Large Mill Research Articles

Chatter suppression in large overhang face milling using a toolholder with high dynamic performance

There is increasing demand for the large overhang toolholder to machine certain workpieces with complex cavities during milling operation, but this kind of toolholder may bring an undesired source of chatter. This paper develops a novel toolholder with high dynamic performance to suppress chatter. Firstly, the dynamics of the milling cutter are investigated according to the cantilever beam theory. The obtained analysis result shows that the increasing stiffness and damping ratio can effectively reduce the vibration amplitude; based on this finding, a novel toolholder is developed through embedding the strips and damping core into the toolholder body. Subsequently, the dynamic characteristic of the novel toolholder is studied qualitatively by the complex number method, and its geometrical parameters are optimized by the finite element method. Finally, modal tests and milling experiments are conducted to verify the chatter stability improvement of the novel toolholder. The experimental results demonstrate that the chatter stability of the developed toolholder is enhanced significantly.

Analysis of Heat Processes in the Energy Supply System of a Gas-Using Feed Boiler

The energy audit conducted on the use of fuel and energy resources in agriculture in the Tambov region showed that energy costs in the cost of production of agricultural products, depending on the type of products produced (milk, meat, vegetables grown in greenhouses, etc.) and their production technology, reach 15-50 percent. On large livestock farms, forage shops and inter-district feed mills are being built for the feed production. Gas-fired cooking cauldrons of low capacity (of 40-250 kilogram per hour) are mainly used for small and private farms. Analysis of low-power cooking boilers has shown that it is possible to improve their energy supply system by applying a method of regulating gas in proportion to the consumed heat flow. Energy savings can reach 40-50 percent. (Research purpose) The research purpose is in designing an equation system for mathematical description of the heat and energy balance of a gas-using cauldron with self-regulation of power to identify energy-efficient modes of its operation. (Materials and methods) Methods of system analysis and synthesis has been used. of knowledge existing in the field of ongoing research on the development of a gas-using digester with self-regulation of power. The methods are based on the theory of heat and mass transfer. (Results and discussion) The article presents a theoretical analysis of heat and power processes occurring in the power supply system of a cauldron with self-regulating power. The authors have designed a heat balance equation describing the processes of heat and mass transfer in a cauldron to identify effective modes of operation of such a power supply system. The article presents derived formulas for determining the useful heat for heating the product in the cauldron, heat loss for heating metal structures, from the enclosing structures to the environment, with outgoing exhaust gases, and from chemical underburning. (Conclusions) The article presents a system of equations that allows to mathematically describe the processes of heat and mass transfer in a gas-using cauldron with self-regulation of power to identify the most energy-efficient modes of its operation. It was found that by improving the power supply system of cauldron by applying a method of regulating gas in proportion to the consumed heat flow, it is possible to achieve energy savings of up to 40-50 percent.

Large Cutting Depth and Layered Milling of Titanium Alloy Thin-Walled Parts

Deformation of thin-walled titanium alloys can occur during the milling process due to the cutting force and chatter vibration, which can influence the precision of the finished parts. In this research, a new milling method without auxiliary support for machining of thin-walled parts was proposed. A large cutting depth and layered milling technology were used during rough machining, with a different machining allowance for each subsequent remaining layer. In the finishing stage, the surface of the previous layer needed to be dressed before processing the next layer. A TiAlSiN-coated, cemented carbide milling cutter was used to machine titanium alloy thin-walled parts, which are characterized by continuous multilayers of unequal thickness. The processing path was simulated using HyperMILL software, and the machining accuracy was detected by the 3D optical scanner. The measurement results indicated that the surface contour accuracy of the parts was ±0.21 mm, within a range of ±0.30 mm. The machining efficiency was increased by 40%, while guaranteeing machining accuracy.

A health management system for large vertical mill

The large vertical mill has complicated structure and tens of thousands of parts, which is a critical grinding equipment for slag and cinder. As large vertical mill always works in severe conditions, the on-line monitoring, timely fault diagnosis, and trend prediction are very important guarantees for the safe service and saving maintaining costs. To address this issue, the health management system for large vertical mill is developed. More specifically, in order to manage reservoirs of state-related running data, the intrinsic physic data, and diagnosis knowledge base, an entity-relationship-model-based database is first constructed. Based on the fault diagnosis reasoning of experts, the fault tree is developed and the fault diagnosis rules are derived. Especially, a hybrid condition prognosis method based on backtracking search optimization algorithm and neural network is developed, and in comparison with traditional back propagation neural network and ant colony neural network, the developed backtracking search optimization algorithm and neural network gets superior hybrid prediction performance in prediction accuracy and training efficiency. Finally, the health management system, including the functions of condition monitoring, fault diagnosis, and trend prediction for large vertical mill is implemented using Microsoft Visual Studio C # and Microsoft SQL Server.

