Rail Vehicle Base Frame Laser Welding for Lightweight Rigidity

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Solution Overview

Problem

Rail vehicle underframes face challenges in achieving high stiffness and load-bearing capacity while minimizing weight and energy consumption, particularly due to the integration of environmentally friendly but heavier systems, and must comply with weight restrictions to avoid excessive wheel loads and stress.

Innovation Solution

A method for manufacturing a floor frame using laser welding to join plate-shaped central and longitudinal elements, allowing for thinner walls and reduced material usage, enhancing rigidity and load-bearing capacity, and incorporating a central longitudinal beam designed as an I-beam for improved stress absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional MAG welding is used to join plate-shaped central section element to longitudinal elements, then sufficient heat input is provided to ensure strong joints, but the central section element requires thicker wall construction to prevent burning through, increasing weight

Engineering Contradiction:

Improvejoint strengthVSAvoidcentral section element weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent replaces conventional MAG welding with laser welding technology. Laser welding provides higher energy density and more precise heat control, allowing thinner wall constructions in the central section element while maintaining sufficient joint strength. The laser beam's focused energy enables localized heating without excessive heat input that would require thicker walls for protection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If multiple elements are used to construct the base frame to ensure sufficient stability and rigidity, then load-bearing capacity is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvebase frame stabilityVSAvoidnumber of elements

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges multiple functional elements into a more integrated base frame construction. By using laser welding to join plate-shaped central section elements directly to longitudinal elements, the design reduces the number of separate components while maintaining structural integrity. This integration simplifies manufacturing and reduces assembly complexity while preserving stability and rigidity.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If thicker wall construction is used in the base frame to ensure load-bearing capacity, then strength is improved, but weight increases and wheel loads become excessive

Engineering Contradiction:

Improveload-bearing capacityVSAvoidbase frame weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent changes the material parameters and construction methods to achieve optimal strength-to-weight ratio. By using laser welding with precise heat control, the base frame can use thinner wall constructions that still provide sufficient load-bearing capacity. The controlled thermal process allows for optimized material usage without excessive weight, keeping wheel loads within permissible limits.

Inventive Principle:

Principle #35Parameter changes

4Strength

If conventional welding methods are used with higher heat input, then strong joints are achieved, but manufacturing precision decreases due to larger tolerances required

Engineering Contradiction:

Improvejoint strengthVSAvoidtolerance requirement

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent substitutes conventional high-heat-input welding with laser welding technology. Laser welding provides superior precision and control over heat distribution, enabling tighter tolerances in the manufactured base frame. The focused laser beam delivers energy precisely where needed, reducing the overall heat input and allowing for more accurate dimensional control while maintaining joint 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 results in a weight-optimized, corrosion-resistant, and cost-effective floor frame with enhanced stability and reduced maintenance needs, ensuring safety against derailment and minimizing material usage.

Implementation Method 1

at least two longitudinal elements, a central longitudinal beam, at least two side longitudinal beams in the direction of or substantially parallel to the longitudinal axis of the rail vehicle and several transverse elements transverse to the longitudinal axis of the rail vehicle are fixed on one side of the plate-shaped central section element by means of laser welding

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP4344976B1Method for producing a base frame for a car body of a rail vehicle and base frame

Publication Date: 2026.01.21 SIEMENS MOBILITY GMBH

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AI summary

The invention relates to a method for manufacturing a floor frame (100) for a car body for a rail vehicle (1) comprising the following steps: - providing at least one plate-shaped central section element (101) and - fixing at least two longitudinal elements (105), a central longitudinal beam (107), at least two side longitudinal beams (111) in the direction of the longitudinal axis of the rail vehicle and several transverse elements (113) transverse to the longitudinal axis of the rail vehicle on one side (103) of the plate-shaped central section element (101) by means of laser welding.