Ultrasonic Touch Fastener Forming With Preheating for Defect Control
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Solution Overview
Problem
Existing methods for forming touch fasteners in substrates using ultrasonic energy face challenges such as quality defects, limited line speeds, and difficulty in controlling process parameters, leading to issues like holes, tears, and inconsistent hook formation.
Innovation Solution
A method involving a rotating anvil and a rotating or stationary source of vibration energy, with controlled thermal and ultrasonic energy application, to form touch fasteners with improved quality and higher line rates, using specific parameters like lineal force, amplitude, and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ultrasonic energy is applied to form touch fasteners, then hook formation is achieved, but localized high temperature regions cause holes and tears in the substrate
Solution Approach 1:
The substrate is preheated uniformly before ultrasonic processing to reduce the temperature differential during bonding, preventing localized overheating and substrate damage while enabling complete hook formation
Solution Approach 2:
The patent modifies the temperature parameters by preheating the substrate to a controlled temperature range, changing the thermal state from cold to warm, which reduces the harmful thermal shock and localized high temperature regions during ultrasonic bonding
2Productivity
If higher line speeds are used to increase productivity, then production efficiency improves, but quality defects such as incomplete hook formation and hard ridges increase
Solution Approach 1:
The substrate is preheated before ultrasonic processing to ensure it reaches optimal bonding temperature even at higher line speeds, maintaining hook formation quality while increasing productivity
Solution Approach 2:
The preheating process creates a continuous thermal field that persists through the ultrasonic bonding process, ensuring consistent temperature conditions throughout the entire hook formation process even at elevated line speeds
3Adaptability or versatility
If shaped and intermittent patch shapes are used to enhance design options, then product versatility improves, but area balance control becomes difficult leading to mechanical vibration and uneven forces
Solution Approach 1:
The patent applies dynamic parameter adjustments including variable ultrasonic power and frequency modulation to maintain area balance control during shaped patch formation, reducing mechanical vibration and uneven forces while preserving design versatility
4Manufacturing precision
If the substrate is heated to raise temperature, then hook formation improves, but thermal energy may reach the source of vibration energy and cause burn-through
Solution Approach 1:
A heat shield is introduced as an intermediary component between the heating source and the ultrasonic sonotrode, blocking thermal energy from reaching the vibration source while allowing ultrasonic energy to pass through and form hooks in the substrate
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 produces high-quality touch fasteners with reduced defects, enabling wider shape variations and consistent hook formation, while minimizing mechanical vibrations and uneven forces.
Implementation Method 1
applying vibration energy from the source of vibration energy to the substrate in the nip to alter the portion of the substrate
Implementation Method 2
applying thermal energy to a portion of the substrate upstream of a nip formed between a first device comprising an outer surface and providing a second device comprising a source of vibration energy
Implementation Method 3
shear stresses in the hot polymer near the stationary sonotrode and the rotating anvil roll may lead to holes in the patch
Data Source
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AI summary
A method of altering a portion of a substrate may include providing a first device and a second device with a nip therebetween. The second device may comprise a stationary or rotating source of vibration energy. When conveyed through the nip, the substrate may be exposed to the vibration energy and the portion thereof may be altered. Thermal energy may be applied to the portion of the substrate upstream of the nip to raise a temperature of the portion of the substrate to a temperature below a melting temperature thereof. A substrate spreader may contact the substrate upstream of the nip to mitigate fold over or wrinkles in the substrate. When the first device is a rotating anvil and the second device comprises a rotating source of vibration energy, the surface velocities thereof may be variable and may be the same or different.