FR2650990A1 - APPARATUS FOR ORIENTING PRODUCTS ON A TRANSPORT LINE, ESPECIALLY FOR AUTOMATIC MACHINES FOR PACKAGING, AND RELATED METHODS - Google Patents

Abstract

Apparatus for orienting products on a conveyor line, in particular for automatic packaging machines, and related methods. Products P, for example confectionery products such as chocolate bars, etc., possibly already contained in individual packages, advance with one of their main axes substantially perpendicular to the direction in which they are transported. The apparatus 5, 8 has a pair of configurations of conveyors, such as endless belts, which can be advanced at different speeds so as to obtain a condition in which the main axes of the products are exactly perpendicular to the line. direction of advance at the exit of the device 5, 8.

Description

- 1

  APPARATUS FOR ORIENTING PRODUCTS ON A LINE

  TRANSPORT, ESPECIALLY FOR MACHINERY

  AUTOMATIC PACKAGING AND METHODS THEREFOR

RELATE

  The present invention generally relates to devices for orienting products and more specifically to orient them with a main axis arranged perpendicular to the direction

transport.

  The invention has been studied paying particular attention to its possible use in the field of automatic packaging machines. In this field of use, products currently being packaged (eg confectionery products such as chocolate bars and the like, possibly already contained in individual packages) with one of their main axes are currently being promoted. , usually the major axis, arranged approximately perpendicular to the direction of advance. This situation is for example common in machines that form packages called "multi-pack", in which the individual products are advanced, inserted in respective packaging of the type "flow-pack / continuous packaging" or "form-fill- seal / form-fill-seal "to another packing machine for insertion, in groups containing a predetermined number of units, into similar larger packets. As the products advance, phenomena of different types, either random or pseudo-deterministic in nature, such as slippage on the conveyor belt, the product slightly held back because of a certain overflow outside, the longitudinal seal of the package, or the presence at one end of the package, a flap1 slightly larger than the flap at the opposite end, may result in the fact that an individual product does not advance with its main axis exactly perpendicular to the

direction of the advance.

  A situation of this type can have adverse effects, for example if a flow of products, more advanced on one side, must be transferred to a blade transporter that ensures their forced training. For example, if the blades have a certain transverse length, or if the blade conveyor engages each product through a plurality of stubs or drive teeth, an incorrectly disposed product may result in unwanted interference.

  with the drive devices.

  In addition, it must be taken into account that any misalignment with respect to the desired position may be further aggravated during the passage from one carrier to another moving forward at a speed

faster.

  Finally, it should be noted that although it is possible to compensate to a certain extent for a limited deviation from the position perpendicular to the direction of the drive (for example by the formation of an accumulation), a gap exceeding a certain value can become irreversible (for example if the products are arranged at around 45 in relation to the direction of advance), with the resulting risk that the product is "chewed" by the packaging machine and therefore the defilement or even the damage or blockage of the machine itself. The object of the present invention is to provide an apparatus which completely remedies the aforementioned problems and which ensures that, at its output, the products are arranged with their main axis in as perpendicular a direction as possible

to the direction of the advance.

  According to the present invention, this object is achieved by means of an apparatus which is characterized by the fact that it comprises: - at least two conveyor configurations for the products, which act in the direction of transport, - means of separate drive for the two conveyor configurations that can impart different speeds of movement to the two carrier configurations, - detecting movens to detect the orientation of the products and to generate at least one signal indicative of the deviation of the main axes of the products relative to the condition in which they are perpendicular to the direction of transport, and - control means which are sensitive to the signals, of which there is at least one, generated by the detector means and which may act on the means of training to vary the speed of movement of the configurations of

carrier to cancel the gap.

  Essentially, the present invention reuses the known principle that, by providing a carrier having two driving arrangements (eg endless conveyor belts), which can be advanced at different speeds, it is possible to vary the orientation of a product carried on the two training arrangements. For example, it is known to use this principle to rotate 90 products arranged "transversely" relative to the direction of the advance to arrange "longitudinally" with respect to the direction of advance. Another object of the invention is a method for orienting the products particularly fast and efficiently with the use of the apparatus of the type

specified above.

  This aspect of the present invention is based on the observation that once a certain product has been detected to advance with its main axis not exactly perpendicular to the direction of the drive, it will not It is not necessary to wait until the degree of this deviation from the desired position has been detected before

  start the necessary corrective action.

  Another object of the present invention is a method of regulating the apparatus of the type specified above to work preferably in accordance with the above.

with the process of the invention.

  The invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of part of an automatic packaging installation comprising two sets of apparatus according to the invention, different parts being omitted for

the clarity of the drawing.

  FIG. 2 is a schematic view comparable to a plan view, showing the structure of the apparatus according to the invention and the problem

that it aims to solve.

  FIG. 3 represents the structure of the control system of the apparatus according to the invention,

  as a block diagram.

