Draw-cord Bags

Abstract

A method and apparatus for producing draw-cord bags wherein a folded sheet of synthetic material is fed step-wise through an apparatus comprising means for folding the open edges of the sheet back upon themselves and producing a pair of seams, means for punching apertures therein, means for threading at least one draw-cord through each seam and means for producing and applying connectors to the ends of said draw-cords to produce an annular draw-cord, further means being provided for producing welded side edges for said bags and separating same from said sheet. The invention also relates to a draw-cord bag produced by the method and apparatus.

Description

This invention relates to bags having draw-cords and to a method for the production thereof, from a weldable sheet of synthetic material having, at the opening of the bag, a turned seam for the reception of at least one annular draw-cord, and preferably two draw-cords arranged at a distance from one another, in which method the edges provided for the turned seam are stamped out with holes for the passage of the draw-cord, the draw-cord being inserted and the pieces thereof connected together. The seam is secured on the body of the bag and the bag is closed on its longitudinal sides and separated. The invention also concerns a device for carrying out the method, and a bag having a draw-cord produced therewith.

In a known method for the mechanical production of bags having draw-cords, a folded piece of synthetic sheet material is provided and welded along the folded edges of the bag lying flat on one another and provided for the seam. Apertures are stamped out, before or after the turning of the seam, for the passage of the cords. Each seam is subsequently secured along its lower edge onto the body of the bag and finally the bag as a whole is closed along one side over the whole depth of the bag and separated as a bag. The cord is inserted before the seaming of the bag. If the cord consists of weldable synthetic material, then on separation and closure of the sides of the bag the cord will at the time of welding be welded into a draw-cord enclosed by the sides of the bag. A disadvantage with a cord consisting of weldable synthetic material is that it is too soft and flexible and is not sufficiently strong. If however some other material is used for the cord, it is then necessary to draw out the cord afterwards to a sufficient length to form a knot. Special devices are used for this and additional space is necessary for the installation of a knotter.

In another known method only one part of the draw-cord is inserted in each side of the bag. The two parts of the draw-cord of a bag are, after the formation of a loop after pulling out the cord to lengthen the ends projecting from apertures in the bag, collected together into a single annular draw-cord by means of clamps. The ends of the draw-cord and the clamps project beyond the ends of the bag. The known bag can only be closed by one sided drawing of the draw-cord from the bag.

The object of the invention is to allow the free selection of the type of connection of the draw-cord not subsequently drawn out, more particularly of the type first mentioned. This object is achieved according to the invention in that two of the pieces of draw-cord projecting into and out of the holes of the bag are formed into an annular draw-cord by means of a connector, particularly one produced from plastics by an injection moulding method. Due to the use of a connector the selection of the material for the draw-cord remains free. This does not need to be drawn after the production of the bag because its length does not exceed the double width of the bag and one part thereof corresponds to the width of the bag. The material for the connector can be optionally selected and its suitability for welding is not a factor to be taken into consideration. The connector can be designed as desired within wide limits. In an injection moulding method using plastics, mechanical devices for the feed of pre-fabricated connectors into the correct position and the connecting thereof to the parts of the draw-cord can be omitted. Marks, for example Trade Marks can be simply applied to the connectors.

The invention further relates to an apparatus for carrying out the method and which includes means for turning the edges provided for the seam, means for the production of holes for the projection of the draw-cord from the bag, means for the insertion of the draw-cord into the seam, means for securing the seam to the bag, and means for the closure of the bag as well as for the separation thereof along its longitudinal side. The apparatus according to the invention is characterized by a moulding device, which connects the parts of a draw-cord belonging to an annular draw-cord into a closed draw-cord by the application of a connector, made from a mouldable material, particularly plastics, produced in a mould, while retaining the original position of the draw-cord in the bag at each side thereof, said device at the same time separating the cords of two adjacent bags from one another. By the introduction of a material prefabricated by the moulding method, two parts of a draw-cord are in each case connected to one another in a satisfactory manner.

