The production line for threading pipes involves multiple aspects such as equipment operation, quality control, safety protection, and production management, which need to be strictly controlled from five aspects: raw material preparation, equipment debugging, production monitoring, finished product inspection, and safety regulations. The following are specific precautions:
1、 Raw material preparation and quality control
Raw material selection and inspection
Material matching: Select raw materials according to the purpose of the pipe, such as rigid polyvinyl chloride (PVC-U) for PVC conduit and high-density polyethylene (HDPE) for PE conduit.
Performance testing: Check the melt flow rate (MFR), density, tensile strength and other indicators of the raw materials to ensure compliance with national standards (such as GB/T 20041.1-2015).
Impurity control: The raw materials must not contain impurities such as metals, sand and gravel, otherwise it may scratch the mold or cause surface defects on the pipe.
Raw material pretreatment
Drying treatment: PVC raw materials need to be dried at 80-90 ℃ for 2-4 hours, with a moisture content controlled below 0.1% to prevent the formation of bubbles during processing.
Uniform mixing: Use a high-speed mixer to thoroughly mix the raw materials with stabilizers, lubricants, fillers, and other additives to ensure accurate formula proportions.
2、 Equipment debugging and parameter setting
Extruder debugging
Temperature control: Set the temperature of each zone according to the characteristics of the raw materials. For example, during PVC extrusion, the barrel temperature is 160-185 ℃ and the head temperature is 175-190 ℃.
Screw speed: Adjust the screw speed to control the melt pressure and output, avoiding material decomposition caused by high speed or poor plasticization caused by low speed.
Vacuum shaping: The pressure of the vacuum shaping box is controlled at -0.06 to -0.08MPa to ensure the stability of the outer diameter of the pipe.
Mold installation and adjustment
Mold matching: Select the mold that corresponds to the specifications of the pipe, and the gap between the mouth molds should be uniform with a deviation of no more than 0.05mm.
Cooling system: Check the water temperature (usually 20-30 ℃) and flow rate of the cooling water tank to ensure rapid cooling and shaping of the pipes, and prevent deformation.
Traction and cutting equipment
Traction speed: The traction speed should be synchronized with the extrusion speed to avoid pipe stretching or stacking.
Cutting accuracy: Adjust the angle and speed of the cutting blade to ensure that the end face of the pipe is flat and the length deviation does not exceed ± 2mm.
3、 Production process monitoring
Real time parameter monitoring
Use sensors to monitor key parameters such as extrusion pressure, melt temperature, and vacuum degree, and adjust them promptly when data fluctuations exceed ± 5%.
Record production logs, including information such as raw material batches, equipment parameters, production time, etc., for easy traceability of quality issues.
Appearance quality inspection
Surface defects: Check the surface of the pipe every 30 minutes for scratches, pits, color differences, and other defects, and clean the mold or adjust the process in a timely manner.
Wall thickness uniformity: Use an ultrasonic thickness gauge to measure the wall thickness of the pipe, and the deviation should be controlled within ± 10%.
size control
Outer diameter and inner diameter: Measure the outer diameter and inner diameter of the pipe with a caliper every hour to ensure compliance with standards (such as DN20 pipe with an outer diameter of 25mm and a wall thickness of 2.0mm).
Ellipticity: Check whether the cross-section of the pipe is round, and the ellipticity should not exceed 2% of the outer diameter.
4、 Finished product inspection and packaging
performance testing
Compression test: Conduct ring stiffness test according to GB/T 9647-2015 to ensure that the pipe can withstand the specified pressure without breaking.
Bending test: Bend the pipe to 90 ° and check for surface cracking or whitening.
Flame retardant test: Conduct a vertical combustion test on PVC pipes, and the oxygen index should be ≥ 32%.
Packaging and Storage
Protective measures: Seal both ends of the pipe with plastic plugs to prevent dust from entering; Wrap PE protective film on the surface to avoid scratches.
Stacking standard: Pipes should be stacked flat or in layers, with a height not exceeding 1.5m, and the bottom should be padded with wooden blocks to prevent deformation.
Environmental requirements: The storage warehouse should be dry, ventilated, with a temperature controlled between 5-35 ℃, and avoid direct sunlight.
5、 Safety and environmental regulations
Equipment safety operation
Protective devices: Ensure that the safety doors, emergency stop buttons, protective covers, and other devices of extruders, cutting machines, and other equipment are intact and effective.
Personal protection: Operators should wear protective goggles, earplugs, dust masks, and heat-resistant gloves to avoid injury from high-temperature materials or splashes.
Electrical safety
Grounding protection: Check if the equipment grounding wire is secure to prevent electric shock accidents caused by leakage.
Insulation testing: Regularly use a megohmmeter to test the insulation resistance of components such as motors and heaters, ensuring it is ≥ 0.5M Ω.
environmental requirements
Waste gas treatment: The hydrogen chloride (HCl) gas generated by the extruder heating needs to be treated through an alkali spray tower and discharged after meeting the standards.
Waste recycling: Scrap materials and non-conforming products need to be sorted and recycled, re crushed, and used for the production of low demand products.