Thermal error controlling for the spindle in a precision boring machine with external cooling across coated joints

2019 ◽  
Vol 234 (2) ◽  
pp. 658-675
Author(s):  
Mohan Lei ◽  
Gedong Jiang ◽  
Liang Zhao ◽  
Jinshi Wang ◽  
Ben Q Li ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Thermal Equilibrium ◽  
Evaluation Method ◽  
Control Method ◽  
Thermal Error ◽  
Joint Surface ◽  
Internal Cooling ◽  
Equilibrium Time ◽  
External Cooling ◽  
Boring Machines

Spindles in precision boring machines usually operate without internal cooling, and thermal error in such spindles is nonnegligible and can severely affect the end-processing quality of the machines. This study aims to investigate the effects that external cooling exerts on the thermal behavior of such spindles. A helical tube cooler is taken for external cooling. An analytical thermal resistance model for the grease-coated cooler-housing joint surface, which considers the pressured cambered-flat contact pair and rough metal surface-grease contact, is presented and validated, and a numerical thermal–fluid–solid coupling model for the cooler-spindle system is then established. An evaluation method is put forward to obtain the stability of the thermal error, which determines the boring processing accuracy and thermal equilibrium time, from experimental data. Then, the external cooling was optimally designed based on the simulation results from the numerical model. Experiments show that the designed cooler reduced the thermal equilibrium time by 47.13% and the maximum thermal error by 81.7%, and the proposed model can accurately predict the cooling effect on the spindle thermal behavior. This study not only provides a thermal error control method for the spindle but is expected to advance the theoretical basis of cooling design for complex electromechanical systems.

scholarly journals Thermal Simulation for a Mechanical Spindle With External Cooler Across Grease Coated Interface

2021 ◽  
Author(s):  
Liang Zhao ◽  
Mohan Lei ◽  
Hongdi Ren ◽  
Jinshi Wang ◽  
Shuai Wang ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Cooling System ◽  
Thermal Error ◽  
Element Model ◽  
Internal Cooling ◽  
Heavy Load ◽  
Silicone Grease ◽  
Total Thermal Resistance ◽  
Rotating Speed ◽  
External Cooling

Abstract Spindles in precision boring machine often work in low speed and heavy load without internal cooling, and the thermal error is nonnegligible. So an external cooling system was designed, and the effectiveness of the designed scheme needs to be preliminarily verified by simulation before building the cooling system. Thermal simulations of the spindle with an external cooler require calculating the thermal resistance of the thermal grease-coated interface between the cooler and spindle. Models describing the contact thermal resistance and total thermal resistance for metal contact filled with silicone grease based on solid-liquid interface force equivalence were described in this paper, and experiments were also conducted to verify the accuracy of these models. The contact thermal resistances between the cast iron/copper and silicone grease on flat or arc surfaces were calculated, and the bulk thermal resistance of the silicone grease layer was calculated. The total heat transferred between the cooler and the silicone grease-coated interface of the spindle were calculated. Heat transfer and heat generation in the spindle were calculated, and a finite element model was established to verify the effectiveness of the designed external cooling scheme. Finally, results from experiments for the spindle in different conditions show that the external cooling system decreases the time to reach thermal equilibrium by more than 60%. The RMSE of the simulated thermal elongation is less than 5.7044 μm when the rotating speed of 3000 rpm, and is less than 3.9714 μm when the rotating speed is 1500 rpm.

scholarly journals Multivariate Statistical Analysis Uncovers Spectrum–Effect Relationship between HPLC Fingerprints and Antioxidant Activity of Saffron

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Ya You ◽  
Zijin Xu ◽  
Qingrou Zhong ◽  
Lin Zhu ◽  
Susu Lin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Quality Control ◽  
Evaluation Method ◽  
Control Method ◽  
Partial Least Square ◽  
Least Square ◽  
Crocus Sativus ◽  
Effect Relationship ◽  
Spectrum Effect

Crocus sativus L. is commonly used as functional food and medicinal herb in traditional Chinese medicine. In this study, the spectrum–effect relationship was established between HPLC fingerprints and in vitro antioxidant activity of saffron to improve the quality evaluation method of saffron. The fingerprints of 21 batches of saffron collected from different regions were assessed, and the data were further analyzed by chemometric methods, including similarity analysis, hierarchical clustering analysis, principal component analysis, and orthogonal partial least squares discriminant analysis. The spectrum–effect relationship between fingerprints and antioxidant effect of saffron was analyzed by grey relational analysis and partial least square methods to figure out the antioxidant component of saffron. Thirteen common peaks of 21 batches of saffron were included in the analysis, and peak 3 (picrocrocin), peak 7 (crocin I), and peak 10 (crocin II) were identified as the main active components responsible for antioxidant efficacy. Besides, a multi-index quality control method was developed for simultaneous determination of these three antioxidant components in saffron. Taken together, this study provided new strategies for the quality control and the development of new bioactive products of saffron in the future.

