Metallic Mold Splitting Structure for Rolling Element Belt
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Solution Overview
Problem
Existing rolling element accommodating belts for linear guide apparatuses face issues with underfill resin formation and burr generation during manufacturing, leading to noise, abrasion, and operational inefficiencies due to residual gas and shrinkage problems.
Innovation Solution
A metallic mold with a splitting structure that allows gas venting at the end portion of the spacer, and a design where the parting line is set on the non-contact face of the spacer portion, preventing underfill and burr formation, and enabling smooth operation without requiring precise control of forming conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If injection molding is conducted using a conventional metallic mold without a splitting structure, then the manufacturing process is simple, but residual gas remains in the end portion of the spacer portion causing underfill defects
Solution Approach 1:
The metallic mold is divided into multiple segments including a movable core and a cavity, with a splitting structure that creates a gas vent passage. This segmentation allows residual gas to escape during injection molding, preventing underfill defects in the spacer portion while maintaining a manageable mold structure.
Solution Approach 2:
A gas vent passage is introduced as an intermediary element within the mold structure. This passage serves as a mediator that allows residual gas to escape from the molding cavity during injection, preventing gas entrapment and underfill defects without requiring complex external vacuum systems.
2Ease of manufacture
If the dividing line of the metallic mold is positioned at the peripheral portion of the spacer portion, then the mold structure is simplified, but burr is generated on the rolling element accommodating belt
Solution Approach 1:
The dividing line of the metallic mold is strategically positioned at the end portion of the spacer portion rather than the peripheral portion. This localized placement ensures that the parting line does not intersect with the rolling element contact surface, preventing burr generation on critical surfaces while maintaining overall mold simplicity.
3Strength
If the rolling elements are tightly contacted with each other due to shrinkage during forming, then the structural integrity is improved, but oil or water is absorbed after molding completion
Solution Approach 1:
The mold structure incorporates a splitting design with a movable core that allows for controlled shrinkage compensation during the cooling phase. By adjusting the positioning and movement of the core and cavity segments, the mold maintains appropriate clearance between rolling elements after shrinkage, preventing excessive tight contact that would lead to oil or water absorption, while still ensuring structural integrity.
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 effectively prevents underfill resin formation and burr generation, ensuring a stable and smooth operation of the rolling element accommodating belt, reducing manufacturing costs and enhancing the quality of the linear guide apparatus.
Implementation Method 1
at least one of the upper and the lower mold has a splitting structure in which a splitting position is located at a position where an end portion of at least one side of inner and outer circumferential direction of the infinite circulating passage of the spacer portion is formed
Implementation Method 2
when melted resin material is poured from a gate into a product configuration portion in a metallic mold
Data Source
AI summary
The metallic mold 90 includes a product configuration portion 93 formed between an upper mold 91 and a lower mold 92. This product configuration portion 93 is composed so that a rolling element accommodating belt 50 formed by this product configuration portion 93 can include spacer portions interposed between balls adjacent to each other in an infinite circulating passage and also include connecting arm portions for connecting the spacer portions to each other and so that the balls can be aligned in the alignment direction in the infinite circulating passage. The upper mold 91 has a splitting structure. In this splitting structure, a splitting position BL is set at a position passing through a position 91t for forming an end portion on the outer circumferential side in the inner and outer circumferential direction of the infinite circulating passage of the spacer portions 51.