Shigen-to-sozai, Vol.116, No.9, pp.759-766.
Analysis of Water Jet Drilling and Chipping
upon Drilling by the Third Power Method
Katsuhiko SUGAWARA1, Akira SATO2 and Takayuki HAMAURA3
| 1. Graduate School of Science and Technology,
Kumamoto University, Kurokami, Kumamoto 860-8555 2. Faculty of Engineering, Kumamoto University 3. Tokyu Construction Co., Ltd. |
| A new scheme called the Third Power Method is proposed for the quantitative analysis of water jet drilling process. The drilling speed is formulated as a function of the erosion strength : Se of materials and the effective pressure : p of a water jet impinging on the bottom surface. The method is successfully applied to the pure water jet drilling in sedimentary rocks and fine ceramics. The attenuation of the effective pressure : p is evaluated from the measurement of the time-dependent drilling depth, as well as the erosion strength of materials which is correlative to the tensile strength of materials. As an application of the method, the chipping upon drilling is analyzed, which is a tensile fracture characteristic of brittle materials. It is clarified that the incidence of chipping increases with decreasing the tensile strength of materials, and that it occurs from the circumference of the bottom in the case that the effective pressure : p is greater than the tensile strength of materials. |
| KEY WORDS: Water Jet, Erosion, Chipping, Drilling, Rock, Fracture |