APPARATUS AND METHOD FOR UNWINDING A BAND AND APPLYING GLUE THERETO

Abstract

 The present invention refers to an apparatus, in particular to an unwinding apparatus, used in coremakers for producing a tubular element by winding a band of card (100) in a spiral and subsequently cutting to size.
The winder according to the present invention comprises a main structure adapted for unwinding a reel of said band (100), comprising a glue dispenser (20) for depositing glue on at least one portion of said band (100) and further comprising, downstream of said glue dispenser (20), at least one heating element (30) configured to heat said at least one portion of said band (100) on which the glue has been deposited.

Description

FIELD OF THE INVENTION

[0001] The present invention refers to an apparatus and to a method for applying glue to a band.

[0002] More specifically, the present invention concerns an unwinding apparatus of a "coremaker".

[0003] The unwinding apparatus, or even more simply unwinder, is a machine adapted for unwinding a band, typically made of card wound in reels, and adapted for applying an adhesive material, typically a vinyl glue, on said band.

[0004] The band thus prepared is then sent to a winding group adapted for carrying out the spiral-winding of said support around a core, or pin, for producing tubular elements intended to be used as internal support, or core, in rolls of toilet paper, rolls of all-purpose absorbent paper, rolls of adhesive tape or other.

[0005] The so-called "coremaker" apparatus therefore comprises at least one unwinding apparatus and at least one winding group.

STATE OF THE ART

[0006] Unwinding apparatuses for coremakers are currently known comprising a glue dispenser with extruder, in order to deposit adhesive material on the substrate that is fed to the winding group.

[0007] It is known to use vinyl glues that are applied cold, however different parameters make the application step of the glue on the substrate particularly critical.

[0008] Among such parameters, that which has the greatest influence not only on the correct arrangement of the layer of adhesive material on the substrate, but also on the subsequent drying step of the glue itself during the subsequent helical winding step of the substrate in the formation of the tubular element, is the temperature of the glue itself.

[0009] Indeed, even if vinyl glues are generally used "cold", this does not means that the deposition process of the glue through the dispenser with extruder can take place at any temperature.

[0010] Rather it is essential that the glue preferably has a temperature around 25°C, in any case comprised between 20°C and 40°C.

[0011] The temperature of the glue is important for the productivity of the machine particularly when it is considered that the support, which as stated in general consists of a band or strip of card, is processed by the unwinding group at a linear speed that can reach 400 metres/minute.

[0012] With these advancing speeds of the support it is essential that the vinyl glue is in the optimal viscosity conditions to obtain a quick and correct dispensing by means of the extruder, and it is therefore essential that its temperature be kept within the recommended range.

[0013] As it is known, the correct arrangement of the glue on the strip of card influences the problem of the formation of "detached edges", i.e. lifting due to a lack of glue of an end band edge at the cutting area along the edge of the strip wound in a spiral.

[0014] In order to avoid the formation of detached edges it is important for the glue applied to dry very quickly, so that the subsequent cutting operation does not cause the end edge to lift, forming the detached edge.

[0015] It can be understood, therefore, that with respect to the problem of the formation of detached edges it is essential that the glue not only be dispensed in the correct amounts and with the correct speed, but also that it dries quickly.

[0016] The problem is even greater the more the following aspects are considered.

[0017] The support material, typically as stated consisting of a strip of card, is required by the market to be increasingly thin, not only to keep down the costs of the material per se, but also to keep down the costs of the subsequent disposal of the product and the waste.

[0018] Therefore, there is a tendency to use a lower number of windings in making the tubular elements in question, preferring single-strip embodiments, and/or to use lower basis weights, which further accentuates the problem of obtaining a correct distribution of the glue on the support and its quick drying.

[0019] A further factor that accentuates the need to obtain quick drying of the glue is the ever-increasing need to use vinyl glues in which the presence of borax is reduced if not entirely absent.

[0020] Vinyl glue indeed consists of long and flexible molecules of a polymer, polyvinyl acetate, in aqueous suspension. Borax binds together the polymeric chains thickening the glue.

[0021] A vinyl glue without the borax-based reagent is therefore more fluid, which accentuates the need for quick drying.

SUMMARY OF THE INVENTION

[0022] The purpose of the present invention is to avoid the drawbacks of the known solutions by providing an unwinder for coremaker machines, adapted for carrying out the production of a tubular element by winding a strip of card in a spiral and subsequently cutting the single elements, which makes it possible to eliminate or at least reduce the drawbacks linked to the dispensing temperature and to the drying speed of the glue that is deposited on the card.

[0023] A further purpose of the present invention is to make an unwinding apparatus that makes it possible to optimise the deposition and drying steps of the glue in relation to high advancing speeds of the band of card, to reduced thicknesses and in the case of vinyl glues without additives, e.g. without borax.

