Simulation and Optimization of the Nozzle Section Geometry for a Suspension Abrasive Water Jet

In order to improve the life cycle and cutting ability of a suspension abrasive water jet nozzle at the same time, hydrodynamics technology, an enumeration method and multiparameter orthogonal optimization are used to optimize the nozzle section geometry, taking the inlet diameter coefficient of the nozzle, the axial length coefficient of the contraction section and the contraction section curve as optimization variables, and selecting the peak velocity and the unit flow erosion rate as the indicators, it is concluded that the optimal contraction section curve is a Widosinski curve, the optimal inlet diameter coefficient of the nozzle is 0.333 and the optimal axial length coefficient of the contraction section is 2.857. Compared with the commercial product single cone nozzle, the performance of the optimal section nozzle improves by 5.64% and the life cycle increases by 43.2%. On this basis, the effects of operating parameters, including inlet pressure, abrasive particle flow rate and abrasive particle size, are further studied. It is determined that the optimal section nozzle has the best performance under the above operating parameters. It is demonstrated that by optimizing the nozzle section geometry, the cutting capacity and life cycle of the nozzle are improved, the performance of the nozzle can be significantly improved and the optimization of the performance of the nozzle is realized.

METHODOLOGICAL APPROACHES TO ACCELERATED TESTS OF CRUSHING KNIVES OF GRINDING CATS. COMPARATIVE TESTS OF LOSS OF CUTTING CAPACITY

The purpose of the research is to analyze the design features and parameters of grinding knives to compare the intensity of loss of cutting ability of each of the models of knives depending on the load cycles. Methods and materials. Conduct an analytical inspection and instrumental studies of the blades of grinding rollers type KR with different design features. Carry out bench accelerated tests based on the cyclic impact load of the knife fragment due to falling on the simulator of wear cycles and check the residual cutting capacity on the cutting simulator. Justify the coefficient of acceleration of tests as a derivative of hardness and density of the simulator, as well as the ratio of the energy of the fall of the knife fragment on the stand and its rotational motion in the field. Statistical analysis of experimental data was performed by analysis of variance and interpreted by standard computer programs Excel in the form of graphs. Results. Analyzing the proposed method for determining the intensity of loss of cutting ability of the knife when it falls on the simulator of plant debris allowed to rank different models and establish their relative resource. Unhardened models of both 45 and 30MnB5 Steel provide low life and their residual cutting ability is only 15-25% compared to hardened models. Analyzing the research results, the hardened model of a knife made of 45 Steel withstands 4 times more load cycles compared to unhardened models, but is inferior to the hardened model of Steel 30MnB5 (borista), which has the highest resource. Even after 150 load cycles (in terms of the work of a roller with a width of 12.5 m - operating time of more than 1000 ha), it retains more than 55% of the initial cutting ability, which is characterized by low intensity of its loss. Conclusions. According to the tests of the intensity of loss of cutting ability of knives, the most acceptable option for the equipment of roller-shredders is a hardened model made of 30MnB5 Steel (borista), which has the highest resource.

Developing Performance Assessment Instruments For Local Organizations in Ecological Restoration As Part of The Cross-Cutting Capacity Development (CCCD-UNDP) Project In Indonesia

Using the CCCD project as the locus of study, this paper reconstructs the empowerment process to reveal and arrange the instruments used at each empowerment stage. The performance measurement instrument was used to measure whether the organization involved in the project was related to project activities directly or indirectly. These two activities helped us compile criteria for the various organizations involved and conceptually draw the pattern of organizational relationships. Findings showed three main processes: (1) the process of identifying and selecting organizations, (2) the process of mentoring and facilitation, and (3) the process of evaluation and follow-up plan. The organizations or groups were divided into primary, secondary, and tertiary groups. Primary groups were directly related and involved in the project. Secondary groups could be involved and did not depend on funding and assistants. Tertiary groups did not need to be involved unless they had such political consequences to influence other groups. The group itself took part in decision-making about management patterns. The pattern could not be separated from the dynamics of policies, markets, and local village and supra-village politics. Based on these findings, the CCCD project confirms that a group empowerment approach must focus on the substantive aspect of achieving project goals, while the procedural aspect merely supports the administrative arrangement so objectives can be achieved more efficiently.

