Arrangement for forming electroplating coating and method

Abstract

An arrangement (1) for forming an electroplating coating on an inner surface (7) of at least one product (2), wherein the at least one product (2) is a hollow metal product (2). The arrangement (1) comprises a fluid circulation system configured to lead fluid (F) in from a first end (8) of the at least one product (2) and to lead said fluid (F) out from a second end (9) of the at least one product (2). The arrangement further comprises at least one electrode (3) configured to be arranged inside the at least one product (2). The at least one electrode (3) has an active area (A) configured to perform plating. The at least one product (2) is configured to move relative to the at least one electrode (3), the at least one electrode (3) is configured to move relative to the at least one product (2), the at least one product (2) and the at least one electrode (3) are configured to move relative to each other to be configured to enable plating of the at least one product (2). The active area (A) comprises an active area length (L), which is less than a product length (P). Further a method is disclosed.

Description

[0001] ARRANGEMENT FOR FORMING ELECTROPLATING COATING AND METHOD

[0002] FIELD OF THE INVENTION

[0003] The present application relates generally to an arrangement for forming an electroplating coating on an inner surface of at least one product . More specifically, the present application relates to the electroplating coating on an inner surface of a hollow metal product .

[0004] BACKGROUND OF THE INVENTION

[0005] Electroplating coating may be used as a surface coating for metal products . The process may be highly toxic in nature and coating result may be uneven. As a result, coatings and coating processes may be further improved to obtain an optimal product .

[0006] SUMMARY

[0007] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subj ect matter, nor is it intended to be used to limit the scope of the claimed subj ect matter . The scope of protection sought for various embodiments of the present disclosure is set out by the independent claims .

[0008] The embodiments of the present disclosure provide an arrangement for forming an electroplating coating on an inner surface of at least one product and a method for forming an electroplating coating on an inner surface of at least one product . The arrangement and the method may provide a centralized electrode, which may improve plating quality. Also, high current densities may be used without quality losses . In addition, theprocess may be safe and efficient for the operator and for quality assurance .

[0009] According to a first aspect an arrangement for forming an electroplating coating on an inner surface of at least one product is disclosed, wherein the at least one product is a hollow metal product, wherein the arrangement comprises a fluid circulation system configured to lead fluid in from a first end of the at least one product and to lead said fluid out from a second end of the at least one product, and at least one electrode configured to be arranged inside the at least one product, wherein the at least one electrode has an active area configured to perform plating, the at least one product is configured to be moved relative to the at least one electrode, the at least one electrode is configured to be moved relative to the at least one product, or the at least one product and the at least one electrode are configured to be moved relative to each other to be configured to enable plating of the at least one product, and wherein the active area has an active area length, which is less than a product length. The electroplating arrangement is a closed arrangement, which may prevent an operator exposure to chemicals . The arrangement is also a quick, safe, and effective process for the operator and for quality assurance . In addition, an outer surface of the product may remain clean throughout the process . This may have the effect that all chemicals and electrical currents may be directed only to the inner surface of the product .

[0010] According to an embodiment of the first aspect, the electrode may be configured to act as an anode or as a cathode, and / or the at least one product may be configured to act as a cathode or as an anode . This has the effect that the same electrode may be used with different fluids . For example, when the fluid is sulphuric acid the product may act as an anode removing oxides from its surface and the electrode may act as acathode . However, when the fluid is a nickel solution or a trivalent chromium solution the electrode may act as an anode and the product may act as a cathode .

[0011] According to an example embodiment, the electrode is made of titanium. The electrode may have a titanium or graphite body. At least the active area may have been made of titanium, a titanium mesh, or graphite . The titanium mesh may be coated with multi-metal oxide . The electrode may be electrically conductive . The electrode may have plastic coating outside the active area .

[0012] According to an example embodiment, the electrode is a body that is structurally continuous along its entire length. The electrode may be an electrically conductive body that may be structurally continuous along its entire length. However, only a defined active area of the electrode may be exposed for plating. The entire electrode may be made of at least one of the following: an electrically conductive titanium, titanium mesh, and / or graphite body. The electrode may be active along its full length in the sense that it may conduct current throughout . Sections outside the active area may be completely coated with an insulation material, such as plastic coating. The insulation material may be one of the following: plastic, fluorocarbon coatings, tapes, and / or films . The insulation material may prevent unintended current flow and chemical interaction. The active area may perform the electroplating. The active area may be made one of the following: titanium, titanium mesh, and / or graphite . This may enhance durability and electrochemical performance . This design may ensure that all electrical and chemical activity may be concentrated on the active area while the rest of the electrode may remain insulated. This may improve plating uniformity, allow the use of high current densities, and ensure reliable operation within the corrosive chemical environment .According to an example embodiment, the fluid may be a sulphuric acid, a nickel solution, a trivalent chromium solution, or an aqueous solution.

