WO2017016596A1

WO2017016596A1 - Machine and method for inspecting the conformity of products

Info

Publication number: WO2017016596A1
Application number: PCT/EP2015/067290
Authority: WO
Inventors: Massimo Bonardi; Emidio Zorzella
Original assignee: Antares Vision S.R.L.
Priority date: 2015-07-28
Filing date: 2015-07-28
Publication date: 2017-02-02

Abstract

The inspection machine (1) for inspecting the conformity of products (4) comprises a first roller (2) equipped with first housings (3) for positioning products (4) and a first controlled depression compartment (6) for retaining products (4) in the first housings (3), a vibrating loader (5) connected to a slide (17) for directing the products (4) to a loading zone (21) on the first roller (2), a second roller (7) parallel to and opposite the first roller (2) and equipped with second housings (8) for positioning the products (4) and a second controlled depression compartment (9) for retaining the products (4) in the second housings (8), transfer means for transferring the products (4) into an overturned position from the first housings (3) to the second housings (8), fluid pre-alignment means in the first housings (3) of the products (4) supplied by the loader and means for the precise positioning in the first housings (3) of the pre-aligned products (4) being provided in cascade.

Description

MACHINE AND METHOD FOR INSPECTING THE CONFORMITY OF PRODUCTS

DESCRIPTION

The present invention relates to a machine and a method for inspecting the conformity of products.

Inspection machines are known in the pharmaceutical and food fields, or in other sectors where it is necessary to identify various products not able to pass the quality test and move them away from the packaging line.

In such machines, through the use of video cameras, there is active control of some product characteristics, such as checking for integrity, the presence of surface impurities and the presence of typical production faults.

An inspection machine known on the market comprises a first roller equipped with first product positioning housings, a first controlled depression compartment for retaining products in the first housings, a second roller parallel to and opposite the first roller and equipped with second product positioning housings, a second controlled depression compartment for retaining the products in the second housings, transfer means for transferring the products into the overturned position from the first housings to the second housings, a first device for checking the conformity of the products positioned in the first housings, a second device for checking the conformity of the products positioned in the second housings, and means for selecting the checked and conforming products.

Loading the products into the first housings of the first roller is a delicate operation since positioning precision is required for correctly checking the conformity and at the same time operating quickly so as to guarantee high productivity.

During loading it may happen that products are not deposited into the relative housings which therefore remain empty or are positioned unsuitably for allowing conformity to be reliably checked. In both cases the productivity of the inspection machine is penalised.

Furthermore, the inside of the inspection machine is not always easily accessible hence complicating the inspection, maintenance and replacement of some components. In particular, it may be rather complicated to replace the rollers according to the specific type of products to be tested.

Another drawback complained of in a traditional inspection machine consists of the limited efficiency of detecting faults when they are of very different types from one another.

For example, the checking device, based on video cameras, may be more efficient in the detection of surface faults, such as breakages, chips and malformations, and less efficient in the detection of colour or impurity faults, or vice versa.

The technical task of the present invention is therefore to provide an inspection method and machine of the type described above that makes it possible to eliminate the cited technical drawbacks of the prior art.

Within the context of this technical task, an object of the invention is to provide an inspection machine of the type described above which is highly productive.

Another object of the invention is to provide an inspection machine that is easily accessible inside for the inspection, maintenance and replacement of its components. Another object of the invention is to provide an inspection machine that is highly efficient in the detection of faults of different types on the products.

Finally, an object of the invention is to provide an inspection machine with a simple construction and reliable operation.

The technical task, as well as these and other objects, according to the present invention are reached by providing an inspection machine for inspecting the conformity of products comprising a first roller equipped with first housings for positioning the products and a first controlled depression compartment for retaining the products in the first housings, a vibrating loader connected to a slide for directing the products towards a loading zone on the first roller, a second roller parallel to and opposite the first roller and equipped with second housings for positioning the products and a second controlled depression compartment for retaining the products in the second housings, transfer means for transferring the products into an overturned position from the first housings to the second housings, a first device for checking the conformity of the products positioned in the first housings, a second device for checking the conformity of the products positioned in the second housings, said first and second checking devices comprising a corresponding image acquisition system from a transit zone of the products, characterised in that on the first roller, upstream of the first checking device with respect to the advancement direction of the products, fluid pre- alignment means of the products supplied by the loader into the first housings and precise positioning means in the first housings of the pre-aligned products are provided in cascade. In a preferred embodiment of the invention the fluid pre-alignment means comprise dispensing nozzles of a calibrated air jet into the first housings.

