Linear Slider Preload Structure for Backlash-Free Lead Screw Drives
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Solution Overview
Problem
Backlash occurs in linear drive mechanisms due to clearances between the lead screw and nut or guide shaft and guide hole, leading to unreliable slider movement.
Innovation Solution
A linear drive device with a lead screw and guide shaft positioned eccentrically, featuring a slider with a guide hole and nut, and employing biasing means and rolling elements to apply and receive reactive forces, thereby suppressing backlash by ensuring proper alignment and preload between the lead screw, nut, and guide shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a linear drive mechanism uses a lead screw and nut with clearances, then the structure is simple and easy to manufacture, but backlash occurs in slider movement
Solution Approach 1:
The biasing means applies a preliminary biasing torque to the slider in advance, creating a pre-load force that eliminates clearances between the lead screw and nut, and between the guide shaft and guide hole. This preliminary anti-action prevents backlash before it can occur during operation, while maintaining the simple lead screw-nut structure.
Solution Approach 2:
The rolling element is positioned between the traveling surface and slider to receive and transmit the biasing torque, creating a preliminary mechanical action that maintains constant contact pressure. This preliminary action ensures that the slider remains firmly engaged with the lead screw and guide shaft throughout operation, preventing backlash without complicating the basic structure.
2Device complexity
If a linear drive mechanism uses a lead screw and nut with clearances, then the device complexity is low, but backlash occurs in slider movement
Solution Approach 1:
The biasing means provides a preliminary counteracting torque that eliminates clearances in the lead screw-nut and guide shaft-guide hole interfaces. This approach maintains low device complexity by using a simple spring or actuator mechanism while achieving high reliability through the pre-applied biasing force that prevents backlash.
Solution Approach 2:
The rolling element acts as an intermediary between the biasing means and the slider, transmitting the biasing torque efficiently. This intermediary component allows the system to achieve high reliability by maintaining constant contact pressure without requiring complex direct coupling mechanisms, thus keeping overall device complexity low.
3Reliability
If biasing means applies biasing torque to the slider, then backlash is suppressed, but the device complexity increases
Solution Approach 1:
The rolling element serves as a simple intermediary that translates the biasing torque into effective pre-load forces at the lead screw-nut and guide shaft-guide hole interfaces. This intermediary approach achieves backlash suppression through a single, simple component rather than requiring complex multi-component biasing mechanisms, thus minimizing the increase in device complexity.
Solution Approach 2:
The biasing means is designed to perform multiple functions simultaneously: applying biasing torque to eliminate clearances, maintaining constant contact pressure, and working through the rolling element to distribute forces evenly. This multi-functionality reduces the need for separate components for each function, thereby limiting the increase in device complexity while achieving reliable backlash suppression.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses backlash in all directions (X, Y, and Z) by applying reactive forces perpendicular to the traveling surface, ensuring precise linear movement of the slider, thus preventing radial and thrust direction backlashes.
Implementation Method 1
a rolling element disposed between the traveling surface of the base and the slider to be traveling along a surface direction of the traveling surface, transmit, to the traveling surface, the biasing torque applied by the biasing means to the slider, and receive reactive force of the biasing torque
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Provided is a linear drive device that makes it possible to surely prevent occurrence of backlash in a slider. The linear drive device of the present invention includes: a lead screw (10); a guide shaft (11); a base (1) including a traveling surface (1d) parallel to the lead screw (10) and the guide shaft (11); and a slider (20) that includes a guide hole (29) through which the guide shaft penetrates and a nut (28) to which the lead screw is screwed, and linearly moves along an axis direction through rotation of the lead screw. The slider includes a first preload spring (35) and a steel ball (24). The first preload spring (35) applies rotational biasing force (RA and RB) along a circumferential direction with the lead screw as a center. The steel ball (24) is travelably disposed between the traveling surface and the slider, transmits, to the traveling surface, the rotational biasing force applied to the slider, and receives reactive force of the rotational biasing force.