US 3442251 A
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Description (OCR text may contain errors)
y 1969 R. J. PERKEL 3,442,251
APPARATUS FOR COATING ARTICLES Filed Oct. 18, 1965 Sheet of 2 Ill/l7 1111/ [I [III I q AC R INVENTOR.
[Ill/l [I II I] I u ATTORNEYS May 6, 1969 Filed Oct. 18, 1965 R. J. PERKEL 3,442,251
APPARATUS FOR COATING ARTICLES Sheet of 2 m/vawroe ROBE/27 J. PER (EL BYGZLJMHOLL 75- United States Patent US. Cl. 118-9 2 Claims ABSTRACT OF THE DISCLOSURE A metal coatingapparatus includes a container having a rotary shaft supporting adjustable arm members forming a grid structure for the work parts. At least two tanks which may contain a metal solution and a reducing solution, respectively, are connected by pumps with con duits extending through the container and having nozzles which can spray the solutions upon the work parts rotating along with the grid. A centrifuge may be located below the container for removing metal residue. The container may be provided with a motor operated cover. The motors actuating the shaft, the pumps and the cover may be included in a single circuit connected to a timing mechanism.
This invention relates to performing metallic depositions upon articles to produce various effects such as mirror silvering and the like.
conventionally, metallic depositions have been placed upon articles by electrical or electroless processes. For example, in mirror silvering the process generally used is the application of a silver nitrate solution and a reducer solution to a surface which has been previously catalytically sensitized. The reducing solution, in the case of electroless deposition of silver, is composed of aldehydes, tartrates and other materials.
The apparatus of this invention set forth herein are particularly concerned with the electroless deposition of metallic films. Considering mirror silvering for example, the conventional process of dipping the mirror into the silvering solution is time consuming. Also, since only a small percentage of the silvering solution is deposited on the work, the remaining silver is not utilized. Silver being a noble metal, some recovery process mustbe utilized which is generally gravity filtration and which still results in considerable loss of silver.
An object of the present invention is to avoid the disadvantages of conventional processing and to produce deposition of metal rapidly and inexpensively.
Another object is to provide means for recovery of the unused noble metal which are quick, rapid and inexpensive.
Other objects of the present invention will become apparent in the course of the following specification.
Optionally, the apparatus of the present invention may be utilized for the deposition of both base metals and noble metals and will provide means for recovery of the noble metal while permitting the base material to leave the apparatus without application of recovery techniques and without interference with the recovery of the noble metal.
The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings showing by way of example only, a preferred embodiment of the inventive idea.
In the drawings:
FIGURE 1 is a front perspective view of one form of apparatus which may be utilized to carry out the method of this invention. The cover of the device is shown in open position and the control board is diagrammatically illus trated.
FIGURE 2 is a plan of the apparatus shown in FIG. 1 with the cover in open position.
3,442,251 Patented May 6, 1969 FIGURE 3 is a front view of the apparatus shown in FIG. 2 with the cover in closed position but with portions thereof broken away to show the internal structure.
FIGURE 4 is a right-side view of the apparatus shown in FIGS. 1 through 3.
FIGURE 5 is a sectional view taken along line 5-5 of FIG. 3.
FIGURE 6 illustrates the centrifuge.
FIGURE 7 is a diagram showing the electrical connections.
As shown in the drawings, the apparatus of this invention comprises a housing 11 which is supported upon a plurality of legs 12. Housing 11 is formed with a container portion 13 and a counterbalanced cover 14, which may be opened and closed by a small motor 4-0. Counterbalancing weights 15 are connected to arms 16 which are connected to cover 14 on opposite sides thereof.
A work support 17 is disposed within portion 13 of housing 11. Work support 17 comprises a shaft 18 and a plurality of arm members 19 secured thereto. Arm members 19 form a grid construction permitting support of the work to be operated on by the apparatus of this invention. Shaft 18 is connected to pulley 20, which in turn is connected to pulley 21 by belt 22. Motor 23- bears shaft 24 which is connected to pulley 21 so that work support 17 may be selectively rotated. Tanks 25 and 26 are adapted to contain solutions for metal deposition and are terminated in conduits 27 and 28, respectively. Pumps 29 and 30 intervene conduits 27 and 28 and conduits 31 and 32, respectively, so as to permit the application of pressure to the solutions contained in tanks 25 and 26. Several conduits 31 ad 32 terminate in spray nozzles 33 which are adapted to impinge upon the work support 17 between arm members 19 thereof.
Since the pumps may contain corrosive material, the machine and all exposed parts are preferably made of stainless steel.
Centrifuge 34 consists of rotor 35 and is disposed in operative relationship with conduit 36 communicating with the bottom of container 13. Rotor 35 of centrifuge 34 is electrically controlled by means of a motor 41. The centrifuge 34 is used to remove silver residue, so that clear efiiuent can be removed through the pipe 42. The centrifuge can be emptied from time to time by removing the cover 43.
