Patent ID: 6652258
Filing Date: 2003-11-25
Classification: B29C

Abstract:
A mold block assembly for thermoforming plastic pipe having transverse corrugations, comprising:a. a mating pair of mold blocks capable of mating along a parting surface; each of said blocks comprising: i. an internal lateral surface comprising at least one corrugation revolving around an axis; ii. an external lateral surface axially concentric with said internal lateral surface, said external lateral surface further comprising at least one channel concentric with said at least one corrugation, the width of said at least one channel corresponding approximately to the width of said at least one corrugation; iii. a vacuum port connected to said at least one channel; iv. a plurality of radial slots having approximately the same width, one end of each of said radial slots intersecting said at least one channel, said slots extending radially inwardly and terminating a distance from said internal lateral surface; v. a plurality of slits formed in said at least one corrugation at said internal lateral surface and intersecting the width of said slots; and vi. at least one outer cover on said external lateral surface forming an air tight manifold, said manifold having a large cross-sectional area relative to the aggregate area of said slits ported to said manifold through said plurality of radial slots.