Cam Follower Insert Design Eliminates Caulking

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Solution Overview

Problem

The assembly of classical cam followers is time-consuming and costly due to the need for caulking and machining of the tappet body, which complicates the manufacturing process.

Innovation Solution

A mechanical system comprising a support element, a pin, and a roller, where an insert made of three separate parts with holding members and a connecting portion allows easy assembly by receiving the pin ends in blind cylindrical recesses, reducing production costs and eliminating the need for caulking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the pin ends are caulked to create a mechanical connection in the tappet bores, then the connection strength is improved, but the assembly time and manufacturing complexity increase

Engineering Contradiction:
Improveconnection strengthVSAvoidassembly time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The patent replaces the permanent caulked pin connection with a disposable retaining ring that can be easily installed and removed. The retaining ring provides sufficient connection strength for the application while allowing for quick assembly and disassembly without requiring caulking operations, thus resolving the contradiction between connection strength and assembly time.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent extracts the caulked pin connection from the assembly process and replaces it with a retaining ring system. This separation allows the pin to be independently positioned and secured without requiring plastic deformation or complex machining operations, thereby reducing assembly time while maintaining connection integrity.

Inventive Principle:
Principle #2Taking out (Extraction)

2Manufacturing precision

If the tappet body is machined to accommodate the pin and roller assembly, then the manufacturing precision is improved, but the production cost and time increase

Engineering Contradiction:
Improvetappet machining precisionVSAvoidproduction cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent segments the tappet assembly into modular components: the tappet body, the pin-roller assembly, and the retaining ring. This segmentation allows each component to be manufactured separately using simpler processes, reducing the need for complex machining operations on the tappet body while maintaining overall assembly precision through standardized interfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces the retaining ring as an intermediary component that mediates between the pin-roller assembly and the tappet body. This intermediary element simplifies the machining requirements of the tappet body by providing a standardized mounting interface, thereby reducing production costs and complexity while maintaining manufacturing precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If the pin is inserted through the flanges with radial recesses for caulked ends, then the mechanical connection is strengthened, but the device complexity and assembly difficulty increase

Engineering Contradiction:
Improvemechanical connection strengthVSAvoidassembly complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent replaces the complex caulked pin connection with a simple retaining ring that can be easily installed and removed. The retaining ring provides sufficient mechanical connection strength for the application while dramatically simplifying the assembly process, eliminating the need for radial recesses and caulking operations.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

Instead of securing the pin to the flanges through caulking (traditional approach), the patent inverts the approach by using a retaining ring that secures the pin-roller assembly from the opposite side. This inversion simplifies the assembly process by eliminating the need for complex radial recesses and caulking operations while maintaining connection strength.

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentEP3026231B1Mechanical system forming a cam follower or a rocker arm, injection pump or valve actuator comprising such a mechanical system and method for manufacturing such a mechanical system
Publication Date: 2020.08.12 AB SKF SKF PATENT DEPARTMENT
  • EP3026231B1 patent drawingFigure 1
  • EP3026231B1 patent drawingFigure 2

AI summary

This mechanical system (1) forms a cam follower or a rocker arm and comprises a support element (10), a pin extending between two opposite ends along a first axis (X1) and supported by the support element (10), and a roller (40) mounted on the pin, movable in rotation relative to the pin around the first axis (X1) and adapted to roll on a cam (2). The mechanical system further includes an insert (20) made from separate parts and including holding members (20A, 20B) supporting the pin ends.