Lead screw, D in, Table 104 – Rockwell Automation Motion Analyzer Software User Manual
Page 181
Rockwell Automation Publication MOTION-UM004B-EN-P - October 2012
181
Sizing Your System
Chapter 2
2.3.2. Lead Screw
A lead screw is coupled to a rotary motor and causes relative linear motion
between a rotating screw and its non-rotating nut.
Figure 133 - Mechanism Type - Lead Screw
Enter the following parameters for lead screw mechanisms, if relevant.
Table 104 - Lead Screw Properties
Parameters
Description
Mechanism Type
From the pull-down menu, choose the mechanism type.
The Load, Stroke, Speed, and Acceleration values are calculated based on the parameters entered
in the previous Load and Profile tabs and displayed here for reference.
Lead Screw Parameters
(label 2 in
Lead
The distance that the slide moves per one full rotation of the screw shaft. Pitch is
sometimes used loosely to describe this parameter. Pitch is actually the distance
between adjacent threads and is equal to lead only for single start threads.
Inertia
(1)
The inertia of the lead screw in the event that the lead screw rotates and the nut
is stationary. Enter the inertia of the nut when the lead screw is stationary and
the nut rotates.
Pre Load
The friction torque produced by pre-loading the two nuts of a ball screw against
each other. This is done to reduce backlash and increase stiffness in the system.
Seal friction should be included in this value. This value can be obtained from the
manufacturer’s data and is normally quoted in data sheets.
Efficiency
The efficiency of the lead screw. This value is available from the manufacturer.
Plain Acme screw = typically 40…60%
Precision screw (with rolling elements) = typically 85… 90%
Slide Mass
The mass of the slide that travels along the lead screw. This mass is affected by
gravity if the inclination in the
on
is non-zero.
(1) Use the
to calculate the inertia value for your application, if the value is not readily available.