Abstract An apparatus for and a method of electrostatically charging coating material. The apparatus includes a composite member terminating in an extended edge adjacent with coating material is formed into a charged spray. The composite member is constructed of an electrically non-conducting binder material such as a polymeric material, for example, phenolic resin and includes in the binder material an electrically conducting material such as graphite or copper, and reinforcing material such as glass fibers or woven hemp or flax (canvas). The composite member has desirable properties such as low effective electrical capacitance despite a necessary large physical size, good impact and tensile strength, and good chemical and mechanical resistance to the action of the ingredients of the coating material. The composite member is adapted to be connected to a high voltage source such as a direct current voltage source capable of supplying up to 100,000 volts or more to the composite member. Means such as a coating material feed tube and nozzle supplies to the composite member a suitable liquid such as paint, or dry coating material such as powder. A suitable means is used to move the coating material across the composite member to the extended edge in the vicinity of which the coating material is formed into a charged spray. The last named means may include an inner hub and an outer hub for cooperatively retaining the composite member.
In an electrostatic coating apparatus including a conductive member having high resistance and forming an annular electrostatic atomizer, a central member connected to a rotating shaft and carrying said conductive member, a resistive high voltage connection between a source of high voltage and said conducTive member, and an insulating support for said rotating shaft and said high voltage connection, the improvement in which the central member is comprised of two separable parts, one part of which is connected to said rotating shaft and includes semiconducting connection connected with said high voltage connection, and the other part of which is fastened to said one part to hold the conductive member removably therebetween and connected with said semiconducting connection.
Claim 2
Dependent Claim
117 words
In an electrostatic coating apparatus including a conductive member having high resistance and forming an annular electrostatic atomizer, a central member connected to a rotating shaft and carrying said conductive member, a resistive high voltage connection between a source of high voltage and said conducTive member, and an insulating support for said rotating shaft and said high voltage connection, the improvement in which the central member is comprised of two separable parts, one part of which is connected to said rotating shaft and includes semiconducting connection connected with said high voltage connection, and the other part of which is fastened to said one part to hold the conductive member removably therebetween and connected with said semiconducting connection.
Claim 3
Dependent Claim
41 words
The apparatus of claim 1 wherein the high voltage connection includes a semiconducting ring surrounding the rotating shaft, and the semiconducting connection is a semiconducting rod carried adjacent the semiconducting ring within the interior of said one part of the hub.
Claim 4
Dependent Claim
41 words
The apparatus of claim 2 wherein the semiconducting rod is oriented within said one part with its end opposite said ring and said one part and rod are spaced from said ring, said space forming a current path with low conductivity.
Claim 5
Dependent Claim
25 words
The apparatus of claim 3 wherein the insulating support encloses resistors forming the resistive high voltage connection, the semiconducting ring, and a resistive connection therebetween.