Space is saved for the locating of the production mould in an advantageous manner, in that the moulds for the connectors are arranged immediately adjacent each other and serve for the production of connectors for two adjacent bags and in that between the moulds for the connectors for a pair of bags a knife is provided. Thus the width of the mould is independent of the width of the bag and does not need to be altered for the production of bags of different widths.

The invention also concerns a draw-cord bag, produced by the method according to the invention and by means of the apparatus according to the invention. The draw-cord bag has at least one annular draw-cord and preferably two arranged at a distance from one another within the seam, the half length of which corresponds to the width of the bag and which projects through the cut-outs in the bag and is characterized in that at each side of the bag a connector of mouldable material, particularly plastics, connects two parts into one draw-cord, which lies within the extension of width of the bag.

The invention further provides that the connectors are of varied design, connectors arranged cross-wise always being of the same design. The attachment points in the draw-cords are therefor made recognizable.

Further advantageous features of the invention will become apparent from the following description in conjunction with the claims and the accompanying drawing wherein an apparatus for carrying out the method and an article produced according to the method are shown schematically.

FIG. 1 is a top plan view of the apparatus for producing a bag in accordance with the invention;

FIG. 2 is a side elevation of the apparatus of FIG. 1;

FIG. 3 is a sectional view taken along the line III--III in FIG. 1 on a larger scale; and

FIG. 4 illustrates a draw-cord bag made in accordance with the invention.

A double layered sheet 2 which is supplied from a roller 1, is closed on one side 3 and open on the other side 4, in which latter position there are two edges lying on top of one another. The chain-dotted lines 5 in FIG. 1 indicate the longitudinal seam for each bag.

On the side 4 a seaming device 6 is arranged downstream of the roller 1 and is followed by a hole stamping device 7. Two cords, forming as a two-part draw-cord, are to be passed into the seam 10 formed by the seaming device 6, from four supply bobbins 8 by means of a feed device 9. A pair of conveyor rollers 11 arranged downstream of the feed device 9 serves to draw the cords from the bobbins 8.

A welding device 12 has a welding rib 13, corresponding to at least the width of a bag, for the production of the welds closing the seam 10.

A connecting device 15 serves for the production of connectors 16 and 17 for the parts 18 of the draw-cord, which correspond in length to the width of a bag. A pair of conveyor rollers 20 is arranged upstream of a welding device 19 for the production of a separating weld seam, and a conveyor device 21 for the conveyance of the finished bag is arranged downstream thereof. The two pairs of conveyor rollers 11 and 20 are driven at the same speed. The conveyor device 21 is designed as a belt conveyor which has narrow conveyor belts running around rollers.

The connecting device 15 is, as shown in FIG. 3, designed as an injection moulding device for the injection of injectable plastic and has a lower mold 22 and an upper mold 23, each of which have four recesses spaced in the form of a square for the production of the connectors 16 and 17. These connectors each being of the same design are arranged cross-wise. Four pressure pistons 24 are adapted to be operated by means of a work cylinder 25 for the simultaneous production of four connectors 16, 17. The material is fed from the side in the form of rods 26 and converted within the upper mold into a state suitable for injecting by means of a heating device (not shown). The part of the mold coming in contact with the sheet, is heat insulated, as indicated in chain-dotted lines, against the part of the mold lying thereabove, and cooled in the same manner as the lower mold 22, so that when the injection mold is pressed together, the sheet cannot adhere thereto. To separate the parts of the draw-cord from the stock rollers 8 a knife 27 is mounted on the upper mold whose cutting edge co-operates with the lower mold 22.

An extrusion device into which granulated material is fed may be substituted for injection molding device. Also, instead of plastics, some other injectable material may be used which serves for the connection of two cord parts.

For the production of draw-cord bags the sheet 2 is incrementally unwound from the roller 1, for which purpose the pairs of conveyor rollers 11 and 20 are driven at the same incremental speed and at the same peripheral speed. Should it be necessary additional devices for driving the sheet may be provided. The edges 4 are turned outwardly or inwardly in the seaming device 6 and form open seams 10. Oblong holes are stamped into the sheets lying above one another by means of the hole stamping device 7, said holes forming cut-outs 28 in the finished draw-cord bag 29. Two cords spaced at a distance from one another are laid by means of the feed device over the open sides of the seam and conveyed by means of the conveyor rollers 11. The welded seam 14 is then produced by means of the welding device 12.