The machine is operated from the electrical console 44, the electrical connections of which :are indicated only diagrammatically in FIG. 7 since the timing mechanism is well known in the art and does not constitute a part of the present invention.
With the foregoing specific description the operation of this invention will now be explained. In this explanation, by way of illustration, the method used will be the method for electroless deposition of silver but it must be understood that other methods could also be em-' ployed.
A typical cycle begins when an operator depresses the master switch 15; then the cover 14 of housing 11 is opened by a small motor 40. Decorative glass parts indicated diagrammatically as 19a are supported between arms 19 of work support 17. The parts have been presensitized by being immersed in a solution of stannous chloride. The arms 19 are adjustable so that they may support parts of different sizes. Tank 25 is filled with ammoniacal silver nitrate and tank 26 with a reducing solution which may contain formaldehyde and sugar. Cover 14- is now closed by reversing the rotation of motor 40 and pumps 27 and 28 are actuated for a preset period by the motor 23 energizing the solenoids 46 and 47 of the pumps. Then a valve (not shown) is opened so that the excess liquid flows through conduit 36. Centrifuge 34 is operated for a predetermined time period, causing the metal particles to adhere to the solution. After completion of the centrifuging step, the eflluent is permitted to drain through pipe 42.
It should be noted that the cam-operated timing mechanism electrically connected with the console 44 will automatically carry out all these steps after the master switch 45 is actuated and will automatically open the switch when the operations are completed. The time for each operation is preset and can be varied by adjusting the timing mechanism. In the above example, for treating glass parts the spray and rotation cycles are adjusted for 15 seconds each while the centrifuge cycle continues for 30 seconds. Approximately the same time periods can be used for metallizing surfaces of parts molded of plastics, such as acrylonitrile butadiene styrene.
The method of this invention may also be carried out by two separate steps, including a spraying of noble metal followed by a spraying of base metal. The noble metal step would be carried out as set forth above. The base metal step would be similar except that the centrifuge 34 would not be actuated since the recovery of the base metal is not important.
Also, in this invention, the metal and reducer solutions may be heated by the inclusion of conventional heating devices in tanks 25 and 26, thermostats being used for proper temperature control.
While the machine is intended essentially for depositing metallic films, it can be also used for delivering a plurality of liquids simultaneously or sequentially to a racked part; obviously, it can be used to automatically flow coat, wash or otherwise deposit a single liquid upon various parts.
The advantage of the machine of the present invention is that it will automatically deposit metal and will automatically recover all metal which has not been deposited about three or four times faster than prior art methods. The number and size of pieces which can be metallized simultaneously is limited only by the size of the metallizing chamber. In the production of articles with reflective and decorative surfaces the machine of the present invention involving a chemical reduction process, is at least as effective, and often more effective, than other metallizing methods, such as vacuum metallizing. The machine can be also used effectively to render nonconductive surfaces of various articles conductive since it will save considerable time and steps.
It is apparent that the example described above has been given solely by way of illustration and not by way of limitation and that it is subject to many variations and modifications within the scope of the present invention. For example, when treating steel lamp bases a third tank and pump for a sensitizer are added to the apparatus. The sensitizer is sprayed first and then the silver and reducer cycles are carried out in the above described manner. Plastic parts may be coated with both silver and copper by using four tanks and pumps, one for silver, the second for its reducer, the third for copper and the fourth for its reducer. In that case consecutive cycles for silver and copper are used; the centrifuge may be provided with a solenoid valve accepting the silver residue and rejecting the copper residue. All such and other variations and modifications are to be included within the scope of the present invention.
What is claimed is:
1. A metal coating apparatus, comprising a container, a swingable cover for opening and closing said container, a rotary shaft mounted within said container, a plurality of work-carrying arm members constituting a grid structure and adjustably mounted upon said shaft, at least two separate tanks for metal coating solution and reducing solution respectively, a separate pump connected with each tank, a separate conduit connected with each pump and extending into and within said container substantially parallel to said shaft, and spray nozzles carried by each of said conduits and directed toward said grid structure.
2. A metal coating apparatus in accordance with claim 1, comprising a centrifuge connected with an opening formed in the bottom of said container, said centrifuge having an outlet for the effluent, a motor for swinging said cover, a motor for rotating said shaft, a motor actuating said centrifuge, and means electrically interconnecting said motors and said pumps to constitute a single timed electrical circuit.
References Cited UNITED STATES PATENTS 1,392,781 10/1921 Marsh et a1. 134-109 X 2,785,999 3/1957 Ruthner 13410'9 X 2,889,837 6/1959 Braun et al 8326 X ROBERT W. MICHELL, Primary Examiner.
J. P. MCINTOSH, Assistant Examiner.
US. Cl. X.R.