Drum Speed Research Articles

Surface Machining of Corundum-Ceramic Components by Free Abrasive

The surface machining of corundum-ceramic components by free abrasive is discussed. The influence of the following factors on the final surface roughness is determined: the type of machining (tumbling or vibrational tumbling), the shape of the abrasive bodies, the presence or absence of machining fluid, the machining time, and the drum speed in tumbling. On that basis, recommendations are presented.

Developing A Rheological Relation for Transient Dense Granular Flows Via Discrete Element Simulation in A Rotating Drum

ABSTRACTThis work examines the μ(I) relation that describes the effective friction coefficient μ of a dense granular flow as a function of flow inertial number I, at the center of a rotating drum from its flow onset to steady state using DEM. We want to see how the internal friction coefficient of an accelerating flow may be predicted so that the associated tangential stress can be estimated with the proper knowledge of the normal stress. Under the three investigated drum speeds (3, 4.5 and 6 rpm), the bulk normal stress, σn(y), is found to be a consistent linear depth profile throughout the flow development with a slope degraded from the hydrostatic value, Ph(y), due to lateral wall friction. With the discovery of a non-constant depth-decaying effective wall friction coefficient, we derive analytically a wall-degradation factor K(h) to give σn(y)= K(h)Ph(y). The depth profile of tangential stress, however, varies in time from a concave shape upon acceleration, τa(y), to a more linear trend at the steady state, τss(y). Hence, the μa-Ia profile (with μa=τ/σn) upon flow acceleration offsets from the steady μss(Iss) relation. A pseudo-steady acceleration modification number, ΔI, is proposed to shift the inertial number in the acceleration phase to I* = Ia+ΔI so that the μa-I* data converge to μss(Iss). This finding shall allow us to predict a transient tangential stress by τa(y) = μss(I*)K(y)Ph(y) using the well-accepted knowledge of steady flow rheology, hydrostatic pressure, and the currently developed wall-degradation factor.

Robustness Optimization of an Existing Tablet Coating Process Applying Retrospective Knowledge (rQbD) and Validation.

The objective of these studies is to verify and validate the improvement in the inter-tablet coating uniformity for an industrially commercialized coated tablet, without involving changes in the approved registration dossier. Using the CPP (critical process parameters) determined from previous retrospective statistical analysis, the recommended working ranges are identified. Retrospective analysis showed that the design of experiments (DoE) provided an improved process variable configuration. Therefore, it is decided to study two critical parameters: Product temperature and drum speed, with an additional 22 experimental design. The quality results of the samples analyzed show that the aesthetic defects of the batches made with the new working ranges have been reduced. These results have also been corroborated with the 42 industrial batches manufactured with the new ranges. With the optimized parameters, tablets have been coated and the suitability of the model determined. The results demonstrated the overall reliability and effectiveness of the proposed Quality by Design approach and provides a useful tool to help optimize the industrial coating process. This study confirms that it is possible to optimize and validate the manufacturing process of an existing commercial product by means of a DoE with retrospective data. Therefore, no variation in the dossier is required.

Polyacrylonitrile Nanofiber Optimization as Precursor of Carbon Nanofibers for Supercapacitors

Polyacrylonitrile (PAN) nanofibers are one of the primary precursors in the production of carbon nanofibers. The nanofiber morphology is significantly affected by the process parameters such as polymer concentration, distance, applied voltage and feed rate during the production of PAN nanofibers obtained by the solution-based electrospinning method, and these parameters should be optimized properly. In this study, firstly PAN nanofiber production parameters were optimized, and then homogeneous and thin PAN nanofibers produced in optimum conditions were used as the precursor in the production of carbon nanofibers. PAN nanofibers with a diameter of 233 nm were obtained at 7.5% PAN concentration in N,N-dimethylformamide (DMF), 28 kV applied voltage, 17.5 cm nozzle to collector distance, 2 ml/h feed rate and 500 rpm rotation speed of the aluminum drum. The carbon nanofiber diameters produced after the stabilization and carbonization processes were measured as 200 and 140 nm, respectively. The morphological, chemical and thermal properties of the produced nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), thermogravimetric analyzer (TGA). Carbon nanofibers, which are made from optimized electrospun PAN nanofibers, can be used to construct supercapacitors in future studies.

