FR2508020A1 - PLASTIC BAG FOR DOMESTIC USE AND METHOD OF MAKING SAME - Google Patents

Abstract

BAG FOR DOMESTIC USE IN HOT WELDED PLASTIC MATERIAL, FOR EXAMPLE FOR THE COLLECTION OF HOUSEHOLD WASTE, OR THE LIKE, MADE FROM A SHEATH B OF PLASTIC MATERIAL, SINGLE OR BELLOWS, SUPPLIED BY A COIL A, CHARACTERIZED IN THAT ITS BOTTOM, CONSTITUTED BY THE CROSS-WELD ZONE AT THE DRIVE DIRECTION OF THE B-SHEATH AND, THEREFORE, THE LONGITUDINAL AXIS OF THE APLATI AND EMPTY BAG, IS FORMED BY THE SUPERPOSITION OF AT LEAST FOUR MAIN WALLS, PREFERABLY OF EIGHT MAIN WALLS, THIS OVERLAPPING BEING OBTAINED BY LONGITUDINAL BENDING OF THE PLASTIC SHEATH, BEFORE ITS ARRIVAL AT THE WELDING AND CUTTING STATION, SUCH AS THE WIDTH OF THE SHEATH, SO FOLDED LONGITUDINALLY, OR SMALLER THAN SLIGHTLY IN THE SOLDERING STATION. THE INITIAL WIDTH L. APPLICATION: MAKING GARBAGE BAGS.

Description

I

  The present invention relates to a bag for

  domestic production of hot-welded plastic and a

  method for making such a bag.

  Bags for household use and, in general, bags made of polyethylene, polypropylene, and the like, intended for use, for example, for the collection of

  garbage, so-called garbage bags, are well known.

  These bags are made from a plastic duct spool.

  blown, flattened or bellows, and are then

  de-hot and cut in a direction transverse to their longitudinal drive axis to obtain the bottom weld joint while the c 8 tee opposite the bottom

  stay open to form the mouth of the bag.

  In general, the final width of the flattened bag is also

  to the width of the initial plastic sheath, so that the machine to weld the bottoms is obliged to have a

  corresponding height for the passage of the plastic sheath

  The sacks obtained by means of the conventional welding and cutting process have a weld joint extending over the whole width of the bottom of the bag and forming, so to speak, the bottom even when filling the realized bag. either from a simple flattened sheath, or from a bellows sheath, there is a distribution of the forces generated by the weight of the material contained in the bag, which will be concentrated along the weld joint and in correspondence vertices of the joint itself,

  producing relatively high voltages on the

  the bag, tensions which in certain situations

  killings, can lead to breakage and tearing

walls of the bag.

  The present invention aims to obviate these difficulties.

  and others, and consists of a plastic bag for household use welded to

  hot, usable, for example, for the collection of gold

  domestic hard or similar, which is made from a plastic jacket, single or bellows, characterized in that its bottom, constituted by the weld area transverse to the drive direction of the sheath and, therefore , at the longitudinal axis of the flattened empty bag, is formed by the superposition of at least four main walls, preferably eight main walls, said superposition being obtained by longitudinal folding of the plastic sheath before it arrives at the station welding and cutting such that the width of the sheath bent longitudinally in said

  station is significantly smaller than the initial width

of said sheath.

  The weld zone forming the bottom of this bag is however shorter and thicker than that of conventional bags so that, when the bag according to the invention is filled and tensioned, efforts instead of

  concentrate and act in correspondence of the weld joint

  re, will distribute themselves evenly on the main walls 1-

  bag blades, which, when the bag is filled and put

  in tension, will blend into one main wall.

  The method of producing the bags according to the invention

  characterized in that from a roll of film

  the plastic in a single or bellows jacket, and before said sheath arrives at the welding and cutting station

  bag bottoms, at least one longitudinal folding is performed.

  dinal of the sheathed sheet, which is formed along the driving direction of the plastic sheath so

  that at the above station this sheath arrives folded longitudinally

  nally, forming a substantial superposition of its main walls, preferably the longitudinal folds of the sheath being two, so as to form in correspondence of

  the welding station, eight main walls superimposed.

  The process of folding-the plastic sheath, according to

  the invention provides for the use of appropriate means, irrespective

  placed between the unwinding coil and the welding station,

  and adapted to give the sheath the longitudinal fold or folds

  necessary to obtain the desired configuration of the

  bottom, said folding means preferably being arranged

  following oblique planes to

  sheath taking place from the relative reel a course so-

  nueux. The folding means can be formed by oblique triangles cooperating with guide rollers

  and / or by double folding groups.

  Advantageously, the plastic sheath is first folded longitudinally by folding around its longitudinal median axis with formation of four main walls and then it is folded again around its new

  median axis with formation of eight super-major main walls

  so that the final width of the sheath, before reaching the hot-soldering station, is one-quarter

the initial width of the sheath.

