US3411263A

US3411263A - Method and apparatus for packaging sheets

Info

Publication number: US3411263A
Application number: US517313A
Authority: US
Inventors: Smolderen Albert Emiel
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1965-03-31
Filing date: 1965-12-29
Publication date: 1968-11-19
Anticipated expiration: 1985-11-19

Description

Nov. 19, 1968 A. E. SMOLDEREN METHOD AND APPARATUS FOR PACKAGING SHEETS Filed Dec. 29, 1965 "m 1m" 1; L

mvzmon ALBERT EMIEL SMOLDEREN United States Patent 3,411,263 METHOD AND APPARATUS FOR PACKAGING SHEETS Albert Emiel Smolderen, Wilrijk-Antwerp, Belgium, as-

signor to Gevaert Agfa N.V., Mortsel, Belgium, a Belgian company Filed Dec. 29, 1965, Ser. No. 517,313 Claims priority, application Belgium, Mar. 31, 1965, 13,718/ 65 7 Claims. (Cl. 5328) ABSTRACT OF THE DISCLOSURE Method and apparatus for wrapping sheets or stacks of sheets, wherein a first web of wrapping material is continuously supplied from a supply of such material, the marginal portions of the web are folded upwardly over a height exceeding the thickness of the sheets or the stacks of sheets, the sheets or stacks of sheets are fed successively onto spaced positions on the travelling web, the extremities of said upstanding marginal web portions are folded towards each other in one plane, a second web of wrapping material is continuously supplied from a supply of such material and conducted over the path of said sheets or stacks of sheets so as to accompany them in their travel with the first web, the sheets are flexed, the folded extremities of the first web and opposed longitudinal margins of the second web are progressively secured to each other, the flexed sheets are relaxed to tighten the wrap, and the first and second web are transversely sealed and severed between successive sheets or stacks of sheets.

The present invention relates to a method and apparatus for continuously wrapping sheets, and is particularly useful for tightly wrapping stacks of photographic film sheets.

It is known that packaged photographic film sheets are liable to damage their light-sensitive or generally radiation sensitive layer or layers due to the rubbing action of the packaged film sheets one against another during the handling of the package, e.g. during transport of such stacks.

A method for packaging stacks of film sheets has been proposed wherein the mutual immobility of the packaged sheets in ensured by tightly enclosing the stack of film sheets in the package. The stack of film sheets is put on a sheet of wrapping material, the said sheet is folded around two parallel sides of the stack While the stack is flexed, the axis of curvature of the flexed stack running parallel to both said parallel sides of the stack, and the opposed margins of the sheet of wrapping material are secured together in overlapping relationship in substantially one plane. After recovery of the stack into flat condition the wrapping material at the end portions of the sleeve projecting from the stack is folded closely against the corresponding edge faces of the stack.

A method and apparatus for packaging sheets as described hereinbefore are disclosed in our co-pending US. patent application No. 341,846 now abandoned.

Although the results obtained according to said method have been successful, the method is liable to one drawv back, viz. it is essentially discontinuous. The discontinuity is due to the necessity to use sheets of wrapping material instead of a web of such material, and further to provide a temporary support in the concavity of the flexed stack for supporting the overlapping opposed margins of the sheet of wrapping material while securing them together in substantially one plane. The use of wrapping material in the form of a sheet is imperative since it is 3,411,263 Patented Nov. 19, 1968 ice impossible, in case a web is used, to fold marginal portions of the web, having a width which is even greater than half the width of the stacks on the web, directly around such stacks on such web Without tearing or stretch ing out the web.

Apparatus for folding marginal web portions of the described sizes are known indeed, but in such apparatus the web is drawn over folding or turning members, which reverse the course of the web, thereby overstretching the material at the folding line, running the risk of impairing the light-tightness of the wrapping material in case of wrapping light-sensitive photographic material, and which make it impossible to insert into the folded web sheets or stacks of a thickness greater than some millimetres.

