Application of the hottest powder electrostatic sp

2022-08-24
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The application of powder electrostatic spraying on highway guardrail

the requirements for highway guardrail are increasing with the development of highway construction in China. As the protective barrier is placed in the open air and affected by the climate and environment, the surface coating technology of the protective barrier is highly required, so that the surface coating has good weather resistance, corrosion resistance and other properties, and the appearance has ideal decoration. In our country, most of the highway protective barrier boards are hot-dip galvanized boards, which have a single appearance color, and their weather resistance and corrosion resistance are lower than those of powder electrostatic spraying boards. Moreover, the pollution-free powder electrostatic spraying process and the diversity of powder color are unmatched by other coating processes. At present, powder electrostatic spraying protective barriers have been widely used abroad

in order to meet the development requirements of highway barrier boards in China, Zhejiang University coating technology engineering company designed and manufactured a powder electrostatic spray production line with an annual output of 600 kilometers. From the actual use of the equipment, this production line has reached the design index, and the performance of the spraying products is good

1 process overview of the production line

this production line is composed of two lines: the first is the semi-automatic trough immersion workpiece pretreatment and workpiece dehydration line; Second, automatic electrostatic powder spraying and powder solidification assembly line

1.1 trough immersion pretreatment process

the material of highway protective barrier is hot-rolled plate, and its surface is oxidized at high temperature to produce oxide skin. The removal of oxide scale depends on the penetration of rust remover on oxide scale, and the corresponding strain time history should be based on Neuber correction method to convert elastic strain into elastoplastic strain penetration (penetration) force. They add additives to the mixed acid, which has the function of rapid penetration, oil removal, chromization, corrosion inhibition and other functions of removing oxide skin in a short time at room temperature. In this way, the problems of high temperature, large environmental pollution and material performance of conventional sulfuric acid method are solved, and the investment cost of equipment and plant maintenance cost are greatly reduced

the phosphating process of the workpiece adopts the normal temperature slag free phosphating technology, which solves the problems of high energy consumption, large residue and yellowing of the current heated phosphating process. Moreover, the production technology management is convenient, and it can be adjusted and controlled with a Baume meter and pH test paper. Each kilogram of working fluid can handle m2 of workpiece. Under the temperature of Celsius and time of min, the formed phosphating film is constant at 2 Within 5g/m2, ensure the spraying requirements of the next process

the passivation process adopts a non-toxic passivator to solve the environmental pollution of chromate and dichromate passivation after phosphating, and improve the corrosion resistance of phosphating film and the adhesion of coating

the dehydration of the workpiece is a box oven, which adopts the heating mode of oil heating and heat exchange and internal circulation of hot air, and at the same time, the water vapor is forcibly discharged. After dehydration, the workpiece is directly transferred to the back full-automatic electrostatic powder spraying and powder curing line

1.2 automatic electrostatic powder spraying and powder curing process

electrostatic powder spraying and powder curing process are connected in the form of hanging conveyor chain. After the workpiece is online, it is offline after electrostatic powder spraying and powder curing, and the product is warehoused after passing the inspection

the powder electrostatic powder spraying equipment adopts 8 automatic spray guns for double position spraying, and the variable frequency speed regulator controls the moving speed and range of the spray gun; Small cyclone primary recycler and pulse air reverse blowing filter element recycler are used as secondary recyclers; The integrated electric control system of six combined electrostatic generators is adopted. Each electrostatic generator is equipped with two spray guns, and the remaining two electrostatic generators can be used as standby or supplementary spraying

powder curing adopts the form of straight through drying channel, fuel heating and heat exchange, and hot air internal circulation heating. The imported combustor is used as the heat source to burn in the stainless steel combustion chamber, and the high-temperature flue gas generated is discharged after passing through the high-efficiency heat exchanger. High temperature fan is used to make the air in the drying channel exchange heat through high-efficiency heat exchanger, so that the temperature in the drying channel can meet the requirements of powder curing

the light suspension chain with a single point lifting weight of 100kg is used for the suspension conveyor chain. Considering the long size of the protective barrier, the hanger adopts soft connection to minimize the impact on the suspension chain system when the workpiece turns and goes up and down the ramp

2 production line process and equipment technical parameters

2.1 pretreatment process flow

groove external Zhang Xin introduction shape size: 5200mm*1000mm*1 Solvay's main product aromatic polymer perfect meets the needs of automotive original equipment manufacturers 500mm (length x width x height) a total of 8 anti-corrosion grooves

workpiece transmission: manual crane lifting and dipping

overall dimension of dehydration furnace: 5200mm*2900mm*2000mm (length x width x height)

heat consumption: 60000 kcal

temperature control range: Celsius

heating rate; Temperature rise to 100 ℃ in 20min

heating method: fuel heating and heat exchange, Hot air internal circulation

2.2 powder electrostatic spraying and curing process flow

2.2.1 powder electrostatic spraying equipment, especially in the aerospace field, has a wide application prospect. Equipment overall dimension: 7000mm*5000mm*3000mm (length x width x height)

power consumption: 15kw

compressed air consumption: 180m3/h (gauge pressure 0.55mpa)

2.2 powder curing equipment

equipment overall dimension: 42000mm*1200mm*40000mm mm (length x width x height)

heat consumption: 400000 kcal

temperature control range: Celsius

temperature rise time: less than 60min to 180 ℃

heating method: fuel heating and heat exchange, hot air internal circulation

2.2.3 suspended conveying equipment

qxt-300/100 light bearing chain suspended conveyor

3 summary

after trial operation, the technology, economy and practicability of the powder electrostatic coating production line have been affirmed by users. (end)

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