Method and apparatus for erecting an open cardboard box

Abstract: This invention relates to a method and an apparatus for automatically forming an open-top parallelepipedic carton (2) from a corresponding box-like open-ended blank (2'), each blank open end being provided with respective end closure flaps, characterized in that it comprises the successive steps of: providing an end closing pad (60) having an abutment plate or wall (61) of corresponding cross dimensions to those of the ends of the blank (2'); fitting said box-like blank over the pad (60), with the plate (61) of the latter positioned at one of the open ends; folding the closure flaps provided at the open end down onto the plate (61) and bonding them together to produce an open-top carton; removing the open-top carton thus obtained from the pad.

Description: This invention broadly relates to a method of forming cardboard containers of parallelepipedic shape, useful for storing and shipping food products therein. Such containers are commonly referred to as "cartons" in the art, and this term will be used to designate them throughout this specification and the appended claims. Cartons are generally obtained from cardboard diecuts which, by appropriate folding and gluing along preset lines, are given the form and stiff feature of an open-top parallelepipedic box having two or more flaps provided at its open top for effectively closing the box after it has been filled. In particular, the invention relates to a method of automatically forming an open-top parallelepipedic carton from a corresponding open-ended box-like blank having respective closure flaps provided at each end. Prior Art To manufacture cartons intended for packing food articles in general, and pre-packaged food articles in particular, therein, somewhat complex automated machinery has been made available in the art which included a carton blank magazine, a carton forming station, and a carton blank transport for transferring the carton blanks from the magazine to the forming station. Reference is made, for example, to US 4 437 851. In particular, prior art automatic machines had the carton blank magazine side-mounted above the forming station and arranged to receive and hold a vertical or sub-vertical stack of superimposed carton blanks, such that the transport could pick up the blanks one-by-one from the stack bottom. In order to periodically refill the carton blank stack in such a magazine, it had been necessary to provide a special loader, which is admittedly made somewhat unreliable by its complicated construction and, above all, by the nature and unpredictability of the carton blank "behavior". Thus, the operation of the whole machine is heavily dependent on this device being functional. At the forming station, the blanks are variously treated (folded, glued, etc.) to produce a desired open-top carton which is then delivered to a packaging machine, also known as boxing machine. To speed up the carton forming process, and keep the magazine size small, it has become common practice to load the magazine with carton blanks in a flattened condition, the so-called "pre-glued blanks", rather than with flat cardboard diecuts. A blank of this type is obtained from a corresponding diecut by making the sidewall of the carton to be produced and- juxtaposing one pair of faces of said sidewall to the other face pair. The use of such pre-glued blanks involves the need to open up the blanks prior to their processing through the forming station (the so-called blank unfolding step). In the prior art, this is done by the transport itself as it picks up the pre-glued blanks from the magazine, the latter being provided with a means adapted to cooperate with the transport in the operation. With the above operation, a carton blank is opened up into an orientation of its juxtaposed faces at right angles to each other, thereby yielding a substantially box-like open-ended structure. At the forming station, a forming die is engaged with the interior of said open-ended structure to enable pusher arms to fold and bond respective flaps together so as to close one of said ends, thereby yielding an open-top carton article. At the end of this forming step, the forming die is withdrawn, and the finished carton is conveyed to a loading station for further processing through the boxing machine. Although advantageous in more than one way, and substantially performing as expected -- as witnesses their widespread acceptance -- conventional automatic carton forming machines of the type just described have certain drawbacks, as explained herein below. First, automatic carton forming machines are highly complicated items of equipment which are expensive to run, critical to adjust, and command careful designing, all of which make them inflexible in terms of changes in production rate and of capability to handle varying size cartons. For instance, the blank magazine is complicated and expensive to run, in that it involves some critical manipulations of mechanical devices incorporated