The present invention enables film or other sheets to be tightly bound against displacement by means of a wrapping material which is supplied in the form of a web. The term web denotes any flexible sheet or sheet-composition which can be continuously fed from a reel or roll.

According to the present invention a method of wrapping sheets or stacks of sheets is provided, wherein a first web of wrapping material is continuously supplied from a supply of such material, the marginal portions of the web are folded upwardly over a height exceeding the thickness of the sheets or the stacks of sheets to be wrapped, the sheets or the stacks of sheets are fed successively onto spaced positions of the traveling web, the extremities of said upstanding marginal web portions extending over the sheets or the stacks of sheets are folded towards each other in one plane, a second web of wrapping material is continuously supplied from a supply of such material and conducted over the path of said sheets or stacks of sheets so as to accompany them in their travel with the first web, the said folded extremities of the first web and opposed longitudinal margins of the second web are progressively secured to each other, and the first and second web are transversely severed between successive sheets or stacks of sheets. The invention also includes any apparatus having features which render it capable of automatically wrapping sheets or stacks of sheets by a method as thus defined.

The second web may be narrower than the first web, onto which the sheets or stacks are initially fed, and may be secured to longitudinal margins of the first web after folding these margins up against the adjacent edges of the sheets or stacks and onto their top faces. This folding of the margins of the first web may take place before the second web becomes located on the sheets or stacks so that this second web overlies the marginal portions of the first web which are on top of the sheets or stacks, or the said folding may take place or at least be completed after the second web has become located, so that the marginal portions of the first web extend over margins of the second Web. l it The webs are preferably secured together along transverse zones located between successive sheets or stacks, each transverse joint being formed before severance of the tube so that the wrapping of each sheet or stack is already completely sealed when the tube portion forming its wrapping is separated from the following portions of the webs.

The webs are preferably joined into tube form while the sheets or stacks lying between them are flexed, so that the tube portions wrapping the successive sheets or stacks are tensioned when the sheets or stacks unflex into fiat condition.

According to preferred embodiments of the present invention, a first web of wrapping material is continuously supplied from a roll of such material in a substantially horizontal plane, the marginal portions of the web are rectangularly folded upwardly, say over a height exceeding by 5 to 30 mm. the thickness of the sheets or the stack of sheets to be wrapped, the sheets or the stacks of sheets are placed successively and in spaced relationship on the advancing web, opposed edge faces of the sheets engaging the upwardly folded marginal portions of the web, the extremities of said upstanding web portions overtopping the sheets or the stacks of sheets (in the said case by a distance of 5 to 30 mm.) are folded towards each other in one plane, a second web of wrapping material is continuously supplied from a roll of such material onto the said folded extremities of the first web and secured thereto, the first and second web are transversely secured to each other between successive sheets or stacks of sheets, and the successive packaged sheets or stacks of sheets are severed by cutting the webs at the area where they are transversely secured to each other.

When the sheets or the stacks of sheets have to be tightly wrapped, the sheets or the stacks of sheets are flexed according to an axis of curvature which runs parallel to the longitudinal direction of the web so as to approach the opposed edge faces of the sheets or stacks of sheets, together with the engaging portions of the first web of wrapping material, towards each other prior to securing the second web to the first web. The sheets or the stacks of sheets are allowed to recover into substantially flat condition after both webs have been secured to each other, thereby tensioning the wrapping, and the first and the second web are transversely secured to each other thereafter.

When slightly changing the order of the successive steps of the inventive method, the extremities of the upstanding portions of the first web are only folded when the second Web has already been applied onto the sheets, so as to locate said extremities of the first web on top of the second web. This method will be preferred for wrapping single sheets of light-sensitive photographic material since in this wrapping, even if a slight interruption exists in the sealing of both webs, light cannot directly impinge upon the photographic sheet enclosed in the package. Indeed light has to be reflected over 180 after penetrating through an opening in the sealing joint between the second web and the folded extremity of the first web sealed thereon, before it can reach the film sheet.

