Authors

Abstract

In the abandoned mine area with Karst landform in China, soils are few and thin but rocks are common, traditional planting hole diggers are unequal to work in rocks for vegetation restoration. A reamer bit with variable lateral drilling radius was designed based on the PDC (polycrystalline diamond compact) bit technology and metamorphic mechanism. Two lateral camber blades with PDC teeth were installed inside the bit body, a screw mechanism was employed as the actuation and a spatial double triangle mechanism was taken for the transmission. The curve of the camber blade was specially defined thus the reaming load was decentralized to 85.7% teeth on the blade. The kinematics of the lateral reamer bit was analysed, the mapping models from the actuation to the reaming radius and speed were established. Concrete samples were reamed indoors from 240mm to 407mm in diameter, the reaming cutting load and time length were measured and analysed. The lateral reamer bit was approved with the experiment results, this study provided equipment support for digging the planting hole in rocky abandoned mine areas and also expanded the PDC bit application.

Abstract in Chinese

中国岩溶地区废弃矿山缺乏土壤岩石大面积裸露，传统植树挖坑机无法在岩石中挖坑造林，生态恢复难度大，亟需研制岩石钻孔挖坑机。结合岩石PDC钻头技术及变胞机构理论，设计了横向可变钻削半径的扩孔钻头。钻头内对称布置了2个镶PDC齿的横向曲面刀翼，以螺旋传动机构为变径驱动，以空间双三角形机构为传动机构，为均衡扩孔载荷单独定义了曲面刀翼形状。分析建立了横向扩孔钻头的运动学模型，推导了驱动螺旋到输出扩孔半径及速度的映射模型。以混凝土试样为对象，进行了室内横向240mm至407mm直径的扩孔试验，测试分析了扩孔过程中的载荷曲线及时间。验证了横向岩石内部扩孔挖坑的可行性,本文的研究为岩溶地区废弃矿山的挖坑造林提供了装备支持，同时扩大了PDC钻具技术的应用场景。