# 急問:施加一扭力於螺栓上，此時螺栓可產生多少推力？

(kgf)呢？

### 1 個解答

• 最佳解答

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：

2010-10-02 13:28:45 補充：

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

2010-10-02 17:27:23 補充：

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

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