Rail Vehicle Body Bolt Assembly for Thin-Sheet Stud Welding

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Solution Overview

Problem

Existing methods for attaching grounding straps to rail vehicle car bodies, such as cupal tabs, are complex and prone to thermal overload, limiting their application to reinforced areas and thin sheets, and are not mechanically stable under high stress.

Innovation Solution

A method using a bolt with an aluminum interface section and a corrosion-resistant steel connection section, where the bolt is welded to the car body using a stud welding process, allowing attachment virtually anywhere, including thin sheets, and featuring a corrosion-resistant steel coating for enhanced stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cup lugs with copper jacket and tin coating are welded to the car body, then corrosion protection is improved, but the manufacturing complexity increases due to milling off the coating in the base area

Engineering Contradiction:
Improvecorrosion protectionVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The connecting element is divided into two distinct sections: an interface section made of aluminum for welding to the car body, and a connection section made of corrosion-resistant steel for attaching rail vehicle components. This segmentation eliminates the need for complex multi-layer coatings and post-welding milling operations, as each section is optimized for its specific function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different sections of the connecting element have different material properties tailored to their specific functions: the interface section uses aluminum for ease of welding to aluminum car body sheets, while the connection section uses corrosion-resistant steel for mechanical stability and corrosion protection. This local differentiation of material quality simplifies the overall manufacturing process by eliminating the need for uniform complex coatings.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If cup lugs are welded to thin sheet metal of the car body, then connection is achieved, but thermal overloading occurs limiting application to reinforced areas only

Engineering Contradiction:
Improveattachment capabilityVSAvoidthermal overload
Core Design Contradiction:
Ease of operationVSTemperature

Solution Approach 1:

The material of the interface section is changed to aluminum, which has lower thermal conductivity and lower melting point compared to steel. This parameter change allows the welding process to be performed on thin sheet metal without causing thermal overload, as the aluminum interface section absorbs and dissipates heat more effectively, preventing damage to the thin car body sheets.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If cup lugs with copper-tin coating are used, then corrosion protection is provided, but mechanical stability decreases under high stress

Engineering Contradiction:
Improvecorrosion protectionVSAvoidmechanical stability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The connecting element is segmented into an interface section and a connection section with different materials. The connection section is made of corrosion-resistant steel that maintains mechanical stability under high stress, while the interface section is made of aluminum for ease of welding. This segmentation allows each section to optimize its properties for its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connecting element is constructed as a composite structure with an aluminum interface section and a corrosion-resistant steel connection section. This composite design combines the advantages of both materials: aluminum provides ease of welding to the car body, while steel provides mechanical strength and corrosion resistance, eliminating the need for copper-tin coatings that compromise mechanical stability.

Inventive Principle:
Principle #40Composite materials

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

Enables secure attachment of rail vehicle components to thin sheet metal sections with improved mechanical stability and longevity, allowing for the transmission of significant tensile forces, reducing spatial restrictions and corrosion risks.

Implementation Method 1

The stud sections are firmly connected to each other. A welding stud with a welding section and a functional section is known, wherein the stud sections are firmly connected to each other. The stud is welded with its interface section to a sheet metal part, particularly aluminum sheet metal, of the car body, preferably using a stud welding process. A stud welding process is defined as a process in which the thermal heat for welding at the interface between the stud and the car body is generated by a current flowing into and through the stud.

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

Coating is preferably done by plasma coating, laser coating or printing.

Methodology Applied
Scientific EffectPlasma coating: Plasma Spray

Implementation Method 3

Coating is preferably done by plasma coating, laser coating or printing.

Methodology Applied
Scientific EffectLaser coating: Laser Beam Welding

Data Source

PatentEP4124536B1Method for manufacturing an assembly comprising a vehicle body and a connecting element
Publication Date: 2024.11.13 SIEMENS MOBILITY GMBH DE
  • EP4124536B1 patent drawingFigure 1
  • EP4124536B1 patent drawingFigure 2~3
  • EP4124536B1 patent drawingFigure 4~5

AI summary

The invention relates, inter alia, to a method for manufacturing an arrangement comprising a car body (10) of a rail vehicle and a connecting element attached thereto. According to the invention, the connecting element is a bolt (30), wherein the bolt (30) comprises an interface section (33) made of aluminum, which serves for attachment to the car body (10), and a connecting section (31) made of corrosion-resistant steel, which serves for attaching a rail vehicle component, and the bolt (30) with its interface section (33) is welded to the car body (10) by means of a welding process.