Corner protector attachment method and apparatus for frames having non-rectangular cross-section moldings

Abstract

A method and apparatus for bending a flat cardboard preform into a corner protector that encloses and protects a corner of a picture frame from impact damage during shipping and handling of the frame includes positioning symmetrically between the corner and preform a thin, wedge-shaped template plate having a forwardly protruding, right-triangularly shaped vertex angle. Bending motion of corner protector cover flap sections upward from the plane of the preform is limited by contact of the flap sections with edges of the template plate to perpendicular positions relative to the plane of the preform, thus assuring that channel-shaped protective covers for sides of the frames formed by subsequent inwardly and downwardly bending of upper end portions of the flap sections to overlie a face surface of the frame will have rectangular cross sections, even if the sides of the frame are non-rectangular, e.g., angled or contoured.

What is claimed is:  
     
         1 . A method for attaching a protective cover to a corner of a frame having front and rear face surfaces, said corner being formed by an intersection at a dihedral frame angle of two adjacent frame moldings comprising two adjacent sides of said frame, each of said frame moldings having an outer side which intersects said front and rear surfaces of said frame at arbitrary front and rear molding angles in a transverse cross sectional view, said method comprising; 
 a. placing said frame corner front face down over a flat corner protector preform comprising a thin sheet of flexible material, said sheet being bendable into a plurality of flaps to enclose portions of said front and rear frame surfaces and said sides of said moldings adjacent to said frame corner,    b. positioning a thin template plate having a vertex angle congruent with said dihedral frame corner angle between said preform and said frame corner with intersecting sides of said template forming said vertex thereat in congruent alignment with said rear side edges of said frame moldings intersecting to form said frame corner,    c. bending from a horizontal plane of said preform first and second, vertically disposed flap sections which contact said first and second edges, respectively, of said template,    d. bending an upper part of each of said first and second flap sections perpendicularly inwards to a horizontal disposition overlying said rear surface of said frame, and    e. securing said overlying parts of said flap sections to each other and to said rear surface of said frame.    
     
     
         2 . The method of  claim 1  wherein at least a part of said outer side of said frame molding is further defined as being obliquely angled with respect to said front and rear surfaces of said frame.  
     
     
         3 . The method of  claim 1  wherein at least a part of said outer side of said frame molding is further defined as being contoured.  
     
     
         4 . The method of  claim 1  wherein said plan view dihedral frame corner angle is further defined as being substantially a right angle.  
     
     
         5 . The method of  claim 4  wherein said preform is further defined as having a first, right triangularly-shaped lower, front face cover flap, the sides of which are vertically aligned with said edges of said template and said rear side edges of said intersecting moldings.  
     
     
         6 . The method of  claim 5  wherein said preform is further defined as including a first, rectangularly-shaped, pendent side cover flap which protrudes outwardly from a horizontal base side of said lower right triangularly-shaped, front face cover flap.  
     
     
         7 . The method of  claim 6  wherein said first, pendent side cover flap is bent perpendicularly up from the plane of said preform to lodge vertically against a first edge of said template plate and a rear edge of a first molding of said frame.  
     
     
         8 . The method of  claim 7  wherein said preform is further defined as having a securement flap which protrudes outwardly from an outer horizontal edge of said pendent side cover flap parallel to said base of said triangularly-shaped lower face cover flap, said securement flap having an outer perimeter edge parallel to said base and said outer horizontal edge of said pendent side cover flap.  
     
     
         9 . The method of  claim 8  wherein said securement flap is bent perpendicularly downwards and inwards towards said first frame molding along a securement flap fold line coincident with said outer horizontal edge of said pendent side cover flap, to overlie a portion of said rear face of said first molding.  
     
     
         10 . The method of  claim 9  wherein said securing step includes fastening said securement flap to an upper facing rear surface of said first molding.  
     
     
         11 . The method of  claim 10  wherein said securement flap is further defined as having an outer perimeter edge parallel to but shorter than said securement flap fold line, thereby giving said securement flap a horizontally elongated, trapezoidal shape.  
     
