Abstract
A zoned vacuum gripping tool comprising one mounting flange, two bellows cups, one ejector, one isolation valve, two zone branches, two pressure sensors 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: two 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, 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]Two 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 two follows from the arrangement: one gripping element per zone branch. Each bellows cup has two 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]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]Two zone branches. Each zone branch carries the vacuum of one zone of the face and no other. The count of two follows from the arrangement: one branch per zone. The distribution is divided into two zones, each fed by its own branch.
[0007]Two pressure sensors. Each pressure sensor taps the line it is placed in and reports the vacuum level in that line. The count of two 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 short pulse. The blow-off pulse is given before set-down.
[0009]The bellows cups are carried on the tool side of the mounting flange.
[0010]The ejector is fixed to the tool side of the mounting flange.
[0011]The isolation valve is placed in the line from the ejector, so that closing the valve cuts the whole circuit from the supply.
[0012]The two 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.
[0013]Each bellows cup is connected to its own zone line, one bellows cup per zone, and is evacuated through that line.
[0014]One pressure sensor is tapped into each zone line, so that each of the two sensors reads its own zone and no other.
[0015]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.
[0016]The robot side of the mounting flange 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 isolation valve and the blow-off valve are switched by the cell controller; the pressure sensors reports to the cell controller.
3. Operating sequence and conditions
[0020]
- When the bellows cups reach the workpiece, the bellows cups are evacuated by the ejector.
[0021]
- When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor of each zone in use.
[0022]
- The workpiece may not be lifted unless the pressure sensor of each zone in use signals a secure grip.
[0023]
- After the vacuum level has exceeded the gripping threshold, the isolation valve is closed by the cell controller.
[0024]
- While the isolation valve is in the closed state, the vacuum downstream of the valve is maintained by the sealed gripping face.
[0025]
- 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.
[0026]
- The workpiece is held until the blow-off valve has opened the circuit.
[0027]The cell controller reads the pressure sensor (each zone line) and commands the blow-off valve, the isolation valve; no sensor drives an actuator directly.
4. Parameters and operating assumptions
[0028]Parameter values of this embodiment: folds of the bellows cups: two (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 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: two (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 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).
[0029]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.
[0030]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.
[0031]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.
[0032]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
[0033]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-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.