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Sheet metal forming and Joining, Dividing by... - Coggle Diagram

- - - - Shockwave
    - - Expensive to make
  - - - Eccentric press
      - Knuckle joint press
      - Crank Press
      - Limited stroke press
        
        Stroke = limited
        
        Production speeds = high
        
        Ram speed = not cte
        
        Max. Force is for a specific part of your stroke
    - - Hydraulic press
        
        Max. Force in entire stroke.
        When press is down, there is a max force
        
        works by pushing and pulling oil
    - - Screw Press
        
        Short contact time
        
        Not a lot of energy
        
        Residual Energy must be absorbed
      - Hammers
        
        Drop Hammer: Uses gravity to deform
        
        Pneumatic:
        
        Hydraulic:
        
        Similar, but air is compressible and oil is not
        
        Counterblow: Tool is squished between upper hammer and lower hammer
        
        Good for Forging
        
        2 movements neutralize the empact force
        
        High deformation speed
        
        Hing deformation Energy
        
        High accuracy
  - - - Not suitable: product exceeds line of force distance diagram of machine
- - - - Large Aircraft parts
    - - Sheet is clamped
        
        Punch will move into material
      - Surface area = increased
      - Thickness = Decreased
    - - Material should have Large strain Hardening
        
        To prevent necking
    - - Long time to plan (To clamp material)
      - Loss of material
        
        Clamp material needs to be removed
  - - - Air Bending
        
        Elastic Springback
        
        Moving the punch
      - Rotary bending
        
        Small radiusses
        
        Hard to control friction (a lot of it)
      - Roll Forming
        
        Continuous rolling process
        
        Large product volume
        
        used also for tubes
        
        welded shut, after rolling
      - Edge Bending
        
        Geometry is fixed
      - Roll Bending
        
        3 forming rollers
        
        Large radiusses
      - Bottoming
        
        Large force - full surface Fully through
        
        Little springback
    - - Outside of sheet: Tensile Stress
      - Inside of sheet: Compression Stress
      - In middle: stress = 0
        
        Compression --> Tensile
      - Max. & Min. Bending radius
        
        Max: related to tensile strength of material
        
        Stress > Tensile Strength: Necking + eventually Tearing
        
        Min: Stress not high enough --> stays in elastic deformation area
        
        Need at least plastic deformation
      - Elastic Springback
        
        Material tries to restore to equilibrium
      - Bending force
        
        Applied force to reach min. Bending radius
    - - Adjust design to prevent:
        
        Wrinkling/buckling
        
        Impossible to create bend
        
        Fracture/ ripping
      - Order of Bending = Important
        
        Bending rules
        
        Principle Plane
      - Consider Elastic Springback
  - - - Workpiece = symmetrical along axis of rotation
      - Thickness = usually Constant
      - At undercut (extra piece, blocking the removal of the sheet): have a shared mandrell = make your mandrell (shape) out of different parts to remove individually
      - Mostly materials with small work hardening exponent (n)
        
        Because: pressure is applied, not tensile stress
        
        No problem with necking
      - Is done Hot and Cold
    - - Presses material on Mandrell + reduces wall thickness.
  - - - With Blankholder
        
        Sheet is held into place
        
        Has Friction
        
        Risk of Tearing
      - Without Blankholder
        
        For thick Sheets
        
        Risk of Wrinkling
    - - With a Die and a mold
        
        Die pushes on sheet
      - Bottom and walls = made from 1 sheet
    - - Under Blankhoder
        
        Axial Compression: By applying Blankholder Force
        
        Radial Elongation: Because of punch that pushes material inwards + Pulls material under the blankholder
        
        Tangential Compression: Because we go from large to small diameter
      - In the wall
        
        Axial Elongation:
        
        Because of movement of punch
        
        Tangential Elongation:
      - Blankholder:
        
        Too Low = Wrinkels
        
        Too High = Material Fracture
      - Deep Drawing
        
        Depends on geometry of Blank
        
        Depends on Geometry of Punch
        
        Depends on the Tensile Strength
    - - Shallow or Deep parts w/ simple shape
      - Shape: Often Cylindrical or rectangular
      - High Production Speed
      - Often Applied
      - High cost for machines and punch
      - Material: Good formable Properties
    - - Ironing:
        
        Smaller wall Thickness Same inner diameter
      - Explosive Forming
        
        Simples Shapes
        
        Lower tooling cost
        
        Larger Sheets
        
        High labor cost
        
        Small batch size
        
        Long cycle times
- - - - Cold rolling results in Anisotropy
        
        Material properties are not the same in all direction
        
        Opposite = Isotropic
        
        2 Types
        
        Planair Anisotropy (Rp): Differences in mechanical properties, in diff directions.
        
