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1.Overview:
PS15-28 type counter-rotating twin-screw plastic extruder is a new product of our company. This machine has good plasticization, uniform mixing, high output, stable quality, high compactness of plastic products, wide application range and PVC powder. Direct extrusion molding and other features.
This machine is equipped with automatic temperature control, vacuum exhaust, screw core circulating oil cooling and other devices. The feeding method uses forced dosing. Both the main motor and the feed motor are steplessly regulated by a DC motor.
The machine is widely used, and the powdered plastic can be directly extruded into various plastic products of different cross sections after being heated. The maximum extrusion capacity of this machine is 750-800kg / hour.
2.Structure brief
This machine consists of nine parts (see Figure 1). Such as fuselage parts, transmission box parts, extrusion system parts, dosing parts, lubrication and cooling parts, constant temperature tank parts,vacuum exhaust parts, electric control box parts and protruding parts. The head parts are prepared by the user unit.
1.Body parts: The fuselage is made of low-carbon high-quality steel profiles. The cross-section of the fuselage adopts frame structure and ribs are set, which has good rigidity and small deformation. The DC main drive motor, transmission box, and extrusion system are directly installed on the upper part of the fuselage. And the lubrication and cooling components, the constant temperature oil tank, the vacuum exhausting parts, the electric control box, and the oil pipes and water pipes are installed in the lower part of the fuselage. The bottom hole of the fuselage is fixed by bolts to the foundation. At the front end of the fuselage, the three inlets of “inlet water”, “return water” and “exhaust” are arranged separately. After the standby device is positioned, the corresponding pipe can be connected.
2.Transmission box component: It is composed of the AC main drive motor and the transmission box through the plum-shaped elastic coupling. The AC motor adopts the Y4 series, with a power of 75kW and a rated voltage of 480V. It has a cooling blower and thermal protection device. It adopts all-digital three-phase stepless speed regulation and has a tachogenerator. The screw speed can be arbitrarily adjusted from 3-30.5r/min, and the speed value can be read directly from the computer screen. The total transmission ratio of the gearbox is 1:63.51, helical gear transmission (see Figure 2). The gearbox lubricant is made of No. 15 hyperbolic gear oil. The fuel quantity is subject to the oil standard on the gearbox and distribution box. In order to prevent the oil temperature from being too high, the lubrication and cooling components are equipped with an oil cooler, and the cooling method is water and oil circulation.
The distribution box consists of one shaft and two gear shafts. The shaft and gear shaft are made of high quality alloy steel, and the surface of the gear is carburized and quenched. The rear end of the shaft is connected with the internal spline of the output shaft of the reduction gear box. The output shaft of the reduction gear box is equipped with a 9039344 thrust spherical roller bearing, and the rear end of the other gear shaft is equipped with a series thrust roller bearing, two bearings. Withstand the axial force from the screw. The bearing capacities of the two thrust bearings are 500 kN and 430 kN, respectively.
3.Extrusion system components:
The extrusion component consists of a barrel and two screws. The two screw cores are made hollow, and a fuel pipe is installed therein, through which the heating oil is circulated for heating or cooling the screw. The oil temperature in the fuel tank will automatically adjust the control after setting the temperature value. The integral barrel is equipped with 7-segment electric heaters on the outer diameter, and 5 of them are equipped with 5 double blowers to cool the barrel. The process of heating the electric heater or cooling the fan is automatically adjusted by the computer after the set temperature value. The screw core heating oil temperature value and the barrel outer diameter electric heating temperature value can be reflected on the computer display screen.
Both the screw and the barrel are made of 38CrMoAlA high-quality alloy steel, which is made by heat treatment and surface nitriding. It has the advantages of high surface hardness, good wear resistance, strong corrosion resistance and long service life.
4.Dosing parts:
It consists of AC variable frequency motor, reducer, feed screw and hopper. The feeding screw is steplessly regulated, and the screw speed is determined by the rotation speed of the twin screw. That is to say, it increases as the twin-screw speed increases, and decreases as the twin-screw speed decreases. Once the balance is established, the feed screw feed rate is equal to the extrusion volume, which is equal to the work output. The feed screw and the extrusion screw can realize synchronous speed regulation, and the rotation speed can be directly displayed from the computer display. The gear unit is lubricated with No. 220 oil. The magnetic turret is attached to the hopper of the machine, which can effectively prevent the magnetic metal impurities such as steel screws and iron filings from being mixed into the barrel and the screw of the extruder with the plastic raw materials. Protect the barrel and screw from damage.