     
         12 . The method of  claim 9  wherein said preform is further defined as including a second, rectangularly-shaped, vertically elongated spine side cover flap which depends outwardly from a vertical altitude side of said lower triangularly-shaped front face cover flap.  
     
     
         13 . The method of  claim 12  wherein said second, spine edge cover flap is bent perpendicularly upwards from the plane of said preform along said altitude edge of said preform to lodge vertically against a second edge of said template plate and a rear edge of a second molding of said frame.  
     
     
         14 . The method of  claim 13  wherein said preform is further defined as having a second, upper right-triangularly-shaped, rear face cover flap which protrudes outwards from an outer vertical joint edge of said spine edge cover flap parallel to said altitude side of said triangularly-shaped lower face cover flap.  
     
     
         15 . The method of  claim 14  wherein said upper triangularly-shaped rear face cover flap is bent perpendicularly downwards along said outer vertical joint line with said spine edge cover flap to overlie a portion of said rear face of said frame including portions of said first and second moldings.  
     
     
         16 . The method of  claim 15  wherein said securing step includes fastening said upper triangular cover flap to an upper surface of said securement flap.  
     
     
         17 . An apparatus for attaching a protective cover to a corner of frame having front and rear face surfaces, said corner being formed by an intersection at a dihedral frame corner angle of two adjacent, first and second frame moldings comprising two adjacent, first and second sides of said frame, each of said frame moldings having an outer side which intersects said front and rear surfaces of said frame at arbitrary front and rear molding angles, respectively, said protective cover being made from a preform composed of a thin sheet of flexible material, said apparatus comprising; 
 a. means for positioning a template plate having first and second side edges which intersect at a dihedral vertex angle and which are congruently alignable with sides of said first and second moldings and said frame, respectively, between said corner protective preform and said frame corner with said first and second side edges of said template vertically aligned with side edges of said first and second frame moldings, respectively,    b. means for bending upwardly from a horizontal plane of said preform first and second, vertically disposed flap sections which contact said first and second edges, respectively, of said template,    c. means for bending inwardly an upper part of each of said first and second flap sections perpendicularly to horizontal dispositions overlying said rear surface of said frame, and    d. means for securing said overlying parts of said first and second flap sections to each other and to said rear surface of said frame.    
     
     
         18 . The apparatus of  claim 17  wherein said means for bending upwardly from said horizontal plane of said preform said first flap section is further defined as comprising in combination a first flap folder arm attached to an upper end portion of a first support post, first elevator actuator means for selectably elevating and retracting said first flap folder arm, and a first, front flap folder arm recess in an upper surface of a worktable, said first recess being located below said preform and adjacent to a side of said first frame molding and below said first flap section of said preform, whereby elevation of said first flap folder arm by said first elevator actuator means forces said first flap section to bend upwardly with respect to said surface of said preform to lodge vertically against said first edge of said template plate.  
     
     
         19 . The apparatus of  claim 18  wherein said means for bending perpendicularly inwardly from said first flap section an upper part which overlies said rear surface of said frame is further defined as comprising a first rotary actuator means coupled to said first flap folder arm, said first rotary actuator means being effective in rotating said first flap folder arm from a home elevated position vertically aligned with said first flap folder arm recess inwardly towards said first frame molding to an active elevated position overlying said first frame molding, thereby bending said upper part of said first flap section over said first frame molding.  
     
     
         20 . The apparatus of  claim 19  wherein said means for bending upwardly from said horizontal plane of said preform said second flap section is further defined as comprising in combination a second flap folder arm attached to an upper end portion of a second support post, second elevator actuator means for selectably elevating and retracting said second flap folder arm, and a second front flap folder arm recess in an upper surface of said worktable, said second recess being located below said preform and adjacent to a side of said second frame molding and below said second flap section of said preform, whereby elevation of said second flap folder arm by said second elevator actuator means forces said second flap section to bend upwardly with respect to said surface of said preform to lodge vertically against said second edge of said template plate.  
     