  FIGS. 4 to 6 show schematically the operation of the apparatus according to

the invention, and -

  Fig. 7 is a schematic flow diagram that illustrates the operating criteria of the system whose block diagram is shown in FIG.

figure 3.

  In Figure 1, part of the conveyor system of an installation, not shown in its entirety, for the automatic packaging of products, is generally designated by

the reference 1.

  As an indication, it may be for example

  an installation to form so-called multi-packets

  pack of products such as chocolate bars

and the like.

  In these packages, each item is initially inserted into a respective package

  of the type "flow-pack / continuous packet" or "form-fill-

  seal / form-fill-seal ", essentially

  formed of an envelope of a sheet material having a longitudinal weld disposed under the product and which is closed by two welds

transverse end.

  For a general description of the criteria according to

  which packaging is made, which need not be repeated here, one can usefully refer for example to the United States Patent No.4

  761 937 under the name of the same applicant.

  Each individual package thus produced constitutes a product P which must be handled in the portion of the installation shown in FIG. 1. More precisely, the individual products P arrive on an input conveyor 2 (usually of the conveyor type). endless) arranged "across", that is to say with one of their main axes (usually the major axis) disposed substantially perpendicular to the direction of advance, to arrive at an output conveyor 3 ( consisting for example of a pair of endless belts driven by a motor), for subsequent transfer to another packaging machine (not visible in the drawings) in which the products P are inserted in groups in packages of the "flow-through" type. continuous pack / pack "or" form-fillseal / form, fill, seal "of larger size, so as to give the

  multiple packets known as "multi-packs".

  In the embodiment shown, the products P are transferred from the entrance belt 2 to the exit belt 3 because they advance under the effect of a cascade of several conveyors comprising: a first transfer conveyor 4 with a smoother, or alignment device, carpet S (known type), optionally adjustable, along one side, which pushes the products P as they arrive, to ensure that their ends are aligned longitudinally, - a first orientation conveyor 5 formed in accordance with the invention, - another transfer conveyor 6 (which must be considered as neutral with regard to the implementation of the invention) which creates an accumulation product dynamics P on itself, - a phasing conveyor 7 which, like the dosing conveyor 2 at the input, has an associated photocell 7a (the photocell analog of the dosing conveyor 2 is spotting e 2a) and has the function of causing the products P to move towards the output conveyor 3 with a predetermined phase relation with respect to a given reference, for example with respect to the blades or drive tabs of a a conveyor located further downstream (not visible in the drawing), and another orienting conveyor 8 which in all respects and for all purposes, the structure can be considered as identical to that of the

  orientation device 5 located further upstream.

  The phasing of the products P by the conveyor 7 (and possibly by the metering conveyor 2 at the inlet) by means of its photocells 7a (2a) is obtained in accordance with the known criteria that it It is not necessary to describe here in detail since they are not concerned with the understanding of the invention. From this point of view, one can usefully refer to the previous Italian patent No. 967 479 assigned to the same assignee and to the corresponding British patent

No. 1,412,679.

  As can be seen in Figure 1, all four conveyors 5 to 8 in cascade are preferably formed of two carpets arranged contiguous and oriented in the direction of transport of products P which are worn on the upper strands of carpets. The mutual spacing of the conveyor belts can be selectively adjusted to better accommodate the sizes (sizes) of the products to be handled. This is achieved by known means which

  do not require a specific description here.

  The criteria adopted for the assembly and training of the different carriers are

also known.

  Usually the drive is provided by the passage of the lower strands of conveyor belts or belts on respective rolls driven by a motor and arranged under the transport plane. In FIG. 1, the rolls in question are designated by the same reference mark as

  the carrier, followed by a letter-suffix.

  It should be noted that within the conveyor system shown in FIG. 1, there are auxiliary conveyor belts 9 to 12 which bridge the voids between the orienting conveyor 5 and the transfer conveyor 6, between the latter and the phasing transporter 7 and between the phasing transporter 7 and the other orientation transporter 8, as well as between this

  last and the output carrier 3.

  The auxiliary conveyors 9, 10, 11 and 12 are arranged at central positions between the pairs of carpets constituting the conveyors they bridge. The function of the auxiliary conveyors 9 to 12 is to ensure that the transfer of the products P between two cascading conveyors is as smooth and smooth as possible. Experiments carried out by the Applicant have in fact shown that, whatever the solution used to form the end of the conveyor end loops (rollers as in the embodiment shown in the drawing of Figure 1 or simple round shapes, known under the name of "feathers", possibly cooled to avoid overheating), the way in which the transfer takes place between cascading mats affects the preservation of the exact orientation of the products.

  P with respect to their direction of transport.

  Therefore, although there is no great need to provide auxiliary conveyors, for example, for the transfer between the input conveyor 2, the transfer conveyor 4 and between the latter and the first orientation conveyor 5 (that is, before the orientation of the P products has been achieved), it is definitely better to

downstream carriers.

