Introduction. Existing publications lack studies on the relationship between salt rocks physical properties, cutters geometry, cutting force, and intergranular fracture of rock under the cutter. By analyzing the system of cracks formed by the cutters between the cutting lines, it is possible to estimate the effi ciency of fracture and design the nature and conditions of cutting. Research aim is to obtain an analytical dependence that links cracks size, cutter geometry, and salt rocks crack resistance; calculate the cutting force; experimentally determine sylvine, halite and carnallite fracture toughness coeffi cients necessary for the calculation. And fi nally, based on the obtained data, the research aimed to build 3D graphs of crack length dependence on cutter geometry for a cross-cutting scheme. Methodology. Sylvine, halite and carnallite crack resistance coeffi cients were obtained by indentation. The coeffi cient values were used in the formula for calculating the size of cracks between the cutting lines in these rocks. The formula was corrected after D6.22 cutter indentation test in salt rocks. Light microscopy technique was used to study fl uid inclusions in salt rocks. Results. Analytical dependence, values of crack resistance coeffi cients were obtained. 3D graphs for halite, sylvine and carnallite were constructed for the cross-cutting scheme. The type, size and concentration of fl uid inclusions along the grain boundaries are given that accelerate intergranular fracture under the cutter. Conclusions. The resulting formula relates cutter geometry (cutting rim width and cutting angle) to the cutting force and viscosity of rocks. The formula was used to build the 3D graphs for sylvine, halite and carnallite for the cross-cutting scheme. The size of cracks under the cutter is connected with the presence of fl uid inclusions. The obtained analytical dependence allows to model the spatial distribution and size of microfractures in salt rocks under the action of the cutting tool. Excessive branching of cracks, energy intensity, and the number of small fractions decrease, when the trajectory of the cutter partially passes through the “technogenic” cracks of the previous bed. This is implemented in the cross-cutting scheme, where this group of cracks plays the role of “starting” ones. Their length in actual practice is important for justifying the optimal cutting parameters and estimating the cutter’s effi ciency.
On the issue of the oretical substantiation and development of a cutting working body for harvesting industrial hemp