        Rp = 0, no differences --> most likely hot rolling
        
        Normal (Rn): Formability compared in surface area, + perpendicular to surface
        
        If Rn > 1, It is ideal for forming
- - - - Screw
      - Nuts and bolts
    - - Riveting parts
    - - Welds
  - - - High pressure + heat
      - Friction welding (using friction to make heat)
        
        Classical friction weldig
        
        2 Rotationally symmetrical parts
        
        1 rotates while pressured on the other
        
        Flash will be made,
        needs to be removed
        
        Can join materials with diff melting points
        
        Ultrasonic Welding
        
        Clean welds
        
        Relatively Low temperature
        
        No heat influence on other materials
        
        Ultrasonic Vibration (25-50 kHz)
        
        To create translating (horizontal) movement
      - Resistance welding (using current to make heat)
        
        Resistance spot welding
        
        1 Spot where current is applied
        
        Connected at 1 point
        
        Difference in Material/Thickness = possible
        
        Material = Electically conductive
        
        Copper
        
        Electrode = High melt point
        
        Resistance between workpiece and electrode = low
        
        Resistance projection welding
        
        Multiple spots at same time
        
        Product = prepared with pins
        
        To connect all at once
        
        Resistance seam welding
        
        Disk-Shaped electrode (Rotates)
        
        Follows a path (here it creates its welds)
        
        Flash welding
        
        Material = electrodes
        
        Can connect materials with diff properties
        
        Good surface quality = necessary
        
        How it Works
        
        Clamp workpiece between 2 electrodes
        
        Where resistance = highest
        Material is heated + melted until joint is created
    - - Electric Arc welding
        
        Consumable or Permanent Electrode
        
        How the meltpool = protected, is always different
        
        Heat source: Electric Arc
        
        Current is sent from electrode --> material
        
        Creates an Electric Arc in between
        
        Spark maintained by gasses + distance
        
        With coated electrode
        
        Consumable Electrode
        
        Metal Core with coating
        
        Can improve conductivity
        
        Keeps arc stabilized
        
        Current = either Direct or Alternating
        
        Hard to automate
        
        MIG, MAG and CO2
        
        Torch + electrode
        
        Through torch, gas is blown to the weld
        
        Long electrode wire = on a reel
        
        Can be automated
        
        Consumable
        
        MIG (Metal Inert Gas)
        
        Gas doesn't react with weld
        
        Gas: Argon or Helium mixture
        
        Good for: Non-Ferrous or alloy steel
        
        MAG (Metal Active Gas)
        
        Limited reaction with weld material
        
        Improves mechanical properties
        
        Gas: little bit of O2 or CO2
        
        Good for low-carbon Steels
        
        CO2
        
        MAG with just CO2
        
        Used to speed up process
        
        TIG welding
        
        Non-consumable Electrode
        
        Made of Tungsten
        
        Tungsten Inert gas
        
        Stable Arc with constant distance
        
        Materials: Ferrous and non-Ferrous
        
        Thinner parts (< 6mm)
        
        Use low speeds
        
        Alternative: Plasma Welding
        
        High voltage between electrode and workpiece
        
        Gas Becomes electrically conductive
        
        Plasma gas and protective gas ionized by arc
        
        Submerged Arc Welding
        
        Layer of flux (powder) is used to protect weld
        
        High currents (up to 2000A)
        
        For thicker sheets and cladding
        
        Ship hulls
        
        Fast process
        
        Only works in Horizontal position
        
        Otherwise Powder leaves
      - Thermochemical Welding
        
        Oxyfuel gas welding
        
        Burn Acetylene
        
        makes a flame --> heats material till melts and can connect the 2 materials
        
        For thin materials
        
        Welding rod necessary
        
        No power source, multifunctional
        
        Cheap and Slow
      - Radiation Welding
        
        Laser Beam Welding
        
        IR light: High energy density
        
        Fast
        
        Accurate and small
        
        Small heat affected zone
    - - Weld melts and solidifies which creates shrinkage
        
