Three bellows cup vacuum gripper, three outlet manifold, plant vacuum fed, manifold pressure sensor, vented before set-down, on a tool changer

Abstract

A bellows-cup vacuum gripping tool comprising one tool-change interface, three bellows cups, one plant vacuum connection, one manifold, one pressure sensor and one vent valve. When the bellows cups reach the workpiece, the bellows cups are evacuated by the plant vacuum connection. Before the workpiece reaches the set-down position, the vacuum circuit is vented by the vent valve while the workpiece is above the receiving surface. The arrangement is a proposed configuration composed from a typed library of mechanism blocks derived from published patents; it has not been constructed.

1. Purpose and arrangement

[0001]This disclosure describes a bellows-cup vacuum gripping tool: three bellows cups carried on a tool-change interface, fed by a plant vacuum connection. It is arranged for verifying that the workpiece is held before the arm moves, controlling the moment of release, taking up height differences at the face and exchanging the tool without rewiring the cell. One concrete embodiment is described; every connection is stated with the medium it carries, and the operating sequence is given as conditions on named operations.

2. Components, construction and connections

[0002]One tool-change interface. The tool-change interface splits the tool into a robot side and a tool side, so the tool can be exchanged without dismantling it. The tool-change interface has a pneumatic lock.

[0003]Three bellows cups. Each bellows cup is folded so that it shortens under vacuum and takes up a height difference between the face and the workpiece. The count of three follows from the arrangement: one gripping element per manifold outlet. Each bellows cup has two folds.

[0004]One plant vacuum connection. The plant vacuum connection takes vacuum from the plant line, so the tool carries no generator of its own.

[0005]One manifold. The manifold receives the vacuum at one inlet and distributes it to its outlets. The manifold has three outlets.

[0006]One pressure sensor. The pressure sensor taps the line it is placed in and reports the vacuum level in that line. The pressure is measured at the manifold.

[0007]One vent valve. The vent valve opens the circuit it is connected to towards atmosphere, which ends the grip. The circuit is vented before set-down.

[0008]The bellows cups are carried on the tool side of the tool-change interface.

[0009]The manifold is fixed to the tool side of the tool-change interface.

[0010]The manifold inlet is connected to the plant vacuum connection, which supplies every outlet of the manifold.

[0011]Each manifold outlet feeds one bellows cup by its own vacuum line, so that the three outlets feed three bellows cups.

[0012]The pressure sensor is tapped into the manifold body and reads the pressure common to every outlet.

[0013]The vent valve is connected to the circuit at the plant vacuum connection and opens that circuit to atmosphere when it is actuated.

[0014]The robot side of the tool-change interface is bolted to the robot flange.

[0015]The locking piston of the tool-change interface is fed from the compressed air supply of the cell.

[0016]The vent valve and the lock of the tool-change interface are switched by the cell controller; the pressure sensor reports to the cell controller.

3. Operating sequence and conditions

[0022]The cell controller reads the pressure sensor (the manifold) and commands the tool-change interface, the vent valve; no sensor drives an actuator directly.

4. Parameters and operating assumptions

[0023]Parameter values of this embodiment: locking of the tool-change interface: pneumatic (sets what has to be present at the interface for the tool to stay attached); folds of the bellows cups: two (sets the travel taken up between the face and the workpiece, and the lateral stiffness of the cup under load); material of the bellows cups: plastic (sets the friction at the lip and the resistance of the folds to fatigue); outlets of the manifold: three (sets how many lines can be fed from one inlet); placement of the pressure sensor: at the manifold (sets where in the circuit the reading is taken and what it describes); timing of the vent valve: before set-down (sets whether the workpiece is released before or after it is supported by the set-down surface).

[0024]The workpiece is released while it is still above the receiving surface and falls the remaining distance onto it. This sequence is for a workpiece and a receiving surface that tolerate that drop, for example a part released into a container or onto a conveyor; the drop height is set by the application and is not fixed here.

[0025]The tool carries no valve between the plant line and the face, so the plant vacuum is applied to the face whenever the plant line is live; release relies on the release element alone.

[0026]The lock is engaged by compressed air acting on the locking piston and is held only while that air pressure is applied; what the lock does on loss of air pressure is not fixed by this arrangement.

[0027]Vacuum levels are stated as gauge pressure below atmosphere. A stronger vacuum is a larger pressure difference below atmosphere, and the vacuum level 'exceeds the gripping threshold' when that difference is at least the threshold difference.

5. Provenance and status

[0028]This document is an original combination composed from a typed library of mechanism blocks. Each block was derived from a published patent and carries typed connection points, the parameters its source states, and its own construction and operating description. The combination described here is proposed and has not been constructed. The published documents behind the blocks used in this arrangement are EP-4489564-B1, US-10259123-B2, US-11427405-B1, US-11858125-B2, US-8006968-B2, WO-2008134339-A4; their text is not reproduced, and the description above is generated from the structure of the combination.