Risk Analysis of Out-drum Mixing Cement Solidification by HAZOP and Risk Matrix

Due to the particularity and complexity of cement solidification, radioactive waste may be released and diffused, causing serious radioactive hazards to equipment, operators and environment. In this study, hazard and operability analysis (HAZOP) and risk matrix were combined to identify and evaluate risks of out-drum mixing cement solidification. Firstly, based on concept and steps of HAZOP, the meaningful deviations of out-drum mixing equipment were described by appropriate guidewords and process parameters. Secondly, the causes and consequences of deviation, and the safety measures were investigated. Finally risk matrix was applied to classify risk level and assess risk of the identified deviation. Results indicated that low level of wet waste in storage and weighing tank, less flow of wet waste in feeding pipe of storage and weighing tank, mixer without mixing speed, high transport speed and additional location of drum are unacceptable risks. The relevant safety suggestions were given to reduce or eliminate potential hazards.

MANUFACTURE AND PERFORMANCE EVALUATION OF A LOCAL THRESHING AND CLEANING MACHINE SUITS MEDICINAL AND AROMATIC PLANTS

Experiments were carried out to manufacture and evaluate the performance of a threshing and cleaning machine suitable for medicinal and aromatic plants (Anise, Fennel and coriander crops). The performance of the manufactured machine was studied under the following parameters: four different drum speeds, four different concave clearances and four different feed rates. The performance of the manufactured machine was evaluated taking into consideration the following indicators: total seed losses, overall machine efficiency, machine productivity, required power, energy requirements and criterion cost. The experimental results reveal that total seed losses as well as criterion costs were minimum while overall machine efficiency was maximum under the following conditions: • Operate the manufactured machine at a drum speed of about 450 rpm for anise and fennel crops, and 400 rpm for coriander crop. • Operate the manufactured machine at a concave clearance of about 9 mm for anise and fennel crops, and 10 mm for coriander crop. • Adjust the feed rates at 1.25, 1.35 and 1.50 Mg/h for anise, fennel and coriander crops respectively.

Experimental investigations on thermal behavior during pick-rock interaction and optimization of operating parameters of surface miner

Operation of surface miner has significantly expanded in mines because of its mass production ability and eco-friendly way of rock excavation. Optimal utilization of operating parameters ensures better cutting efficiency and longer machine life. Elevated temperature of a pick developed during the rock cutting process affects its life. It especially influences the wear rate of the cutting pick. During the present study, operating parameters of a surface miner were examined using the Taguchi method. In the process, an appropriate parametric combination was developed facilitating the use of optimal cutting power, higher production and minimum pick consumption. The role of operating parameters, i.e., depth of cut (DOC), cutting speed (CS) and drum speed (DS) with temperature (T) was analyzed statistically. Empirical models were also developed for studying temperature variations in cutting picks using Taguchi method, multiple linear regression (MLR) and artificial neural network (ANN). Confirmation test revealed that optimized temperature was achieved at a significance level of 0.05 and the Taguchi method enabled better outcomes with minimum deviation and a high degree of optimization of operating parameters of surface miner.

Tuning energy harvesting devices with different layout angles to robust the mechanical-to-electrical energy conversion performance

This research presents an engineering approach to fabricate multilayered electrospun nanofiber mats with high conversion performance of mechanical to electrical energy as well as improved physical stability. Electrospun polyvinylidene fluoride nanofiber webs were prepared with predefined nanofiber alignments. Fiber alignments and layer-by-layer deposition angles are considered as a tool to adjust the piezoelectric responses of multi-layered fibrous mats. Samples with optimized drum speed and maximum aligned nanofibers were utilized to fabricate multi-layered mats in different layering angles from the fiber direction of base layer (0°, 30°, 60°, 90°, 120°, 150°, and 180[Formula: see text]). The effect of layering angle of multi-layered nanogenerators on their piezoelectric responses was investigated using an image analysis approach based on the fast Fourier transform. Multivariate analyses (ANOVA) performed to reveal the relationship between increasing drum speed and nanofibers alignment and the degree of crystallization as well as the formation of β-phase in the fiber crystalline structure. Results showed that increase in drum speeds had a relative improvement in the crystal structure and the formation of β-phase in the electrospun polyvinylidene fluoride nanofiber webs. Furthermore, electrical response of samples with well-aligned polyvinylidene fluoride nanofibers collected at 1800 r/min led to 94.49% improvement when they were exposed by a periodic mechanical impact compared to non-aligned polyvinylidene fluoride nanofiber webs. Piezoelectric response of multilayered samples with layering angles of 120[Formula: see text] showed 41% improvement in their electrical output compared to those with 0[Formula: see text]. These results teach us to establish engineering design rules for textile-based energy conversion devices with different piezoelectric coefficients.

