RU2796389C1 - Tool and method for combined anode-mechanical finishing of heat-shielding multicomponent coatings - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention can be used for finishing selective processing of heat-shielding multicomponent coatings. A tool is proposed for combined anode-mechanical finishing of a heat-shielding multicomponent coating containing dielectric granules and a metal binder, when pressed against the processed heat-shielding multicomponent coating by an element in the form of a flexible sealed chamber, having a conductive base with abrasive grains deposited on it, and a method for carrying out said processing by the proposed tool. The conductive base of the tool is made by braiding from a transverse and longitudinal metal cathode wire, which has periodic bends perpendicularly made along its length, the amplitude of which is not more than the interelectrode gap created by abrasive grains protruding from the conductive base.

EFFECT: required roughness of the heat-shielding multicomponent coating is provided while maintaining heat-shielding dielectric granules and the properties of the multicomponent heat-shielding coating, as well as a stable process of local removal of the metal bond of the multicomponent heat-shielding coating.

3 cl, 6 dwg, 1 ex

Description

The tool and method belong to the field of mechanical engineering and can be used for finishing selective processing of heat-protective multicomponent coatings with an elastic tool. The tool and method relate to the field of mechanical engineering and can be used for finishing selective anode-mechanical processing with an elastic tool of heat-shielding multicomponent coatings located on complex sections of the part in places difficult to access by the tool, and containing dielectric granules and a metal binder. pipe surface according to copyright certificate 259585, Bulletin No. 2 of 1970, characterized in that, in order to increase productivity and quality of processing, the cathodes-tools are made in the form of separate flexible plates, and on the inner surface of the pipe there are elastic chambers with air pressure to create a dense adhering of the chambers to the surface of the processed pipe.

The disadvantages of the known device include a violation of the stability of the interelectrode gap between the tool and the workpiece area due to the insufficient elasticity of the flexible tool in the transverse direction in the areas of recesses on the workpiece surface and the need for increased force pressing the tool to the coating, causing a violation of the quality of the surface layer of the workpiece.

Closest to the proposed tool and method are the tool and method presented in the abstract and dissertation of Panicheva E.V. “Combined finishing of transitional sections of ceramic-metal coatings with dielectric granules” (p. 12 of the abstract), defended in the specialty 05.02.07 in the Dissertation Council D999.155.03 on December 18, 2020 at the Voronezh State Technical University, where the flexible tool is made in the form of a thin metal tape with an abrasive deposited on it and for finishing, a combined method of dimensional anodic dissolution with pressing to the surface of the coating of the part using a clamping element in the form of a chamber was used in the combined electroabrasive processing of the ceramic-metal coating, while the pressing force of the tool is provided by air pressure supplied inside the chamber, and the method carried out by reciprocating movement of the chamber together with a metal tape by flexible tension elements.

The disadvantages of the known tool are the violation of the interelectrode gap between the tool and the workpiece area due to the insufficient elasticity of the flexible tool in the transverse direction in the areas of depressions on the surface of the heat-protective multicomponent coating and the need for increased force pressing the tool to the heat-protective multicomponent coating, which causes the destruction of the dielectric granules of the heat-protective multicomponent coating abrasive grains of the tool and a decrease in the heat-shielding properties of the heat-shielding multicomponent coating on the part. In addition, the pressure in the chamber without support from the side opposite to the tool on the concave sections of the heat-protective multi-component coating cannot ensure uniform contact of the tool with the finishing zone of the metal binder of the heat-protective multi-component coating and does not provide the required cleanliness of the surface of the heat-protective multi-component coating, and in places of increased chamber pressure destroys heat-shielding dielectric granules and violates the heat-shielding properties of the heat-shielding multicomponent coating. The combination of movements of the camera and the metal band of the tool does not allow to stabilize the process of combined finishing and violates the cleanliness of the processing.

