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Level 31

19 B - METAL BULK DEFORMATION - FORGING


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FORGING
COMPRESSION OF WORK BETWEEN TWO DIES, shaping the metal with a forging hammer of a forging press shaping the part following processes: [1] Open-die forging - compressing work between flat or almost flat dies, [2] Impression-die forging - forging work between shaped dies, [3] Flashless forging - compressing metal between dies without posibility for metal to escape in a form of flash. >>> OPEN FLASHLESS IMPRESSIONS GLOW BRIGHTLY
*Open-die forging
COMPRESSION OF PART BETWEEN TWO OPEN DIES, forging a desired geometry in a set of consecutive stages, hammering the workpiece time after time until it conforms to your expectations, an operation also known as upsetting or upset forging. UPSETTING OPEN DIES FORGE AN UPSETTING RAKE.
Analysis of open-die forging
Force equates to flow stress multiplied by area, the whole calculation corrected to accommodate no friction and cooling of metal at the areas where the metal contacts the die, the flow stress and area both increasing as the part gets squeezed, but in case of hot working, the flow stress equals to yield stress of then perfectly plastic material. $$\begin{array}[t]{l} Y_{f}=K\epsilon^{n}=K\left(ln\frac{h_{0}}{h}\right)^{n}\\ F=Y_{f}\cdot A=K\epsilon^{n}\cdot A=K\left(ln\frac{h_{0}}{h}\right)^{n}\cdot A\\ Correct\, for\, friction\\ \mathbf{F=K_{f}\cdot Y_{f}\cdot A}\\ K_{f}=1+\frac{0.4\mu D}{h}\\ F=\left(1+\frac{0.4\mu D}{h}\right)\cdot K\left(ln\frac{h_{0}}{h}\right)^{n}\cdot A \end{array}$$
Open-die forging practice
Human operator manipulates machine to forge simple shapes with favorable grain flow and metallurgical structure.
Grain flow
ALIGNMENT OF CRYSTALLINE STRUCTURE in the direction of working, a feature that increases the strength and durability of the forged part compared to cast or machined part. FLOWING GRAINS RESIST IMPACT AND FATIGUE IN LONGER LIVING CRITICAL COMPONENTS.
Other open die forging operations
Other open die forging operations include: [1] Fullering - reducing cross section with convex dies in preparation for shape forging, [2] Edging - reduction of cross section with concave dies, [3] Cogging - incremental reduction of thickness to make a bloom or a slab from an ingot. >>> FEC - FULLERING, EDGING, COGGING
*Impression-die forging
FORGING THE PART WITH A DIE CONTAINING THE NEGATIVE OF A FINAL SHAPE, usually in a few steps that gradually approximate the final shape, producing a part that requires some machining after forging
Flash in impression-die forging
NARROW FLASH FORCES HOT METAL INTO FINE DETAILS, building up pressure since it cools down and escapes through a narrow opening, leaving all the constrained and more malleable metal behind to fill the die details. COOLING FLASH HELPS DETAILED DIE.
Forces in impression die forging
FORCES CALCULATIONS IN IMPRESSION DIE FORGING are similar to regular forging $F=K_fY_fA$, yet with bigger corrections for flash and part complexity.
Precision forging
IMPROVED AND MORE EXPENSIVE DIE FORGING processes produce near net shape components, leaving only a bit of flash in the slower and more precise forging process, like the one they use to make golf clubs, slowly pressing the club head into a die just to sell it to rich idiots that will pay for anything that sounds better. SLOW AND PRECISE FORGE MAKES EXPENSIVE AND LUCRATIVE GOLF CLUBS.
*Flashless forging
HAMMER STRIKES METAL COMPLETELY ENCASED IN A DIE, without the possibility for flash to escape, the metal volume exactly and precisely and meticulously calibrated to fit into dies, since otherwise, if there is too much metal - the machine will break, if there is not enough - the part will be ruined, a process used to produce pretty precise parts, quite often classified as precision forging, a process used to make parts with fine details, like coins. CLOSED DIE IMPRINTS PRECISE COINS.
