Process and apparatus for coating components of a shopping cart and a product

Abstract

A process and apparatus for coating components against corrosion and for durability. The process including cleaning the metal parts with cleaners and acid dips, rinsing, then dip coating the component with a nickel layer followed by a chemical sealant. The nickel-plated component may then be powder coated and cured. Alternatively, the nickel-plated component may be further layered with a dip-coated layer of chromium to produce durable and corrosion resistant properties.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a process for coating metal articles and more particularly, a process for applying abrasion and corrosion resistance substances to components of a shopping cart, an apparatus for applying such coatings and to shopping cart components having such components.

2. Background Description

Various types of articles, such as for example, shopping carts, require protective coatings to withstand corrosion and abrasion while presenting an attractive appearance. Several techniques are known for coating metallic articles that may involve electrostatic applications of compounds onto the articles. Additionally, certain types of dipping processes are known for specific types of layering. However, individually these techniques typically do not provide high abrasion resistance and impart high strength characteristics.

In addition, protective final finishes (e.g., paint or resin type finishes) are currently applied using a wide range of known techniques such as, for example, electrostatic spray. These finishes may involve a wide range of materials including resins, polymers, organic paint, and the like. However, these processes, by themselves, do not provide a high level of abrasion and corrosion resistance.

A layering process is needed that provides exceptionally high corrosion resistance and exceptionally strong durability against abrasion that utilizes a low cost layering technique and is adaptable to a wide range of article shape, strength, and size. The process should also be suitable for use on a wide range of base metal substrates and provide for application of various final finishes.

SUMMARY OF THE INVENTION

An aspect of the present invention includes a process for plating a component for a shopping cart. The process includes cleaning the component by immersion in a cleaning solution then rinsing the component at least one time to remove the cleaning solution. The process further includes dipping the component into a nickel bath to produce a nickel-plating having a thickness of approximately 0.35-2 mil-inch. The nickel-plated component is rinsed at least one time and electrostatically sprayed with a powder coating, wherein the nickel-plated component produces a substantially corrosion resistant component. Chromium plating may be applied directly to the nickel, in an embodiment.

Another aspect of the present invention includes a process for plating a component including cleaning the component by immersion in a cleaning solution, rinsing the component at least one time and dipping the component into a nickel bath to produce a nickel-plated component having a nickel plating substantially 0.35-2 mil-inch thick. The component may be dipped in a chromium bath to produce a nickel-chromium plated component having a chromium plating substantially 0.0002-0.1 mil-inch thick.

Another aspect of the present invention provides for a means for dipping the component into a nickel bath to produce a nickel-plated component and a means for rinsing the nickel-plated component at least one time. A means is also provided for dipping the nickel-plated component in a chromium bath to produce a nickel-chromium plated component having a chromium plating substantially 0.0002-0.1 mil-inch. Also, a means for rinsing the nickel-chromium plated component at least one time and a means for sealing the nickel-chromium plated component with a chemical sealer and a means for rinsing the sealed nickel-chromium plated component at least one time is provided. A means for drying the nickel-chromium plated component by heating and a means for applying a powder coating to the nickel-chromium plated component to provide a finish and a means for curing the nickel-chromium plated and powder coated component is also provided.

In another aspect of the invention, a shopping cart having one or more components is provided. The one or more components of the shopping cart have a metal like structure with a nickel chromium plating and an electrostatic sprayed powder coating applied over the nickel chromium plating. The nickel plating has a thickness in range of approximately 0.35-2 mil-inch, the chromium plating has a thickness in a range of approximately 0.0002-0.1 mil-inch, and the powder coating has a thickness in a range of approximately 2-6 mil-inch.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings, in which:

FIGS. 1A-1C are block diagrams showing components and stages of the process according to the present invention; and

FIG. 2 is a block diagram showing components and stages of drying and finishing process according to the present invention.

DETAILED DESCRIPTION OF A DETAILED EMBODIMENT OF THE INVENTION

The process of providing coatings to articles according to the present invention involves a multi-step process, in an embodiment, for layering protective metallic layers onto the article, such as components for a shopping cart or other mobile carrier, followed by an application of a finishing layer of powder coat. The layering of an article according to this invention provides particularly durable properties against corrosion and abrasion and is accomplished in a low cost and practical manner. The present invention will be discussed with reference to components of a shopping cart as an illustrative example implementing the process of the present invention. It should be understood, however, by those of ordinary skill that the present invention is not limited to components of shopping carts and may equally be used with other suitable articles capable of undergoing the processes of the present invention.

