Electrostatic Coating Nozzle Bar with Piezo Gap Adjustment
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Solution Overview
Problem
Existing methods for electrostatically coating metal strips, particularly aluminum or aluminum alloy strips, face challenges in achieving even coating distribution due to limitations in adjusting the nozzle gap size, leading to increased waste and inefficiencies in the production of sheet metal parts, as existing solutions require stopping the coating process for adjustments and are prone to errors in small gap sizes.
Innovation Solution
The use of controllable dosing agents with elastic elements, such as spring steel or piezo actuators, allows for local adjustment of the nozzle gap size during the coating process, enabling precise control of the coating material distribution without stopping the process, even at elevated temperatures, and reducing waste by allowing real-time correction of coating errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the nozzle gap size is adjusted using traditional adjusting screws after the coating process, then the coating distribution can be corrected, but the coating process must be stopped and the nozzle bar must be removed and reinstalled, causing production loss
Solution Approach 1:
The patent applies the dynamics principle by replacing static adjusting screws with piezoelectric actuators that enable real-time, dynamic adjustment of the nozzle gap size during the coating process. The piezoelectric elements allow continuous modification of the gap dimension without mechanical disassembly, maintaining production continuity while achieving precise coating distribution control.
Solution Approach 2:
The patent substitutes the traditional mechanical adjusting screw system with a piezoelectric actuation system. The piezoelectric elements convert electrical signals directly into mechanical displacement, eliminating the need for mechanical thread engagement and manual adjustment. This substitution enables automated, in-process adjustment without stopping the coating operation.
2Manufacturing precision
If the nozzle gap size is reduced to less than 250 μm for industrial oils and forming aids, then the coating distribution is improved, but the adjustment becomes more difficult and error-prone
Solution Approach 1:
The patent replaces mechanical adjustment mechanisms with piezoelectric actuators that can precisely control sub-250 μm gap sizes through electrical actuation. The piezoelectric materials provide fine-resolution control without the mechanical complexity of traditional screws, making adjustment easier and more reliable at these small dimensions.
Solution Approach 2:
The patent incorporates feedback control by measuring the actual nozzle gap size and adjusting the piezoelectric actuation accordingly. This closed-loop system compensates for manufacturing tolerances and thermal expansion, ensuring accurate gap dimensions even at less than 250 μm where manual adjustment becomes error-prone.
3Ease of operation
If the nozzle bar is cooled down to adjust the gap size, then the adjustment can be performed, but the coating process must be stopped and the nozzle bar must be reheated, causing additional production loss
Solution Approach 1:
The patent substitutes temperature-dependent mechanical adjustment with electrically-controlled piezoelectric actuation. This allows the nozzle bar to remain at operating temperature while still achieving gap adjustment through electrical signals, eliminating the need for cooling and reheating cycles that cause production losses.
Solution Approach 2:
The patent enables continuous adjustment during the coating process by using piezoelectric actuators that can modify the nozzle gap in real-time without interrupting operation. The useful action of coating continues uninterrupted while the gap size is adjusted through electrical control, maintaining productivity throughout the adjustment process.
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 approach enables more efficient and precise application of coating materials, reducing waste and improving the quality of coated metal strips, allowing for continuous operation and precise adjustment of the nozzle gap size, thus enhancing the production efficiency of sheet metal parts for motor vehicles.
Implementation Method 1
an electrostatic field is generated between the at least one nozzle bar and the metal strip via a voltage source
Implementation Method 2
the dosing means engage with at least one elastic element of the at least one nozzle bar in such a way that the size of the nozzle gap can be locally changed during the coating by local deformation of the elastic element
Implementation Method 3
the dosing means comprise at least one piezo actuator or linear piezo actuator, with which the local change in the size of the nozzle gap takes place
Data Source
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AI summary
The invention relates to a method for electrostatically coating a metal strip (1) with a coating material (2) using at least one nozzle bar (3), wherein: the metal strip (1) is moved in the longitudinal direction relative to the at least one nozzle bar (3); the at least one nozzle bar (3) comprises at least one slotted nozzle with a nozzle slot (3A), which slotted nozzle at least partially overlaps in the transverse direction the metal strip (1) being moved in the longitudinal direction; an electrostatic field is generated between the at least one nozzle bar (3) and the metal strip (1) via a voltage source (4); and the metal strip (1) is coated electrostatically, over at least a partial area, with at least one coating material (2). The problem of providing a method for electrostatically coating a metal strip with a coating material and a corresponding device, with which method and/or device the coating application on the metal strip can be adjusted with less effort and coating the metal strip while producing few rejects is made possible, is solved for a method by using a plurality of addressable dosing means (5) which are arranged on the at least one nozzle bar (3) distributed in the longitudinal direction thereof and with which the size of the nozzle slot (3A) of the at least one nozzle bar (3) can be modified locally during coating using a control signal.