thereto for accommodating the stack of blanks, and coordinate operation of suction means for picking up each blank from the stack bottom, individually in a timed fashion. Furthermore, a FIFO (First-In-First-Out) processing mode is likely to contribute additional service costs from a jammed up blank picking up mechanism. Another drawback is that the blank unfolding operation involves a complex co-operation of interlinked suction mechanisms which dictate the machine timing and restrict the possibility of boosting the machine throughput. In addition, the forming station is difficult to adapt for handling cartons of different sizes. In an effort to fill this demand, in fact, a number of different forming dies are usually provided which can be exchanged according to the carton size to be manufactured. This contributes costly shut-downs for die switching, as well as added difficulty and downtime for re-adjusting the equipment to accept the new size. The technical problem underlying this invention is to provide a method and associated apparatus for forming cartons from corresponding box-like blanks with construction and performance features effective to overcome the aforementioned drawbacks with which the prior art is beset, by enhancing the production rate of and providing the apparatus with automatic carton size switching capabilities. Summary of the Invention The concept behind this invention is that of using a carriage for holding the opened blank to form an open-ended box-like structure, and a fixed pad over which the box-like structure is fitted; the pad being provided with a plate which can be widened to accommodate changing blank sizes. Based on this concept, the technical problem is solved by a method as previously indicated and defined in the characterizing portions of Claim 1 foll.. The invention also relates to an automatic apparatus as indicated and defined in the characterizing portion of Claim 7. The features and advantages of the method and apparatus according to the invention will become apparent from the following description of an embodiment thereof, given by way of non-limitative example with reference to the accompanying drawings. Brief Description of the Drawings In the drawings: Figure 1 is a perspective view of an apparatus according to the invention for forming cartons from blanks fed in a flattened condition; Figure 2 is another perspective view, under a different angle, of the apparatus shown in Figure 1; Figure 3 is a perspective view of a detail of the apparatus according to the invention; Figures 4 to 8 are respective schematic side views of the apparatus shown in Figure 1, during successive steps of the inventive method; Figures 9 to 13 are respective schematic side views of the apparatus shown in Figure 1, during the processing of a larger size carton blank in accordance with successive steps of the inventive method. Detailed Description Referring to the drawing views, an automatic apparatus according to the invention for forming open-top cartons 2 from carton blanks 3 is shown generally at 1 in schematic form. Each blank 3 consists essentially of a cardboard die-cut which comprises the four sidewalls, delimited by fold lines L, of the carton 2 to be formed and a plurality of flaps P arranged to form the carton end panels. In particular, each blank 3 comprises first and second juxtaposed pairs of said walls in a flat configuration. Where the cartons to be produced have rectangular bases, each of said wall pairs is comprised of a large wall PL and a small wall PC, and in said flat configuration, the large wall PL in the first wall pair has the small wall PC in the other pair juxtaposed to it. In other words, the large wall PL in one pair is offset from the large wall PL in the other pair. In addition, the blank 3 is of the pre-glued type, that is, said wall pairs are connected together by a fold line, at one end, and by a glued joint along their respective free sides opposite from said fold line, at the other end. The apparatus 1 is intended, particularly but not exclusively, for forming cartons provided with a side window for viewing the articles contained therein, being known in the trade as "American" cartons. The description to follow will deal with this specific design for convenience of illustration, without this implying any limitations to the Applicant's rights. The apparatus 1 comprises a blank magazine 4 for the blanks 3, a blank "unfolding" station 5 for opening up the blanks, and a carton forming station 6. The stations 5 and 6 are preferably aligned along a main longitudinal axis X-X of the apparatus 1; the magazine 4 being offset to one side of said axis X-X. The magazine 4 is to receive and hold a plurality of flattened blanks 3 which are laid horizontally on top of one another into a preferably vertical stack 7. The blanks 3 are made of a cardboard or another suitable material to yield strong but lightweight cartons 2. During the blank displaying step, to be carried out in accordance with the inventive method as explained hereinafter, the