--- publication_id: "OT-2026-000006066" title: "Bellows cup vacuum gripper, plant vacuum fed, pressure verified, contact triggered on the face" published_at: "2026-09-16T08:21:10.192583Z" canonical_url: "https://opentechnical.org/p/OT-2026-000006066" categories: - "robotics-automation/end-effectors/vacuum-grippers" - "lifting-positioning-manipulation/vacuum-lifting/sealing-and-suction-pads" - "sensors-controls-machine-vision/position-and-presence-sensing/inductive-sensors" - "industrial-components-safety-infrastructure/plant-utilities/vacuum-supply" keywords: - "bellows cup" - "contact detector" - "plant vacuum connection" - "pressure sensor" - "tool-change interface" - "approach detection" - "end of arm tooling" - "plastic" --- # Bellows cup vacuum gripper, plant vacuum fed, pressure verified, contact triggered on the face ## Abstract An end effector for vacuum end-of-arm tooling with compliant bellows cups is described. The tool comprises a tool-change interface (10), a bellows cup (12), a plant vacuum connection (14), a contact detector (16), a pressure sensor (18). 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 vacuum end-of-arm tooling with compliant bellows cups. 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 bellows cup (12), the plant vacuum connection (14), the contact detector (16), the pressure sensor (18). 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. - The tool-side plate of the tool-change interface is bolted to the robot flange (10). - Each bellows cup is connected to the vacuum supply of the cell by a vacuum line that runs into the bellows body (12). - Each bellows cup is mounted on the tool-change interface (12). - The detector watches the bellows cups and reports when a workpiece is present at that face (16). - The pressure sensor is tapped into the line at the vacuum supply of the cell and reads the pressure in that line (18). ## 4. Components [0011] **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. [0012] **Bellows Cup (12).** The bellows cup (12) is provided once in this arrangement. Each cup is folded so that it shortens under vacuum and takes up a height difference between the face and the workpiece. Each cup carries 1 folds. The cups are made of plastic. [0013] **Plant Vacuum Connection (14).** The plant vacuum connection (14) is provided once in this arrangement. The connection takes vacuum from the plant line, so the tool carries no generator of its own. [0014] **Contact Detector (16).** The contact detector (16) 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 gripping face. [0015] **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. ## 5. Operation [0016] 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. - When the bellows cups seal the workpiece, the bellows cups are evacuated by the vacuum supply of the cell. - After the contact detector has detected the workpiece, the vacuum supply is actuated. - When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor. - The workpiece may not be lifted unless the pressure sensor signals a secure grip. [0021] 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 [0022] In one embodiment the gripping face carries 1 bellows 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 bellows cups is doubled for the same envelope, which suits a workpiece that is lighter but less rigid. ## 7. Alternative Configurations [0023] 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 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 plant connection may be replaced by an ejector or a pump carried on the tool, which decouples the tool from the site supply at the cost of mass or of continuous air consumption. 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. ## 8. Parameter Variations [0024] 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 folds of the bellows cup is 1 in the arrangement described; varying it changes the travel taken up at the face and the lateral stiffness under load. The material of the bellows cup is plastic in the arrangement described; varying it changes the friction at the lip and the resistance of the fold to fatigue. The placement of the contact detector is on the gripping face 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. ## 9. Additional Implementations [0025] 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 [0026] 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-4489564-B1, US-10259123-B2, US-11427405-B1, US-11858125-B2, US-2022339798-A1. Their text is not reproduced here; the description above is generated from the structure of the combination. ## 11. Figures ![FIG. 1](figures/fig-001.svg) Block diagram of the tool, with the medium carried by each connection. ![FIG. 2](figures/fig-002.svg) Elevation of the gripping face on its mounting. ![FIG. 3](figures/fig-003.svg) Signal path between the controlled elements and the cell controller.