Boots – shoes – and leggings – Sole-attaching means – Welt connected
Reexamination Certificate
1998-06-25
2001-05-08
Sewell, Paul T. (Department: 3728)
Boots, shoes, and leggings
Sole-attaching means
Welt connected
C036S02200A, C036S03000A, C036S071500, C036S014000, C012S1420MC, C012S1420MC
Reexamination Certificate
active
06226895
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to footwear construction, and more particularly to a footwear construction in which the sole is attached to the upper by a welt.
A variety of different sole constructions are used by the footwear industry. For the most part, each sole construction has characteristics that make it particularly well-suited for specific applications. For example, some sole constructions are selected for their durability, others for their flexibility and comfort, while still others are selected for their aesthetic appeal. One particularly popular type of sole construction is referred to as a welt construction. Welt constructions are popular because they are durable and are aesthetically desirable. There are a variety of different types of welt constructions, but in each construction a “welt,” for example, a strip of material such as leather or hard rubber, is used to intersecure the sole and the upper.
FIG. 1
is an exploded sectional view of a conventional welt construction. This construction includes a welt
150
that interconnects an upper
158
and a sole
172
. The welt
150
includes a base portion
152
with an upwardly extending rib
154
located toward the center of the base portion and a downwardly extending rib
156
located at the inner edge of the base portion
152
. The sole
172
includes an insole
160
, a midsole
168
, and an outsole
170
. The insole
172
includes a downwardly extending rib
164
that is used in interconnecting the insole
160
, upper
158
and welt
150
.
Assembly of this construction involves a number of common steps. First, the elements of the upper
158
are cut from the desired material and fit together (typically by sewing). The fitted upper
158
is then wrapped tightly around a foot-shaped form, or last, and secured to the insole
160
by stapling, stitching, or otherwise fastening it to the insole rib
164
. This step gives the upper
158
the desired shape and is commonly referred to as lasting. Once lasted, the welt
150
is stitched or stapled to the upper
158
and insole
160
by stitches or staples that extend through the inner welt rib
156
, the bottom periphery of the upper
158
, and the insole rib
164
. The midsole
168
is stitched, stapled or otherwise secured to the bottom of the upper/insole assembly. Typically, the midsole
168
is attached to the upper/insole assembly by stitching that extends through the base portion
152
of the welt
150
and the midsole
168
. Afterwards, the outsole
170
is secured to the bottom of midsole
168
, typically by cement or other adhesives. Although this construction is durable and aesthetically appealing, it is a relatively heavy construction and it does not provide the flexibility of other constructions.
In an effort to improve the flexibility and reduce the weight of the sole, a variety of sole constructions have been developed which incorporate polyurethane. For example, some footwear manufacturers currently sell footwear that incorporates a solid polyurethane outsole. Typically, the polyurethane outsole is either directly attached to the upper or it is attached to a midsole that is in turn attached to the upper. Polyurethane is a relatively soft material and it is not as wear-resistant as many other outsole materials, such as leather and rubber. Also, polyurethane has relatively low tear-resistant characteristics. As a result, it does not hold a stitch or staple well, and is consequently not well suited for use in a welted construction.
In an effort to overcome these problems, a number of attempts have been made to enclose the polyurethane in a shell. The shell is relatively wear resistant and it forms the wear surface of the sole. One such construction includes a rubber shell that is filled with polyurethane. The shell is cemented to the upper in a conventional manner. Although this construction provides the improved comfort and weight characteristics of polyurethane, it fails to provide the durability and aesthetic benefits of a welt construction.
SUMMARY OF THE INVENTION
The aforementioned problems are overcome by the present invention wherein a sole construction is provided which includes a polyurethane filled outsole shell that is secured to the upper by a welt. The sole construction includes a generally conventional insole, an outsole shell manufactured from a durable, wear-resistant material, and a welt that interconnects the outsole shell and the insole with the upper. The outsole shell defines a chamber that contains a polyurethane filling material. The polyurethane filling material fills the chamber and bonds directly to the insole, welt, and outsole.
In a preferred embodiment, the welt includes a base portion that is stitched to the shell and a downwardly extending rib that is stitched to both the upper and the insole rib. The shell preferably defines a stitch channel that extends entirely around the circumference of shell to receive the stitches that interconnect the welt and the shell.
In a second aspect, the shell includes a plurality of protrusions, such as scallops, that extending into the polyurethane chamber. The polyurethane surrounds and attaches to the protrusions to enhance the connection between the polyurethane and the shell.
The present invention also provides a method for manufacturing a shoe. First, the upper is lasted and either stitched or stapled to the insole. The welt is then stitched or stapled to the insole/upper combination. Then, polyurethane is poured into the chamber in the shell and the shell is direct attached to the upper/insole/welt assembly. As the polyurethane cures, it expands to fill the space and bond to the shell, the insole, and the welt. The welt is then stitched to the shell around the entire periphery of the sole. The stitch extends between a stitch channel in the welt and a stitch channel in the shell, and preferably does not extend through the polyurethane.
The present invention provides a durable and comfortable sole construction. Because the present invention does not require a midsole, the construction is relatively flexible. The outsole shell provides the sole with excellent wear characteristics. Also, the use of polyurethane makes the outsole lighter and more resilient than a conventional welted construction. In addition, the stitch channel in the shell receives the stitching to protect it from abrasion and wear. The present invention is also easily manufactured using conventional machinery. Further, as the polyurethane cures, it expands into and seals the stitch holes and the seams between the insole, the welt, and the upper. As a result, the present invention allows the possible manufacture of the waterproof welted footwear without the need for a membrane.
These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.
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Sewell Paul T.
Stashick Anthony
Warner Norcross & Judd
Wolverine World Wide Inc.
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