Ceramic Coating Nozzle Pressure Control
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Solution Overview
Problem
Current coating methods for ceramic printing media, such as the bell process and fluid atomizing processes, face challenges in achieving homogeneous application of glaze suspensions, leading to visible banding effects and material inefficiencies, while more complex methods like DOD inkjet printing and print heads with electronically controllable nozzles are costly and prone to clogging.
Innovation Solution
A method involving a coating head with a fluid supply channel and nozzles, where overpressure is applied during coating and negative pressure is applied when not coating, preventing fluid outflow without the need for closing bodies, and maintaining a closed fluid circuit to prevent contamination and drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluid atomizing nozzles are used to apply glaze suspension, then coating speed and productivity are improved, but homogeneous application is deteriorated due to banding effects
Solution Approach 1:
The coating head is divided into multiple nozzles arranged in a specific pattern, where each nozzle applies coating to a specific zone. The nozzles are segmented into different groups that can be independently controlled to eliminate banding effects and achieve homogeneous coverage across the entire substrate surface.
Solution Approach 2:
The system dynamically switches between different nozzle groups based on the position of the substrate and coating requirements. By activating only the necessary nozzles at any given moment and adjusting their operation dynamically, the system maintains high productivity while ensuring uniform coating distribution without visible banding patterns.
2Reliability
If electronically controllable nozzles are used to prevent clogging, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The nozzle system is designed to be self-cleaning through periodic reverse flushing and self-diagnosis capabilities. The nozzles automatically detect clogging conditions and perform cleaning operations without external intervention, maintaining reliability while avoiding complex external cleaning mechanisms and reducing overall system complexity.
Solution Approach 2:
A pneumatic or hydraulic flushing system is integrated into the nozzle design, using fluid pressure to automatically clear deposits and prevent clogging. This approach provides reliable clogging prevention through simple fluid-based mechanisms rather than complex electronic or mechanical systems.
3Ease of operation
If open fluid circuit is used during negative pressure phase, then ease of operation is improved, but contamination and drying occur
Solution Approach 1:
A flexible membrane or thin film barrier is introduced in the fluid circuit to separate the liquid coating material from the atmosphere during negative pressure phases. This barrier prevents contamination and evaporation while allowing the system to maintain ease of operation by not requiring complex sealing mechanisms, as the membrane automatically adapts to pressure changes.
Solution Approach 2:
The fluid circuit is purged with an inert gas atmosphere during negative pressure phases, creating a protective environment that prevents contamination and drying of the coating material. This approach maintains ease of operation by using simple gas flow control rather than complex sealing systems.
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 method ensures even and economical coating with reduced material loss and clogging, allowing for flexible use with different coating systems and preventing nozzle clogging, resulting in a homogeneous and cost-effective application.
Implementation Method 1
applying a respective overpressure relative to the atmospheric pressure to the liquid fluid, at least in the area of each inflow opening of the nozzles, at least during the time intervals in which the at least one printing medium is to be coated in such a way that the liquid fluid is applied in the form of continuous columnar fluid jets
Implementation Method 2
applying a respective negative pressure relative to the atmospheric pressure to the liquid fluid, at least in the area of each inflow opening of the nozzles, during the time intervals in which no liquid fluid is to be dispensed from the nozzles
Data Source
AI summary
A method for coating at least one printing medium, in particular a ceramic printing medium, including the steps of (a) providing at least one coating head with a fluid supply channel, a plurality of nozzles, each having a nozzle channel and an inflow opening, which form the connection of the respective nozzle channels to the fluid supply channel, wherein the respective nozzles are arranged in a stationary manner on a side wall of the fluid supply channel; (b) filling the fluid supply channel with liquid fluid; (c) transporting the at least one printing medium along a transport direction; (d) applying a respective overpressure relative to the atmospheric pressure to the liquid fluid, at least in the area of each inflow opening of the nozzles, at least during the time intervals in which the at least one printing medium is to be coated in such a way that the liquid fluid is applied in the form of continuous columnar fluid jets to the at least one printing medium, wherein according to (e), during the time intervals in which no liquid fluid is to be dispensed from the nozzles, a respective negative pressure relative to the atmospheric pressure is applied to the liquid fluid at least in the area of each inflow opening of the nozzles, as a result of which an outflow of liquid fluid from the nozzle channels, even without the participation of the respective closing bodies assigned to the nozzles, is prevented in step e) and made possible in step (d).