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

Abstract

A suction-cup vacuum gripping tool comprising one tool-change interface, one suction cup, one plant vacuum connection, one pressure sensor, one contact detector and one vent valve. When the suction cup reaches the workpiece, the suction cup is 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 suction-cup vacuum gripping tool: one suction 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 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 mechanical lock.

[0003]One suction cup. Each suction cup presents a sealing lip to the workpiece and is evacuated through its own connection. The suction cups are of the oval form.

[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 gripping face.

[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 suction cup is carried on the tool side of the tool-change interface.

[0009]The suction 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 suction cup and reads the pressure of the whole circuit.

[0011]The contact detector is mounted on the gripping face 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 vent valve is switched by the cell controller; the pressure sensor and the contact detector report to the cell controller.

3. Operating sequence and conditions

[0021]The cell controller reads the pressure sensor (the common supply line) and the contact detector (on the gripping face) and commands the vent valve; no sensor drives an actuator directly.

4. Parameters and operating assumptions

[0022]Parameter values of this embodiment: locking of the tool-change interface: mechanical (sets what has to be present at the interface for the tool to stay attached); form of the suction cup: oval (sets the shape of the contact area and the behaviour of the lip on a curved workpiece); material of the suction cup: polyurethane (sets the friction at the lip and the tolerance of the lip to oil and heat); 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 gripping face (sets where the presence of the workpiece is detected); 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).

[0023]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.

[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 a manually operated lever on the interface; no supply crosses the interface for the lock, and tool exchange needs an operator at the tool.

[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 US-10259123-B2, US-11427405-B1, US-11858125-B2, US-2016214812-A1, US-2022339798-A1, WO-2008134339-A4; their text is not reproduced, and the description above is generated from the structure of the combination.