Conveyors: power-driven – Conveyor for changing attitude of item relative to conveyed... – By conveying randomly faced items and turning items to...
Reexamination Certificate
2003-04-10
2004-08-24
Hess, Douglas (Department: 3651)
Conveyors: power-driven
Conveyor for changing attitude of item relative to conveyed...
By conveying randomly faced items and turning items to...
Reexamination Certificate
active
06779647
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention relates to a method for automatically grouping articles placed on a feeding belt and transported on the feeding belt to a manipulation device where the articles are grouped in a predetermined order to form an assortment of a predetermined number of articles, wherein a recognition device detects the position and orientation of the arriving articles on the feeding belt and sends this information to a control unit which, taking into account the speed of the feeding belt, assigns to each article a placement position and controls the manipulation device accordingly as soon as this article reaches the gripping range of the manipulation device.
2. Description of the Related Art
U.S. Pat. No. 6,374,984 describes a method in which the articles are placed in random order onto the feeding belt, wherein a recognition device detects the orientation and position of the arriving articles and sends this information to a control unit. The control unit evaluates the random order on the feeding belt and determines the position of an assortment, comprised of several articles, on the feeding belt. Taking into consideration the belt speed of the feeding belt, the manipulation device is controlled by the control unit and the articles are moved by the manipulation device into the determined end position on the feeding belt.
The conveying flow of the articles on the feeding belt cannot always be maintained, and interruptions of the supply occur frequently in the known method. When the articles are placed in batches of great numbers onto the feeding belt, the automated manipulation device can group the articles at a high placement speed onto the feeding belt as long as the recognition device signals a sufficient number of articles within a gripping range (range of accessability) of the manipulation device. Before the next batch is placed onto the belt, articles may be temporarily present in reduced numbers on the conveying path of the feeding belt. The last articles of a batch can be positioned occasionally at such unfavorable locations, that grouping to an assortment would require high expenditure. Also, the remaining articles of a batch may no longer match the predetermined number of an assortment. These articles are then no longer correlated with an assortment but are removed from the feeding belt as rejects. Accordingly, each batch in the known method generates more or less reject material because of the articles remaining at the end of the batch sorting process.
SUMMARY OF INVENTION
It is an object of the present invention to provide a method for the automatic grouping of articles of the aforementioned kind which prevents rejects while enabling a reliable combining action to form the assortments and which makes possible a high sorting output.
In accordance with the present invention, this is achieved in that the control unit, when determining the placement position of an article, considers the number of articles on the feeding belt leading and/or trailing this article and, when a number of articles that is smaller than the number required for the assortment is detected, the manipulation devices places the article onto the feeding belt in an advanced position or pushed-back position relative to the conveying direction of the feeding belt.
According to the invention, when determining the placement or manipulation position of each article, the number of articles which are trailing this article on the feeding belt is to be considered and, when the number of articles is determined to be smaller than the number required for the assortment, the manipulation device is controlled and operated in a different mode. A gripped article is then not added to an assortment in the grouping mode of the manipulation device, but is placed in an advanced position or a pushed-back position onto the feeding belt relative to the conveying direction of the feeding belt. In this way, in this backing-up mode, the articles on the feeding belt are pushed back or advanced and only thereafter grouped to form an assortment. This backing-up operation is carried out based on predetermined criteria until the desired number of articles can be combined on the feeding belt.
The invention resides in the basic idea that, for a continuously running feeding belt, the articles are to be grouped within a certain unit of time, for example, the articles are to be grouped in accordance with a predetermined sorting pattern or the articles must be placed into receptacles or the like on the belt. The available excess sorting output when articles are missing can be used for the “backing-up mode” wherein the articles are advanced or are pushed back to trailing placement positions on the feeding belt until a sufficiently large number of articles is present in order to fulfill within the available time frame, as a function of the belt speed, the predetermined sorting rule. In this connection, hygiene criteria can also be taken into consideration, for example. With the method according to the invention, complete assortments are compiled wherein rejects are substantially eliminated.
In particular, it is possible to advance or to push back an article in a relay-type operation by means of a manipulation device comprised of several grippers. In this way, it is possible to cover distances which are a multiple of the gripping range of a robot arm. When the manipulation device has several grippers, the actions of the grippers can be controlled by the control unit in a coordinated fashion. When several article types are sorted or when one article type is embodied as a support, receptacle or the like for the assortment into which other articles are to be placed, each identical article is correlated advantageously with a designated gripper. However, it may also be expedient to control during the backing-up mode a selection of or only a single one of the grippers that are available in order to move all articles on the feeding belt into an advanced or pushed-back placement position. In particular, several grippers can be operated in the gripping mode while, simultaneously, other grippers can be operated in the backing-up mode.
REFERENCES:
patent: 4819784 (1989-04-01), Sticht
patent: 5057055 (1991-10-01), Michaud et al.
patent: 5314055 (1994-05-01), Gordon
patent: 5370216 (1994-12-01), Tsuruyama et al.
patent: 5687831 (1997-11-01), Carlisle
patent: 5845759 (1998-12-01), Takada et al.
patent: 6315103 (2001-11-01), Bousherie
patent: 6374984 (2002-04-01), Nagler
patent: 6502688 (2003-01-01), Krooss et al.
patent: 6540062 (2003-04-01), Wunscher et al.
patent: 1-220628 (1989-09-01), None
patent: WO 92/03364 (1992-03-01), None
Hess Douglas
Huckett Gudrun E.
imt Robot AG
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