Plastic Pelletizer Encyclopedia Information

Extruder according to the head material flow direction and screw centerline angle, the head will be divided into oblique angle head (angle 120o) and right angle head. The shell of the head is fixed on the machine body with bolts, the mold inside the head has a die core sitting, and fixed with a nut on the inlet port of the head, the front of the die core seat is equipped with a die core, and there is a hole in the center of the die core and the die core seat, which is used to pass through the core wire; there is a pressure equalization ring in the front of the head for equalization of pressure; the extrusion molding part consists of the die sleeve seat and the die sleeve, and the position of the die sleeve can be adjusted by the bolts through the support to adjust the relative position of the die sleeve on the core, which is easy to adjust the uniformity of the thickness of the extruded layer. 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 machine head is equipped with heating device and temperature measuring device.

Equipment Introduction

The main machine of plastic pelletizer is extruder, which is composed of extrusion system, transmission system and heating and cooling system. Vigorously develop renewable resources, turning waste into treasure.
⒈ extrusion system Extrusion system includes hopper, head, 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: is the most important part of the extrusion machine, it is directly related to the scope of application and productivity of the extrusion machine, made of high-strength corrosion-resistant alloy steel.
(2) barrel: is a metal cylinder, generally heat-resistant, high compressive strength, strong wear-resistant, corrosion-resistant alloy steel or alloy steel lined with composite steel pipe made. Cylinder and screw with the realization of the plastic crushing, softening, melting, plasticizing, exhaust and compaction, and to the molding system continuous and uniform delivery of rubber. Generally the length of the barrel is 15-30 times of its diameter, so that the plastic can be 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, and the side of the hopper is equipped with sight holes and calibrated measuring devices.
(4) head and mold: the head consists of alloy steel inner sleeve and carbon steel jacket, the head is equipped with molding die. The role of the head is to transform the rotary motion of the plastic melt into parallel linear motion, uniform and smooth introduction into the mold sleeve, and give the plastic to the necessary molding pressure. Plastic in the barrel plasticization compaction, through the porous filter plate along a certain flow channel through the neck of the head into the head molding mold, mold core mold sleeve appropriate coordination, the formation of the cross-section of the ever-decreasing annular gap, so that the plastic melt in the core line around the formation of a continuous and dense tubular cladding layer. In order to ensure that the head of the plastic flow reasonable, to eliminate the accumulation of plastic dead space, 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.

2. Transmission system The transmission system is to drive the screw, supplying the screw in the extrusion process required torque and speed, usually by the motor, reducer and bearings and other components.
3. Heating and cooling device Heating and cooling are necessary for the plastic extrusion process to be able to proceed.
   (1) 2013 extruder is usually used for electric heating, which is divided into resistance heating and induction heating, and the heating piece is installed in the body, neck and head sections. The heating device heats the plastic in the barrel from the outside to warm it up to reach the temperature required for the process operation.
   (2) The cooling device is set up to ensure that the plastic is in the temperature range required by the process. Specifically, it is to exclude the excess heat generated by the shear friction of the rotating screw, in order to avoid the high temperature of 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 However, the cooling at the hopper is to strengthen the conveying effect on the solid material to prevent the plastic particles from sticking and clogging due to the warming, and to ensure the normal operation of the transmission part.

Energy conservation

The energy saving of plastic pelletizer can be divided into two parts: one is the power part and the other is the heating part.
Power part of the energy saving: most of the use of frequency converter, energy saving is through the saving of the motor’s residual energy consumption, such as the actual power of the motor is 50Hz, and you actually only need 30Hz in the production is enough to produce, those excess energy consumption will be wasted, the frequency converter is to change the power output of the motor to achieve the effect of energy saving.
Heating part of the energy-saving: heating part of the energy-saving mostly electromagnetic heaters are used to save energy, the energy saving rate is about 30% -70% of the old resistance circle.

