Arrangement with earth and rock drilling crown - involves pilot drill crown with threaded shaft on which space-producing drill crown is rotatably and eccentrically located

摘要

The threaded shaft on which the pilot drill crown is mounted is fixed in a corresp. hole in the front end of the cylindrical tool fixture, the rear end of which is either formed as a splined shaft fitting in a sink bore type rock drilling machine, or has a tapped hole matching the union threads in a drill rod for striking rock drilling. The central part of the pilot crown is formed as a shaft eccentrically placed in relation to the drillable, on which a space-producing crown with a stop heel formation is rotatably fitted. The tool fixture is provided with a projection which by feed force is brought into contact with the rear edge of the drill shoe firmly welded in the feed tube front end. During drilling a part of the striker energy from the drilling machine is transmitted via the projection to the feed tube for driving it forward.