The extrusion process can be divided into two stages: the first stage is compaction and preloading, which can be collectively referred to as the jacking stage. It is After the paste is loaded into the material chamber and the baffle at the die mouth is lifted up, the plunger is used to apply pressure to the paste, and the pressure is transmitted to all parts, so that the paste can be dense. In this stage, the pressing process, the force and movement (displacement) of paste are similar to that of molding. The second stage is extrusion. After the paste is precompressed, remove the precompression, remove the baffle, and then re pressurize the paste, extrude the paste from the die mouth, and cut it off according to the required length, which is the product of the required length and shape.
Baking is the most important technological process in the electrode production process, and also the most complex one. There are physical changes and chemical changes in this process. The mechanical strength, internal structure and properties of the graphite electrode depend on the amount of binder converted into coke during calcination, and the mechanical properties are directly related to the coking value. So each production of graphite electrode of the domestic large factory to the baking is very important. For the graphite electrode with high strength and high power, in addition to adding appropriate amount of needle coke into the mixture
A kind of Besides, it needs to be roasted twice or three times.
After the surface of the baked semi-finished product is cleaned, it is put into the iron frame, weighed first and then put into the preheating tank for preheating. According to the different specifications of the electrodes, the corresponding preheating time is 6 hours for the electrode below Φ 450mm, 8 hours for the electrode between Φ 450 and Φ 550mm, 10 hours for the electrode above Φ 550mm and 280-320 ℃. The preheated product is quickly put into the impregnating tank together with the iron frame. Before impregnation, the preheating tank has been heated to above 100 ℃, the tank cover is closed, and the vacuum degree is required to be above 600mmhg, and it is kept for 50 minutes. After vacuumizing, the coal tar pitch impregnating agent is added, and then the pressure is applied to press the impregnating agent into the air hole of the electrode. After vacuumizing, check whether there is water in the compressed air pipe. If there is water, drain it first, otherwise it will affect the weight gain rate. Then select the appropriate pressure time according to the size of the electrode, generally four hours. The ratio of the weight increased after impregnation to the weight before impregnation is used to measure whether the impregnated product meets the requirements. A kind of Similarly, in order to improve the quality of products and meet the requirements of customers, the electrode semi-finished products after baking also need to be impregnated twice or three times.
The so-called graphitization is a high-temperature heat treatment process (generally above 2300 ℃) which changes the hexagonal carbon atom plane network from two-dimensional disordered overlapping to three-dimensional ordered overlapping with graphite structure. To put it bluntly, carbon is transformed into graphite. The main difference between roasted products and graphitized products is carbon atom and carbon atom A kind of There are differences in the arrangement order .
Electrode processing is divided into four processes: turning outer circle, flat section, boring joint hole and milling joint hole thread. In mass production, three lathes can be used for flow operation. The outer circle of electrode body is not only to make the product reach a certain degree of finish, but also to eliminate the defects such as bending and deformation caused by the previous process. When turning the outer circle, one end of the electrode is stuck by a chuck, the other end is countered by a center, the turning tool is pressed on the carriage, the turning tool reaches a proper position, the workpiece rotates after starting the lathe, and the turning tool is horizontal Move to the direction, and the processing can be completed in one time. The semi-finished products can be handed over to the next process, flat section and boring. This is the center frame with corresponding specifications installed on the lathe, and one end of the electrode has a chuck A kind of Stuck, the other end is generally supported by a center frame at the distance from the two ends, and the joint hole is bored after the cross-section is flattened, or two turning tools can be installed on the tool frame and simultaneously moved in, and the other end can be processed after one end is processed. After processing the first product, check the coaxiality of the chuck and the center frame, if not, adjust it immediately. To process the thread in the joint hole, this process can be carried out by cutting the thread or milling cutter. The thread processed by milling cutter has good quality and high processing efficiency. The processing is carried out on a lathe equipped with a center frame and a milling cutter. One end of the electrode is stuck by a chuck, and the other end is held by the center frame. After starting the lathe, the electrode rotates slowly, and the milling cutter rotates at a high speed The direction is the same, after the tool setting, the thread is milled once, and the thread is milled. After the first product is processed, five gauges are used to check the coaxiality < 0.01, roundness < 0.03, outer diameter and flatness < 0.01, and the processing can be continued only after passing the inspection. Processed products are put into storage after inspection
Graphite electrode antioxidant macerate is a light white or colorless nearly transparent liquid formed by nanometer ceramic particles dispersed in water solvent. The liquid penetrates into the pores of graphite material and forms a thin protective film of high temperature resistance on the surface of pores and graphite matrix. This layer of protective film can prevent air and graphite material direct contact oxidation reaction. Moreover, the conductivity of graphite material is not affected, and the film formed in the surface of graphite matrix and the pores will not crack or peel off. Our company USES the formula alone, the use effect is better than other manufacturers
In order to improve the yield of graphite electrode and reduce the production cost, we must strictly control the process parameters. Through strict production monitoring of each production process, the production parameters are basically consistent with the established process parameters. The main quality factor of graphite electrode lies in the material allocation and process control. Therefore, the inspection in the laboratory is particularly important, and the inspection of each batch of raw materials and the inspection in the production process are essential.