Connecting Device with Positive-Locking Element for Excavation

Solution Overview

Problem

Existing thread connections in excavation work devices are prone to failure due to notch effects and geometry, leading to insufficient service life under harsh conditions, especially when subjected to compression, traction, and impact forces.

Innovation Solution

A connecting device with a drive section and shaft element utilizing a positive-locking element to separate force transfers, allowing torque transfer through the positive-locking element while tractive and compressive forces are transferred via a thread, enabling self-locking and preventing twisting or slipping, with replaceable positive-locking elements for extended service life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If screw connections with conventional threads are used to connect linkage segments, then the production cost is low and the screw-on process can be automated easily, but the connection represents the weakest point in the linkage due to the small diameter of the threaded plug and the large notch effect of the thread geometry, resulting in insufficient service life

Engineering Contradiction:

Improveproduction cost and automation capabilityVSAvoidservice life of thread connection

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The connection is segmented into two distinct functional parts: the thread connection handles only axial forces (tension and compression), while a separate positive-locking element (key) handles the torque transfer. This segmentation allows each component to be optimized for its specific function, eliminating the need for the thread to bear both axial and torsional loads simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A positive-locking element in the form of a key acts as an intermediary component between the threaded plug and the threaded hole. This key is inserted into a keyway and prevents relative rotational movement, thereby transferring torque without involving the thread connection. The key mediates the torque transfer function, allowing the thread to focus solely on axial force transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the thread connection is designed to transfer both torque and axial forces, then a single connection element is used, but the notch effect and geometry of the thread create stress concentrations that reduce the service life under compression, traction, and impact forces

Engineering Contradiction:

Improvenumber of connection elementsVSAvoidservice life under load

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The connection is segmented into two distinct functional parts: the thread connection handles only axial forces (tension and compression), while a separate positive-locking element (key) handles the torque transfer. This segmentation allows each component to be optimized for its specific function, eliminating the need for the thread to bear both axial and torsional loads simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A positive-locking element in the form of a key acts as an intermediary component between the threaded plug and the threaded hole. This key is inserted into a keyway and prevents relative rotational movement, thereby transferring torque without involving the thread connection. The key mediates the torque transfer function, allowing the thread to focus solely on axial force transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional thread shapes like API threads or round threads are used, then the connection can be made with standard components, but the service life has proven to be insufficient in daily operation of excavation work devices

Engineering Contradiction:

Improveuse of standard thread componentsVSAvoidservice life in daily operation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The connection is segmented into two distinct functional parts: the thread connection handles only axial forces (tension and compression), while a separate positive-locking element (key) handles the torque transfer. This segmentation allows each component to be optimized for its specific function, eliminating the need for the thread to bear both axial and torsional loads simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A positive-locking element in the form of a key acts as an intermediary component between the threaded plug and the threaded hole. This key is inserted into a keyway and prevents relative rotational movement, thereby transferring torque without involving the thread connection. The key mediates the torque transfer function, allowing the thread to focus solely on axial force transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9163671B2Connecting device

Publication Date: 2015.10.20 TRACTO TECHN

AI summary

A connecting device with a drive section having a thread on the end, wherein the connecting device can be used to screw a shaft element to a thread corresponding to the thread of the drive section, wherein, in addition to the thread, at least one positive-locking element forming a positive-locking connection with the shaft element is provided.