NO141505B - PROCEDURE AND MACHINE FOR SHAPING A CONTAINER BLANK TO A TUBE-SHAPED BODY - Google Patents

Abstract

Method and machine for forming a container blank into a tubular body.

Description

The present invention relates to the shaping and erecting of packaging blanks into tubular bodies and in particular the invention relates to the initial stages when erecting blanks of e.g. cardboard with a plastic coating, which is die-cut in advance and equipped with folding lines delimiting four side walls which can be folded along the folding lines into a tubular packaging body with a rectangular cross-section, the free edges of the blanks being arranged to join each other.

The invention concerns a method for shaping a

flat packaging blank consisting of four wall panels separated from each other by parallel folding lines, into a tubular body, where opposing free edge zones which can be sealed under the influence of heat are exposed to heat and the blank is folded flat to bring the heated surfaces into overlapping contact,

whereupon they are sealed to each other along the overlapping edge zones and the flat-folded, edge-sealed blank is raised to tube shape, whereby the two outer fields in the blank are raised at an angle to the center fields to enable heating of the edge zones of the outer fields by the upright outer fields is made to move past devices with which the edge zones are heated, after which the outer fields are folded down towards the middle fields so that the heated edge zones overlap each other and are pressed together and cooled to ensure permanent bonding, and the peculiarity of this method is that straightening the edge-sealed blank into a tubular body with a square cross-section is made by folding the respective fields in relation to adjacent fields about the respective fold lines, the blank being folded flat in one of the blank's flat pressing planes being preformed and prepared for straightening into a tubular shape by. that the blank is folded flat in its second flat-pressing plane, so that after the second flat-pressing it is arranged at roughly right angles to each other so that they form a tubular packaging

body with open ends.

The machine according to the invention, in order to carry out the method, is characterized by the fact that it includes devices for straightening the outer fields in relation to the central field of the workpiece, which devices are made up of suction cups mounted on two pivotable carriers whose pivot axes coincide with the axial extent of each of the folding lines in the workpiece between its outer field and the inner fields, as well as holding devices to keep the fields in an upright position when the suction devices release their grip, the holding devices being made up of rods that can be moved to a raised position behind and under the outer fields after these have been raised , and that the suction devices and the holding devices have mutually synchronized movements, as well as a heating device past which the upright side panels of the workpiece's edge zones are arranged to pass, the heating device comprising a heating unit for heating the thermoplastic coating on one side of one edge zone and another heating unit for heating of the thermoplastic coating on the other side of the second edge zone, and also devices for holding the upright side panels in a suitable position so that they pass next to the heating units during the transfer from the panel erecting devices, these panel holding devices being constituted by a series of rotatable rollers mounted on shafts which are inclined in relation to the horizontal plane, as well as devices for receiving the packaging item with upright side panels whose edge zones are heated, as well as for folding down the said side panels so that the heated edge zones are brought to overlap each other, the receiving devices being made up of rotatable rollers which are positioned so that they receive and retain the upright outer fields on the blank which is passed through the machine in substantially the same angular position as during the heating operation, and the roller can be swung down to the horizontal plane to effect folding of the upright outer fields against the inner fields lying in a common plan.

The invention shall be described in more detail with reference to the attached drawings which, as an example, show an embodiment. Fig. 1 shows a blank for a packaging container suitable for use in carrying out the invention. Fig. 2 shows in perspective a somewhat simplified or schematic drawing of the machine according to the invention, for forming a blank as shown in fig. 1 to a rudder-shaped body.

Fig. 3 shows a plan view of the rear end (insertion end)

of the machine in fig. 2.

Fig. 4 and 5 show end views of the rear part of the machine in different functional positions. Fig. 6 is a cross-section of the heating part in the machine shown in fig. 2, seen in the subject's direction of movement. Fig. 7 shows a side view of the heating part which is shown in fig. 5 as well as a subsequent sealing part in the machine. Fig. 8 shows a cross section of the sealing part in fig. 7, seen in the subject's direction of movement. Fig. 9 shows a side view of a further part of the machine shown in fig. 2, for square forming of packaging bodies after their edge sealing. Fig. 10 and 11 show cross-sections through the part of the machine shown in fig. 9 in different functional positions.

