GB732534A - Body painting machine - Google Patents

Abstract

<PICT:0732534/III/1> <PICT:0732534/III/2> <PICT:0732534/III/3> A machine for painting vehicle bodies comprises mechanism for rotating a body about an axis, and for transporting the body longitudinally along said axis, paint spraying means being aimed towards the path described by the body. The spraying means are maintained at a constant distance from the body and traversed to maintain constant the velocity at which the body surface moves past a nozzle in the spraying zone. A car body 1, Fig. 9, is mounted about a horizontal spindle 2, about which the body revolves, carried by a cradle on an overhead conveyer so as to transport the body longitudinally along its axis of rotation past a framework 3 supporting the paint spraying means. As the body approaches the painter the cradle is engaged by a carriage 31 (Figs. 1 and 4), which is driven the length of the machine at the same speed as the conveyer. The carriage 31 has a device which engages the rotatable mounting of the body and causes the body to slowly turn in an anti-clockwise direction on its axis 2 as it moves along the machine. The carriage is disengaged from the cradle at the end of the movement past the machine, and the carriage is returned to its first position by a chain 33, Figs. 1 and 4. Paint guns 4 (only one is shown in Figs. 9 and 4) move in and out on the machine so that the distance from the gun nozzle 5 to the body surface 6, Fig. 9, remains constant in the various rotative positions. In position A the radial distance from the body surface to the axis 2 is less than in B, so the peripheral velocity of the body surface in A is less than in B; the speed differential in B is reduced by rotating the gun in a clockwise direction. The gun is rotated clockwise when high corners of the body are passing it, and anti-clockwise when low sections are passing. In C the re-entrant surface 8 passes the gun and the shoulder 7 tends to shield surface 8, so the gun is turned clockwise and aimed up into the re-entrant surface 8. Further guns (not shown) may be turned on briefly at the beginning and end of the cycle to spray the central end surfaces of the body. Three square shafts 34, 35 and 36, Figs. 1 and 4, are oscillated by three cam followers 134, Fig. 1, travelling along three fixed cam plates 138, 140 and 142 (selected for each body shape) extending the length of the painter. The square shaft 36 operates valves which switch the spray guns on and off; the shaft 35 causes the p guns to traverse when required by means of chains 213 and 214, Fig. 4, passing round sprockets on arms 206 and 210; the third shaft 34 operates a spur gear 186, Figs. 1 and 4, engaging a rack 187, Fig. 1, forming part of a reciprocating bar 188, Fig. 4, carried between pairs of rollers 189 and 190, at the end of which is a gun 4 which is thus kept at a constant distance from the sprayed surface. Three cylinders, two, 153 and 154, being shown in Fig. 4, are operated to lift the cam followers out of engagement with the three cams while the carriage is returned at the end of the cycle. Specification 652,720 is referred to.