The invention concerns a method and the associated apparatus for automatically fixing the tail end of a wrapping of extendable film provided on loads which are usually palletized by any type of wrapping machine, both of the so-called rotating-table type, where the load placed on the table is rotated about its central axis and the wrapping film is unwound from a distributor driven on a vertical shaft, and of the rotating-arm or ring type, where the load remains stationary, while the said film distributor is displaced parallel to the axis of the load and around the load itself.
At present there exist automatic apparatus which perform the said operation of automatically fixing the tail end of the wrapping film, with insertion of the tail end in a pocket created in at least one penultimate turn of the said wrapping. The known apparatus are constructionally complex, bulky and at the end of the cycle have a component which is still inserted inside the turn of film inside which the pocket has been formed and the tail end of the wrapping has been introduced, so that the working cycle of the wrapping machine must be slowed down in order to allow extraction of the said component. In order to avoid this drawback, the said component is sometimes designed with the possibility of pivoting about a bottom axis transverse to the path of the load, not perpendicular to this path, so as to be extracted automatically from the wrapping while the load moves away from the wrapping station. This solution complicates the apparatus in terms of its construction and, while the said component pivots downwards, its top end touches the wrapped load and may also damage it even if this end is rounded and is designed to be freely rotatable. In the known devices, insertion of the tail end in the pocket created in the film wrapping is generally performed by gripper means which at a certain point require the operation of air jets in order to retain the tail end inside the pocket while these gripper means open and perform the stroke for extraction from the said pocket. This solution complicates further the design of the apparatus and results in problematic and uncertain fixing of the tail end since it is not controlled positively for the whole of the fixing cycle.
The invention intends to overcome these drawbacks of the prior art with an apparatus as claimed in Claim 1 and the following dependent claims, based on the following proposed solution. During the last stages of the wrapping cycle, a straight member of suitable height is arranged along the side of the load and parallel to the latter, said member supporting longitudinally a conveyor which forms a closed loop and is driven on pulleys which are located at the ends of this member and one of which may be actuated by a command received from a small gear motor. When the said member is in the active position, along the side of the wrapped load, a section of its conveyor is directed towards the load while the other section is situated opposite and facing outwards. At least two teeth are fixed onto the said conveyor and at the start of each cycle are positioned at the opposite ends of the member in question. The working cycle envisages that at least one penultimate turn is wound onto the load and positioned transversely on the said straight member in the active position, so as to form a pocket inside this turn and it is envisaged that the portion of this penultimate turn which rests on the said straight member is shortened transversely towards one of its edges, by a tooth of the said conveyor, so as to free the space sufficient for arranging on the said straight member a section of a last turn of the wrapping film. In sequence, the tooth which previously had shortened transversely the said penultimate turn is actuated in the opposite direction so as to clasp transversely the last turn, push it so that it comes out of the member in question and insert and pull it into the pocket of the wrapping formed by the said penultimate turn, while in synchronism the same penultimate turn is pushed transversely by the other tooth in the same direction in which the last turn was pulled out and is made to pass over the said member and extend elastically on the wrapping in order to close the said pocket, while in synchronism the portion of the said last turn trapped inside the said pocket is cut by downstream means which also retain the new leading end of the film so as to then arrange it correctly with respect to the next load to be wrapped. At the end of the working cycle, the apparatus is brought into the horizontal rest position for starting the next cycle for wrapping a new load.
Further characteristic features of the invention, and the advantages arising therefrom, will emerge more clearly from the following description of a preferred embodiment thereof, provided purely by way of a non-limiting example, in the figures of the accompanying illustrations in which:
FIG. 1 is a perspective side view of the apparatus during a first working step;
FIG. 1
a shows details of the main component of the apparatus, viewed along the cross-sectional line A-A of FIG. 1;
FIG. 2 shows a side view of the apparatus during the step according to FIG. 1 and during the next step;
FIGS. 3, 4, 5, 6 and 7 are perspective views of the apparatus during the subsequent steps of its working cycle;
FIG. 8 is a plan view of the apparatus in the condition according to FIG. 5;
FIGS. 9 and 10 show frontally, with parts cross-sectioned and during subsequent working steps, the gripping and cutting unit which performs separation of the tail end of a wrapping from the new leading end of the film supplied by the distributor with the feed reel and which retains the said leading end for the start of the next working cycle.
In order to facilitate understanding of the invention, the description which follows is provided with reference to application of the apparatus to a rotating-table wrapping machine and in the final part of the present description it is indicated how it is possible to use the same apparatus on other types of wrapping machine.
