Short Pulse Laser Structuring of Steel Embossing Rollers
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Solution Overview
Problem
Current methods for producing structured surfaces on steel embossing rollers, such as those used for cigarette innerliners, are limited in precision and efficiency, particularly for large surface areas with macrostructures of 20 μm to 400 μm in size and depth, due to issues with mechanical machining and existing laser systems which often result in unwanted heat generation, material alteration, and poor control over ablation depth and surface quality.
Innovation Solution
A method utilizing short pulse lasers with specific parameter control, including burst mode operation, to achieve precise and efficient macrostructuring of steel rollers with structures up to 400 μm depth and 70 μm line spacing, combined with microstructuring for high-resolution results, using parameters like pulse duration, fluence, repetition rate, and beam focus positioning to avoid thermal overload and improve surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical machining is used to produce structured surfaces on steel embossing rollers, then very good qualitative and quantitative results are achieved, but the possibilities are limited by machining tool dimensions and enormous expenditure is required for large roller surfaces
Solution Approach 1:
The patent replaces mechanical machining with laser technology to structure steel embossing roller surfaces. The laser system can produce fine structures (line spacing down to 70 μm) on large roller surfaces without the limitations of mechanical tool dimensions, dramatically improving productivity while maintaining manufacturing precision
Solution Approach 2:
The patent uses parameter changes in laser processing (pulse width, energy density, scanning speed) to achieve different structure depths and patterns on the roller surface. By adjusting these parameters, the laser can create structures from 20 μm to 400 μm in size and depth, replacing mechanical machining across the entire surface area
2Manufacturing precision
If conventional laser systems with pulse widths around 30 ns are used for machining steel rollers, then some fine machining is achieved down to 70 μm line spacing, but heat generation and material alteration occur
Solution Approach 1:
The patent uses ultrashort laser pulses with widths in the picosecond to femtosecond range (10⁻¹² to 10⁻¹⁵ seconds), which is a dramatic parameter change from conventional 30 ns pulses. This ultrashort duration enables ablation of steel with minimal heat diffusion, achieving precise line spacing of 70 μm while avoiding thermal overload and material alteration
Solution Approach 2:
The patent employs periodic laser pulsing with specific repetition rates to structure the roller surface. The ultrashort pulses are delivered in controlled sequences, allowing each pulse to ablate material before heat can diffuse to surrounding areas, thus maintaining precision while minimizing thermal damage
3Manufacturing precision
If existing laser methods are used for macro-machining of steel rollers with structures from 20 μm to 400 μm, then some structuring is achieved, but poor control over ablation depth and surface quality occurs
Solution Approach 1:
The patent implements feedback control in the laser processing system to precisely control ablation depth and surface quality. By monitoring processing parameters and adjusting laser energy delivery in real-time, the system achieves consistent structuring of steel rollers with structures from 20 μm to 400 μm while maintaining precise depth control
Solution Approach 2:
The patent replaces conventional laser systems with ultrashort pulse laser technology, which provides superior control over ablation depth through the nonlinear absorption characteristics of ultrashort pulses. This substitution enables precise structuring of steel surfaces with structures ranging from 20 μm to 400 μm while maintaining excellent surface quality and depth consistency
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
Enables the rapid and precise production of embossing rollers with complex macrostructures and microstructures, overcoming previous limitations in surface roughness and ablation control, allowing for diverse design possibilities and industrial-scale manufacturing of high-quality steel embossing rollers.
Implementation Method 1
A method utilizing short pulse lasers with specific parameter control, including burst mode operation, to achieve precise and efficient macrostructuring of steel rollers with structures up to 400 μm depth and 70 μm line spacing
Data Source
AI summary
A method for structuring a steel embossing roller surface includes using a short pulse laser including at least one of a femtosecond laser and a picosecond laser. The structuring is macrostructuring with dimensions of over 20 μm and depths up to 150 μm and more. The short pulse laser has: in single pulse operation, a fluence in the range of 0.5 J/cm2 to 3.5 J/cm2, and in burst operation, a mean burst fluence of 0.5 J/cm2 to 70 J/cm2 per pulse; a wavelength of 532 nm to 1064 nm; a repetition rate of 1 kHz to 10 MHz; a pulse to pulse spacing on the roller of 10% to 50% of the beam diameter for the femtosecond laser and of 10-25% and 40-50% of the beam width for the picosecond laser; a laser pulse position near the roller surface; and deflection velocities of up to 100 m/s and more.