Abstract
A zoned vacuum gripping tool comprising one tool-change interface, one foam pad, one ejector, one isolation valve, three zone branches, three pressure sensors, one contact detector and one blow-off valve. When the foam pad reaches the workpiece, the foam pad is evacuated by the ejector. Before the workpiece reaches the set-down position, the workpiece is blown off by the blow-off 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 zoned vacuum gripping tool: one foam pad carried on a tool-change interface, fed by an ejector. It is arranged for handling workpieces that do not cover the whole gripping face, cutting part of the circuit while the rest holds vacuum, verifying that the workpiece is held before the arm moves, starting the cycle at the moment of contact, clearing the face at 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 two stages.
[0005]One isolation valve. The isolation valve sits in the line it controls; closing it cuts that line without disturbing the rest of the circuit. Isolation is common.
[0006]Three zone branches. Each zone branch carries the vacuum of one zone of the face and no other. The count of three follows from the arrangement: one branch per zone. The distribution is divided into three zones, each fed by its own branch.
[0007]Three pressure sensors. Each pressure sensor taps the line it is placed in and reports the vacuum level in that line. The count of three follows from the arrangement: one sensor per zone branch. The pressure is measured at each zone.
[0008]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.
[0009]One blow-off valve. The blow-off valve drives compressed air back through the circuit to the face, which clears the face instead of waiting for the circuit to refill. The blow-off is a short pulse. The blow-off pulse is given before set-down.
[0010]The foam pad is carried on the tool side of the tool-change interface.
[0011]The ejector is fixed to the tool side of the tool-change interface.
[0012]The isolation valve is placed in the line from the ejector, so that closing the valve cuts the whole circuit from the supply.
[0013]The three zone branches are taken from a branch junction on the isolation valve outlet, so that each branch carries the vacuum of its own zone only.
[0014]Each zone line opens into its own section of the distribution chamber behind the porous face of the foam pad, so that the pad is evacuated zone by zone.
[0015]One pressure sensor is tapped into each zone line, so that each of the three sensors reads its own zone and no other.
[0016]The contact detector is mounted on the frame and reports the moment a workpiece is present against the gripping face.
[0017]The blow-off valve is connected to the circuit at the line downstream of the isolation valve, so that compressed air can be driven back through the circuit to the face.
[0018]The robot side of the tool-change interface is bolted to the robot flange.
[0019]The ejector is fed from the compressed air supply of the cell.
[0020]The blow-off valve is fed from the compressed air supply of the cell.
[0021]The locking piston of the tool-change interface is fed from the compressed air supply of the cell.
[0022]The isolation valve, the blow-off valve and the lock of the tool-change interface are switched by the cell controller; the pressure sensors and the contact detector report to the cell controller.
3. Operating sequence and conditions
[0023]
- After the contact detector has detected the workpiece, the vacuum supply is actuated by the cell controller.
[0024]
- When the foam pad reaches the workpiece, the foam pad is evacuated by the ejector.
[0025]
- When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor of each zone in use.
[0026]
- The workpiece may not be lifted unless the pressure sensor of each zone in use signals a secure grip.
[0027]
- After the vacuum level has exceeded the gripping threshold, the isolation valve is closed by the cell controller.
[0028]
- While the isolation valve is in the closed state, the vacuum downstream of the valve is maintained by the sealed gripping face.
[0029]
- Before the workpiece reaches the set-down position, the workpiece is blown off by the blow-off valve while the workpiece is above the receiving surface.
[0030]
- The workpiece is held until the blow-off valve has opened the circuit.
[0031]The cell controller reads the pressure sensor (each zone line) and the contact detector (on the frame) and commands the blow-off valve, the isolation valve, the tool-change interface; no sensor drives an actuator directly.
4. Parameters and operating assumptions
[0032]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: two (sets the flow drawn at low vacuum and the compressed air consumed while a sealed face is held); control of the isolation valve: common (sets which part of the circuit the valve cuts: one branch line on its own or the whole circuit); material of the isolation valve: steel; material of the zone branches: plastic; zones of the zone branches: three (sets how much of the face can be treated separately); placement of the pressure sensors: at each zone (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); duration of the blow-off valve: a short pulse (sets how quickly the face clears and how much air each release costs); timing of the blow-off valve: before set-down (sets whether the pulse assists a drop release or clears the face after set-down).
[0033]A zone is in use when the workpiece covers it. Which zones are in use is decided by the controller from the workpiece programme; this arrangement fixes where each zone is measured, not how the programme is written.
[0034]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.
[0035]The blow-off is a short pulse: the valve opens for a fraction of a second, long enough to break the seal and clear the face, and closes again.
[0036]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.
[0037]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.
[0038]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
[0039]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-10163334-B1, US-11427405-B1, US-11858125-B2, US-2022339798-A1, US-8132312-B2, WO-2008134339-A4, WO-2026020244-A1; their text is not reproduced, and the description above is generated from the structure of the combination.