Abstract
A zoned vacuum gripping tool comprising one tool-change interface, four suction cups, one ejector, four isolation valves, four zone branches, four pressure sensors and one blow-off valve. When the suction cups reach the workpiece, the suction cups are 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: four suction cups 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, clearing the face at 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 pneumatic lock.
[0003]Four suction cups. Each suction cup presents a sealing lip to the workpiece and is evacuated through its own connection. The count of four follows from the arrangement: one gripping element per zone branch. The suction cups are of the flat form.
[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]Four isolation valves. Each isolation valve sits in the line it controls; closing it cuts that line without disturbing the rest of the circuit. The count of four follows from the arrangement: one valve per zone branch. Isolation is per zone.
[0006]Four zone branches. Each zone branch carries the vacuum of one zone of the face and no other. The count of four follows from the arrangement: one branch per zone. The distribution is divided into four zones, each fed by its own branch.
[0007]Four pressure sensors. Each pressure sensor taps the line it is placed in and reports the vacuum level in that line. The count of four follows from the arrangement: one sensor per zone branch. The pressure is measured at each zone.
[0008]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 sustained blast. The blow-off pulse is given before set-down.
[0009]The suction cups are carried on the tool side of the tool-change interface.
[0010]The ejector is fixed to the tool side of the tool-change interface.
[0011]The four zone branches are taken from a branch junction on the ejector outlet, so that each branch carries the vacuum of its own zone only.
[0012]One isolation valve is placed in each zone branch, so that closing that valve cuts its zone from the circuit and leaves the other zones under vacuum.
[0013]Each suction cup is connected to its own zone line, one suction cup per zone, and is evacuated through that line.
[0014]One pressure sensor is tapped into each zone line downstream of that zone's isolation valve, so that each of the four sensors reads its own zone and no other.
[0015]The blow-off valve is connected to the circuit at the ejector outlet, so that compressed air can be driven back through the circuit to the face.
[0016]The robot side of the tool-change interface is bolted to the robot flange.
[0017]The ejector is fed from the compressed air supply of the cell.
[0018]The blow-off valve is fed from the compressed air supply of the cell.
[0019]The locking piston of the tool-change interface is fed from the compressed air supply of the cell.
[0020]The isolation valves, the blow-off valve and the lock of the tool-change interface are switched by the cell controller; the pressure sensors reports to the cell controller.
3. Operating sequence and conditions
[0021]
- When the suction cups reach the workpiece, the suction cups are evacuated by the ejector.
[0022]
- When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor of each zone in use.
[0023]
- The workpiece may not be lifted unless the pressure sensor of each zone in use signals a secure grip.
[0024]
- When a zone is not covered by the workpiece, the isolation valve of that zone is closed by the cell controller.
[0025]
- While the isolation valve of that zone is in the open state, the vacuum of a covered zone is maintained by the ejector.
[0026]
- 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.
[0027]
- The workpiece is held until the blow-off valve has opened the circuit.
[0028]The cell controller reads the pressure sensor (each zone line) and commands the blow-off valve, the isolation valves, the tool-change interface; no sensor drives an actuator directly.
4. Parameters and operating assumptions
[0029]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); form of the suction cups: flat (sets the shape of the contact area and the behaviour of the lip on a curved workpiece); material of the suction cups: polyurethane (sets the friction at the lip and the tolerance of the lip to oil and heat); stages of the ejector: three (sets the flow drawn at low vacuum and the compressed air consumed while a sealed face is held); control of the isolation valves: per zone (sets which part of the circuit the valve cuts: one branch line on its own or the whole circuit); material of the isolation valves: steel; material of the zone branches: plastic; zones of the zone branches: four (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); duration of the blow-off valve: a sustained blast (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).
[0030]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.
[0031]Which zones the workpiece covers is known to the controller from the workpiece programme; the arrangement provides the valve per zone and the controller decides which valves to close.
[0032]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.
[0033]The blow-off is a sustained blast: the valve stays open for the whole release so that the face is cleared of dust and the workpiece is pushed positively away.
[0034]A zone whose isolation valve is closed is cut from the common line and does not vent or blow off until its valve opens.
[0035]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.
[0036]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
[0037]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-10163334-B1, US-11427405-B1, US-11858125-B2, US-2016214812-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.