Hydroforming

About: Hydroforming is a research topic. Over the lifetime, 2796 publications have been published within this topic receiving 26293 citations. The topic is also known as: Bulge forming.

Lubricants suitable for hydroforming and other metal manipulating applications

Abstract: The present invention discloses a hydroforming process for metal parts that uses liquid-film and solid-film lubricants The lubricants used in the invention are particularly useful for die-side lubrication The process includes a step in which a ductile metal part is over-coated with either the liquid-film or solid-film lubricant The liquid lubricants preferably include an oil and a optionally a surfactant The solid lubricants preferably include a hard wax and optionally a surfactant

Magnesium tube hydroforming

Abstract: Magnesium alloys reveal a good strength-to-weight ratio in the family of lightweight metals and gains potential to provide up to 30 % mass savings compared to aluminium and up to 75 % compared to steel. The use of sheet magnesium alloys for auto body applications is however limited due to the relatively low formability at room temperature. Within the scope of this paper, extruded magnesium tubes, which are suitable for hydroforming applications, have been investigated. Results obtained at room temperature using magnesium AZ31 tubes show that circumferential strains are limited to a maximal value of 4 %. In order to examine the influence of the forming temperature on tube formability, investigations have been carried out with a new die set for hot internal high pressure (IHP) forming at temperatures up to 400 °C. Earlier investigations with magnesium AZ31 tubes have shown that fractures occur along the welding line at tubes extruded over a spider die, whereby a non-uniform expansion at bursting with an elongation value of 24 % can be observed. A maximum circumferential strain of approx. 60 % could be attained when seamless, mechanically pre-expanded and annealed tubes of the same alloy have been used. The effect of annealing time on materials forming properties shows a fine grained structure for sufficient annealing times as well as deterioration with a large increase at same time. Hence, seamless ZM21 tubes have been used in the current investigations. With these tubes, an increased tensile fracture strain of 116 % at 350 °C is observed as against 19 % at 20 °C, obtained by tensile testing of milled specimens from the extruded tubes. This behaviour is also seen under the condition of tool contact during the IHP forming process. To determine the maximum circumferential strain at different forming temperatures and strain rates, the tubes are initially bulged in a die with square cross-section under plane stress conditions. Thereafter, the tubes are calibrated by using an optimised pressure-time curve. The IHP forming process has also been used to demonstrate practicability and feasibility for real parts by manufacturing a technology-demonstrator part using the magnesium alloy ZM21.

Enhancement of drawability of cryorolled AA5083 alloy sheets by hydroforming

Abstract: In this paper, an attempt has been made to enhance formability of cryorolled AA5083 alloy sheets (annealed at 275 °C for 15 min) in deep drawing of flat bottom square cup-shaped parts by hydroforming. Numerical simulations based on finite element method have been carried out to study the effect of important process parameters (fluid pressure and sealing force) on formability. The minimum corner radius and the maximum depth that can be achieved without failure and the maximum percentage thinning at the corners have been considered as measures of formability. The results have been compared with conventional deep drawing. The simulation results have also been validated with experimental work in both hydroforming and conventional forming. A process window with optimum combination of peak sealing force and peak pressure has been identified to form the cups up to full depth of the die without failure at die entry or bottom corners. Lubrication between the die and the blank reduced the minimum possible corner radius to nearly 16 mm with thinning less than 6%. In conventional forming only 70% of the full depth could be obtained before failure with 16 mm punch corner radius due to much higher thinning at the corners. This work demonstrates that, by hydroforming, formability of high strength cryorolled Al alloy sheets can be enhanced due to lower thinning and more uniform strain distribution and hence this process route (cryorolling followed by hydroforming) is a potential technique to produce complex parts from lightweight high strength Al alloy sheets due to enhanced formability.

Enhancement on plastic deformation of curved surface shell by sheet hydroforming with optimized pre-bulging process

Abstract: For sheet metal components, the enhancement of formability during plastic deformation is a key criterion in the evaluation of forming quality. To realize homogenous deformation during the forming of curved surface shells, a pre-bulging process combined with sheet hydroforming technology was designed. The pre-bulging shape was optimized using response surface methodology. An experimental setup was manufactured to conduct pre-bulging and sheet hydroforming process. The distribution of strain and thickness were measured to present the formability of the parts. The stress distribution was calculated to analyze the deformation mechanism. Results show that when using appropriate pre-bulging and sheet hydroforming process, the average strain value and uniform deformation parameter can be improved simultaneously. The microhardness of formed shell is increased. The stress state in the center region after pre-bulging is changed to biaxial compression state. It can be concluded that the combination between optimized pre-bulging effect and sheet hydroforming process is a potential method for the enhancement of formability including deformation value and uniformity.