  In practice, each auxiliary conveyor 9 to 12 consists of a narrow endless belt whose upper run increases gradually, coming from below, to come into the transfer region between two conveyors arranged in cascade. The products P being transferred are then supported in exactly horizontal arrangements, exactly in the region in which the carpet or carpets of the upstream conveyor descend below the transport plane and pass around the rollers or exit rollers, a region which the carpet or carpets of the downstream conveyor have not yet reached since they rise, coming from below, passing on the rollers or the input rollers of the respective conveyor. After having ensured the correct transfer of the products P onto the downstream conveyor, the conveyor run of the auxiliary conveyors 9 to 12 can gradually descend for

form his strand back.

  With regard to the drive mechanism, again referring to the embodiment shown in FIG. 1, the drive mechanism for the auxiliary conveyors 9 and 10 can be made slaved to the drive mechanism provided for the conveyor 6 of FIG. to ensure that the speeds

  in advance of the products exactly match.

  The auxiliary conveyor 11 can, if necessary, be made slaved to the drive mechanism provided for the phasing conveyor 7 while the auxiliary conveyor 12 can be made slaved to the drive mechanism

  provided for the output carrier 3.

  Naturally these selections are purely indicative and should not be considered as

an obligation.

  Fig. 2 shows an imaginary plan view of two mats or belts constituting the carrier.

  orientation 5 with their associated motors 5a 5b.

  The description that follows will refer almost

  exclusively to this carrier: it should be understood, however, that all that is stated applies in a manner virtually identical to the other carrier

Orientation 8 located downstream.

  As already indicated, the essential purpose of the conveyor 5 is to ensure that each product P brought to the conveyor entrance (with the direction of advance from left to right with reference to FIGS. 1 and 2 and also to FIGS. following 4 to 6) with one of its main axes, typically its long axis Xp, inclined with respect to the direction D of the transport, (that is to say making with this direction an angle other than 90 - the angle a of FIG. 2 being different from 0) has been returned to the correct orientation at the exit of the conveyor, that is to say so that its axis Xp is exactly perpendicular to the direction D of

the advance (angle a = 0).

  According to the invention, this goal is essentially reached: It - by detecting the error in the positioning of the product P (that is to say the amplitude and the direction of the angle a) and - by modifying the speed motors Sa, 5b so as to correct the error; in practice, it detects which end of the product P is more advanced than the other, and how much, and reduces the speed of advance of the carpet on which is located the most advanced end and accelerates the other carpet , on which is located the least advanced end, until the positioning error is canceled. To detect the error in the positioning of each product P, detectors are used, preferably consisting of two photocells 13a, 13b (14a, 14b in the case

orientation carrier 8).

  As in the case of photoelectric cells 2a and 7a, these products are widely available commercially and are for example manufactured by

  the company SICK (West Germany).

  Preferably, the two photoelectric cells 13a, 13b (which naturally can be replaced by functionally equivalent detectors, optical or non-optical), are of the type which operates by reflection. Consequently, according to widely known criteria, they have a radiation source which sends a light beam (this term also includes radiation outside the visible range, for example infrared radiation) towards a reflecting screen 14 ( In the case of the transversely extending orientation conveyor 8), as a bridge between the two conveyor belts 5,

  immediately below their carrier strands.

  The screen 14 can thus reflect the radiation in the direction of a light-sensitive element (for example a photodiode) which is incorporated in the same enclosure as that containing the light source and which is disposed above the plane on which

P products are transported.

  When there are no products P in correspondence with the photocells 13a, 13b, all of the radiation is reflected by the screen 14 and recovered by the light-sensitive element. If a product P is interposed between the enclosure of the photocells and the reflecting screen 14, however, the propagation path of the radiation beam is interrupted and the corresponding photocell transmits

therefore a detection signal.

  Photocells 13a, 13b can generally be regarded as acting at the respective detection points 16a, 16b which are aligned transversely to the direction D of the product transport so as to define an imaginary barrier B which constitutes a reference for the P. In the context of the application in question, it is considered that it is preferable to choose photocells (or optical detectors).

  similar) which operate by transmission.

  Of course, it is also possible to use other types of detectors, such as proximity detectors (either optical or non-optical) which are capable of detecting the passage of the products P on the two conveyor belts 5 without a screen

reflecting is necessary.

  This type of solution has the advantage that it is possible to detect the passage of the two ends of each product P at positions which are approximately in the center of the conveyor belts, that is to say at positions approximately aligned with the points T1, T2, (it would be more correct to speak of regions given the difficulty of controlling and modeling the process) around which the ends of the product P rotate relative to the conveyor belt during the orientation movement that I ' we will describe more

in detail below.

  However, the use of optical sensors operating by transmission is much better in terms of reliability and accuracy of the detection. The operation of proximity sensors is, in fact, largely affected by the surface characteristics - as well as by the shape and size, of course - of the products of which

the passage is detected.

