WO2008008030A1

WO2008008030A1 - Picking device for distribution and withdrawal of articles to and from a conveyor belt

Info

Publication number: WO2008008030A1
Application number: PCT/SE2007/050459
Authority: WO
Inventors: Göran EWERLÖF
Original assignee: Gepro Ab
Priority date: 2006-07-10
Filing date: 2007-06-21
Publication date: 2008-01-17
Also published as: SE0601519L

Abstract

Picking device (12) for transferring articles (6) between a palette (4) that is moving along a conveyor path (2) and a static position (11a, 11b) outside the conveyor path (2), which picking device comprises at least one rotating picking arm (14) with a gripping unit (15) comprising at least one suction cup (16), which is connected to a sub pressure source such that a sub pressure is created in the suction cup, which is sufficient for the suction cup (16) to be able to lift an article (6), whereby a valve regulator (50) is arranged at the gripping unit (15), which valve regulator (50) controls the sub pressure in the suction cup (16) such that the sub pressure by influence of the valve regulator (50) may be sufficiently reduced for the article to release from the suction cup (16) when the article has been transferred to the desired position. The palette (4) moves at substantially the same speed past the picking device (12) and the picking arm (14) rotates in a plane situated substantially parallel over the plane of the conveyor path (2), whereby the rotating movement of the picking device (12) is synchronized with the movement of the palette (4) along the conveyor path (2) such that the gripping unit (15) of the picking arms (14) is tangent to the conveyor path (2) at substantially the same speed as the palette (4) and substantially at the same time as the palette (4) passes to transfer articles to or from the palette (4), and whereby the rotating movement of the picking device (12) stops when the gripping unit (15) is approaching the static position (11a, 11b) outside the conveyor path (2) that it does not rotate when it picks and releases articles from or to the static position (11a, 11b).

Description

Picking device for distribution and withdrawal of articles to and from a conveyor belt

The invention concerns a picking device for distribution and withdrawal of articles to and from a conveyor path, along which articles are processed. The invention also concerns a processing device comprising such a picking device.

BACKGROUND Today's methods for processing of CDs, in which e.g. a declaration of contents or a decorative colour print is printed on to the trackless side of the CDs, are almost completely automated. A pile of unprinted CDs is placed at the one end of a conveyor path at a printing device, and a pile of printed CDs is subsequently delivered at the other end. The difference between different devices of this kind is above all how many discs that may be printed under a certain period and the quality of the finished printing. Usually the discs are guided forward on so-called palettes or article carriers that are passing different processing stations where the discs are processed. Usually they are stopped when it is time to put on or take away the articles from them. These stops limits the capacity of the device regarding how many articles may be processed during a certain unit of time.

PRIOR ART

In US 6 543 346 (Kammann) a device is disclosed for applying printings to separate articles, at which two picking devices are arranged, one to distribute unprinted articles on palettes that are guided around a conveyor path along which the articles are applied with print, and the other to collect the articles from the palettes after they have been printed. The palettes are sequentially moved around the conveyor path, whereby the articles are distributed and collected when the palettes are stationary. The processing of the articles is also performed when the palettes are stationary.

A drawback residing in that the palettes being moved sequentially around the conveyor path is that it implies a limitation of the number of articles that may be processed in the device during a certain unit of time.

SHORT DESCRIPTION OF THE INVENTION A purpose of the device according to the invention is to provide a reliable device for the processing of articles, such as CDs or the like, in which a great number of articles may be processed during a certain unit of time with maintained quality. Another purpose is to provide a picking device at which the palettes may be guided continuously around a conveyor path at the same time as the articles are transferred to and from the palettes.

According to a first aspect that is complying with these purposes the invention consists of a picking device for transferring articles between a palette that is moving along a conveyor path and a static position outside the conveyor path, which picking device comprises at least a rotating picking arm with a gripping unit comprising at least one suction cup connected to a sub pressure source, which is sufficient for the suction cup to be able to lift an article, whereby a valve regulator is arranged at the gripping unit, which valve regulator is regulating the sub pressure in the suction cup so that the sub pressure by actuation of the valve regulator may be sufficiently decreased so that the article is released from the suction cup when the article has been transferred to the desired position. The palette is moving with a substantially constant speed past the picking device and the picking arm is rotating in a plane situated substantially parallel over the plane of the conveyor path, whereby the rotating movement of the picking arm is synchronized with the movement of the palette along the conveyor path so that the gripping unit of the picking arm is tangent to the conveyor path at substantially the same speed as the palette and substantially at the same time as the palette is passing to transfer the articles to or from the palette, and whereby the rotating movement of the picking arm is stopped when the gripping unit is approaching the static position outside the conveyor path so that it does not rotate when it is picking or releasing articles from or to the static position.

