Method and apparatus for wrapping uniform piles of goods

Abstract

 When bundles (10) or piles of sheets or other goods are packed by means of a packing of the wrapper type, identical packing blanks (38) are used even though the height of the plies of goods varies to some extent. In order to obtain substantially the same tightness of the wrappers enclosing the piles, score lines or folding lines (67) separating closure panels (68) from side panels (58) of the wrapper blank are formed while the pile of goods is positioned on the blank. The forming of score lines takes place in a pressing station (60), where each pile of goods is compressed by a predetermined pressure by means of a pressure head (62). Thereafter, the pressure head is preferably moved a predetermined small distance upwardly, and then the score lines are formed by pressing the upwardly extending parts of the blank against a pair of edges (64) on the pressure head (62) by means of a corresponding pair of backing rollers (65). In this manner the height of the side panels (58) of the wrapper blank is adapted to the actual height of the pile of goods being packed.

Description

[0001] The present invention relates to a method of wrapping uniform piles or bundles of goods, such as piles of superposed sheets of paper or the like.

[0002] It is well-known to pack piles or bundles of goods by means of wrapper blanks which normally consist of rectangular blanks of cardboard, paperboard, or another foldable sheet material. Such wrapper blanks each comprises a bottom panel, which is defined between a pair of spaced, parallel folding lines or score lines with a distance corresponding to the width of the piles of goods to be wrapped, and a flap, which extend from each of the opposite sides of the bottom panel, and which is divided into a side panel and a top panel by an intermediate folding line or score line.

[0003] The goods to be wrapped by means of a wrapper of that type may manually be placed on the bottom panel of a plane wrapper blank. Thereafter, the blank is folded or bended along its score lines and wrapped around the goods so that the edges of the free ends of the wrapper blank are positioned closely adjacent to each other along the upper side of the pile of goods, and these adjacent edges of the wrapper blank may then be interconnected by stapling, by means of adhesive tape, or in any other conventional manner.

[0004] Packagings of the wrapper type are especially suitable when the goods to be packed are resiliently compressible to some extent, because the goods may then be retained within the open ended wrapper by suitably tightening the wrapper around the pile of goods.

[0005] When the goods to be packed are bundles or piles of paper sheets or the like the effective height of these piles may vary to some extent even when the number of sheets in each single pile or bundle is substantially the same. These variations in the pile height may, for example, be caused by variations in the thickness of the single paper sheet, in the moisture content of the paper sheets, in the air spaces defined between adjacent superposed paper sheets, etc. Because identical wrapper blanks provided with preformed score lines are used for packaging piles of goods with slightly varying height, the samples may be made based on an average height of the bundles or piles to be packed, and, consequently, the tightness of the wrapper enclosing each single pile will vary disadvantageously. When the piles of goods are packed manually the variations in the effective height of the piles of goods may to some extent be compensated for. However, this is not possible, when the piles are packed mechanically, because the relationship between the predetermined distance between the folding lines or score lines defining the side panels of the wrapper sample and the actual height of the pile of goods will then determine the tightness of the wrapper surrounding the pile of goods.

[0006] The present invention provides a method of the above type which is especially suited for use in connection with mechanical packaging of piles of goods.

[0007] Thus, the present invention provides a method of wrapping uniform piles or bundles of goods, such as pile- of superposed sheets, said method comprising arranging each pile on a central portion of a flat wrapper blank, which is made from a relatively stiff, foldable sheet material, and in which a first pair of spaced score lines separating the central portion from adjacent free end portions of the blank are formed, folding the free end portions of the blank upwardly along the score lines and into engagement with opposite side surfaces of the pile, detecting the length of the pile, forming in situ a second score line in each of the folded free end portions such that it is spaced from the bottom of the pile at a distance related to the detected height, folding the end portions of the blank along said second score lines and into engagement with the upper surface of the pile, and interconnecting the free ends of the blank so as to form a tubular wrapper package open at both ends.

[0008] Because the said second score lines are formed in situ, and because the spacing between each score line and the bottom of the pile to be packed is chosen in relation to the detected actual height of the pile, the method according to the invention renders its possible to obtain a uniform, optimum tightness of the wrappers even though the height of the piles of goods varies to some extent.

