PVC extruder operation process

                PVC extruder operation process

1. Mixing

1.Materials:

PVC resin, calcium powder, stabilizer, lubricant, anti-impact agent, processing aid ACR (such as HF-100), weathering agent, whitening agent (toner), etc.

2. Operation process:

Picking - ingredients - hot mixing - cold mixing - extrusion - pulling - sizing - cooling - cutting - inspection - packaging - warehousing

3. Mixing operation process:

Details	Instructions	Precautions
Raw material inspection	1. Raw materials such as PVC powder, calcium carbonate and other raw materials should be enough for 8 hours. 2. Check whether the code number of the raw material received matches the code number of the labeled raw material. 3. Check whether the appearance and hue of the raw materials match the existing materials in the workshop.	1. Raw materials such as PVC powder, calcium carbonate and other raw materials should be enough for 8 hours. 2. Check whether the code number of the raw material received matches the code number of the labeled raw material. 3. Check whether the appearance and hue of the raw materials match the existing materials in the workshop.
Electronic scale inspection	1. Whether the operation is normal, whether the data can be reset to zero, and whether the weighing is accurate. 2. Keep it tidy at all times.	1. If the functions or movements of tools or equipment are abnormal, they will be disabled; 2. If the water, gas, or electricity switches are abnormal, or the air pressure, water pressure, etc. are insufficient, the cause should be checked;
Mixer inspection	1. Check whether there are any abnormalities in the water, gas and electricity switches of the mixer. 2. Turn on the switch and check whether the operations of the mixer are normal. 3. Add lubricating oil regularly to ensure normal lubrication of the mixer.
filler	The weighing error of each bag of filler is ±200g.	1. Pay attention to the quality of raw materials, and remove abnormalities such as impurities and moisture. 2. Place the production materials list on the work surface.
Impact modifier	The individual weight tolerance is ±100g.
EOS or DOP	The individual weight tolerance is ±50g.
PVC powder	According to the specified weight, the weight tolerance of each bag is ±100g.
Manual power on	1. Place the "manual" and "automatic" switches in the manual position. 2. Start hot mixing at low speed, and then switch to high speed hot mixing after feeding for 1 minute.	1. Is there any abnormality in the working panel? 2. After the machine enters the automatic program, the switch must not be changed at will. 3. Pay attention to the quality of grinding powder or crushed materials such as impurities, etc. 4. If there is any abnormality in quality, the supervisor and technical department should be notified in time. 5. Isolate and mark abnormal materials and wait for verification before processing.
Feeding	1. Throw in all the prepared ingredients and close the lid.
Automatically start up	1. The mixer automatically switches from low speed to high speed within the set time. 2. The machine enters automatic operation state. When the process temperature reaches the set condition, it will automatically enter the next process.
Feed confirmation	1. It is necessary to confirm the next feeding after the hot mixing is exhausted and the valve is completely closed. 2. Observe the high and low speed conversion of hot pot feeding and temperature changes
Throwing fee	1. After the hot mix is automatically discharged into the cold mixer, the return material is put in.
machine malfunction, Power, gas, water outage	1. Open the hot mixing lid, open the air valve and discharge material at low speed. 2. Heat the pot first and then cool the pot.	The pot cleaning can only be operated after the power switch is turned on and the stop sign is hung.
Mixing quantity control	Mixing needs to take production schedule into consideration. For the same formula, the total amount of mixed ingredients cannot exceed the amount specified in the production bill of materials. When the planned demand is sufficient and an increase is needed, the additional quantity will be notified in a timely manner.	1. Maintain the principle of not mixing too much. 2. When a backlog occurs after the materials are mixed well, the identification card should be hung up.
Record	1. Every time mixing is completed, the total amount of the pot ingredients must be recorded on the record sheet. 2. Record the mixing process for each batch of materials mixed.	1. When the formula content has been modified due to production needs, it must be clearly explained to the next shift. 2. When production and processing of raw materials are abnormal, the specific situation should be reported to the next shift.
tidy	1. After completing the work, turn off the power, water, etc., tidy the workbench, collect the production material list and record sheet, return unused small raw materials, and clean up. 2. Write down the production situation of this class in detail. Including the configuration quantities of various formulas, abnormal situations and matters that need special explanation.

