APPARATUS FOR GRIPPING AND CUTTING FILM USED FOR WRAPPING A PALETTISED LOAD

Abstract: An apparatus for holding and cutting film (1) comprises a unit (6) for gripping and tearing the film (1), located outside the profile of a platform (2) and designed to enable a portion of film of width (L1) between a stack (3) of products on the platform (2) and a film feed reel (4) to be intercepted after the stack (3) has been wrapped and to subsequently tear the portion of film (1) thus intercepted, acting in conjunction with a partial rotation of the platform (2).

Description: Description APPARATUS FOR GRIPPING AND CUTTING A FILM USED FOR WRAPPING A PALETTISED LOAD Technical Field The present invention relates to an apparatus for holding and cutting film used to wrap groups of products. In particular this 5 unit can be applied to machines for the semi-automatic wrapping of stacked products arranged on pallets for transportation of the stacks . 10 Background Art In the sector for the design and construction of machines for wrapping stacked products, manufacturers have, over time, used two different construction philosophies, which have led to 15 the definition of two types of machines, respectively automatic and semi-automatic. These two types originate from a similar basic structure which comprises a support platform for the pallet upon which the group of products to be wrapped rests, and a frame, at the 20 side of the platform, upon which a reel of film for wrapping the group of products is positioned. In the case of automatic machines, there are solutions which envisage a rotating platform and n which the reel only moves vertically up and down in order to unwind the f lm along 25 the group of products, or solutions with a fixed platform and a reel which moves vertically and is supported by an arm which rotates around the group of products . In semi-automatic machines, the first type of system described above for automatic machines is normally used, that is to say, with the rotating platform and a reel which moves n both directions along a vertical axis. These two machines basically differ in that the automatic machines can carry out a series of cycle start and end operations (for example, positioning the free edge of the film near the stack, cutting the f lm upon completion of wrapping and sealing the edge on the pack thus defined, etc.) using automatic devices and without the direct action of operators on the machine; n semiautomatic machines, on the other hand, operators are required n order to carry out these operations. Obviously, these differences mean that the automatic machines are very expensive, used only for high productivity and are top of the range, whilst the semi-automatic machines are economically better suited to companies with medium-small production levels. Disclosure of the Invention In order to bring the two types of machines closer together, the Applicant has designed a film cutting apparatus for machines of the semi-automatic type, with which it is possible to automate the film cutting operation without significantly affecting the cost of the machine and leaving the structure and functions of the current semi-automatic machine unchanged. The technical features of the present invention, in accordance with the above mentioned aims, are described in the claims herein, and the advantages of the invention are more clearly described in the detailed description below with reference to the accompanying drawings, which illustrate a preferred embodiment, and in which: Figure 1 is a schematic top plan view of a machine for wrapping groups of products, equipped with the holding and cutting apparatus made according to the present invention; Figure 2 is a schematic side view, with some parts cut away in order to better illustrate others, of the machine shown in Figure 1; Figure 3 is a view from D n Figure 1 of the apparatus disclosed; Figure 4 is a detail view from E in Figure 1 showing a part of the apparatus disclosed. With reference to the accompanying drawings, in particular, Figure 1, an apparatus 1 is used to hold and cut a length of plastic film 1 of width L (see Figure 2) used to wrap palletised groups of products. The machines that perform operations of this kind (particularly semiautomatic machines, although the apparatus disclosed is not restricted to machines of this type), basically comprise a platform 2 that rotates about its vertical axis Z and that supports on its surface P a group of products to be wrapped with the film 1, the platform 2 being rotated n the direction indicated by the arrow A in Figure 1 to form a wrapped stack 3. The film 1 is unwound from a reel 4, that rotates about its vertical axis Z', and that is supported by a frame (not illustrated since it is of known type) positioned near the platform 2. The frame moves up and down, carrying the reel 4 with it n such a way as to completely wrap the stack 3 in height . When wrapping of the stack 3 has been completed and the reel 4 is in the lowermost position, as shown n Figure 2, the cutting apparatus disclosed herein is activated. This apparatus comprises a unit 6 