Patent Publication Number: US-6711863-B2

Title: Edge cut to increase effective width of insulation sheet and method of forming the same

Description:
This application is a division of application Ser. No. 09/376,243, filed Aug. 8, 1999, now U.S. Pat. No. 6,378,258. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to fibrous and foam insulation sheets, such as but not limited to fibrous insulation batts or blankets for insulating wall, floor, ceiling and roof cavities and, in particular, to fibrous and foam insulation sheets which have lateral edges contoured to function, in combination with the flexibility, compressibility and resilience of the insulation sheets to increase the effective widths of the insulation sheets. When the insulation sheets are placed in a cavity, the increased effective widths of the insulation sheets increases the forces exerted on the lateral edges of the insulation sheets by the opposed surfaces of the framing members defining the cavity to better retain the insulation sheets within the cavity. 
     Fibrous insulation sheets, batts or blankets, such as but not limited to glass fiber insulation batts or blankets, foam insulation sheets or similar insulation batts, blankets or sheets which are flexible, compressible and resilient, are commonly used as an insulation to insulate wall, floor, ceiling and roof cavities of residential, commercial, and industrial buildings. The lengths, widths, and depths of these building cavities are standardized throughout the building industry and are defined by the framing members used in the walls, floors, ceilings and roofs of the buildings. For example, the vertical framing members in the walls of residential building construction are normally standard 2×4 or 2×6 wooden studs which are located on 16 inch or 24 inch centers and form wall cavities having widths of about 14 ½ and 22 ½ inches. The commercially available fibrous insulation batts or blankets used to insulate these wall cavities are both compressible and resilient and are made to standard nominal widths of 15 inches and 23 inches, respectively. The compressibility of the fibrous insulation batts or blankets, which are greater in width than the cavities being insulated, enables the batts or blankets to be placed within the cavities and the resilience of the batts or blankets which exert forces against the surfaces of framing members helps to maintain the insulation batts or blankets in place within the cavities prior to enclosing the cavities with boards, wall boards or similar construction materials. 
     While this method of maintaining the insulation sheets, batts or blankets in place within the cavities prior to putting up the wall board or similar construction materials generally works satisfactorily, sometimes the forces exerted on a sheet, batt or blanket by the framing members to maintain the insulation sheet, batt or blanket in place is insufficient to maintain the insulation sheet, batt or blanket in place. Thus, there has remained a need to better retain the insulation sheets, batts or blankets within the cavities prior to putting up the wall board or similar construction materials to enclose the cavity. 
     SUMMARY OF THE INVENTION 
     The fibrous or foam insulation sheet, batt or blanket and method of the present invention provide a means for better retaining a flexible, compressible and resilient insulation sheet, batt or blanket within a wall, floor, ceiling or roofing cavity by contouring the lateral edges of the insulation sheet, batt or blanket to increase the effective width of the insulation sheet, batt or blanket without increasing the amount of insulation used in the sheet, batt or blanket. More specifically, the insulation sheet, batt or blanket of the present invention has contoured lateral edges which are: a) serpentine, b) inclined at an angle other than perpendicular to the major surfaces of the sheet, batt or blanket, or c) a combination of serpentine and inclined at an angle other than perpendicular to the major surfaces of the sheet, batt or blanket, along the lengths of the lateral edges of the sheet, batt or blanket. These contoured lateral edges increase the effective width of the insulation sheet, batt or blanket relative to a conventional insulation sheet, batt or blanket of the same length, width, thickness and density with straight lateral edges extending perpendicular between major surfaces of the conventional insulation sheet without increasing the amount of insulation material used in the insulation sheet, batt or blanket. 
     As used in this specification and claims in connection with insulation sheets, batts and blankets, the term “width” means the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces of the insulation sheet, batt or blanket) between the lateral edges of an insulation sheet, batt or blanket for any and all planes, passing through the insulation sheet, batt or blanket, that are parallel to the major surfaces of the insulation sheet, batt or blanket. 
     As used in this specification and claims in connection with insulation sheets, batts and blankets, the term “effective width” means the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces of the insulation sheet, batt or blanket) between two parallel or substantially parallel planes extending perpendicular to the major surfaces of the insulation sheets, batts or blankets which planes meet or are tangential to the lateral edges of the insulation sheets, batts or blankets along the lengths of the lateral edges at the farthest lateral projections of the lateral edges. 