Another aspect of the invention consists of a processing device comprising such a picking device. The invention according to both these aspects is complying with the purposes described above.

Preferred embodiments of the invention are presented in the dependent patent claims.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail below in the detailed description with references to the drawings, in which:

Figure 1 is a view from above of a processing device according to the invention;

fig 2a is a view from above of two picking devices for application of unprocessed articles and removal of processed articles to and from the conveyor path of the processing device;

fig 2b shows a cross section along the cut A-A in figure 2a;

fig 3 is a side view of the two picking devices in figure 2a; fig 4 shows the same view as in figure 3 after that the picking devices have been turned 60° counter-clockwise;

fig 5 is a side view of the picking devices at the same stage as in figure 3, but from the other side;

fig 6 shows the same view as in figure 5 after that the picking devices have been turned 60° counter-clockwise, i.e. at the same stage as in figure 4;

DETAILED DESCRIPTION OF THE SHOWED EMBODIMENTS Figure 1 is a schematic view of the device 1 according to a first embodiment of the invention. The device is intended for processing of articles such as CDs, DVDs or the like and comprises a conveyor path 2 along which a number of palettes 4 that are supporting articles 6 to be processed are guided in an orbit in a conveying direction D around the conveyor path 2. At least one processing station 8A-F is placed in connection to the conveyor path 2. In figure 1 all processing stations 8a-f are designed as printing stations, at which the articles are provided with a printing. However, a curing station e.g. 8b, 8d and 8f is preferably placed after each printing station e.g. 8a, 8c and 8e, for curing the recently applied print.

In the description and in the claims, reference numbers with the same numbers, but with different letters refer to similar but not the same details. In the cases where the letters have been omitted the number simply relates to a certain type of detail, and not a specific one of that type.

The device 1 according to the invention comprises two driving devices. The first driving device extends all along the orbit and comprises a chain (not shown) that is driven by two gear wheels 26a and 26b. The chain is engaged with the palettes and is arranged to drive them around the whole conveyor path. The second driving device 30, which overlaps the first driving device, is arranged to drive the palettes 4 at the processing stations 8a- f. For this purpose the second driving device 30 comprises a worm conveyor 32 with a helical curve shaped track, in which a pin (not shown) on the palette is adapted to run. The worm conveyor provides a high accurate driving, which is important in order to minimize the risk that the printing will be blurred.

Further, the movement of the worm conveyor is synchronized with a possible movement at the processing stations. Hence, when the printing is applied by rotating pressing rolls, the rotating speed of the pressing rolls is so adapted that the printed perimeter surface of the pressing roll has the same speed as the palettes.

The articles 6 arrive at the conveyor path piled on a first bar 1 Ia at a storing place, wherefrom a picking device 12A picks them up, one by one, and places them on a palette at the same time as the palette is driven forward in the conveying direction D. A second picking device 12B removes the articles from the conveyor path when they are fully processed and places them on a second bar l ib at a discharging place. When the first bar has no unprocessed articles left it is guided further away to the discharging place to be loaded with articles that have been processed.

As the palettes are driven around the device at a constant speed a high efficiency may be maintained at the device and a large number of articles may be processed at a certain unit of time. To be able to drive the device with as few stops as possible it is also important that the feeding of unprocessed articles and the removing of processed articles to and from the conveyor path is working properly. The invention therefore relates to the picking devices 12a and 12b and their interaction with the passing palettes 4. At known devices the palettes have to be stationary when articles are to be placed and removed. However, the device according to the invention is so designed that the palettes never have to stop under normal operation, whereby a continuous operation with high efficiency is achieved.

In figure 2a the picking devices 12a and 12b are shown in a view from above. Both picking devices comprise three picking arms 14a-c and 14d-f, which are symmetrically arranged at 120° from each other. Every picking arm is equipped with a gripping unit 15 comprising four elastic suction cups 16 (see e.g. figure 2b). The suction cups 16 are connected to a vacuum pump (not shown), whereby the suction cups are arranged to suck up articles 6 at a first position and then after having rotated 180° the articles are released by elimination of the sub pressure when the articles are situated at the release spot. In the shown embodiment the picking arms 14a-f of the picking device are not rotating continuously. Instead each picking device 12a and 12b stops when one of the picking arms 14a-c and 14d-f is located at a bar 11a and 1 Ib to pick up an unprocessed disc 6a, b and to put a processed disc 6d-f down. The movement of the picking devices 12a and 12b is synchronized with the movement of the palettes 4 so that the picking arm is tangent to the conveyor path 2 at the same time as a palette 4 passes a picking device 12a and 12b.

