Drilling arrangement with telescopic drill string and method of making ground and rock boreholes with a telescopic drill string

摘要

In a drilling arrangement for making ground boreholes, which is equipped with kelly bars (4) which can be moved apart telescopically with the assistance of a feed drive and feed members, locking elements (22, 23) are located at a distance from one another on the endless feed member (11) interacting with a stationary guide (2), which locking elements (22, 23) are located below and respectively above a stop (21) fastened to the guide (2). The result of frictionally induced locking between the kelly bars (4) during the drilling advance is that the entire drill string can be advanced as a rigid body by means of the feed drive without relative movement between the kelly bars, specifically by an amount which corresponds to the distance between the locking elements (22, 23). In the absence of locking between the kelly bars, the drill string can be advanced in a manner known per se with positive guidance of, i.e. with relative movement between, the individual kelly bars (4). <IMAGE>