     In the embodiment of the present invention where the lateral edges of the insulation sheet, batt or blanket have generally serpentine contours throughout the lengths of the lateral edges and the lateral edges extend generally parallel with respect to each other throughout the lengths of the lateral edges, a transverse vertical cross section through the insulation sheet, batt or blanket may be shaped generally like a rectangle or a parallelogram with no included right angles. In the embodiment of the present invention where the lateral edges of the insulation sheet, batt or blanket are inclined at an angle other than perpendicular to the major surfaces of the insulation sheet, batt or blanket throughout the lengths of the lateral edges, a transverse vertical cross section through the insulation sheet, batt or blanket is shaped generally like a parallelogram having no included right angles In another embodiment of the present invention, the lateral edges of the insulation sheet, batt or blanket are substantially straight at one major surface of the sheet, serpentine at the other major surface of the sheet, and the angles of the lateral edges relative to the major surfaces of the sheet periodically vary along the length of the lateral edges from inclined at a negative angle to the perpendicular (the perpendicular between the major surfaces), to perpendicular, to inclined at a positive angle to the perpendicular, to perpendicular, to inclined at a negative angle to the perpendicular. 
     With the contours of the lateral edges of the insulation Ad sheet, batt or blanket of the present invention there is no or substantially no increase in the amount of insulation material forming the insulation sheet, batt or blanket of the present invention relative to the insulation material used in a conventional insulation sheet, batt or blanket of the same length, width, thickness and density with straight lateral edges extending perpendicular between major surfaces of the insulation sheet, batt or blanket. However, with the increase in the effective width of the insulation sheet, batt or blanket of the present invention, when the insulation sheet, batt or blanket is placed in a cavity the forces exerted on the lateral edges of the insulation sheet, batt or blanket by the opposed surfaces of the framing members are increased to better retain the insulation sheet, batt or blanket within the cavity. 
     In a first embodiment of the method of forming the contoured edges on the insulation sheets, batts or blankets of the present invention, the contoured edges are formed by cutting an insulation sheet with a series of spaced apart cutting blades that are reciprocally oscillated with respect to the insulation sheet in a direction transverse to a longitudinal centerline of the insulation sheet as the insulation sheet is fed past the cutting blades. The reciprocal oscillation of the blades, as the insulation sheet is fed past the blades, forms a plurality of sheets, batts or blankets with serpentine lateral edges that extend generally parallel with respect to each other. 
     In a second embodiment of the method of forming the contoured edges on the insulation sheets, batts or blankets of the present invention, the contoured edges are formed by cutting an insulation sheet with a series of stationary, spaced apart cutting blades that are positioned across the width of the insulation sheet. The cutting blades are inclined at an angle other than perpendicular to the major surfaces of the insulation sheet and as the insulation sheet is fed past the cutting blades, a plurality of sheets, batts or blankets are formed with lateral edges inclined at angles other than perpendicular to the major surfaces of the insulation sheets throughout the lengths of the lateral edges. The insulation sheets, batts or blankets formed have a transverse vertical cross section that is shaped generally like a parallelogram having no included right angles. 
     In a third embodiment of the method of forming the contoured edges on the insulation sheets, batts or blankets of the present invention, the contoured edges are formed by cutting an insulation sheet with a series of stationary, spaced apart cutting blades that are positioned across the width of the insulation sheet. While the spaced apart cutting blades are maintained in fixed positions relative to the insulation sheet in a direction transverse to a longitudinal centerline of the insulation sheet as the insulation sheet is fed through the cutting station, the cutting blades of the cutting means, which are maintained parallel with respect to each other, are moved synchronously back and forth between a negative angle to the perpendicular between the major surfaces of the insulation sheet and appositive angle to the perpendicular between the major surfaces of the insulation sheet. This method of cutting the insulation sheet forms a plurality of insulation sheets with lateral contoured edges that extend generally parallel with respect to each other. The lateral edges are substantially straight at a first major surface throughout the lengths of the lateral contoured edges and are generally serpentine at a second major surface throughout the lengths of the lateral contoured edges. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1-3 are schematic top, side and end views of a typical prior art insulation sheet for insulating a wall, floor, ceiling or roof cavity of a building. 
