GB2257650A - Carton forming - Google Patents

Abstract

An apparatus for erecting trays from plane canonboard blanks has a die 17, and a reciprocating punch 12 which is driven in a cyclic motion to enter the die 17 carrying a blank with it, and retract from the die 17 after the die has erected the blank to form a tray carton. The blank is supplied to the punch 12 by a mechanism which takes the blank from the front of a stack of blanks in a magazine, and presents the blank in front of the punch 12 as it moves towards the die 17. The blank and the formed tray are held on the punch 12 by vacuum ports formed in the latter. <IMAGE>

Description

CARTON FORMING The invention relates to apparatus for forming cartons from blanks.

A first aspect of the invention relates to punch and die means for forming cartons from blanks. In prior apparatus it is conventional for a punch reciprocating along a linear path, to co-operate with a die to form a carton from a blank presented adjacent the die. As the blank enters the die, the carton is folded around the punch and formed, the punch passes through the die and the carton is released therefrom before the punch retracts back through the die. The carton elements are stuck together during this forming stage by means of pre-applied adhesives which are heated by hot air jets over the period between the time when the blank is presented over the die and the time when the punch enters the die. The apparatus operates in a cylical motion. The next blank is presented over the die immediately after retraction of the punch from the die.Thus the time which is available for heating the adhesives is that part of the cycle between retraction of the punch from the die and next entry of the punch in the die. Considered another way, the time during which the adhesives cannot be heated is the time during which the punch obstructs the die. Since conventionally, the punch has to pass right through the die to release the formed blank, this takes up a relatively large portion, say 50%, of the total cycle time. This leaves at most 50% of the cycle time for heating the adhesives. The minimum cycle time achievable is thus at least twice the time needed for heating.

The first aspect of the present invention provides apparatus in which the portion of the cycle time during which the punch obstructs the die is reduced significantly thus greatly increasing the proportion of the cycle time which is available for heating. This is achieved by providing apparatus in which the punch does not pass through the die to release the carton but retracts from the die carrying the carton for subsequent release.

Accordingly the first aspect of the invention provides apparatus for forming a carton from a carton blank comprising a die, means for sequentially delivering carton blanks to a position adjacent the die, a punch, means mounting the punch for movement in a cyclical motion between a forward position at which it enters the die with a blank to form a carton and a rearward position in which it is retracted from the die, and holding means adapted to hold the carton on the punch as the carton is formed in the die and as the punch is retracted from the die and to release the carton from the punch as the punch reaches its rearward position.

A second aspect of the invention relates to apparatus for singling a carton blank from a stack of blanks such as for delivery to a punch and die.

Conventionally such apparatus comprises one or more suction pads which are movable from a position at which they engage the leading blank of a stack and pick it up, and a position at which they present the blank over a die for subsequent engagement by a punch. A drawback with the conventional apparatus lies in the fact that the suction pads positively engage the blank and move it away from the stack in a rather rapid and sudden motion. This often leads to the next succeeding blank being drawn away with the leading blank. The second aspect of the present invention provides apparatus which allows an air gap to be created between the leading blank and the next succeeding blank before the leading blank is drawn from the stack.

This has the effect of preventing the next succeeding blank being drawn away with the leading blank.

Accordingly the second aspect of the invention provides apparatus for singling a blank from a stack of blanks comprising: a feed surface for supporting a stack of blanks on edge and for feeding the stack towards a singling station, a retractable stop acting on the leading blank at the singling station, an endless conveyor at the singling station having a run spaced from, and substantially parallel to, the plane of the leading blank of the stack, a vacuum box located adjacent the conveyor and acting to tend to draw the leading blank by suction towards and into engagement with the conveyor, and a retractable shroud partially surrounding the conveyor and the vacuum box and movable between a forward position adjacent the stack and a retracted position adjacent the conveyor.

An embodiment of the present invention is described below with reference to the accompanying drawings in which: FIG. 1 is a plan view of a carton blank; FIG. 2 is a perspective view of a formed carton; FIG. 3 is a front view of apparatus for forming cartons from blanks, FIG. 4 is a side view of the apparatus of Fig. 3; FIG. 5 is a part-sectioned side view of a device for feeding a stack of blanks to a singling station; FIG. 6 is a plan view of the device of Fig. 5; FIG. 7 is a part-sectioned view of a device for picking up a blank from a stack and conveying it to a punch and die; FIG. 8 is a front view of the device of Fig. 7; FIG. 9 shows diagrammatic sequential plan views of the operation of the devices of Figs. 5-8; FIG. 10 shows the mounting and drive of a cylindrical punch of the apparatus; and FIG. 11 shows the punch.

