any other suitable fastening means, and such other suitable means of sole assembly  14  to upper  12  will become readily apparent to those skilled in the art, given the benefit of this disclosure. 
     It is to be appreciated that in certain embodiments, sole assembly  14  may serve as a midsole, with an outsole (not shown) being secured to the bottom surface of the midsole. In other embodiments, as illustrated here, the bottom surface of sole assembly  14  serves as the ground-engaging portion (or other contact surface-engaging portion) of footwear  10 . 
     Sole assembly  14  is responsible for attenuating ground (or other contact surface) reaction forces to lessen stresses upon the foot and leg, and absorb energy. Sole assembly  14  may also beneficially utilize such ground reaction forces for more efficient toe-off, and control potentially harmful foot motions, such as over pronation. Sole assembly  14  also forms a ground-engaging portion (or other contact surface-engaging portion) of sole assembly  10 . As noted above, in certain embodiments there is a separate outsole member attached to the bottom surface of a midsole of sole assembly  14 , while in other embodiments there is no separate outsole member of the sole assembly. The bottom surface of sole assembly  14  may include texturing to improve traction. 
     Sole assembly  14  is formed of a plurality of components having different colors. The method used to form the sole assembly from a plurality of preforms having different colors reduces the bleeding between the different colored portions, thereby enhancing the aesthetics of sole assembly  14 . The plurality of components may also have, in addition to different colors, different physical properties or performance characteristics. For example, the hardness of the various components may be different. It is to be appreciated that any of the known physical properties or performance characteristics for sole assemblies can be different for the different components of sole assembly  14 , thereby altering the support, cushioning, load carrying capability, wear characteristics, and tread life of sole assembly  14 , for example. Other suitable physical properties or performance characteristics will become readily apparent to those skilled in the art, given the benefit of this disclosure. 
     As seen in the embodiment illustrated in  FIG. 2 , sole assembly  14  includes a first core portion  32 , one or more inserts  34 , and a perimeter portion  36 . Core portion  32  is formed of a first color, inserts  34  are formed of a second color, and perimeter portion  36  is formed of a third color. While three colors are used in this embodiment, it is to be appreciated that any number of different colors may be used for the various components of sole assembly  14  in accordance with the method of manufacture described below. 
     In certain embodiments, core portion  32 , inserts  34 , and perimeter portion  36  may be formed of injection phylon (Ethylene Vinyl Acetate or “EVA”). The EVA may have a Vinyl Acetate (VA) level between approximately 9% and approximately 40%. Suitable EVA resins include Elvax®, provided by DuPont, and Engage, provided by the Dow Chemical Company, for example. In certain embodiments, the EVA may be formed of a combination of high melt index and low melt index material. For example, the EVA may have a melt index between approximately 1 and approximately 50. 
     The EVA may also include various components including a blowing agent. The blowing agent may have a percent weight between approximately 10% and approximately 20%. Suitable blowing agents include azodicarboamide, for example. In certain embodiments, a peroxide-based curing agent, such as dicumyl peroxide may be used. The amount of curing agent may be between approximately 0.6% and approximately 1.5%. The EVA may also include homogenizing agents, process aids, and waxes. For example, a mixture of light aliphatic hydrocarbons such as Struktol® 60NS may be included. The EVA may also include other constituents such as a release agent (e.g., stearic acid), activators (e.g., zinc oxide), fillers (e.g., magnesium carbonate), pigments, and clays. 
     As illustrated in  FIG. 2 , perimeter portion  36  may form an entire outer periphery  38  of sole assembly  14 . In other embodiments, perimeter portion  36  may form just a portion of outer periphery  38 . As illustrated here, perimeter portion  36  may also completely surround an outer periphery  40  of core portion  32 . As illustrated here, inserts  34  may be completely surrounded by and contained within core portion  32 . 
     Preforms of the components of sole assembly  14  are seen in exploded form in  FIG. 3 . As seen here, core portion preform  32 ′ includes ribs  42  that extend downwardly from its lower surface  44 , and define a plurality of interior recesses  46 . Each insert preform  34 ′ is configured to be seated or received in one of interior recesses  46 . Ribs  42  also define a shoulder  48  extending about at least a portion of core portion preform  32 ′. 
     An aperture  50  extending through perimeter portion preform  36 ′ defines an interior lip  52  that is seated on shoulder  48  of core portion preform  32 ′. As seen in  FIG. 2 , in the finished product of sole assembly  14 , the surface of aperture  50  abuts the exterior perimeter of ribs  42 . 
     As seen here in  FIG. 3 , surface irregularities  53  may be formed in the lower surfaces of core portion preform  32 ′, insert preforms  34 ′, and perimeter portion preform  36 ′. Surface irregularities  53  may take any desired form. In the illustrated embodiment, surface irregularities  53  include a plurality of grooves  55  and lugs or projections  57 , which form a grid of hexagonal projections  57  with corresponding grooves  55  surrounding the projections, as seen more clearly in sole assembly  14  in  FIG. 2 . Surface irregularities  53  may serve aesthetic as well as performance purposes. 
     A method of forming sole assembly  14  that reduces bleeding between the colors of core portion preform  32 ′, insert preforms  34 ′, and perimeter portion preform  36 ′ will now be described. As seen in  FIG. 4 , a first preform mold assembly  54 , which is used to form core portion preform  32 ′, includes an upper plate  56  and a lower plate  58 . Upper plate  56  and lower plate  58  may be rotatably secured to one another with a hinge  60 . A projection  61  extending downwardly from upper plate  56  and a lower recess  62  formed in lower plate  58  cooperate to define a core recess  63 . As seen here, first preform mold assembly  54  includes two core recesses  63  in order to simultaneously form core portion preforms  32 ′ for both left and right sole assemblies. 
