Metal container inspection device

A metal container manufacturing installation, comprising:

• a feeder configured to supply a metal disc;
• an extrusion press configured to extrude the metal disc to form a metal container, the metal container having a cylindrical body with an outer lateral surface, a bottom, an open end opposite the bottom and a central longitudinal axis extending along the cylindrical body, the extrusion press including an extruder that is configured to force the metal disc through a die to transform the metal disc into the metal container, the extrusion press producing striations on the outer lateral surface of the metal container extending in a direction parallel to the central longitudinal axis of the metal container;
• and
• a trimming and brushing machine including:
• a cutting part with a cutting blade for cutting an excess part of the open end of the metal container;
• a brushing part having a brush for brushing the outer lateral surface;
• an actuator for rotating the metal container about the central longitudinal axis;
• an illumination source configured to illuminate the outer lateral surface by producing an illumination plane incident on the outer lateral surface perpendicular to the striations formed in the outer lateral surface, the illumination plane forming an angle of 0-15° with respect to a plane tangent to the outer lateral surface;
• a camera oriented to capture images of the outer lateral surface illuminated by the illumination source;
• and
• an image evaluation unit configured to detect the striations in the images captured by the camera by measuring a depth value of the striations as a function of light reflected from the outer lateral surface and comparing the depth value with a depth threshold value and determining whether the depth value exceeds the depth threshold value;
• the actuator being configured to rotate the metal container about the central longitudinal axis such that the camera obtains the images of the outer lateral surface during at least one complete revolution of the metal container.

A method for detecting striations in an outer lateral surface of a cylindrical body of a metal container, the cylindrical body having a central longitudinal axis, the striations extending in a direction parallel to the central longitudinal axis, the method comprising:

• illuminating the outer lateral surface by producing an illumination plane incident on the outer lateral surface perpendicular to the striations, the illumination plane forming an angle of 0-15° with respect to a plane tangent to the outer lateral surface;
• capturing images of the outer lateral surface illuminated by the illumination source;
• detecting the striations in the images captured by measuring a depth value of the striations as a function of light reflected from the outer lateral surface and comparing the depth value with a depth threshold value and determining whether the depth value exceeds the depth threshold value;
• and
• rotating the metal container about the central longitudinal axis such that the images of the outer lateral surface are obtained during at least one complete revolution of the metal container.