In the embodiment of the invention shown in the drawings, a packaging blank is provided, which e.g. is made of plastic-coated cardboard, for a machine for forming and erecting blanks into a tube-shaped body, which blank is shown in fig. 1, that is, consists of four fields 1, 2, 3 and 4 which are arranged next to each other,

and a sealing field 5, which fields are designed to be folded along folding lines 6, as well as an end sealing field 7 arranged at each end of the blank and delimited by folding lines.

The first recovery step for a subject of the type shown

in fig. 1 consists in the sealing field 5 joining the free edge of the opposite field 1 to form a rudder-shaped body where

the end closing fields 7 protrude from opposite ends. The invention relates to the implementation of this stage of the construction.

A machine according to the invention for carrying out this operation is shown in simplified form in fig. 2 and consists of four parts which are adapted to sequentially process a workpiece which is fed through the machine by means of suitable conveyors, as

the workpiece is fed forward in the direction indicated by an arrow in fig. 1.

In part A of the machine, the outer side panels of the blank that is at the top of a stack of blanks are folded, as the folding takes place along folding lines, and the blank is held up with holding rails, after which the blank is fed on to part B. When the blank passes through part B, the side panels are held up by rollers , while the edge zones of the workpiece are heated in preparation for sealing. The blank then continues to part C where another roller set folds down the side panels so that their heated edge zones overlap each other, after which the thus folded blank passes between pressure rollers which seal the edge zones by uniting the heated piastre surfaces by fusion. From part C, the folded and sealed blank passes in a flat state to part D where there are devices for boyning the side panels 1, 2, 3 and 4 in relation to each other about the fold lines 6, as well as for shaping the blank into a rectangular tube-shaped body 8 which removed from the machine for a subsequent work operation, e.g. to a machine for filling and sealing containers.

The mechanical details in the folding part A in the machine are shown in fig.

3, 4 and 5. A stack 9 of blanks of the kind shown in fig. 1 is held by four uprights 10 which form a frame inside the machine's main frame 11. Shafts 12 are stored in the rear crossbeam of the main frame 11 and carry rocker arms 13. From each rocker arm 13 and at a distance from the shaft 12, a rotatable rudder 14 is arranged which projects out from the rocker arm and which encloses a further rudder 15 which is equipped with suction cups 16 which lies above the uppermost blank in the stack 9. The rear end of the rudder 14 is connected to a spring-loaded plate 17 to enable a certain rotation and self-centering of the suction cups . The rudder 15 is connected to a vacuum source, which is not shown, so that the suction cups 16 can

grasp the uppermost workpiece in the stack 9. As can be seen from the drawing, the suction cups sit above the outer fields 1 and 4 of the workpiece.

The axles 18 which are arranged in bearings 19 on the side beams i

the frame 11 carries at each end an arm 20 and between the outer ends of the arms 20 there is arranged on each side a carrier rail 21 which extends largely along the entire length of the blanks. The rear arm 20 in each carrier rail unit sits close to a rocker arm 13 which forms part of the corresponding suction unit and is connected to this through an adjustable link 22.

The beginning of the work process can be seen from fig. 4 where the suction cups

16 rests against the outer panels 1 and 4 on the uppermost blank in the stack 9. Suction force is applied to the suction cups 16 so that the blanks are gripped and the shafts 12 are twisted to turn the arms 13 and thereby fold the ppp blank blanks 1 and 4 along their fold lines to an upward position which appears from fig. 5. At the same time, the arms 20 are swung by the influence of the links 22 so that the carrier rails 21 are guided in the direction towards the sides of the upright fields 1 and 4. When the suction force in the suction cups 16 ceases, the fields 1 and 4 spring back from the suction cups, but are held upright with the help of the rods 21 (fig. 5) against which they are supported. The front end supports 10 each have a largely inclined piate 23 (fig. 3) which protrudes over the front corners of the uppermost blank in the stack 9. When the suction cups loft the upper blank's fields 1 and 4, the corners of each field are bent so that they slides past the respective plates 23 which catch the next blank in the stack and prevent two blanks from being lofted at the same time.

A pneumatic device 24 mounted in the middle of the cross beam in the frame 11 is arranged to drive a pusher 25 which contributes to the upper part being fed forward when the side fields 1 and 4 are _t)f tel: as can be seen from fig. 5. After a small forward movement of the pusher 25, the workpiece is caught by the driven rollers 26 which continue to feed the workpiece to a point where the rear edge of the workpiece engages a finger or a driver, 27 on the endless chain 28 which feeds the workpiece its subsequent motion.

The driven rollers 26 have corrugated surfaces which are formed by means of rings of plastic, rubber or the like arranged around a

cylindrical roller body.

