RU2354757C2 - Method of electrolyte coating application onto internal surface of small cross-section item, and device for method implementation - Google Patents

Abstract

FIELD: electrics.

SUBSTANCE: method involves submersion of item with anode mounted in it into electrolyte, connection of negative power source pole to the item and positive pole to anode, coating application by electrolyte flushing through internal item cavity. Anode is made of wire inserted into perforated tube and is connected to power source at two sides regardless of item length. Wire inside perforated tube is the conductive cord of anode.

EFFECT: uniform coating of internal surface for items with small cross-section, including long items and items with complex profile, due to simplified method and device.

6 cl, 2 dwg, 1 ex

Description

The invention relates to electroplating, to methods and devices for coating on the inner surfaces of articles, in particular for coating the inner surfaces of articles of small cross section, including curved and long ones.

. Технический результат: повышение стабильности качества покрытия изделий за счет упрощения оборудования, повышения его мобильности и надежности. Недостаток - невозможность его применения для нанесения качественного покрытия на внутреннюю поверхность изделий малого сечения, в том числе длинномерных и сложнопрофилированных (СД).A known method of electrolytic coating on the inner surface of a hollow product (patent RU No. 2282683). The invention relates to the field of electroplating and can be used when applying dimensional high-quality coatings on the inner surface of a hollow product in combination with machining. The method includes placing the anode together with the clamps in the cavity of the product, plastic deformation of the clamps during the deposition of metal from the solution, the movement of the clamps along the length and simultaneously across the deposition surface, supplying a concentrated solution to the product cavity and withdrawing the depleted solution, the solution being fed into the product cavity from the end and pumped along the deposition surface through a system of ribs on the surface of the anode, which are arranged in a spiral at an angle β to the end of the product, and the angle β is selected from the condition:

. Effect: improving the stability of the quality of coating products by simplifying equipment, increasing its mobility and reliability. The disadvantage is the impossibility of its use for applying a high-quality coating to the inner surface of small-section products, including long-length and complex profiles (DM).

As a prototype, the silvering of the waveguide sections (BC), described in OST.5R.9136-83, was taken. Coating (in this case silver) is carried out in several stages. The product is prepared, an anode consisting of several silver wires fixed by flexible supports is mounted in it, and the length of the anode together with the supports is determined by the length of the aircraft. Pre-silvering is performed. A nozzle is mounted for supplying the electrolyte to the aircraft and silvering of the internal cavity of the aircraft is carried out by electrolyte duct containing silver. The negative pole of the current source is connected to the aircraft, and the positive pole to the anode. Moreover, for aircraft with a length of more than 400 mm, a two-sided current supply to the anode is used, for aircraft with a length of less than 400 mm, a one-sided current supply. In the process of silvering with the electrolyte duct, the anode links are periodically displaced relative to the section with the pump and current switched off, unloading the section with the nozzle from the bath. At the end of the silvering, the nozzle and the anode are dismantled, in which violation of the coating is possible.

This process is time-consuming, complex and does not provide uniform coating quality for complex internal surfaces of small sections.

An anode was selected as a prototype of the claimed device (see OST.5P.9136-83.), Which contains several wires made of metal with specified physicochemical properties, fixed in the desired position, ensuring uniform distribution of current using flexible supports. Supports are polyethylene links connected by kapron fishing line or thread. The number of supports, the length of the wire and the length of the fishing line are determined by the length of the waveguide section.

The disadvantage of this method and device is that with sufficient complexity, their implementation does not ensure uniformity of coverage of complex profiled long-length (DM) products of small cross section.

The aim of the invention is to provide uniform coverage of the inner surface of products of small cross section, including long and complex profiles, by simplifying the method and device for electrolytic coating on the inner surface of the products.