        Material doesn't shrink
        
        Difference in stresses --> changes the shape
      - heat affected zones can be too much
        
        which change the mechanical properties
      - Quality control:
        
        Rontgen research
        
        Non Destructive
        
        Qualification of Welders
        
        Experienced welders
        
        Test welding samples: By sawing them, look for weak points
        
        Destructive
  - - - Interlayer with limited strength
      - needs large surface area to join 2 parts
    - - Large area needed
      - Need surface treatment
        
        Makes sure, bonding between the product and interlayer is sufficient
      - No material properties change
      - Little internal stress
    - - Liquid solder flows between the 2 materials that need bonding
        
        This forms mixed crystals
      - Make sure that solder goes everywhere, even in narrow area
      - Clean area before soldering
      - Material:
        
        Solder (Tin and lead): Melt Temp < 450 C
        
        Brazing metal (Copper and Silver): Melt Temp > 450 C
        
        Stronger joints
    - - Interlayer = made of Organic Material or synthetic resin
      - Cohesion = Thin interlayer
        
        If thin: the layer can't move easily
      - To have best Adhesion (bonding)
        
        Clean & pre-process surface
        
        Wet the part
        
        Mechanical interlocking for porous materials
        
        For plastics: Part goes into solution (because of added interlayer)
        
        Then it re-solidifies
        
        Then you made a small layer = a mixture of interlayer and part
        
        Metals = mutual attraction of molecules (Van Der Waals - Forces)
      - Types of Adhesives:
        
        Physically cured:
        
        Moderate strength
        
        Dispersion Adhesive = solvant is water
        
        absorbed by part
        
        Contact Adhesive
        
        Solvant evaporates --> press 2 parts together
        
        Melt Adhesive:
        
        Liquify temporarily by heating
        
        Chemical cured adhesive
        
        Strength from polymerization
        
        Mainly used by plastics
        
        Interlayer = thermoplastics, thermosets
- - - - Sheet metal
  - - - Combination of machine and tooling
        
        Its a press that can punch
      - Has standard tooling
        
        Circle/ square/ triangle
      - Combination of: Punches and Nibbling
        
        Combination: square and circle give diff. contour.
        
        Many circles used to make a contour
      - Often Numerical Control Machines
        
        Has turret = multiple tools available in machine
      - Small batch sizes
      - Multiple products from 1 sheet
    - - Prevent as much scrap possible
      - sometimes by changing design
    - - Most accurate way to Punch/ Blank
        
        Because of counter pressure die
      - Upper pressure pad: has a V-groove
      - Smooth edge & True perpendicular hole
- - - - Leftovers can be reused
  - - - Influences Force:
        
        Length of contour
        
        Contour
    - - Lower speed = Nicer edge
      - Higher speed =
        More strain hardening,
        Larger Burr
        
        But, more production
    - - More friction = more Force required
  - - - Burnish Depth: Smooth cut
        
        Fracture depth: Place where fracture takes place
        
        Rollover depth: smooth rounded edge
        
        Burr height: At then end there is a small burr
      - Clearance: Space between punch and die
        
        Increased clearance = Edges become rougher
        
        No shearing, just a lot of tensile stress
        
        Decreased Clearance = Force to shear becomes High
        
        A lot of wear in tool
      - With flexible material: Burnish Depth increases, because of stretching
  - - - Moving knife: (Preassure pad necessary --> prevents tilting)
    - - Guillotine
      - Rod shears
    - - cut coils into smaller coils
- - - - Burns oxygen to cut material
      - Energy source: conditions -->
        
        Burning of Gas mixture
        
        Ignition temperature = below melting temp.
        
        Melting point of oxide = lower than original material
        
        Oxidation provides enough heat to maintain process
      - Creates rough surface finish
      - Continuous path cutting = possible
      - Dividing multiple layers = possible
    - - Strongly Ionized gas
      - Smooth & Accurate Surface
        
        Except when Turbulant
      - Reaches very high temp (30000 C)
      - High speed
      - Expensive
    - - Concentrated light source melts your material
      - Material can't have too high reflection of light
        
        Aluminium oxide and steel are very good
      - Done with oxygen (for reaction) or with inert gas (no reaction)
      - High Temperatures 10000 C
      - Very accurate
        
        Small width of cut
      - Small heat affected zone
  - - - High pressure with very high speeds
        
        400 Mpa
      - Cuts a lot of materials
        
        Paper
        
        Textile
        
        Plastic
        
        Steel