Ball Bearing Ring Injection Molding Segmentation
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Solution Overview
Problem
Existing methods for producing ball bearing rings using injection molding result in protruding separating markings on the circumference, which can impair the movement of balls in the bearing, as folding cores used in prior art methods create these markings during demolding.
Innovation Solution
A device and method that divides the ball bearing ring into two parts produced by two mold cores, eliminating the need for folding cores and using embossing plates to reduce shrinkage and achieve narrow tolerances, allowing the parts to be assembled without gaps and avoiding blowholes, sink marks, and weld lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If folding cores are used to produce ball bearing rings with undercuts, then the demolding process is enabled, but protruding separating markings are created on the circumference
Solution Approach 1:
The invention divides the ball bearing ring into two separate parts (first and second ball bearing ring parts) produced by two separate mold cores. This segmentation eliminates the need for folding cores that cause separating markings, as each mold core produces a complete half-section without requiring collapse during demolding. The two parts are then joined together to form the complete ball bearing ring.
2Productivity
If folding cores are used to enable demolding, then production is possible, but the individual segments create separating markings that impair ball movement
Solution Approach 1:
The ball bearing ring is segmented into two production parts that are manufactured separately and then joined. This approach maintains production capability while eliminating the harmful separating markings that would otherwise impair ball movement and bearing reliability.
Solution Approach 2:
The invention introduces connecting elements (protrusions and recesses) as intermediaries to join the two ball bearing ring parts. These connecting elements ensure a precise and reliable connection that eliminates gaps and separating markings at the joint, thereby maintaining bearing performance while enabling production.
3Manufacturing precision
If embossing plates are used to compress injected plastic material, then shrinkage is reduced and narrow tolerances are achieved, but device complexity increases
Solution Approach 1:
The embossing plates perform preliminary compression of the injected plastic material during the molding process itself, before demolding. This preliminary action reduces shrinkage and ensures narrow tolerances are achieved during formation, eliminating the need for post-processing adjustments.
Solution Approach 2:
The embossing plates serve multiple functions: they compress the plastic material to reduce shrinkage, they form the final dimensional tolerances, and they create the connecting elements on the ball bearing ring parts. This multi-functionality reduces device complexity by combining several operations into single components.
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 solution produces low-stress, distortion-free ball bearing ring parts that can be easily assembled into a cohesive ball bearing ring, avoiding the issues of protruding separating marks and achieving precise tolerances.
Implementation Method 1
Due to the fact that the embossing plate is part of a piston that can be displaced relative to the opposite mold core, a uniform compression of the injection weight into the casting space can be achieved
Implementation Method 2
The shrinkage of the injected plastic material is reduced by the arranged embossing plates, whereby very narrow tolerances are achieved
Data Source
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Figure 7~10
AI summary
The apparatus has a housing (1) in which two mold cores (21) are arranged. The mold cores limit casting spaces (4) for ball bearing ring parts. A nozzle (5) is arranged for introducing plastic material in the casting spaces. Two embossing plates are arranged to limit one of the two casting spaces and moved relative to the mold cores. Volume of the casting spaces is varied. A mold element (35) is arranged at the embossing plates. Each embossing plate is a component of a piston (3) and moved relative to the mold cores. An independent claim is also included for a method for manufacturing ball bearing rings.