Dry Forming Drum with Variable Perforation Density for Cellulose Products
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Solution Overview
Problem
Existing dry-forming techniques for rigid cellulose products with non-flat shapes face challenges such as high water consumption, energy inefficiency, and the risk of cracking due to uneven grammage and sensitivity to electrostatic charges, making them unsuitable for large-scale production and complex designs.
Innovation Solution
A method and apparatus utilizing a forming drum with varying perforation densities to control the grammage of cellulose fibres, forming a continuous or discontinuous cellulose blank with tailored properties, and using a support structure to produce rigid cellulose products with enhanced strength and reduced waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wet moulding technique is used to produce rigid cellulose products, then the sustainability and material properties are improved, but the water consumption and energy requirements increase substantially
Solution Approach 1:
The invention changes the fundamental parameter of moisture content from high (wet moulding) to low (dry forming), eliminating the need for energy-intensive drying operations while maintaining product integrity through controlled fibre deposition and bonding mechanisms
Solution Approach 2:
The invention replaces the water-based wet moulding mechanical system with an air-based dry forming system, where fibre suspension and deposition are controlled through air flow dynamics rather than water transport, eliminating evaporation energy requirements
2Stability of the object's composition
If wet moulding technique is used to produce rigid cellulose products, then the material sustainability is improved, but the production speed decreases due to drying requirements
Solution Approach 1:
The dry forming process enables continuous production without interruption for drying cycles, as fibres are deposited and bonded in a dry state that maintains structural integrity immediately, allowing continuous operation at high speeds
Solution Approach 2:
The invention extracts the drying step entirely from the production process by using dry fibres from the outset, removing the time-consuming and productivity-limiting drying phase while retaining the sustainability benefits of cellulose materials
3Loss of energy
If air/dry-laid process is used to form cellulose fibres, then the water consumption is reduced, but the network strength and self-supporting properties become weak
Solution Approach 1:
The invention applies preliminary bonding agents or surface treatments to fibres before deposition, or creates preliminary structural patterns during deposition that enhance network strength and self-supporting properties before the final product formation
Solution Approach 2:
The invention creates composite structures within the fibre network by incorporating bonding agents, adhesives, or reinforcing elements that strengthen the weak points in the air-laid fibre network while maintaining the dry forming process benefits
4Device complexity
If uniform perforation density is used in forming drum, then the manufacturing simplicity is maintained, but the grammage uniformity of cellulose blank becomes poor
Solution Approach 1:
The forming drum incorporates locally varied perforation densities matched to the specific grammage requirements of different product regions, with higher perforation densities in areas requiring thicker fibre deposits and lower densities in areas requiring thinner deposits, achieving precise grammage control throughout the product
5Shape
If complex pressing procedure is used to form 3D shaped component, then the product shape complexity is improved, but the risk of sheet cracking increases
Solution Approach 1:
The invention performs preliminary shaping and grammage optimization during the fibre deposition phase itself, creating pre-formed 3D structures with appropriate grammage distribution before pressing, thereby reducing the severity and cracking risk of subsequent pressing operations
Solution Approach 2:
The invention changes the pressing parameters (pressure, temperature, time, moisture content) to optimize for complex 3D shapes, using controlled parameter variations that accommodate intricate geometries without causing sheet failure or cracking
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 solution provides a more efficient and reliable dry manufacturing process for cellulose products with improved rigidity and reduced cracking, allowing for tailored properties and reduced waste, making it suitable for large-scale production and complex designs.
Implementation Method 1
a forming drum having an outer surface comprising perforations, wherein the outer surface is configured for receiving cellulose fibres and for forming a cellulose blank from said quantity of separated cellulose fibres transported by the air flow via the dispenser
Data Source
AI summary
An apparatus for dry manufacturing rigid cellulose products having essentially non-flat general shape comprising a disintegrating unit, a cellulose blank forming unit, and a product forming unit. The cellulose blank forming unit comprises a dispenser for guiding a cellulose fibre carrying air flow from the disintegrating unit, and a forming drum having an outer surface comprising perforations. The outer surface is configured for receiving cellulose fibres and forming a continuous or discontinuous cellulose blank, and comprises a first area having a first perforation density and a second area having a second perforation density less than the first perforation density for forming the cellulose blank with higher grammage at first locations originating from the first area than at second locations originating the said second area. The apparatus further comprises an air removing device arranged inside the forming drum, and a support structure for receiving the cellulose blank from the forming drum.