A new wave of forging production equipment emphasizes availability and the demands of critical materials
By any standard, the first half of 2015 has delivered remarkable progress in new forming process developments. The latest: in July, Schuler Group introduced a drawing for producing aerospace parts in titanium, either by cold forming or hot forming.
While conventional deep drawing dies with widths of up to 1.6 m are used for the cold forming process, a specially designed heating chamber is installed in the press for hot forming. It heats the titanium blanks to 700-950°C before they are formed in the hot-deep-drawing die.
The press bed is equipped with water-cooling and a ceramic insulation layer for protection. Schuler succeeded in integrating the draw cushion with high-temperature-resistant pressure pins into the system. With the aid of the pressure pins – which are led through several temperature layers – the blank-holding forces can be set with particularly high accuracy.
In cold operation, the press has a slide force of 3,150 kN and a bed cushion force of 1,250 kN, compared to 800 and 250 kN in hot operation. The forming speed for the titanium parts ranges from 0.1 to 2.0 mm/sec for hot forming, and 5 to 30 mm/sec for cold forming.
At the same time, Schuler unveiled a hydroforming press for aerospace tubular structures, a monoblock press with two axial cylinders capable of 1,600 mt of press force and a dedicated water hydraulics system.
Aerospace titanium is the material involved in another recent development, an isothermal forging process for TiAl alloy turbine blades, to be designed and supplied by Siempelkamp for Leistritz Turbinentechnik GmbH. Two 8-MN systems will be supplied, one to start production in March 2016, the second in 2017.
Titanium aluminide (TiAl) alloys are intermetallic chemical compound that are high in density, lightweight, and heat-resistant. The material’s ductility has been a problem for product designers though, one that has begun to be address by aerospace (and automotive) designers only in recent decades.
As detailed by Siempelkamp, TiAl’s intermetallic structure is the basis for its high strength and excellent creep resistance at high temperatures. That, as well as the material’s lightness (the density is 4 grams per cubic meter) makes it well suited for aircraft engine components. The material provides the potential to reduce the weight of turbine blades for aircraft engines by up to 50%, according to the forging machinery developer; its strength-to-weight characteristics also provide a significant reduction of centrifugal forces within the aircraft engine.
Earlier this year, the focus of new production technology was on automotive products when Schuler started up a press for Hirschvogel Automotive Group in Denklingen, Germany. The machine, powered with 2,000-mt of force for forming shafts for transmissions, drivetrains, and engine parts, reportedly is the first of its size to feature Schuler’s ServoDirect Technology.
According to Hirschvogel’s works managers, Frank Dobus, “The ability to accurately control the slide speed means we can closely coordinate the forming and transfer processes and prolong die service life. The freely programmable slide movement also greatly facilitates machine set-up. And, in addition, we also expect the new machine to have much lower energy requirements.”
Servo drive technology has been established for forming sheet metal part, and last fall Schuler introduced the first linear hammer powered by servo technology at RUD-Schöttler, a forger in Hagen, Germany. On that machine, the drives improve the accuracy of the hammer movements over what is possible with hydraulic, pneumatic, or other power sources.
According to Schuler it is now equipping an increasing number of forging presses with ServoDirect Technology, including a 1,600-mt closed-die forging press and a 500-mt knuckle-joint press.