RU2671030C2 - Method of restoration of worn surfaces of metal parts - Google Patents

Abstract

FIELD: transport machine building.SUBSTANCE: invention relates to electrophysical and electrochemical treatment, in particular to electroerosive alloying, and can be used for repairing machine parts. Method comprises applying coating with a surface roughness of 1 to 200 mcm to the worn surface of the part by electroerosive alloying with a metal electrode having a discharge energy of 0.036–6.8 J, on which the metal-polymeric material (MPM) is then applied, its polymerization is ensured and it is subjected to finish treatment, while the applied MPM is reinforced before the polymerization with a wire and before it is solidified, the MPM is applied until the reinforcing wire is completely coated with it, while the MPM is initially applied in a thickness at which the level of immersion of the reinforcing wire in the MPM corresponds to at least half the diameter of the reinforcing wire.EFFECT: invention provides improved adhesion and durability of the part to be restored.11 cl, 10 dwg, 4 ex

Description

The invention relates to the field of electrophysical and electrochemical processing, in particular, to electroerosive alloying, and can be used for repair of machine parts.

The most important tasks of the repair and maintenance production are maintaining operability, restoring the resource of machines and equipment, ensuring their high reliability and the possibility of efficient use. To solve these problems, it is envisaged to improve the quality of repairs by introducing modern methods of its organization and optimal technological processes of hardening and restoration of parts. The resource of restored parts, as a rule, is significantly higher due to the use of effective methods of restoration and improved properties of hardened surfaces.

Modern hardening technology has numerous methods for improving the structure and properties of the surface layer of parts, each of which has optimal applications, advantages and disadvantages.

There is a known method of electroerosive alloying (EEL), which is increasingly widely used in industry to increase the wear resistance and hardness of surfaces of machine parts, including those working at elevated temperatures and aggressive environments, to increase heat and corrosion resistance, as well as to restore worn surfaces machine parts during repair, etc.

EEL of the surface is the process of transferring material to the surface to be treated by a spark electric discharge. The method has a number of specific features:

- the anode material (alloying material) can form a coating layer extremely strongly adhered to the surface on the cathode surface (alloyed surface). In this case, not only is there no interface between the deposited material and the base metal, but even the anode elements diffuse into the cathode;

- alloying can be carried out in strictly specified places (radius from fractions of a millimeter or more), without protecting the rest of the surface of the part;

- the technology of electroerosive alloying of metal surfaces is very simple, and the necessary equipment is small-sized and transportable [Lazarenko NI Electrospark alloying of metal surfaces. - M.: Mechanical Engineering, 1976. - S. 3, 4, 13, 19].

Despite the fact that EEL has a positive effect on the wear resistance of the surface layer, its shortcomings often limit the implementation of this technology for a wide range of machine parts. Such disadvantages include an increase in the roughness of the surface of products after EEL, uneven surface hardening, the negative effect of erosion discharge on the fatigue properties of products, etc.

зношених поверхонь металевих деталей

Патент Украины №104664, МПК: В23Н 5/00 /Марцинковський B.C., Тарельник В.Б., Павлов О.Г.,

Опубл. 25.02.2014, Бюл. №4. - 3 с] (прототип).There is also known a method of restoring the surfaces of metal parts, including applying to the worn surface of a part of a coating an electroerosive alloying (EEL) with a metal electrode, in which the EEL coating is applied in conditions providing a given surface roughness of the coating, at least one layer of metal-polymer material is applied to the obtained surface (MPM), provide polymerization of at least one deposited layer of MPM, after which the final polymer layer of MPM is subjected to finishing th processing

on top of metal parts

Patent of Ukraine No. 104664, IPC: V23H 5/00 / Martsinkovskiy BC, Tarelnik VB, Pavlov OG,

Publ. 02/25/2014, Bull. Number 4. - 3 s] (prototype).

The disadvantages of this method are:

- low hardness of metal-polymer materials;

- the main application of the method is the restoration of parts in one-piece joints (seats for bearings, coupling halves, etc.);

- metal-polymer materials work well in compression and much worse in shear, which negatively affects their use for restoring friction surfaces in parts;

- a change in properties with increasing temperature on the friction surfaces, etc.

