An electrostatic device for spraying electrically conductive liquid coating product comprises a storage tank for the product in which the product is at a high voltage. The tank is defined in a substantially cylindrical cavity formed in an insulative material body and inside in which is a piston forming in the cavity a mobile wall separating a coating product chamber from an actuation chamber filled with an electrically insulative actuation fluid. The body is fixed to a conductive material socket which is grounded and to which is connected an actuation fluid supply circuit extending between the socket and the actuation chamber and discharging into the actuation chamber near a back wall of the cavity which is not in contact with the coating product. A section of the supply circuit runs substantially parallel to the cavity in the direction away from the socket starting from the back wall.
In a process and device for spraying a coating product onto an article from a sprayer to which coating product is supplied from a reservoir equipped with a piston which is moved along a path in order to transport the coating product to the sprayer, movement of the piston is controlled as a function of movement of the sprayer relative to the article.
An automatic coating apparatus which is arranged to guarantee higher operational reliability, particularly to preclude coating defects as caused by malfunctioning of a cartridge gripper (56) or by the use of an non-replenished or deficiently replenished paint cartridge. A cartridge gripper assembly (55) is constituted by a gripper member (56) with gripper claws for gripping a paint cartridge (25), a grip detector switch (67) which is adapted to detect whether or not the paint cartridge (25) is securely gripped by the gripper. (56), and a replenishment level detector switch (68) which is adapted to detect whether or not the paint cartridge (25) is replenished with paint to a predetermined extent. Therefore, as the paint cartridge (25) is gripped by the cartridge gripper (56), the grip condition on the paint cartridge (25) can be monitor by the grip detector switch (67). At the same time, a replenished paint level within the cartridge (25) can be monitored from outside by the replenishment level detector switch (68).
An electrostatic spray device contains a tube-like spray element (3); at least one charging electrode (12) to transfer electrostatic charges to the powder; at least one counterelectrode (44) arranged in the vicinity of the charging electrode (12), which is connected to an electrical potential (20) different from the charging electrode (12), so that it takes up at least part of the free ions generated during electrical charging of the powder; at least one ring-shaped element (44; 68; 74) which forms or carries the counterelectrode (44; 64; 74, 76) and extends around the downstream segment (72) of the spray element (3), on which it is radially supported; at least one connection ridge (78) outside the spray element (3), which carries the ring-shaped element (74) at its downstream end (79) and can be attached to the spray element (3) by its upstream end; and an electrical connection between the electrical potential connection (20) and the counterelectrode (44) by way of the connection ridge (78).
By provision of paint cartridges of different colors which are detachably mounted on a coating system, the paint can be changed from one color to another in a multi-color coating operation without necessitating to discharge residues of a previous color. The paint cartridge of each color is replaceably mounted on a housing. Each cartridge is provided with a paint valve (46) which functions to communicate and shut off a paint supply passage in a feed tube. In addition, a thinner valve which serves to communicate and shut off a thinner passage on the housing is provided either on the side of the housing or on the side of the cartridge. These arrangements make it possible to cope with multiple color changes on one coating system. Since both of the paint valve and thinner valve are opened and closed by spray-on and spray-off command signals, respectively, the paint spray can be turned on and off immediately in response to these command signals.
Apparatus and a method are provided for isolating an electrostatic sprayer from an electrically grounded coating product distribution circuit connected thereto. The apparatus includes an electrostatic sprayer carried by a maneuverable robot arm, the sprayer capable of spraying an electrically conductive coating product such as water-based paint onto a workpiece passing in adjacent proximity thereby, on command. The coating product is supplied from a remote source of supply through at least one distribution circuit connected to the sprayer. The apparatus includes therein, carried by the robot arm, an electrically insulative storage tank for the coating product in valved fluid communication with the sprayer. The insulated storage tank is connected to and positioned downstream from a length of electrically insulative supply conduit connected to the distribution circuit and also carried by the robot arm. This conduit includes a cleaning mechanism for cleaning a portion, including all, of this length of supply conduit, in situ, after filling of the storage tank with coating product and before spraying. In this way, substantially all of the conductive coating product is removed from the portion of supply conduit, thereby completely isolating the sprayer electrically from the distribution circuit.
