Plastic machinery is a general term for various machines and devices used in the plastic processing industry. Some general-purpose machines and equipment such as fluid and solid conveying, separation, crushing, grinding and drying also play an important role in the plastic processing industry, so they are often listed as plastic machinery.

The design and manufacture of modern plastic machinery, in addition to relying on the development of mechanical engineering and materials science, is closely related to the progress of theoretical research on plastics engineering.

Product Categories

According to the production process of plastic products, plastic machinery can be divided into four categories : plastic compounding machinery, plastic molding machinery, plastic secondary processing machinery and plastic processing auxiliary machinery or devices. Plastic compounding machinery is used to manufacture various forms of plastic compounding materials, including kneading machines, plastic purifying machines (open mixers and internal mixers ), pelletizers, screening machines, crushers and grinders. Plastic molding machinery, also known as plastic primary processing machinery, is used for the molding of plastic semi-finished products or finished products, including compression molding machines, injection molding machines, extruders, blow molding machines, calenders, rotational molding machines, foaming machines, etc. Plastic secondary processing machinery is used for the reprocessing and post-processing of plastic semi-finished products or finished products, including thermoforming machines, welding machines, heat sealing machines, hot stamping machines, vacuum evaporation machines, flocking machines, printing machines, etc. Metal processing machine tools are also commonly used in plastic secondary processing. Plastic processing auxiliary machinery or devices are used to rationalize the plastic processing process, including automatic metering and feeding devices, automatic scrap recovery devices, automatic injection molded product removal devices, injection mold quick change devices, injection mold cooling machines, automatic thickness measuring devices, and raw material transportation and storage equipment. Such auxiliary machinery or devices have become an indispensable part of the automation of modern plastic processing processes.

The degree of perfection of plastic machinery directly affects the quality, output and cost of semi-finished or finished plastic products. Therefore, it must be able to adapt to the changes in temperature and stress during the plastic mixing and processing process, as well as the changes in the properties of the molten material caused by this, and adapt to special conditions such as chemical corrosion and mechanical wear. The specialization of plastic grades, the development of engineering plastics, the emergence of composite materials, and the development of technologies such as large-scale, lightweight and thin-walled plastic product structures require plastic machinery to achieve: set production for product production purposes; high speed, labor saving, and automation to improve product production efficiency; ensure the precision of product specifications and quality errors to the minimum; low energy consumption, small footprint, easy and safe operation and maintenance.

Prospects

Compared with metal, stone and wood, plastic has the advantages of low cost and strong plasticity. It is widely used in the national economy. The plastic industry occupies an extremely important position in the world today. The production of plastic products has been developing rapidly all over the world for many years. China’s plastic product output has always been at the forefront of the world rankings, and the output of many plastic products has ranked first in the world. China has become a major plastic product producer in the world. From 2001 to 2010, the average annual growth rate of China’s plastic product output remained above 15%, and in 2010, China’s total plastic product output reached 58.3 million tons.

Although China’s total consumption of plastic products ranks second in the world, its per capita plastic consumption is far behind that of developed countries. Data shows that in 2005, China’s per capita plastic consumption was only 29.5 kg, while the per capita plastic consumption in the United States, Belgium and Germany reached 171 kg, 169 kg and 155 kg respectively, which were 5.79 times, 5.73 times and 5.25 times that of China respectively.

As another indicator to measure the development level of a country’s plastic industry, the ratio of plastic to steel is only 30:70 in China, which is lower than the world average of 50:50, and even lower than the 70:30 in the United States and 63:37 in Germany. These gaps, on the other hand, show that China’s plastic products and plastic machinery industries have great room for development.

The Chinese plastic machinery market has attracted more and more attention from foreign companies. Many large international companies have continuously increased the depth and breadth of cooperation with Chinese plastic machinery companies, but more often they have adopted mergers or share purchases to occupy the Chinese plastic machinery market. For example, foreign companies such as Demag, Cornell and Hong Kong Zhenxiong have entered the Chinese market through joint ventures with chinese companies, or by setting up subsidiaries or representative offices.

