ADJUSTABLE GRIPPER FOR CONTAINERS, IN PARTICULAR FOR A STAR CONVEYOR

Abstract: The invention relates to a gripper (3) in a star conveyor (1) for containers (2) comprising means (17, 18, 8) for adjusting the gripper (3) and the adaptability to containers (2) of different diameter, which are formed so as to co-operate with means (9, 10, 11) for moving the gripper so that the adjusting means provide, depending on their position, a plurality of basic configurations for the gripper (3), each suitable for particular diameters of the containers (2) to be processed, while the moving means perform, for each of said basic configurations, opening and closing of the gripper (3) so as to grip or release individual containers (2).

Description: 1 ADJUSTABLE GRIPPER FOR CONTAINERS, IN PARTICULAR FOR A STAR CONVEYOR TECHNICAL FIELD AND BACKGROUND ART The present invention relates to an adjustable gπpper for containers, m particular for a star conveyor In the sector of bottling plants, during the transfer of the containers entering and leaving machines such as filling machines, πnsing machines and labelling machines, it is known to use star conveyors provided w th recesses for containing and transporting the containers PET containers are normally conveyed supported by their projecting collar, while glass containers require a support underneath their base and are retained laterally on the body One of these conveyors is illustrated in DE 29501897 which shows a star conveyor for containers, provided with a plurality of peripheral recesses which contain jaws which open and close with movements in a horizontal plane performed by an actuating device compπsing a cam rotatable between the counter-arms of the jaws so as to separate them or allow their movement towards each other in the presence of a recall spring which tends to bias the jaws nto the open position In this star conveyor, individual recesses may be replaced, but the device operating the j aws is particularly complex Adaptation, where required, of the star wheel m order to process containers of different sizes is also complicated WO 94/16976 discloses a star conveyor provided with a plurality of peripheral recesses for transportation of containers, one for each recess, with the aid of an external guide and a bottom support surface on which the containers rest and are conveyed In this case the recesses cannot be replaced individually since formed on the same disk Adaptation of the conveyor to different sizes of container is simplified with respect to the preceding case, although the adaptation operations are still somewhat laborious since it is necessary to adjust the external guide as well. EP-A-0743267 illustrates a star conveyor provided with grippers formed by two jaws, the opening and closing movement of which is adjusted by means of an eccentric cam which acts on the counter-arms of the jaws and is provided with several self-locking positions, each associated with a particular opening position of the jaws. However, these grippers, when the opening position is changed, also vary their operating range and are unable to remain operative along the pitch diameter of the star conveyor, adversely affecting correct operation thereof. One of the main problems of the star conveyors of the known art is that of the need for complex operations in the event of a change in the size of containers to be processed, as well as the difficulty of access in the event of cleaning and maintenance operations. Another star conveyor is known from the patent EP 0629569 of one of the Applicants, which refers, however, to the processing of PET containers with a projecting neck and in any case requires an external guide for the containers. This patent describes the possibility of adjustment of peripheral recesses of the star wheel by means of a mutual rotation of two disks arranged on top of each other, with a particularly simple and effective operating device. DISCLOSURE OF INVENTION. The object of the present invention is that of eliminating the abovementioned drawbacks and providing a gripper which is constructionally simple and low-cost and which allows processing, in an optimum manner, of containers of different sizes without requiring complex adaptation operations. A further object is that of allowing, when applied to a star conveyor, operation of the star conveyor as a sorting device for deviating the incoming containers towards more than one exit path, according to the requirements (for example so as to sort quality-approved containers from containers which must be rejected). Another object is that of avoiding the use of guides or external counter-guides for retaining the containers inside the star conveyors, so as to avoid further adjustments in the event of a change in size of the containers to be processed and so as to reduce the costs of cleaning the base of the machine, increasing at the same time the accessibility to operators. Another object is that of being able to combine two or more star conveyors, arranging them so that they are at the same height and are not offset with respect to one another. Said objects are fully achieved by the adjustable gripper according to the present invention which is characterized by the contents