Abstract
A bellows-cup vacuum gripping tool comprising one tool-change interface, three bellows cups, one ejector, one isolation valve, one manifold, one pressure sensor 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 bellows-cup vacuum gripping tool: three bellows cups carried on a tool-change interface, fed by an ejector. It is arranged for 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, taking up height differences at the face 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]Three 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 three follows from the arrangement: one gripping element per manifold outlet. Each bellows cup has one fold.
[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 one stage.
[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]One manifold. The manifold receives the vacuum at one inlet and distributes it to its outlets. The manifold has three outlets.
[0007]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 at the manifold.
[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 tool-change interface.
[0010]The manifold is fixed to 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 manifold inlet is connected to the isolation valve outlet, which supplies every outlet of the manifold.
[0014]Each manifold outlet feeds one bellows cup by its own vacuum line, so that the three outlets feed three bellows cups.
[0015]The pressure sensor is tapped into the manifold body and reads the pressure common to every outlet.
[0016]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.
[0017]The robot side of the tool-change interface is bolted to the robot flange.
[0018]The ejector is fed from the compressed air supply of the cell.
[0019]The blow-off valve is fed from the compressed air supply of the cell.
[0020]The locking piston of the tool-change interface is fed from the compressed air supply of the cell.
[0021]The isolation valve, the blow-off valve and the lock of the tool-change interface are switched by the cell controller; the pressure sensor reports to the cell controller.
3. Operating sequence and conditions
[0022]
- When the bellows cups reach the workpiece, the bellows cups are evacuated by the ejector.
[0023]
- When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor.
[0024]
- The workpiece may not be lifted unless the pressure sensor signals a secure grip.
[0025]
- After the vacuum level has exceeded the gripping threshold, the isolation valve is closed by the cell controller.
[0026]
- While the isolation valve is in the closed state, the vacuum downstream of the valve is maintained by the sealed gripping face.
[0027]
- 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.
[0028]
- The workpiece is held until the blow-off valve has opened the circuit.
[0029]The cell controller reads the pressure sensor (the manifold) and commands the blow-off valve, the isolation valve, the tool-change interface; no sensor drives an actuator directly.
4. Parameters and operating assumptions
[0030]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); folds of the bellows cups: one (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: one (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; outlets of the manifold: three (sets how many lines can be fed from one inlet); placement of the pressure sensor: at the manifold (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).
[0031]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.
[0032]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.
[0033]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.
[0034]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
[0035]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-11427405-B1, US-11858125-B2, US-8006968-B2, US-8132312-B2, WO-2008134339-A4; their text is not reproduced, and the description above is generated from the structure of the combination.