Therefore, at present, the technical task of improving the methods for restoring the surfaces of worn metal parts of machines has not lost its relevance.

To solve the problem formulated above, a method is proposed for restoring the surfaces of worn metal parts, which, like the known ones, involves applying an EDM to a worn surface of a part with a metal electrode in modes that provide a given surface roughness of 1 to 200 μm or more and determined discharge energy of 0.036-6.8 J, then at least one layer of metal-polymer material (MPM) is applied to the obtained surface, polymerization is provided, according to at least one deposited layer of MPM, after which the final layer of MPM is subjected to finishing treatment, in which, in accordance with the present invention, the applied layer of MPM is reinforced with at least one layer of wire before polymerization, while providing such a thickness of the applied MPM at which the level of immersion of the reinforcing wire in at least one layer of MPM corresponds to at least half the diameter of the wire forming at least one reinforcing layer, then, without waiting for the MPM to solidify, applied nnogo before dipping into it of reinforcing wires continue to apply at least one layer of the MMM to until completely cover at least one layer of reinforcing wire.

When restoring the soft antifriction worn surface of parts such as bodies of revolution, the applied MPM layer is reinforced before polymerization by winding a wire made of soft plastic material, such as copper, tin, babbitt, silver, tin bronze, onto it. The wire is wound with a pitch of at least 1.0-1.5 mm.

When restoring a hard wear-resistant worn surface of a part such as a body of revolution, the applied MPM layer is reinforced before polymerization by placing a spring made of wire made of hard wear-resistant material, for example, 65G, 9XB2C steel, BrB2 beryllium bronze, and heat-treated it. Moreover, a spring with a winding pitch of at least 1.0-1.5 mm is used.

When restoring a soft anti-friction worn flat and / or curved surface, the applied MPM layer is reinforced before polymerization by placing on it a mesh made of wire made of soft plastic material, for example, copper, tin, babbitt, silver, tin bronze.

When restoring a hard wear-resistant worn flat and / or curved surface, the applied MPM layer is reinforced before polymerization by placing on it a mesh made of wire made of hard wear-resistant material, for example, 65G, 9KHB2S steel, BrB2 beryllium bronze, and heat-treated.

In addition, a mesh with mesh sizes of at least 1.0-1.5 × 1.0-1.5 mm is attached outside the surface being restored, for example, by resistance welding. In this case, before applying a second coat of MPM, the previous coat of MPM after polymerization is cleaned and degreased.

In addition, the finishing treatment of the deposited layer of MPM can be carried out by a mechanical method, for example, grinding or blade processing, to the required depth.

The technical problem formulated above in the present invention is solved through the use of integrated technology, which includes the method of electroerosive alloying with the subsequent application of MPM reinforced with wire. When using the integrated technology, various options for the formation of the structure of the restored surface layer are possible.

The following are specific examples of the method with reference to schematic images, where:

In FIG. 1 presents photographs showing the destruction of the babbitt layer of the support fingers of the gears as a result of its poor-quality filling;

In FIG. 2 is a schematic representation of coating layers deposited on a worn surface of a restored part such as a body of revolution;

In FIG. 3 is a schematic depiction of the operation of immersing the reinforcing wire in the MPM layer deposited after the electro-magnetic layer on the worn surface of the part in FIG. 2;

In FIG. 4 is a schematic representation of a completed coating of a reconditioned part such as a body of revolution, including an MPM layer reinforced with a wire layer;

In FIG. 5 shows the rotor shaft of the central nervous system-180 pump with worn out bearing and landing journals;

In FIG. 6 depicts worn surfaces of thrust bearings;

In FIG. 7 depicts worn surfaces of journal bearings;

In FIG. Figure 8 shows a schematic representation of the reinforcement of an MMM layer with base and repeated mesh layers when restoring extremely worn flat surfaces;

In FIG. Figure 9 shows a schematic representation of the reinforcement of an MMM layer with base and repeated mesh layers when restoring extremely worn curved surfaces;

In FIG. 10 shows the lower part of the centrifugal compressor housing after many years of operation.

