Papers by Keyword: Temperature Control

Abstract: In modern conditions of expanding the use of intelligent manufacturing technologies and increasing requirements for the physical and mechanical characteristics of parts, modeling and assessment of the physical and mechanical characteristics of parts should begin with obtaining correct initial data on the structure of the parts material, taking into account its technological history. However, for some of production technologies, in present time, it’s quite problematic to obtain correct data to take into account a huge number of factors. For example, in the manufacture of thin-walled, low-rigidity parts from polymer composite materials (PCM) using the technology of autoclave vacuum infusion molding with after-heating, the influence of external factors is very huge. This is most noticeable in the manufacture of large low-rigidity parts, for which after-heating is possible only outside the autoclave, or, sometimes, only without removing the part from the mold equipment.

Abstract: Gasification is a technology that can convert biomass into alternative energy. Temperature control in this study is used to control the temperature in the oxidation zone of the gasification process. The weakness in the gasification process is the instability of the syngas produced as a result of the changes in temperature and raw materials in the reactor. Thus, one way to stabilize the syngas produced in the gasification reactor is to control the temperature by controlling the rotational speed of the blower. In this study, the gasification reactor used was a downdraft gasifier type with a 3-level air input made from palm hemp pellets. The results of the study that the performance indicators for gasification without temperature control obtained syngas composition results CO = 21.12 % v, H₂ = 12.39 % v, and CH₄ = 1.33 % v. The calorific value (LHV) of syngas is 4524.97 kJ/kg, the efficiency of cold gas is 58.34%, and the tar content is 77.33 mg/Nm³. While gasification with temperature control results obtained syngas composition CO = 26.12% v, H₂ = 9.3% v, and CH₄ = 1.32% v. The calorific value (LHV) is 4746.82 kJ/kg, the efficiency of cold gas is 61.23%, and the tar content is 60.95 mg/Nm³. The results obtained using temperature control showed an increase in LHV of about 4.9%, an increase in gas efficiency of 2.89% cold, and a decrease in tar content of 16.4 mg/Nm³. The results of this study can be used to further optimize the syngas gasification process.

Abstract: Friction Stir Additive Manufacturing (FSAM) is a novel process with which large-scale aluminum structures can be produced from high-strength alloys such as the 7xxx series. Due to the prevalence of these alloys in airplanes and rockets, the process offers high application potential, for example in fabricating stringers and stiffeners. The building process in FSAM is characterized by sequentially stacking and friction stir lap welding (FSLW) metal sheets. Before adding the next layer, the surface is machined (i.e., by milling). So far, this is a necessary step to enable gap-free welding of the layers, which results in increased costs and reduced layer heights. The investigations described in this paper were aimed at improving the weld surface quality to enable defect-free FSAM without the additional machining step. For this, FSLW was conducted using different welding tools. The resulting welds were evaluated based on superficial and internal characteristics as well as the mechanical properties (shear strength). With a welding tool in which both a rotating and a stationary shoulder were combined, defect-free weld seams with a mean underfill and a mean flash height of 0.07 mm were produced. In a subsequent study, it was proven that defect-free FSAM without surface machining is possible up to the fifth layer using the combined welding tool.

Abstract: Friction Stir Welding (FSW) is a suitable technology to join dissimilar metals such as aluminum and copper or aluminum and titanium. Since it is a solid state welding process, the solidus temperature is typically not exceeded and the formation of intermetallic phases can be minimized compared to fusion welding processes. However, an intermetallic layer is still formed at the joining interface. This layer determines the seam properties such as the joint strength or the electrical conductivity. The thickness of the layer is in the nanometer range and is mainly influenced by the welding temperature via an Arrhenius law. The process temperature mainly depends on the rotational speed and on the feed rate of the machine tool. In this study, a temperature control system for aluminum-copper lap joints was developed. A PI control system was used for this purpose to maintain the given welding temperature by adjusting the rotational speed. Consequently, a constant welding temperature was ensured along the entire seam and influences such as changes in workpiece geometry, environmental conditions, or material variations could be mitigated. Experiments with six different temperature levels (low – high) were conducted for one exemplary welding task in order to verify the proposed constant welding conditions. The joints were investigated by tensile shear tests as well as optical and electron microscopy. It was proven that temperature-controlled FSW ensures a constant thickness of the intermetallic compound layer.

