(19)
(11) EP 0 769 365 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Mention of the grant of the patent:
09.01.2002 Bulletin 2002/02

(21) Application number: 96202864.3

(22) Date of filing: 15.10.1996
(51) International Patent Classification (IPC)7: B31B 1/06, B31B 1/74, B31B 5/80, B65H 1/24

(54)

Blank feeder

Zufuhrvorrichtung von Zuschnitten

Dispositif d'alimentation de flans


(84) Designated Contracting States:
CH DE DK FR GB LI NL SE

(30) Priority: 18.10.1995 JP 26980895

(43) Date of publication of application:
23.04.1997 Bulletin 1997/17

(73) Proprietor: Shikoku Kakoki Co., Ltd.
Itano-gun Tokushima (JP)

(72) Inventors:
  • Kume, Satoshi, Shikoku Kakoki Co., Ltd. of 10-1
    Itano-gun, Tokushima (JP)
  • Hata, Yoshinori, Shikoku Kakoki Co., Ltd. of 10-1
    Itano-gun, Tokushima (JP)
  • Ueda, Michio, Shikoku Kakoki Co., Ltd. of 10-1
    Itano-gun, Tokushima (JP)

(74) Representative: Vollebregt, Cornelis Jacobus, Ir. et al
Algemeen Octrooibureau World Trade Center P.O. Box 645
5600 AP Eindhoven
5600 AP Eindhoven (NL)


(56) References cited: : 
EP-A- 0 034 797
US-A- 4 596 545
EP-A- 0 574 079
   
       
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The invention relates to a blank feeder comprising:

    a magazine for accommodating a plurality of blanks as arranged from a lower end to an upper end thereof in the form of a stack so that the blanks are movable inside the magazine under gravity towards an outlet at the lower end of the magazine,

    a conveyor forming a transport path for supporting the lower ends of a plurality of blanks as arranged closely face-to-face on the conveyor from a terminal end of the path near said magazine to a starting end thereof the arrangement being so that the path of movement of the blanks inside the magazine makes an angle of 105 to 165 deg. with the transport path of the conveyor, and the blanks on the conveyor can not move on the conveyor under gravity towards the terminal end of the path where a blank on the conveyor is supported at its upper end by the uppermost blank within the magazine,

    a sensor for producing a non-detection signal when the quantity of blanks remaining within the magazine has decreased to not greater than a predetermined value and producing a detection signal upon the quantity of remaining blanks exceeding the predetermined value,

    drive means for driving the conveyor in response to the non-detection signal of the sensor and discontinuing the operation of the conveyor in response to the detection signal.



    [0002] Such a blank feeder could be derived from US-A-4596545. Said known blank feeder is used for feeding blanks having the same height whereby the feeder has been provided with a sensor of the contact type.

    [0003] It is an aim of the invention to obtain a feeder adapted for feeding blanks having different heights.

    [0004] According the invention this can be accomplished in that the feeder is adapted to feed various kinds of blanks in different height, whereby the sensor comprises the same number of non-contact type photoelectric tubes as the kind of blanks said photoelectric tubes being disposed at different levels in accordance with the heigth of various blanks so as to produce a non-detection signal or detection signal by detecting the displacement of an upper end of the blank at the terminal end of the transport path due to an alteration in the angle of the same blank in accordance with a variation in the quantity of blanks remaining within the magazine.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0005] 

    Fig. 1 is a side elevation of a blank feeder embodying the invention;

    FIG. 2 is a perspective view of the same;

    FIG. 3 is a sectional view of a magazine of the feeder;

    FIG. 4 is a view in vertical cross section of a rear end portion of a conveyor of the feeder;

    FIG. 5 is a view in vertical cross section of a lengthwise intermediate portion of the conveyor;

    FIG. 6 includes diagrams for illustrating a blank feeding operation; and

    FIG. 7 includes diagrams each showing the operation of feeding blanks of different height.



    [0006] In the following description, the terms "front" and "rear" are to be used based on FIG. 1; the lefthand side of the drawing will be referred to as "front," and the opposite side as "rear." The terms "right" and "left" will be used for the feeder as it is seen from behind toward the front.

