Extruder I. Composition of plastic extruder:
The main machine of the plastic extruder is the extruder, which consists of extrusion system, transmission system and heating and cooling system.
1. Extrusion system Extrusion system includes screw, barrel, hopper, head, and die, plastic through the extrusion system and plasticized into a uniform melt, and in the process of establishing the pressure, by the screw continuous extrusion head.
(1) Screw: the most important part of the extruder, which is directly related to the scope of application and productivity of the extruder, made of high-strength corrosion-resistant alloy steel.
(2) barrel: a metal cylinder, generally made of heat-resistant, high compressive strength, strong wear-resistant, corrosion-resistant alloy steel or alloy steel lined with composite steel pipe. Cylinder and screw with the realization of the plastic crushing, softening, melting, plasticizing, exhaust and compaction, and to the molding system for continuous and uniform delivery of rubber, the general length of the cylinder for its diameter of 15 ~ 30 times, so that the plastic is fully heated and fully plasticized as a principle.
(3) hopper: the bottom of the hopper is equipped with a cut-off device, in order to adjust and cut off the flow of material, the side of the hopper is equipped with a view hole and calibration measurement device.
(4) head and mold: head by the alloy steel inner sleeve and carbon steel jacket composition, the head is equipped with molding die, the role of the head is to rotate the movement of the plastic melt into a parallel linear motion, uniform and smooth introduction into the mold set, and give the plastic to the necessary molding pressure, plastic in the barrel of the plastic compaction, through the porous filter plate along a certain channel through the head neck into the head forming mold, mold core mold set appropriate fit, the mold is not a good choice, but a good choice for the plastic, and the mold is a good choice for the plastic. The plastic is plasticized and compacted in the barrel, and flows into the head mold through the neck of the head along a certain flow path, and the core mold is properly matched to form a ring-shaped gap with decreasing cross-section, so that the plastic melt forms a continuous and dense tubular coating layer around the core line. In order to ensure that the head of the plastic flow reasonable, to eliminate the accumulation of plastic dead ends, often placed in the diversion sleeve, in order to eliminate pressure fluctuations in the plastic extrusion, there are also set up pressure equalization ring. The head is also equipped with mold correction and adjustment devices, easy to adjust and correct the concentricity of the die core and die set.
Extruder according to the head of the direction of the material flow and the screw centerline angle, the head will be divided into angled head (angle of 120o) and right-angle head. The shell of the head is bolted to the body of the machine, the mold in the head has a die core sitting, and fixed with a nut in the head inlet port, the front of the die core seat is equipped with a die core, die core and die core seat in the center of the hole, for the passage of the core; in the front of the head is equipped with an equalization ring for equalization of pressure; extrusion molding part of the mold by the die set seat and the die cover, the position of the die set can be adjusted by the bolts through the support to adjust the relative position of the die set to the core, easy to adjust the relative position of the extrusion packages. The position of the die sleeve can be adjusted by the bolt through the support to adjust the relative position of the die sleeve to the die core, which is convenient to adjust the uniformity of the thickness of the extruded layer. The head is equipped with heating device and temperature measuring device.
2. Transmission system The function of transmission system is to drive the screw and supply the torque and rotation speed required by the screw in the extrusion process, usually composed of motor, reducer and bearings, etc.
3.
3. Heating and cooling devices Heating and cooling are necessary conditions for the plastic extrusion process.
(1) Now the extruder is usually used for electric heating, divided into resistance heating and induction heating, heating pads installed in the body, machine neck, head parts. Heating device from the outside to heat the plastic inside the cylinder, so that it warms up to achieve the temperature required for the process operation.
(2) Cooling device is to ensure that the plastic is in the temperature range required by the process and set up. Specifically, in order to exclude the excess heat generated by the shear friction of the rotating screw, in order to avoid high temperatures so that the plastic decomposition, scorching or shaping difficulties. Barrel cooling is divided into water-cooled and air-cooled two kinds, generally small and medium-sized extruder using air-cooled is more appropriate, large-scale water-cooled or a combination of the two forms of cooling; screw cooling is mainly used in the center of the water-cooled, the purpose is to increase the rate of material solids transport, stabilize the amount of rubber, while improving product quality; but the cooling at the hopper, one is to strengthen the role of solid material transport, to prevent the plastic particles due to the temperature of the viscous plastic plugging The second is to ensure that the transmission part of the normal work.
