|Publication number||US3688650 A|
|Publication date||Sep 5, 1972|
|Filing date||Aug 26, 1969|
|Priority date||Aug 26, 1968|
|Also published as||DE1943306A1|
|Publication number||US 3688650 A, US 3688650A, US-A-3688650, US3688650 A, US3688650A|
|Inventors||Jan Roelof Jochem De Vries|
|Original Assignee||Wavin Bv|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (8), Classifications (24)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent de Vries 3,688,650 i451 Sept. 5, 1972  METHOD FOR MANUFACTURING A BLOCK BAG Jan Roelof Jochem de Vries, Hardenberg, Netherlands Assignee: lndustriele Ondememing Wavin N.V., Zwalle, Netherlands Filed: Aug. 26, 1969 Appl. No.: 853,624
US. Cl ..93/35 R, 93/8 VB, 229/62.5 Int. Cl. ..B3lb 49/04, 865d 31/14 Field of Search.....93/8 VB, 35; 229/625; 150/9 References Cited UNITED STATES PATENTS 2/1966 Gennerich et al. ..229/62.5 3/1966 Lissner ..93/8 X 2/1968 Shaw ..229/62.5 3/1969 Kasting et a1. ..229/62.5 X
Netherlands, ..6812161 FOREIGN PATENTS OR APPLICATIONS 961,222 6/1964 Great Britain ..229/62.5
Primary Examiner-Theron E. Condon Assistant Examiner-Neil Abrams Attorney-Irving M. Weiner ABSTRACT A method for manufacturing a block bag of thermoplastic material with at least one filling valve from a tubular foil part having bottom flaps and at least one comer flap forming the valve being longer than the bottom flaps, wherein the bottom flaps are folded around a heat isolating piece and the stack of foils forming the bottom are heatsealed together by applying heat from both sides of the stack.
The seals are obtained by spot welding, or formed as labyrinth seals. The end of the comer flap forming the valve may be stretched or subjected to a superficial incision, or creasing operation.
By incision, or removing-part of the corner flap forming the valve, a valve having a V form is obtained.
3 Claims, 13 Drawing Figures P'A'IENIEDsEP '91: 3,688,650
' sum a nr 6 I METHOD FOR MANUFACTURING A BLOCK BAGv The invention relates to a method for manufacturing a block bag with at least one filling valve. By making two longitudinal incisions from one end of a part of a thermoplastic tubular foil thus forming two corner flaps and two bottom flaps, folding inwards said corner flaps about diagonal lines extending between the end point of the incision and a point on the longitudinal edge of the tubular foil, folding the bottom flaps about a cross folding line, inserting a separating means, clamping said comer flaps and bottom flaps on each other and activating a sealing member such that longitudinal bottom seals and transverse bottom seals are produced by heatsealing together said two bottom flaps and one of said corner flaps with said bottom flaps.
Such a method is known, but the plastic bags obtained thereby do not meet the requirements, especially as far as the properties of quality of the sealed bottom and the closure are concerned. Moreover difficulties are often experienced on filling such bags by means of bag filling machines.
It is now an object of the invention to provide va method for manufacturing an improved bag.
Such a method is characterized according to the invention in that the starting point is a part of a thermoplastic tubular foil. At least one corner flap, constituting the valve, is longer in the longitudinal direction of the tubular foil than the bottom flaps. After the corner flaps have been folded inwards the bottom flaps are folded about a cross folding line extending substantially perpendicular to the longitudinal axis of the part of the tubular foil in the portion of the non-incised tubular foil part following after the point of inci- 51011.
By starting from a part of a tubular foil at least one of the corner flaps of which is longer, in the' longitudinal direction of the tubular foil, than the bottom flaps and folding about a folding line of the bottom flap, which is situated in the portion of the non-incised tubular foil part following after the end points of the incision, it is possible to obtain a very efficiently constructed bag which can be heatsealed in a minimum of operations, and which furthermore is very solid. This solidity results from the fact that, almost exclusively, a peeling load is applied to the seals on filling such bags. Y
In order to reduce to a minimum the process of welding the layers in the bottom on each other a triangular portion is removed from the tubular foil part at the end thereof and at the location of the line of incision between a bottom flap and a corner flap, preferably whilst forming slanting corner flap edges along the line of incision.
According to a very preferred embodiment said seals are producted by applying heat to the foil layers to be heatsealed from both sides of the superposed foil layers, that is from the side of the separating means and from the sealing member.
The invention is hereinafter clarified with reference to the drawing representing an embodiment for manufacturing a plastic bag according to the invention, various details of the invention being disclosed in the course of the description.
