Bearing Cage Injection Layout for Stronger Weld Lines
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Solution Overview
Problem
Existing bearing cage manufacturing methods via injection molding result in weakened weld lines due to non-uniform resin mixing and misorientation of reinforcing fibers, leading to reduced strength and durability, particularly at stress-concentrated areas.
Innovation Solution
A manufacturing method involving a resin injection gate at the pillar part, with a resin reservoir at one region to create a pressure gradient and induce a forcible resin flow, ensuring the reinforcing fibers are aligned parallel to the flow direction at the weld line, thus enhancing the strength of the weld line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If injection molding is performed with a single resin injection gate, then manufacturing simplicity is maintained, but weld line strength is insufficient due to non-uniform resin mixing and fiber misorientation
Solution Approach 1:
The invention segments the single injection gate into multiple resin injection gates (first and second gates) positioned at different locations. This allows independent control of resin flow from each gate, enabling the first resin flow to carry fibers toward the weld line and the second resin flow to fill the remaining cavity, thereby achieving both manufacturing simplicity and improved weld line strength through controlled multi-gate injection
Solution Approach 2:
The invention applies local quality by designing different gate configurations for different regions of the mold cavity. The first resin injection gate is positioned to specifically target fiber delivery to the weld line area, while the second gate handles general cavity filling. This localized optimization ensures that the critical weld line region receives enhanced fiber reinforcement without compromising overall manufacturing efficiency
2Strength
If reinforcing fiber material is added to melted resin, then strength is improved at most areas, but fiber orientation becomes perpendicular to flow direction at weld line, reducing reinforcing effect
Solution Approach 1:
The invention implements preliminary action by using the first resin injection gate to pre-deliver reinforcing fibers to the weld line region before the main cavity filling occurs. The first resin flow is specifically directed to position fibers in the desired orientation at the weld line, and only then does the second resin flow complete the filling, ensuring fibers are already in place and properly oriented before final solidification
Solution Approach 2:
The invention applies inversion by reversing the conventional injection sequence. Instead of filling the cavity first and hoping fibers align naturally, the first gate is used specifically to inject resin with fibers toward the weld line area in advance, then the second gate fills the remaining space. This inverted sequence ensures fiber orientation is controlled at the critical weld line region rather than being a random outcome
3Productivity
If resin flows are merged at opposite position radially facing the injection gate, then cavity filling is completed, but a weld line is formed with decreased strength
Solution Approach 1:
The invention segments the single resin flow into two separate resin flows from different gates. The first resin flow from the first gate is directed to merge with fibers at the weld line region, while the second resin flow from the second gate fills the remaining cavity. This segmentation allows the weld line to form with properly oriented fibers from the first flow rather than being a weak boundary between two flows from a single gate
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 method effectively suppresses the orientation of reinforcing fibers perpendicularly to the flow direction at the weld line, improving the strength and durability of the bearing cage by promoting a forcible resin flow and controlled fiber orientation.
Implementation Method 1
a resin reservoir at one region to create a pressure gradient and induce a forcible resin flow
Data Source
AI summary
The resin injection gate is disposed at the pillar part. When the bearing cage is divided into first and second regions by an imaginary line connecting the resin injection gate and a weld to be formed at a position radially facing the resin injection gate, a resin reservoir that can store therein the melted resin is formed at the pillar part in only one of the regions. A circumferential distance between the resin reservoir and the weld is smaller than a circumferential distance between the resin reservoir and the resin injection gate. A cross-sectional area of a communicating part of the resin reservoir, which is configured to communicate with the pillar part, is equal to or less than a quarter of a cross-sectional area of the resin injection gate.