[0013] According to an embodiment of the first aspect, the active area length may be 0, 1 - 0, 2 times the product length or 0, 125 times the product length. When the active area length is as long as the product length, low current density may need to be used because the high current density may produce more hydrogen accumulation than the lower current density. However, when the active area length is not as long as the product length, the higher current density may be used. As a result, with the short active area, hydrogen accumulation may be smaller even though the high current density may be used .

[0014] According to an embodiment of the first aspect, the at least one electrode may be configured to move back and forth inside the at least one product during plating or the at least one product may be configured to move back and forth outside the at least one electrode during plating . When the active area length is as long as the product length the electrode may not need to move to anodize the hole product . However, when the active area length is not as long as the product length, the electrode may need to be moved or the at least one product may need to be moved to anodize the hole inner surface of the product .

[0015] According to an embodiment of the first aspect, the arrangement may further comprise at least one guide configured to center the at least one electrode inside and in the middle of the at least one product . Centering the long and narrow electrode in the center of the product may be challenging. When the electrode is in the center of the hole, it may ensure consistent adhesion and coating quality of the product all around and along the entire length of the inner surface of the product .According to an embodiment of the first aspect, the at least one guide may be arranged at least partly around the at least one electrode . This may allow the electrode to be centered and also may allow the electrode to stay centered even when it is moved or when the at least one product is moved around and along the electrode .

[0016] According to an embodiment of the first aspect, the at least one guide may be configured to slide along the inner surface of the at least one product and / or the at least one product may be configured to slide around the at least one guide . The at least one guide may be arranged slidably along the inner surface of the product . The guide or an outer surface of the guide may be made of material that may enable sliding movement of the electrode in the center of the product or enable sliding movement of the product around and / or along the guide . The material of the guide is at least one of the following: plastic, polyethylene, polypropylene, and / or PVDF, for example .

[0017] According to an embodiment of the first aspect, arrangement may be self-supportive, wherein the at least one product may be configured to support itself and the at least one electrode, or the arrangement may comprise a support frame for mechanically supporting the at least one product and the at least one electrode . Self-supportive means that the product may stand on its own and no additional support frame is needed. When the product has smaller size it may need the support frame to support the product and / or the electrode . However, when the product is big, the additional support frame may not be needed because the product is so stabile that it may hold itself up and at the same time also may support the electrode . The product may have a product length from 400 mm to below 1000 mm, or 1000 mm to 10000 mm, for example . The small size is, for example from 400 mm tobelow 1000 mm. The big size product has the product length above 1000 mm, for example .

[0018] According to an embodiment of the first aspect, the arrangement may further comprise at least one controller, which may be configured to control movement of the at least one the following: the at least electrode, the at least one product, and / or at least one fluid into and out of the at least one product . The controller may control overall operation of the system. The controller may be configured to control at least one of the following: movement of the electrode, the at least one product, removal of a sulfuric acid oxide, rinsing with an aqueous solution, and / or supply and removal of fluids containing nickel and chromium. The controller may control speed of the electrode, the at least one product, and / or amount of fluid supply. The controller may be a sequential controller, which may control movement of the electrode, the at least one product, and flow of fluids or chemicals .

[0019] According to an embodiment of the first aspect, the controller may be configured to alternate movement of the at least one electrode, the at least one product, and / or flow of the at least one fluid inside the at least one product . The alternate movement of the at least one electrode, the at least one product, and flow of the fluid may enable better product quality because the amount of the fluid inside the product may always be optimal to the speed of the electrode or the product .

[0020] According to an embodiment of the first aspect, the fluid may be a solution of trivalent chromium cations, which fluid may be configured to be fed into the at least one product while the at least one electrode may be configured to be moved over an area to be plated or the at least one product may be configured to be moved around and along the electrode over an area to be plated during fluid feeding to form a chromium layer . The area to be plated may comprise the inner surface ofthe product or at least part of the inner surface of the product . Trivalent chromium electroplating may be effective due to its low cost, convenience of fabrication through the use of environmentally friendly and nontoxic chemicals, and ability to produce a bright Cr deposit especially when compared to hexavalent Cr . Trivalent chromium plating is also known as Cr3+and chrome ( III ) plating. This kind of plating may use trivalent chromium cations .

