scholarly journals Application of Direct Resistance Heating in Hot Forging and Analysis of Processing Parameters based on Thermo-electro-mechanical Coupling FEM

2018 ◽  
Vol 37 (6) ◽  
pp. 531-538
Author(s):  
Men Zhengxing ◽  
Wang Menghan ◽  
Ma Yaxin ◽  
Yue Taiwen ◽  
Liu Ruilin
Keyword(s):  
Contact Resistance ◽  
Heating Temperature ◽  
Hot Forging ◽  
Processing Parameters ◽  
Experimental Results ◽  
Transient Temperature ◽  
Resistance Heating ◽  
Forming Process ◽  
Mechanical Coupling ◽  
Forming Temperature

AbstractA series of experiments were designed in order to directly heat the billet of 42CrMo4 to the forming temperature in the dies prior to forming and continue to heat the billet during the forming process. Processing parameters during heating and forming were investigated by experimental method and thermo-electro-mechanical coupling FEM. The experimental results show that prior to forming the billet could be rapidly heated to forming temperature under relatively low initial contact pressure, and the heating temperature was proportional to the square of the current intensity. When the heating current remained constant, the heating temperature could not increase with heating time. During the forming process, the billet cooling rate slowed down and the forming time was extended due to the continuous resistance heating during forming. Finally, an incrementally coupled thermo-electro-mechanical model has been developed to analyze the hot-forging process by direct resistance heating. To obtain the transient temperature field prior to forming, a simple model of contact resistance was used in the thermal-electrical simulation, in which the electrical conductance of the contact resistance was proportional to the heating temperature. Contrasted the experimental results and the simulation results, it was found that they coincided well.

Numerical Study on Forming Process by Continuous Resistance Heating

2010 ◽  
Vol 154-155 ◽  
pp. 867-872
Author(s):  
Zheng Xing Men ◽  
Jie Zhou ◽  
Meng Han Wang ◽  
Chang Wei Shao
Keyword(s):  
Temperature Distribution ◽  
Contact Resistance ◽  
Numerical Study ◽  
Mechanical Analysis ◽  
Transient Temperature ◽  
Resistance Heating ◽  
Forming Force ◽  
Forming Process ◽  
Billet Temperature ◽  
Die Geometry

In the present study, an axis-symmetric electro-thermo-mechanical model has been developed to analyze a deformation process by continuous resistance heating. To obtain the transient temperature field prior to forming, a novel temperature-dependent model of the contact resistance was developed in the thermal-electrical analysis. The influences of the contact resistance, the current intensity and the die geometry on the temperature distribution were investigated. In the subsequent electro-thermo-mechanical analysis of the forming process by continuous resistance heating, the variations of the billet temperature distribution, forming force were obtained. The simulation results correspond well with experimental measured values. Furthermore, the influence of a current increasing during forming on the billet temperature and forming force was predicted in order to optimize the forming technology by continuous resistance heating.

Experimental Study of Hot Forming Process by Direct Resistance Heating

2011 ◽  
Vol 704-705 ◽  
pp. 252-260 ◽  
Author(s):  
Zheng Xing Men ◽  
Jie Zhou ◽  
Zhi Min Xu
Keyword(s):  
Experimental Study ◽  
Plastic Deformation ◽  
Hot Forging ◽  
Heating Time ◽  
Resistance Heating ◽  
Forming Process ◽  
Heating Efficiency ◽  
Cylindrical Billet ◽  
Forming Temperature ◽  
Forming Condition

In order to increase heating efficiency and decrease heating time, a new hot-forging method by means of direct resistance heating was investigated in this paper. Based on the approach, the hot upsetting experiments with cylindrical billet of 42CrMo4 were performed. Moreover, the influence of the multi-layer aluminium foils inserted between the billet and the die as a forming condition on heating and forming was researched. The results of the experiments show that prior to forming the billet could be heated quickly to forming temperature in about 10 seconds. During the upsetting process the billet cooling rate was effectively decreased and the forming time was extended in relation to the resistance heating. The insertion of multi-layer aluminium foils not only improved the efficiency of the heating, but also avoided the plastic deformation of the die and the occurrence of cracks on the billet’s surface. Keywords: Resistance heating, Hot forging, upsetting, Aluminium foils Introduction

