Method of hardening of gear wheels with the coating

 

The invention relates to machineoperating and can be used for finishing operations for hardening of complex geometric surfaces with the simultaneous application of composite coatings of ductile metals. The objective of the invention is to improve the quality of coverage, and the reliability of its adhesion with the base metal. The proposed method includes a preliminary hardening of the working surface, the flow in the zone of contact of the composition in the following ratio, wt.%: chloride copper 4-8, Anthranilic acid 8-10, ndimethylacetamide 5, urea 0,5, stearic acid, 0.5 to distilled water 15-20, the composition of ultrafine powders of copper and Nickel in the ratio of 1:1 2-4, glycerin rest, while the friction force in the contact zone reaches 10-12 N, and in the process of formation of composite coatings perform layer-by-layer hardening tool on the working profile, the optimal effort in the area of contact, applied to the tool, P = 2sinb[[n]/0,418]2/E, where f is the contact force, n;- the radius of curvature, mm; b - the working length of the line of contact, mm; E - fashion is permissible contact voltage, MPa. The technical result of the invention is to improve the wear resistance of the samples coated with the stated method of coating. 3 Il.

The invention relates to machine to machine and can be used for finishing operations for hardening of complex geometric surfaces with the simultaneous application of composite coatings of ductile metals.

Known method of applying a metallic coating, wherein the coating material is brought into the treatment area while its surface deformation due to static pressure instrument (SU 1504070, IPC 7 24 In 39/00, 30.08.1989).

The known method of applying metal coatings using a rapidly rotating wire brushes, when the coating material is applied from a terminal donor located at the front of the workpiece surface, the latter is pressed against the pile of brush with a certain force (SU 1206068, IPC 7 24 In 39/00, 23.01.1986; SU 1540364, IPC 7 F 01 D 11/14, 30.06.1994).

Closest to the proposed method is a method of hardening of gear wheels with a coating including a preliminary hardening of the working surface, the flow in the zone of contact of the composition containing the x powders of copper and Nickel in the ratio of 1:1, glycerin else (EN 2138579 C1, IPC 6 23 26/00, 27.09.1999).

The disadvantages of the above methods is the inability to handle complex geometric surfaces gears, application of composite coatings insufficient adhesion to the basis and quality of the coating.

The technical result improved quality of coverage, the reliability of its adhesion with the base metal, the ability to handle involute surface of the gear wheels is achieved by a preliminary hardening treatment involute surface of the gear wheels by air blast shot, or in some other way, where there is a reinforcing effect, such as enhancement of the hardness of the working surface, the formation of a favorable residual stress of compression, clean the surface from dirt. The coating process of preparation begins by running tool with a certain contact force or a possible offset of the axes of the installation. At this stage of treatment is reduced initial roughness of the working surface, is formed juvenile surface, which greatly facilitates the process of education preliminary diffusion layer and subsequently the coating.

In the process of formation of the surface is carried out layer-by-layer hardening treatment in the same tool. At this stage, the additional introduction of ultrafine particles included in the coating and the diffusion layer. Introduction copper coating of ultrafine particles of copper and Nickel allows to form a composite coating on the involute surface. An additional protection against direct contact of the rubbing surfaces. Layer-by-layer hardening treatment improves the quality of the coating.

In the coating decreases the microhardness of the working surface by pokrytiya smoothed when hardening the coating treatment. This surface of the tooth in hydrodynamic mode slippage has smaller values of the friction force reduces the dissipation in the contact and allow for a greater work load on the teeth of wheels and as a result gear has a greater efficiency.

To determine the best efforts of the pressing tool (creating pressure in the contact zone) uses the well-known formula of the contact stresses (formula Hertz)where PN- normal pressure in the contact is determined by the dependence ofTo determine the optimal effort (pressure) in the area of the contact surfaces of the workpiece and the tool is used dependencywhere f is the contact force, N;- the radius of curvature, mm; b - the working length of the line of contact, mm; E - modulus of the coating, MPa;
- angle gear deg;
[n] - permissible contact voltage [n] = 160150 MPa.