The present invention is aimed at providing the required roughness of a heat-shielding multicomponent coating, maintaining heat-shielding dielectric granules and properties of a multicomponent heat-shielding coating, and ensuring a stable process for the method of local removal of the metal binder of a multicomponent heat-shielding coating by anodic-mechanical finishing of the protrusions of the metal bond protruding between the dielectric granules without damaging them. , including on the inner surfaces of parts with limited tool access to the processing zone of a heat-protective multicomponent coating. This is achieved by the fact that its conductive base is made by weaving from a transverse and longitudinal metal cathode wire, which has periodic bends perpendicularly made along its length, the amplitude of which is not more than the interelectrode gap created by abrasive grains protruding from the conductive base, while the conductive base of the tool from the side ends connected with a vibrator, made with the possibility of creating a reciprocating movement of the conductive base and with a unit for measuring and regulating low-voltage direct current.

A method for combined anodic-mechanical finishing of a heat-shielding multicomponent coating, characterized in that local removal of protrusions of the metal bond of the heat-shielding multicomponent coating by anodic-machining in an electrolyte with local dissolution of the metal bond under the influence of current without damaging the dielectric granules during reciprocating movement of the tool base, when In this case, before processing, the length of the perimeter of the conductive base of the tool is reduced to a value that ensures its supply to the treated area of the heat-protective multicomponent coating, the tool is installed with abrasive grains towards the heat-protective multicomponent coating, after which a flexible sealed chamber is placed on the conductive base of the tool, connected to the pressure measurement and control unit , from which gas is supplied to the chamber and its pressure is adjusted until the tops of the abrasive grains touch the surface of the entire treated area of the tops of the abrasive grains of the surface of the entire treated area without cutting the tops of the abrasive grains into the recesses of the heat-shielding multicomponent coating, then a low-voltage current is supplied from the unit for measuring and regulating the low-voltage direct current on the cathode-wire of the tool and the anode-metal bond of the heat-protective multicomponent coating, electrolyte is supplied by irrigation and the vibrator is turned on to create a reciprocating movement of the conductive base of the tool in the direction of its supply along the treated area of the heat-protective multicomponent coating, the processing is carried out until the metal bond of the heat-protective multicomponent coating is locally removed coatings, and the processing process is controlled by a unit for measuring and regulating the current until its value is stabilized, after which the supply of current and electrolyte is stopped, the unit for measuring and regulating pressure in the flexible sealed chamber reduces the pressure until gaps appear between the flexible sealed chamber and the conductive base of the tool, and the conductive base is moved tool and a flexible sealed chamber with a rigid support on the mating area of the treatment zone of the heat-protective multi-component coating of the part and repeat the operation until the entire area of the heat-shielding coating is finished, then the air pressure in the flexible sealed chamber is removed and the tool is removed, compressing its conductive base.

The device of the tool and the essence of the method are illustrated in Fig. 1-6. In FIG. 1 shows the structure of the tool and a diagram of the implementation of the method, where 1 is the workpiece; 2 - metal bond of a heat-shielding multicomponent coating on a part; 3 - dielectric granule in a heat-protective multicomponent coating of a part; 4 - abrasive grain on a conductive basis of the tool; 5 - conductive base of the tool; 6 - gas supply line; 7 - rigid support; 8 - flexible sealed chamber; 9 - flexible conductive rod; 10 - electrolyte storage and supply unit; 11 - vibrator; 12 - block for measuring and regulating low-voltage direct current; 13 - block for measuring and regulating pressure in the chamber; in fig. 2 the position of the tool elements when processing a flat surface of the part coating, where 4 is an abrasive grain on a conductive basis of the tool; 14 - heat-protective multicomponent coating on the workpiece; 15 - transverse elastic metal wire of the conductive base of the tool with a periodic bend along the length; 16 - longitudinal elastic metal wire of the conductive base of the tool with a periodic bend along the length; in fig. 3 is the position of the tool elements when processing the curved surface of the part cover, where 17 is a section of the flat surface of the part cover; 18 - section of the curved surface of the part coating; 19 - bending of the longitudinal elastic metal wire in the conductive base of the tool in the area of the flat surface of the part coating; 20 - bending of the longitudinal elastic metal wire in the conductive base of the tool in the area of the curved surface of the part coating; in fig. 4 - coating before finishing, where 14 - heat-protective multi-component coating on the workpiece; 21 - protrusion of a metal bond on the surface of the coating of the part; in fig. 5 - the position of the tool and the mechanism of electroabrasive finishing of the coating with an elastic tool, where 4 - abrasive grain on the conductive basis of the tool; 15 - transverse elastic metal wire of the conductive base of the tool with a periodic bend along the length; 16 - longitudinal elastic metal wire of the conductive base of the tool with a periodic bend along the length; 22 - cathode-wire; 23 - direction of reciprocating movement of the tool base; 24 - weak electrolyte; 25 - anode - a metal bond of a heat-shielding multicomponent coating on a part; figure 6 - the surface of the heat-shielding multi-component coating after finishing electroabrasive processing, where 26 - the surface of the heat-shielding multi-component coating after finishing.

