Patent Description:
A sole, such as a midsole is a component of a shoe and may be attached to an upper. The sole can provide cushioning and stability to the shoe and, particularly for athletic footwear, absorb shock and control excessive foot motion, such as pronation and supination. A durability and aesthetic appeal of the midsole may be affected by a manufacturing process of the midsole. <CIT> describes moulds for producing shoes having soles moulded directly to the upper or separately moulded soles in which there is included means for positioning component shoe bottom parts in the mould preparatory to moulding.

A method for forming a sole, such as a midsole, for a shoe may include a perforated last. The perforated last may allow gases generated during a chemical reaction to form the midsole to be vented. The midsole may be attached to an upper of the shoe by adhering to a bottom edge of the upper or percolating through stitching of a sock liner. The resulting sole may include improved properties. A perforated last may also be provided. According to the claimed invention, there is provided a system for forming a shoe as defined in appended independent claim <NUM>. Specific embodiments are defined in the appended dependent claims.

The following description relates to systems and methods for manufacturing an article of footwear, and in one example, for manufacturing an athletic shoe. An example of a shoe is shown in <FIG>. The shoe may include an upper connected to a sole structure. The sole structure comprises one or more of an insole, a midsole, and an outsole. The components of the sole structure, as well as the upper of the shoe is depicted in an exploded view in <FIG> to show an ordering and geometry of the shoe elements. The midsole may be formed via injection molding, including mounting the upper on a perforated last for attachment of the midsole to the upper. An example of the perforated last is shown in <FIG>, illustrating positioning of perforations along surfaces of the last. The perforated last may be used during a process for forming the midsole and attaching the midsole to the upper of the shoe. Steps of the process are shown in <FIG>, illustrating a use of a mold into which a foamed material of the midsole may be injected or open poured/casted with the upper, mounted on the perforated last, positioned above the midsole and an outsole arranged below the midsole. Cross-sections of embodiments of the perforated last are shown in <FIG> and <FIG>, depicting a positioning of the perforated last relative to a cavity of the mold during formation of the midsole as well as geometries of an inner conduit of the perforated last. The foamed material of the midsole may attach to a sock liner or a seamed footbed of the upper of the shoe upon curing. Methods for attaching the midsole to the upper via curing of the midsole to the sock liner and seamed footbed are shown in cut-away views of <FIG> and <FIG>, illustrating a method comprising a Strobel seam of the sock liner and a method comprising a blind seam of the seamed footbed, respectively. An example of a method for manufacturing the shoe, including use of a perforated last and injection molding, open pouring or casting, for midsole formation, is provided in <FIG>.

Footwear, and in particular, athletic footwear, may include an upper and a sole structure. While the upper covers a foot and securely positions the foot with respect to the sole structure, the sole structure is positioned under the foot and provides a barrier between the foot and the ground. The sole structure may attenuate ground reaction forces, provide traction and stability, and control foot motion. By attaching the upper to the sole structure to form a shoe, the foot may be surrounded and supported by the shoe so that the wearer may comfortably participate in recreational activities, such as walking and running.

The sole structure may be formed from one or more stacked layers including an insole, a midsole, and an outsole. The insole may be a topmost layer positioned in the upper and configured to be adjacent to a plantar surface of the foot or liner and engage comfortably with the foot. The midsole may be secured to the upper along a length of the upper and form a middle layer of the sole structure between the insole and the outsole. Shock absorption, stability, and motion control are imparted to the wearer's foot by the midsole. The outsole is a bottommost layer of the sole structure and contacts the ground, due to its positioning under the midsole. The outsole may be formed from a durable, rugged material adapted with texturing to provide traction to the shoe. The example layers are for illustrative purposes and one or more of them may include multiple components and/or layers or be divided into continuous and/or discontinuous sections. Further, various layers may be omitted.

A performance of the shoe may be affected by properties of the midsole. For example, for a wearer desiring a high degree of comfort for long distance running, a thicker midsole may be desired. Wearers with foot conditions, such as plantar faciitis, may choose shoes with a firm midsole while trail runners may use shoes with thin midsoles to increase a stability of the foot relative to changes in ground terrain. A secure and comfortable attachment of the midsole to the upper may have a significant impact on a durability of the shoe and consumer appeal of the shoe. The appeal of the shoe may be further affected by aesthetic properties of the shoe, such as unmarred surfaces of the sole structure and smooth, continuous joints between components of the shoe.

The midsole may be formed from a polymer foam material, such as polyurethane (PU), ethylene vinyl acetate (EVA), rubber, or silicone, and constructed by compression molding, injection molding, open pouring, casting, among others. For athletic footwear, in one example, the midsole may be formed via an injection molding process that includes injecting a foaming material, such as PU, into a mold and allowing the foaming or foamed material to cure and harden onto the upper. The midsole may be attached to the upper by applying an adhesive and the outsole may be molded directly to the bottom surface of the midsole or also fixed to the midsole by an adhesive. Alternatively, the midsole may be directly attached to the upper during the injection step by positioning the upper over the mold during injection of the foaming material. A last may be inserted into the upper to provide a structural frame to the upper during the injection process. The last may be a mechanical form with a structure similar to a foot and constructed from a rigid material such as wood, metal, or high-density plastic, among others or combinations thereof. The foaming material may seep through fibers of the upper as well as Strobel or blind seam stitching extending around a perimeter of a foot bed of the inner, thus attaching the midsole to the upper through gaps in the upper materials when the foaming material hardens.

The inventors herein have recognized several issues with the methods described above. For example, during injection and curing of the foaming material, off-gassing may occur which releases macro bubbles, air traps, and/or voids in the midsole material. Macro bubbles, air traps, and voids may be pockets of air with a diameter of at least <NUM>. The foaming material may be enclosed by surfaces of low porosity, such as the mold surfaces and the last, resulting in a trapping of the bubbles, air traps, and voids within the midsole. A presence of macro bubbles, air traps, and voids in the midsole may appear as undesirable blemishes on an exterior surface of the midsole.

One or more of the issues described above may be at least partially addressed by a method for an article of footwear, comprising positioning a perforated last relative to a mold cavity, and injecting a material configured to form a foam into the cavity to form a sole directly attached to an upper around the perforated last. The method includes using a perforated last. The perforations extend through a thickness of the last to fluidly couple air surrounding the last to air within an inner conduit of the last. The perforations create a fluid coupling, during injection molding, opening pouring, or casting, between an interior of the mold cavity and a surrounding atmosphere through the last. Further, off-gassing release may be assisted by applying a vacuum to one or more passages formed in the last via the perforations. Gas produced during injection molding may be vented through the perforations, reducing a likelihood of formation of macro bubbles, air traps, and voids.

