Method for molding running board with step plate
View Patent ↗A process for making a molded running board assembly for installation on a vehicle includes blow molding the body of the running board and incorporating one or more additional components such as a step plate or a trim strip. The process involves placing the insert into the blow mold cavity in a subcavity, holding the insert by vacuum pressure and then extruding and blow molding a parison to simultaneously mold the running board and integrate the insert.
1. A process for making a running board assembly of a running board and an insert comprising:
providing complementary mold components having respective molding cavities, at least one of said mold components having at least a subcavity within the cavity of that mold component;
providing an insert;
inserting the insert into the subcavity;
applying vacuum pressure to the subcavity to hold the insert in place;
extruding a parison between the mold components;
closing the mold components;
expanding the parison within the cavity to simultaneously mold the running board and integrate the insert and the running board,
wherein the insert is selected from the group consisting of one or more step plates, one or more trim strips and combinations of the foregoing.
2. The process of claim 1 wherein the insert is a step plate.
3. The process of claim 2 wherein the step plate is formed of a moldable anti-slip material which is compatible for thermal bonding with said parison.
4. The process of claim 3 wherein said moldable step plate is at a temperature below the molding temperature of the material of the moldable step plate when said moldable step plate is inserted in said subcavity.
5. The process of claim 4 wherein said subcavity comprises a molding pattern for molding a pattern on a surface of said moldable step plate.
6. The process of claim 5 wherein said step of expanding said parison causes said parison to contact said moldable step plate, transfer heat to said moldable step plate to raise its temperature to a temperature suitable for molding said moldable step plate and force said moldable step plate against said molding pattern of said subcavity to mold a surface of said step plate.
7. The process of claim 6 wherein said subcavity has a depth of less than 1 mm and said moldable step plate has a thickness of greater than 1 mm.
8. The process of claim 7 wherein the parison is expanded by blow molding using an internal pressure within the parison of greater than 90 psi.
9. The process of claim 2 wherein said step plate is metallic, said metallic step plate having a support surface and an attachment surface.
10. The process of claim 9 wherein said attachment surface comprises at least one key shaped rib.
11. The process of claim 10 wherein said parison is blow molded against said step plate and said at least one key shaped rib is encapsulated within said molded parison.
12. The process of claim 11 wherein said step plate comprises a plurality of said key shaped ribs and said plurality of key shaped ribs are encapsulated within said molded parison.
13. The process of claim 1 wherein said insert is a trim strip.
14. The process of claim 13 wherein said trim strip is not thermally bondable with said parison.
15. The process of claim 14 wherein said subcavity includes an undercut around at least a portion of the perimeter of said subcavity and said insert is supported in said subcavity so that upon expansion of said parison a portion of said parison may flow into said undercut.
16. The process of claim 15 wherein said parison is blow molded with a parison internal pressure of at least 90 psi.
17. The process of claim 15 wherein said undercut extends substantially around the perimeter of said subcavity so that said parison may flow into a portion of said subcavity when blow molded, adjacent a substantial portion of the edge of the insert so that the expanded parison retains the trim strip.