Second, auxiliary equipment:
Plastic extrusion unit of auxiliary equipment mainly includes payoff device, straightening device, preheating device, cooling device, hauling device, meter meter, spark tester, take-up device. Extrusion unit with different uses of its optional auxiliary equipment is not the same, such as cutter, blow dryer, printing device.
Straightening device: the most common type of plastic extrusion waste is eccentric, and the core of the various types of bending is one of the important reasons for insulation eccentricity. In the sheath extrusion, the sheath surface scratching is also often caused by the bending of the core. Therefore, a variety of extrusion unit in the straightening device is essential. The main types of straightening device: roller (divided into horizontal and vertical); pulley (divided into a single pulley and pulley group); stranded wheel, both drag, straightening, stabilizing tension and other roles; pressure wheel (divided into horizontal and vertical) and so on.
Preheating device: core preheating for insulation extrusion and sheath extrusion are necessary. For the insulation layer, especially the thin layer of insulation, can not allow the existence of air holes, the core in the extrusion package before the high temperature preheating can be completely removed from the surface of the water, oil. For the sheath extrusion, its main role is to dry the cable core, to prevent the role of moisture (or moisture around the package cushion layer) so that the sheath in the possibility of air holes. Preheating can also prevent the plastic extrusion due to sudden cooling and residual internal pressure effect. In the process of extrusion of plastic, preheating can eliminate the cold line into the high temperature head, in contact with the plastic at the die mouth of the formation of the disparity between the temperature difference, to avoid fluctuations in the temperature of the plastic and lead to fluctuations in the extrusion pressure, so as to stabilize the amount of extrusion, to ensure the quality of extrusion. Extrusion unit are used in electric heating core preheating device, required to have sufficient capacity and to ensure that the temperature rises quickly, so that the core preheating and cable core drying efficiency. Preheating temperature is subject to the constraints of the release speed, generally similar to the head temperature can be.
Cooling device: molded plastic extruded layer in the head after leaving the machine, should be immediately cooled and shaped, otherwise it will be deformed under the action of gravity. Cooling is usually water cooling, and according to different water temperatures, divided into rapid cooling and slow cooling. Rapid cooling is cold water direct cooling, rapid cooling of plastic extrusion layer shaping favorable, but for crystalline polymer, because of the sudden hot cooling, easy to residual internal stress in the organization of the extrusion layer, leading to cracking in the process of use, the general PVC plastic layer using rapid cooling. Slow cooling is in order to reduce the internal stress of the product, in the cooling water tank in sections of the water placed at different temperatures, so that the product is gradually cooled down and shaped, PE, PP extrusion on the use of slow cooling, that is, after the hot water, warm water, cold water, three sections of cooling.
Third, the control system:
Plastic extruder control system including heating system, cooling system and process parameter measurement system, mainly by the electrical appliances, instruments and actuators (i.e., control panels and operating stations). Its main functions are: to control and regulate the dragging motors of the main and auxiliary machines, to output the speed and power in line with the process requirements, and to enable the main and auxiliary machines to work in coordination; to detect and regulate the temperature, pressure and flow of the plastic in the extruder; and to realize the control or automatic control of the whole unit.
The electrical control of the extrusion unit is roughly divided into two major parts, transmission control and temperature control, to realize the control of the extrusion process including temperature, pressure, screw rotation, screw cooling, barrel cooling, product cooling and outer diameter, as well as hauling speed, neat rows of lines and ensure that the take-up reel on the reel from the empty disk to the full disk of constant tension take-up control.
1. Extruder host temperature control
Plastic extrusion of wire and cable insulation and sheathing is based on the deformation characteristics of thermoplastics, so that it is in a viscous flow state. In addition to the requirements of the screw and barrel external heating, to the plastic melting extrusion, but also to consider the screw extrusion of plastic when its own heat, so the host temperature should be considered as a whole, both to consider the heater heating on and off, but also take into account the extrusion of the screw heat spillover factors to be cooled, there should be an effective cooling facilities. And requires the correct and reasonable determination of the location of the measuring element thermocouple and installation methods, can be read from the temperature control instrumentation to accurately reflect the actual temperature of the host section. As well as the requirements of the accuracy of the temperature control instrumentation with the system with good, so that the entire host temperature control system fluctuations in stability to achieve a variety of plastic extrusion temperature requirements.
