Abstract
A foam-pad vacuum gripping tool comprising one mounting flange, four foam pads, one vacuum pump, one isolation valve, one manifold, one pressure sensor, one contact detector and one blow-off valve. When the foam pads reach the workpiece, the foam pads are evacuated by the vacuum pump. 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 foam-pad vacuum gripping tool: four foam pads carried on a mounting flange, fed by a vacuum pump. It is arranged for cutting part of the circuit while the rest holds vacuum, verifying that the workpiece is held before the arm moves, starting the cycle at the moment of contact, clearing the face at release and holding a workpiece that a rigid lip cannot seal against. 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 mounting flange. The mounting flange carries the whole assembly and presents the bolt pattern that meets the robot.
[0003]Four foam pads. Each foam pad presents a compliant face to the workpiece; the holding force is spread over the contact area rather than concentrated at a lip. The count of four follows from the arrangement: one gripping element per manifold outlet. The pad is of open cell foam.
[0004]One vacuum pump. The pump draws the circuit down mechanically and adds its own mass to the moving assembly.
[0005]One isolation valve. The isolation valve sits in the line it controls; closing it cuts that line without disturbing the rest of the circuit. Isolation is common.
[0006]One manifold. The manifold receives the vacuum at one inlet and distributes it to its outlets. The manifold has four outlets.
[0007]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 at the manifold.
[0008]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.
[0009]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.
[0010]The foam pads are carried on the tool side of the mounting flange.
[0011]The manifold is fixed to the tool side of the mounting flange.
[0012]The vacuum pump is fixed to the tool side of the mounting flange.
[0013]The isolation valve is placed in the line from the vacuum pump, so that closing the valve cuts the whole circuit from the supply.
[0014]The manifold inlet is connected to the isolation valve outlet, which supplies every outlet of the manifold.
[0015]Each manifold outlet feeds one foam pad by its own vacuum line, so that the four outlets feed four foam pads.
[0016]The pressure sensor is tapped into the manifold body and reads the pressure common to every outlet.
[0017]The contact detector is mounted on the gripping face and reports the moment a workpiece is present against the gripping face.
[0018]The blow-off valve is connected to the circuit at the line downstream of the isolation valve, so that compressed air can be driven back through the circuit to the face.
[0019]The robot side of the mounting flange is bolted to the robot flange.
[0020]The pump motor is supplied from the electrical supply of the cell.
[0021]The blow-off valve is fed from the compressed air supply of the cell.
[0022]The isolation valve and the blow-off valve are switched by the cell controller; the pressure sensor and the contact detector report to the cell controller.
3. Operating sequence and conditions
[0023]
- After the contact detector has detected the workpiece, the vacuum supply is actuated by the cell controller.
[0024]
- When the foam pads reach the workpiece, the foam pads are evacuated by the vacuum pump.
[0025]
- When the vacuum level exceeds the gripping threshold, a secure grip is signalled by the pressure sensor.
[0026]
- The workpiece may not be lifted unless the pressure sensor signals a secure grip.
[0027]
- After the vacuum level has exceeded the gripping threshold, the isolation valve is closed by the cell controller.
[0028]
- While the isolation valve is in the closed state, the vacuum downstream of the valve is maintained by the sealed gripping face.
[0029]
- 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.
[0030]
- The workpiece is held until the blow-off valve has opened the circuit.
[0031]The cell controller reads the pressure sensor (the manifold) and the contact detector (on the gripping face) and commands the blow-off valve, the isolation valve; no sensor drives an actuator directly.
4. Parameters and operating assumptions
[0032]Parameter values of this embodiment: material of the foam pads: sponge (sets the compliance of the sealing face); porosity of the foam pads: open cell (sets whether air passes through the pad body or only through openings cut through it); drive medium of the vacuum pump: electric (sets the supply the pump motor needs from the cell); control of the isolation valve: common (sets which part of the circuit the valve cuts: one branch line on its own or the whole circuit); material of the isolation valve: steel; outlets of the manifold: four (sets how many lines can be fed from one inlet); placement of the pressure sensor: at the manifold (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).
[0033]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.
[0034]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.
[0035]The open-cell foam passes air through its whole face, so an uncovered part of the face draws air through the pad itself; the supply is sized for that continuous flow and the pad relies on flow restriction through the foam, not on a seal, to hold vacuum behind a covered area.
[0036]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
[0037]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-4385681-B1, US-10163334-B1, US-10549431-B2, US-11427405-B1, US-2022339798-A1, US-8006968-B2, US-8132312-B2; their text is not reproduced, and the description above is generated from the structure of the combination.