     FIGS. 4-6 are schematic top, side and end views of a first embodiment of the insulation sheet of the present invention for insulating a wall, floor, ceiling or roof cavity of a building. 
     FIGS. 7-9 are schematic top, side and end views of a second embodiment of the insulation sheet of the present invention for insulating a wall, floor, ceiling or roof cavity of a building. 
     FIG. 10 is a schematic end view of the insulation sheets of FIGS. 7-9 and  11 - 13 , in a larger scale, to better illustrate the included angles of the insulation sheet in transverse cross section. 
     FIGS. 11-13 are schematic top, side and end views of a third embodiment of the insulation sheet of the present invention for insulating a wall, floor, ceiling or roof cavity of a building. 
     FIGS. 14-15 are schematic top and side views of a fourth embodiment of the insulation sheet of the present invention for insulating a wall, floor, ceiling or roof cavity of a building. 
     FIGS. 16-18 are schematic transverse cross sectional views of the insulation sheet of FIGS. 14 and 15 taken substantially along lines  16 — 16 ,  17 — 17  and  18 — 18  of FIG.  14 . 
     FIGS. 19 and 20 are schematic top and side views of an apparatus for forming the insulation sheets of the present invention. 
     FIG. 21 is a top view of an insulation sheet cut into a series of insulation sheets such as the insulation sheets illustrated in FIGS. 4-6. 
     FIG. 22 is a schematic vertical end view of one of a series of saw blades positioned relative to each other as shown in FIG. 20 but inclined to cut an insulation sheet into a series of insulation sheets such as the insulation sheets illustrated in FIGS. 7-9. 
     FIG. 23 is a top view of an insulation sheet cut into a series of insulation sheets such as the insulation sheets illustrated in FIGS. 7-9. 
     FIG. 24 is a top view of an insulation sheet cut into a series of insulation sheets such as the insulation sheets illustrated in FIGS. 11-13. 
     FIG. 25 is a schematic vertical end view of one of a series of saw blades positioned relative to each other as shown in FIG. 20 but being moved back and forth between a negative incline and a positive incline relative to the vertical to cut an insulation sheet into a series of insulation sheets such as the insulation sheets illustrated in FIGS. 14-18. 
     FIG. 26 is a top view of an insulation sheet cut into a series of insulation sheets such as the insulation sheets illustrated in FIGS.  14 - 18 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-3 show a conventional fibrous or foam insulation sheet  20  for insulating the wall, floor, ceiling and roof cavities of buildings and similar structures. Typically, the insulation sheets  20  are made of fibrous materials such as but not limited to mineral fiber insulation sheets, batts and blankets (e.g. glass, mineral wool), and foam materials such as but not limited to polyimide or polyamide foam insulation sheets. The insulation sheet  20  typically comes in various lengths and thickness, such as but not limited to lengths ranging from about 8 feet to about 100 feet and thickness ranging from about 3 inches to about 6 ½ inches. Since the lateral edges 22 and 24 of the insulation sheet  20  are parallel with respect to each other and extend perpendicular to the major surfaces  26  and  28  of the insulation sheet  20 , the width “W” of the insulation sheet and the effective width “EW” of the insulation sheet  20  are the same. These insulation sheets typically range from about 10 inches to about 24 inches in width with insulation sheets about 15 inches wide and about 23 inches wide being the most common. 
     FIGS. 4-18 show fibrous or foam insulation sheet  120 ,  220 ,  320  and  420  for insulating the wall, floor, ceiling and roof cavities of buildings and similar structures. Typically, the insulation sheets  120 ,  220 ,  320  and  420  are made of fibrous materials such as but not limited to mineral fiber insulation sheets, batts and blankets, and foam materials such as but not limited to polyimide or polyamide foam insulation sheets. The insulation sheets typically come in various lengths and thickness, such as but not limited to lengths ranging from about 8 feet to about 100 feet and thickness ranging from about 3 inches to about 6 ½ inches. 
