GB860583A - Method of and apparatus for cleaning or degreasing objects - Google Patents

Abstract

A method of cleaning or degreasing metal objects comprises first treating the objects with a cleaning liquid in liquid or vapour form, and then immersing the objects in a bath of the solvent where they are subjected to ultrasonic radiation generated piezo-electrically within the bath, the means of generation being out of direct mechanical contact of the objects. As shown, an apparatus suitable for the process comprises a housing 1 which is completely closed except for an offset loading hood 2. Inside are contained three wells 3, 4, and 5, the solvent in well 3 being continuously boiled by coil 6, and the resulting vapour being condensed by cooling jacket. The condensed vapour is collected in a gutter 10 and passed through pipe 11 (Figs. 2 and 4) to water separator 12. The solvent outlet 13 of the separator is connected by pipe 15 to solvent reservoir 16 and through pipe 17 to spray sump 18. Wells 3, 4, and 5 are drained by pipes 25, 26, and 27 which all lead into line 23 which, in turn, is connected to the suction side of pump 20a. The suction side of this pump is also connected to line 24 which extends to the bottom of storage tank 16, while the discharge side of pump 20a is connected with <PICT:0860583/III/1> <PICT:0860583/III/2> <PICT:0860583/III/3> <PICT:0860583/III/4> <PICT:0860583/III/5> <PICT:0860583/III/6> sump 18 is provided with connection 41 which permits solvent to overflow into well 5. Pump sump 18 is also connected by line 42 to pump 43, which pumps solvent to spray header and nozzles 154 through pipes 152, 153. Well 5 is provided at the bottom with a heating coil 46 to maintain the solvent at the correct temperature (110-140 DEG F. for trichlorethylene; 140-170 DEG F. for perchlorethylene; 58-78 DEG F. for methylene chloride). Work objects to be cleaned are placed on carriers 80 which are hung from bars 79 between the chains of an endless double chain conveyer 50, the path of which is described by a system of sprocket wheels 51-67 (Figs. 1 and 5), and which is driven by motor 77 with intermittent stops so that the objects on the carriers 80 reside for a definite period of time in well 5. The objects are loaded at 2 and then pass first into well 3 where the liquid level is held either at level L1 or at L4, depending on the top of storage tank 16 by line 39 and with each of wells 3, 4, and 5 through lines 33, 34, and 35 branching off line 32. Interposed valves control the flow of solvent in all lines. Pump whether a liquid or vapour treatment is desired, then into rinsing well 4, where the temperature of the solvent is above that in well 5, and finally into ultrasonic well 5 (Fig. 5) where they are subjected to ultrasonic radiation, while immersed in solvent, suitably for a period of 3-20 seconds, the radiation being of a frequency 10 kc/s.-10 Mc/s., and produced by a pair of transducers 90 energized by oscillator unit 140. The transducers, which are of cylindrically-elongated arcuate section and may be made of barium titanate, are suitably mounted concave side uppermost, the objects on the carriers passing over them and out of direct mechanical contact. From well 5, the conveyer passes the objects upwards through the spray from the spray nozzles 154, and then through the final heating stage, whence they emerge clean and dry, and are off-loaded at 2. Specifications 860,580, 860,581 and 860,582 are referred to.