Grinding Quality Research Articles

Дослідження впливу схеми розташування ножів котка-подрібнювача на показники якості подрібнення стебел соняшнику

The study of the arrangement of the blades of the roller-grinder on the quality of grinding. It is The work is devoted to the improvement of the technological process of grinding sunflower stalks due to the study of the influence of the arrangement of the blades of the roller-grinder on the quality of grinding. in the range of 5… 20 °. It is noted that under 800 kg by loading the roller with the right location of the chopping knives, the lowest value of mathematical expectations of the distribution of crushed stem particles is set at 18.6 km / h. This value is 14%, 30%, 40% and 20% less than the speed , respectively, 7.45 km/h, 10.08, 13.6, 22 km/h. Exceedance of values of mathematical expectations of distributions of particles of stalks at a roller-shredder with the left scheme of an arrangement of knives over the right, for loading of 800 kg, at all speeds investigated is established. The lowest value of mathematical expectation for the right layout of the knives was set at a speed of 18.6 km / h, and for the left - at a speed of 13.6 km / h. The highest value of the mathematical expectation of the distribution of parts of sunflower stalks at the left location of the knives is set at a speed of 10.08 km/h, and for the right scheme - at a speed of 13.6 km/h. Exceeding the lowest value of mathematical expectation over the highest within one scheme of placement of knives was - on the left 48%, on the right 41%. In the roller with the left location of the cutting edge of the knives, with a load of 600 kg in the range of 51–100 mm, the percentage of crushed particles of sunflower stalks exceeded the corresponding values with a load of 800 kg. At speeds of 10.08 km/h, 13.6, 18.6 and 22 km/h, this excess was 1.9 times, 1.44, 1.96 and 1.99 times, respectively.

FIELD TESTS OF THE EXPERIMENTAL INSTALLATION FOR SOIL PROCESSING

It is experimentally established that the quality of soil grinding by the experimental ripper-separator is especially affected by the humidity and density of the composition, so at a soil density of 1.3–1.4 g/cm3 and a minimum soil moisture of 11.4–14.4% rotor speed must be increased up to 127 rpm.

<span style="white-space: normal;"></span><span style="white-space: normal;">Grinding mechanism of titanium alloy: Research status and prospect</span>

Titanium alloy material has excellent properties such as low density, high strength, good oxidation resistance, creep resistance, etc. It has a broad application prospect in various fields. However, these characteristics also make it dif-ficult to process. Grinding is an essential method for high efficiency and precision machining of titanium alloy, ob-taining good machining precision and surface quality. The removal mechanism of titanium alloy is helpful to im-prove the surface quality of titanium alloy grinding. The recent research results in this field are reviewed. Firstly, the grinding technology types of titanium alloy were summarized, and the machining characteristics were systematically analyzed from two aspects of abrasive wear and material removal behavior of titanium alloy. Finally, the development trend of titanium alloy grinding technology in the prospect.

Rigid Shape Matching for 3-D Robotic Grinding Measurement With Applications to Blades

Robotic grinding is a promising method to form the surfaces of industrial components, which improves product quality, lowers machining costs, and reduces processing time. Allowance optimization is a surface matching process, which is important to grinding measurement. The grinding efficiency highly depends on the results of the surface matching between measured points and the design model. However, existing matching methods are usually based on distance and variance minimization, ignoring the grinding requirements to different surfaces, which leads to high processing time and unstable grinding quality. In this article, we proposed a novel surface matching method for robotic grinding. The objective function is constructed via time minimization and involving weights for allowance requirements to different surfaces. This method also balances all measured points’ contributions, avoiding matching distortion due to uneven points’ distribution. Experimental results and comparisons verify the effectiveness of our methods. Comparing to existing matching methods, our method is robust to uneven point distribution and has advantages in reducing the grinding time.