A felt device 42 (fig. 7) which lies against the upper surface of the stack 9 gives, when a workpiece is removed, a signal to a pneumatic jack 43 which lifts the platform under the stack 9 so that the upper surface of the stack is always level with the pusher 25.

When the fields 1 and 4 of a workpiece are folded up as described above and the workpiece moves forward by means of the pusher 25, the workpiece is moved from part A of the machine to its part B which is shown in fig. 6 and 7.

A row of rollers 29 on stationary spindles with an angular position roughly corresponding to the angle at which the upturned fields 1 and 4 are held by means of the carrier rails 21 sit on each side of the machine frame and the upturned fields 1 and 4 arrive, as they leave the carrier rails 21 , to be captured by these rollers 2 9 and thereby held at roughly the same angle during the continued, forward movement. Two mutually separated portals 30 extend over the path of movement of the workpiece and each of these portals has at their midpoint a downwardly directed central bench 31 which at the lower end holds a spring-loaded platform 32 with side rollers 33 adapted to hold down the center panels 2 and 3 on a suitable subject against the lower rolls 26.

In consoles on the portals 30, a heating unit is mounted for heating the plastic coating in the edge zones of a passing workpiece. These heating devices are aimed at the areas of the workpiece to be lined together so that e.g. one device 34 is directed towards the outside of the sealing field 5, while the other heating device 35 is directed towards the inner edge zone of the field 1 which is to be brought into contact with the sealing field 5.

A convenient form of a heating device is made up of gas burners with gas supply through pipe 36 and with flames that are directed at the workpiece. The burners are adjustable.

When a workpiece passes part B, the edge zones on fields 1 and 5 are heated by means of aggregates 34 and 35 to such an extent that the plastic coating softens or melts so that the heated surfaces are united by fusion. In this state, the workpiece moves on to part C of the apparatus (fig. 7 and 8) over rollers 37 which are carried by rails on a lower frame plate 38 and during the movement they are guided in the lateral direction by means of side rollers 39. Over each side of the lower frame plate 38 and in the direction of movement of the workpiece is a rotatable shaft 40 which carries mutually separated support rollers 41

which essentially have the same shape as the rollers 29. By turning the shaft 40, the rollers 41 can be moved between a raised and a lowered position. In the lofted position, indicated by dotted lines in fig. 8, the fulles have a slope that corresponds to the rollers 29. In the lowered position, the rollers 41 are mostly horizontal (solid lines in Fig. 8), and when the rollers move from the loft to the lowered position, they fold the lower panels 1 and 4 so that the edge areas on the field 1 overlapping rests against the outside of the sealing tab 5. It should be noted that a workpiece when transferred from the machine's part B to its part C is gripped by carriers 27 which then feed the workpiece on.

In this folded state, the blank passes between the pressure rollers and past a dress roller 45 with counter rollers 46 so that a permanent seal is achieved in the sealing joint between fields 1 and 4. The dress roller 45 can be dressed by means of internal water circulation, which is not apparent from the drawing and by means of the dress roller, the heated plastic is brought to solidify.again.

The blank then passes over the rollers 47 to the part D of the machine

(fig. 9, 10 and 11). The purpose of part D is to fold up fields 1,2,3 and 4 in the blank, which is now edge-sealed, and to raise the blank into a rudder shape with a square or rectangular cross-section so that the blank can be further lined, e.g. to a packaging machine, as a tube-shaped container body with open ends. In order to achieve such a result, Part D is designed to bring opposing parties together

folded edges of the flat-folded edge-sealed blank which is fed to part D in the flat-folded state in the horizontal plane, which is evident from the solid lines in fig. 10. After the subject's

opposite folded edges are fast together, the workpiece is folded flat

in a largely vertical plane, which is evident from the dotted lines in fig. 10, after which the workpiece is raised under control to form a rudder-shaped body (fig. 11). The frame for part 1 consists of opposite side rails 48 and 49 which have guide tracks in the direction of movement of the workpiece and which can be displaced towards each other and

apart. The insides of these side rails 48 and 49 have recesses or guide grooves, similar to the guide grooves 50 and as can be seen from fig. 10, the folded edges of the workpiece slide into the recesses 50 during the movement of the workpiece from part C of the machine.