[0024] These and other purposes according to the present invention are accomplished by an unwinder for producing a tubular element by winding at least one strip of card in a spiral according to claim 1.

[0025] Further characteristics of the apparatus according to the present invention are the object of the dependent claims.

[0026] In general, the unwinding apparatus according to the present invention achieves the aforementioned purposes by arranging a heating element downstream of the glue dispenser configured to deposit said glue on at least one portion of the band processed by the unwinder, said heating element being adapted for heating the portion of said band on which said glue has been deposited and comprising at least one emitter of air at controlled temperature movable between a first operative position, in which said air flow hits at least one portion of said band and a second rest position, in which said air flow is deviated with respect to said band, not hitting it.

[0027] Said heating element preferably comprises at least one fan adapted for generating an air flow and heating means, for example consisting of an electrical resistance, adapted for heating said air flow generated by said fan.

LIST OF FIGURES

[0028] The characteristics and advantages of the unwinding apparatus according to the present invention will become clearer from the following detailed description, given as an example and not for limiting purposes, referring to the attached schematic drawings, in which:

• figure 1 is an overall side view of the unwinding apparatus according to the present invention;
• figure 2A shows a detailed enlarged view of the heating element adapted for heating the portion of said band on which said glue has been deposited, in which the emitter is in a first position in which the air flow generated by the emitter hits at least one portion of said band;
• figure 2B is the same view of figure 2A in which the emitter is in a second position in which said air flow is deviated with respect to said band, not hitting it;
• figure 3 shows a detailed view of a preferred embodiment of the heating element and, in particular, of the outer casing of said heating element.

DETAILED DESCRIPTION OF THE INVENTION

[0029] With reference to the attached figures, an unwinding apparatus 10 according to the present invention comprises a main structure comprising a plurality of devices, of the known type, which unwind a reel of band 100 of card that is fed to the spindle of the subsequent winding module, not represented in figure 1. The band 100 of card, or of another equivalent material, is conveyed by means of a plurality of pulleys 11 towards a glue dispenser 20 equipped with extruder 21.

[0030] The dispenser, also of the known type, ensures that the glue is deposited on the band 100 in the desired amount and way.

[0031] As stated, typical advancing speed of the band 100 in the unwinding apparatus 10 are about 250-350 metres per minute, up to speeds of 400 metres per minute.

[0032] With such high advancing speed, suitable for maintaining high productivity of the coremaker, the glue risks to not have reached the correct drying point when the band 100 reaches the spindle of the winder, causing the described problems linked to the formation of detached edges.

[0033] In order to overcome these drawbacks, the unwinding apparatus 10 according to the present invention further comprises a heating element 30 adapted for heating the portion of said band 100 on which the glue has been deposited.

[0034] The heating element 30 preferably comprises, in accordance with a preferred embodiment of the present invention, at least one emitter 31 of air having a controlled temperature.

[0035] The heating element 30 preferably comprises at least one impeller adapted for generating an air flow through said emitter 31, and heating means, for example consisting of an electrical resistance, adapted for heating said air flow generated by said impeller.

[0036] Impeller and heating means are not indicated in the attached figures.

[0037] They can advantageously be housed inside the main body 32 of the emitter 31 or on-board the main structure of the unwinding apparatus 10.

[0038] With particular reference to figures 2A and 2B, said heating element 30 comprises a substantially box-shaped containment structure 33 in which said emitter 31 is at least partially housed.

[0039] More specifically, at least the end portion, i.e. the diffuser 31a, of said emitter 31 from which the air flow comes out is preferably housed in said containment structure 33.

[0040] Even more specifically, preferably said containment structure 33 comprises at least one inlet opening 30a and at least one outlet opening 30b for said band 100, which can thus cross said heating element 30.

[0041] Said inlet and outlet openings 30a, 30b are advantageously slit-shaped, so that the air generated by the diffuser does not come out from said openings.

[0042] Advantageously, said inlet opening 30a and said outlet opening 30b are aligned along the direction identified by the advancing direction of the band 100, and an abutment sheet 36 is further provided inside said containment structure 33, also arranged according to the direction identified by said band 100.

[0043] Said abutment sheet 36 is positioned on the opposite side of said band 100 with respect to said diffuser 31a of said emitter 31.

[0044] More specifically, calling the surface facing downwards in the figures on which the glue is placed by the dispenser 22 inner surface 101 of the band 100, and calling the surface facing upwards in the figures outer surface 102 of said band 100, said abutment sheet 36 is positioned inside said containment structure 33 so that the outer face 102 of said band 100 touches it.

[0045] Preferably, said sheet is positioned with respect to said band or is sized with respect to said band so that at least one portion of the outer face 102 of said band 100 projects laterally from said sheet 36, so as not to be in contact with it.

