Threaded Conical Screw Lock for Excavating Tooth Retention

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Solution Overview

Problem

Existing locking methods for excavating teeth in wearing-part systems are inefficient for easy assembly and effective retention, often requiring complex thermal joining or wedging techniques that are cumbersome for replacement and maintenance.

Innovation Solution

A lock system comprising a threaded conical screw and two thread halves with trapezoidal thread beds, where the screw moves axially to lock the excavating tooth to the wearing-part holder, utilizing upper and lower lateral arms and recesses for secure assembly and easy disassembly, and a protective cap for added friction and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional thermal joining techniques (welding, shrink-fitting) are used to mount the wearing-part holder, then strong retention and durability are achieved, but assembly complexity and difficulty of replacement increase

Engineering Contradiction:
Improveretention strengthVSAvoidassembly complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The lock is divided into three separate components: a conical screw, a first thread half, and a second thread half. This segmentation allows the system to achieve strong retention through the threaded connection while maintaining simplicity in assembly, as each component can be independently installed and replaced without complex thermal joining processes.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If a single clamp with limited thread surface is used (as in US 7,997,017), then assembly is simplified, but mechanical contact and bearing surface area are reduced

Engineering Contradiction:
Improveease of assemblyVSAvoidthread bearing surface area
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

The invention transitions from a single-clamp design to a two-thread-half design that distributes the bearing surface across multiple contact points. The first thread half engages with the conical screw on one side, while the second thread half engages on the other side, effectively doubling the thread bearing surface area and improving mechanical contact without complicating the assembly process.

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

3Strength

If the wearing-part holder is welded to the bucket, then strong connection is achieved, but ease of replacement and maintenance decrease

Engineering Contradiction:
Improveconnection strengthVSAvoidease of replacement
Core Design Contradiction:
StrengthVSEase of repair

Solution Approach 1:

The invention replaces thermal joining (welding) with a mechanical threaded connection system. The conical screw with thread halves provides a strong mechanical connection between the wearing-part holder and the tool, while allowing for easy replacement by simply unscrewing the lock components without requiring welding equipment or complex disassembly procedures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of manufacture

If a conventional thread with pointed design is used, then manufacturing is simplified, but bearing surface on unthreaded areas is insufficient

Engineering Contradiction:
Improvethread manufacturing simplicityVSAvoidunthreaded bearing surface area
Core Design Contradiction:
Ease of manufactureVSArea of stationary object

Solution Approach 1:

The thread halves are designed with differentiated local qualities: the threaded portions provide secure engagement with the conical screw, while the unthreaded portions feature enlarged bearing surfaces for distributed load bearing. This local quality variation allows each component to perform its specific function optimally - the threads provide connection strength while the unthreaded areas provide adequate bearing surface without requiring complex manufacturing processes.

Inventive Principle:
Principle #3Local quality

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

Facilitates simple and reliable assembly and disassembly of excavating teeth, providing strong retention and easy replacement, reducing wear and tear on components, and maintaining the lock in a secure position with minimal production costs and high strength.

Implementation Method 1

rotation of the threaded screw moves the threaded screw along the thread beds in the axial direction of the screw into the lock opening

Methodology Applied
Scientific EffectScrew mechanism: Screw

Implementation Method 2

a protective cap for added friction and protection

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2898150B1Lock for tool holder
Publication Date: 2019.05.22 COMBI WEAR PARTS AB
  • EP2898150B1 patent drawingFigure 1
  • EP2898150B1 patent drawingFigure 2a~2e
  • EP2898150B1 patent drawingFigure 3a~3e

AI summary

The invention relates to a lock for releasable locking of an excavating tooth to a wearing-part holder in a wearing- part system, where the excavating tooth and the wearing- part holder together define a lock opening for receiving the lock, where the lock comprises a threaded conical screw and a first thread half designed with a first thread bed, where the first thread half and a second thread half, designed with a second thread bed, are mounted in the lock opening, where the first thread half and the second thread half, with the thread beds directed towards each other, together define an opening for threaded fastening of the threaded conical screw, such that rotation of the threaded screw moves the threaded screw along the thread beds in the axial direction of the screw into the lock opening, locking the lock when the first thread half is moved towards the excavating tooth and the second thread half is moved towards the wearing-part holder. The invention also relates to a wearing-part system, a first thread half, a second thread half, a conical screw, and an associated method for releasable locking of an excavating tooth to a wearing-part holder in a wearing-part system with lock.