US 4,042,734 A · Method for spray coating

Abstract

The disclosure is directed to a method and apparatus for spray painting of large, irregularly shaped articles, where the shape and size of the articles require relative movement between the article and the spray applicator in at least two axes. One, and preferably a plurality of atomizing nozzles are arranged to be rotated about a predetermined axis and are oriented at a substantial angle to such axis. The article to be coated is conveyed past the spray station along one axis, and the rotating spray unit is reciprocated along a second axis at right angles to said axis of conveyance. The orientation and positioning of the atomizing heads is such that the spray fans intercept the primary work surfaces relatively close to the intersection therewith of the axis of spray head rotation. In addition, the rate of spray head rotation is so controlled, in relation to the rate of reciprocation and the rate of conveyance that the spray fans of coating material describe a path in the nature of a tight prolate cycloid. During rotation of the angled spray heads, the various surfaces of an irregularly shaped article are directly exposed to the spray heads and are thoroughly coated.

Claims17

Dependent claims

A process for spray coating of irregularly shaped articles, which comprises

a. progressively conveying the articles along a conveying axis through a substantially enclosed spray chamber,
b. directing one or more spray fans of coating material toward said article,
c. rotating said spray fans about a rotational axis disposed at a large angle to the conveyance axis,
d. said spray fans being directed at a substantial angle with respect to the axis of rotation thereof,
e. reciprocating said spray fans along a reciprocation axis at a substantial augle to said conveying axis,
f. said spray fans being rotated at a rate such, in relation to the speed of reciprocation and the speed of conveyance, that said spray fans described tight prolate cycloids in which the effective ratio of rolling circle radius to tracing point radius (a/b) is 1 to at least about 5.

3 more elements

A process for spray coating of irregularly shaped articles, which comprises

a. rotating at least one spray fan of atomized coating material about a predetermined rotational axis,
b. said spray fan being oriented at a substantial angle to said axis,
c. said spray fan comprising a shaped fan of air-atomized material,
d. relatively moving said rotational axis and said workpiece whereby, in the course of coating said workpiece, said axis of rotation at one or more times lies outside of the workpiece perimeters, in front of the leading edge, behind the trailing edge, above the upper edge and below the lower edge, whereby to apply coating material to all of said edges during the course of spray fan rotation, and whereby substantial amounts of overspray are generated,
e. substantially confining said spray fans to a predetermined spraying zone,
f. causing the overspray liquid from said spraying zone to be drained through a wet wall baffle system and into a sump for recycling,
g. withdrawing air from said spraying zone through said wet wall baffle system whereby to substantially strip overspray mist from said withdrawn air,
h. withdrawing said air in amounts sufficient to maintain said spraying zone at a negative pressure relative to ambient, and
i. recycling at least some of said withdrawn air.

6 more elements

Dependencies are inferred from the claim text.

Method for spray coating

Life of this patent

Method for spray coating

Life of this patent

Abstract

Claims17