Plastic Machine Main Types

There are many types of plastic machinery, which can be divided into three categories according to the processing technology: extruders, injection molding machines and blow molding machines.

plastic extruder

The extruder extrude the molten plastic through a fixed-shaped extrusion port under the action of the screw, and cuts it after being water-cooled and shaped under the action of the traction machine. It is mainly used for large-scale continuous production of various products with the same cross-section, such as pipes, rods, profiles, etc., and can also be used for plastic modification and granulation.

The basic mechanism of extrusion is simple – a screw rotates in a barrel and pushes the plastic forward. The screw is actually an inclined plane or ramp that wraps around the center layer. Its purpose is to increase pressure in order to overcome greater resistance. In the case of an extruder, there are three types of resistance to overcome: the friction of the solid particles (feed) against the barrel wall and the friction between them during the first few turns of the screw (feed zone); the adhesion of the melt to the barrel wall; and the internal logistics resistance of the melt as it is pushed forward.

It is divided into single screw extruder and twin screw extruder.

Injection molding machine

The injection molding machine is used to inject molten plastic into the mold, and the product is formed after cooling. It has a wide range of uses, and the places of use vary depending on the plastic. The injection molding machine is the most widely used processing machine in the plastic processing industry, and it not only has a large number of products.
It can be directly produced by injection molding machine, and it is also the key equipment in the injection stretch blow molding process.

Injection molding machine control system features:

1. Adopt advanced computer control from famous manufacturers;
2. Self-diagnosis fault function;
3. Directly input data such as pressure, speed, time, stroke and temperature;
4. LCD color display (as shown in Figure 1-1);
5. Centralized lubrication;
6. Pressure coupling oil circuit saves electricity;
7. 24V DC oil pressure directional valve coil will never be damaged;
8. Mould cooling water regulating device;
9. MCB insurance electric heating control;
10. Advanced computer control system, large screen display, simple operation interface, clean and easy to use;
11. High-precision electronic ruler stroke control, accuracy can reach ±0.1mm;
12. Improve reproducibility by using pressure and oil quantity feedback;
13. Mechanical, electrical and hydraulic triple safety devices can ensure the safety of the operator in any situation (PD60-PD148 optional hydraulic);
14. Improve reproducibility and operability by installing superior position sensors;
15. Use closed-loop control to achieve ultra-precision molding.

Plastic machinery is also known as plastic machinery, which can be confirmed from the positioning of plastic and plastic. In the eyes of people in the industry, plastic and plastic are the same thing. In the past, chinese factories were called plastic factories, while plastic factories in Hong Kong and Taiwan were called plastic companies. In order to facilitate communication with foreign businessmen, some foreign-invested enterprises in China basically hang the sign of Plastic Co., Ltd.

Blow molding machine

Blow molding is a common method for manufacturing hollow thermoplastic products, with the main products being cylindrical membranes and hollow containers. Blow molding machines can plasticize pre formed products by heating them up, and then enter the mold for blow molding. This method is mainly used for high-speed and high-yield PET bottles
BOPP bottle production, i.e. two-step process; Blow molding can also be combined with injection molding technology to become an injection pull blow molding machine, which is also a common method for producing containers in PET; Blow molding technology can also be combined with extrusion technology, and extrusion blow molding equipment has a wider range of applications and can produce a wider range of products, including multi-layer composite films and various polyolefin hollow containers, widely used in the food, pharmaceutical, and cosmetics industries.

Blowing Machine

The film blowing machine heats and melts plastic particles and then blows them into thin films.

There are many types of film blowing machines, including PE, POF and so on.

The new material blown out with brand new particles is of uniform color, clean and good bag stretching.

Some people also use recycled plastic bags to make particles. These particles are generally called old materials. They are usually gray when made into particles. Pigments are usually added when making bags. The bags are unevenly colored, brittle and easy to break, and the price is also relatively low.