The specified technical result is achieved due to the fact that in the method of electrolytic coating on the inner surface of the product of small cross section, which includes immersing the product with the anode mounted in it into the electrolyte, connecting the negative pole of the current source to the product, and connecting the positive pole to the anode, pumping the electrolyte through the internal the surface of the product, use an anode of wire placed inside a perforated tube of insulating material, and the anode is connected to the current source independently from both sides about the length of the product. In this case, the perforated tube can be made of polyethylene, fluoroplastic or polyvinyl chloride. The wire and perforated tube are flexible.

This set of features allows to reduce the time of the coating process, to simplify it by reducing the number of operations and improve quality.

In the device, the indicated technical result is achieved due to the fact that the anode for electrolytic coating on the inner surface of a small section product, the conductive core of which is a wire, is located inside a perforated tube of insulating material, such as polyethylene, fluoroplastic or polyvinyl chloride, with the possibility of connecting to a current source on both sides, regardless of the length of the product. It is recommended that the perforated tube and wire be flexible. The implementation of this design can significantly simplify the prototype device. The design of the anode makes it possible to apply a coating to the inner surface of the product of small cross section without disturbing it during assembly and disassembly. When applying coating to complex-shaped (curved) and lengthy products, a flexible anode is used (the flexibility in this case is determined by the properties of the wire) of this design, which makes it possible to repeat the shape of the product without disturbing the coating.

Comparison of the claimed technical solutions with prototypes allows us to establish compliance with their criterion of "novelty." In the study of other well-known technical solutions in this technical field, signs that distinguish the claimed invention from prototypes were not identified and therefore they provide the claimed technical solution with the criterion of "inventive step".

The invention is illustrated by drawings, where figure 1 shows a General view of a device for coating the inner surface of hollow articles of small cross section; figure 2 shows the workpiece (waveguide section) with an anode placed in its cavity.

Equipment for electrolytic coating of the inner surfaces of parts contains a bath 1 filled with an electrolyte (containing silver in our example), a pump 2 immersed in a bath 1 and connected with a flexible hose 3 with a device for supplying electrolyte to the coated product 4, also located in the bath 1 with the sides of one of the flanges 8. The electrolyte supply device is equipped with a collector with nozzles 5, in our device there are three of them. The number of nozzles 5 is determined by the number of processed products 4. Through the device, the electrolyte is pumped into the internal cavity of the product 4 from the side of the flange 8, and through the free end from the side of the second flange it is poured into the bath 1. Anode, the conductive core of which is wire 6, made of a material selected depending from the destination, placed inside a flexible perforated tube 7, made, for example, of polyethylene or fluoroplastic, mounted in the internal cavity of the product 4, connected to a positive current source, and product 4 - with a negative. The installation is equipped with a device made in the form of an electronic unit that controls the frequency of the supply current to the pump motor 2 and thereby regulates the change in the electrolyte flow rate.

Installation works as follows.

A product 4 with an anode is connected on one side to one of the nozzles 5. A manifold fitting with nozzles 5 is connected to the hose 3 of the pump 2, nozzles 5 with products 4 are immersed in the bath 1. Products 4 are connected to the negative pole of the current source, and the anode to the positive. When coating with electrolyte pumping, the pump 2 is turned on and with the help of a device made in the form of an electronic unit, the required frequency of the current supplied to the pump 2 motor is set. The power supply is turned on and the required current is set. After the estimated time, everything is turned off in the reverse order.

An example of a specific implementation.

Using the equipment described above, silvering of straight and curved waveguide sections with a length of 205 and 480 mm and a cross section of 11 × 5.5 and 13 × 6.5 mm was made of aluminum alloy. Pre sections are nickel chemically. Intermediate operations (washing, degreasing, etc.) are carried out and the parameters (current density, exposure time) are set in accordance with the standards, and experimental selection of parameters depending on the required coating thickness is possible. The uniformity of the coating over the entire length during silvering is achieved when using silver wire as an anode, placed in a perforated tube, for example, of fluoroplastic. The anode of this design is mounted in the channel of the product (waveguide section). The product is connected to the negative pole. The anode located in the internal cavity of the product is connected to the positive pole of the current source. In our example, the anode is connected from two sides, which guarantees the quality of the coating products of any length, including curved. Pre-silvering and basic silvering are carried out without electrolyte duct. The product with the anode is mounted on a device for supplying electrolyte and immersed in a bath 1 with a silver electrolyte. For silvering with a duct, a pump 2 immersed in a bath 1 is connected using a flexible hose 3 with a device for supplying a silver electrolyte to a coated product 4 (waveguide section). Through the device, the electrolyte is pumped into the internal cavity of the product on one side, it is poured into the bath 1 through the free end. The installation is equipped with a device made in the form of an electronic unit that controls the frequency of the current supplied to the pump motor 2, and thereby regulates the change in the electrolyte flow rate.

