Abstract
An end effector for porous-face vacuum end-of-arm tooling is described. The tool comprises a tool-change interface (10), a foam pad (12), a ejector (14), a isolation valve (16), a manifold (18), and a contact detector (20), a pressure sensor (22), a blow-off valve (24). The arrangement addresses starting the vacuum at the right moment in the approach, where evacuating before the face touches the workpiece wastes air and pulls dust into the circuit, and evacuating late leaves the tool pressing on a workpiece it has not yet gripped. The description covers what detects contact, what that detection starts, and the order of the two events. Every connection is stated with the medium it carries, and the operating sequence is given as conditions on named operations.
1. Technical Field
[0001]This disclosure relates to porous-face vacuum end-of-arm tooling. It concerns the arrangement of a gripping interface, the supply that feeds it, the distribution and control between them, and the sequence in which those parts act on a workpiece. FIG. 1 shows the arrangement as a block diagram with the reference numerals used throughout this description.
2. Technical Context
[0002]The arrangement addresses starting the vacuum at the right moment in the approach. The difficulty is that evacuating before the face touches the workpiece wastes air and pulls dust into the circuit, and evacuating late leaves the tool pressing on a workpiece it has not yet gripped. A tool that does not address it is still usable on a narrow range of workpieces, and the cost appears as cycle time, dropped parts or air consumption rather than as an outright failure. What follows covers what detects contact, what that detection starts, and the order of the two events.
3. System Overview
[0003]The tool comprises the tool-change interface (10), the foam pad (12), the ejector (14), the isolation valve (16), the manifold (18), the contact detector (20), the pressure sensor (22), the blow-off valve (24). FIG. 1 shows how these blocks are connected and which medium each connection carries. The blocks are not interchangeable by name: a connection is made only where one block offers a medium that another needs, and each connection below is stated together with the medium it carries.
[0004]FIG. 2 shows elevation of the gripping face on its mounting.
[0005]FIG. 3 shows signal path between the controlled elements and the cell controller.
[0006]
- The tool-side plate of the tool-change interface is bolted to the robot flange (10).
[0007]
- The foam pad is connected to the ejector by a vacuum line that opens into the distribution chamber behind the porous face (12).
[0008]
- The foam pad is mounted on the tool-change interface (12).
[0009]
- Compressed air is fed to the ejector from the compressed air supply of the cell (14).
[0010]
- The isolation valve is placed in the line from the ejector, so that closing the valve cuts that line and leaves the rest of the circuit under vacuum (16).
[0011]
- The valve is switched by the contact detector (16).
[0012]
- The manifold inlet is connected to the ejector, which supplies every outlet of the manifold (18).
[0013]
- The detector watches the foam pad and reports when a workpiece is present at that face (20).
[0014]
- The pressure sensor is tapped into the line at the ejector and reads the pressure in that line (22).
[0015]
- The blow-off valve is fed from the compressed air supply of the cell (24).
[0016]
- The blow-off valve is connected to the circuit at the ejector, so that a pulse of compressed air can be driven back through it (24).
[0017]
- The blow-off valve is switched by the contact detector (24).
4. Components
[0018]Tool-Change Interface (10). The tool-change interface (10) is provided once in this arrangement. The interface splits the tool into a robot side and a tool side, so the tool can be exchanged without dismantling it. The interface is locked mechanical.
[0019]Foam Pad (12). The foam pad (12) is provided once in this arrangement. The pad presents a porous face, so the holding force is spread over the contact area rather than concentrated at a lip. The pad is made of foam. The pad is of closed cell foam.
[0020]Ejector (14). The ejector (14) is provided once in this arrangement. The ejector draws the circuit down by passing compressed air through a nozzle, so it needs no moving part at the tool. The ejector is built with 2 stages.
[0021]Isolation Valve (16). The isolation valve (16) is provided once in this arrangement. The valve sits in the line it controls, so closing it cuts that line without disturbing the rest of the circuit. An isolation valve is provided per zone. The isolation valve (16) is configured with material steel.
[0022]Manifold (18). The manifold (18) is provided once in this arrangement. The manifold receives the vacuum and distributes it to the outlets that feed the face. The manifold has 2 outlets.
[0023]Contact Detector (20). The contact detector (20) is provided once in this arrangement. The detector watches the face and reports the moment a workpiece is present against it. The detector is placed on the frame.
[0024]Pressure Sensor (22). The pressure sensor (22) is provided once in this arrangement. The sensor taps the line and reports the level it reads, which is what makes the state of the grip observable. The pressure is measured at the manifold.
[0025]Blow-Off Valve (24). The blow-off valve (24) is provided once in this arrangement. The blow-off valve drives compressed air back through the circuit, which clears the face rather than waiting for it to refill. The pulse is a sustained blast. The pulse is given before set-down.
