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T10A钢中轴挡冷成型凹模,外型尺寸为φ130×80mm,要求热处理后硬度为HRC58～60。采用820℃×35min加热水冷,180℃×2h回火。处理后虽然硬度符合技术要求。但是,模具使用寿命很低,一般为2000次,有的只有几百次,最多8000次,多因模具早期开裂和零件卡模失效。模具在160t压力机上工作时每分钟承受20次的挤压和冲击,工作条件恶劣,要求模具有高的强度、硬度、耐磨性和良好冲击韧性。由于模具截面尺寸大,型腔孔径小,淬硬层薄,在冲击负荷下,型腔产生塑性变形、下凹和表面拉裂,造成模具早期失效。为了使模具表面耐磨并提高心部强度,我们改用高温快速加热淬火,即900℃×10min加热淬水,取得了明显效果。表1为新旧工艺处理后,模具型腔表面到心部硬度分布情况。从表1可见,模具型腔表面硬度可由HRC58～60提高到HRC61～63,距表面9mm处硬度可由HRC41提高到HRC52,距表面19mm处可由HRC36提高到HRC39,模具表面耐磨性和心部强度均提高。经生产实践考核,采用高温加热处理的模具,使用寿命都超过20000次,最高已达25000次。实践证明,碳素工具钢冷成型模具采用高温快速加热淬火,可提高模具表面硬度和淬硬层深度,提高使用寿命。
T10A steel shaft block cold forming die, the overall size of φ130 × 80mm, requiring heat treatment after the hardness of HRC58 ~ 60. Using 820 ℃ × 35min heating water cooling, 180 ℃ × 2h tempering. Although the hardness after processing meet the technical requirements. However, the mold life is very low, usually 2000 times, and some only a few hundred times, up to 8000 times, mostly due to mold early cracking and parts card failure. Die in the 160t press machine to withstand 20 times per minute squeeze and impact, poor working conditions, requiring high strength mold, hardness, wear resistance and good impact toughness. Due to the large size of the die section, small cavity diameter, thin hardened layer, under the impact load, the cavity plastic deformation, depression and surface cracking, resulting in early failure of the mold. In order to wear the mold surface and improve the strength of the heart, we use high-temperature rapid heating quenching, that is, 900 ℃ × 10min heating quenching, and achieved significant results. Table 1 for the new and old processes, the mold cavity surface to the heart hardness distribution. As can be seen from Table 1, the surface hardness of the mold cavity can be increased from HRC58 ~ 60 to HRC61 ~ 63, the hardness at 9mm from the surface can be increased from HRC41 to HRC52, the HRC39 can be increased from HRC36 to 19mm from the surface, the wear resistance and the heart strength All improved. The production practice assessment, the use of high temperature heat treatment mold, the service life of more than 20,000 times, up to 25,000 times. Practice has proved that carbon tool steel cold forming rapid heating quenching high-temperature, can increase the mold surface hardness and hardened layer depth, improve service life.