diecut is opened up, and the sidewalls PL, PC of the blank 3 are brought to an orientation at right angles with each other, thereby yielding a parallelepipedic or box-like open-ended structure, at the ends whereof the blank 3 is provided with respective flaps for closing the structure ends. This box-like structure will be later referred to as the box-like blank and referenced 2' in the drawing figures. Thus, the magazine 4 will contain a stack 7 of blanks 3 laid onto a belt conveyor 10 surface. The conveyor 10 is mounted to a magazine base 11 and only operated through an electric motor as a new stack 7 of blanks is to be loaded. The base 11 has an elongate rectangular shape in plan view, and rests on supporting feet 13. The base 11 includes a loading area 20 and an adjacent storage area 30 for the blanks 3, as shown best in Figure 1. A metal wall 14 is secured on a short side of the base to delimit the loading area 20 of the magazine 4 lengthwise. A second metal wall 15 is secured on a long side of the base to extend from the wall 14 perpendicularly thereto and serve as a bottom for the loading area 20. Provided along the other short side of the base 11, opposite from the wall 14, are two vertical angle bars 16, 17 of metal which delimit the storage area 30 of the magazine 4 lengthwise and engage with and retain the blanks 3 by the corner edges of their stacked configuration. One angle bar 16 is mounted fixedly and the other 17 is mounted slidably along a horizontal track extending parallel to the short side of the base 11. Thus, the spacing of the bars 16, 17, and hence the width of the storage area 30, can be adjusted to accommodate different width blanks. Advantageously, each of the bars 16, 17 has the end of a respective plate 19, 21 attached thereto which overhangs the conveyor 10 parallel to the long sides of the base 11 facing the loading area 20. The opposite end of each plate 19, 21 supports a respective sheet-like side frame 22, 23 which extends vertically to retain the blanks 3 sideways at their comers next to the loading area 20. A pintle 24, 25 is mounted on each of the side frames 22, 23, outside the storage area 30, for hinge connection to a respective closure plate 26, 27 extending perpendicularly to the side frames 22, 23. The plates 26, 27 cover and bound the storage area 30 on the loading area 20 side. A hydraulic drive is arranged to operate each pintle 24, 25 for angularly moving the plates 26, 27 to an open position where the loading area 20 is placed in direct communication with the storage area 30 for refilling the magazine 4. By operating the conveyor 10, a new stack 7 of blanks 3 can be readily moved from the loading area 20 into the storage area 30. According to the invention, the blanks 3 are picked up individually and transferred to the opening or unfolding station 5, where they are laid onto and held against a supporting deck 35 equipped with a suction hold-down means 36. According to an advantageous feature of this invention, the blanks 3 are picked up individually from the magazine 4, starting with the topmost accessible blank in the stack 7. Also advantageously, a robot 40 of the pick-and-place type is provided at the opening station 5. In particular, the robot 40 is mounted on a base 65 at the side away from the magazine 4. The robot 40 has an arm 42 which is journalled on the base 41 and continued in a forearm 43 ending in a removable tooling "head" 45 at its free end 44. The tooling head 45 includes a gripper means 46 of the suction type. Specifically, first and second gripper means are provided which comprise first 47 and second 48 sets of suction cups, respectively. The first set 47 include six suction cups adapted, as explained hereinafter, to grip a blank 3 from above, by the large wall PL of the latter. Advantageously, the second set 48 of grippers are mounted tiltably to the tooling head 45 of the robot 40 to more conveniently headle the blanks 3, as explained hereinafter. In particular, the second set includes four suction cups adapted to grip the blank 3 by its small wall PC adjacent the large wall PL gripped by the first set 47 of gripper means. The robot 40 is driven through a plurality of electric motors and pneumatic actuators, and is controlled by an electronic controller, not shown, which is input a plurality of signals relating the positions and movements of the arms 43, 43 and the head 45. The controller controls the movements of the robot 40 according to a sequence of instructions contained in a program which is run under an internal clock of the apparatus. The controller outputs a plurality of control signals which are addressed to corresponding motion transducers, not shown because conventional, for the electric motors to operate the robot arms and head, and to the pneumatic actuators for operating the suction means of the apparatus 1 in a manner and at times as will ensure proper timing with the inventive method. As shown best in Figure 3, the forearm 43 is obviously designed to reach above the stack 7 in the