Extrusion & Post
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PE Pipe Ovality and Wall Thickness Unevenness
Problem Phenomenon
HDPE/PE pipe cross-sections are elliptical, or the circumferential wall thickness deviation is large, affecting butt fusion welding and laying quality.
Cause Analysis
Insufficient vacuum sizing, uneven cooling or mismatch between the haul-off speed and extrusion speed causes ovality; improper die adjustment, die and mandrel misalignment and uneven melt flow cause wall thickness unevenness; the self-weight sagging of large-diameter pipes superimposes.
Solution
①Adjust the vacuum degree of the vacuum tank and ensure uniform circumferential cooling; ②synchronize the extrusion and haul-off speeds; ③regularly check and adjust the die bolts and correct the die-mandrel concentricity; ④correct the sizing sleeve dimensions; ⑤coordinate with online thickness and ovality detection.
Key Takeaway
PE pipe ovality and wall thickness are jointly determined by 'sizing + cooling + haul-off + die concentricity': first get the die concentricity and sizing right, then stabilize the synchronization of extrusion and haul-off, and only then can the geometric accuracy be guaranteed.
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