Mechanism for wrapping machines with film

Abstract: The improvements are done over one of the mechanism that form the machines used to wrapp objects or articles by using a film sheet from a reel. Specifically introduced in the mechanism that adjust the to and fro movement of a connecting rod that limits, the length of the film share to be used as a wrapper of each article or product. With regard to the mechanism that is presented with the improvements of the invention, the connecting rod (6) does a to and fro movement, from the swinging movement of a lever (1) that is set off by a cam (2), for which the connecting rod (6) has a lateral part (8) with a pulley wheel (9) that runs along the groove (10) that is part of the guide (11), that has an articulation (12) that is joint to the chassis (13) of the machine, in such a way that the adjustement in a swinging position of that guide (11) means the limitation of the to and fro movement of the mention connecting rod (6) and consequently of the mechanism that connected to this rod will carry on the drive and sectioning of the film to be use as a wrapper.

Description: OBJECT OF THE INVENTION The invention relates to a mechanism that adjusts and control the length of the film to be used for each type of product, mechanism that is part of the wrapping machine. With the mechanism that constitutes the improvements object of this invention, the connecting rod gains a to and fro movement, within predetermined limits which will provide the length of film necessary to wrapp up the product or article, being connected to the rod that has been provided with the to and fro movement, are the mechanisms in charge of holding and driving the film sheet that comes out of a reel. BACKGROUNDS OF THE INVENTION To carry on the operations, the wrapping machines with film have a lot of mechanisms, between those, is our purpose to mention the one in charge of determining the amount of film that is needed in each different process, depending of the product that is going to be wrapped up. On the European Patent EP-A-0092758, which priority corresponds to U.S. Patent number 371892, between other parts from wrapping machines with film, it is claimed a to and fro mechanism that can be adjusted by the size of the product to be wrapped, based on a lever jointed by one of its ends to a lower plate, while in the upper end is a jointed connecting rod with curved shape, that by one of its ends is linked to a tensor that by its other end moves through a pivot, in an arched slot found in the lower plate, being forecast that the original lever, that is jointed to the chassis of the machine, will have a lateral pivot linked to a cam which turn produces the swinging and/or the to and fro movement of that lever, and in consequence to the swinging of the curved rod, and establishing on the end a tensor that joints the holding mechanisms for the end of the film, with the purpose of driving it and to perform, with other apropiate mechanisms, the wrapping, cutting and other operations that take place inside of the machine as a whole. The lower plate equipped with the curved slot on wich the lower end of the tensor moves is jointed to a mechanism of longitudinal modification of the mention plate, and so of the tensor placement, in such a way that when the tensor changes, the top position on which the curved connecting rod moves also changes and so its to and fro movement, changing with it the distance of the sheet of the film. It must be considered that the adjustment of the length of the curved end of the curved connecting rod will be realized when the length of the film must be changed, because it requires to wrapp up a new product. In that sense, the mechanisms of the transmissions of the adjustements mentioned, will only act when the length of the film must be changed, to wrapp up another new product. DESCRIPTION OF THE INVENTION The object of the invention, based on the mechanism mentioned before, presents as a new feature some improvements that come up with a simplification of the mechanism, a better functioning and so, a greater safety in the general functioning of the machine. Specifically, the mechanism built with the improvements of this invention has the purpose of a to and fro movement, with the particularity that the to and fro movement could be adjusted to give a movement to the driving mechanism of the film sheet that comes out of a reel, driving that as explained before is done at the moment of catching the film by it's sides and pulling from it to the forecast course by the mechanism, when it reaches the end of the course, another mechanism produces the cutting of the sheet, the wrapping of the product and the thermo-sealing of the mention wrapping of film. On the realization of the mechanism of the invention, the connecting rod to which the to and fro movement is transmited, can be moved along the slot that belongs to a intermediate part over which it articulates. In such a way that the part over which the rod could perform its to and fro movement, form a guide that by one end is jointed to the structure or general chassis of the machine and by the other end to an arm, in a way that the adjustment of the mechanism that limits the lenght of the film, is able to vertically move a lever articulately jointed that gives a greater or less drive to the connecting rod in its to and fro movements transmited through the lever, link to the general starting cam. The thin tensor rod could be replaced with a rack that is part of the guide piece, and in which rack is in gear with a pinion that is activated by an engine, all of it with the purpose of achiveing a greater or less tabulate inclination of the guide to reach a different top for the maximum drive of the to and fro movement of the connecting rod. Obviously this solution can be changed by any other apropiate one. In consequence, the adjusting mechanism could be activated by a cam and be jointed to a lever, to which could be also jointed a pneumatic cylinder, in a way that with such pneumatic cylinder the drive of the connecting rod could be changed, on small values (small distances and very tabulated) to allow to make small changes on the lenght of the film in the case of the film already print and so to obtain the adjustment on the printing centre of the article to be wrapp up, while when the purpose is to wrapp a different product the engine that makes an arch to turn to the cam of the adjustment mechanism will be precisely activated, changing the position of the thin tensor rod as well as the position of the guide. This way, the variation of the position, on the swinging of that guide will change the position of the correspondent rod, in relation with its drive end of the to and fro movement, varying the lenght of the film sheet to wrapp a new product to be packed. It must be taken into account that, as we had already explain, the film placed into the reel can be printed, with the printout of signals on the ends of the film with the purpose of been controlled by a photocell. But it is possible that the signals will be modify or do not coincide with the said photocell, and this will cause the decentration of the print on the tray of the wrapper. For that purpose it is required to appreciably modify the drive of the to and fro movement, with that purpose it has been forecast the possibility of placing a pneumatic cylinder that being jointed to the tensor thin rod by one of its ends, and to the articulation lever, by the other end, in order to move the mentioned thin rod, in a precise way and with small distances, altering the end of the to and fro movement path of the rod that is going to work over the mechanisms that take hold of the film sheet. Finally the fact that the lever that is activated by the cam has an arm or lateral emergency over which a rack engages in a pinnion has been forecast, which is in charge of transmiting a simillar to and fro movement for the realization of the other machine operations, as for example, the bending of the film over the object to be packed. DESCRIPTION OF THE DRAWINGS In order to provide a fuller description and to contribute to the complete understanding of the characteristics of this invention, a set of drawings is attached to the specification which, while purely illustrative and not fully comprehensive, show the following: Figure 1.- Shows a schematic representation of the side elevation view of the mechanism that constitute the improvement object of this invention. Figure 2.- Shows one alternative of the realization of the mechanism presented on the prior figure. PREFERRED EMBODIMENT OF THE INVENTION As is shown on the figures, and specifically on figure 1, the mechanism that is being praised realized accordingly to the improvements of the invention, is constituted from a lever (1) that is activated by a cam (2) because the mentioned lever (1) counts with a lateral pivot (3) that moves into the groove of the mentioned cam (2). The lever (1) is supported and articulated by its lower end (4), while by the upper end (5) articulates with a rod (6) that in its free end articulates an element (7) jointed to a mechanism which takes hold of the film that comes from the reel and carries on the wrapping of any object or packing. That rod (6), has a lateral part (8) with a pulley wheel (9), that is moveable by the inside of a groove (10) that belongs to a part that acts as a guide (11), this last piece is articulated by one of its ends (12), to the general chassis (13) of the machine, while by the other end recieve the articulation of the thin tensor rod (14) that by its lower end can be linked to a pneumatic cylinder (15), which is placed over an articulated support (16) to an activating arm (17), which has a lateral bolt (24) that is alocated inside of the cam (25) and that recieves the activation by the turn of an engine (26). The lever (1) counts with a lateral arm (18) over which the rack (19) is mounted, this rack (19) gears a pinnion (20), that through appropriate transmission could provide the to and fro movement to the elements and mechanism intended to realize other types of operations of the packing machine, like the bending of the film over the object to be packed. The figure 2 shows a realization form of the same mechanism, but on which the thin tensor rod (14) has been changed and in its place there is a rack (21) that form part of the guide's end (11), rack that gears a pinnion (22) activated by an engine (23), allowing the variation, in swinging, the placement of the guide (11), because in any of either cases the purpose is that through the cam (2), and after the activation of the lever (1), to carry on the to and fro movement of the connecting rod (6), as a consequence that this movement of the lever (1) the pulley wheel (9) runs by the groove (10) of the guide (11), and depending of the possition of this last one it will obtain one top or the other of the path of that rod (6) in its to and fro movement, and so, therefore the lenght of the path of the mechanism jointed to the rod (6) must be which provides the necessary lenght in each case, or what is the same for each product. On figure 2 it can be observe how the end of articulation (6') of the rod (6) for the element (7), presents each of its limits of its path, depending logically of the possition during swinging of the guide (11), all of it mark on the discountinued line on the figure 2.

