OPENTECHNICAL PUBLICATION OT-2026-000006856 Three finger mechanical gripper, ejector fed, contact triggered, stripped from the face, electric drive Published: 2026-09-16T08:51:19.172730Z Permanent URL: https://opentechnical.org/p/OT-2026-000006856 Categories: Robotics & Automation > End Effectors > Mechanical Grippers ------------------------------------------------------------------------ ABSTRACT An end effector for mechanical gripping end effectors for robotic handling is described. The tool comprises a mounting flange (10), a gripper finger (12), a ejector (14), a contact detector (16), a separating element (18). The arrangement addresses separating a workpiece that stays on the face after the grip is released, where a thin or slightly adhesive workpiece can follow the face upwards even with the circuit open. The description covers what pushes the workpiece off, what it acts on, and when it acts relative to the release. 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 mechanical gripping end effectors for robotic 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 separating a workpiece that stays on the face after the grip is released. The difficulty is that a thin or slightly adhesive workpiece can follow the face upwards even with the circuit open. 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 pushes the workpiece off, what it acts on, and when it acts relative to the release. 3. System Overview [0003] The tool comprises the mounting flange (10), the gripper finger (12), the ejector (14), the contact detector (16), the separating element (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. [0006] - The mounting flange is bolted to the robot flange (10). [0007] - The finger drive is fed from the compressed air supply of the cell (12). [0008] - The fingers are carried on the mounting flange (12). [0009] - Compressed air is fed to the ejector from the compressed air supply of the cell (14). [0010] - The detector watches the fingers and reports when a workpiece is present at that face (16). [0011] - The separating element is driven from the compressed air supply of the cell (18). [0012] - The separating element acts on the workpiece held at the fingers (18). [0013] - The separating element is switched by the contact detector (18). 4. Components [0014] Mounting Flange (10). The mounting flange (10) is provided once in this arrangement. The flange carries the whole assembly and presents the bolt pattern that meets the robot. [0015] Gripper Finger (12). The tool carries 3 gripper fingers. The fingers close onto the workpiece and hold it by form closure rather than by suction. The fingers are driven by a electric actuator. [0016] 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 1 stages. [0017] 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 frame. [0018] Separating Element (18). The separating element (18) is provided once in this arrangement. The separating element acts on the workpiece directly, so release does not depend on the circuit alone. The workpiece is pushed off after set-down. 5. Operation [0019] 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. [0020] - When the gripper reaches the gripping position, the fingers are closed by the electric actuator. [0021] - While the fingers are in the closed state, the workpiece is clamped. [0022] - After the workpiece has reached the set-down position, the workpiece is released by the separating element. [0023] - After the workpiece has reached the set-down position, the fingers are opened. [0024] 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 [0025] In one embodiment the gripping face carries 3 gripper fingers 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 gripper fingers is doubled for the same envelope, which suits a workpiece that is lighter but less rigid. 7. Alternative Configurations [0026] The fingers may be replaced by a vacuum face, which needs only one accessible surface but requires that surface to be sealable. They may also be replaced by a magnetic face where the workpiece is ferrous, which removes the actuator and its supply. 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. 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 [0027] Each parameter below is stated with what it changes in the arrangement. The count of the gripper finger is 3 in the arrangement described; varying it changes the number of contact points and the stability of the grip on an irregular workpiece. The drive medium of the gripper finger is electric in the arrangement described; varying it changes the force curve during closing and what the tool needs from the cell. The stages of the ejector is 1 in the arrangement described; varying it changes the flow drawn at low vacuum and the air consumed to hold a sealed 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 timing of the separating element is after set-down in the arrangement described; varying it changes whether stripping happens with the circuit still closed or after it is open. 9. Additional Implementations [0028] A pressure sensor may be tapped into the circuit so that the state of the grip is observable, and the motion that follows the grip may be made conditional on the level it reports. The whole assembly may be carried on a tool-change interface so that it can be exchanged between jobs without dismantling the tool. 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 [0029] 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-10549431-B2, US-2022339798-A1, US-2023381975-A1, US-8043071-B2, WO-2008134339-A4. Their text is not reproduced here; the description above is generated from the structure of the combination. 11. Figures FIG. 1 Block diagram of the tool, with the medium carried by each connection. FIG. 2 Elevation of the gripping face on its mounting. FIG. 3 Signal path between the controlled elements and the cell controller. FIGURES FIG. 1 Block diagram of the tool, with the medium carried by each connection. FIG. 2 Elevation of the gripping face on its mounting. FIG. 3 Signal path between the controlled elements and the cell controller. ------------------------------------------------------------------------ OpenTechnical publication OT-2026-000006856 Published 2026-09-16T08:51:19.172730Z https://opentechnical.org/p/OT-2026-000006856