Ultrasonic Welding Sonotrode Eccentric Gap Adjustment
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Solution Overview
Problem
Existing ultrasonic devices for hot-melt article welding and cutting face challenges in adjusting the air gap and pressure, particularly when used in inverted positions, where the weight of the ultrasonic assembly tends to separate the sonotrode from the anvil, making it difficult to access and maneuver the adjustment means.
Innovation Solution
The device incorporates an eccentric axis operable in rotation, engaged in the support and the body part, allowing for precise adjustment of the air gap and pressure by offsetting the support by a few micrometers, with a double-shouldered cylindrical bearing surface and threaded surfaces creating eccentricity, and a locking mechanism to maintain the adjustment, enabling easy manipulation in any position, including upside-down configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the device is used in inverted position with ultrasonic assembly below the anvil, then the weight of the ultrasonic assembly tends to separate the sonotrode from the anvil, but this makes it difficult to access and maneuver the adjustment means for air gap and pressure
Solution Approach 1:
The patent inverts the traditional adjustment mechanism by using an eccentric axis that rotates in place rather than requiring linear movement or external access. The eccentricity converts rotational motion into the required linear displacement for air gap adjustment, allowing operation from any device position including inverted configurations where the ultrasonic assembly is below the anvil.
Solution Approach 2:
The patent replaces complex mechanical adjustment systems with a simplified eccentric axis mechanism. Instead of using traditional nuts, bolts, or external adjustment devices that are difficult to access in inverted positions, the eccentric axis provides a self-contained rotational adjustment system that is easily accessible from the outside of the body.
2Force
If the weight of the ultrasonic assembly is used to press the sonotrode against the anvil in normal position, then pressure is maintained, but in inverted position the weight tends to separate the sonotrode from the anvil modifying the air gap and pressure force
Solution Approach 1:
The patent introduces a spring element that acts as a counterweight to the gravitational force on the ultrasonic assembly. The spring is compressed between the eccentric axis mechanism and the body, providing a constant upward force that maintains pressure between the sonotrode and anvil regardless of device orientation. This counteracts the weight of the ultrasonic assembly in inverted positions.
Solution Approach 2:
The patent creates a dynamic pressure maintenance system where the spring force automatically adjusts to compensate for gravitational effects in different positions. The combination of spring force and eccentric axis allows the system to adapt to any orientation while maintaining consistent contact pressure between the sonotrode and anvil.
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 allows for precise and easy adjustment of the air gap and pressure in any device position, including inverted positions, effectively adapting to variations in product thickness and preventing fraying during cutting operations, enhancing operational efficiency and adaptability.
Implementation Method 1
The double-shouldered cylindrical seat and the two threaded seats are offset to create an eccentricity under the effect of the rotational drive of the axis
Implementation Method 2
The ultrasonic vibrations of the sonotrode produce the total or partial melting of the zone of the thermofusible article placed between the sonotrode and the anvil
Data Source
Figure 1~10
Figure 2
Figure 3~4
AI summary
This apparatus comprises, as is usually the case, a body having (i) a part (1a) that receives an oscillating holder (2) to which an assembly is adjustably fixed, said assembly including a converter (3) and a sonotrode (4), and (ii) a part (1b) that receives a counter tool or anvil placed in alignment with, and opposite the sonotrode (4). The assembly is secured to means for modifying the gap between the sonotrode (4) and the anvil and the pressure exerted by the sonotrode (4). The apparatus is also equipped with a means (11) in the form of an eccentric shaft which can be rotated from the exterior of the body and which includes: a double shouldered cylindrical bearing inserted, in a freely rotatable manner, in the thickness of the holder and of part of the body that receives the holder; and a zone with two threaded bearings that extend beyond said part of the body. The rotation of the shaft shifts the holder by a few micrometres in order precisely to readjust, and maintain, the setting for the pressure and the gap when the apparatus is used in any position, including an upside-down position, i.e. when the assembly is located below the anvil.