The most common way to establish tube length after hydroforming is by cutting or shearing the tube to a specified dimension; however, cutting out this step can reduce scrap. A new method designed to eliminate this step combines forming the end of a tube to resemble its final form with using a hydroform die to correct end position variations off the bender. While this approach eliminates the final shear trim operation, it also presents new challenges.
Hydroforming has become a competitive metal forming method and has succeeded in many applications because of its weight- and cost-saving attributes, elimination of joining operations, and ability to offer part design for confined spaces.
July 24, 2003 | By Eric Lundin
F & P Manufacturing Inc., a tier-one automotive components supplier, focused on four areas when it developed a hydroforming line for manufacturing Honda Accord engine cradles. These areas were eliminating end scrap, decoupling the bending machines from the manufacturing line, reducing cycle time, and palletizing parts.
July 10, 2003 | By Dr. Ghafoor Khodayari
It is well-known that tube has become an important material for hydroforming hollow components. The increasing complexity of product structures, particularly in the automotive industry, often requires one or more forming operations before a tube actually is hydroformed. Prebending is one of these forming processes used to prepare tubes for the so-called prebent tube hydroforming.
June 12, 2003 | By Atsushi Shirayori
For hydraulic tube bulging, direct pressure control is the most commonly used process. Pressure control allows engineers to determine the correct capacity hydraulic system and, more importantly, prevent tube rupture. However, inflow control, or control of the volume of fluid inside the tube, theoretically could be another viable hydroforming process. Finite element analysis has shown that inflow control could allow engineers to more accurately predict deformation behavior and therefore enhance the hydroforming process.
April 24, 2003 | By Gary Morphy
The last article in this series noted that variable periphery design, or cross-section expansion, often is thought to be the most important aspect of tube hydroforming design flexibility. Expansion in the hydroforming die commonly is assumed to be the most efficient and most effective method,...
March 27, 2003 | By Tom Driggers
Hydroforming is gaining ground in the manufacture of many automotive components,such as pillars, frame rails, and engine cradles. Automakers are finding hydroforming advantageous for forming many smaller parts also. The process is useful for manufacturing an automobile fuel filler tube, which is the expanded portion of a fuel filler assembly where a fuel nozzle is inserted.
October 24, 2002 | By Serhat Kaya
Passenger car fuel tanks have for many years been made out of plastic. To reduce MTBE leaks in the groundwater, the Department of Energy, The State of California, and the Western States Petroleum Association are studying material alternatives such as high-strength steel, stainless steel and aluminum gas tanks.
Comparing and correlating two tests, a common bench test (twist compression) and a straight-tube corner-fill test, simulate hydroforming to find the coefficient of friction.
October 10, 2002 | By Gary Morphy
It's difficult to overemphasize the importance of cross section expansion when you're talking about successful and innovative hydroforming of steel tubing. Overemphasizing one aspect of the tube hydroforming design process can take attention away from others and result in less than optimal design....
October 10, 2002 | By Shrinivas Patil
As tubular hydroforming becomes a competitive process for the mass production of automotive parts, a tube's material properties must be consistent. To predict variations in material properties, many tube producers use the uniaxial tensile test. Because the specimens for the tensile test are collected before a tube is bent and welded, they are not always accurate. To predict variations in tube property accurately, it should be tested under a biaxial state of stress.
September 12, 2002 | By Markus Erras
A new type of hydroforming press was recently developed for sheet applications. The new press incorporates data acquisition and control features for research purposes. Current press frame designs for tube and sheet forming are uneconomic for large forces. This press achieves a clamping force of 100 mN, which is absorbed by a single cast frame with a circumferential pretensioning system.
May 16, 2002 | By Gary Morphy
Design flexibility is something that all automotive designers want, but too often they lack a thorough understanding of what that means—what aspects of design flexibility apply to a certain part and their effect on cost. A methodology often is adopted when (or even before) a part development...
March 14, 2002 | By Nathan Dwyer
This article discusses an approach to predicting failure in hydroforming prebent aluminum tubes. While strains are well researched for stamping sheet, this type of knowledge is lacking for hydroforming tubular components. Because the strains are different—prebent hydroformed tubular parts experience stress in the axial direction during bending, then in the circumferential direction during hydroforming—new methods for predicting failures are necessary. Researching these methods adds to the knowledge base of hydroforming, helping the technology gain further acceptance in manfacturing.
March 14, 2002 | By Srikanth Kulukuru
This article discusses tests that are used to evaluate flow stress in tube and why the uniaxial test is not suitable for this application. It discusses a bulge test, which stresses the tube biaxially, including tooling, software, and analysis tools for evaluating stresses.