In figure 2b a cross section along the cut A-A in figure 2a is shown of a picking arm 14a and a palette 4a in the stage where a disc 6a is dropped down on to the palette. The palette is driven forward by a chain (not shown) and rolls on four horizontal wheels 44, of which the rear pair of wheels is shown in figure 2b, along the rail 3 of the conveyor path. When the picking arm 14a, as in figure 2b, is straight over the palette 4a, the whole gripping unit 15 will be pushed down by a pressing element 13 designed as a ball bearing at the middle console of the picking device. The gripping unit 15 has for this purpose at its lower inside a horizontal skirt 10 with a convex upper side, which is interacting with the pressing element 13 in such a way that the whole gripping unit 15 is pushed down. Simultaneously, a valve regulator 50 on the inside of the gripping unit 15, is being pushed inwards due to interaction with the projecting convex part 19a on the inside of the picking arm 14a, whereby the projecting part 19a forces the valve regulator 50 inwards. The valve regulator 50 is in its turn regulating a valve that is controlling the sub pressure in the suction cups 16 and the valve is opened when the valve regulator 50 is pushed down, whereby the article 6a is dropped down on to the passing palette 4a when the picking arm 14a is straight above the palette.

Further, the palette 4a is equipped with supporting elements 46, 47 for fixing of the articles 6. In the shown embodiment the palette is adapted to carry discs with a centre hole, whereby the supporting elements 46, 47 consists of two opposed supporting elements 46 and 47 adapted to fix the article 6a in its centre hole. One of the supporting elements 46 is fixedly arranged on the palette while the other supporting element 47 is spring mounted and fixedly connected to a ball bearing 48 placed on that side of the palette 4a that is facing the picking device 12a. When the palette 4a is passing under the picking arm 14a the ball bearing 48 is pushed inwards by interaction with a bulging element 53 arranged right below the picking devices 12a. When the ball bearing 48 is being pushed inwards, the element that is fixedly engaged with the supporting element 47 is also displaced towards the fixed supporting element 46 so that a certain clearance is created on at least one side of the supporting elements with respect to the centre holes of the articles. The created clearance yields a certain allowance within which an article may be placed when it is dropped down on the palette 4a. After the article 6a has been placed on the palette 4a and as consequence of that the palette is driven away the ball bearing 48 leaves the bulging part 53, whereby the spring mounted supporting element 47 springs away from the fixed supporting element 46, and whereby the supporting elements 46 and 47 is exerting pressure against opposite sides of the centre hole of the article 6a, whereby it remains fixed on the palette 4. Thereafter, the supporting elements 46 and 47 keeps the article fixed around the whole conveyor path 2 and past the processing stations 8a-f until the palette 4a is approaching the second picking device 12b, which is also equipped with a bulging part 53 adapted to interact with the ball bearing 48 of the palette according to the method described above.

The use of the supporting elements 46, 47 according to the shown embodiment requires that the articles that are to be processed include a centre hole, in which the articles may be fixed. If the articles that are to be processed do not have such a centre hole another type of supporting element must be used. Supporting elements may e.g. be arranged to grasp the opposed outer sides of the articles, whereby one of the supporting elements or both are adjustable in the same way as the spring mounted supporting element 47. It is also conventional to fix articles by means of vacuum, which is customary in prior art even when the articles include centre holes. A problem related to the vacuum fixing of articles is however that a vacuum suction apparatus has to be connected to each palette, which means that advanced valve and tube systems are needed to accompany each individual palette around the whole conveyor path. Thanks to the supporting elements according to the invention the design of the device is principally made simpler, without reducing the quality. It may even be easier to make sure that the disc will end up in a correct position when using the supporting elements according to the invention since they are automatically assuring that the articles are correctly situated, while, on the other hand a vacuum suction apparatus just as well may fix a disc in an incorrect position. Thus, supporting elements according to the invention involve advantages over the prior art.

The second picking device 12b functions in a manner similar to that of the first picking device except for one important difference; it relocates processed discs from the palettes to the second bar 1 Ib. When the picking arm 14f of the second picking device 12b passes a palette 4b, as shown in figure 2a, the suction element 16 of the gripping unit 15 is adapted to abut the fully processed article 6f in the same way as at the first picking device 12a. The only difference is that no projecting convex part facing the conveyor path 2 and corresponding to the projecting convex part 19a of the first picking device 12a is arranged at the second picking device 12b. Consequently the valve regulator 50 is not manipulated, whereby the valve remains closed and the suction force in the suction cups 16 is maintained when a suction cup 16 is abutting the article 6f, which of course is a condition for the article 6f to be sucked up by it.

