RU2282683C1 - Method for electrolytically applying coating onto inner surface of hollow article - Google Patents

Abstract

FIELD: electroplating processes, possibly deposition of high quality predetermined size coating onto inner surface of hollow article.

SUBSTANCE: method comprises steps of arranging anode together with clamps in cavity of article; plastically deforming (by means of clamps) metal being deposited out of solution; moving clamps along length of surface to be deposited and simultaneously across said surface; supplying into cavity of article concentrated solution and draining from it depleted solution; supplying solution into cavity of article at side of article end and pumping solution along surface to be deposited with use of system of ribs on anode surface. Said ribs are arranged along helix by angle β relative to end of article. Said angle is selected according to condition β is less than β<|±π/4|.

EFFECT: highly stable quality of coating, enlarged assortment of products due to simplified equipment of high mobility, reliable circulation of solution in deposition zone.

3 cl, 2 dwg

Description

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.

There is a method of dimensional coating (chrome plating) of parts with the deposition of fine-grained precipitates of chromium of a given thickness, according to which the surface in the process of electrolytic coating is plastically deformed by clamps in the form of abrasive bars (AS USSR No. 231989; Cl. 48 a, 5/06; 1967 .).

The disadvantage is the formation of abrasive and chrome dust, which must be removed from the area covered by the electrolyte duct (hereinafter referred to as the “solution”), followed by the mandatory cleaning of this solution.

A known method of obtaining a wear-resistant coating, in which the outer surface of the part rotated in the solution is electrolytically coated with a subsequent rolling-in with a reinforcing element (clamp) (AS USSR No. 795845; B 23 P 1/18, C 25 D 5/48 ; 1979).

The disadvantage is the impossibility of its use for applying a high-quality coating on the inner surface.

A known method of electrolytic coating on the inner surface of a hollow product, in the process of deposition of metal from a solution, it is plastically deformed by clamps moving along and across the deposition surface, and at the same time a concentrated and depleted solution is fed into the cavity of the product, in which the product is reciprocated, the clamps rotate coaxially with the anode, the concentrated solution is fed into the cavity of the product through a system of blades that rotate simultaneously with the anode and aspolagayut angle α to the end product, and the angle α is selected from the condition α <| ± π / 2 | (Patent RU No. 2156836; MKI 7 C 25 D 5/22. Declared December 29, 1998, No. 98124026/02).

The disadvantage of the invention is that the method cannot be applied when coating the inner surface of massive hollow products (cylinders), in addition, the method does not provide the required pressure of the column of solution for pumping through the product, firstly, in the case of using an anode of rectangular cross section during its rotation, “rarefaction zones are formed "Leading to rupture of the continuous flow of the solution, secondly.

The closest technical solution is the method of electrolytic coating on the inner surface of a hollow product, in which the anode and clamps are placed in the cavity of the product, during the deposition of metal from the solution, it is plastically deformed by clamps that move along the length and simultaneously across the deposition surface, and into the cavity of the product concentrated and depleted solution is fed (USA Patent No. 3616289; IPC C 23 B 5/56; B 23 P 1/02. National Cl. 204/26; 204/143 G; 204/217; 204/224; 1969 g.).

The disadvantage of the invention is the complexity of the device for coating the inner surface of a hollow product, which reduces the stability of the quality of the coating, and the limited range of products.

Effect: increasing the stability of the coating quality while expanding the product range by simplifying equipment, increasing its mobility and reliability of the circulation of the solution in the deposition zone.

The specified technical result is achieved due to the fact that in the known method of electrolytic coating on the inner surface of a hollow product, in which the anode is placed in the cavity of the product together with the clamps, during the deposition of metal from the solution, it is plastically deformed by clamps that move along the length and simultaneously across deposition surface, and a concentrated and depleted solution is fed into the cavity of the product, the solution is fed into the cavity of the product from the end and pumped along the surface of the deposition Nia by a system of ribs on the anode surface, which have a helix angle of β to the end product, and the angle β is selected from the condition β <| ± π / 4 |. In addition, the hollow product is moved back and forth, and the anode with clamps is rotated; either the hollow article is rotated, and the anode with clamps is moved back and forth.

The implementation of the anode with a system of ribs on its surface at an angle β to the end of the product, where the angle β is selected from the condition β <| ± π / 4 |, allows its rotation and reciprocation of the hollow product to provide intensive pumping of the solution, maintaining its optimal concentration in the cathode space, as applied to the coating of thin-walled cylinders or other axisymmetric hollow articles of small mass. In the case of coating a hollow product such as thick-walled cylinders or other axisymmetric hollow massive products, the proposed scheme is realized by rotating the hollow product and reciprocating the anode with a system of ribs on its surface located in a spiral at an angle β to the end of the product, and the angle β is selected from conditions β <| ± π / 4 |.

