Talking about the operation process of PVC extruder

January 06, 2021

The operation process of the PVC extruder is as follows:

First, mixing
1. Materials:
PVC resin, calcium powder, stabilizer, lubricant, impact agent, processing aid ACR (such as HF-100), weathering agent, whitening agent (toner).
2. Operation process:
Picking--ingredient--hot mixing--cold mixing--extrusion--traction--sizing--cooling--cutting--inspection--packaging--inbound
3. Mixing operation process:

Rules

Instructions

Precautions

Raw material inspection

1. Raw materials such as PVC powder and calcium carbonate should be used for 8 hours.

2. Check whether the raw material code and the identification material code are consistent with each other.

3. Check whether the appearance and hue of the raw materials are consistent with the existing materials in the workshop.

1. Whether the raw materials meet the production needs.

2. If there is any difference in the appearance and appearance of the raw materials, the product technology department shall be notified to verify.

Electronic scale inspection

1. Whether the operation is normal, whether the data can be zeroed, and whether the weighing is accurate.

2. Keep it tidy at all times.

1. If the tool, device function, or action is abnormal, it is disabled.

2. If the water, gas or electric switch is not normal, or the air pressure or water pressure is insufficient, the cause should be checked;

Mixer inspection

1. Check if there are any abnormalities in the water, gas and electricity switches of the mixer.

2. Turn on the switch and check if the movement of the mixer is normal.

3. Add lubricating oil at regular intervals to ensure normal lubrication of the mixing machine.

filler

Weighing error of ±200g per bag of packing weight.

1. Pay attention to the quality of raw materials, such as impurities and water.

2. The production material list is placed 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 per bag is ±100g.

Manual boot

1. Place the “Manual” and “Auto” switches in the manual position.

2. Start the hot mixing and low speed, and then transfer the high speed hot mix after 1 minute of feeding.

1. There is no abnormality in the work panel.

2. After the machine enters the automatic program, the switch must not be switched at will.

3, pay attention to the quality of ground or pulverized materials such as impurities, etc.

4. If there is any abnormality in quality, the supervisor and technical department should be notified in time.

5. Isolation and identification of abnormal materials, which can be processed after verification.

Feeding

1. Draw all the prepared materials and close the lid.

Automatic boot

1. The mixer automatically switches from low speed to high speed within the set time.

2. The machine enters the automatic running 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 when the heat is mixed and the valve is completely closed.

2. Observe the high and low speed conversion and temperature change of the hot pot.

Return material

1. After the hot mix is ​​automatically discharged into the cold mixing machine, it is put back into the material.

machine malfunction,

Power outage, gas, water

1. Open the hot mix cover and open the air valve at low speed.

2. Clear the hot pot after clearing the hot pot.

The pot has a hanging stop card after the electric brake is pulled to operate.

Mixing amount control

Mixing needs to consider the production schedule. In the same formula, the total amount of the mixture cannot exceed the amount specified in the production bill. When the planned demand is sufficient and the amount needs to be increased, the additional quantity is notified in time.

1. Maintain the principle of not mixing much.

2. When the backlog occurs after the material is mixed well, the identification card should be hung.

recording

1. For each mixing, the total amount of the material should be recorded on the record sheet.

2. Record the mixing process once for each batch of material.

1. When the content of the formula has been modified due to production needs, it must be clearly explained to the next class.

2. When the production and processing of raw materials is abnormal, the specific situation should be referred to the next shift.

sort out

1. After completing the work, turn off the power supply, water, etc., organize the workbench, clean up the production materials list and record sheet, and return the unused raw materials to clean and clean.

2. Write down the production situation of this class in detail. Includes configuration quantities for various recipes, anomalies, and special issues.