of the claims indicated below and in particular by the fact that it comprises means for adjusting the grippers and the adaptability to containers of different diameter, which are formed so as to co-operate with the means for moving the grippers so that the adjusting means provide, depending on their position, a plurality of basic configurations for the grippers, each suitable for particular diameters of the containers to be processed, while the moving means perform, for each of said basic configurations, opening and closing of the grippers so as to grip or release individual containers. The container gripping operation occurs along the pitch diameter of the star conveyor with which the gripper is associated. The moving means comprise for example a support which has, fixed to it, the gripping elements of the gripper and at least one roller travelling in a cam rotating integrally with the star conveyor. Said support is movable radially on a pin as a result of the rotational movement of the star conveyor. The gripping elements comprise preferably two gripping elements acting on one side of the container and a third gripping element acting on the opposite side and positioned at an intermediate height between the two gripping elements and formed so as to be arranged between the bottom level of the upper gripping element and the top level of the lower gripping element. The adjusting means comprise, for example, a vertical pin which is fixed at the bottom to a transverse pin movable radially in the star conveyor; a shaped profile followed by the vertical pin by means of resilient compensation means and provided with a plurality of inclined surfaces or ramps which are equal in number to the grippers associated with the star conveyor. The displacement of the vertical pin on the shaped profile towards the outside or towards the inside of the star conveyor causes respectively a greater degree of opening or a smaller degree of opening of the gripping elements of the gripper and allows gripping of containers of predefined size always along the pitch diameter of the star conveyor. BRTEF DESCRIPTION OF DRAWINGS. These and other characteristic features will emerge more clearly from the following description of a preferred embodiment illustrated, purely by way of a non-limiting example, in the accompanying plates of drawings in which: - Figure 1 shows a vertically sectioned view of the gripper applied to a star conveyor; - Figure 2 shows the profile of a positive cam of the star conveyor according to Figure 1 ; - Figures 3 and 4 show respectively a vertically sectioned view and a plan view of the gripper; - Figure 5 shows a plan view of the gripper operating stages indicated by the letters A, B, C, D, E, and F; - Figures 6A, 6B and 6C show a plan view of the gripper configured for three different increasing diameters of the containers to be processed; - Figure 7 shows a plan view of the combined arrangement of two different star conveyors provided with grippers. BEST MODE FOR CARRYING OUT THE INVENTION. With reference to the Figures, 1 denotes in its entirety a star conveyor for containers 2 which may be made of glass or plastic material such as PET for example. The conveyor 1 is provided with a plurality of grippers 3 on its external periphery, each of which is intended to grip and release individual containers. Each gripper 3 comprises gripping elements 4 consisting of thin plates 5 of music steel lined with a sheathing 6 of plastic material and forming the jaws of the gripper. The plates 5 are fixed to the same pin 7 movable radially and provided with a front spring 8. 9 denotes a positive cam (a section of which is shown in detail in Figure 2) and in which a pair of rollers 10 travel, said rollers being attached to a vertical support 11 to which the grippers are also fixed. The vertical support 11 may slide radially on the pin 7. For each gripper 3 the conveyor 1 comprises a pin 7 and a cam portion 9 such as that illustrated in Figure 2. 12 denotes a three-hinged arch which connects together the plates of the gripping elements. Each plate, in fact, has, associated with it, a small pin 13 supporting a small link bar 14, the other end of which is attached to a central pin 15 which passes through the pin 7 and is integral therewith, so that the radial movement of the pin 7 towards the outside or towards the inside of the conveyor 1 causes, for the same positioning of the support 11, a variation in the opening of the gripping elements, depending on the position of the three-hinged arch. The gripping elements are kept normally in the closed position by means of a pair of spπngs 16 which form resilient means for connecting together the gripping elements 4 The gripping elements are three in number m the case shown, two being positioned so as to grip the container on one side and the third being positioned so as to grip the container on the opposite side and being arranged heightwise so that the third gripping element is located at an intermediate height between the levels of the two other elements so as not to create interference during the possible combination of several star conveyors provided with grippers according to the present invention, as shown m Figure 7 17 