In addition, the perforated last may be used in combination with direct molding of the midsole to the upper with attachment between the upper and midsole achieved by either allowing the foaming material to seep through the upper materials (e.g., fibers or weave) or by engaging the midsole with a seamed footbed of the upper. Furthermore, even though there is a fluid passage enabling gas to escape, the sole material is held in place by the footbed or sock or other structure of the upper. This eliminates or minimizes trimming sole material seeping beyond a desired border, e.g., outer shape, of the midsole, thereby further reducing costs associated wih manual labor. Additional details and components of the method are elaborated in further detail with respect to the descriptions of <FIG>.

Turning now to <FIG>, a shoe <NUM> may comprise an upper <NUM> and a sole structure <NUM>. A set of reference axis <NUM> is provided, indicating a y-axis, an x-axis, and a z-axis. The upper <NUM> may be arranged above the sole structure <NUM> and adapted to allow a foot to be inserted into a cavity of the shoe <NUM> through an opening <NUM>. The foot is held in place in the shoe <NUM> by the upper <NUM> and may directly contact inner surfaces of the upper <NUM>. To provide comfortable engagement of the foot with the upper <NUM>, the upper <NUM> may be constructed from a flexible synthetic material, such as polyester, nylon, synthetic leathers, or a natural material such as leather. The shoe <NUM> may further include a sock liner arranged along an inner surface of the upper <NUM>, inside the cavity of the shoe, and attached to the upper <NUM> by stitching.

The upper <NUM> may be adapted with a lacing system <NUM> including a set of laces threaded through apertures in the upper <NUM> along a region of the upper <NUM> adjacent to an instep of the foot when the shoe <NUM> is worn. In other examples, the upper <NUM> may have a Velcro attachment instead of the lacing system <NUM> or neither the lacing system <NUM> or the Velcro attachment. The lacing system may be used to tighten the upper around the foot and enhance a securing of the foot inside the shoe <NUM>.

The upper <NUM> may be secured along a bottom edge <NUM> to the sole structure <NUM>. The sole structure may include an insole positioned inside the cavity of the shoe <NUM> along a footbed of the shoe, a midsole <NUM>, and an outsole <NUM>. The midsole <NUM> is directly adjacent to and above the outsole <NUM> so that the midsole <NUM> and the outsole <NUM> are in face-sharing contact, the shared face coplanar with an x-z plane. The midsole <NUM> may be a compressible layer of a foamed material, such as ethylene vinyl acetate (EVA), polyurethane (PU) or thermoplastic polyurethane (TPU) and, as described above, configured to attenuate ground forces and decrease impact transferred to the foot due to contact of the shoe with the ground. In some examples a thickness, defined along the y-axis, of the midsole <NUM> may vary according to a desire for increased shock absorption at certain regions relative to the foot. For example, a region under a heel of the foot may be thicker than a region under a ball of the foot if the shoe <NUM> is adapted for long distance running. In addition, a firmness of the midsole <NUM> may be non-uniform along the midsole <NUM> to provide stability or cushioning in desired regions of the midsole <NUM>.

The outsole <NUM> may have an upper face <NUM> that is contoured to match a bottom face <NUM> of the midsole <NUM>. A bottom face <NUM> of the outsole <NUM> may be textured to provide traction to the shoe <NUM>. The outsole <NUM> may be formed from a material that is less compressible and more durable than the midsole <NUM>, such as carbon rubber or blown rubber.

The components of a shoe <NUM> are shown in an exploded view <NUM> in <FIG>. The shoe <NUM> has a toe region <NUM> and a heel region <NUM> and comprises an upper <NUM> with a lacing system <NUM> and an opening <NUM> as well as a sole structure <NUM> that includes a midsole <NUM>, and an outsole <NUM>. The upper <NUM> may have an attached sock liner (not shown in <FIG>) that lines an interior of the upper <NUM> or may be directly stitched to a seamed footbed that provides a bottom surface to the upper <NUM>. Furthermore, in some examples, the sole structure <NUM> may also include an insole positioned below the upper <NUM> and above the midsole <NUM> that is contoured to match a shape of a foot. The insole may be arranged above the sock liner or the seamed footbed at a bottom of an inner cavity of the shoe <NUM> and may be formed from EVA.

The sole structure <NUM> may be shaped to match an outer geometry of a bottom edge <NUM> of the upper <NUM>. The midsole <NUM> may have a raised edge <NUM> surrounding at least a portion of a perimeter of the midsole <NUM> that extends above an upper surface <NUM> of the midsole. A width of the midsole <NUM>, defined along the x-axis, may be wider than a width of the upper <NUM> and the insole <NUM> so that the bottom edge <NUM> of the upper <NUM> may fit within and be surrounded by the raised edge <NUM> of the midsole <NUM>.

Portions of the outsole <NUM> in <FIG> may be similarly shaped as the midsole <NUM> but the outsole <NUM> may alternatively comprise a plurality of sections that are fixed to regions of a bottom surface of the midsole <NUM>. The outsole <NUM> may be adapted to provide traction in desirable regions of the sole structure <NUM>, such as under a ball of the foot. The outsole <NUM> may be thinner, as defined along the y-axis, than the midsole <NUM>. The outsole <NUM> may be contoured to match a shape of the midsole <NUM> and include a textured bottom face <NUM>.

A process to attach the components of the shoe <NUM> shown in <FIG> to form a unitary article of footwear may include the use of a last. The last may be a structure shaped similarly to a foot and formed from a rigid material such as wood, metal, or high density plastic. An upper and a sole structure of a shoe may be formed around the last and thus an overall shape of an interior of the shoe may depend on a geometry of the last.

During shoe formation, the upper may be wrapped snugly around an upper portion of the last. The last, and the upper, may be positioned on top of a mold so that the last is sealingly engaged with a top edge of the mold. A foamed material may be injected, open poured, or casted into a cavity of the mold, which may be a sealed chamber due to the positioning of the last over the mold. As the foamed material cures, gases may be generated that remain trapped within the cavity of the mold and within a material of the midsole. The trapped gases may form macro bubbles, air traps, or voids that may be visible along an outer surface of the midsole after curing is complete, leaving undesirable cosmetic defects.