Development and Performance Evaluation of a Solar Powered Lawn Mower

The continuous increase in the cost of fuel and the effect of emission of gases from burned fuel into the atmosphere when operating engine powered lawn mower has necessitated the use of the abundant solar energy from the sun as a power source of a lawn mower. A solar powered lawn mower was designed, fabricated and assembled on the basis of the general principle of mowing. The components of the lawn mower are; direct current (DC) motor, rechargeable battery, solar panel, galvanized steel blade of various thicknesses and shapes, and a speed controller. The required torque needed to drive the galvanized steel blade was achieved through the DC motor. The speed of the DC motor was controlled by the speed controller with the resistance in the circuit and allowed the motor to drive the blade at varied speeds. The battery recharged through the solar charging circuit, which comprises of a solar panel and charge controller. Performance evaluation was conducted on the developed mower with various thicknesses (1 mm, 1.5 mm and 2 mm) and shapes of the cutting blade (two, three and four blades). It was found that the cutting efficiency of the mower ranges from 70.50% - 84.10%, also the cutting capacity ranges from 0.05 ha h-1 - 0.27 ha h-1, the uncut area was also found to range from 15.90% - 29.50%.

Evaluation of the cutting ability of two reciprocating instruments (WaveOne Gold e W-file)

Instrumentation is a fundamental step in endodontic treatment to promote proper cleaning and shaping of the canal. The objective of this study was to compare the cutting capacity of two reciprocal nickel-titanium systems in simulated canal blocks. Sixty acrylic blocks were used, divided into two groups of reciprocal files (WaveOne Gold - WOG and W-File - WF), each with 30 blocks and divided into 3 groups (n=10) representing the first, second and third uses: WOG1, WOG2, WOG3, WF1, WF2, and WF3, respectively. Ink was injected into the simulated channels, which were covered with laminated paper to avoid affecting the instrumentation. For irrigation, 5mL of saline was used at each instrument change. At the end of instrumentation, the blocks were photographed and analyzed in a computer program to compare the results before and after instrumentation. In the statistical analysis, the tests S Shapiro-Wilk, T for independent samples and Mann Whitney were performed. Under the experimental conditions in which this study was conducted, it is concluded that there were no significant differences in apical transport after the third application. However, the instruments of the W-File group had more conservative preparations with a better centralization capacity compared to the instruments of the WaveOne Gold group, which caused preparations with a larger diameter.

The enhancement of cutting capacity of a grinding wheel when processing ductile steel blank parts by ultrasonic activation

The study aimed to identify the relations between the sticking intensity and ultrasonic vibrations (UV) used for processing and evaluate the wheels’ performance when grinding ductile materials blank parts. The authors carried out the numerical simulation of local temperatures and the 3H3M3F steel workpiece temperature when grinding by ultrasonic activation. The study determined that the application of ultrasonic vibrations with the amplitude of 3 µm causes the decrease in local temperatures by 13…40 %, and in blank part temperature – up to 20 %. The calculation identified that the activation of ultrasonic vibrations with the amplitude of 3 µm causes the decrease in the glazing coefficient by 33 % for cutting grain and by 7 % for deforming grain. When increasing the longitudinal feed rate or the grinding depth, the glazing coefficient increases to a lesser degree when using the ultrasonic vibration than in the case without ultrasonic activation. The authors carried out the numerical simulation of local temperatures when scratching the 3H3M3F steel specimens by single abrasive grains with ultrasonic activation. The sticking deformation and the stresses resulted from this deformation and affecting the junction points of sticking with grains with and without ultrasonic vibrations application are calculated. The experimental research included the micro-cutting of specimens with single abrasive grains. The experiments identified that the abrasive grains wear out and glaze to a lesser degree when micro-cutting a workpiece with ultrasonic vibrations activation. The lowering of the intensity of sticking of the workpiece material particles to the abrasive grains due to the adhesion causes the decrease in the glazing coefficient when using ultrasonic activation. The study considered the possibility to enhance the efficiency of flat grinding through the use of the energy of ultrasonic vibrations applied to a blank part in the direction with the grinding wheel axis. A workpiece fixed in the device between the vibration transducer and the support is one of the components of a vibration system. The authors performed the experiment when grinding 3H3M3F and 12H18N10T steel workpieces with the wheel face. When grinding with ultrasonic vibrations, the grinding coefficient increases up to 70 %, and the redress life increases twice or thrice.