magazine 4 for individually picking up the blanks 3 and placing them onto the supporting deck 35. Advantageously, the tooling head 45 of the robot 40 is driven unfailingly over the stack 7 in the magazine 4, for the picking up step, to directly grip a blank 3, based on computations of the blank conjectural position carried out by the electronic controller. The tooling head 45 is also provided with proximity sensors connected to the controller, which sensors are only operated after a predetermined number of automatic pick-ups, e.g. ten pick-ups, to re-calibrate and re-inizialize the location of the stack 7 top stored in a memory associated with the electronic controller. The supporting deck 35 extends horizontally and forms the top wall of a powered carriage 37 which is moved back-and-forth on a central rail 38 extending along the longitudinal axis X-X of the apparatus 1 from the blank opening station 5 to the carton forming station 6, and back. Advantageously, the carriage 37 is provided with a suction holding means 36, e.g. pneumatically operated suction cups. These cups are operative to exert their holding power on the large wall PL of the lower pair of juxtaposed walls of the blank 3. A sidewall 39 is attached to the carriage 37 along the adjacent side of the carriage to the magazine 4 and extends vertically. An additional suction means 52 is provided at the top end of the wall 39; this means preferably comprises a set of horizontally aligned suction cups. The carton forming/closing station 6 includes an end-closing pad 60 facing the carriage 37 and provided, on its end facing the carriage 37, with a vertical abutment plate or wall 61 basically rectangular in shape. The cross-dimensions of the plate 61 are substantially the same as, or correspond to, those of the open ends of the box-like blank 2'. The underside of the plate is adjustable to lie flush with the hold-down supporting deck 35. The plate 61 also has first 66 and second 67 portions, each carrying a respective suction cup 68, 69 for holding corresponding portions of the bottom of the carton 2. The two portions 66, 67 of the plate 61 are mounted on telescoping guides for movement toward and away from each other in order to change the transverse extension of the plate 61, and hence of the pad 60, when the dimensions of the carton 2 to be produced are changed. These portions 66, 67 of the plate 61 are guided for movement toward and away from each other in an automatic manner by drives, according to the change in size involved. Alternatively, as shown in Figures 9 to 13, the portion 67 can be hinge connected with one side to the portion 66, such that it can be extended or tucked away, as required to accommodate the changed size. The pad 60 is mounted on a bridge structure 65, which is integral with the robot base 41 and the base 11 of the magazine 4, through an arm 62 which is pivoted for a tilting movement about a horizontal axis. A drive means 64 for operating the arm 62 is carried on the structure 65. The drive 64 for the arm 62 allows the pad 60 to be moved angularly through approximately 90° about the pivot axis of the arm 62 for shifting the plate 61 from its carton forming position, where it is facing the carriage 37, to a discharge position where the finished carton is delivered onto a transport 70 comprising an elevating transport. The movements of the carriage 37 and the arm 62 of the pad 60 is driven by an electronic control device, not shown because conventional. This electronic control device is programmable with wired logic and controls the various movements at the forming/end closing station 6 of the apparatus 1. Furthermore, the electronic control device is connected electrically to the electronic controller of the robot 40 for passing to the controller any interrupt or diagnostic signals enabling the controller to stop the robot movements on the occurrence of a failure or a jam in the forming station 6. The forming station 6 is provided with oppositely located glue dispensing devices 58 which are mounted to the bridge structure 65 on either sides of the axis X-X of the apparatus 1. Relative to the linear path of travel of the carriage 37 toward and away from the forming station 6, these dispensers 58 are located upstream of the plate 61 at an adjustably set level. The operation of the glue dispensers 58 is controlled by the electronic control device upon receiving an electric signal from a position sensor associated with the transfer path of said carriage 37. In particular, an encoder 59 is positioned at one end of the rail 38 to keep accurate track of the carriage 37 displacement and cause the dispensers to apply, during the carriage travel movement, an amount of glue onto at least two opposite flaps of the box-like open-ended blank 2', in timed relationship with the flap movement past the dispensers 58. Also provided is a pusher means 69 for folding down onto said plate 61 the closing flaps provided at one of the open ends, so as to bond the flaps together and produce said open-top carton 