which grips and tears the film 1, this unit being located outside the profile of the platform 2, close to the edge of the platform itself and being designed to intercept a portion of film of width LI less than the total width L of the film 1 between the stack 3 and the reel 4 and to subsequently tear the portion of film 1, acting in conjunction with a rotational movement of the platform 2. The unit 6 comprises a main gripper 8 consisting of two arms 8a and 8b, the first being equipped with a blade 81 and the second with a pressure plate 8p designed to hold and gather the torn portion of film 1. In order to intercept and tear the film 1, the main gripper 8 comprises drive means 7 which act on the gripper m such a way as to grip the portion of film 1 by performing a first rotation through a defined angle a to a position where the gripper is substantially vertical (see dashed line and arrow Fl n Figure 2 and Figure 3) with the film 1 placed between the two arms 8a and 8b of the gripper 8, and a second rotation through a further angle 3 to a position where the portion of film 1 is gathered and the ma n gripper 8 is substantially horizontal and over the platform 2 (see continuous line and arrow F2 in Figure 2) . In other words, the mam gripper 8 initially lies outside the platform 2 (see Figure 2) so as not to interfere with the wrapping of the stack 3 and then rotated through a straight angle while the platform 2 is also appropriately rotated m such a way as to intercept and cut the portion of f lm 1 (as described in more detail below) . The numeral 9 indicates cam means located and operating between the drive means 7 and the ma gripper 8 in such a way as to hold the film 1 between the first and second arms 8a and 8b when the first and second rotations are performed n order to grip and gather the portion of film 1. The cam means 9 (see Figure 3 n particular) consist of a circular track 10 made on a drum 10T associated to a shaft 11 by which the ma gripper 8 is driven. In this track 10 there runs a cam follower roller 12 attached to the first arm 8a of the mam gripper 8 m such a way as to move the first arm from an idle position where the first arm 8a is away from the second arm 8b (as illustrated) to a working position (see arrow F3) where the first arm 8a is in contact with the second arm 8b in such a way as to grip and gather the portion of film 1. The above mentioned drive means 7 of the mam gripper 8 consist of a geared motor 13 connected, through the drive shaft 11, to the corresponding lower ends of the arms 8a and 8b forming the mam gripper 8. As clearly shown m Figures 1 and 2, the first and second arms 8a and 8b forming the mam gripper 8 have a first, straight portion 14 and a second, angled portion 15 that form a passage 16 which, when the second tearing off rotation is performed, is located close to the outer edge of the platform 2. The gap 16 is used, as described m more detail below, by means 17 for gripping and completely tearing off the portion of film 1 torn by the mam gripper 8. The means 17 for gripping and completely tearing off the portion of film 1, located between the gripping and tearing unit 6 and the reel 4, are associated to the outer edge of the platform 2 and act as an element for holding the film 1 unwound from the reel 4 during the further rotation of the platform 2 m the wrapping direction A. The gripping and tearing off means 17 (see Figure 4) comprise a secondary gripper 18 consisting of a fixed arm 19 attached to the platform 2 and a mobile arm 20 pivoted, at C, to the support of the fixed arm which acts as a stop. The free end of the mobile arm 20 is equipped with a roller 21 which comes into contact w th drive means 22 that act on the mobile arm m such a way as to move it away from the fixed arm 19 (see continuous line and arrow F4 in Figure 4) by rotating it about the pivot C n such a way as to intercept, between the two arms 19 and 20, the gathered portion of film 1 being held by the gripping and tearing unit 6. Spring means 23 act on the mobile arm 20 so that when the two arms 19 and 20 are moved away from the drive means 22, a rotation in the direction opposite to the previous direction (see arrow F5 in Figure 4) is performed in such a way as to stop the portion of film 1 between the two arms 19 and 20 by lowering the mobile arm 20. The above mentioned drive means 22 (see Figure 4 again) consist of a shaped profile 24 associated to the first arm 8a of the mam gripper 8 when it is in the tearing off position, that is to say, substantially horizontal over the platform 2. The special "Z" shape of the arms 8a and 8b is such that the secondary gripper 18 can intercept the shaped profile 24 thanks to the passage 16 formed by the arms 8a and 8b of the mam gripper 8 themselves (see also Figure 2) during the rotation of the platform 2: n this way, the secondary gripper 18 is opened and the portion of film 1 previously gathered by the mam gripper 8 can then be intercepted and gripped. To keep the gathered portion of film 1 tensioned in the interception area of the secondary gripper 18, there is a vertical idle roller 