Glue Dispenser

Abstract: A glue dispenser is described, for dispensing glue by overflow. The dispenser includes a tubular container (55) provided with means (61) which define a slit (63) from which the glue is dispensed. Means (91) are also provided for feeding the glue to said tubular container (55) and to said slit in order to have said glue dispensed by overflowing from said slit.

Description: The invention refers to a glue dispenser according to the preamble of claim 1, which can be used e.g. for glueing the tail or outer end of a web material wound to form a roll or log. A glue dispenser of this kind is known from GB-A-1.497.662. This known glue dispenser is used for applying glue on a continuously moving web which travels in front of and in contact with the dispensing slit. As soon as the feeding of the web is interrupted, the web is lifted from the slit, the glue is removed from said slit and the latter is closed until the operation of the machine is started again. From FR-A-2.606.674 a glue applicator is know, for applying glue on a lid. The applicator is provided with a circularly shaped slit surrounding a duct which is connected with a collector tank. The glue fed in excess from said circular slit is conveyed with the aid of vacuum in said collector tank and is not recirculated. GB-A-1.434.941 discloses a glue applicator for applying glue to a carton blank or the like. Glue is intermittently dispensed from a nozzle by means of a cylinder-piston pumping means. When the cylinder-piston pumping means are inoperative, glue is continuously kept under circulation in a closed circuit by means of a balanced system of two pumps, and does not overflow from the nozzle. An inert gas chamber surrounding the nozzle avoids oxidation of the glue. A glue dispenser for glueing the outer end of a log of web material is described in U.S. Patent N.4,475,974. That apparatus comprises chain means which supports pairs of bearing rollers. The logs to be glued are disposed on these- bearing rollers. Each roll or log is transported by means of a conveyor member through a first station in which the tail or outer end of the web is unwound from the log and laid down onto a flat surface. At a second station a nozzle, moving parallel to the axis of the log, applies glue to the end of the unwound material. At a third station, the log is rotated between the two bearing rollers so as to wrap the outer end and back onto the log and thus glue it to the outer surface of the log. Located downstream of these stations are log-pressing and closing rollers and a discharge surface. This apparatus makes it possible to attain high outputs per hour in that, at each instant, three logs are processed at the same time in the three stations for the unwinding, glueing and closing of the log, respectively. However, this type of glue applicator has a rather complex and costly structure. It is an object of the invention to provide a simpler glue dispenser which, when applied e.g. to a tail sealer, makes it possible to reach high outputs per hour with an extremely simple construction and with a limited number of movable parts. The glue dispenser of the present invention, e.g. for use in an apparatus for glueing the tail of logs or rolls of web material is defined in claim 1. It comprises a tubular container provided with means defining a slit from which the glue is dispensed, and means for feeding the glue to said tubular container. A storage tank is provided below the container to collect the glue overflowing from said slit. Recirculating means are provided for recirculating said overflowing glue to the tubular container. Preferably the slit is disposed in alignment with a surface on which the items to be glued are made to roll. Advantageously the storage tank may be connected to a glue reservoir into which the glue collected by said tank is re-admitted to let it into the tubular container afterwards. Said reservoir may be located at such a height that the difference between the level of glue inside the reservoir and the height of the dispenser slit will allow the glue to flow through the latter. In this way, a continuous flow of glue from the reservoir to the container, and from the latter to the dispensing slit, is obtained. The glue flow rate is determined by the difference in height between the glue surface within the reservoir and the dispenser slit, by the pressure loss along the glue path, by the glue viscosity, and by the slit dimensions. This type of supply has the advantage of not requiring a controlled dispensing means, such as a pump and a nozzle and, moreover, it allows a continuous and easily adjustable flow of glue from the reservoir to the slit, while the excess of glue overflowing from the slit, which is not picked up by the logs rolling over the same slit, is collected in the underlying tank from which it can be easily recovered and made to flow back into the upper reservoir. This avoids the drawbacks exhibited by the nozzle-type dispensing means which, when the apparatus is stopped even for short periods, are clogged up by the drying of the glue, thus making it difficult to re-start the apparatus. With a continuous flow of glue, as obtained through the dispenser of the present invention, there is no undesirable drying of glue during short pauses of the apparatus, since the supply is not interrupted and the glue remains in circulation. Further advantageous