denotes a vertical pm which is fixed to the pin 7 and which forms, together with a shaped profile 18, eyelet 19 and spring 8, means for adjusting the grippers and the adaptability to containers of different diameter The vertical p 17 has a front compensating system consisting of the spπng 8 (which also provides compensation for the pm 7 and the cam 9 and forms resilient compensating means) and a rear abutment formed by the shaped profile 18 compπsmg as many inclined surfaces or ramps as there are grippers or peπpheral recesses of the star conveyor The shaped profile 18 is normally integral with the star conveyor 1 and rotates together therewith, but when there is a change in the size of the containers to be processed, said profile ma) be rotated so as to produce the simultaneous radial displacement, towards the outside or towards the inside, of all the vertical pins 17, thus allowing the simultaneous adjustment of all the grippers As shown in Figures 6A, 6B and 6C, varying the position of the vertical pin 17 inside the eyelet 19 causes a vaπation in the basic distance between the central pm 15 of the three- hinged arch and the support 1 1 of the grippers, so that a reduction in this distance results in a smaller degree of opening of the grippers themselves, but m particular the vaπation in position of the vertical pin 17 enables the gripping action of the grippers to be maintained along the pitch diameter of the star conveyor (the pitch radius is indicated by 7 20 in Figure 6), independently of the diameter of the containers. Basic adjustment is performed by sliding the pin 7 with respect to the support 11, by means of operation (rotation) of the shaped profile 18, which has a plurality of steps or ramps equal in number to the grippers which are mounted on the star conveyor. Further sliding of the support 11 with respect to the pin 7 occurs during the operating cycle of the grippers (as shown in Figure 5 in the successive steps A to F) so as to control the opening and closing movements of the grippers: this is performed by means of the cam 9, the profile of which produces the radial displacement of the support 11 on the pin 7 during rotation of the star conveyor about its central axis of rotation. Essentially, the vertical pin 17 provides a basic setting for the opening and closing movements of the grippers which are then adjusted by the cams 9, the rollers 10 and the support 11. The basic setting is intended both for the adaptability to the various diameters of the containers to be processed and for obtaining limitation of torque during closing of the grippers so as to be able to process also containers which are fairly pliable without crushing them or deforming them. In fact, in the case, for example, of glass containers where the container is frequently affected by the phenomenon of ovalisation (namely errors of about 2-3 mm in the container diameter), the vertical pin 17 is set so that the support 11 does not come into contact with it, but remains at a distance of a few millimetres, while in the case of PET containers (which have a more precise diameter) the basic adjustment is performed so that, during gripping of the container, the support 11 is in contact with the vertical pin 17. It is also envisaged using a graduated vernier for the glass and for the PET so as to perform, with rapidity, the abovementioned adjustments when there is a change in the size or a change in the type of containers to be processed. 8 The support 11 sliding on the pin 7, the rollers 10 and the cam 9 form means for moving the gripping elements 4 so as to close and open. The grippers according to the present invention, together with the associated adjusting and moving means, allow the processing of containers with a variation in diameter of more than 20 mm, for example are able to process containers which have a diameter of between about 57 mm and about 80 mm, which is not possible with the devices according to the known art. The star conveyor 12 together with the original grippers according to the present invention is also able to operate as a sorting conveyor: it is sufficient to replace the cam 9 with a plurality of actuators, one for each gripper, consisting for example of pneumatic cylinders which are controlled by a centralized control and operating logic system and which are designed to act on the rollers 10 or directly on the supports 11. An important characteristic feature of the star conveyor described above consists in the fact that, in the rest condition, the grippers are positioned inside the pitch diameter of the conveyor and, only in the operative conditions where the container is gripped, do they operate along a diameter which is greater than the pitch diameter, as illustrated in Figure 8. In this way it is possible, for example, to process containers which have a large diameter (also up to 80 mm) with a very small step of the conveyor (about 94 mm). Moreover, the fact that the gripper remains inside the pitch diameter during release or when there is no container allows the combined arrangement with other star conveyors of the same type having the same grippers, without creating interference during transfer of the containers from one conveyor to the other.

