Process of making plastic hinge for raceway

Claim 1

A process for forming an elongate plastic article having first and second rigid plastic panels of substantially uniform thickness and integrally joined together by a flexible plastic hinge portion, comprising the steps of: extruding first and second sheetlike panels of a rigid plastic material so that the panels have opposed longitudinally-extending edges positioned close to but sidewardly spaced apart; coextruding a strip of a soft and flexible plastic material into the longitudinal space defined between the opposed edges of said first and second panels so as to define a flexible portion which is integrally bonded to the opposed edges of the panels and extends across the thickness thereof; forming during said first-mentioned extrusion step a rigid plastic bridge structure which spans across the space between the opposed edges but which projects outwardly from side surfaces of the panels and is integrally joined thereto so as to rigidly structurally join the panels together for maintaining dimensional stability; said coextrusion step resulting in the flexible portion having a part which projects outwardly beyond the side surfaces of the panels and is surrounded by the bridge structure; and thereafter simultaneously severing said bridge structure and said projecting part from said article at a location which is approximately flush with said side surfaces so that said panels are integrally interconnected solely through said flexible portion.