SU1710240A1 - Electrode tool for electrically machining small-diameter holes and method of manufacturing it - Google Patents

Abstract

The invention relates to the field of machine building, and can be used for dimensional electroprocessing of small-diameter holes. The purpose of the invention is to increase the machining accuracy by increasing the rigidity of the electrode tool. The device contains a profiling part 1. a guiding part. insulating sheath 3. The profiling part 1 is installed in the sheath 3 with a gap designed to supply the working medium to the treatment area. The guide part is made in the form of ribs 4. interconnected by a shell. The total cross-sectional area of the channels formed by the ribs, the shell and part 1. is smaller than the cross-sectional area of the gap between the shell and part 1 to the guide part by the total cross-sectional area of the ribs, which is chosen from the condition 3 ^ 5 / 3p < 4. where SP is the total cross-sectional area of the ribs; : 3з '^^ is the cross-sectional area of the gap between the shell and part 1 to the guide part. In the manufacture of an electrode tool, a nylon cutter is inserted into the gap between the shell and the profiling part from the working end of the tool electrode and fixed them on the inner surface of the shell by pulling the assembled tool electrode through a preheated to a temperature close to the melting temperature of the sheath material and the filaments, the calibrating element with a hole whose diameter is chosen less than the diameter of the assembled electrode tool by 0.1-0.05 mm. 2 sec.pf'-ly, 4 ill., 1 tabl .. ^ L ^ L / I; ^ rCOXI o | XiJ ^ iOl > &

Description

The invention relates to the field of engineering, in particular, to methods for producing deep holes of any profile and small cross section in metals and alloys in the process of electrical dimensional processing.

The purpose of the invention is to improve the accuracy of processing holes.

FIG. 1 shows a hole with a conductive wall located in it; the moment of treatment is a longitudinal section; figure 2 - electrode-tool, longitudinal section; in FIG. 3 is a section A-A in FIG. 2; figure 4 - section bb in figure 2.

The device contains a profiling part 1, a guiding element 2, a current-insulating sheath 3, the profiling part 1 is installed in a current-insulating sheath 3 with a gap for supplying the working medium to the electrode tool, and the guiding element is made in the form of ribs 4 interconnected by a thin insulating shell 5, placed in the side interelectrode gap with the possibility of fixing the profiling part. in the center of the hole. The ribs and a thin insulating sheath divide the interelectrode gap into several channels: channels. For electrolyte exit from the tool electrode and channels for removing the electrolyte from the treatment zone. The channels for electrolyte exit from the tool electrode are formed by the surfaces of the profiling part 1, ribs 4 and the inner side of the insulating sheath, and the channels for removing the electrolyte from the working zone are formed by the side surface of the hole being machined and the outer side of the insulating part, the total area of the channels cross-section for removing the electrolyte from the tool electrode less than the cross-sectional area of the gap to enter the working medium into the cavity of the current-insulating sheath by the total area the cross-sectional edges which conditions are selected from:

3 5з / 5р 4,

where S3 is the cross-sectional area of the gap for injecting the working medium into the cavity of the current-insulating sheath;

SP is the total cross-sectional area of the ribs.

The upper part of the guide element 2 is hermetically connected to the tubular current-insulating sheath 3 (Figures 2 and 3), the outer diameter of which is less than the diameter of the hole being machined.

The second end of the current isolating shell is tightly connected to a special electrolyte supply chamber, while the cross-sectional area of the internal cavity does not overlap with the details of its attachment to the chamber filled with electrolyte.

The profiling part of the electric tool is connected through the cavity of the tubular current-insulating sheath by means of a metal connection to the current source. The shape and geometrical dimensions of the cross section of the profiling part are independent of the shape and geometrical dimensions of the transverse

5 sections of metal connection with a current source under the condition that the pressure of electrolyte supply is established to establish a steady flow of electrolyte throughout the cavity volume

0 tubular current isolating shell. Such a condition can be realized, for example, by making a guide element with a total cross-sectional area of the electrolyte outlet channels.