Investigation on surface quality and burr generation of high aspect ratio (HAR) micro-milled grooves

With a widespread application of micro machinery, high-quality surface demand of high aspect ratio (HAR) micro-grooves is increasing gradually. However, problems of imperfect inside-wall surface quality and massive burrs are particularly prominent in the generation process of HAR micro-grooves with the large length-diameter ratio micro-end mills. In this paper, a preliminary research on surface quality and burr generation mechanism is conducted to achieve the desired HAR micro-grooves. The top-burr generation rule of HAR grooves is discussed by establishing a FE model. The effects of cutting fluids and the wear of micro-milling tools on surface quality and micro-burr generation were analyzed. Results have shown that the burr generation and surface quality were strongly dependent on the tool wear and the groove depth. As the cutting cycles increased, the top-burr dimensions kept level with the variation in the edge-radius. Furthermore, the water-free alcohol based lubrication was demonstrated to play a positive role in improving surface quality and reducing burr generation. Finally, a desired HAR micro-groove with a nanometer level areal surface roughness (Sa = 77.4 nm) was obtained under the optimized conditions.

Johnson Lumber: Bet on the Upside or Avoid the Downside?

James Baker is general manager of a large lumber mill in rural Virginia, Johnson Lumber. While on a business trip with the owner (the founder's grandson) and the owner's son, he receives the news that the company's planing mill has caught fire and is burning down. Baker, the owner, and the owner's son must decide what to do in the wake of losing the planing mill. Choices include rebuilding, seeking partnerships with other mills to use their facilities to fulfill existing business, or possibly closing shop and simply taking current profits. If they rebuild, Johnson Lumber will have to shut down for a year, risking the loss of customers and putting several people from the struggling community around the mill out of a job. If Johnson Lumber closes entirely, it will put its workers in an even worse position. But would it be feasible to use other mills' facilities? What if the other mills turned them down? On top of everything, the owner and his son have differences in their attitudes about and goals for the business. Baker must consider the options carefully and balance the pressure to please both the current and future owners of Johnson Lumber with what would be best for the business and the local community whose families it helped support. Excerpt UVA-ENT-0196 Rev. Feb. 18, 2020 Johnson Lumber: Bet on the Upside or Avoid the Downside? Friday, March 9, 2006 The ringer on James Baker's phone seemed overly loud. Perhaps that was because it was 4:00 a.m., and he was in a hotel room on a business trip. It was never good news when the phone rang at that hour. This case was no exception. It was Janet McAleer, the security guard at Johnson Lumber's planing mill facility in Ladysmith, Virginia. “The mill has smoke in it,” she said. A fire in a lumber mill, which was by definition filled with fuel, was to be taken seriously. . . .

De windmolen

The windmill. The origins of a Dutch icon The windmill is an icon of the Netherlands. But when did this instrument acquire this symbolic role at home and abroad? After all, mills are also common outside of the Netherlands. In this essay, it is argued that during the second half of the 19th century, foreigners systematically identified the Netherlands and the windmill for the first time. More than in other countries, there was a varied use of mills in the Netherlands, large and robust mills and clusters of industrial mills. Within the Netherlands itself, development towards an iconic position is only visible around the turn of the century when the mill turned out to be a plus in tourist recruitment abroad and when mills were slowly disappearing from the landscape.

Influences of linear interpolation method and cutting parameters on machined surface texture in large curvature surface milling

Influences of linear interpolation method and cutting parameters on machined surface texture in large curvature surface milling

Spatial assessment of the techno-economic potential of bioelectricity production from sugarcane straw