The device 15 serves to separate parts of the draw-cord, in lengths corresponding to the width of a bag, from the bobbins 8. The device 15 also serves for the connection, for each bag, of two draw-cord parts 18 from two seams 10 lying above one another into an annular draw-cord by means of the connectors 16 and 17 produced from plastics in the injection moulding method, the parts 18 of the draw-cord being, for each bag, laid onto the seams 10 so that sufficient distance is provided between the two draw-cords for the production of the connectors 16, 17.

A separating welded seam is produced in the welding device 19, and the finished bags are drawn away by the conveyor device 21 and stacked.

The connectors 16 and 17 are of different sizes and shapes in order to identify clearly the contact positions on the draw-cords. The component devices of the apparatus save room on laying out and are so designed that they can be dismounted from and re-mounted in the machine. Due to this different bags can be produced on one apparatus for the production of bags without a great deal of work being involved in conversion. The bags are preferably produced with two annular draw-cords arranged at a distance from one another.

The production of the connectors takes place very rapidly so that a large output of bags from the apparatus is possible. The connectors form a positive connection between the parts 18 of the draw-cord so that these parts are not separated from one another even by rough usage. During the production of the connectors 16, 17 various marks, for example Trade Marks may be applied thereon.

The apparatus, being formed from individual components or additional appliances does not require much maintenance, can be interchanged in a simple manner and is easy to operate so that a saving in operators is obtained when draw-cord bags are produced with connectors which hold firmly.

Claims

I claim:

1. An apparatus for the production of draw-cord bags from a weldable plastic sheet having at the opening of each bag a turned seam for the reception of at least one draw-cord, which apparatus has means for the turning of the edges of said sheet for producing said turned seam, means for the production of holes through which the draw-cord may extend, means for the introduction of the draw-cord into the seam, means for securing the seam onto the body of the bag and for the closure of the bag, as well as for the separation thereof along its longitudinal sides characterized by a device which connects parts of the draw-cord by the application of connectors produced in a mold from moldable material while retaining the original position of the draw-cord in the bag, said parts being connected at each side of the bag into a closed draw-cord, said device simultaneously separating the cords of two adjacent bags from one another.

2. An apparatus according to claim 1 characterized in that, the mold has individual molds for the production of four connectors and in that the individual molds arranged cross-wise are each alike in pairs but are of different design from other pairs of molds.

3. An apparatus according to claim 2, characterized in that, the molds are arranged adjacent one another and serve for the production of connectors of two adjacent bags and in that a knife is provided between the molds, for two bags.

4. A draw-cord bag having two draw-cords arranged at a distance from one another in the seam, the half-length of which cords corresponds substantially to the width of the bag and which projects through a cut-out in the bag, characterized in that, at each side of the bag, a connector of moldable material is secured near each end of each draw-cord for connecting two parts of each draw-cord into annular draw-cords, which lie within the extension in width of the bag, one of said connectors near one end of one of said draw-cords being of a larger dimension at one side of the bag as compared to the dimension of the other of said connectors near the opposite end thereof, and one of said connectors near one end of the other of said draw-cords being of a larger dimension at the opposite side of the bag as compared to the dimension of the other of said connectors near the opposite end thereof.

5. A method for the production of draw-cord bags from a weldable plastic sheet, the opening of each bag having turned seams for the reception of a pair of annular draw-cords, comprising, turning the edges of each bag opening to provide the seam, stamping out holes in each bag for passage of the draw-cords, placing the draw-cords spaced longitudinally from one another within the turned edges so that opposite ends of each cord project outwardly of each bag through said holes, seaming the edges of each bag together, closing the edges of the seam and the longitudinal edges of each bag and thereafter separating the bags from the sheet, forming connectors by injection molding on each of said draw-cord ends which project outwardly of each bag through said holes with adjacent pairs of said connectors for each adjacent bag being spaced from one another, and separating the cords of two adjacent bags from one another during the connector forming step.