Patent GB-596858-A (GB)
Title: Improvements in or relating to process and apparatus for forming or coating articlesby dipping
IPC: B29C41/14
Filed: 1944-09-22
Abstract: <PICT:0596858/III/1> Apparatus for coating articles by dipping comprises a dipping frame carrying one or more articles and adapted for vertical movement into and out of a tank, power actuated means, e.g., an electric motor, for raising and lowering the frame, and means controlled by the movement of the frame for reversing, stopping, and changing the speed of the motor at predetermined points in the vertical movement of the frame whereby the rate of movement of the surface of the liquid in the tank over the surface of the articles can be maintained substantially uniform.  Means for providing a "dwell" when the articles are fully immersed and for inverting the articles to prevent the formation of a thickened tip after withdrawal may be included.  In one arrangement in which the dipping frame is brought in turn over each of two tanks containing coagulant and latex, Figs. 1 and 2, the dipping frame 4, 4b, carries a frame 6a, 6b, on a rotatable shaft 6, the articles 5 depending from a bar 5a clamped by a device 7 to the frame 6a, 6b, which is made top-heavy by a weight 6d so that on the release of a locking <PICT:0596858/III/2> <PICT:0596858/III/3> <PICT:0596858/III/4> <PICT:0596858/III/5> device LM (normally locked) and an initial push by a spring loaded plunger (not shown) it will swing through 180 degrees to the dotted line position.  The frame 6a, 6b is returned to its first position by a handle 6g.  The frame 4 runs on wheels 4e on rails 3d, 3e extending across both tanks 8, 9, and connected by a frame 3 which can be raised and lowered by an electric motor 2 mounted on a fixed frame 1 working through screw and nut gearing. The frame 3 carries a shelf 3f on which are mounted a series of switches A 1-9 and B 1-9.  The buttons 10d, Fig. 9, of these switches (one of which is shown at 10) are operated as the dipping frame moves up and down by arms 10c carrying rollers 10e which engage projections P formed at predetermined places in accordance with the shape of the articles on panels 8b, 9b mounted in fixed relationship to the tanks 8, 9.  Other switches C8, C9, 39 (operated by arms C8a, C9a on frame 4), US, ULS, DS (operated by fingers USa, ULSa, DSa on the frame 3) are mounted on the rail 3 and fixed frame 1 respectively.  The sequence of operations is as follows:-The panels 8b, 9b are set to the correct height with respect to the liquid levels in the tanks 8, 9, in their frames 8a, 9a, by setting the points of two gauges (one shown at 8e) on the surface of the liquids in the two tanks by handwheels 8c, 9c. The frame 4 is moved manually into position over the coagulator tank 8, closing safety switch C8 in the motor circuit and switch 39 which brings switches A1-9 into action and isolates switches B1-9.  The operator presses the starter switch and the frames 3 and 4 travel down removing finger ULSa from switch ULS which is thus closed and which allows the motor to continue after the operator has released the starting switch.  The frame 4 travels down at full speed until the articles 5 are just clear of the liquid surface LL, Fig. 11, when projection P1, <PICT:0596858/III/6> Fig. 10, on panel 8b engages its associated roller 10e to operate switch A1 reducing the speed of the motor until the articles are immersed to the line a, Fig. 11, when switch A2 is operated to increase the speed.  Further changes occur at levels at b, c and at d switch A5 is operated to reverse the motor.  Corresponding speed changes occur at c, b &c. on withdrawal which is completed at high speed after the articles are clear of the liquid, the motor finally being stopped by finger ULSa, opening switch ULS. The tank 8 dipping may be repeated by again pressing the starting switch.  Otherwise the frame 4 is moved over to tank 9 opening switch C8 and switch 39 which brings into action switches B1-9 and isolates switches A1-9, and closing safety switch C9 also in the motor circuit in parallel with C8. Opening switch 39 also brings into action when required a time delay and the electro-magnetic release for the locking device LM.  On pressing the starting switch the frame 4 is lowered as before with corresponding speed changes brought about by switches B1-4 but after momentary reversal of the motor by switch B5 the motor is stopped and restarted after a predetermined time by the time delay to provide the "dwell" in the latex.  The articles are then withdrawn with speed changes at appropriate points and when clear of the latex a switch (not shown) on frame 1 is operated to release the locking device LM, the articles then swinging through 180 degrees as described above. The release may be prevented from operating if not required by a manual switch.  US, DS are safety over-running switches to stop the motor should the reversing switch and ULS fail to operate.  In the modification of Fig. 13, the carriage 4 instead of reciprocating is traversed along a continuous rail R from coagulator tank 8, latex tank 9, drying tunnel DT, washing and rinsing tanks back to the tank 8.  The rail R dips over the washing and rinsing tanks to allow the articles to be immersed. Above tanks 8 and 9 rail R has gaps bridged by rail sections Ra movable vertically by independent motors.  As the dipping frame 4 approaches the tanks its weight is taken off the centre rail R by the four wheels 4e engaging sets of side rails 3d1, 3d, 3d11 &c. the rails 3d which are connected to the movable rail section Ra giving a steadier support during dipping.  The panels 8b and 9b (not shown) in this case are movable with the frame 4 and the banks of switches are carried on the fixed frames 1.  Adjustment for liquid level in the tanks 8 and 9 is accomplished by raising and lowering the tanks by hydraulic cylinders H8, H9.  Each motor has its own control circuit, the changeover switch 39 not being required and the time delay being omitted for tank 8 and the electro-magnetic release for the locking device LM omitted for both tanks.  Centering switches are provided to prevent operation except when the frame 4 is centred on a rail section Ra and a hand released device locks the wheels 4e during the dipping operation.