GB2289887A

GB2289887A - Device for feeding blanks to a user machine

Info

Publication number: GB2289887A
Application number: GB9510369A
Authority: GB
Inventors: Boldrini Fulvio
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 1994-06-01
Filing date: 1995-05-23
Publication date: 1995-12-06
Anticipated expiration: 2015-05-23
Also published as: GB2289887B; ITBO940255A1; ITBO940255A0; DE19519224A1; GB9510369D0

Description

2289887 DEVICE FOR FEEDING BLANKS TO A USER MACHINE This invention relates

to a device for feeding blanks to a user machine. In the ensuing description, the term "blank" means any piece of sheet material usable in particular in a packeting machine for wrapping a product. To feed blanks to a user machine, consisting for example of a packeting machine arranged to fold the blanks about relative products, it is known to use a feed unit comprising essentially a hopper, from one end of which said blanks are withdrawn in succession by a withdrawal device to be fed to a subsequent user station. This withdrawal device comprises generally a carriage driven with reciprocating rectilinear motion along a path substantially perpendicular to an axis of the stack of blanks and supporting a suction Sector. This suction sector is connected angularly to a gearwheel engaging a fixed rack, and is substantially tangential to the exit end of the hopper. In this manner the suction sector can adhere by suction to the end blank of said stack and then remove this blank from the hopper by rotating about its axis following rectilinear travel of the carriage along said path. At the end of this carriage travel, the blank is transferred to a subsequent transport device, comprising for example rollers which convey it to the user station. Although the aforedescribed known device is mechanically efficient, it is of poor reliability because of the relatively violent acceleration and deceleration imparted to the carriage transporting the suction sector if associated with user machines having an operating rate exceeding a determined value. To improve the reliability of the feed of blanks to user machines a feed device has been devised (see also Italian patent application B092A 000109) in which at the exit end of the hopper the blanks are peeled off by a peel-off roller which feeds the end blank of the stack by pushing it to a suction roller which withdraws it and feeds it to the user machine. To ensure that the blanks are fed in correct phase relationship to the user machine the device in question also comprises phaser means consisting of a suction plate interposed between the peeloff roller and the withdrawing suction roller. This plate, under the control of actuator means able to cyclically interrupt its connection to a suction source associated with it, transfers each blank to the withdrawing roller at a predetermined moment. In addition to the said plate there is provided substantially tangential to said suction roller an arresting and counteracting roller which rotates in the opposite direction to the direction of advancement of the blanks and has a surface with a high coefficient of friction. The arresting and counteracting roller ensures correct positioning of each blank before its release by the phaser means, and also forms a stop for those blanks lying above the end blank. This device is more effective than the aforegoing device, but also has drawbacks in that the weight of the stack and the relatively large area of contact between the blanks, together with possible electrostatic cohesion between the blanks, are factors which tend to brake the blank during its advancement, so delaying its withdrawal by the suction roller, so that it consequently becomes out of phase with the user machine. In addition, particularly at high operating rates and for reasons related to the aforesaid factors, it can happen that the blanks are not effectively subdivided by the suction plate due to untimely creation of vacuum by said actuator means associated with the plate. As a result of this, subsequent correct feed of the blank to said arresting roller cannot be guaranteed. The object of the present invention is to provide a device for feeding blanks to a user machine which obviates the described drawbacks of the known art. The present invention provides a device for feeding blanks to a user machine, comprising a hopper for containing a plurality of stacked blanks and delivering the blanks through its exit end, in correspondence with which there operate peel-off means arranged to extract said blanks and to transfer them along a first advancement path to means for withdrawing and feeding individual blanks; said withdrawing means comprising a first roller for withdrawing individual blanks, which is rotatable about a first axis of rotation and defines a second advancement path connected to said first advancement path at a connecting region, and an arresting second roller which cooperates with said first roller and is positioned on the opposite side of said first and second path to the first roller, to rotate about a second axis of rotation parallel to said first axis of rotation in a direction equal to the direction of rotation of said first roller, said first and second roller being spaced apart by a distance approximately equal to the thickness of a said blank, characterised by comprising, for restraining the blanks situated in contact with said first roller, means positioned substantially in correspondence with the connecting region between said first and said second path to cooperate, in phase, with said first and second roller and movable between at least one operating position close to said second roller in which the restraining means intercept the front free end of each said blank, and a non-operating position providing free passage for said blank. The invention is described hereinafter with reference to the accompanying drawings, which illustrate a non-limiting embodiment thereof and in which: Figure 1 is a front view, shown partly in section and partly as blocks, of a device for feeding blanks to a user machine; Figure 2 is a schematic side view of the device of Figure 1 to an enlarged scale; and Figure 3 shows a detail of the device of the preceding figures to an enlarged scale. With reference to the figures of the accompanying drawings, and in particular with reference to Figure 1, the reference numeral 2 indicates a hopper for containing a plurality of blanks 1 to be fed to a user machine. The hopper 2 has a lower exit end 2U at which there operate peel-off means 5 which in the illustrated case form the first withdrawal and transfer means for withdrawing the blanks 1 in succession.

