Quality Of Material Processing Research Articles

Electrothermal Effect on Organic Dispersed Hydraulic Systems

Of particular interest is the processing of agricultural products of plant and animal origin: vegetable and fruit juices, milk serums, potato juice, moist and moistened feeds and others that belong to organic dispersed hydraulic systems. The efficiency of processing these media can be improved by passing an electric current through them. (Research purpose) The research purpose is describing the mechanism of the thermal effect of electric current on organic dispersed hydraulic systems on the example of whey, searching for the role of the thermal factor in the regulating action of the current. (Materials and methods) Considered an organic colloidal solution simplistically as a two-phase dispersed system in which protein molecules act as a dispersed phase, and the rest of the colloidal system acts as a dispersed medium. In order to clarify the role of the thermal factor in the regulating action of the current, an electrical circuit for the replacement of a fragment of a medium with proteins was compiled. (Results and discussion) It was established that the electrical circuit of the substitution of the medium with protein molecules allowed calculating the processing parameters of colloidal solutions. Based on the results of the calculations carried out, it was shown that when such colloidal solutions are treated with electric current as a result of direct selective thermal action of the current, the temperature of protein molecules exceeds the average tempera­ture of the surrounding product by no more than 10 degrees Celsius. It was determined that the thermal effect of the current is an important factor in influencing colloidal solutions, however, an increase in temperature leads to an increase in energy consumption during electrical processing of these media. (Conclusions) The mechanism of the thermal effect of electric current on organic dispersed hydraulic systems – whey – was given. It was revealed that the obtained results are necessary for modeling electric and temperature fields that determine the uniformity and quality of material processing. It was stated that modeling the modes of electrical treatment of colloidal solutions will reduce the temperature of the medium and, consequently, the energy intensity of the process, optimize non-thermal factors during coagulation of colloidal solutions.

Формирование коаксиальных полей остаточных напряжений в полотне круглой пилы

The working tool of machines with circular cutting units is a circular saw, the condition of which largely determines the quality of material processing. Circular saw blades in the process of operation are subjected to a complex effect of force and temperature factors that cause elongation and deformation of the saw blade, and the occurrence of internal stresses that take it out of the flat form of elastic balance and reduce the tool’s performance. The ability of saws to resist these factors is determined by the rigidity and stability of the saw blade. It is customary to consider a circular saw blade consisting of three zones: peripheral, middle and central. The middle part has the greatest influence on the stability of the saw blade. Initially, after manufacturing, the saw blade has a flat shape of balance, which can be disturbed by any external impact on the saw during the cutting process. The balance disturbance causes the blade and the cutting edge of the saw to deviate from the initial operating condition and reduce the accuracy and quality of wood processing. In order to prevent the influence of external forces, coaxial zones of plastic deformation of a certain width are formed in the middle part of the blade. In this case, under the influence of the created stresses, the effect of web tension appears. In world practice, two methods of forming such zones are used: forging and rolling. The creation of normalized stresses in the circular saw blade is carried out by local mechanical contact action of the working body of the saw tool on the steel saw blade in certain places of the middle zone. Compressive stresses compensating the forces of centrifugal acceleration, the thermal heating of individual zones of the saw blade, the external longitudinal and transverse bending forces that occur in the blade during wood processing are formed in the treated annular zones. The considered methods for creating annular zones of plastic deformation fields involving mechanical action on the saw blade have significant drawbacks, the elimination of which requires fundamentally new technical solutions. It is proposed to form coaxial fields of residual stresses of the saw blade by thermoplastic action consisting in creation of normalized residual stresses in the saw blade by concentrated thermal action on local annular zones coaxially located along the saw blade for the entire thickness of the saw. The formation of coaxial circular fields of residual stresses in the circular saw blade is simulated. The considered method of saw preparation will increase its stability in the process of operation.

RESEARCH OF THE INFLUENCE OF LOW-FREQUENCY AND HIGH-FREQUENCY ACTIONS ON PROCESSING OF TECHNOLOGICAL ENVIRONMENTS

The processing of various vibrational low-frequency and cavitation high-frequency actions by their rheological properties is studied. A mathematical model of the motion of particles of a technological environment is determined taking into account the different nature of the dissipative forces. Two kinds of frictional forces are applied: dry at the first stage of changing the constituents of the mixture and viscous at the second, final stage of compaction of the mixture. The obtained analytical dependencies reveal the physical picture of the behavior of particles and the technological environment as a whole. The key stages of compaction to account for dry and viscous friction between the components of materials are described. It is revealed that processing at low frequencies reduces energy costs. Taking into account in vibroacoustic processes the contribution of higher harmonics greatly accelerates the process of cavitation. This is a fundamentally new result and the idea of the possibility of obtaining an effect for creating new materials. The obtained amplitudes and frequencies of oscillations of both low-frequency and high-frequency modes open a new direction in technologies for improving the quality of material processing. The main modes and parameters of vibrational and acoustic action for effective implementation of material processing processes are determined. The obtained results are applied at definition of rheological and technological parameters at various stages of processing of materials. The basic directions of quality improvement of processing environments are formulated.

Experiment study on performance of abrasive slurry jet with or without high polymer in stainless steel machining

Abrasive slurry jet (ASJ) with high polymer converges better than the one without it does, which has significant advantages in the cutting capability and quality in material processing. The paper carried out two groups of experiments to study the performance of ASJ with or without polymer additives in stainless steel cutting. In the first one, full factorial design method was used to study the effects of parameters (pressure, high-polymer mass concentration, and traverse speed) on cutting depth and kerf width. And a dimensionless model for predicting cutting depth was established with multivariable linear regression calculation. The orthogonal experimental method was adopted in the second group of experiments to study the effects of parameters (pressure, high-polymer mass concentration, traverse speed, and stand-off distance) on surface roughness with the range analysis and variance analysis method. And the surface roughness partition in ASJ cutting was obtained. The conclusions of the paper can provide technical guidance in material processing with ASJ.