Knowledge about Cable Making Machine

The installation, adjustment and commissioning of the machine are generally specified in the operating instructions of the extruder. Here, the operation method, maintenance and repair of the extruder are briefly described as follows:

1、 Operating method of extruder

Operators must be familiar with the structural characteristics of the extruder they operate, especially the structural characteristics of the screw, the characteristics of the control instruments for heating and cooling, the characteristics of the head and the assembly conditions, so as to correctly grasp the extrusion process conditions and correctly operate the machine.

The operation methods of extruding different plastic products are different, but there are also similarities. The following is a brief introduction to the same operation steps and precautions when extruding various products.

1. Preparation before start-up

(1) Plastic used for extrusion molding. Raw materials shall meet the required drying requirements, and further drying is required if necessary. And the raw materials are sieved to remove agglomerates and mechanical impurities.

(2) Check whether the water, electricity and gas systems of the equipment are normal, ensure that the water and gas circuits are unblocked and leak free, whether the electrical system is normal, and whether the heating system, temperature control and various instruments work reliably; Low speed test run of the auxiliary machine with no load and observe whether the equipment operates normally; Start the vacuum pump of the setting table and observe whether it works normally; Lubricate the lubricating parts of various equipment. If any fault is found, it shall be removed in time.

(3) Mounting head and setting sleeve. According to the variety and size of the product, select the head specification. Assemble the machine head in the following order.

① The heads shall be assembled together and installed on the extruder as a whole.

② Before assembling the machine head, the grease applied during storage shall be wiped off, and the surface of the cavity shall be carefully inspected for bumps, scratches and rust spots. Necessary polishing shall be carried out, and then a layer of silicone oil shall be applied on the surface of the flow channel.

③ Assemble the plates of the machine head in sequence, apply high-temperature grease on the threads of the bolts, and then screw the bolts and the flange.

④ Place the perforated plate between the flanges of the machine head to ensure that the perforated plate is pressed without overflow.

⑤ Before tightening the fastening bolts of the connecting flange between the die and the extruder, the horizontal position of the die shall be adjusted. The level of the square die can be adjusted by the level gauge, and the level of the round die can be adjusted by the bottom surface of the die based on the rubber bottom surface of the shaped model.

⑥ Tighten the connecting flange bolts, tighten the head fastening bolts, install the heating ring and thermocouple, and note that the heating ring should be close to the outer surface of the head.

⑦ Install the setting sleeve and adjust it in place. Check whether the main machine, the setting sleeve and the center line of the tractor are aligned. After adjustment, tighten the fixing bolts. Connect the water pipes and vacuum pipes of the set sleeve.

⑧ Turn on the heating power supply to evenly heat the machine head and the machine. At the same time, open the cooling water at the bottom of the hopper and the gear box and the inlet valves of the exhaust vacuum pump. When heating, the temperature of each section shall be adjusted to 140 ° C, and the temperature shall be kept for 30-40min when the temperature rises to 140 ° C, and then the temperature shall be increased to the temperature during normal production. When the temperature rises to the temperature required for normal production, keep it for about 10min to stabilize the temperature of all parts of the machine, and then start the production. The holding time varies according to different types of extruders and plastic raw materials. Keep the temperature for a period of time to make the internal and external temperatures of the machine consistent, so as to prevent the instrument indicating that the temperature has reached the required temperature while the actual temperature is low. At this time, if the material is put into the extruder, the actual temperature is too low and the melt viscosity of the material is too high, which will cause the axial force overload and damage the machine.

⑨ Feed the raw materials for start-up into the hopper for use.

2. Drive

(1) The machine can be started after the constant temperature is reached. Before the start-up, the head and extruder flange bolts should be tightened again to eliminate the difference between the thermal expansion of the bolts and the head. The head bolts should be tightened diagonally and evenly. When tightening the flange nuts of the machine head, it is required that the tightness of the four sides should be consistent, otherwise the material will run away.

(2) To start, press the "ready to start" button, then connect the "start" button, and then slowly rotate the screw speed adjustment knob to start the screw speed slowly. Then gradually speed up and add a small amount of materials. During feeding, pay close attention to the indication changes of the host ammeter and various indicator heads. The screw torque shall not exceed the red mark (generally 65% - 75% of the torque table). Before the plastic profile is extruded, no one shall stand in front of the die to prevent injury accidents due to bolt breaking or wet and foaming of raw materials. After the plastic is extruded from the die, the extrudate shall be cooled slowly and led to the traction device and the setting die, and these devices shall be started. Then according to the indication value of the control instrument and the requirements of the extruded products. Adjust each part accordingly to make the whole extrusion operation reach the normal state. The twin-screw extruder uses a metering feeder to feed evenly and at the same speed.

