THE USE OF THE CLUSTER ANALYSIS METHOD TO DESCRIBE THE MIXING PROCESS OF THE MULTI-ELEMENT GRANULAR MIXTURE

The paper presents a new idea of and approach to using the cluster analysis to describe a complex problem concerning the mixing process of granular mixture in industrial conditions. The phenomenon of mixing is still not well understood particularly in the process of mixing multi-component nonhomogeneous mixtures. Most real granular mixtures which are present in the industrial practice, such as feed mixing, are multi-component heterogeneous systems. The results and conclusions obtained from the modelling process in laboratory conditions cannot be directly translated into industrial conditions due to the change in the scale of the device. Real situations are usually more complex and bring with them new problems to be solved and the need to develop other methods of describing the process of mixing. The article describes the process of mixing compound feeds consisting of various cereal grains of different properties, namely of different size of grains and bulk density, carried out in a two-tone industrial mixer

The Effect of Mixing Time on the Homogeneity of Multi-Component Granular Systems

Mixing of granular materials is unquestionably important. Mixing solids is common in industrial applications and frequently represents a critical stage of the processes. The effect of mixing determines the quality of products. The objective of this study was to determine the effect of mixing time on the quality of multi-component granular mixtures. Experimental studies were conducted at the mixing process line in an industrial feed mill. The applied granular systems are feed mixtures with different weight proportions of individual components, varying in their diameter dimensions and bulk densities. Estimation of the degree of homogeneity was performed based on the scale of the mixture quality proposed by Boss according to the relation suggested by Rose. The mixing degree M as a function of time for granular mixtures was extended by presenting it according to different levels of collecting samples. Studies were performed for four mixtures varying according to their granular mixture formulas for five different mixing times. The quality of granular mixtures consisting of eight components was defined as \u27very good\u27 for mixing times of 30, 40, 50, and 60 minutes and as \u27good\u27 for the 20-minute mixing time. For the 12-component mixture BF, the quality was considered as \u27excellent\u27 for the 40-minute mixing time, and as \u27very good\u27 for mixing times of 20, 30, 50, and 60 minutes. For the 12-component mixture WM and the 14-component mixture WW, the quality was considered as \u27excellent\u27 for all mixing times (M>0.96)

Homogeneity assessment of multi-element heterogeneous granular mixtures by using Multivariate Analysis of Variance

Rad se bavi analizom homogenosti heterogenih zrnatih smjesa s više sastojaka. U tu se svrhu primijenila multivarijantna analiza variance. Istraživanje je provedeno u pogonu za proizvodnju krme koristeći vertikalni mikser s pužnom miješalicom u koji staje masa materijala od 2,1 ÷ 2,2 tone. Analizirale su se krmne smjese sastavljene od desetak vrsta raznog sjemena s različitim dimenzijama zrna, različitih gustoća i oblika. Homogenost smjese određena je uzimanjem uzoraka tijekom punjenja vreća. Pokazalo se – na osnovu statističkih ispitivanja – da je koncentracija pojedinačnih multi-elemenata, heterogenih zrnatih mješavina ista u čitavoj količini krmne smjese. Smjese su homogene (jednolike), što je od bitne važnosti, kada se procjenjuje kvaliteta dobivenih smjesa. U tom stadiju proizvodnje nije bilo nikakvog razdvajanja smjese i sastojci su bili dobro izmiješani. Nadalje, verificirana je hipoteza da skraćivanje vremena miješanja od standardnih 30 na 20 minuta nema utjecaja na homogenost smjese.The article presents a homogeneity analysis of multi–element heterogeneous granular mixtures. For this purpose, multivariate analysis of variance was used. The research study was conducted in an industrial feed production plant using a vertical mixer equipped with a worm agitator and with the mass of materials of 2,1 ÷ 2,2 tones being put into it. Fodders comprising a dozen of whole seed components varying in grain diameter dimensions, densities and shapes were the subject of the research material. Homogeneity of fodder was determined based on samples taken during the bagging process. It was demonstrated – on the basis of statistical tests – that concentration of individual multi-elements, the heterogeneous granular mixtures is the same in the whole volume of the fodder. The mixtures are homogeneous (uniform), which is of vital significance, when considering the quality of mixtures being obtained. At this stage of production, there was no dissection of the mixture, and components were well–mixed. Furthermore, the hypothesis stating that shortening of the mixing time from standard mixing time of 30 to 20 minutes would not adversely affect the homogeneity of the mixture was verified

