Method and apparatus for uniformly debossing and aperturing a resilient plastic web

Claim 1

A method for constructing a forming cylinder for imparting an uninterrupted, uniformly apertured three-dimensional pattern to a heated plastic film subjected to a fluid pressure differential while in contact with its surface, said method comprising the steps of: (a) forming substantially continuous patterns of apertures in a multiplicity of planar sheets, at least a portion of said sheets having aperture patterns in which the apertures at least to a degree coincide from one sheet to another, at least a portion of said coinciding apertures being dissimilar in size from one lamina to another; (b) superposing said sheets having said patterns of coinciding, dissimilarly sized apertures upon one another to form a three-dimensional stack having a greater overall thickness than the maximum depth to which said film is drawn when subjected to said fluid pressure differential, said stack further exhibiting a three-dimensional continuum of capillary networks, each of said capillary networks placing the uppermost and lowermost surfaces of said stack in exclusive fluid communication with one another, each of said capillary networks having a cross-sectional area which varies in size intermediate the uppermost and lowermost surfaces of said stack, said cross-sectional area reaching a minimum at a point located intermediate said uppermost and lowermost surfaces of said stack and thereafter increasing in the direction of the lowermost surface of said stack; (c) bonding said superposed stack of sheets to one another at contact points to form an integral laminate structure; (d) causing the uppermost surface of said laminate structure to assume a radius of curvature greater than that of said lowermost surface of said laminate structure without causing delamination thereof, thereby causing said laminate structure to assume a substantially tubular shape having an outermost surface corresponding to the uppermost surface of said stack and an innermost surface corresponding to the lowermost surface of said stack; (e) securing the opposing free edges of said tubular shaped laminate structure to one another while maintaining substantial continuity of said three-dimensional continuum of capillary networks about the entire periphery of the tubular member thus formed; and (f) supporting the innermost surface of said tubular laminate structure on a multiplicity of support members, each of said support members having a land which contacts the innermost surface of said tubular laminate structure, the width of said lands being insufficient to completely obstruct said capillary networks at their points of contact with the innermost surface of said tubular laminate structure, whereby said outermost and said innermost surfaces of said tubular laminate structure are maintained in fluid communication with one another about the periphery of said tubular structure.

Claim 2

A method for constructing a forming cylinder for imparting an uninterrupted, uniformly apertured three-dimensional pattern to a heated plastic film subjected to a fluid pressure differential while in contact with its surface, said method comprising the steps of: (a) forming substantially continuous patterns of apertures in a multiplicity of planar sheets, at least a portion of said sheets having aperture patterns in which the apertures at least to a degree coincide from one sheet to another, at least a portion of said coinciding apertures being dissimilar in size from one lamina to another; (b) superposing said sheets having said patterns of coinciding, dissimilarly sized apertures upon one another to form a three-dimensional stack having a greater overall thickness than the maximum depth to which said film is drawn when subjected to said fluid pressure differential, said stack further exhibiting a three-dimensional continuum of capillary networks, each of said capillary networks placing the uppermost and lowermost surfaces of said stack in exclusive fluid communication with one another, each of said capillary networks having a cross-sectional area which varies in size intermediate the uppermost and lowermost surfaces of said stack, said cross-sectional area reaching a minimum at a point located intermediate said uppermost and lowermost surfaces of said stack and thereafter increasing in the direction of the lowermost surface of said stack; (c) bonding said superposed stack of sheets to one another at contact points to form an integral laminate structure; (d) causing the uppermost surface of said laminate structure to assume a radius of curvature greater than that of said lowermost surface of said laminate structure without causing delamination thereof, thereby causing said laminate structure to assume a substantially tubular shape having an outermost surface corresponding to the uppermost surface of said stack and an innermost surface corresponding to the lowermost surface of said stack; (e) securing the opposing free edges of said tubular shaped laminate structure to one another while maintaining substantial continuity of said three-dimensional continuum of capillary networks about the entire periphery of the tubular member thus formed; and (f) supporting the innermost surface of said tubular laminate structure on a multiplicity of support members, each of said support members having a land which contacts the innermost surface of said tubular laminate structure, the width of said lands being insufficient to completely obstruct said capillary networks at their points of contact with the innermost surface of said tubular laminate structure, whereby said outermost and said innermost surfaces of said tubular laminate structure are maintained in fluid communication with one another about the periphery of said tubular structure.