RU2537345C2 - Method of electrode wire production - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: initially at one end of wire its diameter is decreased by value of allowance for draw die installation and to length required for the draw die installation, this wire end is fixed in movable pole, then draw die is installed on the wire end, its diameter is equal to the diameter of wire with reduced diameter, this end is secured in movable pole. The opposite end of the weakly tensioned wire is fixed in the fixed pole, then tension forced are applied to wire ends, the force does not exceed the tensile strength of the wire material, beginning of the wire elongation during LV direct current passage through the wire is registered. Then wire end in the fixed pole is released, and wire is drawn through the draw die maintaining permanent tension forces acting on wire.

EFFECT: keeping of straightness and rigidity of long electrodes-tools out of plastic metals, ensuring the required diameter and accuracy of perforated hole.

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Description

The invention relates to the field of mechanical engineering and can be used for electroerosive, electrochemical, combined flashing of deep holes of small diameter in metallic materials with a plastic wire electrode tool.

A known method [1] of electrochemical processing of channels, in which tensile forces are used to straighten the electrode-tool.

The disadvantages of the method include the inability to maintain the straight axis of the electrode-tool after removing tensile forces.

A known method [2] of straightening the wire, according to which for straightening the wire is pulled and passed through it current pulses, causing heating, stretching and increased elasticity of the wire.

The disadvantages of the method include an uncontrolled change in the thickness of the wire during stretching, changing its diameter, increasing elasticity without stabilizing the residual stresses that cause secondary bending of the axis of the wire, the possibility of breaking in uncontrolled tension, violation of the accuracy of the electrode-tool and the stitched hole.

As a prototype, we accept the method [2].

In the proposed method, the preservation of the straightness and stiffness of long electrode electrodes-tools made of ductile metal materials, providing the required diameter and accuracy of the stitched hole.

A method of manufacturing a wire electrode includes processing the wire by fixing the wire in a movable and fixed racks and stretching the wire using a die, while first reducing its diameter from one end of the wire by the amount of allowance for installing the die by the length of the section required to install the die and fixing it end of the wire in a movable stand, after which they put a die on the end of the wire, the diameter of the hole of which is equal to the diameter of the end of the wire with a reduced diameter, fix this to nets in a movable stand, and the opposite end of a weakly stretched wire is fixed in a fixed stand, then tensile forces are applied to the ends of the wire not exceeding the tensile strength of the wire material, the beginning of the wire extension is recorded while passing a low-voltage direct current through it, and then released from fixing the end of the wire on a fixed stand and then pull the wire through the die, maintaining constant tensile forces on the wire.

The essence of the proposed method is illustrated by figures 1 and 2. Figure 1 shows the main elements of the installation for implementing the method and shows their interaction, figure 2 shows a device for moving the elements of the installation.

On the housing 1 (Fig. 1), a fixed stand 2 and a movable stand 3 of dielectric material are fixed. A wire 6 is fixed on fixed 2 and movable 3 racks with screws 4 and 5, having on the side of the movable stand 3 a section 7 of reduced diameter with a die 8 installed in the bracket 9 and fixed by a screw 10. The bracket 9 is fixed on the fixed rack 2 by a screw 11. For supply current to wire 6 with section 7 at the points of attachment of the wire to the posts 2 and 3 with screws 4 and 5, current leads 12 and 13 are installed from a low-voltage direct current source (not shown in FIG. 1). The movable stand 3 has a dovetail type guide element 14 with an adjustment plate 15 (FIG. 2). Under the strap 15, a support 16 of the stretching device for tensioning the wire 6 with section 7 is installed. The initial position of the support 16 is fixed with a screw 17. Between the rack 3 and support 16 there is a mechanism for tensioning the wire 6 with section 7, including (Fig. 1) an extension indicator 18 on a scale 19 of the wire 6 with section 7 under tension, the elastic element 20 calibrated on a scale of 19 to evaluate the force applied when stretching the wire 6 with section 7. Tension is carried out by a pneumatic cylinder 21 having a stroke of 22 not less than the length of wire 6 with section 7. Air x is supplied to the pneumatic cylinder 21 through the pipe 23 with a pressure gauge 24 and is removed through the pipe 25 with a valve 26.

The method is as follows: cut the wire 6 to a size equal to the distance between the outer surfaces of the racks 2 and 3.

Calculate or select from the reference the size of the allowance to obtain the optimal hardening on the surface of the wire 6 of a metal plastic material. The calculation can be performed according to the book [3], p. 116, formula 6.20.

At one end of the wire 6, a section 7 is made with a diameter smaller by twice the size of the allowance to obtain optimal cold work. The length of the section 7 is taken equal to the sum of the thicknesses of the die 8 and the width of the rack 3. The diameter of the hole of the die 8 is taken equal to the diameter of the portion 7 of the wire 6.

Take the stand 3 and the support 16 to the pneumatic cylinder 21, for which they open the valve 26 on the nozzle 25, release the support 16 from the pressure of the screw 17, supply air under pressure (control with a pressure gauge 24) through the nozzle 23 and the rod 3 with the support 16 is moved by the rod 22.

On the section 7 of the wire 6 is installed coaxially with the section 7 of the die 8, the end of the wire 6 is passed through the hole in the bracket 9, mounted on the rack 2 by a screw 11 with a current lead 12, the end of the wire 6 is fixed in the rack 2 mounted on the housing 1, by a screw 4, and die 8 in bracket 9 with screw 10.

