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PVC HosesAnalysis Of Molding Quality

Edit: Weifang Jintai Plastic Industry Co.,Ltd    Date: Aug 24, 2017

(1) pipe surface is uneven with wrinkles

① Extruder process temperature is high or the temperature distribution is unreasonable, did not reach the temperature from the feeding section to the molding die mouth gradually increased process conditions. Should be appropriate to adjust the temperature control section.

② mold parts of the various parts of the temperature uneven, there may be local heating components do not work. Should be properly modified to improve the heating arrangement.

(2) pipe diameter is not round

① melt temperature is high, should be appropriate to reduce the mold and barrel process temperature.

② from the molding die extrusion tube cooling rate is not uniform. Should be appropriate to adjust the cooling method, the tube circumference to be uniform cooling cooling.

③ set sleeve deformation is not round, should check the maintenance.

(3) pipe diameter of the outer diameter of the vertical error

① screw rotation instability, so that the extrusion melt flow instability. Check the belt drive in the drive system, there may be belt work slip phenomenon, should be adjusted or change the belt.

② traction machine running is not smooth, resulting in the extrusion die mouth of the tube is not fixed, affecting the longitudinal dimensional accuracy of the pipe. Adjust the control or maintenance of the tractor drive system.

③ machine feed at the mouth of the feed is not uniform, should check whether the hopper material "bridge" phenomenon.

④ tube diameter method of internal pressure, the tube may be blocked air leakage or compressed air input instability, should be checked and repaired.

(4) pipe wall thickness is not uniform

① forming mold parts in the processing accuracy is poor, after assembly parts of the concentricity of less than the quality requirements, the results of the mold cavity within the cavity of the melt flow is not uniform. Should check the quality of parts processing and concentricity after assembly accuracy, if necessary, re-design and processing.

② die and mandrel concentricity adjustment accuracy is not in place, die and mandrel with the circumference of the gap is not uniform. The gap should be re-adjusted.

(5) pipe surface rough dull

① die or mandrel diameter or diameter of the finish is poor, rough uneven. Should be grinding, the face roughness Ra should not be greater than 0.32μm.

② mold forming section of the process temperature control unreasonable, high or low are prone to this phenomenon. Should pay attention to the temperature regulation control here.

③ barrel process temperature is low, the raw material did not achieve complete plastic uniform. Should be appropriate to improve the barrel heating temperature.

(6) pipe surface with black or yellow stripes

① barrel or screw serious wear and tear, melt in the barrel to stay too long decomposition. Check the assembly clearance of the barrel and screw and replace it if necessary.

② forming mold melt flow in the poor, there are material area, resulting in part of the material decomposition. Should deal with mold repair, replacement of poor precision parts.

③ shunt cone angle, the flow resistance. The mold structure should be modified.

④ raw material composition is unreasonable, poor thermal stability of raw materials. Adjust the use of stabilizer in the feedstock.

⑤ screw tail part of the lubricating oil is too large, flow to the barrel side and raw materials mixed. Note the amount of grease used here.


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