Shear Cutting
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Shear Cutting Wolfram Volk and Jens Stahl Institute of Metal Forming and Casting, Technische Universita¨t M€ unchen, Garching, Germany
Synonyms Blanking; Cutting; Punching; Shearing
Die
cutting;
Piercing;
Definition Shear cutting is the separation of workpieces by two blades moving in opposite directions past each other (DIN 8588 2013).
Theory and Application Basics The shear cutting processes are part of the separation manufacturing processes, standardized in (DIN 8580 2003) and more precisely characterized in (DIN 8588 2013) as the mechanical separation of workpieces without forming shapeless matter. Here, shapeless matter refers to chips or grinding dust, for example. Some parts manufactured by shear cutting are displayed in Fig. 1.
Figure 2 shows a typical tool with sheet metal. A shear cutting tool consists of at least a punch and a die, also referred to as die plate. The punch and die plate move in opposite directions past each other and are, therefore, responsible for the cutting. On account of this, they are also referred to as the tool’s active elements. Both the punch and die need to possess cutting edges. These are usually sharp or manufactured with a small radius of approximately 15 mm. Bigger radii or a chamfer may be used instead of the radius in special cases. As illustrated in Fig. 2, the punch’s lower surface and the die’s upper surface are both flat and parallel. Therefore, the whole cutting edge operates from the beginning of the cutting operation. However, this is not a necessity. The geometry of the punch and die plate does not have to be identical: a sloped punch may be used together with a flat die plate, for example. The die clearance is the distance between punch and die plate, measured perpendicular to the area in which the cutting edge moves during the cutting process (DIN 8588 2013). It is common to specify the die clearance as a percentage of the sheet metal thickness. Usually, the die clearance ranges between 5 % and 12 % of the sheet metal thickness, depending on the workpiece material and the desired cut surface qualities, for example. A blank holder, in the case of fineblanking with an additional vee-ring (see Fig. 2 on the right), is used to improve the quality of the manufactured parts. It fixes the sheet metal by
# CIRP 2015 The International Academy for Production Engineering et al. (eds.), CIRP Encyclopedia of Production Engineering, DOI 10.1007/978-3-642-35950-7_16823-1
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Shear Cutting
Shear Cutting, Fig. 1 Parts manufactured by shear cutting (Courtesy of Feintool Technologie AG, Lyss (Switzerland))
Shear Cutting, Fig. 2 Basic terms of the shear cutting process (left) and the fineblanking process (right) according to (Schmidt et al. 2007)
Shear Cutting, Fig. 3 Open (left) and closed cut (right) together with piercing and blanking according to (DIN 8588 2013)
Shear Cutting
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pressing it against a stationary part before the cutting operation. Furthermore, it reduces warping of the sheet metal during the cutting operation by applying pressure on the workpiece, c
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