Abstract A method and apparatus for manufacturing synthetic resin extrusion products by controlling the temperature of the resin to within + OR - 10*F. of a desired point as it is formed into a homogeneous mass and extruded. This control is accomplished by providing one temperature sensing thermocouple in the barrel of the extruder, another temperature sensing thermocouple in the heating/cooling jacket mounted on the outside of the barrel, and by providing electrical control circuitry which averages the temperature readings of the two thermocouples and controls the supply of energy to the heating/cooling jacket in accordance with the difference between that average and the desired temperature to which the controller is set. Included as well is the novel synthetic resin extrusion article obtained by extruding the resin upwardly into a tubular parison using this low temperature process and stretching the parison axially before blow molding it.
Apparatus according to claim 1 wherein the heat exchange device includes both heating means and cooling means and the means including control circuitry includes means for energizing the heating means whenever the indicated temperature average is below the set point by a predetermined amount and for energizing the cooling means whenever this average is above the set point by a predetermined amount.
Claim 2
Dependent Claim
71 words
Apparatus according to claim 2 wherein there is a well in the radial periphery of the barrel and the first temperature sensing device comprises a thermocouple mounted in the well, the heat exchange device is mounted on the barrel, there is a well in the periphery of the heat exchange device and the second temperature sensing device comprises a thermocouple mounted therein and said control circuitry includes a null balance circuit.
Claim 3
Dependent Claim
25 words
Apparatus according to claim 3 wherein each of the thermocouples lie at different radial distances in a single plane through and perpendicular to the barrel.
Claim 4
Dependent Claim
38 words
Apparatus according to claim 4 wherein the control circuitry is voltage regulating circuitry whereby the amount of energy fed to the heating means increases as the difference between the average indicated temperature and the set point becomes greater.
Claim 5
Dependent Claim
35 words
Apparatus according to claim 1 wherein the heat exchange units include heating means and the means including control circuitry includes means for energizing the heating means whenever said average is lower than a predetermined level.
Claim 6
Dependent Claim
35 words
Apparatus according to claim 1 wherein the heat exchange units include cooling means and the means including control circuitry includes means for energizing the cooling means whenever said average is higher than a predetermined level.