A Method of Robot Grinding Force Control Based on Internal Model Control Principle

The application of robots in the grinding industry can solve the problems in traditional artificial grinding, such as high labor intensity, low work efficiency, unguaranteed processing quality and serious physical injury to workers. In order to ensure the grinding quality, it is necessary to control the grinding force. The aims of this study is use PID-IMC controller to control the grinding force. Carry on the robot dynamics analysis to establish the dynamics model. Based on the principle of internal model control (IMC), PID controller is optimized and PID-IMC controller is obtained, which is used to realize the constant force control of robot grinding. Simulation and experiments results show that, the dynamics model and control method proposed in this paper have a better effect in the control of robot grinding force.

Detection and Analysis of Rice Quality of Yunnan Purple Rice Seed Resources

Purple rice, as a special rice with important nutritional and health functions, has important scientific significance and application value for genetic improvement of purple rice and breeding of new varieties through in-depth study on its grain quality characters. In this paper, the grain quality characters of 39 kinds of purple rice introduced from Yunnan were tested, and the test results were analyzed comprehensively, which provided scientific basis for the introduction and popularization of high quality purple rice in Yunnan. Taking purple rice germplasm resources introduced from Yunnan Province as experimental materials, the appearance quality, cooking and eating quality, cooking and eating quality of 39 kinds of purple rice were analyzed by using near-infrared grain analyzer, automatic amino acid analyzer, viscometer and microwave digestion instrument combined with biochemical and physical-chemical analysis techniques and methods the grinding quality and nutritional quality were detected and analyzed. The results showed that there were abundant variation types in grain length, grain width, ratio of length to width, gelatinization temperature, taste value, amylose content, viscosity of rice flour, protein content, amino acid content, brown rice rate, milled rice rate and head rice rate. In particular, the appearance quality of grain type, milling quality of head rice rate, nutritional quality of amino acid content, cooking and eating quality of Rice Flour Viscosity, eating value and gelatinization temperature and other important quality traits in rice materials have a wide range of variation. Therefore, the results of this study provide important genetic and breeding resources for the breeding of new rice varieties with high quality.

PREPARATION OF WOOD FIBER SEMI-FINISHED PRODUCTS IN KNIFE MACHINES OF VARIOUS MODIFICA-TION

In this paper, we consider the results of a study of the influence of the design and technological parameters of grinding machines of various modifications on the quality of wood pulp.
 According to the results of processing multifactor experiments implemented according to the second-order B-plan, a mathematical description was obtained of the dependence of the degree of grinding of pulp on the gap between the grinding disks, wear of the segments, the rotational speed of the lower screw and the concentration of pulp. The obtained regression models are adequate to the process and can be applied in practice for predicting the qualitative characteristics of wood pulp depending on the parameters of the grinding process.
 Analyzing the obtained experimental data, it can be noted that such factors as the state of the surfaces of grinding disks, the gap between them and the concentration of wood fiber have the greatest influence on the degree of grinding of the mass. Evaluation of graphical dependencies allows you to determine the extent to which you can vary the operating and design parameters of the grinding process to obtain wood fiber with the required grinding quality.

OBTAINING AN ANALYTICAL DEPENDENCE OF THE STRENGTH PROPERTIES OF PAPER ON THE PAPER-FORMING PARAMETERS OF THE FIBROUS MASS

Wood is of great practical importance as a starting material for the recovery of cellulose. Wood plays not only an important economic role as a building and finishing material, but is also one of the cheapest and most widely used raw materials for the industrial production of cellulose vines. In turn, the grinding equipment serves to divide the cellulosic materials into fibers, from the grinding of the fibers and imparting certain properties to them. One of the most important properties of paper is mechanical strength. The standard provides for certain requirements for different types of paper, depending on the consumer conditions for the use of finished products. Durability of paper is determined by various indicators characterizing: paper resistance to a gap, breakdown, tear, an anguish, lengthening to a gap. In this work, the role of milling of fibrous materials in the general preparatory cycle of pulp and paper production is considered, the advantages of knife-free milling are presented, the factors determining the strength of paper are considered, functional dependencies of the main physical and mechanical characteristics of the finished product on the complex parameter of the quality of pulp milling and the complex parameter of the machine are obtained. Numerical value of complex parameter of grinding quality is determined depending on duration of grinding.