Abstract: Processing of dump slag steelmaking to extract a metal component should include the stage high-temperature recovery oxide components. The efficiency of the recovery phase depends on both temperature conditions and the composition slag, and introduced additions. The exploration of the possibility and feasibility of the liquid-phase restoration for steelmaking waste slag of the Zlatoust Metallurgical Plant applying the induction heat installation is the aim of this study. Application of induction heating was tested by laboratory research for implementation of the process of the liquid-phase metal restoration from various structure dump slags of the steel-smelting production. The parameters of the reconstruction process corresponding to the maximum extraction of a metal component from the waste slag have been identified. The design of industrial induction plant for liquid slag processing with a separate periodic metal release and a depleted slag melt was developed.

Abstract: The issue of temperature control in the research devices is well known and well described in the literature. Yet in the practical applications, in every-day engineering practice there are situations where theoretical knowledge is not applicable in a straight forward manner and the proper settings of the controller parameters constitutes a problem to be addressed and solved with and individual approach. This article presents an example of commissioning of a heated test chamber that is a part of a research apparatus for testing the erosive wear of materials, developed and built at the Institute for Sustainable Technologies – National Research Institute in Radom.The test apparatus is used for eroding the surface of the tested sample with a stream of a mixture of air and an abrasive medium. The test can be performed in room temperature and in raised temperature, both for the ambient of the sample as well as for the air used to make a mixture. The maximal temperature allowed in the machine is 600°C, so the test chamber is equipped with a hermetic door and heat insulation. The construction of the chamber makes it very inertial in terms of heating and cooling, which makes the temperature control a bit challenging.The system is controlled with a PLC with software PID controller implemented in Temperature Controller library. The use of standard set-up of PID parameters resulted in heating with significant overshoot and long settling time which was unacceptable. Trials to tune the parameters with use of built-in algorithm resulted in slower heating and still didn’t eliminate the overshoot. The literature research and tests were performed to identify the problem and to implement simple solution.The article presents the selected results of the literature research and details on the performed tests. The algorithm of the final solution is presented and the characteristics of the heating process after the modification of the control algorithm. The final solution of the issue is an algorithm that uses the standard available temperature controller and the temperature monitor to influence the actions of the controller. The difficulties in identification of the control object (the chamber) caused the inability to solve the problem analytically, but the practical and empirical approach and several trials and errors allowed for the almost optimal control characteristics, which allows no overshoot and as fast as possible heating of the object.

Abstract: In this paper, a linear quadratic Gaussian controller is proposed to achieve the robust temperature stability of the fuser system against measurement noise and system disturbance. The proposed controller is fitted to replace the PI controller and relative mathematical derivation is described. The system is implemented using MATLAB and SIMULINK with adding the noise and disturbance. Improvement of performance is verified by comparison with conventional PI controller results on several key factors of the fuser system.

Abstract: The automatic heating control systems seem to be the nonlinear systems with thermal inertias and time delay. The controller is also nonlinear because its information and power signals are limited. Application of methods, which are available for nonlinear systems together with computer simulation and mathematical modeling, create possibility to reach serious information about researched system. The paper contains the heating system model with the cascade control, simulation model of this system and some simulation results created in Matlab/Simulink environment.

Abstract: This paper presents the performances of an enhanced fuzzy logic controller (EFLC) for simulated Heat Exchanger (HE) temperature control system. The HE system is modeled mathematically using Energy Balance Equation and simulated using MATLAB/Simulink software. The Fuzzy Inference Structure (FIS) used was Sugeno-type. EFLC comprises of two parts which are normalized FLC part and model reference (MR) part. Both normalized and MRFLC part was using Gaussian membership function (MF) with 7x7 rule bases. Set Point (SP) tests conducted for change from 43°C to 39°C, 39°C to 35°C and 43°C to 35°C. The performances on SP tests of the FLC and proposed EFLC were compared to PID controller. The results showed that EFLC produced lower decay ratio (DR) with less oscillations, reduced undershoot (US), shorter settling time (T_s) and minimum Integral Absoluter Error (IAE) compare to FLC and PID controller.

Abstract: The temperature of forging dies has a high influence on the wear development of the tool surface. To reduce the thermal impact on tool life cooling lubricants are used in many manufacturing processes. They perform two functions: tool cooling and reduction of friction. Cooling lubricants must always meet these two requirements. Within this article the separation and the particular optimization of both functions is presented.As an alternative to a graphite-water-mixture, boron nitride is the medium of choice for lubrication purposes, since it features excellent lubricant properties. For a high wettability it is applied by electrostatic coating.As an alternative approach to removing heat from a forging die, the usage of heat pipes is for the first time investigated in this paper. These passive elements are able to transport heat without using external energy. They will be varied in form and volume. This cooling method will be qualified for the use in forging dies.