US2791161A - Method of and device for making letter envelopes - Google Patents

Description

W. DOETSCH May 7, 1957 l METHOD OF AND DEVICE FOR MAKING LETTER ENVELOPES Filed Sept. 8. 1953 3 Sheejts-Sheet 1 1 May 7, 1957 w. DOETSCH 2,791,161

METHOD OF' AND DEVICE'FOR MAKING LETTER ENVELOPES Filed Sept. 8, 1953 3 Sheets-Sheet 2 mhh I ,igmlu L 1111 May 7, *1957 Filed Sept. 8. 1955 W. DOETSCH METHOD OF AND DEVICE FOR MAKING LETTER ENVELOPES 3 Sheets-Sheet 3 nite METHOD F AND DEVICE FOR MAKING LETTER ENvELoPEs The present invention relates to envelopes and more particularly concerns a method of and a machine for making envelopes of the tive-seal or the like shape or size -according to which selectively either the respective uppermost or the respective lowermost sheet of a stack of sheets is withdrawn with or without simultaneous formation of a fold. This method as heretofore practiced has the drawback that a spacing between the smallest and largest size to be worked is unavoidable so that the output per time unit is relatively limited. Moreover the heretoyfore known method does not make it possible to work the envelopes in such close succession that there is practically an uninterrupted track of closely succeeding envelopes passing by the respective treatment stations.

IIt is, therefore, an object of this invention to provide a method of and machine for making envelopes which will overcome the above ment-ioned drawbacks.

`Numerous and various methods have been applied heretofore` for making envelopes with gummed closure ilaps. Iny this connection, there are used machines which work from a sheet, and there are also machines which work from a r-oll. With regard to the folding and pasting of the letter envelopes it may be mentioned that with the said two types of machines, the said working steps are carried out after the paper has been cut into blanks of predetermined size. With both manufacturing methods it is known prior, as well as after the folding step, to provide the blanks with adhesive or the like for the later pasting of the closure flaps. In order to dry said gummed closure flaps, it was heretofore necessary to employ a rather long drying path; in particular with high speed machines having high output, it was necessary in view of the high paper speed to increase the drying path more and more. This in turn required larger and larger desi-gus of the drying devices in the shape of 1conveyor belts or conveyor chains. On the other hand, with these long drying paths especially when using conveyor belts, shifting of the work pieces frequently occurred which harmfully affected the folding process.

It is,therefore, another objectV of this invention to provide a method of and machine for making envelopes with gummed closure aps which will reduce to a minimumthe drying period for the adhesive applied to the paper surface so that, even with a maximum output and a maximum paper speed, only a very short drying path will be required. Y

It is still another object of this invention t-o provide a method of and machine for making envelopes from precut sheets of paper which, while being rather simple, is high-ly economical, eicient and easily to be realized.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings in which: v

Fig. 1 diagrammatically illustrates the principle of a first method according to the invention.

Fig. 2 diagrammatically illustrates a method which is somewhat modified over that of Fig. 1.

States Patent mice what modified over that of Fig. 3 for carrying out the method according to Fig. 2.

Fig. 8 is a plan view of the side flap folding devices.

General arrangement The essence of the invention consists `in that the blanks cut to a predetermined size and withdrawn from a stack of blanks are passed by the treatment stations in au overlapping or fanned out manner. These blanks or work pieces, while being in the said arrangement, have, according to the new method, applied the adhesive or gum for the later pasting of the closure flaps, whereupon after eifected drying, the folding, turning over and gumming of the aps extending transverse to and in the conveying direction, is effected in such a manner that an uninterrupted paper train is formed, the wor-k pieces of which subsequently by the turning-over step and closing of the closure flaps are separated into individual finished work pieces.

The employment of the method, according to the I present invention, i. e. the arrangement of a staggered paper layer according to mass production methods for purposes of folding and pasting has considerable advantages over the heretofore known methods. According to the presen-t invention, depending on the width of the staggering, simultaneously a more or less great number of work pieces can be subjected to the folding and gumming process. With reference to the length of the blanks in the conveying direction, according to the present invention, the heretofore customary inter-spaces between the smallest and largest sizes to be Worked, are completely eliminated since the Work pieces are subjected to the folding step in an uninterrupted sequence. This results in a considerable increase of the output without increasing and accelerating the working tools while the paper blanks may move at a minimum speed. vAccording to the present invention, a conveyor is provided for conveying the work pieces which conveyor has its outer surfaces provided with an elastic adhesion-creating mass. As support for said conveyor, a slide rai-l or guiding rail may be provided which presses the work pieces carried by said conveyor against the latter so that the work pieces will be passed through t-he machine in a safe manner without changing their position relative to said conveyor.

