EP3119710B1 - Method and machine for producing small-width bobbins of film consisting of a stretchable plastic material, from a large-width bobbin - Google Patents

Description

The invention relates to the technical sector of stretchable plastic films in particular in the field of packaging.

More particularly, the invention relates to a method and a machine for making coils of small widths of stretchable plastic film from a wide-width reel for continuously unrolling the stretchable film.

This type of stretch film is well known to a person skilled in the art and has many advantages in view of its essential characteristic of being able to undergo an important lengthening which can be 500% compared to its initial length without being torn under this effect. elongation. The result is to be able to significantly reduce the quantities of material while allowing the assembly of various products given the tension exerted by the stretch film under the effect of its elongation.

It is also known, for a person skilled in the art, to produce reels of stretch film of small widths, for example of the order of 15 cm from a reel of stretch film of great width, called the mother reel, of the order for example of 60 cm. According to the state of the art, for the realization of these coils of small widths, considering that the film is unrolled continuously from the mother reel, in combination with different return rollers some of which are motorized, it is necessary, after having cut the stretchable film at the output of said mother reel to produce breadths of width and numbers corresponding to the desired reels, to wind these widths in a staggered manner to avoid the overlap of the latter as and when winding. This results, for the operator, an obligation to very often change the winding bars on which are arranged mandrels that cooperate with the widths to make the coils small widths.

These different manipulations generate, therefore, a significant downtime by observing, moreover, the obligation to put between each mandrel for winding rolls, spacers tubes.

Furthermore, it has been observed that the result obtained is not always satisfactory, since the tension of the stretchable film is not really controlled so that the edges of the coils obtained are not perfectly smooth and regular. A method and a machine representing the state of the art are disclosed in the document DE 102010051481 A1 . The object of the invention is to remedy these disadvantages in a simple, safe, effective and rational manner.

One of the problems to be solved by the invention is to be able, from a reel of stretch film of large width, to wind on mandrels arranged in a juxtaposed manner on a single winding bar, the different widths precut to achieve concomitantly the number of desired coils of small widths of stretch film.

• on coupe le film étirable à la sortie de la bobine de grande largeur pour réaliser des laizes de largeur et de nombres correspondants aux bobines souhaitées,
• on étire les laizes provoquant un écartement des lignes de coupe suite à la diminution de la largeur desdites laizes résultant de l'étirement,
• on relâche la tension d'étirement de chacune des laizes,
• on enroule à l'état relâché les laizes sur des mandrins pour réaliser les bobines de petites largeurs.

To solve such a problem, it has been conceived and developed a method for producing coils of small widths of stretchable plastic film, from a reel of large width where is unrolled continuously said film. According to the process of the invention:

• the stretchable film is cut at the exit of the large-width reel to produce widths and numbers corresponding to the desired reels,
• stretching the widths causing a spacing of the cutting lines due to the decrease in the width of said widths resulting from the stretching,
• we release the stretching tension of each width,
• the widths are rolled in the relaxed state on mandrels to produce the coils of small widths.

The invention also relates to a machine for producing coils of small widths of stretch plastic film advantageously implementing the method according to the invention.

• une bobine mère à partir de laquelle est déroulé en continu le film étirable,
• des moyens de coupe aptes à réaliser des laizes dont la largeur et le nombre correspondent aux bobines à réaliser,
• des moyens aptes à étirer les laizes pour diminuer leur largeur afin d'écarter d'une manière concomitante les lignes de coupe,
• des moyens d'enroulement des laizes à l'état relâché, sur des mandrins pour réaliser les bobines de petites largeurs.

For this purpose, the machine comprises:

• a mother reel from which the stretch film is unwound continuously,
• cutting means adapted to produce widths whose width and number correspond to the coils to be produced,
• means capable of stretching the widths to reduce their width in order to concomitantly distance the cutting lines,
• means for winding the widths in the relaxed state, on mandrels for making the coils of small widths.

To solve the problem of continuously making widths of determined widths and from the wide-width reel, the cutting means are constituted by blades arranged parallel and in alignment perpendicular to the direction of unwinding of the film, being shifted according to a distance corresponding to the desired width of the width. Cutting blades are mounted on a fixed support bar arranged parallel to the film and perpendicular to the running direction of said film.