Claims: Mechanism designed to adjust the limits of the path of a connecting rod in a to and fro movement, based on the swinging of a lever (1) activated by a cam (2), that lever (1) being supported and articulated by its lower end (4) on the general structure of the machine and linked to the cam (2) through a lateral pivot, and the lever (1) linked by the opposed end to the rod (6), through articulation means (5), to perform the to and fro movement of the rod, characterized in that the mechanism has the capacity of determining the to and fro movement of the mentioned rod (6), by a lateral elongation (8) of the rod (6) with a pulley wheel (9) capable of running along a groove (10) that belongs to a piece that acts as a guide (11), which is articulated by one of its ends (12) to the general structure of the machine (13), such guide (11) being associated with positioning and swinging adjustment features of the guide to determine the path of the rectilinear to and fro movement of the rod (6). Mechanism as in claim 1, characterized in that the positioning adjustement features of the guide (11) are formed by a thin tensor rod (14), articulated by its end to the mentioned guide (11), being moved, the tensor rod (14), by the push of the lever (17), being at the same time, equipped with the resources for its vertical swinging movement, resources that could be in the form of providing to the mentioned lever (17) with a bolt (24) that will be placed laterally inside of cam that is controlled by an engine (26). Mechanism as in claim 2, characterized in that the adjustment of the film length in a tabulated way and in small strokes can be realized placing between the thin tensor rod (14) and in the articulation with respect of the lever (17), a pneumatic cylinder in charge of changing the length of the lever (14) with the consequent relative movement of the guide (11), in order to obtain the desire centre when the film sheet is printed at the time of being place over the tray or article of the wrapp. Mechanism as in claim 1 characterized in that the activating lever (1) is capable of incorporating a lateral arm (18) with a rack (19) that engages with a pinnion (20) that activates a transmission to provide movement for the elements of the machine that are forecast for other purposes. Mechanism as in claims 1 and 2, characterized in that the adjusting resources of the swinging placement of the guide (11) are formed by a determinant sector of a rack (21), shaped on the end of such guide (11), in which rack (21) engages a pinnion (22) activated by an engine (23), statically assembled on the general structure of the machine.

Inventors: ERRASTI IRIARTE IOSU, ERRASTI IRIARTE, IOSU
Applicants: ULMA S COOP, ULMA, S.COOP. LTDA.
Application year: 1993
Main classification: B65B57
IPC codes: B65B57, B65B11