Extruder Drive, Components, Maintenance & Coating Lines

Extruder, which is currently used, is driven by ordinary motor for screw rotation through the reducer. It is only to reach the volume of screw speed and extrusion by pressing the button down. When changing varieties and specifications of products, the adjustment of the volume of melt extrusion or extrusion rate is necessary to readjust the screw speed; when the head pressure begins to change, it is necessary to readjust the screw speed for restoring the pressure; and the auxiliary line likewise, it is necessary to readjust the screw speed.

The screw speed of an extruder is an important process parameter to control the quality of extrusion rate and products. The pressure of material in the barrel increases as speed changes; while the shear strengthening of materials can improve the material temperature, and reduce melt viscosity, which is conducive to the full material and evenly mixed plastics. However, with high screw speed and fast rate of extrusion, melt in the mouth can cause flow instability. Therefore, it is necessary to put weight on the screw speed of a screw extruder.

An extruder drived by a switched reluctance motor has the following advantages:

(1) The speed of screw with long-term operation can be adjusted from zero to the highest speed in the range of stepless speed regulation, with high efficiency and smaller temperature rise of motor and controller.

(2) When an extruder begins to work, it is not possible to bring about the starting current, which is more than the original rated current 5 to 7 times. Meanwhile, there is no need to start an extruder with lower pressure, for the starting current can be smoothly increased as the current requires. The longer the start-up time is, the smaller the starting current will be. When the starting torque reaches 150% of rated torque, the starting current of the extruder is only 30% of rated current.

(3) There is no burning of motor and controller in an extruder with switched reluctance motor when three-phase input power is absent, and it can only lead to decrease of input electrical power output.

(4) During the operation of an extruder, there is no such an error that leads to short-circuit devices and burning controller, caused by lack of power devices.

(5) There is no belt drive in an extruder, but the screw speed can be adjusted accurately. Due to non-winding and rotor cage of the motor, it processes high mechanical strength and reliability of the transmission.

The screw of an extruder driven by switched reluctance motor can be operated through the gear of the motor, which can realize speed control under extrusion rate and the pressure. Generally, an extruder processes its own characteristics: wide range of speed adjustment, steady speed and high precision, small starting current, large starting torque. Due to a small heat-driven system, the occurrence of burning motor and controller is significantly reduced. In particular, it is very efficient to save energy, and the quantity of energy-saving is around 11%, compared with the variable frequency speed regulation system. Such an extruder has made a lot of progress: simple structure, digital control, stepless speed regulation, and high efficiency energy-saving.

In the previous studies, a driven method of extruders by variable speed switched reluctance motor drive is put forward. Based on analysis of present states of extruders, the method which could realize flexible numerical control by using variable speed switched reluctance motor to controlling the screw speed on velocity and pressure of extrusion was narrated. In addition, the advantage of saving energy and change of renovated extruders were analyzed. It was proved in practice that the renovated extruders had higher performances in efficiency and capability.

The main drive motor of extruder is mainly through the parallel shaft helical gear reducer to drive screw’s rotation and changes its running speed to constant torque speed under the fundamental frequency.

In the past, to consider the loaded starting torquethe, it needs to set the corresponding torque to upgrade alignmentthe when we use V/f control converter in extruder . If the torque’s elevation is set to high, the excitation will be too high in light loaded low-frequency which is easy to cause the serious heat of motor to effect the stable operation of equipments.

When used in screw extruder,the self learning function of vector control KV2000 converter can be used to observe the parameter of electric machine which can ensure good output characteristics in the low-frequency. Automatic energy-saving function of KV2000 can reduce the output current with the change of torque. This function can not only save energy, but also eliminate the possibility of the occurence of work hazard.

KV2000 converter has high-quality operational characteristics when it is used in extrusion equipment. This is decided by favorable product performance supplied by vector control converter.

High-frequency response provided by high-speed processor

Built-in processor of KV2000 converter provides high control accuracy, high-frequency response and good dynamic performance.The technological requirements of extrusion machine mainly is to control the constant pressure of exits. When the equipment just start working, it should take rotational speed control; when it reaches to the demand pressures, it should turn to pressure control. In switching process, there should be no impact, and high control accuracy of converter is demanded to veceive the pressure signal.

Over the years, it is a problem for stepless speed regulation in maintaining a large screw extruder torque, due to direction changing of DC motor for speed control, small torque of AC motor, and complex mechanical of speed control, continuously variable high cost and low efficiency of the hydraulic motor, along which many new ways come into being. There are many shortcomings of VVVF, such as low speed electric heat, large energy consumption, low efficiency, torque small, narrow speed range, and the phenomenon of electrical burn, reliability and low running so that people are unsatisfied with VVVF of screw extruder.

(1) Adjusting the speed regulator screw can be fully compensated pressure fluctuations of an extruder.