5 from the tool electrode to the working treatment area is smaller than the cross-sectional area of the gap for electrolyte entry from the nozzle of the electrolyte supply chamber. The metal bond can be made by extending the core part, not changing the shape and geometric dimensions of the cross section over the entire length before connecting to the current source. The ratio of the input and output areas of the electrolyte in the pin of the current insulating sheath is crucial in the design of the proposed electrode tool with insufficient rigidity of the main part for transmitting the axial feedrate

0 When machining the holes, and is chosen depending on the mass of the electrode tool in the working state (filled with electrolyte), on the viscosity of the electrolyte and the friction force of the guide element about

5 walls of the hole.

In the case under consideration, in the proposed electrode tool, the elastic current-insulating sheath also performs the functions of a rigid constructive

0 elements for transmitting axial feed force.

This becomes possible due to the fact that the total cross-sectional area of the ribs, made in the lateral

5, in the working area and partially overlapping the electrolyte from the current-insulating sheath, was chosen in accordance with the condition of complete elongation of the elastic tubular sheath along the entire length of the tool electrode, i.e.

Pn Sp (Me + FTP + t),

where RP is the electrolyte supply pressure;

SP is the total cross-sectional area of the edges of the guide element;

Me is the mass of the electrode tool in working condition (filled with electrolyte);

FTP is the force of friction of the guiding element against the walls of the hole being machined;

Gp is the stress force of viscosity in the electrolyte passing through the gap between the current insulating sheath and the profiling part.

The length of the ribs 4 is set only along the length of the guide element.

The rationale for choosing the ratio of the sizes of the total cross-sectional area of the channels for electrolyte discharge from the tool electrode and the cross-sectional area of the gap for introducing the working medium into the cavity of the current-insulating sheath is given in the table.

The table shows the measurement results of the V mm / min processing speed (electrode feed rate) and the roughness height Ra of the surfaces of the holes obtained, depending on the ratio 5z / 5p, where Zs is the cross-sectional area of the gap for the electrolyte to enter the cavity of the current-insulating sheath; Sp - sum-, marne cross-sectional area of the ribs.

Material samples - Art. 45.

From the data in the table, it can be seen that at values less than 3, the processing speed V mm / min decreases, and the height Ra, µm increases. This is due to the fact that with an increase in the total cross-sectional area of the ribs, the cross-sectional area of the channels for supplying electrolyte to the treatment area, and as a result, the temperature of the electrolyte in the treatment area rises and the process slows down.

With an increase in SZ / Zr values of more than 4, the processing speed V mm / min also decreases, and the roughness height Ra increases. This is due to the fact that as a result of excessively reducing the size of the cross-sectional area of the ribs, the condition of complete stretching of the elastic tubular current-insulating sheath is not observed and the rigidity of the electrode tool is lost during processing due to the high flow rate of the electrolyte. tool and its supply to

axial direction becomes poorly feasible, uneven.

Thus, the most optimal ratio

3 ЗЗ / Зр 4.

With this ratio, the processing speed is the highest and the processing purity corresponds to the characteristic electrochemical processing results.

A method of making an electrode tool for electrically processing small diameter holes is to

next.

The core part 1 of the electrode, made, for example, of tungsten wire O 1., 0 mm, is placed at one end inside a current-insulating sheath with

a gap designed to supply electrolyte to the electrode tool.

As an insulating sheath, you can use, for example, an insulating sheath with a wire of mark RPD 761-0.5, with

the inner diameter of the shell is 1.3 mm and the wall thickness is 0.08-0.1 mm.

Then, for the manufacture of the guide element 2, between the insulating sheath and the wire, from the working end

the electrode tool inserts ribs made, for example, from segments of a forest with a diameter of 0.25 mm and a length of 5-7 mm, while the diameter of the nylon forest should not exceed the value of the interelectrode gap. The ribs 4, which fix the profiling part 1, are installed with a certain constant angle of inclination relative to the geometrical axis of the guide element, the value of which is chosen from the relation

2n: p

cos a - p1

where R is the radius of the profiling part; . I is the length of the fixing edge: n is the number of edges. For this design of the electrode tool, in accordance with the condition of necessity and sufficiency, fixing one circle in the center of another (i.e. fixing the profiling part in the center of the hole being machined) to a circle of larger diameter is reliably solved with

by using three edges placed in the gap between the circles, 120 ° around the circle, or provided that any of the three arcs of the circles connecting the fixing points of the edges is less than 180 °.

