Shearing - Course: Technique of working sheet metals, pipes and sections. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 17 p.) 6. Sequence of Selected Shearing Operations (introduction...) 6.1. Cutting-in Sheets on the Tinners’ Snip 6.2. Cutting-off the Sheet on the Lever Shear 6.3. Cutting-off Angular Sections on the Lever Shear

Shearing - Course: Technique of working sheet metals, pipes and sections. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 17 p.)

6. Sequence of Selected Shearing Operations

The shearing operations are distinguished by differently handling the various shears.

6.1. Cutting-in Sheets on the Tinners’ Snip

- Scribe sheet as to accurately to size.

- Exactly set shear horizontally with 15° wide jaws onto the scribed line and align.

Figure 25. Tinners’ snip jaws correctly opened

- Cut in the sheet, but do not close the shear completely, otherwise the sheet is laterally torn at the end of cut.

- Continue shoving the shear by repeatedly opening the jaws.

- Again cut in the sheet up to the preset length.

6.2. Cutting-off the Sheet on the Lever Shear

- Scribe sheet as to accurately to size. In case of improper surface, punch-mark scribed line for control. Scrap side should be the right-hand sheet side, if possible.

- Check blade clearance on shear and re-adjust, if required. Shove sheet far into the shear blades, align scribed line with upper and lower shear blades - scrap side should be right-hand.

- Set hold-down bar on left-hand sheet surface and release hand-lever lockage.

- Pull hand-lever evenly downwards and follow up cutting effect and cutting direction of upper shear blade. As for longer cuts take heed of continuously feeding sheet metal.

Figure 26. Sheet correctly placed on the lever shear

1 workpiece side, 2 waste side

Do not completely lower the upper shear blade, as the shear blade end causes transverse cracks in the sheet!

- Completely cut the sheet through at the end - again lock the hand lever.

- Release toe dog and pull sheet out of the shear.

- Immediately throw the extremely bent waste material always rendering on the shear’s right-hand side (in line of vision to the shear) into the waste container.

Do not let cut-off and bent sheet pieces lie on ground - risk of getting injured

What is to be expected in the sheet metal when the shear blades are completely closed?
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Why should the scrap side of a sheet be always situated on the right-hand sheet side?
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6.3. Cutting-off Angular Sections on the Lever Shear

- Scribe length of angle section accurately to size. Scribe the line inside.

- Shove angular section through the shear’s angular-profiled blade (in line of vision to the shear).

- Align scribed line with upper shear blade.

- Release hand lever locking device.

- Pull down hand lever with a jerk.

- Pull angular section out of the shear. Throw waste par into the waste container.

Figure 27. Correct section knife for the shearing of angles

Why must steel sections be cut with section knives?
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What will happen when steel sections are cut on plane shear blades?
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Why must the hand lever of the lever shear be locked after the cutting operation?
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Why must waste material rendered during the shearing operation be immediately thrown into the waste container?
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