    [0007] With reference to FIG. 1, one of radial mandrels 11 of an intermittently drivable rotary body for forming containers is halted at a blank feed station, as inclined obliquely rearwardly downward at an angle of 45 deg with a horizontal

    [0008] The illustrated blank feeder is adapted to selectively feed to the mandrel 11 three kinds of blanks B which are different in height, i.e., tall containers, medium-sized containers and low containers. The feeder comprises a magazine 13 disposed in the rear of the mandrel 11 and having a lower-end outlet 12 facing obliquely forwardly downward for accommodating a plurality of flat blanks B in the form of a stack, a conveyor 14 having a forwardly extending horizontal path of transport for transporting the blanks B to be accommodated in the magazine 13, with the front end of the transport path opposed to the interior of the magazine 13, a picker 15 so disposed as to be movable toward or away from the outlet 12 for taking out blanks B from the outlet 12 one by one while unfolding each blank B into a square or rectangular tube, a pair of guide rails 16 extending from a position opposed to the outlet 12 to a position close to the outer end of the mandrel 11 along the axial extension line of the mandrel 11 and inclined at the same angle as the mandrel 11 for guiding the blank B as unfolded into a square or rectangular tube to the mandrel 11, and a loader 17 reciprocatingly movable along the guide rails 16 for pushing the blank B to the mandrel 11 and fitting the blank around the mandrel 11 as the blank B is guided by the rails 16.

    [0009] With reference to FIGS, 2 and 3, the magazine 13 comprises a rectangular frame 21 elongated along the axial extension line, surrounding the outlet 12 and inclined at the same angle as the mandrel 11, i.e., at 45 deg when seen from one side. The frame 21 comprises an upper frame member 22, right and left side frame members 25,24 and a movable member 26 movable inside the frame 21 longitudinally thereof. The lower frame member 23 is provided on its lower face with a blank opening fixed nail 31 projecting inwardly of the frame 21 and has two lower guide rods 32 extending upright from its upper face. The left frame member 24 is provided on the lower face thereof with four arcuate guide plates 33 for guiding the left edge of the blank B when the blank is unfolded, and has three guide rods 34 extending upright from the upper face thereof. The right frame member 25 is provided on the lower face thereof with a blank support bar 35 having one end projecting inwardly of the frame 21, and has three right guide rods 36 extending upright from the upper face thereof. The movable member 26 has a blank opening movable nail 37 on its lower face, an upper guide rod 38 on its upper face and a pusher arm 39 on a side face thereof.

    [0010] FIG. 3 shows, as accommodated in the magazine 13, a tall blank B1 in dot-and-dash lines, a medium-sized blank B2 in a two-dot-and-dash line, and a low blank B3 in a three-dot-and-dash line. The position of the movable member 26 is adjustable in accordance with the height of the blanks B1, B2, B3.

    [0011] A photoelectric tube 41 for detecting the tall blank is attached to the upper end of the right guide rod 36 positioned first from above, and a photoelectric tube 42 for detecting the medium-sized blank and a photoelectric tube 43 for detecting the low blank are attached to the upper end of the right guide rod 36 positioned second.

    [0012] The conveyor 14 comprises a frame 53 supported by the upper ends of front and rear posts 51, 52, a horizontal front driven shaft 54 and rear drive shaft 55 provided respectively at the front and rear ends of the frame 53 and extending transversely of the feeder, a pair of right and left front pulleys 56 fixed to the driven shaft 54, a pair of right and left rear pulleys 57 fixed to the drive shaft 55, a pair of right and left toothed belts 58 each reeved around the front pulley 56 and the rear pulley 57 at one of the right and left sides, right and left side guide plates 59 arranged respectively at the right and left sides of the pair of endless belts 58 externally thereof, and a pair of right and left arcuate bridge plates 61 extending from positions laterally outside the pair of front pulleys 56 to the upper ends of the respective lower guide rods 32.

    [0013] A photoelectric tube 62 is disposed at the right side of front end of the right belt 58 for detection to discontinue picking, and a blank supply alarm photoelectric tube 63 is disposed to the rear of the tube 62. A stopper 64 in the form of an L-shaped plate for preventing blanks from falling down is provided across the upper path of travel of the belts 58.

    [0014] With reference to FIG. 4, a driven pulley 71 is fixed to the right end of the drive shaft 55. A motor 72 installed below the drive shaft 55 has an output shaft fixedly carrying a drive pulley 73. A belt 74 is reeved around the driven pulley 71 and the drive pulley 73.