2. This pusher means 69 is operated during the final section of the carriage 37 travel, with the box-like blank 2' already fitting partly over the pad 60. The means 69 comprises a pair of oppositely located pushers 8, mounted to the bridge structure 65 on either sides of the axis X-X of the apparatus 1 and consisting of plates 8 disposed above and below the pad 60 for angular displacement toward the supporting deck 35. The steps of the method of this invention will now be described with reference to an initial condition of the apparatus 1 being ready to pick up the topmost blank 3 from a stack present in the magazine 4. This blank picking up step is carried out by lowering the gripper means of the tooling head 45 of the robot 40 into engagement with the upper pair of upward-facing walls PL and PC of each blank 3. The robot 40 will then take the blank 3, held parallel to itself (in a horizontal orientation throughout), from the magazine 4 to the forming station 5, and lay the blank 3 down onto the supporting/retaining deck 35 in the station. At this stage, the blank 3 is opened up with a pantograph-like movement (unfolded) by moving the tooling head 45 away from the retaining deck 35 along a predetermined blank unfolding path. Advantageously, this blank unfolding path is at least a section of the return travel path of the tooling head 45 of the robot 40 toward the magazine 4 to pick up the next blank. This enables the apparatus to handle the blanks 3 at a much faster rate than that provided by conventional "carton opening" equipment. As a characterizing feature of this invention, only the small wall PC in the upper wall pair of said blank 3 is released, by just deactuating the second gripper means 48 of said tooling end, before said tooling head 45 is moved away from the supporting deck 35. With this condition, only the large wall PL in the lower wall pair of the blank 3 and the large wall PL in the lower wall pair of the blank 3, being offset from each other, will be held in the respective gripper means 47 and 36. Advantageously, the gripper means 48 are mounted for tilt movement on the tooling head 45, and when operated, are shifted angularly not to interfere with the sidewall 39 of the carriage 37 during the return movement of the tooling head toward the magazine 4. During this return movement, the first gripper means 47 of the tooling end 45 retains its hold on the large wall PL of the upper wall pair of the blank 3. Said wall PL is then lifted off the supporting deck 35, entraining in its movement the adjacent walls PC of the blank and forcing them to move angularly about their respective fold/connection lines to the wall PL held against the supporting deck 35. In this way, the blank walls PL and PC, which have been opened with a substantially pantograph-like movement in a positive direction, are caused to take a position at right angles to each other and produce the box-like open-ended blank 2'. At this stage, the box-like open-ended blank 2' will be releasably attached to the transfer carriage 37, being held thereon by the means 36 and 52 provided on the carriage. At the next step of the inventive method, the box-like blank 2' is fitted over the pad 60, itself held stationary, with the plate 61 facing the carriage 37, at one of said open ends. The carriage 37 is driven along the rail 38 toward the pad 60. During the travel movement of the carriage 37, the glue dispensers 58 are actuated by the electronic control device receiving electric signals from the encoders 59 to suitably dab with glue at least two opposite flaps of the box-like open-ended blank 2'. The pusher means 69 is then operated to produce a closed bottom in the open-ended blank 2, with the latter held at least partly over the plate 61 of the pad 60 by the suction cups of the plate. The bottom closing step provides for the pushers to fold the glue-coated flaps in a direction toward the plate 61, and the plates 8 to cooperate with the pushers in concurrently folding the perpendicular flaps to the glue-coated ones. Thus, a carton is produced on the pad 60 which has a closed bottom and an open top. The open-top carton 2 is then withdrawn positively from said pad 60, after its arm 62 has been moved angularly to a position where said plate 61 lie horizontally. The means of positively withdrawing said carton 2 from the pad 60 consists of the elevating transport 70, which is operated to take the finished carton 2 to a packaged article boxing machine. The apparatus 1 of this invention does solve the technical problem and offers a number of advantages, foremost among which is surely that the apparatus throughput and rate of carton blank opening can be much higher than in conventional apparatus. In addition, the apparatus and method of this invention can complete the formation of cartons in a more effective and simple style, to the point that the possible occurrence of a jam condition in the automatic operation of the apparatus is effectively minimized, and in all events can be easily fixed by unskilled personnel.