In a preferred embodiment of the invention the precise positioning means comprise feeler organs arranged tangentially to the first roller.

In a preferred embodiment of the invention the precise positioning means are of the fluid type.

In a preferred embodiment of the invention between the fluid pre-alignment means and the precise positioning means mechanical removal means are provided for removing excess products.

In a preferred embodiment of the invention the mechanical removal means for removing excess products comprise at least one rotating brush arranged tangentially to the first roller.

In a preferred embodiment of the invention the brush rotates with an axis of rotation parallel to the axis of the first roller and angular speed in the same direction as the first roller for redirecting the excess products to the loading zone. The present invention also discloses an inspection method for inspecting the conformity of products characterised in that it comprises, during the continuous and synchronised rotation of first and second opposite rollers, the subsequent steps of channelling the products into first housings in the first roller, subjecting the products thus channelled to a jet of air so as to pre-align them in the first housings, mechanically removing the products from the first roller that have not been channelled into the first housings, precisely positioning the pre-aligned products in the first housings, illuminating a first transit zone of the precisely positioned products retained in the first housings through a controlled depression and acquiring the image of the precisely positioned products in transit from the first illuminated transit zone for a first inspection, transferring the products subjected to the first check into an overturned position in second housings in the second roller, illuminating a second transit zone of the products retained in a precise position in the second housings through a controlled depression and acquiring the image of the precisely positioned products in transit from the second transit zone illuminated for a second inspection, and selecting the conforming products.

Other characteristics of the present invention are also defined in other dependent claims.

Further characteristics and advantages of the invention will more fully emerge from the description of a preferred but not exclusive embodiment of the inspection machine according to the invention, illustrated by way of indicative and non- limiting example in the accompanying figures of the drawings, in which:

figures 1 and 2 show an axonometric view of the inspection machine,

figure 3 schematically shows a raised lateral view of the inspection machine of figures 1 and 2;

figure 4 schematically shows an axonometric view of the two lighting systems and the image acquisition system of the first checking device;

figure 5 schematically shows an axonometric view of the two lighting systems and the image acquisition system of the second checking device;

figure 6 schematically shows the position of the three linear video cameras with centred optics envisaged in the second checking device; figure 7 schematically shows the position of the two linear video cameras with decentred optics envisaged in the second checking device;

figure 8a shows the signal of the encoder used for timing the acquisitions of the optical acquisition system and of the two lighting systems in each checking device; figure 8b shows the acquisition control pulses for the optical acquisition system; figure 8c shows the acquisition control pulses for the first lighting system;

figure 8d shows the acquisition control pulses for the second lighting system;

figure 9a shows the sequence of lines acquired overall with oblique and incident light alternatively active;

figure 9b shows the reconstruction of the image with the lines acquired with oblique light active;

figure 9c shows the reconstruction of the image with the lines acquired with incident light active;

figure 10 shows a plan view from above of the loading zone of the first roller;

figure 11 shows a sectional view of a first positioning housing; and

figure 12 shows a sectional view of a second positioning housing.

With reference to the figures mentioned, an inspection machine for inspecting the conformity of products is shown indicated overall with the reference number 1.

The machine 1 comprises a control unit which with the aid of an encoder coordinates the various activities.

The machine 1 comprises a first roller 2 equipped with first housings 3 for positioning the products 4, a vibrating loader 5 connected to a slide 17 for directing the products 4 towards a loading zone 21 on the first roller 2, a first controlled depression compartment 6 for retaining the products 4 in the first housings 3, a second roller 7 parallel to and opposite the first roller 2 and equipped with second housings 8 for positioning the products 4, a second controlled depression compartment 9 for retaining the products 4 in the second housings 8, transfer means for transferring the products 4 into an overturned position from the first housings 3 to the second housings 8, a first device 11 for checking the conformity of the products 4 positioned in the first housings 3, a second device 12 for checking the conformity of the products 4 positioned in the second housings 8, and means 13 for selecting the checked and conforming products 4.