2. Extrusion

Operators must be familiar with the structural characteristics of the extruder they operate, the heating and cooling control instrument characteristics, machine head characteristics and assembly conditions, etc., in order to correctly grasp the extruder process conditions, operate the machine correctly, and extrude different products The models and specifications have different operating methods. During the production process, various process parameters should be checked regularly according to process requirements to see if they are normal.

※Preparation before starting up

1. Mold preparation and installation

1.1 According to the production arrangement, find out the mold for producing the product, as well as the related sizing sleeves, rubber rings, clamps, heating sheets, heating rings and operating tools (movable wrenches, hexagonal wrenches, screwdrivers, sandpaper, pry bars, etc.) .

1.2 Check all parts of the mold and sizing sleeve, and polish the parts that are in contact with the material;

1.3 Install the corresponding molds, sizing sleeves, rubber rings, clamps, heating sheets, heating rings, etc.;

1.4 Adjust the die gap of the mold and connect the power cord of the heating plate and heating coil;

 

2. Inspection of the extruder host

2.1 Check whether the water, gas, and oil circuits of the extruder are smooth, and whether there are any water, air, or oil leaks;

2.2 Turn on the power of the host, turn on the power switch of each heating unit, and set a relatively low temperature. Use a thermometer to check whether the temperature rise of each heating unit is normal and whether each temperature control instrument is normal, and then turn off the power switch of the heating unit;

2.3 Check whether the host vacuum pump is operating normally, whether the pipeline is smooth, and whether there is air leakage, water leakage or blockage;

2.4 Check whether the feeding device is operating normally.

2.5 After all the above steps are normal, turn on the heating switch of each section of the mold, and set the initial process temperature to around 120 degrees;

2.6 After the temperature of each section of the mold reaches the initial setting value, start setting the operating temperature; the following are the reference temperature setting values:

Barrel area 1 (feeding area) 185 degrees - 192 degrees

Barrel second zone (heating zone) 188 degrees - 195 degrees

Barrel three areas (plasticizing area) 175 degrees-182 degrees

Barrel four areas (feeding area) 160 degrees - 172 degrees

Converging core 160-172 degrees

Die head 175-185 degrees

Mouth mold 188 degrees-205 degrees

2.7 The above temperature values are for reference only, and the actual setting should be determined according to product quality requirements; after the temperature of each section of the mold reaches the set value, it needs to be kept warm for 30 minutes to ensure that each heating unit is heated evenly.

3. Inspection of extruder auxiliary machinery

3.1 Inspection of cooling water tank

1) Turn on the power switch of the cooling water tank;

2) Press the forward and backward movement switch of the cooling water tank to check whether the forward and backward movement of the water tank is normal;

3) Open the water inlet valve of the cooling water tank, turn on the water pump operation switch, check whether the water inlet and spray device are blocked, open the water outlet valve of the tank, and check whether the outlet water path is normal;

4) Turn on the sink vacuum pump and check the operation of the vacuum pump;

5) Check whether the level of the cooling water tank and its center line are in the same straight line as the center line of the extruder;

3.2 Tractor

1) Start the tractor and check whether the traction of the tractor is normal;

2) Press down and lift the switch of the tractor to check whether the air path is normal;

3) Check whether the track position of the tractor can be adjusted;

3.3 Check the cutting machine and pipe rack

1) Ordinary saw blade cutting machine

a) Adjust the height of the cutting fixture and perform cutting movements to check whether the movements are normal.

b) Adjust the position of the cutting stroke switch.