FIGS. 1A, 1B, and 1C are block diagrams showing components and stages of the plating process and plating machine according to the present invention, as generally shown as reference numeral 5. FIGS. 1A-1C may also represent high level flow diagrams representative of the process steps according to the present invention. The illustrative embodiment portrays a shopping cart frame as an article 10 for coating; however, any suitable article of manufacture may be coated using the process of the present invention. These articles may be made from any suitable metal such as, for example, steel, alloys, or the like (generally metal-like). The temperatures, layering thickness of any plating and time period discussed throughout the process of the present invention each have, in an embodiment, an associated tolerance of +/−20%. It should also be understood that FIGS. 1A-1C, each are representative of a component to be dipped in an appropriate solution and then removed therefrom.

To begin, the processes of the invention include stages of cleaning and rinsing the article in preparation of receiving coatings of nickel, and optionally, chromium. In operation, the article 10 is loaded onto a plating machine 5 via conveyor 15, which successively moves the article through various stages of the process. These stages include the dipping stages as well as, in an embodiment, spraying stages. However, as discussed, the dipping and spraying stages may be interchangeable, in instances.

At stage 20, the article is immersed in a caustic soak cleaner and comprises sodium hydroxide, having a concentration range 8 to 14 percent by volume, and surfactants and solvents at a combined concentration of 2 to 8 percent by volume, operating at a temperature range of 150 to 190 degrees Fahrenheit. This cleaner solution removes any foreign substances and generally cleans the article.

This caustic soak typically lasts approximately 6-8 minutes. It is noted that, as stated above, all temperature, concentrations, voltage, current, time and thickness ranges contemplated by the invention may vary approximately +/−20% from the stated ranges.

At stage 25, the article is at a rinse stage for removing the caustic soak and typically lasts approximately 0.5-2 minutes for the rinse. The rinse typically is typically flowing fresh water, but may be other rinse agents, and minimizes carry-over of cleaner solution to the next process tank.

The rinse is shown as a dip, however, other methods may be used in all the rinse steps such as, for example, a spray rinse. The article moves along to an electro cleaner stage 30 for immersion and further preparation for layering of the nickel or chromium plating. The electro cleaner may include such cleaners as, for example, a caustic cleaning solution comprising sodium hydroxide, having a concentration range of 6 to 15 percent by volume, and surfactants and chromium reducing agents at a combined concentration of 2 to 8 percent by volume, operating at a temperature range of 150 to 190 degrees Fahrenheit. The part is subjected to an anodic electrolytic cleaning process at an impressed voltage of approximately 5 to 12 volts resulting in a current density of approximately 40 to 60 amperes per square foot of part surface area.

This immersion typically lasts approximately 3-4 minutes and is followed by another rinse stage 35 with a suitable rinse agent, such as water, to remove the electro cleaner. This rinse stage lasts approximately 1-2 minutes. A second rinse at stage 40 may also be provided, in an embodiment, after stage 35 and may last approximately 1-2 minutes to insure complete removal of the electro cleaner.

Still referring to FIGS. 1A-1C, the article proceeds to stage 45, which is an electro acid immersion stage. This immersion stage lasts approximately 3-4 minutes. The electro acid may include, for example, sulfuric acid having a concentration range of 9 to 14 percent by volume, fluoride agents having an active fluoride of 0 to 6 percent by volume, and wetting agents, operating at a temperature range of 150 to 190 degrees Fahrenheit. The part is subjected to an cathodic electrolytic cleaning process at an impressed voltage of 4 to 12 volts resulting in a current density of approximately 5 to 30 amperes per square foot of part surface area.

This stage further advances the cleaning of the article's surface typically removing any oxide scales present from the processing of the metal and is followed by another rinse stage 50 that lasts approximately 0.5-2 minutes. At stage 50, another electro cleaner immersion stage 55 may be provided, in an embodiment, for approximately 1-4 minutes. The electro cleaner may include such cleaners as, for example, a caustic cleaning solution comprising sodium hydroxide, having a concentration range of 6 to 15 percent by volume, and surfactants and chromium reducing agents at a combined concentration of 2 to 8 percent by volume, operating at a temperature range of 150 to 190 degrees Fahrenheit. The part is subjected to an anodic electrolytic cleaning process at an impressed voltage of approximately 5 to 12 volts resulting in a current density of approximately 40 to 60 amperes per square foot of part surface area.

Two rinse stages 60 and 65, similar to stage 25, are then provided to remove any electro cleaner. The stages 60 and 65 each last approximately 0.5-2 minutes.

The article moves along the plating machine 5 to an acid dip stage 70 wherein the article is dipped in an acid bath for approximately 1-3 minutes. The acid may include an acidic cleaning solution comprising hydrochloric acid, having a concentration of 15 to 40 percent by volume, fluoride agents having an active fluoride of 0 to 6 percent by volume, and wetting agents, operating at a temperature range of 70 to 150 degrees Fahrenheit. The part is subjected to an anodic electrolytic cleaning process at an impressed voltage of 5 to 12 volts resulting in a current density of 40 to 60 amperes per square foot of part surface area. A rinse stage 75, similar too stage 25, follows for approximately 0.5-2 minutes.