To address the issue of macro bubble formation in the midsole, a perforated last is used. A first example of a perforated last <NUM> is shown from a side view <NUM> in <FIG> and from a bottom view <NUM> in <FIG>. The perforated last <NUM> has an upper portion <NUM>, as shown in <FIG>, shaped to represent an upper region of a foot and a lower region of an ankle. The upper portion <NUM> of the perforated last <NUM> has a forefoot portion <NUM>, representing an instep and toes of the foot and a heel portion <NUM>, representing a heel of a foot. An upper, such as the upper <NUM> of <FIG> and <NUM> of <FIG>, and including a sock liner, may be fitted around the upper portion <NUM> of the perforated last <NUM> and fastened tightly to secure the upper in place.

When the perforated last <NUM> is placed over a mold and a foamed material is injected into the mold to form a midsole, the midsole may conform to a shape of a footbed <NUM> of the perforated last <NUM>, as shown in <FIG>. The footbed <NUM> may be a bottom surface of the perforated last <NUM> and couple to the upper portion <NUM> via curved surfaces so that the perforated last <NUM> has a smooth continuous form.

The perforated last <NUM> includes perforations <NUM> extending through a thickness of the perforated last <NUM>. In one example, the perforated last <NUM> may be substantially hollow, with an inner conduit <NUM> that extends through the perforated last <NUM> so that the perforated last <NUM> is a shell with a thickness through which the perforations <NUM> extend. In this way, air in the inner conduit <NUM> is fluidly coupled to air surrounding the perforated last <NUM> through the perforations <NUM>. According to the claimed invention, the perforated last <NUM> is substantially solid and the inner conduit <NUM> extends down from an opening at a top of the perforated last <NUM> through a portion of a height <NUM> of the perforated last <NUM>, the height <NUM> defined along the y-axis. A manifold, arranged within the perforated last <NUM>, is coupled to the inner conduit <NUM>, fluidly coupled to the inner conduit <NUM> and extending substantially horizontally (e.g., along the z-axis) through the perforated last <NUM>. The perforations <NUM> are fluidly coupled to the manifold, thereby fluidly coupling air surrounding the perforated last <NUM> to air inside the inner conduit <NUM>.

The perforations <NUM> may be distributed in various regions of the perforated last <NUM>, such as along a lower edge <NUM> of the upper portion <NUM> of the perforated last <NUM> as shown <FIG>. The perforations <NUM> are also disposed in the footbed <NUM> of the perforated last <NUM>. The perforations <NUM> may generally be arranged in clusters or spaced apart evenly. According to the claimed invention, the clusters of the perforations <NUM> are positioned in regions where the midsole is anticipated to be thicker, such as under a heel of the foot along the footbed <NUM> in dashed region <NUM>, along an arch of the foot in dashed region <NUM>, under a ball of the foot in dashed region <NUM>, or under toes of the foot in dashed region <NUM>. The perforations <NUM> may also be clustered at regions where macro bubbles, air traps, and/or voids in the midsole may affect coupling of the midsole to the upper, such as along the lower edge <NUM> of the upper portion <NUM> of the perforated last <NUM> or along an upper surface of the forefoot portion <NUM> of the perforated last <NUM>, proximal to a perimeter of the perforated last <NUM>, as shown in <FIG>.

It will be appreciated that the perforated last <NUM> of <FIG> is a non-limiting example. Some examples of the perforated last <NUM> may include perforations <NUM> arranged in different patterns, spacing, size, geometry, and positions, relative to surfaces of the perforated last <NUM>, from those indicated in the present disclosure. Other examples may include different combinations of the clusters of perforations. For example, the shoe may have clusters of perforations <NUM> under the toes (dashed region <NUM>) and along the arch (dashed region <NUM>) or under the ball of the foot (dashed region <NUM>) and under the heel (dashed region <NUM>) or just under the ball of the foot. Numerous variations of the perforations <NUM> and clustering of the perforations <NUM> have been envisioned. Further, some or all of the example passages, connections, and/or manifolds illustrated in <FIG> and <FIG> may be incorporated in the last(s) of <FIG>.

As described above, the perforated last <NUM> may generally include the inner conduit <NUM> extending through the perforated last <NUM> so that the perforated last <NUM> is substantially hollow while the thickness of the perforated last <NUM> is sufficient to maintain a structural integrity of the perforated last <NUM>. According to the claimed invention, the perforated last <NUM> is substantially solid with a relatively shorter and narrower inner conduit <NUM> extending through a portion of the perforated last <NUM> and coupled to a manifold. The perforations <NUM>, extending through the thickness of the perforated last <NUM>, fluidly couple air inside the inner conduit <NUM> to air outside of and surrounding the perforated last <NUM>. Further details of a geometry of the perforations <NUM> are shown in <FIG> and elaborated further below. The fluid coupling of air inside and outside of the perforated last <NUM> allow gases formed during curing of the midsole to vent through the perforations <NUM>. Pressure in the midsole due to off-gassing may be equalized across the perforations <NUM>, releasing the gases to the atmosphere. In some examples, the inner conduit of the perforated last <NUM> may be coupled to a vacuum pump to further encourage evacuation of gases from the midsole during injection of the foamed material.

The venting of gases assisted by vacuum may be applied during a manufacturing process of a shoe. Additionally, or alternatively, venting to atmosphere unassisted by vacuum may also be used, if desired. Further, the level of vacuum applied may be adjusted during the manufacturing process. In one example, the vacuum level may be increased in response to formation of defects (which may be identified via a camera/inspection system automatically based on image processing of molded products) on the surface of the midsole, for example.

The manufacturing process is illustrated in the perspective views <NUM>, <NUM>, and <NUM> of <FIG>, respectively, of an example of a method that uses the perforated last <NUM> (e.g., the perforated last <NUM> of <FIG>) and a mold <NUM> to form a midsole of a shoe <NUM>. The mold <NUM> is shown in <FIG> and <FIG> with a portion of the mold cut away for illustrative purposes. The perforated last <NUM> may be hollow and include the inner conduit <NUM> fluidly coupled to perforations, such as the perforations <NUM> of <FIG>, of the perforated last <NUM>. An upper <NUM> of the shoe may be mounted tightly over the upper portion of the perforated last <NUM>. A footbed may be arranged between the upper and the perforated last <NUM>, the footbed attached to the perforated last <NUM> by stitching, glue, or fusing.

