Please follow the detailed Help center instructions to transfer the files to supported eReaders. Service Service Contacting Schuler Service. The New Industrial Revolution. Low pressure tube hydroforming considered an inexpensive option for forming these advanced high strength steel. Please enter a search term. Web, Tablet, Phone, eReader.

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Explosive forming For large parts, explosive hydroforming can generate the forming pressure by simply exploding a charge above the part complete with evacuated mold which is immersed in a pool of water. The tooling can be much cheaper than what would be required for any press-type process. The hydroforming-into-a-mold process also works using only a shock wave in air as the pressuring medium. Particularly when the explosives are close to the workpiece, inertia effects make the result more complicated than forming by hydrostatic pressure alone.

Tube hydroforming[ edit ] In tube hydroforming THF there are two major practices: high pressure and low pressure. With the high pressure process the tube is fully enclosed in a die prior to pressurization of the tube. In low pressure the tube is slightly pressurized to a fixed volume during the closing of the die this used to be called the Variform process. Today it is mostly used in the automotive sector, where many industrial applications can be found.

In tube hydroforming pressure is applied to the inside of a tube that is held by dies with the desired cross sections and forms. When the dies are closed, the tube ends are sealed by axial punches and the tube is filled with hydraulic fluid. The internal pressure can go up to a few thousand bars and it causes the tube to calibrate against the dies.

The fluid is injected into the tube through one of the two axial punches. Axial punches are movable and their action is required to provide axial compression and to feed material towards the center of the bulging tube. Transverse counter punches may also be used to punch holes in the work piece at the end of the forming process. Designing the process has in the past been a challenging task, since initial analytical modeling is possible only for limited cases.

Often FEM simulations must be performed in order to find a feasible process solution and to define the correct loading curves: pressure vs. Bending is done sequentially along the length of the tube, with the tube being bent around bending discs or dies as the tube length is fed in.

Bending can be done with or without mandrels. This additional complexity of process further increases the reliance on FEM for designing and evaluating manufacturing processes. The feasibility of a hydroforming process must take into consideration the initial tube material properties and its potential for variation, along with the bending process, hydraulic pressure throughout the forming process, in inclusion of axial feed or not, in order to predict metal formability.

Process sequence in tube hydroforming of a t-shape with counterpunch Typical tools[ edit ] Tools and punches can be interchanged for different part requirements.

One advantage of hydroforming is the savings on tools. For sheet metal only a draw ring and punch metalworking or male die is required. Depending on the part being formed, the punch can be made from epoxy, rather than metal. The bladder of the hydroform itself acts as the female die eliminating the need to fabricate it. This allows for changes in material thickness to be made with usually no necessary changes to the tool. However, dies must be highly polished and in tube hydroforming a two-piece die is required to allow opening and closing.

Geometry produced[ edit ] Another advantage of hydroforming is that complex shapes can be made in one step. In sheet hydroforming SHF with the bladder acting as the male die almost limitless geometries can be produced.

However, the process is limited by the very high closing force required in order to seal the dies, especially for large panels and thick hard materials. Small concave corner radii are difficult to be completely calibrated, i.

In order to keep the die closing force under prescribed limits, the maximum internal fluid pressure must be limited. This reduces the calibration abilities of the process, i. Limits of the SHF process are due to risks of excessive thinning, fracture, wrinkling and are strictly related to the material formability and to a proper selection of process parameters e.

Tube hydroforming THF can produce many geometric options as well, reducing the need for tube welding operations. Similar limitations and risks can be listed as in SHF; however, the maximum closing force is seldom a limiting factor in THF. Metal hydroforming also allows for a smoother finish as draw marks produced by the traditional method of pressing a male and female die together are eliminated. While springback has long been a topic of discussion for sheet metal forming operations it has been far less of a topic of research for tube hydroforming.

This may in part be a result of the relatively low levels of springback naturally occurring when deforming the tubes into their closed section geometries. Tube Hydroformed sections by the nature of their closed sections are very rigid and do not display high degrees of elastic deformation under load. For this reason it is likely that negative residual stress induced during tube hydroforming might be insufficient to deform the part elastically after the completion of forming.

However, as more and more tubular parts are being manufactured using high strength steel and advanced high strength steel [13] parts, springback must be accounted for in the design and manufacture of closed section tube hydroformed parts.

Notable examples include: Sheet Hydro Forming[ edit ] Satellite antennas up to 6 meters in diameter, such as those used in the Allen Telescope Array. The process has become popular for the manufacture of aluminium bicycle frames. The earliest commercially manufactured one being that of the Giant Manufacturing Revive bicycle first marketed in Many motor vehicles have major components manufactured using this technology, for example: The technique is widely used in the manufacture of engine cradles.

The first mass-produced one was for the Ford Contour and Mystique in The Buick Regal and Oldsmobile Cutlass had hydro-formed instrument panel beams.


Fundamentals of Hydroforming

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