Under the side rail 48 there is a spring-loaded presser foot 51 which carries a suction cup 52 which is connected via a rudder 53 to a vacuum source. In the same way, a presser foot 54 sits under the side rail 49. When the flat-folded and edge-sealed blank has reached the recess 50, the side rails 48 and 49 are moved towards each other with the result that the upper horizontal fields 1 and 4 are folded upwards, while the lower fields on folded down in the same way. This changed folding is shown in fig. -10--where the subject's horizontal flat-folded position is shown in solid lines, while the subject's vertical flat-pressed position is shown in dotted lines. In this last position, the fields 2 and 3 are pressed together between the presser foot 51 and the presser foot 54. In this position, the suction cup 52 is brought into engagement with the field 3, after which the side rails 48 and 49 move away from each other. As a result, the field 3 in an upright position is pulled to the side (on the left in Fig. 10) towards the outer resting position of the suction cup.

A plate 55 is pivotably mounted on the side rail 48, and this

plate 55 is rotatably connected with a link 56. When the rail 48 is moved towards the rail 49, the link 56 will force the plate 55 to loft by the plate 55 rotating around its connection point in the rail 48 from the "closed" position (as the fren leaves it solid line in Fig. 10 and 11) to the upright position, which is evident from its dotted line in Fig. 10. When the rail 48 is moved back and retracts the field 3 with the help of the suction cup 52, the plate 55 will automatically fold down again as it revolves around the connection point under the influence of the link 56

and thereby the plate 55 comes to fold down the field 4 to a horizontal position (fig. 11). As a result of this shaping, where fields 3 and 4 are brought at right angles to each other, the opposite fields are angled in the same way and the blank takes the form of a tube-shaped body with a rectangular cross-section, as can be seen from fig. 11. It should be noted that in order to facilitate these

folding movements and to receive the folded edges of the blank, the recesses 50 have a considerable width and rounded corners. The edge-sealed and upright blank leaves the machine in a manner shown in fig. 2 to be fed on to a subsequent work operation, e.g. into a packaging machine, the workpiece being guided by the presser foot 51 on one side and by a series of blunt-conical guide rollers 57 on the other side.

The individual parts of the machine described above are operated jointly

by means of a drive 58 which is driven by a chain 59 from an external power source, the drive 58 being in engagement with a drive 60 which drives a chain or a belt 61 which is fast over drives or pulleys 62a and 62b arranged under part D in the machine (fig. 9). On the same shaft as the drive 58, a cam wheel 63 is arranged against which runs a cam roller 64 which sits on a lever 65 on a shaft 66 which is influenced by means of a spring 67 so that the cam roller 64 is forced to run against the cam wheel 63. The side rails 48 and 49 each sit in a slide 68 with reciprocating movement between rollers 69 under the control of an angle lift arm 70 which is rotatably supported on the machine frame at 71. Each slide 68 is connected to one arm of the angle lift arm via an adjustable link 72 (fig. 10), while the other arm of each angle lever is connected via an adjustable link 73 with a lever 65 which sits on the shaft 66 and is controlled by the gear wheel 58 in the manner described above. With each revolution of the gear wheel 63, the lifting arms 65 are given a rocking movement so that the side rails 48 and 49 on the slides 68 move back and forth as described earlier.

On the shaft for the pulley 62a sits another drive or a pulley on which runs an endless chain 74 (figs. 7 and 9) which, by means of gears or sprockets with a suitable ratio, drives the pressure roller 46 and a large drive 75. A chain 76 (fig. .7) which is driven by the drive 75 drives a drive 77 which in turn has a chain connection for driving a small drive 78. The drives 77 and 78 drive the rollers 26 and the chain 76 drives the carriers 27 which carry the blanks through the machine. On the shaft for the drive 75 sits a cam 79 against which runs a cam roller 80 which is arranged on a lift arm 81 which is rotatably supported at 82. The free end of the lift arm 81 stands above a cable 83 which runs over the pulley 84 in connection with the pulley 85 so that this is notified of a back-and-forth rotation. A cable 86 around the pulley 85 (fig. 4) runs over the pulleys 87 and 88

and has its ends connected to tension springs 89 which are attached to the frame 11. The pulleys 87 and 88 are arranged on the shafts 12 and when the lever arm 81 is tilted by the cam 79 at each rotation, the retraction of the cable 83 comes to turn on the pulley 85 and thus also on the pulleys 87 and 88 (in the opposite direction) so that the plates 13 with the suction cups 16 and the support pulleys 21 are tilted in the previously described manner. The final ejection of the upright tubular bodies takes place by means of carriers 90 on the chain or belt 61. The different gear ratios as well as the shape and setting of the combs are chosen with regard to the correct synchronization between the successive work operations on a workpiece so that it can be achieved a continuous blank flow through the machine..

