Forming thermoplastic web materials
AssigneeHitek Limited
InventorAnthony E. Flecknoe-Brown
Life of this patent
Estimating the term…
Abstract
A web of thermoplastic material extruded directly into a set of tempering rolls is cooled on its upper and lower surfaces while the interior of the web is kept molten. The partially cooled web is fed onto a converyor on which it is fed to a thermoformer. The web remains on the conveyor until its surface layer in contact with the conveyor is reheated to a thermoformable temperature below that at which the web will stick to the conveyor. Apparatus for feeding a web of thermoplastic material from an extrusion to a thermoformer includes tempering rolls and conveyor means which can be adjusted in their relative positions and to control the length of conveyor means contacted by the web.
Claims16
A method of thermoforming hollow objects including:
- extruding a web of thermoplastic material directly into a set of temperature controlled tempering rolls, cooling upper and lower surface layers of the web by passage through said tempering rolls which maintaining the interior of the web in molten condition between said surface layers, feeding the partially cooled web onto a conveyor, and conveying the web to the entry of a thermoformer, characterized in that the web is allowed to remain on the conveyor over such a length of the conveyor and for such a time until the surface layer of the web which is in contact with the conveyor has been reheated by the molten interior of the web to a thermoformable temperature below the temperature at which the web will stick to the conveyor.
Apparatus for feeding thermoplastic sheet from an extruder to a thermoformer, including a set of temperature controlled tempering rolls to receive a web of molten thermoplastic material from the extruder, conveyor means to receive the tempered web from the tempering rolls and convey the web to the entry of the thermoformer, characterized in that the relative positions of the tempering rolls and the conveyor means and the length of the conveyor means contacted by the web are adjustable whereby the temperature of the web surface in contact with the conveyor means can be controlled so that it enters the thermoformer at a thermoformable temperature below that at which the web will stick to the conveyor means.
Dependencies are inferred from the claim text.