Heat treatments, such as steel tempering, are temperature-controlled processes. It allows ferrous steel to stabilize its structure after the heat treatment and quenching stages. The tempering temperature also determines the hardness of the steel, preferably to its optimum working strength. In a tempering furnace, a heat-resistant fan is commonly employed to generate moderate gas circulation to obtain adequate temperature homogeneity and heat transfer. Nevertheless, there is a tradeoff because the overall thermal efficiency is expected to reduce because of the high rotating speed of the fan. Therefore, this study numerically investigates the thermal efficiency changes of an electric tempering furnace due to changes in the rotating speed of the fan and the effects on temperature homogeneity and the heat transfer rate to the load. Heat losses through the walls were calculated from the external temperature measurement of the furnace. Four different speeds were simulated: 720, 990, 1350, and 1800 rpm. Thermal homogeneity was improved at higher rotating speeds; this is because the recirculation zone caused by the fan improved the flow mixing and the heat transfer. However, it was found that the thermal efficiency of the tempering furnace decreased as the rotating speed values increased. Therefore, these characteristics should be modulated to obtain a profit when controlling the rotating speed. For example, although thermal efficiency decreases by 20% when the rotating speed is doubled, the heat transfer rate to load is increased by up to 50%, which can be beneficial in decreasing the process of tempering times.

Numerical Simulation of the Flow and Heat Transfer in an Electric Steel Tempering Furnace

The cutting force spectrum of the CNC lathe is the basic data for the reliability design, reliability test, and reliability evaluation of the CNC lathe and its components. Due to the complex and changeable turning conditions and different cutting processes, the cutting load presents multi-peak characteristics. At the same time, grouping the counted load cycles when parameter modeling will produce certain errors. As a result, the parameter distribution model cannot meet the modeling requirements. Thus, a compilation method based on kernel density estimation (KDE) of goodness-smoothness comprehensive evaluation (G-SCE) is proposed. The KDE is used to establish the dynamic cutting force distribution of the CNC lathe in which grouping the counted load cycles is not needed. For the bandwidth-determining methods, the rule of thumb method (ROT) and the least-squares cross-validation method (LCV) do not take into account the influence of different bandwidths on the goodness estimation and the smoothness of the estimated curve, and the G-CSE for KDE is proposed to determining the optimal bandwidth. It includes the estimation accuracy test method based on multiple goodness-of-fit tests and the smoothness test method based on the envelope curve, and the entropy method is used to comprehensively weights the estimated goodness index and the smoothness index to determine the optimal bandwidth. The results of the case analysis indicate that the method proposed can solve the problem of too large estimation error of parameter distribution for multimodal distribution. At the same time, it can better comprehensively evaluate the KDE under different bandwidths. In short, a new method of optimal bandwidth selection is proposed in the original method.

/pdf/compilation-method-of-cnc-lathe-cutting-force-spectrum-based-4hljyp73xa.pdf

Compilation method of CNC lathe cutting force spectrum based on kernel density estimation of G-SCE

Today, sustainability represents a fundamental concept to be developed and implemented in any industrial context. Therefore, it is essential to be able to measure sustainability performance by proper indicators, along the entire lifecycle and the value chain, considering environmental, economic, and social impacts. Moreover, every manufacturing company should have a specific measuring framework to calculate all the specific parameters. In this direction, the modern digital transition and Industry 4.0 (I4.0) technologies are proposing to transform human–machine relations, with a significant impact on social and organizational aspects. At the same time, digitization can help companies to define and implement sustainability by correlating production with proper evaluation metrics. The aim of this research is to provide a complete overview of sustainability Key Performance Indicators (KPIs) based on the Triple Bottom Line concept, referring to the three sustainability areas. Such an overview can be used by companies to set their specific KPIs and metrics to measure their sustainability level, according to their needs.

/pdf/sustainability-and-industry-4-0-definition-of-a-set-of-key-ua94sm33.pdf

Sustainability and Industry 4.0: Definition of a Set of Key Performance Indicators for Manufacturing Companies

The impeller is the primary working component of centrifugal fans, whose internal flow directly determines the performance of the whole system. This work presents a numerical investigation by using ANSYS-Fluent on the internal flow of a Sirocco fan to investigate the effects of the inclination angle of the blades on the fan performance. The orientation of the blade for the baseline model is strictly along the axial direction, while three inclination angles, i.e., 3.5°, 7.0°, and 10.5°, are chosen for the inclined blades of the modified impeller to improve the aerodynamic performance of the fan. The effects of the inclined blade are demonstrated by the variations in static pressure, efficiency, and pressure and velocity distributions at various inclination angles. The computed results reveal that there is an optimum inclination angle, which produces the best aerodynamic performance.

Effects of an Inclined Blade on the Performance of a Sirocco Fan

Considering that there are many design variables in multi-blade centrifugal fans, the complicated design parameters and internal flow uncertainty increase the difficulty of studying fan noise mecha...

Sandip T. Chavan

Papers

Effect of Volute Tongue Clearance Variation on Performance of Centrifugal Blower by Numerical and Experimental Analysis

Static and Fatigue Analysis of Lathe spindle for Maximum Cutting Force

Optimization of Casting Yield in Multi-cavity Sand Moulds of Al-alloy Components

To predict the surface roughness of Black ABS component with variable parameters by applying the Taguchi method

Prioritization of Green Supply Indicators with Analytic Hierarchy Process (AHP) Model