25 which is mounted on the unit 6 close to the mam gripper 8 m such a way as to tension the section of film 1 located near the interception area between the reel 4 and the ma gripper 8 when the latter is in the horizontal tearing position over the platform 2. In practice, the apparatus made in this way works m the following manner. When a group of products has been positioned on the platform 2, the latter is activated and the reel 4 moves along its vertical axis Z' in order to wrap the group of products. On completion of wrapping, the reel 4 is located at its lowermost point relative to the platform 2, in the position illustrated in Figures 1 and 2. The mam gripper 8 is now moved by the geared motor 13 to the vertical position where the two arms 8a and 8b are moved close together in such a way as to stop the portion of film 1 whose width LI is less than the total width L of the film 1. This starts tearing the film 1 and the tearing action is continued by rotating the platform 2 through a defined angle large enough to tear off the film 1 completely into two parts close to the gripping area of the gripper 8. Once the film 1 has been torn off, the gripper 8 turns to the second horizontal position over the platform 2, thus gathering the portion of film 1 and, if necessary, completing the tearing off action (if the previous rotation of the platform 2 was not sufficient to tear the film off completely) . Once this has been done and with the unit 6 and the platform 2 stopped n position, the wrapped stack 3 can be removed. After removal, another stack of products can be placed and the platform 2 rotated again (without creating interference between the group of products and the mam gripper 8) to enable the secondary gripper 18 to intercept and hold the section of film 1 stretched and gathered close to the mam gripper 8. It is now possible for the ma gripper 8 to move back to its rest position, outside the profile of the platform 2, and for another wrapping cycle to be started with the front end of the film 1 held by the secondary gripper 18. The wrapping cycle can be performed m this way to completion or, alternatively, the front end may be released when wrapping is at a certain point by stopping the platform 2 at a certain position, rotating the mam gripper 8 over the platform 2 (without intercepting the film 1) and moving the platform only just enough to lift the secondary gripper 18 by contact with the profile 24, thus releasing the end of the film 1. The mam gripper 8 is then rotated towards the outside of the platform 2 again and the wrapping cycle may continue. The invention achieves the preset aims through an extremely simple and economical apparatus that is very easy to use and that is safe and reliable in gripping and cutting the wrapping film. Furthermore, the aims are achieved without altering the basic structure of the machine but adding an additional feature which automates the working cycle of the machines without signif cantly increasing their price. The invention described can be subject to modifications and variations without thereby departing from the scope of the inventive concept. Moreover, all the details of the invention may be substituted by technically equivalent elements.

Claims: Claims 1. An apparatus for holding and cutting film (1) of width (L) used to wrap palletised groups of products in machines comprising a platform (2) that rotates about its vertical axis (Z) and that supports on its surface (P) a group of products to be wrapped with the film (1) to form a wrapped stack (3) by rotating the platform (2); the film (1) being unwound from a reel (4), that rotates about its vertical axis (Z 1 ), and that is supported by a frame located near the platform (2) and designed to move the reel (4) up and down in such a way as to completely wrap the stack (3) m height, the apparatus being characterised in that it comprises a unit (6) for gripping and tearing the film (1), located outside the profile of the platform (2) and designed to enable a portion of film (1) of width (LI) between the stack (3) and the reel (4) to be intercepted after the stack (3) has been wrapped and to subsequently tear off the portion of film (1), acting in conjunction with a partial rotation of the platform (2) . 2. The apparatus according to claim 1, characterised in that it comprises means (7) for driving the gripping and tearing unit (6), said means acting on the unit, which consists of a mam gripper (8) with two arms (8a, 8b), n such a way as to enable the ma gripper (8) to perform at least a first rotation through a defined angle (α) so that the gripper is substantially vertical and holds the portion of film (1) in a position such that the film (1) can be torn when the platform (2) is rotated, and a second rotation through a further angle (β) to a position where the portion of film (1) is gathered and the mam gripper (8) is substantially horizontal and over the platform (2) . 