    [0015] FIG. 5 shows that each of the belts 58 bears on a slip plate 81 when in the upper path of travel.

    [0016] The blanks B within the magazine 13 move at an angle of 45 deg with respect to a horizontal, in other words, at an angle of 135 deg with the path of transport of the conveyor 14.

    [0017] Tall blanks B1 are fed to the mandrel by the operation to be described next with reference to FIG. 6.

    [0018] FIG. 6, diagram (a) shows that blanks B1 in a quantity slightly less than when filling up the magazine 13 are accommodated as stacked up within the magazine. The uppermost blank B1 is positioned at a level lower than the photoelectric tube 41 for detecting tall blanks. On the other hand, supported on the conveyor 14 are the lower ends of blanks B1 as arranged closely face-to-face, the stopper 64 bears on the lower end of the rearmost blank B1, and the upper end of the foremost blank B1 is supported by the uppermost blank B1 in the magazine 13. In this state, the tube 41 for detecting the tall blank B1 produces a non-detection signal, whereupon the conveyor 14 is driven in response to the non-detection signal. When driven, the conveyor 14 delivers the blanks B1 thereon successively from the foremost position. This raises the level of the uppermost blank B1 within the magazine 13. With this movement, the inclination of blanks B1 with respect to a horizontal gradually increases.

    [0019] When the uppermost blank B1 inside the magazine 13 has risen to the level shown in FIG. 6, (6), the tube 41 for detecting tall blanks produces a detection signal, in response to which the conveyor 14 is halted to interrupt the delivery of blanks B1 into the magazine 13. As blanks B1 are taken out from the magazine 13 in this state, the level of the uppermost blank B1 inside the magazine 13 descends, gradually decreasing the inclination of the blanks on the conveyor 14 with respect to the horizontal. Upon the level of the uppermost blank B1 within the magazine 13 descending to the level shown in FIG. 6, (a), the tube 41 for tall blanks B produces a non-detection signal again, whereupon the conveyor 14 is driven in response to the signal to deliver blanks B1 into the magazine 13.

    [0020] FIG. 6, (b) shows the blank supply alarm photoelectric tube 63 while it is producing a non-detection signal. It is desirable to replenish the conveyor 14 with new blanks when this signal is given. The replenishment is made manually by the worker by retracting the stopper 64 and placing blanks B1 in the emptied space.

    [0021] If the blank takeout operation is continued without replenishment despite the emission of the non-detection signal from the alarm tube 63, the quantity of blanks B1 on the conveyor 14 further decreases to the state shown in FIG. 6, (c), whereupon the photoelectric tube 62 for detection to discontinue picking produces a non-detection signal. The picker 15 is then forcibly brought out of operation to discontinue the operation of taking out blanks from the magazine 13.

    [0022] FIG. 7, (a) shows an operation to feed medium-sized blanks B2. In this case, the photoelectric tube 42 for detecting medium-sized blanks produces a non-detection signal and detection signal for controlling the conveyor 14 for driving or stopping. FIG. 7, (b) shows an operation to feed low blanks B3 using the non-detection and detection signals of the photoelectric tube 43 for detecting low blanks.

    [0023] In feeding any of the three types of blanks B1, B2, B3 which are different in height, variations in the level of upper end of the blank B1, B2 or B3 in the magazine 13 or on the conveyor 14 is detected as described above.

    [0024] If the non-detection signal and detection signal of the tube 42 for detecting medium-sized blanks are used in feeding tall blanks B1 and when the state of FIG. 6, (a) is brought about, blanks B1 on the conveyor 14 are present in front of the tube 42 for the medium-sized blank, so that the tube 42 produces no non-detection signal. When the quantity of blanks B1 in the magazine 13 decreases from the state of FIG. 6, (a), reducing the inclination of the blanks B1 on the conveyor 14 with respect to a horizontal and causing the blanks B1 on the conveyor 14 to disappear from the position in front of the tube 42, the medium-sized blank detection tube 42 produces a non-detection signal. This means that for the tube 42 to detect whether blanks B1 are present or absent when the inclination of blanks has reduced, there is a need to greatly alter the quantity of blanks remaining within the magazine 13, whereas if the alteration is great, the pressure acting on the lowermost blank B1 in the magazine 13 varies greatly to adversely affect the blank takeout operation.