In the drawing:
FIG. 1 is a flattened part of a tubular foil used for manufacturing a bag;
FIG. 2 shows a perspective view of such a tubular foil P FIG. 3 represents a tubular foil p'art after the corner flaps have been unfolded;
.FIG. 4 represents an unfolded tubular foil part before introducing a separating means connected with a sealing member;
FIG. 5 shows a separating means with heatable parts disposed in the bottom portion of the bag;
FIG. 6 represents a bottom portion of the bag after the sealing member together with the separating means is disposed on the bottom to be formed;
FIG. 7 is a sealed bottom with bag, obtained according to the method of the invention;
FIG. 8 shows one embodiment of a pattern for cutting foil parts from a tubular foil;
FIG. 9 shows a preferred embodiment of a foil part out from a tubular foil utilizing the pattern shown in FIG. 8;
FIG. 10 is a flattened part of a tubular foil having two comerflaps of equal length; v
FIG. 11 shows a perspective view of the tubular foil parts of FIG. 10;
FIG. 12 represents the tubular foil part of FIG. 10
and 1 1 after the corner flaps have-been unfolded;
FIG. 13 represents a completely unfolded tubular part before introducing a-separating means.-
The FIGS. 1 and 2 represent a tubular foil part denoted by l which is provided with two longitudinal incisions 2 forming two comerflaps, a first cornerflap 5 and a second or other corner flap 5, and two bottom flaps 6 and 6. The first comer flap 5 is longer, in the longitudinal direction of the tubular foil, than the bottom flaps 6, 6', while the other corner flap 5' is shorter, in the longitudinal direction, than the bottom flap 6. The bottom flaps 6,6 are provided with end edges 8 and 8'. The corner flaps 5, 5' are inwards folded about the diagonal lines 3, 3' (see FIG. 3) according to the arrows 9, 9' as represented in FIG. 2. These diagonal lines extend between the points 7, 7' of incision 2, 2' and the point of intersection of the folding lines 3, 3' with the longitudinal edges of the foil part.
Before folding according to the diagonal lines a triangular portion is removed from the corner flaps 5, 5 at the end of the tubular foil part whereby the slanting edges 10, 10' are obtained.
' After folding the corner flaps 5, 5' about the diagonal lines 3, 3' whereby the angular points ll, 11' are obtained, which can be interconnected by the connecting line 12, a separating means in the shape of a heat isolating piece or stamping piece 13, is introduced in such a way that the stamping piece 13 comes to lie over the corner flap 5, and the comer flap 5' is situated over the stamping piece 13. The stamping piece 13 is hinged to the heatable sealing member 14. Preferably the stamping piece 13 which is going to cooperate with the heated sealing member 14 is provided with sealing bars or wires 13a.
Hereupon the bottom flaps 6, 6' are folded, according to the arrow 9a, about the cross folding line 15, 15' which is situated in the tube foil part behind the points 7, 7 of incision 2, 2'. Preferably the perpendicular distance IIb between the transverse folding lines 15, 15' and the end edges 8, 8' of the bottom flaps 6, 6' is almost equal to, but preferably slightly smaller than twice the distance b between the transverse folding lines 15, 15 andthe connecting line 12 between the angular points 11, ll.
Thereupon the sealing member 14 provided with sealing bars or wires 14a stamp hingedly connected with the is pressed on the folded and unfolded bottom corner flaps. It should be noted that just before heatsealing is effected the sealing bars or wires 13a and 14a lie opposite each other. By pplying heat the longitudinal and cross sealings 17 are formed.
It is advisable to provide partial diagonal seals 18. These seals as well as the seals 16 and 17 can be efficiently formed by spot welding, whereby the air in the bag can easily escape on filling. This can be obtained by using sealing bars or wires having profiles providing spot seals.
The longitudinal seals 16 and the diagonal seals 18 and the cross seals 17 are advantageously formed as labyrinth seals. in this way the block bag obtained according to the invention is specially suitable to let the air escape on'filling the bag without solid substances being taken along.
Due to the suitable selection of the distance llb between the end edges 8, 8 and the cross folding line l5, 15', that is slightly smaller than twice the distance between the cross folding line 15, 15' and the connecting line 12 between the angular points 11, 11', a proper closure can be achieved by means of a rectangular welded joint. In order to fix internal tubular foil parts in position in the best possible way another cross seal 17 is formed across the two edges 8, 8' of bottom flap 6, 6 at one end of the folded bottom flaps and in addition thereto one or more diagonal seals 18.