(2) When the speed regulator screw unchanged, the remaining length of polymer melt can be regulated relying on the stabilized voltage screw, which has a good effect on voltage regulation,but only the largest fluctuations is 83163% in the value of regulation.

(3) With lower price, the device is acceptable to the majority of enterprises

(4) It is convenient to clean the screw of an extruder, due to simple structure of the regulator device.

(5) The device is connected to the vertical extruder head, unlike the pressure fluctuation controller, which requires a direction change of the head.

A screw extruder may have one screw or multiple screws. The single screw extrusion machine is widely used in the process of plastics. A single screw extruder’s speed is around 100rpm and the speed of the twin screw extruder can be changed according to its application. High-speed twin screw extruder machines are mainly used for extruding mixtures of two kinds of material, at a rate of about 200-500rpm; When used at a low-speed, the twin screw extruder’s speed is about 10-40rpm, normally used for extruding sections.

For the co-rotating twin screw extruder, the shear component of it is kneading disk.2 (diamond) disk kneaders can be used, which has strong transmission capacity but not very strong shear capacity. At the same time it can reduce the shear by reducing the thickness of kneading disc and increasing the wrong angle of kneading block.

Some factories of foreign counties have designed a non-mating-type mixing elements called “multiple processing units” in screws. These elements can be used with the retro directive component and form a mixing box. This can make the materials annular flow in part of the screw so that the capacity of distribution of mixed can be increased, and high temperature caused by the over shear of materials can be availed at the same time. Besides, temperature can be controlled through reducing shear by lower screw speed and liquid cooling of the screw in the high shear zone.

According to the research, although reducing the screw speed will reduce the production capacity of the co-rotating twin screw extruder,it can reduce the extrusion volatility so that make the surface of the extrusion products smoother.

Although the screw of strong shearing cold feeding screw extruder has a more complex configuration and higher manufacturing costs, it has widely used in manufacture for its good exhausting affection. The operation principle of the screw of strong shearing cold feeding screw extruder is similar to that of cold feeding screw. But it has its own character.

The feeding parts of it use the large four-head screw configuration with angle shallow groove. This configuration has a lot of advantages: firstly, the strength and rigidity of the screw bottom have been improved;Secondly, the feeding ability of the large angle screw thread can be increased so that the imperfection that the shallow groove has a poor feeding ability can be made up and the transmission ability of rubber can be improved as well. In addition, multi-head screw thread can improve the feeding speed and is good for the stability and the feeding ability of various rubber materials in the extruding procession of rubber materials.

A twin screw extruder is not a simple combination of two single screws. In addition to the nuclear space between twin screw and barrel, there are side gap, the tetrahedron gap and calendaring gap. Mating-type twin screw extruder can be divided into full meshing engagement and a part one and the entire mating type can be further subdivided into conjugate and non-conjugated type. It is interrelated among different geometric parameters, such as screw diameter, screw head, screw edge width, the center distance. Due to the different geometric parameters, the horizontal spiral flow channel slot of twin screw extruder can be opened. It is geometric complexity that can distinct single screw extruder and twin screw extruder fundamentally.

Twin Screw Extruder , Double Stage Extrusion
Extrusion process and structures: the machine consists on an extrusion barrel with axial grooves which extend through solids conveying section and the feed section, which vanish at the exit end of the compression portion. The apparatus also consists on a helical thread extrusion screw possessing a maximum channel depth in the feed section, which depth shortens at the exit end. The plastic extrusion composition is going to be packed as a non-rotating mass by the process and apparatus so to fill the solids-conveying and compression sections and add the dead head pressure and extrusion productions to the motor.

Pin barrel cold feeding extruders are the breakthrough of cold feed extruders. It can be applied to 90% of the plastic material. Pin barrel cold feeding extruders use a streaming method rather than rely on a specially designed screw or setting intense heat of the section in screw.

This streaming method can turn the plastic material into the shunt-type screw of pin barrel cold feeding extruders , which has a good quality of mixing and a good consistency of temperature.

It is shown that in co-rotating twin screw extruder there are more design constraints because the flight flank angle has to equal the angle of intermesh. This is not the case for counter-rotating twin screw extruders. The various geometries possible in the two types of extruders are shown. Although the geometries used for co-rotating extruders are well known, the geometries for counter-rotating extruders are not well known. In fact, some of the geometries possible with counter-rotating extruders have not yet been made commercially available. The implications of the geometric analysis on actual extruder performance is discussed in detail.

Attention as follows

1. If the extruder makes an abnormal sound, please stop the extruder immediately and check it.

2. Empty is not allowed when operating the extruder.

3. In order to avoid the damage of the screws and barrel, please prevent the metal or other sundries falling into the hopper. You can take magnetic components or magnetic frame in the orifice of the hopper as a protector. In addition, screen the materials before putting into the hopper.

