Remanufacturing Piston Defects via Welding and Machining

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Solution Overview

Problem

Internal combustion engine pistons pose a challenge in remanufacturing as they often require modification to meet technical and aesthetic standards, with existing methods altering material properties and appearing worn, making them unsuitable for commercial reuse.

Innovation Solution

A method involving sorting used pistons into categories for remanufacturing, where defective pistons are repaired by depositing molten welding filler material and machining it to bond with the base material, resulting in pistons with unique or identical material compositions that meet specifications, thus being interchangeable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional remanufacturing techniques are used to repair piston defects, then the technical requirements are met, but the material properties are altered and the component appears worn, reducing aesthetic appeal

Engineering Contradiction:

Improvetechnical sufficiencyVSAvoidaesthetic appeal

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies the copying principle by creating a replica of the original piston surface through welding and machining. The repair process reproduces the original surface geometry and material properties, making the repaired area indistinguishable from the original manufacturing condition. This allows the piston to meet both technical requirements and aesthetic standards without visible wear marks.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent employs parameter changes by carefully controlling welding parameters (temperature, time, material composition) and machining parameters (cutting depth, speed, finish) to restore the piston to its original state. By adjusting these parameters, the repair process achieves both structural integrity and surface quality that match the original manufacturing specifications.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If used pistons are remanufactured to original specifications, then aesthetic appeal is maintained, but the quantity of reusable pistons is limited due to strict sorting criteria

Engineering Contradiction:

Improveaesthetic appealVSAvoidinventory population

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent applies preliminary action by performing welding repairs before final machining and surface finishing operations. This sequence allows defective pistons to be restored to acceptable condition early in the process, enabling them to proceed through subsequent manufacturing steps and enter the replacement inventory, thereby increasing the quantity of reusable pistons.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements discarding and recovering by identifying pistons that would traditionally be discarded due to surface defects, repairing them through welding and machining, and recovering them as serviceable replacement parts. This process transforms previously unusable pistons into valuable inventory assets.

Inventive Principle:

Principle #34Discarding and recovering

3Strength

If welding filler material is deposited to repair piston defects, then material integrity is restored, but the processing time and complexity increase

Engineering Contradiction:

Improvematerial integrityVSAvoidprocessing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent applies mechanics substitution by replacing traditional multi-step mechanical repair methods with a welding-based approach followed by minimal machining. The welding process directly builds up material to replace defective areas, eliminating the need for extensive material removal and subsequent reconstruction operations, thereby simplifying the overall process while maintaining strength.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method effectively repairs defects in pistons, ensuring they meet new standards without visible wear, maintaining material integrity and aesthetic appeal, allowing for reliable reuse in internal combustion engines.

Implementation Method 1

depositing welding filler material in a molten state onto a base material of the piston forming the defect

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

machining the deposited filler material once bonded to the base material and solidified

Methodology Applied

Scientific EffectSolidification: Freezing

Implementation Method 3

depositing welding filler material in a molten state onto a base material of the piston forming the defect

Methodology Applied

Scientific EffectWelding: Welding

Data Source

PatentUS9550256B2Used piston processing and repair strategies for populating replacement piston inventory

Publication Date: 2017.01.24 CATERPILLAR INC

AI summary

Processing used pistons includes receiving defective and non-defective pistons removed from service, sorting the used pistons into standard and expanded processing categories, and repairing a defect in pistons in the expanded processing category via welding. An inventory of interchangeable replacement pistons is populated with remanufactured pistons from both the standard and expanded processing categories.