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Press series for hydro-forming

IHU hydraulic 4-column press forms heat exchanger 

Since its formation in 1960, S. Dunkes (Kirchheim/Teck) has been building hydraulic presses, and is one of the few mid-sized companies that  is also intensively involved with hydro-forming technology. The Swabian machinery builder underscores its more than 20 years of expertise in this field with a series of high-performing plans with closing forces ranging from 5000 kN to 30,000 kN. In addition to the strictly technical and functional capabilities of the 2, 3, or 4 column, or frame presses, the mid-sized company makes a compelling case specifically with respect to process know-how and engineering. This expertise is of vital importance during the conceptual design and fine tuning of the systems required for the total process: the high-pressure technology for forming pressures up to 4000 bar, the closing cylinders – including the ceiling systems to compensate the length change caused by the volume increase, the HFA technology (water-based flame retardant fluids), consisting of a water tank and filter systems and control technology, the PC control, and many others must be adjusted to the respective workpiece, or the corresponding material characteristics.


Due to the increasing part variety, die changes also need to be simplified with appropriate facilities. Of particular importance is the resistance of the sealing rails installed on the protective sleeves and other components against the aggressive HFA fluids (compressed water). Due to the complete supply of the IHU plant and the harmonised elements, cycle times between 15 and 40 seconds can be realized, depending on workpiece size and the degree of forming. The use of robots and material handling facilities enables a significant increase in plant productivity.


The significant performance capabilities in the IHU field, prompted a South-African company to retain Dunkes for the delivery of a plant to form the exchangers. In addition to the hydraulic 4-column press, type HS 4-IHU-2500, with a clamping force of 25 000 kN and several high-pressure intensifiers up to a forming pressure of 4 000 bar, the delivered scope  also included the water hydraulics,  the filter system,  and the die change facility. Before shipment, the plant was tested under series conditions for four weeks at the Kircheim  factory. The plant, which tips the scale at approximately 200 tonnes, was dismantled and shipped following customer approval. The order scope also included the logistics in South-Africa, the local installation of the plant, commissioning, and training of the operator staff by Dunkes employees.


The IHU plant has been working to the customer satisfaction since the beginning of this year. The experience of the mid-sized company, which was already demonstrated during the planning stage – the entire plant was planned and delivered in only nine months – also proved meaningful during the delivery and commissioning process. After four weeks, the forming plant was operational and transferred to the customer. Since then, it has been working defect-free in 3-shift operations and produces heat exchangers at a cycle time of approximately 40 seconds at consistent quality. At any time, the specialists in Kircheim can review the program currently in operation at the customer via modem, therefore having the ability to immediately intervene in case of a malfunction and to provide the local service staff with appropriate recommendations.

Dunkes hydro-forming press, HS4-IHU-2500, in a 4-column design to form heat exchangers.
Associated products