The present invention furthermore comprises a method of depositing and drying the paste or gum on the closure v aps. According to this new method, the paper sheets to be provided with paste or gum at the various closure flaps, are prior to the application of such paste or gum, dried in any convenient manner so that the humidity contained in the paper sheets will be evaporated. This method makes it possible that immediately following the evaporation process, paste or gum can be applied to said paper sheets and said paste or gum will immediately harden on the paper surface and due to the heat radiation of the heated paper will immediately and completely dry. The advance in the art as brought about by the present invention consists in that, even with a maximum output and at a maximum paper speed, only a very short drying path will be required for the drying period.

Structural arrangement Referring now to the drawings and Figs. l and 3 thereof in particular, the respective lowermost sheet or blank patented May 7, 1951 whenthe withdrawal is effected, first ,the closure ap 51 isfolded over so that the latter willrest on what will `later form the address side of the envelope. The thus staggered blanks overlapping each other and provided with a turned over closure flap are successively passed upon .a pair of belts or bands 6, 7 (see Figs. 3 and 6). The said belts or bands carried by pulleys 31, 32 carry the echeloned or` overlappingwork pieces 4 incooperation with the. guiding rails4 8, 9 during the gumming and dryingv Between said conveyor belts or bands 6, 7' (Figs. 3 and 6),` there is provided a heating chamber 10' process.

in which are arranged heating tubes 11.- When the train of overlapping work pieces 4, by means of the Conveyor belts 6, 7, is passed over the heating chamber 10, the said echeloned or overlapping work pieces are, according to the present invention, heated to such an extent that the gum or paste 12 subsequently applied to said work pieces bya gumming device 13 will immediately harden on the paper surface and will, due to the heat radiation of the train of work pieces itself, completely dry. On its further way over the heating chamber 10, the work pieces 4 are .passed onto the conveyor belt 14; The conveyor belt 14 is, according to the present invention, designed similar to the conveyor belts 6, 7 and has its outer surface provided'withv an elastic adhesion-creating mass as, for instance, rough rubber, sponge rubber or cellulose sponge.

When the work pieces 4 enter between the conveyor belt' 14 and the guiding rail 15, the work pieces are by means of the guiding rail 15T pressed against the conveyor beltV 14 and are carried through the machine While the work pieces slide `along said guiding rail 15. Laterally of the conveyorbelt 14, there are arranged folding knives 16 and folding loops `17. While the train or overlapping work pieces f4 is passed through the folding knives 16 and folding loops 17, those two flap portions18 ofeachV work piece 4which stick out from the central portion of the workpiece in a direction transverse to the conveying direction, are foldedover so that an `uninterrupted train is formed made up of the individual'work pieces cachot which has already-three folds. pieces leaves the conveyor belt 14 and the guiding rail 15,` it entersl between the delivery rollers 19, 20. Onthe upper roller20 there are provided gum or pasteapplying means which receive the paste or gum from `a device 21 arranged thereabove for pasting the bottom ilap 24.

As soon as the leading folding edge 22'passes below the contact point of the two delivery rollers 19,' 29, the respective leading work piece 25 istat an increased speed separated from the entering train of-work pieces because the rollers V19, 20 have a higher speed than the belt .14. Simultaneously the work piece is provided with the paste orgum 23 for pasting thebottom ap 24. The two delivery rollers 19,` 20 feed the work piece 25 provided with three folds into the folding pocket 26 so that while the direction of movement is being reversed, the bottom flap 24 is folded over and is pasted to thetwo lateral flaps 13. Whcn the work piece passes through the rollers 19, Z0, the closure hap 5 which was folded over during the with drawal of the respective sheet from the pile of sheets 1. is caught by the suction roller 27, is opened and is passed between the `rollers 27 and 2S. The roller 27 feeds the now leading closure flap. 5 through guiding means 30 while the work piece iscaught by the lower suction roller 28 directly behind the folding edge 29 and by the guide 30is started upwhile the closure flap 5 is being closed.

Accordingutothefmcthod illustratedin Fig. 2, thewitlr When the train of work drawal and folding of the work pieces is effected in a manner similar to that of the method according to Fig. 1. Therefore, the same reference numerals as in Fig. 1 have been employed in Fig. 7 illustrating the machine for carrying out the method of Fig. 2. However, the reference numerals employed in Fig. 7 and designating parts corresponding to those of Fig. 3 are provided with the same reference numerals as employed in Fig. 3 with the addition of the sutix 11. As will be seen from Figs. 2 and 7, the method and arrangement respectively illustrated therein differ from that of Figs. l and 3 in that the paste or gum is applied to the closure flaps subsequent to the folding step. According to Figs. 2 and 7, an envelope is made by subjecting the blanks directly to the folding process while the work pieces, when they are withdrawn from the stack 1a, are simultaneously staggered or tanned out. The preliminary breaking, the folding over and the gummingis carried out in the same succession as referred to in Fig. l. The thus-formed train is then divided up into individual pieces in `such a manner that the individual work piccesare staggered with regard to each other in an overlapping manner and in this position are conveyed together.