     The insulation materials forming the insulation sheets  120 ,  220 ,  320  and  420 , such as mineral fiber insulation batts or blanket or foam insulation sheets must be flexible, compressible and resilient. The insulation sheets  120 ,  220 ,  320  and  420  formed from the insulation materials must also be flexible, compressible and resilient so that when an insulation sheet  120 ,  220 ,  320  or  420  is placed between the opposed surfaces of the generally parallel extending framing members defining the width of a wall, floor, ceiling or roof cavity, the insulation sheet can flex and compress or deform along its length to conform the lateral edges of the insulation sheet to the surfaces of cavity sidewalls defined by the opposed surfaces of the framing members and resiliently press against the opposed surfaces of the framing members to hold the insulation sheet in place by the opposing forces exerted on the insulation sheet by framing members. In addition, since the lateral edges of the insulation sheets  120 ,  220 ,  320  and  420  are contoured or shaped to increase the effective widths “EW” of the insulation sheets relative to the widths “W” of the insulation sheets  120 ,  220 ,  320  and  420  and cross sections of the insulations sheets taken anywhere along the lengths of the insulation sheets in planes extending perpendicular to both the major surfaces and the parallel edges of the insulation sheets are rectangles or parallelograms, the effective widths “EW” of the insulation sheets  120 ,  220 ,  320  and  420  are increased to more effectively maintain the insulation sheets within wall, floor, ceiling and roof cavities without increasing the amount of insulation material used in the insulation sheets. 
     By way of example, in a wall cavity used in residential construction the distance between the opposed surfaces of the framing members defining the widths of the cavities is typically about 14 ½ or about 22 ½ inches and the widths “W” as well as the effective widths “EW” of the conventional insulation sheets  20  used to insulate such cavities are typically about 15 and 23 inches respectively. Since the widths “W” as well as the effective widths “EW” of the insulation sheets are about ½ inch greater than the cavity widths, the forces between the lateral edges of the insulation sheets and the sidewalls of the cavities, generated by the resilience of the ½ inch of resilient insulation material, act to maintain the insulation sheets in place during construction. With the insulation sheets of the present invention (sheets  120 ,  220 ,  320  and  420 ), the effective widths “EW” of the insulation sheets can be easily increased, e.g. by another ½ inch to an inch or more, without increasing the amount of insulation material in the sheets to increase the forces maintaining the insulation sheets in place. 
     In the insulation sheet  120  of FIGS. 4-6, the lateral edges  122  and  124  of the insulation sheet, batt or blanket have generally serpentine contours throughout the lengths of the lateral edges and the lateral edges  122  and  124  extend parallel or substantially parallel with respect to each other throughout the lengths of the lateral edges. In addition, the lateral edges are perpendicular or substantially perpendicular to the major surfaces  126  and  128  of the insulation sheet  120  and a transverse vertical cross section through the insulation sheet, batt or blanket is shaped generally like a rectangle. 
     As best shown in FIG. 4, due to the serpentine contour of the lateral edges  122  and  124 , the effective width “EW” of the insulation sheet  120  [the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces  126  and  128  of the insulation sheet  120 ) between two parallel or substantially parallel planes extending perpendicular to the major surfaces of the insulation sheet which planes meet or are tangential to the lateral edges  126  and  128  of the insulation sheet along the lengths of the lateral edges at the farthest lateral projections  130  and  132  of the lateral edges] is greater than the width “W” of the insulation sheet [the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces  126  and  128  of the insulation sheet  120 ) between the lateral edges  122  and  124  of an insulation sheet for any and all planes, passing through the insulation sheet  120 , that are parallel to the major surfaces of the insulation sheet. Desirably, the distance between a lateral projection  130  and the next succeeding lateral projection  130  along the lateral edge  122  and a lateral projection  132  and the next succeeding lateral projection  132  along the lateral edge  124  each ranges from about 2 to about 4 feet. 