(3) When the discharge of the die is uniform and the plastic is good, the tractor can be used to set the sleeve. The plasticization degree shall be judged by experience. Generally, it can be judged according to the appearance of the extruded material, that is, the surface is glossy, free of impurities, foaming, coke and discoloration. The extruded material is extruded by hand to a certain extent without burrs and cracks, and has a certain degree of elasticity. At this time, it indicates that the plasticization of the material is good. If the plasticization is poor, the screw speed, barrel and head temperature can be adjusted properly until the requirements are met.

(4) In the process of extrusion production, regularly check whether various process parameters are normal according to the process requirements, and fill in the process record sheet. Check the quality of profile products according to the quality inspection standards, and take timely measures to solve problems.

3. Parking

(1) Stop feeding and extrude the plastic in the extruder. When the screw is exposed, turn off the power supply of the barrel and head and stop heating.

(2) Turn off the power supply of extruder and auxiliary machine to stop the screw and auxiliary machine.

(3) Open the connecting flange of the machine head and disassemble the machine head. Clean the perforated plate and various parts of the machine head. In order to prevent damage to the inner surface of the machine head during cleaning, the residual materials in the machine head shall be cleaned with steel laws and steel sheets, and then the plastic adhered to the machine head shall be ground off with sandpaper, polished, and coated with engine oil or silicone oil for rust prevention.

(4) Clean the screw and barrel. After the head is removed, restart the main machine, add shutdown materials (or broken materials), and clean the screw and barrel. At this time, the screw is selected at low speed (about Sr / min) to reduce wear. After the stopped material is milled into powder and completely extruded, compressed air can be used to repeatedly blow out the residual granules and powder from the feeding port and the exhaust port until there is no residual material in the barrel. After that, reduce the screw speed to zero, stop the extruder, and turn off the main power supply and the main cold water valve.

(5) Safety items that should be paid attention to during extrusion include: rotation of electricity, heat and machinery, loading and unloading of heavy parts, etc. The extrusion locomotive room must be equipped with lifting equipment to assemble and disassemble heavy parts such as machine head and screw to ensure safe production.

2、 Maintenance of extruder

The screw extrusion system is maintained by daily maintenance and regular maintenance.

(1) Routine maintenance is a regular routine work, which does not account for the operating hours of the equipment and is usually completed during startup. The focus is to clean the machine, lubricate the moving parts, fasten the loose threaded parts, and timely check and adjust the motor, control instrument, working parts and pipelines.

(2) Regular maintenance is generally carried out after the extruder is shut down after 2500-5000h continuous operation. The machine needs to be disassembled to check, measure and identify the wear of main parts, replace the parts that have reached the specified wear limit, and repair the damaged parts.

(3) It is not allowed to run empty to avoid rough rolling of screw and machine.

(4) In case of abnormal noise during the operation of the extruder, stop the extruder immediately for inspection or repair.

(5) Prevent metal or other sundries from falling into the hopper to avoid damaging the screw and barrel. In order to prevent iron sundries from entering the barrel, magnetic absorbing parts or magnetic frames can be installed at the feeding port of the barrel to prevent sundries from falling. The materials must be screened in advance.

(6) Pay attention to the cleanliness of the production environment, and do not allow garbage and impurities to mix with materials to block the filter plate, which will affect the output and quality of products and increase the resistance of the machine head.

(7) When the extruder needs to be stopped for a long time, anti rust grease shall be applied on the working surfaces of the screw, the machine and the head. The small screw shall be hung in the air or placed in a special wooden box and leveled with wooden blocks to avoid deformation or damage of the screw.

(8) Regularly calibrate the temperature control instrument and check its adjustment correctness and control sensitivity.

(9) The maintenance of the reducer of the extruder is the same as that of the general standard reducer. It is mainly to check the wear and failure of gears and bearings. The reducer shall use the lubricating oil specified in the machine manual, and add the oil according to the specified oil level. If the oil is too small, the lubrication will not be reversed, and the service life of the parts will be reduced; Too much oil, high heat, high energy consumption, and easy deterioration of oil will also cause lubrication failure and damage to parts. The sealing gasket (ring) shall be replaced in time at the oil leakage part of the reducer to ensure the lubricating oil quantity.

