Metal Forming Operations: Presses and Hammers Overview

FORMING OPERATIONS PERFORMED ON PRESSES AND HAMMERS

Operation Definition Sketch Applications Open Die Forging Forming by uniaxial compression between flat parallel plates (dies) Discs or blanks used as preforms. Very large shafts or forgings of simple shape Forming by uniaxial compressive force using dies with cavities which control lateral flow Shaped parts small to medium size such as connecting rods, handles, levers, gear blanks Closed Die Forging Upsetting A special type of closed die forging operation on bars in which a longitudinal force causes a local flow Heads on bolts, valves, Flanges and shoulders on shafts Forward Extrusion Forming by axial flow of a billet through a die orifice in the direction of an applied compressive force Regular or irregular structural shapes such as window moldings, angle sections, circular or irregular tubing

Operation Definition Sketch Applications Back Extrusion Forming by axial flow of a billet through a die orifice opposite to the direction of an applied compressive force Regular or irregular structural shapes, tubes for grease and cosmetics Coining Shallow configurations on flat objects, such as ornamental designs or structural ribs and bosses Special type of closed die forging operation in which the lateral surfaces are restrained resulting in a variable thickness and a well- defined imprint of the die faces Breaking (Bending) Forming of structural shapes such as angles and channels by bendin sheets or plates in a long press called a brake Structural shapes such as automobile and truck chassis. Angle and channel sections having large moment of inertia to weight ratio Hydroform (Guerin Process) (Rubber Punch) Bending or drawing operation in which either the punch or the die is a piece of constrained rubber Low quantity of parts that could be made by drawing

Operation Definition Sketch Applications Swagging Flaring ends of tubes, reduction of tube or shaft diameter Forming operation in which the diameter of bars or tubes is changed by repeated blows of radially actuated shaped hammers Staking Forcing a shaped punch into the top of a projection to complete a riveting operation As a substitute to drilling and riveting Shearing Rapid method of cutting bar stock or plates to length A material separation operation using two knife blades or a punch and die wherein the material deformation is localized and due to shear forces Hobbing (Hubbing) Forming a very smooth, accurately shaped die cavity by pressing a hardened punch into a softer metal die block Making many duplicate cavities, e.g. Plastic molds for molding typewriter keys, plastic wall tile

Operation Definition Sketch Applications Embossing Forming a design on thin materials by raising or lowering portions of the material by localized bending Forming ribs to increase rigidity. Making ornamental or communicative designs Drawing (Deep, Cup) Cups, shells, short tubes, automotive bodies, gas tanks, appliance covers Forming by pushing a formed punch against a flat sheet and forcing it over a shaped die- edge into the die cavity to take the shape of a recessed vessel. Ironing For thinning and sizing walls of predrawn parts Forming by reducing the wall thickness of deep drawn parts by forcing them through a die with a punch wherein the clearance is les than the original Wall thickness Sizing Finish forming operation, usually done on a preformed parts, in closed dies to obtain very accurate dimensions Accurate control of height or area of a formed part such as bosses

Operation Definition Sketch Applications Blanking A material separation process using a punch and die to shear a useful blank from a thin piece of material Making discs, washers or flat blanks which may be drawn afterwards Piercing A material separation operation using a punch and die to shear a hole in a thin piece Rapid method of making holes or slots in a part

FORMING OPERATIONS PERFORMED ON ROLLS

Operation Definition Sketch Applications Rapid method of producing bars of uniforms cross section Rolling Forming operation on cylindrical rolls wherein the cross sectional are of a bar or plate is reduced with a corresponding increase in length Rapid method of forming long lengths of tubes or structural shapes Roll Forming A continuous bending operation generally performed on originally coiled strip material and resulting in long shaped sections such as angles, channels and tubes Forge Rolling A closed die forging operation in which the die cavities are machined in the periphery of cylinders Similar to closed die forging except longer parts can be forged For low production forming since cost of tooling is low Power Spinning Forming of a conical part from a disc in which the diameter does not change by progressively forcing the disc against a conical mandrel by means of a small roller moving from the center out

Operation Definition Sketch Applications To straighten sheets that have been rolled Roll Straightening Straightening of a bar or plate by passing it through a series of rolls which are not all in the same plane, causing a material to be bent so that it is straight after the bending forces are removed To originate holes in seamless tubing Tube Piercing Tube piercing is a Rolling process in which a solid cylindrical bar is formed into a rough seamless tube by means of two conical rolls oppositely skewed a few degrees from the axis of the bar Thread Roling A plastic deformation process in which threads are formed on a cylinder that has an original diameter equal to the final pitch diameter To form threads by plastic flow rather than machining. Gear teeth and splines can be formed by a similar process

FORMING OPERATIONS PERFORMED ON DRAW BENCHES

Operation Definition Sketch Applications Wire or Bar Drawing Reducing the diameter of a bar or a wire by pulling it through a tapered orifice in a die Forming small cross sectional parts of uniform cross section and close tolerance Tube Drawing Reducing the Wall thickness of a tube by pulling it simultaneously over a mandrel and through a die orifice Forming close tolerance tubing Bending I or L sections to small radii Stretch Forming Simultaneously stretching and bending, over a die, a bar or a plate that would fail by compressive buckling if bending alone was attempted Stretcher Leveling Straightening a sheet or plate by performing slight tensile deformation Straightening sheets or plates previously rolled