In FIG. 1, T denotes the rotating table on which the palletized load C is arranged, said load being wrapped with spiral turns of extendable film supplied by a feed device which carries the reel B of extendable film and the usual means for pre-stretching the film and which is raised and lowered by suitable means in synchronism with rotation of the table and the load. In these types of machine, the apparatus is mounted along the side of the rotating table T and comprises a first straight member 1 which has a length for example greater (see below) than the width of the extendable film as it is supplied by the distributor with the reel B, a flat form and is directed with its edge towards the load C. The member 1 has a rounded upper form 101 and at this top end has a means 102 for driving at least one conveyor, for example a toothed belt 2, which travels guided inside a longitudinal groove 201 (FIGS. 1a, 2) of the said member 1 which at the other end has a toothed pulley 202 keyed onto the shaft of a small gear motor 3 which is fixed on the side of the same member 1. The gear motor 3 is in reality fixed onto one of the flanges of a U-shaped support 104 which, as can be seen from FIG. 3, forms the end of an arm 4 which is pivotably joined together at 5 with the side of the rotating table T and which with the other end is connected to a reciprocating actuator, for example to the rod of a fluid-pressure cylinder and piston unit 6 hinged with the base of its body to the said table T. By means of the action of the actuator 6, the member 1 may be brought from the lowered and horizontal rest position into the raised position directed upwards, as shown in broken lines and continuous lines, respectively, in FIG. 1.
According to a preferred embodiment of the invention, as shown in the detail of FIG. 1a, the outer side of the conveying belt 2 is coplanar with or slightly set back from the edges 301 of the longitudinal channel 201 of the member 1 inside which this belt travels in a guided manner and these edges 301 are suitably rounded and polished or in any case treated so as to have a low coefficient of friction, since the film must be able to slide on them, as will become clear from the remainder of the description. The conveying belt 2 has, fixed thereon, oppositely synchronized, at least two teeth 7, 7′ which are rounded both at the end and on the teeth, with a substantially L-shaped profile, and which at the start of each working cycle are positioned at the opposite ends of the member 1, as shown in FIG. 1. According to a constructional variant, not shown in the drawings, at least that tooth of the said teeth 7, 7′ which at the start of the cycle is positioned in the vicinity of the drive means 102 of the conveyor 2 may be provided with a T-shaped side profile since this tooth is required to perform opposite operations on the penultimate and last turn of the wrapping film, as can be seen in the remainder of the description.
In order to be able to fix the tail end of the film for wrapping the load C it is envisaged that in synchronism the member 1 mentioned above is brought from the horizontal rest position into the raised operating position so that a section of a penultimate turn S of the wrapping film supplied by the distributor with the reel B rests transversely on the outer edge of the said member 1, as shown in FIG. 1, such that a pocket Z inside which the tail end of the wrapping film can be inserted is formed between this penultimate turn and the wrapped load C (see below). In sequence, while the table T continues to rotate at a speed which is preferably less than the operating speed, the gear motor 3 is activated so as to lower the upper tooth 7 on the outer side of the straight member 1, as shown in FIG. 2, so that the portion of the penultimate turn S which rests on the member 1 is lowered by the said tooth 7 so as to free frontally the member 1 by an amount sufficient to allow a section of a last turn S1 of the wrapping film supplied by the distributor with the reel B to be rested transversely thereon, as shown in FIG. 3, and, when these conditions are achieved, the table T stops.
At this point of the cycle the operation of another component of the apparatus is envisaged, this now being described with reference to FIGS. 1, 3, 9 and 10. Parallel to the pivot 5, in a position situated between the latter and the distributor with the reel B for feeding the film, a second pivot 8 is envisaged, said pivot being longer than the pivot 5 and supporting the middle part of the forked and right-angled base 109 of a second straight member 9 for example with a box shape and the same base 109 is hinged via its free end with a reciprocating actuator 10, for example with the rod of a fluid-pressure cylinder and piston unit in turn hinged with the base of its body on the side of the table T, similar to the cylinder 6 considered above for the other component of the apparatus. The box-shaped member 9 has, mounted and fixed inside it, the body of a cylinder and piston unit 11, the rod 111 of which projects by a suitable amount from the said member 9 and has, fixed at the end, a jaw 12 for example in the form of an overturned cup. The body of the cylinder 11 projects from the box-shaped member 9 with a tapered and cylindrical portion 211, on which one end of a short cylindrical spring 13 is fixed for example by means of friction, alongside which spring the box-shaped body 9 has, fixed thereon, an extension of its edge with which it is intended to come into contact with the said last turn S1 of the wrapping film. This extension is, for example, formed by a round metal pin 14 which is welded to the body 9 and which terminates above the said spring 13 with a rounded end 114 slightly bent towards the rod of the cylinder 11. When the apparatus is in the rest condition, the member 9 described above is in the horizontal and lowered position as can be seen from FIG. 1, alongside the member 1 which is also in the rest position. After the step shown in FIG. 2, the straight member 9 is raised into the active position as can be seen from FIG. 3, so as to co-operate with the section of the last turn S1 situated between the film distributor with the reel B and the member 1, so that this last turn S1 makes certain and uniformly distributed contact with the said member 1, while the said turn S1 touches the said last member, partly on the body 9, partly on the extension 14 and partly on the rod 111 of the cylinder 11, as shown in broken lines in FIG. 9.
