Ultrasonic Welding Spacing Control With Voice Coil Actuation

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Solution Overview

Problem

Existing ultrasonic welding systems struggle to maintain a precise and constant spacing between the energy emitter and the support underneath materials with uneven thickness, such as woven or non-woven fabrics, due to inherent vibrations and the need for inefficient harmonic filtering systems.

Innovation Solution

A sonication welding system with a frame and adjustment mechanism that includes a high-stiffness structure, a tilting plate, and a voice coil actuator, allowing real-time control and micrometric adjustment of the spacing between the sonotrode and anvil element using a linear actuator and transmission lever, minimizing vibrations and ensuring constant spacing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If additional on-site measuring devices and harmonic filtering systems are used to track and maintain spacing, then spacing control is achieved, but device complexity and processing time increase significantly

Engineering Contradiction:
Improvespacing control precisionVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex electronic measurement and filtering systems with a purely mechanical solution. A voice coil actuator directly couples to the sonotrode positioning mechanism, providing precise spacing control through electromagnetic force without requiring external sensors or harmonic filtering. The mechanical feedback through the rigid frame structure enables direct sensing and correction of spacing deviations.

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

Solution Approach 2:

The system uses its own structural components (rigid frame, voice coil actuator, transmission lever) to automatically maintain spacing without external control systems. The voice coil actuator responds directly to spacing deviations through mechanical coupling, creating a self-regulating system that eliminates the need for separate measurement and control devices.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If an Archimedes screw system with rotary actuator is used for vertical movement, then material replacement is enabled, but spacing adjustment precision deteriorates due to uncompensated vertical loads

Engineering Contradiction:
Improvematerial replacement capabilityVSAvoidspacing adjustment precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent introduces a counterweight mechanism that compensates for vertical loads on the sonotrode. The counterweight system balances the gravitational force and welding reaction forces, allowing the voice coil actuator to focus solely on fine spacing adjustments without being overwhelmed by vertical load variations during material replacement operations.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The positioning system is divided into two independent functions: a rotary actuator with Archimedes screw for coarse vertical movement and material replacement, and a voice coil actuator for fine spacing adjustment. This segmentation allows each component to optimize its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

3Manufacturing precision

If voice coil actuator is used for micrometric adjustment, then spacing precision is improved, but system complexity increases

Engineering Contradiction:
Improvespacing adjustment precisionVSAvoidactuator system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the voice coil actuator directly with the existing sonotrode positioning mechanism, eliminating the need for separate fine-adjustment devices. The voice coil integrates with the transmission lever and frame structure, using existing mechanical components as part of the electromagnetic actuation system, thereby reducing overall complexity despite adding precision capability.

Inventive Principle:
Principle #5Merging (Combining)

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 system achieves precise and real-time adjustment of the spacing between the sonotrode and anvil element, enhancing welding precision and reducing the time required for resuming operations after material replacement.

Implementation Method 1

a control member (6) with a voice coil actuator (20) generating a lifting force counterbalancing a weight of the sonotrode (15) and compensating for variations in thickness of the material (M)

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

The transformation of the electrical signal into mechanical force is achieved in the transducer using a piezoelectric material, which can polarize generating a potential difference when subjected to mechanical deformation (direct piezoelectricity) and conversely deform when subjected to a potential difference which causes a charge polarization therein (reverse piezoelectricity). The latter property is that utilized in ultrasonic transducers.

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

By virtue of its structural characteristics, the latter amplifies the vibration, in some cases with the aid of a so-called booster, and transfers it to the medium or material to be treated.

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentEP4324586B1Sonication welding system
Publication Date: 2025.11.05 V TECH S R L S
  • EP4324586B1 patent drawingFigure 1
  • EP4324586B1 patent drawingFigure 2
  • EP4324586B1 patent drawingFigure 3

AI summary

The present invention relates to a sonication welding system, in particular a high-precision welding system. In particular, the invention relates to an ultrasonic welding system (1) comprising a frame (2) to which at least one ultrasonic welding device (3) is movably mounted, wherein the ultrasonic welding device (3) comprises a sonicator device (4), a anvil element (5) and a member (6) for adjusting the spacing (17) between said sonicator device (4) and said anvil element (5), characterized in that said adjustment member (6) comprises a linear actuator (20) operatively coupled to the sonicator device (4) by means of a kickdown lever transmission.