Referring to Figs. 1 and 2 it can be seen that a typical carton blank 1 comprises a bottom panel 2, a lid panel 3, side panels 4, corner flaps 5 and lid flaps 6.

The formed carton of Fig. 2 has its side panels 4 held by adhesive to the corner flaps 5. The lid panel 3 and lid flaps 6 remain in a single plane. After filling the carton is closed by adhering the lid flaps 6 to the outside faces of respective side panels 4.

Figure 3 shows a front view of apparatus 7 for forming cartons from blanks. The apparatus has a frame 8 including two side plates 9. The apparatus shown forms two cartons at a time and thus is provided with two stacks 11 of carton blanks (shown diagrammatically) and two cyclically operated punches 12. Formed cartons are carried from the apparatus on a single transverse conveyor 13. The layout of parts of the apparatus can be seen in Figures 3 and 4. Each half of the apparatus comprises a blank stack supporting and feeding device including a pair of side plates 14 and feeding means 15, a device 16 for picking up a blank from a stack and conveying it to a die 17, and a punch 12 driven in cyclical motion on a linkage 20.

As can be seen from Figs. 5 and 6 the blank stack feeding means 15 comprises a feed surface 21 for supporting a stack of blanks on edge and for feeding the stack towards a singling station at the left hand end of the feed surface as seen in Figs. 5 and 6. The arrow in Fig. 5 points in the feed direction. The feed surface 21 is partly provided by an endless conveyor 22 consisting of a pair of endless chains 23 mounted on brackets 24. Also mounted on the brackets 24 is a feed plate 25 whose upper surface is very slightly inclined to that of the conveyor 22 and forms the left hand end of the feed surface 21. As can be seen from Fig. 4, the feeding means is mounted in the apparatus at an inclination to the horizontal so that the blanks in the stack will move under gravity along the feed surface as successive blanks are removed from the stack at the singling station. The conveyor 22 is non-driven and runs freely. A retractable stop 28 passes through a notch 29 in the downstream end of the feed plate 25 to engage the leading blank of the stack and prevent any further movement to the left in Figs. 5 and 6. The stop 28 is pivotably mounted on a block 31 about a pivot 32 and can be retracted by operation of a ram 33 connected between the feed plate 25 and the block 31. In the retracted position (not shown) the stop is below the level of the feed plate and no longer engages the leading blank.

A device for picking up the leading blank from a stack and conveying it to a die is shown in Figs. 7 and 8. The device comprises an endless conveyor 35 provided by a pair of elastomeric belts 36 each passing over guide wheels 37, 38, 39 and 40 which are all fixed in the frame 8 of the apparatus. The endless conveyor 35 has a downward run 42 which is spaced from but substantially parallel to the plane of the leading blank of the stack.

An elongate polymeric block 43 fixed to the frame 8 of the apparatus is mounted between the belts 36 at their downward run 42 and extends above the run 42. The block 43 supports the guide wheels 37 and 38 and guide rollers 44. The block has a hollowed out section 45 in which an elongate metal block 46 is housed to form a vacuum box 47 which is permanently connected to a source of high displacement vacuum (not shown) via a hose 48.

Freely mounted wheels 49 are mounted in the block 46.

Spaced passages 50 connect the vacuum box to the space between the belts 36 at their downward run 42. The wheels 49 are tangential to the plane of the belts 36.

A shroud 51 comprising a pair of side plates 52 is pivotally mounted on the axis of the guide wheels 37. The side plates 52 are connected together by a back plate 53.

A ram 54 is connected between the back plate 54 and the frame of the apparatus and is operable to move the shroud between a forward position as shown in Fig. 7 in which the front edges 55 of the side plates are adjacent the leading blank of the stack, and a retracted position in which the front edges 55 of the side plates are adjacent the run 42 of the conveyor. In practice, the front edges of the side plates in the retracted position are located just behind the belts 36 on the side of the run 42 which is remote from the stack. An arrow in Fig. 7 shows the direction of motion of the conveyor.

The operation of the device for picking up a single blank from a stack is shown schematically in Fig.

9. At position a, the shroud is in its forward position such that the edges 55 of the side plates 52 engage the leading blank of the stack. The retractable stop 28 is in its raised position and prevents the leading blank from being drawn towards the vacuum box 47 by the suction generated therein. At position b, the stop 28 has been retracted and the leading blank is deformed towards the vacuum box. This operation is carried out slowly without mechanical action on the leading blank and as a result there is no tendency for the next succeeding blank to be drawn too. At position c, the stop 28 has been returned to its operative position to hold back the remainder of the stack as the shroud is retracted to its rearward position carrying the leading blank by virtue of the suction generated by the vacuum box.At position d, the shroud has reached its retracted position and the leading blank is held against the belts 36 and the wheels 49 by the suction of the vacuum box and is conveyed away down the run 42 of the conveyor which moves continuously. The shroud then returns to its forward position to pick up the next succeeding blank.

