RU2634398C2 - Combined treatment method of narrow part channels - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention can be used for finishing treatment of small-sized flow channels of parts of various shapes, for example, slit channels of cooling shells having unstable initial micro- and macro-geometry of the surface and uneven physicomechanical properties of the surface layer of the material after preliminary shaping. The method includes electrochemical treatment of narrow channels of parts while simultaneously pumping a conductive liquid through all channels, containing not more than 2% of abrasive grain M1-M3. During the treatment, the flow of liquid passing through the channels is measured, and the electrochemical treatment is carried out at a voltage of 8-10 V and a constant pressure of the pumped conductive liquid until a predetermined flow rate is reached.

EFFECT: increasing the operational parameters of parts with narrow channels due to obtaining a stable micro profile of the channel surface and selective alignment of the micro-profile of their surface in conditions of limited space for the combined electrochemical treatment.

2 dwg, 1 ex

Description

The invention relates to the field of combined processing and can be used for finishing processing of small-sized flow channels of parts of various shapes, for example, slotted channels of cooling shells having unstable initial micro- and macro-surface geometry and uneven physical and mechanical properties of the surface layer of the material after preliminary shaping.

The known method [1], used in abrasive extrusion processing of parts having a channel of cylindrical shape, turning into a cone. A cone-shaped leveling device is placed in the conical part of the channel. The latter provides a constant cross-sectional area of the formed annular gap along the entire length of the conical part. A viscoelastic abrasive mixture is forced through the channel to ensure a constant volumetric flow rate of the abrasive mixture. Such actions contribute to increasing the uniformity of the channel processing along the entire length. This method cannot be implemented in holes of small diameter, and uneven removal of material occurs, increasing in smaller places of the hole section.

There is a method of hardening processing of the inner surfaces of parts [2], which consists in supplying balls to the surface to be treated with the application of an electric field, characterized in that the treatment is carried out in a gas-liquid weakly conducting medium at an electric field voltage of 2-5 V in two stages, and in the first stage the treated surface at an angle of no more than 60 ° serves beads with a diameter of 150-200 microns with a compressed air pressure of 0.2-0.4 MPa and a treatment time of each surface section of 30 s, and at the second stage, beads with a diameter about 50 μm in diameter with a compressed air pressure of not more than 0.3 MPa and a treatment time of each surface area of 15 s. This method cannot be implemented in holes with a depth of more than 5 diameters due to shielding and mutual collision of balls in the hole.

Closest to the proposed one is a method of jet electrochemical processing of nozzle holes [3], comprising supplying a conductive fluid through a hollow cathode tool and machined holes, characterized in that the conductive fluid is initially supplied without connecting current to the cathode instrument, and its flow rate is recorded through each the hole to be treated, then the hole with the highest flow rate is determined and all the holes are drowned, then the current is turned on and the holes are sequentially opened, located They are located behind the hole with the highest flow rate, and through each of them pumping conductive liquid is performed until the flow rate is equal to the flow rate through the hole with the highest flow rate. Using the totality of the above techniques in the electrochemical treatment of nozzle openings allows us to solve the problem of fine-tuning the nozzles by uniformity of spray and eliminating rejects by this characteristic. The disadvantages of this method are the inability to ensure the geometric shape of the hole with a distorted original cross-sectional shape and deep hole due to uneven material removal and inapplicability to non-circular channels, as well as multiple flow rates for each hole of each nozzle, which significantly increases the cost of their refinement.

The present invention is aimed at improving the performance of parts with narrow channels by obtaining a stable microprofile surface and selective alignment of the microprofile surface in a limited space combined electrochemical treatment with the addition of abrasive in a conductive working fluid pumped simultaneously through all channels of the part.

The invention and the sequence of the method is illustrated by drawings.

In FIG. 1 shows a diagram of the combined electrochemical treatment of narrow channels of a part with the addition of an abrasive. The essence of the method consists in passing a flow of conductive fluid 5 containing abrasive 3 of low concentration (2%) with grain size M1-M3 simultaneously through all channels of part 1. A low voltage current (8-10 V) is applied to the technological system “conductive fluid-part”, and it is maintained under a certain regime of time until a given flow rate is obtained at a constant liquid pressure. The direction of the flow of conductive fluid with the abrasive indicated by arrow 2 allows you to correct the local errors of form 4, since the abrasive works more actively in places where the nominal pass is reduced and removes material in these places that need additional removal of material, aligning the cross section of all channels of one part. The electrochemical effect intensifies the process of mechanical removal of material from microprotrusions, reducing processing time.

