Metal Tube Bending Springback Correction
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Solution Overview
Problem
Metal tube bending processes face challenges due to natural variations in sheet metal, such as springback, which can lead to excessive scrap rates due to under or over bending, caused by factors like material characteristics, temperature, and tooling wear, resulting in inconsistent final geometry.
Innovation Solution
A method utilizing real-time closed-loop feedback to measure and correct the bending force and coordinates based on actual springback, employing a rotary draw bender with a measuring device and controller to adjust bending parameters, ensuring precise geometry by reapplying force based on calculated correction factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional open-loop bending process is used, then the bending operation is simple and fast, but the manufacturing precision deteriorates due to unaccounted springback variations
Solution Approach 1:
The patent implements a closed-loop feedback system where a measuring device (video camera) captures the actual bend geometry after springback occurs, and the controller uses this measured data to calculate and apply correction factors for subsequent bends. This feedback mechanism directly addresses the springback variation problem by continuously monitoring and adjusting the bending process based on actual results.
Solution Approach 2:
The system performs preliminary measurement of the first bend's actual geometry before proceeding to subsequent bends. By measuring the actual springback of the first bend and calculating correction factors in advance, the system prepares the adjusted bending coordinates for all subsequent bends, ensuring precision is built into the process before variations accumulate.
2Productivity
If no springback correction is applied, then the bending process is fast and simple, but the scrap rate increases due to under or over bending
Solution Approach 1:
The feedback system measures the actual bend coordinates after springback and compares them to the desired coordinates, calculating correction factors that are applied to subsequent bends. This prevents both under-bending and over-bending by continuously adjusting based on actual material behavior, thereby reducing scrap while maintaining efficient production throughput.
Solution Approach 2:
The system uses the actual springback data from each workpiece to automatically generate correction factors for itself, without requiring external intervention or manual adjustment. The controller self-corrects the bending process by applying calculated correction factors to subsequent bends, enabling the system to compensate for material variations autonomously.
3Measurement precision
If real-time feedback measurement is implemented, then the bend geometry accuracy is improved, but the measurement and control complexity increases
Solution Approach 1:
The patent replaces complex mechanical measurement systems with a video camera-based optical measurement system. The video camera captures images of the bent workpiece, and the controller processes these images to determine actual bend coordinates. This substitution simplifies the physical measurement apparatus while maintaining high measurement precision through digital image analysis.
Solution Approach 2:
The system creates a digital copy of the actual bend geometry through video imaging and image processing. Instead of using complex physical measurement tools, the system captures an optical copy of the bend and analyzes it digitally to extract precise coordinate information, simplifying the measurement process while maintaining accuracy.
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 significantly reduces scrap rates by accurately accounting for springback variations, achieving the desired bend geometry and improving overall quality and uptime in metal tube bending processes.
Implementation Method 1
Springback is the tendency of sheet metal (or a metal tube formed from a sheet) to lose some of its shape when it is removed from a die. As the die is released, the work piece ends up with less bend than that on the die
Implementation Method 2
The video camera records an image of the metal tube and relays the position of the metal tube derived from the image to the controller
Data Source
AI summary
A method of bending a metal object, such as a tube, is provided that uses real time, closed-loop feedback of the actual springback of the object in order to modify the applied bending force or preprogrammed bending coordinates so that the final desired bend geometry is achieved. The variability of springback from object to object is thus accounted for and the number of objects that must be scrapped due to incorrect bends (over bend or under bend) is reduced. The method is carried out using an apparatus such as a rotary draw bender with a measuring device operable to measure actual bend coordinates of metal objects bent by the bender. A controller is operatively connected to the bender and the measuring device and is configured to control the bender to bend the metal objects at least partly based on measured bend coordinates provided by the measuring device.