A tool for combined finishing of heat-shielding multicomponent coatings, in which the conductive base 5 (Fig. 1) is made of conductive weaving from the transverse 15 (Fig. 2) and longitudinal 16 elastic metal wire, which has periodic bends along the length perpendicular to the surface of the conductive base 5 (Fig. 1) tool. On the wire 15, 16 (Fig. 2) from the side of the heat-protective multi-component coating 14 of the part, abrasive grains 4 are applied (Fig. 1, 2, 5), which are pressed against the heat-protective multi-component coating 14 of the workpiece 1 by a flexible sealed chamber 8 (Fig. 1 ) on the tool surface. The amplitude of the bending of the wire 15 and 16 (Fig. 2, 5) is not more than the interelectrode gap created by abrasive grains 4 protruding from the conductive base of the tool (Fig. 1, 2, 5). From the side opposite the conductive base of the tool 5 (Fig. 1), a flexible sealed chamber 8 is installed on it, based on the conductive base of the tool 5 on one side, and on a rigid support 7 on the other. The flexible sealed chamber is connected by a flexible gas supply line 6 with a block 13 for measuring and regulating pressure in a flexible sealed chamber 8. The conductive base of the tool 5 from the side of its ends is connected to a vibrator 11 and with a block 12 for measuring and regulating low-voltage direct current.