Second, extrusion
The operator must be familiar with the structural characteristics of the extruder being operated, the characteristics of the control instrument for heating and cooling, the characteristics of the head and the assembly conditions, so as to correctly grasp the extruder process conditions, operate the machine correctly, and extrude different products. The operation method of the model and specification is different. During the production process, it should be checked regularly whether the various process parameters are normal according to the process requirements.
※Prepare before starting
1. Mold preparation and installation
1.1 According to the production arrangement, find out the mold for the production of the product, and related sizing sleeves, rubber bands, clamps, heating sheets, heating coils and working tools (viving wrench, hex wrench, screwdriver, sandpaper, crowbar, etc.) .
1.2 Inspect the parts of the mold and sizing sleeve and illuminate the parts in contact with the material;
1.3 Install the corresponding mold, sizing sleeve, rubber band, clamp, heating sheet, heating coil, etc.;
1.4 Adjust the die gap of the mold, connect the heating wire and the power cable of the heating coil;
2, the inspection of the extruder host
2.1 Check whether the water, gas and oil passages of the extruder are unblocked, whether there are water leakage, air leakage or oil leakage;
2.2 Turn on the power of the main unit, turn on the power switch of each heating unit, set the relatively low temperature, check whether the heating temperature of each heating unit is normal with the thermometer, and whether the temperature control instruments are normal, turn off the power switch of the heating unit;
2.3 Check whether the operation of the main vacuum pump is normal, and whether the pipeline is unblocked, whether there is air leakage, water leakage or blockage;
2.4 Check that the feeding device is operating normally.
2.5 After the above steps are all normal, turn on the heating switch of each section of the mold, and set the initial process temperature to about 120 degrees;
2.6 After the temperature of each section of the mold reaches the initial set value, start setting the working temperature; the following are the reference temperature setting values:
One section of the barrel (feeding area) 185 degrees - 192 degrees,
The second zone of the barrel (heating zone) is 188 degrees - 195 degrees.
Three zones of the barrel (plasticized area) 175 degrees -182 degrees,
The four zones of the barrel (feeding area) are 160 degrees - 172 degrees.
Confluence core 160-172 degrees,
Die 175-185 degrees,
Mold 188 degrees - 205 degrees;
The temperature value above 2.7 is for reference only. The actual setting should be determined according to the product quality requirements. After the temperature of each section of the mold reaches the set value, it should be kept for 30 minutes to make the heating units evenly heated.
3. Inspection of the auxiliary machine of the extruder
3.1 Inspection of the cooling water tank
1) Turn on the power switch of the cooling water tank;
2) Press the front and rear movement switches of the cooling water tank to check whether the front and rear movement of the water tank is normal;
3) Open the inlet valve of the cooling water tank cooling water, open the water pump running switch, check whether the water inlet and the sprinkler are blocked, open the water outlet valve of the water tank, and check whether the water outlet is normal;
4) Open the sink vacuum pump and check the operation of the vacuum pump;
5) Check if the level of the cooling water tank and its center line are in the same line as the center line of the extruder;
3.2 tractor
1) Start the tractor and check if the traction of the tractor is normal;
2) Press the lower pressure of the tractor and lift the switch to check whether the gas path is normal;
3) Check if the track position of the tractor is adjustable;
3.3 Inspection of cutting machine and pipe rack
1) Ordinary saw blade cutting machine
a) Adjust the height of the cutting jig and do the cutting action to check if the action is normal.
b) Adjust the position of the cutting stroke switch.
2) Planetary cutting machine
a) Check the cleaning condition of the cutting machine working chamber, open the power switch and air valve switch of the cutting machine;
b) replacing the fixture 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 the correct amount of feed;
e) Press the “manual” cutting button to start the pre-feed and view the actual infeed position of the blade from both ends of the cutter;
f) If the amount of the infeed is not suitable, it needs to be reset according to the above steps until it is suitable;
g) Take a tube of about 2 meters in the same diameter as the pipe to be produced, place it on the clamp at both ends of the cutting machine, repeat e) and f) to observe the cutting action, and check the cutting effect, such as the cutting effect is not good. Then you need to re-adjust the amount of feed;
3.4 Check whether the center lines of the extruder main unit, cooling water tank, tractor, cutting machine and pipe rack are on the same line, otherwise they need to be adjusted to be on the same line;
3.5 Install the traction tube on the auxiliary machine;
3.6 Check the computer printer.
※ boot
1. Confirm that the temperature rise of the extruder is normal. After the temperature of the mold reaches 150 °C or above, re-tighten the fastening screws and bolts of the mold and re-adjust the wall thickness adjustment screws to make the die gap more uniform. ;
2. After the host temperature reaches the set temperature and is kept for 30 minutes (usually the machine can be normally produced, in order to prevent the material from decomposing in the barrel, the temperature of the main unit is 10 °C~20 °C lower than the actual production temperature) Main engine oil pump, lubrication, cooling system and waterway system;
3. When confirming that the synchronization of the main engine, the screw and the feeding speed control knob are all at the “zero” position or at the minimum position, the main motor is started and slowly and uniformly accelerated to about 5 RPM;
4. Start the feeding motor of the feeding system, and make the feeding rotation speed run at a speed lower than the screw rotation speed, so that the feeding material is in a "starved" state;
