The present invention generally relates to equipment used in an electrodeposition process and, more particularly, to an electrode assembly that is used to electrify a solution or bath so that material can be deposited on a workpiece.
The term “electrodeposition” broadly refers to any process that uses electrical current in a solution or bath in order to adhere material to a workpiece surface. In a typical electrodeposition process, an electrically charged workpiece is submerged in an electrolytic solution along with an oppositely charged electrode; this creates electrical current that flows through the solution between the workpiece and the electrode. The solution undergoes an electrochemical process which results in components of the solution being adhered to a workpiece surface. As a final step, the workpiece may be taken out of the solution, rinsed, and then cured. It should be appreciated that an electrodeposition process could include both cathodic and anodic processes such as electrocoating (E-coating), electroplating, as well as any other suitable process for adhering primer, paint, films, metallic coatings, etc. to a workpiece surface.
According to one embodiment, there is provided an electrode assembly for use in an electrodeposition process. The electrode assembly may include an electrode that exchanges electrical current with a solution, and a passageway that extends with the electrode and includes one or more openings. During the electrodeposition process, gas that is trapped between the solution and a workpiece can escape through the opening and travel within the passageway.
According to another embodiment, there is provided an electrodeposition process that comprises the following steps: (a) bringing an electrode assembly into contact with a solution, wherein the electrode assembly includes an electrode and a passageway with at least one opening; (b) locating the opening in a space that is formed between a surface of a workpiece and the solution; (c) removing gas from the space through the opening and the passageway; and (d) providing an electrical current that causes components of the solution to be deposited on the workpiece.
Preferred exemplary embodiments of the invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein:
The electrode assembly described herein may be used in an electrodeposition process in order to improve the distribution and adherence of material to a workpiece surface. One factor that can prohibit material from being optimally deposited on a workpiece involves gas that becomes trapped between the workpiece and the solution. The trapped gas prevents portions of the workpiece surface from coming into contact with the solution; this, in turn, prevents those areas of the workpiece surface from being painted, plated, coated, etc. The electrode assembly described below includes a passageway that removes the trapped gas in order to increase the amount of workpiece surface area that comes into contact with solution. Although the following description is provided in the context of an exemplary automotive application using an electrocoat or E-coat process, it should be appreciated that the electrode assembly could be used in other electrodeposition processes known in the art.
With reference to
Turning now to
Electrode 22 is an elongated current carrying member that is coupled to an energy source so that it can exchange electrical current with solution 14 during an electrodeposition process. Electrode 22 can either be charged as an anode (shown in
Passageway 24 extends with electrode 22 and includes at least one opening 38 for gas that becomes trapped between workpiece 10 and solution 14. In the exemplary embodiment of
Opening 38 communicates with passageway 24 so that gas trapped between solution 14 and workpiece 10 can escape through the opening and travel within passageway. Opening 38 can be located at one of a number of different locations, and can have one of a number of different configurations. In the embodiment shown in
According to another embodiment, the passageway is located outside of the electrode and extends along at least a portion of the electrode length. For example, the passageway could be bounded or defined by a separate tube or hose that runs alongside electrode 22. In such an embodiment, electrode 22 could be a solid piece of conductive material and the passageway could extend within a tube that is attached or secured to the side of the electrode by way of fasteners, clips, ties, etc. Solid and perforated tubes are just two possibilities.
Sleeve 26 surrounds at least a portion of electrode 22 and insulates the electrode from workpiece 10, but still allows electrical current exchange between the electrode and the solution. Sleeve 26 can be made of a porous insulative material that is permeable to gas and liquid such as, but not limited to, a sponge, a meshing material, a plastic netting, or a foam. Still referring to
Pump 28 communicates with passageway 24 and draws gas and/or solution through opening 38 and the passageway. In some cases, it may be desirable for pump 28 to suck both trapped gas and solution 14 into passageway 24, as this can have a recycling effect on the solution and prevent stagnant pools of paint or other solution from forming. If pump 28 is designed to suck up both trapped gas and solution, then the pump should have some type of output that is in communication with solution 14 so that the liquid solution can be delivered back to the bath. This recirculation helps keep solution 30 agitated within solution bath 14 and may improve the electrodeposition process. In another embodiment, pump 28 could be omitted and passageway 24 could lead to an open area, container, or the like. For example, if the relative pressure difference between the trapped gas and the corresponding atmosphere where the passageway leads to is great enough, then it may not be necessary to actively evacuate the trapped air with a pump. In these cases, the trapped gas will have a greater pressure than that of the atmosphere and will be forced through passageway 24 without the assistance of a pump.
In operation, electrode assembly 20 removes trapped air from underneath workpiece 10 in order to improve the electrodeposition process and obtain a more uniform and desirable coating on the workpiece. The removal of the trapped air could be conducted at the same time that electrode 22 is provided with an electrical charge, or the two steps could be performed sequentially. As workpiece 10 is being submerged in solution 14, gas such as air may be caught or otherwise accumulate in a space 42 formed between the workpiece and the solution. Opening 38 is preferably positioned at the highest point within space 42 where gas might naturally accumulate; however, this is not necessary. In some cases, free end 40 of sleeve 26 may even contact the underside of workpiece 10 to help ensure that the opening is positioned at the highest possible point in order to remove substantially all of the gas. Upon activation, pump 28 sucks gas out of space 42 until the gas is substantially removed and solution 14 fills the void. Electrical charge can then be applied to electrode 22 so that the surrounding solution becomes electrified and an electrical current is formed. Components of solution 30 are then deposited on, and permanently adhered to, workpiece 10 which is provided with an opposite charge. In the absence of the trapped gas, solution 14 can now contact portions of workpiece 10 where before it could not, and a coating is more evenly applied.
In this context, the exemplary electrode assembly not only improves the electrodeposition process by removing trapped air, but it also provides charge to the electrolytic solution in a region surrounding the part to be coated.
It is to be understood that the foregoing description is not a definition of the invention, but is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. For example, the electrode assemblies described above could be used in addition to or in lieu of traditional stationary electrodes that charge an electrolytic solution or bath. It is also possible for the electrode assemblies to be mounted in a stationary way; that is, the above-described electrode assemblies could be mounted to the tank so that they remain fixed as the parts are conveyed. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.
As used in this specification and claims, the terms “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.
Number | Name | Date | Kind |
---|---|---|---|
6143155 | Adams et al. | Nov 2000 | A |
Number | Date | Country |
---|---|---|
56075597 | Jun 1981 | JP |
Number | Date | Country | |
---|---|---|---|
20100051452 A1 | Mar 2010 | US |