Cab Corner Reinforcement for Construction Machine Buckling Prevention

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Solution Overview

Problem

Conventional reinforcement methods for construction machine cabs weaken frame members at apex portions due to concentrated load stress, leading to potential buckling when loads act in directions decreasing the angle between adjacent frame members.

Innovation Solution

A reinforcing member with bent surface portions is installed in right-angled corners, surface-contacting with frame members and utilizing the cab's floor plate to distribute load stress, preventing buckling without additional components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a triangular platy reinforcement is placed into a right-angled corner with apex portions in line contact with frame members, then the cab is reinforced to protect the user, but the frame members are weakened and prone to buckling around the apex portions due to concentrated load stress

Engineering Contradiction:
Improvecab strengthVSAvoidframe member reliability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The reinforcing member is changed from a two-dimensional triangular plate to a three-dimensional structure with bent surface portions that extend outward. This dimensional change allows the reinforcement to contact the frame members over a larger surface area rather than at line contacts, distributing the load stress and preventing concentrated stress points that cause buckling.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The reinforcing member incorporates bent surface portions with curved geometries that wrap around the frame members. This curvature allows the reinforcement to conform to the frame member surfaces and distribute loads more evenly, converting the sharp line contacts into distributed surface contacts that reduce stress concentration.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If additional reinforcing plates are prepared to prevent buckling of frame members, then the frame members are protected from buckling, but the number of components increases

Engineering Contradiction:
Improveframe member reliabilityVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The reinforcing member is integrated with the floor plate by forming the bent surface portions directly from the floor plate material. This merging eliminates the need for separate reinforcing plates, as the floor plate itself is transformed into the reinforcing structure that protects the frame members from buckling.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The floor plate is given multiple functions: it serves as both the walking surface and as the reinforcing member that protects frame members from buckling. By making the floor plate multi-functional, additional reinforcing components are eliminated while maintaining structural protection.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2423392B1Reinforcement for cab in construction machine
Publication Date: 2018.11.21 PRESS KOGYO CO LTD
  • EP2423392B1 patent drawingFigure 1
  • EP2423392B1 patent drawingFigure 2
  • EP2423392B1 patent drawingFigure 3

AI summary

A reinforcement (18) is attached to the right angle corner between the right rear side column material (10) and the right underside beam material (15) which form the cab (5) frame of a hydraulic shovel (1) so that buckling of the thin right underside beam material (15) can be prevented. The reinforcement (18) is made to penetrate through a penetrate portion (15d) formed on the upper side surface of the right underside beam material body (15a) so that the second bent surface portion (18b) formed on the reinforcement (18) is abutted against the lower side surface of the right underside beam material body (15a), and a thick floor plate (20) is abutted against the lower side surface of the right underside beam material body (15a). Consequently, when a load works in the direction for decreasing the angle between the right rear side column material (10) and the right underside beam material (15), the load is received by the floor plate (20) and even if the right underside beam material (15) is a thin hollow material having weak strength, the right underside beam material (15) is not buckled but protected thus achieving an increase in the strength of the cab (5). FIGS. 4A, 4B and 4C