1. Field of the Invention
The invention relates to a method and apparatus for forming sheet material, and particularly sheet material that can be used as a stiffener. The sheet material can be used in many manufacturing processes, including, for example the manufacture of footwear, hats, luggage, golf bags and clothing, to name a few.
2. Description of the Related Art
Stiffeners are used in the footwear to provide varying degrees of resilience, stiffness and shape retention in the heel and toe portions of the footwear. These materials often are made from a needle punched non-woven fabric or a woven fabric. The fabric alone generally does not provide the desired degrees of resiliency, stiffness and shape retention. Hence, the fabric is treated with a resin, such as latex, to provide appropriate resiliency, stiffness and shape retention.
Several optional manufacturing processes have been used to provide the necessary resiliency, stiffness and shape retention to the stiffeners for shoes and sneakers. For example, some manufacturers pass a web of the woven or non-woven fabric from a roll through a bath of latex resin. The latex resin saturates the fabric. The saturated fabric then is passed from the bath and passes through heating devices for curing. Other manufacturing processes apply a latex powder to the woven or non-woven fabric rather than passing the fabric through a bath. The fabric then is heated sufficiently for the latex powder to melt into the fabric. Still other manufacturing processes extrude a coating of latex onto the non-woven fabric.
The stiffener typically must be adhered to adjacent layers of the footwear. Thus, the latex-saturated non-woven fabric typically is treated with a hot melt coating to provide a finished stiffener that has adhesive properties. Accordingly heat and/or pressure applied during the footwear manufacturing process will bond the stiffener to inner and outer layers of the footwear.
Stiffeners for footwear typically are made by manufacturers with special expertise in this technology. The manufacturers form the stiffeners from long rolled webs of non-woven fabric. The long webs then are cut into rectangular sheets that are stacked on a pallet, wrapped and transported to the manufacturer of the footwear. The footwear manufacturer then stamps out small blanks from the large sheets to form stiffeners of appropriate dimensions for the heel and/or toe portion of the footwear. The stiffener for the heel portion of the footwear generally is referred to as a heel counter, while the stiffener for the toe portion of the footwear generally is referred to as a box toe.
The stamping operation that is used to form the blanks 100 necessarily leaves a substantial amount of waste material as the blanks 100 are cut from the sheet. The skiving operation also creates a substantial amount of waste material, and the quality control checking typically identifies rejects that constitute waste. Waste produced during the manufacture of shoe stiffeners can be recycled due to environmental concerns of the shoe manufacturer and/or environmental laws of the governmental jurisdiction in which the shoe manufacturing is carried out. The shoe manufacturer typically will not have the interest or ability to undertake a recycling of the scrap stiffener materials. Hence, the shoe manufacturers typically return the scrap to the manufacturer of the stiffener materials for recycling.
The large sheets of stiffeners produced by the above-described prior art manufacturing processes typically is highly automated and often is carried out in more industrialized areas of the world. Other aspects of shoe manufacturing, including the skiving operations, are more labor intensive and hence often are carried out in less industrialized areas of the world. Thus, it is not uncommon for the sheets of stiffeners to be made in Europe or North America. The sheets then are transported long distances to areas of the world that have cheaper sources of labor. The scrap material then is transported back to the source of the sheet material. Hence, there are substantial shipping costs relating to portions of the stiffeners that are not used. The shoe manufacturing industry is highly competitive, and even small savings in cost can lead to a significant competitive advantage. Thus, processes that reduce or eliminate the transport of excess stiffener materials could be commercially very beneficial to the manufacturers of stiffeners.
Significant competition also exists among the shoe manufacturers. Hence, there is a commercial advantage to reducing the costly labor intensive aspects of shoe manufacturing, such as the above-described skiving operations and quality control checking.
The footwear industry was the focus of the preceding discussion of sheet materials and stiffeners. However, other industries employ sheet materials that must have specified stiffness, resiliency and shape retention characteristics. For example, sheet materials with specified stiffness, resiliency and shape retention characteristics are used in hats, purses, luggage, back packs, golf bags, clothing and many other products. Accordingly, an object of the invention is to provide a method for manufacturing sheet material, such as stiffeners, in a more efficient manner.
It is another object of the subject invention to provide an apparatus for efficiently manufacturing sheet material that must be cut and formed, such as the sheet material used in heel counters and box toes of footwear.