Example 1

Restoration of worn surfaces of parts such as bodies of revolution from soft antifriction metals.

As you know, the main reason for the failure of machine parts is not a breakdown, but the wear of their surface layer. Sometimes in the process of work it becomes necessary to restore the outer surfaces from soft antifriction metals of the parts of the bodies of revolution, for example, the support fingers of the gears after the destruction of the babbit layer.

On the worn surface of the part 1 (Fig. 2), by the EEL method, a coating layer 3 of any soft antifriction metal (copper, tin, silver, tin bronze, etc.) is applied. In this case, between the deposited metal and the part, a transition layer 2 is formed, which is the mutual diffusion penetration of the elements of the anode and cathode. Coatings can be applied by varying the discharge energy in the range of 0.036-6.8 J. With increasing discharge energy, the thickness of the applied coating and the surface roughness increase. The layer thickness may vary, depending on the nature of the interaction of the anode and cathode (installations with a manual vibrator, such as "Elitron 52-A" and mechanized installations with multi-electrode heads, such as "Elitron-347" or "EIL-9"), in the first case from 0.01 to 0.25 mm and in the second case from 0.05 to 2.0 mm, and the height of the microroughness (Rz) in this case changes, respectively, from 8.5 to 155.8 μm and from 20 to 200 microns. After that, metal-polymer material 4 is applied to the EEL surface.

Application of the material is one of the operations that determine both the quality of the formed adhesive bonds and the durability of the restored part. The metal polymer layer is carefully rubbed with a spatula or spatula into the surface of the restored part. When the polymer material is rubbed into the depressions and microroughnesses of the restored part, on the one hand, adhesion is improved, and on the other, it eliminates the likelihood of corrosion foci in these depressions not filled with polymer material. The formed MPM layer should be of such a thickness that subsequently the wire 5 wound subsequently on the surface of the component coated with it is submerged at least to half its diameter (Fig. 3).

Guided by the basic concept of the MPM application, namely, that its working layer should not be less than 1-1.5 mm, the step of winding the wire (t) on the shaft will be:

t = d + 1-1.5 mm

where d is the diameter of the wire [A.A. Ishchenko. Technological basis for the restoration of industrial equipment with modern polymer materials. - Mariupol: PSTU, 2007.- p. 93].

After winding the wire, it is necessary to continue the application of MPM until the applied layer covers the fully wound wire (Fig. 4).

In this case, to restore worn surfaces, you can use a wire of: copper, tin, babbitt, silver, tin bronze, etc.

Example 2

Restoration of worn surfaces of parts such as bodies of revolution from hard wear-resistant metals

In FIG. Figure 5 shows the rotor shaft of the TsNS-180 pump with worn bearing and landing journals, which have a hardness of about 35-40 HRC units and need repair. In this case, after applying an EEL coating of a hard wear-resistant metal to a machined worn surface and applying a layer of MPM, using the technology described above (see example 1, Fig. 2), a heat-treated spring is put on the formed layer with an interference fit. In this case, the thickness of the applied MPM 4 should provide coverage of the wire 5, at least up to half its diameter (Fig. 3).

After the spring is put on, it is necessary to continue applying the MMM until its ball 4 completely covers the coil of the spring (Fig. 4). It should be noted that the step when winding the spring, as in example 1, should be at least 1.0-1.5 mm. The material of the spring can be steel 65G, 9HV2S, beryllium bronze BrB2, etc.

The hardened metal-polymer material can be processed by any of the known methods, including grinding and processing with a blade tool [A.A. Ishchenko. Technological basis for the restoration of industrial equipment with modern polymer materials. - Mariupol: PSTU, 2007.- p. 55, 56].

Example 3

Restoration of worn flat and curved surfaces of parts made of soft antifriction metals.

Often there is a need to restore flat and curved worn surfaces from soft antifriction metals, for example, support and thrust sliding bearings (Fig. 6, 7).