Although they are recycled plastic bags, they are generally waste bags in the bag-making process and are very different from garbage plastics in the usual sense.

Composition

The film blowing machine consists of nine parts:

① motor, ② cylinder, ③ head, ④ die, ⑤ V plate, ⑥ pair of wheels, ⑦ smooth wheel, ⑧ pair of wheels 2, ⑨ wind

Raw materials

• LLDPE and LDPE is 160-180 degrees
• HDPE temperature is 210-230 degrees

The three most important factors for film blowing machine operation

• Temperature (machine temperature, room temperature)
• Dihelical
• Three cooling systems

Application

The film produced by the film blowing machine is suitable for various high-end film packaging. This kind of film can be widely used in light and heavy packaging due to its good barrier properties, freshness preservation, moisture resistance, frost resistance, oxygen isolation, and oil resistance. Such as various fresh fruits, meat products, pickles, fresh milk, liquid beverages, medical supplies, etc.

Calender

In plastic machinery, calenders usually form a complete calendering production line with leading devices such as material conveying, screening, metering, kneading and plasticating, subsequent devices such as decoupling, traction, embossing, cooling, thickness measurement, coiling, cutting, as well as transmission, monitoring and heating devices to produce soft and hard films, sheets, artificial leather, wallpaper and floor rolls and other products.

There are many ways to classify calenders in plastic machinery. The number of rollers can be divided into two-roller, three-roller, four-roller and five-roller types. The arrangement of the rollers can be divided into F, Z, S and L types.

Unlike other plastic machinery, the calender consists of a frame, rollers and their adjustment devices, a transmission system and a heating system (Figure 10 Plastic calender ). The frame is usually made of cast iron and is directly installed on both sides of the cast iron or cast steel machine base to support roller bearings, shaft crossing or roller pre-bending devices, roller adjustment devices, lubrication devices and other auxiliary devices. The rollers are made of chilled cast iron and cast steel, and their aspect ratio is selected according to the bending strength of the roller material, which is about 2.6 to 3.5. In order to compensate for the uneven thickness of the product caused by the bending deformation of the roller, the rollers are mostly made into waist drums, and the roller crossing device and roller pre-bending device can also be used to eliminate the uneven thickness of the product. Each roller is driven by a separate motor. The rollers are generally heated by steam or superheated water, and the temperature difference between the two ends is required to be no more than 1°C. Each roller has an independent automatic heating system. Modern calenders use roller bearings instead of traditional sliding bearings to save energy, improve bearing life and product thickness accuracy.

Depending on the specifications of the calender, the thickness of the produced soft PVC film is also different.

Internal Mixer

The full name is closed plastic mixer. It is one of the main equipment for plastic compounding. According to the working principle, it can be divided into two types: intermittent and continuous. The main structural parameters of the internal mixer are the rotor speed, diameter, length and total capacity of the internal mixer. Figure 1 shows the structure of an elliptical rotor intermittent internal mixer. It consists of a mixing chamber, a rotor, an upper push bolt (pressing device), a lower push bolt (unloading device), a heating and cooling device, and a transmission system. Its working principle is: the mixed material enters the mixing chamber from the hopper, and is subjected to constantly changing shearing, kneading and friction in the gap between the two relatively rotating rotors, the gap between the rotor and the inner wall of the mixing chamber, and the gap between the rotor and the upper and lower push bolts, so that the plastic generates heat and plasticizes, and is mixed evenly. Intermittent internal mixers have tended to be standardized and serialized.

The more commonly used ones are rotor type continuous internal mixer and twin screw mixer. There are many types of twin screw mixers. Generally, they have the ability to force material conveying, strong mixing function, short residence time of materials in the twin screw, and good self-cleaning performance of the twin screw, which can eliminate material accumulation in time and reduce material degradation, so their application is becoming more and more popular.