To solve the problem of temporarily reducing the width of the widths, the means for stretching the widths, are constituted by two motorized rollers and superimposed driven in the opposite direction, the widths successively passing from the mother reel, on one of the rollers , between the two rollers, then on the other roll, to be conveyed towards the winding means of said widths, said rollers being driven at different speeds.

In order to solve the problem of making the rolls of small widths as such, the means for winding the widths, in the relaxed state, consist of a motorized roller arranged opposite a winding bar of said widths and driven at a different speed, especially lower, the speed of the drawing rollers.

According to another characteristic and to solve the problem of making small-width coils on a single winding bar, the mandrels are rotatably mounted in a position of juxtaposition on said common bar arranged parallel to the drive roller and substantially in tangency position.

Advantageously, in order to increase the production rates, the mandrels are rotatably mounted on a plurality of common bars coupled to a rotating support disk by being circularly offset and arranged parallel to each other and relative to the drive roller in order to be successively brought into position. tangency with said roll.

• la figure 1 est une vue à caractère schématique montrant les principales étapes de procédé selon l'invention,
• la figure 2 est une vue en perspective à caractère schématique des principaux éléments de la machine.

The invention is described below in more detail with reference to the figures of the accompanying drawings, in which:

• the figure 1 is a schematic view showing the main process steps according to the invention,
• the figure 2 is a schematic perspective view of the main elements of the machine.

The invention applies, as evoked, to any type of stretchable plastic film (F). It is recalled that the aim is to produce, from a reel (1) on which the stretchable film (F) is wound, this reel (1) being generally known under the name of reel, reels of small widths (11). These coils of small widths are constituted by a winding on mandrels (2), widths (L), resulting from cuts formed over the entire width of the film (F) in the direction of the length and scroll of the latter.

Thus, according to the method of the invention, the stretchable film (F) is cut at the exit of the reel (1) of large width to achieve the widths (L) whose width and number correspond to the desired small width reels (11).

The widths thus formed are then stretched to cause a separation of the cutting lines (C), which spacing results from the decrease of the width of the widths following the stretching action to which they are subjected. At this level, the widths (L) are no longer joined. The stretching tension of each of the widths is then released and simultaneously rolled up in the relaxed state on the mandrels (2) to produce the rolls of small widths.

It has been illustrated, in particular figure 2 , an embodiment of a machine for the production of several coils of stretchable plastic film of small widths and from a coil (1) as indicated above.

The film (F), wound on a roll (1a) receiving the mother reel, is conveyed, in relation with a return roller (3), at a cutting station (4) shaped to produce the widths (L ). For example, this cutting station (4) comprises blades (4a) arranged parallel and in alignment perpendicular to the unwinding direction of the film (F). The blades (4a) are offset at a distance corresponding to the desired width of the width. In the illustrated example, the cutting blades (4a) are mounted on a fixed support bar (4b) arranged parallel to the film and perpendicular to the direction of travel of the latter. It therefore appears, as the film (F) travels, that the different blades (4a) will make cuts (C) parallel to each other and parallel to the longitudinal edges of the film (F) so as to form, concomitantly, the widths (L) intended to constitute the coils of small widths after having been wound on the mandrels (2).

At the output of the cutting station (C), the machine comprises a station adapted to stretch the widths (L) to reduce their width in order to move away, concomitantly, the cutting lines (C) so that said widths are not more joined.

This stretching station consists of two motorized rollers and superimposed (5) and (6) positively rotated in the opposite direction. At the exit of the cutting station, the widths pass successively on the upper roll (5), between the two rollers (5) and (6), then on the lower roll (6) in order to be conveyed towards a winding station for the formation of coils of small widths.

To perform the stretching action of the widths, the rollers (5) and (6) are driven at different speeds.

The widths (L) are then conveyed, by way of return rollers (7), to the winding station consisting essentially of a motorized roller (8) and a cylindrical common bar (9) arranged parallel to the roller (8) substantially in tangent position. This bar (9) is intended to receive the different mandrels (2) in the juxtaposition position. To ensure that the rolls are wound loose, the roll (8) is driven at a speed less than the speed of the draw rolls (5) and (6). The different mandrels (2) are mounted free to rotate on the bar (9) to ensure the winding of the widths as and when under the effect of driving the winding roller (8).