CONTROLLED VIBRATING MILL FOR GRINDING BULK MEDIUM

One of the advanced types of grinding equipment are vibrating mills, which provide high specific productivity at relatively low energy consumption, adjustable tone of grinding products. Vibration impact on the product significantly increases the shock-absorbing effect with the possibility of wide and separate variation of shock and abrasion factors. Significant speed of mechanical and heat and mass transfer processes, a high degree of homogeneity of the obtained products, the possibility of efficient fine grinding and dispersion of the product at relatively low energy consumption lead to the widespread use of vibratory grinding. The constructive scheme of the mill is developed, in which the flat vertical vibrating field provides lifting of a part of loading and by means of the transport-reloading device carries out its continuous adjustable movement from one grinding chamber to another, thereby circulating-spatial movement of the environment in which there is a grinding process. shock interaction of grinding bodies and material that is crushed. The priority direction of development of science and technologies at the modern level is the development, creation and implementation of new generation mechatronic systems. One of the most important rules for the construction of vibrating mills is the need to maximize the degree of their automation in order to increase productivity, improve the quality of grinding and reduce the cost of the process. Also in the article the structural model of the controlled vibromill with spatial-circulating loading movement which at change of weight of a working body in the course of separation and unloading of the crushed material from a grinding chamber constantly adapt to a resonant mode of work at the set technologically optimum parameters (productivity) and the minimum power consumption.

The Applied model of grinding a spherical solid particle with a direct impact on a non-deformable flat surface

A grinding process using a free impact breakage mechanism is used in industries. In order to make calculations, predict grinding results, and evaluate mills functioning, it is necessary to assess the parameters of the grinding process and interrelations between the process parameters, mills parameters and materials properties, i.e. it is necessary to use an adequate mechanical-mathematical model of the process. However it is difficult to model due to some phenomena occurring in this process. Nowadays, various researchers have established the basis for the structure of the grinding process, but the application of the existing hypotheses and methods to evaluate the grinding process is quite difficult. This paper solves the problem of a spherical shape particle impacting an absolutely rigid half-space. It proposes a refined mechanical and mathematical model describing the process of destruction of the particle using the free direct impact breakage mechanism on an absolutely rigid, stationary, and flat surface. By using the Hertz-Staerman's classical analytical dependencies on the force contact interaction of the spherical bodies and the technical theory of the longitudinal waves’ propagation in the elastic continuous medium, we obtained a new refined solution of the applied dynamic problem related to a direct impact of a ball simulating a particle of a feeding material (an absolutely rigid surface simulating the working body of the mill) taking into account local physically linear deformations, the time parameter and radial particle size. The improved theoretical model of the spherical particle destruction was brought to applicable analytical calculations, tested and illustrated by a numerical example. It made it possible to describe the fracture of the material particles, predict the result and calculate the grinding process depending on its parameters providing the required quality of grinding by regulating and selecting characteristics, designing and selecting the grinding equipment, and modeling the grinding process using the free impact breakage mechanism.

Research on variation of grinding temperature of wind turbine blade robotic grinding

As a large composite curved surface component, the wind turbine blade is easy to suffer from grinding burn if the grinding parameters are improperly selected during the robot grinding process, which will seriously affect the surface grinding quality. In order to effectively predict the surface grinding temperature of robot grinding wind turbine blade, the curved surface grinding heat source model was established according to the material removal depth of any grinding point in the grinding contact area, and the temperature field under different grinding process parameters was numerically simulated using finite element method. The comparison between simulation and experiment indicates that the temperature on both sides of grinding contact area is higher than the middle temperature, and the maximum grinding temperature value appears on the cut-out side of the cup wheel. The maximum grinding temperature increases as increasing the wheel speed, feed rate and maximum grinding depth, feed rate is the biggest influence factor on the grinding temperature. The maximum grinding temperature of finite element simulation is in good agreement with the experimental results and the maximum relative error is <6%. The research results reveal the variation law between the curved surface grinding parameters and grinding temperature of curved surface grinding, which provides reference and basis for the prediction of grinding temperature of the wind turbine blade ground by robot.