  In an application such as the one in question, in general, it is very difficult to predict the dimensional characteristics, and in particular the surface characteristics of the products (as we have seen, the products can either be coated, either already coated with respective packages which may be of a material which is more or less reflective, transparent,

colored, etc.).

  As will be seen better from the following, on the other hand, the fact that the optical detectors 13a, 13b are placed in positions which, of necessity, are not aligned with the carpets

  carriers 5 (usually immediately

  beyond the mats on their inner side) results in a detection error which must be taken into account according to the criteria which will be described

in more detail below.

  Figure 3 shows the general structure of the control system for the device according to the invention. The system can be formed with the use of a microprocessor (modules 17, 22, 23, 24 and 25) which receives the detection signals generated by the photocells 13a, 13b via a gate input 17 and provides, on the output lines 18a, 18b, respective feedback signals to the units 19a, 19b, which activate the motors 5a, 5b which drive the conveyor belts. A keyboard, or similar data input unit 20 is also connected to the input range 17 of the microprocessor system and allows the data to be entered into the system relating, for example, to the different dimensions of the processed products, in particular with regard to the factor of

  correction that will be discussed later.

  Two position detectors, typically encoders or resolvers, associated with the motors a, 5b are designated 21a and 21b and can supply the respective counters 22a, 22b with signals of the on / off type indicative of the positions reached by the motors 5a, 5b, and therefore by the carpets that they train, according to a system

general reaction control.

  For the sake of simplicity, reference will be made hereinafter

  under the carpet moved by the motor 5a (that is to say on the left compared to the direction of advance of the products) as the "first carpet" while the other carpet, moved by the engine 5b, will be

designated "the second carpet".

  The encoder 21a and the counter 22a will therefore simply be designated, the "first encoder" and the "first counter", while the encoder 21b and the counter 22b will be designated the "second encoder".

and the "second counter".

  The two counters 22, 22b act under the control of the central processing unit CPU, denoted by the reference 23, of the microprocessor system which, in particular, can reset the counters 22a and 22b selectively. A memory 24 is also connected to the central processing unit CPU 23 and can be entered, for example by the keyboard 20, correction data and dimensions, of which

the job will be described below.

  The data and instruction bus of the control system is generally designated by the mark 25 and is connected to the input of the digital-to-analog converter 26 whose output line 27 is connected to the sign change inputs and non-change of sign, respectively, of the two amplifiers 28a, 28b, the gains of which can be varied selectively. The output of each amplifier 2Sa, 28b is connected to one of the inputs of a respective multiplier 29a, 29b, the other input receives, on a line 30, a signal indicative of the base speed or reference speed of movement of the conveyor 5, regardless of the fluctuations imparted at the speeds of the motors Sa, b to orient the products P. In practice, this speed defines the overall speed of advance of the products P on the conveyor 5. As will be seen below, the function of the adjustment system that controls the orientation conveyor 5 is to selectively increase or decrease the speed of each of the conveyor belts relative to the base speed of the conveyor belt.

  to obtain the desired orientation correction.

  The output signal of each of the multipliers 29a, 29b is sent to the input of the respective adders 30a, 30b which also receives the signal giving the base speed which is on the line 30. The output lines of the adders 30a, 30b constitute the lines of

  driving engines 18a and 18b mentioned above.

  It will be appreciated that the function of the multipliers 29a and 29b is essentially to apply a corrective increase or decrease (by means of the adders 30a, 30b) to the basic speed signal that is present on the line 30 and which is proportional to the value

basic speed.

  In other words, this means that in practice the corrective signal present on the line 27 only depends on the angular deviation of the product P (angle i) with respect to the desired position and that it is automatically applied to the overall speed of carrier 5 motion as a result of the multiplication performed in the multipliers

29a, 29b.

  The gain of the amplifiers 28a, 28b defines the speed with which the corrective action takes place, that is to say the intensity of the corrective signals which are applied to the actuators 19a, 19b for a given value of the error signal. present

on line 27.

  The opposite signals of the gains of the amplifiers 28a, 28b relate to the sense of the deviations detected.

  products P with respect to the desired orientation.

  In the embodiment of FIG. 3 (taken in conjunction with FIG. 2), the error signal is assumed to be positive when the left end of the product P (in the direction of advance of the product) is

  more in advance than the right end.

  In this case, to correct the error, slow down the left belt (motor 5a) and accelerate

the right carpet (motor 5b).

  For this reason, the gain of the amplifier 28a which controls the motor 5a has been shown with a minus sign and a plus sign has been assigned to the gain of the amplifier 28b which controls the motor b. It can be seen immediately that, in the case of the opposite orientation (the left end behind the right end), with the resulting generation of a negative error signal, on the line 27, the necessary reaction is the acceleration of the left-hand carpet and deceleration

the right carpet.

  In a first possible embodiment of the invention, the error signal to be sent to the digital-to-analog converter 26 for subsequent transmission on the line 27 could be given by the duration of the interval that elapses between: - the instant to which the product P reaches the detection point 16a of the photocell 13a and obscures it, and - the instant at which the opposite end of the product P reaches the detection point 16b of the other cell

photoelectric 13b.