With mechanical contact of the abrasive grain with the protrusions, the material is removed by micro cutting and the productivity of the process depends on the concentration of the abrasive, the orientation of a single abrasive at the moment of interaction with the surface, the size of the granules and the profile of the channel. Simultaneously with the mechanical action, the effect of anodic dissolution reduces the contact force due to liquid and oxide films between the workpiece and the granule, as well as due to the anodic dissolution of the peaks of irregularities on the surface at the points of contact with the granule, which reduces the friction resistance. All channels of the part are made with minimal drawing dimensions, allowing you to remove microprotrusions within the tolerances on the dimensions so as not to violate the requirements of the design documentation.

To carry out combined processing of slotted channels, a system for measuring flow rate characteristics is built into the installation for electrochemical fine-tuning. The essence of the work of such a technological system is as follows:

- to carry out combined processing, fill the line with a conductive fluid with the addition of an abrasive, apply voltage to the part and the working fluid, turn on the installation for combined treatment;

- in the process of combined electrochemical processing with the addition of an abrasive, the total flow rate of the conductive fluid through the flow channels is measured automatically at a constant pumping pressure, without turning off the voltage and without stopping the supply of abrasive,

- the processing time is automatically limited upon reaching the set flow rate. Upon reaching the specified flow rate, the installation is turned off and the system is flushed;

The sequence of operation of the installation shown in FIG. 2, consists in the following. Before starting the electrochemical treatment with the addition of abrasive filler, the installation is tuned. To do this, the workpiece is placed in the device for combined processing 6, the valves 9 are moved to position I, the pump 12 is turned on, the conductive fluid is supplied from the tank 14 when the required pressure is reached, which is monitored by the pressure gauge 7. For the combined processing, the valves 9 are moved to position II turn on the pump 11, connecting the line with the capacity of the conductive fluid with the addition of abrasive 13, and turn on the installation for combined processing 6, take readings from the flow meter 10. Upon reaching the specified of the flow rate, the installation 6 is turned off automatically, the bench valves 9 are moved to position I and the system is flushed and cleaned using the filter 8. The pumps 11 and 12 are turned on, the valves 9 are switched over automatically using the control panel 15; the console also displays pressure and flow parameters.

Measurement of the flow rate passing through the channels of the conductive fluid with the addition of abrasive during the combined treatment allows you to control the mass flow rate of the conductive fluid and upon reaching the desired rate to stop processing. This ensures that channels with an exact preset flow rate are obtained. The combination of two types of impacts in one process: mechanically abrasive and electrochemical with simultaneous measurement of the flow rate of conductive fluid with the addition of an abrasive, can simultaneously provide the desired geometric shape of the cross section of all channels of the part, the necessary roughness and the specified flow rate. By changing the concentration of abrasive and voltage, you can control the process of formation of surface microgeometry with specified characteristics.

An example implementation of the method. A cylinder with cooling channels with a width of 4 mm and a height of 1.2 mm and an initial surface roughness of channels of 5-7 μm was processed according to the above-described scheme in the following combined processing modes: voltage U = 8 V, anodic current density 0.1 A / m ² , abrasive concentration of 2% grit M1-M3, time 12 s at a constant pressure of pumping fluid 1 × 0.20 MPa.

As a working fluid, weakly conductive process water was used. Repeated lapping operations were not required.

The surface roughness in the slotted channels of the cylinder was 1.2-1.4 μm, the hardening of the surface layer was 3.3 ÷ 3.4%, the stability of the flow characteristics at operating pressures according to the design documentation for the channels of one part was 1-1.5%, in a batch parts 2-3%, which meets the specified technical requirements of the developer to the channels of flowing parts

Information sources

1. RF patent No. 2469832. The method of abrasive extrusion processing of the channel with a cylindrical and conical parts / Auth. Levko V.A., Pshenko E.B., 2012

2. RF patent for the invention No. 2491155. The method of hardening processing of the internal surfaces of parts / Auth. Sukhochev G.A., Nebolsin D.M., Smolyannikova E.G., 2013

3. RF patent for the invention No. 2162394. The method of tuning nozzles / Auth. Smolentsev V.P .; Smolentsev G.P .; Smolentsev E.V .; Dorofeev A.A .; Koptev I.T., 2001

Claims (1)

A method for the combined processing of narrow channels of parts, including the electrochemical treatment of narrow channels of parts while simultaneously pumping through all channels of a conductive fluid containing not more than 2% abrasive with a grain size of M1-M3, while in the process of processing the flow rate of the fluid passing through the channels is measured, and the electrochemical processing carried out at a voltage of 8-10 V and a constant pressure of the pumped conductive fluid to achieve a predetermined flow rate.

Images