宋世傑 發問時間: 科學工程學 · 10 年前

急問:施加一扭力於螺栓上,此時螺栓可產生多少推力?

例:

螺栓材質 sncm21 回火45°HRC

螺栓牙峯直徑=Φ25.6mm

螺栓牙底直徑=Φ22.9mm

螺距5.08mm (5牙/1")

方形牙(90°)

當我使用扭力扳手,施加一個30kgf.m 的扭力於此螺栓時,此螺栓可以產生多少推力

(kgf)呢?

感謝!!

雙手奉上20點

1 個解答

評分
  • 10 年前
    最佳解答

    圖片參考:http://docs.engineeringtoolbox.com/documents/1308/...

    The effort force for a screw jack when neglecting friction can be expressed as F = Q p / 2 π R (1)where F = effort force at the end of the arm or handle (lb)Q = weight or load (lb)p = pitch distance or lead of thread in one turn (in)r = pitch radius of screw (in)R = lever-arm radius (in)Example - Screw jack without frictionIf the load on a screw jack is 200000 lb, the lever-arm is 20 inches and the pitch equals 1/8 inches, the effort force can be estimated asF = (200000 lb) (1/8 in) / 2 π (20 in) = 199 lbScrew Jack with FrictionFor motion in the same direction as the load (load assist the screw jack), the effort force can expressed asF = Q ( (2 π μ r - p) / (2 π r + μ p) ) (r/R) (2)where μ = friction coefficientFor motion in the opposite direction as the load (load assist the screw jack), the effort force can expressed asF = Q ( (2 π μ r + p) / (2 π r - μ p) ) (r/R) (3)

    2010-10-02 11:57:58 補充:

    不考慮磨擦力時:

    F = Q p / 2 π R

    公式中

    FR = 施加之扭力 = 30kgf.m = 217 in lbf

    Q = 產生多少推力 = ? lbf

    p = 螺距5.08mm = 0.2 in

    Q=2π FR/p = 2π 217 /0.2 = 6818 lbf = 3092 kgf

    不考慮磨擦力時:產生推力 3092 kgf

    2010-10-02 12:29:02 補充:

    http://www.engineeringtoolbox.com/screw-jack-d_130...

    2010-10-02 13:11:18 補充:

    http://nptel.iitm.ac.in/courses/Webcourse-contents...

    2010-10-02 13:24:43 補充:

    http://www.buyblueprint.com/article/48/

    2010-10-02 13:28:45 補充:

    http://tohnichi.jp/technical/pdf/02_bolt_tightenin...

    2010-10-02 17:27:23 補充:

    http://en.wikipedia.org/wiki/Leadscrew

    2010-10-02 17:35:02 補充:

    上面這答案, 3092 kgf, 好像不對???

    2010-10-02 19:16:30 補充:

    另一公式:

    扭力(螺絲進行方向與力的方向相同)

    T raise = 0.5* F * d* (p + π µ d) / (π d - µ p ) = 0.5*F*d* tan(Ø+λ )

    公式中

    T = 扭力 = 30kgf*m = 30000kgf*mm

    F = 推力

    d = 螺栓牙直徑,平均 24.25mm

    p = 螺距5.08mm

    µ = 磨擦係數

    Ø =磨擦角

    λ = 前置角 arctan (5.08mm / π24.25mm)

    計算結果如下

    µ =0,產生推力 37105 kgf

    µ =0.10, 14745 kgf

    µ =0.15, 11305 kgf

    µ =0.17, 10335 kgf

    2010-10-02 19:17:57 補充:

    上述公式在

    http://en.wikipedia.org/wiki/Leadscrew

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