[0009] In order to secure the best possible uniformity of the tightness of the wrappers each pile of goods is preferably compressed by exposing it to a predetermined pressure prior to detecting the height of the pile. The greater the pressure is at which the pile is compressed, the better is the uniformity of the tightness of the wrappers. Therefore, the piles of goods are preferably compressed by exposing them to a pressure exceeding that corresponding to the desired tightness of the wrappers. Thus, the distance between the bottom of the pile and each of the second score lines is preferably made slightly greater than the height of the pile when exposed to said predetermined compressive force. Consequently, the pressure at which the piled goods are compressed in their packed condition is smaller than the pressure to which the pile is exposed by detecting the height of the pile.

[0010] Despite the variation in height of the piles to be packed it is preferred to use identical wrapper blanks for packing the piles. Because it is desired to avoid overlapping of the free end portions of the wrapper blank, even when the height of the pile is relatively small, the lengths of the wrapper blanks are preferably chosen such that it is smaller than or equal to the peripheral length of a vertical cross-section of the smallest pile to be wrapped. When the wrapper blank has been wrapped around a pile of goods a greater or smaller spacing will then be defined between the adjacent free ends of the blank. This space may, for example, be covered by an adhesive tape, such as a fibre glass reinforced adhesive paper tape, which is supplied to the upper side of the wrapper.

[0011] The invention also relates to an apparatus for wrapping uniform piles or bundles of goods as described above, said apparatus comprising first folding means for folding the end portions of a flat wrapper blank having a pile of superposed goods, such as sheets, placed on a central portion thereof upwardly into engagement with opposite side surfaces of the pile, means for detecting the height of the pile, means for forming in situ a score line in each of upwardly folded free end portions at a position spaced from the bottom of the pile with a distance related to the detected height, second folding means for folding the end portions of the sample along the score lines just formed and into engagement with the upper surface of the pile, and means for interconnecting the free ends of the blank. By means of such an apparatus, in which the folding lines or score lines are formed in the blanks in dependency of the actual height of the pile of the goods to be wrapped, it is possible to obtain substantially the same tightness of the wrappers despite small variations in the height of the piles, as explained above.

[0012] The means for detecting the height of each pile of goods may comprise a pressure head for compressing the pile from above at a predetermined pressure, and the means for forming score lines in the end portions of the blank may comprise folding edge portions formed on the pressure head and extending across the upwardly folded end portions, and means for pressing these folded end portions into engagement with the folded edge portions.

[0013] As explained above, it is normally desired to obtain a wrapper tightness which is smaller than that corresponding to the pressure at which the pile of goods is compressed by the pressure head. Therefore, it is desired to have the score lines formed in the end portions of the wrapper sample at a position slightly above the level of the bottom surface of the pressure head when the pressure head is compressed thereby. This may, for example be obtained by arranging the said folded edge portions on the pressure head at a small distance above the bottom surface of the pressure head. Alternatively, the said folded edge portions may be positioned at substantially the same level as the bottom surface of the pressure head, and the pressure head may then after compression of the pile of goods be moved a small predetermined distance upwardly from its lower position, before the folding lines or score lines are formed in the end portions of the wrapper blank.

[0014] The invention will now be further described with reference to the drawings, wherein

Fig. 1 is a diagrammatic and perspective view of a system or plant for packing piles of labels or other paper sheets, said plant comprising an embodiment of the apparatus according to the invention, and

Fig. 2 is a perspective view of piles of labels, which have been packed by the plant or system shown in Fig. 1.

[0015] The plant or system shown in Fig. 1 may be used in connection with a sheet pile separating and bundling apparatus as that described in applicants PCT-application No. DK83/00023. Bundles 10 of labels or sheets are supplied from this piling or bundling apparatus to a corner cutting apparatus generally designated by 12 by means of a conveyer belt 11. The cutting machine 12 is of a generally known structure and will therefore not be described in detail.