The invention also includes apparatus for carrying out such preferred methods. Such apparatus comprises means for continuously advancing a first web of wrapping material over horizontal supporting means, first folding means adjacent said supporting means for rectangularly upwardly folding marginal portions of the web, feeding means for arranging the sheets or stacks of sheets in determined spaced relationship on the folded web, the opposed edge faces of the sheets engaging the upwardly folded marginal portions of the web, means for continuously advancing a second Web of wrapping material and applying it onto the sheets or the stacks of sheets placed on the first web and second folding means for folding the extremities of the upstanding portions of the first web towards each other so as to let the margins of the one web engage the folded extremities of the other web, means for securing said extremities of the first web and said margins of the second web to each other, means for securing the webs transversely to each other between successive packages, and cutting means for transversely severing the packages from each other.

The term sheet as used in the present description denotes also elongate strips of material the length of which is a multiple of the width, e.g. a strip of X-ray film with a length of 20 m. and a width of 30 cm., which is used in industry for radiographing welding joints of pipes.

By the term width of the sheets or the stacks of sheets in connection with the webs of wrapping material is meant the dimension of the sheets or the stacks of sheets located transversely with respect to the longitudinal direction of the web and running parallel to the plane of the web.

The term opposed edges of the sheets in connection with the web onto which they are located, denotes the two edge faces of the sheets or the stacks of sheets which run parallel to the longitudinal direction of the web.

The term stack of sheets denotes any plurality of stacked sheets of equal size, either or not provided with protecting leaves or cardboard sheets at the top and the bottom of the stack, with interleaves, etc.

The accompanying diagrammatic drawing illustrates an apparatus embodying the present invention for wrapping stacks of radiographic film sheets of determined sizes.

The illustrated apparatus comprises a basic part 10, a support 11 mounted at one side on said basic part and several smaller supports mounted at the opposite side on said basic part for supporting several parts of the apparatus.

The

rollers

12 and 22 are freely rotatable and they contain a first web 13 of wrapping material and a second web 23 of wrapping material, respectively. Two rollers 14 and 15 are mounted so that they are freely rotatable and they hold each a roll of

small tapes

16 and 17, respectively.

Two welding means 18 and 19 comprise each an electric heating element which heats a metal core ending in the

welding pins

20 and 21. Said pins exert a pressure on the side of the web 13 opposite to the side which, together with the

tapes

16 and 17, is passed over the free-turning roller 24.

First folding members and 26 fold the margins of the web 13 upwardly over 90. Second folding means 27, 28 fold the extremities of said upwardly folded margins again over 90 so as to locate them in a horizontal plane.

Stack positioning means is provided which is indicated by the numeral 30 and which in a known Way comprises two parallel rows of vertical fingers which cyclically can approach horizontally to each other over a given distance and then remove vertically from the web, so as to properly align the sheets of the stacks, which the operator has placed on the web between the said fingers in the longitudinal direction of the web and to properly space the successive stacks on the web.

A roller 31 which is stationarily fitted on a free-turning shaft 32 presses on the central part of the stacks as they pass under it. The stacks are flexed thereby, since the upper side of the basic part 10 is progressively concavely curved in the transverse direction from behind the stack positioning means 30 up to the said roller 31, and the upstanding portions of the

second folding members

27 and 28 slightly approach towards each other.

The second web 23 of wrapping material is passed over the free-turning roller 33 and it is applied with its margins onto the folded extremities of the margins of the first web.

Two welding means 34 and 35, provided with welding pins similar to those of the welding means 18 and 19, exert a pressure on the margins of the web 23.

After said welding means 34, 35 the concavity of the upper side of the basic part 10 of the apparatus progressively diminishes, and at the place of the transport roller system 36 the said upper side has recovered into its flat form.

The roller system 36 comprises two horizontal rows of driven rollers which engage a wrapped stack at either side thereof in order to advance the webs at a uniform speed and to flatten the stack, thereby tensioning the wrapping around the stack.

