Introduction of Flow Enamel Coating
The flow coating in the production process of the enamel factory is not to immerse metal body in the enamel slurry, but hang it on the drive chain; when the metal body passes through the appropriate position, the enamel slurry flows to the enamel surface through the conveying pipe, and the excess The enamel slurry flows back into the pump. This kind of enameling operation is suitable for large batches of single-variety products.
The typical domestic flow coating is the inner surface coating of the inner tank of the water heater. There are manual, semi-automatic and fully automatic coating methods. At present, semi-automatic enamelling is mainly used, and manual or mechanical assistance is required for the upper and lower parts. After the workpiece is positioned, the automatic enamelling starts.
Automatic enameling is also called automatic online enameling, which can reduce labor and improve the quality of enameling. Automatic online flow enameling can produce workpieces of the same variety and different specifications with strong adaptability.
The automatic online coating equipment can be configured with different numbers of stations according to the output requirements. The inner tank is hung on the conveyor chain and lifted to the rotating station. The upper part of the inner liner is equipped with a photo-eye recognition device, which can automatically locate the inner liner. The diaphragm pump transports the enamel slurry to the long rod gun, which is pneumatically lifted to inject the enamel slurry into the liner, and the long rod gun completes the injection of the enamel slurry and then returns, and the liner starts to rotate within the predetermined angle range according to the program . The surplus enamel slurry flows out from the mouth of the inner tank, and returns to the feeding system through the filter screen. After the whole cycle is over, the machine returns to the zero position, and the inner tank is transported to the next process by the catenary.
Most of the enamel frit used in the flow coating of the inner tank is pre-ground powder that has been configured by the enamel frit manufacturer. Before use, it only needs to be soaked in water and can be used after full stirring. In some cases, more enamel slurry appears after stirring. Air bubbles can be used for enamelling after a certain period of time. Since the appearance of the enamel surface of the water heater is not as strict as the physical and chemical performance requirements, the thickness of the enamel slurry is usually thicker, so that the workpiece can ensure the proper adsorption of the enamel slurry and at the same time, the excess enamel slurry It is easier to eliminate, and the thicker enamel slurry is more suitable for the long-term firing of such large products and is not easy to burn.
For small workpieces, you can clamp the workpieces on the conveyor chain first, and use the vertical drop of the chain to completely immerse the workpieces into the enamel slurry pool and slowly remove the workpieces from the enamel slurry pool as the chain runs. Lift in the slurry tank to allow the excess enamel slurry to drip down before entering the drying process. When individual workpieces cannot completely rely on the enamel slurry to flow by itself to achieve the uniform enamel layer of the entire workpiece, you can manually supplement some actions, such as using a hook Lift the workpiece at a certain angle, or manually erase the powder accumulation in the groove with severe powder accumulation. The use of this coating method greatly saves labor, and it is easy to keep the quality of the product consistent.
The products that use this method in China mainly include flat pieces for assembling the oven body, and grilling nets for the oven industry.
The enamel slurry using this method requires frequent testing and adjustment of its density and fluidity properties, and at the same time, frequent or even continuous stirring. If necessary, a constant temperature device may be installed in the enamel slurry pool to ensure that the enamel slurry is in the production process. The operation performance in the system is stable. The enamel frit should be made of materials with better leveling properties, and the density and fluidity of the enamel slurry should be larger than those of manual dipping, so that the excess enamel slurry will easily flow out of the workpiece when it flows naturally, and at the same time it will be larger. After drying and firing the dense enamel slurry on the workpiece, it is easier to meet the thickness requirements of the product.
From the perspective of the operation process of the workpiece, this method seems to be classified as "dipping enamel", but because the excess enamel slurry after immersion is mainly eliminated by natural flow, it is very similar to the enamel of the water heater inner tank, so it is classified For "flow coating".