5. Operation
[0026]The operating sequence is given as conditions on named operations. Each condition names the event it depends on and the operation it governs, so the order of events is explicit rather than implied by the order of the sentences. FIG. 2 shows the gripping face referred to in these steps. The tool is presented to the workpiece square to the face, and the numbered operations below are what the arrangement does from that point.
[0027]
- When the foam pad seals the workpiece, the foam pad is evacuated by the ejector.
[0028]
- After the contact detector has detected the workpiece, the vacuum supply is actuated.
[0029]
- When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor.
[0030]
- The workpiece may not be lifted unless the pressure sensor signals a secure grip.
[0031]
- While the isolation valve is in the closed state, its own vacuum is held by the isolated zone.
[0032]
- The vacuum is maintained by the remaining zones unless their own valves are in the closed state.
[0033]
- Before the workpiece reaches the set-down position, the workpiece is blown off by the blow-off valve.
[0034]
- The workpiece is held until the blow-off valve has opened the circuit.
[0035]An operation whose condition is not met does not run. A condition that is stated with UNLESS holds except while its event is true, and one stated with UNTIL ends the operation at the moment its event becomes true. With the workpiece released, the tool returns to the pick position and the cycle repeats.
6. Example Embodiments
[0036]In one embodiment the gripping face carries 1 foam pads on a common mounting, fed as shown in FIG. 1, and the tool is presented to the workpiece square to the face. In a second embodiment the same face is arranged in two rows so that a long workpiece is supported at both ends, with the connections of FIG. 1 unchanged. In a third embodiment the face is built at half the pitch and the number of foam pads is doubled for the same envelope, which suits a workpiece that is lighter but less rigid.
[0037]In a further embodiment the zones are sized so that the smallest workpiece in the range covers one whole zone, so that no partly covered zone has to be held under vacuum at any point in the cycle.
7. Alternative Configurations
[0038]The gripping face may instead use a folded bellows cup, which takes up height differences at the cost of lateral stiffness. The gripping face may instead use a flat cup, which is stiffer laterally but needs the face and the workpiece to meet squarely. A gripping face of this kind may also be replaced by fingers closing on the workpiece, which removes the air circuit entirely and requires access to two opposed surfaces of the workpiece. The ejector may be replaced by a pump at the tool, which stops the continuous air draw and adds mass to the moving assembly, or by a connection to a plant vacuum line, which removes the generator from the tool and couples the tool to the rest of the site. The isolation valve may be provided once for the whole circuit rather than per zone, which is simpler and gives up the ability to hold vacuum on a covered zone while another is open. The blow-off may be replaced by a plain vent, which releases at the rate the circuit refills and needs no compressed air at the moment of release.
8. Parameter Variations
[0039]Each parameter below is stated with what it changes in the arrangement. The locking of the tool-change interface is mechanical in the arrangement described; varying it changes what has to be present at the interface for the tool to stay attached. The porosity of the foam pad is closed cell in the arrangement described; varying it changes the flow drawn through the face and the vacuum level that can be held behind it. The stages of the ejector is 2 in the arrangement described; varying it changes the flow drawn at low vacuum and the air consumed to hold a sealed face. The control of the isolation valve is per zone in the arrangement described; varying it changes whether one zone can be cut on its own or only the whole circuit. The outlets of the manifold is 2 in the arrangement described; varying it changes how many connections can be fed from one inlet without dividing the face. The placement of the contact detector is on the frame in the arrangement described; varying it changes whether contact is reported for the face as a whole or for one part of it. The placement of the pressure sensor is at the manifold in the arrangement described; varying it changes whether the reading describes the whole circuit or one zone of it. The duration of the blow-off valve is a sustained blast in the arrangement described; varying it changes how quickly the face clears and how much air each release costs. The timing of the blow-off valve is before set-down in the arrangement described; varying it changes whether the pulse assists set-down or clears the face after it.
9. Additional Implementations
[0040]A separating element may be added so that a workpiece which follows the face upwards after release is pushed off positively. The face may be divided into zones, each fed by its own branch, so that a workpiece covering part of the face is handled without the uncovered part being held under vacuum. The arrangement may be duplicated on one mounting so that two workpieces are handled in one cycle, with the distribution fed from a common inlet and each face controlled on its own.
10. Provenance and method
[0041]This document is an original combination composed from a typed library of mechanism blocks. Each block was derived from the published patent literature and carries typed connection points, the parameters its source states, and its own construction and operating description. The combination described here is proposed rather than taken from any one source, and it is not asserted to have 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-8006968-B2, US-8132312-B2, WO-2008134339-A4. Their text is not reproduced here; the description above is generated from the structure of the combination.
11. Figures