The techno-economic potential of bioelectricity from sugarcane straw is highly affected by the availability and distribution of straw, the scale of the sugarcane mill and its proximity to the grid connection. All these parameters present high spatial variation. This study aims to spatially assess the techno-economic potential of bioelectricity from straw of the mills from São Paulo state (Brazil). It is assumed that all 174 mills are equipped with an adjacent power plant, and that all straw within the collection radius of the mill can potentially be used in the adjacent power plant. The straw costs are assessed making use of the spatial information on straw availability and the collection radius of the mills. The bioelectricity costs are calculated taking into account the scale efficiency, investments and operational costs, and cost of connecting to the nearest transmission infrastructure. The bioelectricity costs range between 68 and 266 US$.MWh−1 across mills. The mills with high bioelectricity potential and low costs are generally large mills located in traditional sugarcane areas characterized by suitable agro-ecological conditions. Assuming a cut-off price of 80 US$.MWh−1, the techno-economic potential of bioelectricity of straw in Sao Paulo is 14.2 TWh, which equals 10% of total electricity consumption of the state.

Effect of HRT on performance of hybrid upflow anaerobic sludge blanket (HUASB) reactor using bio balls in treatment of pulp and paper mill bagasse wash water

Abstract Enormous quantities of bagasse are being used as raw material in agro based large integrated pulp and paper mills. Anaerobic technology is an effective means of biodegradation of organic substance in wastewater and energy production of biogas that can be used as an alternative fuel. This study illustrates the effect of HRT on performance of lab scale hybrid upflow anaerobic sludge blanket (HUASB) reactor on treatment of pulp and paper mill bagasse wash water. The lab scale HUASB reactor was designed for an effective volume of 0.013 m3 with bio balls as packing media at the top of reactor and operated under mesophilic condition. After startup period, the reactor was operated with HRTs of 23.55, 15.98, 12.00, 10.03 and 7.97 h for the average influent COD concentrations of 2503.6 mg/L, 3918 mg/L, 5432 mg/L, 6608 mg/L and 7996 mg/L respectively. The results showed that the maximum COD removal efficiencies and TSS removal efficiencies were in the range of 68.60–92.19% and 89.56–94.66% respectively. The minimum and maximum biogas yield of 0.32 and 0.53 m3/kg CODa were obtained at influent concentration of 2503.6 mg/L and 7996 mg/L respectively.

Avaliação de implementação lean manufacturing: estudo de caso no setor de manutenção de uma siderúrgica de grande porte

O Lean Manufacturing tem se mostrado uma importante ferramenta de gestão para organizações que visam competitividade em um mercado cada vez mais exigente e informado. Este artigo apresenta uma avaliação do grau de implementação da filosofia Lean no setor de manutenção de componentes em uma oficina central, situada em uma usina siderúrgica de grande porte localizada no estado de Minas Gerais. Para alcançar o objetivo deste estudo foram realizadas visitas ao setor e entrevistas semiestruturadas com a equipe que trabalha no programa de implementação da filosofia junto aos funcionários. Anexo as entrevistas foram formulados checklists que avaliaram qualiquantitativamente as ferramentas implementadas gerando dessa maneira um gráfico do grau de implementação das mesmas. Apesar de certo grau de subjetividade inerente ao processo de avaliação qualitativo, é possível identificar no artigo, o atual grau de maturidade da filosofia, destacando forças e fraquezas na implementação, sinalizando assim aspectos que merecem especial atenção no processo de aperfeiçoamento do modelo enxuto.

Flexible, thermally conductive layered composite films from massively exfoliated boron nitride nanosheets

Flexible, electrically insulating and highly thermally conductive materials are desired in the thermal management application of next-generation electronic devices. In this work, bulk boron nitride are exfoliated in N-methyl-2-pyrrolidone solvent through a unique combination of large and small ball milling, generating large-volume dispersion with plane defect-free, few-layered boron nitride nanosheets. The exfoliated dispersion is concentrated through centrifugation and further processed into large-area, layered composite films with poly(vinylidene fluoride) through a scalable doctor-blading technique. The high quality of boron nitride nanosheets and their well-ordered layered arrangement imparts the composite film with high in-plane thermal conductivity and low through-plane thermal conductivity. With incorporation of 60 wt% boron nitride nanosheets, the in-plane thermal conductivity is as high as 11.88 W/m K, two orders of magnitude larger than neat poly(vinylidene fluoride). The through-plane thermal conductivity is only 0.41 W/m K, about the same as neat poly(vinylidene fluoride). Besides, the composite film is highly flexible and can be folded without fracture.