The vibrating loader 5 is positioned inside a shell of the machine 1 to prevent the products 4 being contaminated by external agents.

The first roller 2 has a rotating hollow external cylindrical part 2a supported coaxially by a fixed hollow internal cylindrical part 2b.

The second roller 7 has a rotating hollow external cylindrical part 7a supported coaxially by a fixed hollow internal cylindrical part 7b.

The first positioning housings 3, present on the rotating part 2a of the first roller 2, are ordered in equally spaced rectilinear rows that extend along axial generatrices of the rotating part 2a of the first roller 2 and in equally spaced circular rows that extend along circumferential generatrices of the rotating part 2a of the first roller 2. The first housings 3 on the bottom have calibrated through channels 3 ' in the thickness of the wall of the rotating part 2a of the first roller 2. The channels 3' extend radially with respect to the axis of the first roller 2.

The second positioning housings 8, present on the rotating part 7a of the second roller 7, are ordered in equally spaced rectilinear rows that extend along axial generatrices of the rotating part 7a of the second roller 7 and in equally spaced circular rows that extend along circumferential generatrices of the rotating part 7a of the second roller 7. The second housings 8 on the bottom have calibrated through channels 8' in the thickness of the wall of the rotating part 7a of the second roller 7. The channels 8' extend radially with respect to the axis of the second roller 7.

The first positioning housings 3 are preferably different in conformation from the second positioning housings 8 to leave different surfaces of the products 4 positioned in them exposed to the light.

In the specific case in question the first housings 3 are conformed so as to leave at least one first base 4a of the products 4 exposed to the light, while the second positioning housings 8 are conformed to leave at least the four lateral faces 4c, 4d, 4e, 4f and the second base 4b of the products 4 exposed to the light.

In particular the first positioning housings 3 are formed by hollows 3 a within which the products 4 are housed completely or almost, while the second positioning housings 8 are formed by pedestals 8a that support the products 4 in a cantilever fashion.

The slide 17 has guiding grooves 17a with progressively increasing width and depth from an initial zero value. The number of grooves 17a is equal to the number of circular rows of first housings 3. Each groove 17a is aligned with a corresponding circular row of first housings 3 to deposit a product 4 into the first housing 3 that passes in front of it during the rotation of the first roller 2. The specific conformation and arrangement of the slide 17 allows the products 4 to be channelled effectively and smoothly towards the first housings 3 provided on the first roller 2.

At the loading zone 21 a level sensor 46 is positioned adapted to stop the loader 5 when a certain threshold in the level of products 4 accumulated in the loading zone 21 is exceeded.

Advantageously at a section of the first roller 2 arranged, with respect to the advancement direction of the products 4 on the first roller 2, upstream of the first checking device 11, fluid pre-alignment means of the products 4 in the first housings 3 supplied by the vibrating loader 5 and precise positioning means in the first housings 3 of the pre-aligned products 4 are provided in cascade.

The fluid pre-alignment means comprise dispensing nozzles 18 of a calibrated air jet, and in particular a row of fixed nozzles 18 arranged along an axial generatrix of the fixed hollow internal cylindrical part 2b of the first roller 2. The nozzles 18 are designed to blow air into the channels 3 ' of the rectilinear rows of housings 3 that individually transit in front of them during the rotation of the first roller 2. The air jet is calibrated to allow any products 4 deposited in precariously balanced conditions to settle into the first housings 3.

The precise positioning means comprise feeler organs 20, and in particular a row of feeler organs 20 arranged tangentially to an axial generatrix of the rotating hollow external cylindrical part 2a of the first roller 2. The feeler organs 20 are designed to move the products 4 housed in the rectilinear rows of housings 3 against a wall of the first housings 3 which individually transit in front of them during the rotation of the first roller 2.