1. Compared with resistance heating, electromagnetic heaters have more than one layer of insulation, heat utilization increased.
2. Compared with resistance heating, electromagnetic heaters act directly on the material tube heating, reducing the heat transfer heat loss.
3. Compared with resistance heating, electromagnetic heater heating speed is faster than a quarter, reducing the heating time.
4. Compared with resistance heating, electromagnetic heater heating speed, productivity is improved, so that the motor is in a saturated state, so that it reduces the high power and low demand caused by the loss of electrical energy.
   The above four points is the electromagnetic heater, why can energy saving in plastic granulator up to 30% -70% of the reasons.

Plant equipment

Auxiliary equipment
Auxiliary equipments of plastic pelletizing machine mainly include wire release device, straightening device, preheating device, cooling device, traction device, meter meter, spark tester, and take-up device. Extruder set of different uses of its optional auxiliary equipment is not the same. Such as cut off, blow dryer, printing device.
Straightening device: the most common type of plastic extrusion waste is eccentric, and the core of 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 devices are: 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 is necessary for insulation extrusion and sheath extrusion. For the insulation layer, especially the thin layer of insulation, can not allow the existence of air holes, the core in the extrusion of the 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. The preheating temperature is subject to the constraints of unwinding speed, generally similar to the temperature of the machine head.
Cooling device
Molded plastic extrusion layer in the head after leaving the machine, should be immediately cooled and shaped, otherwise it will be deformed under the action of gravity. The cooling method usually adopts water cooling, and according to the different water temperatures, it is 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, the cooling water tank in sections placed in different temperatures of water, so that the product is gradually cooled down and shaped, PE, PP extrusion on the use of slow cooling, that is, through the hot water, warm water, cold water cooling in three stages.
Control system
The control system of plastic pelletizing machine includes heating system, cooling system and process parameter measurement system, which is mainly composed of electrical appliances, instruments and actuators (i.e. control panel and operation desk). Its main role is to: control and regulate the main and auxiliary drag motor, output speed and power in line with the process requirements, and can make the main and auxiliary coordinated work; detect and regulate the temperature, pressure, flow of plastic in the extruder; realize the control of the whole unit or automatic control.
The electrical control of the extrusion unit is broadly divided into two major parts of the transmission control and temperature control to achieve the extrusion process, including temperature, pressure, screw speed, screw cooling, barrel cooling, product cooling and outer diameter control, as well as hauling speed, neat rows of threads and ensure that the take-up reel from the empty disk to the full disk of constant tension take-up control.
⒈ extrusion machine temperature control of the host wire and cable insulation and sheath plastic extrusion 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, transferred to the plastic so that it melts extrusion, but also consider the screw extrusion of plastic when its own heat, so the temperature of the host should be considered as a whole, both to consider the opening and closing of the heater heating, but also take into account the extrusion heat spillover factors to be cooled by the screw, there should be 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.
Pake 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, 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 take the post-thrust limit value of the 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 rubber 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 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, if the speed of the haul-off device fluctuates greatly, it will also cause the change of the outer diameter of the cable. The screw and haul-off speed can be reflected by the corresponding instrument on the operating table, which should be closely observed when extruding to ensure high quality and high yield.
Control of Singing Outer Diameter
As mentioned above, in order to ensure the size of the outer diameter of the product cable, in addition to controlling the size tolerance of the core (core), the extrusion temperature, screw speed, traction device speed should be controlled to ensure that the measurement of the outer diameter of the control is a comprehensive reflection of the accuracy and level of the above control. 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.
Careful winding requirements of the tension control
In order to ensure that the winding at different line speeds, from the empty disk to the full disk work of constant tension requirements, I hope that the winding device has a storage line tension adjustment mechanism, or in the electrical consideration of constant line speed system and constant tension system of winding and so on.
Selection of the entire machine’s electrical automation control
This is the realization of high-speed extrusion line should have the process control requirements, mainly: boot temperature interlock; working pressure protection and interlock; extrusion, hauling two major components of the proportional synchronization control of the drive; take-up and hauling synchronization control; outside the diameter of the online detection and feedback control; according to a variety of different needs to be composed of components of the single machine and the whole tracking control.