Claims: A method of automatically forming an open-top parallelepipedic carton from a corresponding box-like open-ended blank (2'), each blank open end being provided with respective end closure flaps, characterized in that it comprises the successive steps of: providing an end closing pad (60) having an abutment plate or wall (61) of corresponding cross dimensions to those of the open ends of said box-like opened blank (2'), said plate or wall lying in a vertical position; fitting said box-like blank over said pad (60), with the plate (61) of the latter positioned at one of said open ends; folding the closure flaps provided at said one open end down onto said plate (61) and bonding them together in order to close said end and to produce said open-top carton (2); removing the open-top carton (2) thus obtained from the pad after the latter has been moved angularly to a position where said plate would lie horizontally. A method according to Claim 1, characterized in that , to permit of fitting the box-like blank over said pad, said blank (2') is attached releasably to a transfer carriage (37) guided for movement toward and away from said pad along a perpendicular direction to said plate. A method according to Claim 2, characterized in that a glue is dispensed onto oppositely located flaps to be folded down onto said plate during the movement of said carriage (37) toward said pad (60). A method according to Claim 3, characterized in that the glue dispensing is enabled by an electronic control device receiving a signal from a position sensor (59) associated with the travel path of said carriage (37). A method according to Claim 1, characterized in that the pad angular movement is controlled by said electronic control device. An apparatus for automatically forming an open-top parallelepipedic carton from a corresponding box-like open-ended blank (2'), each blank open end being provided with respective end closure flaps, characterized in that it comprises: an end closing pad (60) carried on a tiltable arm (62) about a horizontal axis; a plate or wall (61), associated with one end of said pad and having corresponding cross dimensions to those of the open ends of said blank (2'); a means (64) of moving said arm (62) angularly about said axis from a position where said plate (61) lies vertically to a position where it lies horizontally, and back; a blank transfer carriage (37) guided for movement along a straight horizontal path toward and away from said pad, said carriage being provided with a means (36) of holding releasably thereon a box-like blank in a position with its open ends oriented along the travel direction of the carriage, in order to fit the box-like blank over the pad, with the plate (61) positioned at one open end of the blank; a glue dispensing means (58) disposed along the travel path of said carriage (37) for dispensing glue onto opposite flaps of the end to be closed of said blank; a means (70) of positively removing from said pad an open-top carton formed thereon. An apparatus according to Claim 6, characterized in that said plate (61) has at least first (66) and second (67) portions for changing the transverse extension of the plate on the occasion of a change in carton size. An apparatus according to Claim 6, characterized in that said carriage (37) has a horizontal deck equipped with a first hold/release means (36), and has a vertical wall (39) equipped with a second hold/release means (52) arranged to cooperate with said first means (36) for retaining two contiguous walls of the box-like blank. An apparatus according to Claim 6, characterized in that said means of positively removing the open-top carton from the pad (60) comprises an elevating transport (70).

Inventors: MARAZZI GIORGIO, MARAZZI, GIORGIO
Applicants: BARILLA ALIMENTARE SPA, BARILLA ALIMENTARE S.P.A.
Application year: 1999
Main classification: B31B5
IPC codes: B31B5