US20040238363A1

US20040238363A1 - Device and method for coating bicycle components

Info

Publication number: US20040238363A1
Application number: US10/449,527
Authority: US
Inventors: Gerrit Jager
Original assignee: DT Swiss Inc
Current assignee: DT Swiss Inc
Priority date: 2003-05-30
Filing date: 2003-05-30
Publication date: 2004-12-02

Abstract

The present invention relates to a device and to a method for coating bicycle components. According to the invention, the device has at least one power supply unit, at least one liquid tank and at least one conveying means for the bicycle components to be coated. On the power supply unit, there are at least two electrodes that are connected to the bicycle components and arranged in the liquid tank. In the liquid tank, there is also a carrier solution having a prescribed proportion of a coating substance, where the electric circuit to the power supply unit is closed when at least one component is at least partially brought into contact with the liquid. The coating substance is deposited at least as a function of a prescribed electric current.

Description

The present invention relates to a device and to a method for coating bicycle components.

Methods for coating components and parts where, for example, the surface is provided with a coat of paint, are known from the state of the art. For instance, the paint is sprayed as a liquid onto the surface or else—as is known from the powder-coating method—applied in the form of dry granules onto the surface and then bonded to the surface in a subsequent baking procedure.

A drawback of these methods is that, in the case of a liquid application, for example, the thickness of the coat of paint can vary, thereby impairing the adhesion between the paint and the surface to be coated. Moreover, when coating powders are used, voids that might have been created, for instance, when the individual components were welded or joined together, are then merely covered up by the paint, thus remaining present as voids.

Before this backdrop, it is the objective of the present invention to provide a device and a method which at least partially overcome the disadvantages known from the state of the art and which provide a cost-effective surface coating for bicycle components offering sufficient stability of the surface structure, even under severe stress.

This objective is achieved by means of a device for coating bicycle components according to claim 1 and by a method for coating bicycle components according to claim 8. Preferred refinements of the solution according to the invention are the subject matter of the subordinate claims.

The device according to the invention for coating bicycle components has at least one power supply unit, at least one liquid tank and at least one conveying means for the bicycle components to be coated.

In particular, a direct-current unit having at least two electrodes is employed as the power supply unit.

Thus, according to the present invention, for instance, at least the conveying means and particularly the bicycle to be coated, constitutes a first electrode. The second electrode is, for example, at least the liquid tank and, in particular, it can also be an electrode arranged in the liquid tank.

Both electrodes are connected to the power supply unit, where the electric circuit of the device is closed when, under the prescribed conditions, the bicycle component or components to be coated is or are at least partially brought into contact with the liquid. The liquid is held in a liquid tank and it consists essentially of a carrier solution with a prescribed proportion of a coating substance. The invention is also characterized in that the bicycle component or components are coated by depositing the coating substance that is dispersed in the liquid, where the deposition takes place at least as a function of a prescribed electric current.

According to a preferred embodiment, the device is used to coat bicycle components that are made with at least one material from a group of materials comprising metals such as, for instance, aluminum, iron, nickel, zinc, titanium, bronze, metal alloys thereof and the like. However, it also falls within the scope of the present invention to coat bicycle components which, in addition to the above-mentioned materials, also contain materials from a group of materials comprising natural and synthetic plastics, natural substances, composites, fiber-reinforced plastics and the like.

According to the present invention, however, particularly bicycle components or parts are coated which have at least one area that is electrically conductive or that does not exceed a prescribed specific electric resistance.

According to another particularly preferred embodiment, the coating substance is at least partially dispersed in a carrier solution, where this carrier solution is selected from among a group of liquids comprising water with or without additives, particularly demineralized water, solvents, auxiliaries such as, for example, surfactants and the like.

According to another particularly preferred embodiment, the coating substance itself is one that is selected from a group of materials comprising paints, particularly acrylic-based or epoxy-based paints and the like, and/or which also exhibit at least a prescribed particle size distribution and prescribed charging characteristics.

The carrier solution, containing at least one partially dispersed coating substance, also exhibits a dynamic viscosity which, according to a preferred embodiment, lies between 0.2 and 10 mPa·s, more preferably between 0.3 and 2 mPa·s and particularly preferred between 0.4 and 1 mPa·s.

However, the viscosity can be selected so as to be higher or lower, depending on the part to be coated, where the selection of the viscosity determines the coating thickness as well as the penetration depth of the coating substance, particularly into voids that might be present in the parts to be coated. Thus, for instance, a carrier solution with a very low viscosity in which the coating substance is at least partially dispersed can—depending on the particle size distribution of the coating substance—penetrate very easily into pores or depressions that might be present in the material to be coated, thereby largely preventing the occurrence of uncoated voids and flaws.