The feeler organs 20 can oscillate in contrast and due to the action of relevant elastic means (not shown) with an axis of oscillation parallel to the axis of the first roller 2.

Alternatively, fluid precise positioning means can be provided which with higher construction complexity prevent the manipulation of the products 4 due to direct contact hence further limiting the risk that they could get damaged.

Between the fluid pre-alignment means and the precise positioning means mechanical removal means are also provided for removing the excess products 4. The mechanical removal means for removing excess products 4 comprise at least one rotating brush 19 arranged tangentially to an axial generatrix of the rotating hollow external cylindrical part 2a of the first roller 2.

The brush 19 rotates with an axis of rotation parallel to the axis of the first roller 2 and angular speed in the same direction as that of the first roller 2 to redirect the excess products 4 to the loading zone 21.

The first controlled depression compartment 6, connected to relevant means for creating a depression within it, is defined by the outer surface of the fixed part 2b of the first roller 2 and extends fully or prevalently from one side of the plane L passing through the axes of the first and second roller 2, 7. This first controlled depression compartment 6 in particular subtends an angle slightly less than 180°. The first housings 3 through the channels 3 ' can establish fluid communication with the first controlled depression compartment 6 when they transit in front of it. The first checking device 1 1 faces the fixed part 2b of the first roller 2 where the first controlled depression compartment 6 is provided. In particular, the first checking device 11 is contained within a box-like body that faces the first roller 2 with an arched transparent wall 14 coaxial to the first roller 2 itself.

The first checking device 11 is supported by a slide 22 translatably and radially with respect to the first roller 2 to allow the replacement and maintenance of the latter.

The second controlled depression compartment 9, connected to relevant means for creating a depression within it, is defined by the outer surface of the fixed part 7b of the second roller 7 and extends folly or prevalently, with respect to the first controlled depression compartment 6, from the other side of the plane L passing through the axes of the first and second roller 2, 7. This second controlled depression compartment 9 in particular subtends an angle slightly less than 180°. The second housings 8 through the channels 8' can establish fluid communication with the second controlled depression compartment 9 when they transit in front of it.

The second checking device 12 faces the fixed part 7b of the second roller 7 where the second controlled depression compartment 9 is provided. In particular, the second checking device 12 is contained within a box-like body that faces the second roller 7 with an arched transparent wall 15 coaxial to the second roller 7 itself.

The second checking device 12 is supported by a slide 23 translatably and radially with respect to the second roller 7 to allow the replacement and maintenance of the latter. The first roller 2 comprises a blowing and sucking device 26 for cleaning the first housings 3, in a diametrically opposite position to the first controlled depression compartment 6, hence in a zone of the first roller 2 where the first housings 3 are always free.

The second roller 7 comprises a blowing and sucking device 27 for cleaning the second housings 8, in a diametrically opposite position to the second controlled depression compartment 9, hence in a zone of the second roller 7 where the second housings 8 are always free.

The transfer means for transferring the products 4 into an overturned position from the first housings 3 to the second housings 8 are configured to generate controlled overpressure and specifically comprise, at the transfer zone, a row of fixed nozzles 10 arranged along an axial generatrix of the fixed hollow internal cylindrical part 2b of the first roller 2. The nozzles 10 are provided to blow air into the channels 3' of the rectilinear rows of housings 3 that individually transit in front of them during the rotation of the first roller 2. The air jet can exert on the products 4 the necessary thrust to bring them into the overturned position in the rectilinear row of second housings 8 that are opposite the rectilinear row of first housings 3 affected by the air jet.

Selection means 13 for selecting checked and conforming products 4 are also configured to generate a controlled overpressure and specifically comprise, at the unloading zone of the products 4 from the second roller 7, at least a first, a second and, respectively, a third row of fixed nozzles 13a, 13b, 13c arranged along a first, a second and respectively a third axial generatrix of the fixed hollow internal cylindrical part 7b of the second roller 7. The nozzles 13a, 13b, 13c are designed to blow air into the channels 8' of the rectilinear rows of housings 8 that individually transit in front of them during the rotation of the second roller 7. Each individual nozzle of each row of nozzles 13a, 13b 13c can be piloted individually by the control unit independently from the other nozzles to release the product 4 that transits in front of it into a corresponding collector 24a, 24b, 24c according to the outcome of the quality check, for example according to whether the product 4 does not conform (24a), has not been inspected (24b) or conforms (24c).