A methodology for designing cutting drum of surface miner to achieve production of desired chip size

The size of coal chips, produced during coal cutting operations, is of prime importance from the viewpoint of feed size desired by power plants. Proper chip size in cutting can eliminate primary crushing and in-turn save energy. Achieving a designated size of chip is intimately linked with the drum design inter alia the wrap angle, line spacing of picks and pick size. Operating parameters namely cutting speed and drum speed also influence the output. Considering the increased need to produce a sized product for cost-effective mining, a design methodology was developed to achieve a required chip size for surface miners with a middle drum configuration. Various pick, drum and operational parameters were taken into account for the development of drum design, namely drum width, drum diameter, pick size, clearance angle, rake angle, cutting angle, lacing pattern, angle of wrap, depth of cut, indented depth of cut and pick spacing. Limiting factors for drum design such as the number of picks, pick temperature, strength of pick, depth of cut and dust generation were discussed. A new drum configuration for achieving 100 mm chip size was validated which showed close agreement with the output produced using 2200SM model surface miner.

Development Seed Cotton Feeder-Cleaner Suit for Small Gins تطویر مُغذی / مُنظف للقطن الزهر یناسب الحلاجات الصغیرة

This research aims to develop and evaluate the performance and efficiency of the seed cotton feeder-cleaner suit for small gins to reduce maintenance & downtime of the gin. The studied factors were four different feed rates ranged from 0.5, 0.75, 1.0 and 1.25 kg/min; Four different speeds of saw cleaning drum ranged from 3.32, 4.27, 5.22 and 6.17.m/s; Four different speeds of brush cleaning drum ranged from 5.32, 6.83, 8.39 and 9.87.m/s using seed cotton varieties of Giza 86 and Giza 94. The obtained results concluded that: The maximum productivity of the developed feeder /cleaner was 1.075 kg/h for cleaning Giza 86 variety compared to 1.115 kg/h for Giza 94 variety at the saw drum speed of 3.32 m/s, brush drum speed of 5.32 m/s and feed rate of 1.25 kg/min . The maximum values of cleaning efficiency of 89.60 and 94.30 % were obtained at the feed rate of 0.5 kg/min; saw drum speed of 6.17 m/s and brush speed of 9.87 m/s during cleaning seed cotton Giza 86 and Giza 94, respectively. The developed seed cotton feeder/cleaner produced better values of 2.5 and 50% span fiber length, uniformity ratio of length, reflectance of color and cotton fiber strength with seed cotton variety of Giza 94 compared to Giza 86.

Research of loading of loose components the lock feeder at secondary temporary dispensing for non-mixing automatic machines

Results of pilot study and their statistical processing on the basis of multiple-factor experiment are provided. Operation of the stand of the lock feeder applied to dispensing of bulks from metal powders by way of time separation from the flow of micro doses of components given by the feeder was investigated. These feeders are used as the automation equipment in conveyor, rotor and birotary non-mixing installations. Regression models for determination of the actual productivity of lock feeder are received. It is established that dependences of productivity of lock feeders on the circumferential speed of rotation of the dosing drum and its operating volume are nonlinear. At the constant volume of grooves, the same productivity can be received at different values, the circumferential speed of drum that is at implementation of the different kinematic modes. At design and the choice of processing equipment it is necessary to use the received dependences that will allow on the set actual capacity of the feeder to choose geometry and kinematic parameters of process of dispensing.

PENGEMBANGAN DAN EVALUASI MESIN PENYANGRAI KOPI TIPE DRUM UNTUK USAHA SKALA KECIL

The design, manufacture and evaluation of a drum coffee roasting machine had been carried out. The aimed of the study was to develop a small-scale drum roaster to meet the demand of the small enterprises at design and function. The development stage consisted of sizing of the main components, creating technical drawings, determination of component materials, manufacture and performance test. The dimension of the roaster drum was 168.28 mm in diameter and 250 mm in length; the capacity of the roaster was 750 gram/ batch. Results of the test determined that the coffee roasting machine had worked well as expected. The preheating time was 15-22 minutes at a drum speed of 67.5 rpm. The initial loading temperature was 180°C. The test using arabica coffee bean reveals that the average crack time was 8.78 minutes, development time was 2.35 minutes, decreasing mass and increasing volume ranged from 19.80 – 20.30 % and 49.97 – 54.85 % respectively. The average crack time of Robusta coffee bean was 10 minutes; development time was 3 minutes, decreasing mass and increasing volume ranged from 10.87 – 14.90 % and 44.93 – 56.20 %, respectively. The required time to roast Arabica green coffee bean to the light-medium and medium-dark level was 11.3 and 12.38 minutes respectively, besides for Robusta green coffee beans was 13.00 and 14.00 minutes respectively.

