Grooved Plastic Component Joining for Low-Trace Ultrasonic Welding
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Solution Overview
Problem
Existing methods for connecting plastic components, such as bumpers and sensor holders, often result in visual impairment due to energy input during ultrasonic welding, and there is a need for a method that enhances connection strength while minimizing thermal and energy impact.
Innovation Solution
A method involving plastics injection moulding with surface structures of grooves on the components, specifically with spacings and depths of 0.1 to 2 mm, and using ultrasonic welding with a sonotrode to connect components step-by-step, reducing energy input and improving strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If ultrasonic welding is performed on smooth contact faces to make the contact area as large as possible, then the welding area is maximized, but the visual appearance is impaired due to energy input during melting
Solution Approach 1:
The invention applies different surface qualities to different regions: the visible outer surface remains smooth for aesthetic purposes, while the fastening region contains grooves that localize the welding action. This ensures that melting and energy input are confined to the grooved areas, preserving the smooth visual appearance of the outer surface while maintaining adequate contact area through the grooved structure.
2Area of stationary object
If ultrasonic welding is performed on smooth surfaces with large contact area, then the welding coverage is improved, but the connection strength is insufficient
Solution Approach 1:
The grooved surface structure creates localized regions of enhanced welding intensity within the fastening area. The grooves concentrate ultrasonic energy and facilitate deeper material interpenetration, thereby increasing connection strength without requiring an increase in the overall contact area. The smooth outer surface maintains aesthetic appearance while the grooved fastening region provides superior mechanical bonding.
3Ease of manufacture
If conventional ultrasonic welding is used on smooth surfaces, then the process is simple, but the connection strength increases by only limited amounts
Solution Approach 1:
The groove structure is pre-formed in the fastening region during component manufacturing, before the welding process. This preliminary structuring of the surface prepares the material to receive and concentrate ultrasonic welding energy more effectively, enabling stronger connections without adding complexity to the welding process itself. The grooves guide the welding action and enhance material interpenetration.
4Reliability
If energy is applied during ultrasonic welding to melt the contact face, then the welding process is effective, but thermal influence and stress increase
Solution Approach 1:
The grooved surface structure localizes the thermal influence and melting action to specific regions within the fastening area. By confining the ultrasonic energy input to the grooved zones, the overall thermal affect on the component is reduced, while still achieving effective welding in the critical bonding regions. This localized approach maintains welding effectiveness while minimizing unwanted thermal stress.
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 method achieves a high-strength connection with reduced thermal and energy impact, enhancing the visual appearance by minimizing visible traces and increasing connection strength by 9-13% compared to unstructured connections.
Implementation Method 1
the energy for the welding being introduced into the plastic components via at least two pins of the sonotrode
Implementation Method 2
by the melting or liquefying of the plastic material of the second component
Implementation Method 3
at least one fastening region is provided on the at least one component and is moulded with a surface structure of grooves having a small spacing
Implementation Method 4
a reliable and firm connection of the two components is formed after the (re)solidification of the plastic
Data Source
AI summary
The invention relates to a method for producing a connection between a first plastic component and a second plastic component, wherein at least one of the two components is produced by plastics injection moulding, wherein at least one fastening region is provided on the at least one component and is moulded with a surface structure of grooves having a small spacing, and wherein the components are connected to one another by an ultrasonic welding method in the fastening region.