The collector 24c of conforming products is positioned strategically, protected from the slide 25 in order to prevent products 4 already checked being "polluted" by products 4 not yet inspected that are accidentally detached from the housing 3 of the roller 2.

Alongside the collectors 24a, 24b, 24c there is a further collector 24d into which through a slide 25 products 4 accidentally detached from the first roller 2 above are conveyed during the first check.

The inspection method for checking the conformity of the products 4 substantially comprises the following steps in a time sequence.

The first and the second roller 2 and 7 rotate continuously in a synchronised way at the same constant peripheral speed but in the opposite direction of rotation.

The vibrating loader 5 supplies the slide 17 which at the loading zone 21 directs the products 4 into the first housings 3 of the first roller 2.

Products 4 that are unstably balanced in the first housings 3 during their advancement on the first roller 2 are subjected to a jet of air from the nozzles 18 in order to settle in the first housings 3, while excess products 4 deposited on the first roller 2 outside the first housings 3 are rejected by the brush 19 towards the loading zone 21.

Pre-aligned products 4 are then positioned precisely by the feeler organs 20 in the first housings 3.

Now, let's follow the outcome of the products 4 precisely positioned in a rectilinear row of first housings 3 during the advancement due to the rotation of the first roller 2 and the second roller 7.

The reference transit zone 28 and respectively 29 is defined by the surface brushed by an axial generatrix of the rotating part 2a of the roller 2 and respectively by the rotating part 7a of the roller 7 during the rotation of the roller 2 and respectively 7 by a first and a second angular reference position.

The illuminated transit zone 28 and respectively 29 is sized for the crossing of a single rectilinear row at a time of first housings 3 and second housings 8 respectively.

Due to the effect of the rotation of the rotating part 2a with respect to the fixed part 2b of the first roller 2 the first housings 3, remaining in fluid communication through the channels 3' with the first controlled depression compartment 6 active for firmly and precisely retaining the products 4 in position, transit through the first transit zone 28 which is illuminated according to the methods described below. The image of the products 4 transiting from the first transit zone 28 is acquired according to the methods shown below for a first fault check. As the rotation of the rotating part 2a continues with respect to the fixed part 2b of the first roller 2 the first housings 3 are staggered from the first controlled depression compartment 6 until the channels 3' are aligned with the nozzles 10 active to transfer into the overturned position the products 4 in the second housings 8 of the second roller 7 that are opposite the first housings 3 of the first roller 2. The row of second housings 8 that receives the products 4 is in fluid communication through the channels 8' with the second controlled depression compartment 9 that firmly and precisely retains the products 4 in position. Due to the effect of the rotation of the rotating part 7a with respect to the fixed part 7b of the second roller 7 the second housings 8, remaining in fluid communication through the channels 8' with the second active controlled depression zone 9 to firmly and precisely retain the products 4 in position, transit through the second transit zone 29 that is illuminated according to the methods described below. The image of the products 4 transiting from the second transit zone 29 is acquired according to the methods shown below for a second fault check. As the rotation of the rotating part 7a continues with respect to the fixed part 7b of the second roller 7 the second housings 8 align the channels 8' in succession with the nozzles 13a, 13b and 13c piloted individually by the control unit for unloading the products 4 selectively into the corresponding collector 24a, 24b, 24c according to the outcome of the conformity check.

Each checking device 11 and respectively 12 comprises at least a first and a second independent lighting system arranged and configured to substantially illuminate a same transit zone 28 and respectively 29 of the products 4, and an image acquisition system of the transit zone 28 and respectively 29.

The first lighting system is arranged and configured for the emission of oblique light on the transit zone 28, 29.

The second lighting system is arranged and configured for the emission of incident light on the transit zone 28, 29.

We initially refer to the first checking device 1 1.

The first lighting system comprises a first string 30 of LEDs 30a, 30b spatially aligned parallel to the axis of the first roller 2.