3. The apparatus according to claim 2, characterised in that it comprises cam means (9) located and operating between the drive means (7) and the mam gripper (8) in such a way as to grip the film (1) between the first and second arms (8a, 8b) when the first and second rotations are performed by the ma gripper (8) in order to hold and gather the portion of film (1) . 4) The apparatus according to claim 3, characterised in that the cam means (9) consist of a circular track (10) which is associated to a shaft (11) for rotating the main gripper (8) and within which there runs a cam follower roller (12) attached to the first arm (8a) of the mam gripper 8 in such a way as to move the first arm (8a) from an dle position where it s away from the second arm (8b) to a working position where it is in contact with the second arm (8b) in such a way as to grip and gather the portion of film (1) • 5) The apparatus according to claim 2, characterised in that the means (7) for driving the mam gripper (8) consist of a geared motor (13) connected, through a drive shaft (11), to the ends of the arms (8a, 8b) forming the mam gripper (8) . 6) The apparatus according to any of the foregoing claims, characterised in that the first and second arms (8a, 8b) of the main gripper (8) have a first, straight portion (14) and a second, angled portion (15) that form a passage 16 which is located close to the outer edge of the platform (2) when the second rotation is performed in order to gather the film. 7) The apparatus according to claim 1, characterised in that t comprises means (17) for gripping and tearing off the portion of film (1) between the gripping and tearing unit (6) and the reel (4), said means being associated to the outer edge of the platform (2) and being designed to grip the film when the platform (2) performs a further rotation. 8) The apparatus according to claim 7, characterised in that the gripping and tearing off means (17) comprise a secondary gripper (18) consisting of a fixed arm (19) attached to the platform (2) and a mobile arm (20) pivoted, at (C) , to the support of the fixed arm; the free end of the mobile arm (20) being equipped with a roller (21) which comes into contact with drive means (22) that act on the mobile arm (20) in such a way as to move it away from the fixed arm (19) by rotating it about the pivot (C) n such a way as to intercept, between the two arms (19, 20), the portion of film (1) being retained by the gripping and tearing unit (6); spring means (23) being provided to act on the mobile arm (20) so that when it is moved away from the drive means (22), a rotation in the direction opposite to the previous direction is performed in such a way as to stop the portion of film (1) between the two arms (19, 20) . 9) The apparatus according to claim 8, characterised in that the drive means (22) consist of a shaped profile (24) associated to a first arm (8a) of a mam gripper (8) when the latter is in a gathering configuration, that is to say, substantially horizontal and over the platform (2); and having an area or passage (16) allowing the secondary gripper (18) to move under the arms (8a, 8b) of the mam gripper (8). 10) The apparatus according to any of the foregoing claims from 1 to 6, characterised in that the gripping and tearing un t (6) comprises a vertical idle roller (25) mounted close to the mam gripper (8) and designed to tension the portion of film (1) between the reel (4) and the mam gripper (8) when the latter is in the horizontal tearing position over the platform (2) . 11) A method for holding and cutting f lm (1) of width (L) used to wrap palletised groups of products in machines comprising a platform (2) that rotates about its vertical axis (Z) and that supports on its surface (P) a group of products to be wrapped with the film (1) to form a wrapped stack (3) by rotating the platform (2); the film (1) being unwound from a reel (4), that rotates about its vertical axis (Z 1 ) , and that is supported by a frame located near the platform (2) and designed to move the reel (4) up and down in such a way as to completely wrap the stack (3) n height, the method being characterised n that, after the product stack (3) has been wrapped, it comprises the following steps: - intercepting and gripping a portion of film (1) of width (LI), positioned between the stack (3) and the reel (4) using a unit (6) positioned outside the profile of the platform (2); - tearing the film (1), close to the area where the film is being held by the unit (6), through tens on ng of the film between the stack (3) and the reel (4), or through partial rotation of the platform (2); - gathering the portion of film (1) using the un t (6) and positioning the portion close to the edge of the platform (2). 12) The method according to claim 11, characterised in that it comprises, after the gathering step, a further step of completely tearing off the portion of film (1) gathered by the unit (6), said tearing off action being performed by gripping means (17) located on the edge of the platform (2) .

Inventors: BETTINI RODOLFO, ROSSI BRUNO, BETTINI, RODOLFO, ROSSI, BRUNO
Applicants: BETTINI RODOLFO, ROBOPAC SA, ROSSI BRUNO, BETTINI, RODOLFO, ROBOPAC S.A., ROSSI, BRUNO
Application year: 2000
Main classification: B65B11
IPC codes: B65B11