RU1808553C - Method of electric treatment of holes of small diameters - Google Patents

Description

The invention relates to the processing of metal by the action of high-density electric current on a workpiece using an electrode, which is a tool, in particular, to combined methods of processing small-diameter holes by means of electroerosive piercing of a hole in a dielectric fluid medium and electrochemical treatment by feeding electrolyte to the output terminal of the hole for example, a nozzle opening of a nozzle of a diesel nozzle.

The aim of the invention is to improve the quality of the machined hole by obtaining a constant predetermined radius of rounding of its edge.

This goal is achieved by the fact that in the method of electrically treating a hole of small diameter with a series of electric discharges in a dielectric fluid medium between a workpiece and an electrode that performs a working movement, at the stage of processing the edges of the hole, they are fed

electrolyte from the opposite side of the firmware for a certain period. At this time, the mode of movement of the electrode is changed to cease its working movement. To change the mode of motion, longitudinal vibrations with an amplitude equal to a predetermined radius of rounding of the edge are reported to the electrode. At the same time, a constant flow rate of the electrolyte is maintained, which is lower than the flow rate of the dielectric fluid.

Owing to this embodiment of the method, longitudinal vibrations of the electrode make it possible for the electrolyte to penetrate into the outlet portion of the surface of the hole, which is part of its depth equal to the predetermined rounding radius. At the same time, the predetermined flow ratio ensures a decrease in the electrolyte concentration at the electrode oscillation depth, and as the depth deepens, the intensity of dissolution of the surface of the hole decreases, which allows

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to learn the required rounding radius, and also prevents the penetration of electrolyte beyond this depth, which allows to keep the diameter of the hole constant outside the rounding zone.

Thus, the method allows to save the size of the bore of the hole, and the hydraulic characteristics can be significantly improved due to the same rounding of the edge.

In addition, in order to obtain identical radii of rounding of the edges of two or more holes extending into the common cavity, the electrolyte flow rate is maintained constant during the preparation of the edges of each subsequent hole by sealing the previously machined holes.

This method allows during the period of electrochemical dissolution of the edge during the processing of each subsequent hole, due to the sealing of the already processed holes, to maintain the required constant flow rate of the electrolyte.

When implementing the method, the optimal electrolyte flow rate should be 1.5-2 times less than the flow rate of the dielectric fluid. If the flow ratio at the gap between the part and the electrode of the order of 0.015 mm is less than one and a half, then the electrolyte can flow outside the rounding area and the electrochemical processing of the cylindrical part of the hole is unacceptable and can lead to an increase in the bore cross section. And if the expense ratio is more than two, then the concentration of the electrolyte will be less, and the hydraulic characteristics of the hole will not have a given value.

The drawing shows the location of the nozzle holes in the body of the spray. The nozzle body 1 has several nozzle openings a (two in the section), of the same diameter d and depth, and the radius of the rounding off of the outlet edge of the hole is R. The openings exit into the blind cavity b. Electroerosive treatment of each hole a is carried out by a series of electric discharges from the generator 2 of the discharge pulses by the electrode 3 in the dielectric fluid medium, which is supplied through the nozzle 4. The interelectrode gap during processing is L. After receiving the through hole, the erosion treatment is stopped by turning off the generator 2 and turning off the working movement of the electrode, which fixes the electrode inside the fillet zone (as shown in

drawing). Generator 2 is switched to a constant voltage source, longitudinal vibrations with amplitude c are communicated to the electrode, and electrolyte is fed through the nozzle 6 into the blind cavity. After the treatment is completed, the generator 2 is turned off, the electrolyte supply is stopped, the electrode is withdrawn from the hole, the housing 1 is turned to process the next hole, and the previously processed one is hermetically sealed.

Example. The YaZTA atomizer body for a KAMAZ diesel engine was machined, having four nozzle holes d 0.34 + 0 01 mm, 0.9 mm long and a predetermined optimum radius of rounding R 0.11 mm. Distilled water with specific resistance 2500 Ohm m and flow rate 0.5 l / h. The copper electrode of the state standard specification 2112-79 MT brand diameter was used as an electrode

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During the rounding of the exit edge, longitudinal vibrations of 0.115 mm were reported to the electrode; a 2% sodium nitrate solution with a flow rate of 0.23 L / h was used as the electrolyte.

Comparative bench tests for the stability of the throughput of sprayers processed by the known and proposed methods showed a significant increase in the stability of the throughput. Thus, the proposed method allows to obtain high quality nozzle openings that provide improved operational performance of diesel engines.

Using the method in the mass production of diesel fuel equipment will create a significant technical and economic effect.

Claims (2)

1. A method of electrically treating holes of small diameter, including piercing the hole with a movable electrode in the EDM mode with the dielectric fluid being fed into the treatment zone and finalizing the inner edge of the hole in the electrochemical mode with the electrolyte being fed from the opposite side, characterized in that, in order to improve the quality of the hole machining with a predetermined radius of rounding of the inner edges in the nozzle nozzles, in the mode of electrochemical treatment, the axial oscillations with the amplitude and it is equal to the specified radius of the rounding of the edges, while providing an electrolyte flow rate less than the flow rate of the dielectric fluid, 2. The method according to claim 1. due to the fact that, in order to identify the quality of processing of several holes entering into the common cavity, during the processing of each subsequent hole, all previous openings are sealed.