Thermoforming Machine

There are basically two types of thermoplastic sheet forming machines: roll-fed and sheet-fed. Roll-fed thermoforming machines are fed with roll- shaped sheets or are directly connected to a sheet extruder to form an assembly line. Sheet-fed thermoforming machines are named for the pre-cut sheets they are fed into.

Continuous sheet-fed thermoforming machines are quite popular. They can produce high-quality products at high speed and are supplied according to mold specifications. The most popular specifications are 60×60, 90×90, 125×106cm, etc. This type of thermoforming machine is often designed with a heating furnace that is 3 to 4 times the length of the longest mold. Most heating furnaces are electrically heated and installed on a frame that can be removed from the sheet conveying system. There are two main types of ovens: C-frame type and drop-door type. The thermoforming system is mostly driven by hydraulic or mechanical means. Single-sheet feeding thermoforming machines can be divided into two types: rotary type and shuttle type. Rotary thermoforming machines are often used for mass production of products. Commonly used are three-station standard thermoforming machines with a station rotation of 120°; there are also four-station thermoforming machines, that is, one heating station is added. The shuttle thermoforming machine has a forming station, the sheet is clamped on the clamping frame, and then reciprocates above the heating furnace. It is also designed as a double-station thermoforming machine consisting of two forming stations and a drying oven. This type of thermoforming machine has a wide range of processing adaptability.

Energy saving methods

Energy saving of plastic machinery can be divided into two parts: one is the power part and the other is the heating part.

Energy saving in the power part: Most of them use frequency converters. The energy saving method is to save the surplus energy of the motor. For example, the actual power of the motor is 50Hz, but you only need 30Hz in production. The excess energy is wasted. The frequency converter changes the power output of the motor to achieve energy saving.

Energy saving in heating part: Energy saving in heating part mostly adopts electromagnetic heater, and the energy saving rate is about 30%-70% of the old resistance coil.

1. Compared with resistance heating, electromagnetic heater has an extra insulation layer, which increases the utilization rate of thermal energy.
2. Compared with resistance heating, electromagnetic heater directly heats the material tube, reducing heat transfer and heat energy loss.
3. Compared with resistance heating, the heating speed of electromagnetic heater is more than one-quarter faster, which reduces the heating time.
4. Compared with resistance heating, electromagnetic heaters heat faster, which improves production efficiency and keeps the motor in a saturated state, reducing the energy loss caused by high power and low demand.

Maintenance Of Plastic Machine

Plastic machinery must be maintained during operation, and this maintenance must be carried out according to certain regulations, which is conducive to the operation of mechanical equipment. At the same time, maintenance according to the relevant requirements of the corresponding equipment safety and technical performance can effectively ensure the maximum safety of equipment and personnel.

Pre-installation inspection

The equipment is also composed of various components. Before installation, each equipment component should be inspected, including the main steel structure, bearings, bolts, etc. At the same time, the surface condition of the parts should be checked for corrosion resistance, etc. This should be recorded for future inspection.

Maintenance

When the equipment is operating normally, daily and regular maintenance must be carried out in accordance with rules and regulations. Daily maintenance is mainly responsible for cleaning, tightening, lubrication, adjustment, and anti-corrosion, which must be checked every day. Regular maintenance involves several maintenance and repairs of mechanical equipment within the prescribed time, with cleaning, lubrication, adjustment, disassembly, and inspection as the core content.

Overhaul requirements

The overhaul of equipment means that the equipment is seriously worn or damaged, and the performance of the machine has significantly decreased. This is the time to carry out an overhaul. If the power performance of the machine has significantly decreased, fuel consumption has increased, the operation is poor, the sound is abnormal, or the equipment can no longer perform its normal production performance, a comprehensive and thorough restorative repair method is adopted. At this time, the overhaul should be carried out according to regulations and the progress of the work should be arranged at the same time.