  According to another embodiment, the plastic sheath

  tick is first folded longitudinally by acting

  at the same time on the longitudinal edges of the oppo-

  so that the width of the sheath thus folded is

  divided by two, it is then, as already folded ,.

  folded again about its longitudinal median axis to obtain a width of the sheath thus bent equal to one quarter

of the initial width.

  These characteristics, and others not yet stated, of the invention will now be described with reference to the accompanying drawings, relating to embodiments given merely by way of non-limiting examples, drawings in which: FIG. 1 shows a bag obtained starting from a simple plastic sheath, in its empty and flattened configuration; Fig 2 shows a bag obtained from a sheath

  plastic bellows, also in a configuration

  of and flattened; Fig. 3 is a schematic view of a first embodiment of the method of longitudinally folding a single sheath unwinding from the feed roll to obtain thick and narrow bottom bags, according to the invention; Fig 4 shows an alternative embodiment of the method of Fig 3; Fig 5 is a schematic perspective view of a

  bag obtained by the process according to the invention in the confi-

  guration it takes when it is filled; Fig 6 shows the bag of Fig 1 in the configuration it takes when filled; and Fig 7 shows the bag of Fig 2 in its configuration

when it is filled.

  Referring now to the drawings and in parti-

  In FIG. 3, A denotes a single sheathed plastic sheet feed reel, but of course a bellows sheath such as that of FIG. 2 can also be provided, the reel A taking place by providing the sheath B which is engaged. in the direction of arrow X by

means not shown.

  Along the first path that takes place in a plane from line 10 to roller 12, the sheath B is extended as in B1 with the two equal and opposite main walls 14, 16 (FIGS. it is shown spaced apart for better understanding of the drawings L e S references C and D designate nt

  the longitudinal folding means employed, which are

  by oblique triangles cooperating with rollers

obliques 12, 18 and 20, 22.

  When the sheath B will clog the roll 12 and will pass on the oblique triangle C, it is folded around its median longitudinal axis 24 being guided by the rollers 18, the symmetrical longitudinal folding of the sheath is then carried along the journey between

roll 12 and the rollers 18.

  At the exit of the rollers 18 the width of the initial sheath was divided by two, and the sheath B took the configuration B 2 Then the sheath, already folded by the medium along the longitudinal loop F forming four main walls, is folded again by the means D around the median axis 26 so that at the exit of the guide rollers 22, the width of the sheath, in its configuration B 2,

  will be divided into two halves by taking the configuration

  final ration (B 3), o the width of the sheath will be equal to one quarter of the initial width L. In this configuration B 3 there will be eight superimposed main walls, that is to say the walls 28, 30;

  32, 34; 36, 38; 40, 42, which all derive from the main walls

  initial cipales 14, 16, which have been folded twice,

as we wrote above.

  In practice, the method according to the invention gives the sheath a first longitudinal loop F, deriving from folding about the median axis 24 and then a second longitudinal loop G deriving from folding around the axis

median 26.

  As can be seen, the longitudinal folding means C, D are arranged in different oblique planes so that the path of the sheath B is sinuous, but with an initial course 44 parallel to the final run 46, having the two main walls 14, 16 only along the initial course 44 while, along the final course 46, there are eight main walls superimposed

34 to 42.

  By maintaining this configuration B 3 folded longitudinally

  nally twice, the sheath arrives at the welding station

  and cutting sack funds, not shown.

  In the above-mentioned station, the bottom of the bag N according to the invention is hot-welded in the same way as in conventional processes, said bottom P being much narrower and thicker than the bottom Q of the conventional bags. Indeed, while the bottom Q of conventional bags is formed by a solder joint 52 connecting only the two walls 16, 14, according to the invention the bottom P is formed by a weld zone comprising the eight main walls 28 to 42 as already described, which have a width equal to

  quarter of the width of the walls 14, 16.

  It should be noted that while in the configuration of the filled bag of Figs 6 and 7 the weight of the material contained therein in the conventional bags will concentrate its efforts along the solder joints 52 and, in particular, at the vertices 54 , 56 and, therefore, breakage and tearing of the plastic material forming the bag can occur, the new bag N, when filled, takes (Fig 5) at the bottom P a particular configuration that can be called nen tomato "Since the walls 28 to 42 extend by swelling so that the stresses more

  dangerous will be distributed along a band Z reduced.

  therefore the pressure that will be exerted on the bottom P and

  thus avoiding the danger of breaks or tears.

  It should be noted that another benefit deriving

  of the bag N and the method of embodiment described is deo

  the use of small welding machines for bottom welding P and cutting, being

  given that the final width of the sheath in na configura-

  B 3 is one quarter of the initial width of the sheath in its configuration B Si, to obtain a bag H or M of the conventional type having a width of 700 ma is usually used a welding machine having a height of

  800 au, with the same machine welder it is possible to ob-

  hold four folded bag strips longitudinally from the

aforesaid manner.

