Chain Sling Connecting Part to Prevent Bending Stress in Loops

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Solution Overview

Problem

Chain slings experience reduced load-bearing capacity due to additional bending stresses caused by hooks, and forming loops can be problematic when openings are too small, leading to potential unintentional loosening of the load.

Innovation Solution

A connecting part for chain slings that allows the chain to be guided through a receiving opening and then threaded into the supporting chain strand, with a bolt fixing the last chain link between longitudinal legs, preventing sliding and reducing bending stresses, thus maintaining load capacity and preventing unintentional detachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a hook is used as a connecting part to form a loop, then the chain can be easily connected to form a loop, but additional bending stresses occur that reduce the load-bearing capacity by up to 20%

Engineering Contradiction:
Improveease of loop formationVSAvoidload-bearing capacity
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The connecting part is divided into two separate components: a socket portion that receives the chain and a cap portion that secures it. This segmentation allows the chain to be inserted without bending stresses and then locked in place, eliminating the need for a traditional hook that causes stress concentration.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of using a hook that the chain bends around (which causes stress), the invention inverts the approach by using a socket that receives the chain end and secures it with a cap. This reverses the traditional connection method to avoid bending stresses entirely.

Inventive Principle:
Principle #13The other way round (Inversion)

2Volume of moving object

If the opening through which the chain must pass is made small, then the connecting piece can be compact, but it becomes problematic when the opening is too small to accommodate a connecting piece at the end of the chain

Engineering Contradiction:
Improvesize of connecting pieceVSAvoidease of chain threading
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The connecting part is divided into a socket portion with a receiving opening and a separate cap portion. The receiving opening is sized to accommodate the chain, while the cap portion is inserted through the same opening to secure the chain. This segmentation allows the opening to be optimized for chain passage without requiring excessive space for the entire connecting mechanism.

Inventive Principle:
Principle #1Segmentation

3Ease of operation

If a traditional hook is used to connect the chain, then the chain can be easily formed into a loop, but the load can unintentionally come loose from the loop

Engineering Contradiction:
Improveease of loop formationVSAvoidprevention of unintentional loosening
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The connecting part consists of a socket portion that receives the chain and a cap portion that secures it. The cap portion includes a fastening element that locks the chain in place, preventing unintentional loosening while maintaining ease of assembly through the sequential insertion process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The socket portion is prepared in advance with the receiving opening and fastening element positioned to receive and secure the chain. This preliminary preparation ensures that once the chain is inserted and the cap is secured, the connection is reliably locked and cannot unintentionally loosen.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3376065B1Connecting part for chain suspensions for forming a chain loop on a chain link composed of chain elements
Publication Date: 2022.01.26 PEWAG AUSTRIA GMBH
  • EP3376065B1 patent drawingFigure 1
  • EP3376065B1 patent drawingFigure 2~3
  • EP3376065B1 patent drawingFigure 4

AI summary

A connecting element (8) for chain slings (1) for forming a chain loop on a chain strand (2) consisting of chain links (3) comprises two parallel longitudinal legs (11, 12) forming a gap (13) between them. These legs are connected at one end (14, 15) by a position-fixable bolt (16) running perpendicular to them. At their other ends, they merge into a transverse bracket (17) that projects perpendicularly towards the front of the connecting element (8), connects both longitudinal legs (11, 12), and is curved between them. The gap (13) is wider than the web width (B) of a chain link (3), but smaller than its link width (C). The transverse bracket (17) projects from both longitudinal legs (11, 12) on its inner side by a distance approximately half the link width (C) of a chain link (3).At the top of the inlet of each longitudinal leg (11, 12) into the crossbar (17) and on its side facing the gap (13) and extending to it, a recess (18, 19) is provided in which an end region (20) of a chain link (3A'), which lies approximately parallel to the opening plane of the gap (13), can be received while simultaneously being supported in the longitudinal direction of the side legs (11, 12) in the direction away from the bolt (16).