Equipment scrapping

During the overhaul process, there is a possibility of scrapping, which is implemented by maintenance professionals, and records and acceptance must be kept. For equipment that has exceeded or is close to scrapping, a certificate of overhaul acceptance should be provided before installation, and scrapping records should be kept.

Safety Certificate

With the continuous development of the plastic machinery manufacturing industry, the export volume of plastic machinery has continued to rise, and the export countries have also expanded from the original Southeast Asia and the Middle East to developed countries and regions such as Europe and the United States. In order to better cope with trade technical barriers and expand the international market share of Chinese plastic machinery, many plastic machinery companies have carried out safety certifications such as CE and UL. However, due to the lack of understanding of safety certification, many problems have arisen in the selection of certification agencies and the certification process, and even being deceived. As the only national plastic machinery inspection agency for plastic machinery, it shoulders the heavy responsibility of guiding the development of the industry. It is obligatory and necessary to use the professional and technical capabilities of the center to introduce safety certification knowledge to the majority of plastic machinery manufacturers, so as to promote the plastic machinery industry to better overcome trade technical barriers and improve international competitiveness. Considering that the safety certification that most companies need is the EU’s CE safety certification, this will be the focus of the following introduction.

CE is the abbreviation of Conformitē Europēeme (European Conformity Assessment) in French, which is a mandatory safety mark unique to the European Union. The basis for the EU market to assess whether a product can be circulated is whether the product has been affixed with the CE mark. Once a product is affixed with the CE mark, it means that the product meets the basic public safety, health, environmental protection and consumer protection requirements of the European Union. The European Union currently has 27 member states: Belgium, Cyprus, Czech Republic, Denmark, Germany, Greece, Spain, Estonia, France, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Austria, Poland, Portugal, Romania, Slovakia, Slovenia, Finland, Sweden and the United Kingdom, as well as Turkey, which is eager to join the European Union. The European Union has issued a total of 22 directives (directives can be defined as European laws, which are higher than the technical regulations of each member state), involving products such as: electronic and electrical products, mechanical equipment, simple pressure vessels, toys, construction products, personal protective equipment, medical equipment, gas stoves, pressure equipment, etc.

Plastic injection or compression molding machines with manual loading and unloading are classified as dangerous machines by the EU Machinery Directive due to their high degree of danger. They must be tested and approved by the Notified Body (EU authorized agency) before they can be affixed with the CE mark and sold and used in the EU.

Since the plastic machines produced in China have two modes of loading: automatic and manual, but rarely use fully automatic unloading by manipulators, the control computers of the plastic machines also have three modes of manual, semi-automatic and automatic, and such plastic machines are classified as dangerous machines. However, some certification or consulting companies do not actually have the EU authorization qualifications for plastic machines as dangerous machines, so they use two methods to deceive plastic machine manufacturers:

1. Help plastic machinery enterprises to make self-declarations. Certification companies help enterprises to make self-declarations through consulting and other services, but such declarations are difficult to pass the customs of EU countries, and the effectiveness of the certificates is extremely poor.
2. Limiting plastic machines to non-hazardous machines. Certification companies take advantage of the view of plastic machine technicians that fully automatic state means automatic unloading, confuse the definition of automatic unloading in the machinery directive, and limit plastic machines to non-hazardous machines. As a result, plastic machine companies’ future export products must be equipped with robots and specific plastic machine computers that are limited to fully automatic state, causing difficulties for manufacturers to export.

Industry Development

China’s plastic machinery industry started in the late 1950s. With the development of China’s petrochemical industry, China’s plastic machinery industry has gradually formed an independent industrial sector and has begun to take shape. China has become the world’s largest producer of plastic machinery parts.

The plastic machinery industry is developing very fast. The number of plastic machinery manufacturers in China has grown to more than 1,000, but there are only about 400 enterprises with a certain scale and strength. China’s plastic machinery industry has achieved leapfrog development after the “15th Five-Year Plan”. The scale of the industry has expanded, and the main economic indicators have increased year by year for eight consecutive years. Its development speed and main economic indicators are among the best in the 194 industries under the jurisdiction of the machinery industry.