[0021] According to a second aspect, a method for forming an electroplating coating on an inner surface of at least one product using the arrangement according to any of the preceding embodiments of the first aspect is disclosed, wherein the at least one product is a hollow metal product and wherein the arrangement comprises a fluid circulation system, at least one electrode arranged inside the at least one product, wherein in the method the fluid circulation system leads fluid in from a first end of the at least one product and out from a second end of the at least one product; wherein the at least one electrode has an active area performing plating, wherein the active area has an active area length, which is less than a product length. The at least one product moves relative to the at least one electrode, the at least one electrode moves relative to the at least one product, or the at least one product and the at least one electrode move relative to each other enabling plating of the at least one product . The fluid may be directed from the bottom up . The at least one product may be located vertically in relation to the ground, or it may be tilted to an angle . When the at least one product is tilted, the angle may be so big that gases may escape . The angle is from 0° to 90° , or 45° , for example .

[0022] According to an embodiment of the second aspect, the arrangement may be is self-supportive, wherein the at least one product may be configured to supportitself and the at least one electrode, or the arrangement may comprise a support frame for mechanically supporting the at least one product and the at least one electrode .

[0023] According to an embodiment of the second aspect, the electrode may act as an anode or as a cathode, and / or the at least one product may act as a cathode or as an anode . This has the effect that the same electrode may be used with different fluids . For example, when the fluid is sulphuric acid the product may act as an anode removing oxides from its surface and the electrode may act as a cathode . However, in a nickel solution or a trivalent chromium solution the electrode may act as an anode and the product may act as a cathode .

[0024] According to an embodiment of the second aspect, the method may comprise a pretreatment process, which may comprise feeding a sulphuric acid into the at least one product while moving the at least one anode inside the at least one product or moving the at least one product outside the at least one electrode . The least one anode may be moved over the area to be plated during sulphuric acid feeding or the at least one product may be moved outside the at least one electrode to remove oxide layers . The at least one product to be coated may first be subj ected to appropriate pretreatment steps, such as, for instance, chemical and / or electrolytic degreasing using the sulphuric acid to remove oil and dirt from the surface to be coated. When the fluid is sulphuric acid the product may act as an anode removing oxides from its surface and the electrode may act as a cathode . In addition, the at least one product to be coated may be subj ected to etching, acid activation, or pickling to activate the surface before the actual coating and plating.

[0025] According to an embodiment of the second aspect, the method may comprise feeding a nickel solution into the at least one product while moving the at leastone electrode inside the at least one product or moving the at least one product outside the at least one electrode to form a nickel layer . The least one electrode may be moved over the area to be plated during nickel solution feeding or the at least one product may be moved outside the at least one electrode to form the nickel layer . When the fluid is the nickel solution the electrode may act as an anode and the product may act as a cathode . The nickel layer may be formed on the pretreated inner surface . The nickel layer may produce a corrosion resistant nickel underlayer and may provide an adhesion layer for chrome plating.

[0026] According to an embodiment of the second aspect, the method may comprise feeding a trivalent chromium solution into the at least one product while moving the at least one electrode inside the at least one product or while moving the at least one product outside the at least one electrode to form a chromium layer . The least one electrode may be moved over the area to be plated during trivalent chromium solution feeding or the at least one product may be moved outside the at least one electrode to form the chromium layer . The chromium layer may be formed on the nickel underlayer . The trivalent chromium solution may comprise trivalent chromium cations . When the fluid is the trivalent chromium solution the electrode may act as an anode and the product may act as a cathode . The trivalent chromium coating process may be safe and less toxic than hexavalent chromium containing process .

[0027] According to an embodiment of the second aspect, the method may comprise rinsing the inner surface of the at least one product with an aqueous solution before feeding a nickel solution into the at least one product; and / or rinsing the inner surface of the at least one product with an aqueous solution before and / or after feeding the trivalent chromium solution into the at least one product . Rinsing may remove chemicalresidues from the inner surface of the product . The rinsing may be done after pretreatment with the sulphuric acid and / or after the nickel layer is formed. The rinsing may also be done after chrome plating. The rinsing after chrome plating may be done inside or outside the arrangement . It may also be possible that the rinsing of the inner surface is not done .

