The results are presented of tests conducted at three different depths of cut and a velocity of 3.1 m/min on a work-hardening lead-alloy workpiece with a 10-degree-rake photoelastic tool. In addition to examining the behaviour of the chip-tool contact stresses, the paper considers the forces acting on the tool and distinguishes three areas: rake, nose, and flank. It evaluates the rake forces from the photoelastic results directly, estimates the nose forces by making certain assumptions with regard to the distribution of stresses, and neglects the stresses on the flank. The sum of the forces so obtained is then compared with the measured resultant cutting force; there is good agreement. There is a particularly significant observation which, contrary to previously published results, shows that the frictional stresses vary linearly in the so-called sticking zone and tend towards a constant only at relatively high depths of cut. This is discussed in relation to the general concept of plastic friction and the variation of the coefficient of friction on the rake face. The significance of the measured resultant coefficient of friction is also considered.

The paper analyzes the properties of rocks with a shale structure, justifies the need to apply force in the direction of the lowest strength. The list of crushing equipment used in the process of obtaining cube-shaped crushed stone is given. It is established that the existing crushing equipment is not able to take into account the specific texture of the crushed materials and this does not allow obtaining cube-shaped crushed stone from shale materials. A description of the new design of the press-roll unit, which allows obtaining cuboid crushed stone from rocks with a shale structure, is given. The press-roll unit includes a device for directional feeding of shale materials to its working bodies, which create a force effect on the fed pieces of rock in the required direction. The design of the tooth of the working body is described, which allows to reduce significantly the replacement time of worn elements and reduce the bending loads acting on it. This leads to an increase in the reliability of the structure and reduces the metal consumption of repairs. A mathematical model of the directional movement of shale materials in a roll device is considered and an equation for calculating the required force is obtained. Graphical dependences of the influence of the roller installation angle and its horizontal and vertical displacement on the amount of deformation of the feed material layer are presented.

been selected from 260 different architectures. The selected ANNs are able to predict the impinging penetration length with mean square error (MSE) lower than 0.00097 and correlation coefficient higher than 0.98921. Moreover, the selected ANNs for predicting the spray cone angle have maximum MSE of 0.0004 and minimum correlation coefficient of 0.99439. According to weights and bias of the designed ANNs, two set of equations are proposed for predicting the impinging penetration length and cone angle. Moreover, Based on CFD results, longer impinging penetration length and larger cone angle are achieved using higher injection pressure and ambient temperature and lower backpressure.

The paper provides an analysis of grinding systems used in the world practice, including the main technical solutions in the field of fine grinding of materials using a ball mill, and also presents indicators of their efficiency. It was found that the grinding systems of the partitioned grinding process with pre-grinding in a press-roll grinder showed the greatest efficiency from their use. However, today in various countries, free-standing units are used for deagglomeration of pressure-pressed semi-finished products, which require additional space for their placement and operation and maintenance costs. The authors describe the design of a press-roll unit with a device for breaking pressure-pressed materials, which allows reducing these costs, as it performs the following technological operations: volume-shear deformation of the material is carried out due to the conical profile of the main rolls; the compressed materials are disaggregated in the reverse direction of compression by means of additional rollers that have a reverse taper to the main rolls. A scientifically-based method for calculating the energy index of a new design of press roll unit is proposed, which allows for the energy calculation of these machines.

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