| 摘要 |
<p>1375456 Percussive drills ATLAS COPCO AB 8 Sept 1972 [8 Sept 1971] 41820/72 Heading B4C [Also in Division F1] The dust brought up from the borehole in an air-flushed rock drilling operation is collected from a shell 1 through a suction outlet 8, the air being supplied forwardly through an annular space 6 formed by a neck ring 4 by means of an air ejector comprising an annular pressure air injecting slot 5. As shown in Fig. 2 the air ejector delivers a primary flow of air through the neck ring 4 from the slot 5 which is supplied with compressed air from an inlet 13, the flow causing a secondary flow 14 of sealing air into the shell 1. Dust is also prevented from escaping from the lower end of the shell by the intake of air 15 between a rubber skirt 9 and the rock face by the suction outlet 8. To promote rotational flow of the air and dust within the shell, the drill stem 10 and air ejector are eccentrically disposed in the shell 1 and the suction outlet 8 is tangential. The air ejector may be made in two halves 21, 22, Fig. 3, which can be pivoted to the opening position to let through the drill bit as shown in the left-hand side of the Figure; this ejector may be combined with a stem support 20. In Fig. 4 (not shown) a further air ejector is provided and positioned at the forward end of the housing to facilitate collection of an air, dust and water mix when drilling in formations containing water. Fig. 5 (not shown) illustrates a self-closing and self-cleaning air ejector having an elastomeric part (40) forming one side of the slot. The slot is opened to a size determined by the pressure of air during use. Particles jammed in the slot may be blown out by applying a higher air pressure.</p> |
