Ultrasonic Joining with Induction Heating for Thermoplastics
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Solution Overview
Problem
Existing methods using ultrasonic vibration energy for joining thermoplastic polymers face limitations, including restricted local targeting of liquefaction, limited choice of thermoplastic polymers, and design constraints due to vibration wavelength, especially for polymers with high glass transition temperatures or brittle materials that are prone to mechanical damage.
Innovation Solution
Combining ultrasonic vibration energy with electromagnetic induction heating, using a susceptor additive in the thermoplastic polymer to raise its temperature above the glass transition temperature, allowing for more controlled and widespread absorption of ultrasonic energy, thereby enhancing the joining process by improving liquefaction precision and applicability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ultrasonic vibration energy alone is used to liquefy thermoplastic polymer, then the method is simple, but the liquefaction is restricted to specific locations and the choice of polymers is limited
Solution Approach 1:
The patent combines electromagnetic induction heating with ultrasonic vibration energy to create a hybrid joining process. The induction heating unit heats the thermoplastic polymer to its melting point, while ultrasonic vibration provides additional energy for liquefaction and penetration. This merging of two energy sources expands the range of applicable polymers including those with high glass transition temperatures, while maintaining a relatively simple overall process structure.
Solution Approach 2:
The patent changes the thermal state parameter of the thermoplastic polymer by applying electromagnetic induction heating to raise the temperature above the glass transition temperature. This parameter change enables the polymer to absorb ultrasonic energy more effectively and liquefy more uniformly, thereby expanding the choice of usable polymers beyond what ultrasonic vibration alone could achieve.
2Strength
If ultrasonic vibration energy is applied to brittle materials, then joining can be achieved, but mechanical damage is prone to occur
Solution Approach 1:
The patent applies electromagnetic induction heating to preheat the thermoplastic polymer before applying ultrasonic vibration energy. This preliminary heating action raises the polymer temperature above its glass transition temperature, making it more ductile and less prone to brittle failure during the subsequent ultrasonic vibration process, thereby reducing mechanical damage while maintaining joining strength.
Solution Approach 2:
By changing the temperature parameter of the thermoplastic polymer through induction heating, the material transitions from a brittle state to a more ductile state. This parameter change reduces the harmful mechanical damage to brittle materials during the joining process while still achieving strong bonding through controlled liquefaction and penetration.
3Manufacturing precision
If high compression force is applied during ultrasonic joining, then penetration into fibrous material is improved, but mechanical stress on the device increases
Solution Approach 1:
The patent applies electromagnetic induction heating to preheat and soften the thermoplastic polymer before applying compression force during ultrasonic vibration. This preliminary heating action reduces the required compression force needed for penetration into the fibrous or porous material, thereby achieving the same manufacturing precision with lower mechanical stress on the device.
Solution Approach 2:
By changing the temperature parameter of the thermoplastic polymer through induction heating, the material becomes softer and more penetrable. This parameter change allows for precise penetration into the opening with reduced compression force, decreasing the mechanical stress and pressure requirements on the joining device.
4Adaptability or versatility
If thermoplastic polymer with high glass transition temperature is used, then material selection is expanded, but ultrasonic energy absorption is reduced
Solution Approach 1:
The patent applies electromagnetic induction heating as a preliminary action to raise the temperature of the thermoplastic polymer above its glass transition temperature. This preheating enables polymers with high glass transition temperatures to effectively absorb ultrasonic energy during the joining process, thereby expanding the range of applicable polymers without sacrificing energy absorption efficiency.
Solution Approach 2:
By changing the temperature parameter of the thermoplastic polymer through induction heating, the material's ability to absorb ultrasonic energy is significantly improved. This parameter change allows polymers with high glass transition temperatures to be effectively used, expanding material selection while maintaining or enhancing ultrasonic energy absorption and liquefaction efficiency.
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 combination enables more flexible and efficient joining by allowing targeted liquefaction of thermoplastic polymers, expanding the range of applicable polymers and designs, and reducing mechanical stress, while maintaining the advantages of low viscosity and high penetration capability of ultrasonic vibration methods.
Implementation Method 1
applying an alternating electromagnetic field suitable for heating the heatable portion by electromagnetic induction for a time sufficient for raising the temperature of the heatable portion, in particular for raising this temperature above the glass transition temperature of the thermoplastic polymer
Implementation Method 2
applying ultrasonic vibration energy and a compression force to the device or to the object for pressing the device against the object for a time sufficient for liquefying or at least plasticizing the polymer of the heatable portion
Implementation Method 3
providing a device comprising a first solid portion containing a thermoplastic polymer and a susceptor additive being electrically conducting and/or magnetic, in particular ferromagnetic, and being present in the polymer at a concentration great enough for enabling heating of the first portion by electromagnetic induction
Data Source
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AI summary
Disclosed is a method for joining a device (1) to an object (2) with the aid of a combination of ultrasonic vibration energy and induction heating, wherein the device (1) comprises a portion (1.1) of a thermoplastic polymer and a susceptor additive wherein this portion (1.1) is at least partly liquefied or plasticized through the ultrasonic vibration energy in combination with the induction heating and wherein the joining comprises establishing a connection between the device (1) and the object (2) which connection is at least one of a positive fit connection, a weld, a press fit connection, and an adhesive connection. Therein the induction heating on the one hand is applied for rendering the named device portion (1.1) suitable for absorption of ultrasonic vibration energy or better suitable for such absorption than other device portions by raising its temperature, in particular by raising its temperature above the glass transition temperature of the polymer. The ultrasonic vibration energy on the other hand is used for liquefying or at least plasticizing the thermoplastic polymer of the named device portion (1.1).