Ultrasonic Welding Force Sensing Near the Sonotrode Zero Position
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Solution Overview
Problem
Ultrasonic welding processes face challenges in accurately measuring and controlling forces exerted on joining partners, leading to variations in weld quality, particularly in mechanical strength and electrical conductivity.
Innovation Solution
An ultrasonic welding device equipped with a sonotrode arrangement, an anvil, a displacement device, and a force sensor positioned near a zero point position to measure forces exerted by the sonotrode arrangement, allowing for precise force measurement and control, minimizing friction and vibration-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is positioned to measure forces during ultrasonic welding, then measurement precision is improved, but the force sensor is subjected to high-frequency vibrations and friction that reduce its service life and measurement accuracy
Solution Approach 1:
The patent introduces a force sensor that is indirectly coupled to the sonotrode assembly through a bearing element, which acts as an intermediary. This bearing element transmits only the static or low-frequency dynamic forces from the sonotrode to the force sensor, while filtering out the high-frequency ultrasonic vibrations. This resolves the contradiction by enabling accurate force measurement without exposing the sensor to damaging vibrations.
Solution Approach 2:
The patent replaces direct mechanical coupling between the force sensor and sonotrode with a bearing-based mechanical filter system. The bearing element serves as a mechanical low-pass filter that allows force transmission while blocking high-frequency vibration transmission, thus protecting the force sensor while maintaining measurement capability.
2Measurement precision
If the force sensor is positioned close to the sonotrode head for accurate measurement, then measurement precision is improved, but the sensor is exposed to higher vibrations and friction
Solution Approach 1:
The bearing element positioned between the sonotrode and force sensor acts as a selective transmitter that allows the force sensor to be positioned close to the sonotrode for accurate measurement of welding forces, while simultaneously filtering out harmful high-frequency vibrations and reducing friction effects on the sensor.
3Manufacturing precision
If direct force measurement is implemented during ultrasonic welding, then manufacturing precision is improved, but device complexity increases due to additional sensing and control systems
Solution Approach 1:
The patent uses a purely mechanical bearing-based vibration filtering system instead of complex electronic vibration isolation systems. This mechanical approach achieves vibration isolation and force transmission with minimal additional complexity, enabling accurate force measurement and weld quality control without significantly increasing device complexity.
Solution Approach 2:
The bearing element automatically performs the function of vibration filtering and force transmission without requiring active control or additional power. The passive mechanical filter inherent in the bearing structure provides the necessary vibration isolation, simplifying the overall system while enabling precise force measurement for weld quality improvement.
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 configuration enables accurate force measurement and control, improving weld quality by ensuring consistent mechanical strength and electrical conductivity, extending the service life of the force sensor and allowing for real-time monitoring and regulation of the welding process.
Implementation Method 1
The sonotrode assembly (3) is configured to transmit ultrasonic vibrations, which are generated at the sonotrode assembly in a region remote from the sonotrode head, to the sonotrode head (11) such that the sonotrode head (11) vibrates in a direction of vibration of the sonotrode assembly (3)
Implementation Method 2
The force sensor (9) is positioned and configured in a contact area (23) adjacent to the zero point position (21) such that forces (Fs) exerted on the force sensor (9) by the sonotrode arrangement (3) parallel to the displacement direction (19) can be measured by means of the force sensor (9)
Implementation Method 3
The displacement device (7) is configured to displace the sonotrode assembly (3) and the anvil (5) relative to one another in a direction of displacement (19)
Data Source
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AI summary
The invention relates to an ultrasonic welding device (1) comprising a sonotrode assembly (3), an anvil (5), a displacement device (7), and a force sensor (9). The sonotrode assembly (3) has a sonotrode head (11). The sonotrode assembly (3) is designed to transmit ultrasonic vibrations, which are generated at the sonotrode assembly in an region (13) remote from the sonotrode head, to the sonotrode head (11) such that the sonotrode head (11) oscillates in an oscillation direction (17) of the sonotrode assembly (3) and such that the sonotrode assembly (3) oscillates minimally in the oscillation direction (17) at a zero position (21) which is located at a distance from the sonotrode head with respect to the oscillation direction (17). The displacement device (7) is designed to displace the sonotrode assembly (3) and the anvil (5) relative to one another in a displacement direction (19). The force sensor (9) is positioned and configured in a contact region (23) adjacent to the zero position (21) in such a way that forces (Fs) exerted by the sonotrode assembly (3) on the force sensor (9) parallel to the displacement direction (19) can be measured with the aid of the force sensor (9). Based on the measured forces (Fs), a closed-loop control device (39) can control functions or properties of the ultrasonic welding device (1) in a closed-loop manner.