The invention relates to a process and apparatus for making profiled sheet material, such as sheet material that may be used for stiffening selected areas of footwear. The process includes forming a sheet material having appropriate stiffening, resiliency and shape retention characteristics for the specified end use. The process then includes cutting the sheet material into blanks with specified shapes and substantially simultaneously forming the cut blanks of sheet material to have the required profile. The forming step preferably is carried out to provide at least one chamfered edge on the sheet material.
The cutting and forming may be carried out with a stamping apparatus or with a rotary cutter. The stamping apparatus or the rotary cutter may include at least one continuous cutting edge for cutting through the sheet material. The stamping apparatus or the rotary cutter also may have a profiled region substantially bounded by the cutting edge. The cutting edge and the profiled region cut the sheet material into small blanks of specified shapes and substantially simultaneously form the cut blanks of the sheet material to have the specified profile. The forming aspect of the process may be carried out to define the above-referenced chamfer along at least one of the cut edges.
Embodiments of the invention that employ rotary cutters may cut sections of the sheet material from an elongate web while the web is fed longitudinally and continuously through the rotary cutter. Embodiments of the invention that employ a stamping press may cut the sections of the sheet material from an elongate web of sheet material as the sheet material is fed incrementally into and through the stamping press.
The formation of the specified profile on the blanks of sheet material requires some movement or flowing of the sheet material as part of the forming process. The cutting and forming of the blank of the sheet material can be carried out more easily if the sheet material is sufficiently warm to permit flowing of the sheet material in response to forces exerted by the forming and cutting die. Thus, the forming and cutting step of the process preferably is carried out before the sheet material is cured completely. Alternatively, the sheet material may be heated prior to forming and cutting to ensure that the sheet material can be formed without excessive pressure.
The sheet material that is subject to forming and cutting may be the above-described fabric that has been saturated with a resin. However, a preferred embodiment employs an extruded resin rather than a resin saturated fabric. The extrusion process enables a unitary matrix of resin to be formed with specified stiffening characteristics and with specified adhesive characteristics. Furthermore, the extruded resin is more easily formable than the resin saturated fabric. The apparatus for forming the resin web preferably includes an adjustable lip die to permit the thickness of the resin web to be varied in accordance with the specification of the finished product.
The process and apparatus of the invention eliminates the labor intensive skiving operations associated with the prior art. Hence, the stiffeners such as heel counters or box toes can be formed easily with a high degree of automation at the location at which the sheet material is formed. The profiled stiffeners then can be shipped to the site for manufacturing the finished product without the need to transport waste portions of the web to the site of manufacturing and then to transport waste portions of the web back to its origin for recycling. Hence, the subject invention results in very substantial reductions in shipping costs, and corresponding reductions in overall costs. For example, waste of the web may be ground up or otherwise processed at the site of the web production. Particles derived from the waste of the web may be heated or otherwise processed to achieve proper moisture content and then may be re-deposited directly back into the extruder.
The process and apparatus of the invention achieves many other manufacturing efficiencies. For example, prior art processes typically require complicated and costly compounding of powders for coating onto a fabric web. Those process steps are entirely unnecessary with preferred embodiments of the subject invention. Prior art processes also often require mixing of hot melts for application to a fabric web. The costs and time associated with mixing and applying the hot melt coating is avoided with preferred embodiments of the subject invention. Processes that involve saturating a fabric web also require large ovens for drying the fabric web. The ovens take up a substantial amount of floor space in a manufacturing facility and require significant amounts of energy to operate. In contrast, preferred embodiments of the subject process and apparatus may rely largely upon the heat imparted to the web as part of the extrusion process. Any reheating that may be required to soften the web prior to forming and cutting is less than the heat required for drying the saturated web. Hence, heaters used with the apparatus of the subject invention are preferably smaller and more energy efficient. Still further, the subject invention avoids the sheeting that is an integral part of prior art processes. In particular, the prior art webs are cut into rectangular sheets for shipment to a separate manufacturing facility. The sheets then are fed sequentially into a stamping apparatus. In contrast, the subject invention enables finished products to be formed and cut substantially simultaneously and directly from the web. The separate sheeting process is not required. Recycling also is much more efficient. Unused parts of the web can be recycled directly into the hopper of the extruder. Prior art processes typically must include a cryogenic grinding process or some other complex grinding process for the waste material.
