Ball Screw Spindle Ball Return Inserts for Compact Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ball screw drives with a spindle nut closed on one side face challenges in assembly and pre-installation of balls, as the assembly aid cannot be pushed out, and the ball return increases installation space.
Innovation Solution
A ball screw drive design with a ball screw spindle featuring a thread track over 360° and a circumferential wall with a ball return, incorporating inserts with a ball race that connects the thread track ends, allowing for a simple geometric depression and insert design, reducing friction and noise, and enabling a compact, one-sided spindle nut assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a spindle nut closed on one side is used, then the installation space is reduced, but the assembly process becomes impossible with conventional methods since the assembly aid cannot be pushed out
Solution Approach 1:
The ball return function is extracted from the spindle nut and relocated to the ball screw spindle itself. The circumferential wall of the spindle is designed to form the ball return, separating the ball circulation function from the nut structure. This allows the nut to be closed on one side while maintaining assembly capability through the open end of the spindle.
Solution Approach 2:
Instead of placing the ball return in the spindle nut as in conventional designs, the invention inverts the arrangement by placing the ball return in the ball screw spindle. This inversion resolves the contradiction by enabling both the closed nut design and feasible assembly process.
2Ease of manufacture
If the ball return is arranged in the spindle nut, then the assembly is simplified, but the installation space required increases
Solution Approach 1:
The ball return is merged with the circumferential wall of the ball screw spindle, utilizing the existing structural space of the spindle rather than requiring additional space in the spindle nut. This integration maintains assembly simplicity while reducing the overall installation space requirement.
3Ease of manufacture
If pre-installation of balls on the ball screw spindle is attempted, then assembly is simplified, but the ball return in the spindle nut cannot be filled with balls
Solution Approach 1:
The ball return is extracted from the spindle nut and placed in the spindle, allowing balls to be pre-installed on the spindle and then circulated through the ball return formed in the circumferential wall. This resolves the contradiction by enabling both pre-installation and proper ball return functionality.
Data Source
AI summary
An actuator assembly comprises a ball screw drive having a ball screw spindle rotatably mounted about a spindle axis, on which a spindle nut is received, and a thread track on an outer circumferential surface of the ball screw spindle, has a portion of a ball return on a circumferential wall of the ball screw spindle, which return connects a beginning and an end of the thread track to one another. At the beginning and at the end of the thread track, an insert is inserted in which a ball race is formed, which is part of the ball return. The inserts are arranged such that each end of a ball race adjoins a portion of the ball return and another end adjoins a beginning of a thread track or an end of the thread track. In a section perpendicular to a spindle axis, an angle of the ball race to a tangent to the thread track at an adjacent beginning or end of the thread track is greater than 90° in a central portion between the first and the second end of the ball race. To determine the angle, a side of the tangent on which a portion of the thread track directly adjacent to the beginning or the end lies is selected. To produce the ball screw spindle, a channel of the ball return is introduced into the circumferential wall, a thread is introduced into an outer circumferential surface of the ball screw spindle, and in each case one depression is introduced into the outer circumferential surface at the beginning and at the end of the thread track, and inserts are inserted into the depressions.