2. Extruder pressure control
In order to reflect the extrusion of the head, the need to detect the extrusion of the head pressure, due to the domestic extruder does not have a head pressure sensor, generally on the screw extrusion thrust measurement instead of the measurement of the head pressure, the screw load table (ammeter or voltmeter) can correctly reflect the size of the extrusion pressure. Extrusion pressure fluctuations, is also one of the important factors causing extrusion quality instability, extrusion pressure fluctuations and extrusion temperature, the use of cooling devices, the length of continuous operation time and other factors are closely related. When the anomaly occurs, can be excluded from the rapid exclusion, must be re-organized production should be decisive shutdown, not only can avoid the increase in scrap, but also to prevent accidents. Through the detection of the pressure gauge readings, you can know the plastic in the extrusion of the pressure state, generally taken after the thrust limit value alarm control.
3. Screw speed control
Screw speed regulation and stabilization is one of the important process requirements of the host drive. Screw speed directly determines the amount of glue and extrusion speed, normal production always hope to achieve the highest possible speed and achieve high yield, the extruder requires screw speed from the start to the required working speed, the speed range available to use to be large. And the stability of the speed of high requirements, because fluctuations in speed will lead to fluctuations in the amount of extrusion, affecting the quality of extrusion, so in the case of traction line speed does not change, it will cause changes in the outer diameter of the cable. Similarly, such as the traction device line speed fluctuations will also cause changes in the outer diameter of the cable, screw and traction line speed can be reflected through the corresponding instrumentation on the operating table, extrusion should be closely observed to ensure high quality and high yield.
4. Outer diameter control
As mentioned above in order to ensure that the products of the outer diameter of the cable size, in addition to the requirements of controlling the size of the core (core) tolerance, in the extrusion temperature, screw speed, hauling device speed should be controlled to ensure that the measurement of the outer diameter of the control of the integrated reflection of the above control of the level of precision and accuracy. In the extrusion unit equipment, especially high-speed extrusion production line, should be equipped with online OD detector, at any time on the cable OD detection, and will exceed the signal feedback to adjust the traction or screw speed, correct the OD overrun.
5. winding requirements of the tension control
In order to ensure that different line speeds under the winding, from the empty disk to the full disk of the work of the constant tension requirements, I hope that the winding device has a storage line tension adjustment mechanism, or in the electrical consideration of the constant line speed system and constant tension system of the winding and so on.
6. The machine's electrical automation control
This is the realization of high-speed extrusion line should have the process control requirements, mainly: start-up temperature interlock; working pressure protection and interlocking; extrusion, hauling the two major components of the proportional synchronization of the drive control; take-up and hauling synchronization control; external diameter online detection and feedback control; according to a variety of different needs to be composed of components of the machine and the entire control of the tracking. The control of tracking.
Fourth, the classification of extruders:
Plastic extruder is divided into twin-screw extruder and single-screw extruder
The difference between the two kinds of extruders:
Single-screw machine and twin-screw machine: one is a screw, one is a two screws. Are driven by a motor. Power due to different screws and different. 50 cone double the power of about 20KW, 65 about 37KW. output and material and screw related, 50 cone double the output of about 100-150KG / H, 65 cone double about 200-280KG / H. Single-screw production is only half.
Extruder according to the number of screws can be divided into single-screw, twin-screw and multi-screw extruder. At present, the single-screw extruder is most widely used, suitable for general material extrusion processing. Twin-screw extruder has less heat generated by friction, the material is subjected to more uniform shear, the screw's conveying capacity is larger, the extrusion volume is more stable, the material stays in the barrel for a long time, and the mixing is uniform.
SJSZ series conical twin-screw extruder has the characteristics of forced extrusion, high quality, wide adaptability, long service life, small shear rate, the material is not easy to decompose, mixing and plasticizing performance is good, powder direct molding and other characteristics of the temperature self-control, vacuum exhaust and other devices. It is suitable for the production of pipes, plates, shaped materials and other products.
Single-screw extruder, whether as plasticizing granulation machinery or molding processing machinery occupies an important position in recent years, single-screw extruder has been a great development. At present, Germany produces large-scale pelletizing single-screw extruder, screw diameter of 700mm, output of 36t/h.