When implementing the above technology, the following results were obtained.

Of the six samples coated with an internal anode according to OST5R. 9136-83 (with one- or two-sided current supply to the anode depending on the length of the product and the electrolyte flow), the channel is not covered on two samples, on four samples on the inner surface the coating either does not meet the requirements of GOST 9.301 or is damaged when the internal anode is dismantled.

Of the eight samples coated using an internal anode of silver wire placed in a perforated tube, with an electrolyte duct and two-way supply of current to the anode, the coating on the inner surface meets the requirements of GOST 9.301 on all samples.

One sample (11 × 5.5 × 480 mm) was coated without an internal anode. The internal channel of the waveguide was not opened.

Sample No. 16 (13 × 6.5 × 205 mm) was coated using an internal anode of silver wire placed in a perforated tube, with two-sided supply of current to the anode, without a silver electrolyte duct. The coating in appearance meets the requirements of GOST 9.301. The coating is uneven with an underestimation of the thickness of the coating in the middle to 50%.

Sample No. 17 (13 × 6.5 × 205 mm) was coated using an internal anode made of a stainless steel cable, placed in a perforated tube, with two-sided current supply to the anode, without a silver electrolyte duct. The coating in appearance meets the requirements of GOST 9.301. The coating is uneven with an underestimation of the thickness of the coating in the middle to 50%.

The main difficulty in covering a long waveguide of complex shape (with bends) is the installation and dismantling of the internal anode. Dismantling the internal anode according to OST. 5P. 9136-83 leads to violation (stripping) of the coating along the entire length of the waveguide. Dismantling the inner anode with silver wire does not give such a defect.

When using the method and device reflected in this application for the invention, there are minor uncovered contact points of the device with the waveguide and a partial lack of coverage at the interfaces, which is allowed by the technical documentation.

Inspection of the external surface of the waveguides was carried out in accordance with GOST 9.301 and OST 92-1436 after cutting.

The adhesion control was carried out by the heating method in accordance with GOST 9.302.

The thickness control of the coating was carried out by the jet-periodic method and metallographic method in accordance with GOST 9.302.

Using the invention allows:

get a silver coating with the required functional properties in one galvanic bath;

to obtain a uniform coating on the inner surface of products of small cross section along the entire length of the part (up to 500 mm), including complex profiles;

significantly simplify the technology of coating.

Claims (6)

1. The method of electrolytic coating on the inner surface of a product of small cross section, including immersing the product with the anode mounted in it into the electrolyte, connecting the negative pole of the current source to the product, and connecting the positive pole to the anode, coating with pumping the electrolyte through the internal cavity of the product, characterized in that they use an anode made of wire placed inside a perforated tube, while the anode is connected to a current source from two sides, regardless of the length of the product. 2. The method according to claim 1, characterized in that the wire and perforated tube are made flexible. 3. The method according to claim 1 or 2, characterized in that the perforated tube is made of polyethylene, fluoroplastic or polyvinyl chloride. 4. An anode for electrolytic coating on the inner surface of a small section product, the conductive core of which is a wire, characterized in that the wire is located inside a perforated tube with the ability to connect to a current source from two sides, regardless of the length of the product. 5. The anode according to claim 4, characterized in that the wire and perforated tube are made flexible. 6. The anode according to claim 4 or 5, characterized in that the perforated tube is made of polyethylene, fluoroplastic or polyvinyl chloride.

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