The blank conveyed away by the conveyor 35 drops off the bottom of the run 42 and is presented by means of guides and a stop in front of a die 17 (see Figs. 12 and 13). At this point adhesive located on the blank is heated by hot air jets in conventional manner prior to the blank being engaged by a punch 12 and formed in the die 17.

The mounting and operation of the punch is described with particular reference to Figs. 10 and 11.

The apparatus described has two punch and die arrangements, and the punches 12 are mounted on a pair of cross-bars 60. The cross-bars 60 extend between two identical linkages 20 arranged on either side of the apparatus. Each linkage 20 comprises a first limb in the form of a crank 61 driven in rotation about a shaft 62 by a motor 63. Pivotally connected to the free end of the crank 61 is a second limb in the form of a rod 64 of adjustable length. The other end of the rod 64 is connected between the ends of a third limb in the form of an arm 65 pivotally mounted on a side plate 9 of the apparatus. A cylindrical tube 67 rigid with the arm 65 extends across the apparatus to connect the two linkages together to be driven in unison by the motor 63.A fourth limb of the linkage, in the form of a further rod of adjustable length 68 is pivotally connected at one end to the free end of the arm 65. The other end of the rod 68 is pivotally connected to one end of a fifth limb of the linkage in the form of a slider 69. The slider 69 is reciprocated along a straight guide bar 70 fixed to the side plate 9 of the apparatus. A sixth limb of the apparatus in the form of a plate 71 is pivotally connected at one end to the other end of the slider 69. The cross-bars 60 are mounted on the plates 71 of the two linkages 20. A seventh limb of the linkage in the form of a yet further rod of adjustable length 72 is pivotally connected to the other end of the plate 71. The other end of the rod 72 is mounted for pivotal movement about a stub shaft 73 fixed to the side plate 9 of the apparatus.

The position of the linkage as shown in Figure 10 corresponds to the forward position of the punch 12 when it is within the die. In this position the slider 69 and plate 71 are aligned. It will be appreciated that the motion of the punch while in the die is approximately linear.

As shown in Figure 11, the punch 12 comprises a prismatic head 75 detachably mounted on the cross-bars 60. A tube 76 selectively connects the interior of the punch 12 with a source of vacuum (not shown) and a source of pressurized air (not shown). The vacuum or pressurized air is connected to the space around the punch through a port or ports (not shown) in the front face 77 of the punch (not visible in Fig. 11) and through ports 78 in the side faces 79 of the punch. As the punch engages a blank presented over the die 17, the bottom panel 2 of the blank covers the front face 77 of the punch and is held thereto by vacuum, and as the punch enters the die the side panels and corner flaps are mechanically folded towards the side faces 79 of the punch. The ports 78 are located so that the side panels 4 and corner flaps 5 are drawn to and held firmly against the side faces 79 of the punch by the suction of the vacuum which at that time is connected to the punch.

As the punch is retracted from the die and moves towards its rearward position shown in Figure 4, the adhesive on the blank, which has previously been rendered tacky by hot air jets, is allowed time to cool and set and so it adheres the carton panels firmly and permanently in their required mutual configuration. The adhesive may be, for example, in the form of a polythene coating which is pre-applied to the entire surface of the blank but only locally heated, or in the form of locally pre-applied adhesive. In an alternative arrangement (not shown) the adhesive may be a hot molten adhesive which is applied through nozzles located adjacent the die. In this case the hot air jets are not required.

At the rearward position of the punch the vacuum is switched off by a reversing valve and pressurized air is connected to the ports in the punch to cause the formed carton to be released. The released carton drops onto the transverse conveyor 13 and is carried from the apparatus.

Because the suction plays an important part in positioning the side panels and corner flaps of the blank in relation to the bottom panel, it is not necessary for the elements to be forced against the punch by the die 17. The die only needs to move them to a position at which they are influenced by the suction. Thus there can be considerable spacing between the punch and the die when the punch is in the die and a simplified die which can be readily adjustable in size for different cartons can be used. The punch is rapidly detachable and can be quickly replaced with a punch of a different size. A further advantage of the spacing between the punch and the die is that an absolutely linear motion of the punch as it enters the die is not essential. This permits simplification of the linkage through which the punch is driven.

