Press Brake Feedback Crowning for Partial Bending Accuracy
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Solution Overview
Problem
Existing press brake technologies face challenges in achieving accurate multistage bending due to variations in Young's modulus and thickness of workpiece materials, leading to inaccuracies in bending angles and dimensional errors.
Innovation Solution
A press brake system equipped with a die, punch, crowning mechanism, bending amount measuring device, and control device that adjusts the crowning amount and tilt to correct for differences between middle and end bending amounts, accounting for springback changes caused by material variations and thickness errors, thereby improving forming accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed stroke value is used for bending, then the forming process is simple and fast, but the bending accuracy deteriorates due to material variations and thickness errors
Solution Approach 1:
The patent implements feedback control by measuring the actual bending amount with sensors and comparing it to the target bending amount. The control device then adjusts the stroke value based on the measured bending amount to achieve the target bending angle, resolving the contradiction between fast forming and accurate bending by dynamically correcting for material variations.
Solution Approach 2:
The patent transitions from a fixed, static stroke value to a dynamic stroke value that is adjusted in real-time based on measured bending amounts. The stroke value is corrected using the difference between measured and target bending amounts, allowing the system to adapt to material variations while maintaining high forming speed.
2Measurement precision
If the bending angle is monitored during forming with feedback, then the angle accuracy is improved, but the measurement error significantly influences the stroke in multistage bending
Solution Approach 1:
The patent performs preliminary measurement of the bending amount after forming and uses this measurement to correct the stroke value for subsequent forming operations. By measuring first and then correcting based on the measurement, the system avoids the problem of measurement errors directly influencing the stroke during the forming process itself.
3Productivity
If the stroke value is determined in advance without actual forming, then the process is efficient, but the bending accuracy deteriorates due to variations in Young's modulus and thickness
Solution Approach 1:
The patent enables the system to self-correct by using its own measurement capability to detect bending amount deviations and automatically adjust the stroke value accordingly. The control device uses the measured bending amount to calculate the correction needed, making the system self-regulating without external intervention, thus maintaining both efficiency and 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
The system enhances bending accuracy and dimensional precision of multistage bending processes by dynamically correcting for material and thickness variations, ensuring high accuracy in forming complex shapes like circular tubes.
Implementation Method 1
a punch that is arranged so as to be opposed to the die and moves in an upper-lower direction relative to the die to press a front surface of the workpiece
Implementation Method 2
a relation between the stroke value and a realized angle depends on Young's modulus of the material of a workpiece... variations of Young's modulus from the nominal value of the material... springback amount itself changes
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
There is provided a press brake that improves bending accuracy of a partial bending method. The press brake includes: a conveying mechanism that intermittently conveys a workpiece; a die; a punch; a crowning mechanism; a bending amount measuring device; and a control device. The control device presses an end portion of the workpiece in a conveying direction by the punch and conveys the workpiece by the conveying mechanism until the pressed portion enters into a measurement range of the bending amount measuring device. The control device drives the crowning mechanism so as to correct a crowning amount in accordance with a difference between a middle bending amount and an end bending amount measured by the bending amount measuring device.