The main symbol of the development of single-screw extruder lies in the development of its key parts - screw. In recent years, people have carried out a lot of theoretical and experimental research on the screw, so far there are nearly a hundred kinds of screws, common separation type, shear type, barrier type, shunt type and wavy type and so on.
From the single-screw development point of view, although in recent years the single-screw extruder has been more perfect, but with the continuous development of polymer materials and plastic products, there will be more characteristic of the new screw and special single-screw extruder. In general, the single-screw extruder to high-speed, high-efficiency, specialization direction.
Twin-screw extruder feeding characteristics, suitable for powder processing, and better than the single-screw extruder mixing, exhaust, reaction and self-cleaning function, characterized by processing of thermally unstable plastics and **** mixing shows its superiority. In recent years, foreign twin-screw extruder has been a great development, various forms of twin-screw extruder has been serialized and commercialized, the production of more manufacturers, roughly categorized as follows:
(1) According to the relative position of the two axes, there are parallel and conical points;
(2) According to the two screw meshing procedures, there are meshing and non-meshing points;
(3) According to the direction of rotation of the two screws, there is a difference in the type and non-mesh;
(3) By the According to the direction of rotation of the two screws, there are the same direction and the opposite direction, and in the opposite direction, there are inward and outward; □
(4) According to the screw rotating speed, there are high speed and low speed;
(5) According to the structure of the screw and the barrel, there are the whole and the combination of the points.
On the basis of twin-screw extruder, in order to make it easier to process the poor thermal stability of the **** mix, some manufacturers have developed multi-screw extruder such as planetary extruder, etc.
V. Mechanical principle of the extruder:
In the raw material powder to add water or appropriate liquids, and constant mixing. The stirred material is extruded from the porous head or metal mesh with high extrusion pressure.
Usually the material is extruded with a screw after it has been placed in a cylindrical container. With the use of variable frequency technology, the pressure can be controlled so that the most suitable linear speed can be selected.
The principle of single screw extruder
The single screw is generally divided into three sections in effective length, according to the size of the screw diameter Pitch Depth of the screw to determine the effective length of the three sections, generally divided by one-third each.
The last thread in the mouth of the material is called conveying section: the material can not be plasticized here, but should be preheated, pressurized and squeezed, the old extrusion theory that the material is a loose body, and later proved that the material is actually a solid plug, that is to say, the material is extruded by the extrusion of a solid as a plug, so as long as the completion of the conveying task is its function.
The second section is called the compression section, the volume of the screw groove gradually become smaller and smaller, and the temperature to reach the degree of plasticization of the material, which produces compression by the conveyor section of the three, where the compression to one, which is called the compression ratio of the screw - 3:1, there are changes in the machine, the completion of plasticization of the material into the third section.
The third section is the measurement section, where the material to maintain the plasticizing temperature, just like the metering pump as accurate, quantitative delivery of molten material to supply the head, the temperature can not be lower than the plasticizing temperature, generally slightly higher.
Six, the extruder notes:
1, the extruder should be running in the right direction to avoid reversal.
2, do not run on empty stomach, must be warmed up with the material running, so as to avoid the occurrence of sticky bar (holding the shaft) phenomenon.
3, the extruder's feed port, bleeder hole is strictly prohibited to enter the iron and other miscellaneous, so as not to cause accidents, affecting production.
4, safe electricity, grounding wire.
5, the machine running inlet, outlet, belt, gears and other rotating parts of the prohibited hand touch.
6, the machine should be filled with lubricating oil before use, so as not to cause damage to the machine.
[Edit]Extruder operating procedures
Plastic extrusion line of various types of products, have their operating characteristics, a detailed understanding of its operating characteristics, in order to give full play to the effectiveness of the machine. Extruder is one of the types and its, grasp the operating points of the extruder, the correct and reasonable use of the extruder. The use of screw extruder including machine installation, adjustment, test run, operation, maintenance and repair and a series of links, its use has a general machine **** sex, mainly in the drive motor and speed reducer. But the screw extruder's working system that is the extrusion system, but also unique features, in the use of screw extruder should pay special attention to its characteristics.