r Said means 5 transfer groups 1G of superposed mutually contacting blanks from the exit end 2U of the hopper 2 along a first rectilinear advancement path P1 extending in a direction which feeds the blanks 1 to subsequent withdrawal and feed means 6. Said withdrawal and feed means 6 are arranged to withdraw and then feed individual blanks 1P of the group 1G to a user station 4, consisting of a user machine of known type indicated schematically as a block. Specifically, the withdrawal and transfer means 5 comprise a conveyor belt 25 positioned below the hopper 2 and extending endlessly about two rollers 26, at least one of which is motorized, and having its upper branch 25' arranged in substantial contact with the blanks 1. The belt 25 feeds the blanks 1 along a corridor 20, described in detail hereinafter, which is defined by two mutually facing walls 21 and 22 extending between the exit end 2U of the hopper 2 and said means 6 for withdrawing and feeding ndividual blanks 1. The number of blanks 1 forming each group 1G depends on the distance between said two walls 21 and 22 and the thickness of each blank 1. At the upper end of the corridor 20 there is provided in proximity to the hopper 2 a roller 23 which acts as a lead-in for the entry of the group 1G of blanks into the corridor 20. As shown in Figures 1 and 2, the means 6 for individual withdrawal and feed consist essentially of a withdrawing first roller 7 and an arresting second roller 9, which are substantially tangential to each other, with both rotating in an anticlockwise direction (Figure 1) about respective axes X1 and X2. The first roller 7 is arranged to grip and retain an individual blank 1P, and is rotatable about the axis X1 in the same direction V1 as said feed direction. The roller 7 is also substantially tangential to the wall 22 at the exit position of the corridor 20 on the opposite side of the corridor 20 to the wall 21. The roller 7, defining a second path P2 of arcuate advancement of the individual blanks 1P towards said user station 4, consists of a drum 7T rotatable about the axis Xl. In the preferred embodiment shown in Figure 2, the drum 7T is split into two separate equal parts 7A and 7B spaced axially apart to define an inner compartment within the roller 7 and keyed onto a single horizontal hub 32. The cylindrical peripheral surface of the drum 7T is provided with a plurality of radial holes 7S selectively communicating, in known manner, with a compressed air source, not shown. The holes 7S are intended to retain the individual blanks 1P by suction at determined points of the peripheral surface of the drum 7T. Said arresting second roller 9, which cooperates with the first roller 7, is positioned on the opposite side of said first and second paths P1 and P2 to the first roller 7, and rotates about a second axis X2 parallel to the first axis X1 of the first roller 7 in said direction V2. In practice, the second roller 9 rotates in the opposite direction to said feed direction, so intercepting the remaining blanks of the group 1G fed into the corridor 20 which lie above that withdrawn by the first roller 7. In this respect, the distance between the two rollers 7 and 9 is substantially equal to the thickness of a blank 1. As can be seen in Figure 3, means 10 for restraining the A individual blank 1P retained by the first roller 7 cooperate with the first and second roller 7 and 9. The restraining means 10 are positioned at the connecting region Z between the first and second path P1 and P2. More specifically, the means 10 consist essentially of an arm 13 pivoted at one end about a third axis of rotation X3 situated in a region between the corridor 20 and the first roller 7 and extending within said compartment defined by the two equal constituent parts 7A and 7B of the roller 7 (in practice the arm 13 is pivoted to the end part of the horizontal wall 22). The arm 13 is movable, in phase with the operating stages of the user station 4, between an operating position close to the second roller 9 (shown in Figure 1), in which the arm 13 intercepts the front end of the individual blank 1P, and a non-operating position removed from the second roller 9 (shown by dashed lines in Figure 1), in which the arm 13 allows free passage to the individual blank 1P retained by the first roller 7. This latter position is preferably maintained by the arm 13 during the advancement of the first portion of the individual blank 1P dragged by the first roller 7. The arm 13 intercepts the individual blank 1P in that its opposite operating end 11 is provided with an abutment tooth 15 defining an actual vertical abutting wall for the individual blank 1P when the arm 13 is moved into said operating position close to the second roller 9. When in this position the tooth 15 lies in a position perpendicular to the point of tangency between the roller 7 and the arm 13. Said corridor 