Claims: CLAIMS 1. Adjustable gripper for containers, in particular for a star conveyor, comprising at least two opposite gripping elements forming the jaws of the gripper and means for moving said gripping elements so as to close and open, characterized in that it comprises means (17, 18, 8) for adjusting the gripper (3) and the adaptability to containers (2) of different diameter, which are formed so as to co-operate with the abovementioned moving means (9, 10, 11) so that the adjusting means provide, depending on their position, a plurality of basic configurations for the gripper (3), each suitable for particular diameters of the containers (2) to be processed, while the moving means perform, for each of said basic configurations, opening and closing of the gripper (3) so as to grip or release individual containers (2). 2. Adjustable gripper according to Claim 1, in which the adjusting means are formed so as to adjust the gripping position of the gripping elements (4) so that, with a variation in the diameter of the containers (2) to be processed, the gripping elements (4) grip the containers (2) always along the pitch diameter of the star conveyor (1) with which the gripper is associated. Adjustable gripper according to Claim 1, in which the moving means comprise a support (11) which has, fixed to it, the gripping elements (4) and at least one roller (10) travelling in a cam (9) rotating integrally with the star conveyor (1), said support being movable radially on a pin (7) as a result of the rotational movement of the star conveyor (1). 4. Adjustable gripper according to Claim 1 , in which the gripping elements (4) comprise two gripping elements acting on a same side of the container (2) and a third gripping element acting on the opposite side, being positioned at an intermediate height between the two gripping elements and formed so as to be arranged between the top level of the upper gripping element and the bottom level of the lower gripping element. 10 5. Adjustable gripper according to Claim 1 , in which the adjusting means comprise: - a vertical pin (17) which is fixed at the bottom to a pin (7) movable radially in a star conveyor (1) with which the gripper (3) is associated; - a shaped profile (18) followed by the vertical pin (17) by means of resilient compensation means (8), said shaped profile being provided with a plurality of inclined surfaces or ramps which are equal in number to the grippers associated with the star conveyor (1); the displacement of the vertical pin (17) on the shaped profile (18) causing a variation in the basic opening position of the gripping elements (4) of the gripper. 6. Adjustable gripper according to Claim 1, in which the gripping elements (4) are fixed to the same support (11) sliding on a pin (7), the gripping elements (4) being connected together by a three-hinged arch (12) and by resilient means (16). 7. Adjustable gripper according to Claim 6, in which the three-hinged arch (12) comprises two small link bars (14), each of which is attached at one end to a small pin (13) of a gripping element (4) and at the other end to a central pin (15) inserted in the pin (7) and integral therewith. 8. Adjustable gripper according to Claim 1, arranged together with a plurality of similar grippers on the periphery of a star conveyor (1), characterized in that the means for moving the gripping elements (4) so as to close and open comprise an actuator for each gripper, all the actuators being controlled by a central control and operating logic system which selectively causes opening and closing of selected grippers of the star conveyor (1). 9. Adjustable gripper according to Claim 1, in which the gripper is formed so as to be positioned in the rest condition inside the pitch diameter of the star conveyor (1) with which it is associated and so as to be outside said pitch diameter only in the operative conditions where the container (2) is gripped. 10. Star conveyor for containers, characterized in that it comprises a plurality of grippers (3) 11 according to any one of the preceding claims. 11. Plant for bottling or filling and transporting containers, characterized in that it comprises at least one star conveyor (1) according to Claim 10.

Inventors: PRETI FABRIZIO, ZACCHE VANNI, PRETI, FABRIZIO, ZACCHE', VANNI
Applicants: PRETI FABRIZIO, SASIB LABELLING MACHINERY S P, SASIB SPA, ZACCHE VANNI, PRETI, FABRIZIO, SASIB LABELLING MACHINERY S.P.A., SASIB S.P.A., ZACCHE', VANNI
Application year: 1999
Main classification: B65G29
IPC codes: B65G29, B65G47, B67C7