  If a product is perfectly aligned (angle e = 0 - that is to say in an ideal situation) these moments coincide and there is no error signal or corrective reaction sent to the engines Sa and 5b which continue to move at the same speed

  identified by the signal present on line 30.

  On the other hand, the greater the interval between the two transit instants in correspondence with the photocells 13a and 13b, the greater the deviation of the product P from the desired perpendicular condition: therefore more large is the reaction signal that must be applied to the motors 5a and 5b to compensate for this difference. The type of solution described (the fact of determining the reaction signal as a function of the interval between the instants at which the two ends of the product reach the detection points of the two photocells has the disadvantage

  that - to correct the positional error - one does not

  do not read the time interval between

the two moments in question.

  The presently preferred embodiment of the present invention, on the other hand, provides for the use of this

  time interval for correction purposes.

  From this point of view, the present invention is based on the observation that, as soon as the end of the most advanced product P (that is to say the direction of deviation from the desired perpendicular position ) has been identified, it is already possible to intervene to correct at least

partially the gap.

  Consequently, referring to the situation shown in FIG. 2, as soon as the front edge of the product P reaches the detection point 16a of the photoelectric cell 13a, it is immediately known that the correction must be made in the direction to slow down the movement of the carpet driven by the engine and simultaneously to increase the speed of the carpet

driven by the 5b engine.

  This procedure also has the advantage of making it possible to reduce the positioning error even before the actual value of this error has been reached.

been detected.

  We will immediately appreciate this fact by referring to the sequence illustrated in the figures

4, 5 and 6.

  The three figures in question are divided into two parts. The upper part, marked a), represents the position of the leading edge (ie the most advanced edge) of the product P by

  to the detection point 16a of the photocell

  electric 13a. The lower part marked b), on the other hand, represents the position of the same edge by

  compared to the detection point 16b of the photocell

electric 13b.

  As soon as the front edge P reaches the detection point of the photocell 13a (FIG. 4), the system of the invention intervenes to slow down

  the engine 5a and accelerate the engine 5b.

  The overall effect is to transmit a leftward or counterclockwise rotation to the product P (referring to the position shown in FIG. 2) and thus to bring its main axis Xp towards the position perpendicular to the direction D of the advance so as to reduce the positioning error

(Figure 5).

  This corrective action continues until - edge P reaches section point 16b

  of the photocell 13b (Figure 6).

  At this point, the remaining positioning error is certainly lower than the original positioning error (i.e. the error at the entry of the orientation conveyor 5). In other words, the positioning error that remains and remains to be corrected on the remaining portion of the path followed by the product P on the conveyor belts 5 is certainly

less than the original error.

  Applicant has found that it is preferable that photocells 13a, 13b be positioned approximately at the center of the total length of conveyor 5 (remember that the distance between the two mats can be selectively adjustable depending on the different sizes of the handled products), taking into account that the carrier conveyor belts are approximately 10-20 cm long in most

applications envisaged.

  In more general terms, the portion of the conveyor 5 which is upstream of the imaginary barrier B defined by the photocells 13a, 13b must be of a length to ensure that, at least under the conditions of routine use - the product P is fully loaded on the conveyor 5 before reaching barrier B. The length of the downstream portion must allow the corrective action to be effected efficiently without it being necessary to impart to the belts relative velocities relative to to the product P that might drag the product so that it becomes

difficult to control.

  With regard to the initial step of correcting the positioning error (performed during the time interval that elapses between the times at which the photocells 13a, 13b are covered by the front edge of the product P), it has been found that the correction is more effective if the reaction signal sent by line 26 increases as time passes, 2 <5o99Q starting from the instant at which the first photocell electrical connection is covered by the front edge of the product P. In practice, this means that the preliminary corrective action is more effective than the distance of the product from the position

ideal is bigger.

  The flowchart of FIG. 7 shows how this result can be obtained, with a circuit layout such as that shown in FIG.

3.

  Starting from a step, generally designated by the mark 100, for which the device is activated, as each product passes on the orientation conveyor 5 (the speed of the conveyor and that of the conveyors placed in position). upstream are regulated so as to ensure that only one product P comes on both the conveyor 5), in a first step 101, the system (i.e. in practice the central processing unit CPU 23) detects the

  recovery of one of the photo cells

  13a, 13b by the front edge of the product P. In a subsequent decision step 102, the

  system identifies which of the two photocells

  electric was covered. The direction of the deviation of the product P from the desired perpendicular condition is thus identified (positive or negative angle e). The direction of the gap is recorded in the system by positioning indicators at two different logical levels

  which identify the direction-of the deviation (not 103, 104).