An alternate apparatus and method in accordance with the invention avoids the initial formation and/or use of sheet material prior to making the profiled blanks. In this regard, the apparatus may include first and second rolls defining a nip therebetween. The first roll may have a smooth outer surface. The second roll, however, is formed with an array of inwardly directed die recesses corresponding to the specified shapes of the profiled blanks. Areas between their respective die recesses are disposed to substantially contact the smooth outer surface of the first roll at the nip between the first and second rolls. The apparatus of this embodiment is employed by depositing a flowable resin at the leading side of the nip between the rolls. Rotation of the rolls forces the resin into the die recesses in the second roll and hence forms the resin material into shapes corresponding to the specified profile for the blanks. Further rotation of the rolls moves the profiled blanks away from the nip and enables the blanks to be separated from the second roll and transported to an appropriate location for quality control, packaging and shipment to a customer.
The alternate apparatus may further include a retainer disposed in the interstice at the downstream side of the nip. The retainer has a shape substantially conforming to the shape of the interstice and functions to keep the flowable resin in the die recesses while the resin is curing sufficiently to be separated from the die recesses of the second roll. A specified flowability and curing can be achieved at appropriate times during the process by heating the first roll and/or by cooling the second roll and the retainer. The heating of the first roll helps to maintain flowability of the resin as the resin approaches the upstream side of the nip. The cooling of the second roll and the cooling of the retainer helps to cure the resin after the resin has been urged into the respective die recesses.
The apparatus and method of the alternate embodiment described above achieves all of the advantages of the first embodiment. However, the alternate embodiment offers still further advantages. In particular, the process of the alternate embodiment avoids the need and expense for an extruder that first forms a web of material. Rather, the resin is fed directly into the nip between the first and second rollers. Second, the alternate embodiment produces virtually no waste that would otherwise require recycling. In contrast, the first embodiment and the above-described prior art yield significant amounts of waste at locations on the web between the blanks that are cut according to the prior art process or roll formed according to the first embodiment.
An apparatus in accordance with a first embodiment of the invention is identified generally by the numeral 10 in
The web 24 produced by the extruder 12 is deposited onto a conveyor 26 that moves the web 24 away from the extruder. A heating station 28 is in proximity to the conveyor 26 and prevents the web 24 from curing and solidifying into its stiffened state. The heating station 28 may include an array of infrared heaters that function to maintain the resin web 24 in a semi-molten soft state and hence readily deformable in response to pressure thereon. However, the web 24 is not heated sufficiently to generate flow or dimensional changes in the absence of pressure. Hence, the thickness of the web 24 passing through the heating station 28 can be controlled.
The apparatus 10 further includes a forming and cutting station 30 substantially adjacent the downstream end of the heating station 28. The forming and cutting station 30 of the apparatus 10 includes a rotary forming and cutting die 32 as shown most clearly in
The die set 36 produces a blank 44, as shown in
The rotary cutting and forming die 32 shown in
The conveyor 26 extends downstream from the forming and cutting station 30 and then wraps around a drive roll 54. As a result, blanks 44 or other cut sections are deposited into an appropriate receptacle, while remaining portions of the web 24 are sent to a different receptacle for recycling.
The apparatus 60 further includes a forming and cutting station 80. In this embodiment, the forming and cutting station 80 includes a stamp forming and cutting press 82 that moves toward and away from the web 64 and in directions substantially perpendicular to the direction of movement of the web 64 along the conveyor 76. The stamp forming and cutting press 82 includes a plurality of die sets 84, each of which has a peripheral cutting edge 88 similar to the cutting edge 38 on the die sets 36 of the rotary forming and cutting die 32. The cutting edges 88 are dimensioned to pass completely through the web 64. Additionally, areas of each die set 84 bounded by the cutting edge 88 are configured to form a specified profile. In this regard, the cutting edge 88 may include a first section where an inner surface of the cutting edge 88 is aligned parallel to the direction of movement of the stamp forming and cutting press 82. However, a second section is aligned at an acute angle to the direction of movement of the stamp forming and cutting press 82 to form a chamfer 52 along at least one edge, as shown in
The portion of the apparatus 60 shown in
A further embodiment of an apparatus in accordance with the invention is identified generally by the numeral 90 in
As shown most clearly in
The alternate method illustrated in
This application relates to Provisional Patent Application No. 60/570,159 filed May 12, 2004 and Provisional Patent Application No. 60/577,962 filed on Jun. 8, 2004.
Number | Date | Country | |
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60570159 | May 2004 | US | |
60577962 | Jun 2004 | US |