US2629808A - Apparatus for sealing wrapping material - Google Patents

Description

Feb. 24, 1953 L. A. ULMSCHNEIDER APPARATUS FOR SEALING WRAPPING MATERIAL 2 SHEETSSHEET 2 Filed Nov. 15, 1950 IAMQENCE A. ULMSCHNEIDER lma entor (lttornegs Patented Feb. 24, 1953 APPARATUS FDR. SEALING WRAPPING MATERIAL Lawrence A. Ulmschneider, Rochester, N. Y., as-

signor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application November 15, 1950, Serial'No. 195,784

- This invention relates to sealing facing edges of wrapping material which may consist of a supportsuch as metal foil or paper having a thermoplastic coating on one side. Such Wrapping materials are well known and the thermoplastic may be of a type which can be sealed by bringing the thermoplastic faces together and heating, with or without pressure. One object of my invention is to provide a sealing mechanismby which two edges of wrapping material may be sealed together, preferably in a continuous operation,by moving the wrapping material and the sealing means relative to each other. Another object of my invention is to provide an apparatus for sealing which will satisfactorily seal wrapping material, even though the wrapping. material may be creased or bent so that it may not lie substantially in a plane. A still further object of my invention isto provide a sealing means in which a minimum amount of pressure is applied to the wrapping material as it passes between the heating elements of the sealing mechanism. A further object of my invention is to provide a sealing mechanism which will contact all of that part of the edges of the material which is to be sealed together. Other objects will appear from the following specification, the novel features being particularly pointed out in the claims at the end thereof. Coming now to the drawings wherein like reference characters denote like parts throughout:

Fig. 1 is an end elevation of a sealing mechanism constructed in accordance with and embodying a preferred form of my invention;

Fig. 2 isa perspective view with certain parts omitted for clearness;

Fig. 3 isa top plan view of the sealing mechanism shown-in the preceding figures;

Fig. l is a fragmentary detail on a somewhat exaggerated scale illustrating a feature of my invention; and

Fig. 5 is asection taken online 5--5 of Fig. 4.

The invention consists broadly in an apparatus for satisfactorily sealing two edges of wrapping material by heating plastic facing surfaces of the material to a point at which they will fuse together and adhere while holding the edges of said material lightly together, preferably passing the edges through a serpentine or wavy path. It has been found that after wrapping various articles, the edges of the wrapping material do not liein a plane, but, to the contrary, they may have small folds, wrinkles, indentations, and the like, which prevent. the'two surfacesfrorn lying smoothly; in; contact. Heretofore, sealing 6 Claims. (Cl. 219-19) apparatus has ordinarily applied considerable pressure and has endeavored to iron out the irregularities in the surface of the wrapping material by smoothing devices, rollers, or the like. but such devices have not been entirely satisfactory because very often more pressure had to be applied to the material than the material could stand. In a continuous operation, such as may be carried out with my sealing device, it is preferable to move the material to be sealed at arelatively high rate of speed, such as, for instance, 40 feet per minute, andif varying pressure, or if a relatively heavy pressure, is applied to the edges, it is very difficult to bring the adhesive surfaces smoothly and fully into contact. My improved method consists in heating the material edges while moving. these edges through a slightly wavy path, since I have found that such a path, by bending the material back and forth even though slightly, tends to smooth out the material, since it will normally lieflat transversely of each bend, so that by applying comparatively light pressure, the surfaces, if not in contact in passing around one bend, will be in contact in passing around another, and by raising the temperature to the desired degree they may be caused to adhere. At the same time the pressure actually applied tothe wrapping material is so light that-some up-and-down and even sideways motion is permitted between the edges of the material to be joined and the heating elements. It has been found in practice that extremely light pressure is desirable. I have also found that the serpentine path can be en-, tirely satisfactory even though the deflection of this path from a straight line is extremely slight. Itis tobe understood that the embodiment shown in the drawings isonly one preferred embodiment for. accomplishing the desired result, and that other embodiments will readily suggest themselves to those skilled in. the art.

