Abstract
A performance and specific energy calculation procedure has been developed for diamond cutting machines used for the mining of natural stone blocks. The calculations are based on the natural stone diamond cutting theory according to which the stone cutting machine performance can be determined by the rated drive power of the cutting tool and by the specific energy of the tool-rock interaction. The specific energy can be estimated either through experiment or analytically. The work offers an analytical method of determining the specific energy of the rock surface destruction process based on energy consumption and ratios which are fractions of the total specific energy used for rock destruction, the tool and the friction between the rock and the tool. The energy capacity of the rock surface destruction process and its percentage ratio of the total energy consumption can only be determined through calculations which do not allow for friction. The energy capacity of the rock is described by the surface contact hardness which is Brinell hardness.
For a more accurate interaction between the diamond cutting tool and the rock when calculating the rock surface destruction factor, an active diamond grain principle was applied. The principle says that for front-end hole coverage a cutting tool should have a certain percentage of single-point diamonds. This helps to achieve an efficient rock destruction at the lowest percentage of single-point diamonds.
With the help of the data collected, it was possible to analytically estimate the specific energy and thus the diamond cutting performance depending on the cutting mode. Cutting at a constant specific energy has a number of advantages over cutting at a constant advance speed of the tool, which includes a higher performance and a lower specific energy. At the same time the energy based cutting mode leads to an increased specific tool consumption, which should be taken into account in each particular case by way of estimating and comparing the specific cutting cost.
The performance calculations performed were done for the cutting at a constant specific energy and followed two different patterns. In the first instance the specific cutting performance was estimated analytically based on the proposed procedure. And in the second instance the specific cutting performance was calculated based on the experimental data. Comparison of the two outcomes showed a discrepancy of no more than 10%, which means that the procedure developed can be recommended as a comprehensive method of estimating the performance of diamond cutting machines used to cut stone blocks of differing hardness.
Keywords
Performance, diamond cutting machine, specific energy, energy capacity, cutting mode.
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