Machine installation, adjustment, test drive in general in the extruder's instruction manual are clearly stipulated, here on the operation of the extruder, maintenance and repair is briefly described as follows:
Operators must be familiar with their own operation of the structural characteristics of the extruder, in particular, to correctly grasp the structural characteristics of the screw, the characteristics of the control instrumentation of the heating and cooling, the characteristics of the machine head and the assembly, etc. In order to correctly grasp the conditions of the extrusion process. In order to correctly grasp the extrusion process conditions, the correct operation of the machine.
When making different plastic products, the operation of the extruder is different, but also has its own similarities. The following is a brief introduction to the extrusion of a variety of products with the same operating steps and should pay attention to the operation of the extruder.
1, driving before the preparatory work
(1) for extrusion molding plastic. Raw materials should meet the required drying requirements, if necessary, further drying. And sieve the raw material to remove lumps and mechanical impurities.
(2) check the equipment in the water, electricity, gas system is normal, to ensure that the water, gas path is smooth, no leakage, the electrical system is normal, the heating system, temperature control, a variety of instrumentation is working reliably; auxiliary empty low-speed test run, observe whether the equipment is running normally; start the stereotypes table vacuum pump, to observe whether the work is normal; in the slippery parts of a variety of equipment refueling lubrication. If you find faults in time to eliminate.
(3) head and sizing set. According to the product varieties, size, select the head specifications. According to the following order to install the head.
2, drive
(1) can be driven after the constant temperature, before driving the head and extruder flange bolts should be tightened again to eliminate the difference between the bolt and the head of thermal expansion, tighten the head bolts in the order of diagonal tightening, the force should be uniform. When tightening the head flange nut, it is required to tighten and loosen all around the same, otherwise the material should be run.
(2) drive, choose to press the "ready to drive" button, and then connect the "drive" button, and then slowly rotate the screw speed adjustment knob, screw speed slow start. Then gradually speed up, while adding a small amount of material. When adding materials, pay close attention to the host ammeter and various indication of the indication of the meter head changes. The screw torque should not exceed the red mark (generally 65%-75% of the torque table). Before the plastic profile is extruded, no one is allowed to stand in front of the mouth mold to prevent injuries due to the bolt pulling off or the raw material being wet and foaming. After the plastic is extruded from the head die, it is necessary to cool the extruded material slowly and lead it onto the haul-off device and shaping die, and start these devices. Then according to the indication value of the control meter and the requirement of the extruded products. The parts will be adjusted accordingly, so that the whole extrusion operation to reach a normal state. And according to the need to add enough material, twin-screw extruder using metering feeder uniformly at the same speed.
(3) when the mouth mold material uniformity and good plastic can be hauling people shaping set. Plasticizing degree of judgment based on experience, generally based on the appearance of the extruded material to judge, that is, the surface has a glossy, unadulterated, no foaming, scorched material and discoloration, extrusion by hand to a certain degree of extruded material extruded to a certain degree of burrs, cracks, there is a certain degree of elasticity, which indicates that the material is well plasticized. If the plasticization is bad, you can adjust the screw speed, barrel and head temperature until it meets the requirements.
(4) in the extrusion production process, should be required by the process to regularly check whether the various process parameters are normal, and fill in the process record sheet. Check the quality of the profile products according to the quality inspection standards, and take timely measures to solve the problems found.
3, parking
(1) stop charging, the extruder will be squeezed out of the plastic, revealing the screw, turn off the barrel and the head of the power supply, stop heating.
(2) Turn off the extruder and auxiliary power supply, so that the screw and auxiliary machine stop running.
(3) Open the head coupling flange and disassemble the head. Clean the perforated plate and all parts of the head. Clean up in order to prevent damage to the inner surface of the head, the residual material in the head should be cleaned up by steel law, steel piece, and then use sandpaper to grind away the plastic adhering to the head, and lighten it, and apply machine oil or silicone oil to prevent rust.
(4) screw, barrel cleaning, remove the head, restart the host, add parking material (or crushed material), cleaning screws, barrels, screws at this time to choose a low-speed (sr/min or so) to reduce wear and tear. To be parking material crushed into powder completely extruded, available compressed air from the charging port, exhaust port repeatedly blowing out the residual granules and powder, until there is really no residual material in the barrel, down the screw speed to zero, stop the extruder, turn off the main power supply and the main valve of the cold water.
(5) extruder in the extrusion of safety items should be noted: electricity, heat, mechanical rotation and heavy parts of the loading and unloading. Extruder workshop must be equipped with lifting equipment, loading and unloading head, screw and other bulky parts to ensure safe production.
