Hydroforming

Hydroforming isn't as mysterious as it seems. This technology area is full of articles, including case studies, on hydroforming sheet metal and tubular sections.

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Examining the effects of push assist on the formability of aluminum tubes

July 10, 2003

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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.

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Dealing with internal pressure in free hydraulic bulging

June 12, 2003

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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.

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Tube Hydroforming Design Flexibility—Part III

April 24, 2003

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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,...

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Fill 'er Up

March 27, 2003

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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.

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Automobile fuel tanks

Hydroforming of passenger car fuel tanks

October 24, 2002

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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.

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Material property variations in tubes used for hydroforming

October 10, 2002

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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.

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Tube Hydroforming Design Flexibility—Part II

October 10, 2002

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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....

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Analyzing tubes, lubes, dies, and friction

October 10, 2002

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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.

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Designing a hydroforming press for research, production

September 12, 2002

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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.

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Tube Hydroforming Design Flexibility—Part I

May 16, 2002

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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...

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Predicting failure in hydroforming prevent aluminum tubes: Strain variables require sophisticated analysis

March 14, 2002

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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.

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Determining flow stress of tubes

March 14, 2002

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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.

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Hydroforming machine

Hydroforming gains ground in Germany

January 24, 2002

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This article examines hydroforming in Germany, focusing on the advancement of the technology. It specifically discusses growing automotive uses, a new type of hydroforming press, material quality requirements, cost factors, new testing methods, and simulation software.

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How material influences bending for hydroforming

January 10, 2002

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The bending characteristics of a tube depend on the material it is made of. Exceeding the allowable limits of this deformation results in unusable parts. The author relates his company's examination and comparison of the bending of two different seamless, extruded tubes: aluminum alloy and steel.

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Hydroforming provides Rx for medical pumps

January 10, 2002

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This article relates how a Florida-based company used hydroforming to produce titanium housings for implantable pumps for a Massachusetts-based manufacturer.

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