Investigation into spatial variability of rock cutting data of a conical tool

The main purpose of this thesis is to analyze the one dimensional rock cutting signals by geostatistical methods. To provide for better understanding of rock cutting mechanisms. At the first part of thesis, descriptions of rock cutting theory and geostatistical methods are briefly summarized. Secondly, variogram analyses are applied to rock cutting signals obtained from linear cutting tests of 6 different rock samples with a conical cutting tool by using GS+ software to calculate variogram parameters which are sill, nugget and range. Then, the variogram parameters are correlated to cutting performance parameters obtained in relieved and unrelieved cutting modes such as depth of cut, average and maximum cutting cutting and normal forces, specific energy, optimum specific energy, coarseness index and optimum coarseness index previously obtained from linear cutting tests and rock properties. The relationship between variogram parameters and depth of cut indicate general and positively proportional trends for both relieved and unrelieved cutting modes and for both normal and cutting force data. Analysis of the unrelieved normal force data indicates that while the sill has good correlations (positively proportional trends) with the tool forces at both 5 and 9 mm depths of cut, the nugget and range do not have any significant relationships. Specific energy and coarseness index do not significant relationships with variogram parameters at these cutting conditions for normal force data. Analysis of the unrelieved cutting force data indicates that while the sill and nugget have good correlations (positively proportional trends) with the tool forces and specific energy at both 5 and 9 mm depths of cut, the range does not have any significant relationships. Specific energy and coarseness index do not significant relationships with variogram parameters at these cutting conditions for cutting force data. Analysis of the relieved normal and cutting force data obtained at optimum cutting conditions indicates that all the variogram parameters have promising correltaions with the cutting performance parameters, except for coarseness index, at both 5 and 9 mm depths of cut. Any significant relationships can not be found between the rock properties (uniaxial compressive strenght, tensile strenght, static and dynamic elasticity modulus) and the variogram parameters. This study shows that some of the cutting performance parameters of conical tools can be generally predicted by variogram parameters determining spatial variability of regionalized parameters. However, it is indicated that the range parameter is not enough to explain chip size and/or chipping mechanism for conical tools.