The transverse sealing means 37 comprises an upper transverse sealing bar 38, moved by a pneumatic cylinder 39, and a cooperating lower sealing bar (not shown) which can approach towards each other and press onto each other in a plane which is located half the height of the wrapped stacks. In a known way the sealing bars are provided at their cooperating faces with an electrically heated flat resistance Wire, which is covered with a strip of Teflon fabric (Teflon is a registered trademark of E. I. du Pont de Nemours & C0,, Wilmington, Del., U.S.A.).

A transverse cutting means 40 comprises an upper severing knife 41 moved by a pneumatic cylinder 42 and a cooperating lower knife (not shown) which can approach towards each other so as to separate the successive packaged stacks.

The sealing means 37 and the cutting means 40 are both mounted on a carriage 43 which is supported by guide rails 44. The carriage is cyclically moved to the left hand side, according to the figure, at the speed of travel of the webs over a distance which is shorter than the distance between two successive stacks, and thereafter it is returned at increased speed to the right hand side, according to the figure, in order to start a next cycle.

The said movements are imparted to the carriage by the chain 45 being cyclically driven by motor means in either direction. Motor means of the present kind are well-known in the art and have therefore not been represented here.

The operation of the apparatus for wrapping stacks of radiographic film sheets, each stack containing 125 sheets of NIF (non-interleaved film) film of x 8 inches, a protective cardboard sheet being provided at either side of the stack, will now be described.

The first web 13 has a width of 34 cm., the second web 23 has a width of 25 cm. Both Webs are composed of three adhering superposed layers, viz. a black paper layer, an aluminium layer and a polyethylene layer. Such like materials permit to package film sheets so that they are fully protected against moisture, chemical vapours and light. The web 13 is wound on the roll 12 with the polyethylene layer at the inside, the web 23 is wound on the roll 22 with the polyethylene layer at the outside.

The

tapes

16 and 17 consist of a tough kind of paper, they have a width of 3 mm. and a thickness of some tenths of a millimetre.

The

webs

13 and 23 are continuously pulled from the

rolls

12 and 22 by the driven rollers 36 being always in contact with at least one wrapped stack.

The operator places a stack of sheets on the advancing web 13 between the positioning means 30, the longitudinal direction of the sheets extending transversely of the web. The opposed transverse edges of the sheets engage the upstanding marginal portions of the web 13. The

tapes

16 and 17 remain in place at the inside of the upstanding marginal portions of the web when inserting the stack, since they have been secured to the polyethylene layer of the web 13 by means of the welding pins 20 and 21 which weaken the polyethylene layer and press the web against said tapes. The opposed longitudinal edges of the sheets of the stack are aligned by the stack positioning means 30 which after the aligning operation vertically remove from the web so as to let the stack pass by.

The stack of sheets is continuously advanced in flat condition by the web 13 until reaching the flexing roller 31. Immediately before this roller is reached the extremities of the upstanding margins of the web 13 have come into contact with the

second folding members

27, 28 which progressively fold said extremities towards each other.

The lower part of the roller 31 extending beneath the top side of the stack engaging its periphery, causes the stack to flex so as to make it pass under the roller. The flexing of the stack is permitted by the concave upper side of the basic part 10 as described hereinbefore.

The flexing of the stack is assisted by the vertical portions of the

folding members

27, 28 which slightly converge so as to exert pressure on the opposed edge faces of the stack.

When passing under the roller 33, the extremities of the margins of the first web 13 have been folded on top of the stack in one plane and the second web 23 is applied onto said folded extremities.

As the stack is still flexed, it passes under the sealing means 34, 35. Near its both extremities the web 23 is heated by the heating means 34, over a small path, so that its thermoplastic layer at the opposite side softens. Together with the pressure exerted by the sealing means, a tight joint is formed between the extremities of both webs. The tensioning of the webs in the longitudinal direction suflices to ensure a suflicient stiffness of the web portions between the successive stacks so that the webs are also well sealed to each other at those areas when passing under the sealing means 34, 35.

After said sealing means 34, 35 the concavity of the upper side of the basic part 10 gradually decreases, as mentioned already hereinbefore. When reaching the transport roller system 36 (in the drawing the distance between the sealing means 34, 35 and the roller system has been reduced considerably) the wrapped stack is flattened and the wrapping tensions around the stack.

