CONVEYOR AND/OR ACCOMPANYING BELT

Abstract: A belt (1), suitably closed into ring-shape and carried around at least two turn-round and/or driving cylinders (2, 3), is made of plastics material, particularly of polytetrafluoroethylene, or the like, or it is constituted by a fabric, particularly of glass, impregnated and/or coated with plastics material, particularly with polytetrafluoroethylene. Both longitudinal edges of the belt have an enlarged guiding bead (6) resting on the edge (4) of each end face of the turn-round cylinder and/or driving cylinder (2, 3) or on an annular step of said cylinder, or engaging into an annular groove in said cylinder. The enlarged guiding bead (6) may be constituted by a flexible core (5) incorporated within the respective longitudinal edge of the belt (1), and particularly enwrapped by a marginal portion (101) of the belt (1) which is folded over around the core (5) and is secured to said belt (1).

Description: This invention relates to an endless belt carried around at least two turn-round and/or driving cylinders, and made of plastics material, particularly of polyetrafluoroethylene (PTFE, TFE), or the like, or made of a fabric of natural, mineral, or synthetic fibres, particularly of glass, or the like, impregnated and/or coated with plastics material, particularly with polytetrafluoroethylene (PTFE, TFE), or the like. Endless belts of this type are known from the former production of the Applicant, and may be used for any suitable purpose, for example, as conveyor belts, i.e., for supporting and conveying articles or materials, or as accompanying belts, i.e., for guiding and holding articles and materials being conveyed otherwise. In a preferred type of use of said belts, the latter are used as so-called sealing belts. In this case, a sequence of articles to be sealed, e.g. a sequence of packages provided with heat-sealable wrappers, are passed between two facing, generally vertical stretches of two endless belts of their facing stretches will move in the same direction and at the same speed as the interposed articles to be sealed, thus moving along with them with no rubbing therebetween during their movement. During the passage between the said belts, the said articles are subjected, with the intermediary of said belts, at first to a heat-sealing operation and then, if desired, to a cooling operation by means of heated plates and cooled plates, respectively, arranged at stationary positions on the outer sides of said facing stretches of the belts. In a different application, conveyance and sealing are performed by one single endless belt operated by horizontally positioned cylinders. Heretofore, in order to avoid any displacement of said belts with respect to their turn-round and driving cylinders, one edge of the belt, particularly the upper edge of a vertically-operating sealing belt, was reinforced by adhering a strip thereto, and at this reinforced marginal area, the belt was provided with a longitudinal sequence of positioning pivots equally spaced from each other. These positioning pivots are engaged in a corresponding annular groove formed in each of the belt turn-round and driving cylinders, thus preventing the belt from displacing axially of said cylinders. The application of the said positioning pivots, however requires time and labor and, therefore, increases the cost of said belts. Morever, the said positioning pivots add to the weight of the belt, and require the use of turn-round and driving cylinders of particular construction, i. e., provided with at least one annular groove. Moreover, guiding profiles are necessary for the belt to be supported along the stretches, where the said belt is running free over a straight path. The guiding or positioning pivots running on, or in, the said profiles, will cause a tiresome noise. The positioning pivots applied on the belt constitute points of structural discontinuity in the marginal area, which is therefore liable to an increased risk of rupture. From the document GB-A-1.083.536 a belt conveyor is known, comprising a belt having continuous longitudinal ribs along one face thereof and being supported by rollers with concavely curved treads arranged in spaced parallel rows, so that the longitudinal ribs in the belt engage the treads in the rollers. From the document GB-A-1.122.282 also a conveyor belt is known, for conveyors of the kind in which a conveyor belt is supported and frictionally driven by cables, and is provided with guideways associated with opposite faces of the belt, for locating the cables, and formed by longitudinally extending projections of the belt. From the document GB-A-2.054.507 a conveyor is known, comprising an endless conveyor belt of rubber or a similar material, which is guided over carrier rollers by means of beads provided in its edge regions and extending over its entire length. The beads bear through flat lower surfaces on the cylindrical peripheral surface of the rollers. The beads may be provided with incorporated cores forming pressure and/or tension-resistant inserts, which are firmly connected with the material of the belts. The object of the invention is to overcome the aforementioned disadvantages of the heretofore known belts, and the invention aims to simplify the construction of the said type of belts and to reduce the cost and weight thereof, by eliminating the said structural discontinuity of the edge, and by making the construction of the turn-round and driving cylinders simpler and more economical. This problem is solved by the invention in that each longitudinal edge of the belt has incorporated therein a flexible core which forms an enlarged guiding bead, and which is freely slidable with respect to the belt. Thus, an endless belt according to the invention, may rest via the thicker, i.e., enlarged guiding beads in its longitudinal edges on two associated annular steps formed on the turn-round