1、 Equipment installation and debugging

1. Fundamentals and Calibration
   • Basic requirementsThe equipment needs to be installed on a concrete foundation with a horizontal error of ≤ 0.2mm/m to avoid vibration causing deviation in the wall thickness of the pipe (such as the inclination of the traction machine causing the pipe ovality to exceed the standard).
   • Calibration ExampleAdjust the centerline of the extruder, shaping box, and traction machine using a laser level to ensure a coaxiality error of ≤ 0.5mm.
2. Electrical and Temperature Control
   • grounding protectionAll equipment must be reliably grounded with a grounding resistance of ≤ 4 Ω to prevent the risk of electrical leakage.
   • Temperature control accuracyControl the heating zone of the barrel (such as independent temperature control in zone 6), with temperature fluctuations of ≤± 2 ℃, to avoid local overheating and decomposition of materials (PVC decomposition temperature is about 180 ℃).
3. Mold and shaping matching
   • Mold selectionThe diameter of the mold outlet is equal to the nominal outer diameter of the pipe multiplied by (1+0.8%~1.2%) (if producing DN200 pipe, the mold diameter should be 201.6~202.4mm).
   • Vacuum shapingThe vacuum degree should be stable at -0.06~-0.09MPa, and the water flow rate should be ≥ 15L/min to ensure that the pipe is quickly shaped and not deformed.

2、 Process parameter control

1. Raw material ratio and pretreatment
   • formula ratioPVC resin: CaCO3: stabilizer: lubricant=100:40:2 (mass ratio), needs to be mixed using a high-speed mixer at 110-120 ℃ for 8-10 minutes.
   • Moisture content controlThe moisture content of the raw material should be ≤ 0.2%, otherwise bubbles are prone to occur (it can be dried in a hot air circulating oven at 80 ℃ for 2 hours).
2. extrusion process
   • temperature curve(Taking PVC-U as an example):

     Barrel section	Temperature (°C)	effect
     feeding section	160-170	Preheating of materials
     Compression segment	175-185	Material plasticization
     measuring section	180-190	Stable extrusion
     nose	190-200	成型定型

   • screw speedAdjust according to the specifications of the pipe (such as DN160 pipe speed of 18-22pm), and match it with the traction speed (extrusion speed: traction speed=1:1.02-1.05).
3. Cooling and traction
   • cooling waterThe water temperature is 15-25 ℃, and the water flow rate is ≥ 2m/s to avoid internal stress in the pipes (which can be improved by increasing the spray angle or extending the length of the cooling water tank).
   • tractionThe traction force should be stable at 500-800N (adjusted according to the pipe specifications), as excessive force can easily cause the pipe to stretch and deform.

3、 Production Safety and Operating Standards

1. Pre-start inspection
   • safety protectionCheck if the emergency stop button, protective cover, and limit switch are functioning properly, and if the electrical cabinet door is closed.
   • lubrication systemThe oil level of the gearbox should be above the centerline of the oil gauge, and the bearings should be lubricated with lithium based grease 1-2 times per shift.
2. process monitoring
   • key parameters：
     • Host current: ≤ 150A (DN200 pipe). If it exceeds the limit, the machine should be stopped immediately for inspection.
     • Pipe wall thickness: Real time monitoring using an online thickness gauge, with a deviation of ≤± 0.3mm.
   • quality inspectionInspect the appearance (no cracks or bubbles) and size (outer diameter, wall thickness, roundness) of the pipes once per hour.
3. Shutdown and Emergency Response
   • Normal shutdownFirst, reduce the screw speed to zero, then turn off the heating, and finally stop the cooling water (with an interval of ≥ 5 minutes).
   • emergency：
     • Pipe melting and rupture: reduce the head temperature by 10-15 ℃ and increase the traction speed by 5%.
     • Vacuum leakage: Immediately stop the machine and check the sealing ring. After replacement, it is necessary to vacuum again to -0.08MPa.

4、 Maintenance and upkeep

1. routine maintenance
   • cleanClean the residual materials in the hopper, screw, and mold every shift (using a copper brush to avoid damaging the chrome plating layer).
   • fastenCheck whether the connecting bolts (such as flanges and bearing seats) are loose, and the torque should meet the requirements of the equipment manual.
2. regular maintenance
   • Screw and barrelMeasure the gap every six months (normal 0.1~0.3mm), and repair or replace if the gap is greater than 0.5mm.
   • vacuum pumpReplace lubricating oil every month and check if the filter screen is clogged (pressure gauge reading should be ≤ -0.1MPa).
3. Spare Parts Management
   • Key spare partsHeating coils, thermocouples, cutting blades, sealing rings, etc. The inventory level needs to meet the 24-hour production demand.
   • Life management：
     • Screw lifespan: approximately 8000-10000 hours (adjusted according to the corrosiveness of the raw materials).
     • Mold lifespan: approximately 50000-80000 meters (depending on pipe specifications and materials).

5、 Common Problems and Solutions

6、 Environmental Protection and Energy Management

1. waste gas treatment
   • The exhaust port of the extruder needs to be connected to an activated carbon adsorption device, with a VOC emission concentration of ≤ 50mg/m ³ (in accordance with GB 31572-2015 standard).
   • dataThe amount of waste gas produced per ton of PVC pipe is about 100-150m ³.
2. energy consumption optimization
   • frequency conversion controlThe screw drive adopts a frequency converter, which can reduce energy consumption by 15-20% (for example, the power consumption of the DN200 pipe production line has decreased from 380kWh/t to 320kWh/t).
   • waste heat recoveryThe cooling water of the barrel can be recycled for drying raw materials, saving about 20% of steam consumption.

7、 Personnel training and management

1. Operation Training
   • New employees need to pass theoretical (equipment principles, process parameters) and practical (startup, mold adjustment, quality inspection) assessments before they can operate independently.
   • training cycleNot less than 40 hours (including 20 hours of in class learning).
2. Quality Management
   • Implement a system of first inspection, patrol inspection, and final inspection, with a first inspection pass rate of 100% and a finished product pass rate of ≥ 98%.
   • recording requirementsProduction records, equipment maintenance records, and quality inspection records must be kept for at least 2 years.

By strictly following the above precautions, the efficient and stable operation of the drainage pipe production line can be ensured, and the product quality meets the requirements of standards such as GB/T 5836.1-2018. At the same time, the failure rate (target ≤ 2 times/month) and energy consumption cost (target ≤ 350kWh/t) can be reduced.