Tutorial: Engineering technology Topic: Flat forming - punching, bending Prepared by: Ing. Elena Nová Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/ je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.
Flat forming-punching, bending
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
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
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)
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.
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).
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!
Seaming is edge bending either manually or using flanging rolls.
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’.
Production of thin-walled tubes.
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