An adaptive parameters adjustment and planning method for robotic belt grinding using modified quality model

As a kind of flexible manufacturing system, the machining quality of a robotic belt grinding system is related to a variety of factors with strong time variation, which easily leads to process fluctuations and affects the final quality. Therefore, it is a great challenge to control the quality precisely during the whole grinding procedure. Focusing on this problem, an adaptive parameters adjustment and planning method for robotic belt grinding using the modified quality model is proposed in this paper. Firstly, the correlation analysis method of grinding parameters in time domain is presented based on an improved-Mahalanobis distance. The response surface methodology (RSM) is utilized to construct the quality prediction model, and furtherly the parameter sensitivity function, which can characterize the influence degree of different parameters on the grinding quality, is introduced to calculate the Mahalanobis distance for improving the accuracy of the correlation analysis method. Secondly, based on the correlation analysis, a conversion method from the old samples into the new samples space is presented using vector field smoothing algorithm (VFS), then the modified grinding quality model can be re-established adopting the new samples. Furtherly, taking the problem of poor robotic response rate into consideration, a multi-parameters collaborative planning method under the smoothness constraint is developed using particle swarm optimization (PSO) algorithm, which can avoid the parameter mutation and improve the process stability. Finally, belt grinding experiments on a curved surface were carried out based on the robotic grinding platform. The results show that the approach can improve the grinding shape accuracy, which verify the effectiveness of the proposed methods.

Pose Error Estimation Using a Cylinder in Scanner-Based Robotic Belt Grinding

Scanner-based robotic grinding has shown great potential for replacing the manual method to achieve efficient and automatic manufacturing. However, its application has been limited by the grinding quality, which is affected by the pose errors between the robot and other workcells (a scanner, a workpiece, and a tool). To improve the pose accuracy, this article proposes a novel estimation method for above three pose errors, where a cylinder is used as the calibration object. Using differential kinematics, the relationship between the hand-eye pose error and the reconstructed error is built. The hand-eye pose error is estimated by scanning and reconstructing a cylinder. An iterative method is presented to find the optimized orientation error vector, avoiding the uncertain error of multiple solutions using the Schmidt method. Based on the speed adjoint transformation, a mathematical model between the workpiece/tool pose errors and grinding error is built. Then, an experimental estimation approach for the workpiece/tool pose errors is presented by shape matching the measured points of the grinded cylinder with the design model. Unlike the traditional static construction method, this method uses large-scale measured points with high measurement accuracy to improve the estimation accuracy and stability and can estimate the pose error caused during the dynamic grinding process, such as vibration and force deformation. Finally, pose error estimation and compensation experiments are performed to verify the feasibility of the proposed method.

Моделирование процессов получения древесноволокнистых полуфабрикатов в целях расширения сырьевой базы лесопромышленных предприятий

Currently, materials made of wood-fiber semi-finished products are widely used in house building as structural, finishing and insulating materials. According to the results analysis of numerous studies, the raw material for their production is technological chips of woodworking waste. While production, the chips are subjected to hydrothermal treatment and further grinding in disk knife grinding machines in two stages. Significant energy consumption of the wood fiber production process is driven not only by grinding wood chips in stages, but also by overcoming the hydrodynamic resistance of the aqueous environment, where grinding is carried out. The process of grinding wood chips, made of from chopping residues, in an aerodynamic medium on an upgraded cross-bar mill was studied in order to solve the problem of expanding the raw material base for the production of a wood fiber semifinished product and reducing the energy intensity of the grinding process. The features of this process were analyzed and its effectiveness was assessed. The influence of the exposure time of wood chips of chopping residues in an acetic acid solution, the size of the working gap and the angle of inclination of the front edge of the knife on the grinding degree and fractional quality of wood pulp grinding was determined. Statistical and mathematical equations, that describe the studied process, were obtained, and the graphical dependencies are constructed. The following basic requirement is fulfilled for the dependencies: the experimental points for a total should lie quite close to the curve. These equations allow predicting the quality of wood pulp depending on the set modes of the grinding process; as well as determining the quality indicators of wood pulp with known values of the technological and structural parameters of the grinding machine. The efficiency of the process of obtaining the wood-fiber semi-finished product in an aerodynamic environment from wood chips produced as a result of chopping residues (branches, twigs, etc.) processing in a mobile wood chipper, is proven.