Continuous Cooling Transformation Diagram and Properties of Hot Forming Steel

2012 ◽  
Vol 152-154 ◽  
pp. 585-588 ◽  
Author(s):  
Mei Zhang ◽  
Qing Shan Li ◽  
Kun Han ◽  
Chao Bin Huang ◽  
Ru Yi Wu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Heating Temperature ◽  
Tensile Tests ◽  
Processing Parameters ◽  
Total Elongation ◽  
Hot Forming ◽  
Forming Process ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Metallographic Observation

Continuous cooling transformation (CCT) diagram of steel 22MnB5 was studied using dilatometer method. The influence of the hot forming process parameters, such as the heating temperature and holding time on the mechanical properties and microstructure of stamped parts was analyzed by tensile tests and the metallographic observation on the parts with various processing parameters. The microstructural evolution obtained from the dilatometer samples reveals that the cooling rates not smaller than 20K/s induced fully martensitic microstructure. As the cooling rate decreasing, more ferrite and pearlite or more bainitic microstructure forms. Tensile tests results show an excellent tensile strength and ductility combination of 22MnB5. The tensile strength and yield strength reach 1500MPa and 1200MPa respectively, with total elongation of around 10%.

Short Time Transient Behavior of SiGe-based Microrefrigerators

2009 ◽  
Vol 1166 ◽  
Author(s):  
Ezzahri Younes ◽  
James Christofferson ◽  
Kerry Maize ◽  
Ali Shakouri
Keyword(s):  
Time Constant ◽  
Joule Heating ◽  
Thermal Imaging ◽  
Heating Temperature ◽  
Transient Behavior ◽  
Experimental Results ◽  
Transient Temperature ◽  
Geometrical Parameters ◽  
Semiconductor Interface ◽  
Time Constants

AbstractWe use a Thermoreflectance Thermal Imaging technique to study the transient cooling of SiGe-based microrefrigerators. Thermal imaging with submicron spatial resolution, 0.1C temperature resolution and 100 nanosecond temporal resolution is achieved. Transient temperature profiles of SiGe-based superlattice microrefrigerator devices of different sizes are obtained. The dynamic behavior of these microrefrigerators, show an interplay between Peltier and Joule effects. On the top surface of the device, Peltier cooling appears first with a time constant of about 10-30 microseconds, then Joule heating in the device starts taking over with a time constant of about 100-150 microseconds. The experimental results agree very well with the theoretical predictions based on Thermal Quadrupoles Method. The difference in the two time constants can be explained considering the thermal resistance and capacitance of the thin film. In addition this shows that the Joule heating at the top metal/semiconductor interface does not dominate the microrefrigerator performance or else we would have obtained the same time constants for the Peltier and Joule effects. Experimental results show that under high current values, pulse-operation the microrefrigerator device can provide cooling for about 30 microseconds, even though steady state measurements show heating. Temperature distribution on the metal leads connected to the microrefrigerator’s cold junction show the interplay between Joule heating in the metal as well as heat conduction to the substrate. Modeling is used to study the effect of different physical and geometrical parameters of the device on its transient cooling. 3D geometry of heat and current flow in the device plays an important role. One of the goals is to maximize cooling over the shortest time scales.

scholarly journals Pengaruh Serapan Sistem Pendingin pada Shrinkage untuk Blister dari PVC

Jurnal METTEK ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 26
Author(s):  
Dikky Antonius ◽  
Budiarto Budiarto ◽  
Benedigtus Tito
Keyword(s):  
Heating Temperature ◽  
Vacuum Pump ◽  
Forming Process ◽  
Forming Temperature ◽  
Quality Check ◽  
Vacuum Test ◽  
Digital Caliper

