Single bellows cup vacuum gripper, plant vacuum fed, supply line pressure sensor, vented after set-down, on a tool changer

Abstract

A bellows-cup vacuum gripping tool comprising one tool-change interface, one bellows cup, one plant vacuum connection, one pressure sensor, one contact detector and one vent valve. When the bellows cup reaches the workpiece, the bellows cup is evacuated by the plant vacuum connection. After the workpiece has reached the set-down position, the vacuum circuit is vented by the vent valve. 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: one bellows cup 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, starting the cycle at the moment of contact, 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]One bellows cup. Each bellows cup is folded so that it shortens under vacuum and takes up a height difference between the face and the workpiece. 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 pressure sensor. The pressure sensor taps the line it is placed in and reports the vacuum level in that line. The pressure is measured in the supply line.

[0006]One contact detector. The contact detector reports the moment a workpiece is present at the gripping face; its sensing technology is not fixed by this arrangement. The contact detector is mounted on the frame.

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

[0008]The bellows cup is carried on the tool side of the tool-change interface.

[0009]The bellows cup is connected to the plant vacuum connection by a single vacuum line, so that the face is evacuated through that line.

[0010]The pressure sensor is tapped into the line between the plant vacuum connection and the bellows cup and reads the pressure of the whole circuit.

[0011]The contact detector is mounted on the frame and reports the moment a workpiece is present against the gripping face.

[0012]The vent valve is connected to the circuit at the plant vacuum connection and opens that circuit to atmosphere when it is actuated.

[0013]The robot side of the tool-change interface is bolted to the robot flange.

[0014]The locking piston of the tool-change interface is fed from the compressed air supply of the cell.

[0015]The vent valve and the lock of the tool-change interface are switched by the cell controller; the pressure sensor and the contact detector report to the cell controller.

3. Operating sequence and conditions

[0022]The cell controller reads the pressure sensor (the common supply line) and the contact detector (on the frame) 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 cup: 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 cup: plastic (sets the friction at the lip and the resistance of the folds to fatigue); placement of the pressure sensor: in the supply line (sets where in the circuit the reading is taken and what it describes); placement of the contact detector: on the frame (sets where the presence of the workpiece is detected); timing of the vent valve: after set-down (sets whether the workpiece is released before or after it is supported by the set-down surface).

[0024]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.

[0025]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.

[0026]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

[0027]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-2022339798-A1, WO-2008134339-A4; their text is not reproduced, and the description above is generated from the structure of the combination.