The second limiting criteria process cover (defining permissible nagruzkakh see reference "machine Parts. Calculation and design" /under. Ed. N.With.Acherkan, ed. 3-E. - M.: Mashinostroenie, T. 1,-1968,-s.).


wherethe coefficient of sliding friction surfaces;
specific linear normal load in contact, N/mm;
VOCD- the speed of the sliding contact m/s, VOCD= |VK1-VK2|;
VK1VK2- the velocity of the contact point along the tooth, m/s;


given radius of curvature, m;
the radii of curvature of the profile of the mating tooth of the wheel at the contact point;
1,2- frequency of rotation of the wheel and tool, rad/S.

It is established that the allowable temperature in contact in the absence of binding profiles of the tooth 250oC.

The load value (estimated effort) in the treatment area may change due to the displacement of the axes of the tool and the workpiece surfaces on the wheel and the contact force, which is provided by the working spring installation for processing.

Example contracepprevalence hardening (base material BKC-4). Scheme final processing involute surface of the toothed wheel shown in Fig. 1, 2. For material of this type is recommended composition, wt.%:
Chloride copper - 4-8
Anthranilic acid - 8-10
The ndimethylacetamide - 5
Urea - 0,5
Stearic acid - 0.5
Distilled water is 15-20
The composition of ultrafine metals (copper, Nickel in the ratio 1:1) - 2-4
Glycerin - Rest
After pre-hardening of the machined wheel 1 is mounted on the rim of the cartridge, for example, a lathe (see Fig. 1). In the tool holder of the machine (not shown) sets the body of the tool holder 2 in which is mounted a spring-loaded tool 3. Turn on the rotation of the details. Preparatory processing involute surface is carried out by a free spinning tool on the work surface, a member in engagement with the workpiece. The transverse flow of the caliper and the action of the operating spring 4 located in the housing, the optimum effort RV Voltage (force) occurring in the contact zone, controlled by the movement of the screw 5 relative to the body of the tool holder. Preliminary preload tube 6 provides the stability of pressure in the contact zone in proteina running reduces the initial roughness. In the process of formation of a coating (feed composition) is carried out layer-by-layer padding. The optimal number of liquids is determined by the formula:
Q=zb, l/m, - (5)
wherespecific application of the compound in contact (determined experimentally, about 2 g);
z - number of teeth;
b - the working length of the tooth.

Preparatory phase the formation of the coating, its layer-by-layer hardening takes about 40-60 with when the wheel speed of 15-20 rad/S. the Calculation, the specific strength of the pressure contact is 30-40 N/mm2.

Comparative evaluation of the quality of composite coatings was carried out on the kinetic parameters of the treated surfaces sclerometry and on the results of bench tests on samples. As the kinetic parameter was determined by the activation energy of surface coatings, with increasing numerical values which increases wear resistance of the surfaces. The original surfaces (uncoated) the value of activation energy reaches 15 kJ/mol, while the surfaces with the proposed composite coating 26 kJ/mol. Bench tests have proved that the wear resistance of samples with composition is adavani change of friction coefficient on time (EP properties) for different formulations is shown in Fig. 3.

The proposed composition is prepared by alternately mixing followed by the addition of glycerol and ultrafine powders. The components included in the composition, non-toxic, environmentally friendly, safe in operation. For extended storage subsidence of ultradispersed powders, therefore, before application of the composition is thoroughly mixed.


Claims

Method of hardening of gear wheels with a coating including a preliminary hardening of the working surface, the flow in the zone of contact of the composition containing the chloride of copper, ndimethylacetamide, urea, stearic acid, distilled water, composition of ultrafine powders of copper and Nickel in the ratio of 1: 1 and glycerin, wherein the composition further comprises Anthranilic acid in the following ratio, wt. %:
Chloride copper - 4-8
Anthranilic acid - 8-10
The ndimethylacetamide - 5
Urea - 0,5
Stearic acid - 0.5
Distilled water is 15-20
The composition of ultrafine powders of copper and Nickel in the ratio of 1: 1 2-4
Glycerin - Rest
when this frictional force in the contact zone reaches 10-12 N, and in the process obrazovaniye force in the contact zone, applied to the tool
P = 2sinb[[n]/0,418]2/E
where f is the contact force, N;
- the radius of curvature, mm;
b - the working length of the line of contact, mm;
E - the modulus of elasticity of the coating, MPa;
- angle gear deg;
[n] - permissible contact stress, MPa.

 

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