Described herein is an electrostatic spray coating machine of the type which has a plural number of supporters (31) at intervals around the circumference of a housing (2) as electrode retainer rods for holding external electrodes (32). Each supporter (31) is formed with an oblique surface (31A) at the fore end thereof to provide a concealing projection (31B) on the inner side of the fore end of the supporter (31). As a result, when seen from the rotary atomizer head (5), the discharge distance (H') betweewn the fore end (32A) of each external electrode (32) and the rotary atomizer head (5) is increased to permit application of a higher voltage to the external electrodes (32).

An electrostatic repulsion device is provided in an electrostatic spray paint booth having a grounded ceiling and conveyor to improve transfer efficiency in applying the paint to a workpiece and maintain a safe working environment without requiring protective fencing between an operator and the application equipment. The device includes an electrical cable having a resistive conductor surrounded by an insulation layer. The conductor provides a low electrical capacitance when connected to a high voltage source. Conductive pins are mounted along the cable through the insulation to contact the conductor and are arranged parallel to the spray path in two longitudinal groups, with the first set being diametrically opposed to the second set. Each pin has a discharge end that is substantially flush with the outside surface of the insulation layer. The device is transversely mounted with respect to a spray path of charged, atomized paint particles dispensed from a non-conductive, rotary spray device, so that an electrostatic field from the first set of conductive pins repels the atomized, charged paint particles away from the grounded ceiling and conveyor of the paint booth towards a workpiece. The electrostatic field produced by the second set of conductive pins bleeds accumulated charge from the repulsion device before a high energy discharge can occur whenever a grounded object comes into proximity with the device. This safety feature eliminates the need for protective fencing and interlocks within the spray booth.

The rotary atomizer coater is particularly adaptable to a high voltage rotary atomizer coater which can be robot mounted. A rotatable bell cup, which is mounted on a turbine driven shaft is positioned within a housing. A fluid tube within the housing includes a fluid discharge tip which extends through an inlet opening in the bell cup for supplying charged coating fluid directly to the inner surface of the bell cup interior which is open to atmosphere. An electrical resistor is mounted between the fluid discharge tip and a power supply within the housing. When a grounded object approaches the bell cup, the current between the bell cup and the grounded object will increase and voltage drop across the resistor results, thereby reducing the voltage at the bell cup and diminishing the potential for a high energy spark.

A rotary atomizing electrostatic coating apparatus includes a plurality of paint nozzles and a solvent nozzle. Each paint nozzle communicates uniquely with a respective paint source separate by respective paint passages which are pathwise separate from each other. In each paint passage, a respective paint valve is installed. When changing a painting color according to the present invention, the paint filling the operating paint nozzle and the paint passage connected thereto is not washed out by a washing solvent, so that the amount of paint wasted when changing the painting color is decreased to substantially zero and the working time period for changing the painting color is also shortened. A corresponding method of use of such an apparatus is also disclosed which reduces the amount of paint wasted and the amount of solvent used during a step of switching from a first paint to a second paint.

A sprayer, such as an electrostatic rotary bell-shaped sprayer is made from a material comprising carbon fiber, teflon and polypropylene. An exemplary material comprises about 30% carbon fiber, about 5% teflon, and about 65% polypropylene. When used for electrostatic spraying, the sprayer provides a mist containing an electrical charge equal to at least 20% of the charge applied to the sprayer. For example, when 100,000 volts are applied to the sprayer, the downstream mist contains a charge of at least 20,000 volts. The sprayer can also include a plurality of pits arranged near its outer edge in an offset matrix pattern producing therebetween two sets of intersecting surface lines. The sprayer can further include a deflection part with a pointed rear center section positioned opposite an opening in a base part. A plurality of axial passages positioned around the pointed section and extending toward a front surface of the deflection part allow for the passage of cleaning fluid therethrough. The device according to the invention provides better atomization and better adhesion of paint to a grounded article such that less paint is required than is required with conventional devices, and further provides ease of cleaning and increased durability.