It will be appreciated that all the elements of the apparatus are driven in timed relation such that after a formed carton is retracted from the die 17 on the punch 12, a succeeding blank is presented over the die by the device 16. Adhesive on the succeeding blank is heated by air jets whilst the blank awaits the return of the punch to the die. Since the punch obstructs the die for a relatively short period, a greater portion of the cycle time is available for heating.

The construction of the die 17 and location of nozzles for the hot air jets are shown in Figs. 12 and 13. The opening of the die is defined by a plurality of position-adjustable metal formers 81 each curving gently through 900 at the entrance to the die. The formers can be adjustably positioned to define different die sizes for different cartons. Guide plates 83 are mounted in front of the die and cooperate with a stop 84 to present the blank 1 over the die. Hot air tubes 85 with nozzles 86 direct jets of hot air to the appropriate parts of the side panels 4 and corner flaps 5.In Fig. 12 the nozzles directing hot air onto the corner flaps 5 are located behind the blank, that is, on the die side, whereas the nozzles directing hot air onto the side panels 4 are in front of the blank and the guide plates 83 are locally apertured so that the hot air can be directed through them onto the side panels.

The conveyor 13 is briefly described with reference to Fig. 14. This conveyor is similar to the conveyor 35 in construction in that the conveying elements are a pair of elastomeric belts (not shown) running over a block 90 connected to a source of vacuum. In this case, however, the block is divided into segments 91 which are sequentially connected to the source of vacuum by a valve 92. When a carton lies on the conveyor in a position over a segment 91 which is connected to the vacuum, it is drawn by suction into frictional engagement with the elastomeric belts on which it is carried and is thus conveyed to the left in Fig. 14. The timing of the valve 92 is such that vacuum is connected to the next succeeding downstream segment 91 as the carton arrives over it. The sequential connection of pairs of the segments 91 to the source of vacuum via the valve 92 is shown by views a) to d) of Fig.

14. The dotted lines running through the views represent the positions at which cartons are delivered from the two punches of the apparatus. Cartons delivered to the conveyor by the two punches are quickly and positively conveyed from the machine at a controlled rate but in a very gentle manner. Since only some of the segments 91 are connected to the source of vacuum at any one time, the energy loss is less than if all sections were permanently connected.

Claims (12)

Claims:

1. Apparatus for forming a carton from a carton blank comprising a die, means for sequentially delivering carton blanks to a position adjacent the die, a punch, means mounting the punch for movement in a cyclical motion between a forward position at which it enters the die with a blank to form a carton and a rearward position in which it is retracted from the die, and holding means adapted to hold the blank on the punch as the carton is formed in the die and as the punch is retracted from the die and to release the carton from the punch as the punch reaches its rearward position.

2. Apparatus as claimed in claim 1 wherein the holding means comprises ports provided in the punch and means for connecting the ports selectively to a source of vacuum and a source of pressurized air.

3. Apparatus as claimed in claim 2 wherein the punch has a head having a front face and four side faces, and wherein the ports are formed in the front face and the side faces of the head.

4. Apparatus as claimed in any of claims 1-3 wherein the means mounting the punch for cyclical motion comprises a linkage and wherein the motion of the punch within the die is approximately linear.

5. Apparatus as claimed in claim 1 wherein the means for sequentially delivering carton blanks comprises a continually moving conveyor provided with a vacuum box for holding blanks against the conveyor surface by suction.

6. Apparatus as claimed in claim 5 wherein the conveyor comprises a pair of spaced elastomeric belts running in parallel with the vacuum box located therebetween.

7. Apparatus for singling a blank from a stack of blanks comprising: a feed surface for supporting a stack of blanks on edge and for feeding the stack towards a singling station, a retractable stop acting on the leading blank at the singling station, an endless conveyor at the singling station having a run spaced from, and substantially parallel to, the plane of the leading blank of the stack, a vacuum box located adjacent the conveyor and acting to tend to draw the leading blank by suction towards and into engagement with the conveyor, and a retractable shroud partially surrounding the conveyor and the vacuum box and movable between a forward position adjacent the stack and a retracted position adjacent the conveyor.

8. Apparatus as claimed in claim 7 wherein the conveyor comprises a pair of spaced elastomeric belts running in parallel, with the vacuum box located therebetween.

9. Apparatus as claimed in claim 8 wherein the shroud comprises a pair of side plates located one to each side of the conveyor.

10. Apparatus as claimed in claim 8 wherein the side plates of the shroud are pivotally mounted on a common axis and movable between their forward and rearward positions by a ram.

11. Apparatus as claimed in any of claims 7-10 further comprising a stationary die and a cyclically driven punch wherein the endless conveyor is arranged to deliver blanks sequentially to the die.

12. Apparatus for forming a carton from a blank substantially as described herein with reference to the accompanying drawings.