SheetMetal Forming Processes

1
Sheet-Metal Forming Processes
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Sheet-Metal Forming Processes
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Aluminum Two-Piece Beverage Cans

• FIGURE 7.77 Aluminum two-piece beverage cans.
  Note the fine surface finish. Source Courtesy of
  J. E. Wang, Texas AM Univerity.

4
Metal-Forming Process for Food and Beverage
Containers

• FIGURE 7.76 The metal-forming process used to
  manufacture two-piece beverage cans.

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Punching, Blanking and Shearing Operations

• FIGURE 7.8 (a) Punching (piercing) and
  blanking. (b) Examples of various shearing
  operations on sheet metal.

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Efficient Nesting of Blanks

• FIGURE 7.69 Efficient nesting of parts for
  optimum material utilization in blanking. Source
  Society of Manufacturing Engineers.

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Shearing

• FIGURE 7.4 Schematic illustration of the
  shearing process with a punch and die. This
  process with a punch and die. This process is a
  common method of producing various openings in
  sheet metals.

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Progressive Dies

• FIGURE 7.13 (a) Schematic illustration of the
  making of a washer in a progressive die. (b)
  Forming of the top piece of an aerosol spray can
  in a progressive die. Note that the part is
  attached to the strip until the last operation is
  completed.

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The Effect of Bending On Too Tight A Radius
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Minimum Bend Radii

• TABLE 7.2 Minimum bend radii for various
  materials at room temperature.

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Common Die-Bending Operations

• FIGURE 7.22 Common die-bending operations,
  showing the die-opening dimension W used in
  calculating bending forces. See Eq,(7.11).

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Presses

• Solid Gap Frame(150 tons)
• OBI
• Adjustable bed frames
• Turret Presses

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PressBrake 30 feet, 1250 ton Niagara Machine
and Tool Works
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Bending Operations In a Press Brake

• FIGURE 7.23 Schematic illustration of various
  bending operations in a press brake.

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Bead Forming

• FIGURE 7.25 (a) Bead forming with a single die.
  (b) Bead forming with two dies in a press brake.

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Bending

• FIGURE 7.15 (a) Bending terminology. The bend
  radius is measured to the inner surface of the
  bend. Note that the length of the bend is the
  width of the sheet. Also note that the bend angle
  and the bend radius (sharpness of the bend) are
  two different variables. (b) Relationship between
  the ratio of bend radius to sheet thickness and
  tensile reduction of area for various materials.
  Note that sheet metal with a reduction of area of
  about 50 can be bent and flattened over itself
  without crackling. Source After J. Datsko and C.
  T. Yang.

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Bend Allowance

• Unless specified otherwise, r t
• q positive included angle from flat
• k is a material constant

t
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Material is 0.050 Alum. Measurements are O.D.
Holes (6) are 3/32 dia, 1/4 from edge
3.600
2.050
1.25
.550
4.570
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Depth of Notch ________
.25
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Bend Allowance Calculation Methods
Outside Width
Height
r usually t
r
Flat Length 2(Height-r-t) Outside Width
2(tr) 2(Bend Allowance)
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Bend Allowance Calculation

• Determine The Bend Points

Bend Point Height-r-t1/2Bend Allowance
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Depth of Notch Height-t-rBend Allowance Need
To Leave Room For Over Bend
Flat Length 2(Height-r-t) Outside Width
2(tr) 2(Bend Allowance)
Bend Point
Flat Length
.25
Bend Point Height-r-t1/2Bend Allowance
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Deep-drawing Process

• FIGURE 7.50 (a) Schematic illustration of the
  deep-drawing process. This procedure is the first
  step in the basic process by which aluminum
  beverage cans are produced today. The stripper
  ring facilitates the removal of the formed cup
  from the punch. (b) Variables in deep drawing of
  a cylindrical cup. Only the punch force in this
  illustration is a dependent variable all others
  are independent variables, including the
  blankholder force.

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Explosive Forming Process

• FIGURE 7.42 Schematic illustration of the
  explosive-forming process. Although explosives
  are generally used for destructive purposes,
  their energy can be controlled and employed in
  forming large parts that would otherwise be
  difficult or expensive to produce by other
  methods.

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Roll-Forming Process

• FIGURE 7.27 The roll-forming process.

• FIGURE 7.28 Stages in roll forming of a
  sheet-metal door frame. In Stage 6, the rolls may
  be shaped as in A or B. Source G. Oehler.

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Fastening

• Riveting / Stitching
• Seaming /Crimping
• Welding Processes

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Examples of Rivets and Stitching

• FIGURE 12.48 Examples of rivets (a) solid, (b)
  tubular, (c) split (or bifurcated), and (d)
  compression.

• FIGURE 12.49 Examples of metal stitching.

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Designs Guidelines for Riveting

• FIGURE 12.58 Design guidelines for riveting.
  Source J. G. Bralla.

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Double-Lock Seam and Crimping

• FIGURE 12.50 Stages in forming a double-lock
  seam.

• FIGURE 12.51 Two examples of mechanical joining
  by crimping.

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Home Work

• Read
• http//www.thefabricator.com/ToolandDie/ToolandDie
  _Article.cfm?ID1747
• http//en.wikipedia.org/wiki/Sheet_metalCutting
• Do Sheet Metal homework located on Web CT, Print
  complete turn in next lecture.