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    Solving Session 1 Mech422

    Uploaded by

    Ismail Abou Zeid
    This document outlines 9 problems related to mechanical engineering problem set 1 on forming operations, rolling, and forging. Problem 1 asks to determine the amount of reduction in cross-sectional area for a stretching operation given strength and strain-hardening properties. Problem 2 asks to determine strength and strain-hardening exponent values based on given stress-strain data. Problem 3 asks to calculate minimum friction, exit velocity, and slip for a rolling operation reducing a steel plate's thickness.

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    Solving Session 1 Mech422

    Uploaded by

    Ismail Abou Zeid
    52 views2 pages
    This document outlines 9 problems related to mechanical engineering problem set 1 on forming operations, rolling, and forging. Problem 1 asks to determine the amount of reduction in cross-sectional area for a stretching operation given strength and strain-hardening properties. Problem 2 asks to determine strength and strain-hardening exponent values based on given stress-strain data. Problem 3 asks to calculate minimum friction, exit velocity, and slip for a rolling operation reducing a steel plate's thickness.

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    This document outlines 9 problems related to mechanical engineering problem set 1 on forming operations, rolling, and forging. Problem 1 asks to determine the amount of reduction in cross-sectional area for a stretching operation given strength and strain-hardening properties. Problem 2 asks to determine strength and strain-hardening exponent values based on given stress-strain data. Problem 3 asks to calculate minimum friction, exit velocity, and slip for a rolling operation reducing a steel plate's thickness.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    52 views2 pages

    Solving Session 1 Mech422

    Uploaded by

    Ismail Abou Zeid
    This document outlines 9 problems related to mechanical engineering problem set 1 on forming operations, rolling, and forging. Problem 1 asks to determine the amount of reduction in cross-sectional area for a stretching operation given strength and strain-hardening properties. Problem 2 asks to determine strength and strain-hardening exponent values based on given stress-strain data. Problem 3 asks to calculate minimum friction, exit velocity, and slip for a rolling operation reducing a steel plate's thickness.

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    © All Rights Reserved
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    SOLVING SESSION 1

    MECH 422
    FALL 2022
    Problem 1
    The strength coefficient = 240 MPa and strain-hardening exponent = 0.40 for a metal used in a forming
    operation in which the work-part is reduced in cross-sectional area by stretching. If the average flow stress on
    the part is 140 MPa, determine the amount of reduction in cross-sectional area experienced by the part.

    Problem 2
    The following stress and strain values were measured in the plastic region during a tensile test carried out on a
    new experimental metal: (1) true stress = 300 MPa and true strain = 0.27 cm/cm, and (2) true stress = 360
    MPa and true strain = 0.85 cm/cm. Based on these data points, determine the strength coefficient and strain-
    hardening exponent.

    Problem 3
    A 42.0-mm-thick plate made of low carbon steel is to be reduced to 34.0 mm in one pass in a rolling operation.
    As the thickness is reduced, the plate widens by 4%. The yield strength of the steel plate is 174 MPa and the
    tensile strength is 290 MPa. The entrance speed of the plate is 15.0 m/min. The roll radius is 325 mm and the
    rotational speed is 49.0 rev/min. Determine (a) the minimum required coefficient of friction that would make
    this rolling operation possible, (b) exit velocity of the plate, and (c) forward slip.

    Problem 4
    A 5.0 cm-thick slab is 25 cm wide and 3.6 m long. Thickness is to be reduced in three steps in a hot rolling
    operation. Each step will reduce the slab to 75% of its previous thickness. It is expected that for this metal and
    reduction, the slab will widen by 3% in each step. If the entry speed of the slab in the first step is 12 m/min,
    and roll speed is the same for the three steps, determine: (a) length and (b) exit velocity of the slab after the
    final reduction.

    Problem 5
    In the previous problem, suppose that the percent reduction were specified to be equal for each pass, rather
    than the draft. (a) What is the minimum number of passes required? (b) What is the draft for each pass?

    Problem 6
    A plate that is 250 mm wide and 25 mm thick is to be reduced in a single pass in a two-high rolling mill to a
    thickness of 20 mm. The roll has a radius = 500 mm, and its speed = 30 m/min. The work material has a
    strength coefficient = 240 MPa and a strain hardening exponent = 0.2. Determine (a) roll force, (b) roll torque,
    and (c) power required to accomplish this operation.

    Problem 7
    A hot rolling mill has rolls of diameter = 60 cm. It can exert a maximum force = 1780 kN. The mill has a
    maximum power = 75 kW. It is desired to reduce a 3.75 cm thick plate by the maximum possible draft in one
    pass. The starting plate is 25 cm wide. In the heated condition, the work material has a strength coefficient =
    140 MPa and a strain hardening exponent = zero. Determine (a) maximum possible draft, (b) associated true
    strain, and (c) maximum speed of the rolls for the operation.

    Problem 8
    A cylindrical part is warm upset forged in an open die. The initial diameter is 45 mm and the initial height is 40
    mm. The height after forging is 25 mm. The coefficient of friction at the die-work interface is 0.20. The yield
    strength of the work material is 285 MPa, and its flow curve is defined by a strength coefficient of 600 MPa
    and a strain-hardening exponent of 0.12. Determine the force in the operation (a) just as the yield point is
    reached (yield at strain = 0.002), (b) at a height of 35 mm,(c) at a height of 30 mm, and (d) at a height of 25
    mm. Use of a spreadsheet calculator is recommended.

    Problem 9
    A hydraulic forging press is capable of exerting a maximum force = 1,000,000 N. A cylindrical work-part is to be
    cold upset forged. The starting part has diameter = 30 mm and height = 30 mm. The flow curve of the metal is
    defined by K = 400 MPa and n = 0.2. Determine the maximum reduction in height to which the part can be
    compressed with this forging press, if the coefficient of friction = 0.1. Use of a spreadsheet calculator is
    recommended.

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