*Forging equipment
Forging equipment consists of forging machines such as hammers and presses, forging dies, and auxiliary equipment such as furnaces to heat steel, mechanical devices to load and unload the work, and trimming stations to cut away flash. >>> HumP DeaF TooL: HAMMERS, PRESSES, DIES, FURNACES, LOADERS, TRIMMERS
Forging hammers
HAMMER LIFTS AND DROPS ON WORKPIECE, impacting it with great force, the drop hammer's ram housing the upper portion of the die, the anvil containing the lower portion of the die, the ram driven either by gravity - a weight lifts and smashes the work, or by steam or air - steam pushes the piston that rams the workpiece, in both cases the drop hammer transmit great energy to the building's foundation. MIGHTY HAMMER SMASHES METAL AND SHAKES BUILDING.
Forging presses
PRESS APPLIES PRESSURE TO METAL, using mechanical and hydraulic means, the mechanical presses convert rotational motion of a motor into linear motion using eccentrics, cranks, and knuckle joints, thus having high forces at the bottom of the stroke, and hydraulic and screw presses apply constant force through out the stroke. >>> SMH: SCREW MECHANICAL HYDRAULICS
Forging dies
Design of the forging die must consider the following factors: [1] Parting line - location of parting line determines grain flow and flash formation; [2] Draft - only if the part is tapered, angled at around 3° for aluminum and about 5° to 7° for steel; [3] Webs and ribs - thin features parallel and perpendicular to parting line impede flow of metal the thinner they get; [4] Fillets and radii - small radii and fillets limit metal flow, large radii and fillets help metal flow. [5] Flash - flash formation causes pressure buildup in the die, thus pushing the metal into the fine details of the die, pressure controlled by design of land - the conduit for flash flow and gutter - the storage of excess metal. >>> PeDro ReaR Fuck: PARTING, DRAFT,, RADII, RIBS,, FLASH
Land and gutter
LAND CONTROLS CROSS SECTION OF FLASH FLOW, thus controlling the the pressure buildup in the part, and the gutter stores the excess metal. PRESSURED LAND CONTROLS SPACIOUS GUTTER.
FORGING RELATED PROCESSES
FEW OTHER FORGING RELATED PROCESSES utilize a similar, wondrously violent manner of beating metal into a submissive shape: [1] Upsetting and heading - punch beats inside a die to increase its diameter, in order to make bolt heads; [2] Swagging and radial forging - dies decrease diameter of rod; [3] Roll forging - forging part with rotating rolls; [4] Orbital forging - presses rotating cone into part; [5] Hubbing - makes molds by pressing hard hub into soft metal part; [6] Isothermal forging - heated die forges titanium to prevent oxidation; [7] Trimming - removal of flash by shearing it of from still warm part, shearing it of in a trimming press. >>> HiS ROpe HIT: HEADING, SWAGGING,,, ROLL, ORBITAL,,, HUBBING, ISOTHERMAL, TRIMMING
Upsetting and heading
PUNCH PRESSES CYLINDRICAL PART TO PRODUCE BOLT HEAD, the maximal length deformed in one blow is three times the stock diameter $ L_{\begin{array}{c} max\, deformation\\one\, blow \end{array}}\approx3\cdot D$ , a mass production operation, an operation in which a horizontal punch slams on the wire or tube to produce a bolt head.
Swagging and radial forging
DIES REDUCE DIAMETER OF TUBE OR ROD, creating tapers on tubes, cylinders, and rods, the dies rotating around the part in swagging or the work rotating in radial forging, producing tapered tubes or cylinders. ROTATING DIES FORGE TAPERED CYLINDERS.
Roll forging
SHAPED ROLLS FORGE THIN RODS, imparting a shape upon the work as it travels through the rolls, creating a stronger workpiece due to better grain flow that machining the rod or billet would produce. FORGING ROLLS SHAPE STRONGER BILLETS.
Orbital forging
ROTATING CONE FORGES METAL, compressing it with only with small part of its surface, thus reducing forces required to forge the part. ROTATING CONE FORGE SAVES ENERGY AND MONEY
Hubbing
HARDENED STEEL DIE MAKES MOLD OUT OF SOFTER STEEL, the die forcefully pushes down on the work, making an impression used as a injection molding or die casting mold, after the excess and bulging metal is machined away.
Isothermal forging
HEATED DIES SHAPE REACTIVE METALS, the dies heated to the same temperature as the titanium or supperalloy work reduce friction and forces during forging, a process quite often performed in vacuum to prevent rapid oxidation. SAME TEMPERATURE REDUCES FRICTION AND FORCES.
Trimming
PRESS REMOVES FLASH BY SHEARING IT AWAY, pushing the part through trimming dies to remove the bulging flash.