New products of paper by hydromechanical paperboard forming
From the IGF project 17788 N entitled “Application of fluidic media based processes to deep-drawing of paper and paperboard” it is known that the hydrostatic pressure superposition during the active-media-based deep drawing of paper causes an extension of the process limits. However, compared to conventional deep-drawing, the process speed of the previous process designs was significantly slower. Therefore, the aim of this project was to combine the advantages of pressure superposition based on active media in terms of forming limits with the increased process speed of conventional deep-drawing in the process of hydro-mechanical deep-drawing.
To achieve this goal, a tool concept consisting of a solid deep-drawing punch and a fluid cushion was initially designed. By means of a pressure control it is possible to control the counter pressure in the fluid cushion and adjust it if necessary. Subsequently, the process limits could be determined in test series. In order to lay the foundations for the industrial establishment of the process, additional design strategies for the development of new paper products were developed with the aid of numerical simulations. For the numerical modeling of a material, material data describing the material behavior in abstract form is required. Based on the findings of previous research projects, specific material characterizations and tests on friction behavior were carried out. In this context, similarities and differences between the two types of material selected by the project committee (recycled and virgin fiber board) have been shown, particularly in terms of strength. Pronounced direction-dependent properties were observed in the tensile test. The fresh fiber board proved to be stronger in terms of its maximum load bearing capacity, but only slightly more elastic.
The data obtained were used to build numerical simulation models that are suitable for the design of tools and feasibility analyses. Here, a two-dimensional approach proved to be effective in making fundamental statements about geometric tool design, process parameters and process control. In alignment with experimental forming tests, the models were extended to three dimensions, tested and further optimized. It was shown that in particular the mapping of the direction-dependent properties and the behavior in the event of overstraining (damage) lead to an increase in the effort involved in data generation, modelling and calculation.
Based on the experimental findings and the simulation data, tools for hydro-mechanical forming of paper were developed. The results of the forming tests were used for comparison with the numerical data. Furthermore, a system for the introduction of steam has been integrated into the blank-holder area. This makes it possible to moisturize the forming material during the process. With the help of the steam, the resistance against wrinkling of the paper is reduced, which allows a significantly finer wrinkling pattern to be produced. In addition, the dimensional accuracy of the cup diameter can be improved by up to 79 %. The results thus reveal a great potential for the use of steam in the industrial forming technology of paper in terms of improving product quality and process control.
For further information, the final report can be downloaded here.
The IGF-Research Project 18331 N, supported by the German Pulp and Paper Association, is funded in the scope of the “Progamm zur Förderung der Industiellen Gemeinschaftsforschung” (IGF) via the German Federation of Industrial Research Associations (AiF) by the German Ministry for Economy and Energy as decided by the German parliament.
Furthermore, we thank all involved companies for the support of the research project “New products of paper by hydromechanical paperboard forming”:
- A. Obenauf GmbH & Co. KG
- Feinpappenwerk Gebr. Schuster GmbH & Co. KG
- Bene_fit GmbH & Co. KG /Gebrüder Dorfner GmbH & Co. KG
- Huissel Werkzeugbau GmbH
- Epurex Films GmbH & Co. KG
- Günter E. Meyer GmbH
- Schoeller Technocell GmbH & Co. KG
- Omya International AG