Mathematical modeling of the process of grinding grain materials

The problem of providing peasant (farmer) households with the means of production is currently very relevant, since the existing prototypes of equipment do not always satisfy both the necessary and sufficient conditions for its use. With small production volumes, it is rather difficult to ensure a high load factor and uniformity of high-performance equipment. High prices for energy resources in agricultural enterprises do not allow producers to reduce prices for their products, as a result, it negatively affects, first of all, consumers. Consequently, in the modern conditions of the functioning of peasant (farmer) farms, the development of new and improvement of existing means of mechanizing the production process, corresponding to the foundations and principles of resource conservation, comes to the fore. Among the means of mechanization for grinding grain materials, the most common are universal impact crushers with articulated hammers. They are able to grind various types of raw materials, are relatively simple in design and convenient in maintenance and operation. Their design allows easily changing wear parts (hammers, decks, grates). At the same time, modern designs have significant disadvantages such as the following ones: high metal consumption and energy consumption of installations, uneven grain size distribution with an increased content of dust particles, intensive wear of working bodies and the associated decrease in productivity and quality of material grinding.

INTEGRATED STUDY OF THE EFFICIENCY OF GRINDING MATERIAL IN AN IMPACT-CENTRIFUGAL MILL

Grinding processes, which are very common and occurring in almost any industry and agriculture, require large energy costs and are associated with irretrievable losses due to wear of working units of grinders. It is generally recognized that reduction in specific energy costs is possible when using mills in which grinding will be carried out mainly due to the impact loading of a material. The results of studies of a single impact grinding of materials with various physical and mechanical properties, depending on the impact velocity and design features of a grinder in an impact-centrifugal mill, are presented. Experimental dependences of impact-centrifugal grinding are presented. Graphic dependences of the median particle mass distribution of a ground material depending on the number of blades are obtained. The number of blades for a given rotor diameter (0.4 m) was 4, 6, 8, 12 pcs. The graph shows that when grinding chalk, the number of blades does not significantly affect the quality of grinding. When grinding sylvinite and in particular gypsum stone with an increase in the number of blades to 8, the grinding fineness improves, i.e., the median particle size decreases, however, with a further increase in the number of blades, the dispersed composition of the products remains almost constant. The analysis of known data on the theory of impact grinding is given, on the basis of which the principles of creating new energy-efficient machines for grinding materials, in particular to reduce energy costs, were formed.

Investigating the grinding performance of unidirectional and 2.5D-C/SiCs

The grinding performances of unidirectional and 2.5D-C/SiCs were discussed in this paper. In particular, the effects of the grinding depth and fibre architecture on the grinding force, surface quality and grinding debris and the material removal mechanisms of C/SiCs were the main focuses of this investigation; these issues have not received much attention in previous studies. Therefore, this study attempted to analyze the grinding mechanism of C/SiCs and improve the corresponding grinding quality on the basis of discussing the grinding properties of C/SiCs with different fibre architectures. The grinding depth had a substantial influence on the grinding properties of the C/SiCs. Compared to the unidirectional C/SiCs, the 2.5D-C/SiCs sustained a higher grinding force under the same grinding parameters. Fibre pullout and fibre outcrop were the fundamental damage modes of the unidirectional C/SiCs. In contrast, interfacial debonding, matrix cracking, fibre pullout and fibre outcrop were the primary defect forms of the 2.5D-C/SiCs. The subsurface damage in the 2.5D-C/SiCs was shallower and wider than that in the unidirectional C/SiCs. In addition, there was a substantial difference between the debris from the unidirectional and 2.5D-C/SiCs. The grinding force, surface quality and grinding debris of C/SiCs with different fibre architectures can be predicted with the principles outlined in this study. Hence, this research can provide a reference for increasing the grinding performance of C/SiCs with different fibre architectures.