20 extends longitudinally through a length depending on the length of the blanks 1. In this respect the corridor 20 is of such dimensions as to allow the group 1G of blanks 1 transiting along it to be subjected, when the blanks 1 are intercepted by said restraining means 10, to a substantially negligible compression action by the blanks 1 stacked in the hopper 2. In other words, the corridor 20 has a length substantially equal to the length of the blanks 1, so that when these latter arrive in proximity to the restraining means 10 they have almost completely left the hopper 2, and are hence not affected by the compression force generated on them by the stacked blanks 1. In order to enable the arm 13 to correctly withdraw an individual blank 1P, the arresting second roller 9 is provided with an outer surface the coefficient of friction of which varies in accordance with the angular position of the roller 9. In practice the second roller 9 acts on those blanks of the group 1G lying in said region Z by means of a portion thereof which has a high coefficient of friction and is able to halt said blanks 1 and maintain them at rest before they are fed individually to the first roller 7. This portion of high coefficient of friction corresponds to an angle C at the centre of the roller 9 extending from the region in which the arm 13 operates to a region situated beyond the point of contact of the second roller 9 with the remaining blanks of the group 1G. In order to effect the described restraining, the second roller 9 is provided with friction generating means 12, and comprises, continuously rotating about the second axis X2, an outer ring 16 sealedly mounted on a fixed inner hub 18 and comprising a Q plurality of through holes 17 uniformly distributed over its outer surface. The ring 16 centrally comprises (see Figure 2) a circumferential recess 19 for housing part of the arm 13 and tooth 15 when these are moved into their operating position. Rotating the ring 16 cyclically brings the holes 17 into correspondence with said friction generating means 12 fixedly positioned between the hub 18 and ring 16 and generating a vacuum along the arc corresponding to the angle C at the centre. The friction generating means 12 are located radially on the second roller 9 and comprise (see Figure 2 in particular) a suction chamber 30 opening on one side onto the outer ring 16 and connected to an air-tight conduit 31 connected to a suction source, not shown. The assembly formed by the chamber 30 and conduit 31 is securely fixed to the hub 18. The described device feeds the blanks 1 to the user machine in the following manner. Starting with the corridor 20 empty and the arm 13 in its intercepting operating position, the blanks 1 descend along the hopper 2 and are withdrawn by the belt 25, which in addition to initially removing the blanks 1 transfers them by advancing them along the corridor 20 with the aid of the lead-in third roller 23. During this stage the belt 25, in cooperation with the corridor 20, acts on a group 1G of blanks, which are made to advance in mutual contact. The group 1G of blanks hence passes along the first rectilinear path P1 by traversing the corridor 20, until it reaches the first roller 7. In the region Z where the first path P1 joins the second path P2, - 10 that individual blank 1P at the bottom of the group 1G is withdrawn by the roller 7 by virtue of the vacuum present within the drum 7T, whereas the remaining blanks 1 lying above the bottom are retained in this region by the suction created by the roller 9. The individual blank 1P is then advanced by the first roller 7 until it is intercepted by the tooth 15 of the arm 13 which, when commanded by a control unit 40 connected to a sensor 41 positioned along the second path P2, controls the passage (phase and feed frequency) of the advancing blanks 1, and moves into the lowered position to hence allow free passage to the individual blank 1P now correctly positioned. When a first portion of the individual blank 1P lies beyond the point of interception by the tooth 15, the arm 13 returns to its raised operating position to intercept the next individual blank 1P. The advancing individual blank 1P is then transferred to advancement rollers which insert the blank 1P into the user station 4. In the light of the aforegoing, the corridor 20 effectively forms a buffer store situated along the feed path of the blanks 1. The described device is constructionally very simple and consequently highly economical. The restraining arm, which effectively forms a re-phaser, represents a safety element with_ regard to the positioning and centering of the blanks 1 being fed, particularly at high operating speed, in that it is of mechanical type providing fast response in its interception and release movements. This feed precision is positively influenced by the presence of the suction roller 9.