The ribs 4 are fixed on the inner surface of the current isolating sheath. To do this, the assembled electrode tool is applied through a calibration hole, heated to a temperature close to the melting point of the current-insulating sheath material and manufactured fins.

This also makes it possible to fix the edges relative to each other, obtaining an edge thickness of 0.3 mm, which corresponds to the characteristic interelectrode gap. The assembled electrode tool is connected to a current source; for this, the free end of a tungsten wire is passed through a 1.5 mm hole in a conical nozzle into an electrolyte supply chamber and connected to the negative pole of the current source. A cone of the nozzle is tensioned onto the cone of the nozzle and sealed with a cap nut that is wrapped around the nozzle cone. With this design, the proposed electrode tool withstands the electrolyte supply pressure of up to 4.5 atm. The diameter of the holes obtained is 1.6 mm. Hole depth 500 mm. The angle of the locking ribs in this case 8T12 °.

Processing is performed as follows.

Using a special sealed chamber, the electrolyte under pressure is supplied to the tubular current-insulating sheath 3. The steady-state flow of the electrolyte, established throughout the volume of the cavity of the tubular current-insulating sheath, creates constant values of pressure on the inner side of the current-insulating sheath and maintains it in a tight-tensioned state, which allows transmitting through it an axial force to feed the entire electric tool, regardless of the rigidity of the metal connection of the profiling part 1 with the current source. The electrolyte, the passage through the electrolyte outlet channels from the electrode tool, formed by the ribs 4, the inner side of the insulating shell 5 and the surface of the profiling part 1 connected to the negative pole, enters the working treatment area. The metal of the workpiece, connected to the positive pole, dissolves in the electrolyte and together with it, first through the electrolyte outlet channels from the treatment zone formed by the outer surface of the insulating shell 5 and the surface of the hole to be machined, then through the gap formed by the surface of the hole being machined and the outer barrel current insulating sheath 3, is poured out of the hole. To prevent possible stagnation zones

electrolyte in the working area of the processing flow of the electrolyte is attached to the rotational movement in the working area due to the implementation of fixing the profiling part 1 of the ribs 4, the guiding element 2 with a constant angle of inclination relative to the geometrical axis of the guiding element.

In the initial period of machining, the direction of the tool electrode is imparted by imposing 1 on the part of a special conductor having a guide hole whose diameter is equal to the diameter of the hole: formed in the part during machining. In the process of processing, the supply pressure of the electrolyte can be raised to values limited by the tensile strength of the current-insulating sheath material;

The device of the electrode-tool ensures the accuracy of a given direction, the independence of the shapes and geometrical dimensions of the core part from the geometrical dimensions of the metal connection with the current source, the supply of electrolyte to the working area in a wide range of technological needs for the processing of metals and alloys and the removal of reaction products when forming deep holes with small sizes profile

The technical solution allows to prevent the formation of electrolyte stagnation zones in the treatment zone and to increase the depth of the holes being machined to 500 mm.

Claims (1)

1. Electrode-tool for electrical processing of small-diameter holes, containing an electrically conductive rod placed in a dielectric shell with a gap forming a channel for supplying the working medium to the treatment area, characterized in that, in order to improve machining accuracy, the electrode-tool is provided the guide part formed by the shell at the working end of the electrode tool and the dielectric fins inserted into the electrode tool placed between the shell and the rod; the cross-sectional area of the channels formed by the ribs, the shell and the core is smaller than the area of the cross-sectional area of the gap between the shell and the rod to the guide part, by the value of SP of the total area of the edge, which is chosen from the condition of 3 5/5 4. 2, A method of manufacturing an electric tool for electrical processing of small-diameter holes, which consists in placing an electrically conductive rod with a gap inside the dielectric shell, characterized in that, in order to increase the machining accuracy, the gap between the shell and the rod from the working end of the tool electrode is inserted segments of the kapron thread and fix them on the inner surface of the shell by pulling the assembled electrode tool through a preheated to a temperature close to Temperature melting sheath material and filaments calibrating element with an opening whose diameter is chosen less than the diameter of the assembled electrode-instru0 ment at 0.1-0.05 mm. Electrolyte removal Flowed electrolyte fe.J 6-6 FagL