2. Tutorial: Engineering technology Topic: Flat forming - punching, bending Prepared by: Ing. Elena Nová Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002 je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.

3. Flat forming-punching, bending

4. 3.Punching – stamping sheets are pierced by shearing (die) cutter. Its main parts are blanking punch and punching / blanking die. Blanking punch- moving part of tool Punching die- stationary part

5.  Cutting clearance – between blanking punch and punching die is axial clearance. If too big cut is rough with tear edges.  Clearance should be 0,5% of sheet thickness. Schema of cutting using cutting tool (SK- cutting punch, SC- cutting die)  ms=cutting clearance

6.  Simple cutting tool  First tool is simple cutter designed for one operation.  Strip position is secured by solid stop, shift by one step (size of product plus allowance)

7.  With big and series production are used progressive tools.  Shift of strip is usually from right to left.  Right (small) circular blank  falls to waste, from the left  part of tool falls finished  product – washers.

8.  4. Bending is a forming process where usually is material permanently deformed at different bend angles with smaller or bigger edge radius.  For bending are use tools named – bending dies (roll and die).

9.  Bending principles  At bending, inner part has ‘compression and outer side traction stresses generating plastic deformations. If the worked material is not sufficiently ductile cracks can develop on the outer surface!

10.  Seaming is edge bending either manually or using flanging rolls.

11.  Roll-bending is bending between rolls.  It is used at production of cylindrical or conical tubes, casing jackets and even plates 30mm thick. Thicker plates are usually ‘hot bended’.  Machines used for this process are called ‘bending rollers’.

12.  Production of thin-walled tubes.

13.  http://coptel.coptkm.cz/index.php?action=2 &doc=20458&docGroup=4913&cmd=0&inst ance=2