(10) The cooling water pipe attached to the extruder is easy to scale on the inner wall and easy to corrode and rust on the outside. Careful inspection shall be carried out during maintenance. Excessive scale will block the pipeline, fail to achieve the cooling effect, and serious corrosion will cause water leakage. Therefore, descaling, anti-corrosion and cooling measures must be taken during maintenance.

(11) For the DC motor driving the screw rotation, the brush wear and contact shall be mainly inspected, and the insulation resistance of the motor shall be measured frequently if it is above the specified value. In addition, check whether the connecting wire and other parts are rusted and take protective measures.

(12) Assign special personnel to be responsible for equipment maintenance. The detailed records of each maintenance and repair shall be included in the plant equipment management file

Poor plasticization of wire and cable extruder raw materials and Solutions

Poor plasticization of ejector material

The poor plasticization of general extruder materials is mainly shown as follows: the extrusion cladding has toad skin; The plastic surface is dark, glossless, and has small cracks; There is an obvious seam at the glue joint of the extrusion cladding layer; The main reasons are:

a. The temperature control is too low, especially at the head;

b. Other plastic particles with different properties are mixed in the insulating or sheathing materials;

c. The screw rotation is too fast, and the plastic is not fully plasticized;

d. The plastic itself has quality problems.

In view of the above reasons, attention should be paid to the rationality of the temperature control of the extruder; The quality and qualified product name of the received materials shall be confirmed; We can not blindly pursue the output and improve the production speed of the ejector; Strengthen the storage of raw materials, especially in the plastic drying process; Reasonable die matching to enhance extrusion pressure and screw reflux.

In addition, plastic scorching is a common quality defect in the process of plastic extrusion, and its attention is shown as follows: the temperature display is extremely high; There is a lot of smoke and strong irritating smell at the die mouth of the machine head, and there is a popping sound in serious cases; The extruded plastic layer has coke particles; There are continuous bubbles at the glue joint; Note: the main reasons are:

a. Super high temperature control to reach the thermal degradation temperature of plastics;

b. The screw has not been cleaned for a long time, and the accumulated scorched materials are extruded with the molten plastic;

c. The heating or shutdown time is too long, so that the plastic in the barrel will be heated and decomposed for a long time;

d. The temperature control instrument is out of control or misaligned, resulting in high temperature decomposition;

e. The cooling system of the ejector is not opened, resulting in overheating of material shearing friction.

Therefore, in the production process of the extruder, it is necessary to strengthen the inspection of whether the heating and cooling systems work normally; The setting of the ejection temperature shall be determined according to the process requirements and the rotation speed of the screw; Reasonably control the heating temperature

Precautions when the extruder is not started for a long time

1. The soft water circulating cooling system of the unit shall be used for the operation of materials with large internal heat or sensitive shear heat. Before use, the water tank shall be filled with boiler soft water to the specified level. When the system is used for the first time, soft water shall be added to the specified level after the system is working, and an appropriate amount of soft water shall be added to the normal level.

2. Measure the heater with a megger, and the insulation resistance of the heater shall not be greater than 0.5 Μ Ω (not opened for a long time).

3. Clean the storage bin and hopper. After confirming that there is no foreign matter, fill the storage bin with materials. Various metering and feeding devices shall be calibrated on site according to industrial requirements, the feeding curve of each feeding device shall be given and the commissioning scheme shall be agreed.

4. Add lubricating oil into the tank to the middle position shown by the cursor, start the oil pump for test lubrication, and then add the oil to the middle position of the cursor.

5. Check that all upper and lower water pipes, oil pipes and vacuum pipes are unblocked and free of leakage. All control valves shall be easily adjusted.

6. Confirm whether the combination configuration of the screw barrel of the main engine is suitable for the material variety to be carried out. If it is obviously not suitable, conduct re combination adjustment.

7. Check whether the thermocouple, melt sensor and other detection elements are installed well.

8. Check the rotation direction of the main motor and the feeding motor, face the extruder main machine discharge head, and the main machine rotates clockwise.