In sequence (FIG. 4), the reverse movement of the belt 2 is performed, so as to raise the tooth 7 which causes raising of the bottom edge of the last turn S1 and at the same time moves away from the penultimate turn S which extends elastically over the member 1. During this step, the last turn S1 is shortened transversely so that it is raised from the body 9, passes beyond the extension 14 and is arranged in contact with the rod 111 alone of the cylinder 11, as shown in continuous lines in FIG. 9. In sequence, as shown in FIGS. 5 and 8, the tooth 7 passes beyond the upper drive device 102 of the member 1 and insert the last turn S1 in the pocket Z formed by the penultimate turn S. During this step and during the next step shown in FIG. 6, where the last turn S1 is inserted fully inside the said pocket Z, a suitable quantity of film may be supplied tensioned by the distributor with the reel B. FIG. 6 shows how, while the tooth 7 inserts the last turn S1 inside the pocket Z, the penultimate turn S is gradually raised by the other tooth 7′ and is made to pass over the top end of the member 1, firstly with its upper edge which is arranged elastically in contact with the wrapped load, closing the upper mouth of the said pocket Z. In suitable sequence, retraction of the rod 111 of the cylinder 11 is actuated so that it grips the last turn S between the cup member 12 and the top end of the spring 13 and then compresses this spring as shown in FIG. 10 so as to retain firmly this last turn and cause the portion thereof facing the load to co-operate with a transverse cutting means 15 which consists for example of a sawtooth blade fixed to the top of the box-shaped body 9 and protected inside the extension 14 and which separates the tail end of the wrapping which is about to be completed from the leading end of the film supplied by the distributor with the reel B which is firmly held between the parts 12 and 13. In synchronism with the said operation for cutting the tail end and retaining the new leading end of the film, the tooth 7′ also causes the bottom edge of the penultimate turn S to pass over the member 1, so that the said turn S extends elastically downwards, adheres to the wrapped load C and closes the pocket Z inside which the tail end of the last turn S1 of the wrapping film remains firmly gripped. In order to ensure certain disengagement of the tooth 7′ from the tail end of the film, the said tooth 7′, in synchronism, is raised and brought into the start of cycle position. It is clear that in the apparatus and in the method according to the invention, the tail end of the wrapping film is controlled in a positive and certain manner for the whole of the fixing cycle, while ensuring that the same apparatus offers a high level of operational reliability.
In sequence, while the wrapped load moves away, the member 1 is pivoted downwards and the member 9 is also pivoted downwards, as already mentioned with reference to FIG. 1. The leading end of the film supplied by the distributor with the reel B is retained by the gripper unit 12, 13 which is closed and in the lowered position. When a new load has been positioned on the table T, after the latter has started the cycle for wrapping this load, when the first turn of the said wrapping film is suitably automatically fixed in position, the said gripper unit 12, 13 is opened with extension of the rod 111 and it is possible to envisage the operation of means—not shown in that known—which blow compressed air onto the section of the leading end of the film which would otherwise remain hanging from the load, so as to move it towards the load in such a way that it is incorporated in the next turns of the wrapping film.
The apparatus as described may also be used in rotating-arm wrapping machines or in ring machines and in this case will be positioned statically alongside the motor-driven rollerway which transports and positions correctly the load in the wrapping station. In ring machines, the said apparatus could be differently positioned on the structure which rotatably supports the ring, with an orientation overturned with respect to that shown, so as to be arranged along the path of the wrapping film only during the final stages of the tail end fixing cycle, all of which in a manner which can be deduced and easily realized by persons skilled in the art.
It is understood that the description refers to a preferred embodiment of the invention to which numerous variations and modifications, in particular of a constructional nature, may be made, these referring for example to the use of means other than the toothed belt 2, or to the use of at least two belts arranged alongside each other and each having one of the said teeth 7, 7′ mounted thereon and to the provision of movement means which allow the selective operation of the said teeth, for example couplings of the electromagnetic or other type which could obtain their movement from a single gear motor 3. In order to simplify the action of the various components of the apparatus and/or so as to be able to produce the same apparatus with smaller dimensions, the distributor with the reel B for feeding the film may be provided with known means which are to reduce the width of the film supplied for formation of the said penultimate turn and/or last turn S, S1.
Patent Grant
8099935
