Parameter study of chain trenching machines of Underwater Construction Robots via analytical model
Analytical model by considering the kinematics, dynamics, and energetics of the trenching machine is adopted and proposed to design an underwater chain trenching machine at UCRC-KIOST. In this paper, parameter study and sensitivity analysis is conducted to show how the variations of operational and geometric parameters, as well as cutting tools and material condition affect the forces, moment, weight, and power components. The study sheds some important insights about how the trenching machine behaves and thus the information from this study can be used to design a trenching machine for the required working condition. The parameter study shows that minimum weight requirement for self-propelled vehicle is increased during operation at steep bar angle, and to keep the traction of the vehicle getting worst, it is recommended to cut the trench at low bar angle and make sure the cutting tool is still sharp. The results also show that traverse speed, cutting depth, uniaxial compressive strength, and trench width are the most sensitive parameters affecting the power and angular speed. On the other hand, weight of the vehicle, nose radius, bar length, and pivot point location does not affect the total chain power at all.
Mechanics of cutting and boring : part VI, dynamics and energetics of transverse rotation machines
Abstract : The report deals with forces and power levels in cutting machines having a disc or drum that rotates about an axis perpendicular to the direction of advance. The forces on individual cutting tools are related to position on the rotor and to characteristics such as tool layout, rotor speed, rotor size, machine advance speed, and rotor torque. Integration leads to expressions for force components acting on the rotor axis, taking into account tool characteristics, cutting depth of the rotor, and rotor torque. These provide estimates of tractive thrust and thrust normal to the primary free surface. For self-propelled machines, this leads to considerations of traction, normal reaction, weight and balance, and power/weight ratios. Specific energy consumption is analyzed and related to machine characteristics and strength of the material being cut. Power per unit working area is discussed, and data for existing machines are summarized. Power requirements for ejection of cuttings are analyzed, and the hydrodynamic resistance on underwater cuttings is treated. A number of worked examples are given to illustrate the principles discussed in the report. (Author)
Novel coal-cutting bits and their wear resistances. Report of investigations/1983
Based on earlier tests that showed steel to be much more likely to cause frictional ignition than tungsten carbide, the Bureau of Mines redesigned coal-cutting bits to reduce the hazard of face ignitions. Two bit designs--a muchroom-shaped bit with a conical shank and a dovetail bit with a rectangular shank--are described, as well as bit wear tests conducted in the laboratory and in an operating coal mine.