features of the dispenser according to the invention are set forth in the annexed claims. The invention will be better understood by following the description and the attached drawing, which shows a feasible, not limiting, embodiment of the same invention, applied to a tail sealer. In the drawing: Fig. 1 shows an ensamble side view of the apparatus according to the invention applied to a tail sealer. Fig. 2 is an enlarged detail of the tail unwinding region. Fig. 3 shows an enlarged side view of the glue application region. Fig. 4 shows a cross-section view of the glue dispenser. Fig. 5 shows a section taken on line V-V of Fig. 4; and Figs. 6 and 7 are schematic views of two embodiments of the glue dispenser system according to the present invention. With reference to Fig. 1, the tail sealer wherein the glue dispenser is applied, by way of example, comprises an inclined surface 3 on which the logs of web material roll when they are discharged from an upstream-located rewinder, not shown. Downstream of the inclined surface 3 is a rotating wheel 5 which transfers the rolls coming from the surface 3 to the next station, generally designated 7, for the unwind of the tail L. The station for the unwinding of the log tail comprises a pair of cylinders 9 and 11 rotating about fixed axes in a direction indicated by the arrows in the Figure. Associated with the cylinder 11 is a suction box 13 with a surface 15 on which, during the unwinding operation, the tail of the log, being discharged on the cylinders 9 and 11, is laid. Associated with the unwinding station 7 are nozzles 17, 19 from which air jets facilitate the unwinding of the tail from the log on the surface 15. A sensor 21 disposed above the surface 15 and schematically represented in the Figure detects the position of the tail on the bearing surface 15. Said sensor 21 is mounted by means of a knob 22 and a slot, as as to be easily moved in the direction of the double arrow f21. Moving the sensor 21 makes it possible to adjust the length of the unwound tail and thus the position of the line of glue with respect to the tail of the web material. The unwinding station operates substantially in a manner similar to that described in the cited patent U.S. 4,475,974 and, therefore, will not be described in greater detail. The apparatus further comprises a conveyor 23 which may be a pair of chains parallel to each other and disposed one on either side of the machine, only one of them being indicated in dotted line in Fig. 1. The conveyor 23 is driven by a series of wheels or pulleys 25, 27, 29, 31, 33 and 35. The wheels 25 to 35 define a path of the conveyor 23 for the purposes indicated below. In the example shown, the wheel 25 is driven into rotation through a belt or chain 37, by a motor or motor-reducer 39, and transmits the motion to the other wheels. Cradles 41 pivotally connected to the conveyor 23 are provided for supporting the log. In the example shown in Fig. 1, six cradles 41 are provided, each of which is pendulum-like pivoted to the conveyor 23. In practice, each cradle 41 consists of a transverse beam 40 connected at its ends to two small side boards 42 swingingly pivoted at 43 to the respective conveyor 23. Each beam 40 carries a plurality of V-shaped troughs 44 which form the teeth of a comb-like structure. The cylinders 9, 11 are provided with corresponding annular slots to allow the passage of the V-shaped troughs 44, for the purposes to be indicated below. An applicator generally designated 45 is disposed above the unwinding station 7 for applying the glue to the log and downstream of said applicator additional means 47 are disposed for pressing the tail, now rewound, against the log, and fixing it onto the latter. Disposed downstream of means 47 is a wheel 49 which discharges the logs, one after the other, onto an inclined plane 51 to feed them to further work cycles. The wheel 49 is synchronized with the motion of the conveyor 23, and thus of the cradles 41, to discharge the logs R onto the inclined plane 51, when no cradle is passing through the discharge region of the wheel 49. In practice, the wheel 49 discharges at such a frequency as to avoid the accumulation of rolls after the glueing station. The glue-applying means 45 are shown in detail in Figs. 4 and 5. Substantially, these means comprise a dispenser 53 made up of a tubular-shaped container 55 which has a square cross-section and is provided with holes 57 on top. The holes 57 of the tubular container 55 lead into a wedge-shaped spout 59 formed by a pair of inclined plates 61 which define at their top a slit 63 from which the glue is delivered. The slit 63 is disposed in alignment with a log or roll rolling surface 65 for the application of the glue in a manner to be described later on. The position of the slit 63 with respect to the surface 65 can be seen in detail in Figs. 3 and 4,wherein the dispenser device 53 is schematically represented. As shown in particular in Fig. 4, one of the two plates 61 is fixed on the tubular container 55, while the other may be adjusted in position in the direction of arrow f61 by means of a series of set screws 69 which engage into bushes 71 fixed to the relevant plate 61. Shapes 72 (Fig. 5) are provided to guide the motion of the plate 61 during adjustment. The tubular container 55 extends throughout the width of the apparatus, while the slit 63, defined by the plates 61, extends to an