In this case, after applying a soft antifriction metal coating to the machined worn surface by EEL and applying a layer of MPM, using the technology described above (see Example 1, Fig. 2), a mesh 5 is applied to the formed layer, FIG. 8, 9, made of soft antifriction metal with mesh sizes of at least 1.0-1.5 × 1.0-1.5 mm. In this case, initially the thickness of the layer 4 of the coating deposited by MPM should ensure that the wires of the mesh 5 are immersed in it, at least up to half their diameter (Fig. 3). The mesh 5, 6 can be attached outside the restored surface in any known manner, for example, by welding by resistance welding.

After installing the mesh 5, it is necessary to continue applying the layer 4 of the MPM coating until the mesh is completely immersed in it (Fig. 4, 8, 9).

In case of significant wear, the application of the mesh 6 can be repeated as many times as necessary (Fig. 8, 9). The hardened metal-polymer material can be processed by any of the known methods, including grinding or processing with a blade tool [A.A. Ishchenko. Technological basis for the restoration of industrial equipment with modern polymer materials. - Mariupol: PSTU, 2007.- p. 55, 56].

Example 4

Restoration of worn flat and curved surfaces of parts made of hard wear-resistant metals

In FIG. 10 shows the lower part of the centrifugal compressor housing with worn flat and curved surfaces after many years of operation.

In this case, worn flat and curved surfaces of the products are restored according to the technology described in example 3, except that the mesh used is made of heat-treated solid wire.

For all embodiments, the condition is true that, before applying a repeated layer of MPM, the previous layer of MPM 4 (Figs. 4, 8, 9) is cleaned and degreased after polymerization.

Claims (11)

1. A method of restoring a worn surface of a metal part, comprising applying to the worn surface of the part by electroerosive alloying with a metal electrode with a discharge energy of 0.036-6.8 J coating with a surface roughness of 1 to 200 μm, which is then applied to the metal-polymer material (MPM), its polymerization and finishing it, characterized in that prior to polymerization, the applied MPM is reinforced with wire and until it solidifies, it continues to be applied MPM until it is completely coated with it reinforcing wire, and initially MPM is applied with a thickness at which the immersion level of the reinforcing wire in the MPM corresponds to at least half the diameter of the reinforcing wire. 2. The method according to p. 1, characterized in that when restoring the soft antifriction worn surface of the part in the form of a body of revolution, the deposited MPM is reinforced before polymerization by winding a wire made of soft plastic material selected from copper, tin, babbitt, silver and tin bronze. 3. The method according to p. 2, characterized in that the wire is wound with a pitch of at least 1.0-1.5 mm. 4. The method according to p. 1, characterized in that when restoring the hard wear-resistant worn surface of the part in the form of a body of revolution, the applied MPM is reinforced before polymerization by placing a spring made of a wire made of a hard wear-resistant material selected from 65G steel on it with interference 9XB2C and BrB2 beryllium bronze, and heat-treated. 5. The method according to p. 4, characterized in that the spring is used with a winding pitch of at least 1.0-1.5 mm. 6. The method according to p. 1, characterized in that when restoring a soft antifriction worn flat and / or curved surface of the part, the applied MPM is reinforced before polymerization by placing on it a mesh made of a wire made of a soft plastic material selected from copper, tin , babbitt, silver and tin bronze. 7. The method according to p. 1, characterized in that when restoring a hard wear-resistant worn flat and / or curved surface of the part, the applied MPM is reinforced before polymerization by placing a mesh on it made of a wire made of a hard wear-resistant material selected from 65G steel, 9ХВ2С and beryllium bronze BrB2, and heat-treated. 8. The method according to p. 6 or 7, characterized in that the grid is attached outside the restored surface of the part, for example, by contact welding. 9. The method according to any one of paragraphs. 6-8, characterized in that a grid is used with mesh sizes of at least (1.0-1.5) × (1.0-1.5) mm. 10. The method according to any one of paragraphs. 6-9, characterized in that with significant wear of the restored surface, the mesh is re-applied. 11. The method according to any one of paragraphs. 1-10, characterized in that after polymerization during repeated application of the MPM, the surface is cleaned and degreased.

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