Solid Bearing Cage Cycloidal Machining

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Solution Overview

Problem

The high production costs and material requirements for solid cages in rolling bearings, particularly due to the complex and costly process of milling out windows in solid components, necessitate a more efficient manufacturing method that balances accuracy and cost.

Innovation Solution

A method involving cycloidal machining steps to form pocket sides in a solid component, using a cutting tool guided along cycloid paths to create precise, high-quality pockets without scraping, allowing for the production of solid cages with trapezoidal or rectangular cross-sections, suitable for roller bearings, with reduced finishing needs and lower tolerance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional separating processes (milling) are used to manufacture solid cages, then windows can be created in the solid component, but production costs increase and manufacturing complexity increases due to sequential milling of multiple windows

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidproduction cost
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The manufacturing process is segmented into two distinct phases: rough machining to create component blanks with raw pockets, and precision cycloidal machining to form final pocket sides. This segmentation allows each phase to be optimized independently, reducing overall production cost and complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Raw pockets are pre-formed in the component blank during rough machining before the precision finishing step. This preliminary action removes bulk material in advance, so that the subsequent cycloidal machining only needs to refine the pocket sides, significantly reducing machining time and cost

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If conventional machining methods are used to create pockets in solid components, then pockets can be formed, but surface quality decreases and manufacturing precision decreases due to scraping processes

Engineering Contradiction:
Improveprocess simplicityVSAvoidsurface quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The cycloidal machining process uses periodic oscillating motion of the cutting tool along a cycloid path, which continuously varies the cutting angle and depth. This periodic action ensures consistent surface quality and precise dimensional control while maintaining a simple scraping-like operation

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The cutting parameters (tool path, oscillation amplitude, feed rate, and cutting depth) are precisely controlled and varied during the cycloidal machining process. By optimizing these parameters, high surface quality and manufacturing precision are achieved while keeping the process simple and efficient

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If extensive post-processing is performed to achieve high manufacturing accuracy, then dimensional stability improves, but production time increases and productivity decreases

Engineering Contradiction:
Improvedimensional stabilityVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The cycloidal machining process performs precision finishing in a single continuous operation without interruption or intermediate steps. The tool continuously traces the cycloid path throughout the entire pocket, achieving final dimensional accuracy in one pass and eliminating the need for separate post-processing operations

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The cycloidal machining process is self-finishing, meaning the same process that removes material also creates the final precise surface geometry. The periodic cycloidal motion inherently produces the required surface quality and dimensional accuracy, so no additional service or post-processing is needed

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3380739B1Method for producing a solid component, and a solid component
Publication Date: 2020.03.25 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3380739B1 patent drawingFigure 1
  • EP3380739B1 patent drawingFigure 2a~3
  • EP3380739B1 patent drawingFigure 4a~4c

AI summary

Cages in rolling bearings are used to guide and space apart rolling bodies. The cages are often annular and have windows in which the rolling bodies are arranged. Along with plastic cages and sheet metal cages, solid cages are known which are machined from a solid semifinished product using separating methods. The invention relates to a method for producing a solid component. The production is carried out over two cycloidal machining steps. The solid cage (1) defines a cage rotational axis (K) and has a plurality of webs (2) which form pockets (3) for receiving rolling bodies. Each of the webs (2) has a first and a second web side (5a, b) for contacting the rolling body in the circumferential direction about the cage rotational axis (K). The method has the following steps: producing a cage blank (12), said cage blank (12) having a plurality of blank webs (13) which form blank pockets (14); producing the first web side (5a) using a tool blade (9), said tool blade (9) being guided relative to the cage blank (12) along a first cycloidal path in a first cycloidal machining step, wherein the first web sides (5a) are cut by the tool blade (9) and/or a cutting angle of the tool blade (9) is positive; and producing the second web side (5b) using a tool blade or the tool blade (9), said tool blade (9) being guided relative to the cage blank (12) along a second cycloidal path in a second cycloidal machining step, wherein the second web sides (5b) are cut by the tool blade (9) and/or a cutting angle of the tool blade (9) is positive.