Flash and tear analysis on plastic tubs
While the moulded tub turns one revolution in its cradle, the mouth rim is imaged tangentially against a backlight. In the profile extracted from the edge silhouette, a peak beyond the band is marked as flash and a notch as a tear.
The profile curve of the full turn and the largest deviation are recorded; an out-of-tolerance tub is flagged together with the defect angles and rejected. The result goes to the process monitoring display with the mould cavity number.
- 01 Positioning
- 02 Edge silhouette
- 03 Profile analysis
- 04 Decide
The tub arrives on the roller line and stops at the station; the presence photo-sensor starts the rotation.
- Rotation
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- Edge deviation
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- Defects
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Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
On light-coloured plastic both flash and tear have the same colour as the body and give no contrast when viewed from the surface. The whole rim must be checked over a full turn, and the tub coming out of the mould settles slightly differently in the cradle every time.
Solution approach
While the tub turns one revolution in its cradle, the mouth lip is imaged tangentially against a backlight; a telecentric lens keeps the silhouette edge independent of distance. Lip height is recorded against the rotation angle and compared with the tolerance band; a peak outside the band is classed as flash and a notch as a tear.
Process steps
- 01
Positioning
The tub arrives on the roller line and stops at the station; the presence photo-sensor starts the rotation.
- 02
Edge silhouette
The backlight comes on and the rim is imaged tangentially as the tub turns.
- 03
Profile analysis
Edge height is plotted against angle and searched for peaks or notches outside the band.
- 04
Decide
The largest deviation of the full turn is compared with the tolerance.
Related applications
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