The LEDs 30a, 30b are split into two groups according to the emission direction LI, L2. The LEDs 30a, 30b are in particular configured for emission in two emission directions LI, L2 coplanar and orthogonal to one another.

The first lighting system also comprises a second string 31 of LEDs 31a, 31b spatially aligned parallel to the axis of the first roller 2.

The LEDs 31a, 31b are split into two groups according to the emission direction L3, L4. The LEDs 31a, 31b are in particular configured for emission in two emission directions L3, L4 coplanar and orthogonal to one another, and orthogonal in turn to the two emission directions LI, L2 of the LEDs 30a, 30b of the first string 30 of LEDs.

The number of LEDs in each string 30, 31 is equal to twice the number of first housings 3 in each rectilinear row of first housings 3.

The first lighting system associates with each first housing 3 in the transit zone 28 a corresponding set of four LEDs 30a, 30b, 31a, 31b dedicated to its oblique lighting from four different angles.

The second lighting system comprises a first string 32 of LEDs 32a spatially aligned parallel to the axis of the first roller 2 and configured for emission in a single emission direction L5.

The second lighting system also comprises a second string 33 of LEDs 33a spatially aligned parallel to the axis of the first roller 2 and configured for emission in a single emission direction L6 inclined with respect to the emission direction L5 of the first string 32 of LEDs.

The number of LEDs 32a, 33a, in each string 32, 33 is equal to the number of first housings 3 in each rectilinear row of first housings 3.

The second lighting system associates with each first housing 3 in the transit zone 28 a corresponding set of two LEDs 32a, 33a, dedicated to its incident lighting from two different angles.

The image acquisition system comprises in the specific case a single linear video camera 34 sufficient for acquiring the image of the products 4 whose first base 4a only is substantially exposed to the light.

We now refer to the second checking device 12.

The first lighting system is the same as that described for the first checking device 1 1.

It comprises a first string 36 of LEDs 36a, 36b spatially aligned parallel to the axis of the second roller 7.

The LEDs 36a, 36b are split into two groups according to the emission direction L9, L10. The LEDs 36a, 36b are in particular configured for emission in two emission directions L9, L10 coplanar and orthogonal to one another.

The first lighting system also comprises a second string 35 of LEDs 35a, 35b spatially aligned parallel to the axis of the second roller 7. The LEDs 35a, 35b are split into two groups according to the emission direction L7, L8. The LEDs 35a, 35b are in particular configured for emission in two emission directions L7, L8 coplanar and orthogonal to one another, and orthogonal in turn to the two emission directions L9, L10 of the LEDs 36a, 35b of the first string 35 of LEDs.

The number of LEDs in each string 35, 36 is equal to twice the number of second housings 8 in each rectilinear row of second housings 8.

The first lighting system associates with each second housing 8 in the transit zone 29 a corresponding set of four LEDs 35a, 35b, 36a, 36b dedicated to its oblique lighting from four different angles.

The second lighting system is the same as that described for the first checking device 11.

It comprises a first string 37 of LEDs 37a spatially aligned parallel to the axis of the second roller 3 and configured for emission in a single emission direction LI 1. The second lighting system also comprises a second string 38 of LEDs 38a spatially aligned parallel to the axis of the second roller 3 and configured for emission in a single emission direction L12 inclined with respect to the emission direction LI 1 of the first string 37 of LEDs.

The number of LEDs 37a, 38a, in each string 37, 38 is equal to the number of second housings 8 in each rectilinear row of second housings 8.

The second lighting system associates with each second housing 8 in the transit zone 29 a corresponding set of two LEDs 37a, 38a, dedicated to its incident lighting from two different angles. The image acquisition system comprises in the specific case five linear video cameras 39, 40, 41, 42, 43, for acquiring the image of the products 4 whose second base 4b and four lateral sides 4c, 4d, 4e, 4f are substantially exposed to the light. The linear video cameras 39, 40, 41 , 42, 43 have different pointing angles onto the transit zone 29 and in particular the video camera 41 is pointing onto the second base 4b of products 4 transiting in the transit zone 29, the video camera 39 is pointing onto the side face 4f of the products 4 transiting in the transit zone 29, the video camera 40 is pointing onto the side face 4e of the products 4 transiting in the transit zone 29, the video camera 42 is pointing onto the side face 4c of the products 4 transiting in the transit zone 29, and the video camera 43 is pointing onto the side face 4d of the products 4 transiting in the transit zone 29.

