RU145833U1 - STEP GUIDE DEVICE FOR SUBMERSIBLE MULTI-STAGE ELECTRIC CENTRIFUGAL PUMP - Google Patents

Abstract

1. The guide apparatus of the stage of a submersible multistage electric centrifugal pump, comprising a cylindrical body made of pseudo-alloy steel-copper, an upper disk having an opening surrounded by an edge along the shoulder, a lower disk, guide vanes located between the disks, characterized in that the upper surface of the shoulder is formed layer with increased hardness using laser heat treatment. 2. The guide apparatus according to claim 1, characterized in that the layer with increased hardness is distributed over the entire width of the shoulder to a depth of 0.5-1.2 mm and is made with a fusion zone, the depth of which does not exceed 0.05-0.1 mm and smoothly decreases from the center to the edges, and the width is 0.35-0.4 of the width of the shoulder.

Description

The utility model relates to the field of pump engineering and can be used for the manufacture of working bodies (steps) of submersible centrifugal and centrifugal-vortex pumps designed for pumping formation water with a high concentration of abrasive particles.

Known corrosion-resistant stages of a submersible pump containing a guiding apparatus and an impeller, and in the case of a single-bearing design and a protective shaft sleeve made of a material such as niresist composition: 3% C, 1-2.8% Si, 13.5-17.5% Ni, 1.5-2.5% Cr, 5.5-7.5% Cu, 0.012% S, oct. Fe (Vikhman V.G., Filippov V.N. Submersible wear-resistant centrifugal pumps for oil production: Express information. M: TSINTIHIMNEFTEMASH, No. 6, 1989; TU 26-06-1305-81 Castings of working bodies of submersible centrifugal pumps for oil production from austenitic modified cast iron of the Niresist type).

The disadvantage of steps made of such materials is the low wear resistance in the abrasive medium of the shoulder of the guide apparatus, which together with the impeller washer forms a friction pair of the axial bearing of the step.

Known radial friction pair in the steps of submersible pumps, operable with a high content of abrasive particles, the elements of which are made of powder copper steel with the addition of a pair of chromium and molybdenum to any element (Patent No. 2114334 of the Russian Federation, F16C 33/12, publ. June 27, 1998. )

The disadvantages of steps made of such a material include low abrasion resistance.

The closest technical solution to the claimed one is the guiding apparatus of the stage of a submersible multistage electric centrifugal pump, containing a cylindrical body made of powder material, an upper disk having an opening surrounded by a shoulder along the edge, a lower disk, guide vanes located between the disks (Patent No. 2193115 of the Russian Federation, F04D 13/08, published on November 20, 2002).

For the manufacture of the guide vane, a material was used containing: C - 0-1.5% and copper - 10-20%, in which, if it is necessary to increase corrosion and abrasion resistance, nickel and molybdenum are added, and copper is introduced by the method of impregnation (infiltration). Such powder materials impregnated with copper are commonly called steel-copper pseudo-alloys (Smyshlyaeva T.V., Shatsov A.A. Steel-copper pseudo-alloys with a dispersed carbide phase // Promising materials. Technologies. Constructions. Krasnoyarsk, 1998, issue 4, p. 53-56).

The disadvantage of this technical solution is the need for the introduction of expensive alloying elements and insufficient resistance of the shoulder of the guide apparatus to abrasion.

This utility model provides increased durability of the structure.

The specified technical result is achieved by the fact that in the guide apparatus of the stage of a submersible multistage electric centrifugal pump containing a cylindrical body made of a steel-copper pseudo-alloy, an upper disk having an opening surrounded by a shoulder along the edge, a lower disk, guide vanes located between the disks, according to the invention, a layer with increased hardness is formed on the upper surface of the shoulder using laser heat treatment.

A layer with increased hardness is made with a fusion zone, the depth of which does not exceed 0.05-0.1 mm and gradually decreases from the center to the edges, and the width is 0.35-0.4 of the width of the shoulder. Moreover, the total depth of the layer of high hardness, distributed over the entire width of the shoulder, is 0.5-1.2 mm

The formation by means of laser heat treatment (LTO) of a layer of increased hardness with the indicated parameters significantly increases the resistance of the collar to abrasion due to a decrease in the residual tensile stresses along the edges of the reflow zone.

The selected size of the reflow zone minimizes roughness, which allows to reduce the volume or completely abandon further surface treatment (grinding), that is, reduce the number of operations for the manufacture of guide vanes. It is not advisable to form a fusion zone with a depth exceeding 0.1 mm, since in this case sections with a high level of residual stress arise in the high hardness layer, and with a fusion zone depth of less than 0.05 mm, a layer of increased hardness is formed, the thickness of which is insufficient for collar protection against wear.

Figure 1 presents the inventive guide apparatus; figure 2 - microstructure of a fragment of a layer of high hardness in the cross section of the shoulder, perpendicular to the direction of movement of the laser beam during LTO; Fig.3-5 view of the surface of the shoulders with different reflow zone after grinding to a depth of 0.1 mm

The guide apparatus (Fig. 1) consists of a cylindrical body 1, an upper disk 2 and a lower disk 3, between which guide vanes 4 are formed, which form the return channels. On the upper disk 2 there is a hole 5, surrounded by a shoulder 6 along the edge. The upper layer 7 of the shoulder 6 has increased hardness and is formed by LTO.