1 11 ill 3:.

PATENT CLAIMS 1. A device for feeding blanks to a user machine, comprising a hopper (2) for containing a plurality of stacked blanks (1) and delivering the blanks (1) through its exit end (20), in correspondence with which there operate peel-off means (5) arranged to extract said blanks (1G) and to transfer them along a first advancement path (P1) to means (6) for withdrawing and feeding individual blanks (1P); said withdrawing means (6) comprising a first roller (7) for withdrawing individual blanks OP), which is rotatable about a first axis of rotation (X1) and defines a second advancement path (P2) connected to said first advancement path (P1) at a connecting region (Z), and an arresting second roller (9) which cooperates with said first roller (7) and is positioned on the opposite side of said first (P1) and second (P2) path to the first roller (7), to rotate about a second axis of rotation (X2) parallel to said first axis of rotation (X1) in a direction (V2) equal to the direction (V1) of rotation of said first roller (7), said first (7) and second (9) roller being spaced apart by a distance approximately equal to the thickness of a said blank (1), characterised by comprising, for restraining the blanks (1P) situated in contact with said first roller (7), means (10) positioned substantially in correspondence with the connecting region (Z) between said first (P1) and said second (P2) path to cooperate, in phase, with said first (7) and second (9) roller and movable between at least one operating position close to said second roller (9) in which the restraining means (10) intercept the front free end of each said blank (1P), and a non-

2. A operating position providing free passage for said blank (1P).

device as claimed in claim 1, characterised in that said first advancement path (P1) is defined by two facing walls (21, 22) bounding a passage corridor (20) starting from the side of said hopper (2) and extending substantially as far as said restraining means (10) through a length (L) depending on the length (1) of said blanks (1), its dimensions being such a to enable the blanks (1) transiting along it to be subjected, once intercepted by said restraining means (10), to a compression action by the blanks (1) stacked in said hopper (2).

3. A device as claimed in claim 2. characterised in that said corridor (20) has a length substantially equal to the length of said blanks (1).

4. A device as claimed in any one of claims 1 to 3, characterised in that said peel-off means (5) consist of withdrawal and transfer means for said blanks (1) and comprise a conveyor belt (25) extending endlessly about two rollers (26), of which at least one is motorized; said belt (25) having a branch (25) facing said hopper (2) and positioned in contact with said blanks (1).

5. A device as claimed in any one of the preceding claims, characterised in that said second roller (9) is defined peripherally by regions of different coefficient of friction, there being provided on the second roller (9) at least one region of greater coefficient of friction to halt a said blank (1P) withdrawn from said hopper (2) by said first roller (7), there also being provided friction generating means (12) cooperating ll A 7 with said second roller (9) and arranged to define said region of greater coefficient of friction.

6. A device as claimed in any one of the preceding claims, characterised in that said restraining means (10) comprise an arm (13) pivoted at one end about a third axis of rotation (X3) positioned in proximity to a region interposed between said first roller (7) and said first path (P1), and comprising at its opposite operating end (11) an abutment tooth (15) which, when in said operating position, defines an abutting wall for a said blank OP).

7. A device as claimed in claim 5 or 6, characterised in that said second roller (9) comprises a movable outer ring (16) sealedly mounted on a fixed inner hub (18) and having a uniformly distributed plurality of holes (17) which are moved into correspondence with said friction means (12) during the rotation of said ring; the friction means (12) being fixed and operating between said hub (18) and said outer ring (16). 8. A device as claimed in claim 7, characterised in that said friction means (12) are positioned radially on said second roller (9) and comprise a suction chamber (30) opening on one side onto the ring (16) and connected on its other side to a conduit (31) communicating with the outside of said roller (9) and fixed to said hub (18); said ring (16) centrally comprising a circumferential recess (19) able to house said restraining means (10) when in their operating position. 9. A device as claimed in any one of claims 6 to 8, characterised in that said first roller (7) is divided into two - 14 separate equal parts (7A, 7B) spaced apart to define a compartment and keyed onto a single horizontal hub (32); said restraining arm (13) being housed in and extending within said compartment. 10. A device as claimed in any one of the preceding claims, characterised in that in proximity to the connecting region between said corridor (20) and said hopper (2) there is provided a lead-in third roller (23) facilitating the advancement of said blanks (1) towards said corridor (20). 11. ' A device for feeding blanks to a user machine, substantially as described with reference to the figures of the accompanying drawings.