The conveyor 15 then transports the article 10 to a nickel plating stage 80. At this stage, the article is dipped in an electrolytic nickel bath for approximately 19-24 minutes to provide a thickness in the range of 0.35-2 mil-inch. This provides a nickel-plated coating to the article. The nickel plate is then rinsed by four or more successive rinse stages 85, 90, 95, and 100, each of which is approximately 0.5-2 minutes.

The article 10 may optionally enter another sequence for coating with chromium to produce a nickel-chromium layered article, or alternatively, continue directly with the rinse stage 110. In an embodiment, the additional rinse steps may be eliminated if there is no chromium layering. Continuing with chromium plating, the nickel coated article 10 proceeds to a chromium dipping stage 105. The nickel-coated article 10 is immersed in a chromium bath for approximately 2-4 minutes that produces a chromium plating in the range of 0.0002 to 0.1 mil-inch. The chromium plating includes chromium metal plating derived from tri-valent or hexavalent electrolytic process.

At stage 110, the nickel-plated, or alternatively, the nickel-chromium plated article 10 is rinsed for approximately 0.5-2 minutes, followed by a second rinse stage 115 for about another 0.5-2 minutes, both similar to stage 25. A chemical sealer is applied at stage 120, which lasts for about 0.5-2 minutes. The chemical sealer may include an acidic solution and other adhesion promoters. The sealer passivates unplated surfaces and enhances subsequent metal-to-plastic adhesion. The chemical sealer stage 120 is followed by two rinse stages 125 and 130, similar to stage 25. If necessary, the article 10 may be removed from the plating machine 5 at this point and transferred to a drying and finishing sequence, or if the sequence is continuous, the article 10 proceeds directly to the drying and finishing sequence.

FIG. 2 is a block diagram showing components and stages of the drying and finishing process according to the present invention. FIG. 2 may also represent high level flow diagrams representative of the process steps according to the present invention. In this sequence, the plated article 10 proceeds to the drying and finishing sequence, generally shown as reference numeral 145, beginning with a drying stage 150. In the drying stage, the nickel coating or nickel-chromium coatings are dried in an oven. The oven temperature is nominally 325 degrees Fahrenheit. The heating time is approximately 5-10 minutes (+/−20%) with a cooling time of approximately 5-10 minutes (+/−20%). Of course, the cooling time may be greater. Again, it is noted that all temperatures, drying and cooling times, etc. may vary according to the present invention by approximately +/−20%, or in another embodiment, more or less ranges are also contemplated for use by the invention.

The article 10 is then conveyed to the powder coating stage 160. At this stage, a powder coating finish is applied to the article 10, typically by an electrostatic spraying process, although other means may be employed by the present invention. The powder coating finish may be one of many types including plastic, resins, polymers, or the like, and may be of various colors. The thickness is typically 3-5 mil-inch with time in the spraying booth of approximately 1-2 minutes. The powder coated article 10 then enters a curing stage 170, at which time, the article is heated in an oven to a temperature of approximately 425 degrees Fahrenheit for approximately 15-20 minutes. The article 10 is then cooled for approximately 5-10 minutes producing a finished article 10 of substantial corrosion resistance and high durability.

While the invention has been described in terms of embodiments, those skilled in the art will recognize that the invention can be practiced with modifications and in the spirit and scope of the appended claims.

Claims

1. A process for plating a component for a shopping cart or carrying conveyance, the process comprising the steps of:

cleaning the component by a cleaning solution;

rinsing the component at least one time to remove the cleaning solution;

dipping the component into a nickel bath to produce a nickel-plating having a thickness of approximately 0.35-2 mil-inch thick;

rinsing the nickel-plated component at least one time; and

electrostatically spraying a powder coating over the nickel-plating,

wherein the nickel-plating and powder coat produces a substantially corrosion and abrasion resistant component.

2. The process of claim 1, further comprising the steps of:

before the electrostatic spraying step, dipping the nickel-plated component in a chromium bath to produce a chromium plating having a thickness of substantially 0.0002-0.1 mil-inch thick; and

rinsing the nickel-chromium plated component at least one time after the dipping the nickel-plated component in the chromium bath step.

3. The process of claim 2, wherein each of the rinsing steps is approximately 0.5-2 minutes.

4. The process of claim 2, further comprising the step of:

sealing the nickel-chromium plated component with a chemical sealer before the electrostatic spraying step; and

rinsing the chemical sealer from the nickel-chromium plated component.

5. The process of claim 2, further comprising the steps of:

drying the nickel-chromium plated component;

applying the powder coating after the drying step to the nickel-chromium plated component; and

after the drying step, curing the nickel-chromium plated component.

