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Advantages of Press Forging over Drop · PDF file17 Forging Advantages of Press Forging over Drop Forging - Press forging is quieter than drop forging. - Press forging is faster (one

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  • Forging 17

    Advantages of Press Forging over Drop Forging

    - Press forging is quieter than drop forging.

    - Press forging is faster (one operation).

    - Alignment of the two die halves can be easily maintained.

    - Structural quality of the product is superior.

    - More accurate parts are obtained.

    Forging 18

    Machine Forging

    - The quality of the forging is better.

    Advantages

    Limitations

    - Not convenient for heavy job, due to handling difficulty.

    - Forging machines have a higher productivity and their maintenance is much cheaper. - The upsetting process can be automated.

    - Intricate, nonsymmetric jobs are difficult.

    - The maximum diameter is limited to 25 cm.

  • Forging 19

    Die Cavity Design FactorsDie Cavity Design Factors

    1. Draft

    3o - 7o for external surfaces

    5o - 10o for internal surfaces

    1o if automatic ejectors are employed

    Is the angle of taper put on all sides to facilitate its quick removal from the die cavity after forging.

    Forging 20

    2. Fillet and Corner Radii

    Die Cavity Design FactorsDie Cavity Design Factors

  • Forging 21

    - Straight die - Simple locked die - Compound locked die - Counter locked die

    3. Parting Line

    Die Cavity Design FactorsDie Cavity Design Factors

    Forging 22

    4. Shrinkage and Die wear

    For steel, shrink allowance is about 16 mm per metre.

    For forging weight up to 4.5 kg., die wear allowance is 0.4-0.8 mm.

    For forging weight 9 kg.-22.5 kg., die wear allowance is 1.6-2.4 mm.

    Die Cavity Design FactorsDie Cavity Design Factors

  • Forging 23

    5. Mismatch

    6. Finish Allowance

    Die Cavity Design FactorsDie Cavity Design Factors

    Forging 24

    Force - Travel Diagram Basic types of Material Flow

    Closed Die Forging

  • Forging 25

    Forging 26

    Flash Design

    Flash thickness - s Flash land - b Die-land Ratio - b/s

  • Forging 27

    sA0.015 s

    1. Bruchanov and Rebelski

    b/s from table 13.8

    Determination of Die Land Ratio

    2. Voigtlander

    00.016d s

    0d63

    sb

    Determination of Die Land Ratio

    Forging 28

    3. Neuberger and Mockel

    4. Vieregge

    51

    0

    d0.017d s 0

    3 h0 drhdd30

    sb

    020 2/21

  • Forging 29

    mA = mE+mG+mZ mA - mass of initial stock in kg. mE - mass of forged part in kg. mG - mass of flash material mZ - mass of fiery particles

    mA = W. mE

    Ref. - H.Tschatsch, Praxiswissen Umformtechnik, Vieweg, 1997. (in German)

    Initial Stock Size

    Forging 30

    Kf1 = resistance to deformation at 1 s-1

    Stress, Force and Work - Strain rate

    0hV

    - Resistance to deformation m

    fk f1k

    - Resistance to deformation at the final stage fkY wek

    - Maximum Force wed kA F

    - Work F

    fhm kV W

    Average strain

    0

    Vn hAd

    hm

  • Forging 31

    Example

    Forging 32

    New Trends in Forging Technology

    1. Liquid forging (THIXO FORMING)

    2. Isothermal forging

    3. Powder forging

    4. Orbital forging

    5. Incremental forging

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