Abstract
A foam-pad vacuum gripping tool comprising one tool-change interface, one foam pad, one ejector, one pressure sensor, one contact detector and one vent valve. When the foam pad reaches the workpiece, the foam pad is evacuated by the ejector. 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 foam-pad vacuum gripping tool: one foam pad carried on a tool-change interface, fed by an ejector. 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, holding a workpiece that a rigid lip cannot seal against 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 foam pad. The foam pad presents a compliant face to the workpiece; the holding force is spread over the contact area rather than concentrated at a lip. The pad is of open cell foam.
[0004]One ejector. The ejector draws the circuit down by passing compressed air through a nozzle; it has no moving part at the tool and consumes air for as long as it runs. The ejector has three stages.
[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 foam pad is carried on the tool side of the tool-change interface.
[0009]The ejector is fixed to the tool side of the tool-change interface.
[0010]The foam pad is connected to the ejector outlet by a single vacuum line, so that the face is evacuated through that line.
[0011]The pressure sensor is tapped into the line between the ejector and the foam pad and reads the pressure of the whole circuit.
[0012]The contact detector is mounted on the frame and reports the moment a workpiece is present against the gripping face.
[0013]The vent valve is connected to the circuit at the ejector outlet 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 ejector is fed from the compressed air supply of the cell.
[0016]The locking piston of the tool-change interface is fed from the compressed air supply of the cell.
[0017]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
[0018]
- After the contact detector has detected the workpiece, the vacuum supply is actuated by the cell controller.
[0019]
- When the foam pad reaches the workpiece, the foam pad is evacuated by the ejector.
[0020]
- When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor.
[0021]
- The workpiece may not be lifted unless the pressure sensor signals a secure grip.
[0022]
- After the workpiece has reached the set-down position, the vacuum circuit is vented by the vent valve.
[0023]
- The workpiece is held until the vent valve has opened the circuit.
[0024]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
[0025]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); material of the foam pad: sponge (sets the compliance of the sealing face); porosity of the foam pad: open cell (sets whether air passes through the pad body or only through openings cut through it); stages of the ejector: three (sets the flow drawn at low vacuum and the compressed air consumed while a sealed face is held); 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).
[0026]The open-cell foam passes air through its whole face, so an uncovered part of the face draws air through the pad itself; the supply is sized for that continuous flow and the pad relies on flow restriction through the foam, not on a seal, to hold vacuum behind a covered area.
[0027]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.
[0028]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
[0029]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-4385681-B1, 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.
6. Correction notice
[0030]This publication supersedes OT-2026-000006316, whose text described this arrangement with defects recorded in the quality register at https://opentechnical.org/qa/. The earlier publication is unchanged and remains public. Changes made to reach a consistent configuration: sensor placement moved from an absent manifold to the supply line; release element added: a vent valve after set-down (the legacy assembly had no way to let go); foam_pad material 'foam' is not offered by the library; the source-stated value 'sponge' is used.