RU2403132C1 - Method of electroerosion machining of integral gear unit closed rim - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to electroerosion machining of complex-section articles made from current conducting materials by wire electrode at PNC cutout machines. Proposed method comprises coordinate transfer of wire electrode bending around exposed rim of integral gear wheel unit in axes X and Y along trajectory set by control program. Note here that lateral involute surface of closed rim first tooth is machined, then tooth space, lateral surface and second tooth crest generatrix, second lateral surface of second tooth are machined. Similarly, surface of the entire gear ring is machined all over its edge in turning the gear unit about its axis. In 3 to 4 cycles, asperity height makes Ra 0.2 to 0.4 mcm.

EFFECT: higher efficiency and reliability.

2 cl, 2 dwg, 2 tbl

Description

The invention relates to the field of aircraft engine, mechanical engineering, in particular to electrical discharge machining (EEO) of complex products from conductive materials by wire electrode on EDM cutting machines, and can be used in the manufacture of cylindrical involute gear blocks of external gears.

A known method of EEE of gears, in which a cylindrical involute gear rim is formed on an EDM cutting machine using CNC coordinated coordinate movements of the wire electrode in the X and Y axes (processing along the contour) along the path specified from the control program (RU 2212317 C1), where one of the lateral surfaces of the tooth is replaced by a straight line, therefore, the requirements for the accuracy of the form are much softer, and the number of forming points of the profile (respectively, the number of reference points of the trajectory of the wire elec rod) of this lateral surface is given by the smallest number of them taken as an analog.

Disadvantages:

1. A straight line is processed, which is replaced by the involute of the non-working side of the tooth.

2. The generatrix of the vertices and depressions between the teeth is not processed by EEE, blade processing with subsequent grinding is applied, that is, burns occur on the surfaces and the overall (long) size of the wheel block increases (the number of reference points of the trajectory of the wire electrode for electroerosive shaping of the ring gear is insufficient).

The closest method of the same purpose to the claimed invention in terms of features is the EEE method of gears, in which the gear of a cylindrical involute gear is formed on an EDM cutting machine with CNC due to coordinated (subject to the laws of description equidistant involute side surfaces) coordinate movements of the wire electrode in X and Y axes (contour processing) along the path specified from the control program (Khudobin L.V., Kravchenko V.D., Yudakov D.V. dew improve operational efficiency electroerosion cutting gear teeth on CNC linear interpolation // Engineering Bulletin -. 2001. - №8 -.. C 39-44), taken as a prototype.

Disadvantages:

1. The generatrix of the vertices and depressions between the teeth is not processed by EEE, blade processing with subsequent grinding is applied, that is, burns occur on the surfaces and the overall (long) size of the wheel block increases (the number of reference points of the trajectory of the wire electrode for electroerosive shaping of the ring gear is insufficient).

EFFECT: increased productivity of manufacturing closed rims of solid wheel blocks with a tendency to reduce dimensions and increase the reliability of the design of wheel blocks.

The technical result is achieved by the fact that in the method of electric discharge machining the closed crown of a whole block of gears on a CNC electric cutting erosion machine, including the coordinate movements of a wire tool electrode enveloping the open ring of a whole gear block in the X and Y axes along the path specified from the control program while forming the lateral involute surface of the first tooth of the closed crown, then the cavity between the teeth, the side surface and forming the vertices of the second tooth, the second side the second tooth surface and likewise forms the surface of the entire gear ring along the contour when the block of gears rotates around its axis. For 3-4 cycles, the microroughness height Ra = 0.2-0.4 microns is provided.

