Columnar Thermoplastic Resin Pellets for Electric Cable Sheath
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Solution Overview
Problem
Existing methods for manufacturing electric cables using thermoplastic resin pellets do not adequately address the flowability of pellets from the hopper to the cylinder, leading to unevenness in the thickness of the sheath.
Innovation Solution
The use of columnar thermoplastic resin pellets with a specific cross-sectional shape ratio (a/b ≥ 1.0 to ≤ 2.6) and a hopper design with a unit height volume ratio to pellet volume greater than 16, enhancing the flowability and reducing discharge time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thermoplastic resin pellets are used, then the pellets can be supplied to the molding machine, but the flowability from hopper to cylinder is insufficient causing uneven sheath thickness
Solution Approach 1:
The patent changes the geometric parameters of the pellets by controlling the ratio of longer diameter to shorter diameter (a/b) to be 1.0 or more and 2.6 or less, and by controlling the ratio of unit height volume of cylindrical portion to pellet volume (α) to be more than 16. These parameter changes optimize both flowability and sheath thickness uniformity simultaneously.
2Productivity
If the hopper volume ratio is not optimized, then the hopper can be designed simply, but the discharge time increases and flowability decreases
Solution Approach 1:
The patent optimizes the hopper design by setting the ratio α of unit height volume of cylindrical portion to pellet volume to be more than 16. This parameter change reduces discharge time and improves flowability without requiring complex hopper structures.
3Ease of manufacture
If pellets with inappropriate shape are used, then the pellets can be manufactured easily, but the bulk density is inappropriate causing poor spreading behavior
Solution Approach 1:
The patent controls the shape parameters of pellets by specifying the ratio a/b of longer diameter to shorter diameter (1.0 ≤ a/b ≤ 2.6) and the ratio α of hopper volume to pellet volume (α > 16). These parameter changes ensure appropriate bulk density and spreading behavior while maintaining manufacturability.
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 stabilizes the moldability of the sheath and reduces thickness unevenness by optimizing the flowability of pellets, thereby improving the production efficiency and yield of electric cables.
Implementation Method 1
melting the thermoplastic resin pellet in the cylinder to supply molten resin to the die
Implementation Method 2
extruding the molten resin from the die to form the sheath on the core wire
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
If a and b are respectively the major diameter and the minor diameter of a cross-sectional shape obtained by cutting a columnar thermoplastic resin pellet along a plane orthogonal to the height direction of the pellet, a ratio a/b of the major diameter a to the minor diameter b is at least equal to 1.0 and at most equal to 2.6. A ratio α of the volume per unit height of an opening portion of a hopper of a molding machine into which the thermoplastic resin pellet is introduced relative to the volume of the thermoplastic resin pellet is greater than 16.