5, depending on the size of the host current, properly increase the host and feed speed, pay close attention to the change of current when increasing the speed, in order to avoid excessive current acceleration should first mention the host speed, then increase the feed speed; just start the host speed 5~10 rpm, feed speed is 3~6 rpm, and pay close attention to the host current and various indications: 90 machine start current can't exceed 60A; 65 machine start current can't exceed 40A; 55 machine The starting current should not exceed 30A to avoid excessive pressure and damage to the machine. After the out of the die, the speed can be slowly increased, and the amount of current is moderately increased.
6, check whether the discharge is uniform, use the adjustment to adjust the material wall thickness evenly;
7. When the die discharge is uniform and the plasticization is good, it can be pulled into the shaping sleeve, and the judgment of the plasticization degree needs to be based on experience. Generally, it can be judged according to the appearance of the extruded material, that is, the surface is shiny, free of impurities, no foaming, coke and discoloration, and the extrudate is drawn to a certain level by hand without burrs and cracks; The strength is strong, indicating that the plasticization is good. If the plasticization is not good, the formula, barrel and die temperature can be adjusted appropriately to meet the production requirements.
8. Observe the plasticization of the material from the exhaust port, open the water inlet switch of the vacuum pump in time and start its motor to evacuate the material in the cylinder;
9. In the case that the die discharge is uniform and the plasticization is good, a circular hole is cut with a knife directly above the tube blank, and the tube embryo is inserted into the sizing sleeve, and at the same time, a small amount of cooling water is turned on. Cooling, after the tube is out of the sizing sleeve, the tube embryo is connected with the traction tube by the hook;
10, start the tractor and quickly adjust the traction speed to the appropriate speed (small diameter pipe does not need to be towed, then estimate a traction speed and let it open, then directly pull the tube from the sizing sleeve to the tractor, then Adjust its speed);
11. Cover the lid of the cooling water tank, turn on the water pump and vacuum pump, cool the tube embryo in the water tank and keep the vacuum in the water tank at 0.02~0.04Mpa;
12. According to the requirements of the product, adjust the coding content of the computer inkjet printer, and other settings and start printing;
13. Start the cutting machine;
14. Gradually increase the screw and feed rate of the extruder until the production speed meets the production speed requirement and start normal production.
15. In normal production, the unpackaged products on the pipe rack shall not exceed the following quantities: a. D75mm for DFPmm, 5 for D110mm, 3 for D160mm and D200mm for b-package; b. When wrapped with packing rope, all products No more than 1.5 bundles (except when eating).
16. For safety reasons, the operator must operate on the front of the extruder during normal production. No one should touch any part of the body with the active part of the machine.
17. Measurement and packaging records:
17.1 The outer diameter, wall thickness, out-of-roundness and length of the tube blank were measured with a vernier caliper. And adjust the extruder operating conditions to make the size within the standard range. The pipe tube needs to be tested with a pipe spring to meet the requirements.
17.2 Take the sample contrast tube color is consistent with the sample; the pipe is weighed within the standard range; and the simple physical property test (continuous line pipe folding; drain pipe pedal brittleness, etc.);
17.3 Samples shall be handed over to the quality control for further physical property testing according to actual needs;
17.4 Record operating conditions and data archiving;
17.5 Arrange the packaging workers to package and record the production capacity according to the packaging specifications;
18, do a good job in the shift work and records.
※In-process inspection and precautions
1. Pay attention to whether the current change of the extruder main engine 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, the current should remain high.
2. Check the gear reducer, the main body and other transmission parts for abnormal sounds.
3. Check whether the fasteners are loose or not, and whether there is abnormal vibration during the operation;
4. Check the oil temperature in the gear reducer, the oil temperature should not exceed 60 °C;
5. Check whether the temperature control, cooling, lubrication and vacuuming system of the main machine and auxiliary machine are running normally;
6. Observe whether the extruded material of the extruder is stable and uniform, with or without plasticization, overheating, discoloration and unstable pressure on the head;
7. Record the process parameters such as temperature, pressure, main engine speed, feeding speed, main current and vacuum degree of the extruder;
8. Do a good job in the health of the machine.
※Shutdown
1, normal shutdown
1) first turn off the heating unit switches of the main unit barrel;
2) Close the discharge port of the hopper or adjust the feed speed to “zero” and stop the motor;
3) Close and clean the main unit vacuum pump;
4) Gradually reduce the speed of the main screw, and after the material in the barrel is drained as much as possible, adjust the screw speed of the main machine to “zero” position (if necessary, add the cleaning material first and the material to be cleaned out from the die) The screw can be stopped at the rear);
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 “zero” position, and turn off the oil pump, lubrication, cooling system and water system and main power supply of the main engine;
7) Turn off the waterway system, pneumatic system and related motors of each part of the auxiliary machine;
8) Stop the printing action of the computer printer, turn off the power, and clean the print head with a special cleaning agent;
9) Turn off the power of the auxiliary machine.
2. Abnormal shutdown (downtime caused by accidents such as power failure): After the shutdown, the screw and feeding speed of the main engine should be quickly reduced to “zero”, and the heating unit switches and other auxiliary systems should be turned off. After the fault is processed, press again. The normal boot sequence is turned on. If the downtime is long, the mold must be removed and cleaned before reinstalling the mold.
3. Clean the auxiliary machine of the extruder and do a good job in sanitation.

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