[0016] It is often desired to have one of the corners of the labels - which may, for example, be labels for cigaret packages - cut off. Therefore, the bundles 10 of labels successively supplied by the conveyer belt 11 may be delivered to a table 13 of the cutting apparatus 12, where they are pushed into engagement with an angular abutment member 15, which is movable by means of a pneumatic cylinder 14. The cylinder 14 may then successively push the bundles 10 into engagement with another angular abutment which is formed by an abutment plate 17, which is movable by means of a pneumatic cylinder 16, and an abutment plate 18, which is fixedly mounted on the table 13. A bundle 10 of sheets or labels engaging with the abutment plates 17 and 18 may be pressed against the table 13 by means of a piston-like retaining member 19 which is actuated by a pneumatic cylinder, while one of the corners of the sheet bundle is cut by means of a cutting knife 20, which is also actuated by a pneumatic cylinder. When a corner of the bundle has been cut off, the cylinder 16 is actuated so as to push the abutment plate 17 and the bundle of sheets into a path defined between a pair of funnel-shaped guide rails 21 for guiding the bundles of sheets or labels to a conveyer belt 22. The movements of the movable parts of the cutting apparatus 12 are controlled in dependency of signals received by detectors 23, 24, and 25, which may, for example, be in the form of photoelectric cells.

[0017] It is desired to have the bundles 10 of sheets or labels which have been cut in the cutting apparatus 12 collected into piles. In the embodiment shown in the drawings, each of these piles consists of two superposed layers of label bundles 10, in which each layer consists of three bundles, vide Fig. 2, and it is desired to have each of these piles packed in an open ended package 26 of the wrapper type as illustrated in Fig. 2.

[0018] The conveyer belt 22 and another conveyer belt 27 aligned therewith form a supply path for the sheet bundles 10. The conveyer belt 22, which has a relatively smooth surface, is continuously driven by an electric motor 28, while the conveyer belt 27, which has a relatively rough surface, is intermittently driven by means of an electric motor 29 in such a manner that a predetermined number (in the present case three) of the sheet bundles 10 is moved onto a supporting plate 31 which is movable by means of a pneumatic cylinder 30, and into engagement with a substantially vertical abutment plate 32, which is fixedly mounted on and movable together with an elevator device 33.

[0019] Feeding rollers 36 are feeding a web 35 of cardboard or paperboard from a supply roll 34 to a cutting device ."7 for cutting predetermined lengths from the web 35 so as to form wrapper blanks 38. These blanks are successively placed on a blank conveyer 39, which is driven by an electric motor 40, and which is formed by a pair of chains or belts 40, supplied with carrier members 41. Fixed rails 43 having a spacing corresponding substantially to the length of the sheet bundles 10 are arranged between these chains or belts, and the upper edges of the rails are arranged in such a level in relation to the upper surface of the upper run of the chains or belts 42 that the bottom side of the wrapper blanks 38 carried by the conveyer 39 are brought into engagement with the upper edges of the rails 43. Rollers 44 arranged above the rails 43 may be moved towards and away from these rails by means of a pneumatic cylinder 45. When a wrapper sample 38 passes the rails, the rollers are pressed against the wrapper blank, whereby a pair of spaced, parallel folding or score lines 46 defining a bottom panel 47 of the sample therebetween, are formed while the sample is passing the rails.

[0020] The blank conveyer 39 is operated so that the wrapper blanks which are now provided with folding lines 46, are successively passed to a position below the elevator device 33. When three sheet bundles 10 have been placed on the supporting plate 31, the supporting plate is moved to the right in Fig. 1 by means of the cylinder 30, whereby these bundles are supported by a comb-shaped horizontally extending supporting plate 48 forming part of the elevator device 33. The elevator device 33 is then moved downwardly by means of an electric motor 49, and a corresponding chain drive and the comb-shaped supporting plate 48 are thereby brought into engagement with a complementary shaped guide member 50. The supporting plate 48 is moved downwardly to a position in which it is in engagement with the wrapper blank 38, which is positioned immediately below the elevator device and which is supported by the blank conveyer 39 and by a conveyer 51 aligned therewith. Thereafter the supporting plate 48 is moved horizontally in a direction transversely to the conveyers by means of a pneumatic cylinder 52. As the vertical abutment plate 32 of the elevator device 33 does not participate in this horizontal movement, the three bundles will thereby come into direct engagement with and become supported by the bottom panel 47 of the wrapper blank. The elevator device 33 is now returned to its upper position and the supporting plates 31 and 48 are returned to their initial positions. Thereafter the conveyer belt 27 is caused to supply another three bundles on to the supporting plate 31, and by operations similar to those described above, these three further bundles are brought to a position in which they rest on the top of the three bundles previously positioned on the wrapper blank.