As illustrated in <FIG>, the perforated last <NUM> may be positioned over a cavity <NUM> in the mold <NUM>. The cavity <NUM> may be shaped similarly to the footbed of the perforated last <NUM> at a top of the cavity <NUM>, with respect to the y-axis, and may vary in geometry as the cavity <NUM> extends down into the mold <NUM>, depending on a desired shape of the midsole. For example, the cavity <NUM> may be configured to impart the midsole with curved sides, a textured pattern, or a widening of the midsole along the x-z plane, in a downwards direction away from the upper <NUM> of the shoe <NUM>.

The cavity <NUM> may extend entirely through thicknesses, defined along the y-axis, of a first half <NUM> and a second half <NUM> of the mold <NUM>. The first half <NUM> may be stacked on top of the second half <NUM> so that the cavity <NUM> is aligned through the first half <NUM> and the second half <NUM>. The second half <NUM> may include an inlet port <NUM> extending from an edge of the second half <NUM> of the mold <NUM> to the cavity <NUM>, which fluidly couples air surrounding the second half <NUM> of the mold <NUM> to air inside the cavity <NUM>. A thin flash <NUM> may run around a circumference of the cavity <NUM>, between the first half <NUM> and the second half <NUM>, extending a short distance in to the cavity <NUM> of the mold <NUM>. The flash <NUM> may seal the cavity <NUM> and retain foamed material, used to form the midsole, when the material is injected so that the foamed material does not leak down over the sides of an outsole <NUM>. The outsole <NUM> may be arranged in the cavity <NUM> to form a bottom layer of the shoe <NUM>.

A vertically-movable bottom piston <NUM>, e.g., able to slide along the y-axis, shaped similar to the cavity <NUM>, may be positioned at a bottom of the cavity <NUM> and may sealingly engage with the cavity <NUM> to form a floor of the cavity <NUM>. The outsole <NUM> may be preformed and arranged at a bottom of the cavity <NUM> on top of the bottom piston <NUM> while the bottom piston <NUM> is in a lowered position, as shown in <FIG>. An upper surface of the outsole <NUM> may be prepared for attachment to the midsole by roughening the upper surface, priming, and coating the upper surface with an adhesive such as cement. The cement may be heat-activated prior to formation of the midsole.

The perforated last <NUM> and the upper <NUM> may be lowered to contact the mold <NUM>, as shown in <FIG>. A mixer-injector <NUM> is inserted into the inlet port <NUM> and a measured amount of the foamed material, e.g., polyurethane, for example, is introduced through the inlet port <NUM>. The foamed material may initially be a liquid or gel that foams upon mixing with a chemical that triggers a foaming reaction either before or after injection. Alternatively the material may be injected already in a foamed consistency. The amount of polyurethane does not fill the cavity <NUM> of the mold <NUM> when the bottom piston <NUM> is in the lowered position. Injection of the desired amount of polyurethane is achieved by timing an interval during which gear pumps <NUM> and <NUM> are turned on to deliver components A and B, which, in one example, may be isocyanate and polyol resin to form polyurethane, to the mixer-injector <NUM> which is rotating as indicated by arrow <NUM> to mix components A and B. In other examples, however, an additional component C may be included to assist in the foaming process which may be a liquid or a gas.

Upon introduction of mixed components A and B to the cavity <NUM>, the bottom piston <NUM> is raised upwards, along the y-axis, so that an upper, outside edge of the outsole <NUM> engages with the flash <NUM>, as shown in <FIG>. The inlet port <NUM> is thereby closed off from the cavity <NUM> containing the polyurethane. The polyurethane foams and expands, filling the inner volume of the cavity <NUM> with the bottom piston <NUM> in a raised position to form a midsole <NUM>, and irreversibly coupling with a lower edge of the upper <NUM>. Off-gassing may occur as the polyurethane foams and expands, creating pockets of air within the polyurethane in the cavity <NUM>. The gas vents through perforations of the perforated last <NUM> and evacuation of the gas may be further assisted by connecting the inner conduit <NUM> of the perforated last <NUM> to a vacuum source. The finished shoe <NUM> may be removed by separating the first half <NUM> from the second half <NUM> of the mold <NUM>.

As another example of the manufacturing process, the midsole may be formed by a pouring process (e.g., open pouring or casting). The bottom piston <NUM> may be in the raised position, engaged with the flash <NUM>, with the mold <NUM> assembled so that the first half <NUM> is stacked on top of the second half <NUM>, to form an open receptacle for receiving the polyurethane (or some other type of material configured to foam) as a molten phase. The polyurethane may be poured into the cavity <NUM> and the perforated last <NUM> and upper <NUM> placed over the cavity <NUM>, thereby allowing the polyurethane to attach to the upper <NUM> as the material cures and hardens.

In this way, the perforated last <NUM> may provide a structural guide to form the midsole or sole of the shoe <NUM>, scaled at a <NUM> to <NUM> ratio of the last to the midsole and/orsole. The dimensions of the perforated last <NUM> thus determine the final dimensions of the midsole/sole of the shoe without adjustments to account for expansion or contraction of the midsole/sole material. Injection molding or open pouring or casting of the midsole/sole at the <NUM>:<NUM> scale allows the midsole/sole to be directly attached to upper components of the shoe <NUM> during the formation process.

While <FIG> show the perforated last in an upright position and positioned above the mold, relative to the y-axis, other examples may include different orientations of the perforated last and mold. For example, the components of the <FIG> may be positioned upside-down with respect to the views shown or perpendicular. Various alignments where the cavity of the mold receives the footbed of the perforated last have been envisioned and are within the scope of the present disclosure.