The influence of mechanical action on felting shrinkage of wool fabric in the tumble dryer

Felting shrinkage of untreated wool fabric occurs easily during tumble drying. Mechanical action applied on fabrics plays a significant part in felting shrinkage of wool fabric. In general, the more severe the mechanical action of a washing or drying machine, the more rapid the felting shrinkage. However, both the degree and type of mechanical action applied on the fabric can influence felting shrinkage of untreated wool fabric. In the current study, fabric movement and felting shrinkage of untreated wool fabric at different rotation speeds of the drum in a tumble dryer without heating were studied. Based on the different fabric movements at different rotation speeds of the tumble drum, the extents of impact and rubbing forces at different rotation speeds were assessed by ranking. The total mechanical action applied on the fabric was expressed as the percentage of thread removal of “thread removal fabric” during the drying process. The results showed that lowest mechanical force on fabrics could be achieved when higher rotation speeds of the drum were used to dry wool fabrics in the tumble dryer, and could prevent wool felting shrinkage. It was also found that falling of the fabric followed by impact on the drum wall caused less felting shrinkage than sliding with rubbing between fabrics. Therefore, maintaining the falling movement could be a potential method to dry wool fabric in drying machines without causing severe felting shrinkage.

Experiments and optimization for the WEDM process: A trade-off analysis between surface quality and production rate

This work addressed a parameter optimization to simultaneously decrease the root mean square roughness (Rq) as well as the thickness of the white layer (TW) and improve the material removal rate (MRR) for the wire electro-discharge machining (WEDM) of a stainless steel 304 (SS304). The factors considered are the discharge current (C), the gap voltage (VO), the pulse on time (POT), and the wire drum speed (SP). The interpolative radius basic function (RBF) is applied to show the correlation between the varied factors and WEDM performances measured. The optimal selection is chosen using the multi-objective particle swarm optimization (MOPSO). Moreover, a traditional one using the response surface method (RSM) and desirability approach (DA) is adopted to compare the working efficiency of two optimization techniques. The results showed that the optimal findings of the C, POT, VO, and SP are 5.0 A, 1.0 µs, 61.0 V, and 8.0 m/min, respectively. The values of the Rq and TW are decreased by approximately 33.33% and 23.53%, respectively, while the MRR enhances 47.42% at the optimal selection, as compared to the common values used. The BRF-MOPSO can provide better performance than the RSM-DA.

Heat transfer enhancement in rotary drum dryer by incorporating jet impingement to accelerate drying rate

The purpose of this study was to investigate experimentally the effects of impinging jets installed in a conventional rotary dryer for heat transfer enhancement. The metal drum had as insert a jet tunnel at the centerline, and the jets were arranged in an in-line configuration on the jet tunnel. A jet-to-jet (S) and a jet-to-target (H) distances were fixed at S/d = 6 and H/d = 4, respectively. Jet velocity (Vj ) was set at Vj = 5, 10 and 15 m/s, while jet temperature (Tj ) was 70, 80 or 90 °C. Drum rotation speed (N) was also investigated at N = 0.5, 1, and 3 rpm. The conventional rotary dryer was examined at the same mass flow rate of hot air to compare with the case having impinging jets. All experiments were conducted by batch drying 5 kg of fresh chilies for 8 hours. Results showed that installing jets gave more effective heat transfer, which accelerated water removal over that with the conventional rotary dryer, and the moisture contents were greatly reduced. On using impinging jets, the jet temperature had more influence on heat transfer enhancement than the jet velocity. In comparison, the effect of drum speed was small.

Influence of load mass and drum speed on fabric motion and performance of a heat pump tumble dryer

The present study investigates fabric motion in the drum and its effect on performance parameters of a domestic heat pump tumble dryer in several operating points, defined by different load masses and drum speeds. Fabric motion in the drum was recorded by using a high-speed camera and evaluated statistically in order to determine the relation between the fabric distribution and the dryer performance parameters. Multiple regression analysis was performed to develop models for condensate mass flow rate as a function of drum speed, load mass, and drying stage. The results enable optimization of dryer operating parameters with respect to energy efficiency, drying time per kilogram of fabric, and condensate mass flow rate.