[0021] The conveyer 51 is now actuated, whereby the wrapper sample and the sheet bundle piled on the bottom panel thereof are moved to a blank folding station 53 at which swingably mounted side flaps 54 and end flaps 55 are arranged. These side and end flaps may be swung by means of pneumatic cylinders 56 and 57, respectively, from a substantially horizontal to a substantially vertical position. Thereby side panels 58 of the wrapper blank are folded upwardly against the sides of the sheet pile along the folding or score lines 46. At the same time the end flaps secure that the end surfaces of the sheet bundles 10 are flushing.

[0022] From the folding station 53 the partly folded wrapper blank and the sheet pile supported thereby are moved in between a pair of guide rails 59 by means of the conveyer 51. These guide rails serve to retain the side panels of the wrapper blank in their upturned positions till the sample and the sheet pile reach a pressing station 60.

[0023] The pressing station 60 comprises a pressure head 62, which is vertically movable by means of a cylinder structure, and the transverse position of the pressure head may be adjusted by means of a screw spindle 63. The pressure head 62 is made from a somewhat resilient material and comprises a pair of longitudinally extending edges 64 at the bottom side thereof. The pressure head also comprises a pair of swingably mounted backing rollers 65 which may be swung into engagement with the edges 64 by activating associated pneumatic cylinders. When a sheet pile with a surrounding, partly folded wrapper blank is moved from the folding station 53 into the pressing station 60, the free end portions of the side panels of the wrapper blank are moved along and in engagement with shoulder-like portions 66 of the pressure head so that the bottom surface of the pressure head is positioned immediately above the exposed upper surface of the pile of sheets. The cylinder structure 61 is now activated so that the pressure head 62 is moved downwardly and is caused to compress the pile of sheets at a predetermined pressure. From this lower compressing position of the pressure head which may be used as an indication of the actual height of the sheet pile in question, the pressure head is moved a small distance upwardly by activating the cylinder structure 61. In this new position the backing rollers 65 are swung against the edges 64 of the pressure head, whereby a pair of transverse folding lines 67 separating a pair of lid or cover panels 68 from the side panels 58 (Fig. 2) is formed in the wrapper blank. Because the folding lines 67 are formed a predetermined small distance above the upper surface of the sheet pile, when the same is compressed by a predetermined pressure, it is obtained that the distance between the folding or score lines 46 and 67 of the wrapper and thereby the height of the side panels 58 is accurately adapted to the height of the pile of sheets to be packed, even though the wrapper blanks are identical in other respects.

[0024] As indicated in Fig. 1, the cylinder structure 61 may comprise two cylinders 69 and 70, and the upward movement of the pressure head along the said predetermined distance after compression of the pile of sheets may then, for example, be obtained exclusively by actuating one of the cylinders, for example the cylinder 69, the movement of which may be detected by means of suitable detecting means 71.

[0025] The pile of sheets with the packaging blank wrapped around is moved by means of the conveyer 51 from the pressing station to a closure station 72, where the adjacent free edge portions of the lid panels are connected by means of an adhesive tape 73. By movement of the packaging and the piles of sheets wrapped thereby from the pressing station the lid panels 68 are moved under a pair of rails 74 extending along the path 51, whereby the lid panels are retained folded downwardly into engagement with the upper surface of the pile of sheet. A carriage 75 provided with a supply roll 76 of the adhesive tape is movably mounted at the closure station 72. The adhesive tape is passed over a number of guide rolls 77, 78, 79 into engagement with the upper surfaces of the free edge portions of the lid panels 68. A cutting knife 80 arranged after the guide roll 79 may be actuated by means of an associated pneumatic cylinder, and a radiation heater 81 is mounted on the carriage 75 after the cutting knife. When the adhesive tape is brought into contact with the lid panels so that it bridges the space 82 defined therebetween and the carriage 75 is thereafter moved in relation to the packaging or wrapper by means of a pneumatic cylinder 83, the lid panels are interconnected by means of the adhesive tape 73. The adhesive tape 73 is provided with a heat sensitive adhesive or a so-called "hot-melt", which may be made sticky by means of the radiation heater 81. The finished packaging may now be moved to a storing site by means of a conveyer 84.