A cross-section <NUM> of second example of a perforated last <NUM> (in accordance with the claimed invention) is depicted in <FIG>, positioned over a cavity <NUM> of a mold <NUM>. The mold is similar to the mold <NUM> of <FIG>. The perforated last <NUM> is shown without a mounted upper of a shoe, e.g., the upper <NUM> of <FIG>. The perforated last <NUM> include perforations <NUM> arranged along a footbed <NUM> of the perforated last <NUM> as well as along upper surfaces of the perforated last <NUM>. A portion of the perforations <NUM> proximal to a toe region <NUM> of the perforated last <NUM> extend through a material of the perforated last <NUM> and fluidly couple to a manifold <NUM> in the last that is, in turn, fluidly coupled to an inner conduit <NUM> of the perforated last <NUM>. Another portion of the perforations <NUM> extend from an outer surface of the perforated last <NUM>, to the inner conduit <NUM>, such as the perforations proximal to a heel region <NUM> of the perforated last <NUM>. The manifold <NUM> may be a channel extending substantially along and at an angle to the z-axis, from the toe region <NUM> of the perforated last to the inner conduit <NUM>. The inner conduit extends from an opening <NUM> at a top of the perforated last <NUM>, down through a portion of a height of the perforated last <NUM>, the height defined along the y-axis. As such, the perforated last <NUM> is predominantly solid, e.g., not hollow.

A vacuum source <NUM>, such as a vacuum pump, may be attached to the opening <NUM> at the top of the perforated last <NUM>. When activated, the vacuum source may generate a low pressure region within the inner conduit <NUM> and the manifold <NUM> of the perforated last <NUM>. As a result, when a foamed material is injected through inlet port <NUM> in the direction indicated by arrow <NUM> to form a midsole, gases generated during the midsole forming process are forced to evacuate through the perforations <NUM>. When the material of the midsole is injected in the cavity <NUM> and a bottom piston <NUM> is raised, similar to the process described in <FIG>, the midsole material may undergo off-gassing as a volume of the cavity <NUM> is decreased and the foamed material cures.

The cavity <NUM> may be a fully enclosed chamber when the bottom piston <NUM> is raised so that the inlet port is blocked and air outside of the mold <NUM> does not exchange with air inside the cavity <NUM>. The cavity <NUM> may be surrounded by the footbed <NUM> of the perforated last <NUM>, side surfaces <NUM> of the mold <NUM>, and a top surface <NUM> of the bottom piston <NUM>. The side surface <NUM> of the mold <NUM> and the top surface <NUM> of the bottom piston <NUM> may be continuous surfaces that block gas flow. While the footbed <NUM> of the perforated last <NUM> may be formed from a material that is impermeable to liquids, the material may be gas permeable and the perforations <NUM> provide vents for gases to flow. Gases may travel through the foamed material in the cavity <NUM> and into the perforations <NUM>, as indicated by arrows <NUM> to equalize a pressure gradient between the cavity <NUM> and the inner conduit <NUM> of the perforated last <NUM>. Gases entering perforations <NUM> in the toe region <NUM> of the perforated last <NUM> may be channeled into the manifold <NUM> and then flow to the inner conduit <NUM> while gases entering perforations <NUM> in the heel region <NUM> of the perforated last <NUM> may be evacuated directly into the inner conduit <NUM>. The gases may be drawn to the vacuum source <NUM>, as indicated by arrows <NUM>, thereby reducing a likelihood that macro bubbles, air traps, or voids remain trapped within the midsole.

In another cross-section <NUM> of a third example of a perforated last <NUM> (not in accordance with the claimed invention), the perforated last <NUM> is similarly positioned over the mold <NUM>. the perforated last <NUM> may have a similar external shape as the perforated last <NUM> of <FIG>. The perforated last <NUM>, however, is substantially hollow with an inner conduit <NUM> that is larger in volume than the inner conduit <NUM> of <FIG>, extending through the perforated last <NUM> so that an inner surface <NUM> of the perforated last <NUM> is spaced away from an outer surface <NUM> of the perforated last <NUM> by a relatively uniform thickness of a material of the perforated last <NUM>. The thickness is a distance between the inner surface <NUM> and the outer surface <NUM> of the perforated last <NUM>. In this example, the perforated last <NUM> is hollow and configured as a shell.

Perforations <NUM> may extend through the thickness of the perforated last <NUM>, disposed in a footbed <NUM> as well as upper surfaces of the perforated last <NUM>. The perforations <NUM> allow gases, generated during the midsole formation process, to vent from the cavity <NUM> of the mold <NUM> into the inner conduit <NUM> of the perforated last <NUM>. Evacuation of gases from the foamed material of the midsole may be further assisted by actuating the vacuum source <NUM>, coupled to an opening <NUM> of the inner conduit <NUM> at a top of the perforated last <NUM>.

Gases in the midsole material contained in the cavity <NUM> may generate pressure within the cavity <NUM> and, unable to flow through side surfaces <NUM> of the mold <NUM> or the top surface <NUM> of the bottom piston <NUM>, may be channeled through the perforations <NUM>, as indicated by arrows <NUM>, and into the inner conduit <NUM> of the perforated last <NUM> to alleviate the pressure gradient. The pressure gradient between the cavity <NUM> of the mold <NUM> and the inner conduit <NUM> of the perforated last <NUM> may be exacerbated by the actuating vacuum source to decrease a pressure of the inner conduit <NUM>. Gases drawn into the inner conduit <NUM> of the perforated last <NUM> through the perforations <NUM> may flow to the vacuum source <NUM>, as indicated by arrows <NUM>.

A fourth example of a perforated last <NUM> (not in accordance with the claimed invention) is shown in a cross-section <NUM> in <FIG>. The perforated last <NUM> is similarly shaped and positioned over the mold <NUM> as the perforated lasts <NUM> and <NUM> of <FIG>, respectively. However, the perforated last <NUM> of <FIG> may be substantially solid, e.g., without any hollowed regions or inner chambers. The perforated last <NUM> may include a last extension <NUM> that protrudes upwards from an upper region of the perforated last <NUM>. The last extension <NUM> may be formed from a metal, or some other rigid material, and may be fixed to the upper region of the perforated last <NUM>. In one example, a vacuum source, such as the vacuum source <NUM> of <FIG>, may be coupled to the last extension <NUM>.

The perforated last <NUM> may comprise a first set of perforations that are through holes <NUM>, extending from an upper surface <NUM> of the perforated last <NUM> to a bottom surface <NUM> of the perforated last <NUM>. Air inside the cavity <NUM> of the mold <NUM> is fluidly coupled to air surrounding the perforated last <NUM>, external to the cavity <NUM>, via the through holes <NUM>, as indicated by arrows <NUM>. The through holes <NUM> allow gases generated during formation of a midsole in the mold cavity <NUM> to be vented from the cavity <NUM> to the surrounding atmosphere.

