Abstract: The present invention provides a method for machining a workpiece, which comprises the steps of: separately supplying compressed air and a liquid into a through-hole longitudinally extending through a drawbar within a spindle of a machine tool; allowing the compressed air and the liquid to separately flow through the through-hole; mixing the liquid with the compressed air in a distal end portion of the through-hole so as to make the liquid into a mist form; ejecting the resulting mist from a distal open end of the through-hole to supply the mist to a distal end of a tool along an outer periphery of the tool or through the inside of the tool; and machining the workpiece while ejecting the mist from the distal end of the tool to supply the mist to a machining part.

Abstract: A trench shoring system using panels as shoring walls to prevent possible collapse of natural ground walls of trenches in trenches such as for burying pipes underground, having a sliding panels type trench shoring system that offers increased safety during the job, and higher job efficiency.

Abstract: A plug of an expansion beam for shoring up sand guards is equipped with a second non-return valve. If it should happen that the head of the plug is broken off owing to, for example, a falling rock, the second non-return valve works as a safety device to prevent the expansion and contraction of the expansion beam. Thus, the shoring up function is able to be maintained.