2) Planetary cutting machine

a) Check the cleanliness of the working room of the cutting machine, and turn on the power switch and air valve switch of the cutting machine;

b) Replace the clamps before and after the cutting machine;

c) Adjust the position of the cutting stroke switch and set the length of the product (should be slightly larger than the actual length);

d) Adjust the position of the tool so that it has just the right amount of feed;

e) Press the "Manual" cutting button to start pre-feeding, and check the actual feeding position of the blade from both ends of the cutting machine;

f) If the feed amount is not appropriate, you need to reset it according to the above steps until it is appropriate;

g) Take a 2-meter section of pipe with the same diameter as the pipe to be produced, place it on the clamps at both ends of the cutting machine, repeat e) and f) to observe the cutting action, and check the cutting effect, if the cutting effect is not good The feed amount needs to be readjusted;

3.4 Uniformly check whether the center lines of the extruder host, cooling water tank, tractor, cutting machine, and pipe rack are on the same straight line, otherwise they need to be adjusted to be on the same straight line;

3.5 Install the traction tube on the auxiliary engine;

3.6 Check the computer inkjet printer.

※Start up

1. Confirm again whether the temperature rise of the extruder is normal. After the temperature of the mold reaches above 150°C, re-tighten the fastening screws and bolts of the mold and readjust the wall thickness adjustment screws to make the die gap more uniform. ;

2. After the host temperature reaches the set temperature and is kept warm for 30 minutes (usually with a machine that can produce normally, in order to prevent the material from decomposing in the barrel, the machine can be started slowly when the host temperature is 10°C~20°C lower than the actual production temperature), then turn on the machine. Main engine oil pump, lubrication, cooling system and water system;

3. After confirming that the synchronization, screw, and feeding speed knob of the host are all at the "zero" position or the minimum position, start the host motor and accelerate slowly and evenly to about 5RPM;

4. Start the feeding motor of the feeding system, and make the feeding revolution run at a lower speed than the screw revolution, so that the feed is in a "hungry" state;

5. Depending on the size of the host current, increase the host and feeding speed appropriately. When increasing the speed, pay close attention to the change of the current. To avoid excessive current when accelerating, you should first increase the host speed and then increase the feeding speed; start the host speed at the beginning. 5 to 10 revolutions per minute, and the feeding speed is 3 to 6 revolutions per minute. At the same time, pay close attention to the changes in the host current and various indicating instruments: the starting current of the 90 machine cannot exceed 60A; the starting current of the 65 machine cannot exceed 40A; the starting current of the 55 machine The starting current cannot exceed 30A to avoid excessive pressure and damage to the machine. After the material comes out of the die, the speed can be slowly increased and the current amount can be increased appropriately.

6. Check whether the material is discharged evenly, and use the adjustment to adjust the wall thickness of the material evenly;

7. When the die discharge is uniform and the plasticization is good, it can be pulled into the shaping sleeve. The degree of plasticization needs to be judged based on experience. Generally, it can be judged based on the appearance of the extruded material, that is, the surface is shiny, free of impurities, foaming, scorch, and discoloration. The extruded material is stretched by hand to a certain level without burrs and cracks; it has a certain elasticity and is stretched. Strong tensile strength indicates good plasticization. If the plasticization is not good, the temperature of the formula, barrel, and die can be adjusted appropriately to meet production requirements.

8. Observe the plasticization of the material from the exhaust port, promptly turn on the water inlet switch of the vacuum pump and start its motor to evacuate the material in the barrel;

9. When the die discharge is uniform and the plasticization is good, use a knife to cut a small circular hole directly above the tube embryo and insert the tube embryo into the sizing sleeve. At the same time, turn on a small amount of cooling water and turn it on. Cool, and after the tube embryo comes out of the sizing sleeve, use a hook to connect the tube embryo and the traction tube together;

10. Start the traction machine and quickly adjust the traction speed to the appropriate speed (when small-diameter pipes do not need traction, estimate a traction speed in advance and let it start, and then directly pull the tube embryo from the sizing sleeve to the tractor manually, and then adjust its speed);

11. Close the lid of the cooling water tank, turn on the water pump and vacuum pump, cool the tube embryo in the water tank and maintain the vacuum degree in the water tank at 0.02~0.04Mpa;

12. According to the requirements of the product, adjust the coding content and other settings of the computer inkjet printer and start printing;

13. Start the cutting machine;

14. Gradually increase the screw and feeding speed of the extruder until the production speed reaches the production speed requirements, and start normal production.