The drawings show:

figure 1 shows a diagram of the electrical discharge machining of a cylindrical involute closed rim 4 of the gear block 6 with the bending of the open rim 5 of the wire 3 using diamond guides 2 and rollers 1, which is obtained by EDM cutting on a CNC machine according to the proposed method. This wheel in the design of the gear transmission can perform the function of both a reversible or a non-reversible gear wheel based on the fact that the end profiles (left and right) of the side surfaces for each of the teeth of the ring gear are formed involute when processing the generatrix of the vertices and depressions of the teeth;

figure 2 shows a cylindrical involute disc gear, the gear rim of which is obtained by EDM cutting on a CNC machine according to the proposed method. This wheel in the design of the gear transmission can perform the function of both a reversible and a non-reversible gear based on the fact that the end profiles (left 8 and right 8) of the side surfaces for each of the teeth form a ring gear involute when processing generatrix of the tops 7 and valleys 9 of the teeth .

A feature of the proposed method is that in order to increase the productivity and reliability of the design of the block of gears 6 for electroerosive shaping of the ring gear 4 (figure 1) (side surfaces 8 (figure 2), forming the tops 7 (figure 2) and the depression between the teeth 9 (figure 2)) set the path of movement of the wire electrode based on the control program along the closed ring contour of the whole block of gears in the CNC of the EDM machine with the dimensions indicated in figure 2 (R1min, drowning 0,00 ... 0, 15 m m).

The implementation of the method.

The proposed method of EEE of gears can be implemented on the basis of any of the EDM cutting machines with a CNC contour system (AP200L, EXC100, AP450L, AP150, AP200, AP200L, Mitsubishi FA10, Mitsubishi FA20, etc.).

The part is based on the machine in a standard fixture (based on prisms along the landing necks of the gear block). The wire electrode in a special device (figure 1) using diamond guides 2 and additional rollers 1 with the envelope of the open crown is fed to the part. Processing is carried out for 3-4 cycles of processing along the contour of the closed gear of the whole block of gears when the part is rotated around its axis to ensure the required degree of accuracy of the gear in the EEE modes presented in table 1 and below.

Workpiece parameters:

1) module m = 3;

2) the number of teeth z = 19;

3) degree of accuracy 5-5-5;

4) the displacement coefficient x = 0;

5) profile angle α = 25 °;

6) characteristics of the surfaces of the samples before EDM (table 2);

Wire electrode parameters:

1) material: brass wire;

2) size: diameter ⌀ 0.2 mm.

Processing modes are assigned according to the reference data depending on the material of the part, wire electrode and equipment used. The following modes are assigned for parts made of high alloy steel and tools:

1) Table 1 shows the sequence of the EDM treatment;

2) the average open circuit voltage is 120 V;

3) the shape of the pulses is comb;

4) polarity - direct;

5) the working environment is oil;

6) specific metal removal - 1.5 - 2.5 mm ³ / (A · min);

7) the surface roughness after EEE Ra = 0.2-0.4 microns.

Table 1 EDM modes Parameter Name Processing sequence one 2 3 Pulse duration, μs 64 16 8 Operating frequency, kHz fourteen 125 200 Average current, A 32 fourteen 10 The gap between the wire and the part, mm 0,07 0.015 0.005 Average operating voltage, V 42 28 25

table 2 Sample Material steel grade Microhardness of contact surfaces for nitrocarburizing ion nitriding 20HZMVF-Sh (EI415-Sh) HRC _E 60 ... 65 HRC _E 33 ... 45 18X2H4MA 12X2N4A

As a result of the EEE, a closed crown 4 of the integral block of gears 6 shown in FIG. 1 will be formed.

Claims (2)

1. The method of electrical discharge machining of the closed crown of a whole block of gears on a CNC electric cutting erosion machine, including the coordinate movements of a wire-electrode tool enveloping the open ring of a whole block of gears in the X and Y axes along the path defined by the control program, while forming a side the involute surface of the first tooth of the closed crown, then the cavity between the teeth, the side surface and the vertices of the second tooth, the second side surface of the second tooth and similarly they shape the surface of the entire gear ring along the contour when the block of gears rotates around its axis. 2. The method according to claim 1, in which 3-4 processing cycles provide a height of microroughness Ra of 0.2-0.4 microns.

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