China's extruder technology innovation
In recent years, China's conventional extruders and production lines, with excellent cost-effective gradually popular in the international market. At the same time, China's continuous innovation in the field of advanced extrusion technology, to develop a variety of new extrusion products. Precision extrusion technology to adapt to the needs of high-precision processing
Precision extrusion molding can eliminate the need for subsequent processing means to better meet the needs of product applications, while achieving the purpose of reducing material costs and improving product quality. Nowadays, to meet the needs of precision direct extrusion of plastic products, a variety of mature technology has been introduced to the market, polymer melt gear pumps is one of the important means. This technology has been widely used in chemical fiber, film, profile, pipe, plate, cable, composite extrusion, pelletizing and other production lines.
The Institute of Rubber and Plastic Machinery of Beijing University of Chemical Technology, after years of systematic research on melt gear pumps, has successfully completed a series of development and development of plastic melt gear pumps, is now able to design and manufacture of plastic melt gear pumps such as 28/28 (center distance/tooth width), 56/56, 70/70, 90/90, etc., with a maximum difference in inlet and outlet pressures of up to 30MPa, which can meet the requirements of different production capacity, and has been used in the production of plastic melt gear pumps, and has been used in the manufacture of plastic melt gear pumps. The maximum pressure difference between inlet and outlet can be up to 30MPa, which can meet the requirements of different production capacity, and has been applied in practice and achieved good results. Institute of Rubber and Plastic Machinery, Beijing University of Chemical Technology, through an in-depth study of one body type gear pump extruder, designed and developed 115 one body type gear pump extruder.
Gear pumps on the rubber industry precision molding is also beneficial. In order to meet the domestic demand for rubber melt gear pumps, Beijing University of Chemical Technology and Beijing Aviation Manufacturing Engineering Research Institute, Hangzhou Chaoyang Rubber Company Limited cooperation, *** with the research and development of XCP150/100, XCP120/90 two models of rubber melt gear pump extrusion unit. This unit has ideal working characteristics, to ensure that the extrusion volume and gear pump speed into a linear relationship, can be realized on the output of precise control, improve the dimensional accuracy of the product.
Multi-layer *** extrusion technology mature development
Multi-layer composite technology using materials with medium and high barrier properties and other packaging materials composite, integrated barrier materials with high barrier properties and other materials cheap or special mechanics, thermal and other properties, to achieve a specific functional needs. *** The structural design of extrusion composite film gradually requires that it can systematically achieve the ideal realm of integrating function, technology, cost, environmental protection, safety, and secondary processing, thus realizing the possibility of maximizing the number of composite layers has become one of the technologies pursued by suppliers. Guangdong Jinming Plastic Equipment Co., Ltd. seven-layer composite film *** extrusion blow molding technology can be described as China's typical development in this field.
The seven-layer composite film *** extrusion blow molding unit using the key technologies include: two short and one long and pitch change screw plasticizing extrusion system, engineering analysis software on the vibration-induced plasticizing device optimization design, the plane valve additive die head and inclined valve additive die head, the internal cooling technology and the dual-air outlet negative pressure cooling technology, multicomponent loss-in-weight metering feeding, on-line film thickness precision control system, computer centralized automatic control system and bus control system, the computer centralized automatic control system and bus control system. Computerized centralized automatic control system and bus control (CANOPEN) technology.
At the same time the number of layers increased, to adapt to the special function of the film production technology is also one of the hot spots of the market development. Recently, Guangdong Shicheng company designed and manufactured a width of 3150mm PP environmental protection wood grain film casting production line. The production capacity of this line is more than 800kg/h. The screw is designed for high-speed shearing, mixing, and high-efficiency plasticizing screw, and the customer can directly use the high-filled calcium carbonate powder and inorganic pigment color powder, thus saving expensive raw material costs. The whole line can not only produce PP environmental protection wood grain film production, but also can be flexibly converted to produce other products, to broaden the customer's product range. In the trial production process of Shicheng Company, not only the production of beautiful PP wood grain film, but also the production of CPP film, PP stationery film and PP stationery sheet.
Innovative three-screw blending technology
Parallel co-rotating twin-screw extruders for blending and pelletizing production lines have become quite mature after the rapid development in the last 20 years or so. On the other hand, the traditional meshing disc and reciprocating screw extruders have been adapted to the needs of high filler blending, and the degree of industrialization has been increasing.