Functional Uses

Function
Adopting special screw design and different configurations, it is suitable for the production of PP, PE, PS, ABS, PA, PVC, PC, POM, EVA, LCP, PET, PMMA and other plastics for recycling and color mixing granulation. The reduction gearbox adopts high torque design, realizing noiseless and smooth running and other properties. The screw and barrel are treated with special hardening treatment, which has the characteristics of wear-resistant, good mixing performance and high production capacity. The design of vacuum exhaust port or common exhaust port can exhaust the moisture and exhaust gas away during the production process, which makes the material output more stable and the pellets more solid, and ensures the excellent quality of the products.
Picture
Plastic granulator is mainly used for processing waste plastic film (industrial packaging film, agricultural mulch, greenhouse film, beer bags, handbags, etc.), woven bags, agricultural convenience bags, pots, buckets, beverage bottles, furniture, daily necessities, etc., applicable to most common waste plastics, it is the most versatile, widely used and popular plastic recycling processing machinery in the recycling industry of waste plastics.

Features
⒈All recycled materials can be produced after being classified, crushed and cleaned without drying, drying or sun-drying, and can be used both dry and wet;
⒉Everything from raw material crushing, cleaning, feeding to granulation is automated;
⒊Make full use of the high-pressure friction uninterrupted heating system to automatically heat production, avoiding continuous heating and saving electricity and energy;
⒋Adopt a split fully automatic power distribution system to ensure the safe and normal operation of the motor;
⒌The screw barrel is made of imported high-strength and high-quality carbon structural steel, which is durable;
⒍The appearance of the machine is beautiful and elegant. Color matching and spray painting can be carried out according to customer requirements;

Process parameters

Process flow
Raw material classification → raw material crushing and cleaning → automatic feeding and injection into the main machine for plasticization → auxiliary machine extrusion → water or air cooling → automatic pelletizing → bagging
Specifications
Screw diameter (mm) Length-to-diameter ratio (L/D) Maximum squeeze volume (Kg/h) Main motor power (Kw) Center height
Φ120 28:1 150 22 1000 Φ130 28:1 200 37 1000
Φ140 26:1 250 45 1000 Φ150 26: Φ 160 25: Φ170 25:1 700 95 1200

Crusher
There are many types of crushers for plastic products, including shear crushers suitable for crushing various types of plastic products, impact crushers and compression crushers suitable for crushing brittle plastic products. A widely used shearing crusher, it consists of a machine base, a crushing chamber, a hopper, a screen plate, a transmission mechanism, a rotating knife and a fixed knife.
The working method of the shearing plastic crusher is very simple: the shearing knife is composed of a rotating blade and a fixed blade, and the rotating blade is driven by an electric motor; the waste plastic to be crushed is sent to the crushing chamber from the hopper, and passed through the high-speed rotating cutter It is chopped into pieces and then flows out of the machine through the porous sieve plate.
Washing machine
The function of the cleaning machine is to remove the dirt and sediment on the plastic through the turning, stirring and water flushing of a pair of rotating stirring blades. Then the plastic fragments are removed from the water through the lifting device. Take it out and send it to the dehydration process.
Dehydrator
The structure of the dehydrator is simple, similar to the structure of the household dryer, and the working method is also similar. It mainly uses the centrifugal force of high-speed rotation to remove the water from the broken plastic in the drum.
Dryer
The plastic that has been crushed, cleaned and dehydrated still has a certain degree of moisture. The function of the dryer is to send it through the feeding port into a dryer with hot air circulation, allowing the water in the material to evaporate and dry the plastic to meet the extrusion requirements. Out of the granulation process needs.
Extruder
The extruder is a vented extruder. Its function is to remix the crushed, cleaned and dried plastic pieces through the extruder, heat them into a molten state, and then extrude and cut them into pellets.
Since the sources of waste plastic products are complex and there are many types of mixtures, and there are many volatiles, moisture and other components in the materials, it is more appropriate to use a vented extruder.
The exhaust-type extruder mixes and melts waste plastics. The shape of the materials used is relatively special, so a spiral forced feeding device is used. A filter is installed in front of the barrel, and the molten material is extruded through a porous plate and then pelletized. The waste material is recycled by extruding the strips, cooling them in a water tank, and then cutting them into pellets.

