Jointed Fiber Strand Structure for Clean Cutting and Uniform Dispersion
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Solution Overview
Problem
Existing methods for joining carbon or glass fiber strands to facilitate continuous operation in producing chopped strand mats result in unevenness, contamination, and reduced cutability, leading to defects in molded articles.
Innovation Solution
A jointed strand comprising a superposed portion in which fibers are oriented in one direction, with a joint portion having a slit and interlaced monofilaments at a joint spot orthogonal to the fiber orientation, reducing the number of monofilaments and improving cutability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strands are jointed by making a knot, then the strands are connected, but the knot may remain in the SMC or stampable sheet causing defects, and the cutability is deteriorated
Solution Approach 1:
The joint portion is divided into multiple joint spots (first joint spot, second joint spot, etc.) distributed along the fiber orientation direction. This segmentation prevents the formation of a single large knot that would contaminate the product, while still achieving reliable strand connection through multiple smaller interlacing points.
Solution Approach 2:
The harmful knot structure is extracted and replaced with a slit structure. The slit extends in the fiber orientation direction and prevents monofilaments from forming interlaced knots, while the joint spots provide the necessary connection without creating product-contaminating structures.
2Strength
If strands are jointed by twisting, then the joint portion is strengthened, but chopped strands are not cut properly and are sprayed as lumps causing areal weight unevenness
Solution Approach 1:
The joint portion is segmented into multiple joint spots rather than a single twisted region. This segmentation allows the strand to maintain strength through distributed interlacing while preventing the formation of a continuous twisted structure that would resist cutting and cause lump formation.
Solution Approach 2:
The twisting action is extracted and replaced with a slit structure combined with localized joint spots. The slit prevents the formation of a continuous twisted structure, while the joint spots provide localized strength without compromising the cutability of adjacent chopped strands.
3Reliability
If air splicer is used to interlace monofilaments, then strands are connected, but the number of monofilaments at joint portion increases causing large chopped strand lumps
Solution Approach 1:
The joint portion is divided into multiple joint spots with fewer monofilaments at each spot, rather than having all monofilaments interlaced in a single location. This segmentation reduces the number of monofilaments at any given point, preventing the formation of large chopped strand lumps while maintaining overall connection reliability.
Solution Approach 2:
The excessive monofilament interlacing is extracted and replaced with a slit structure. The slit prevents the superposition and interlacing of large numbers of monofilaments, while the joint spots provide necessary connection with controlled, reduced monofilament counts.
4Ease of operation
If joint portion is made rigid to hold flat strand shape, then handling is improved, but cutability is deteriorated
Solution Approach 1:
The joint portion is segmented into multiple joint spots rather than a single rigid structure. This segmentation provides sufficient structural support for handling while maintaining flexibility and cutability, as the distributed structure does not create a continuous rigid barrier to cutting.
Solution Approach 2:
The rigid structure is extracted and replaced with a slit combined with localized joint spots. The slit provides structural definition for handling, while the localized joint spots provide minimal interference with the cutting process, preserving cutability.
Data Source
AI summary
A jointed strand includes a superposed portion in which a first strand end in which fibers are oriented in one direction and a second strand end in which fibers are oriented in one direction are superposed; and a joint portion in which fibers of the first strand and the second strand are interlaced at the superposed portion, wherein the joint portion has a slit extending in a fiber orientation direction and a joint spot adjacent to the slit at one location or a plurality of locations aligned in a direction orthogonal to the fiber orientation direction, and monofilaments of the first strand and the second strand are interlaced at the joint spot.