extent approximately equal to the axial development of the logs to be glued. Disposed beneath the tubular container 55 is a storage tank 73 mounted by brackets 75 to the sides 77 (Fig. 5) of the apparatus. The brackets 75 are provided with slots 79 for the passage of screw means 81 therethrough; said screw means are provided for a clamping engagement to the machine frame allowing the assembly made up of tank 73, container 55 and plates 61 to be adjusted in height. The adjustment is carried out by means of set screws 83. The tank 73 has a laterally (to the right in Fig. 5) inclined bottom and is provided with a pipe fitting 85 at the lowest point thereof for connection to a conduit 87 from which the glue collected within the tank 73 is taken out and made to re-circulate in a manner to be described later on. Conduits 91 are joined to the tubular container 55 for the inflow of glue inside the said tubular container 55. The glue is drawn out through the conduits 91 from a reservoir 93, schematically shown in Fig. 1, in which the glue surface reaches a level higher than the slit 63 defined by plates 61 fixed to the tubular container 55. In this way, the glue contained in the reservoir 93 may flow through the conduits 91 into the tubular container 55 and come out by overflowing from the slit 63 because of the difference in height between the glue surface inside the reservoir 93 and the feeding slit 63. The flow rate of glue may be easily adjusted by varying the difference in height. Advantageously, the glue is made to flow continuously, and the excess of glue overflowing or overfalling from the slit 63, and which is not applied to the log as described later on, collects in the underlying storage tank 73 to be recovered through the conduit 87 and re-circulated into the reservoir 93 by a suitable pumping means. The arrangement of reservoir 93 and conduit 91 with respect to the glue-feeding device is also schematically depicted in Fig. 6 which shows a glue-recirculating pump 92. The delivery of glue may also take place in a different way, with an arrangement of the type shown in Fig. 7. In this embodiment, the glue reservoir, designated 93', is disposed at a lower level with respect to the delivery slit 63 and to the tubular container 55. The excess of glue collected in the tank 73 is directly introduced into the reservoir 93' through the conduit 87. From this reservoir, the glue is drawn out by a constant-flow rate pump 94, to be fed into the tubular container 55 via the conduit 91'. The above-described apparatus operates as follows. The roll or log coming from a rewinder located upstream of the described apparatus is made to roll onto the inclined surface 3 and transferred by the wheel 5 to the cylinders 9 and 11 which, as described for example in the cited patent U.S. 4,475,974, provide for unwinding a portion of the tail (free end) to lay it down onto the surface 15 of the suction box 13 with the aid of the nozzles 17, 19 and of sensor 21 which stops the rotation of cylinders 9, 11 the moment the free unwound end reaches a pre-determined position on the surface 15. At this point, the conveyor 23, which moves in the direction of arrow f23, brings one of the cradles 41 below the log supported by the cylinders 9 and 11 and raises it up towards the glue-applying means generally indicated by 45. As shown in particular in Fig. 2, when the log R is lifted from the cylinders 9 and 11 by means of the cradles 41, its tail end L hangs freely downwards. Along the path of the conveyor 23, a guide surface 95 is disposed which drives the cradles 41 into oscillation when these arrive at the height of the surface 65 for discharging the log R onto the said surface 65. The log-discharge phase is shown in particular in Fig. 3. the position for the discharge of log R onto the surface 65 is so determined that, when the log begins to roll over the said surface 65, it comes in contact with the slit 63, defined by the plates 61, at the position where the tail is to be glued. Accordingly, when the log R begins to roll on the surface 65, as shown in Fig. 3, it comes in contact with the slit 63 and has applied thereto, in the region I, an amount of glue sufficient to allow the subsequent anchorage of the tail L which is re-wound onto the log body as the latter continues to roll downwardly in the direction of arrow fR along the surface 65. Disposed at a suitable distance from the slit 63, two cylinders 97, 99 are part of the log-closing means 47. The space between the rollers 97, 99 is such that, when the log passes between them, the log itself is radially compressed to receive the tail L onto the log. To this end, both cylinders 97, 99 are motor-driven and are rotated at slightly different peripheral speeds. The difference between the peripheral speeds is such as to rotate the log through one or two revolutions during its transit between the cylinders 97, 99. The thus-closed log is discharged, as already described, onto the discharge plane 51 by means of wheel 49. For the above-described apparatus to work properly, it is evident that the tail L of log R must be folded downwards when the log is discharged from the conveyor onto the surface 65 and passes over the glue-feeding slit 63. If the wound material is sufficiently flexible, the tail L places itself spontaneously in the position shown in Fig. 2. However, in some cases, and when the material wound up on the log R