When the wrapped stack is leaving the roller system 36, the last roller pair thereof still engaging the stack, then the carriage 43 has been located in the position most to the right according to the figure. A magnetic valve is opened, and air-pressure is admitted to the cylinder 39 so that the sealing bar 38 and the cooperating lower sealing bar approach to each other and transversely weaken and seal the web portions extending just in front of the wrapped stack. The opening of the valve may be triggered by sensing means 47 comprising a microswitch which is actuated by a lever, said lever being strongly biased so that the small roller, fitted as its extremity and running over the lower web, depresses slightly the web when a web portion between two successive stacks passes over it. Said roller is positioned at about 015 cm. after the vertical plane through the two sealing bars, and as it depresses the web when rolling over the trailing edge of the preceding stack, the sealing bars seal the webs right in the middle of the spacing between said preceding stack and the following one.

At the moment the sealing means 37 was actuated, also the means driving the carriage was started and the carriage 43 moves to the left at a speed equal to that of the webs. The electric circuit of the magnetic valve controlling the cylinder 39 remains closed by a delaying relay so that when the small roller rolls on the following stack, the sealing means remains operative.

After moving over a distance of about five centimetres the carriage, by an upstanding leg, actuates the micro switch 48, the electric contact of which controls a magnetic valve in the air-pressure supply of the cylinder 42. The transverse cutting means 40 is operated and separates two successive packages. The closed contact of the microswitch 48 further energizes a relay which breaks the electric circuit of the magnetic valve controlling the cylinder 39 so that the transverse sealing means 37 becomes inoperative.

The mentioned relay also reverses the drive sense of the motor means driving the chain and the carriage 43 returns to the right. The contact of the microswitch 48 re-opens whereby the transverse cutting means retakes its inoperative position. All these operations are performed within one second or so, so that the cutting means 40 only makes a quick cutting movement. When the carriage 43 has returned to the right, the mechanism is ready for being triggered by a next wrapped package.

The packages delivered by the apparatus may be removed from the apparatus by hand, or received by a transport mechanism for transporting them to another packaging machine which puts the packages separately in cardboard boxes. When use is made of rectangular cardboard boxes of a known type which are opened at one of the two opposed small sides a particularly interesting package for the films has been obtained. In fact, when the operator has to open a new package, he opens the cardboard box at one side by folding or tearing away the flaps, he pulls out the film package over a few centimetres so that he can seize the wrapping of the stack by a corner, and then he pulls away the said corner piece of the wrapping thereby tearing the tear strip which ends in said corner piece through the wrapping material over the width of the package. The tensioning of the stack is thereby removed since it has been applied in the longitudinal direction of the stack. Now the operator can pull, without difiiculty, the sheets out of the box one by one.

The described embodiment related to a method for tightly wrapping wherein the second web was applied on top of the first web and then secured thereto. It is clear that in applying the second web to the sheets to be wrapped before the margins of the first web have been folded over the sheets, the extremities of the first web overlay the margins of the second web. Such technique is even to be preferred when sheets must be wrapped which are not provided with a protective cardboard sheet or the like at either side, since in that event a greater safety can be attained with respect to defects in the sealing, as mentioned in the introduction of the present description.

The composition of the webs of wrapping material may be different from that of the webs used in the described embodiment. In the case the joint between the two webs is realized by applying a very quick drying adhesive, e.g. the known adhesives on the basis of lattices, by inserting a strip of thermoplastic tape, or by using a self-adhesive tape, the thermoplastic layer of the wrapping material may be omitted.

The apparatus may also be used for non-tightly wrapping stacks of sheets, and in such case the roller 31, the concave curvature of the upper side of the casing 10 and the convergency of the

folding members

27, 28 may be omitted.

The tear strips 16, 17 may be applied at only one side of the stacks or may even be omitted. Feeding means may be provided for feeding other strips, sheets or webs in the package, e.g. colour strips for characterizing the type of material contained in the package, thin lead foils in the packaging of single radiographic film sheets for use as intensifying screen, etc.