The good development prospect of plastic processing industry will still be the driving force for the rapid development of China’s plastic machinery manufacturing industry. It is estimated that the annual average growth rate of China’s demand for plastic machinery will be about 6% in the future, reaching 14.5 billion yuan by 2010. In other words, China’s plastic machinery industry has great development potential and strong stamina, especially some models with high technological content, good performance and relatively moderate prices, such as super large, precise and special injection molding machines, low temperature and high power single screw extruders, multi-layer co-extrusion blow molding machines for producing high permeability resistance and heat resistance packaging materials, blow molding machines for producing industrial parts (auto parts, etc.), etc., all have good development prospects.

Industry Trends

1. Starting from the development of plastic products, we provide plastic machinery users with a full range of services including products, process formulas, equipment and after-sales services.
2. According to the user’s requirements, we design and manufacture suitable equipment to help the user solve his or her process difficulties.
3. Learn from the technological development of related industries in a timely manner and apply the latest scientific and technological achievements to the industry, such as the scientific and technological achievements of the electronics, communications, automobile and aerospace industries.
4. Keep pace with the progress of materials science and adapt new equipment to the processing of new raw materials.
5. Establish the concept that the key factor for users’ success or failure in market competition is equipment, and strive to ensure that equipment operates at a high speed, high efficiency, and energy saving.
6. There are cases of optimization and reorganization between enterprises, but there is no large-scale merger like that of large chemical enterprises.

Chinese trends

1. Breaking the original industry boundaries, plastic machinery has become a pattern for serving various industries and is developing in depth, and it is possible to transition to guiding market consumption, but it must be correct.
2. When conditions permit, we will continue to learn from foreign advanced products, processes and equipment through various means, including joint ventures and cooperation, to develop China’s plastic machinery and improve its technological level.
3. The chinese low-end and medium-end market capacity will be squeezed smaller and smaller. Some enterprises will split and reorganize, some enterprises will reduce the proportion of plastic machinery and turn to diversified operations, and some enterprises will avoid chinese vicious competition and open up foreign markets.
4. Social professional cooperation will gradually mature. Some manufacturers will focus on a certain local market to expand their business.
5. Some far-sighted and capable enterprises began to increase their investment in science and technology and accelerate the recruitment of high-quality management and scientific and technological personnel in order to further develop and strive to compete with the world’s powers.

More Introducing

The plastic is plasticized into a uniform melt by the extruder, and under the pressure established during plasticization, the screw is continuously extruded from the die head at a constant temperature, quantity and pressure. Most thermoplastics use this method. There are many different models and specifications of screw extruders, and the most commonly used extruder is the screw extruder. The extruder host drive using an AC inverter can fully meet the process requirements of the extruder and achieve the necessary process control indicators. After many years of actual operation in various places, it is stable, the product has strong adaptability and obvious economic benefits.

First, the main machine of the plastic extruder is the extruder, which consists of an extrusion system, a transmission system, and a heating and cooling system.

1. Extrusion system The extrusion system includes a screw, barrel, hopper, die, and mold. The plastic is plasticized into a uniform melt through the extrusion system and is continuously extruded out of the die by the screw under the pressure built up in the process.
2. Transmission system The function of the transmission system is to drive the screw and provide the torque and speed required by the screw during the extrusion process. It is usually composed of a motor, a reducer and bearings.
3. Heating and cooling device Heating and cooling are necessary conditions for the plastic extrusion process to proceed.

Second, auxiliary equipment The auxiliary equipment of the plastic extruder unit mainly includes the wire release device, straightening device, preheating device, cooling device, traction device, meter counter, spark tester, wire take-up device. The auxiliary equipment selected for the extruder unit is different for different purposes. For example, there are also cutters, dryers, printing devices, etc.

