We propose the idea of ​​using a ceramic material mold instead of a metal mold to deepen the stainless steel 3, 6.
This work first used reaction sintering method to prepare silicon nitride ceramic material mold, and then it was installed on the YA-100 type four-column hydraulic drawing machine to deepen the stainless steel experiment, and provided basis for the application of brittle materials such as ceramics in the stamping and deep drawing field.
2 Materials and Methods, 2.1 Die Preparation of Silicon Nitride Ceramic Material After the 100 mesh silicon powder was molded on a YA-100 hydraulic press, it was isostatically compacted under a pressure of 300 MPa. After roughing, it was sintered in a 50kW electric furnace at 1450 50 hours under normal pressure nitrogen. After the sintering is completed, the furnace is air-cooled and the end face and the inner edge are finished to the final size on the surface grinder and the inner edge grinder, respectively.
2. 2 The installation structure of the test device mould is shown in Fig. 2. To prevent the die from cracking, the Q235 steel sleeve should be hot-pressed outside the ceramic die.
The stainless steel used for the test is made of Japan with a thickness of 0. 5mm and SUS304. For the index of plate forming properties, see 6; for the deep drawing, the lubricating material is a water-based deep drawing lubricant. For the composition and properties, see document 7-8. The drawing equipment is YA-100. Four-column hydraulic drawing machine; Deep drawing product is stainless steel vacuum insulation cup lid.
Schematic diagram of the mold installation structure 3 Results and discussion 3.1. Surface quality of drawn parts and molds After inspection, Shandong Oil and Water Separator used this mold to deepen 2,000 products, and the surface of the mold was free from scratches and scratches. No surface defects, such as deep ribs, are produced near the surface; scratched and scratched surfaces on the surface of the drawn product are in full compliance with product quality standards.
Deep drawing test results The number of drawn parts The number of defective parts of 2, 000 drawn parts < 0. 1 The surface quality of the drawn parts The normal surface quality of Si 3 N 4 ceramics can be seen from the results of the above deep drawing test: Reaction sintering Silicon nitride ceramics can be successfully used in the manufacture of deep drawn metal molds.
3.2 Theoretical analysis of deep-drawing stainless steel in ceramic molds According to the basic principles of tribology and the principle of material selection for deep-drawing dies 9, deep-drawing must pass through strictly polished SUS304 stainless steel products in order to overcome scratches on the surfaces of drawn parts. , To reduce the cost of polishing, mold materials with completely different chemical composition, mechanical properties, and physical and chemical properties should be selected. In this study, the reactive sintering of silicon nitride ceramic mold materials satisfies the above principles and eliminates the root cause of scratches, thus achieving satisfactory application results.
In addition, due to the relative sliding of the parts of the mold and the workpiece and the plastic deformation of the plate, the reaction sintering of a silicon nitride ceramic material to deepen the SUS304 stainless steel product will generate a large amount of frictional heat and deformation heat. At this time, the silicon nitride ceramic protrusions will Water undergoes a violent tribochemical reaction, and the formation of SiO 2 10- 14 Si 3 N 4 + 6H 2 O 3SiO 2 + 4NH 3 SiO 2 will further undergo hydrolysis reaction with water to form an easily shearable Si(OH) 4 film, ie, : SiO 2 + 2H 2 O Si (OH) 4 Hydrolysis reaction product, one part will be dissolved in lubricant medium, the other part will be concentrated on the friction surface to form a layer of hydration film. Gao Yimin et al.10 investigated the tribological properties of Si 3 N 4 ceramics and metallic materials by using FTIR experiments to verify the gel-like SiO 2 and SiO 2 crystals produced on the frictional surface of the system.
This helps to reduce the friction and wear of the mold.
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