As indicated in the drawings, the preferred embodiment consists of a sealing unit consisting of two sections, I and 2; these sections being hinged together at 3. Section I is carried by a support t which may be. attached as by bolts 5 toaframe 6 of a machine, of which this sealing unit may form a part, andsection 2 in its operative position shown in Fig. 1 may be'latched on a post i attached as by bolts 8 to the frame 5. The: outer end S ofsection 2 may be latched by latch member is pivotally mounted at H to the post iand having a spring l2 holding the latch in-its'operative position, or against the. stop pin it. On the underneathsideofplate l. there is a positioning and sealing element l5 which may be fixedly mounted to part i in any suitable manner. The sealing element l5 may consist of a block of insulating material provided with two forwardly extending arms |6 which are mounted on the ends and, in this instance, three forwardly extending fingers each of which carries an insulating pin, such as Pyrex glass 3, which are preferably mounted as shown in Fig. 3 in apertures IS in which they may slide, being pressed outwardly by light springs 20. Set screws 29a are provided for varying the tension on the springs. The forwardly extending arms I6 slidably support the heating elements 2| which may be conveniently made from a flexible Nichrome band, or other resistance material. This band has one end 22 immovably anchored on one side and the other end 23 attached to a slide member 24 so that a spring 25 anchored on member IE on a set screw 26 may be used to take up the slack in the band 2| and provide a predetermined tension thereon. A nut 2'! permits this tension to be adjusted as desired. Thus, the flexible band 2| is normally drawn taut by the spring 25, but under light pressure, and the pressure of the springs 20 is insufficient to overcome spring 25. If only one wrapping material is to be used, this adjustment may be omitted and both ends of the spring band may be immovably anchored.

A terminal 28 is provided on one end of the flexible band 2| and a terminal 29 is also attached to the other end of the band.

The hinged section 2 carries a similar heating element 30, this element including rounded arms 3| about which a flexible resistance band 32 passes; one end 33 of this band being attached to a fixed terminal 34 and the other end 35 being attached to a slidable terminal 36 drawn by a spring 31 toward the outside of the sealing element 30, thereby stretching the band 32 taut about the rounded ends 3| and under light pressure. A bolt 38 and nut 39 permits adjustment of this tension. The sealing member 39 likewise has fingers 40, two being shown in this case, projecting toward the fingers l1 but preferably lying midway between them. These fingers have slideways for insulating posts 41 which are pressed outwardly by light springs 42, the tension of which may be adjusted by set screws 43. When the two heating elements are in the position shown in Fig. 2, the Nichrome bands or heating elements 2| and 32 present a wavy path which is shown in exaggerated form in Fig. 4. In this figure, a pair of posts i8 and one post 4| are illustrated as contacting with the Nichrome bands to deflect these bands from a straight path by a distance D between each pair of posts. This distance is much less than i1lustrated, and it has been found that a deflection of, roughly, :s of an inch is suitable for many materials, although, obviously, this distance may be increased or decreased by the setting of the springs 25, 2D, 31, and 42 to properly take care of the particular wrapping material used.

I have found that a wrapping material consisting of an aluminum foil of .001 thickness may be coated on one side with a thin layer of 22 lb. plasticized paper of about .001" in thickness and the opposite side of the material may support a polyethylene layer of .0015" as the heatsealing layer. With such material, I have found that a wavy path in which the material is deflected between a 32nd and a 16th of an inch is entirely satisfactory, and, as the edges of the material are moved back and forth through the serpentine path, the entire edges of the material to be sealed are caused first to contact and then to adhere, even though the pressure is so light that it permits relative movement between the material and sealing bands to occur, at least to some slight degree, both transversely and longitudinally of the seam.

In Fig. 2, I have shown the sealing step being carried out to seal a tubular member which may be folded into rectangular shape by any of the well-known machines for accomplishing this result, such as in the manner shown in U. S. Patent No. 1,313,234, John G. Jones, Wrapping Process, August 12, 1919. Fig. 2 shows a tubular member T has been folded up with outwardly extending flanges F, it being understood that the heat-sealing plastic layer, such as polyethylene, lies inside of the flanges; these layers being brought into contact at C just before the tubular member bearing the wrapped articles A reaches the sealing position.

In the present instance, this tubular member T is moved along a table 5|] by means of a. pair of endless belts 5| and 52. These belts pass over pairs of rollers 53 and 54, best shown in Fig. 3, which are driven by any suitable mechanism at the same speed and in the direction shown by the arrows. The runs of the belt between the two sets of rollers (only one set being shown in Fig. 3) engage the side walls S of the folded tube T and move it at the desired speed. As the contacting upstanding flanges C reach the sealing elements l5 and 30, they engage the resilient Nichrome bands 2| and 32, and the upstanding flanges or edges of the material C are smoothed into contact as the edges C weave slightly back and forth in passing through the machine. By slightly bending the edges transversely of their direction of travel, any irregularities or departures from a plane are caused to smooth out. even though only light pressure is applied. As the plastic becomes warm, it softens and the two softened layers may move slightly relative to each other and into good adherence so that as the contacting edges C leave the heating units, and the temperature of the heating elements is no longer present, the flanges adhere over that entire surface which is heated by the flexible bands. It has been found that such a seam is extremely tenacious and is completely waterproof, and, in addition, the seam may be made while the tube is traveling at a relatively high speed. In addition, I have found no tearing of the wrapping material in passing through this sealing device because of the light pressure which is applied, and because some movement of the contacting flanges C relative to the bands is permitted at all times.