The use of a system of ribs on the anode surface, arranged in a spiral at an angle to the end of the product, allows continuous pumping of a column of solution enclosed in the cavity of the product, maintaining a constant optimal concentration of the solution in the cathode space, which improves the stability of the coating quality and increases the deposition rate of the metal, while the design of a specialized device (equipment) is simplified, its mobility is increased, and the product range is expanded both in diameter, wall thickness and in length INE. Due to the intensive displacement of the depleted solution from the product cavity by the concentrated one, active removal of free hydrogen from the deposited surface occurs, the film of which is constantly destroyed under the action of clamps, and its removal by the flow of the solution outside the product. A multiple decrease in the content of free hydrogen in the chromium layer occurs, for example, which increases the resistance of the coating to embrittlement and eliminates peeling of the coating during operation of the product. In addition, the implementation on the surface of the anode of a system of ribs located in a spiral at an angle β to the end of the product, can significantly increase the surface area of the anode, which increases the deposition rate and the stability of the quality of the coating.

Figure 1 presents a schematic diagram of a device for coating the inner surface of thin-walled hollow products; figure 2 presents a schematic diagram of a device for coating the inner surface of large, massive cylinders or other axisymmetric hollow products.

Specialized equipment for the implementation of the proposed method includes a bath 1 with a solution 2 in which the product 3 is placed, in the cavity of which an anode 4 is located with a system of ribs 5 arranged in a spiral at an angle β to the end face of the product 3, selected from the condition β <| ± π / 4 |, and clamps 6. The anode 4 together with the clamps 6 performing plastic deformation rotate around its axis (transverse movement of the clamps) with an angular velocity ω, and the product 3 with a speed ν move back and forth (longitudinal movement of the clamps) of the surface to be deposited - as applied to a thin-walled cylinder. The angle β is less than π / 4, which ensures the capture of a portion of the solution and its sequential supply by a system of ribs 5 along the axis of the product 3, and the direction of the angle β - “+” or “-” is chosen opposite to the direction of rotation of the anode 4.

In the case of coating a large massive cylinder, the product 3 is placed on a pallet 7 rotating at a speed ω, and the product 3 with a pallet 7 form a cavity closed on the pallet side into which a concentrated solution is supplied. Placed in the cavity of the product 3 anode 4 with a system of ribs 5 on its surface, made in a spiral at an angle β to the end face of the product 3, selected from the condition β <| ± π / 4 |, together with the clamps 6 give the reciprocating movement of the anode 4 with speed ν. The combined action of the rotation of the product 3 on the pallet 7 and the reciprocating movement of the anode 4 with a system of ribs 5 arranged in a spiral at an angle β at a speed ν promotes active pumping of the solution in the cavity of the product 3 and the flow of lean solution through the edge of the cylinder into the bath 1.

Experimentally, the proposed method was tested when applying a chrome coating to the inner surface of the gas separator (pump module). In the case of a gas separator measuring ⌀ 90 × 1.2 mm and a length of 230 mm, a coating thickness of 150 μm was applied. The goal is to obtain a high-quality wear-resistant layer. Used a vertical diagram of the device (see figure 1). An anode with a diameter of 70 mm was used with a system of ribs with a diameter of 80 mm located in a spiral at an angle β to the end of the product, where the angle β = 23 °, the distance between the ribs was 20 mm; the anode was made with 5 clamps. The anode rotation speed is ω = 85 rpm, the reciprocating movement of the gas separator body is ν = 56 rpm (i.e. 56 double strokes / min). A steady pumping of the solution through the gas separator body was obtained, the chromium deposition rate increased by 50%, the coating quality was high: fine-grained structure, the surface of the coating was shiny, there were no pores, roughness was (0.04 ... 0.03) microns, microhardness was 1050 kg / mm ² , defects (chips, peeling, scoring) - are absent.

The worn cylinder liner of the diesel locomotive was restored. Sizes, mm: diameter - 260, wall thickness - 12, height - 480; weight ~ 50 kg. Material - modified cast iron. Surface preparation - grinding. The required coating thickness is 1.5 mm. The recovery method is iron. A vertical diagram of the device was used (Fig. 2): the speed of rotation of the pallet was ω = 112 rpm, the movement of the anode was ν = 187 bits. moves. Received a high-quality coating of the required thickness, without defects, roughness - 0.1 μm, hardness - HRc = 59. The deposition rate doubled.

Claims (3)

1. The method of electrolytic coating on the inner surface of a hollow product, in which the anode is placed in the cavity of the product together with the clamps, during the deposition of metal from the solution, it is plastically deformed with clamps that move along the length and simultaneously across the deposition surface, and concentrated product is fed into the cavity and a depleted solution is removed, characterized in that the solution is fed into the cavity of the article from the end and pumped along the deposition surface by means of 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 β <| ± π / 4 |. 2. The method according to claim 1, characterized in that the hollow article is moved back and forth, and the anode with clamps is rotated. 3. The method according to claim 1, characterized in that the hollow article is rotated, and the anode with clamps is moved back and forth.

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