Shock Absorber Piston Rod Welding Process for Dirt Shield Sealing

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Solution Overview

Problem

Conventional hydraulic dampers or shock absorbers face durability issues under higher static and dynamic loads due to the limitations of single-weld operations, particularly with the attachment of dirt shields, which can lead to rust bleeding and reduced resistance to contaminants.

Innovation Solution

A two-weld process is employed, where a resistance or friction weld is initially used to attach the upper stem or attachment loop to the lower portion of the piston rod, followed by a MIG or MAG weld that covers and secures the dirt shield, enhancing the connection's strength and sealing while eliminating rust bleeding and weld spatter issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single welding operation is used to attach the dirt shield to the piston rod, then the manufacturing process is simple and cost-effective, but the durability and resistance to static and dynamic loads are insufficient

Engineering Contradiction:
Improvewelding process simplicityVSAvoiddurability under load
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The welding process is divided into two distinct operations: a first welding operation that attaches the dirt shield to the piston rod, and a second welding operation that attaches the upper stem to the piston rod. This segmentation allows each weld to be optimized for its specific function, with the first weld providing a clean, spatter-free attachment for the dirt shield, and the second weld providing strong structural attachment for the upper stem, thereby resolving the contradiction between manufacturing simplicity and durability.

Inventive Principle:
Principle #1Segmentation

2Productivity

If a single welding operation is used, then the manufacturing cost and time are reduced, but rust bleeding and weld spatter damage to the sealing system occur

Engineering Contradiction:
Improvemanufacturing efficiencyVSAvoidrust bleeding and weld spatter
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The welding operations are segmented into two separate steps: first attaching the dirt shield, then attaching the upper stem. This segmentation prevents weld spatter from damaging the sealing system during the first weld, and eliminates rust bleeding issues that would occur with a single prolonged welding operation, while maintaining manufacturing efficiency through systematic process organization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The dirt shield is attached in a preliminary welding operation before the upper stem is attached. This preliminary action protects the piston rod and sealing system from weld spatter during the critical first attachment, and prevents rust bleeding by completing the dirt shield attachment before subsequent welding operations occur nearby.

Inventive Principle:
Principle #10Preliminary action

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

This two-step welding process increases the durability and resistance to static and dynamic loads, simplifies the painting process, reduces costs by eliminating a welding step, and ensures the sealing system remains free from damage by weld spatter, providing superior strength and reliability.

Implementation Method 1

a resistance or friction weld is initially used to attach the upper stem or attachment loop to the lower portion of the piston rod

Methodology Applied
Scientific EffectFriction welding: Friction Welding

Implementation Method 2

followed by a MIG or MAG weld that covers and secures the dirt shield

Methodology Applied
Scientific EffectArc welding: Welding

Data Source

PatentEP2137429B1Improved rod assembly weld and method for manufacturing rod assembly
Publication Date: 2019.06.05 TENNECO AUTOMOTIVE OPERATING COMPANY INC
  • EP2137429B1 patent drawingFigure 1
  • EP2137429B1 patent drawingFigure 2
  • EP2137429B1 patent drawingFigure 3~4

AI summary

A shock absorber includes a welded piston rod assembly. The piston rod assembly comprises an upper piston rod portion welded to a lower piston rod portion and a dirt shield welded to both of the upper piston rod portion and the lower piston rod portion using a single weld.