Abstract
A zoned vacuum gripping tool comprising one mounting flange, four bellows cups, one ejector, four isolation valves, four zone branches, four pressure sensors, one contact detector and one blow-off valve. When the bellows cups reach the workpiece, the bellows 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 bellows cups carried on a mounting flange, 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 and taking up height differences at the face. 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 mounting flange. The mounting flange carries the whole assembly and presents the bolt pattern that meets the robot.
[0003]Four bellows cups. Each bellows cup is folded so that it shortens under vacuum and takes up a height difference between the face and the workpiece. The count of four follows from the arrangement: one gripping element per zone branch. Each bellows cup has three folds.
[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]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 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.
[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 sustained blast. The blow-off pulse is given before set-down.
[0010]The bellows cups are carried on the tool side of the mounting flange.
[0011]The ejector is fixed to the tool side of the mounting flange.
[0012]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.
[0013]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.
[0014]Each bellows cup is connected to its own zone line, one bellows cup per zone, and is evacuated through that line.
[0015]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.
[0016]The contact detector is mounted on the gripping face and reports the moment a workpiece is present against the gripping face.
[0017]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.
[0018]The robot side of the mounting flange 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 isolation valves and the blow-off valve are switched by the cell controller; the pressure sensors and the contact detector report to the cell controller.
3. Operating sequence and conditions
[0022]
- After the contact detector has detected the workpiece, the vacuum supply is actuated by the cell controller.
[0023]
- When the bellows cups reach the workpiece, the bellows cups are evacuated by the ejector.
[0024]
- When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor of each zone in use.
[0025]
- The workpiece may not be lifted unless the pressure sensor of each zone in use signals a secure grip.
[0026]
- When a zone is not covered by the workpiece, the isolation valve of that zone is closed by the cell controller.
[0027]
- While the isolation valve of that zone is in the open state, the vacuum of a covered zone is maintained by the ejector.
[0028]
- 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.
[0029]
- The workpiece is held until the blow-off valve has opened the circuit.
[0030]The cell controller reads the pressure sensor (each zone line) and the contact detector (on the gripping face) and commands the blow-off valve, the isolation valves; no sensor drives an actuator directly.
4. Parameters and operating assumptions
[0031]Parameter values of this embodiment: folds of the bellows cups: three (sets the travel taken up between the face and the workpiece, and the lateral stiffness of the cup under load); material of the bellows cups: plastic (sets the friction at the lip and the resistance of the folds to fatigue); 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 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); placement of the contact detector: on the gripping face (sets where the presence of the workpiece is detected); 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).
[0032]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.
[0033]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.
[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 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.
[0036]A zone whose isolation valve is closed is cut from the common line and does not vent or blow off until its valve opens.
[0037]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
[0038]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-10163334-B1, US-10549431-B2, US-11427405-B1, 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.