NO NOISE DRILLING MACHINE

摘要

PURPOSE: A hammer drill for drilling underground with low-noise is provided to remarkably reduce operation noise caused by excavation by using air pressure compressed in a compression chamber. CONSTITUTION: A hammer drill(100) for drilling underground with low-noise comprises a compression chamber. The compression chamber is arranged on the inner diameter of an outer sleeve(30) touching a hammer bit(50) and a piston(40). The compression chamber is composed of an outer cylinder(54a) and an inner cylinder(54b). The outer cylinder has an inner diameter in which the outer diameter of the piston is inserted and is inserted into the outer sleeve. The inner cylinder is installed on the top end of an air exhaust hole(51) of the hammer bit and has an outer diameter which can be inserted into the inner diameter of the piston.