Side milling capability of rock cutting tools
Currently, the deviating hole drilling occupies a leading role in Russia. Directional drilling is used when the wells for oil and gas in Western Siberia, in the north of the European part, in the North Caucasus, in Tatarstan, Bashkortostan, Samara region and other areas are drilled, as our regions have a vast number of factors interfering with conventional drilling.
Finite Element Method for Prediction of Rock Breaking Performance of the Tipped Hob With Different Tooth Profiles
The raise boring machine, which plays a crucial role in wellbore construction, has been widely applied in subway tunnels and mine construction projects. High levels of quality and safety, make it recognized and promoted by an increasing number of users. The tipped hob as a rock-breaking cutter of the raise boring machine poses a direct influence on the efficiency of the well-bore construction. In this paper, the finite element software LS-DYNA is employed to establish the model of the crushed rock with the tipped hob, and the accuracy of the model is examined by experiments. On this basis, the variation laws and correlations of feed force, lateral force and positive force under different penetration depths are studied. The results show that as the penetration depth increases, the feed force, lateral force and positive force all grow exponentially. In the geological environment with high rock hardness, spherical tooth can effectively reduce cutter wear and conical tooth can achieve higher crushing ability. The research results provide a theoretical basis for the selection of a suitable tipped hob to improve rock breaking efficiency.
Microstructure evolution of Cu-Pb monotectic alloys during directional solidification
Abstract Planar, cellular and dendrite morphologies were observed at different concentrations in the directional solidification of Cu-Pb monotectic alloys. In Cu-Pb hypomonotectic alloys, the directional solidification microstructure changes from columnar dendrite to the irregular rod composite structure with increasing lead content and growth rate. In Cu-Pb hypermonotectic alloys, the structure changes from the band structure and elongated droplets to irregular rod composite structure with increasing growth rate. The range of composition of forming the rod composite structure around the monotectic points increases with the increasing growth rate. The transient morphology of Cu-Pb alloys in the directional solidification was obtained. The solid/liquid interface of Cu-Pb alloys presents planar and the second liquid droplets are pushed by growing front under the high temperature gradient With increasing growth rate or decreasing temperature gradient the planar interface becomes unstable and the cellular structures with L 2 phase at the cell boundaries are developed.