forming.ppt

Forming ProcessesForming Processes

GMP

Metal Forming/Press Operations

Forming processes are one of the most popular means of producing high volume products. Examples include appliance, aircraft, and automotive industries. – Major Reasons:

» Production costs are low

» Well suited for high production applications

» Process capabilities

» Processes are built into tooling

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Tools

One of the basic tools used in these processes is a punch & die.– A punch is the portion of the tool attached to the ram of

the press and is inserted into the die.

– A die is usually the stationary portion of the tool attached to the press bed. It has a cavity to accept the punch.

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Tools

Punch & die

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Tools

A progressive die is a tool capable of performing several operations from raw material to final product. These dies can be made from catalog items and divided into removable sections.

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Tools

Die alignment and clearance– Uniform clearance

– General rule - 5-7% material thickness

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Tools

Punch & dies are capable of performing the following examples of cold working(CW) operations:– Blanking - cutting desired shape from strip, burrs left

on strip

– Piercing - leaving desired shape on strip, burrs on scrap

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Tools

Punch & die capabilities continued:– Forming & Bending

– Shearing

– Ironing

– Drawing

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Process Capabilities

Blanking vs. Piercing

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Tools

Forming & Bending

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Tools

Shearing

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Tools

Ironing

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Process Capabilities

Drawing

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Calculating Pressure for a Process (Tons)

General formula for a hole– Diameter of hole x Thickness of material x Ultimate

Tensile Strength (UTS) = Pressure in Tons

– Guidelines» Mild Steel = 80 - 60,000 psi, Brass = 60,000 psi,

Bronze = 40,000 psi, Copper = 30,000 psi

Alum = 20,000 psi

Example– 2” dia. hole in ¼ steel plate

» 2 x .250 x 80= 40 tons

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Calculating Pressure for a Process (Tons)

General Formula - Profile – P= (L x 1/3) x material thickness x 60 (UTS)

– Example = Punch a 1”x 2” rectangle in ¼” brass» P= (6 x 1/3) x .250 x 60 = 29.7 ~ 30 tons

Machinery’s Handbook 23rd Edition

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Progressive Dies

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Progressive Dies

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Machine Tools- Presses

Classification– Manual

» Foot operated

– Light work -shearing

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Machine Tools- Presses

Mechanical – Max pressure near bottom of stroke

– Faster motion

– Operations - cutting, shallow forming, drawing, and progressive die operations

– Limitation - length of stroke set by design of mechanism = less flexibility

– Capacities up to 6,000 tons

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Machine Tools- Presses Mechanical Press Drive Mechanisms

» Crank = Simple design - used for piercing, blanking, and drawing operations

» Eccentric/Cam = Short ram stroke which provides a dwell a bottom of stroke

» Knuckle Fast action and high mechanical advantage Applications include coining and sizing

» Toggle = Drawing presses to move the blank holder

» Screw = Slow action

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Machine Tools- Presses

Hydraulic– Motion as a result of piston motion = longer or variable

stroke lengths can be programmed (within limitations of the piston).

– Steady pressure for operations such as deep drawing

– Single-slide

– Multiple-slide

– Capacities up to 50,000 tons

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Machine Tools- Presses

Frame classification– Gap

» Open arrangement of press frame

» Excellent clearance around dies

» Can handle long and wide parts

– Arch» Lower portion of press near the bed is wide to accommodate

large sheet material

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Machine Tools- Presses Frame classification continued:

– Straight side» Strong frame design—heavy loads are taken up in vertical

direction of massive frame

» Less of a tendency for punch & die to misalign

– Horn» Heavy shaft projecting from frame

» Used primarily for cylindrical work involving seaming, flanging, riveting, and embossing

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Machine Tools- Presses

Frame classification continued: – Inclined

» Vertical design can be tilted back to allow parts and scrap to slide out

» Used on parts involving bending, piercing, blanking, etc.

– Turret Presses» Production of sheet metal parts having a variety of patterns,

holes, cutouts, etc. in various sizes

» Current presses are CNC controlled and combined into “machining centers”, capable of laser, forming, and water-jet operations.

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Machine Tools- Presses

Frame classification continued: – Four Slide

» Complex forming of small to medium size parts

» Machine Basics 4-slides at 90 degrees controlled by cam to progressively

move through a cycle to achieve a final part Can be “tooled” with punches, cut-off tools,

lifting/shifting tools, and welding systems.

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Machine Tools- Presses

Frame classification

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Machine Tools- Presses

Accessories