     In the insulation sheet  220  of FIGS. 7-9, the lateral edges  222  and  224  of the insulation sheet, batt or blanket have generally serpentine contours throughout the lengths of the lateral edges and the lateral edges  222  and  224  extend parallel or substantially parallel with respect to each other throughout the lengths of the lateral edges. In addition, the lateral edges are inclined at an angle to the perpendicular to the major surfaces  226  and  228  of the insulation sheet  220  and a transverse vertical cross section through the insulation sheet is shaped generally like a parallelogram having no included right angles. As best shown in FIG. 7, due to the serpentine contour of the lateral edges  222  and  224  and the incline of the lateral edges  222  and  224  relative to the perpendicular to the major surfaces  226  and  228  of the insulation sheet, the effective width “EW” of the insulation sheet  220  [the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces  226  and  228  of the insulation sheet  220 ) between two parallel or substantially parallel planes extending perpendicular to the major surfaces of the insulation sheet which planes meet or are tangential to the lateral edges  226  and  228  of the insulation sheet along the lengths of the lateral edges at the farthest lateral projections  230  and  232  of the lateral edges] is greater than the width “W” of the insulation sheet [the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces  226  and  228  of the insulation sheet  220 ) between the lateral edges  222  and  224  of an insulation sheet for any and all planes, passing through the insulation sheet  220 , that are parallel to the major surfaces of the insulation sheet. Due to the inclination of the lateral edges  222  and  224  to the perpendicular, the farthest lateral projections  230  along lateral edge  222  occur where the lateral edge  222  meets the major surface  228  of the insulation sheet and the farthest lateral projections  232  along lateral edge  224  occur where the lateral edge meets the major surface  226 . Desirably, the distance between a lateral projection  230  and the next succeeding lateral projection  230  along the lateral edge  222  and a lateral projection  232  and the next succeeding lateral projection  232  along the lateral edge  224  each ranges from about 2 to about 4 feet. 
     As best shown in FIG. 10, the included angles “a” and “b” between the lateral edges  222  and  224  and the major surfaces  226  and  228  in a transverse cross section of the insulation sheet  220  are other than right angles with the included angles “a” being acute angles and the included angles “b” being obtuse angles. Desirably, the angles “a” range from about 60° to about 85° and the angles “b” range from about 95° to about 120°. 
     In the insulation sheet  320  of FIGS. 11-13, the lateral edges of the insulation sheet, batt or blanket are inclined at an angle to the perpendicular to the major surfaces  326  and  328  of the insulation sheet and are parallel with respect to each other throughout the lengths of the lateral edges  322  and  324 . In addition, a transverse cross section through the insulation sheet perpendicular to the major surfaces of the insulation sheet is shaped generally like a parallelogram having no included right angles. As best shown in FIG. 11, due to the incline of the lateral edges  322  and  324  relative to the perpendicular to the major surfaces  326  and  328  of the insulation sheet, the effective width “EW” of the insulation sheet  320  [the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces  326  and  328  of the insulation sheet  320 ) between two parallel or substantially parallel planes extending perpendicular to the major surfaces of the insulation sheet which planes meet the lateral edges  326  and  328  of the insulation sheet along the lengths of the lateral edges at the farthest lateral projections  330  and  332  of the lateral edges] is greater than the width “W” of the insulation sheet [the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces  326  and  328  of the insulation sheet  320 ) between the lateral edges  322  and  324  of an insulation sheet for any and all planes, passing through the insulation sheet  320 , that are parallel to the major surfaces of the insulation sheet. Due to the inclination of the lateral edges  322  and  324  to the perpendicular, the farthest lateral projection  330  along lateral edge  322  occurs where the lateral edge  322  meets the major surface  328  of the insulation sheet and the farthest lateral projection  332  along lateral edge  324  occurs where the lateral edge meets the major surface  326 . 
     As with the transverse cross section of insulation sheet  220 , the included angles “a” and “b” between the lateral edges  322  and  324  and the major surfaces  326  and  328  in a transverse cross section of the insulation sheet  320  are other than right angles with the included angles “a” being acute angles and the included angles “b” being obtuse angles. Desirably, the angles “a” range from about 60° to about 85° and the angles “b” range from about 95° to about 120°. 