It is, of course, not necessary that the material should move relative to the sealing means since comparatively short seals can obviously be made by moving the sealing member relative to the contacting surfaces of the wrapping material, and, of course, this method can be carried out in many ways. The distance between the members l8 and 4| and their spacing from each other does not appear to beat all critical and may be varied widely, and, in fact, all that is necessary is to deflect the resistance sealing bands from a straight path even to a slight degree. This, by causing the contacting edges to move back and forth in passing between the bands, smooths the material so the heat sealing plastic layers arebrought intointimate contact while heated so that they firmly adhere.

As will be noticed in Fig. 2, where a circuit is schematically shown, the heating elements 2| and 32 are heated from a source of current 606I through a conductor 62, rheostat B3, and conductor 64 leading to terminal 34, through the Nichrome band 32, to terminal 35, through conductor 65, terminal 29, Nichrome band 2!, and conductor 66. The temperature may be adjusted by the rheostat 63. I have found that with polyethylene and the wrapping material described above, a temperature of from 310 to 315 degrees produces entirely satisfactory results. quite a little in accordance with the wrapping material as in cases where the paper layer is thicker, a higher heat may be required, and if the paper layer is omitted, the heat may be slightly reduced. If the aluminum is thicker, a much higher heat due to the conductivity of the aluminum, is required. Different materials may therefore require heat adjustments. Where it is not so essential to provide complete waterproofing, material may be used which is less expensive and which may omit, for instance, the metal foil layer which, however, is preferable for a moistureproof package. Whether the material is paper, foil, or foil and paper, the method is the same in that the contacting edge surfaces to be joined are passed through a wavy path so as to flatten out and bring into contact small irregularities in the surface of the sheet to be contacted.

While I have shown a preferred form of my invention, and one which is well adapted for achieving the objects of this invention, it is to be understood that this is not to be considered in a limiting sense. Various possible embodiments can readily be made and will suggest themselves to those skilled in the art, so that embodiments disclosed herein should be taken as illustrative and not in a limiting sense.

Having thus described my invention, what I claim is new and desire to secure by Letters Patent of the United States is:

1. Apparatus for sealing areas of wrapping material comprising a support having a heat and pressure sensitive plastic on one side, said apparatus including a pair of elongated heating elements, means for heating said elements to a predetermined degree, a series of locating devices for the pair of heating elements to hold them toward each other and with the heating elements lying in a serpentine path, and means for moving two layers of the wrapping material with the heat and pressure sensitive layers in contact relative to the heating elements to unite The necessary temperature may vary 6 the two layers of wrapping material over the heated areas.

2. Apparatus for sealing in accordance with claim 1 characterized in that the heating elements are flexible resistance bands passing back and forth between staggered supporting members and held thereby in a serpentine path.

3. Apparatus for sealing in accordance with claim 1 characterized in that the heating elements are flexible resistance bands and spaced supports for the bands comprising springpressed plugs on both sides of the bands for resiliently holding the bands in a wavy path.

4. Apparatus for sealing areas of wrapping material comprising a support having a heat and ferently from the means on the other side so that the bands may present a wavy path through which the areas of the wrapping may be moved to heat-seal the facing thermoplastic layers thereof.

5. The apparatus defined in claim 4 characterized in that at least one support carrying a spring band is spring-pressed toward the other support carrying a spring band.

6. The apparatus defined in claim 4 characterized in that at least one support carrying a spring band is spring-pressed toward the other support carrying a spring band, and in which at least one support is hingeclly mounted to move one spring band to and from the other spring band.

LAWRENCE A. ULMISCHNEIDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,291,807 Hart, Jr. Aug. 4, 1942 2,439,918 Auxier et al Apr. 20, 1948 2,457,498 Russell et a1 Dec. 28, 1948 2,469,972 Lowry May 10, 1949 2,478,132 Schade Aug. 2, 1949 2,491,048 Jenkins Dec. 13, 1949 2,517,672 Jenkins Aug. 8, 1950 2,544,133 Carlson Mar. 6, 1951 2,556,008 Spalding June 5, 1951

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