PERFOMANCE OF GEAR HONES WITH VARIOUS BONDING AGENTS DEPENDING ON THEIR MATERIAL’S MECHANICAL PROPERTIES

Gear hones are used for finish machining of hardened gear teeth lateral faces applying the generating method. The effectiveness of using such tools depends mainly on their composite material’s mechanical properties: bending strength, shrinkage, hardness, and the elasticity modulus. In practice, gear hones feature low durability and often fail due to tooth strippage; besides, they gave insufficient cutting capacity and wear resistance. It is of interest to study operation capacity of the most advanced gear hones with relatively hard eposy-aceturic and elastic hydroxyurethane bonding agents that have improved mechanical properties of the material. It was demonstrated that operational durability of such gear hones increases at increased bending strength and hardness and decreased material shrinkage. Elastic gear hones with a hydroxyurethane bonding agent also depend on the elasticity modulus; a value of 500…1000 MPa should be considered optimal. High durability of such gear hones is ensured even at low values of bending strength due to deformability of the teeth material.

Evaluasi Pengangkatan Cutting pada Trayek 17 ½ inch dengan Metode CTR CCA dan CCI pada Sumur KS Lapangan BW

<p>Lumpur pemboran atau <em>drilling fluid </em>merupakan salah satu parameter yang dapat mempengaruhi kesuksesan dari kegiatan pemboran. Pengangkatan <em>cutting </em>oleh lumpur pemboran yang optimal akan menghasilkan pemboran yang efisien dan terhindar dari permasalahan yang merugikan. Pada tugas akhir ini, dilakukan evaluasi kemampuan pengangkatan <em>cutting</em><em> </em>oleh lumpur pemboran yang digunakan di sumur KS lapangan BW pada pemboran trayek 17 ½ inch dengan menggunakan lumpur pemboran KCl Polimer serta melihat pengaruh perubahan sifat fisik dan <em>rate </em>pemompaan terhadap pengangkatan <em>cutting.</em><em></em></p><p> Metode yang digunakan dalam evaluasi ini yaitu <em>Cutting Transport Ratio</em> (CTR) <em>Cutting Capacity Annulus </em>(CCA) dan <em>Cutting Car</em><em>rying </em><em>Index </em>(CCI) dengan kriteria keberhasilannya dengan melihat nilai yang didapatkan<em> </em><em>Cutting Transport Ratio</em> (CTR)&gt; 90%, <em>Cutting Capacity Annulus </em>(CCA) &lt; 5% dan <em>Cutting Car</em><em>rying </em><em>Index </em>(CCI) &gt;1. Faktor yang mempengaruhi keberhasilan dari pengangkatan <em>cutting </em>ini adalah rheology lumpur yang digunakan, kecepatan fluida di annulus, konsentrasi <em>cutting </em>dan <em>rate </em>pemompaan yang diberikan.</p><p> Dari hasil perhitungan yang telah dilakukan pada trayek 17 ½ inch dengan data lapangan yang digunakan maka didapatkan nilai <em>Cutting Transport Ratio</em> secara keseluruhan (CTR) rata – rata di atas 90%, nilai <em>Cutting Capacity Annulus (CCA) </em> 1,8-3,5 %, dan nilai <em>Cutting Carrying Index (CCI) </em>1,3 – 3,6. Berdasarkan evaluasi yang telah dilakukan, nilai yang didapatkan memenuhi kriteria pengangkatan <em>cutting </em>yang baik, maka pengangkatan <em>cutting </em>pada sumur KS lapangan BW trayek 17 ½ inch optimal dan tidak mengindikasikan terjadi pengendapan <em>cutting</em>. Selain itu, didapatkan bahwa sifat fisik dari lumpur yang digunakan seperti <em>Yield Point </em>mempengaruhi keberhasilan pengangkatan <em>cutting </em>dimana nilai <em>yield point </em>pada lumpur dapat mengangkat <em>cutting</em>, <em>flowrate </em>yang diberikan juga berpengaruh terhadap kemampuan pengangkatan <em>cutting </em>dimana nilai <em>flowrate </em>yang rendah dapat membuat <em>cutting </em>tidak terangkat dan terjadi pengendapan <em>cutting </em>didasar lubang.</p>