Stick-Slip Detection via Plug Support Bar Load Analysis
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Solution Overview
Problem
Existing methods for detecting the precursor to the stick-slip phenomenon during cold drawing of pipes are inadequate, as they rely on auditory detection or sensors that struggle to distinguish small vibrations of the plug from other noise sources, leading to delayed reaction and reduced manufacturing efficiency.
Innovation Solution
A method involving load measurement on the plug support bar during cold drawing, where frequency analysis of load measurement values over a predetermined frequency band is used to detect precursors of the stick-slip phenomenon, allowing for early detection and prevention of the phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If auditory detection by operator is used to detect stick-slip phenomenon, then detection method is simple, but detection accuracy is insufficient and reaction is delayed
Solution Approach 1:
The patent replaces the auditory detection system (human operator's ear and brain processing) with an automated sensor-based detection system. Acceleration sensors mounted on the plug support bar directly measure vibrational acceleration, and a controller processes this data to detect stick-slip phenomena. This substitution of mechanical/biological detection with instrumental detection resolves the contradiction by providing both automated simplicity and high measurement precision.
Solution Approach 2:
The patent introduces acceleration sensors as intermediary devices between the stick-slip phenomenon (vibration source) and the detection system. These sensors convert mechanical vibrations into electrical signals that can be processed by the controller, serving as a mediator that bridges the physical phenomenon and the detection/analysis system, thereby improving detection accuracy while maintaining system simplicity.
2Manufacturing precision
If drawing speed is reduced to prevent stick-slip phenomenon, then occurrence of dimensional defects is prevented, but manufacturing efficiency is reduced
Solution Approach 1:
The patent implements a feedback control system where acceleration sensors continuously monitor vibrations during drawing, the controller analyzes the signals to detect stick-slip phenomena in real-time, and the system responds by adjusting drawing speed only when necessary. This feedback mechanism resolves the contradiction by maintaining high drawing speeds during normal operation (preserving productivity) while automatically reducing speed only when stick-slip is detected (maintaining dimensional accuracy).
Solution Approach 2:
The patent introduces dynamic adjustment of drawing speed based on real-time vibration conditions rather than using a fixed conservative speed. The drawing speed becomes a dynamic parameter that adapts to actual process conditions, allowing high speeds when stable and reduced speeds when stick-slip occurs. This dynamic approach resolves the contradiction between maintaining high productivity and ensuring dimensional accuracy.
3Extent of automation
If AE sensor is used to detect vibration frequency, then detection automation is improved, but ability to distinguish small vibrations from noise is insufficient
Solution Approach 1:
The patent applies local quality by mounting acceleration sensors directly on the plug support bar, placing the detection device at the precise location where stick-slip vibrations occur. This localized detection approach allows the system to capture high-frequency vibrations specific to the plug support bar while filtering out distant noise sources, resolving the contradiction between automated detection and vibration discrimination accuracy.
Solution Approach 2:
The patent utilizes the principle of mechanical vibration detection by employing acceleration sensors that specifically measure high-frequency vibrational movements. The system detects the characteristic vibration patterns of stick-slip phenomena through acceleration measurements, enabling automated detection with high precision by focusing on the specific vibrational signature of the defect.
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 enables accurate detection of precursors before the stick-slip phenomenon occurs, allowing for timely reduction in drawing speed to prevent dimensional defects and vibrations, thereby improving manufacturing efficiency and reducing the risk of cracks.
Implementation Method 1
a load measurement step of measuring a load applied to the plug support bar in the drawing direction
Implementation Method 2
the plug support bar 4 stretches in the drawing direction since the rear edge of the plug support bar 4 is fixed on the base of the drawing machine. Accordingly, on account of a contractive force due to the elasticity of the plug support bar 4
Implementation Method 3
the plug 3 is pulled by friction force generated between itself and the inner surface of the pipe T
Data Source
AI summary
A precursor detection device 6 detects a precursor of a stick-slip phenomenon in a drawing machine 1. The precursor detection device 6 includes a load measurement section 61 for measuring a load applied to a plug support bar 4 in the drawing direction, a precursor detection section 62 for detecting a precursor of a stick-slip phenomenon based on a load measurement value measured by the load measurement section 61, and a control section 63. After drawing is started, a load applied to the plug support bar 4 in the drawing direction is measured by the load measurement section 61 during a predetermined period from a measurement start point to a measurement end point, and based on the measured load measurement values, a precursor of a stick-slip phenomenon is detected by the precursor detection section 62.