Proses thermoforming dilakukan dengan memanaskan material lembaran plastik kemudian diberi tekanan atau vakum ke rongga cetakan untuk mendapatkan bentuk yang diinginkan. Pada penelitian ini, proses thermoforming diaplikasikan untuk membuat Blister. Dimana Blister adalah tempat memasukan obat berbentuk pila tau kapsul. Temperatur air pendingin (forming temperature) diatur dari mulai 19oC, 21oC dan 25oC, sementara temperatur pemanasan (heating temperature) disusun dari mulai 110oC, 120oC dan 130oC untuk masing-masing temperatur air pendinginan. Kualitas Blister diukur dengan metode visual, serta menggunakan jangka sorong digital untuk melihat shrinkage (cacat penyusutan) yang mungkin terjadi. Kebocoran blister juga dicek dengan menggunakan pompa vakum. Hasil akhir menunjukkan bahwa seiring temperatur air pendingin dinaikkan, maka energi yang dilepas oleh mesin sebagai panas semakin turun diakibatkan perbedaan antara temperatur pemanasan dan pendinginan yang semakin sedikit. Pengujian toleransi ukuran menggunakan jangka sorong memperlihatkan bahwa penyusutan terjauh dialami oleh sampel dengan temperatur pemanasan 110oC, pengujian visual juga menyatakan hasil dari sampel pada temperatur pemanasan 110oC tidak terbentuk semuanya.  Sampel dengan temperatur pemanasan 120oC dan 130oC mempunyai kualitas yang jauh lebih baik dalam hal toleransi dibandingkan temperatur pemanasan 110oC. Toleransi terbaik ditunjukkan oleh sampel dengan temperatur pemanasan 130oC dan pendinginan 25oC, namun sayangnya, dari pengujian vakum, parameter ini menunjukkan indikasi kebocoran. Thermoforming is one of the forming process which heating the material – usually plastic – then pressurized to form the shape. In this research thermoforming processes applied to make a Blister. Blister is one of the medicine container – usually capsule. The forming temperature is set in 19oC, 21oC, and 25oC, meanwhile heating temperature is set in 110oC, 120oC and 130oC. The quality check by visual and using digital caliper to check the shrinkage. Meanwhile, the vacuum pump is used to check the leak of Blister. The result shows that the energy released by the machine is smaller when the forming temperature is increased, caused by the differentiation of the heating temperature and the forming temperature. The highest shrinkage shown in the sample heated at 110oC and formed at temperature 19oC. However, by visual check, the sample heated at 110oC is broken regardless the forming temperature made. Better quality shown in the sample heated at 120oC and 130oC. The lowest shrinkage shown by the sample heated at 130oC and formed at 25oC, however the vacuum test indicated there are leak in the Blister.

Numerical Simulation and Process Optimization of Automotive Friction Materials in Warm Pressing Forming

2013 ◽  
Vol 788 ◽  
pp. 57-60
Author(s):  
Chun Cao ◽  
Chun Dong Zhu ◽  
Chen Fu
Keyword(s):  
Process Optimization ◽  
Heating Temperature ◽  
Maximum Energy ◽  
Heating Time ◽  
Product Performance ◽  
Forming Process ◽  
Friction Materials ◽  
Forming Technology ◽  
The Relationship ◽  
Temperature Heating

Warm pressing forming technology has been gradually applied to the forming of automotive friction materials. How to ensure product performance to achieve the target at the same time achieve the maximum energy saving is the research focus of this study. In this paper, by using finite element method, the field of automotive friction materials in warm pressing forming was analyzed, reveals the relationship between the temperature field and the heating temperature/heating time. Furthermore, the energy consumption was analyzed and compared it with hot pressing forming process. The results will have significant guiding to the process optimization in warm pressing forming.

