Apparatus and method for forming a mold for lenticular sheet

Abstract

Abstract THE PRESENT INVENTION PROVIDES AN APPARATUS AND A METHOD FOR FORMING A MOLD MEMBER TO FORM A TRANSPARENT SHEET WHICH COMPRISES A CLOSELY PACKED ARRAY OF LENSLETS HAVING CONVEX SPHERICAL SURFACES ON AT LEAST ONE OF ITS FACES. A FLAT HARD SURFACE IS PROVIDED WITH SURROUNDING MARGIN MEMBERS WHICH ARE ADJUSTABLE TOWARD AND AWAY FROM EACH OTHER. ON THE SURFACE WITHIN THE MARGIN MEMBERS IS ARRANGED A CLOSELY PACKED ARRAY OF SPHERICAL BALLS, USUALLY BALL BEARINGS, ONE LAYER DEEP AND ALL OF THE SAME DIAMETER, THE THICKNESS OF THE MARGIN MEMBERS BEING SUBSTANTIALLY EQUAL TO THE DIAMETER OF THE BALLS. AFTER THE SPACE BETWEEN THE MARGIN MEMBERS HAS BEEN FILLED, THE MARGIN MEMBERS ARE ADJUSTED TO COMPRESS THE ARRAY OF BALLS SO THAT EACH OF THE BALLS IS IN FIRM CONTACT WITH ITS NEIGHBORING BALLS, OR WITH A MARGIN MEMBER. THE SINGLE LAYER ARRAY OF BALLS IS THEN COVERED WITH A SHEET OF THERMOPLASTIC MATERIAL AND A SECOND LAYER OF SIMILAR MATERIAL, WITH ONE OR MORE THIN SPOUTS PROTRUDING INTO THE SPACE BETWEEN THE TWO LAYERS SO THAT A THERMOSETTING RESIN MAY BE FORCED INTO THE SPACE BETWEEN THE TWO LAYERS THEREBY FORMING A RESILIENT CUSHION. AROUND THE EDGES OF THE BALL ARRAY, THERE ARE PREFERABLY PROVIDED SHIM MEMBERS OVER THE MARGIN MEMBERS, THE SHIM MEMBERS OVERLAPPING AT LEAST THE FIRST ROW OF BALLS ON EACH SIDE OF THE BALL-FILLED AREA, THEREBY COVERING THE RELATIVELY LARGE MARGINAL CAVITY FORMED BETWEEN ANY TWO ADJACENT BALLS NEXT TO THE MARGIN MEMBER. OTHER MARGINAL RESILIENT MEMBERS OR GASKETS MAY ALSO BE PROVIDED AS DESIRED. HEAVY CLAMPING BARS HAVING RECESSES TO ACCOMMODATE THE SPOUTS ARE PROVIDED OVER THE MARGINAL MEMBERS, SHIMS AND GASKETS AND THESE BARS ARE SECURED TO MAKE THE EDGES OF THE PLASTIC SHEETS FLUID-TIGHT. LONG BOLTS OR PINS ARE PROVIDED THROUGH THE PLASTIC SHEETS, SHIMS, MARGIN MEMBERS AND CLAMPING BARS SO AS TO SECURE THE ASSEMBLY AND PROVIDE REGISTER POINTS WHICH ARE USEFUL IN THE LATER USE OF THE MOLD MEMBER TO BE FORMED. A SETTABLE FLUID RESIN, PREFERABLY A THERMOSETTING RESIN, IS THEN INTRODUCED UNDER SLIGHT PRESSURE INTO THE SPACE BETWEEN THE PLASTIC SHEETS, THROUGH ONE OR MORE OF THE SPOUTS PROVIDED THEREBETWEEN, AFTER WHICH THE ASSEMBLY OF PLASTIC SHEETS AND FLUID RESIN IS SUBJECTED TO HEAT AND PRESSURE TO DEFORM THE SHEET OF PLASTIC IN CONTACT WITH THE BALLS AS WELL AS TO SET THE FLUID RESIN FORMING A CUSHION BETWEEN TWO PLASTIC SHEETS. THE PRESSURE IS THEN CONTINUED ON THE ASSEMBLY WHILE THE RESIN COOLS, THEREBY SUBSTANTIALLY ELIMINATING SHRINKAGE AND DEFORMATION OF THE CUSHION. WHEN COOL, A THICK, RIGID BACK-UP PLATE IS CEMENTED OVER THE TOP OF THE SET CUSHION AND THIS CEMENTED ASSEMBLY IS REMOVED FROM THE MOLDING ASSEMBLY, AND THE EDGES MAY BE TRIMMED. THE SET CUSHION ASSEMBLY MAY BE DIRECTLY USED AS A CASTING CAVITY. FOR THIS PURPOSE ITS EMBOSSED FACE IS PREFERABLY MADE OF A FLUOROHALO-CARBON FILM SUCH AS "ACLAR" FILM, OR THE CUSHION IS SPRAYED WITH SILVER OR VAPOR-PLATED WITH A THIN LAYER OF AN ELECTRICALLY CONDUCTIVE METAL, SUCH AS CHROMIUM, AFTER WHICH IT IS PLATED WITH A THICKER LAYER OF A SOLID METAL SUCH AS NICKEL. THE BACK OF THE ELECTRODEPOSITED METAL MAY THEN BE MACHINED TO PROVIDE A FLAT SURFACE AND/OR MAY BE REINFORCED WITH A THICK RIGID BACK-UP PLATE, AND AFTER SEPARATION OF THE ELECTRODEPOSITED METAL FROM THE PLASTIC CUSHION AND IF NECESSARY AFTER MACHINING THE PERIPHERY OF THE ELECTRODEPOSITED METAL, THE LATTER FORMS A DURABLE MASTER FOR PRESSING A NEW PLASTIC CUSHION OR FOR ELECTROFORMING A CURABLE MOLD FOR THE PRODUCTION OF LENTICULAR SHEETS COMPOSED OF CONVEX SPHERICAL LENSLETS, SUITABLE FOR USE IN INTEGRAL PHOTOGRAPHY ACCORDING TO THE LIPPMANN PROCESS OR MORE ESPECIALLY ACCORDING TO THE PROCESS DISCLOSED IN MY COPENDING APPLICATION SER. NO. 600,957 FILED DEC. 12, 1966.

Inventors

• 👤 Roger L De Montebello

Bibliographic Details