scholarly journals INFLUENCE OF GROOVES AND POSITION OF ELECTRODES ON THE TEMPERATURE DISTRIBUTION OF A FLAT MOLD USING HIGH-FREQUENCY DIRECT RESISTANCE HEATING

2020 ◽  
Author(s):  
KAZUTO TANAKA ◽  
YOSHIKI FURUKAWA ◽  
TSUTAO KATAYAMA ◽  
KIMITAKA WATANABE ◽  
MASATAKA KAWAGUCHI ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
High Frequency ◽  
Resistance Heating

Embedded resistive heating in composite scarf repairs

2016 ◽  
Vol 51 (18) ◽  
pp. 2575-2583 ◽  
Author(s):  
Mahdi Ashrafi ◽  
Brandon P Smith ◽  
Santosh Devasia ◽  
Mark E Tuttle
Keyword(s):  
Temperature Distribution ◽  
Outer Surface ◽  
Thermal Gradient ◽  
Thermal Damage ◽  
Electrical Current ◽  
Tensile Tests ◽  
Resistance Heating ◽  
Uniform Temperature ◽  
Uniform Temperature Distribution ◽  
Bond Strengths

Composite scarf repairs were cured using heat generated by passing an electrical current through a woven graphite-epoxy prepreg embedded in the bondline. Resistance heating using the embedded prepreg resulted in a more uniform temperature distribution in the bondline while preventing any potential thermal damage to the surface of the scarf repairs. In contrast, conventional surface heating methods such as heat blankets or heat lamps lead to large through thickness thermal gradient that causes non-uniform temperature in the bondline and overheating the outer surface adjacent to the heater. Composite scarf repair specimens were created using the proposed embedded heating approach and through the use of a heat blanket for circular and rectangular scarf configurations. Tensile tests were performed for rectangular scarf specimens, and it was shown that the bond strengths of all specimens were found to be comparable. The proposed embedded curing technique results in bond strengths that equal or exceed those achieved with external heating and avoids overheating the surface of the scarf repairs.

Local Prevention of Hardening for Punching of Hot-Stamped Parts

2015 ◽  
Vol 639 ◽  
pp. 205-212 ◽  
Author(s):  
Kenichiro Mori ◽  
Tomoyoshi Maeno ◽  
Takuya Suganami
Keyword(s):  
Temperature Distribution ◽  
Laser Cutting ◽  
Heating Temperature ◽  
Resistance Heating ◽  
Hardness Distribution ◽  
Delayed Fracture ◽  
Austenitic Transformation ◽  
Sheared Edge ◽  
Heat Transfers

Punching portions of the sheet are sandwiched between the ceramic billets during rapid resistance heating to prevent hardening of these portions. When the heating temperature is locally lower than that of the austenitic transformation, i.e. below 800 oC, this portion is not hardened without occurrence of martensitic transformation, and thus cold punching of hot-stamped parts becomes easy. The ceramic billets are made of alumina and the heat transfers to the billets. The temperature distribution just after resistance heating, the hardness distribution of the hot-stamped sheet, the cold punching load, the quality of the punched hole, etc. were measured. Hardening of punching portions was successfully prevented by sandwiching between the ceramic billets. The cold punching load for the local prevention of hardening was half of that without local prevention and the delayed fracture was also prevented, whereas the drop in hardness around the sheared edge became larger than that for laser cutting.

Three Dimensional Analysis of High Frequency Induction Welding of Steel Pipes With Impeder

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Hyun-Jung Kim ◽  
Sung-Kie Youn
Keyword(s):  
Temperature Distribution ◽  
High Frequency ◽  
Three Dimensional ◽  
Proximity Effects ◽  
Small Scale ◽  
Element Analysis ◽  
Steel Pipes ◽  
High Processing Speed ◽  
High Frequency Induction

High frequency induction welding is widely employed for longitudinal seam welding of small scale tubes and pipes due to its relatively high processing speed and efficiency. This research is aimed at understanding the variables that affect the quality of the high frequency induction welding. The welding variables include the welding frequency, weld speed, vee angle, and tube thickness. Temperature distribution of the tube is calculated through three dimensional coupled electromagnetic and thermal finite element analysis. The skin and proximity effects are considered in the electromagnetic analysis. The influence of the impeder is also analyzed. The effects of the operating welding variables on the temperature distribution are investigated quantitatively by exhibiting the heat affected zone. The results explain the mechanism of significant enhancement of welding efficiency when the impeder is used. Not only good weld state can be obtained but also overheated edge can be avoided by understating the effect of welding variables. Suggestions are made for the better induction welding conditions.

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.

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