Handling: hand and hoist-line implements – Utilizing fluid pressure – Venturi effect
Reexamination Certificate
2000-03-31
2002-05-07
Cherry, Johnny D. (Department: 3652)
Handling: hand and hoist-line implements
Utilizing fluid pressure
Venturi effect
Reexamination Certificate
active
06382692
ABSTRACT:
This application claims Paris Convention priority of DE 299 05 951.0 filed Apr. 6, 1999 the complete disclosure which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The invention concerns a vacuum gripper for suctioning workpieces, comprising a vacuum supply, an elastic vacuum body and a vacuum body holder, wherein the side of the vacuum body facing the workpiece comprises a sealing lip defining a vacuum chamber, the vacuum chamber being connected to the vacuum supply.
Vacuum grippers are used to suction objects or workpieces such that they can either be fixed or handled. The suctioned object can be transported by disposing the vacuum grippers on manipulators. Different objects require different corresponding vacuum grippers. The vacuum grippers are usually adapted to the size and weight of the object to be manipulated. The vacuum grippers usually comprise a continuous sealing lip closing a vacuum chamber or sealing it off with respect to the surroundings. This enables relatively simple gripping and transport of flat objects, such as metal sheets or glass plates. Metal sheets have the associated problem that they tend to slip with respect to the vacuum gripper, since the surface of the metal sheet is oily. This can, under certain conditions cause production delays and, in the worst case, a production stoppage. Large and therefore heavy metal sheets require vacuum grippers with relatively large surfaces which can disadvantageously deform the metal sheets when holding the sheets under vacuum. Such deformations are unacceptable with thin metal sheets of a sheet thickness of less than 1 mm, as are primarily used in construction of motor vehicle bodies.
It is therefore the underlying purpose of the invention to provide a vacuum gripper which effects reliable gripping and gentle treatment of the workpieces.
SUMMARY OF THE INVENTION
This object is achieved in accordance with the invention with a vacuum gripper of the above mentioned type by providing the vacuum chamber with ribs projecting into the vacuum chamber and by providing the ribs and/or the sealing lip with at least one groove on its side facing the vacuum chamber.
In a further development, the side of the sealing lip facing the vacuum chamber comprises a groove extending in the circumferential direction and the vacuum chamber is provided with radially extending ribs projecting into the vacuum chamber.
The groove extending in the circumferential direction on the surface of the sealing lip facing the vacuum chamber largely prevents slippage of the object suctioned by the vacuum gripper. This groove can be designated as an oil groove in which an oil film can accumulate or into which the oil film is displaced by the abutting sealing lip. Moreover, the groove produces two sharp sealing edges on the sealing lip which help to prevent slippage.
A further advantage of the vacuum gripper in accordance with the invention is that it comprises ribs projecting into the vacuum chamber which limit the depth of the vacuum chamber to thereby prevent e.g. a metal sheet from being suctioned too far into the vacuum chamber. After suctioning, the metal sheet abuts on the projecting ribs, which prevent deformation of the metal sheet by further suctioning.
A further development provides that the groove extends along the entire circumference of the sealing lip. The groove may or may not thereby comprise interruptions. Moreover, the groove can be flow-connected to the vacuum chamber.
The radially extending ribs projecting into the vacuum chamber preferably have differing lengths and widths. Thereby, e.g. four or eight long and wide ribs can be provided which are evenly distributed about the circumference, wherein shorter and narrower ribs are disposed between these long and wide ribs. The remaining spaces can be provided with even shorter and narrower ribs. The ribs are formed as bridges and comprise parallel longitudinal sides and longitudinal edges. In another embodiment, the ribs can be wedge-shaped, wherein their broader end extends radially outwardly such that the free spaces between the ribs are reduced in size.
In a further development, the ribs comprise a flat abutment surface for the workpiece. Preferably, this abutment surface is profiled or provided with recesses. These profiles or recesses function as oil grooves to prevent slippage of the suctioned object, wherein the ribs support the object.
An advantageous embodiment provides that the grooves extend at an angle with respect to the radial and circumferential directions. This produces sharp edges extending at an inclined angle with respect to the longitudinal direction of the ribs or to the travel of the associated section of the oil groove provided in the sealing lip. This produces optimum support, e.g. of an oily metal sheet, on the vacuum gripper.
One side of the grooves is open to withdraw oil entering the grooves. This has the advantage that the oil which is displaced from the surface of the metal sheet when the metal sheet abuts on the abutment surface of the ribs can enter the grooves and exit through the one-sided open end.
In a further development, the vacuum gripper comprises a central annular rib whose abutment surface has recesses. This central annular rib prevents loading of the metal sheet in those areas from which air is suctioned in the vacuum chamber but which are not provided with radial ribs. Air is suctioned from the vacuum chamber via the recesses provided in the radial direction in the annular rib.
Preferably, the radially extending ribs and the annular rib are separated from one another. This permits air to be easily suctioned from all areas of the vacuum chamber to guarantee fast suctioning of the workpiece and secure support of the suctioned workpiece.
Further advantages, features and details of the invention can be extracted from the dependent claims and the following detailed description of a particularly preferred embodiment with reference to the drawing. The features shown in the drawing, recited in the claims, and given in the description may thereby be essential to the invention either individually or collectively in any arbitrary combination.
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patent: 2853333 (1958-09-01), Littel
patent: 3005652 (1961-10-01), Helm
patent: 3062746 (1962-11-01), Oakes
patent: 3152828 (1964-10-01), Lytle
patent: 3195941 (1965-07-01), Morey
patent: 3240525 (1966-03-01), Wood
patent: 3330589 (1967-07-01), Mumma
patent: 3926466 (1975-12-01), Carpenter
patent: 5611585 (1997-03-01), Lingell
patent: 374154 (1964-02-01), None
patent: 177571 (1993-07-01), None
patent: 148889 (1962-01-01), None
Dittmann Hans
Eisele Thomas
Schmalz Kurt
Cherry Johnny D.
J. Schmalz GmbH
Vincent Paul
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