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close this bookShearing - Course: Technique of working sheet metals, pipes and sections. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 17 p.)
View the document(introduction...)
View the documentPreliminary Remarks
View the documentHints on Labour Safety
View the document1. Purpose of Shearing
View the document2. Tools and Machines
View the document3. General Construction of Shears
View the document4. Mode of Operation of the Shearing Process
View the document5. Shearing Techniques
Open this folder and view contents6. Sequence of Selected Shearing Operations

4. Mode of Operation of the Shearing Process

In shearing, two wedge-shaped shear blades closely pass by each other. The workpiece that is placed between the two shear blades is cut under continued effect of force. The shearing process is performed in 3 stages:

Notching

When the blades touch down, the material springs back a bit under the effect of force. As soon as its elastic limit has been overcome, the blades notch the workpiece.


Figure 17. Notching

1 upper blade, 2 notched sheet, 3 lower blade

Cutting

In further penetrating, the shear blades overcome the internal resistance of the metal structure and cut the workpiece.


Figure 18. Cutting

1 upper blade, 2 cut-in sheet, 3 lower blade

Tearing

The penetrating shear blades squeeze the material together between the blades, resulting in a material solidification. Since the blades are not able to further penetrate the material, they tear the residual material apart under continued effect of force.

These stages can be seen at joint faces of thick sheets.


Figure 19. Tearing

1 upper blade, 2 torn sheet, 3 lower blade


Figure 20. Sheared joint face

1 upper notch, 2 smooth cut face, 3 rough torn face, 4 lower notch