In order to contain the transversal dimensions of the second checking device 12 the image is reflected by special reflecting mirrors 44, 45 since the inspection is performed looking laterally and therefore not perpendicular to the row of products 4. For a focused image the video cameras 42 and 43 therefore have decentred optics.

The inspection method of the conformity of products 4 envisages illuminating the same transit zone 28 and respectively 29 of the products 4 with the first and the second independent lighting system of the first checking device 11 and respectively the second checking device 12.

The lighting of the transit zone 28, 29 is piloted stroboscopically by alternating switching on the first and the second lighting system.

The inspection method therefore envisages acquiring images from the transit zone 28, 29 both when it is illuminated with oblique light from the first lighting system and when it is lit with incident light from the second lighting system.

The images from the transit zone 28 are acquired with the linear video camera 34 while those from the transit zone 29 are acquired with the linear video cameras 39, 40, 41 , 42, 43.

The lines of the image acquired are separated so as to obtain a first image of the products 4 illuminated by the first lighting system and a second image of the products 4 illuminated by the second lighting system in each of which the products

4 are substantially positioned in the same spatial coordinates.

The image acquisition process, with reference to the first checking device, is schematically illustrated in figures 8a to 8d and 9a to 9c and is substantially as follows.

The video camera 34 points onto the transit zone 28.

The encoder generates equally spaced electric pulses and at the rising front of the electric pulse the control unit generates both an acquisition activation control pulse for the linear video camera 34 and a light emission control pulse for the first lighting system, while at the falling front of the electric pulse the control unit generates both an acquisition activation control pulse for the linear video camera 34 and a light emission control pulse for the second lighting system.

Naturally, the control unit generates a control pulse for interrupting the emission of light for the first lighting system before or at the same time as the light emission control pulse for the second lighting system and vice versa.

The lines a_h a₂...a_n acquired by the linear video camera 34 when the transit zone 28 is illuminated by the first lighting system alternate with the lines b_t, b₂...b_n acquired by the linear video camera 34 when the transit zone 28 is illuminated by the second lighting system. Subsequently, through relevant software, the control unit reconstructs the first image of the products 4 illuminated by the first lighting system and the second image of the products 4 illuminated by the second lighting system by separating the lines a_{] 5} a₂...a_n from the lines a a₂...a_n and stacking the lines a._\, a₂...a_n according to the same order of acquisition and the lines bj, b₂...b_n according to the same order of acquisition.

Advantageously, the acquisition system acquires from the transit zone 28 a first and respectively a second image in each of which the products 4 are positioned substantially at the same spatial coordinates.

In this way it is possible to correlate the two images acquired in two different lighting conditions to highlight faults that may not have easily emerged from the examination of just one of the images. For example, lighting with oblique light is more suitable for the identification of surface faults such as breakages, chips and malformations, while lighting with incident light is more suitable for identifying colour or impurity faults.

The image acquisition process, with reference to the second checking device, will not be repeated since it is exactly the same as what has just been described. It should only be noted that in this case all the video cameras 39, 40, 41, 42, 43 are pointing fixed onto the transit zone 29.

The machine and method for inspecting the conformity of products thus conceived are susceptible to numerous modifications and variants, all of which falling within the scope of the inventive concept; moreover, all details may be replaced with other technically equivalent elements.

The materials used, as well as the dimensions, may in practice be of any type according to requirements and the state of the art.

