--- publication_id: "OT-2026-000034604" title: "Single bellows cup vacuum gripper, single stage ejector, supply line pressure sensor, sustained blow-off before set-down, on a tool changer" published_at: "2026-09-17T08:22:51.876169Z" canonical_url: "https://opentechnical.org/p/OT-2026-000034604" categories: - "robotics-automation/end-effectors/vacuum-grippers" - "sensors-controls-machine-vision/position-and-presence-sensing" - "sensors-controls-machine-vision/force-and-pressure-sensing/vacuum-sensors" - "robotics-automation/end-effectors/tool-changers" keywords: - "bellows compliant vacuum tool" - "tool-change interface" - "bellows cup" - "ejector" - "pressure sensor" - "contact detector" - "blow-off valve" - "blow off release" - "compressed air supply" - "contact sensing" --- # Single bellows cup vacuum gripper, single stage ejector, supply line pressure sensor, sustained blow-off before set-down, on a tool changer ## Abstract A bellows-cup vacuum gripping tool comprising one tool-change interface, one bellows cup, one ejector, one pressure sensor, one contact detector and one blow-off valve. When the bellows cup reaches the workpiece, the bellows cup is 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: one bellows cup carried on a tool-change interface, fed by an ejector. It is arranged for verifying that the workpiece is held before the arm moves, starting the cycle at the moment of contact, 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 mechanical lock. [0003] **One bellows cup.** Each bellows cup is folded so that it shortens under vacuum and takes up a height difference between the face and the workpiece. Each bellows cup has three folds. [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 pressure sensor.** The pressure sensor taps the line it is placed in and reports the vacuum level in that line. The pressure is measured in the supply line. [0006] **One contact detector.** The contact detector reports the moment a workpiece is present at the gripping face; its sensing technology is not fixed by this arrangement. The contact detector is mounted on the gripping face. [0007] **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 sustained blast. The blow-off pulse is given before set-down. [0008] The bellows cup is carried on the tool side of the tool-change interface. [0009] The ejector is fixed to the tool side of the tool-change interface. [0010] The bellows cup is connected to the ejector outlet by a single vacuum line, so that the face is evacuated through that line. [0011] The pressure sensor is tapped into the line between the ejector and the bellows cup and reads the pressure of the whole circuit. [0012] The contact detector is mounted on the gripping face and reports the moment a workpiece is present against the gripping face. [0013] The blow-off valve is connected to the circuit at the ejector outlet, so that compressed air can be driven back through the circuit to the face. [0014] The robot side of the tool-change interface is bolted to the robot flange. [0015] The ejector is fed from the compressed air supply of the cell. [0016] The blow-off valve is fed from the compressed air supply of the cell. [0017] The blow-off valve is switched by the cell controller; the pressure sensor and the contact detector report to the cell controller. ## 3. Operating sequence and conditions - After the contact detector has detected the workpiece, the vacuum supply is actuated by the cell controller. - When the bellows cup reaches the workpiece, the bellows cup is evacuated by the ejector. - 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. - 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 workpiece is held until the blow-off valve has opened the circuit. [0024] The cell controller reads the pressure sensor (the common supply line) and the contact detector (on the gripping face) and commands the blow-off valve; no sensor drives an actuator directly. ## 4. Parameters and operating assumptions [0025] Parameter values of this embodiment: locking of the tool-change interface: mechanical (sets what has to be present at the interface for the tool to stay attached); folds of the bellows cup: three (sets the travel taken up between the face and the workpiece, and the lateral stiffness of the cup under load); material of the bellows cup: 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); placement of the pressure sensor: in the supply line (sets where in the circuit the reading is taken and what it describes); placement of the contact detector: on the gripping face (sets where the presence of the workpiece is detected); duration of the blow-off valve: a sustained blast (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). [0026] 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. [0027] The blow-off is a sustained blast: the valve stays open for the whole release so that the face is cleared of dust and the workpiece is pushed positively away. [0028] The lock is engaged by a manually operated lever on the interface; no supply crosses the interface for the lock, and tool exchange needs an operator at the tool. [0029] 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 [0030] 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-11427405-B1, US-11858125-B2, US-2022339798-A1, US-8132312-B2, WO-2008134339-A4; their text is not reproduced, and the description above is generated from the structure of the combination.