High-voltage cable insulation material continuous extrusion processing characteristic evaluation and optimization method and apparatus

A method for optimizing continuous extrusion processing of a high-voltage cable cross-linked polyethylene insulation material, comprising:

• at a step B1, using a set cross-linkable polyethylene insulation material, and selecting a small single-screw extruder with a similar structure and the same number of heating sections as a large extruder according to the number of heating sections of the large extruder used in an actual production;
• at a step B2, heating the cross-linkable polyethylene insulation material into a melt under set process conditions, continuously extruding the melt through the capillary mold by the single-screw extruder, continuously measuring and recording an inlet pressure P of the capillary, a mass growth rate w of an extruded melt, and the diameter D′ of a melt strip during the extrusion, and obtaining an apparent shear viscosity ηa of a melt flow;
• at a step B3, calculating an outlet expansion rate δ of the melt by using the diameter D′ of the melt strip;
• at a step B4, recording and displaying curves ηa(t) and δ(t) of the apparent shear viscosity and outlet expansion rate of the melt changing with time, determining time corresponding to an increase of a set percentage in the ηa (t) or δ(t) on the curve ηa (t) or δ(t) as the starting time of the cross-linking reaction, and recording the time as TX;
• at a step B5, providing a plurality of groups of different process conditions, continuously extruding the melt of the tested material through the capillary mold under each group of process conditions, retesting the starting time TX of the cross-linking reaction of the material, and obtaining a value of the TX related to each group of process conditions;
• at a step B6, determining a shear viscosity corresponding to a maximum value of TX as a numerical characteristic of the melt in an optimal flow state, and determining the group of process conditions corresponding to the shear viscosity as a group of optimal conditions for the extrusion processing of a long-length submarine cable;
• at a step B7, setting production process parameters of an actual extruder according to a rule of obtaining process parameters through the testing of the small extruder at the step B6, and fine-tuning the production process parameters to obtain the optimal process parameters.