Screw Fastening Failure Detection Using Axial Speed at Temporary Seating

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Solution Overview

Problem

Existing screw fastening technologies face challenges in accurately determining screw fastening failure due to variations in screw length and material properties, leading to potential collisions with objects and erroneous determinations.

Innovation Solution

A screw fastening failure determination device that includes a speed acquisition unit to measure the axial speed of a screw driver during a temporary seating process, allowing for precise determination of screw fastening failure based on speed feature values at a prescribed timing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a long measurement set time is used to ensure accurate screw presence determination, then measurement accuracy is improved, but the determination is delayed and the bit may collide with the object to be fastened

Engineering Contradiction:

Improvescrew presence determination accuracyVSAvoiddetermination delay

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary detection of screw presence at the measurement start position before the screw enters the screw hole. By detecting whether the screw is present at the initial position (where the bit contacts the screw head) before insertion begins, the system can immediately determine screw presence without waiting for the screw to enter the hole, thus avoiding determination delay while maintaining accuracy

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent divides the screw fastening process into distinct phases: (1) measurement phase at the measurement start position where the bit contacts the screw head before insertion, and (2) insertion phase where the screw enters the screw hole. By performing detection during the measurement phase at a specific position, the system achieves accurate determination without requiring extended measurement time throughout the entire insertion process

Inventive Principle:

Principle #1Segmentation

2Productivity

If the measurement set time is shortened to prevent bit collision, then productivity is improved, but measurement accuracy deteriorates especially for shorter screws

Engineering Contradiction:

Improvefastening speedVSAvoidscrew presence determination accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system performs screw presence detection at the measurement start position before the screw insertion begins. This preliminary detection at the initial contact position allows for immediate determination of screw presence, enabling short measurement time that prevents bit collision while maintaining accurate detection even for shorter screws

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces traditional mechanical detection methods (such as thrust-based detection) with a position-based detection method. By detecting screw presence at the measurement start position where the bit contacts the screw head, the system achieves accurate detection without relying on mechanical thrust measurements that are affected by material properties and tolerances

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If thrust-based detection is used to determine screw presence, then device complexity is reduced, but measurement accuracy deteriorates due to sensitivity to external factors

Engineering Contradiction:

Improvedetection system simplicityVSAvoidscrew presence determination accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces thrust-based mechanical detection with position-based detection. By determining screw presence at the measurement start position where the bit contacts the screw head, the system achieves accurate detection without using thrust sensors, thereby maintaining device simplicity while eliminating sensitivity to material properties and tolerances

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces the measurement start position (where the bit contacts the screw head) as an intermediary reference point for detection. This intermediary position provides a consistent and reliable reference that is independent of the object material properties and screw tolerances, enabling accurate detection without complex thrust measurement systems

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3950214B1Screw fastening failure determination device, screw fastening device, screw fastening failure determination method, and control program

Publication Date: 2023.05.03 OMRON CORP

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AI summary

Provided is a technique capable of suitably determining screw fastening failure. A screw fastening failure determination device (10) includes: a speed acquisition unit (13) which acquires an axial speed of a screw driver or a speed feature value relating to the speed; and a failure determination unit (14) which determines, in a temporary seating process, that a screw fastening has failed on the basis of the axial speed or the speed feature value at a prescribed timing.