Influence of molding on properties of magnesia carbon brick and selection of pressurization system

Influence of molding on properties of magnesia carbon brick and selection of pressurization system

Forming is a process of making a product have a certain shape, increasing its filling density, and densifying the product's organizational structure. The molding of magnesia carbon brick is a narrow molding, which refers to semi-dry molding. During semi-dry molding, the molding pressure must overcome the friction between the materials and the friction between the materials and the mold sleeve. , and to overcome the deformation of the material, so the pressure is not uniform for the entire material. When the change occurs, the density near the pressure surface is high, and the porosity is small, and the place far from the pressure surface is low in density and large in porosity.

First ,the influence of molding on the properties of magnesia carbon brick

In the production of magnesia carbon brick, the setting of the entire forming process is often related to the product density. Under the premise that there is no problem with the raw materials, the density of the general product meets the specified requirements, and other indicators are basically no problem. For this reason, we generally Production is controlled according to brick density. In order to produce qualified products, we generally use high-pressure molding, and strictly monitor the single weight of the product during the molding process. Normally, the higher the pressure of the press, the higher the density of the product, and the smaller the distance between particles, so the required combination The lower the dosage is, it is important that the product will crack due to too much binder and localized concentration.

In order to achieve a uniform and dense product, we generally use a large-tonnage press to achieve this, and formulate a certain pressure system to ensure the quality of the product. Generally, it is light first and then heavy, and lightly press several times to remove the gas in the material. When pressing lightly, the pressurization speed should not be too fast, so as to avoid the gas being sealed in the material and cannot be discharged. If conditions permit, use vacuum equipment to exhaust the effect. will be better. After light pressing, the green body can be pushed out of the mold cavity and repeated several times in order to fully exhaust the gas and avoid spalling. Finally, heavy pressure is used to ensure the product density, especially the last few blows must be enough. Considering the elastic after-effect of pressing magnesia carbon brick, the die head should not be lifted too fast during the pressing process.

Presses have been replaced for several generations. At present, there are several presses in the factory producing magnesia carbon brick. The commonly used presses are friction presses, electric screw presses and hydraulic presses. Due to the high price of hydraulic presses, only a few large factories can have them. Although hydraulic presses are fast in production, they also have great limitations, that is, they are not flexible enough, and it is inconvenient to replace brick types. It is only suitable for mass production of a single variety. In the brick industry, the market share of hydraulic presses is not high, and the proportion of friction presses and electric screw presses in factories is still larger. Since electric screw presses are a rising star, for many factories, production equipment has been After the installation is completed, it is impossible to re-purchase new equipment after dismantling it. Because the press occupies a large proportion of the capital in the production equipment, so far, the share of the friction press still exceeds that of the electric screw press. But the gap is gradually narrowing.

Second, the choice of pressurization system

When a specific brick type is involved in the production process, we need to determine which machine to use for production. How to formulate specific pressurization methods, these are all explored in actual production, of course, they are also summed up through continuous experiments. The number of pressurization times is small and the pressure is not enough, which will lead to insufficient density of bricks and large pores; Too much impact force will cause the product pellets to be broken, time-consuming and electricity-consuming, these are not what we want to see.

First of all, we have to judge what kind of product is suitable for what kind of machine to use. For example, 8Kg ladle bricks, 400T, 630T, and 1000T machines can be produced, but which type of machine is the most suitable? According to the characteristics of the machine itself , Our general choice method is to choose small machines as much as possible under the condition that the pressure of the machine can meet the pressure system. The main consideration is economic benefits. Large machines generally consume more electricity and have high operating costs, but at the same time, we must also pay attention to the limit capacity of the machine. , as shown in Table 1, if the product with a single weight of 25~28Kg is produced by a 630T machine, although it can be produced, it is already close to the limit capacity of the machine. In this case, not only the wear of the machine is large, but also the production efficiency It is also low, so such products should be produced by 1000T machines.