Multi-Layer Fibrous Web Formation With Breast Roll Shaking
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Solution Overview
Problem
Existing multi-layer headbox technology faces challenges in achieving uniform color and high transverse strength in paper production, particularly at low cover weights, due to the narrow window for headbox consistency and jet-to-wire speed difference, leading to poorer transverse strengths and formation issues.
Innovation Solution
A method and machine that form a multi-layer fibrous web by using a multi-layer headbox to create a top and bottom layer on a first wire, a middle layer on a second wire, and a reserve layer on a third wire, with horizontal shaking of the breast roll and minimal impulse sieve tables to ensure rapid fixation and uniformity, avoiding layer mixing and turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If headbox consistency and jet-to-wire speed difference are increased to achieve good coverage, then layer purity and uniform color are improved, but transverse strength deteriorates due to higher tear length ratio
Solution Approach 1:
The breast roll shaker applies mechanical vibration to the forming wire in the transverse direction, which redistributes fibers and equalizes formation without requiring high headbox consistency settings. This vibration mechanism allows achieving uniform color and good layer purity while maintaining lower jet-to-wire speed difference, thereby preserving transverse strength.
Solution Approach 2:
The invention changes the operational parameters by introducing breast roll shaking frequency and amplitude as new control variables. By adjusting these vibration parameters, the system can achieve optimal formation and layer purity at different headbox consistency settings, decoupling the traditional trade-off between coverage quality and transverse strength.
2Manufacturing precision
If low turbulence is maintained at the beginning of sheet formation to achieve good coverage, then layer purity is improved, but formation losses and surface irregularities increase
Solution Approach 1:
The breast roll shaker introduces controlled mechanical vibration that prevents fiber mat from sticking to the wire and reduces formation losses. The vibration keeps the fiber suspension moving uniformly across the wire surface, eliminating surface irregularities while maintaining low turbulence conditions that preserve layer purity.
Solution Approach 2:
The system transitions from a static forming process to a dynamic one by continuously vibrating the breast roll. This dynamic approach allows the fiber mat to be evenly distributed and prevented from adhering to the wire, reducing formation losses while maintaining the low turbulence environment needed for good layer purity.
3Productivity
If multi-layer headbox is used to produce multi-layer paper, then productivity is improved, but device complexity increases due to narrow window for headbox consistency and jet-to-wire speed difference
Solution Approach 1:
The breast roll shaker provides a feedback mechanism that continuously adjusts the distribution of fibers during formation. By monitoring and responding to formation quality in real-time through vibration control, the system maintains optimal performance across a wider range of headbox consistency settings, reducing the complexity of precise parameter control.
Solution Approach 2:
The breast roll shaker acts as an intermediary between the headbox and the forming wire, mediating the fiber distribution process. It transforms the fiber suspension from the headbox into a uniformly distributed layer on the wire, decoupling the complexity of headbox settings from the final formation quality, thereby simplifying overall system operation.
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 improves layer purity and coverage quality, reduces formation losses, and enhances transverse strength, while minimizing the need for a headbox and shortening the paper machine length, thus reducing costs.
Implementation Method 1
a breast roll shaker (44) assigned to the breast roll (42), by means of which the breast roll (42) and thus the fourdrinier wire (40) can be shaken back and forth, particularly horizontally in the transverse direction
Implementation Method 2
a vacuumed sieve table is assigned to the respective fourdrinier wire or top former for fixing a covering layer formed from a fiber suspension
Data Source
Figure 1~2
AI summary
The invention relates to a method for producing a multi-layer fibrous web, in particular a multi-layer paper or cardboard web, wherein at least two layers are formed from fibrous suspensions supplied by means of a multi-layer headbox to a long screen or TopFormer, in particular a TopFormer F ® of the applicant, which is provided with a breast roll shaking. In addition, a machine suited for carrying out the method is specified for producing a multi-layer fibrous web, in particular a multi-layer paper or cardboard web.