CompMechLab Research Projects

Description of relief stamping method:

Elements used in relief stamping: a metal stamp with an engraved image, paper material or paperboard, a polyurethane plate. The relief image on the polyurethane is obtained by pressing the paperboard by the stamp into the polyurethane.
 

Fig. 1. Manufacturing scheme of the relief stamping process

Fig. 2. Photo of a stamp with a set of engraved test images

The stamping process is followed by a by-effect - tension of paper material (Fig . 3). In addition, as a result of created pressure elastic material "leaks" outside the stamp area and bursts the paperboard by the stamp perimeter (Fig. 4).

Fig. 3. The result of paperboard side tension during the stamping process

Fig. 4. The result of tension and breach by the stamp contour 

Modeling of the relief stamping process is done for two different metal stamps (Fig. 5). The large stamp is the one with three columns of type-setting elements: square, rectangular and hemispherical. The small stamp is the one with a single column of type-setting elements (rectangular). 

Fig. 5. Stamp profiles

The small stamp. Displacements distribution (Click to enlarge).

The small stamp. Von Mises stress distribution (Click to enlarge).

During the relief stamping process thinning of a perforated sheet occurs, which can lead to paper rupture. The paper thinning typical for the studied process is represented in Fig. 6. The initial (paper) thickness is equal to 0.1 mm. The most probable rupture zones are located in the areas of connection of the paper with side surfaces.  

Fig. 6. Variation of paper thickness (mm)

The large stamp. Displacement field (m). Paper sheet

The large stamp. Distribution field (m). Polyurethane base plate

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• Food, packaging

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