Move the rack 3 with the guiding element 14 and the support 16 until the section 7 of the wire 6 is installed in the hole of the rack 3 until it stops in the die 8 and the wire 6 is weakly tensioned with the section 7, after which the section 7 and the current lead 13 are fixed with a screw 5.

The support 16 is moved, the elastic element 20 is compressed until the initial tension value is set according to the index 18 on the scale 19, after which the position of the support 16 is fixed with a screw 17 on the bracket 15, which regulates the clearance for moving the rack 3 and the support 16.

The tensile strength of the wire material is selected from the reference books and the obtained value is reduced by 20-25%. For the diameter of section 7, the longitudinal tension of the wire 6 is found. Air pressure is supplied through the pipe 23, which is controlled by a pressure gauge 24 by opening or closing the valve 26 on the pipe 25. Using a calibrated scale 19 with an elastic element 20, the pressure of the pressure gauge 24 is set, corresponding to the calculated force of the longitudinal tension of the wire 6 and section 7. A low-voltage current is supplied through the current leads 12 and 13 to the wire 6 with section 7 and the start of extension of the wire 6 with section 7 is fixed by pointer 18, then release give screws 4 and 17. Wire 6 with section 7 together with the stand 3, support 16, the stretching mechanism begins to move relative to the die 8, fixed with a screw 10 in the bracket 9, to obtain the required hardening (squeezing) of the surface layer on the wire 6. Then release fixing screw 5 of section 7 of wire 6, remove wire 6 from section 3 from section 3 with section 7, cut section 7.

An example of the application of the method:

It is necessary to manufacture a wire electrode tool for electrical discharge erosion in steel 45 holes with a diameter of 0.3 mm to a depth of 2 mm. As a tool, a wire is used from the material LS 59-1, recommended for drawing with the surface layer being fretted.

According to [3], the allowance for optimal hardening is 0.0183 mm.

According to [4] (p. 38; 41), the value of the lateral gap during electroerosive finishing is 9-10 microns for steels (by a diameter of 0.018-0.02 mm). Then the diameter of the wire to obtain a hole with a diameter of 0.3 mm, followed by calibration of the unworn section will be 0.28-0.282 mm. Therefore, the wire can be made according to the proposed method from a standard brass wire with a diameter of 0.3 mm by using a die with a hole diameter of 0.28-0.282 mm and a width of 1.5 mm. The tensile force (P) of a wire of this diameter with area F is

P = Kσ _in F,

where K is the safety factor for wire tensile strength (K = 0.75-0.8);

σ _in - tensile strength of brass, σ _in = 35 kgf / mm ² (according to the references σ _in = 30-40 kgf / mm ² );

.F is the cross-sectional area of the wire $$F=\frac{3,\mathrm{fourteen}\cdot 0,{28}^2}{\mathrm{four}}=0,0615\mathrm{<figure-callout\; id="2"\; label="m\; m"\; filenames="00000002.png"\; state="\{\{state\}\}">m\; </figure-callout>}{m}^{}{}^{{}_2}$$

.

Then P = 1.72 kgf (P≈17 N).

When preparing the wire for straightening, a section with a diameter of 0.28 mm and a length of 8 mm was formed by electrochemical etching on a workpiece with a length of 138 mm (width of the die 1.5 mm, width of the movable stand 6.5 mm).

Processing Modes:

The tensile strength of the wire 17 N; current strength 0.6 A; the heating time of the electrode wire 1-2 s; the time to obtain a wire electrode-tool with a working part length of 130 mm is less than 1 minute.

Results of use:

The measurement of the wire showed that the change in diameter was 0.002 mm, the bend was not more than 0.005 mm, and the stiffness increased by 8-10 times compared to un-mounted (non-riveted) wire. This made it possible to stably obtain holes of 0.3 ± 0.015 mm, which corresponds to the achievement of the goal.

Information sources

1. A.S. 252801. V.P. Smolentsev, N.I. Firsov, N.N. Feklistov, V.A. Lugovsky. The method of electrochemical processing of channels. 1969, Bull. No. 29.

2. EM Levinson Electroerosive processing of metals, Lenizdat, 1961 - 184 s.

3. Combined processing methods / Under. ed. V.P.Smolentseva. Voronezh: VSTU, 1996 - 168 p.

4. V.P. Smolentsev. The manufacture of a tool with a non-profiled electrode, M.: Mechanical Engineering, 1967 - 160 p.

Claims (1)

A method of manufacturing an electrode-wire, including processing the wire by fixing the wire in a movable and fixed racks and stretching the wire using a die, characterized in that first, at one end of the wire, its diameter is reduced by the allowance for the installation of the die and the length of the section required for installation dies and fixing this end of the wire in a movable stand, after which they put a die on the end of the wire, the diameter of the hole of which is equal to the diameter of the end of the wire with a reduced diameter, s this end is fastened in a movable stand, and the opposite end of a slightly stretched wire is fixed in a fixed stand, then tensile forces are applied to the ends of the wire not exceeding the tensile strength of the wire material, the beginning of the wire extension is fixed while passing a low-voltage direct current through it, and then released from fixing the end of the wire on a stationary stand and then pull the wire through the die, maintaining constant tensile forces on the wire.

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