石油取芯钻头石墨模具在热压过程中的受力状况分析

Analysis of forces on the graphite mold of core bit for oil during hot pressing

石墨模具以其优良的性能被广泛应用于热压孕镶金刚石钻头的制造。本文设计了两种规格相同(直径均为216 mm),但端部形状不同的石油取芯钻头的石墨模具,并利用有限元分析软件ANSYS对它们在热压过程中的受力状况进行了分析。分析结果表明:在18 MPa压力下,圆弧形钻头的模具在胎体与模具接合处出现了应力集中,超过模具的极限抗拉强度,导致模具破裂。因此,在设计钻头的石墨模具时,应考虑到钻头的端部形状,参考有限元分析结果再对模具进行设计,有助于优化设计,降低试验和生产成本。

Graphite mold has been widely used in hot pressing of impregnated diamond bit manufacturing owing to its excellent performance. The authors designed two kinds of graphite mold for oil coring bits of the same specification （diameter of 216 mm） but with different crown shape, and used finite element analysis software ANSYS to analyse the molds＇ force condition during the hot pressing process. The results showed that： under the pressure of 18 MPa, for the mold of circular-arc bit, stress concentration occurred at the junction between mold and matrix, which exceeded the mold＇ s ultimate tensile strength and caused the mold to rupture. Therefore, when designing the graphite mold of a bit, the crown shape of the bit should be taken into account, and the finite element analysis results should be used as references in order to optimize the design and reduce the cost of test and production.