GB1347392A - Electrostatic coating apparatus - Google Patents

Abstract

1347392 Electrostatic coating RANSBURG CORP 19 April 1971 [17 March 1970] 24388/71 Heading B2L [Also in Division F1] An electrostatic coating apparatus comprises two rotating coating discs 16, 36 and hydraulic drive means 26, 46 for moving the discs transversely to the direction of motion of the article to be coated and a synchronising system 51 for controlling the movement of one device relative to the other in order that a minimum distance is retained therebetween. An article 11 to be coated is carried in a circular path around the coating heads and is maintained at earth potential. The coating heads are rotated by motors 17, 37 and are fed with coating material from supply tanks 19, 39. Each coating head is moved vertically by hydraulic piston and cylinder arrangements 26, 46 so that both move in synchronism. When they are to be moved downwardly a pump 52 feeds pressure fluid via pipe 55 to the upper end of cylinder 45 so that its associated piston 43 moves downwardly. Fluid from below the piston 43 is pumped via a pipe 58 to the upper part of cylinder 25 thus forcing down the piston thereon. Excess fluid from below the piston 23 returns via pipe 53 to the reservoir 50. The limits of traverse of the piston rods are detected by micro switches. If, during downwardly movement it is detected that the lower disc has arrived before the upper coating disc then this unbalance is detected by the means 51 and the upper coating head is allowed to move down before the upstroke begins. During the downward stroke the motor 46 acts as the driving motor and the motor 26 is driven. During the upstroke the roles of the motors are reversed. Synchronising arrangements: Switches 81, 82, 83, 84 are connected to the appropriate solenoids of the solenoid operated four way valves (Fig. 2). To start upward movement fluid is pumped through valves 63, 70 to fluid motor 26 and fluid from the other side of the piston in motor 26 actuates motor 46. When disc 36 reaches its upper limit switch 81 is actuated. When disc 16 reaches the upper limit switch 83 is actuated and valve 63 is energised to connect pump 52 to motor 46 and downward displacement takes place. Switches 84 and 82 are then actuated in sequence to again reverse the motion. If on the upward stroke switch 83 is actuated before switch 81 the appropriate part on valve 70 remains closed so that piston rod 24 cannot move but movement is allowed in motor 46 so that switch 81 can be operated so that the discs are again in register. Similarly on the downstroke the discs can be put into register. A modified form of synchronising means is described in respect of Fig. 3 (not shown).