Hereinafter the work of the two picking devices 12a and 12b shall be described one by one with reference to the figures 3-6. The first picking device 12a is, as earlier mentioned, arranged to pick unprocessed discs from the storing place at the first bar 11a and distribute them on the palettes. From figure 3 it is evident how a gripping unit 15 at a picking arm 14b is lowered straight at the first bar 1 Ia to collect the uppermost disc 6b from the pile. As the gripping unit 15 is lowered the suction cups 16 will abut the disc 6a so that the disc connects to them. A lifting fork 17, shown most clearly in figure 4, is arranged at the first bar for sequentially lifting the discs, after which they are collected from the pile. A spacer 18 is arranged under the discs in order for the lifting fork to reach the discs. Contrary to when the picking arm passes a palette the picking arms 14a-c of the picking device 12a are not rotating when they collect articles from the bar 11a. In figure 4 is shown that the first picking device is equipped with a slightly upwardly slanted adjustable wing 51 comprising a peripheral ball bearing 52. During the earlier stage, which is shown in figure 3 the adjustable wing is in a horizontal position, whereby the ball bearing 52 (hidden behind the gripping unit 15) is abutting the horizontal skirt 10 at the picking arm 14b and whereby the gripping unit 15 is held down such that the suction cups 16 are abutting the uppermost article 6b and may suck it up from the first bar. The adjustable wing 51 is lowered following that a picking arm has stopped at the bar 11a and is again elevated before the picking arm starts to move away from the bar. The disc is subsequently kept fixed on the picking arm until the picking arm passes straight above a palette 4 on the conveyor path.

In figure 4 and 6 the picking devices are shown at a later stage, i.e. the same stage as is shown in figures 2a and 2b, when the picking devices have been rotated 60° counter clockwise such that a picking arm 14a is straight above a palette 4 on the conveyor path 2. As the palettes are driven forward at a constant speed, the movement of the picking arms must be synchronized with the speed of the palettes 4. Consequently the picking devices are accelerated from a stationary position, in which a picking arm is straight above the bar (figure 3 and 5) , to rotate with an angular speed in which the gripping unit 15 of the picking arm 14a equals the speed of the passing palette 4a (figure 2a-b, 4 and 6). Subsequently, the picking device 12a is retarded until it has returned to a stationary position, in which the following picking arm 14c is located right above the bar 11a and a new disc may be collected.

In figure 3 and to some extent also in figure 5 it is shown how a picking arm 14d at the second picking device 12b delivers a processed disc 6d to the second bar 1 Ib. The control of the sub pressure in the suction cups 16 is operated in a similar way as when the sub pressure is eliminated to release the article 6a from the first picking device 12a on to the passing palette 4a. A projecting convex part 19b at the second picking device 12b in line with the bar 1 Ib is interacting with the valve regulator 50 on the gripping unit 15 such that the sub pressure is eliminated and the disc is released straight at the bar l ib. When the picking arm leaves the static position at the bar the valve is immediately reclosed and a sub pressure is again created at the suction cups 16 of the gripping unit 15. When a picking arm passes a palette with a fully processed disc, as is the case in figure 3 and 5, the gripping unit 15 is lowered such that the suction cups 16 come sufficiently close to the disc in order to suck them up from the palette and fix them to the suction cups. Consequently, in the shown embodiment, a sub pressure is maintained in the suction cups through out the whole loop, except at the places where the articles are released, e.g. straight above the palette 4a of the first picking device 12a and straight above the bar 1 Ib of the second picking device 12b.

Above a working operating embodiment of the invention has been described. However, it is obvious for a person skilled in the art that the device may be designed in a great number of different ways within the extent of the protection, which only is limited by the scope of the claims below.