Moreover, the selection of the coating parameters can also determine the properties, particularly those pertaining to the impermeability to gases and/or liquids. Thus, the components or areas coated with the above-mentioned substances can be rendered virtually gas-tight and liquid-tight.

In particular, this translates into advantages to the effect that, for example, during the coating of bicycle wheel rims that are to be used with tubeless tires, it is possible to dispense with impregnation, that is to say, the application of a gas-tight coating in an additional work step, and the wheel rim attains the material properties desired for its use with such tires.

According to another particularly preferred embodiment, the device to coat bicycle components has a plurality of liquid tanks in which the components can particularly be pre-treated and/or coated and/or rinsed.

According to the present invention, pre-treatment refers particularly to the cleaning of the surface of the components, particularly the metal surfaces which, according to another particularly preferred embodiment, can also be phosphatized so as to prepare them for the subsequent coating.

In particular, cleaning and/or phosphatizing are necessary in order to better meet the quality requirements made of the coating.

The term phosphatizing refers particularly to iron and zinc phosphatizing processes known from the state of the art which are employed according to the invention in the form of an immersion system and/or a spraying system.

Furthermore, the cleaning can be carried out using hot and highly alkaline cleansers, so as to remove any grease, oil and/or other residues that might still be present on the components to be coated. Thus, for instance, several liquid tanks can be used where, depending on the material of which the components are made, many or just a few liquid tanks holding different solutions can be utilized. Particularly when it comes to the treatment of components that are made of aluminum or aluminum alloys, the cleaning operation has to be performed very carefully in order to avoid damage to the surface of the material to the greatest extent possible. An alternative cleaning method exists in the form of so-called power washing in which the components are cleaned at high pressure, once again with an alkaline cleanser, although at a lower concentration than in the case of immersion cleaning operations.

According to another particularly preferred embodiment, the components are treated with a metallic pickling agent prior to being coated, a process in which the metallic pickling agent—particularly but not exclusively—contains at least one constituent on the basis of phosphate acid.

This is particularly effective in cleaning a component on which there is a film of rust where this chemical process achieves de-rusting, de-scaling and deoxidizing of alloy and low-alloy grades of steel.

In addition to removing oxidized surface impurities such as rust, scale and tarnished layers, it is also possible to remove cuttings or metal dust of the type formed, for example, during cold rolling or other cold-forming methods or during blasting with a metallic abrasive or with acid-soluble pigments that often cause problems during de-greasing.

According to the present invention, the coating is done by means of paint deposition, which takes place as a result of a chemical reaction (coagulation).

The reaction transpires through the flow of electric current from one electrode to the workpiece via the conductive coating substance.

According to the present invention, the term coating substance refers to paints, particularly to electrodeposition paints, which contain at least one pigment, one binder and one carrier solution preferably consisting of fully demineralized water, and which are mixed with a prescribed proportion of an organic solvent.

The binder according to an particularly preferred embodiment consists at least partially of an epoxy resin and/or acrylic resin. These resins are ionized by means of a so-called neutralization reaction with organic acids and converted into a water-soluble state. Within the scope of the reaction, water is broken down (oxygen, hydrogen) by means of electrophoresis brought about by the electric current, a process in which ions are split off and gases are released (FIGS. 1 and 2).

In a cationic coating method, the pigment and the binder are deposited onto the workpiece, which constitutes the cathode, while iron, for example, oxidizes and dissolves on the anode that is situated inside the liquid tank. Prior to penetrating into the material, the layer of coating substance that is deposited onto the material has a rather irregular, porous structure which, however, liquefies into a uniform, contiguous paint film in another process step following the baking procedure. However, according to a particularly preferred embodiment, prior to the baking procedure, at least one rinsing system is used to clean the coated component of any paint residues, where filtrates of the carrier solution that have been cleaned or purified to differing degrees can be used, particularly for the rinsing.

The objective of the present invention is also achieved by means of a method for coating bicycle components that are made at least partially of an electrically conductive material, where the method comprises the following steps:

The bicycle components are pre-treated before the actual coating operation. Such pre-treatment stages are, for instance, the cleaning, rinsing and/or activation of the surface by means of a treatment stage involving phosphate.

Following this pre-treatment, the component is coated according to the invention in at least one dipping bath, where at least one coating substance that is at least partially dispersed in a carrier solution is then deposited onto the component.

