Claims
- 1. A process for producing a light weight hollow thermoplastic board having a first planar sheet and a second planar sheet which are spaced apart by and interconnected by longitudinally extended ribs having shifted patterns, which comprises:
extruding molten thermoplastic through an extruder having a die assembly with a die with a cavity having a cross-section corresponding to a desired external shape of a thermoplastic board and having mandrels within said cavity to create a soft board having a plurality of longitudinal passageways and ribs between a first planar sheet and a second planar sheet; advancing the resulting soft board to a sizer and coller assembly to set the first dimensions of the soft board and cool it to a rigid board; during said extruding and said advancing, oscillating one of said die assembly and said sizer and cooling assembly relative to one another in a predetermined sequence to cause said ribs to shift from a straight line path to eastablish a board with ribs of shifting patterns.
- 2. The process of claim 1 wherein said die assembly is stationary and said sizer and cooling assembly is oscillated.
- 3. The process of claim 2 wherein said sizer and cooling assembly is oscillated mechanically.
- 4. The process of claim 2 wherein said sizer and cooling assembly is oscillated by computer control.
- 5. The process of claim 1 wherein said die assembly is oscillated and said sizer and cooling assembly is atationary.
- 6. The process of claim 5 wherein said die assembly is oscillated mechanically.
- 7. The process of claim 5 wherein said die assembly is oscillated by computer control.
- 8. The process of claim 1 wherein said process further includes: annealing said rigid board in an oven.
- 9. The process of claim 1 wherein said board is made of thermoploastic polymer selected from the groups consisting of olefins, styrenes, vinyl chlorides, acrylics, carbonates and ethylene terephthalates.
- 10. The process of claim 9 wherein said thermoplastic polymer is selected from the group consisting of polypropylenes, linear polyethylene, branched polyethylene and copolymers thereof.
Parent Case Info
[0001] This application is a divisional application of Ser. No. 09/902,317, filed Jul. 10, 2001.
Divisions (1)
|
Number |
Date |
Country |
Parent |
09902317 |
Jul 2001 |
US |
Child |
10831577 |
Apr 2004 |
US |