Composite Knitting Bar Molded by Internal Pressure
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Solution Overview
Problem
Existing methods for producing plastic knitting tool bars face challenges in achieving mechanical stability while minimizing mass, as they often require additional components that increase weight and require frequent changes to press molds for design modifications.
Innovation Solution
The method involves using a press mold with a hose that generates internal pressure to shape the plastic, allowing for reinforcement and design flexibility without adding mass, using a prepreg with fibers aligned in different directions for enhanced strength, and maintaining pressure with a temperature-resistant hose that remains inside the bar.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a bar is made from light metal such as magnesium or aluminum, then the mass is reduced compared to traditional materials, but the mass remains considerable and mechanical stability is insufficient
Solution Approach 1:
The patent applies composite materials by combining plastic with fiber reinforcements (such as glass fibers, carbon fibers, or aramid fibers) to create a fiber-reinforced plastic bar. This composite structure provides both lightweight properties and high mechanical stability, resolving the contradiction between reducing mass and maintaining strength. The fiber reinforcement embedded in the plastic matrix delivers superior strength-to-weight ratio compared to traditional light metals.
2Strength
If fiber-reinforced plastic strips are laid flat and overlapping to form a hollow profile, then mechanical stability is improved, but additional mass is introduced with the shaped body required for manufacturing
Solution Approach 1:
The patent extracts and eliminates the need for a separate shaped body (abutment) by using the hollow profile itself as the manufacturing support structure. The hollow profile is formed directly from the fiber-reinforced plastic strips during the molding process, removing the additional mass that would be required for a separate shaped body while maintaining mechanical stability.
Solution Approach 2:
The patent merges the functions of the hollow profile and the manufacturing abutment into a single integrated structure. The hollow profile serves both as the structural component providing mechanical stability and as the support structure during manufacturing, eliminating the need for a separate shaped body and reducing overall mass.
3Strength
If open profiles are assembled to form the body of the knitting tool bar, then high mechanical stability is achieved, but changing the design requires changing the press mold
Solution Approach 1:
The patent segments the bar into modular components including the hollow profile, fiber reinforcements, and integrated abutment structures. This segmentation allows individual components to be independently designed and adjusted without requiring changes to the entire press mold, enabling design flexibility while maintaining mechanical stability through the modular assembly.
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 results in a lightweight yet stable plastic knitting tool bar with improved mechanical properties and the ability to easily modify the design without changing the press mold, achieving high strength and stability with reduced material usage.
Implementation Method 1
the interior is subjected to internal pressure during pressing by means of a pressure fluid
Implementation Method 2
the internal pressure, which can be generated by a pressurized fluid, for example compressed air or a liquid
Implementation Method 3
A prepreg is a flat semi-finished plastic product in which reinforcing fibers are embedded in a plastic matrix. With a UD prepreg (UD stands for unidirectional), the fibers all have the same preferred direction. Such a prepreg is cured in the press mold under pressure and optionally also under elevated temperature and/or with the release of heat.
Data Source
Figure 1~7
Figure 8~10
AI summary
A needle bar is made from a pre-preg with unidirectional fiber reinforcement (10) by forming in a mold (2). The hollow space in the bar cross-section is produced by folding the pre-preg over a tube (12). Once the assembly is in the mold, the tube is inflated by air or hydraulic pressure to impose the required shape. After molding, the tube is left in position and forms part of the needle bar. An independent claim is included for a needle bar with a solid mounting section (11, 13) and a hollow section with an internal tube (12) made in this way from a pre-preg. The pre-preg includes several layers of unidirectional reinforcement, the directions changing from layer to layer.