Text written in Basque and translated automatically by Elia without any subsequent editing. SEE ORIGINAL

Water to form

Water is one of the main causes of erosion in the same relief. It slowly transforms the landscape in its own way, although it affects it violently from time to time. The industry also uses water to shape the tools, but at high pressure and consequently in low-time jobs. This technique is called hydroforming or hydroforming and has been used in the industry for years. Mondragon Unibertsitatea is developing a new hydroforming system: high temperature has been added to high pressure.

At high pressure the water washes. The cleaning services of our municipalities use it to clean the streets and, on the other hand, many household appliances also work based on

water pressure systems. The industry is also well aware of the properties of water at high pressure, but uses it for another purpose: metal modeling. This technique is called hydroforming or hydroforming and has been used in the industry for years. Mondragon University, on the other hand, has challenged itself to improve this technique and is therefore developing a new hydroforming system.

One of the classic ways of shaping metal sheets is to place the sheet in a die and press it against the die by means of a punch. Typically, the sheet, die and punch itself are made of metal; but this is not always the case. One of the matrices and/or the punch may be liquid.

LUCIA ALVAREZ; Elhuyar Foundation: In the hydroforming or hydroforming technique, water or some other fluid is used to shape the parts. It is used to pressurize the liquid and push the sheet against the matrix. Thus, the sheet will take the form of a matrix.

The innovation of Mondragon Unibertsitatea is to carry out this technique in the heat rather than in the ambient temperature until now.

As such, hydroforming has long been used in the industry at room temperature. This is because, with the punch being liquid, smoother shapes are obtained, and the friction between the sheet and the punch disappears. In the case of hot working, these advantages would be increased.

ANDREA AGINAGALDE; Mondragon Unibertsitatea. At what temperature are you investigating and why?

Research is being done with aluminum and magnesium. Specifically, they discuss how and how these materials can be deformed before they are broken using hot hydroforming.

Aluminum, for example, is a lightweight material, but it is also very rigid and cannot be deformed very much; it breaks relatively easily. When heated, however, it becomes much more flexible, easier to grow. However, it has a limitation: above 300°C, the microstructure of aluminum begins to transform, losing the properties that make it interesting. For this reason, research at Mondragon University is carried out at around 260-280°C.

The hot embodiment of the invention also has effects with respect to the liquid used in hydroforming.

ANDREA AGINAGALDE; Mondragon Unibertsitatea. In hot hydroforming water or some other liquid is used; what and why?

In sheet experiments, the die gap is filled with oily fluid before the sheet is placed so that no air remains. If air remained between the fluid and the sheet, the result would be defective.

The upper die is then placed on top of the sheet.

After the two dies and the sheet have been prepared, the entire system is heated and the fluid is pressurized. In this way, the pressure of the fluid pushes the sheet and deforms it.

They are tested not only with sheets, but also with tubes. The machine differs both in the shape of the dies and in the manner in which the fluid is introduced, but basically does the same. The tube is inserted into the mold and the upper die is also placed, then the tube is filled with fluid and, with the system well heated, the pressurized fluid changes the shape of the tube.

However, in the case of pipes, it is necessary to provide a piston at the sides to exert a force also at the sides to contract the part. Unless the piece is pushed laterally, the contour in which the tube is deformed would be greatly thinned, as the surface área increases, and the piece would be weakened. Pushed laterally, the piece is contracted and the thickness of the metal is maintained.

The contractions, in these experiments, deform the sheets and tubes to the point of rupture in order to know the limits of the metal.

Jon Ander Esnaola; Mondragon Unibertsitatea. What is the purpose of breaking up?

To perform the tests to the point of rupture, open molds are used so that the metal does not have a stop. In addition, in the case of sheets, they record the process with video cameras inserted in the machine. A matrix is placed on the images in the computer, so that it is possible to easily follow the trajectory of each point of the sheet in three dimensions.

They use the painting of the sheet to locate the reference points.

Through these trackings, they analyze how the metal behaves at different temperatures, pressures, and pressurization rates. Precise temperature control, for example, is particularly important because it has a major impact on the deformability of the metal. It is often desirable to heat the areas that need to be deformed the most. They measure the temperature with sensors placed inside the dies.

When it comes to tube testing, they don’t record the process by video; they work with photos. The tubes have a lattice on their surface and, by comparing the initial and final photographs, follow the path of the lattice points.

The result of the hot hydroforming is remarkable; more complex shapes can be obtained in the pieces, even softer ones. The researchers believe that it will be useful to make any piece.

Jon Ander Esnaola; Mondragon Unibertsitatea. Is this an application for the shaping of any pipe or for those with special shapes?

Hot hydroforming is still in the experimental phase, but researchers at Mondragon University believe that by the summer they will be able to develop industrial applications.