Aluminum profile vertical powder coating production line
ã€China Aluminum Industry Network】 1. Development and Overview of Vertical Powder Spraying Powder spraying is a dry surface treatment process. After ultrafine pigment particles are electrostatically treated, they are sprayed on the product to form a coating that is cured by a curing oven. Form a solid coating. Doosan Main Wiring Harness,Doosan Main Pump Assy,Doosan Excavator Main Pump,Doosan Loader Parts JINING SHANTE SONGZHENG CONSTRUCTION MACHINERY CO.LTD , https://www.sdkomatsugenuineparts.com
Due to powder coating has:
1) The surface is beautiful, durable, scratch-resistant, chemical-resistant, and UV-resistant;
2) Environmental protection, no waste liquid discharge;
3) Perfect corner coverage effect;
4) Uniform color and wide range of spray colors;
5) The thickness is easy to control and is therefore widely used.
Powder coating and painting began in the late 1930s. The flame spraying method was used to apply the polyethylene powder to the metal surface in a molten state, which is the beginning of powder coating. Until the 1950s, after Germany's invention of the fluidized bed dip coating method, the powder coating and the coating process were greatly developed. China's powder coating started late. In 1989, Changzhou Huayi Aluminum Profile Factory introduced the American Nordson powder spraying equipment. It is the former home of China's aluminum powder spraying, but with the economic reform and opening up, powder coating technology was obtained in China. Rapid development. Early adopters were horizontal production lines, but with the development of economic technology, Italy and Japan first introduced vertical spraying production lines and began to be widely used. The vertical powder coating production line has been developed into a mature product, and the uniformity of the pretreatment, drying and dusting coating, as well as the effect of curing, have reached the advanced level in foreign countries, due to the small footprint of the vertical line, operation Fewer workers, uniform dusting, and cured layers all achieve perfect results.
2. Process of vertical powder spraying production line Process group of vertical powder spraying production line The main components of the established powder spraying production line are pre-processing, loading/unloading system, dusting system, powder recovery system, solidification and drying part, and automation control part. composition.
The work process is mainly divided into: pre-treatment → on the shelf → spray → curing → unloading → packaging.
1) The pre-existing treatment is mainly to clean the stains on the surface of the aluminum profiles and form a layer of chromium film on the surface to make the dusting work well.
Process flow: basket → degreasing → washing → (alkaline etching) → washing → surface adjustment (neutralization) → washing → chromate → washing → hot (pure) washing → drip drying → drying → send spraying.
Among them, the concentration of degreasing, alkaline etching, surface modification, and chromizing agent is based on the concentration tank solution provided by the supplier. Wash tank with general tap water. Hot water wash with pure water. (alkaline erosion can not use) tank structure:
Degreasing tank: It is mainly used to clean the surface of aluminum profiles to prevent the adsorption of electrostatic powder on the surface of aluminum. The tank body is anticorrosive with soft PVC. The main component of the bath is sulfuric acid, and the temperature is room temperature. The tank size depends on the length of the larger profile and the yield.
Rinse tank: Clean the chemical residue from the last tank. Anti-corrosion of the tank adopts soft PVC. The main component of the tank fluid is tap water, and the temperature can be normal temperature. The tank size depends on the length of the larger profile and the yield.
Table adjustment (neutralization): Neutralization of acid residues in the degreasing bath. The tank body is anticorrosive with soft PVC. The main component of the bath fluid is the temperature of 10 degrees to 60 degrees. The tank size depends on the length of the larger profile and the yield.
Chromizing bath: chemical conversion to prevent the electrostatic powder from being detached. There are two kinds of chromizing and phosphating. These two methods have been used for many years, the performance is quite stable, the production is easy to operate and can be processed according to the color The conversion effect was discriminated, in which the aluminumized film was yellow and the phosphorus-chromium film was green. The operation temperature and time range of the two processes were wide, and the coating thickness was generally 0.3-0.8 g/M2. The corrosion resistance of the chromatographic tank was adopted. In soft PVC, the main component of the bath is fluorozirconate or fluorotitanate, and the temperature is 25 degrees to 55 degrees. The tank size depends on the length of the larger profile and the yield.
Hot water washing tank: After the chromate treatment process, its antisepsis adopts the all stainless steel structure, the bath liquid composition is pure water, the bath temperature is controlled to 60-80 degrees. Its temperature control can be heated by water heater or steam.
Drying furnace: The chromium chromatographic film after drying is dried so that no water remains on the surface. If moisture is left on the surface of the workpiece to enter the dusting process, the coating will produce bubble defects. The drying temperature should not be too high, or the transformed film will lose too much water of crystallization and the transformation will occur, resulting in loose film and reduced coating adhesion. The heating of the drying oven can be based on different customers' needs to use gas burners or diesel burners. The temperature can be controlled by the temperature control system to set the target temperature. The furnace body is made of stainless steel.
2) The loading and unloading system is composed of two parts: the chain conveying and the loading and unloading conveyor belts. It plays a linking role in the whole system, and the three conveyor belts are kept in sync during automatic operation. Among them, the chain conveyor belt is an electromagnetic adjustment device, and the upper and lower material conveyor belts are controlled by a frequency converter, and are synchronously adjusted by sampling and calculating the feedback signal of the rotary encoder.
The main function of the loading and unloading conveyor belt is that the aluminum profiles are horizontal to vertical when loading, and form a smooth transition from vertical to horizontal when loading. To prevent aluminum swing, scratch the surface. It is at an angle of 40 degrees with the conveyor chain. The running speeds of the loading and unloading chain are carefully calculated by the PLC to ensure that the three are synchronized in space. The main components: a conveyor belt driven by a motor, equipped with non-slip baffles on the conveyor belt, in order to ensure the orderly landing of aluminum shelves.
