The precision gear is measured by vacuum carbonitriding heat treatment, and the layer is 0. 18～0. 20mm, and the quenching hardness is 728～731HV, which meets the technical requirements. Table 5 lists the inner hole measuring point 1 (lower end) and measuring point 2 (upper end), see the gear sectional view (see Figure 7), the inner diameter measurement value and deformation before and after heat treatment. When the difference between the measuring point 1 and the measuring point 2 of the same gear is ≥0. 01mm, the inner hole of the gear is a bell mouth, which is a scrap; otherwise, it is a good product. Therefore, from the bell mouth of Table 1, it can be seen that the 12 gears tested are all qualified products. This is sufficient to illustrate the advantages of small deformation of vacuum carbonitriding heat treatment.
3. Technical equipment and selection of vacuum carbonitriding
The cooling after vacuum carbonitriding can be oil cooled. When oil cooling, Table 6 lists the various types of double chamber vacuum carburizing and carbonitriding oil quenching furnaces. You can select the type you need according to the heating zone size and furnace weight in Table 6. Figure 8 shows the condition of the vacuum carbonitriding equipment and the surface of the workpiece after oil quenching.
Conclusion
The application of acetylene vacuum carburizing has brought the development of vacuum carburizing technology into a new stage. The carbon black in production is obviously reduced, the maintenance cycle is lengthened, the furnace loading is increased, and the production efficiency is improved. Compared with gas carbonitriding, vacuum carbonitriding is completely anaerobic, and the layered structure has no crystalline oxide layer. It is suitable for ordinary carbon steel, alloy steel and powder metallurgy. The heat treatment deformation is smaller than carburizing. high. For the basic parts and components of the machinery industry, the service life is increased and the national resources are saved. This is of great significance. The new technology of vacuum carbonitriding requires less infiltration gas and emission of exhaust gas, which saves gas, is clean and environmentally friendly, and is expected to be widely used.
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