4. Emendate the temperature control instrument periodical to ensure the correctness of the modulation and the sensitivity of the regulation.

5. Please coat the antirust grease on the surface of the screws, barrel and some other place when stop using the extruder in long time. Pint-sized screws should be hand in the air or put in the special box. And level up the screws to avoid the damage and distortion.

6. Please keep a clean manufacture environment and do not let the impurity mixed with the material block up the filter pad. It will make a serious impact to the quality and quantity of the goods.

1. No contaminant is allowed in the raw material. Hard stuff like metal and stone debris is prohibited from entering into the hopper and twin screw extruder;

2. When open the hopper cover or vacuum cover, please be very careful not to take foreign material into the extruder or standard single screw extruder ;

3. Spare sufficient time for warming up the machine and keep the temperature at present value for, normally, two hours;

4. The machine is allowed to get initiated only from low speed and the non-load running time is not allowed to be beyond three minutes.

1.It is necessary to have an all-around check on the tightness of all screw bolts after the twin screw extruder (single screw extruder) has been running for a period of time.
2.If the main drive and heaters stop abruptly from an unexpected power cut, the temperature of all the barrels should be resumed up to the previous one and be kept for some time before the extruder is restarted.
3.When the gearbox keeps rolling for 500 hours, iron filings or other impurities should be washed off from gears and the lubricant oil inside should be replaced.
4.If the gauges or indicating hands stay at the maximal limit, please check the condition of sensors such as the thermal couple.

In order to protect the wheel box of the twin screw extruder, you must obey the followings:

1. The lubrication used in the twin screw extruder must be original No.150 Medium Pressure gear oil;
2. The normal operation oil leveler may not under the center oil leveler. Please supplement when it’s under the center oil leveler;
3. After the first 500 hours’ using, please change the lubrication;
4. Then, change the lubrication after every 3000 hours using;
5. Please clean the box and oil filter when changing the oil. First settle the new oil, put the upper layer of oil into the box to clean it and spill the oil. Then pour the new oil in;
6. Please lean the oil filter of the twin screw extruder per month during normal using period, and per week during running-in period. The way of cleaning: first find the oil filter and open it, then take out the dunghill in it.

Unstable current of the mainframe

Reasons:

(1) Uneven feed.
(2) There is a damage or bad lubricant effect in the axletree of the twin extruder’s main motor.
(3) Failure in some parts of the heater and it does not work.
(4) The trim plate of the screws is placed in a wrong place. Or interference from components because of the wrong phases.

Solutions:

(1)Check the feeder and eliminate the faults.
(2)Check the main motor and change the axletrees of the twin extruder if necessary.
(3)Check the heaters and replace the heaters of the twin extruder if necessary.
(4)Check the trim plates and pull the screws to ensure that there is no interference from components.

Reasons for Machine Start-up Failure

Reasons:
(1) There is a problem in the driving process of the twin screw extruder.
(2) There are problems in the thread, maybe the fuse is burnt out.
(3) The interlocking devices related to the main motor have stopped working.

Solutions:
(1) Inspect the working/driving process of the twin screw extruder which must be in compliance with the normal principle.
(2) Examine the electro circuit of the main motor.
(3) Check the lubricating oil pump is or not activated. After that examine the conditions of the interlocking devices related to the main motor. If the oil pump could not start, then the main motor cannot work.
(4) If the faradism in the transducer has not discharge totally, please close the main power source and wait for 5 minute, then restart the twin screw extruder.
(5) Check the emergency push button is reset or not.

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The steel pipe with coatings is widely used in the industries of oil, and gas transportation. The coating plant for steel pipes makes the coated steel pipes anti-corrosive. The anti-corrosion production line is applied to protect the pipes against rust and corrosion. With the traditional galvanized steel pipe, compared with light weight, corrosion-resistant, anti-aging is a long life, easy to transport and so on. The anti-corrosion steel pipe production line is a breakthrough in the industry.

Grinder Spring Loader
A part for and an means of coating the outer surface of a non-rotating pipe with a liquid comprised a fluid reservoir in order to contain fluid to beremoved from onto the surface of a pipe, and a pipe receiving chamber extending through and separate from the fluid reservoir. The apparatus further having a plurality of fluid intake openings positioned in the fluid reservoir includes a fluid application assembly for the intake of fluid from the appratus. The fluid intake openings are rotatable in a circular pattern within the reservoir about a path extending through the chamber. The apparatus has a plurality of fluid discharge exit in fluid intercourse with the fluid intake openings and directed towards the path. The fluid discharge outlets are rotatable harmoniously with the fluid intake openings about the path, depending on fluid entering the fluid intake openings from the reservoir is discharged through the fluid discharge outlets to coat the outer surface of a pipe being carried along the path.

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