[0028] According to an embodiment of the second aspect, forming of the electroplating coating may be carried out at a constant current density of 150 - 600 A / dm2. High constant current density is 150 - 600 A / dm2, for example . The short and / or narrow active area may allow for high current densities . For example, a coating thickness of 10 pm and a hardness of 1000 HV may be achieved in 8-10 minutes for a trivalent chromium plating. Thus the better thickness and hardness of a chrome coating may be achieved faster with the high current densities than using conventional coating methods with the lower current densities .

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings :

[0031] Fig. 1 schematically shows an arrangement as seen from front, according to an example embodiment;

[0032] Fig. 2 schematically shows an arrangement comprising an electrode located inside a product, according to an embodiment;

[0033] Fig. 3 schematically shows the arrangement of Fig . 2 seen from above, according to an example embodiment ;Fig. 4 illustrates an example method for forming an electroplating coating on an inner surface of at least one product, according to an example embodiment .

[0034] Like references are used to designate like parts in the accompanying drawings .

[0035] DETAILED DESCRIPTION

[0036] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings . The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The description sets forth the functions of the example and the sequence of steps or operations for constructing and operating the example . However, the same or equivalent functions and sequences may be accomplished by different examples .

[0037] According to an example embodiment, a conventional electroplating coating is used as a surface coating for metal products, such as pipes . A long and thin anode may be used for coating. However, it may be difficult to center the anode in the middle of the pipe . Also, used high current density may cause anode distortion, heating, and hydrogen accumulation. This may cause uneven coating inside the pipe and quality control difficulties . The process may also be highly toxic in nature .

[0038] According to an example embodiment, an arrangement comprises a product and an electrode, such as an anode or cathode, comprising a narrow active area . For example, when a gun barrel has a diameter of 5, 65 mm caliber, the active area is 5 cm. Here the caliber refers to an internal diameter of the product, such as a barrel or a pipe . The arrangement may also comprise guides,which may keep the electrode in the center of the product and prevent the electrode from becoming overlying. In addition, the arrangement may reduce hydrogen build-up . Closed process may also ensure operator safety without chemical exposure .

[0039] The arrangement may further comprise controller, such as sequential controller, which may control the electrode movement and fluid flow. It may also allow precise control of pretreatment and plating, and optimized repeatability and efficiency during the process . The centralized electrode may improve plating quality. In addition, with the narrow active area it may be possible to use high current densities without quality losses .

[0040] According to an example embodiment, an arrangement for coating the inside of a product, such a barrel or pipe, is disclosed. The arrangement may comprise a support frame for holding the product in place, an electrode configured to move back and forth along the length of the product in a narrow active area, and electrode guides for ensuring centering within product . The arrangement may also not comprise a support frame . The guides may be in contact with the inside surface of the product . The arrangement may further comprise a sequence controller for controlling the movement of the electrode and the supply of fluids or chemical solutions, such as sulfuric acid for deoxidation, water for rinsing, and nickel and chromium baths . The controller, such as a sequence controller, may be programmed to alternate the movement of the electrode, such as an anode or a cathode, the product, and the flow of chemicals within the product . This may allow for complete plating, deoxidation, and layer formation without operator exposure to chemicals .

[0041] According to an example embodiment, an arrangement for forming an electroplating coating on an inner surface of at least one product is disclosed, whereinthe at least one product is a hollow metal product . The arrangement may comprise a fluid circulation system configured to lead fluid in from a first end of the at least one product and to lead said fluid out from a second end of the at least one product . The arrangement may further comprise at least one electrode configured to be arranged movable or stationary inside the at least one product . The at least one electrode may have an active area configured to perform plating. Movement of the at least one product relative to the at least one electrode, movement of the at least one electrode relative to the at least one product, or movement of the at least one product and the at least one electrode relative to each other may be configured to enable plating of the at least one product . The active area may have an active area length, which may be less than a product length. The at least one product may be configured to be moved relative to the at least one electrode, the at least one electrode may be configured to be moved relative to the at least one product, or the at least one product and the at least one electrode may be configured to be moved relative to each other to be configured to enable plating of the at least one product .

[0042] According to an example embodiment, a method for coating an inside of product, for example 5. 65 mm caliber, is disclosed. The product may be mounted on a stationary support frame or arrangement may be self-supportive, wherein the at least one product may be configured to support itself and the at least one electrode . An electrode centered inside the product may move along its length or the product may move around, outside, and / or along the electrode and / or at least one guide . The electrode may have a narrow active area, for example approximately 5 cm. The narrow area may reduce required current and prevent excessive hydrogen accumulation inside the product . The electrode may have guidesthat may keep it centered inside the product and in light contact with an inner surface of the product .