Third, Control system The control system of the plastic extruder includes a heating system, a cooling system and a process parameter measurement system, which is mainly composed of electrical appliances, instruments and actuators (i.e., control panels and operating tables). Its main functions are: to control and adjust the traction motors of the main and auxiliary machines, output the speed and power that meet the process requirements, and enable the main and auxiliary machines to work in coordination; to detect and adjust the temperature, pressure and flow of the plastic in the extruder; to achieve control or automatic control of the entire unit. The electrical control of the extruder unit is roughly divided into two parts: transmission control and temperature control, which realizes the control of the extrusion process including temperature, pressure, screw speed, screw cooling, barrel cooling, product cooling and outer diameter, as well as the traction speed, neat wire arrangement and constant tension wire collection control from empty to full on the wire reel. Among them, the control of the screw speed is the core of the whole set of equipment. The adjustment and stability of the screw speed is one of the important process requirements of the main engine transmission. The screw speed directly determines the amount of glue and the extrusion speed. In normal production, we always hope to achieve the highest speed and high production as much as possible. The extruder requires a large speed adjustment range from the start-up to the required working speed. In addition, the speed stability is required to be high, because the fluctuation of the speed will lead to the fluctuation of the extrusion volume and affect the extrusion quality. Therefore, if the traction line speed does not change, it will cause the outer diameter of the cable to change. Similarly, if the line speed of the traction device fluctuates greatly, it will also cause the outer diameter of the cable to change. The screw and traction line speeds can be reflected by the corresponding instruments on the operating table. Close observation should be made during extrusion to ensure high quality and high production.

Disadvantages of traditional control systems:

• (1) In the traditional screw extruder system, the screw is driven by a DC motor. In the case of direct drive, the screw is directly driven by a gearbox; in the case of indirect drive, the screw is driven by a belt and a traction plate. Traditional DC motors have certain disadvantages: for example, the brushes of DC motors need to be replaced once a month, and DC motors need to be cleaned frequently in dusty or corrosive environments. Sometimes, clean cooling air needs to be introduced from outside the workshop.
• (2) The disadvantages of indirect drive screw extruders are: belt slip, belts will cause certain energy losses, and more mechanical devices increase the possibility of wear and failure. The biggest disadvantages of DC motors are excessive noise, brush sparking, rotor pollution, high motor temperature, insufficient exhaust and motor vibration. Therefore, screw extruders using DC motors have higher maintenance costs and the initial cost of DC motors is also higher.

Fourth, the realization of frequency conversion transformation.

The inverters are used in extrusion equipment and have high-quality operating characteristics, which is determined by the good product performance that the vector control inverter itself can provide.

High performance CPU provides higher frequency response, and the high-speed CPU built-in in the frequency converter has high control accuracy and fast frequency response performance. The main process requirement of the extruder is to control the constant pressure at the outlet. When the equipment starts working, it controls the speed. When the required pressure is reached, it switches to pressure control. The switching process should have no impact and require high control accuracy of the frequency converter to respond to pressure signals.

Vector control provides high torque output at low frequencies. The main driving motor of the extruder is mainly driven by a parallel axis helical gear reducer to reduce speed and drive the screw to rotate. When the operating speed is changed below the fundamental frequency, it is a constant torque speed regulation. In the past, when using V/F control type frequency converters, the starting torque of the load needs to be considered, and the corresponding torque increase position needs to be set. If the torque increase is set too high, it will excite too much during low-frequency light loads, which can easily cause serious motor heating and affect the stable operation of the equipment.

By using a speed sensorless vector type frequency converter and using self-learning function to observe motor parameters, not only can the motor ensure good output characteristics at low frequencies, but the automatic energy-saving operation function of the frequency converter itself will reduce the output current with the change of torque. This not only saves energy, but also eliminates the possibility of the above-mentioned work hazards.

The torque limit and slip compensation are automatically set according to the motor structure, with a speed control accuracy of up to 0.1%.