    [0025] Further when the inclination of the blanks B1 on the conveyor 14 with respect to the horizontal diminishes, with a reduced quantity of blanks present within the magazine 13, there arises the likelihood that blanks will clog an intermediate portion of the magazine 13 when falling from the conveyor 14 into the magazine 13.


    Claims

    1. A blank feeder comprising:

    a magazine (13) for accommodating a plurality of blanks (B) as arranged from a lower end to an upper end thereof in the form of a stack so that the blanks (B) are movable inside the magazine (13) under gravity towards an outlet (12) at the lower end of the magazine (13),

    a conveyor (14) forming a transport path for supporting the lower ends of a plurality of blanks (B) as arranged closely face-to-face on the conveyor (14) from a terminal end of the path near said magazine (13) to a starting end thereof the arrangement being so that the path of movement of the blanks (B) inside the magazine (13) makes an angle of 105 to 165 deg. with the transport path of the conveyor (14), and the blanks (B) on the conveyor (14) can not move on the conveyor (14) under gravity towards the terminal end of the path where a blank (B) on the conveyor is supported at its upper end by the uppermost blank (B) within the magazine (13),

    a sensor (41-43) for producing a non-detection signal when the quantity of blanks (B) remaining within the magazine (13) has decreased to not greater than a predetermined value and producing a detection signal upon the quantity of remaining blanks exceeding the predetermined value,

    drive means for driving the conveyor (14) in response to the non-detection signal of the sensor (41-43) and discontinuing the operation of the conveyor (14) in response to the detection signal,

       characterised in that the feeder is adapted to feed various kinds of blanks (B1, B2, B3) in different height, whereby the sensor (41-43) comprises the same number of non-contact type photoelectric tubes (41-43) as the kind of blanks (B1, B2, B3) said photoelectric tubes (41-43) being disposed at different levels in accordance with the heigth of various blanks (B1, B2, B3) so as to produce a non-detection signal or detection signal by detecting the displacement of an upper end of the blank (B) at the terminal end of the transport path due to an alteration in the angle of the same blank (B) in accordance with a variation in the quantity of blanks (B) remaining within the magazine (13).
     
    2. A blank feeder as defined in claim 1, wherein the path of movement of blanks (B) within the magazine (13) is orthogonal to an downwardly inclined axial extension line of a container forming mandrel (11) and the magazine (13) has its outlet (12) opposed to the axial extension line and below the mandrel (11).
     
    3. A blank feeder as defined in any of claims 1 or 2, wherein a stopper (64) for preventing blanks from falling down is provided so as to push the blanks (B) on the transport path of the conveyor (14) from the starting end of the transport path towards the terminal end.
     
    4. A blank feeder as defined in any of claims 1 to 3, wherein a photoelectric tube (62) for detection blanks (B) is disposed at the terminal end of the transport path of the conveyor (14), movement of a picker (15) for taking out blanks (B) from the magazine (13) being stoppable in response to a non-detection signal of the photoelectric tube (62) for detection in order to discontinue picking.
     
    5. A blank feeder as defined in claim 4, wherein a blank supply alarm photoelectric tube (63) for detecting blanks (B) is disposed at a predetermined distance away from the photoelectric tube (62) for detection blanks (B) toward the starting end of the transport path for giving an alarm when the photoelectric tube (63) does not detect a blank (B).
     


    Ansprüche

    1. Rohlingzuführvorrichtung mit

    einem Magazin (13) zum Aufnehmen einer Mehrzahl von Rohlingen (B), die von einem unteren zu einem oberen Ende des Magazins in Form eines Stapels angeordnet sind, so daß die Rohlinge (B) innerhalb des Magazins (13) unter Einfluß der Schwerkraft in Richtung eines Auslasses (12) am unteren Ende des Magazins (13) bewegt werden können,