     
         21 . The apparatus of  claim 20  wherein said means for bending perpendicularly inwardly from said second flap section an upper part which overlies said rear surface of said frame is further defined as comprising a second rotary actuator means coupled to said second flap folder arm, said second rotary actuator means being effective in rotating said second flap folder arm from a home elevated position vertically aligned with said second flap folder arm recess inwardly towards said second frame molding to an active elevated position overlying said second frame molding, thereby bending said upper part of said second flap section over said second frame molding.  
     
     
         22 . The apparatus of  claim 17  wherein said means for positioning said template plate between said preform and said frame corner is further defied as comprising in combination; 
 a. a worktable having an upper surface for supporting a preform,  
 b. means for positioning an individual preform at a predetermined location on said upper surface of said worktable,  
 c. means for positioning a corner of a frame at a predetermined location relative to said preform, and  
 d. template linear actuator means for advancing said template forward to an operative position between said preform and said frame prior to said preform being bent around said frame corner, and retracted to a home position thereafter.  
 
     
     
         23 . The apparatus of  claim 22  wherein said template plate is further defined as having triangularly-shaped laterally symmetric front portion, and a longitudinal center line parallel to a line of action of said template plate linear actuator.  
     
     
         24 . The apparatus of  claim 23  wherein said template plate is further defined as being mounted on the upper surface of a support base, said support base having a transversely disposed front edge wall located rearwards of said front triangular portion of said template plate.  
     
     
         25 . The apparatus of  claim 24  wherein said means for positioning an individual preform at a predetermined location on said upper surface of said worktable is further defined as comprising in combination a preform pusher plate, and a preform linear actuator for advancing an individual preform forward into a predetermined operative position on said upper surface of said worktable, and retracting said pusher plate to a rearward home position.  
     
     
         26 . The apparatus of  claim 25  wherein forward motion of said preform to said predetermined operative position is limited by contact of said preform with said front edge wall of said template plate base.  
     
     
         27 . In a method for folding a flexible material around a corner of a frame having front and rear face surfaces to thereby form a protective cover for said corner, said corner being formed by an intersection at a dihedral angle of two adjacent, first and second sides of said frame, the improvement comprising; 
 a. positioning a thin template plate which has in plan view a wedge-shaped forward portion approximating that of an isosceles triangle which has a transversely disposed base and equal length sides which angle forward and inwards towards a longitudinal center line comprising an altitude of the triangle and which intersect at a vertex angle to form a forward protruding vertex, between said flexible material and a face of said frame, with said vertex and sides of said template plate symmetrically positioned with respect to said sides and corner of said frame, and    b. bending from a plane containing said material towards said first and second sides of said frame first and second flap sections for subsequent bending over a face of said frame, inward motion of said first and second flap sections being limited by contact between first and second flap sections and said first and second sides, respectively, of said template plate.    
     
     
         28 . The method of  claim 27  wherein said vertex angle of said template plate is substantially equal to ninety degrees.  
     
     
         29 . The method of  claim 28  wherein said dihedral frame angle is substantially equal to ninety degrees.  
     
     
         30 . In an apparatus for attaching a protective cover to a corner of a frame having front and rear face surfaces, said corner being formed by an intersection at a dihedral frame corner angle of two adjacent, first and second sides of a frame, said protective cover being made of a thin sheet of flexible material, the improvement comprising; means for positioning a template plate which has first and second side edges that intersect at a dihedral template vertex angle which is substantially congruently alignable with said first and second sides and dihedral frame corner angle, respectively, between said thin sheet of flexible material and a face surface of said frame, whereby bending motion of first and second flap sections from said thin sheet of material towards said first and second sides of said frame is limited by contact between said first and second flap sections and said first and second sides, respectively, of said template plate.  
     
     
         31 . The apparatus of  claim 30  wherein said vertex angle of said template plate is substantially equal to ninety degrees.  
     
     
         32 . The method of  claim 31  wherein said dihedral frame angle is substantially equal to ninety degrees.