The Model of Changes in the Psychomotor Performance of the Production Workers

The results of the study indicated a relationship between the worker’s psychomotor performance at a certain time of the work shift and the changes in the level of their fatigue. The performance is reflected in the production results, such as the decrease in the productivity and an increase in the number of defects. The results of the study made it possible to define a model (algorithm) of changes in the worker’s psychomotor performance. The developed model identifies the direction of the organisational changes in a production plant environment operating in the rotational shift pattern. The organisational changes can relieve staff in the night and minimise the risk of the declining production efficiency during work at night

Strengthening Effect after Disintegration of Stainless Steel Using Pulsating Water Jet

The article deals with the measurement of micro-hardness of the track by the action of ultrasonic excitation of pulsating water jet. The cumulative effect of liquid matter in the form of droplets concentrated in waveform measurements was provided in horizontal and vertical direction to material core (AISI 304). The material was subjected to pressures of p = 40, 50 and 60 MPa with the actuator working at a frequency of 20,14 kHz and traverse speed v = 1,1 mm/s, v = 0,80 mm/s and v = 0,30 mm/s respectively. The micro hardness measurement was carried out after machining it by pulsating water jet. The values were recorded in the zone located transversally under the trace to the depth of 1,5 mm with 0,1 mm distance between successive points. It was found that the deformation of material was ascertained from the boundary to the outer environment created by pulsating water jet to the inner core of the material. The results indicate that the pressure was the most influential parameter, which was responsible for the deformation strengthening of the material

Measurement of thermal emission during cutting of materials using abrasive water jet

This article deals with measurement of the thermal gradient on material during abrasive water jet cutting. The temperature was measured by thermocamera before the technological process started, during the abrasive water jet cutting process technology, and just after the cutting process. We performed measurements on several types of materials. We calculated the approximate amount of energy during the abrasive water jet cutting process technology that changes into thermoenergy, which is the current water pressure drained in a catcher tank

Developing of wear model of construction materials in abrasive soil pulp employing discriminant analysis

U radu se opisuje metoda odabira kemijskog sastava i strukture površinskog sloja konstrukcijskih materijala koji odgovaraju svojstvima abrazivne zemljane mase koja se obrađuje. Eksperiment je proveden u laboratoriju metodom "rotirajuće mase". Matematičkim modelom razvijenim za eksperiment omogućena je simulacija promjena u trošenju konstrukcijskih materijala korištenih u zemlji ovisno o promjeni kemijskog sastava i strukture konstrukcijskog materijala i vlažnosti zemlje. Rezultati pokazuju da intenzitet trošenja u šljunčanom tlu može biti prihvatljiv za materijale koji sadrže manje od 20 % C+Cr (upotrebljene u tlu s vlažnošću višom od 12 %) kao i u tribološki nepovoljnim uvjetima (vlažnost tla ispod 6 %), ako je sadržaj C+Cr u konstrukcijskom materijalu viši od 25 %.This paper presents a method of selecting the chemical composition and structure of the surface layer of construction materials to suit the property of the abrasive soil pulp being processed. The experiment was conducted in a laboratory, by the "rotating mass" method. The mathematical model developed for the experiment enables simulation of the wear changes of the construction materials used in soil, depending on changing of chemical composition and structure of the construction material and soil humidity. The results produced in the experiment have shown that the wear intensity in gravel soil may be acceptable for both materials containing less than 20 % C+Cr (used in soil with humidity of more than 12 %) and in tribological unfavourable conditions (soil humidity below 6 %), if the C+Cr content in the construction material exceeds 25 %