Timing Chain Guide Base Frame Casting Without Drafts
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Solution Overview
Problem
Conventional guides for traveling transmission mediums, such as roller chains, face issues with instability and uneven wear due to a peaked shoe-supporting surface caused by mold drafts, requiring additional machining steps that increase production costs and weight, and lead to mold distortion and reduced lifespan.
Innovation Solution
A three-part mold is used to cast an I-shaped base frame without drafts, allowing for accurate and stable shoe mounting, eliminating the need for post-casting machining, reducing weight, and improving mold opening resistance and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-part mold with drafts is used to cast the base frame, then the mold opening is facilitated, but a peaked shape is formed on the shoe-supporting surface causing shoe instability and uneven wear
Solution Approach 1:
The mold is divided into three separate parts (first mold part, second mold part, and third mold part) instead of using a conventional two-part mold. The third mold part specifically forms the shoe-supporting surface without requiring drafts, while the first and second mold parts can be easily separated. This segmentation allows the shoe-supporting surface to be formed with high precision while facilitating mold opening through the first and second parts.
2Ease of manufacture
If drafts are formed in the mold cavity to facilitate mold opening, then the mold can be opened easily, but a central peak is formed in the shoe-supporting surface requiring additional machining
Solution Approach 1:
The mold is divided into three separate parts (first mold part, second mold part, and third mold part) instead of using a conventional two-part mold. The third mold part specifically forms the shoe-supporting surface without requiring drafts, while the first and second mold parts can be easily separated. This segmentation allows the shoe-supporting surface to be formed with high precision while facilitating mold opening through the first and second parts.
3Manufacturing precision
If cutting or machining is performed to remove drafts from the shoe-supporting surface, then the shoe mounting accuracy is improved, but the production cost and labor increase
Solution Approach 1:
The third mold part is designed to form the shoe-supporting surface with the correct flat geometry directly during the casting process, eliminating the need for subsequent machining or cutting operations. This preliminary action ensures that the shoe-supporting surface is produced with the required precision in the initial casting step, avoiding additional manufacturing steps.
4Ease of manufacture
If the mold is opened after the base frame has cooled, then the casting can be removed, but thermal shrinkage and distortion occur reducing mold life
Solution Approach 1:
The mold is divided into three separate parts (first mold part, second mold part, and third mold part) instead of using a conventional two-part mold. The third mold part specifically forms the shoe-supporting surface without requiring drafts, while the first and second mold parts can be easily separated. This segmentation allows the shoe-supporting surface to be formed with high precision while facilitating mold opening through the first and second parts.
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 simplifies production, reduces costs, enhances accuracy, and extends mold life by avoiding thermal shrinkage and distortion, ensuring stable shoe mounting and smooth mold opening.
Implementation Method 1
since, in the process of casting the conventional base frame 520, the mold is opened after the base frame has cooled, thermal shrinkage can occur, and loads applied during separation of the mold parts P1 and P2 can cause distortion of the casting
Data Source
AI summary
A guide for a traveling transmission medium such as a timing chain comprises a resin shoe for sliding contact with the transmission medium, supported on a base frame having an two flanges and a web in an I-shaped cross-section. The base frame is produced from aluminum by die casting, using a three-part mold. Two parts of the mold cooperate to form a part of the mold cavity that forms one of the flanges and the web of the base frame, and a third part of the mold cooperates with the first two parts to form a part of the cavity in which the other flange of the base frame is formed without a draft.