5.Constant temperature fuel tank components:
It consists of an electric motor, a gear pump, a fuel tank, an electric heater and a water cooler. This part can heat the oil at a set temperature value to heat or cool the screw. When the cold car is turned on, the high temperature oil that is introduced acts as a heating screw. After working for a period of time, the screw temperature is continuously increased due to the mixing and shearing of the plastic. In order not to overheat the screw, the high temperature oil acts as a cooling. Through the device, the plasticizing temperature can be made uniform, and the material is not easily decomposed, thereby improving the quality of the plastic product (see Figure 5). The oil temperature of this part can be automatically controlled and detected. The temperature value can be displayed on the computer display.
Lubrication cooling components:
It consists of an electric motor, a gear pump, a water cooler and a signal filter. The main function of this component is to forcibly lubricate the transmission system and cool the lubricating oil. When the oil filter is clogged, the signaling device sends out an alarm signal and sends a parking signal to ensure sufficient lubrication in the transmission box to avoid the entire transmission. The system is damaged.
6.Vacuum exhaust parts:
It consists of a water ring vacuum pump, a powder gas separator, an electromagnetic valve and a connecting pipe (see Figure 7). During the extrusion and plasticization process, the materials often entrain air, adsorbed water and volatiles generated at the molding temperature. These mixed gases are mixed in the material. If not discharged in time, the quality of the plastic products will be affected, and pores, bubbles and scars will appear on the surface and inside of the product. The function of this component is to suck the mixed gas from the exhaust port of the cylinder through a water ring vacuum pump and discharge it to the outside to ensure the quality of the product. The degree of vacuum can be adjusted by a plug valve, generally controlled to be below 0.07 MPa, or selected according to the extrusion process requirements. The system also has a solenoid valve on the water pump inlet pipe, the function of which is to open the valve when the vacuum pump is working, and the valve is closed when the vacuum pump stops working. The amount of water ingress can be adjusted by a plug valve.
7.The machine is not attached to the machine head parts, and is prepared by each user unit. Replacing different heads can squeeze out a variety of different plastic products.
8.If the user entrusts the unit to manufacture the machine head, it can be specified in the order contract.
9.AC motor speed control and electric heating control system. Please refer to the electrical control chapter in the manual.
10.This machine is equipped with accessory parts:
(1) A large hexagonal wrench is used as a nut on the disassembly lever.
(2) One piece of the top plate and the clamping block are used as disassembly screws.
3.electrical control system
The electrical control system is partly composed of an AC speed control system and a heating control system, which are assembled in an electrical control box.
Both the main screw motor and the feed motor have a wide speed range and high speed regulation. Both can individually adjust their speed and synchronize speed.
The heating system realizes the accurate control of the temperature of the heating part (constant temperature tank, barrel, head) through the computer operation screen and alarms in the over temperature (under temperature) state.
(1) DC speed control system
The main screw motor and the feed motor of the PS115-28 type counter-rotating twin-screw plastic extruder use DC motors.
Main screw motor：Y4-280 75kW 480V 140A
（Current limit before leaving the factory75kW 260A）
Excitation voltage：480V
Feed motor is variable frequency motor：130SZD03-CF 1.5KW
1500RPM 180V 10A
With 85CF01 speed motor：55V/2000RPM
In order to ensure that the two have a wide adjustment range, good adjustment performance, high speed regulation accuracy and strong anti-interference ability, the machine uses a thyristor double closed-loop speed control system.
The main screw motor speed control device adopts the all-digital AC inverter 590+ 380A of British Continental. If the drive fails, you can check the fault information. For details, please refer to the AC manual.
(2) Heating control system
The heater of screw hot oil and barrel heating zone 1 ~ 7 is powered by 220V/480V three-phase four-wire system, and the heater of the combined core is powered by 220V single phase.
| Segment name | Power（KW） |
| Screw hot oil heater | 6 |
| Barrel heating zone 1 | 12 |
| Barrel heating zone 2 | 12 |
| Barrel heating zone 3 | 10 |
| Barrel heating zone 4 | 10 |
| Barrel heating zone 5 | 80 |
| Barrel heating zone 6 | 8 |
| Confluent core | 4.5+2.5 |
At the right end of the control box, twenty sets of electric heaters and thermocouple plug-in devices are provided for the user to select (except for the combined core). Among them, the first to eighth groups have eight single-phase sockets, and the maximum power of the heater connected to each socket is 7 kW. Groups 9 to 14 have six three-phase sockets, and the maximum power of the heater connected to each socket is 10.5 kW. Groups 15-20 have six single-phase outlets, and the maximum power of the heater connected to each socket is 3.5 kW.
(3) Operational use of the electrical control system
Please read the operation manual and electrical principle drawing of the computer control system of this machine in detail, and understand the control logic.
4.Machine installation:
Select the lifting equipment and the cable according to the weight of the machine. Lift according to the lifting diagram (see Figure 4). It must be stable when lifting, and should not be shaken. Avoid vibration when placing the foundation to ensure that the machine parts are not damaged.