15. During normal production, the number of unpackaged products on the tube rack shall not exceed the following: a. When packaging a single tube, D75mm and D110mm are 5 tubes, and D160mm and D200mm are 3 tubes; b. When wrapping with packaging rope, all products No more than 1.5 bundles (except during meals).

16. For safety reasons, during normal production, the operator must operate on the front of the extruder. No one is allowed to contact any part of the body with the movable parts of the machine.

17. Measurement and packaging records:

17.1 Use vernier calipers to measure the outer diameter, wall thickness, out-of-roundness and length of the tube embryo. And adjust the extruder operating conditions to control the size within the standard range. The wire pipe needs to use a pipe spring to test that the inner hole meets the requirements.

17.2 Take a sample and compare the color of the pipe to be consistent with the sample; weigh the pipe within the standard range; and perform simple physical property testing (the wire pipe is constantly folded in half; the drainage pipe pedal is brittle, etc.);

17.3 Take samples according to actual needs and submit them to quality control for further physical property testing;

17.4 Record operating conditions and data archiving;

17.5 Arrange packaging workers to pack according to packaging specifications and record production capacity;

18. Carry out shift handover work and records.

※Inspections and precautions during operation

1. Pay attention to whether the current change of the extruder host is stable. If the fluctuation is large, the feeding amount should be reduced. After the current is stable, the feeding amount can be slowly increased. If the feeding amount is reduced and the current remains high, the machine should be stopped for inspection;

2. Check whether there are any abnormal sounds in the gear reduction box, the main body and other transmission parts.

3. Check whether the fasteners are loose and whether there is any abnormal vibration during operation;

4. Check the oil temperature in the gear reduction box. The oil temperature should generally not exceed 60°C;

5. Check whether the temperature control, cooling, lubrication and vacuuming systems of the main engine and auxiliary engine are operating normally;

6. Observe whether the extruded material from the extruder is stable and uniform, and whether there are phenomena such as poor plasticization, overheating, discoloration, and unstable head pressure;

7. Keep records of the extruder’s temperature, pressure, host speed, feeding speed, host current, vacuum and other process parameters;

8. Do a good job in sanitation of the machine.

※Stop

1. Normal shutdown

1) First turn off the switches of each heating unit of the main machine barrel;

2) Close the discharge port of the hopper or adjust the feeding speed to "zero" and press the motor stop button;

3) Turn off and clean the main vacuum pump;

4) Gradually reduce the speed of the main machine screw, and after emptying the material in the barrel as much as possible, adjust the main machine screw speed to the "zero" position (if necessary, add cleaning material first and wait for the cleaning material to come out of the die) The screw can be stopped later);

5) Remove the mold in time and clean the material in the mold in time;

6) Start the screw again. After the material in the barrel is squeezed out, adjust the speed to the "zero" position, and turn off the oil pump, lubrication, cooling system, water system and main power supply of the main machine;

7) Close the water system, air system and related motors of various parts of the auxiliary engine;

8) Stop the printing action of the computer inkjet printer, turn off the power, and clean the print head with special cleaning agent;

9) Turn off the power of the auxiliary machine.

2. Abnormal shutdown (shutdown caused by accidents such as power outage): After shutdown, the screw and feeding speed of the host should be quickly reduced to "zero", and the switches of each heating unit and other auxiliary systems should be turned off. After the fault is resolved, press Start the machine according to the normal startup sequence. If the shutdown time is long, you need to remove the mold, clean it, reinstall the mold, and then start the machine.