As explained above, the coating substance consists of at least one binder and at least one pigment, demineralized water being employed as the carrier solution. After the coating operation, the component is cleaned with the carrier solution and subsequently heated in an oven until the paint layer that has been applied runs and forms a homogenous, contiguous film. According to a particularly preferred embodiment, the retention time in the oven is between 30 and 150 minutes, preferably between 60 and 120 minutes.

According to an particularly preferred embodiment, the particle size distribution of the coating substance and the type of carrier material are selected in such a way that the coating substance is deposited onto the surface as well as into a prescribed area of the porous structure of the component. In particular, through a low viscosity and an appropriately selected current intensity, the deposition of the coating substance is not limited only to the surface of the component but rather, the coating substance is also deposited, for example, into pores, cracks and irregularities of the type formed, for instance, when the components are welded together.

According to another particularly preferred method, the bicycle components are coated in an essentially continuous process of the kind known, for example, from assembly-line production. The term “essentially continuous process” as used here refers to an ongoing process which, however, can also be divided into individual sequences. Moreover, it also refers to the fact that the conveyance of the components is reduced or interrupted as a function of the retention times in the individual treatment stages. According to the present invention, this can also encompass various process stages where, in particular, a pre-treatment and a post-rinsing of the components can be integrated into the continuous coating process. It is also within the framework of the present invention to configure this process in such a way that, following the rinsing of the components, the baking is carried out in an oven that can be continuously charged, where the paints are then melted.

Additional features and advantages of the present invention will be presented below with reference to the figure description. However, it should be pointed out that this should not be construed as a limitation of the invention, but rather that these are simply examples of the execution of the method according to the invention and of the use of a device according to the invention.

Thus, the following is shown: [0038]
FIG. 1—a schematic representation of an anionic coating method; [0039]
FIG. 2—a schematic representation of a cationic coating method; and [0040]
FIG. 3—a simplified process diagram of the coating of bicycle components.[0041]
FIG. 1 shows a schematic drawing of a preferred embodiment of the coating of bicycle components according to the invention illustrating the physical principle that materials having opposite electric charges attract each other. In the coating method according to the invention, a direct current [0042] 10 is applied to a workpiece 14 and to at least one additional electrode where, in order to coat the workpiece, the latter is dipped into a liquid in which coating substance particles of opposite ionization are dispersed. Owing to the different charges, the coating substance particles are carried to the workpiece, where they are deposited. A uniform film is formed on the surface of the workpiece and the coating operation is continued until a prescribed thickness has been reached.
According to an particularly preferred embodiment, this layer has an electrically insulating effect so that, beyond a prescribed thickness, the deposition onto the surface of the component is reduced or stopped, thus completing the coating operation. [0043]
In FIG. 1, [0044] reference numeral 10 designates the source of direct current, with the anode being identified by the “−” sign and with the cathode being identified by the “+” sign. The component 14 is attached to the cathode 12. Electrophoresis causes oxygen to be generated at the cathode 12 while hydrogen is generated at the anode and escapes from the liquid as gas. Due to the potential difference, the coating substance migrates in the direction indicated by the arrow 13.
FIG. 2 shows a schematic drawing of the cationic coating method, where the device differs from that of FIG. 1 particularly by virtue of the fact that the workpiece is arranged on the anode. The coating substance is deposited onto [0045] component 14. The arrow 17 indicates the direction in which the coating particles migrate.
FIG. 3 is a schematic drawing of a simplified process diagram in which [0046] components 20 are coated by means of the method according to the invention. The direct-current source 10 is connected to the electrodes 28 and 29, where the liquid tank 21 holds the carrier solution in which the coating substance is at least partially dispersed. The components 20 are dipped into this liquid tank 21. The retention time is employed to regulate, among other things, the coating thickness, where additional parameters such as, for example, the concentration of the coating substance in the carrier solution as well as the voltage and the current intensity all have an influence on the coating thickness to be created, which can thus be regulated. The components are removed from the coating bath above the dripping area 22 located adjacent to the liquid tank 21 and they are subsequently rinsed twice above tanks 24 and 26.
Treated carrier solution that has been removed from the tank [0047] 22 by a pump 30 and that has been pre-treated in a first filter 31 and then recovered in the ultrafiltration unit 32 is employed as the rinsing agent here. The overflow is recycled via a heat exchanger into the liquid tank 21. This ensures that the carrier solution is as clean as possible during the second rinsing procedure and that impurities adhering to the components will be largely rinsed off. After the second rinsing procedure, the coated components are placed into an oven where they are baked at object temperatures between 125° C. and 200° C. [257° F. and 392° F.] for approximately 30 minutes. In the case of a continuous process, the paint is also baked in a continuous process stage which is followed by cooling and tempering or, if necessary, by an appropriate reworking of the components.