Analysis of load sharing capability of a series-connected twin synchronous motor drive coupled to a common load shaft by gearing

Torque limitations on gear teeth led to the use of two motors on opposite sides of the gear to drive large grinding mills. For such systems, motor overheating and rapid gear-teeth wear have been observed, especially when using synchronous motors due to load imbalance between the two motors. This paper studied a drive system consisting of two separate three-phase synchronous motors whose phase windings are split into two sections in a manner that makes them appear as six-winding machines, and then each of the resulting six windings of one motor are connected in series with those of the other motor, with no phase transposition, such that only three terminals of each motor are available to be connected to supply. The field windings are connected in parallel to the same source. Again, the motors, running on separate shafts, are connected to a common load shaft through a speed reduction gear driven through pinions. A detailed mathematical model is developed in the q-d axis, and the system is implemented on the MATLAB/ SIMULINK environment. A circumferential error in the girth gear was modeled to introduce load imbalance. It is observed that despite the load imbalance, the stator currents and the load torque seen by the two motors are the same. However, a variation is observed in their rotor angles. This suggests that while the motor units inherently share the mill load equally thereby removing the possibility of motor overheating, the varying rotor angle may represent a problem for the motor shafts. Keywords: Six-winding Machine, Synchronous Motors, Series-Connected, Common Load Shaft, Speed Reduction Gear, q-d Axis

Инновационные решения в управлении качеством продукции мукомольных предприятий

The present research features the Russian flour-milling industry. Flour manufacturers are a key component of the bread- baking complex of Russia, which ensures the food security of the country in the conditions of import substitution. However, large flour mills have recently experienced a decrease in profitability indicators, and production of low-quality flour by illegal producers has increased. Hence, the quality management system of flour milling enterprises requires new methodological approaches to assess the effectiveness of quality control procedures and innovative ways to improve product quality management that would ensure the competitive advantage. Quality management should be based on representative information obtained by using differential or complex methods, with numerical values established by measuring various indicators of product quality, i.e. objective and subjective. The quality assessment system should be used to determine the quality level at each stage of the innovation process, which will allow for effective management decisions. The considered quality assessment methods were adapted to the sectoral specifics of the milling industry, since the efficiency of grain processing largely depends on the stability of regimes at all its stages. The paper introduces an economic and mathematical model that includes the calculation of three groups of assessment indicators: the quality of preparation of raw materials for grinding, the quality of the technological process, and the technical level of production. The performance indicators of their activities proved to be significantly affected by the quality characteristics of the processed raw materials, the efficiency of process control, and the use of the potential of the technical level of production. The analytical studies conducted by the authors revealed trends in the product quality management at sectoral enterprises and proved the need to use system-oriented innovative solutions at all stages of flour production.

Segregation of water and gravel using large ball mill device with roughness bed

Segregation of water and gravel using large ball mill device with roughness bed

NEW APPROACH IN MODIFYING QUENCHING PROCESSES BASED ON POSSIBILITY OF CONTROLLING STEEL’S SURFACE TEMPERATURE BY INSULATING LAYER

In the paper is shown a possibility to govern surface temperature of steel parts during quenching by controlling the thickness of the insulating layer. That results in developing the new quenching technologies like austempering process via cold liquids. The investigations were performed with a low concentration of the polyethylene in cold water using 20 mm cylindrical probe instrumented with two thermocouples. It is established that with the increase concentration of polyoxyethylene in cold water (beginning from 0.001 %) different heat transfer modes are observed resulting in the elimination of film boiling process at 0.001 % concentration, increasing surface temperature of probe during self – regulated thermal process, periodical changing of heat flux densities, slow cooling of surface temperature like in oil when concentration reaches 1 % polyoxyethylene in water, and so on. It is underlined that low concentration of polyoxyethylene in water can serve as an excellent quenchant for accelerated and uniform cooling of steel parts decreasing by this way the cost of a coolant. In this case accelerated cooling should be interrupted at proper time to provide optimal hardened layer afterr quenching. Such approach guarantees increasing service life of steel parts after accelerated cooling with the significant decrease of their cost and eliminates carburization process, The technology can be used for hardening large steel parts like large wind mill gears, large bearing rings, etc.