6. The process of claim 5, wherein the drying step includes heating the nickel-chromium plated component approximately 5-10 minutes, +/−20%, in a temperature of about 325 degrees F., +/−20%, and then cooling the nickel-chromium plated component.

7. The process of claim 2, wherein the applying a powder coating step takes approximately 1-2 minutes.

8. The process of claim 5, wherein in the curing step includes heating the nickel-chromium component to about 425 degrees F. for about 15-20 minutes.

9. The process of claim 8, further includes cooling the nickel-chromium component.

10. The process of claim 2, wherein the applying the powder coating includes electrostatically spraying the powder coating to produce a thickness of about 3-5 mil-inch.

11. The process of claim 1, wherein cleaning the component step includes immersing the component in a caustic cleaner.

12. The process of claim 1, wherein the cleaning the component step includes immersing the component in a first electro cleaner.

13. The process of claim 12, wherein the cleaning step includes immersing the component in a second electro cleaner.

14. The process of claim 13, further comprising the step of immersing the component in an acid dip after the second electro cleaner step.

15. The process of claim 1, further comprising the step of:

before the electrostatically sealing step, sealing the nickel plated component with a chemical sealer; and

rinsing the sealed nickel plated component at least one time.

16. The process of claim 1, further comprising the steps of:

before the electrostatically spraying step, drying the nickel plated component by heating to a temperature of approximately 325 degrees F. +/−20%, and then cooling the nickel plated component; and

after the electrostatically spraying step, curing the nickel plated sprayed component by heating to approximately 425 degrees F. +/−20% and then cooling.

17. The process of claim 1, wherein the powder is applied to the nickel plated component to a thickness of about 3-5 mil-inch.

18. A process for plating a component for a shopping cart or carrying conveyance, the process comprising the steps of:

cleaning the component by immersion in a cleaning solution;

rinsing the component at least one time to remove the cleaning solution;

dipping the component into a nickel bath to produce a nickel-plated component having a nickel plating substantially 0.35-2 mil-inch thick; and

dipping the nickel-plated component in a chromium bath to produce a nickel-chromium plated component having a chromium plating substantially 0.0002-0.1 mil-inch thick.

19. The process of claim 18, further comprising the steps of:

sealing the nickel-chromium plating with a chemical sealer; and

rinsing the sealed nickel-chromium plating at least one time.

20. The process of claim 19, further comprising the steps of:

drying the nickel-chromium plated component;

applying a powder coating to the nickel-chromium plated component to provide a finish; and

curing the nickel-chromium plated and powder coated component.

21. The process of claim 20, wherein the drying step includes drying the nickel-chromium plated component approximately 5-10 minutes, +/−20%, in a temperature of about 325 degrees F., +/−20%, and cooling the nickel-chromium plated component.

22. The process of claim 20, wherein the applying a powder steps includes electrostatically spraying the powder coating to produce a powder coating thickness of about 3-5 mil-inch.

23. The process of claim 20, wherein in the curing step includes heating the nickel-chromium plated component to approximately 425 degrees F., +/−20%, for approximately 15-20 minutes, +/−20%, and then cooling the nickel-chromium plated component.

24. An apparatus for plating a component, comprising:

a means for cleaning the component by immersion in a cleaning solution;

a means for rinsing the component at least one time to remove the cleaning solution;

a means for dipping the component into a nickel bath to produce a nickel-plated component having a nickel plating substantially 0.35-2 mil-inch thick;

a means for rinsing the nickel-plated component at least one time,

a means for dipping the nickel-plated component in a chromium bath to produce a nickel-chromium plated component having a chromium plating substantially 0.0002-0.1 mil-inch thick;

a means for rinsing the nickel-chromium plated component at least one time,

a means for sealing the nickel-chromium plated component with a chemical sealer;

a means for rinsing the sealed nickel-chromium plated component at least one time;

a means for drying the nickel-chromium plated component by heating;

a means for applying a powder coating to the nickel-chromium plated component to provide a finish; and

a means for curing the nickel-chromium plated and powder sprayed component.

25. The apparatus of claim 24, wherein the means for drying the nickel-chromium plated component is an oven capable of heating to a temperature of about 325 degrees F., +/−20% for approximately 5-10 minutes, +/−20%.

26. A shopping cart having one or more components, the one or more components of the shopping cart having a metal like structure with a nickel chromium plating and an electrostatic sprayed powder coating applied over the nickel chromium plating, the nickel having a thickness in range of approximately 0.35-2 mil-inch thick, the chromium plating having a thickness in a range of approximately 0.0002-0.1 mil-inch thick, and the powder coating having a thickness in a range of approximately 3-5 mil-inch.