Claims

1. An inspection machine (1) for inspecting the conformity of products (4) comprising a first roller (2) equipped with first housings (3) for positioning the products (4) and a first controlled depression compartment (6) for retaining the products (4) in the first housings (3), a vibrating loader (5) connected to a slide (17) for directing the products (4) towards a loading zone (21) on the first roller (2), a second roller (7) parallel to and opposite the first roller (2) and equipped with second housings (8) for positioning the products (4) and a second controlled depression compartment (9) for retaining the products (4) in the second housings (8), transfer means for transferring the products (4) into an overturned position from the first housings (3) to the second housings (8), a first device (11) for checking the conformity of the products (4) positioned in the first housings (3), a second device (12) for checking the conformity of the products (4) positioned in the second housings (8), said first and second checking devices (11, 12) comprising a corresponding image acquisition system from a transit zone (28, 29) of the products (4), characterised in that on the first roller (2), upstream of the first checking device (11) with respect to the advancement direction of the products (4), fluid pre-alignment means of the products (4) supplied by the loader (5) into the first housings (3) and precise positioning means in the first housings (3) of the pre-aligned products (4) are provided in cascade.

2. The inspection machine (1) according to the preceding claim, characterised in that between said fluid means and said precise positioning means, mechanical removal means are provided for removing excess products (4).

3. The inspection machine (1) according to any one of the preceding claims, characterised in that said fluid pre-alignment means comprise dispensing nozzles (18) of a calibrated air jet into the first housings (3).

4. The inspection machine (1) according to any one of claims 2 and 3, characterised in that said mechanical removal means for removing excess products (4) comprise at least one rotating brush arranged tangentially to the first roller (2).

5. The inspection machine (1) according to the preceding claim, characterised in that said brush rotates with a parallel axis of rotation to the axis of the first roller (2) and angular speed in the same direction as said first roller (2) to redirect the excess products (4) to the loading zone.

6. The inspection machine (1) according to any one of the preceding claims, characterised in that said precise positioning means comprise feeler organs arranged tangentially to the first roller (2).

7. The inspection machine (1) according to the preceding claim, characterised in that said feeler organ can oscillate with a parallel axis of oscillation to the axis of the first roller (2).

8. The inspection machine (1) according to any one of claims 1 to 5, characterised in that said precise positioning means are of the fluid type.

9. The inspection machine (1) according to any one of the preceding claims, characterised in that said slide (17) has guide grooves having a gradually increasing width and depth from an initial zero value.

10. The inspection machine (1) according to any one of the preceding claims, characterised in that said vibrating loader is positioned within a machine casing.

1 1. The inspection machine (1) according to any one of the preceding claims, characterised in that said first housings (3) have a different conformation from said second housings (8).

12. The inspection machine (1) according to the preceding claim, characterised in that said first housings (3) are conformed to house the products (4) completely or almost within them while the second positioning housings (8) are conformed to support the products (4) in a cantilever fashion.

13. The inspection machine (1) according to any one of the preceding claims, characterised in that at least said first checking device (1 1) is supported by a slide that is radially mobile with respect to the first roller (2) to allow the maintenance and replacement of the first roller (2).

14. The inspection machine (1) according to any one of the preceding claims, characterised in that at least the acquisition system provided in the first checking device comprises at least one linear video camera, and in that at least said first checking device has a first oblique lighting system for the transit zone (28) and a second incident lighting system for the transit zone (28).

15. An inspection method for inspecting the conformity of products (4) characterised in that it comprises, during the continuous and synchronised rotation of first and second opposite rollers (2, 7), the subsequent steps of channelling the products (4) into first housings (3) of the first roller (2), subjecting the products (4) thus channelled to a jet of air so as to pre-align them in the first housings (3), mechanically removing the products (4) from the first roller (2) that have not been channelled into the first housings (3), precisely positioning the pre-aligned products (4) in the first housings (3), illuminating a first transit zone (28) of the precisely positioned products (4) retained in the first housings (3) through a controlled depression and acquiring the image of the precisely positioned products (4) in transit from the first illuminated transit zone (28) for a first inspection, transferring the products (4) subjected to the first check into an overturned position in second housings (8) of the second roller (7), illuminating a second transit zone (29) of the products (4) retained in a precise position in the second housings (8) through a controlled depression and acquiring the image of the precisely positioned products (4) in transit from the second transit zone (28) illuminated for a second inspection, and selecting the conforming products (4).