In the layer with increased hardness 7 (Fig. 2) in the middle of the upper surface of the shoulder around the circumference, a melting zone 8 is formed, the depth of which gradually decreases from the middle to the edges, then there is a surrounding layer with partial melting 9. Below and on both sides of the reflow zone thermal influence (HAZ) 10. At the edge of the heat-affected zone 10, a transition zone 11 is formed. Next is the main volume of the collar 6 with structure 12, in which no visible changes occurred during LTO.

Zones 8–10 have high hardness; in transition zone 11, hardness drops sharply. In the bulk of collar 6 to the entire depth (up to 3-4 mm), the microhardness remains constant at 400 HV, which is slightly higher than the microhardness of the material before LTO (250-300 HV).

The structure of the fusion zone 8 consists of a steel matrix (mainly in the martensitic state) with dispersed copper deposits. The microhardness in the reflow zone is 700-800 HV. The structure of the heat-affected zone (HAZ) 10 consists of a steel matrix (martensite + a small amount of residual austenite), in which the copper inclusions remain in the same form as in the starting material. The microhardness in the martensitic regions of the HAZ ranges from 700 to 1000 HV.

In the layer with partial reflow 9 during the LTO, the copper component melts, but since the steel frame remains in this solid state, the dispersion of the structure, as in zone 8, does not occur.

The selection of LTO modes ensures the formation in the shoulder 6 of the melting zone 8 with a depth of 0.05-0.1 mm and a width of 0.35-0.4 of the width of the shoulder 6, in which a layer with increased hardness is extended to a depth of 0.5-1 , 2 mm. In LTO, the laser beam is directed perpendicular to the upper surface of the shoulder 6, while in the best execution the center of the laser beam moves in the middle of the width of the shoulder around the circumference (for example, due to the rotation of the part around its axis), which ensures uniform hardening of the surface on both sides of the reflow zone one pass.

When the stage is working, the impeller washer slides along the hardened surface of the shoulder 6 of the guide apparatus. Together, they act as an axial stage bearing. The abrasive wear of the shoulder occurs under the influence of abrasive particles present in the pumped liquid, which fall between the shoulder and the washer. In the performance with a rubber washer, the collar wears out first. Therefore, increasing the hardness of the surface layer of the shoulder significantly increases the wear resistance of the entire structure.

The table shows the results of comparative life tests of the guide vane of the centrifugal-vortex stage pump 2 VNNP5-79, commercially available from Novomet-Perm CJSC (sample 4), the claimed guide vane (sample 2) and guide vanes having a fusion zone on the outer surface of the collar with a depth that goes beyond the claimed (samples 1, 3) when using the same impeller and rubber washers. The guiding devices were made of pseudo-alloy carbon steel-copper (ZhGr1D15) with a shoulder width of 4 mm. LTO parameters, sizes of specimen fusion zones and test results are shown in the table.

Life tests were carried out under the following conditions:

- medium - water + quartz sand (10 g / liter);

- rotation speed - 2910 rpm;

- pump flow rate - nominal (80 ± 8 m ³ / day);

- test time - 4 hours

As can be seen from the table, the wear of the shoulder of the inventive guiding apparatus (sample 2) compared with commercially available (sample No. 4) is 35% less. The increase in wear resistance of samples 1 and 3 is slightly less, respectively, 18 and 29%.

Table Sample No. Processing mode Reflow zone Melting zone width / shoulder width Collar wear, mm The increase in wear resistance,% (W / S), (kW / cm ² ) ν, mm / min spot diameter d, mm depth mm width mm one 12 0.8 3.2 0.287 2.49 0.623 0.42 eighteen 2 8 1,2 3.99 0,090 1.46 0.365 0.33 35 3 8 0.8 3.99 0.170 2,31 0.578 0.36 29th four without LTO - - - 0.51 Notes: W is the used laser power; W / S is the power density in the laser beam; ν is the velocity of the laser beam.

Figure 3 illustrates the advantage of sample 2 over samples 1 (figure 4) and 3 (figure 5), which is manifested when grinding the upper surface of the shoulder to a depth of about 0.1 mm. On samples 1 and 3, having a depth of reflow zone of more than 0.1 mm and a width of more than 0.4 width of the shoulder, after the stage of grinding the shoulders, it is seen that annular chipping holes 13 are formed on both sides of the flash zone 8, which shows a high level of residual stresses stretching in these areas, which explains the low resistance to wear of the samples during life tests, compared with sample 2, in which there are no chipping holes.

Thus, an increase in the wear resistance of the inventive guide vane is achieved during LTE of the shoulder surface not only due to changes in the microstructure and increase in hardness of the material, but also due to the absence of sections with a high level of residual stresses in the layer of increased hardness.

In these examples, a pseudo-alloy carbon steel-copper was used, in which there are no alloying elements. Similar results can be achieved in the case of using an alloyed steel matrix, provided that the susceptibility of the material to quenching is maintained.

Claims (2)

1. The guide apparatus of the stage of a submersible multistage electric centrifugal pump, comprising a cylindrical body made of pseudo-alloy steel-copper, an upper disk having an opening surrounded by an edge along the shoulder, a lower disk, guide vanes located between the disks, characterized in that the upper surface of the shoulder is formed layer with increased hardness using laser heat treatment. 2. The guide apparatus according to claim 1, characterized in that the layer with increased hardness is distributed over the entire width of the shoulder to a depth of 0.5-1.2 mm and is made with a fusion zone, the depth of which does not exceed 0.05-0.1 mm and gradually decreases from the center to the edges, and the width is 0.35-0.4 of the width of the shoulder.