• MATERIALS

    The impact of high voltage electric discharge treatment on the properties of Cu – Al powder mixture

    Machines. Technologies. Materials., Vol. 15 (2021), Issue 6, pg(s) 248-251

    Studies of the impact of high voltage electric discharge (HVED) treatment on the dispersion and phase composition of 87,5 % Al + 12,5 % Cu powder system were performed. It was shown that HVED treatment in kerosene with specific treatment energy of 5 MJ/kg leads to the decrease of mean diameter of treated powder from 15 to 13 μm, and the increase of specific treatment energy leads to the decrease of mean diameter of treated powder from 15 to 6 μm. X-ray diffraction analysis shows that CuAl2 and Al4C3 are synthesized in all considered treatment regimes.
    HVED treatment with increased specific treatment energy leads to the increase of quantity of synthesized Al4C3 phase. The use of “three point – plane” electrode system instead of “point – plane” during HVED treatment of 87,5 % Al + 12,5 % Cu powder system leads to the increase of quantity of synthesized Al4C3 and CuAl2 phases, while the efficiency of powders dispersion slightly decreases. Up to 40% of particles in powder mixture, treated by HVED in kerosene with the use of “three point – plane” electrode system, have diameter close to the diameter of the initial powder mixture

  • TECHNOLOGIES

    Technique of tooth relieving of worm hobs for cutting Novikov gears with double lines of action

    Machines. Technologies. Materials., Vol. 14 (2020), Issue 4, pg(s) 166-172

    Worm hobs for cutting Novikov gears have the profile of a generating worm, which varies not only in a radius, but also in a sign of curvature. A technique for relieving tooth flanks of these hobs by disk grinding wheel is developed. It allows for bringing together grinding and ground profiles in an axial section of the generating worm as close as possible. A method for calculating setting-ups and profile coordinates of the grinding wheel is given for real production conditions.

  • MECHANIZATION IN AGRICULTURE

    Experimental study results of the grinding process in a hammer-type shredder with side separating sieves

    Mechanization in agriculture & Conserving of the resources, Vol. 66 (2020), Issue 2, pg(s) 55-58

    The technical implementation of air-product flow control in the working chamber of a hammer mill for timely separation of conditioned particles from the main stream and their lateralization (removal to the side zones) for the purpose of evacuation from the working chamber is considered. The energy and quality indicators of the grinding process in a hammer mill with side separating sieves are determined. The obtained experimental dependences are necessary for the manufacture of hammer crushers for farms and the development of recommendations for the operation of hammer crushers with side separating sieves. Improving the conditions of the grain material separation process and timely unloading of the finished product from the grinding chamber makes it possible to achieve economic efficiency by reducing the content of the dust fraction in the finished product and reducing the specific energy costs of the grinding process.

  • MECHANIZATION IN AGRICULTURE

    Grinding characteristics and heat of combustion of sprouted wheat

    Mechanization in agriculture & Conserving of the resources, Vol. 65 (2019), Issue 4, pg(s) 117-119

    Pre-harvest sprouting is the premature germination of cereal seeds so that the embryo starts growing while still on the head in the field. Grain germination before the harvest is a serious problem in many wheat-growing areas of the world. The grain and flour quality parameters impacted by pre-harvest sprouting are strongly related with climatic variables and soil water condition. This process especially occurs when wet conditions delay harvest. Spouted seed is usually inadequate for flour productions. Products made of sprouted flour are generally unacceptable to producers and consumers. Moreover, it is also often inadequate as feed because microbiological contamination. However, it seems that such kind of waste grain can be utilized for energetic purposes. The aim of the present work was to study the grinding process of sprouted wheat. The heat of combustion of sprouted grain and sound grains was also determined. Three-day germinated kernels of three wheat varieties were used for investigation. After germination the wheat kernels were dried at 40°C by using an air dryer to obtain the same moisture as that of the grain before sprouting (14.0% w.b.). The sound kernels were used as a control sample. The sprouted and the sound samples of grain were ground by using the knife mill MG-200. The results showed that the sprouting of wheat had a significant influence on the grinding process, both on the particle size distribution and grinding energy requirements. The sprouting caused a decrease in the average particle size and value of specific grinding energy in all cultivars. The values of specific grinding energy ranged average from 21.6 kJ·kg-1 to 23.6 for kJ·kg-1 fore sprouted and sound kernels, respectively. The heat of combustion of sprouted grain was only slightly lower value of this parameter obtained for sound grain and ranged from 15.9 to 16.5 MJ/kg.

  • TECHNOLOGIES

    Effect of Al-Ti-C system master alloy high energy synthesis on efficiency of Ni based superalloy inoculation

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 8, pg(s) 331-334

    The possibility of high energy synthesis of Ti–Al–C system powder grain refiner by using high voltage electric discharges for treatment of powder mixtures of 75 % Ti + 25 % Al and 85 % Ti + 15 % Al composition in kerosene with subsequent briquetting by spark plasma sintering is shown in present work. It is found out that high voltage electric discharge treatment of powders leads to the increase of dispersity as well as to synthesis of new carbon containing phases during chemical interaction between system components and products of working hydrocarbon liquid destruction. The possibility of controlling this process by changing initial composition of powders, specific treatment energy and spatial distribution of plasma formations by changing electrode system type is shown. It is also shown that changing master alloy synthesis parameters allows controlling inoculation efficiency. Thereby it is possible to achieve surface or volumetric inoculation, so selective increasing of plastic or strength properties of Ni-based cast superalloys becomes possible. Introduction of 0.01 % of synthesized grain refiner during the casting of SM88U (СМ88У) superalloy allows decreasing mean grain size from 1…2 mm to 0.2…0.5 mm. Tensile strength of inoculated superalloy at the temperature of 900˚С was 68 MPa while their stress rupture strength increased by 20 % in average. Composition and properties of inoculated alloys comply with standard technical documentation, which allows their usage for the
    production of gas turbines blades.

  • MACHINES

    NEW TYPE OF INNOVATIVE LIFTERS

    Machines. Technologies. Materials., Vol. 10 (2016), Issue 8, pg(s) 9-11

    In this article the new shape of lifters for Semi-Autogenous Grinding (SAG) and autogenous mills has been investigated. Lifters are designed for lifting, separating the grinding bodies (at SAG mill) and the grinding material to the required height of separation, crushing and grinding of the material in order to achieve the required output particle size. The main purpose of these mills is material grinding and crushing. Lifters are most used in the mining industry. Hence, attention is paid to analysis of different working regimes of mills with new lifter shape.

  • THE DEPENDENCE OF THE PHYSICAL AND MECHANICAL

    Innovations, Vol. 3 (2015), Issue 1, pg(s) 25-27

    The results of studies of the influence of the type of machining and tool material to the structural state of the surface layer and the fatigue strength of ХВСГsteel during machining are shown. Processing with the composite-10 tool in a surface layer for α – and γ – phases is accompanied only by compressing residual pressure while abrasive processing promotes occurrence of stretching pressure of an I-type. Increasing of cutting speed of the composite-10 tool from 50 to 200 m/min does not lead to significant changes in fatigue strength.