[0046] Advantageously, the width of the portion of said band that projects from said sheet corresponds to the width of the strip of band on which the glue has been deposited by the dispenser 22.

[0047] Basically, advantageously the heating element 30 is configured so as to foresee that the strip of band 100 engaged by the glue is free with respect to any type of abutment, whereas the part of band not engaged by the glue rests, with its outer face 102, against said support sheet 36 which has the function of preventing the band itself from moving through the action exerted by the air flow coming from the emitter 31, modifying the distance of the band 100 from the diffuser 31a of the emitter 31, a distance that influences the heating of the band itself.

[0048] At the same time, however, the provision that consists of foreseeing that the edge engaged by the glue is free with respect to abutment against the sheet, ensures that the heating temperature of the portion of band engaged by the glue is exclusively due to the hot air flow.

[0049] This aspect is clearer when it is considered that said emitter 31 is movable between a first operative position, shown in figure 2A, in which said emitter 31 is oriented so that the air flow hits at least one portion, the one hit by the glue, of said band, and a second rest position, shown in figure 2B, in which said air flow is deviated with respect to said band, so as not to hit it.

[0050] Preferably, the emitter 31 for this purpose is movable between the first operative position in which the diffuser 31a at its end is close to the band 100, about 1 centimetre away from the lower surface 101 of the band and so that the air flow is substantially perpendicular to the lower surface 101 of the band, and the second position in which said diffuser 31a of said emitter 31 is moved with respect to the band 100, so that the air flow generated by the emitter 31 does not hit the band 100.

[0051] Advantageously, said diffuser 31a is configured like a blade, or like a slit, in order to convey the air flow with greater precision onto the desired portion of band.

[0052] Furthermore, said diffuser 31a is advantageously removable, so that diffusers 31a with different shapes or characteristics can be mounted on the emitter 31.

[0053] Advantageously, said containment structure 33, shaped substantially like a box, comprises an inner wall 33a and an outer wall 33b, a gap 34 being formed between the two walls.

[0054] Furthermore, according to what can be seen in figures 2A and 2B, said inner wall 33a is associated with deflector elements 35 adapted for channelling the air flow coming from the emitter 31 when the latter is positioned in the second rest position of figure 2B.

[0055] Thanks to this configuration of the containment structure, and in particular to the presence of the deflectors 35, it is possible to move the emitter 31 in the second rest position conveying the air outwards, in particular the air can freely come out from the lower area of said containment structure 33.

[0056] Advantageously, the emitter 31 is rotatably associated with a support element 37, so that it is movable between said first and said second position rotating around a hinging point.

[0057] Furthermore, advantageously, the movement of the emitter is obtained through pneumatic actuation means.

[0058] According to a preferred embodiment of the present invention shown as a non-limiting example in the attached figures, the heating element 30 of the winding apparatus 10 according to the present invention is suitable for generating a hot air flow at high temperatures, of about 400°C-600°C.

[0059] For this purpose, the heating means are suitably sized and thus so is the fan.

[0060] The possibility of moving the emitter 31 of said heating element 30 between a first operative position and a second rest position in which the air does not hit the band 100 has the purpose of preventing damage to the band 100 in the case of the unwinder stopping.

[0061] Indeed, in the case in which it is necessary to stop the advancing of the band 100 it is necessary, to avoid burning the band itself, to immediately interrupt the outflow of hot air. However, even by interrupting the supply to the resistance, the cooling transient of the heating means would not ensure an immediate decrease in temperature of the air flow, and therefore the band would continue to be hit by hot air risking burning.

[0062] In the same way, it is not possible to instantaneously interrupt the air flow by turning off the fan, since that would risk damaging the heating means themselves. The system for moving the emitter 31, which has been described, has therefore been devised and provided. Thanks to the possibility of moving the emitter taking the air flow away from the band 100, there is an immediate interruption of the flow that hits the band, with it being possible at a subsequent time to turn off the heating means and then, when they are cooled down sufficiently, also turn off the fan.

[0063] The containment structure 33 of the heating element 30 has also been devised and made to ensure optimal safety conditions for users who work near to the machine.

[0064] In order to respect safety standards, the external temperature of the containment structure 33 must be below 50°C, since the worker must not risk getting burnt in the case in which accidental contact is made, for example by resting a hand on it, with the outer surface of the heater 30.

[0065] According to a preferred embodiment of the present invention, shown in figure 3, the containment structure 33 advantageously comprises an inner wall 33a and an outer wall 33b, a first gap 34 being provided between the two walls.

[0066] Outside of said outer wall 33b, advantageously there is also a layer of insulating material 38, for example consisting of glass-ceramic, over which a layer of polycarbonate 39a, for example Lexan, and preferably a second layer of polycarbonate 39b separated by a second gap 39c from said first layer of polycarbonate 39a, is juxtaposed.

