Drilling Apparatus Oblique Illumination for Scratch Inspection
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Solution Overview
Problem
Existing drilling apparatuses face challenges in automatically detecting circular scratches around through-holes in plates due to the obstruction of the annular pressing member, which hinders the use of dark field illumination techniques for precise inspection.
Innovation Solution
Incorporating a moving drill mechanism and illumination devices inserted through circumferentially distributed holes in the annular pressing member, angled at 25 to 60° relative to the plate surface, to enable dark field inspection by preventing direct reflection of regular light onto the camera.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bright-field technique is used for inspection, then the inspection can be performed with simple illumination, but circular scratches cannot be precisely detected
Solution Approach 1:
The patent changes the illumination angle parameter from perpendicular (bright-field) to oblique (dark-field), specifically setting the angle between the illumination device optical axis and the plate surface normal between 25-60 degrees. This parameter change enables precise detection of circular scratches by causing reflected light from scratches to enter the camera while regular surface reflections are directed away from the camera.
2Measurement precision
If a dark field technique is used for inspection, then circular scratches can be precisely detected, but the illumination is hindered by the presence of the pressing member
Solution Approach 1:
The patent divides the pressing member structure by forming multiple insertion holes through its thickness, allowing illumination devices to be segmented and positioned at different locations. This segmentation enables the illumination devices to approach the plate surface from multiple angles, achieving the required oblique illumination angle for dark-field technique despite the pressing member's presence.
Solution Approach 2:
The patent transitions from attempting to illuminate the plate from the same plane as the camera (2D approach blocked by pressing member) to illuminating from a different angular dimension (3D approach). By positioning illumination devices through insertion holes at oblique angles, the system accesses the plate surface from a different spatial dimension, enabling dark-field illumination without removing the pressing member.
3Extent of automation
If the drill is made movable between machining position and retraction position, then automatic inspection can be performed, but the device complexity increases
Solution Approach 1:
The patent merges the drill's positioning function with the inspection process by utilizing the existing movable mechanism that positions the drill between machining and retraction positions. This existing movement capability is combined with the illumination and camera systems to create an integrated automatic inspection function, avoiding the need for separate positioning mechanisms and reducing overall system complexity.
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
Enables precise automatic circular scratch inspection using a dark field technique by ensuring that irregularly reflected light from scratches is captured by the camera, overcoming the limitations of bright-field techniques.
Implementation Method 1
the light that is reflected regularly on the surface of the plate is directly incident on the camera (bright-field technique). However, with the bright-field technique, circular scratches captured in the image cannot be precisely detected. On the other hand, in the case of adopting a dark field technique, the light is emitted at such an angle that the light reflected regularly on the surface of the plate is not directly incident on the camera, but the light that is reflected irregularly on the circular scratches is directly incident on the camera.
Data Source
AI summary
A drilling apparatus includes: a table supporting a plate; a drill machining a through-hole in the plate; an annular pressing member pressing the plate around the through-hole; a camera capturing a plate surface image through an inner space of the pressing member; and a moving device moving the drill between machining and retraction positions, the machining position being at which the drill center coincides with the pressing member center, the retraction position being a position at which the drill is positioned outside a field of view of the camera. Insertion holes distributed in a circumferential direction are formed in the pressing member, and illumination devices, each emitting light to the plate surface around the through-hole, are inserted in the respective insertion holes. An optical axis direction of each of the illumination devices inserted in the respective insertion holes and the plate surface form an angle of 25 to 60°.