The plastic processing industry also uses a variety of auxiliary equipment including chillers, pulverizers, dryers, feeders, mixers, temperature controllers, cooling towers, and so on.
Plastic processing industry also often uses cooling water and cooling devices. At present, there are many domestic manufacturers of cooling machines, and the products can basically meet domestic needs. Industrial refrigeration units mainly include integrated refrigeration units, mobile refrigeration units and central refrigeration units. Integrated refrigeration units include air-cooled refrigeration units, of which air-cooled units are divided into integrated condensers, remote condensers and external systems. The condenser of the indoor air-cooled unit can be used for heating in the winter, and exhaust ventilation in the summer. Outdoor units save space in the plant.
More and more companies are using central refrigeration systems. The central refrigeration system can meet the user's requirements for high efficiency, customization and a wide range of refrigeration. For example, the Canadian Berg company can provide indoor air-cooled, remote air-cooled and water-cooled refrigeration systems with cooling capacity from 10 tons to 200 tons. They can also provide semi-hermetic, screw and turbo compressors as well as single, multiple circuit, single and multiple circuit evaporator designs according to user requirements. At present, domestic refrigeration enterprises still have a certain gap compared with foreign enterprises in terms of central refrigeration systems.
Many plastic container and product manufacturing companies produce scraps and defective products during the production process, and they are usually mashed by a crusher for reuse. In particular, the crusher occupies an important position in the waste plastic recycling production line. Most waste plastics need to be broken into small pieces or fragments before they can enter the sorting processing stage. Due to the low technical content of the crusher, there are many plastic machine companies in China that can produce crushers. According to different uses, the crusher is divided into low speed crusher, medium speed crusher, high speed crusher and powerful crusher, etc.
Low-speed pulverizers are generally suitable for crushing stick-shaped engineering plastics, belonging to the relatively high-tech and relatively new types of pulverizers; medium-speed pulverizers have a wide range of applications, and can smash hard engineering plastics and soft General-purpose plastic is the most widely used pulverizer with the largest output. High-speed pulverizers are generally used as machine-side pulverizers. They can smash harder rods, and smash hot and soft materials. High efficiency, can also be used as a centralized crusher, and the price is relatively low; the powerful crusher is mainly used in the occasions requiring a large number of centralized crushing, can crush thick products such as plastic profiles and pipes.
At present, there are many manufacturers of general-purpose pulverizers in China, which can basically meet user requirements. It's just that the shredders produced by most manufacturers have a rough appearance and the knives are not durable enough.
Whether it is injection molding, extrusion or blow molding, the dryness of plastic resin is usually required. Some plastic resins, such as PET resins, easily absorb water from the atmosphere. Therefore, before starting plastic processing, the resin usually needs to be dried to meet the specified moisture requirements. In industrial production, hot air is usually used to dry the resin. The main factors affecting the drying effect are air volume, temperature and dew point. Generally, the air is used to dry the material. In order to achieve the final required moisture content, there must be sufficient air volume to complete the heating cycle and take away the humid air; each material has its own unique drying temperature range. Within the allowed drying temperature range, setting the temperature as high as possible is beneficial to improve the drying efficiency. Hot air ventilation dryer is the most commonly used dryer. Its main feature is that it can keep the resin drying temperature uniform, so it can shorten the drying time successfully.
In addition, there is a dehumidification hot air dryer. The drying air passes through the material in the hopper, takes away the moisture in the material, and continues to dehumidify after leaving the drying hopper, and warms to the optimal temperature required by the drying hopper before re-entering the drying hopper. Many Chinese companies produce dryers. In terms of production and technology of stand-alone dehumidification equipment, the gap between products produced by imported or wholly foreign-owned enterprises is not very large, but there are still gaps in on-line equipment such as conveyor integrated dryers. Only a few joint ventures can produce. This integrated equipment combines the dryer and the feeder into one, which can greatly improve the convenience of product use, save energy and give full play to the use efficiency of the molding site. Such as the Zhangjiagang Great Wall Matsui Machinery Co., Ltd. production of MATSUI integrated hot air dryer and integrated dehumidifier dryer. MOTAN, which has a large share in the high-end plastic auxiliary machinery market, produces not only single-type dehumidifier dryers, but also central dehumidifier dryers, which can perform dehumidification operations for multiple sets of equipment at the same time.
Accurate feeding is one of the most basic requirements in the plastics processing industry. Feeding systems generally include weighing feed systems and volumetric feed systems. Weighing feeders weigh materials to determine the amount of material to be added, while volumetric feeders measure volume to determine the amount of material to be added. The latter is mainly used for adding liquid materials. In the plastics processing industry, weighing-type feeding systems are mainly used, especially granule weighing feeders.
The key technology of stand-alone weighing feeder is the accuracy and precision of weighing, which is very important for product quality and cost control. The opening and closing device of the proportional valve and the hopper directly affect the accuracy. Because the feeding cannot be controlled accurately at one time, the weighing device needs to be operated repeatedly to determine the precise value. Therefore, the memory function of the weighing device is very important. The weighing machine of Canadian Mold (tek) company can estimate the remaining value after the first weighing and weigh it again in a small range. Therefore, it not only improves the efficiency, but also guarantees Accuracy. The opening and closing valves of Mould weighing machines are also very precise, which can precisely control the amount of each addition like a human hand. Therefore, their weighing machines can ensure that the error of all batches of products is within one thousandth. There is still a gap between the domestic weighing feeder and imported products in terms of precision.