[edit]Extruder failure analysis
Extruder is a common plastic machinery and equipment, in the daily operation of the extruder in the process, the extruder will appear a variety of faults, affecting the normal production of plastics machinery, the following we are on the extruder failure analysis.
Extruder failure analysis: host current instability
1, production reasons:
(1) uneven feeding.
(2) The main motor bearing is damaged or poorly lubricated.
(3) A section of the heater is out of order and does not heat.
(4) Screw adjustment pad is not right, or phase is not right, element interference.
2, treatment:
(1) Check the feeder, troubleshooting.
(2) Overhaul 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 to check the screw for interference.
Extruder failure analysis: the main motor can not start
1, the cause:
(1) driving program is wrong.
(2) There is a problem with the main motor thread, whether the fuse wire is burned ring.
(3) The interlocking device related to the main motor works
2. Treatment:
(1) Check the program and drive again according to the correct driving order.
(2) Check the main motor circuit.
(3) Check whether the lube oil pump starts, and check the status of the interlocking device related to the main motor. The motor cannot be turned on without the oil pump.
(4) Inverter inductance is not discharged, turn off the main power and wait for 5 minutes before starting.
(5) Check whether the emergency button is reset.
Extruder Failure Analysis: head discharge is not smooth or clogged
1, the causes:
(1) The heater does not work in a certain section, the material is poorly plasticized.
(2) The operating temperature is set low, or the molecular weight distribution of the plastic is wide and unstable.
(3) There may be foreign materials that do not melt easily.
2. Treatment:
(1) Check the heater and replace it if necessary.
(2) Verify the set temperature of each section, and if necessary, consult with the processor to increase the temperature setting
(3) Clean and inspect the extrusion system and the head.
Extruder failure analysis: mains startup current is too high
1. Causes:
(1) Insufficient heating time and high torque.
(2) A section of the heater does not work.
2, treatment:
(1) driving should be hand disk car, such as not easy, then extend the heating time or check whether the section heater is working properly.
Extruder fault analysis: the main motor makes an abnormal sound
1, the cause:
(1) The main motor bearing is damaged.
(2) The main motor silicon controlled rectifier line in a silicon controlled damage.
2, treatment:
(1) Replace the main motor bearings.
(2) Check the SCR rectifier circuit and replace the SCR components if necessary.
Extruder fault analysis: the main motor bearing temperature rise is too high
1, the cause:
(1) bearing lubrication is poor.
(2) Severe bearing wear.
2. Causes:
(1) Check and add lubricant. Check the motor bearings and replace them if necessary.
Extruder fault analysis: head pressure instability
1, the causes:
(1) The main motor speed is not uniform.
(2) Uneven rotational speed of the feeding motor, fluctuations in the amount of feed.
2. Treatment:
(1) Check the main motor control system and bearings.
(2) Check the feeding system motor and control system.
Extruder failure analysis: low lubricating oil pressure
1, the reason:
(1) lubricating oil system regulator pressure setting is too low.
(2) Oil pump failure or suction pipe blockage.
2, treatment:
(1) Check and adjust the lubricating oil system pressure regulator.
(2) Check the oil pump, suction pipe.
Extruder fault analysis: automatic screen changer is slow or not working
1, the cause:
(1) low air or oil pressure.
(2) cylinder (or hydraulic station) leakage (or oil leakage)
2, treatment:
(1) Check the power system of the screen changer.
(2) Check the sealing of the cylinder or hydraulic cylinder.
Extruder fault analysis: safety pin or safety Jian was cut off
1, the cause:
(1) excessive torque of the extrusion system
(2) the main motor and the input bearing coupling is not centrifugal
2, the treatment method:
(1) check the extrusion system whether there is metal and other things into the jam screw. At the beginning of the occurrence, check whether the preheating warming time or warming value is
in line with the requirements.
(2) Adjust the main motor
Extruder Failure Analysis: Sudden drop in extrusion volume
1, the cause:
(1) feeding system failure or hopper no material
(2) the extrusion system into the hard stuck screw, so that the material can not be passed
2, treatment:
(1) check the feeding system or the hopper, the material is not available. Check the material level of feeding system or hopper
(2) Check and clean the extrusion system.