As has been stated hereinbefore it is advisable to bevel the corner flaps 5, in such a way that the slanting edges 10, are obtained. This construction is advantageous in that less layers of material need be sealed locally to each other.
The tubular foil part 1 is obtained by cutting along cutting lines 4, 4' in, and removing triangular areas 20, 20' from -a tubular foil 19. This cutting process may be accomplished with a single cutter member having a cial incisions in the surface of the foil of the flap. In adcutter.
cutting surface corresponding to this configuration in one operation.
By this process of cutting tubular foil parts 1 are obtained, the corner flaps 5 of which are diagonally oppositely situated.
If a rather thick material is used for the tubular foil, the corner flap 5 consituting a valve of the bag is relatively stiff and inflexible, and will not conform to the bottom of the closure of the bag. This difiiculty can be overcome by decreasing the thickness of the corner flap 5 by subjecting its to a transverse stretching operation. This stretching operation decreases the thickness of the corner flap 5, and increases its surface area. As a consequence, the flap 5 adapts itself more readily to the shape of the closure of the bag. After the bag is filled and turned upside down, the filling material in the bag presses against the portion of the flap 5 situated within the bag. Due to the increased surface area of the flap 5, small channels are formed between the flap 5 and the other components comprising the closure of the bag through which air can escape from the closed bag.
In the alternative, an increased flexibility of the corner flap 5 or valve can also be achieved without increasing its surface area by employing lines of weakness 21. These lines of weakness comprise very superfi- The FIGS. 10 and 11 represent a tubular foil part denoted by 31 which is provided with two longitudinal incisions 32 while forming two comer flaps 35 and 35' and two bottom flaps 36 and 36'.
. A portion 34, 34' is severed from these bottom flaps 36 and 36 whereby the end edges 38, and 38' of the bottom flaps 36 and 36' are formed. The two corner flaps 35 and 35' now of equal length are inwards folded about diagonal lines 33 and 33' according to the arrows 39 and 39', as represented in FIG. 3. These diagonal lines extend between the, end points of the incisions 37 and 37' and the folding lines 39, 39'.
For. the purpose of folding, and to require fewer layers of material which need be sealed locally to each other, a part of the comer flaps 35, 35 is removed, whereby the oblique edges 40 and 40 are obtained.
In some cases the long valve being formed by corner flap 35 causes difficulties in filling machines for hard materials. in order to meet this difficulty an incision may be given in the longitudinal edge 43 of corner flap 35 from the free end.
More preferably a triangular part 44, 44 is removed from the end of the comer flap 35 constituting the valve whereby the cutting edges 46, 46' are formed. The length'of the longitudinal edge 43 of the tubular foil removed from the corner flap 35 is less than thevertical distance between the free ends'38, 38' of the bottom flap 36, 36' and the free end of corner flap 35. In this way the valve part has a V-form so that even with short filling pipes of filling machines the valve does not come into contact with the filling material coming from the filler pipe, thus preventing the valve or flap 35 from interfering with the flow of filling material and deflecting it away from the valve.
After folding the comer flaps about the lines 33, 33 whereby the angular points 41, 41' are obtained, between which extends a connecting line 42, a separating means in the shape of a stamping piece 13 is introduced, the stamping piece 13 being introduced in such a way that the comer flaps 35' comes to lie over the stamping piece 13 and the comer flaps 35 comes to lie under the stamping piece 13. The stamping piece 13 is hingedly connected with the sealing member 14, both being provided with sealing bars or wires 13d and 14a as already discussed.
Hereupon the bottom flaps are folded about a cross folding line 45, 45 which is situated in such a way in the tube foil part behind the end points 37, 37' of the incisions, that the perpendicular distance Ila between the cross folding line 45, 45 and the end edges 38, 38' of the bottom flaps 36, 36' is slightly smaller than twice the distance a between the transverse folding line 45, 45' and the connecting line 42 between the angular points 41,41.
Thereupon the sealing member 14 hingedly connected with the stamping piece 13 is pressed on the folded bottom flaps, whereby longitudinal seals and transverse seals corresponding to seals 16 and 17 of FIG. 7 are obtained.
It is advisable to provide partdiagonal seals corresponding to seals 18. Of course these seals can also be very efiiciently formed by spotwelding whereby the air in the bag can easily escape on filling.
These longitudinal seals 16 may also, together with diagonal seals 18 and transverse seals (corresponding to seals 16, 18 and 17) be formed as labyrinth seals.