  For example, referring to the conventions adopted in FIGS. 2 and 3, the deviation of the product P represented on the dash-punctuated line in FIG. 2 (the left end more advanced than the right-hand end) can be considered a positive deviation (indicator positioned at logic level "1"), while a negative direction is attributed to a deviation in the opposite direction (indicator positioned at logic level "0"). When the sign of the deviation has been identified, the unit 23 (step 105) starts the counters (22a, 22b) which have been previously reset (not

114 - see below).

  The counting signal, which is indicative of the feedrate of the product P (in the specific case it is the counting signal of the first counter 22a) serves, taking into account the sign expressed by the indicator at steps 103, 104, generating a corrective signal which is sent to the converter 26 (step 106). The signal in question gradually increases in intensity as the time elapses, starting from the moment when the product P has covered the first photocell. It is thus possible to generate on line 27 a corrective signal in accordance with the criteria seen above, the intensity of the signal increasing all the more as the deviation from the desired perpendicular condition is more pronounced. This first corrective step continues until the other photocell is also covered by the product P. In a control step 1060, on the other hand, the system verifies that the count (for example that of the second counter 22b ) did not exceed a maximum that would indicate that the product was so poorly positioned (in longitudinal position) that it did not cover the other photocell. In this case, the system immediately goes to step 114 and becomes ready for another

cycle with another product.

  In the current case, when the other photocell is also covered by the product (step 107), some correction of the positioning error has already been made. At this point, the second counter (22b) is reset (step 108) and the difference between the count of the first counter 22a and that of the second counter, reset, 22b, is used as an indication of the relative deviation of the ends of the product P The difference between the accounts being evaluated, a signal is obtained which is indicative of the residual positioning error. This signal can be used as a feedback signal to send to the converter

  Digital / Analogue 26 and Line 27.

  Since the positions 16a, 16b at which the photoelectric cells 13b, 13b detect the passage of the front edge of the product P are offset relative to the conveyor belts 5, in practice the corrective signal obtained as the difference between the counts of the two counters 22a 22b tends to to be an underestimated value of the actual deviation (in the direction of advance of the products P) between the points - or rather the regions T1, T2 around which then occurs the rotational movement which operates

positioning correction.

  To obtain a completely satisfactory correction, it is therefore necessary to add a correction factor (KSl), which takes into account the dimension and the geometric characteristics of the product P, to the correction signal obtained as

  difference between the counts of the counters 22a, 22b.

  This correction factor is read by the CPU 23 as a result of a reading in the memory 24 at the next step 110 at which the system arrives in case of a positive result obtained at the comparison step 111 in which the system detects whether,

2650-990

  yes or no, the overall speed of advance of the device (in practice the base speed on line 30) is below a certain maximum threshold value. We will describe more completely below

  the reasons that lead to this comparison.

  At step 112, the correction factor determined by the CPU unit at step 110 is added to the feedback signal obtained at step 109 so that it can be used later, at step 113, to generate the feedback signal that is actually sent. to the digital-to-analog converter 26 to correct the error. After completion of step 113 and a step 114 in which the counters are reset,

  the system is ready to repeat the cycle (step 115).

  If, in step 111, the system detects that the overall speed of advance of the system is greater than a predetermined threshold, the correction factor is not

applied.

  The threshold speed used for comparison at step 111 is chosen to be less than, or equal to, the speed at which the reaction on conveyor belts 5, taking into account correction factor KS1, could be too violent and cause uncontrolled sliding of the product

P on conveyor belts 5.

  This threshold speed can easily be determined experimentally according to the characteristics of the installation and the

  characteristics of the products P to handle.

  If this speed is reached (i.e., if a negative result is obtained at the comparison in step 111), the correction factor is not applied (the system goes directly to step 113). This means that, at least in some cases, the correction of the positions (orientations) of the products P carried out by the carrier is incomplete in the sense that the angle t can, at least in certain cases, still remain slightly

  different from the desired value of 0.

  For this reason, it is preferable (as in the embodiment to which FIG. 1 relates) to provide two cascaded conveyors 5, 8 so that the downstream orientation conveyor (ie ie the carrier 8 in the embodiment shown) acts as final corrector for the slight error

  residual positioning that can leave.

  subsist the upstream referral carrier.

  The two orientation conveyors 5, 8 could be arranged directly in cascade, preferably with an auxiliary conveyor such as one of the carriers 9 to 12 between the two, so as to ensure that the products P are transferred regularly and without and the alignment already achieved by the upstream referral

is not disturbed.

  However, intermediate conveyors may be interposed between the two orientation conveyors 5, 8 either with a dynamic accumulation function (as in the case of the separating conveyor -6 of the embodiment of FIG. 1), or as delivery conveyors. in phase, as the carrier 7. It should be noted that carriers of the latter type usually detect the passage of the product P in the central position (see the position of the photocell 7a of Figure 1) and that an error residual positioning therefore does not affect

  appreciable way the result of the phasing.

  It is not easy to determine a priori the

  value of correction factor KS1 (steps 110 and 112).