and driving cylinders, so as to prevent the belt from displacing axially on the said cylinders, and as to maintain at the same time the said belt stretched in its transverse direction. This transverse stretching of the belt according to the invention, that can be obtained by virtue of the enlarged beads in its longitudinal edges, is particularly important and advantageous for the said sealing belts, which should be as thin as possible (to permit a better transfer of heat), but which should have at the same time no wrinkles or creases, in order to ensure a perfect heat-sealing. With an endless belt according to the invention, the turn-round and driving cylinders need not to be provided with annular grooves and the same may be thoroughly plain, the width of the belt and the length of its turn-round and driving cylinders being so matched with each other that the belt will rest by the enlarged guiding beads in its longitudinal edges against the preferably beveled edges of the two end surfaces of said cylinders. At the same time, the cores incorporated in the longitudinal edges of the belts according to the invention, will cause the said edges to be considerably reinforced, and will render the same more resistant to any stresses, particularly to tensile stresses in the longitudinal direction, whereby any risk of rupture of the said edges is reduced, and a uniform distribution of tensions on both sides of the belt, is achieved. In the meantime, the feature that the flexible cores forming the enlarged guiding beads in the longitudinal belt edges, are freely slidable with respect to the belt, affords the advantage of allowing different elongations of the cores and the belt, due to thermal expansion or mechanical stresses. The said slidable flexible cores may be incorporated into the respective longitudinal edges of a belt according to the invention, in any suitable manner such as, for example - according to one preferred embodiment of the invention, by folding the marginal portion of at least one longitudinal edge of the belt around the respective core, and securing the same to the belt by stitching and/or glueing and/or sealing (claim 2). According to another embodiment of the invention, the slidable flexible cores are incorporated into the respective longitudinal edges of the belt by rolling the marginal portion of at least one longitudinal edge around the respective core, so that a curl is obtained, which is fixed either by glueing or by sealing (claim 3). According to a further embodiment of the invention, the slidable flexible cores are incorporated into the respective longitudinal eages of the belt by threading the core, either before or after closing the belt into ring-shape, into a respective tubular cavity formed along the corresponding longitudinal edge of the belt (claim 4). Other advantageous embodiments of the belt according to the invention, as well as of the combination of this belt with turn-round and/or driving cylinders, are defined in dependant claims 5, 6 and 7 and in claims 8 to 10, respectively. Some embodiments of the invention will be described hereinafter with reference to the accompanying drawing, wherein: Fig. 1 is a perspective and partly sectional view of an endless belt according to the invention, mounted on two turn-round rollers. Fig. 2 is an axial sectional view, on an enlarged scale, of one of the turn-round rollers of Fig. 1, and of the belt mounted around said cylinder. Fig. 3 shows a possible embodiment where a flexible core is incorporated in the longitudinal edges of the belt. Fig. 4 is a part sectional view similar to that of Fig. 2, showing the end edge of a turn-round cylinder, with another embodiment of the respective longitudinal enlarged edge of a belt. With reference to the Figures, the numeral 1 indicates an endless belt which may be made of a sheet of any plastics material, particularly of polytetrafluoroethylene, or the like, or which may be made of a fabric of any material, particularly of glass fibres, or the like, impregnated and/or coated with any suitable plastics material, particularly with polytetrafluoroethylene, or the like. The belt 1 is mounted around at least two turn-round cylinders 2 and 3, one of which may be powered so as to act as a driving cylinder. The cylinders 2, 3 are of plain configuration, and they only have a bevelling 4 at their end edges. In the illustrated embodiment, the axes of the two turn-round cylinders 2, 3 and therefore the planes of the two stretches of the belt 1, are substantially vertical, but obviously they may be, as an alternative, either horizontal or at any angle. Of course, the belts according to the invention may be used as well in a horizontal position and also individually for example, as conveyor belts or as conveyor and sealing belts. The two longitudinal edges of the belt 1 are so enlarged as to form, each, a guiding or positioning bead 6. In the embodiment illustrated in the Figs. 1 and 2, the enlarged guiding bead 6 of each longitudinal edge of the belt 1 is obtained by incorporating into the respective edge of the belt 1 a flexible and tension-resistant core 5. For this purpose. the corresponding marginal portion 101 of each longitudinal edge is folded around the core 5 and is secured to the belt 1 in any suitable manner, particularly by stitching and/or glueing and/or sealing. The core 5 of the enlarged bead 6 of each longitudinal edge of the belt 1 extends over the entire length of the belt l and, preferably, it is also of closed ring configuration similarly to said belt. Said core 5 may be made of any suitable material which - when the marginal portion 101 of the belt 1 is sealed and/or when the belt 1 is subjected to a thermal action such as when it is used as a sealing belt - should also be resistant to said heat. Thus, for example, the core 5 may be constituted by a flexible rod of plastics material or by a small string or cable