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一、概述在仪器仪表工业中,经常要采用各种类型的压铸件。随着现代工业的不断发展,仪表产品不断更新换代,因而对压铸件的质量也提出了更高的要求。例如防爆热电偶外壳,是一个典型的厚壁耐压零件,其平均壁厚为7.5mm,压铸后要加工外螺纹和细牙内螺纹,螺纹加工后只允许有两个直径小于1mm的气孔存在,并要求能耐压12kgf/cm~2。长期来由于内在质量不好,该零件的成品率一直很低,只有30%左右。过去虽对模具作了改进,合金采取除气精炼,并调整了压铸工艺参数,合格率仍低于68%,质量也不稳定。我们曾对J1113A型压铸机进行过测试,发现建压时间竟长达500～600ms,而最大压射速度只有2.9m/s,此时若无增压,压力冲击峰值可达到197kgf/cm~2,且该机慢行程又是固定的,也不能满足压铸工艺的需要。所以采用J1113A等类型压铸机已难于适应诸如厚壁耐压件、薄壁深腔件以及高气密防爆零件的生产要求。
I. Overview In the instrumentation industry, often have to use various types of die-casting. With the continuous development of modern industry, instrumentation products constantly upgrading, so the quality of die-casting also put forward higher requirements. For example, explosion-proof thermocouple housing is a typical thick-walled pressure parts, the average wall thickness of 7.5mm, die-casting to be processed after the external thread and fine thread internal thread, thread processing allows only two pores less than 1mm in diameter exists , And required pressure 12kgf / cm ~ 2. For a long time due to poor internal quality, the parts yield has been very low, only about 30%. Although in the past made improvements to the mold, the alloy to remove gas refining, and adjust the die-casting process parameters, the passing rate is still below 68%, the quality is not stable. We have tested the J1113A die-casting machine and found that the build-up time actually up to 500 ~ 600ms, while the maximum injection speed of only 2.9m / s, this time without pressurization, the peak pressure shock can reach 197kgf / cm ~ 2 , And the slow travel is fixed, it can not meet the needs of die-casting process. Therefore, the use of J1113A and other types of die-casting machine has been difficult to adapt to such as thick-walled pressure parts, thin-walled deep-cavity parts and high-density explosion-proof parts of the production requirements.