Anti-backlash Spring Lift for Additive Manufacturing

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Solution Overview

Problem

In additive manufacturing with powdered build materials, accurately lowering the build platform incrementally for each layer is challenging due to the need for precise control within a few microns, which existing drive systems often fail to achieve consistently, leading to inefficiencies and potential backlash.

Innovation Solution

A lift system incorporating a rotationally stationary leadscrew, a rotatable drive nut, an anti-backlash spring applying continuous downward force, and a counter-balance spring providing continuous upward force, ensuring that net downward forces exceed upward forces to prevent backlash and maintain consistent motion throughout the range of motion, allowing for the use of less expensive components like commodity leadscrews and plastic drive nuts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional drive system is used to lower the build platform, then the system is simpler and less expensive, but the positioning precision deteriorates due to backlash and inconsistent forces

Engineering Contradiction:

Improveplatform positioning precisionVSAvoiddrive system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies counter-balance springs that generate upward forces to offset the downward forces from platform weight and build material. This creates a balanced force system that eliminates backlash in the leadscrew-nut interface while maintaining positioning precision throughout the platform's range of motion.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent uses springs with specific force constants and pre-loads that change the force parameters dynamically as the platform moves. The counter-balance springs are designed to provide increasing upward force as the platform descends, compensating for the decreasing downward force from the anti-backlash spring and maintaining consistent net forces for precise positioning.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If expensive precision components are used in the lift drive system, then the positioning precision improves, but the manufacturing cost increases

Engineering Contradiction:

Improveplatform lowering precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent enables the use of commodity leadscrews and plastic drive nuts instead of expensive precision-ground metal components. The spring-based force balancing system compensates for the lower inherent precision of these cheaper components, achieving the required positioning accuracy through force control rather than relying on expensive precision mechanics.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

By dynamically adjusting the force parameters through spring pre-loads and selection, the system achieves consistent positioning precision across the entire range of motion. The springs are designed to maintain optimal force conditions that eliminate backlash and ensure repeatable positioning, allowing standard components to perform at precision levels previously requiring expensive specialized parts.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If the platform is lowered incrementally for each layer, then the manufacturing precision of each layer is maintained, but the total time to complete the build increases

Engineering Contradiction:

Improvelayer thickness precisionVSAvoidbuild cycle time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The spring-based force balancing system maintains continuous contact and consistent forces between the leadscrew and drive nut throughout the entire lowering motion. This eliminates dead zones and backlash that would require re-positioning or correction, allowing the platform to be lowered continuously and precisely for each layer without time-consuming adjustments or corrections.

Inventive Principle:

Principle #20Continuity of useful action

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

This solution enables more accurate and consistent force control in the lift drive system, reducing the risk of backlash and allowing for the use of cost-effective components, thereby improving the precision and efficiency of the additive manufacturing process.

Implementation Method 1

an anti-backlash spring to apply a continuous downward force to the leadscrew

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a counter-balance spring to apply a continuous upward force to the leadscrew

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

a rotationally stationary leadscrew to support a platform, a rotatable drive nut to drive the leadscrew up and down

Methodology Applied

Scientific EffectScrew mechanism: Screw

Data Source

PatentUS11364681B2Lift to lower and raise a platform

Publication Date: 2022.06.21 PERIDOT PRINT LLC

AI summary

In one example, a platform lift includes a rotationally stationary leadscrew to support a platform, a rotatable nut to drive the leadscrew up and down through a range of motion, a first spring to apply a continuous downward force to the leadscrew throughout the range of motion, and a second spring to apply a continuous upward force to the leadscrew throughout the range of motion.