The method is carried out as follows: in the case of combined finishing of heat-shielding multicomponent coatings from dielectric granules 3 and a metal bond of a heat-shielding multicomponent coating 2 (Fig. 1), by anodic mechanical processing, the process is performed in a weak electrolyte 24 (Fig. 5) with the dissolution of the metal bond of the heat-shielding multicomponent coating 2 (Fig. 1) by a current without damage to dielectric granules 3 in a heat-shielding multicomponent coating of a part (Fig. 1), where under the current supplied from the unit 12 for measuring and regulating low-voltage direct current through the cathode-wire 22 (Fig. 5) and the anode 25 , which is used as a metal bond 2 (Fig. 1) heat-shielding multicomponent coating 14 (Fig. 2, 3) on the workpiece 1 (Fig. 1). The conductive base 5 of the tool under the action of the vibrator 11 through flexible conductive rods 9 (Fig. 9) reciprocates 2 of the conductive base of the tool 3 (Fig. 5). Under the action of current, the cathode-wire 22 and the anode 25 (Fig. 5) in the environment of a weak electrolyte 24 coming from the electrolyte storage and supply unit 10 (Fig. 1), the protrusions 21 (Fig. 4) of the metal bundle 2 (Fig. 1) heat-protective multicomponent coating 14 (Fig.2, 3) parts are removed by anodic dissolution, the uniformity of which ensures the integrity of the dielectric granules 3 (Fig. 1) heat-protective multicomponent coating 14 (Fig. 2, 3, 4). With limited access of the tool to the place of processing of the heat-protective multicomponent coating, the length of the perimeter of the conductive base 5 of the tool is reduced to a value that ensures its supply to the place of finishing and installation of the tool with abrasive grain 4 (figure 1, 2) towards the heat-protective multicomponent coating 14 (fig. 2, 3) on the workpiece 1 (Fig. 1), after which a flexible sealed chamber 8 is placed on the conductive base 5 of the tool, into which gas, for example air, is supplied from the unit 13 for measuring and controlling pressure in the flexible sealed chamber 8 through line 6, and regulate its pressure by the measurement and control unit 13 until the tops of the abrasive grains 4 reach the surface of the entire treated area (Fig. 2) without cutting the tops of the abrasive grains into the recesses of the heat-protective multicomponent coating of the workpiece 1 (Fig. 1). In this case, the length of the curved or concave section 18 of the surface of the heat-protective multi-component coating of the part (Fig. 3) can have an increased length of the perimeter 20 both along and across the supply of elastic metal wire 15 and 16 (Fig. 2) relative to the flat surface of the heat-protective multi-component coating of the part 17 with a bending of the wire 19. Then, from the unit 12 (Fig. 1) for measuring and regulating direct current, a low-voltage current is supplied to the cathode-wire 22 and anode 25 (Fig. 5), (metal bond 2 in Fig. 1) of the heat-shielding multicomponent coating 14 ( Fig. 2, 3, 4) on parts 1 (Fig. 1), weak electrolyte 24 (Fig. 5) is supplied by irrigation from the block 10 (Fig. 1) for storing and supplying weak electrolyte, vibrator 8 is turned on to create reciprocating movements 23 (Fig. 5) of the conductive base 5 (Fig. 1) of the tool in the direction of its supply along the treated area of the heat-shielding multicomponent coating 14 (Fig. 2, 3) of part 1 (Fig. 1) and processed until the local removal of the metal bond 2 of the heat-shielding multicomponent coating 14 by combined anodic finishing of protrusions 21 (Fig. 4) metal bond 2 (Fig. 1) protruding between dielectric granules 3 (Fig. 1) without damaging them, including on the inner surfaces of parts with limited tool access to the processing zone of the heat-protective multicomponent coating 14 (Fig. 2, 3 ). The processing process is controlled by block 12 (Fig. 1) for measuring and regulating low-voltage direct current until its value stabilizes, after which the supply of current and electrolyte is stopped, by block 13 for measuring and regulating the pressure in the flexible sealed chamber 8 is reduced until gaps appear between the flexible sealed chamber 8 and conductive base 5 of the tool, move the conductive base 5 of the tool and the flexible sealed chamber 8 with a rigid support 7 to the mating section of the processing zone of the heat-protective multi-component coating 14 (Fig. 2, 3) of the part 1 and repeat the operation until the entire area of the heat-protective multi-component coating 14 is finished. As a result, a surface 26 (Fig. 6) is obtained with the required quality of finishing of a heat-protective multicomponent coating. Next, the pressure is removed in the flexible sealed chamber 8 (Fig. 1), the conductive base 5 of the tool is compressed and it is removed from the part 1.

An example of the implementation of the method.

In the combustion chamber of a liquid-propellant rocket engine with local areas of a heat-shielding ceramic-metal coating on the inner surface, including a spherical one, it is necessary to remove the nickel protrusions by finishing. It serves as a binder of a heat-shielding multicomponent coating applied by the plasma method for fixing dielectric granules of black grade 54C silicon carbide with a size of 0.38-0.42 mm on the surface of the combustion chamber, forming together with a nickel bond a heat-shielding layer 0.4-0.48 mm thick with a surface roughness of 60 -70 µm and local protrusions of nickel of the same size. It is necessary to remove the protrusions while maintaining the integrity of the dielectric granules, the uniformity of the heat-shielding multicomponent coating and obtain a roughness not lower than Rz=10mkm. The perimeter of the neck of the part, through which it is possible to bring a tool in the form of a grid to the place of processing, is 20% less than the inner diameter of the place where the heat-protective multicomponent coating is applied. The tool is made of brass wire with a diameter of 0.15 mm with a bend of longitudinal and transverse wires, forming an amplitude of 0.4-0.5 mm. The wire is coated with abrasive grains of electrocorundum, which are fixed on the wire from the side of the working surface galvanically with nickel with a protrusion of about 0.5 mm. By compressing the wire braided conductive base of the tool and twisting it, it was possible to reduce the length of the adequate perimeter of the tool base up to 1.5 times and freely introduce an elastic tool with flexible conductive metal rods into the workpiece, remove the front flexible conductive rod from the opposite section of the part, connect the rods with using a vibrator with a frequency of 50 Hz, set the amplitude of the reciprocating movements of the tool to 0.5-1.0 mm. Then, a flexible hermetic chamber with cavity dimensions was placed on the conductive base of the tool, providing contact with the opposite treated surface of the heat-protective multicomponent coating of the inner surface of the part. Compressed air pressure was applied to the flexible sealed chamber and the pressure was increased until the abrasive grains of the tool touched the entire processing zone of the heat-protective multicomponent coating, including the spherical section with a profile depth of 4.8 mm. The working pressure in the chamber was 0.18 MPa. A voltage of 5V was applied through flexible current-carrying rods, sending a 6% aqueous solution of sodium nitrate to the irrigation treatment zone. Turning on the vibrator, increased the voltage on the electrodes to stabilize the current strength. It amounted to 7 + 0.3V. The treatment was carried out before the current began to fall on the electrodes. The processing time of the site was 35 seconds. Measurement of the irregularities of the heat-shielding multicomponent coating after finishing showed that the surface roughness was Rz=7-8mkm. At the same time, no traces of destruction of heat-shielding dielectric granules were found, and the thickness of the heat-shielding coating became at least 0.4 mm, which meets the requirements of the technical specifications for the thickness of the heat-shielding multicomponent coating.