Experimental Evaluations of the Relative Contributions to Overall Effectiveness in Turbine Blade Leading Edge Cooling

2018 ◽  
Author(s):  
Carol E. Bryant ◽  
Connor J. Wiese ◽  
James L. Rutledge ◽  
Marc D. Polanka
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Leading Edge ◽  
Internal Surface ◽  
Internal Cooling ◽  
Transfer Coefficients ◽  
Impingement Cooling ◽  
External Cooling ◽  
Turbine Component ◽  
Overall Effectiveness

Gas turbine hot gas path components are protected through a combination of internal cooling and external film cooling. The coolant typically travels through internal passageways, which may involve impingement on the internal surface of a turbine component, before being ejected as film cooling. Internal cooling effects have been studied in facilities that allow measurement of heat transfer coefficients within models of the internal cooling paths, with large heat transfer coefficients generally desirable. External film cooling is typically evaluated through measurements of the adiabatic effectiveness and its effect on the external heat transfer coefficient. Efforts aimed at improving cooling are often focused on either only the internal cooling or the film cooling; however, the common coolant flow means the internal and external cooling schemes are linked and the coolant holes themselves provide another convective path for heat transfer to the coolant. Recently, measurements of overall cooling effectiveness using matched Biot number turbine component models allow evaluation of the nondimensional wall temperature achieved for the fully cooled component. However, the relative contributions of internal cooling, external cooling, and convection within the film cooling holes is not well understood. Large scale, matched Biot number experiments, complemented by CFD simulations, were performed on a fully film cooled cylindrical leading edge model to evaluate the effects of various alterations in the cooling design on the overall effectiveness. The relative influence of film cooling and cooling within the holes was evaluated by selectively disabling individual holes and quantifying how the overall effectiveness changed. Several internal impingement cooling schemes in addition to a baseline case without impingement cooling were also tested. In general, impingement cooling is shown to have a negligible influence on the overall effectiveness in the showerhead region. This indicates that the cost and pressure drop penalties for implementing impingement cooling may not be compensated by an increase in thermal performance. Instead, the internal cooling provided by convection within the holes themselves was shown, along with external film cooling, to be a dominant contribution to the overall cooling effectiveness. Indeed, the numerous holes within the showerhead region impede the ability of internal surface cooling schemes to influence the outside surface temperature. The results of this research may allow improved focus of future efforts on the forms of cooling with the greatest potential to improve cooling performance.

Investigation of the Conjugate Convective-Conductive Thermal Behavior of a Rib-Roughened Internal Cooling Channel

2004 ◽  
Author(s):  
Roberto Fedrizzi ◽  
Tony Arts
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Thermal Behavior ◽  
Large Scale ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Heat Flux Distribution ◽  
Metallic Wall ◽  
Scaled Models ◽  
Rib Roughened

The proposed contribution concerns an experimental investigation of the conjugate thermal behavior of a rib-roughened cooling channel. Previous investigations mainly were focused on the convective aspects of the heat transfer; the scaled models were made of low conductivity material and the heat conduction was not representative of the behavior inside a real metallic airfoil. To overcome this limitation, a large-scale facility with a metallic ribbed wall was designed and tested. Infrared thermography was used to measure the temperature distribution on the wetted surface. Dedicated software was developed to correct the temperature field distortions and to apply the radiation-temperature calibration. The convection coefficient was calculated as a function of the measured wall temperature and computed wall heat flux. The code FLUENT® was used to solve the energy equation into the metallic wall, providing the surface heat flux distribution. The complex contribution of the ribs, in terms of heat transfer, was highlighted.

scholarly journals Cutting Performance of Austenitic and Duplex Stainless Steels with Drills of Three Cutting Edges

2021 ◽  
Author(s):  
João Marouvo ◽  
Pedro Ferreira ◽  
Fernando Simões
Keyword(s):  
High Pressure ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Duplex Stainless Steels ◽  
Tool Geometry ◽  
Internal Cooling ◽  
Drilling Performance ◽  
External Cooling ◽  
Cutting Vibration

Austenitic and duplex stainless steels are considered be the best in corrosion resistance among different grades of stainless steels. Due to high strength, duplex stainless steels applications are increasingly as an alternative to the austenitic stainless steels. In this sense, the machining study of this materials is an important issue, in order to better understand the performance of the tools and the quality of the parts manufactured for high-demand industries. In this research, the machinability of both stainless steels was evaluated in the drilling operation, using drills with three cutting edges. This type of drill geometry is particularly useful when conventional solid carbide drills fail. The drill point of triple edge is very stable, demonstrating optimal positioning accuracy and better performance in deep bores. Using the same tool geometry, a comparative analysis of drilling performance on austenitic and duplex stainless steels was made. In experimental procedure, external low-pressure cooling or internal high-pressure cooling was applied alternatively. The cutting vibration, the tool wear, the roughness and the hole diameter accuracy were evaluated in the series of holes made. The obtained results show that the most important factor to increase the number of holes made is the use of high-pressure internal cooling. When external cooling is used, AISI 304 have a worse behaviour than duplex stainless steel, due to greater susceptibility to built-up-edge formation and work hardening. The tool deterioration is mainly non-uniform chipping for external cooling and flank wear for internal cooling.