[0043] According to an example embodiment, the electrode is repeatedly moved back and forth along the length of the product or the product is repeatedly moved back and forth along the length of the electrode, for example up-down-up cycle, during chromium plating, thereby achieving uniform coating thickness and reducing hydrogen accumulation.

[0044] According to an example embodiment, the outer surface of the product remains clean throughout the process because all chemicals and electrical currents are directed only to the inner surface of the product .

[0045] According to an example embodiment, the design of the support frame and the closed system prevents the operator from being directly exposed to the chemicals, thereby increasing the safety of the process .

[0046] An example of Fig. 1 shows an arrangement 1 as seen from front . An example of Fig. 2 shows part of an arrangement 1 or a self-supportive structure comprising an electrode 3 located inside a product 2, and an example of Fig. 3 shows the arrangement of Fig. 2 seen from above .

[0047] An example of Fig. 1 shows an arrangement 1 for forming an electroplating coating on an inner surface 7 of at least one product 2. The at least one product 1 may be a hollow metal product 2. The metal product to be coated may be any metal article made of, for instance, steel, copper, bronze, brass, etc. The arrangement may comprise a support frame 5 for mechanically supporting the at least one product 2 and the at least one electrode 3. The example of Fig. 1 shows that the arrangement has five products 2 in a first row attached between a lower support plate 12 and an upper support plate 13 of the support frame 5. However, the arrangement may have one or more rows of five or more products behind the first row. The amount of the products 2 attached between thesupport plates 12, 13 may be one or more . The at least one product 2 may be attached detachable between the lower and upper support plates 12, 13. The arrangement 1 may have the lower and upper support plate 12, 13. The arrangement 1 may further comprise a fluid circulation system configured to lead fluid F in from a first end 8 of the at least one product 2 and lead said fluid F out from a second end 9 of the at least one product 2. The fluid is a sulphuric acid, a nickel solution, a triva-lent chromium solution, or an aqueous solution, for example . Also, other fluids may be used. The example of Fig. 1 shows that the arrangement comprises an inlet 10 where the fluid F may enter to the first end 8 of the product 2 and an outlet 11 where the fluid F may leave the arrangement 1. The fluid F may be fed through one or more pipes that may be located inside and / or attached to the support frame 5 and / or the lower support plate 12. The fluid F may leave the second end of the at least one product 2 through one or more pipes that may be located inside and / or attached to the support frame 5 and / or the upper support plate 12. The arrangement 1 may further comprise at least one electrode 3 configured to be arranged inside the at least one product 2. The at least one electrode 3 may have an active area A configured to perform plating when moving inside the at least one product 2 or when the at least one product 2 may be configured to be moved around and along the electrode 3 over an area to be plated, as shown in Fig. 2. The active area A may have an active area length L, which is less than a product length P .

[0048] The arrangement 1 may further comprise a fastening plate 14 to which the at least one electrode 3 may be attached. The at least one electrode 3 may be located inside the at least one product 2. The fastening plate 14 may be arranged to move the at least one electrode 2 up and down in relation to the at least one product 2 . The at least one electrode 3 may movevertically inside the at least one product 2. The at least one electrode 3 may move inside the at least one product 2 between the inlet 8 and outlet 9 of the least one product 2 .

[0049] According to an example embodiment, the arrangement 1 may further comprise a fastening plate 14 to which the at least one product 2 may be attached. The at least one electrode 3 may be located inside the at least one product 2. The fastening plate 14 may be arranged to move the at least product 2 up and down in relation to the at least electrode 3. The at least one product 2 may move vertically outside the at least one electrode 3. According to an example embodiment, the arrangement 1 may comprise at least one controller 6, which is configured to control movement of the at least one electrode 3 inside the at least one product 2, movement of the at least one product 2, and / or movement of the at least one fluid F into and out of the at least one product 2 .

[0050] According to an example embodiment, the controller 6 is configured to alternate movement of the at least one electrode 3, the at least one product 2, and / or flow of at least one fluid F inside and / or outside the at least one product 2 .

[0051] The example of Fig. 2 shows part of an arrangement 1 comprising an electrode 3 located inside a product 2. A support frame 5 is not shown in Fig. 2. On the other hand, the product 2 may alternatively be self-supportive, wherein the product 2 may be configured to support itself and the electrode 3. The product 2 and electrode may be similar as used in Fig . 1 arrangement 1. The electrode 2 may comprise an active area A, and an active area length L, which may be less than a product length P .

