Forming Processes

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Forming Processes

• General Manufacturing Processes Engr.-20.2710
• Instructor - Sam Chiappone

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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 1x 2 rectangle in ¼ brass
• P (6 x 1/3) x .250 x 60 29.7 30 tons
• Machinerys 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 designheavy 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