US 6,149,732 A · Method and apparatus for removing plastic residue

Abstract

Equipment used in the processing of plastic, such as molds and extrusion screws, is cleaned of plastic residue by a combination of thermal cycling and agitation without impact cleaning. A chamber can be heated by an electric radiant heater and cooled by the introduction of liquid nitrogen. A fixture in the chamber receives the equipment to be cleaned and is agitated by a drive motor. The chamber is heated and cooled in the following cycle in which the drive motor agitates the fixture: first to 250-300.degree. F., then to -315.degree. F., then cycled between -50.degree. F. and -10.degree. F., then to 150.degree. F., then to -200.degree. F., then to 100.degree. F., then to ambient temperature. The chamber is controlled by a computer that prompts the operator for the kind of plastic to be cleaned off of the equipment and then controls the heating and cooling automatically.

Claims8

Dependent claims

A method of cleaning residue of a material from equipment used in processing the material, the method comprising the following steps:

(a) thermally cycling the equipment between a first temperature and a second temperature which is different from the first temperature such that the equipment is exposed to each of the first and second temperatures at least twice;
(b) agitating the equipment during step (a) to loosen the residue of the material from the equipment so as to clean the residue of the material from the equipment;
and
(c) before step (a):
exposing the equipment to a third temperature which is higher than either of the first and second temperatures;
and
then exposing the equipment to a fourth temperature which is lower than any of the first, second and third temperatures.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus for removing plastic residue

Life of this patent

Method and apparatus for removing plastic residue

Life of this patent

Abstract

Claims8