Spindle Drive with Offset Threads for Dental Material Extrusion

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Solution Overview

Problem

Current dental material dispensing devices are costly to manufacture and require complex gearboxes, leading to high production costs and potential reliability issues, while also being inefficient in handling high-viscous materials and requiring high-force motors.

Innovation Solution

A spindle drive system with a pair of threaded spindles and a clasp nut member featuring offset thread structures, allowing for a compact design that minimizes parts and tools needed, enabling efficient extrusion of dental materials, including high-viscous ones, using relatively small and inexpensive motors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If complex gear boxes are used to drive the piston, then the device can achieve high extrusion force, but the manufacturing cost increases and reliability decreases

Engineering Contradiction:
Improveextrusion forceVSAvoidgear box complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The patent removes the complex gearbox from the drive system entirely, replacing it with a direct spindle-nut mechanism. The threaded spindle directly converts rotational motion to linear piston movement without intermediate gear transmissions, eliminating the problematic component while maintaining force transmission capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical gearbox system with a threaded fastening mechanism (spindle and nut). This substitution uses the mechanical advantage of threaded engagement to achieve force multiplication and directional control without requiring complex gear trains, thereby simplifying the overall mechanical system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Force

If high-force motors are used to drive the piston, then the device can extrude high-viscous materials, but the device cost and motor size increase

Engineering Contradiction:
Improvepiston drive forceVSAvoidmotor size and cost
Core Design Contradiction:
ForceVSQuantity of substance

Solution Approach 1:

The patent changes the mechanical transmission parameters by using a fine-pitch threaded spindle. This allows the motor to operate at higher rotational speeds with lower torque requirements, while the threaded mechanism provides the necessary force multiplication. The parameter change from direct high-torque transmission to speed-based transmission with mechanical advantage reduces motor size and cost.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If fast extrusion speeds are used, then productivity increases, but the device cannot handle high-viscous materials effectively

Engineering Contradiction:
Improveextrusion speedVSAvoidextrusion force for high-viscous materials
Core Design Contradiction:
ProductivityVSForce

Solution Approach 1:

The patent creates a dynamic system where the spindle rotation speed can be varied to match the viscosity requirements of different materials. For high-viscous materials, the system operates at lower speeds with higher force transmission through the threaded mechanism. For lower viscosity materials, the spindle can rotate faster, maintaining productivity while adjusting to material-specific requirements.

Inventive Principle:
Principle #15Dynamics

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 enables a robust, cost-effective, and reliable dental material dispensing device capable of slow extrusion speeds, reducing manufacturing complexity and costs, while allowing for the use of smaller motors and efficient handling of high-viscous materials.

Implementation Method 1

The spindle drive comprises a pair of threaded spindles (11, 12) which extend generally parallel to a longitudinal axis (A). The spindle drive comprises further a clasp nut member (20) which has a first thread structure (21) and a second thread structure (22). Each of the first and second thread structures (21, 22) being adapted for engaging with the thread of anyone of the spindles to establish a screw connection between the clasp nut member and the spindles.

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP2782682B1A device for dispensing a dental material
Publication Date: 2015.09.09 3M INNOVATIVE PROPERTIES CO
  • EP2782682B1 patent drawingFigure 1
  • EP2782682B1 patent drawingFigure 2
  • EP2782682B1 patent drawingFigure 3~4

AI summary

A device (100) for dispensing a dental material which comprises a spindle drive (10) for driving a piston (111) for extruding the dental material. The spindle drive (10) comprises a pair of threaded spindles and a clasp nut member (20) which is adapted for engaging with anyone of the spindles. The clasp nut member has first and second thread structures (11, 12) which are offset relative to each other by about 1/2 of the pitch of the thread of the spindle or the thread structures (11, 12) in a dimension of the pitch.