Increased Productivity by Improved Cuttiig Technology

Summary

This paper concerns the adaptation of cutterhead-roadheaders for driving galleries along seams and in sterile rock for the purpose of underground coal mining. With increasing efficiency and reliability of this type of machine the range of use could be pushed to always harder partition rock. Here a very clear limitation could be found by the maximum possible loading of a pick and the danger of inflammation of methane-air mixtures, caused by excessive temperatures generated during the cutting process.

In co-operation with the users and research institutes the range of use of this type of machine could be extended by improved mechanical resistance of picks and pick-holders and by assembling a nozzle, situated inside the pick-holder and working with high pressure water.

This research was performed by tests on a test bench of a research institute, in the plant and underground. The results were evaluated by observation and continuous measuring of the most important parameters.

The results gained up to now are encouraging. Pour main effects could be achieved as follows;

• - the stronger picks reduce the breakage of the tungsten carbide tips;

• - the nozzles produce sufficient cooling of the pick, so that methane ignitions and inflammations can be avoided;

• - cooling and “sealing” of the picks by the high pressure water reduce abrasion to a great degree—this leads to longer endurance of the pick and keeps the tips sharper;

• - by bringing the high pressure water immediately to the location of dust formation, dust suppression is highly improved and so also the working conditions on site.

The results so far show that after some improvements the system will be ready for use at the end of 1980. This will permit the use of cutterhead-roadheaders—mainly for the purpose of driving galleries along seams and in sterile rock—in harder and more abrasive rock types in an economic, attractive way.