     Recesses  64  formed in the bottom of core recess  63  serve to form ribs  42  when core portion preform  32 ′ is formed in first preform mold assembly  54 . Recesses  64  may include surface irregularities  66 , which serve to form the mating surface irregularities  53  in the lower surface of ribs  42 , as described above in conjunction with  FIG. 2 . 
     Core portion preform  32 ′ is formed in core recess  63  of first preform mold assembly  54  in known fashion, with heated EVA being inserted into core recess  63 . The resultant EVA core portion preform  32 ′ is later combined with insert preforms  34 ′ and perimeter preform  36 ′ to form sole assembly  14 , as described in greater detail below. 
     A second preform mold assembly  68 , seen in  FIG. 5 , is used to form insert preforms  34 ′ and perimeter portion preform  36 ′. Second preform mold assembly  68  includes a bottom plate  70 , a top plate  72 , a core plate  73  positioned below top plate  72 , and a sidewall plate  74  positioned between bottom plate  70  and core plate  73 . The plates of second preform mold assembly  68  are connected by way of a hinge  76 . A projection  78  extending downwardly from core plate  73 , an aperture  80  extending through sidewall plate  74 , and a recess  82  formed in the top surface of bottom plate  70  cooperate to define first, or insert, recesses  84  and a second, or perimeter, recess  86 , seen in  FIGS. 6 and 7 . As seen here, second preform mold assembly  68  includes two sets of insert recesses  84  and two perimeter recesses  63  in order to simultaneously form of insert preforms  34 ′ and perimeter portion preforms  36 ′ for both left and right sole assemblies. 
     Surface irregularities  88  formed in the bottom surface of recess  82  serve to form the mating surface irregularities  53  in the lower surface of inserts  34  and perimeter portion  36 , as described above with respect to core portion  32  and in conjunction with  FIG. 2 . 
     A perimeter portion preform  36 ′ with insert preforms  34 ′ seated therein and formed in second preform mold assembly  68  is shown here for illustrative purposes in the right recess  82  of bottom plate  70 . It is to be appreciated that any number of insert preforms  34 ′ may be formed in second preform mold assembly  68 . In the illustrated embodiment, there are three insert preforms  34 ′ used to form sole assembly  14 . It is to be appreciated that a single insert preform  34 ′, or any number of insert preforms  34 ′, may be used to form sole assembly  14 . 
     As seen in  FIG. 6 , sidewall plate  74  and core plate  73  are pivoted downwardly into a closed position onto bottom plate  70 . The heated EVA for forming perimeter portion preform  36 ′ is then injected through a first gate  90  formed in core plate  73 , as illustrated with arrow A. The EVA for perimeter portion preform  36 ′ is thus positioned within perimeter recess  63 . 
     After heated EVA is injected into perimeter recess  63 , top plate  72  is then pivoted down into a closed position on core plate  73 . Heated EVA for forming insert portions  34 ′ is then injected through a second gate  92  formed in top plate  72  and core plate  73  into insert recesses  84 . Thus, the configuration of the second preform mold assembly  68  allows for the simultaneous formation of two different colors of the injected EVA material to form both insert preforms  34 ′ and perimeter portion preform  36 ′. 
     All of the preforms, that is, core portion preform  32 ′, insert preforms  34 ′, and perimeter portion preform  36 ′, each having a different color, are then preassembled into a single sole assembly preform  94 . As illustrated in  FIGS. 8-10 , this unitary sole assembly preform  94 , formed of all three colored materials is then placed in a single step into a recess  96  formed in a heated bottom plate  98  of a third mold assembly  100 , as depicted by arrow C. Once sole assembly preform  94  is seated in recess  96 , a top plate  102  of third mold assembly  100  is positioned on bottom plate  98  so as to close third mold assembly  100 . Sole assembly preform  94  is then subjected to heat within third mold assembly  100  for a predetermined time period so that core portion preform  32 ′, insert preforms  34 ′, and perimeter portion preform  36 ′ bond to one another, thereby forming sole assembly  14 . 
     In certain embodiments, third mold assembly  100  is maintained at a temperature between approximately 170° C. and 180° C. for approximately 10 minutes. The specific temperature and time period used to form sole assembly  14  in third mold assembly  100  can be varied, in known fashion, depending on the particular EVA used. 
     In known fashion, after sole assembly  14  is removed from third mold assembly  100 , sole assembly  14  will expand. Sole assembly  14  then goes through typical stabilization steps, including cooling and trimming, as necessary. 
     By inserting the entire unitary preform  94  into recess  96  at one time, bleeding between the different colors of the portions of preform  94  as sole assembly  14  is formed is reduced, since all of the materials start melting at the same time upon insertion into third mold assembly  100 . 
     In certain embodiments, as seen in  FIG. 2  and noted above, the surface irregularities  53  may form a defined pattern. As seen in the embodiment illustrated here, surface irregularities  53  form a grid of hexagonal projections  57  with corresponding grooves  55  formed about projections  57 . In such an embodiment, it may be desirable to have the boundaries between the different colors, that is, the color lines between core portion  32 , inserts  34 , and perimeter portion  36  not match or follow exactly along the edges of projections  57  or grooves  55 . Any bleeding between the different colors will be more observable if the color lines are attempted to line up with the edges of projections  57  and grooves  55 . The user&#39;s eye will be less likely drawn to the bleeding if the color lines move across projections  57 , rather than exclusively along the perimeters of projections  57 . 
     Thus, while there have been shown, described, and pointed out fundamental novel features of various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, it is expressly intended that all combinations of those elements and/or steps which perform substantially the same function, in substantially the same way, to achieve the same results are within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.