[0052] According to an example embodiment, the active area length L is 0, 1 - 0, 2 times the product length P or 0, 125 times the product length P .According to an example embodiment, the electrode 3 may be configured to act as an anode or as a cathode, and / or the at least one product 2 is configured to act as a cathode or as an anode . For example, when the fluid F is sulphuric acid the at least one product 2 may act as an anode removing oxides from its surface and the movable 3 part may act as a cathode . However, when the fluid F is a nickel solution or a trivalent chromium solution the electrode 2 may act as an anode and the at least one product 2 may act as a cathode . According to an example embodiment, the at least one electrode 3 is configured to move back and forth inside the at least one product 2 during plating, or the at least one product is configured to move back and forth outside the at least one electrode during plating.

[0053] According to an example embodiment, the arrangement further comprises at least one guide 4 configured to center the at least one electrode 3 inside and in the middle of the at least one product 2. The guide 4 may comprise ring 15 and at least one protrusion 15. The example of Fig. 2 shows two guides 4 located above and below the active area A. Outside the active area the electrode may be insulated. Insulation material may be at least one of the following: plastic, fluorocarbons, tapes and / or films . The fluorocarbons may be PTFE, FEP, or vinyl coatings (PVC / Plastisol) .

[0054] The example of Fig. 3 shows the product 2, the electrode 3, and the guide 4 seen from above . The guide 4 comprises a ring 15 located around the electrode 3 and four protrusions 16 evenly attached an outer surface of the ring 15. The protrusions 16 may slide along an inner surface 7 of the product 2 and / or the at least one product 2 may be configured to slide around the at least one guide 4. This may center the electrode 3 and guide 4 inside and in the middle of the product 2. The guide 4 may also have other forms .According to an example embodiment, the at least one guide 4 is arranged at least partly around the at least one electrode 3. The guide may be fixedly attached to the electrode 3. Thus, the guide 3 may not move along the electrode 3.

[0055] According to an example embodiment, the at least one guide 4 is configured to slide along the inner surface 7 of the at least one product 2 and / or the at least one product 2 may be configured to slide around the at least one guide 4 .

[0056] According to an example embodiment, the fluid F is a solution of trivalent chromium cations, which fluid F is configured to be fed into the at least one product 2 while the at least one electrode 3 is configured to be moved over an area to be plated or the at least one product 2 is configured to be moved around and along the electrode 3 over an area to be plated during fluid feeding to form a chromium layer . The area to be plated may be the inner surface 7 of the product 2 or at least part of the inner surface 7.

[0057] According to an example embodiment, the arrangement 1 is self-supportive, wherein the at least one product 2 is configured to support itself and the at least one electrode 3, or the arrangement comprises a support frame for mechanically supporting the at least one product and the at least one electrode 3.

[0058] Figure 4 illustrates an example of a method for forming an electroplating coating on an inner surface 7 of at least one product 2 using the arrangement 1 according to any of the example embodiments above and / or the arrangements of Figs . 1 to 3 . The at least one product 2 may be a hollow metal product 2. The arrangement 1 may comprise a fluid circulation system, at least one electrode 3 arranged inside the at least one product 2 .

[0059] At operation 400, the method may comprise that the fluid circulation system may lead fluid F in from afirst end 8 of the at least one product 2 and out from a second end 9 of the at least one product 2.

[0060] At operation 410, the method may comprise that the at least one electrode 3 may have an active area A, which may perform plating, wherein the active area A may have an active area length L, which may be less than a product length P .

[0061] At operation 420, the method may comprise that the at least one product 2 may move relative to the at least one electrode 3, the at least one electrode 3 may move relative to the at least one product 2, or the at least one product 2 and the at least one electrode 3 may move relative to each other enabling plating of the at least one product .

[0062] According to an example embodiment, the arrangement 1 is self-supportive, wherein the at least one product is supporting itself and the at least one electrode 3, or the arrangement comprises a support frame 5 for mechanically supporting the at least one product 2 and the at least one electrode 3.

[0063] According to an example embodiment, the electrode 3 is acting as an anode or as a cathode, and / or the at least one product 2 is acting as a cathode or as an anode .

