Wear of the cutting tools of rock excavation machines

The rate of wear of rock cutting tools is very difficult to predict during the planning phase of a project. It is desirable to know which rock parameters should be assessed in advance, to predict the rte of wear and the type of wear that would operate for a certain rock using a certain type of excavation machine. Displacement controlled laboratory experiments, specially designed to study the wear of steel chisels cutting different types of rock, have been carried out. Apart from the rock type the feed of the test chisels into the rock has been varied. Above a certain value of feed, which was determined by the properties of the rock to be cut, the type of wear changed and the rate of wear decreased rapidly. Rock excavation machines with revolving cutter heads or chains, such as cutter suction dredgers, trenchers or turret-type tunnel boring machines have the arc-shaped cut of the cutting tools through the rock in common. During the arc-shaped cut the feed of the cutting tools varies from 0 to a maximum which depends upon the machine and rock characteristics. The implementation of the feed of a bit or pick of such a machine in the assessment of the expected amount of wear in rock cutting projects with such rock excavation machines enhances the accuracy of the wear prediction.