Load on Power Screw given Torque Required in Lifting Load with Acme Threaded Screw Calculator

Load on Screw Formula:

\[ W = \frac{2 \times M_{tli} \times (1 - \mu \times \sec(0.253) \times \tan(\alpha))}{d_m \times (\mu \times \sec(0.253) + \tan(\alpha))} \]

Torque for lifting load (M_tli):

N·m

Coefficient of friction (μ):

Helix angle of screw (α):

Mean Diameter of Screw (d_m):

Load on screw (W): N

1. What is Load on Power Screw Calculator?

Definition: This calculator determines the axial load that can be lifted by an Acme threaded power screw given the required torque and screw parameters.

Purpose: It helps mechanical engineers and designers calculate the load capacity of Acme threaded screws in lifting applications.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ W = \frac{2 \times M_{tli} \times (1 - \mu \times \sec(0.253) \times \tan(\alpha))}{d_m \times (\mu \times \sec(0.253) + \tan(\alpha))} \]

Where:

\( W \) — Load on screw (N)
\( M_{tli} \) — Torque for lifting load (N·m)
\( \mu \) — Coefficient of friction at screw thread (typically 0.15)
\( \alpha \) — Helix angle of screw (degrees)
\( d_m \) — Mean diameter of power screw (m)
\( \sec(0.253) \) — Secant of Acme thread angle (constant)

Explanation: The formula accounts for the torque required to overcome friction and lift the load in an Acme threaded screw mechanism.

3. Importance of Load Calculation

Details: Proper load calculation ensures screw mechanisms are designed with adequate strength and torque capacity for safe operation.

4. Using the Calculator

Tips: Enter the torque, friction coefficient (default 0.15), helix angle (default 4.5°), and mean diameter (default 0.046m). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is sec(0.253) used in the formula?
A: This accounts for the 14.5° thread angle of standard Acme threads (secant of 0.253 radians).

Q2: What's a typical coefficient of friction for Acme threads?
A: Typically 0.15 for steel screws with lubrication, but can range from 0.1 to 0.3 depending on materials and lubrication.

Q3: How do I measure the mean diameter?
A: It's the average of the screw's major and minor diameters, or twice the distance from thread centerline to bearing surface.

Q4: What affects the helix angle?
A: The helix angle depends on the screw's pitch and diameter. It's calculated as arctan(pitch/(π×mean diameter)).

Q5: Does this account for screw efficiency?
A: Yes, the formula inherently accounts for efficiency through the friction and angle terms.