Claims (3)

1. A tool for combined anode-mechanical finishing of a heat-shielding multicomponent coating containing dielectric granules and a metal binder, when pressed against the processed heat-shielding multicomponent coating by an element in the form of a flexible sealed chamber, having a conductive base with abrasive grains deposited on it, characterized in that it is conductive the base is made by weaving from a transverse and longitudinal metal cathode wire, which has periodic bends perpendicularly made along its length, the amplitude of which is not more than the interelectrode gap created by abrasive grains protruding from the conductive base, while the conductive base of the tool is connected from the ends to a vibrator made with the possibility of creating a reciprocating movement of the conductive base, and with a block for measuring and regulating low-voltage direct current. 2. The method of combined anode-mechanical finishing of a heat-protective multicomponent coating containing dielectric granules and a metal bond with a tool according to claim 1, characterized in that the protrusions of the metal bond of the heat-protective multicomponent coating are locally removed by anodic-machining in an electrolyte with local dissolution of the metal binder under by the action of current without damaging the dielectric granules during reciprocating movement of the base of the tool, while before processing, the length of the perimeter of the conductive base of the tool is reduced to a value that ensures its supply to the treated area of the heat-protective multicomponent coating, the tool is installed with abrasive grains in the direction of the heat-protective multicomponent coating, after which on a flexible sealed chamber is placed on the conductive base of the tool, connected to a pressure measurement and control unit, from which gas is supplied to the chamber and its pressure is regulated until the tops of the abrasive grains touch the surface of the entire treated area without cutting the tops of the abrasive grains into the recesses of the heat-shielding multicomponent coating, then from the measurement unit and regulation of low-voltage direct current, low-voltage current is supplied to the cathode-wire of the tool and the anode-metal bond of the heat-protective multicomponent coating, electrolyte is supplied by irrigation and the vibrator is turned on to create a reciprocating movement of the conductive base of the tool in the direction of its supply along the treated area of the heat-protective multicomponent coating, the process is carried out processing until the local removal of the metal bond of the heat-shielding multicomponent coating, and the processing process is controlled by a low-voltage direct current measurement and control unit until its value stabilizes, after which the current and electrolyte supply is stopped, the pressure in the flexible sealed chamber is reduced by the pressure measurement and control unit until gaps appear between the flexible a sealed chamber and a conductive base of the tool, move the conductive base of the tool and the flexible sealed chamber with a rigid support to the mating section of the processing zone of the heat-protective multi-component coating of the part and repeat the operation until the entire section of the heat-protective coating is finished, then the pressure is relieved in the flexible sealed chamber and the tool is removed by squeezing its conductive base. 3. The method according to claim 2, characterized in that air is supplied to the flexible sealed chamber from the pressure measurement and control unit.

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