US 5,244,618 A · Process and apparatus for continuous three-dimensional forming of heated thermoplastic materials

Abstract

Continuous process and apparatus form products from thermoplastic materials between top and bottom mold carriages. A flexible silicone rubber mold on a fiber belt continuously moves around each carriage frame. A surface of desired shape on one rubber mold mates with the desired shape of an opposed rubber mold forming a continuously moving mold channel into which is fed hot thermoplastic material at moldable temperature. After discharging the molded plastic product from the moving mold channel, localized surface heat in the molds resulting from contact with hot plastic is removed from the belt molds by air blown onto mold surfaces. Each carriage frame includes a back-up plate coated with low friction coefficient material over which slides a continuously moving belt mold. These slippery plates have numerous air-bearing holes feeding high pressure air between them and the respective moving fiber belt for reducing friction and wear. The fiber belts are guided and driven by a wide, central V-shaped toothed ridge or by twin, wide V-shaped toothed ridges along belt margins. These ridges fit into and mesh with corresponding toothed grooves of sprocket drive rolls, serving to maintain alignment of revolving mold belts. An electric drive motor, with or without torque-motor assistance, revolves both belt molds in unison maintaining their mating alignment. Electric screw jacks raise the top carriage, extend/retract grooved exit rolls, fine-tune alignment of revolving belt molds by adjusting grooved exit rolls and adjust the machine relative to the extruder.

A process for three-dimensional forming of thermoplastic material heated to a formable temperature comprising the steps of:

(a) providing a first flexible belt mold with an inner side and with a first mold surface on an outer side, said first mold surface having a first three-dimensional mold pattern therein;
(b) providing a second flexible belt mold with an inner side and with a second mold surface on an outer side, said second mold surface having a second three-dimensional mold pattern therein;
(c) providing first and second spaced parallel longitudinally extending ridges on said inner side of said first belt mold;
(d) providing third and fourth spaced parallel longitudinally extending ridges on said inner side of said second belt mold;
(e) positioning said first mold surface in juxtaposition with said second mold surface with said first and second three-dimensional mold patterns being in mating relationship for defining at least one mold channel between said first and second mold surfaces;
(f) revolving said first and second flexible belt molds for moving said mold channel from an entrance region to an exit region;
(g) introducing heated thermoplastic material at moldable temperature into the entrance region of the moving mold channel;
(h) forming heated thermoplastic material in said moving mold channel and removing heat therefrom for setting thermoplastic material in said moving mold channel into a formed product having a three-dimensional surface pattern exiting from the exit region of the moving mold channel;
(i) stabilizing said first flexible belt mold along said moving mold channel by a first backup plate extending longitudinally along the inner side of said first flexible belt mold;
(j) guiding said first flexible belt mold by first and second spaced parallel clearances extending longitudinally along said first backup plate for receiving said first and second ridges, respectively;
(k) stabilizing said second flexible belt mold along said moving mold channel by a second backup plate extending longitudinally along the inner side of said second flexible belt mold;
(l) guiding said second flexible belt mold by third and fourth spaced parallel clearances extending longitudinally along said second backup plate for receiving said third and fourth ridges, respectively;
(m) introducing air between the inner side of said first flexible belt mold and said first backup plate between said first and second ridges for providing an air-bearing effect for reducing friction between the inner side of said first flexible belt mold and said first backup plate;
(n) introducing air between the inner side of said second flexible belt mold and said second backup plate between said third and fourth ridges for providing an air-bearing effect for reducing friction between the inner side of said second flexible belt mold and said second backup plate;
(o) blowing air onto said first mold surface for removing heat from said first mold surface as said first flexible belt mold is returning from said exit region to said entrance region;
and
(p) blowing air onto said second mold surface for removing heat from said second mold surface as said second flexible belt mold is returning from said exit region to said entrance region.

14 more elements

Facts

Application

07/843,362Filed 25 Feb 1992 · division

Priority

6 Apr 1990

Granted

14 Sep 1993

Term ends

Not estimatedThe source records don’t support an estimate.

Classification20 codes

B29C 35/16
Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor: cooling
B29C 43/222
Of articles of indefinite length: characterised by the shape of the surface
B29C 43/48
Compression means for making articles of indefinite length: endless belts
B29C 43/52
Component parts, details or accessories; Auxiliary operations: heating or cooling

Process and apparatus for continuous three-dimensional forming of heated thermoplastic materials

Life of this patent

Process and apparatus for continuous three-dimensional forming of heated thermoplastic materials

Life of this patent

Abstract

Claims17