[0067] Advantageously, above said containment structure 33 it is possible to provide a fan 50 or analogous cooling means suitable for creating a cool air flow in the gaps of the structure itself.

[0068] For the sake of completeness of description, as can be seen in the attached figures, an opening 40 for the insertion of the band 100 inside the containment structure 33 is provided on said containment structure 33.

[0069] Another object of the present invention is a method for applying glue to a band 100 processed by an unwinding apparatus 10 according to what has been described up to here, which comprises the steps of:

• Providing the band 100 and feeding it to a glue dispenser 20;
• Depositing a controlled amount of glue on said band 100 by means of said dispenser 20;
• At least partially hitting the surface of said band 100 on which the glue has been deposited with a hot air flow.

[0070] Method according to what has been described above, in which said step consisting of hitting the band 100 with a hot air flow occurs when the formation speed of the tube in the winding group is about 80 metres/minute, corresponding to an advancing speed of the band 100 in the unwinding apparatus that is roughly double, indicatively 150 metres/minute.

[0071] The method according to what has been described also preferably foresees that said hot air flow has an average temperature of about 400°-600° C.

[0072] The coremaker machine thus conceived can undergo numerous modifications and variants, all of which are covered by the invention; moreover, all of the details can be replaced by technically equivalent elements. In practice, the materials used, as well as the sizes, can be whatever according to the technical requirements.

Claims

1. Unwinding apparatus (10) for coremaker machines comprising a main structure adapted for unwinding a reel of a band (100) of cardboard or similar material that is fed to the spindle of a winding module, comprising a glue dispenser (20) for depositing glue on at least one portion of said band (100), characterised in that it comprises, downstream of said glue dispenser (20), at least one heating element (30) configured to heat said at least one portion of said band (100).

2. Unwinding apparatus (10) according to the previous claim, characterised in that said heating element (30) comprises a hot air emitter (31).

3. Unwinding apparatus (10) according to the previous claim, characterised in that said hot air emitter (31) comprises at least one fan and heating means for heating the air flow generated by the fan.

4. Unwinding apparatus (10) according to the previous claim, characterised in that said emitter (31) is movable between a first operative position in which said emitter (31) is oriented so that the air flow hits at least the portion of said band (100) on which the glue is present, and a second rest position in which said air flow is deviated with respect to said band (100), so as not to hit it.

5. Unwinding apparatus (10) according to the previous claim, characterised in that said emitter (31) is hinged to a support element (37) fixedly connected to said apparatus (10).

6. Unwinding apparatus (10) according to the previous claim, characterised in that said emitter (31) is moved by pneumatic actuation means.

7. Unwinding apparatus (10) according to one or more of the previous claims, characterised in that said heating element (30) comprises a containment structure (33) in which said emitter (31) is at least partially housed.

8. Unwinding apparatus (10) according to one or more of the previous claims, characterised in that said emitter (31) comprises a main body (32) and an end portion (31a) from which the air flow comes out, at least said end portion (31a) being housed inside said containment structure (33).

9. Unwinding apparatus (10) according to one or more of the previous claims, characterised in that said containment structure (33) of said heating element (30) comprises an inner wall (33a) and an outer wall (33b), a first gap (34) being provided between the two walls.

10. Unwinding apparatus (10) according to the previous claim, characterised in that said containment structure (33) further comprises, outside of said outer wall (33b), a layer of insulating material (38), preferably glass-ceramic, on which a layer of polycarbonate (39a), preferably Lexan, is juxtaposed.

11. Unwinding apparatus (10) according to the previous claim, characterised in that said containment structure (33) further comprises, outside of said outer wall (33b), a second layer of polycarbonate (39b) separated by a second gap (39c) from said first layer of polycarbonate (39a).

12. Unwinding apparatus (10) according to the previous claim, characterised in that said emitter (31) is configured to emit hot air at a temperature of about of 400°C-600°C.

13. Unwinding apparatus (10) according to the previous claim, characterised in that said heating element (30) further comprises at least one inlet opening (34) and at least one outlet opening (35) for said band (100), which can thus cross said heating element (30), an abutment sheet (36) being further provided inside said containment structure (33) and arranged according to the direction identified by said band (100).

14. Method for applying glue to a band (100) processed by an unwinding apparatus (10) according to claim 1, comprising the following steps:

- providing the band (100) and feeding it to a glue dispenser (20);

- depositing a controlled amount of glue onto said band (100) by means of said dispenser 20;

- at least partially hitting the surface of said band (100) on which the glue has been deposited with a flow of hot air generated by a heating element (30).

15. Method according to the previous claim, wherein said step consisting of at least partially hitting the surface of said band (100) on which the glue has been deposited with a flow of hot air is carried out when the advancing speed of the band exceeds the threshold value of about 150 m/min.

Drawing