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 vacuum pump (14), a isolation valve (16), a pressure sensor (18), and a vent valve (20). The arrangement addresses controlling the moment the workpiece is let go, where releasing before the workpiece is supported drops it, and releasing late drags it across the set-down surface as the tool lifts away. The description covers which valve opens the circuit, the position the workpiece must reach first, and what the tool does between those two moments. 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 controlling the moment the workpiece is let go. The difficulty is that releasing before the workpiece is supported drops it, and releasing late drags it across the set-down surface as the tool lifts away. 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 which valve opens the circuit, the position the workpiece must reach first, and what the tool does between those two moments.
3. System Overview
[0003]The tool comprises the tool-change interface (10), the foam pad (12), the vacuum pump (14), the isolation valve (16), the pressure sensor (18), the vent valve (20). 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 vacuum pump 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]
- The pump motor is supplied from the electrical supply of the cell (14).
[0010]
- The isolation valve is placed in the line from the vacuum pump, 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 pressure sensor (16).
[0012]
- The pressure sensor is tapped into the line at the vacuum pump and reads the pressure in that line (18).
[0013]
- The vent valve is connected to the circuit at the vacuum pump and opens that circuit to atmosphere when it is actuated (20).
[0014]
- The vent valve is switched by the pressure sensor (20).
4. Components
[0015]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.
[0016]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 sponge. The pad is of open cell foam.
[0017]Vacuum Pump (14). The vacuum pump (14) is provided once in this arrangement. The pump draws the circuit down mechanically and adds its own mass to the moving assembly. The pump is driven by a electric motor.
[0018]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.
[0019]Pressure Sensor (18). The pressure sensor (18) 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.
[0020]Vent Valve (20). The vent valve (20) is provided once in this arrangement. The vent valve opens the circuit to atmosphere, which is what ends the grip. The circuit is vented after set-down.
5. Operation
[0021]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.
[0022]
- When the foam pad seals the workpiece, the foam pad is evacuated by the vacuum pump.
[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]
- While the isolation valve is in the closed state, its own vacuum is held by the isolated zone.
[0026]
- The vacuum is maintained by the remaining zones unless their own valves are in the closed state.
[0027]
- After the workpiece has reached the set-down position, the vacuum circuit is vented by the vent valve.
[0028]
- The workpiece is held until the vent valve has opened the circuit.
[0029]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
[0030]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.
[0031]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
[0032]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 pump may be replaced by an ejector, which removes the moving part at the tool and spends compressed air while it runs, or by a connection to a plant vacuum line. 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 vent may be supplemented by a blow-off pulse, which clears the face rather than waiting for it to refill.
8. Parameter Variations
[0033]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 open 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 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 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 timing of the vent valve is after set-down in the arrangement described; varying it changes whether the workpiece is released before or after it is supported.
9. Additional Implementations
[0034]A contact detector may be placed at the face so that evacuation starts only once the workpiece is present, which keeps the circuit closed during the approach. 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
[0035]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, WO-2008134339-A4. Their text is not reproduced here; the description above is generated from the structure of the combination.
11. Figures