of natural, mineral or synthetic fibres, particularly of glass or glass fibres. In a possible modified embodiment, the core 5 may be constituted by a small cable of coiled steel wire, as shown in Fig. 3. This embodiment facilitates the junction of the two ends of the flexible core 5 when it is closed into a ring configuration. In the embodiment of Fig. 4, the enlarged guiding bead 106 at each longitudinal edge of the belt 1 is obtained by rolling the respective marginal portion of the belt 1 transversely to said belt and by securing the curled bead thus obtained in any suitable manner, for example, by sealing or glueing its turns to each other. Said marginal portion of the belt 1 may be rolled, similarly to the illustrated embodiment, also around a core, e.g. around a wire of any metal or any other suitable material. Said core may remain incorporated within the curl thus obtained, or it may be unthreaded therefrom, e.g. after its consolidation, thus forming an enlarged tubular curl-shaped bead. The width of the belt 1 is selected depending upon the length of the turn-round cylinders 2, 3 so that the belt 1 will rest with its enlarged guiding beads 6 or 106 or both its longitudinal edges against the beveled edges 4 of the respective end surfaces of said turn-round cylinders 2,3, as shown particularly in the Figs. 2 and 4. The belt 1 is thus effectively prevented from displacing transversely, i.e. from displacing in the axial direction of the leading cylinders 2, 3, and the belt 1 will be maintained stretched and straight also in its transverse direction. Instead of resting against the end edges 4 of the turn-round cylinders 2, 3, the enlarged guiding beads 6, 106 of the longitudinal edges of the belt 1 may rest against corresponding annular steps formed peripherally on the turn-round cylinders 2, 3 or they may engage into corresponding annular grooves formed in said guiding cylinders 2, 3. In a further possible embodiment, each guiding cylinder 2, 3 is formed on at least one and possibly on both ends thereof with two or more peripheral annular grooves so that it can be used with belts 1 of different width, each of which is engaged by means of the enlarged guiding bead of its longitudinal edges in one of the two or more corresponding annular grooves or on a step or on the edge of the respective end surface of the cylinder. This provision permits to use belts of different widths on the same turn-round and/or driving cylinders.

Claims: An endless belt (1) carried around at least two turn-round and/or driving cylinders (2, 3), and made of plastics material, particularly of polyetrafluoroethylene (PTFE, TFE), or the like, or made of a fabric of natural, mineral, or synthetic fibres, particularly of glass, or the like, impregnated and/or coated with plastics material, particularly with polytetrafluoroethylene (PTFE, TFE), or the like, characterized in that each longitudinal edge of the belt (1) has incorporated therein a flexible core (5) which forms an enlarged guiding bead (6), and which is freely slidable with respect to the belt (1). A belt according to claim 1, characterized in that the marginal portion (101) of at least one longitudinal edge of the belt (1) is folded around the respective core (5), and is secured to the belt (1) by stitching and/or glueing and/or sealing. A belt according to claim 1, characterized in that the marginal portion of at least one longitudinal edge of the belt (1) is rolled transversely to said belt (1) around the respective core (5), so that a curl is obtained, which is fixed either by glueing or by sealing. A belt according to claim 1, characterized in that the said core (5) is threaded, either before or after closing the belt (1) into ring-shape, into a respective tubular cavity formed along the corresponding longitudinal edge of the belt (1), A belt according to claims 1 to 4, characterized in that said core (5) is made of a material capable of resisting the tension and heat to which the belt (1) is subjected, and is constituted by a flexible rod of plastics, a small string or cable of natural, mineral, or synthetic fibres, particularly of glass, or the like. A belt according to claims 1 to 4, characterized in that the said core (5) comprises one or more steel cores, particularly one coiled steel wire. A belt according to claims 1 to 6, characterized in that said core (5) is closed on itself into ring-shape. Combination of a belt, according to any of claims 1 to 7, with turn-round and/or driving cylinders (2, 3), characterized in that the width of the belt is so matched with the length of the turn-round and/or driving cylinders (2, 3) that the enlarged guiding beads (6, 106) in the two longitudinal edges of the belt will rest against the preferably beveled edges (4) of the said cylinders (2, 3). Combination of a belt, according to any of claims 1 to 7, with turn-round and/or driving cylinders (2, 3), characterized in that said turn-round and/or driving cylinders (2, 3) are formed with at least two axially spaced annular steps or anular grooves, and the width of the belt (1) is compatible with the distance between these steps or grooves, so that the enlarged guiding beads (6, 106) in the two longitudinal edges of the belt will rest each against a step, or will engage each into a groove in said cylinders. Combination of a belt, according to any of claims 1 to 7, with turn-round and/or driving cylinders (2, 3), characterized in that the enlarged guiding bead (6, 106) in one of the longitudinal edges of the belt (1), rests on an annular step in the turn-round and/or driving cylinder (2, 3), or on the edge of an end surface thereof, and the enlarged guiding bead (6, 106) in the other longitudinal edge of the belt (1) engages into an annular groove in cylinder (2, 3).

Inventors: SANSONE, GIORGIO
Applicants: FIRIE DI GIORGIO SANSONE S.A.S.
Application year: 1988
Main classification: B65G15
IPC codes: B65G15