Screw Fastening Method Using Collision Cycle Verification

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Solution Overview

Problem

Existing screw fastening methods struggle to accurately detect the starting position of screwing to prevent jamming between external and internal threads, especially when noise vibrations occur alongside thread collisions.

Innovation Solution

A screw fastening method and device that use a sensor to detect collisions between thread ridges while reversing the shaft part, determining if the time interval between collisions matches a theoretical cycle calculated from the rotation speed, and only normalizing the rotation when the interval matches the cycle multiple times or after a predetermined period, distinguishing genuine collisions from noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If vibration detection is used to detect thread ridge collisions during reverse rotation, then the starting position of screwing can be detected, but noise vibrations cause false detection and prevent accurate identification of the true starting position

Engineering Contradiction:

Improvedetection accuracy of thread ridge collisionVSAvoidreliability of starting position detection

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The system uses feedback by comparing the detected vibration cycle with the theoretical cycle calculated from rotation speed. The control unit continuously monitors vibrations during reverse rotation and compares the detected collision cycle against the expected theoretical cycle, adjusting the determination of the starting position based on this feedback comparison to filter out noise vibrations that do not match the theoretical pattern

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes the parameter of cycle comparison by introducing the theoretical cycle calculation based on rotation speed as a reference parameter. Instead of relying solely on raw vibration detection, the system calculates what the collision cycle should be theoretically from the known rotation speed, and uses this parameter to validate whether detected vibrations represent true thread ridge collisions or noise

Inventive Principle:

Principle #35Parameter changes

2Difficulty of detecting and measuring

If reverse rotation is used to detect thread ridge collisions, then the starting position can be identified, but noise vibrations are indistinguishable from true collisions causing false activation

Engineering Contradiction:

Improvedetectability of thread ridge collisionVSAvoidprecision of collision detection

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The theoretical cycle calculation acts as an intermediary between the rotation speed and the vibration detection. Instead of directly equating any vibration during reverse rotation to a thread ridge collision, the system introduces the theoretical cycle as an intermediary reference that mediates the determination process, filtering out noise vibrations that do not conform to the expected theoretical pattern

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the shaft part is rotated normally immediately after detecting a collision, then fastening can begin, but false collisions due to noise cause premature fastening and potential thread jamming

Engineering Contradiction:

Improvefastening speedVSAvoidreliability of fastening operation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs a preliminary verification action by comparing the detected vibration cycle with the theoretical cycle before initiating normal rotation for fastening. This preliminary check ensures that the detected collision is genuine and not noise, preventing premature fastening that would cause thread jamming while still enabling quick activation when the condition is truly met

Inventive Principle:

Principle #10Preliminary action

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

This approach effectively prevents thread jamming by accurately distinguishing between thread collisions and noise vibrations, ensuring reliable fastening even in the presence of noise other than collisions.

Implementation Method 1

detecting collisions between thread ridges of the external thread and the internal thread using a sensor while the shaft part remains rotated reversely

Methodology Applied

Scientific EffectVibration: Vibration

Data Source

PatentUS10173305B2Screw fastening method and screw fastening device

Publication Date: 2019.01.08 TOYOTA JIDOSHA KK

AI summary

A screw fastening method includes reversely rotating a shaft part of a fastening tool in a direction of loosening one of an external thread and an internal thread, which is engaged with the shaft part, while one of the external thread in a non-screwed state and the internal thread in a non-screwed state, which is engaged with the shaft part, is pressed against the other thread, detecting collisions between thread ridges of the external thread and the internal thread using a sensor while the shaft part remains rotated reversely, determining whether or not a time interval between collisions detected by the sensor matches a theoretical cycle of collisions calculated from rotation speed of the shaft part, and fastening the external thread and the internal thread to each other by normally rotating the shaft part when it is determined that the time interval matches the theoretical cycle.