Finally means may be provided for automatically feeding the sheets or the stacks of sheets to be wrapped successively onto the first web, so that the apparatus may operate completely automatically.

I claim:

1. A method of wrapping sheets or stacks of sheets, comprising the steps of continuously supplying a first web of wrapping material, upwardly folding the marginal portions of the web over a height exceeding the thickness of the sheet or stack of sheets to be wrapped, feeding the sheets or stacks of sheets successively onto spaced portions of the travelling web, folding the extremities of the upstanding marginal portions of the web towards one another over said sheet or stack of sheets, flexing said sheets by causing their opposed edge faces, together with the corresponding portions of the folded web, to approach one another, continuously supplying a second web of wrapping material above the path of said sheets or stacks of sheets so as to accompany them in their travel with the first web, progressively securing together the said folded extremities of said first web and the opposed longitudinal margins of said second web, allowing the sheets or stacks of sheets to recover into substantially flat condition so as to tension the wrapping, and transversely securing said first and second webs to each other, and severing said webs, at positions between such sheets or stacks of sheets.

2. A method according to claim 1, wherein the marginal portions of the first web which are folded upwardly have a height exceeding by from 5 to 30 millimeters the thickness of the sheets or the stacks of sheets fed onto said web.

3. A method according to claim 1, including the step of feeding a tear strip continuously between at least one of said opposed edge faces of the sheets and the engaging marginal portion of the first web.

4. A method according to claim 3, wherein said tear strip is sealed to the inside of said first web.

5. A method of wrapping sheets or stacks of sheets, comprising the steps of continuously supplying a first web of wrapping material, upwardly folding the marginal portions of the web over a height exceeding the thickness of sheets or the stacks of sheets to be wrapped, feeding the sheets or stacks of sheets successively onto spaced positions on the travelling web, continuously supplying a sec ond web of wrapping material above the path of said sheets or stacks of sheets so as to accompany them in their travel, folding towards one another onto said second web the extremities of the upstanding marginal portions of the first web which extend above the sheets or stacks of sheets, flexing the sheets by causing their opposed edge faces to approach towards one another, together with the corresponding portions of the first web of wrapping material, securing the folded portions of the first web to the margins of the second web, and thereafter allowing the sheets or the stacks of sheets to recover into substantially flat condition, thereby tensioning the wrapping.

6. Apparatus for wrapping sheets or stacks of sheets, comprising means for continuously advancing a first web of wrapping material over a horizontal support, said support being provided with a concave curvature whose axis runs parallel to the longitudinal direction of said first web, first folding means adjacent said support for rectangularly upwardly folding marginal portions of said web, the sheets or stacks of sheets being placed in spaced determined positions on the said web, between and engaging the upfolded marginal portions thereof, second folding means for folding the extremities of the upstanding portions of the web towards each other, flexing means comprising opposed parts engaging the opposite edge faces of the sheets and the portion of the web lying thereagainst, to define a converging path for the said opposed edges of the sheets so as to cause them to approach to one another, whereby to flex the sheets, means for continuously advancing a second web of wrapping material and applying it onto the folded extremities of the first web, means for securing said extremities of the first web and the margins of the second web to each other, and means for securing the webs transversely to one another between successive packages and for transversely severing the successive packages from each other at the areas where they have been transversely secured to one another, the last-named means being positioned sufficiently after the locus of operation of said flexing means as to allow the sheets to be restored to their flat, unflexed condition and thereby to tension the wrapping formed by said webs.

7. Apparatus according to claim 6, including means for feeding a tear strip between at least one of said opposed edge faces of the sheets and the edge-engaging portion of said first web.

References Cited UNITED STATES PATENTS 2,627,153 2/ 1953 Stencil. 3,017,795 1/1962 Joa 53l80 X 3,088,256 5/1963 Brown 5328 3,234,705 2/1966 Schwartz 53-28 WILLIAM W. DYER, J R., Primary Examiner.

N. ABRAMS, Assistant Examiner.