[0026] The apparatus or system described above may operate automatically, and the various operations are then controlled by an electronic control circuit, not shown, receiving signals from sensors and detectors arranged at various positions of the apparatus.

[0027] It should be understood that while the present invention has been described with reference to packing of piles of labels or other paper sheets, the invention may also be used in connection with piles of other goods which are compressible to some extent, such as filters, mats, textile materials, or other fibrous materials.

Claims

1. A method of wrapping uniform piles or bundles (10) of goods, such as piles of superposed sheets by arranging each pile on a central portion (47) of a flat wrapper blank (38), which is made from a relatively stiff, foldable sheet material, such as cardboard or paperboard, and in which a first pair of spaced score lines or folding lines (46) separating the central portion (47) from adjacent free end portions (58,68) of the blank are formed, folding the free end portions (58,68) of the blank (38) upwardly along the score lines (46) and into engagement with opposite side surfaces of the pile, further folding the end portions (58,68) of the sample along a second pair of score lines or folding lines (67) into engagement with the surface of the pile, and thereafter interconnecting the free ends of the blank so as to form a tubular wrapper package open at both ends, characterized in that the height of the pile is detected while the pile is arranged on the wrapper blank (38), and that the second pair of score or folding lines (67) is thereafter formed in situ in the folded free end portions such that each of the second score lines is spaced from the bottom of the pile with a distance related to the detected height, and that the end portions of the blank (38) are thereafter folded into engagement with the upper side of the pile along the said second pair of score or folding lines (67).

2. A method according to claim 1,
characterized in that each of the piles is exposed to a predetermined compressive force, when the height of the pile is being detected.

3. A method according to claim 2,
characterized in that the distance between the bottom of the pile and each of the second score lines is made slightly greater than the height of the pile when exposed to said predetermined compressive force.

4. A method according to any of the claims 1-3,
characterized in that identical blanks (38) are used having their central parts (47) defined between said first pair of score lines (46) which are spaced with a distance corresponding to the width of the piles to be wrapped, the length of the blank being smaller than or equal to the peripheral length of a vertical cross-section of the smallest pile to be wrapped.

5. A method according to any of the claims 1-4,
characterized in that the folded free end portions (68) of the blank (38) are interconnected by means of an adhesive tape (73).

6. A method according to any of the claims 1-5,
characterized in that the goods to be wrapped are moved along a first path (22,27), that the wrapper blanks (38) are moved along a second path (39) located at a lower level, and that a pile of goods is formed on each blank by moving layers of goods from the first to the second path by means of an elevator (33).

7. An apparatus for use in carrying out the method according to claim 1,
characterized in first folding means (54,59) for folding the end portions (58,68) of a flat wrapper blank (38) having a pile of superposed goods, such as sheets placed on a central portion (47) thereof upwardly into engagement with opposite side surfaces of the pile, means (62,71) for detecting the height of the pile, means (64,65) for forming in situ a score line in each of the upwardly folded free end portions at a position spaced from the bottom of the pile with a distance related to the detected height, second folding means (74) for folding the end portions of the sample along the score lines just formed and into engagement with the upper surface of the pile, and means (72) for interconnecting the free ends (68) of the blank (38).

8. An apparatus according to claim 7,
characterized in that the means for detecting the height of the pile of goods comprise a pressure head (62) for compressing the pile from above at a predetermined pressure.

9. An apparatus according to claim 8,
characterized in that the means for forming score lines in the end portion of the blank comprises folding edge portions (64) formed on the pressure head and extending across the upwardly folded end portions, and means (65) for pressing these folded end portions into engagement with the folding edge portions.

10. An apparatus according to claim 9,
characierized in that the pressing means (65) are adapted to be operated when the folding edge portions are located at a predetermined small distance above the upper surface of the pile in its compressed condition.

11. An apparatus according to any of the claims 7-10,
characerized in further comprising a pair of vertically spaced upper and lower moving paths (22,27, and 39) for goods to be wrapped and for the wrapper blanks, respectively, and an elevator device (33) for transferring goods from the upper to the lower path so as to form a pile of goods on each of the wrapper samples arranged on the lower path.

Drawing