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    Home > Coatings News > Paints and Coatings Market > Application of automotive water-based paint supply system and intelligent electric pump Wang Yuzhe

    Application of automotive water-based paint supply system and intelligent electric pump Wang Yuzhe

    • Last Update: 2020-11-28
    • Source: Internet
    • Author: User
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    Automotive coating is a typical representative of industrial coating, a large number of assembly line production, generally multi-layer coating, the use of drying paint system, it is a large energy consumption and the production of "painting pollution" of large households. With the continuous enhancement of people's environmental awareness and the continuous improvement and soundness of the corresponding regulations, the use of water-based coatings and other low VOC (volatile organic compounds) or VOC-free environmental protection coatings, as well as low energy consumption processes and related equipment is the inevitable development trend of the automotive coating industry. This paper aims at the characteristics of water-based paint in the automotive industry and its requirements for paint supply system, and combined with the characteristics of the new intelligent electric paint supply pump, specially introduces the advantages of electric pumps used in water-based lacquer supply systems, and compares with the hydraulic pumps currently widely used for reference by peers
    China
    .
    1 Characteristics of water-based coatings and the characteristics of their paint supply systems
    the types of coatings dispersed in water are mostly water-based coatings, and their properties and flow behavior are different from traditional solvent-based coatings:
    (1) water-based coatings have poor pigment dispersion;
    (2) surface pressure is large,
    (3) evaporation latent heat is large, i.e. it is affected by temperature and humidity,
    (4) dispersion stability is poor, poor shear resistance performance,
    (5) conductivity is good, corrosion resistance is high.
    because of the above characteristics of water-based coatings, its spraying temperature, humidity and other construction windows and baking temperature and other construction conditions have strict requirements, not to mention here.
    the shear force has an effect on the stability of water-based coatings, and even has a destructive effect. At the same time, the viscosity of water-based coatings also has an impact, in the circulatory system caused by different shear forces at different times water-based coatings will show different viscosity, resulting in inconsistent flow rate, thereby affecting the balance of the circulatory system and the instability of fluid flow rate in the equipment. Therefore, in addition to the use of stainless steel or high-quality plastics in the paint system of water-based coatings, we must try to reduce the shearing force of the circulatory system, using low shear pumps and related components. In addition, in the non-production process, the best solution is to reduce the flow rate within the system, that is, the flow rate of the coating in the pipeline, as far as possible to reduce the shear force on the degradation of the coating.
    2 Types of electric pumps and new intelligent electric pump structure features
    Paint circulation pumps used in paint systems in the automotive coating industry can be divided into the following categories:
    (1) according to the driving mode is divided into: pneumatic pumps, hydraulic pumps, electric pumps.
    (2) according to the discharge method is divided into: piston pump, diaphragm pump, centrifugal pump.
    in China, the paint supply pumps used in the centralized paint system of water-based paint and finish paint are mainly pneumatic piston pumps and hydraulic piston pumps. Electric pumps have been increasingly used in North America and Europe since 2000 due to their energy cleanliness and ease of control and operation, low operating noise, no icing, frosting and oil leakage.
    2.1 The development and type of electric pump
    To ITW's products, for example, electric pumps in its development process has also appeared different types of products, according to its structure, can be divided into the following:
    (1) cam rotor shape: the use of two rotor rotation to provide fluid and pressure, the shortcomings of the production of shear, can not transport low-viscosity coatings, mechanical shaft sealing needs to continue the supply of paint, easy to generate heat and waste energy.
    (2) crank link: it is a re-reserective motion pump that can be used with a 4-ball pump in the middle range for different flow levels. This pump needs to be equipped with special software or a regulator to reduce pressure pulsation and obtain stable material pressure. A regulator is not required if driven by an inverter motor.
    (3) Cam-shaped electric pump: is a two-cam horizontal pair pump, the driver's schematic shows in Figure 1; Different drive motors can be equipped to achieve different material transfer flows.
    new type of electric pump can achieve intelligent control effect by equipping it with the corresponding control hardware and software, also known as "smart electric pump".
    2.2 Features of the new smart electric pump
    The new intelligent electric pump has the following characteristics:
    (1) stable pressure output, low pulsation.
    The center drive mechanism of the pump is a cam, so that there is no conversion valve, and the cam is structurally designed to allow its driven mechanism to achieve constant speed motion, thus ensuring stable pressure at the output and eliminating the need for a regulator. The pulsation of coating pressure in the main road is shown in Figure 3 between this electric pump without a regulator and the pulsation of the paint supply of pneumatic pumps and hydraulic pumps (with or without a regulator). As can be seen from Figure 3: The electric pump can greatly reduce the pressure pulsation in the coating circulation system. This is not only conducive to the stability of paint performance, but also to ensure that the paint system produces good spraying results.
    3 Comparing the pulsation levels of electric pumps with pneumatic and hydraulic pumps, figure
    (2) is synchronized with spray equipment and production lines.
    For cam-shaped electric pumps equipped with intelligent control systems, such as variable frequency motors, programmable control software, etc., the following functions can be achieved: according to the actual production conditions, synchronized with the spraying equipment, only in the use of the color material circulation system into the working state, while the rest of the color material circulation system in low flow, low pressure "sleep" mode (i.e., the paint flow rate is minimized, and regular circulation, to prevent paint precipitation). According to the actual statistics on the production line, the average number of pumps operating at high flow is about 3.5 during full-load production. In addition, it can be synchronized with the production line, i.e. during non-production periods, such as weekends or holidays, intelligent control cycle system is in "sleep" mode, which can bring the following benefits to the coating circulation system:
    .
    energy consumption.
    reduce system load and extend equipment life.
    reduce operating costs.
    the above characteristics of the intelligent electric pump make its application in the water-based coating circulation system greatly reflected in the advantages.
    3 Intelligent electric pump and hydraulic pump paint supply system comparison
    (1) equipment configuration
    For the second-line circulation system of water-based coatings shown in Figure 4: when the hydraulic pump is used for painting, the system pressure can only be adjusted by manually adjusting the back pressure valve, and the flow of the system is controlled by the number of blows from the hydraulic pump. The system cannot minimize flow rates during non-production times. When an electric pump is used for painting, the pneumatic backpressurized valve can be driven by controlling electrical signals to regulate the pressure of the paint supply system, which is equipped with a pressure sensor to monitor the working pressure of the circulating system. This adjusts the output flow of the electric pump by interlocking the signal with the production equipment, so that the "real-time" detection, adjustment and control can be achieved. Table
    1 System configuration comparison table
    Figure 4 Binary Circulation System
    (2) Equipment investment and economy
    According to Table 1, for a set of water-based paint two-line circulation system, hydraulic pump paint system and electric pump paint system equipment configuration is different, the price of electric pump paint system slightly higher than 5%. However, as shown in Figure 5, when applied to water-based paint systems, the system's power consumption is greatly reduced due to the characteristics of the electric pump system that are synchronized with the coating equipment and production lines, and the variable frequency control flow, while reducing the load on the equipment and extending the service life of the equipment.
    Figure 5 Electric Energy Consumption Comparison Figure
    4 Conclusion
    With people's environmental awareness and related regulations continue to improve and improve, in the automotive industry water-based paint, paint will gradually replace solvent-based coatings. Because of its low degradation of coatings, real-time control of the system, energy saving and consumption reduction, intelligent electric pumps will become the main force of water-based paint supply system paint pumps, so as to save resources, reduce operating costs and clean production and other purposes.
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