It follows therefore from these provisions that the winding of the different widths is no longer performed staggered as is the case according to the state of the art, but simultaneously on a single bar receiving the different mandrels.

To increase the production rates, with the aim of producing coils of small diameters (11) from several bars, the mandrels (2) are rotatably mounted on several bars (9) mounted on a rotating support disk (10). ) being circularly offset and arranged parallel to each other and to the winding roller (8). Due to the rotational movement of the support (10), the bars (9) with the mandrels (2) can therefore be successively brought into the tangent position with the winding roller (8).

• La possibilité de réaliser des bobines film étirable de petites largeurs, à partir d'une seule barre commune d'enroulement recevant en juxtaposition les différents mandrins.
• La qualité de résultat obtenu au niveau des bords des bobines étant donné que la tension du film est parfaitement maîtrisée.
• L'augmentation de la cadence de production en considérant la diminution du temps d'intervention au niveau du changement des mandrins.

The advantages stand out well from the description, in particular one underlines and recalls:

• The possibility of producing stretch film coils of small widths, from a single common winding bar receiving in juxtaposition the different mandrels.
• The result quality obtained at the edges of the coils, since the tension of the film is perfectly controlled.
• The increase in the rate of production considering the reduction of the intervention time at the level of the change of the mandrels.

Claims (8)

1. A method of forming small-width rolls of film (F) of a stretch plastics material, from a large-width roll (1) from which said film is unrolled continuously, wherein:

   - the stretch film is cut as it is unrolled from the large-width roll (1) to form strips (L) of widths and in number corresponding to the desired rolls;

   said method being characterized in that:

   - the strips (L) are stretched, thereby causing the cutting lines to be spaced apart due to the reduction in the widths of said strips (L) resulting from the stretching;

   - the stretch tension on each of the strips (L) is relaxed;

   - the strips (L) are rolled up in the relaxed state onto mandrels (2) for forming the small-width rolls (11).
2. A machine for forming small-width rolls (11) of film (F) of a stretch plastics material, from a large-width roll (1) from which said film is unrolled continuously, said machine comprising:

   - a mother roll (1) from which the stretch film (F) is unrolled continuously;

   - cutting means (4) for forming strips (L) of widths and in number corresponding to the rolls (11) to be formed;

   said machine being characterized in that it further comprises:

   - means suitable for stretching the strips (L) so as to reduce their widths, thereby concomitantly causing the cutting lines (C) to be spaced apart;

   - means for rolling up the strips (L) in the relaxed state onto mandrels (2) for forming the small-width rolls (11).
3. A machine according to claim 2, characterized in that the cutting means (4) are constituted by blades (4a) disposed mutually parallel in a line perpendicular to the direction of unrolling of the film, while being mutually offset by distances corresponding to the desired widths of the strips.
4. A machine according to claim 2, characterized in that the cutting blades (4a) are mounted on a stationary support bar (4b) disposed parallel to the width of the film (F) and perpendicular to the direction of unrolling of said film.
5. A machine according to any one of claims 2 to 4, characterized in that the means suitable for stretching the strips are constituted by two motor-driven and superposed rollers (5 and 6) driven in opposite directions, the strips passing successively from the mother roll (1), over one of the rollers (5), between the two rollers (5 and 6), and then over the other roller (6) so as to be brought towards the means for rolling up said strips, said rollers (5 and 6) being driven at different speeds.
6. A machine according to any one of claims 2 to 5, characterized in that the means for rolling up the strips, in the relaxed state, are constituted by a motor-driven roller (8) disposed facing a roll-up bar (9) for rolling up said strips and driven at a speed different from, and in particular less than, the speeds of the stretching rollers (5 and 6).
7. A machine according to claim 6, characterized in that the mandrels (2) are mounted to be free to rotate in juxtaposed positions on the common roll-up bar (9) disposed parallel to the drive roller (8) and in a position in which it is substantially tangential thereto.
8. A machine according to claim 7, characterized in that the mandrels (2) are mounted to be free to rotate on respective ones of a plurality of common bars (9) that are coupled to a rotary support disk (10) while being mutually offset circularly and being disposed parallel to one another and to the drive roller (8) so as to be brought, in succession, into the position in which they are tangential to said roller.

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