The perforated last <NUM> may also be adapted with a second set of perforations that are blind holes <NUM>, extending upward from the bottom surface <NUM> through a portion of a distance between the upper surface <NUM> and the bottom surface <NUM> of the perforated last <NUM>. The blind holes <NUM> may be coupled to conduits <NUM> extending through a material of the perforated last <NUM> that fluidly couples the blind holes <NUM> to a port <NUM> in the last extension <NUM>. Gases generated during formation of the midsole in the cavity <NUM> of the mold <NUM> may be vented through the blind holes <NUM>, as indicated by arrows <NUM> and conduits <NUM> to the surrounding atmosphere. Removal of gases through the blind holes <NUM> may be further aided by coupling the vacuum source to the last extension <NUM>.

Examples of how a midsole may irreversibly attach to a lower edge of an upper of a shoe is illustrated in detail in <FIG>. A first cut-away view <NUM> of an example of a shoe <NUM> is shown in <FIG> where Strobel stitches are used to connect an upper region <NUM> of a sock liner <NUM> to a bottom region <NUM> of the sock liner <NUM>. The sock liner <NUM> may be an inner liner of an upper <NUM> of the shoe <NUM>. A midsole <NUM> is arranged below the bottom region <NUM> of the sock liner <NUM> that curves up along an outer surface of the upper <NUM> to match a contour of a lower edge <NUM> of the upper <NUM>. An outsole <NUM> may be attached to a bottom surface of the midsole <NUM>.

The sock liner <NUM> may be similarly shaped to an interior cavity of the shoe <NUM> as well as to a shape of the perforated last. By arranging the sock liner <NUM> within the cavity of the shoe <NUM>, the sock liner <NUM> may provide a comfortable interface between upper regions of a user's foot, such as an instep, and the upper <NUM> of the shoe and also couple the upper <NUM> to the midsole <NUM> of the shoe <NUM>.

The sock liner <NUM> may be formed of a flexible, elastic knit material such as polyester, that is porous enough to allow air to flow through the material but not sufficiently porous to allow high viscosity fluids to flow through. The upper region <NUM> of the sock liner <NUM> may be attached to the bottom region <NUM> by a continuous border of stitching, forming a seam. In one example, the seam may be a Strobel seam that includes Strobel stitching. The Strobel seam may continue around a perimeter of the edge of the upper region <NUM> of the sock liner <NUM>, forming a continuous border of Strobel stitches. A Strobel stitch <NUM> is shown in <FIG> and illustrated in greater detail in an expanded view <NUM>. The Strobel stitch <NUM> may be a circular loop sewn by a Strobel machine that connects the upper <NUM>, the upper and bottom regions <NUM>, <NUM> of the sock liner <NUM> at an intersection of the upper <NUM> of the shoe <NUM> with the upper and bottom regions <NUM>, <NUM> of the sock liner <NUM>. At the Strobel stitch <NUM>, the upper <NUM> and the bottom region <NUM> of the sock liner <NUM> may be in edge sharing contact while the upper region <NUM> of the sock liner <NUM> may be stacked above the upper <NUM>.

Each Strobel stitch <NUM> of the Strobel seam may be spaced apart from adjacent Strobel stitches so that there are gaps between each Strobel stitch <NUM> of the seam. During injection of the foamed material of the midsole <NUM>, the foamed material may have low enough viscosity prior to curing to seep through the gaps between each Strobel stitch <NUM> of the seam. However, the viscosity may be high enough to not penetrate through the material of the bottom region <NUM> of the sock liner <NUM>. The seeping of the foamed material allows an amount of percolated material <NUM> of the midsole <NUM> to be disposed above the bottom region <NUM> of the sock liner <NUM> and above the upper region <NUM> of the sock liner <NUM> proximal to the Strobel stitch <NUM>. In some examples, the foamed material may also seep through a material of the upper <NUM> of and the sock liner <NUM> if the materials are of a sufficiently high porosity.

The percolation of the foamed material through the gaps of the Strobel seam secures the midsole <NUM> to the upper <NUM> of the shoe <NUM>. When the foamed material cures and hardens, the material of the midsole <NUM> extends continuously through the gaps of the Strobel seam, as well as through pores of the upper <NUM> materials, forming a plurality of ligaments between the midsole <NUM> and the percolated material <NUM>. Thus the midsole is maintained securely in place against the lower edge <NUM> of the upper <NUM> and the bottom region <NUM> of the sock liner <NUM> by anchoring of the midsole <NUM> to the sock liner <NUM> and upper <NUM> via the ligaments of foamed material.

The midsole <NUM> may be formed in a mold, such as the mold <NUM> of <FIG> and the mold <NUM> of <FIG> and <FIG>, that includes a single inlet port without additional ports or channels for exchange between air in a cavity of the mold and air surrounding the mold. In one example, a first half and a second half of the mold, with reference to the first and second halves <NUM>, <NUM> of the mold <NUM> of <FIG>, may not include any ports to vent gases or excess foamed material. The material of the midsole <NUM> is confined to the cavity while gases may pass through the gas-permeable bottom region <NUM> of the sock liner <NUM>. In contrast to conventional molds that include vent ports through which foamed material may seep, trimming of cured midsole material that percolates through the vent ports is no longer demanded. As a result, an amount of labor involved in the manufacturing process is reduced.

A second cut-away view <NUM> of an example of a shoe <NUM> is shown in <FIG> where a blind seam may be used to connect an upper <NUM> of a shoe <NUM> to a footbed <NUM>. The footbed <NUM> may be formed from a flexible material such as nylon that is porous so that air may flow through the material but is impermeable to viscous fluids. The blind seam may bind a bottom edge <NUM> of the upper <NUM> to an edge of the footbed <NUM> and continue around a perimeter of the footbed <NUM>. A midsole <NUM> is arranged below the footbed <NUM> and may curve up along an outer surface of the upper <NUM> to match a contour of a lower portion <NUM> of the upper <NUM>. An outsole <NUM> may be attached to a bottom surface of the midsole <NUM>.

The bottom edge <NUM> of the upper <NUM> and the edge of the footbed <NUM> may be stitched so that the bottom edge <NUM> of the upper <NUM> and the edge of the footbed <NUM> bend at a merging region and angle downwards, along the y-axis, extending away from an interior <NUM> of the shoe <NUM> and below a horizontal stitch <NUM>. The extension of the bottom edge <NUM> of the upper <NUM> and the edge of the footbed <NUM> away from the interior <NUM> of the shoe <NUM> may form a seam allowance <NUM>.