is thicker and stiffer, it may be necessary to provide means a ensuring the correct position of the log tail prior to the discharge of the log onto the surface 65. In the example shown in Figs 1 and 2, this is achieved by means of a surface formed by a first, substantially vertical plate 101, and of a second, inclined plate 103. The plate 101 can be adjusted by means of screw means 105 and a handwheel 107 to take up such a position, with respect to the log in transit, as to always ensure (also in case of varying log diameter) that the tail L of the log is folded downwards. When the log R is discharged as shown in Fig. 3, the tail L rests on the inclined plate 103 and slides over it upwards while the log R rolls along the surface 65. Even though in the above-described embodiment guide means 95 are provided outside the conveyor 23 for causing oscillation of the cradles 41, in a modified embodiment it is possible to omit these guide means and replace them with guide means incorporated in the cradles themselves. For example, the side boards 42 of each cradle 41 can be connected to the relevant conveyor 23 not only with a pivot at 43, but also with a further pivot 150 engaging in a slit 151 of the side board itself. Such a slot 151 is shown in Fig. 2. If the first pivot 43 and the further pivot 150 engaging in the slot are connected to two different links of a chain forming the conveyor member 23, then a change in direction of the conveyor 23, such as the one caused by pulleys 27, 29, causes an oscillation of the side boards and thus of the cradles 41 connected to the conveyor. In this way, oscillation of the cradle 41 and discharge of the log is achieved without external guides 95, these being replaced by the guide formed by the pivot and slot arrangement in the flexible member and the side boards. Further modifications of the above-described apparatus are possible. Eg. wheel 49 can be omitted and cylinders 97, 99 can be synchronized with the movements of the cradles 41. As stated above, each log R is kept for a while between cylinders 97, 99, in order to seal the tail to the log. This is obtained by keeping the peripheral speeds of cylinders 97 and 99 at the same value for a while. Thereafter, cylinder 97 is allowed to rotate faster than cylinder 99, thus causing the closed log R to further roll toward the inclined surface 51. If the rotational speeds of cylinders 97 and 99 are made to vary in synchronism with the passage of cradles 41 in front thereof, the wheel 49 can be omitted, since distribution of the logs is achieved by suitably controlling the rotational speeds of cylinders 97, 99, e.g., by means of a central processing unit (not shown) or other suitable means.

Claims: A glue dispenser, including a tubular container (55) provided with means (61) defining an upwardly oriented longitudinally extending slit (63) from which the glue is dispensed, and means (91) for continuously feeding the glue to said tubular container (55) and, from this, to said slit (63), characterized in that the glue is made to continuously overflow from said upwardly oriented slit; that it comprises a storage tank (73) located beneath the tubular container (55), to collect the excess of glue continuously overflowing from said upwardly oriented longitudinally extending slit (63); that recirculating means (92, 94) are provided, for recirculating said excess of continuously overflowing glue from said storage tank (73) to said tubular container (55); and that said slit (63) is associated with means (23, 41, 65) for intermittently feeding the items to be glued. A glue dispenser according to claim 1, characterized in that the storage tank (73) is connected to a glue reservoir (93), in which the glue collected by said storage tank (73) is re-introduced for its subsequent feeding into the tubular container (55). A glue dispenser according to claim 2, characterized in that said reservoir (93) is disposed at such a level that the glue is made to flow out through the dispenser slit by the difference in height between the slit (63) and the glue level inside the glue reservoir (93). A glue dispenser according to claim 2, characterized in that pumping means (92, 94) are arranged between said storage tank (73) and said reservoir (93) or between said reservoir (93') and said tubular container, for recirculating said glue. A glue dispenser according to one or more of the preceding claims, characterized by means (83) for adjusting the position of the slit (63) from which the glue is fed. A glue dispenser according to one or more of the preceding claims, characterized by means (69, 71, 72) for adjusting the width of the slit (63) from which the glue is fed. A glue dispenser according to one or more of the preceding claims, characterized in that said slit (63) is defined by a pair of inclined plates (61) delimiting a wedge-shaped spout (59). A glue dispenser according to claims 6 and 7, characterized in that said inclined plates (61) are movable one with respect to the other to adjust the width of said slit (63.) A glue dispenser according to one or more of the preceding claims, characterised in that said slit (63) is arranged in alignment with a surface (65) on which the items to be glued are made to roll.

Inventors: BIAGIOTTI GUGLIELMO, BIAGIOTTI, GUGLIELMO
Applicants: PERINI FABIO SPA, FABIO PERINI S.P.A.
Application year: 1991
Main classification: B05C5
IPC codes: B05C5, B05C9