Segmented Center Die Mold for Flexible External Gear Release
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Solution Overview
Problem
The existing molds for flexible externally toothed gears in strain wave gearing face challenges in ensuring smooth mold-opening and mold-releasing operations due to insufficient punching allowance, leading to potential meshing defects and shortened die life.
Innovation Solution
A mold configuration with a center die divided into multiple circumferentially spaced divided dies and a divided die movement mechanism that allows each die to retract radially inward during mold-opening, ensuring smooth removal without excessive force, and a mechanism to prevent molding material from entering gaps between the divided dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the center die is designed with a shaping outer peripheral surface to define the inner peripheral surface shape of the cylindrical part, then the inner diameter of the cylindrical part can be maintained uniformly along the axial direction, but it becomes difficult to provide a taper on the shaping outer peripheral surface to obtain sufficient punching allowance for smooth mold-opening operation
Solution Approach 1:
The center die is divided into multiple divided dies arranged circumferentially. Each divided die can be independently retracted radially inward during mold-opening, creating clearance between the divided dies and the molded product. This segmentation allows the mold-opening operation to proceed smoothly without requiring a taper on the shaping outer peripheral surface, thus maintaining uniform inner diameter while improving ease of operation.
2Ease of operation
If the center die is divided into multiple divided dies with a divided die movement mechanism, then punching allowance is improved for smooth mold-opening and mold-releasing operations, but the device complexity increases due to the additional mechanism required
Solution Approach 1:
The divided dies are designed with a movement mechanism that allows them to dynamically adjust their position during the molding cycle. During molding, the divided dies are positioned to define the inner peripheral surface shape with high precision. During mold-opening and mold-releasing operations, the divided dies retract radially inward to create punching allowance. This dynamic adjustment enables the system to achieve smooth operations without excessive complexity.
3Duration of action of stationary object
If the divided dies are retracted radially inward during mold-opening, then the punching allowance is increased to prevent die life shortening, but the manufacturing precision of the inner peripheral surface shape may be affected
Solution Approach 1:
The divided dies dynamically adjust their position based on the operational phase. During the molding phase, the divided dies are positioned to ensure high manufacturing precision of the inner peripheral surface shape. During mold-opening and mold-releasing operations, the divided dies retract radially inward to create punching allowance and prevent die life shortening. This dynamic positioning allows the system to maintain high precision while extending die life.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A mold (100) used for molding a flexible external gear (3) of a strain wave gearing (1) is provided with an outer die (110) and a center die (120) that defines the inner peripheral surface shape of the flexible externally toothed gear (3). The center die (120) is provided with a die divided part (122) composed of a plurality of divided dies (121) divided in the circumferential direction. Each divided die (121) can be retracted by a divided die movement mechanism (140) from a molding position (121A) to a retracted position (121B) that is radially inward from the molding position. When the mold is opened after molding, the die divided part (122) as a whole is slightly contracted by retracting each divided die (121) to the radially inward retracted position (121B). The center die (120) can be extracted from the outer die (110) without applying excessive force.