Nonwoven Fabric Production with Three-Stage Drawing for Reinforcement
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Solution Overview
Problem
Existing nonwoven fabrics used in civil engineering applications lack sufficient mechanical characteristics, limiting their effectiveness as reinforcement materials.
Innovation Solution
A three-step drawing process involving two aerodynamic devices and a mechanical device, combined with mechanical rollers and a mechanical distributor, is employed to produce high tenacity filaments, followed by consolidation using needle-felting and thermal treatment to enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-step drawing process is used, then the production process is simple, but the filament tenacity is insufficient
Solution Approach 1:
The drawing process is divided into three separate stages: first aerodynamic drawing device, then mechanical drawing device with rollers, and finally second aerodynamic drawing device. Each stage progressively increases filament tenacity, transforming a single-step process into a multi-stage progressive drawing system that achieves high mechanical properties without excessive complexity
Solution Approach 2:
The mechanical drawing device incorporates rollers with variable speeds and movable secondary rollers that can transition between non-intercepting and intercepting positions. This dynamic adjustment allows the system to adapt the drawing intensity at each stage, optimizing filament tenacity development while maintaining process control
2Strength
If high drawing tension is applied to increase filament tenacity, then filament strength improves, but thermal shocks may damage the filaments
Solution Approach 1:
The filaments are pre-cooled by the first cooling device before entering the mechanical drawing device. This preliminary cooling action prepares the filaments to withstand the subsequent drawing tensions without thermal shock damage, allowing high tenacity to be achieved safely
Solution Approach 2:
The mechanical drawing device incorporates heatable rollers that can be heated to temperatures between 60°C and 150°C. This parameter change in temperature allows the rollers to assist drawing through temporary heating, preventing thermal shocks while maintaining drawing efficiency and achieving high filament tenacity
3Productivity
If the secondary rollers intercept the filaments immediately, then drawing is more effective, but the spinning process becomes difficult to initiate
Solution Approach 1:
The secondary rollers are designed to be movable relative to the primary rollers, allowing them to transition between non-intercepting and intercepting positions. Initially, they are positioned to not intercept filaments, enabling easy spinning initiation. Once spinning is established, they move to intercepting positions to provide effective drawing, thus resolving the contradiction between ease of initiation and drawing effectiveness
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 process produces a nonwoven fabric with improved mechanical properties suitable for reinforcement in civil engineering structures, ensuring even load distribution and structural integrity.
Implementation Method 1
a first aerodynamic drawing device downstream of the cooling device, to draw the filaments; a second aerodynamic drawing device downstream of the mechanical drawing device
Implementation Method 2
a suction element to suction gases below the filament collection surface
Implementation Method 3
the rollers are heatable preferably to a temperature between 60°C and 150° C, in order to adjust the temperature of an element against which the filaments come into contact, thereby preventing, for example, thermal shocks, or otherwise assisting the drawing by means of temporary heating
Data Source
Figure 1
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AI summary
Apparatus for the production of a nonwoven fabric comprising: a spinneret for extruding a plurality of filaments; at least one first cooling device arranged below the spinneret; a first aerodynamic drawing device downstream of the cooling device, to draw the filaments; a mechanical drawing device downstream of the first aerodynamic drawing device; a second aerodynamic drawing device downstream of the mechanical drawing device; a mechanical distributor arranged downstream of the second aerodynamic drawing device to divert the path of the filaments; a filament collecting device arranged below the mechanical distributor, wherein the collecting device comprises a collection surface to collect the filaments and form a nonwoven fabric; a suction element to suction gases below the filament collection surface.