  This factor is connected by a coefficient of proportionality to the value (a) of the deviation of the product from the position perpendicular to the direction D of the advance. This appears clearly from simple geometrical considerations: the more the product is inclined relative to the desired perpendicular position, the more important is the distance between the detection points 16a, 16b of the photocells and the points T1, T2 around which is the orientation of the product. The coefficient of proportionality in question is affected by various factors such as the size of the product, both as regards its length (and therefore the positions of the ends with respect to conveyor belts) and as regards its width (which affects the ratio of the rotational sliding of the product P with respect to the belts), or by the characteristics of the relative sliding of the product or its packaging and the material constituting the belts. Given this situation, it is not generally possible, at least with the applicant's current level of experience, to provide an exact model and therefore an algorithm to determine the value of the

correction factor.

  However, this factor can be easily determined experimentally and, more specifically, the coefficient mentioned, because it is independent of the speed of movement of

P products on the carrier 5.

  This makes it possible to implement a simple procedure for adjusting the device 1 in the following terms. A sample of the products P which are to be handled is placed at the entrance of the conveyor 5, in a condition of misalignment with respect to

  the perpendicular to the direction D of the transport.

  The device is then started at low speed (that is to say under conditions that allow the operator to visually follow the misalignment correction at the two steps described above) and thus identifies, if necessary by successive approximations. , the corresponding correction factor (and therefore the coefficient of its proportionality to the deviation) to be applied to obtain

  the desired orientation at the exit.

  It is confirmed and permanently loaded in the memory 24, for example by means of the keyboard 20, the coefficient thus identified. During the operation of the device, the CPU 23 CPU will be able, from this, to calculate the correction factor KS1 to apply

  in step 112 by multiplying it by the detected difference.

  The same adjustment operation can be performed for products P of different characteristics (for example of different dimensions), so that a set of coefficients is then entered in the memory 24 to enable the system to calculate the correction factor. to apply to the type of product P that is being handled at a given moment, during the operation of the

  device, to obtain the desired correction.

Claims (24)