Scaled-up pulverizing for lignocellulose biomass using a vibratory mill with ring media

Japanese cedar pulverization differences related to mill chamber size on the vibration mill with ring media (tandem ring mill) were investigated to accumulate data for scaled-up pulverization as pretreatment for enzymatic saccharification. Pulverization was conducted using tandem ring mills of three types: HV30, TR3000, and HV70. Their respective mill chamber inner diameters and interior lengths were 278 mm and 216 mm, 280 mm and 1640 mm, and of 669 mm and 3000 mm. Pulverization results were compared in terms of particle size, enzymatic saccharification efficiency and energy efficiency. Results demonstrate that the HV30 was more effective for preparing powder for high enzymatic saccharification than other tandem ring mills. However, the pulverization efficiency was lower for the HV 70 with a large mill chamber. Results showed a similar relation between energy consumption and the saccharification efficiency irrespective of the length differences of HV30 and TR3000. The TR3000 showed a slight performance advantage for unit energy consumption for scaled-up pulverization.

Stored product insects at a rice mill: Temporal and spatial patterns and implications for pest management: Presentation

Monitoring is fundamental to integrated pest management programs since it provides feedback on effectiveness of prevention programs and helps with targeting interventions as needed and evaluating their effectiveness. Rice mills are spatially complex facilities that have a combination of rough rice storage bins, buildings where rice is milled and processed, and warehouses and bulk storage bins where finished product is held before shipment. Each of these structures can have its own suite of insect species, different levels of risk, as well as different suites of management tools available. At a large rice mill in Brazil, stored product insect activity was monitored using food bait traps placed around rough rice receiving areas and storage bins; inside building containing white rice mill, rice flour mill, and packaging; and inside building for processing parboiled rice. The facility was monitored from 2010 to 2018 with 100 traps. Major pest species recovered at the facility included Sitophilus oryzae, Sitophilus zeamais, Rhyzopertha dominica, Tribolium castaneum, Cryptolestes ferrugineus, Ahasverus advena, Oryzaephilus surinamensis, Typhaea stercorea, Anthicus floralis, and Nitidulidae species. Temporal and spatial patterns in abundance were evaluated for each of the major species and for major functional groups (primary feeders, secondary feeders, and fungal feeders). Monitoring data generated was used to guide pest management programs and also provided the information needed to develop management thresholds.

Energy management practices in Bangladesh's iron and steel industries

The aim of this paper was to study energy management and improved energy efficiency among large iron and steel mills in Bangladesh. The results show that there are some barriers to energy management practices among large steel mills, the most important barriers being the perceived absence of cost-effective technical measures, high perceived risks due to uncertain future energy costs and poor information quality. However, this study has shown that the reduction in energy costs due to improved energy efficiency constitutes the most important driver for energy efficiency in the studied steel mills. The results also show that most of the steel mills have not had any technical energy efficiency improvement measures implemented in the production process. Moreover, the steel mills seem unfamiliar with the concept of including energy service companies, and the lack of information or awareness seems to be the main reason behind this. The paper also finds that energy efficiency is perceived to be able to be improved by 6%–8% through energy management practices.

Technoeconomic assessment of hydrothermal liquefaction oil from lignin with catalytic upgrading for renewable fuel and chemical production

Lignin is a readily available by‐product of the Kraft pulping process, and may be processed via hydrothermal liquefaction (HTL) to produce a bio‐oil suitable for cofeeding into a petroleum refinery hydrotreatment unit. HTL of lignin is performed in near‐critical water and, in addition to the bio‐oil, produces an aqueous organic and solid char phase. The aqueous organics are primarily phenolics, which may be converted into valuable coproducts via liquid–liquid extraction and hydrotreatment to benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds. Three technological scenarios were developed: a current technology case, a state‐of‐the‐art research case, and an optimal case based on product targets provided by refiners. For a large Kraft pulp mill (400 metric tons/day of dry lignin), a renewable fuel production of 65–70 million L/year, with capital costs of $114–125 million and a final per liter cost of $0.41–0.44 were estimated. The BTEX coproduct yield ranged from 16.8–18.0 million L/year. An economic analysis of the process revealed that the hydrotreatment steps have the highest installed capital costs, while the liquid–liquid extraction process is the largest operating cost. Based on these results, the minimum selling price (MSP) of the biofuel is between $3.52 and $3.86/gallon, and the MSP of BTEX is between $1.65 and $2.00 per liter. With current technology, coproduction of BTEX does not offset the cost of biofuel production. Improved technology to further lower bio‐oil oxygen content and decrease both capital and operating costs are needed to make HTL‐based fuels competitive with fossil fuel‐based options.This article is categorized under: Energy Research & Innovation > Science and Materials Bioenergy > Economics and Policy Bioenergy > Systems and Infrastructure