9. For the operation requiring oil vacuum exhaust, clean tap water shall be added to the condensate tank to the specified water level. Close all valves of vacuum pipeline and condensate tank, and check whether the sealing ring of exhaust chamber is in good condition

10. The main machine of the extruder is cooled by soft water.

11. Check whether the electrical wiring is accurate and free of looseness.

Empty car test procedure of cable extruder

1、 Check whether the lubricating parts of each equipment and the quality of lubricating oil in the reduction box meet the standards, and supplement or add enough lubricating oil appropriately. The lubricating oil level is at the high line of the marking line (add l-ckc150 gear oil in the gear box)

2、 Control box circuit closing power supply

3、 Start the lubricating hydraulic pump, input the lubricating oil to each lubricating part, and check whether the working position of each lubricating oil is normal

4、 Check whether there are foreign matters in the hopper and barrel, and whether the magnetic frame in the hopper can be ready for work

5、 Jog the lubricating oil pump motor to check whether the rotation direction of the motor is the same as that required by the pump. If it is correct, start the lubricating oil pump formally to check whether the position of the lubricating oil spray oil is correct and whether there is leakage in the pipeline. After everything is normal, lubricate for 3 minutes

6、 Start the screw drive motor at low speed (the screw can not be stopped at high speed, and the screw shall be operated at high speed immediately when it is not fully started, and the knob must be reset to zero when it is stopped). Observe whether the pendulum needles of the ammeter and voltmeter on the control box are abnormal, and the power consumption shall not exceed 15% of the rated value (the idling time shall not exceed 3 minutes)

7、 Check whether the rotation direction of the screw is correct and whether there is friction between the screw and the barrel

8、 Check whether there is leakage in the oil, water and gas pipelines, and whether the connection mode and flow direction are correct

9、 Stop the screw rotation, exit the screw, and check whether the working surface of the screw and the barrel is scratched or grooved. If so, replace the equipment

10、 Screw work adjustment detection test, use tachometer to measure the maximum and minimum speed of screw drive shaft, and compare the instructions.

11、 Test whether the emergency stop button on the equipment works accurately and reliably

12、 Reinstall the screw after everything is normal

13、 The barrel is heated and the operation sequence is as follows:

(1) each section of the barrel shall be heated and the temperature control instrument shall be adjusted according to the extrusion process temperature requirements, and the special person shall be responsible for it. Other people shall not set and modify the process parameters without permission

(2) after heating to the temperature required by the process, keep the temperature constant for 1 hour and record the heating time

(3) use the mercury thermometer to detect the temperature of each section of the machine barrel, and verify the difference between the temperature of the adjustment instrument and the measured temperature of the mercury thermometer

(4) whether the heating resistance breaking alarm device in the heating device of the test machine barrel can give an accurate alarm

(5) turn off the heating power supply of the barrel, start the cooling device separately, check the working condition of the cooling system, and ensure that the water flow is smooth and there is no leakage.

1. Temperature setting: too high temperature will not only make the appearance too bright, but also easily lead to poor appearance due to too low burning temperature. Moreover, the discharge pressure will be uneven and eccentric due to too low temperature. More importantly, the machine will be damaged due to insufficient temperature and heavy load

2. The appearance is hairy and uneven, and the temperature is normal. It should be caused by the moisture of the rubber. When the rubber is poured into the hopper, the dryer should be opened, and the general temperature is about 60 ° C

3. Check whether the semi-finished products to be delivered meet the process requirements, check whether the cables are scratched and whether the arrangement is wrong

4. Compare the reserved sample line to confirm whether the color of the wire and the bright fog surface meet the requirements

5. When the outer diameter is unstable, it should be caused by uneven paying off tension or improper distance between inner and outer molds

6. The appearance is concave and convex, and the semi-finished product will shake more than once, which should be caused by the small inner eye

7. Set the spray content, check whether it is consistent with the instruction sheet and whether the spacing meets the requirements

8. Confirm whether the wire surface is smooth and whether the outer diameter is within the tolerance range

9. The sheath shall not be pushed out too tight or too loose, and the cable core shall not be loosened or squeezed. The minimum thickness is 0.5mm

10. The shutdown time should not be too long, otherwise the screw and the head rubber will be burnt

11. Confirm whether the take-up line is in good condition and the line spacing is appropriate

12. After continuous startup for 12 hours, the machine head needs to be disassembled and the filter screen needs to be replaced to avoid impurities in the wire

13. After the start-up is normal, check the outer diameter, appearance and spraying content of the wire at any time to confirm the quality of the wire

Every operator should understand that reducing the maintenance of the ejector, replacing parts and extending the service life of the ejector are important measures to reduce the cost of producing plastic products and improve economic benefits. The equipment can work in the best state for a long time, and the quality and output of plastics are stable, which are the basic conditions to ensure that the production enterprises have higher profits

The operator can work according to the operating procedures of the body and be responsible, which is the best maintenance and repair of the equipment. Therefore, new workers must learn and memorize the operating procedures of the machine before taking up their posts. Only after passing the actual operation assessment can they formally take up their posts and operate independently.