The plastic processing industry has entered the stage of large-scale production. Especially the plastic packaging industry, such as the production of PET bottles, often requires feeding multiple, dozens or even hundreds of devices at the same time. It is neither convenient nor economical to use a stand-alone feeder. The use of a central feeding system becomes inevitable.
At present, the central feeding systems used by the Chinese plastics processing industry are almost all imported products, and the central feeding systems of Motan and Mould-tek occupy a considerable proportion. The central feeding system uses the central power source to transport the materials to the destination, which has the advantages of high automation, energy saving, safety and reliability, etc., and some central feeding systems also have dust collection functions, which can improve the working conditions next to the host and reduce the Pollution, improve production efficiency and product quality.
The advanced central feeding system can control the work of dozens or even hundreds of feeders at the same time. For example, the T-LINK series central controller of Mould-Tek Company relies on a twisted pair to connect with the controller of each feeder. Through the entire system, the way of central connection of the central control system and each feeder is changed. Not only improves efficiency and reduces errors, it also enables two-way communication. During operation, the system first inputs signals to tell the device what to do. After the device is complete, it will send back signals to the host, answering how well it did, and how it turned out. It achieves two-way communication and intelligent operation. In addition, the controller uses a touch screen to control time, volume and weight loading. When used in conjunction with the WL series weighing and loading machine, the amount of material used can also be printed by a printer. The controller can control three vacuum pumps (including one standby pump) and hundreds of feeders. The feeding priority of each feeding machine can be set according to the needs, and the feeding proportion and layering of the two-component material feeding machine can be easily controlled at the same time.
The mixer should also use a weighing and feeding system. When the mixture needs to be mixed and granulated, the uniformity of the mixture depends on the design and manufacture of the screw. The mixing nozzle of Sulzer rare element alloy, which is promoted by the Hong Kong Precision Injection Molding Laboratory, can be added to the injection or extrusion head to achieve full mixing of materials.
Mold temperature machine
Maintaining the proper temperature of the mold is very important for the molding of plastic products. Generally, the temperature of the mold should be lower than the glass transition temperature or thermal deformation temperature of the plastic to ensure that the plastic melt solidifies and molds. The temperature of the mold temperature will affect the melt viscosity, which will affect the melt's ability to fill the cavity and the cooling time. Under the premise of ensuring that the cavity is filled smoothly, using a lower temperature and shortening the cooling time can improve production efficiency.
There are two types of mold temperature machines: water type and oil type. At present, most of the mold temperature machines made in China are equipped with all-digital PID temperature control and automatic cooling control, which can automatically maintain a stable mold temperature. The temperature can be accurately controlled within ± 1 ° C, and there are many safety settings. Many key components such as high temperature and high temperature pumps and liquid level switches are imported from abroad, such as the mold temperature machine produced by Yili Machinery Company; and the MKR series mold temperature controller produced by Zhangjiagang Huaming Machinery uses thermal oil as the medium, which can be used Production of plastic parts with high injection mold temperature and high-precision plastic parts. It is also suitable for processes such as plastic blown films that require constant temperature control. The heating temperature can reach 160 ° C and the temperature control accuracy is + 1%. There are more series products for thermostats, including: water temperature mold thermostat, high temperature water mold thermostat, oil mold thermostat and special mold thermostat, etc. At present, domestically produced injection molding machines have basically been matched with domestic mold temperature machines.
There are many types of plastic auxiliary machines. In addition to the above products, they also include suction devices, vibrating screens, mills, shredders, and conveyor belts with metal detection devices. Most products can be manufactured in China and can meet the requirements.
Direction of development
There are many manufacturers of plastic auxiliary equipment in China and their development is rapid. Most of the high-level enterprises are concentrated in Dongguan, Shanghai and other places.
At present, China can produce most types of plastic auxiliary machines, and even some products have reached the point of oversupply, but the industry also has certain problems. The main manifestations are as follows: the product has low technical content, fewer products with high degree of automation, and less multifunctional integrated equipment; the phenomenon of unification is obvious. Equipment manufactured by different manufacturers is very small, technology and product duplication are serious, and low-end products are highly competitive. It can be said that the lack of technological innovation and simple repetitive production are the biggest obstacles to the development of China's plastic auxiliary machinery.
In fact, at present, China's plastic auxiliary machinery manufacturers have upgraded their products, and the time has come to develop high-end products. With the development of China's plastic processing industry and the accumulation of experience of plastic product manufacturing enterprises, it has provided space for the development of China's high-end auxiliary machinery market. For example, at present some plastic processing enterprises with certain production experience have given up the practice of importing a full set of production lines from abroad, and instead purchased key mainframes from abroad, and then matched domestic auxiliary equipment to form a production line. Of course, this also puts forward higher requirements for domestic plastic auxiliary machines.
Today's plastic auxiliary machines are no longer simple mechanical operating systems, but more and more electronic control technologies are integrated. In addition to strengthening their own R & D investment, production enterprises should also work closely with colleges and electronic research and development units. The modern plastic processing industry not only requires auxiliary equipment to be reliable and economical, but also requires accuracy, precision, and meets the needs of large-scale production. Therefore, precision, combined auxiliary machine systems and auxiliary machine systems with central control capabilities will be the development direction of China's plastic auxiliary machines.
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