Press Brake Optical Monitoring for Shadow-Induced False Detection
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Solution Overview
Problem
The existing optical safety devices in press brakes often incorrectly detect foreign bodies due to shadow enlargement caused by temperature gradients, leading to reduced working efficiency and productivity.
Innovation Solution
An optical safety device with a projector and photodetectors that includes an invalidation unit to prevent false detection by determining if the shadow of the upper die extends to the photodetectors, and a calculation unit to assess shadow enlargement, ensuring accurate detection of foreign bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical safety device is equipped in the press brake to monitor foreign bodies, then safety of the bending work is improved, but false detection occurs due to shadow enlargement from temperature gradients
Solution Approach 1:
The press brake is divided into a monitoring region and a non-monitoring region. The optical safety device monitors only the monitoring region for foreign bodies, while the non-monitoring region allows shadow enlargement without triggering false alarms. This segmentation resolves the contradiction by spatially separating the detection function from the shadow interference zone.
Solution Approach 2:
Different regions of the press brake are assigned different functional qualities: the monitoring region has high detection sensitivity for foreign bodies, while the non-monitoring region tolerates shadow enlargement. This local differentiation allows the system to maintain detection accuracy where needed while accommodating thermal effects elsewhere.
2Area of stationary object
If the optical path length is increased to cover a longer upper die, then monitoring coverage is improved, but shadow enlargement increases causing false detection
Solution Approach 1:
The optical path is segmented into a monitoring region with shorter optical path length for accurate foreign body detection, and a non-monitoring region where shadow enlargement is tolerated. This allows extended upper die coverage while maintaining detection precision in the critical monitoring zone.
Solution Approach 2:
The system transitions from a single-dimensional optical path to a two-dimensional spatial arrangement by introducing a non-monitoring region adjacent to the monitoring region. This dimensional expansion allows the optical path to extend longer while isolating the detection function to a specific zone where precision is maintained.
3Loss of energy
If the press brake operates in cold environmental temperature, then energy efficiency is improved, but temperature gradient causes air convection and light bending
Solution Approach 1:
The harmful effect of temperature gradient-induced light bending is extracted and isolated to the non-monitoring region. By separating the monitoring region from the thermal convection zone, the system maintains energy efficiency in cold environments while preventing thermal effects from interfering with optical detection.
Solution Approach 2:
The non-monitoring region acts as an intermediary buffer zone between the cold environmental air and the monitoring region. This intermediary space allows temperature gradients and air convection to occur without directly affecting the optical path in the monitoring region, thus eliminating light bending interference.
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
Prevents erroneous detection of foreign bodies, thereby maintaining operational efficiency and safety during bending operations, even with long upper dies, by accurately distinguishing between shadow enlargement and actual foreign body presence.
Implementation Method 1
when a monitoring light B passes through the air layer having a temperature gradient, the monitoring light B is bent toward the cold air region CA due to the difference in a refractive index of the air
Implementation Method 2
a layer of air with a temperature gradient is generated
Data Source
Figure 1~2(b)
Figure 3
Figure 4
AI summary
A determination part 70 determines whether or not a shadow of an upper mold 12 is expanded to a photodiode 564 by laser beam B projected to a light receiver 52 side based on a light receiving state of a photodiode 564 positioned in a vicinity of the upper mold 12. When it is determined that the shadow of the upper mold 12 is expanded to the photodiode 564 positioned in the nearest vicinity of the upper mold 12, the invalidation unit 72 invalidates the photodiode 564. A detection unit 74 detects a presence or absence of a foreign body between the upper mold 12 and a lower mold 14 based on light receiving states of the effective plurality of photodiodes 56 during a lowering operation of an upper table 26.