Abstract
An end effector for vacuum end-of-arm tooling for robotic material handling is described. The tool comprises a tool-change interface (10), a suction cup (12), a vacuum pump (14), a manifold (16), a pressure sensor (18), and a blow-off valve (20). The arrangement addresses knowing that the workpiece is actually held before the arm moves, where a cup that has not sealed looks the same as a cup that has, and the difference only appears when the load is already in the air. The description covers where the pressure is measured, the condition that counts as a secure grip, and what the motion is not permitted to do until that condition holds. 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 vacuum end-of-arm tooling for robotic material handling. 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 knowing that the workpiece is actually held before the arm moves. The difficulty is that a cup that has not sealed looks the same as a cup that has, and the difference only appears when the load is already in the air. 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 where the pressure is measured, the condition that counts as a secure grip, and what the motion is not permitted to do until that condition holds.
3. System Overview
[0003]The tool comprises the tool-change interface (10), the suction cup (12), the vacuum pump (14), the manifold (16), the pressure sensor (18), the blow-off 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]
- Each suction cup is connected to the vacuum pump by a vacuum line, so that the cup face is evacuated through that line (12).
[0008]
- Each suction cup is mounted on the tool-change interface (12).
[0009]
- The pump motor is supplied from the electrical supply of the cell (14).
[0010]
- The manifold inlet is connected to the vacuum pump, which supplies every outlet of the manifold (16).
[0011]
- The pressure sensor is tapped into the line at the vacuum pump and reads the pressure in that line (18).
[0012]
- The blow-off valve is fed from the compressed air supply of the cell (20).
[0013]
- The blow-off valve is connected to the circuit at the vacuum pump, so that a pulse of compressed air can be driven back through it (20).
[0014]
- The blow-off 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 pneumatic.
[0016]Suction Cup (12). The suction cup (12) is provided once in this arrangement. Each cup presents a sealing lip to the workpiece and is evacuated through its own connection. The cups are of the flat form. The cups are made of silicone.
[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]Manifold (16). The manifold (16) is provided once in this arrangement. The manifold receives the vacuum and distributes it to the outlets that feed the face. The manifold has 6 outlets.
[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]Blow-Off Valve (20). The blow-off valve (20) 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
[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 suction cups seal the workpiece, the suction cups are 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]
- Before the workpiece reaches the set-down position, the workpiece is blown off by the blow-off valve.
[0026]
- The workpiece is held until the blow-off valve has opened the circuit.
[0027]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
[0028]In one embodiment the gripping face carries 1 suction cups 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 suction cups is doubled for the same envelope, which suits a workpiece that is lighter but less rigid.
7. Alternative Configurations
[0029]The gripping face may instead use a flat cup, which is stiffer laterally but needs the face and the workpiece to meet squarely. The gripping face may instead use an array of discrete cups, which concentrates the holding force at the lips and needs a sealing surface. 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. An isolation valve may be added in the line to each zone, which allows one part of the face to be cut from the circuit while the rest holds its vacuum. 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
[0030]Each parameter below is stated with what it changes in the arrangement. The locking of the tool-change interface is pneumatic in the arrangement described; varying it changes what has to be present at the interface for the tool to stay attached. The form of the suction cup is flat in the arrangement described; varying it changes the contact area and the behaviour of the lip on a curved workpiece. The material of the suction cup is silicone in the arrangement described; varying it changes the friction at the lip and the tolerance of the face to oil and heat. The outlets of the manifold is 6 in the arrangement described; varying it changes how many connections can be fed from one inlet without dividing the face. 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
[0031]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
[0032]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 US-11427405-B1, US-11858125-B2, US-2016214812-A1, US-8006968-B2, US-8132312-B2. Their text is not reproduced here; the description above is generated from the structure of the combination.
11. Figures