The blind seam may comprise a plurality of horizontal stitches, represented in <FIG> by the single horizontal stitch <NUM>, and illustrated in greater detail in an expanded view <NUM>. The horizontal stitch <NUM> may be coaxial with the x-axis and may couple the bottom edge <NUM> of the upper <NUM> to the edge of the footbed <NUM> to form the seam allowance <NUM>. The seam allowance <NUM> may terminate at a lower end with raw ends <NUM> and <NUM> of the upper <NUM> and the footbed <NUM>, respectively.

The horizontal stitch <NUM> and a high density (e.g., small gaps in between) of the horizontal stitches of the blind seam, or, in some examples, overlapping horizontal stitches of the blind seam, may block a foamed material (used to form the midsole <NUM>) from percolating through the blind seam. As the foam material cures, the material may irreversibly couple with surfaces provided by the irregularly shaped raw ends <NUM>, <NUM> of the upper <NUM> and the footbed <NUM>, as well as to surfaces of the seam allowance <NUM>, and the horizontal stitch <NUM>. The midsole <NUM> is thereby securely attached to the upper <NUM> of the shoe <NUM> by curing and coupling to the seam allowance <NUM> which extends downwards into the midsole <NUM>.

A midsole of a shoe may be attached to an upper of the shoe by injecting a foamed material, as shown in <FIG>, and allowing the foamed material to cure and attach by either percolating through a Strobel seam, as shown in <FIG>, or adhering to a seam allowance of a blind seam, as shown in <FIG>. While both methods may be similarly effective for securing the midsole to the upper, the use of the blind seam may be more desirable with respect to aesthetic appeal. The percolation of the foamed material through Strobel stitches of the Strobel seam may appear as an irregular mass of hardened material along in an interior perimeter of a bottom region of a sock liner in the shoe. The blind seam, however, retains the foamed material in the midsole, imparting the interior with a more clean appearance and well-defined borders between components of the shoe, such as between the upper and the footbed. Thus, from a marketing perspective, the blind seam method may be deemed more desirable.

An example of a method <NUM> for forming an article of footwear, such as a shoe, by an injection molding process is provided in <FIG>. The method <NUM> includes using a perforated last, such as the perforated last of <FIG> and a mold with a cavity, such as the mold <NUM> of <FIG> or the mold <NUM> of <FIG> and <FIG>. At <NUM>, the method includes preparing components of the shoe. The preparation may include mounting upper components of a shoe onto the perforated last. The upper components may include a preformed upper and a sock liner, or an upper with a seamed footbed or a single upper unit without a sock liner or footbed. Preparing the components may also include inserting the perforated last into the sock liner or upper with the upper wrapped around an upper portion of the last at <NUM>. The upper may be tightened by adjustment of a lacing system or by a Velcro fastening system.

Preparing the shoe components may also include preparing an upper surface of a preformed outsole by roughening and priming the surface at <NUM>. An adhesive such as cement may be applied to the upper surface of the outsole and the outsole may be heated to activate the cement. Furthermore, presparing the shoe components may include positioning the outsole at a bottom of the cavity of the mold at <NUM>, while a bottom piston of the mold, such as the bottom piston <NUM> of <FIG> is in a lowered position. Preparation of the shoe components further include, at <NUM>, positioning the perforated last over the cavity of the mold so that the cavity is a closed sealed chamber.

At <NUM>, the method includes injecting a foamed material, such as polyurethane, through an inlet opening in a bottom half of the mold. The foamed material may fill a portion of the inner volume of the cavity. The bottom piston is raised at <NUM> so that the outsole, resting on the bottom piston, is above the inlet opening in the bottom half of the mold and air surrounding the mold is not fluidly coupled to air in the cavity through the inlet opening.

At <NUM>, the method includes evacuating gas generated during curing of the foamed material. The gas may be evacuating by venting through a material of a bottom region of the sock liner (that is impermeable to the foamed material) and through perforations of the perforated last. The perforations may be fluidly coupled to an inner conduit of the perforated last. The evacuated gas may be emitted to the atmosphere via the inner conduit. The inner conduit may also be coupled to a vacuum source, such as a vacuum pump, to evacuate gases from the foamed material more efficiently.

Evacuation of gases from the foamed material of the midsole may occur for a duration of a hardening period of the foamed material, such as <NUM>-<NUM> minutes. As the foamed material hardens and cures, the material may percolate through Strobel stitches of a Strobel seam, as well as a material of the upper components, coupling the upper region of the sock liner to the bottom region of the sock liner, as well as to the upper, thereby securing the midsole to the upper. Alternatively, the foamed material may irreversibly couple to a seam allowance of a blind seam of the upper and footbed, similarly attaching the midsole to the upper of the shoe if a blind seam is present instead of the Strobel seam. At <NUM> of the method, the mold is opened by separating a top half and the bottom half of the mold and the completed shoe is removed.

In this way, a shoe may be manufactured by using a perforated last and forming a midsole by injection molding. A foamed material may be injected, open poured, or casted into a mold and gases generated during curing of the foamed material may be evacuated through perforations of the perforated last. The perforations are fluidly coupled to an inner conduit of the perforated last that may be coupled to a vacuum pump to assist in drawing gas bubbles, air traps, and voids out of the midsole. Reducing the presence of bubbles, air traps, and voids in the midsole may improve an aesthetic quality of the midsole. An effectiveness of coupling of the midsole to an upper of the shoe may be further enhanced by providing surfaces of a seam allowance of a blind seam, the blind seam attaching a footbed to the upper, for adherence. Alternatively, the foamed material may percolate through Strobel stitching of a Strobel seam of a sock liner, as well as through materials of the upper, to similarly attach the midsole to the upper of the shoe. The combination of the perforated last with direct coupling of the midsole to the sock liner provides a simpler, faster manufacturing process than conventional methods and reduces a likelihood of forming cosmetically degraded midsoles, thereby reducing costs and improving production efficiency.