Claims

1. Device (1) for processing of articles (6) such as CDs, DVDs or the like, which comprises: - a conveyor path (2), at least one processing station (8a-fj placed along the conveyor path (2), at least one palette (4), which is arranged on the conveyor path (2) to carry an article (6) that is to be processed at a processing station (8a-f) and to guide it in an orbit in a conveying direction (D) around the conveyor path (2); a driving device for driving the palette (4) in the conveying direction (D) around the conveyor path (2); a first picking device (12a) with at least one rotating picking arm (14a-c) comprising a gripping unit (15), whereby the first picking device (12a) is arranged to transfer unprocessed articles (6a, 6b) from a storing place (l la) outside the conveyor path (2) to the palette (4), wherein the gripping unit (15) grasps the article at a storing place (1 Ia) and dropping it on the palette (4) on the conveyor path (2) after the picking arm (14a- c) has rotated to the conveyor path (2); a second picking device (12b) with at least one rotating picking arm (14d-f) comprising a gripping unit (15), whereby the second picking device (12b) is arranged to transfer processed articles (6d-f) from the palette (4) after that the articles have been processed at the processing station (8a-f), wherein the gripping unit (15) grasps a processed article from the palette (4) on the conveyor path (2) and releases it after the picking arm (14d-f) has rotated to a collection place outside the conveyor path, characterised in that the driving device (20,

30) is arranged to drive the palette (4) with a substantially constant speed around the conveyor path (2) , whereby the picking arms (14a-c, 14d-f) of the picking devices (12a, 12b) are rotating in a plane that is substantially parallel to the plane of the conveyor path, and whereby the picking arms (14a-c, 14d-f) and the gripping units (15) are synchronized with the movement of the palette (4) along the conveyor path

(2) so that they are tangent to the conveyor path at the same time as a palette (4) passes and with substantially the same speed as the palette (4) when they are transferring articles to and from the palette (4); wherein the first picking device (12a) stops when the picking arm (14a-c) is straight over the storing place (l la) and the gripping unit (15) grasps an article from it, after which the picking device is accelerated such that the picking arm (14a-c) when it passes over the palette (4) has substantially the same speed as the palette (4) ; and that the second picking device (12b) stops when the picking arm (14d-f) is straight over the collecting place (1 Ib) and the gripping unit drops the article on it, after which the picking device (12b) is accelerated so that the picking arm (14d-f) has substantially the same speed as the palette (4) when it passes over the palette (4).

2. Device according to claim 1 , characterised in that each gripping unit (15) comprises at least one suction cup (16) that is connected to a sub pressure source, whereby the suction cup (16) is arranged to fix the article (6) by means of a sub pressure and whereby the sub pressure is eliminated to drop the article at the releasing spot.

3. Device according to claim 2, characterised in that the gripping unit (15) on the first picking device is displaceable between an upper position and a lower position, whereby it is arranged to be displaced down to the lower position when a picking arm (14a-f) passes over a palette and whereby the article that is holding the suction cup (16) in the lower position is abutting the palette at the same time as the sub pressure is eliminated and the article is released.

4. Device according to any of the proceeding claims, characterised in that the palette comprises supporting elements (46, 47) for fixing the article on the palette when the palette is guided around the conveyor path, whereof at least one supporting element is moveable and arranged to release the engagement with the article (6) when the palette (4) passes under the picking device (12) such that the article (6) may transfer to or from the palette (4) at the picking devices (12) without being impeded by the supporting elements (46, 47).

5. Device according to any of the proceeding claims, characterised in that both picking devices (12) each comprise three picking arms (14a-c; 14d-f), which are symmetrically arranged 120° from each other.

6. Picking device (12) for transferring of articles (6) between a palette (4) that is moving along a conveyor path (2) and a static position (11a, 1 Ib) outside the conveyor path (2), which picking device comprises at least one rotating picking arm ( 14) with a gripping unit ( 15) comprising at least one suction cup (16), which is connected to a sub pressure source such that a sub pressure is created in the suction cup, which is sufficient for the suction cup (16) to be able to lift an article (6), whereby a valve regulator (50) is arranged at the gripping unit (15), which valve regulator (50) controls the sub pressure in the suction cup ( 16) such that the sub pressure by influence of the valve regulator (50) may be sufficiently reduced for the article to release from the suction cup ( 16) when the article has been transferred to the desired position, characterised in that the palette (4) moves at substantially the same speed past the picking device (12) and the picking arm (14) rotates in a plane situated substantially parallel over the plane of the conveyor path (2), whereby the rotating movement of the picking device (12) is synchronized with the movement of the palette (4) along the conveyor path (2) such that the gripping unit (15) of the picking arms (14) is tangent to the conveyor path (2) at substantially the same speed as the palette (4) and substantially at the same time as the palette (4) passes to transfer articles to or from the palette (4), and whereby the rotating movement of the picking device (12) stops when the gripping unit (15) is approaching the static position (11a, 1 Ib) outside the conveyor path (2) that it does not rotate when it picks or releases articles from and to the static position (11a, 1 Ib).