The thus-formed paper track is, according tothe present invention, heated by any convenient means such as the heating drum 10a .(Fig. 7) whereupon the paste or gum is-applied to the'closure aps. has been completed, the closure flaps are closed while thc workipieces are collected andstacked up toa stack.

As for as.` the principleof the invention is concerned, it is immaterial whether the pre-cut sheets or blanks are withdrawn from the-stack of sheets Withor without the simultaneous formation of a fold. The invention may also be applied where the withdrawal of the sheets is effected with open unfolded sheets.

It yis furthermoreto be understood that the present invention-is, 'by' noimeans, limited to the particular methods and devices described in the preceding specification with regard to the'accompanying drawings, but also cornprises any modifications-within the scope of the appended claims.`

What I claim is:

1. A- method of making envelopes from sheets arranged in a stack `andcut to size with corner portions thereof cut to respectively form the side, bottom and closure flaps, Which'includes the steps of: withdrawing fromsaidstackvina continuous process one sheet after another while advancing said sheets in superimposed but staggered'position so that said sheets overlap each other in the direction of advancement ofsaid sheets; heating saidsheets while they are thus being advanced; applying `adhesive 'to that portion of said heated sheets which will form Athe-closure flap; drying the thus applied adhesive; subsequently folding at least those portions of 'said sheets which form the side-flapsof the envelopes while simultaneously advancing the thus folded sheets in superimposed ,and overlapping*l condition; segregating the" individual folded sheets from 'each other; applying adhesive to margirial portions ofthe` side flaps of said segregated and folded sheets; folding over the bottom flaps of said segregated-andA folded sheets while pressing the same against said side flaps; and subsequently folding the closure flaps so that they will lie on the back side of the envelopes.

2. A method of making .envelopes from sheets arranged in a stackand cut to size with corner` portions thereof cutto respectively form the side, bottom and closure aps, which includes the steps of: withdrawing from said stack in `a continuous process one sheet after another whileadvancing said sheets in superimposed but staggered position so 'that said sheets overlap cach other in the direction of advancement of said sheets while thus advancing'said sheets folding at least those sheet portions which form the side flaps of the envelopes to be made; heating the thus-folded sheets; applying adhesive to that portion of said sheets which will form the closure flaps; drying After the drying process` the thus-applied adhesive; applying additional adhesive t0 those porti-ons of said sheets which will form the side and bottom portion of the envelopes; and pressing said side and bottom flaps against each other so as to connect the same together.

3. An arrangement for making envelopes, which -includes a rotatable drum, heating means arranged within said drum for heating the same, iirst conveying means provided with elastic gripping means and arranged to convey in overlapped relationship pre-cut paper sheets to be made into envelopes over said drum over a predetermined arc thereof for heating said sheets, means arranged `adjacent the periphery of said drum intermediate the end points of said arc and a considerable distan-ce away from the starting point of said arc for applying adhesive means to that portion of each sheet passing over said drum which Will form the closure portion of the respective envelope, second conveying means adjacent said drum for receiving in overlapped relationship the sheets passed over ysaid arc of said drum, folding means arranged adjacent to and laterally of said second conveying means for folding portions of said sheets while in said overlapped relationship into side flaps of the respective envelope, roller means arranged adjacent that end of said second conveying means which is remote from said drum to receive the folded sheets from said second conveying means, sa-id roller means having a rotational speed greater than the speed 4of said second conveying means to thereby segregate the individual folded sheets from each other, paste-applying means adjacent said roller means for applying paste to that portion of said sheets which will form the bottom flap of the respective envelope, and folding means for folding said bott-om flap and fastening the same to `sa-id side ilaps.

References Cited in the le of this patent UNITED STATES PATENTS 232,777 Sutton Sept. 28, 1880 890,114 Wing .lune 9, 1908 1,557,534 Swab Oct. 13, 1925 1,807,867 Novick June 2, 1931 2,354,351 Schuetz July 25, 1944 2,359,825 Campbell Oct. 10, 1944 2,568,629 Heywood Sept. 18, 1951 FOREGN PATENTS 626,262 Germany Feb. 22, 1936

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