Experimental Assessment of High Temperature Formability of Boron Steel Sheet Manufactured With a Spring Compound Bending Die

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Yang Li ◽  
Yong-Phil Jeon ◽  
Chung-Gil Kang
Keyword(s):  
Mechanical Properties ◽  
Heating Temperature ◽  
Boron Steel ◽  
Hot Press ◽  
Forming Process ◽  
Steel Sheets ◽  
Press Forming ◽  
Bending Process ◽  
Tension Testing ◽  
Hot Press Forming

Bending behavior occurs in the hot press forming process, resulting in many cases of failure during forming. To address the problem of cracking and improve the formability and mechanical properties of boron steel sheets in the bending process, an experiment has been carried out by using a spring compound bending die. Also, a comparison has been made between the traditional U-bending die and the spring compound bending die with regard to formability. The influence of the parameters for hot press forming such as the heating temperature, punch speed, and die radii on the mechanical properties and microstructure was analyzed by tension testing and metallographic observations.

Comparison between an Advanced Numerical Simulation of Sheet Incremental Forming Using Adaptive Remeshing and Experimental Results

2013 ◽  
Vol 554-557 ◽  
pp. 1375-1381 ◽  
Author(s):  
Laurence Giraud-Moreau ◽  
Abel Cherouat ◽  
Jie Zhang ◽  
Houman Borouchaki
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Sheet Metal ◽  
Metal Forming ◽  
Tool Path ◽  
Incremental Forming ◽  
Computation Time ◽  
Experimental Results ◽  
Forming Process ◽  
Adaptive Remeshing

Recently, new sheet metal forming technique, incremental forming has been introduced. It is based on using a single spherical tool, which is moved along CNC controlled tool path. During the incremental forming process, the sheet blank is fixed in sheet holder. The tool follows a certain tool path and progressively deforms the sheet. Nowadays, numerical simulations of metal forming are widely used by industry to predict the geometry of the part, stresses and strain during the forming process. Because incremental forming is a dieless process, it is perfectly suited for prototyping and small volume production [1, 2]. On the other hand, this process is very slow and therefore it can only be used when a slow series production is required. As the sheet incremental forming process is an emerging process which has a high industrial interest, scientific efforts are required in order to optimize the process and to increase the knowledge of this process through experimental studies and the development of accurate simulation models. In this paper, a comparison between numerical simulation and experimental results is realized in order to assess the suitability of the numerical model. The experimental investigation is realized using a three-axis CNC milling machine. The forming tool consists in a cylindrical rotating punch with a hemispherical head. A subroutine has been developed to describe the tool path from CAM procedure. A numerical model has been developed to simulate the sheet incremental forming process. The finite element code Abaqus explicit has been used. The simulation of the incremental forming process stays a complex task and the computation time is often prohibitive for many reasons. During this simulation, the blank is deformed by a sequence of small increments that requires many numerical increments to be performed. Moreover, the size of the tool diameter is generally very small compared to the size of the metal sheet and thus the contact zone between the tool and the sheet is limited. As the tool deforms almost every part of the sheet, small elements are required everywhere in the sheet resulting in a very high computation time. In this paper, an adaptive remeshing method has been used to simulate the incremental forming process. This strategy, based on adaptive refinement and coarsening procedures avoids having an initially fine mesh, resulting in an enormous computing time. Experiments have been carried out using aluminum alloy sheets. The final geometrical shape and the thickness profile have been measured and compared with the numerical results. These measurements have allowed validating the proposed numerical model. References [1] M. Yamashita, M. Grotoh, S.-Y. Atsumi, Numerical simulation of incremental forming of sheet metal, J. Processing Technology, No. 199 (2008), p. 163 172. [2] C. Henrard, A.M. Hbraken, A. Szekeres, J.R. Duflou, S. He, P. Van Houtte, Comparison of FEM Simulations for the Incremental Forming Process, Advanced Materials Research, 6-8 (2005), p. 533-542.

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