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Production process of metering nozzle

metering nozzle1. Ingredients. Accurately weigh various zirconia particles and powders according to a certain proportion, and the weighing error (mass fraction) should generally not exceed 0.5%.

2. Premix. The particle gradation is strict and the fine powder content is high. In order to make the powder, especially the additives with less content, mix more uniformly, the fine powder is often mixed evenly with mixing equipment such as ball mill tank, conical mixer, etc. before mixing. , so that the fine powder components are evenly distributed, which is conducive to sintering and reduces the occurrence of cracks.
High-performance zirconia metering nozzle are often added with zirconia fine powder, which needs to be mixed evenly when mixing, so the premixing of fine powder is particularly necessary. In the production process, if the fine powder is not mixed uniformly, it will cause uneven thermal stress, which will lead to cracking (or cracking) of the product.

3. Mixing. In order to mix various raw materials and binders uniformly, forced mixing equipment is often used for mixing. First put the granules into the mixer and stir for 3~5min, then add an appropriate amount of binder and stir for 3~5min, so that the binder evenly covers the surface of the granules: then put the weighed fine powder into the mixer and mix for 10 minutes It takes ~15min. During the mixing process, attention should be paid to cleaning up the materials stuck to the bottom and sides of the mixer, otherwise the materials may be mixed unevenly.

4. Forming. Generally, machine press is used for molding, and the molding pressure should not be too high, otherwise the blank of the metering nozzle is easy to crack, and the life of the molding die is short. The length-diameter ratio of the metering nozzle is generally greater than 2, so double-sided pressure molding is generally adopted during molding, which can improve the density of the green body.

5. Dry. Before firing, it is necessary to discharge the moisture introduced by the binder during mixing, so that the green body has a certain strength, which is convenient for kiln loading and firing. The drying heating curve and the maximum drying temperature should be reasonable, so that the water can be discharged evenly and reduce the damage to the green body.

6. Firing. The metering nozzle blank is loaded into a high temperature kiln, and the blank is sintered according to a certain heating system. The maximum firing temperature depends on the tundish nozzle material, generally greater than 1700℃. The high temperature kiln can be a shuttle kiln, a tunnel kiln, etc. The performance of zirconium products mainly depends on solid-phase sintering to produce ceramic bonding. The sintering condition has a great influence on the performance of the products. The sintering temperature is suitable, the products are sintered well, the porosity is low, the density is high, and the corrosion resistance is strong; the temperature is too high Or too low, the product performance is difficult to meet the requirements of use.

7. Pick. After firing, the metering nozzle should be selected. The selection items include nozzle size deviation, missing edge depth, crack size, molten hole, deformation, etc. The inner hole of the metering nozzle core is the main object of inspection.

8. Bonding assembly. The nozzle core and nozzle jacket are bonded with fire clay, then dried, and ready to be transported to the steel mill for use. In the past, single-material sizing nozzles were often supplied, but in recent years, many customers prefer composite nozzles for the purpose of saving costs With inserts and press jacket. This manufacturing method makes the entire system very reliable without the risk of breakout between the insert and the outer casing.

9. The surface of the quick-change nozzle generally needs to be painted with skateboard oil to facilitate smooth sliding.



Contact: Ed


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Add: South Tower, Greenland Central Plaza, Zhengzhou, Henan Province, China