Device to feed work pieces using gripping rails

Details Device to feed work pieces using gripping rails Device to feed work pieces using gripping rails

2003-02-19

2004-03-09

Bidwell, James R. (Department: 3651)

Conveyors: power-driven

Conveyor system for moving a specific load as a separate unit

System includes an oscillating or reciprocating load...

C198S468900

Reexamination Certificate

active

06702098

ABSTRACT:

This application claims the right of priority from DE 102 06 773.2, filed Feb. 19, 2002, which is incorporated herein by reference as if fully set forth.
BACKGROUND
This invention pertains to a device for stepwise feeding of work pieces using two gripping rails that can be moved back and forth in the feed direction, with the gripping rails having gripping parts or gripping zones with which to grasp the work pieces. To grasp the work pieces and move them in the feed direction, these gripping rails can be moved and then returned to their starting position, wherein there are at least two levers attached to each gripping rail at a distance from one another that tilt parallel to one another in the plane of motion of the gripping rails or in a plane parallel to it or a mirror image thereof, and wherein the levers of one gripping rail tilt in the opposite direction to those of the other gripping rail, said levers being coupled to their respective rails via a longitudinal guide extending in the direction of orientation of the gripping rails.
A prior art device of this type is known from EP 0 633 077 B1 that can be used in stamping presses as described in DE 100 19 109 A1, and its usefulness has been proven since it requires minimal design height, particularly in the grip zone, and since it saves space and simplifies the synchronization of the motions of the levers. Nevertheless, the synchronization of the motions of the levers in this known device requires a mechanical connection, and the gripping rails travel along a pull and/or push bar in their longitudinal direction of extension, which produces this mechanical connection and provides for the synchronous motion of the levers. In addition, to accomplish a uniform feed motion, a relatively expensive gear design is required in order to coordinate the gripping motions, the feed motions and the return motions in time with one another.
SUMMARY
Therefore, the object is to create a device of the type mentioned above in which the mechanical complexity can be reduced; in particular the complexity of the uniform feed motion can be reduced.
In order to meet this objective, the device defined above is characterized in that to produce the feed and return motion, at least one feed transverse directly or indirectly attaches to the gripping rails outside of their gripping zones, said traverse moving perpendicular to itself, that at least one driven tilt arm is connected to this feed traverse whose tilting motion can be converted into a feed motion of the feed traverse perpendicular to itself and thus into a feed motion and return motion, respectively, of the gripping rails, wherein the point of attachment of the tilt arm slides within a longitudinal guide running in the direction of orientation of the feed traverse, that a servomotor is provided as the drive unit for the tilting motion, and that means are provided to guide the feed motion of the feed traverse perpendicular or parallel to itself.
Using servomotors, mechanical transmission means such as gears, cam plates and the like can be eliminated, i.e. bodies of considerable mass that are accelerated and braked as the device is actuated. Moreover, the mechanical complexity is considerably reduced.
An embodiment of the invention that meets this criteria comprises at least one mechanical guide, for example at least one guide track, guide profile, guide rail or guide bar, that is provided to guide the feed and return motion of the traverse perpendicular to itself, at least one guide member or guide element that is present at the feed traverse or connected to the traverse and that engages the mechanical guide, or that at least one guide is provided on the feed traverse that runs perpendicular to the direction in which it extends and that cooperates with at least one fixed guide member or guide element. Preferably in this regard, there are two parallel guide rails or guide bars. This makes it possible for a single tilt arm driven by a servomotor to be sufficient to move the feed traverse perpendicular to itself, thus resulting in the feed and return motion of the gripping rails.
A preferred embodiment of the invention can be characterized in that as a means to guide the feed traverse perpendicular or parallel to itself, a second tilt arm driven by a servomotor engages the traverse and that is approximately a mirror-image of the first tilt arm and that has the same dimensions, the tilt motion of said second tilt arm being transformed, together with that of the first tilt arm, into the feed and return motion of a corresponding feed traverse, respectively, or of a common feed traverse, and thus into the feed and return motion of the gripping rails, wherein the point of attachment of this second tilt arm slides within a longitudinal guide that runs in the direction of orientation of the associated feed traverse. In the same way that the gripping rails themselves can be moved synchronously toward and away from one another by means of levers that are placed approximately mirror-imaged with respect to one another, they can also be moved in the feed and return direction via a common feed traverse, or if necessary by two separate feed traverses, and two oppositely rotating tilt arms attached to it/them of equal size and driven by means of servomotors. This provides a simple mechanical design with few parts to be accelerated. For precise motions, an additional mechanical guide can also be provided in this case.
In the process, the driven shaft of each servomotor can be directly coupled to the tilt axis of its respective tilt arm or arms, or the shaft can constitute this axis—in particular as a single piece. The motion of the servomotor can thus be directly transmitted into the tilt motion of the respective tilt arm so that no additional translations or transmissions of force are necessary to move the feed traverse. The mechanical complexity is thus correspondingly low.
The feed traverse can penetrate guide notches or guide openings that run along or through the gripping rails perpendicular to the gripping rails, and the gripping rails can move perpendicular relative to the feed traverse in its longitudinal direction as they open and close. In this way, the gripping rails can execute their opening and closing motions and can also still be moved in the feed direction and reverse with the help of the feed traverse.
A modified additional embodiment provides that guide fingers or the like which slide along the feed traverse in its direction of orientation are placed in slots, for example, to couple the feed traverse to the gripping rails, said guide fingers extending from the feed traverse outward into matching recesses in the gripping rails.
Another configuration is made possible by placing the tilting levers used to move the gripping rails above and/or below the gripping rails, and by placing the feed traverse and its tilt arm below and/or above the gripping rails, since the latter are located outside of the gripping zone and thus also away from the press tools.
The levers that operate the gripping rails can also each have a servomotor as a drive system for its tilt motions and the servomotors of the tilting levers for the gripping rails and those of the tilt arm or arms for the feed traverse can have a common control system that matches their tilt motions to one another, in particular temporally. By using servomotors for the drive system of multiple, or if possible for all tilt arms, the matching of the individual motions to one another can be carried out by means of a control system, specifically electrical or electronic, and preferably programmable, which requires considerably less mechanical complexity than a mechanical coordination system via gears.
The 'tilting ends of the tilt levers and the tilt arms can each attach to glide blocks that slide within slots in the gripping rails and in the feed traverse. This results in a direct and ideal connection of the tilting levers and the tilt arm to parts that move only in straight lines so that the tilt motions can be converted practically unfettered into cor

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