    einer Fördervorrichtung (14), die einen Transportweg zum Aufnehmen der unteren Enden einer Mehrzahl von Rohlingen (B), die eng aneinander Fläche an Fläche auf der Fördervorrichtung (14) von einem hinteren Ende des Weges nahe des Magazins (13) zu einem vorderen Ende von diesem angeordnet sind, wobei die Anordnung derart ist, daß der Bewegungsweg der Rohlinge (B) innerhalb des Magazins (13) einen Winkel von 105 bis 165 Grad zum Transportweg der Fördervorrichtung (14) aufweist und sich die auf der Fördervorrichtung (14) befindlichen Rohlinge (B) nicht auf der Fördervorrichtung (14) unter dem Einfluß der Schwerkraft in Richtung des hinteren Endes des Weges bewegen können, wo ein Rohling (B) auf der Fördervorrichtung an seinem oberen Ende vom obersten Rohling (B) innerhalb des Magazins (13) gehalten wird,

    einem Sensor (41-43) zum Erzeugen eines Nicht-Erfassungs-Signals, wenn die Anzahl von Rohlingen (B), die innerhalb des Magazins (13) verbleibt, derart abgenommen hat, daß sie nicht größer als ein vorbestimmter Wert ist, und eines Erfassungs-Signals, sobald die Menge der verbleibenden Rohlinge den vorbestimmten Wert überschreitet,

    Antriebsmitteln zum Antreiben der Fördervorrichtung (14) als Antwort auf das Nicht-Erfassungs-Signal des Sensors (41-43) und Abbrechen des Betriebs der Fördervorrichtung (14) als Antwort auf das Erfassungs-Signal,

    dadurch gekennzeichnet, daß die Fördervorrichtung dazu geeignet ist, verschiedene Arten von Rohlingen (B1, B2, B3) in verschiedenen Höhen zuzuführen, wobei der Sensor (41-43) die gleiche Anzahl von kontaktlosen Vakuum-Photozellen (41-43) wie Arten von Rohlingen (B1, B2, B3) aufweist, die Vakuum-Photozellen (41-43) auf verschiedenen Niveaus entsprechend der Höhen der verschiedenen Rohlinge (B1, B2, B3) angeordnet sind, um ein Nicht-Erfassungs-Signal oder ein Erfassungs-Signal zu erzeugen, indem die Verschiebung eines oberen Endes des Rohlings (B) am hinteren Ende des Transportwegs aufgrund einer Winkeländerung desselben Rohlings (B) entsprechend einer Änderung der Anzahl von Rohlingen (B), die innerhalb des Magazins (13) verbleiben, erfaßt wird.
     
    2. Rohlingzuführvorrichtung nach Anspruch 1, worin der Bewegungsweg der Rohlinge (B) innerhalb des Magazins (13) senkrecht zur abwärts geneigten, axialen Verlängerungslinie eines Behälterumformdorns (11) steht und der Auslaß (12) des Magazins (13) gegenüber der axialen Verlängerungslinie und unterhalb des Dorns (11) angeordnet ist.
     
    3. Rohlingzuführvorrichtung nach einem der Ansprüche 1 oder 2, worin ein Anschlag (64), der verhindert, daß die Rohlinge herunter fallen, derart angeordnet ist, daß er die Rohlinge (B) auf dem Transportweg (14) vom vorderen Ende des Transportwegs in Richtung des hinteren Endes drückt.
     
    4. Rohlingzuführvorrichtung nach einem der Ansprüche 1 bis 3, worin eine Vakuum-Photozelle (62) zum Erfassen der Rohlinge (B) am hinteren Ende des Transportwegs der Fördervorrichtung (14) angeordnet ist, wobei die Bewegung einer Entnahmevorrichtung (15) zum Entnehmen von Rohlingen (B) aus dem Magazin (13) als Antwort auf ein Nicht-Erfassungs-Signal des photoelektrischen Rohres (62) zur Erfassung angehalten werden kann, um die Entnahme zu unterbrechen.
     
    5. Rohlingzuführvorrichtung nach Anspruch 4, worin eine Rohlingzufuhr-Alarm-Vakuum-Photozelle (63) zum Erfassen von Rohlingen (B) in einem vorbestimmten Anstand von der Vakuum-Photozelle (62) zum Erfassen von Rohlingen (B) ist in Richtung des vorderen Endes des Transportwegs angeordnet, um einen Alarm auszugeben, wenn die Vakuum-Photozelle (63) keinen Rohling (B) erfaßt.
     


