Claims
- 1. In a method of producing a low density foamed thermoplastic resin article by extruding a foamable thermoplastic resin into a chamber at subatmospheric pressure and withdrawing the foamed thermoplastic resin extrudate from said chamber into the atmosphere, the improvement comprising,
- providing a vacuum chamber with means to evacuate it,
- a barometric leg connected to said vacuum chamber and terminating in a pool of liquid open to the atmosphere,
- the density of the liquid being greater than the density of said foamed thermoplastic resin extrudate and the barometric leg having a conveyor therein extending from the vacuum chamber into said pool of liquid,
- conveying said extrudate from said chamber without substantial tension sufficient to deform said extrudate into said pool of liquid whereby said workpiece floats up into engagement with said conveyor and moving said extrudate with said conveyor into said pool of liquid and through said liquid out into said atmosphere,
- said conveyor having a relatively flat underside inclined at an acute angle to the horizontal such that friction between the workpiece and the conveyor is sufficient to cause said extrudate to move along with the conveyor through said pool of liquid.
- 2. The method recited in claim 1 wherein said conveyor has protuberances on the lower side thereof and said protuberances grasp said extrudate, thereby moving said extrudate along with said conveyor through said pool of liquid until said extrudate is released into said atmosphere.
Parent Case Info
This is an improvement of my application Ser. No. 294,770, filed Oct. 4, 1972 which in turn is a division of my application application Ser. No. 47,277, filed June 18, 1970 and now U.S. Pat. No. 3,704,083.
US Referenced Citations (7)
Foreign Referenced Citations (2)
Number |
Date |
Country |
1,084,746 |
Sep 1967 |
UK |
1,233,088 |
May 1971 |
UK |