Claims (4)

1. Method for shaping a flat packaging blank consisting of four wall sections (1, 2, 3, 4) mutually separated by parallel folding lines, into a tubular body, where opposing free edge zones that can be sealed under the influence of heat are exposed to heat and the blank is folded flat to bringing the heated surfaces into overlapping contact, after which they are sealed to each other along the overlapping edge zones and the flat-folded, edge-sealed blank is raised to tube shape, whereby the two outer fields (1, 4) of the blank are raised at an angle to the middle fields (2, 3) to enable heating of the edge zones on the outer fields by causing the upright outer fields to be moved past devices with which the edge zones are heated, after which the outer fields are folded down towards the center fields so that the heated edge zones overlap each other and are pressed together and cooled to ensure permanent bonding, characterized in that the erection of the edge-sealed blank into a tubular body with a square cross-section is carried out by the respective fields (1, 2, 3, 4) is folded in relation to adjacent fields around the respective fold lines (6), with the workpiece that is flat-folded in one of the workpiece's flat pressing planes being preformed and prepared for straightening into a tube shape by folding the workpiece flat in its other flattening plane, so that after the second flattening, it is largely arranged at right angles to each other so that they form a tubular packaging body with open ends. 2. Machine for carrying out the method as stated in claim 1, for forming a tubular container body from a flat blank of a packaging material which can be sealed by heating, and comprising four fields (1, 2, 3, 4) which are mutually separated by folding lines (6), characterized in that the machine includes devices for straightening the outer fields in relation to the central field of the workpiece, which devices are made up of suction cups (16) mounted on two pivotable carriers (14) whose pivot axes (12) coincide with the axial extent of each of the folding lines (6) in the workpiece between its outer fields (1, 4) and the inner fields (2, 3), as well as holding devices (20, 21) to keep the fields in an upright position when the suction devices (16) loosens the grip, as the holding devices consist of rods (21) which can be moved to a raised position behind and under the outer fields (1, 4) after these have been raised, and that the suction devices (16) and the holding devices (20, 21 ) have mutually synchronized movements, as well as a warm-up ng device (34, 35) past which the upright side panels of the edge zones of the workpiece are arranged to pass, the heating device (34, 35) comprising a heating unit (34) for heating the thermoplastic coating on one side of one edge zone and another heating unit ( 3 5) for heating the thermoplastic coating on the other side of the second edge zone, and also devices (29) for holding the uprighted side panels in a suitable position so that they pass next to the heating units during the movement from the panel erecting devices, these panel holding devices (29) consists of a number of rotatable rollers mounted on shafts that are inclined in relation to the horizontal plane, as well as devices (40) for receiving the packaging item with side panels facing upwards whose edge zones are heated, as well as for folding down the said side panels so that the heated edge zones are brought to overlap each other, as the receiving devices consist of rotatable rollers which are positioned in such a way that they receive and phase tholds the upright outer fields of the workpieces which are passed through the machine in largely the same angular position as during the heating operation, and as the rollers can be swung down to the horizontal plane to effect folding of the upright outer fields towards the inner fields which lie in a common plane. 3. Machine as specified in claim 2, characterized in that the rollers sit on shafts which are arranged at a largely right angle to a rotatable shaft (40), with the help of which the rollers can be swung down in the horizontal plane, and that the machine includes devices which can are moved in relation to each other and which have recesses (50) for receiving the side edges of the flattened, edge-sealed blank, which devices are arranged to move towards each other in order to lead the two upper and lower fields towards each other (1.4 : 2 ,3) which previously lay in pairs in a mostly common plane, whereby the blank is folded flat in a plane that is mostly at right angles to the original folding plane for the blank. 4. Machine as stated in claim 3, characterized in that one of the movable devices is equipped with suction devices (52) designed to grip one of the fields in the folded blank and to pull this field backwards when the respective movable device is moved backwards , and that the machine also comprises a flap element (55) which is controlled by one of the movable devices and is arranged to fold the fields in relation to each other so that they open and form a tubular body, the flap element consisting of a rotatable plate or flap arranged to fold down one of the upright fields to a position at a largely right angle in relation to the neighboring field, so that all four fields are arranged in such a way in relation to each other that a tube with a square cross-section is formed.