     In the insulation sheet  420  of FIGS. 14-18, the lateral edges  422  and  424  of the insulation sheet, batt or blanket are substantially straight and parallel with respect to each other at one major surface  428  of the sheet, serpentine and parallel with respect to each other at the other major surface  426  of the sheet, and the angles of the lateral edges  422  and  424  relative to the major surfaces  426  and  428  of the sheet periodically vary along the length of the lateral edges from inclined at a negative angle to the perpendicular (the perpendicular between the major surfaces), to perpendicular, to inclined at a positive angle to the perpendicular, to perpendicular, to inclined at a negative angle to the perpendicular. FIGS. 16-18 are transverse cross sections of the insulation sheet  420 , extending perpendicular to the major surfaces of the insulation sheet, at different locations along the length of the insulation sheet. FIG. 16 shows the lateral edges  422  and  424  inclined at a negative angle of desirably up to about 30° to the perpendicular between the major surfaces  426  and  428  of the insulation sheet. FIG. 17 shows the lateral edges  422  and  424  inclined perpendicular to the major surfaces  426  and  428  of the insulation sheet. FIG. 18 shows the lateral edges  422  and  424  inclined at a positive angle of desirably up to about 30° to the perpendicular between the major surfaces  426  and  428  of the insulation sheet. Thus, along the length of the insulation sheet  420 , the transverse cross section of the insulation sheet  420  passes from a parallelogram with no included right angles when the lateral edges are inclined at a negative angle (FIG.  16 ), to a rectangle (FIG.  17 ), to a parallelogram with no included right angles when the lateral edges are inclined at a positive angle (FIG.  18 ), back to a rectangle (FIG.  17 ), etc. The included angles between the lateral edges  422  and  424  and the major surfaces  426  and  428  in the transverse cross sections of the insulation sheet shown in FIGS. 16 and 18 are other than right angles with the included acute angles preferably ranging from about 60° to about 85° and the included obtuse angles preferably ranging from about 95° to about 120°. 
     As best shown in FIG. 14, due to the serpentine contour of the lateral edges  422  and  424  where the lateral edges meet the major surface  426 , the effective width “EW” of the insulation sheet  420  [the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces  426  and  428  of the insulation sheet  420 ) between two parallel or substantially parallel planes extending perpendicular to the major surfaces of the insulation sheet which planes meet or are tangential to the lateral edges  426  and  428  of the insulation sheet along the lengths of the lateral edges at the farthest lateral projections  430  and  432  of the lateral edges] is greater than the width “W” of the insulation sheet [the perpendicular distance (as measured along a straight line in a plane parallel to the major surfaces  426  and  428  of the insulation sheet  420 ) between the lateral edges  422  and  424  of an insulation sheet for any and all planes, passing through the insulation sheet  420 , that are parallel to the major surfaces of the insulation sheet. Desirably, the distance between a lateral projection  430  and the next succeeding lateral projection  430  along the lateral edge  422  and a lateral projection  432  and the next succeeding lateral projection  432  along the lateral edge  424  each ranges from about 2 to about 4 feet. 
     FIGS. 19 and 20 are schematic plan and side views of a cutting station  40  for forming the insulation sheets  120 ,  220 ,  320  and  420  by the method of the present invention. The cutting station includes support surfaces  42  and  44  for supporting an insulation sheet  46  as the insulation sheet is passed through the cutting station  40  and a series of cutting blades  48  positioned across the width of the cutting station in a direction perpendicular to the movement of, the insulation sheet  46  through the cutting station  40 . Successive cutting blades  48  of the series of cutting blades are equally spaced from each other across the width of the cutting station to form a series of insulation sheets  120 ,  220 ,  320  or  420  of equal width. While, as shown, the cutting blades  48  are circular rotary saw blades, other forms of cutting blades can be used such as but not limited to band saw blades. 
     In a first embodiment of the method of forming the contoured edges on the insulation sheets  120  of the present invention, the contoured edges  122  and  124  are formed by cutting the insulation sheet  46  with the series of spaced apart cutting blades  48  by reciprocally oscillating the cutting blades  48  back and forth with respect to the insulation sheet  46  in a direction transverse to a longitudinal centerline of the insulation sheet as the insulation sheet is fed past the cutting blades  48 . In this embodiment of the method of the present invention, the saw blades  48  are oriented perpendicular to the upper major surface of the insulation sheet  46  and the lateral edges  122  and  124 , formed on the insulation sheets  120  made from the insulation sheet  46 , extend perpendicular to the major surfaces of the insulation sheet  46 . As shown in FIG. 21, the reciprocal oscillation of the cutting blades  48 , as the insulation sheet  46  is fed past the cutting blades  48 , forms serpentine lateral edges  122  and  124  on the insulation sheets  120  that extend parallel or generally parallel with respect to each other for the length of the insulation sheets  120 . The length of the transverse movement of the cutting blades is determined by the increase desired in the effective width of the insulation sheets  120 . However, by way of example, when forming a series of 15 inch or 23 inch wide insulation sheets  120  for insulating wall cavities, the cutting blades  48  would be moved transversely from about ½ inch to about 1 inch to increase the effective widths “EW” of the insulation sheets to about 15 ½-16 inches or 23 ½-24 inches respectively with the reciprocal motion of the saw blades being repeated for every 2 to 4 feet of movement of the insulation sheet  46  past the saw blades. The effective widths “EW” of insulation sheets of other widths, e.g. widths ranging from about 10 inches to about 24 inches, can also be increased in a like manner. 
