Rolling Body Compression Molding With Annular Concaves

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Solution Overview

Problem

Conventional methods for manufacturing cylindrical rolling bodies result in excess material and recesses on the outside section and end surfaces, leading to difficulties in handling scrap material and high processing costs due to the need for post-processing removal.

Innovation Solution

A molding device with a pair of molds featuring annular concave sections and knockout pins allows for relative displacement, minimizing excess material and recesses by promoting material flow into the molds and reducing the need for post-processing removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional compression molding is used to manufacture cylindrical rolling bodies, then the manufacturing process is simple, but excess material and recesses are generated on the outside section and end surfaces, leading to high processing costs and difficult scrap handling

Engineering Contradiction:
Improvemolding process simplicityVSAvoidsurface quality (excess material and recesses)
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The mold cavity is segmented into multiple regions: a main molding cavity and additional concave sections positioned at specific locations. These concave sections are designed to receive and contain the excess material that is extruded during compression molding, thereby preventing the formation of harmful protrusions and recesses on the final product surface.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The concave sections act as intermediary structures between the molding force and the intermediate material. They provide a designated pathway and containment zone for the material flow, guiding the extruded material into controlled locations rather than allowing it to form defects on the product surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If conventional compression molding is used, then the molding device structure is simple, but post-processing removal of excess material is required, increasing processing time and costs

Engineering Contradiction:
Improvemolding device structureVSAvoidpost-processing time
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The mold design incorporates concave sections that are pre-configured to capture and contain the excess material during the compression molding process itself. This preliminary action of providing designated material containment zones eliminates the need for subsequent post-processing operations to remove excess material, thereby reducing processing time and costs.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If compression molding is performed without annular concave sections, then the molding process is straightforward, but recesses are formed on the end surfaces of the intermediate material

Engineering Contradiction:
Improvemolding process simplicityVSAvoidend surface quality
Core Design Contradiction:
Ease of manufactureVSShape

Solution Approach 1:

The mold design applies local quality by positioning concave sections with specific geometries at particular locations within the mold cavity. These locally optimized structures are designed to match the expected material flow patterns and pressure distributions during compression molding, thereby preventing recess formation on the end surfaces while maintaining overall process simplicity.

Inventive Principle:
Principle #3Local quality

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

The solution effectively prevents excess material and recesses from forming, reducing processing time and costs by ensuring efficient compression molding and easy handling of the intermediate material.

Implementation Method 1

the intermediate material is plastically deformed by compressing the intermediate material by bringing the pair of molds close to each other to compression mold the intermediate material

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

the intermediate material is plastically deformed by compressing the intermediate material

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP3628413B1Molding device for manufacturing cylindrical rolling body, manufacturing method for cylindrical rolling body, manufacturing method for rolling bearing, manufacturing method for vehicle, and manufacturing method for mechanical apparatus
Publication Date: 2021.11.24 NSK LTD
  • EP3628413B1 patent drawingFigure 1
  • EP3628413B1 patent drawingFigure 2
  • EP3628413B1 patent drawingFigure 3

AI summary

With respect to the manufacture of cylindrical rolling bodies, excess material on an outside section in the radial direction and recesses in both end surfaces in the axial direction are not generated as much as possible in the intermediate material that is removed from a molding device for performing compression molding. Annular concave sections 27 are provided on the inner-circumferential surfaces 20a of molding concave sections 19a provided in a stationary-side mold 17a and a movable-side mold 18a. The stationary-side mold 17a and the movable-side mold 18a are brought close to each other in the axial direction while compressing the intermediate material 23 in a state in which both side sections in the axial direction of the intermediate material 23 are inserted into the molding concave sections 19a. At this time, a part of the material of the intermediate material 23 is made to enter inside the annular concave sections 27, and undercut sections 32 are formed on the outer side in the radial direction of a compression-molded intermediate material 23b. After that, when removing both side sections in the axial direction of the intermediate material 23b from the inside of the molding concave sections 19a in the axial direction, the undercut sections 32 are drawn through or handled by stepped sections 29 existing at the end sections in the axial direction of the annular concave sections 27.