Conveyors: power-driven – Conveying system having plural power-driven conveying sections – Recycling load in a closed path
Reexamination Certificate
2001-12-10
2003-07-29
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Conveying system having plural power-driven conveying sections
Recycling load in a closed path
C198S394000, C198S750100
Reexamination Certificate
active
06598730
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a parts feeder according to the preamble of claim
1
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PRIOR ART
For the transfer of parts, which are supplied in the form of bulk goods in a storage container, to a robot, the parts as a rule firstly have to be separated from one another (that is to say individualized) and brought into an orientation and position suitable for the transfer to the robot. This task is carried out by parts feeders, as they are known (also referred to as feed systems). A parts feeder accordingly picks up parts in the form of bulk goods, separates the parts and transfers them in a suitable orientation and position to a robot. The robot grips the suitably oriented parts in a selection zone of the parts feeder and subsequently transfers them for further processing and/or mounting to a mounting system, a processing station or the like. In this connection, a robot is to be understood as any kind of apparatus for gripping parts in a favorable orientation and position and subsequently conveying them away from the point at which they are gripped or selected.
Most customary parts feeders comprise a mechanical filter in the form of a vibrating pot which can be rotated about a vertical axis to separate the parts and to orient and position the same. The pot is provided with internal, spiral volutes. Arranged along the volutes are a large number of mechanical guide elements and barriers. On account of the vibrating rotational movement of the pot, the parts are transported upward along the volutes to the outlet of the pot. By means of the barriers and guide elements, only parts in a specific orientation are transported as far as the outlet of the pot, the remainder fall back onto the bottom of the pot in order to begin a renewed transport operation along the volutes. From the outlet of the pot, the parts are typically conveyed onward via linear rails, in order to maintain their separation and orientation.
The mechanical filters in the form of vibrating pots have the disadvantage that they are tailored specifically to specific parts. They are extremely inflexible in relation to changes in the parts. In the event of a modification to the geometric form of the parts, most often the entire vibrating pot has to be redesigned, constructed and tested. In addition, both the volutes of vibrating pots and the linear rails adjacent to the pots are susceptible to blockages as a result of defective and/or particularly unfavorably positioned parts, in particular when the latter have a complicated geometric form.
In the U.S. Pat. No. 5,687,831 (Adept Technology), a parts feeder is described which, as compared with vibrating pots, exhibits improved flexibility in relation to different parts forms. The parts feeder according to U.S. Pat. No. 5,687,831 comprises an essentially horizontal transport section on which the parts are transported to a selection zone. In the selection zone, favorably oriented and arranged parts are detected by means of a video camera and are subsequently gripped by a robot and transferred to a mounting system. The parts that are not selected are guided back to the start of the transport section by means of a recirculation system for a renewed passage through the parts feeder. While they are being fed back, the orientation and the position of the parts are changed in order that they may be oriented favorably during the next pass and selected in the selection zone.
Although the parts feeder according to U.S. Pat. No. 5,687,831 is to a certain extent flexible in relation to different parts forms, it is relatively complicated in design terms and requires a considerable amount of space for the arrangement of the transport section, the selection zone and the recirculation system.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a parts feeder which is simple in design terms, space-saving and flexible in relation to different parts forms.
The object is achieved as defined by the features of the independent patent claims.
According to the invention, a parts feeder for a robot has a selection zone accessible to the robot, a device for changing the orientation and/or the position of the parts stochastically, and a device with a parts recirculation element for recirculating the parts. The device for changing the orientation and/or the position of the parts stochastically is a vibrating platform constructed at the same time as a selection zone. The parts recirculation element and the vibrating platform can be brought relative to each other into two different positions in such a way that in the first position the vibrating platform can be loaded with parts from the parts recirculation element and in the second position the parts which fall down from the vibrating platform can be collected by the parts recirculation element.
In the course of the present description and the claims, a parts recirculation element is always to be understood as an element provided to recirculate parts. Such a parts recirculation element can be constructed, for example, as a separate section, as a zone or parts carrying area which can be moved with respect to the vibrating platform, as a recirculation container constructed so as to accommodate a few parts, or as a storage container constructed so as to accommodate a large quantity of parts.
The parts recirculation element is used firstly, in a first position, to load the vibrating platform with parts. As soon as the vibrating platform has been loaded with a sufficient number of parts, the parts recirculation element and the vibrating platform are brought relative to each other into a second position, in which the same parts recirculation element is used to collect parts which fall down from the vibrating platform during the vibration. At the same time, the vibrating platform serves as a selection zone for the parts feeder, that is to say the parts are gripped by the robot on the vibrating platform and conveyed away. (The actions of gripping the parts and conveying them away is also referred to as selecting the parts.) If the number of parts remaining on the vibrating platform falls below a minimum number, the parts recirculation element and the vibrating platform are brought relative to each other into the first position again, in order to load the vibrating platform again with parts from the parts recirculation element. As a result, the parts which have fallen down from the vibrating platform onto or into the parts recirculation element are guided back to the vibrating platform and are therefore recycled. The parts recirculation element therefore serves alternately as a parts reservoir for loading the vibrating platform with parts and as a collecting element for collecting the parts that fall down from the vibrating platform, in order subsequently to recycle the latter. Because the same element is used to load the vibrating platform with parts and to collect the parts falling down from the vibrating platform, the necessity for separate parts transport devices to feed back the parts that have fallen down from the vibrating platform, and their renewed feeding to the vibrating platform are dispensed with. As opposed to previously known parts feeders, the parts feeder according to the invention therefore manages without any parts transport devices for horizontal parts conveyance, such as conveyor belts, linear rails or the like. This permits an extremely simple and space-saving construction of the parts feeder according to the invention. In addition, as a result of the elimination of the conveyor belts and linear rails, which are susceptible to blockage, the risk of blockage of the entire parts feeder can be reduced substantially.
The vibrating platform and the parts recirculation element can be moved relative to each other. In order to produce the relative movement, either the vibrating platform can be arranged to be substantially fixed to a frame of the parts feeder, and the parts recirculation element can be arranged to be movable with respect to this frame and therefore to the vibrating platform. Or, vice versa,
Gertsch Christoph
Ryser Olivier
Birch Stewart Kolasch & Birch, LLP.
Crawford Gene O
Ellis Christopher P.
Mikron SA Boudry
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