     As shown in FIG. 21, the outermost insulation sheets  120   a  and  120   b  formed from the insulation sheet  46  by this process would have one straight edge and one serpentine edge. Since the serpentine edges are only on one side of each of these outer sheets, the effective widths “EW” of these two outermost insulation sheets  120   a  and  120   b  would be the same as the widths “W” of the inner insulation sheets  120 . However, by making the insulation sheet  46  “X” of an inch wider on each side as shown in FIG. 21, e.g. increasing the width of the insulation sheet by ¼ to ½ inch on each side, the effective widths “EW” of the outermost insulation sheets  120   a  and  120   b  can also be increased. 
     The method for forming the insulation sheets  220  of the present invention is essentially the same as the method for forming the insulation sheets  120  with one exception. The saw blades  48 , as shown in FIG. 22, are each inclined at the same angle to the perpendicular to the major surfaces of the insulation sheet  46 . Thus, the lateral edges  222  and  224  formed on the insulation sheets  220  by cutting the insulation sheet  46  are inclined at angles other than the perpendicular to the major surfaces of the insulation sheets  220 . By combining the formation of inclined lateral edges with the formation of the serpentine lateral edges, the effective widths “EW” of the insulation sheets are determined by both the inclination of the saw blades and the degree of transverse movement of the saw blades. As with the insulation sheets  120   a  and  120   b , the outermost insulation sheets  220   a  and  220   b  can have their effective widths increased by increasing the width of the insulation sheet  46  increased by “X” of an inch on each side. 
     In another embodiment of the method of forming the contoured edges on the insulation sheets  320  of the present invention, the contoured edges  322  and  324  are formed by cutting the insulation sheet  46  with the series spaced apart cutting blades  48 . However, in this embodiment of the method, the cutting blades  48  are maintained in a stationary position across the width of the insulation sheet  46  and are inclined at an angle other than the perpendicular to the major surfaces of the insulation sheet  46 . As the insulation sheet  46  is fed past the inclined cutting blades  48 , a plurality of sheets  320  are formed (as shown in FIG. 24) with lateral edges  322  and  324  inclined at angles other than the perpendicular to the major surfaces of the insulation sheets throughout the lengths of the lateral edges. As with the insulation sheets  120   a  and  120   b , the outermost insulation sheets  320   a  and  320   b  can have their effective widths increased by increasing the width of the insulation sheet  46  increased by “X” of an inch on each side. 
     In another embodiment of the method of forming the contoured edges on the insulation sheets  420  of the present invention, the contoured edges  422  and  424  are formed by cutting the insulation sheet with the series of spaced apart cutting blades  48 . The saw blades  48  are maintained in stationary or fixed positions across the width of the insulation sheet  46  as the insulation sheet is fed through the cutting station  40 . However, as schematically shown with respect to a single saw blade in FIG. 25, the cutting blades  48 , which are maintained parallel with respect to each other, are moved synchronously back and forth from a negative angle to the perpendicular between the major surfaces of the insulation sheet, to the perpendicular, a positive angle to the perpendicular between the major surfaces of the insulation sheet, back to the perpendicular, and so forth. This method of cutting the insulation sheet  46  forms a plurality of insulation sheets  420  with lateral contoured edges  422  and  424  that extend parallel or generally parallel with respect to each other. The lateral edges  422  and  424  are substantially straight at a first major surface throughout the lengths of the lateral contoured edges and are generally serpentine at a second major surface throughout the lengths of the lateral contoured edges. As with the insulation sheets  120   a  and  120   b , the outermost insulation sheets  420   a  and  420   b  (only  420   b  is shown) can have their effective widths increased by increasing the width of the insulation sheet  46  increased by “X” of an inch on each side. 
     In describing the invention, certain embodiments have been used to illustrate the invention and the practices thereof. However, the invention is not limited to these specific embodiments as other embodiments and modifications within the spirit of the invention will readily occur to those skilled in the art on reading this specification. Thus, the invention is not intended to be limited to the specific embodiments disclosed, but is to be limited only by the claims appended hereto.