One-Piece Ballscrew Recirculation Part for Axial Molding
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Solution Overview
Problem
Existing ballscrew mechanisms face manufacturing complexity due to the presence of undercuts in one-piece recirculation parts, making axial molding impossible.
Innovation Solution
A one-piece recirculation part design with lumens and deflectors that allow axial molding by avoiding undercuts, featuring a bottom, recirculation path, deflectors, and lumens that enable guide faces to be molded without interference, using a two-shell mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-piece recirculation part is designed with deflectors and guide faces to guide balls along an S-shaped path, then ball guidance function is improved, but manufacturing complexity increases due to undercuts that prevent axial molding
Solution Approach 1:
The patent introduces lumens (internal cavities) that extend in the axial direction, allowing the deflector to be positioned in a different spatial arrangement. The lumen creates a void space that eliminates the undercut condition, enabling the deflector to be molded axially without requiring complex side-actions or breaks in the mold. This dimensional reorganization of the part geometry resolves the conflict between functional requirements and manufacturability.
Solution Approach 2:
The patent extracts material to create lumens (cavities) within the recirculation part body. By removing material in specific locations, the design eliminates undercuts that would otherwise prevent axial molding. The lumen acts as a void space that allows the deflector to be formed without creating interfering geometric features, thus simplifying the molding process while maintaining the deflector's ball-guiding function.
2Ease of manufacture
If a one-piece recirculation part is made from two half-parts connected by a joint to enable molding, then manufacturability is improved, but device complexity increases
Solution Approach 1:
The patent segments the mold cavity into two separate shells (first and second mold shells) that can open and close axially. This segmentation of the molding tool, rather than the part itself, allows the complex geometry with deflectors and lumens to be formed in a single axial molding action. The two-shell mold design enables each shell to form complementary surfaces that together create the complete recirculation part without requiring the part to be split into multiple components.
3Ease of manufacture
If material is removed to create lumens in the recirculation part, then manufacturing simplicity is improved, but use of material increases
Solution Approach 1:
The patent implements lumens as nested cavities within the recirculation part structure. These internal voids are formed by the molding process itself, where the mold shells create negative spaces that result in lumens after demolding. This nesting approach eliminates the need for secondary material removal operations, as the lumens are formed directly during the primary molding process, thereby avoiding additional material waste that would occur with post-manufacturing machining or drilling.
Data Source
AI summary
A one-piece recirculation part intended to be housed in a cavity of a threaded member of a ballscrew mechanism comprises a bottom, facing in a reference direction of a reference axis, a recirculation path facing in the opposite direction and designed to pass through a thread of the threaded member, and at least one deflector, projecting from the recirculation path in the opposite direction to the reference direction. The deflector forms a guide face located at a distance from the recirculation path and facing in the reference direction, opposite a lumen in the one-piece part which extends parallel to the reference axis and opens onto the bottom and the recirculation path. When projected orthogonally onto a reference plane perpendicular to the reference axis, the first lumen surrounds or coincides with the guide face of the first deflector.