"VISION GROUP FOR AN OPTICAL INSPECTION MACHINE FOR THE

QUALITY CONTROL OF PARTS"

[0001] The present invention refers to a viewing unit for an optical inspection machine for the quality control of parts, in particular gaskets.

[0002] According to the preamble of claim 1, there is a known viewing unit that comprises a video camera provided with a lens slidably held by a frame so as to move vertically by translational movement by a motor apparatus .

[0003] The video camera is designed to acquire images of a part to be checked, positioned beneath the frame, generally on a rotary table.

[0004] The purpose of this invention is to propose a viewing unit capable of acquiring images of parts having considerably different shapes and/or dimensions, using the same video camera.

[0005] This purpose is achieved with a viewing unit according to claim 1. The dependent claims describe preferred embodiments of the invention.

[0006] The features and advantages of the viewing unit according to the invention will become clear from the description given below of preferred embodiments, given solely as non-limiting examples in reference to the enclosed figures, wherein:

[0007] - figure 1 is an elevation view of a viewing unit according to the invention;

[0008] - figure 2 is a perspective view of the viewing unit;

[0009] - figure 3 is a perspective view of the viewing assembly of the viewing unit;

[0010] - figure 4 shows the viewing assembly as a partial axial cross-section;

[0011] - figure 5 is an elevation view of the viewing assembly;

[0012] - figure 6 is a plan view of the viewing assembly from the bottom;

[0013] - figure 7 is an exploded perspective view of some components of the viewing assembly; and

[0014] - figure 8 is a perspective view of an example of an optical inspection machine for the quality control of parts that uses a viewing unit according to the invention .

[0015] In these drawings, the number 1 refers to a viewing unit as a whole according to the invention.

[0016] Viewing unit 1 comprises a viewing assembly 10 slidably supported by a frame 12.

[0017] In one embodiment, frame 12 is formed primarily along a vertical axis X between an upper plate 12 and a lower plate 12". For example, an illuminator 140 (figure 8) suitable for illuminating the part framed by viewing assembly 10 can be secured to lower plate 12".

[0018] Viewing unit 1 is provided with a first drive unit 14 suitable for moving viewing assembly 10 axially along frame 12.

[0019] According to the invention, viewing assembly 10 comprises a video camera 16 and a plurality of lenses 18a, 18b, 18c, 18d having different optical properties. Lenses 18a-18d can be used selectively with video camera 16, for example according to the shape and/or dimensions of the part to be checked.

[0020] By means of corresponding lens mounts 182, lenses 18a-18d are secured in corresponding lens openings 20 made in a peripheral area of a rotary plate 22.

[0021] By means of a corresponding video camera mount 162 suitable to be connected to a lens, video camera 16 is positioned in viewing assembly 10 so as to pass in front of the side of the peripheral area of rotary plate 22 opposite the side from which the lenses extend.

[0022] Viewing assembly 10 is provided with a second drive unit 24 suitable for rotating rotary plate 22 so as to have lens openings 20 selectively face video camera mount

162 so as to make video camera mount 162 and one of the plurality of lenses 18a, 18b, 18c, and 18d coaxial to each other.

[0023] It is known that a video camera and a lens connect together by screwing the lens mount to the mount on the video camera. A video camera with a particular mount can only be connected to lenses having mounts that are compatible with that of the video camera, to ensure proper optical operation of the assembly.

[0024] According to a preferred embodiment, video camera 16 has a video camera mount 162 suitable for connecting lenses having an ideal focal length, that is, the optimum focal length for video camera 16 being used, which is greater than the real focal length of lenses 18a, 18b,

18c, and 18d secured to rotary plate 22. The thickness of rotary plate 22 and the play in the gap between rotary plate 22 and video camera mount 162 are chosen so as to compensate for the difference between the ideal focal length and the actual focal length.

[0025] Consequently, viewing unit 1 according to the invention uses a video camera and lenses that are incompatible with each other. Rotary plate 22 therefore serves as an adaptor that makes the video camera and set of lenses optically compatible with each other.

[0026] The "play in the gap" refers to the air gap needed to ensure rotation of rotary plate 2 in relation to video camera mount 162 without friction wear. [0027] In one practical embodiment of the invention, video camera mount 162 is a "CS" mount and lens mount 182 is a "C" mount .

[0028] Consequently, since there is a difference of 5 mm between a "CS" mount and a "C" mount, the thickness of rotary plate 22 is about 4.5 mm, each lens opening 20 is a threaded opening into which lens mount 182 is completely screwed, and the play in the gap is about 0.5 mm.

[0029] According to one embodiment, viewing assembly 10 further comprises an electromechanical centering bolt 30 which is actuatable to cause a centering pin 32 to engage with conical centering holes 34 made in rotary plate 22.

[0030] Second drive unit 24 causes rotary plate 22 to rotate in such a way as to position a lens 18a-18d substantially in front of video camera mount 162. At this point electromechanical bolt 30 is electrically actuated so as to cause centering pin 32 to enter one of conical centering holes 34. In this way a very precise alignment between the lens and video camera mount 162 is achieved along with strong angular locking of rotary plate 22.

[0031] In one embodiment, viewing assembly 10 is assembled to a support structure 40 comprising a fixed plate 42 that holds video camera 16 and that is coaxial to and facing rotary plate 22. [0032] In addition, support structure 40 forms a U-bracket 44 that extends from fixed plate 42 and that supports second drive unit 24 at its top, coaxially to fixed plate 42 and rotary plate 22.

[0033] Second drive unit 24 comprises a drive shaft 46 that passes through fixed plate 42 and to which rotary plate 22 is secured.

[0034] In one embodiment, electromechanical centering bolt 30 is also supported by fixed plate 42.

[0035] In one embodiment, lateral arms 48 extend from U- bracket 44 to connect to corresponding guide rods 50 of frame 12 for the translational movement of viewing assembly 10 along said guide rods 50.

[0036] Figure 8 shows an example of an optical inspection machine 100 for the quality control of parts, in particular gaskets. Machine 100 comprises a rotary table 102 on which are positioned parts to be inspected, at least one inspection station 104 comprising, above and/or below rotary table 102, a viewing unit 1 as described above for inspecting one or more outer and/or inner surfaces of the parts placed on rotary table 102.

[0037] In order to satisfy contingent requirements, a person skilled in the art could make modifications, adaptations, and substitutions of parts with functionally equivalent ones to the embodiments of the viewing unit according to the invention, without exceeding the scope of the following claims. Each feature described as belonging to a possible embodiment may be implemented independently of the other described embodiments.