  1. Apparatus for conveying products (P) and for orienting them with a main axis (Xp) arranged perpendicular to the direction (D) of the transport, characterized in that it comprises: - at least two conveyor configurations (5 ) for the products (P), which act in the direction (D) of the transport, - separate drive means (5a, 5b) for the two conveyor configurations (5) which can impart different speeds of movement to the two configurations of conveyor (5), - detecting means (13a, 13b) for detecting the orientation (t) of the products and for generating at least one signal (27) indicative of the deviation of the main axes (Xp) of the products ( P) with respect to the condition in which they are perpendicular to the direction (D) of the transport, and - control means (17 to 30) which are sensitive to the signals (27), of which there is at least one, generated by the detector means (13a, 13b) and which can act (1 9a, 19b) on the drive means (5a, 5b) for varying the speed of movement of the conveyor configurations (5) to cancel the gap.   2. Apparatus according to claim 1, characterized in that the conveyor configurations (5) are generally endless configurations. Apparatus according to Claim 2, characterized in that conveyor configurations are in the form of motor-driven belts (5) (5a, 5b) with upper strands.   for the transport of the products (P).   4. Apparatus according to any one of   Claims 1 to 3, characterized in that   the detector means consist of optical detectors (13a, 13b).   5. Apparatus according to claim 1 or claim 4, characterized in that the detector means (13a, 13b) consist of detectors which operate by emission of beams of radiation through the path, on the carrier, of the products ( P), whereby the passage of the products (P) in correspondence with the detector means (13a, 13b) interrupts the beams of radiation.   6. Apparatus according to any one of   claims 1, 4 or 5, characterized in that   that the detector means comprises a pair of detectors (13a, 13b) aligned transversely to the direction (D) of the transport, whereby the time interval between the moments at which the products (P) pass in correspondence with the pairs of detectors (13a, 13b) is indicative of the gap.   7. Apparatus according to claim 6, characterized in that the detectors (13a, 13b) are arranged generally out of alignment with the carrier configurations (5).   8. Apparatus according to any one of   preceding claims, characterized in that   the control means (18 to 30) comprise, for controlling the drive means (5a, 5b) associated with each conveyor configuration (5): - amplifier means (28a, 28b) to which the signals are supplied ( 27), of which there is at least one, indicative of the deviation, the gain of each amplifier means (28a, 28b) having the opposite sign of that of the amplifier means (28b, 28a) associated with the means driving means (5b, 5a) of the other conveyor configuration (5), multiplier means (29a, 29b) which act on the output signal of the amplifier means (28a, 28b) and on a signal (30a). ) indicative of the overall transport speed of the products (P), and the adder means (30a, 30b) to which are supplied the output signal of the multiplier means (29a, 29b) and the signal indicative of the overall speed of transporting products (P), the output signal of the adder means s (30a, 30b) driving the means drive (5a, 5b).   9. Apparatus according to claim 6, characterized in that the control means (17 to 30) comprise counter means (22a) which are activated when the products (P) pass in correspondence with that of the detectors (13a, 13b). ) that the products (P) meet first, and in that the counter signal of the counter means (22a) is used as a signal indicative of the difference (27), at least until the products ( P) pass in correspondence with the other of the detectors (13b, 13a) which is the second meet the products (P).   10. Apparatus according to claim 9, characterized in that the control means (18 to 30) comprise other counter means (22b) which are reset when the products (P) pass in correspondence with that of the detectors (13b). , 13a) which is the second that the products (P) achieve, in that the difference between the counting signal of the counter means 2650990-   (22a) and the count signal of the other, reset, counter means (22) is used to generate the deviation signal after the products (P) are matched with that of the two detectors (13b, 13a) who is the second that the products (P) meet.   11. Apparatus according to claim 7 and claim 10, characterized in that it also comprises means (23, 24) for applying predetermined correction factors to the deviation signal, the correction factors being   preferably proportional to the deviation signal.   12. Apparatus according to claim 11, characterized in that the control means (17 to 30) further comprise a threshold function (111) which is sensitive to the overall speed of transport of the products (P) and which can prevent applying the predetermined correction factors to the deviation signal when the overall transport speed of the products (P) exceeds a predetermined threshold value. Apparatus according to claim 9 or claim 10, characterized in that the counter means (22a, 22b) are driven by respective sensor elements (2Ia, 22b) for detecting the movement of the drive means (5a). , 5b) so that the control means (17 to 30) operate according to a system general reaction.   14. Apparatus according to claim 13, characterized in that the sensor elements (21a, 21b) are constituted by encoders or resolvers.   15. Apparatus according to claims 1 to 14,   arranged in cascade with at least one similar device (8) inside a line (1) for transporting products (P).   16. Apparatus according to claim 15, characterized in that at least one intermediate conveyor (7) is interposed between the two similar sets of devices (5, 8) in cascade and has for   function of phasing the products (P).   17. Apparatus according to claim 15 or claim 16, characterized in that at least one conveyor (6) is interposed between the two similar sets of apparatuses (5, 8), in cascade, and   Its function is to accumulate the products (P).   18. Apparatus according to any one of   claims 15 to 17, characterized in that   auxiliary conveyors (9 to 12) are inserted into the gap between the sets of conveyor devices (5 to 8) arranged in cascade, to ensure that the products (P) are transferred substantially without their transport movement be disturbed.   19. A method of controlling the operation of the apparatus according to claim 1, characterized in that it comprises the steps of: providing detector means (13a, 13b) so as to form at least two zones (16a, 16b) ) in which the passage of the products (P) is detected, each close to one or the other of the conveyor configurations (5) respectively, - detecting the passage of the products (P) in correspondence with that of the two zones of detection (16a, 16b) that the products (P) first encounter, so as to identify the direction of the deviation, - act (17 to 30) on the drive means (5a, 5b) in a first step deviation correction means for creating a difference in the speeds of the driving means (5a, 5b) so as to vary the speeds of movement of the conveyor configurations (5) in the direction of reducing the deviation, - detect the passage of products (P) in correspondence with that of the two zo detection range (16b; 16a) which is the second encountered by the products- (P), the time interval that elapses between the moments at which the products (P) pass in correspondence with the two detection zones (16a). , 16b) being indicative of the residual difference to be corrected, and - acting (17 to 30) on the drive means (5a, 5b), in a second pitch correction step, to create a difference in the speed of movement of conveyor configurations (5) to cancel the residual gap.   20. A method according to claim 19, characterized in that it comprises, during the first pitch-correction step, the step of progressively increasing the difference between the speeds of movement of the conveyor configurations ( 5), starting at the moment of passage of the products (P) in correspondence with that of the two detection zones (16a, 16b) that the   products (P) meet in the first place.   21. The method of claim 19 or claim 20, for controlling the operation of the apparatus according to claim 7, characterized in that it comprises the step of applying to the deviation signal predetermined correction factors which preferably are proportional to the deviation signal.   22. The method according to claim 21, further comprising the step of detecting the overall transport speed of the products (P) and the step of preventing the application of the predetermined correction factors to deviation signal when the overall transport speed of the products (P) exceeds a predetermined threshold value. 23. A method for determining the correction factors referred to in claim 11 or claim 21, the correction factors being proportional to the deviation of a respective coefficient, characterized in that it comprises the steps of to: - a) placing a product (P) at the inlet of the apparatus (1) with a deviation () from the perpendicular condition, - b) advancing the apparatus at a generally low speed so as to enable the detection of the effectiveness of the correction of the difference obtained by the device (5).   - c) if the correction is effective, identify the correction factor applied and the difference value (t), - d) calculate (23) the respective coefficient, and   e) memorizing the coefficient thus calculated.   24. The method as claimed in claim 23, characterized in that steps a) to e) are repeated for products (P) of different characteristics and that the coefficients are memorized. calculated.