[0064] According to an example embodiment, the method comprises a pretreatment process, which comprises feeding a sulphuric acid into the at least one product 2 while moving the at least one electrode 3 inside the at least one product 2 or moving the at least one product 2 outside the at least one electrode 3 to remove oxide layers . When the fluid is sulphuric acid the product may act as an anode removing oxides from its surface and the electrode may act as a cathode . In an initial surface pretreatment step sulfuric acid may be fed into the product 2 while the electrode 3 may be moved along the inner surface 7 or the product 2 may be moved outside the electrode 3, thereby removing oxide layers .According to an example embodiment, the method comprises feeding a nickel solution into the at least one product 2 while moving the at least one electrode 3 inside the at least one product 2 or moving the at least one product 2 outside the at least one electrode 3 to form a nickel layer . When the fluid is the nickel solution the electrode may act as an anode and the product may act as a cathode . The nickel layer may be formed on the pretreated inner surface .

[0065] According to an example embodiment, the inner surface of the product is rinsed with water after the sulfuric acid treatment to remove chemical residues . After that the inner surface may be treated with a nickel solution to form a thin nickel layer . Thickness of the nickel layer is approximately 1 pm on the inner surface, for example . The movement of the electrode 2 or the product may allow the nickel coating to be applied to the entire inner surface 7 of the product 2 to ensure uniform adhesion.

[0066] According to an example embodiment, the method comprises feeding a trivalent chromium solution into the at least one product 2 while moving the at least one electrode 3 inside the at least one product 2 or moving the at least one product 2 outside the at least one electrode 3 to form a chromium layer . When the fluid is the trivalent chromium solution the electrode may act as an anode and the product may act as a cathode . The trivalent chromium solution may be formed on the nickel layer . The trivalent chromium solution may be formed on the pretreated inner surface without the nickel layer .

[0067] According to an example embodiment, the method comprises rinsing the inner surface 7 of the at least one product 2 with an aqueous solution before feeding the nickel solution into the at least one product 2, and / or rinsing the inner surface 7 of the at least one product 2 with the aqueous solution before and / or after feeding the trivalent chromium solution into the atleast one product 2. It may also be possible that the rinsing of the inner surface is not done . The rinsing may be done only after after the sulfuric acid treatment or only after forming the nickel layer. The pretreatment may not need to be done . It may also be that the only layer is the chromium layer .

[0068] According to an example embodiment, forming of the electroplating coating is carried out at a constant current density of 150 - 600 A / dm2.

[0069] According to an example embodiment, using high current densities, for example in the range of 150-600 A / dm2, in a trivalent chromium coating, thereby achieving a hardness of more than 1000 HV and a thickness of approximately 10 pm in 8-10 minutes .

[0070] Further features of the method directly result from functionalities of, for example, the arrangement 1. Different variations of the method may be also applied, as described in connection with the various embodiments .

[0071] Any range or device value given herein may be extended or altered without losing the effect sought . Also, any embodiment may be combined with another embodiment unless explicitly disallowed.

[0072] Although the subj ect matter has been described in language specific to structural features and / or acts, it is to be understood that the subj ect matter defined in the appended claims is not necessarily limited to the specific features or acts described above . Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims .

[0073] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments . The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of thestated benefits and advantages . It will further be understood that reference to ' an' item may refer to one or more of those items .

[0074] The steps or operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate . Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subj ect matter described herein. Aspects of any of the embodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought .

[0075] The term ' comprising' is used herein to mean including the method, blocks, or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements .

[0076] Although subj ects may be referred to as 'first' , 'second' , or 'third' subj ects, this does not necessarily indicate any order or importance of the subj ects . Instead, such attributes may be used solely for the purpose of making a difference between subj ects .

[0077] It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art . The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments . Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from scope of this specification.

Claims

CLAIMS1. An arrangement ( 1 ) for forming an electroplating coating on an inner surface (7 ) of at least one product (2 ) , wherein the at least one product (2 ) is a hollow metal product (2 ) , wherein the arrangement ( 1 ) comprisesa fluid circulation system configured to lead fluid (F) in from a first end ( 8 ) of the at least one product (2 ) and to lead said fluid (F) out from a second end ( 9) of the at least one product (2 ) ; andat least one electrode (3) configured to be arranged inside the at least one product (2 ) ; wherein the at least one electrode (3) has an active area (A) configured to perform plating, wherein the electrode (3) is insulated outside the active area (A) ;the at least one product (2 ) is configured to be moved relative to the at least one electrode (3) , the at least one electrode (3) is configured to be moved relative to the at least one product (2 ) , or the at least one product (2) and the at least one electrode (3) are configured to be moved relative to each other to be configured to enable plating of the at least one product ( 2 ) ; andthe active area (A) comprises an active area length (L) , which is less than a product length (P) .