(1) First check the complete condition of the machine, check whether the random accessories are complete according to the list of accessories.
(2) The foundation of the machine must be solid, and the selected position must ensure the disassembly and maintenance of the machine.
(1) According to the machine foundation map (see Figure 3), pour the concrete foundation and correctly leave the anchor bolt hole position.
(2) After the foundation is dry, hang the main unit, place the anchor bolts, and adjust the block. Use the spirit level to adjust the main unit to a horizontal position, and then pour concrete into the anchor bolt holes. , adjust the horizontal position, tighten the anchor bolt nut, and fix the main unit.
(3) Install the electric control box wire and connect the power according to the electrical wiring diagram.
(4) Installation 1 1/4′′ tap water pipe is connected to the machine inlet pipe.
(5) Install the 1 1/2′′ return pipe and connect it to the machine return pipe.
(6) Install the 1 1/2′′ exhaust duct and connect to the machine exhaust pipe.
(7) Check the oil level of the lubricating oil in the gearbox, distribution box and feed reducer of the transmission system. If the liquid level is low, add the liquid level to the liquid level. The lubricating oil grades used are No. 15 hyperbolic gear oil and No. 20 motor oil.
(8) Clean up the whole machine. After a thorough inspection, after lubricating the lubrication, turn on the power and test the steering of the AC motor and each motor. Ensure that the power supply is correct.
(9) After the empty vehicle test preparation work is completed, the empty vehicle test can be carried out (the general idle vehicle test screw speed is not more than 10r/min, and the time is not more than 3 minutes.
5.Commissioning and operation:
1.Preparation work
(1) After referring to the instruction manual, it must be tested by a familiar craftsman.
(2) Check the cleanliness of the machine, especially check if there is any foreign matter in the hopper, and the exposed parts should be wiped clean.
(3) Check whether the pipe joints such as the fuel tank, oil passage, cooling water circulation system and vacuum exhaust system of the lubrication cooling system are loose. Whether the temperature meter and other meter pointers are in the zero position.
(4) Press the power supply and water source.
2.No-load test
(1) Start the main motor and observe if the motor is turning correctly (should the screw rotate from the inside to the outside). This machine is not allowed to have a screw reversal phenomenon. The screw idle time is not allowed to be too long (the general time does not exceed 3 minutes, the screw speed is not more than 10r/min). Before the no-load test, some lubricant can be added to the barrel to prevent the screw from scratching the inner wall of the barrel. After the correct direction of operation, the main motor should be turned off.
(2) Start the quantitative feeding motor, observe whether the feeding screw is turning correctly, and gradually adjust the speed from 0-30.5r/min. Finally return to the speed zero, turn off the motor.
(3) Start the vacuum pump motor and observe if the motor is turning correctly.
(4) Start the constant temperature fuel tank motor, observe whether the oil circuit is unblocked, and there is no leakage at the joint. The pressure of the oil system should be ≤0.8MPa. If it does not meet, it should be re-adjusted.
(5) Start the lubrication cooling system motor, observe whether the oil circuit is unblocked, and there is no leakage at the joint. The pressure of the oil system should be ≤0.8MPa. If it is not met, the oil filter must be removed for cleaning or replacing the oil filter.
(6) Open the cooling water system valve and observe the circulation and leakage of the cooling water.
(7) Turn on the barrel and the tank electric heating power supply, observe the heating situation and automatic insulation.
3.Load test
(1) According to the material performance, the heating stability of the barrel electric heating coil and the electric heating temperature of the constant temperature tank are selected according to the process requirements. After warming to the set value, the temperature was kept for 2 hours. Because the temperature rise rate of the constant temperature tank is faster, the barrel heating time can be later than the barrel temperature. Operate the single-speed control knob, first start the main motor, make the screw run at low speed, and then start the feeding motor. Both sides are slow to fast, ensuring speed matching. The amount of feed should not be excessive or insufficient. After the extruded product appears at the mouth of the barrel, it is slowly accelerated to the required number of revolutions. When the feed screw speed is properly matched with the twin-screw speed, synchronous speed regulation can be realized. At this time, only the synchronous speed control knob is needed to realize the speed increase and decrease. When the extruded product is normal, the vacuum exhaust pump motor can be activated to vent the product. Check the quality of the product, and further adjust the rotation speed to make the product quality and output meet the specified requirements.
(2) In the adjustment operation, make a number of records in time for the process reference.
(3) After the test run, the material must be completely squeezed. Then the barrel, screw and head are removed, or the cleaning material is added. After the original material is squeezed, stop.
6.Maintenance of the machine:
Special precautions for local operation
Copyright 2018 Wuxi Guangliang Plastic Machinery Co., Ltd