The conveyor chain is driven by a universal conveyor chain to move aluminum profiles to designated rails. The length of the entire chain is between 100 and 150 meters, and it can withstand high temperatures. Its operating speed is related to the number of spray guns and the thickness of sprayed powder. Under normal circumstances, the running speed of the conveyor chain for single-sided twelve spray guns is 1.5 to 2 m/min.
3) Powder spraying system The powder spraying system is the core part of the entire production line: it is mainly composed of two reciprocating machines with adjustable top/bottom dead center, adjustable speed and powder spraying system.
Reciprocator: Its height is related to the length of the larger profile sprayed by the customer. The spray gun is mounted on the moving platform of the reciprocating machine. The moving platform reciprocates up and down according to the linear guide. The schematic is shown in the figure. The top and bottom dead point adjustment is feedbacked by the encoder to the PLC to calculate the pulse positioning. The adjustment accuracy is 1mm. The top/bottom dead center position can be set through the touch screen or the host computer. Its operating speed is adjusted by the potentiometer input to the inverter, speed adjustment range 0HZ ~ 50HZ (0m / s ~ 8m / s), according to the actual needs of the customer's spray thickness on-site adjustment.
High-pressure electrostatic spray gun and multi-function spray gun controller: Imported Swiss Golden Horse Automatic high-voltage electrostatic spray gun equipped with an integrated electrostatic high-voltage generator is the core of powder spraying equipment. It is a key component that sprays powder onto the workpiece. The daily maintenance volume is very small. Equipped with an electrode holder discharge needle cleaning system, it can guarantee a stable and efficient powder charging effect and continuous and stable powder output. Swiss Golden Horse Automatic High Voltage Electrostatic Spray Gun The Golden Horse Multifunctional Spray Gun Controller provides a user-friendly interface that allows for the repeated setting of control parameters to achieve excellent spray results.
The advantages of this controller are:
* Repeatable spray results can be achieved at any time * All spray parameters (spray voltage, spray current, transfer air, and electrode holder wash air) can be set accurately, respectively * Endurance powder charge conditions * Uniform powder discharge for all spray guns * Uniformity The coated surface* enables accurate control of the coating surface thickness to achieve powder savings. In addition, 255 individual coating programs are stored in the controller and can be recalled at any time.
The multi-function gun controller is used in combination with the optional OptiFlow to measure and regulate the transmission air and auxiliary air. The DigitalBus data bus module can exchange data with a remote programmable controller (PLC). Cyclone Recycling Unit The role of the cyclone recycling unit is to separate the recovered powder from the air. The air powder mixture extracted from the spray booth is sent to the cyclone separator. The mixture forms a downward swirling airflow, and the heavy powder particles are centrifugally thrown against the wall of the cyclone and then fall onto the lower powder screen. On the powder screen, impurities are screened out and qualified powder is re-entered into the powder loop and used. This cyclone separator is more suitable for the use of rapid color change spraying.
4) After curing, the workpiece of the curing furnace must be placed in the baking oven as soon as possible to be leveled and cured so as to prevent dust and other impurities from adhering and powder falling and affect the coating quality. Curing furnace with two Swedish Baitong burners for heating, using natural gas (or liquefied petroleum gas) as fuel, with an annual output of 15,000 tons, the vertical section of the larger profile length of 7.5 meters as an example: its solidification The internal space of the furnace is designed to be 200m3. The heating rate is about 15 to 20 minutes at room temperature and 180°C. There are four temperature sampling points, can monitor the furnace temperature at any time, can also be used for curve analysis with the host communication, report records for the record, every two temperature control points to control a burner, in order to ensure uniform temperature inside the furnace. The air curtains are installed at the entrance and exit of the furnace body to ensure heat loss in the furnace.
5) Automatic control system Automatic vertical dusting production line control part mainly consists of: pre-processing, conveying system, dusting system, curing furnace parts. Intelligent control using PLC, and online monitoring and operation with the touch screen, and on-line remote system, on-site monitoring, data acquisition and analysis, curve archive, report generation. Another spray gun controller can be selected according to customer requirements can be added to the host computer to monitor operations.
The whole line control system maps the moisture drying on the surface of the aluminum profile and provides hot water. A burner is used in conjunction with a temperature controller to control the temperature in the drying oven. The temperature of the bath can be monitored and the collected temperature can be archived in the host computer.
The conveyor system is composed of two parts: the chain conveyor and the upper and lower material conveyor belts. It plays a linking role in the entire system, and its three conveyor belts keep synchronized during automatic operation. Among them, the chain conveyor belt is an electromagnetic adjusting device, and the upper and lower material conveyor belts are controlled by a frequency converter, and the synchronous encoder adjusts the feedback signal of the rotary encoder after sampling. The conveyor line speed can be displayed on the touch screen or the host computer, and the main conveyor belt is adjusted by the electromagnetic governor.
The dusting system is the core part of the entire production line and consists of two vertical reciprocators. The operating speed and position of the top and bottom dead points can all be adjusted via on-site potentiometers. Through PLC calculations, rotary encoders are used as top and bottom dead center position feedback, and the inverter performs the operation. With upper and lower limits, overload protection.
The curing oven is a post-processing, and the two burners heat the furnace temperature. Through the sampling of the four temperature control points to control the furnace temperature, the temperature controller can communicate with the PLC, and the temperature is set on the temperature controller. Can be set. The sprayed material is cured and leveled at a set temperature.
Summary: The vertical powder coating production line has been approved by many manufacturers in China because of its various advantages.