Operation details

First, the purpose
The purpose of standardized equipment operation and equipment maintenance is to ensure the normal operation of the equipment and extend its life, reduce maintenance costs and improve production efficiency.

2. Scope of application
   The operation guidance only applies to the production line equipment of TPR/EVA/PVC/masterbatch/font-less cable materials/rubber high-fill engineering materials produced by this company.
3. Special responsibilities
   Special equipment operators and maintenance personnel designated by the user are not allowed to operate in violation of regulations, and must operate the equipment skillfully. They must supervise irrelevant personnel not to approach, tamper with, or damage the equipment.
4. Operation details
   ⒈Turn on the power in sequence, set the temperature and pay attention to whether the heating is normal.
   ⒉Clean the hopper and other units, the inlet and outlet pipes, and check the oil level and lubrication status of each gear oil, machine oil, and high-temperature butter. The gear oil of a new machine should be replaced at least once every six months, and the moving parts should be lubricated at least once a week.
   ⒊When the temperature is close to the set temperature, prepare the materials and start the main motor in sequence.
   ⒋The temperature of the extruder must reach the set temperature. Only when the feeding device is turned on can the cleaning material or the residue in the raw material cleaning screw be poured in until the new material is squeezed out. Then the extrusion is paused and the filter plate and mold are quickly installed. head. Only then can the die head be closed. After closing the die head, turn on the main screw motor of the granulator. The operator should stay away from the die head at this time to prevent the hard material from clogging the die head and exploding and injuring people. Until the die head squeezes out the filament material, then close it. Pelletizing cover and connect the cutting knife holder and lock it.
   ⒌After the above operations are in place, turn on all fans in order > Vibrating screen > Pelletizer > The operation of the host machine.
   ⒍Adjust the granulator during normal granulation and use variable frequency speed adjustment to adjust the particle size. The screw must allow the pelletizer to rotate continuously before discharging. If it is water-cooled spray granulation, the pelletizing cover must be filled with water first, and finally the main engine must be turned on for formal production.
   ⒎Start the extrusion host and slowly and quickly adjust the frequency control of the host and the pelletizer according to the particle size requirements. Only by achieving coordination between the two can the cut particles be better uniform and the particle output be maximized.
   ⒏The operation sequence of stopping the operation is opposite to that of starting the production. First turn off the main engine drive, then turn off the power of the auxiliary machines in sequence, and finally clean the die head quickly to prevent the die head from cooling and clogging (Special note: the die head is discharged after each shift is stopped. The holes and filter plate must be completely cleared before reinstallation for production, otherwise there is a risk of explosion of the die head due to blockage).
5. Precautions
   ⒈It is strictly forbidden for unrelated personnel to talk to the equipment operator, and only one person is allowed to operate the button instructions on the electronic control panel;
   ⒉ Regularly check the insulation effect of wires and circuits, and always pay attention to the warnings on the machine warning signs;
   ⒊It is strictly prohibited for non-professionals to open the door of the power distribution cabinet before the power is cut off, and it is strictly prohibited to adjust the cutting tool before the pelletizer is completely stationary;
   ⒋When the moving parts and hopper are clogged, do not use your hands or iron rods, but only use plastic rods to handle them carefully;
   ⒌Be careful of burns when touching hot parts. When the kneader is working, it is strictly prohibited for staff to put their upper body into the barrel to inspect or remove materials;
   ⒍If there is a power outage during work, the circuits of each motor should be cut off and the materials in the machine should be cleaned up in time. The carbonization of the materials will affect the next production;
   ⒎When a machine malfunctions, stop the machine operation as soon as possible and do not make any claims on your own. And notify and wait for the maintenance personnel to check and repair or call to guide the maintenance;
   ⒏Prevent all factors from causing machine damage and work-related injuries; operate in strict accordance with standardized operating methods to reduce the occurrence of malfunctions or accidents.