To work independently and become a qualified production operator, pay attention to the following matters:

(1) During the shift handover, the problems occurred in the production equipment of this shift shall be clearly handed over to the next shift for attention; Make shift handover records of the production volume, product quality and production tools of the shift.

(2) After the shift handover procedures are completed, the production quality of the products, the quality of raw materials for production and the quantity of production materials in the hopper of the ejector shall be checked annually. If any problem is found, it shall be put forward to the person in charge in time.

(3) Check whether the barrel and process control temperature of the ejector are within the process temperature range required by production. It can be adjusted according to the quality of the product and the operation experience.

(4) The patrol inspection shall be conducted around the production equipment for one week to check the working conditions of the transmission parts during the operation of the equipment, see whether the rotation is stable and normal, listen to the working sound for abnormalities, and check whether the temperature of the heating part is normal

(5) Check the voltage and current pointer of the main motor on the operation control box. The pointer of the ammeter should be within the normal rated current index.

(6) The screw of the production machine rotates smoothly, and the plastic products are ejected from the machine head at an even speed and smoothly; After a period of time, check the appearance quality of the products, or take some products to check whether the indicators of the products are qualified

(7) In case of sudden power failure during work, the switches of main motor, electric heating and feeding system shall be turned off immediately, and the speed regulating switch knob shall be adjusted to zero. When the power supply is restored, the barrel shall be heated and heated first. After reaching the process temperature, the barrel shall be kept constant for a period of time; Rotate the motor connecting belt by hand to test the resistance of the screw rotation; If it is easy, start the motor at low speed and start working. If the pointer of the ammeter exceeds the rated current value or the starting speed of the screw is not stable, stop the machine in time, find out the cause (possibly the temperature of the material in the barrel is low), find out the cause of the fault and start the machine after troubleshooting.

(8) If the shutdown time is long or the production is stopped, if the raw material in the barrel is polyacrylene, it can not be cleaned. Then, if there are polyamide and other raw materials in the barrel, the raw materials in the barrel must be cleaned; Then dismantle the screw and clean the adhesion between the screw and the barrel; After the residues in the barrel of the screw machine are cleaned, apply a layer of antirust oil, wrap the screw, and hang it vertically in a dry and ventilated

High temperature rise of main motor bearing of wire extruder:

Causes:

(1) poor bearing lubrication.

(2) The bearing is severely worn.

Treatment:

(1) check and add lubricant.

(2) Check the motor bearing and replace it if necessary.

Unstable head pressure of wire extruder

Causes:

(1) the speed of the main motor is not uniform.

(2) The rotation speed of the feeding motor is uneven, and the feeding amount fluctuates.

Treatment:

(1) check the main motor control system and bearing.

(2) Check the feeding system motor and control system

he extruder is a common mechanical equipment in the electronic industry. In order to better maintain the plastic granulator in a good operating state at all times and ensure efficient production and operation, it is necessary to carry out maintenance and cleaning work on time. There is no mistake in the text about maintenance and cleaning. So let's master several cleaning methods of the extruder screw.

A、 Epoxy resin cleaning method:

Alkyd resin or epoxy resin glue is selected for cleaning. Generally, it is used for cleaning of new machines and equipment or after the extruder is applied for a period of time. Because some raw materials remain on the screw or barrel, the extrusion rate of raw materials slows down, and the color deviation of the color change type is very large, this type of method can be selected.

B、 Disassembly and cleaning:

1. Manual production: add washing material from the opening until the color of the extruded material strip is the same as that of the washing material powder, stop feeding, discharge the raw materials, and stop the screw rotation of the twin-screw extruder;

2. Open the feed pipe of the screw extruder and gradually remove it;

3. Rotate the screw of the twin-screw extruder and remove the packing, discharge the residual washing material in the barrel and remove the packing;

4. After shutdown, check whether the screw is clean and tidy, and manually eliminate the finished products on the screw. Re install the screw; Add new material to clean the residual washing material in the barrel and stop the screw rotation;

5. Install the packing and material pipe of the twin-screw extruder, and carry out the actual cleaning operation of the twin-screw extruder.

C、 Fire burning method:

It is a common and effective method for plastic granulation enterprises to remove the plastic fixed on the screw by baking or burning. After the application of the screw, the gas furnace shall be selected for cleaning. At this time, the screw contains the heat from the production and processing, so the heating capacity of the screw is still uniform.