Abstract: A surface coating applied to a subject surface includes an undercoating, a color base layer, coated over the undercoating layer, which contains a coloring material, and a color clear layer, coated over the color base layer, which contains a coloring dye of a hue within +/-10 from a hue of the coloring material of the base color layer on the 100-division Mansell hue ring.

Abstract: A surface coating applied to a subject surface includes an undercoating, a color base layer, coated over the undercoating layer, which contains a coloring material, and a color clear layer, coated over the color base layer, which contains a coloring dye of a hue within +/-10 from a hue of the coloring material of the base color layer on the 100-division Mansell hue ring.The color clear layer may be applied with a paint spray device while rotating the subject surface around an axis and continuously moving the subject surface along the axis to form a spiral pattern of paint spray relative to and around the subject surface at regular pitches. Preferably, the ratio of each of the regular pitches to a width of the pattern of paint spray is less than 0.3.

Abstract: A drilling method of drilling an imaginary facing for excavating a curved tunnel such that the imaginary facing is nonparallel to an existing facing. The drilling method includes the steps of obtaining a first equation for transformation between a primary coordinate system defined with respect to the imaginary facing and a secondary coordinate system defined with respect to the existing facing, transforming a primary drilling pattern of the primary coordinate system into a secondary drilling pattern of the secondary coordinate system, obtaining a second equation for transformation between the secondary coordinate system and a final coordinate system defined with respect to a drilling vehicle, and transforming the secondary drilling pattern to a final drilling pattern of the final coordinate system.

Abstract: An explosive charging apparatus for charging controlled amount of explosives sequentially to bores drilled in a rock surface. The charging apparatus includes an explosive charging pipe, a boom mechanism carrying the explosive charging pipe, boom actuators for actuating the boom mechanism so that the explosive charging pipe is moved to a desired position, a control circuit for controlling the boom actuators and the explosive charging pipe.

Abstract: This invention relates to an automatically controlled rock drilling apparatus which performs rock drilling operations as well as post-drilling operations such as explosive charging. Memory means are used during the drilling operation and reused during subsequent operations for follow-up work, specifically the charging of explosive to the drilled bores.

Abstract: A drilling apparatus includes a drilling rod, a feed motor for advancing and retreating the rod in relation to an object to be drilled, and a control system for controlling the movement of the rod. The control system includes a pulse generator for producing one long duration pulse upon completion of each rotation of the drilling rod, an oscillator for producing high frequency pulses, a counter for counting the number of high frequency pulses during the long duration pulse, and a control circuit for controlling the feed motor in response to the counted number of pulses, the control system operating so that the counted number of high frequency pulses equals a predetermined number during the period of the long duration pulse.The control system is arranged to increase the advancing force of the drilling rod when its rotational speed increases (i.e.