Dynamic thermal behavior and thermal error prediction of spindle due to periodic jump motions in a large precision die-sinking EDM machine

2019 ◽  
Vol 33 (7) ◽  
pp. 3397-3405 ◽  
Author(s):  
Zhaoxi Zhao ◽  
Jia Zhang ◽  
Yukui Wang ◽  
Zhenlong Wang ◽  
Jianyong Liu ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Thermal Error ◽  
Error Prediction

The Effects of Periodic Suction on Separated Flow in Diffuser

2017 ◽  
Author(s):  
Jin-Chun Wang ◽  
Guoping Huang ◽  
Yu-Xuan Yang ◽  
Xin Fu ◽  
Lu Weiyu
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Evaluation Method ◽  
Control Method ◽  
Phase Locking ◽  
Separated Flow ◽  
Total Pressure Loss ◽  
Control Effect ◽  
Suction Control ◽  
Control State

The effects of periodic suction on the separated flow are still unclear and the relevant researches are still scarce, thus this paper presents a periodic suction method to suppress the flow separation in diffuser. An evaluation method of periodic suction mass flow rate’s effect on total pressure loss is developed firstly and the comparison between periodic suction and steady suction’s effect on total pressure loss was performed. The result showed that compared to steady suction, periodic suction can provide a better control effect in a wide operating range, even nearly double in some control state. Besides, the effect of periodic suction on the frequency and phase of separation vortex was studied. It showed that periodic suction control method can achieve frequency and phase locking with very low control energy. What’s more, frequency and phase locking point corresponds to the turning point of the periodic suction exerting unsteady control’s advantage. The separation vortex and it’s relation with the pressure time histories and spectral density was also investigated. Lastly, the proper orthogonal decomposition was employed to further explore the control mechanism of periodic suction. The result showed that the main effect of the periodic suction is reallocating the energy of each mode, and strengthening the second and third modes, while the steady suction weakened these modes. It indicates that the reason of the control effect difference between steady and periodic suction may be that steady suction doesn’t effectively use the energy of vortex, but removed it directly. Also, compared to the steady suction state and no-control state, the time modal coefficients in the first three modes are most orderly in the periodic suction state.

Modeling of Radiators with Mass Flow Control

2019 ◽  
Vol 887 ◽  
pp. 667-675
Author(s):  
Ondřej Šikula ◽  
Pavel Charvát ◽  
Lahouari Adjlout ◽  
Omar Ladjedel
Keyword(s):  
Energy Consumption ◽  
Time Delay ◽  
Flow Control ◽  
Thermal Behavior ◽  
Computer Modeling ◽  
Control Method ◽  
Thermal State ◽  
Heating Energy Consumption ◽  
Dynamic Phenomena

The topic of the contribution can be included in computer modeling of the thermal behavior of radiators for heating of buildings. Control of heaters leads to dynamic phenomena affecting the final thermal state of the heated room and heating energy consumption. The paper focuses on modeling of radiator quantitative control method using thermostatic valve. The objective of the paper is to show a quality of controlling and to compare an energy consumption when various thermostatic radiator valves time delay are set. The models of control, radiator, and a room are implemented in software TRNSYS. The results show significant differences in energy consumption.

Basic Research on Combinatorial Evaluation Method for Coefficient of Thermal Expansion

2007 ◽  
Vol 1024 ◽  
Author(s):  
Yuko Aono ◽  
Seiichi Hata ◽  
Junpei Sakurai ◽  
Ryusuke Yamauchi ◽  
Hiroyuki Tachikawa ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Thermal Behavior ◽  
Young’S Modulus ◽  
Evaluation Method ◽  
Coefficient Of Thermal Expansion ◽  
Young's Modulus ◽  
Ccd Camera ◽  
Basic Research ◽  
Film Library ◽  
Combinatorial Methods

AbstractThe coefficient of thermal expansion (CTE) is one of the most important material properties for actuators driven by heat or structure over a wide temperature. The CTE of an alloy depends on its composition, and combinatorial methods are very effective for researching new alloys. A CTE evaluation method, which can be applied to combinatorial methods or a thin film library, is proposed in this paper. The thermal behavior of a bi-layer cantilever couple was used for the evaluation, and the Young's modulus, which is also an important property, was simultaneously obtained. Firstly, one bi-layer cantilever was fabricated and agreement of the thermal behavior with the theoretical behavior was confirmed. The estimated error of the measurement device (CCD camera) resolution was then analyzed. The results indicate that combinatorial evaluation does not enable an accurate evaluation of Young's modulus, but does allow the CTE be accurately determined.

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