Patent GB-718190-A (GB)
Title: Arrangement for covering plane or curved surfaces with a coating applied by a nozzle
IPC: C03C17/00
Filed: 1951-09-12
Abstract: <PICT:0718190/III/1> <PICT:0718190/III/2> <PICT:0718190/III/3> A device for coating plane or curved surfaces from a nozzle, has a gear imparting to the surface to be coated a rotation around an axis perpendicular to the surface, and imparting to the nozzle relative to this axis of rotation a motion causing a travel of the spraying area of the nozzle over the surface being coated with a component directed towards the axis of rotation, and which at the same time automatically governs at least two of the following three factors determining the thickness of the coating, i.e. the speed of rotation of the surface being coated, and the relative motion between this surface and the nozzle, and additionally, if desired, the nozzle rate of emission, in a manner to produce a desired coating thickness.  As shown, a lens i is rotated about its axis whilst being sprayed from a nozzle h1.  During the spraying the nozzle is given a motion so that its spraying area travels from the margin of the lens towards its centre at a rate which provides a uniform coating, and at the same time the nozzle is rotated so that its spraying axis remains perpendicular to the curved lens surface.  These motions are effected by a gear working as follows: The rotation of a wormwheel k1 on a shaft k rotates a cam k2.  The surface of this cam rests on a roller m which is carried by a bearing block attached to the frame of the device.  Accordingly the rotation imparts a lateral movement to the shaft k which is also imparted to a guide bow e in which it is mounted.  The guide bow e and two straight edges c1 and c2 are rigidly attached to a pin e1 and these straight edges also rest on rollers b1 and b2, and consequently the pin e1, through the lateral movement of the guide bow, moves along the radius of a circle centred at M.  The pin e1 is connected to a pin f by a 1 : 2 gearing system g1, g2, g3, g4 and since pin f is attached to a lever f1 which is constrained by link mechanism to move only parallel to itself, the pin is given a lateral movement.  Further, the swing movement of the straight edges c1 and c2 also impart a clockwise rotation to the gear wheel g1 which is doubled to the gear wheel g4 and pin f.  These motions are transmitted by a curved arm h to the nozzle h1.  Guide bow e has an upwardly directed arm e3 carrying on its upper end a screw e4 which is secured against axial displacement and bears at one end a right-hand thread with a nut e5 and at the other end a left-hand thread with a nut e6.  Each of the straight edges c1 and c2 has an arm c5 and c6 engaging with lateral studs on the nuts e5 and e6.  By this mechanism it is possible with nut e2 loosened to vary the angle between the straight edges by turning the screw e4 and thereby setting any desired radius of curvature for the motion of e1. When the nozzle comes up to the axis of rotation of the lens, the nozzle must either be shut off, or its direction of motion reversed. If it is desired to influence the nozzle emission this may be done by providing it with a throttle valve governed by the motion of the guide bow or of the plate cam.  The gear may be modified to produce a non-uniform thickness of coating.  The change in rate of the motion of the nozzle necessary to produce a uniform coating is treated mathematically.