  It should also be mentioned that the overall congestion

  of the bag N is to ukme to reduce the operations of condition-

  thus facilitating the work of the operator.

  FIG. 4 represents a variant of the process of r 6

  The effect of the longitudinal folding of the plastic sheath B. my effect, instead of the first oblique triangle folding means 0, is used in this case a double folding group

  GI, the second folding means J being still used.

  In this case, the group GI formed of a pair of opposing Y-shaped folding elements, 11-13, fold loegitdinleent

  the lateral end flanges 27, 25 of the plasma sheath

  3 so that along the path between the group GI and the roll 20 the division of the width L is obtained because the edges 27 and 25 have been folded below the sheath which then takes the configuration B 2 with fornation longitudinal loops R, S As the sheath is driven, it passes from the configuration B 2 A final B 3 in which it is conforemée by the guide means J which gives the sheath a second longitudinal folding around the median axis of the configuration B 2 so that finally, the sheath, in addition to the longitudinal folds R, 8, is also provided with the fold back T, with the result that we have

  in this case, the superposition of eight main parais

  blades, but with a different succession with respect to the configuration of FIG. 3, due to the new way in which the folding has been done so that, instead of only two longitudinal backs, in this case, the Longitudinal fold backs In the embodiment of FIG. 4, the sheath arrives at the welding station, not shown, in the configuration B 3, where the soldering of the sack bases, the cutting and then the forming of the new bag are made This bag formed by the superposition of eight main walls, takes the form and the characteristics of resistance of the previous bag in there

  adding all the advantages of this case.

  It is understood that variants and perfection

  details can be imagined without leaving the

framework of the invention.

REVEDICATIONS

  1. Bag for household use made of plastic material welded & hot, for example for the collection of household waste, or the like, made from a sheath (B) of plastic, simple or bellows, provided by a coil (A ), characterized in that its bottom,

  constituted by the weld zone transverse to the direc-

  of the sheath (B) and, consequently, to the longitudinal axis of the flattened empty bag, is formed by the superposition of at least four main walls,

  preferably eight main walls, this superimposed

  tion being obtained by longitudinal folding of the plastic sheath, before its arrival at the welding and cutting station, so that the width of the sheath, thus folded longitudinally, in said station is

  substantially smaller than the initial width (L).

  2. Bag according to claim 1, characterized in that the weld zone forming the font (P) of this bag is however shorter and thicker than that of conventional bags so that when the bag (Y) according to the invention is filled and tensioned, the efforts, instead of concentrating and acting in correspondence of the welding Jeint, will be distributed uniformly on the main walls of the bag, which when the bag (N) is filled and put in voltage, will blend into one wall. Bag according to claim 1, characterized in that

  that when this bag (N) is filled, it takes a configuration

  ration "tomato" because with the plastic sheet

  extent of the small weld zone of the bottom of the

  The inflated portions of the plastic material leave, which will be disposed from the bottom (P) according goasses which will merge into a single wall formed by the sheet

of plastic material.

  4 Process for producing plastic bags

  for domestic use, intended for example for

  garbage collection or the like, known as "bags"

  trash bins *, characterized in that from a coil (A) of plastic sheet, single or bellows jacket, and before said sheath arrives at the welding station and cutting the sack, it is realized at least a longitudinal folding of the sheet (B) in sheath, which is formed

  along the entraining direction of the plasma sheath

  tick so that at said station said sheath arrives folded longitudinally forming a substantial superposition of its main walls, the longitudinal folds

  the sheath preferably being two, so as to form

  sea, in correspondence of the welding station, eight

  superimposed principal kings (28, 30, 32, 34, 36, 38, 40, 42). 5. Method according to claim 4, characterized in that the provision of the use of suitable means interposed between the unwinding coil (A) and the welding station

  and adapted to impart to the sheath (B) the longitudinal fold or folds

  tudinal needed to get the desired configuration

  from the bottom, said folding means preferably being

  placed in oblique planes to accomplish A

  sheath unwinding from the reel (A), a sinuous course.

  6 Process according to claim 4, characterized in that the folding means are constituted by oblique triangles (C, D) cooperating with guide rollers (12, 18 and 20, 22) and / or by groups of double

folding (GI).

  Process according to claim 4, characterized in

  that the plastic sheath (B) is folded longitudinally-

  by first folding around its median axis

  initial longitudinal formation with four primary walls

  cipales and then she is bent again around her

  new central axis with the formation of eight main walls

  superimposed so that the final width of the sheath before reaching the hot-soldering station is the

  quarter of the initial width (L) of the sheath (B).

  8. Method according to claim 4, characterized

  in that the plastic sheath (B) is first folded longitudinally

  tudinally by acting simultaneously on the long edges

  the width of the thus folded sheath is less than half and then said sheath, already folded, is subsequently folded around its longitudinal median axis to obtain a width of the sheath. sheath thus folded, equal to the

quarter of the initial width (L).