Numerical analysis of different heating systems for warm sheet metal forming

Abstract

The main goal of this study is to present an analysis of different heating methods frequently used in laboratory scale and in the industrial practice to heat blanks at warm temperatures. In this context, the blank can be heated inside the forming tools (internal method) or using a heating system (external method). In order to perform this analysis, a finite element model is firstly validated with the simulation of the direct resistance system used in a Gleeble testing machine. The predicted temperature was compared with the temperature distribution recorded experimentally and a good agreement was found. Afterwards, a finite element model is used to predict the temperature distribution in the blank during the heating process, when using different heating methods. The analysis also includes the evaluation of a cooling phase associated to the transport phase for the external heating methods. The results of this analysis show that neglecting the heating phase and a transport phase could lead to inaccuracies in the simulation of the forming phase.

The Effect of Elevated Temperature on the Drawability of a Circular Deep Drawn Metal Cup

“…According to Lean et al [3], the application of temperature increment towards the punch and die can produce several outcomes such as increasing limiting drawing ratio, an increment on the depth of drawn cup and reduce the fracturing effect. On the other hand, Martins et al [4] presented the analysis of different heating methods frequently used in laboratory scale and in the industrial practice to heat blanks at elevated temperatures. In addition to this, Palaniswamy et al [5] also presented a study of a deep-drawn cup of magnesium alloys at elevated temperature as an optimization approach for car-making industries.…”

Numerical modeling of the thermal contact in metal forming processes

“…The heat flow across the interface between two contacting bodies plays an important role in many engineering applications, such as the automotive [52], microelectronics [54], metalworking [37], and gas turbine industries [17]. The heat flow across contacting interfaces is commonly quantified by the interfacial heat transfer coefficient (IHTC), which is the inverse of the resistance to heat flow [28]. This resistance is the cause of temperature discontinuity at the interface between the bodies.…”

“…Indeed, the real contact area is a very small fraction of the nominal contact area (2 % for metallic contact). The real contact occurs only in certain discrete points, at the top of asperities [28]. The contact pressure has a close connection with the real contact area, since the deformation of the contacting asperities induced by the contact pressure increases the real contact area and, consequently, the IHTC value.…”

“…The heat transfer across the contact interface occurs by conduction through asperities in contact, convection through the fluid inside the gap, and by radiation across the gap [47]. The radiation can be negligible for temperatures lower than 300 • C [28]. The gap fluid conductance is less efficient than the conduction through asperities.…”

Application of a continuum damage mechanics (CDM)-based model for predicting formability of warm formed aluminium alloy

“…However, it is a fact that the ductility of some aluminium alloys can be enhanced by raising deformation speed (AA6082 for example) [4]. Therefore, characterising the aluminium alloy formability at elevated temperatures and for a wide range of strain rates is crucial for the wider use of elevated temperature aluminium sheet forming processes [5][6][7].…”