NKK Establishes Integrated System for
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| Example of tube-hydroformed auto part (differential case) |
NKK has established a fully integrated system for tube-hydroforming auto parts. The NKK system extends from prototype development through mass production of tubular hydroformed parts for automakers and auto parts manufacturers. The tube-hydroforming system joins NKK's recently established tailor-welded blank (TWB) sheet processing system, which also was developed for the automotive industry.
Tube-hydroforming is an inner high-pressure forming method to shape steel tubes by bulging them with water. Unlike conventional methods, in which several parts are press-formed and welded together to make products, tube-hydroforming can create tube products in fewer steps.
Today's auto parts make greater use of closed-section structural parts to reduce weight and achieve the rigidity required for collision safety. At the same time, auto parts must also conserve resources and reduce costs. TWB sheet technology and tube-hydroforming technology offer potential solutions to these issues.
Tube-hydroforming technology consists of several unique combined processing techniques, including:
- Preliminary forming to create deformed closed-section shapes with bends by means of complex bending and die pressing
- Inner high-pressure forming by using product-shape section dies, which corresponds to conventional bulge forming
- Die-less punching carried out in liquid-pressure forming dies.
The design of lightweight, rigid, collision-safe auto parts requires a combination of the most suitable materials and the most suitable processing techniques and forming conditions. NKK has conducted research into hydroforming and secondary processing of electric-resistance welded pipes since 1994. It has recently extended its research program to include cooperative projects with Japanese universities. These basic research activities, together with the technical support provided to NKK customers, have enabled the company to accumulate the expertise to organically link four essential technologies, i.e. materials designing, forming processing, numerical analysis, and prototyping technology that includes die designing.
Use of tube-hydroformed and secondary-processed parts by automakers is rapidly increasing. In response, working with a domestic hydroformed parts manufacturer, NKK has decided to apply its integrated technologies in the installation of a new 1,000Tf hydroforming press, suitable for all types of hydroformed parts studied thus far. The installation of the new equipment will give NKK the first integrated tube-hydroforming development system, capable of handling all steps from process design, prototype development through mass production, in Japan's steel industry.
The tube-hydroforming system, together with the TWB system, paves the way for what NKK refers to as "Early Vendor Involvement," in which the company is involved from the initial stages of automotive design, helping to shorten designing periods and optimize materials. NKK looks forward to actively proposing solutions that address the needs of automakers and offer the market more value-added tubular products.