Due to the suitable selection of the distance Ila between the end edges 38, 38' and the transverse folding line 45, 45' and the connecting line 42 a rectangular welded joint suffices for a good closure. In order to fix in position the loose hanging tubular foil parts in the best possible way another transverse seal is provided between the'two transverse seals at the ends and in addition thereto the diagonal seals.
The good quality of the seals appears from the fact that the shearing strength of the welded joint is 6.3 kg] 1 mm, which is to 20 percent more than normal. It should'be noted in this connection that the tensile strength of the tubular foil materials is 6.3 to 6.5 kg per cm2.
The aforementioned method is of special importance for the manufacture of bags from polyethylene, a rather stiff material in working up.
The tubular foil material is always a thermoplastic material such as polyvinylchloride or polyethylene, preferably the bags are manufactured from polyethylene material. It will be obvious that other thermoplastic materials can also be used for manufacturing the described thermoplastic block bags.
What I claim is:
l. A method of manufacturing a block bag from a thermo plastic tubular foil material having at least one disposed between said first and second corner flaps;
folding each of said first and second corner flaps inwardly about a diagonal folding line defined by said second point of said incision nearest it, and a third point on an adjacent longitudinal edge of said tubular foil spaced longitudinally from said transverse end edge of said tubular foil more distant than said second point;
inserting a separating member with sealing bars under said second corner flap and over said first comer flap;
folding said bottom flaps inwardly about a folding line transverse to said longitudinal axis, said transverse folding line situated between a line defined by said third points on said longitudinal edges of said tubular foil, and a line defined by said second points of said incisions, in an overlapping relationpl i g a sealing member withsealing bars over a closure formed by said bottom flaps and said comer flaps;
activating said seaiing bars from both sides of said closure formedby folding said first and second corner flaps and said bottom flap to seal said bottom flaps, and said comer flaps together; and
removing said separating member after sealing said closure from both sides.
2. A method of manufacturing block bags substantially as set forth in claim 1 further characterized by:
stretching said first comer flap constituting a valve in a direction transverse to said longitudinal axis of said tubular foil to make said flap thinner and more flexible to more readily adapt to the configuration of said closure and to form channels through which trapped air may escape.
3. A method of manufacturing block bags substantially as set forth in claim 1, further characterized by:
forming superficial fourth incisions in said first corner flap constituting a valve in a direction substantially parallel to said longitudinal axis of said tubular foil to make said flap more flexible and more readily adaptable to the configuration of said closure and to form channels through which trappedairmay escape.
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|US3235169 *||Apr 8, 1963||Feb 15, 1966||Windmoeller & Hoelscher||Plastic valve bag|
|US3237534 *||Jan 23, 1963||Mar 1, 1966||Lissner Hans||Process of manufacturing sacks|
|US3370780 *||Oct 22, 1965||Feb 27, 1968||Continental Can Co||Bag with self-venting back seam|
|US3439864 *||Sep 5, 1967||Apr 22, 1969||Union Carbide Corp||Sift-proof industrial bag|
|GB961222A *||Title not available|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3896708 *||Oct 23, 1973||Jul 29, 1975||Wavin Bv||Plastic block bag with a valve|
|US4382538 *||Sep 26, 1980||May 10, 1983||St. Regis Paper Company||Valved lined container|
|US5408641 *||Apr 1, 1994||Apr 18, 1995||Digital Equipment Corporation||Programmable data transfer timing|
|US6533457 *||Sep 8, 1999||Mar 18, 2003||Chronos Holdings Limited||Sack|
|US6623829 *||Apr 27, 2000||Sep 23, 2003||Free-Flow Packaging International, Inc.||Tear-off cushions of loose fill packing material|
|US9126383 *||Apr 30, 2014||Sep 8, 2015||Innoflex Incorporated||Bottom-gusseted package and method|
|US20040050021 *||Sep 17, 2003||Mar 18, 2004||Free-Flow Packaging International, Inc.||Cushions of loose fill packing material|
|US20140294326 *||Apr 30, 2014||Oct 2, 2014||Innoflex Incorporated||Bottom-gusseted package and method|
|U.S. Classification||493/200, 493/213, 493/219, 383/53, 383/126, 493/929|
|International Classification||B31B29/84, B29C65/02, B65D30/24, B65D30/18, B31B29/00|
|Cooperative Classification||Y10S493/929, B65D31/142, B29C65/02, B31B29/84, B31B29/00, B65D31/08, B31B2219/9058, B31B2221/20|
|European Classification||B29C65/02, B31B29/84, B31B29/00, B65D31/08, B65D31/14A|