2. The arrangement ( 1 ) according to claim 1, whereinthe electrode (3) is configured to act as an anode or as a cathode; and / orthe at least one product (2 ) is configured to act as a cathode or as an anode .

3. The arrangement ( 1 ) according to claim 1, wherein the active area length (L) is 0, 1 - 0, 2 times the product length (P) or 0, 125 times the product length (P) •4. The arrangement ( 1 ) according to any of the preceding claims, wherein,the at least one electrode (3) is configured to move back and forth inside the at least one product (2 ) during plating; orthe at least one product (2 ) is configured to move back and forth outside the at least one electrode (3) during plating.

5. The arrangement ( 1) according to any of the preceding claims, wherein the arrangement ( 1 ) further comprises at least one guide (4 ) configured to center the at least one electrode (3) inside and in the middle of the at least one product (2 ) .

6. The arrangement ( 1 ) according to claim 5, whereinthe at least one guide (4 ) is configured to slide along the inner surface (7 ) of the at least one product (2 ) ; and / orthe at least one product (2 ) is configured to slide around the at least one guide (4 ) .

7. The arrangement ( 1 ) according to any of the preceding claims, whereinarrangement ( 1 ) is self-supportive, wherein the at least one product (2 ) is configured to support itself and the at least one electrode (3) ; or the arrangement comprises a support frame (5) for mechanically supporting the at least one product (2) and the at least one electrode (3) .

8. The arrangement ( 1) according to any of the preceding claims, wherein the arrangement ( 1 ) further comprises at least one controller ( 6) , which is configured to control movement of the at least one of the following: the at least one electrode (3) ; the at leastone product (2 ) , and / or the at least one fluid (F) into and out of the at least one product (2 ) .

9. An arrangement ( 1 ) according to any of the preceding claims, wherein the fluid (F) is a solution of trivalent chromium cations, which fluid (F) is configured to be fed into the at least one product (2) while the at least one electrode (3) is configured to be moved over an area to be plated or the at least one product (2 ) is configured to be moved around and along the electrode (3) over an area to be plated during fluid feeding to form a chromium layer .

10. A method for forming an electroplating coating on an inner surface (7 ) of at least one product using the arrangement ( 1 ) according to any of the preceding claims, wherein the at least one product (2 ) is a hollow metal product (2 ) and wherein the arrangement ( 1 ) comprisesa fluid circulation system; andat least one electrode (3) arranged inside the at least one product (2 ) , wherein in the methodthe fluid circulation system leads fluid (F) in from a first end (8 ) of the at least one product (2 ) and out from a second end ( 9) of the at least one product (2 ) ;the at least one electrode (3) has an active area (A) performing plating, wherein the electrode (3) is insulated outside the active area (A) , wherein the active area (A) has an active area length (L) , which is less than a product length (P) ; andthe at least one product (2 ) moves relative to the at least one electrode ( 3) , the at least one electrode (3) moves relative to the at least one product (2 ) , or the at least one product (2 ) and the at least one electrode (3) move relative to each other enabling plating of the at least one product (2 ) .

11. The method according to claim 10, wherein the method comprises a pretreatment process, which comprises feeding a sulphuric acid into the at least one product (2) while moving the at least one electrode (3) inside the at least one product (2 ) or moving the at least one product (2 ) outside the at least one electrode (3) to remove oxide layers .

12. The method according to claim 11, wherein the method comprises feeding a nickel solution into the at least one product (2 ) while moving the at least one electrode (3) inside the at least one product (2 ) or moving the at least one product (2 ) outside the at least one electrode (3) to form a nickel layer .

13. The method according to claim 11 or 12, wherein the method comprises feeding a trivalent chromium solution into the at least one product (2 ) while moving the at least one electrode (3) inside the at least one product (2) or moving the at least one product (2 ) outside the at least one electrode (3) to form a chromium layer .

14. The method according to claim 12 or claim 13, wherein the method comprisesrinsing the inner surface (7 ) of the at least one product (2 ) with an aqueous solution before feeding the nickel solution into the at least one product (2 ) ; and / orrinsing the inner surface (7 ) of the at least one product (2 ) with the aqueous solution before and / or after feeding the trivalent chromium solution into the at least one product (2 ) .

15. The method according to any of claims 11 to 14, wherein forming of the electroplating coating iscarried out at a constant current density of 150 - 600 A / dm2.

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