The Nutritional Components of Rice are Closely Related to Grain Quality Traits in Rice

Starch, protein and lipid are the most important nutrients in rice, and their composition and content in rice grains play a decisive role in the grain quality. Rice quality (including appearance quality, cooking quality, nutrition quality, grinding and processing quality, etc.) is not only affected by the composition of the nutrients in grain of rice, but also by the physical and chemical characteristics and their content in grains, but also vulnerable to external environmental conditions. To clarify the relationship between the main nutrients in rice and their grain quality traits is of great theoretical significance and potential application value for the continuous improvement of rice quality in the future. Therefore, this paper reviewed the effects of starch, protein, lipid and mineral elements in grain of rice and also on quality of trait in rice. It is also discussed the relationship between these nutrients and rice grain quality traits. All of those will provide important information for the quality of grain improvement and breeding of new varieties with high quality in rice.

Multi-information fusion-based belt condition monitoring in grinding process using the improved-Mahalanobis distance and convolutional neural networks

Due to the advantages of flexibility, high efficiency, and low processing heat, belt grinding has been widely applied in manufacturing industries. As belt wear will cause deterioration of the removal capacity, increasing the surface irregularity and adversely affecting the grinding quality, interests in belt condition monitoring have signficantly augmented in recent years, which not only secures the surface quality, but also helps to optimize the utilization of the belt’s life cycle. A multi-information fusion-based belt condition monitoring method in grinding process using the improved-Mahalanobis distance and Convolutional Neural Networks (CNN) is proposed in this paper. Firstly, a time-domain mapping relationship between belt wear and material removal rate is put forward and a factor k t is derived to characterize the wear status. Furtherly, the evolution of abrasive grains degradation as well as the wear effect on grinding quality is analyzed. Secondly, a parallel multi-sensor integration grinding system including force, vibration, sound and acoustic emission sensors is established, based on which the single-factor and multi-factor sensitivity experiments are conducted to determine the optimal combination of characteristic signals. Finally, a multi-layer model including the grinding conditions classification and belt stages identification is established adopting the methods of improved-Mahalanobis distance and CNN. On one hand the model is not limited to a fixed condition and has a wider application scope, on the other hand avoids the impact of human experience on the features extraction and improves the model accuracy from the theoretical perspective. The experimental results show that the identification accuracy of the belt wear stage adopting the method in this paper is no less than 94 % for the 16 sampling conditions and more than 86 % for other grinding conditions. Furtherly, the contrast experiments indicate that the method in this paper is of a higher accuracy than the single-layer CNN model, which proves the effectiveness of the proposed method.

Comparative multiscale investigations of material removal behaviors of SiCp/5083Al, SiC ceramic and 5083Al alloy by single scratch tests

To gain a deep insight into the material removal mechanism of high volume fraction SiCp/Al during a grinding process, comparative multiscale investigations of material removal behaviors of 50 vol% SiCp/5083Al, bulk SiC and bulk 5083Al are presented by single scratch tests. Scratch mechanical properties including scratch force, friction coefficient and AE signal, as well as cross-sectional profile including residual scratch depth and material removal ratio are introduced to measure material removal behaviors at macroscale and mesoscope. Moreover, surface morphology of scratch grooves with help of SEM micrographs and explanatory model of material removal mechanisms are used to understand material removal evolution at microscale. It has demonstrated that at macroscale and mesoscope material removal behaviors of SiCp/5083Al are similar to that for 5083Al, but different from that for SiC, at microscale essentially different from that for 5083Al and SiC. Normal force (scratch depth) has significant influence on material removal behaviors, a sufficiently low scratch depth could achieve ductile removal of particles SiC resulting in a comparatively good surface for SiCp/5083Al, otherwise, the reverse. The work findings provide a critical insight of the material removal mechanism for SiCp/Al by considering coupling effects of particles SiC and matrix Al, and critical information for improving grinding quality.