    Revendications

    1. Chargeur d'ébauches comprenant :

    un magasin (13) destiné à loger plusieurs ébauches (B) disposées de son extrémité inférieure à son extrémité supérieure sous la forme d'une pile, afin que les ébauches (B) puissent se déplacer à l'intérieur du magasin (13) sous l'effet de la gravité en direction d'une sortie (12) située au niveau de l'extrémité inférieure du magasin (13),

    un convoyeur (14) définissant une trajectoire de transport pour supporter les extrémités inférieures de plusieurs ébauches (B) disposées face à face de manière rapprochée sur le convoyeur (14) depuis une extrémité terminale de la trajectoire, proche dudit magasin (13) jusqu'à une extrémité initiale de celle-ci, le dispositif étant tel que la trajectoire de déplacement des ébauches (B) à l'intérieur du magasin (13) forme un angle de 105 à 165 degrés avec la trajectoire de transport du convoyeur (14), et que les ébauches (B) situées sur le convoyeur (14) ne peuvent pas se déplacer sur celui-ci sous l'effet de la gravité en direction de l'extrémité terminale de la trajectoire où une ébauche (B) située sur le convoyeur est supportée au niveau de son extrémité supérieure par l'ébauche extrême supérieure (B) située dans le magasin (13),

    un capteur (41-43) destiné à générer un signal de non détection lorsque la quantité d'ébauches (B) restant dans le magasin (13) a diminué pour atteindre une valeur non supérieure à une valeur prédéterminée, et un signal de détection lorsque la quantité d'ébauches restantes est supérieure à la valeur prédéterminée,

    des moyens d'entraînement destinés à entraîner le convoyeur (14) en réponse au signal de non détection du capteur (41-43) et à interrompre le fonctionnement du convoyeur (14) en réponse au signal de détection,

       caractérisé en ce que le chargeur est adapté pour charger différents types d'ébauches (B1, B2, B3) de différentes hauteurs, le capteur (41-43) comprenant le même nombre de tubes photoélectriques de type sans contact (41-43) qu'il y a de types d'ébauches (B1, B2, B3), lesdits tubes photoélectriques étant disposés à des niveaux différents en fonction de la hauteur des différentes ébauches (B1, B2, B3) afin de générer un signal de non détection ou un signal de détection lorsqu'ils détectent le déplacement d'une extrémité supérieure de l'ébauche (B) au niveau de l'extrémité terminale de la trajectoire de transport, dû à un changement de l'angle de la même ébauche (B) en fonction d'une variation de la quantité d'ébauches (B) restant dans le magasin (13).
     
    2. Chargeur d'ébauches tel que défini dans la revendication 1, dans lequel la trajectoire de déplacement des ébauches (B) dans le magasin (13) est orthogonale à une ligne d'extension axiale inclinée vers le bas d'un mandrin de formage de récipients (11), le magasin (13) ayant sa sortie (12) située en face de la ligne d'extension axiale et au-dessous du mandrin (11).
     
    3. Chargeur d'ébauches tel que défini dans la revendication 1 ou 2, dans lequel un butoir (64) destiné à empêcher les ébauches de tomber est disposé de manière à pousser les ébauches (B) sur la trajectoire de transport du convoyeur (14) de l'extrémité initiale de la trajectoire de transport vers l'extrémité terminale.
     
    4. Chargeur d'ébauches tel que défini dans l'une quelconque des revendications 1 à 3, dans lequel un tube photoélectrique (62) destiné à détecter des ébauches (B) est disposé au niveau de l'extrémité terminale de la trajectoire de transport du convoyeur (14), un mouvement d'un dispositif de prélèvement (15) destiné à sortir des ébauches (B) du magasin (13) pouvant être stoppé en réponse à un signal de non détection du tube photoélectrique de détection (62) afin d'interrompre le prélèvement.
     
    5. Chargeur d'ébauches tel que défini dans la revendication 4, dans lequel un tube photoélectrique d'alarme de fourniture d'ébauches (63) destiné à détecter des ébauches (B) est disposé à une distance prédéterminée par rapport au tube photoélectrique (62) pour détecter des ébauches (B) vers l'extrémité initiale de la trajectoire de transport en vue de déclencher une alarme lorsqu'il ne détecte pas d'ébauche (B).
     




    Drawing