Planet Carrier Assembly via Segmented Cage and Post-Machining Alignment
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Solution Overview
Problem
The assembly of a planet carrier with a cage and a cage carrier in turbomachines is challenging due to static redundancy, requiring precise manufacturing tolerances that are difficult to achieve and costly to implement.
Innovation Solution
A method for manufacturing a planet carrier with an annular cage and cage carrier, involving separate production with excess thickness, alignment, and machining to achieve a single-piece assembly, using tools for precise positioning and attachment to ensure accurate alignment and robust assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the planet carrier is assembled from a cage and a cage carrier with multiple fingers and saddles, then the assembly is robust and flexible, but the assembly process becomes very difficult due to static redundancy and requires extremely tight manufacturing tolerances
Solution Approach 1:
The planet carrier is divided into two main segments: a cage with posts and saddles, and a cage carrier with fingers. These segments are designed to be assembled together through through-openings, allowing the complex structure to be built from manageable parts while maintaining structural integrity through the interconnected finger-saddle joints
Solution Approach 2:
Connection axles serve as intermediary elements that pass through the through-openings of the saddles and fingers to join the cage and cage carrier segments. These axles act as mediators that transmit forces and enable the assembly of the two segments while accommodating the static redundancy of the structure
2Manufacturing precision
If tight manufacturing tolerances are used to ensure proper alignment of through-openings, then the assembly accuracy is improved, but the manufacturing cost increases considerably
Solution Approach 1:
The through-openings in the saddles and fingers are pre-formed with generous tolerances during the manufacturing of individual components. The critical alignment is then achieved through the assembly process itself, where connection axles and assembly fixtures establish the precise relative positions of the cage and cage carrier segments, eliminating the need for expensive tight-tolerance manufacturing
Solution Approach 2:
The assembly structure itself provides the alignment function through the geometric constraints of the through-openings and connection axles. The design allows components to self-align during assembly through the natural fit of the connection elements, reducing dependency on pre-established precise manufacturing tolerances
Data Source
AI summary
The invention relates to a method for assembling (S) a planet carrier (16), comprising the following steps: separately producing (S1) the cage (20) and the cage carrier (30), providing a machining allowance at one element from among the through-holes (23, 25) in at least one upright (21) of the cage (20) or the through-hole (32) in a finger bar (31) of the cage carrier (30), and/or at one element from among a bearing seat (26) or a rolling bearing seat (41, 42); assembling (S2) the cage (20) and the cage carrier (30) and securing (S3) same to produce a one-piece assembly; determining (S4) the position of a reference axis (Y1, Y2) linked to the cage (20), to the cage carrier (30) and/or to the shaft (40); and, taking account of the position of the reference axis (Y1, Y2), machining (S5) all or part of the machining allowances.