Seal Device Slide Ring Parting Line Leakage Prevention
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Solution Overview
Problem
Conventional sealing devices face issues with sealability due to damaged portions formed by parting lines and through-cuts, leading to potential leakage channels when a slide ring with a step cut shape is injection molded, causing wear on the back ring and compromising long-term sealing performance.
Innovation Solution
The sealing device features a slide ring with a through-cut in a step cut shape, where the parting lines formed during molding are arranged such that they do not overlap with the circumferential cut at the junction surface with the back ring, preventing communication between damaged portions and thus avoiding leakage channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a slide ring with a through-cut in step cut shape is injection molded, then the slide ring can be manufactured at lower cost with improved attaching ability, but parting lines and damaged portions are formed on the surface, leading to wear on the back ring and potential leakage channels
Solution Approach 1:
The patent applies preliminary action by strategically positioning the circumferential cut and axial cuts in advance during the molding process design phase. The circumferential cut is positioned to start from a location that avoids parting lines, and axial cuts are oriented to extend toward端面 (end faces) rather than perpendicular to the sliding surface, preventing damaged portions from communicating with each other before assembly occurs
Solution Approach 2:
The patent converts the harmful effect of parting lines and damaged portions into a beneficial outcome by strategically positioning cuts so that damaged portions do not communicate. The circumferential cut creates expansion for better attaching ability while the specific positioning ensures damaged portions remain isolated, transforming what would be leakage pathways into non-critical surface features that do not compromise sealing
2Ease of operation
If the circumferential cut and axial cuts are positioned to improve attaching ability, then the slide ring can be easily fitted into the annular concave groove, but damaged portions on the back ring junction surface may communicate to form leakage channels
Solution Approach 1:
The patent applies local quality by making the cut positioning highly specific to local geometric relationships. The circumferential cut is positioned at a precise location on the circumference, and axial cuts are oriented at specific angles toward端 faces, creating localized damage patterns that do not interconnect. This localized control of damage distribution maintains both attaching ability and sealability
3Strength
If a high strength material is adopted for the slide ring, then the durability is improved, but it becomes difficult to fit the slide ring into the annular concave groove
Solution Approach 1:
The patent applies segmentation by introducing through-cuts that divide the slide ring structure into segments. The circumferential cut creates a discontinuity that allows the ring to expand outward, while axial cuts create additional segmentation that facilitates deformation. This segmented structure enables high-strength materials to be fitted into grooves by allowing controlled expansion at cut locations without compromising overall structural integrity
Data Source
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AI summary
[Object] To provide a sealing device which is free of such a situation that a damaged portion of a back ring caused by a parting line at a surface of a slide ring is communicated with a damaged portion of the back ring caused by a through-cut of the slide ring to thereby form a leakage channel. [Solving means] A sealing device (1) having: a slide ring (2) made of a resin; and a back ring (3) made of an elastic body; the sealing device (1) being configured to seal an annular gap between a housing having a shaft hole, and a shaft inserted through the shaft hole; wherein the slide ring (2) has: a through-cut (22), comprising a circumferential cut (22A), and axial cuts (22B) extending from both ends of the circumferential cut, along the axial direction; and multiple parting lines (23A, 23B) formed on a surface of the slide ring (2), where the parting lines (23A, 23B) have been formed by injection molding the slide ring by a mold dividable into multiple partial molds at multiple junction of molds on the mold, and by subsequently parting the mold at the junction of molds; and wherein the parting lines (23A, 23B) are arranged so that the parting lines (23A, 23B) are not overlapped with the circumferential cut (22A) exposed at the junction surface of the slide ring (2) with the back ring (3), throughout the lengthwise direction of the circumferential cut.