Claims

1. A device to coat bicycle components having at least one power supply unit, at least one liquid tank and at least one conveying means for the bicycle components,

wherein the power supply unit is particularly a direct-current unit having at least two electrodes, and

wherein at least the conveying means, particularly the bicycle component as at least a first electrode, and at least the liquid tank, particularly at least a second electrode arranged therein, are connected to the power supply unit, and

wherein the liquid tank holds a carrier solution having a prescribed proportion of a coating substance,

wherein the electric circuit of the device is closed when, under the prescribed conditions, the bicycle components are at least partially brought into contact with the liquid,

characterized in that

the bicycle component is coated by means of deposition of the coating substance dispersed in the liquid at least as a function of the prescribed electric current.

2. The device for coating bicycle components according to claim 1, characterized in that

the device serves to coat bicycle components that are made with at least one material from a group of materials comprising metals such as, for instance, aluminum, iron, nickel, zinc, titanium, bronze, metal alloys thereof and the like.

3. The device for coating bicycle components according to claim 1, characterized in that

the coating substance is at least partially dispersed in a carrier solution, wherein this carrier solution is selected from among a group of liquids comprising water with or without additives, particularly demineralized water, solvents, auxiliaries such as, for example, surfactants and the like.

4. The device for coating bicycle components according to claim 3, characterized in that

the coating substance is selected from a group of materials comprising acrylic-based or epoxy-based paints and the like which exhibit a prescribed particle size distribution and prescribed charging characteristics.

5. The device for coating bicycle components according to claim 1, characterized in that

the carrier solution containing the coating substance has a dynamic viscosity between 0.2 and 10 mPa·s, more preferably between 0.3 and 2 mPa·s and particularly preferred between 0.4 and 1 mPa·s.

6. The device for coating bicycle components according to claim 1, characterized in that

the device has a plurality of liquid tanks in which the components are pre-treated, coated and rinsed.

7. The device for coating bicycle components according to claim 1, characterized in that

prior to being coated, the component is cleaned in at least one additional liquid bath, and particularly impurities such as oil, grease and corrosion residues or the like are removed, at least from the surface.

8. A method for coating bicycle components that are made at least partially of at least one electrically conductive material, comprising the following steps:

pre-treatment of the bicycle components;

electrochemical coating of the components in a dipping bath in which at least one coating substance is deposited onto the component, said coating substance being at least partially dispersed in a carrier solution;

post-rinsing of the components with the carrier solution;

baking of the components in an oven.

9. The method for coating bicycle components according to claim 8, characterized in that

the pre-treatment of the bicycle components comprises at least one process step that is selected from a group that comprises cleaning, pickling, activating, post-rinsing, etc. the components, particularly their surfaces.

10. The method for coating bicycle components according to claim 8, characterized in that

the coating substance is deposited onto the surface and at least into a prescribed area of the pore structure of the component.

11. The method for coating bicycle components according to claim 8, characterized in that,

after the baking of the coated component, a surface structure is created that is at least partially gas-tight and liquid-tight.

12. The method for coating bicycle components according to claim 8, characterized in that,

the bicycle components are coated in an essentially continuous process.

13. The method for coating bicycle components according to claim 8, characterized in that at least one heat exchanger is arranged in the flow path of the carrier solution.

14. Use of the method for coating bicycle components according to one of claims 8 through 13, wherein the bicycle components belong to a group of bicycle components comprising bicycle forks, bicycle wheel rims, bicycle springs, saddle supports, handlebar fittings, bicycle wheel hubs, bicycle spokes, bicycle frames, bicycle cranks, fenders and the like.

15. The use of the device for coating bicycle components according to at least one of claims 1 through 7, wherein the bicycle components belong to a group of bicycle components comprising bicycle forks, bicycle wheel rims, bicycle springs, saddle supports, handlebar fittings, bicycle wheel hubs, bicycle spokes, bicycle frames, bicycle cranks, fenders and the like.

16. Components, particularly bicycle components, which are coated with a device according to at least one of claims 1 through 7, wherein the bicycle components belong to a group of bicycle components comprising bicycle forks, bicycle wheel rims, bicycle springs, saddle supports, handlebar fittings, bicycle wheel hubs, bicycle spokes, bicycle frames, bicycle cranks, fenders and the like.

17. Components, particularly bicycle components, which are coated by means of a method according to one of claims 8 through 13, wherein the bicycle components belong to a group of bicycle components comprising bicycle forks, bicycle wheel rims, bicycle springs, saddle supports, handlebar fittings, bicycle wheel hubs, bicycle spokes, bicycle frames, bicycle cranks, fenders and the like.