3. Clean the auxiliary machinery of the extruder and do a good job of sanitation.

3. General faults of extruder and their troubleshooting methods

※The host current is unstable

1. Production reasons:

1. Uneven feeding.

2. The main motor bearing is damaged or poorly lubricated.

3. A certain section of heater fails and does not heat.

4. The screw adjustment pad is incorrect, or the relative position is incorrect, and the screw edge component interferes.

2. Processing method:

1. Check the feeder and troubleshoot.

2. Inspect the main motor and replace the bearings if necessary.

3. Check whether each heater is working properly and replace the heater if necessary.

4. Check the adjustment pad, pull out the screw and check whether there is any interference with the helical element of the screw.

※The main motor cannot start

1. Cause:

1. The driving procedure is wrong.

2. There is a problem with the main motor thread, and whether the fuse is burned.

3. The interlock device related to the main motor works

2. Processing method:

1. Check the procedure and drive again according to the correct driving sequence.

2. Check the main motor circuit.

3. Check whether the lubricating oil pump is started and check the status of the interlock device related to the main motor. The oil pump does not turn on and the motor cannot turn on.

4. The inverter's induction power has not been discharged completely. Turn off the main power supply and wait for 5 minutes before starting it again.

5. Check whether the emergency button is reset.

※The machine head is not discharging smoothly or is blocked

1. Cause:

1. A certain section of the heater does not work, and the material is poorly plasticized.

2. The operating temperature is set too low, or the molecular weight distribution of the plastic is broad and unstable.

3. There may be foreign matter that is not easily melted.

2. Processing method:

1. Check the heater and replace if necessary.

2. Verify the set temperature of each section, and negotiate with the technician to increase the temperature set value if necessary.

3. Clean and inspect the extrusion system and machine head.

※The main power starting current is too high

1. Cause:

1. Insufficient heating time and high torque.

2. A certain section of heater does not work.

2. Processing method:

1. Turn the car by hand when driving. If it is not easy, extend the heating time or check whether the heaters in each section are working properly.

※The main motor makes abnormal noise:

1. Cause:

1. The main motor bearing is damaged.

2. One of the thyristors in the main motor thyristor rectifier circuit is damaged.

2. Processing method:

1. Replace the main motor bearings.

2. Check the silicon controlled rectifier circuit and replace the silicon controlled components if necessary.

※The main motor bearing temperature rise is too high:

1. Cause:

1. The bearing is poorly lubricated.

2. The bearings are severely worn.

2. Causes:

1. Check and add lubricant. Check the motor bearings and replace if necessary.

※The machine head pressure is unstable:

1. Cause:

1. The main motor speed is uneven.

2. The feeding motor speed is uneven and the feeding amount fluctuates.

2. Processing method:

1. Check the main motor control system and bearings.

2. Check the feeding system motor and control system.

※Lubricating oil pressure is low:

1. Cause:

1. The pressure setting value of the pressure regulating valve of the lubricating oil system is too low.

2. The oil pump is faulty or the oil suction pipe is blocked.

2. Processing method:

1. Check and adjust the lubricating oil system pressure regulating valve.

2. Check the oil pump and oil suction pipe.

※The automatic screen changing device is slow or ineffective

1. Cause:

1. Low air pressure or oil pressure.

2. The cylinder (or hydraulic station) leaks air (or oil).

2. Processing method:

1. Check the power system of the screen changing device.

2. Check the sealing condition of the air cylinder or hydraulic cylinder.

※The safety pin or safety key is cut off

1. Cause:

1. The extrusion system torque is too large.

2. The connection between the main motor and the input bearing is not concentric.

2. Processing method:

1. Check the extrusion system to see if there is any metal or other objects stuck in the screw. When it first occurs, check whether the preheating heating time or heating value meets the requirements.

2. Adjust the main motor

※Sudden drop in extrusion volume:

1. Cause:

1. The feeding system fails or there is no material in the hopper.

2. The extrusion system enters and blocks the screw hard, preventing the material from passing through.

2. Processing method:

1. Check the feeding system or hopper material level.

2. Check and clean the extrusion system.