There is generally described herein a method which does not belong to the claimed invention and which includes positioning a perforated last relative to a cavity of a mold; and injecting a material configured to form a foam into the cavity to form a sole directly attached to an upper around the perforated last. A first example of the method includes injecting the material into the cavity to form a midsole arranged between the upper and an outsole and wherein the material is injected through an inlet port of the mold, the inlet providing a single source of entry of the material into the cavity. A second example of the method optionally includes the first method and further includes wherein forming the midsole includes enclosing the material of the sole within continuous, gas-impermeable surfaces of the mold that do not include openings in addition to the inlet port and trapping the material of the midsole within the surfaces of the cavity of the mold when a bottom piston of the mold is raised while flowing gas through perforations of the perforated last from the midsole to an inner conduit of the last, the inner conduit forming an opening at a top of the last. A third example of the method optionally includes one or more of the first and second methods, and further includes, flowing gas through the perforations from the midsole to a manifold fluidly coupling the perforations to the inner conduit and wherein the inner conduit is coupled to a vacuum source. A fourth example of the method optionally includes one or more of the first through third examples, and further includes, mounting an upper of the article of footwear onto the perforated last. A fifth example of the method optionally includes one or more of the first through fourth examples, and further includes, wherein mounting the upper onto the perforated last includes inserting the perforated last into the upper attached to a seamed footbed, the seamed footbed coupled to the upper by a blind seam continuing around a perimeter of the footbed. A sixth example of the method optionally includes one or more of the first through fifth examples, and further includes, wherein attaching the midsole to the upper includes curing the foamed material around a seam allowance of the blind seam, the seam allowance extending downwards into the midsole. A seventh example of the method optionally includes one or more of the first through sixth examples, and further includes, wherein mounting the upper onto the perforated last includes positioning a sock liner between the upper and the perforated last and covering a bottom surface of the perforated last with a bottom region of the sock liner, the sock liner formed from a gas-permeable material. An eighth example of the method optionally includes one or more of the first through seventh examples, and further includes, wherein attaching the midsole to the upper includes engaging the foamed material with the bottom region of the sock liner so that the foamed material is in direct contact with a seam extending around a perimeter of the bottom region of the sock liner. A ninth example of the method optionally includes one or more of the first through eighth examples, and further includes, wherein attaching the midsole to the upper includes seeping the foamed material through gaps between Strobel stitches forming the seam of the sock liner, and through pores of a material of the upper, into an interior of the article of footwear, and curing the foamed material with a portion of the foamed material disposed in the interior of the article of footwear and coupled to the midsole via extensions of the foamed material through the gaps.

According to the claimed invention, the system includes a perforated last, a mold with a cavity shaped to receive a bottom region of the perforated last, and an injection machine configured to couple to an inlet port in the mold and to inject a material configured to foam and form a sole. The perforated last has a plurality of perforations extending through a thickness of a wall of the perforated last, a portion of the the plurality of perforations fluidly coupling air inside an inner conduit of the perforated last to air outside of the perforated last and wherein the plurality of perforations are clustered adjacent to regions of the midsole where an increased thickness of the sole is desired. The perforated last is substantially solid and the inner conduit extends down from an opening at a top of the perforated last through a portion of a height of the perforated last. A manifold is arranged within the perforated last and is coupled to the inner conduit, wherein the manifold is fluidly coupled to the inner conduit and extends through the perforated last. A portion of the perforations are fluidly coupled to the manifold, thereby fluidly coupling air surrounding the perforated last to air inside the inner conduit. The system optionally includes, wherein the inner conduit of the perforated last is adapted to couple to a vacuum source and wherein the inner conduit is a channel for gas to be drawn from the foamed material of the sole, where the inner conduit is positioned between perforations of the perforated last and the vacuum source. The system optionally includes, wherein a seam formed of Strobel stitches, spaced apart from one another, connects an upper of the shoe to a sock liner and wherein a portion of the foamed material is arranged within an interior of the shoe, along the seam of Strobel stitches and coupled to the sole by ligaments of foamed material extending through gaps between the Strobel stitches. The system optionally includes, wherein a blind seam connects an upper of the shoe to a footbed of the shoe with a seam allowance extending downwards into the sole and wherein the sole is bonded to the seam allowance and the foamed material of the sole is maintained within the sole, below the seamed footbed.

Claim 1:
A system for forming a shoe (<NUM>, <NUM>, <NUM>, <NUM>) comprising;
a perforated last (<NUM>, <NUM>, <NUM>, <NUM>);
a mold (<NUM>, <NUM>) with a cavity (<NUM>, <NUM>) shaped to receive a bottom region of the perforated last (<NUM>, <NUM>, <NUM>, <NUM>); and
an injection machine configured to couple to an inlet port (<NUM>, <NUM>) in the mold (<NUM>, <NUM>) and to inject a material configured to foam and form a sole (<NUM>, <NUM>),
wherein the perforated last (<NUM>, <NUM>, <NUM>, <NUM>) has a plurality of perforations (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) extending through a thickness of a wall of the perforated last (<NUM>, <NUM>, <NUM>, <NUM>), the plurality of perforations (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) fluidly coupling air inside an inner conduit (<NUM>, <NUM>, <NUM>) of the perforated last (<NUM>, <NUM>, <NUM>, <NUM>) to air outside of the perforated last (<NUM>, <NUM>, <NUM>, <NUM>) and wherein the plurality of perforations (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) are clustered adjacent to regions of the midsole (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) where an increased thickness of the sole (<NUM>, <NUM>) is desired, and
wherein the perforated last (<NUM>, <NUM>, <NUM>, <NUM>) is substantially solid and the inner conduit (<NUM>, <NUM>, <NUM>) extends down from an opening (<NUM>) at a top of the perforated last (<NUM>, <NUM>, <NUM>, <NUM>) through a portion of a height of the perforated last (<NUM>, <NUM>, <NUM>, <NUM>);
wherein a manifold (<NUM>) is arranged within the perforated last (<NUM>, <NUM>, <NUM>, <NUM>) and is coupled to the inner conduit (<NUM>, <NUM>, <NUM>), wherein the manifold (<NUM>) is fluidly coupled to the inner conduit (<NUM>, <NUM>, <NUM>) and extends through the perforated last (<NUM>, <NUM>, <NUM>, <NUM>),
wherein a portion of the perforations (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) are fluidly coupled to the manifold (<NUM>), thereby fluidly coupling air surrounding the perforated last (<NUM>, <NUM>, <NUM>, <NUM>) to air inside the inner conduit (<NUM>, <NUM>, <NUM>).