Multi-Objective Optimization of Process Parameters of Longitudinal Axial Threshing Cylinder for Frozen Corn Using RSM and NSGA-II

Corn was frozen at harvest time in high-latitude areas, when corn kernel is wetter and more easily broken. When frozen corn was threshed and separated by the longitudinal axial threshing cylinder of a combine harvester, it caused a significantly high kernel damage rate and loss rate. The process parameters of threshing cylinder were optimized using RSM (response surface method) and NSGA-II (Non-Dominated Sorted Genetic Algorithm-II). The drum speed (Ds), feed rate (Fr) and concave clearance (Cc) were determined as the optimized process parameters. The loss rate (Lr) and damage rate (Dr) were indicators of operational performance. The RSM was used to establish a mathematical model between process parameters and indicators. With an elite strategy, NSGA-II was used for multi-objective optimization to obtain the optimal operational performance of the threshing cylinder. Overall, when the drum speed was selected as 384.1 rpm, the feed rate as 8.6 kg/s and the concave clearance as 40.5 mm, according to the requirement of corn harvest, the best operational performance of the longitudinal axial threshing cylinder on frozen corn was obtained. The Lr was 1.98% and the Dr was 3.49%. This result indicated that the applicability of the optimal process parameters and the optimization method of combining NSGA-II and RSM was effective for determining the optimal process parameters. This will provide an optimization method for synchronously reducing the loss rate and damage rate of grain harvesters.

Manipulating Chain Type and Flail Drum Speed for Better Fibre Recovery in Chain-Flail Delimber-Debarker-Chipper Operations

Manipulating Chain Type and Flail Drum Speed for Better Fibre Recovery in Chain-Flail Delimber-Debarker-Chipper Operations

Simulation of winding web on surface winder (Stress distribution, tension and slippage of wound roll)

Surface winding processes are simulated up to 49-70 laps by means of a FEM commercial software. The simulation model is composed of a flexible web with linear-isotropic nature, rigid core and rigid drum (or rigid two drums and a rider roll). Stress distributions of wound rolls, tension (tangential stress) change during winding and layer slippage are investigated. The main results are as follows. In case of single-drum surface winding, the roll stresses become larger as a friction coefficient between web layers, nip load, drum diameter or a line tension increases, or Young’s modulus decreases. Poisson’s ratio has little effect. The roll stresses depend on not only WIT (increased tension of the outermost layer due to the nip load), but a decreasing rate of tension at a web point during winding, and they have a cross relation with a value obtained by integrating a web tension varying curve from the start point where the web enters the roll to the end of winding. In case of two-drum surface winding with differential drum speeds, the web tension varies complicatedly at three nip zones and is larger between the rider roll and the second drum. The tension of the outermost layer decreases with increase in the roll diameter. The slippage occurs as the outer web layer pulls the inner in the roll rotational direction and is larger at the outer web layers. When speeds of the two drums are equal, the first drum drives the roll and the tension is larger between the second and the first drum. The slippage is the same as the differential drum speed case in the range of 2/3 of the roll thickness, but in the rest range, the slippage occurs in the opposite direction.

Manipulating Chain Type and Flail Drum Speed for Better Fibre Recovery in Chain-Flail Delimber-Debarker-Chipper Operations

A chain-flail delimber-debarker-chipper (CFDDC) was adapted for treating smaller trees than normal by replacing the standard flails with lighter ones, and by reducing flail drum rotation speed. The machine produced 16 full containers (24 t each) for the standard configuration and 24 full containers for the innovative one. For each container the researchers measured: original tree mass, chip mass, time consumption and fuel use. Results indicated that the innovative setting accrued a 12% improvement on fiber recovery compared with the standard setting (control). At the same time, productivity increased by 20% and fuel consumption was reduced by 30%. Product quality was largely unaffected, with bark content remaining below the 1% threshold specification. If at all, product quality was improved through the reduction of fine particles, possibly derived from less diffused fraying. These results have triggered the real scale adoption of the new setting by contractors who participated in the study. The success of the innovative treatment is likely explained by its better alignment with the weaker structure of small trees from low-yielding stands.