RU2456139C1 - Cathode for electrochemical machining - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal working, particularly, to equipment for electrochemical machining of large-size thin-wall parts of the type of solids of revolution. Cathode comprises working element with shape repeating that of machined surface. Said working element is arranged on the rod and rigidly jointed therewith. Axis of symmetry of working element is aligned with the rod rotational axis. Note here that said working element part represents a plate with width at its every point satisfies the following conditions: b₁/V₁=b_n/V_n=const, where b₁, b_n are plate width at different points, V₁, V_n are linear velocities at said points.

EFFECT: higher quality of machining.

1 tbl, 3 ex, 6 dwg

Description

The invention relates to the field of metalworking, namely to the electrochemical processing of large-sized thin-walled parts such as bodies of revolution.

For surface treatment of parts such as bodies of revolution, sectional cathodes are used (Orlov V.V., Chugunov BN / Electrochemical shaping - M .: Mashinostroenie, 1990, p.188-189).

The use of sectional cathodes for processing large parts is problematic, because the design of the sectional cathode is cumbersome, difficult to manufacture and operate.

As a prototype, a tubular-contour cathode was selected, the working element of which repeats the profile of the surface being machined and is made of a conductive (copper or steel) tube. The ends of the tube are rigidly fixed in the cathode body (Vestnik Mashinostroeniya No. 11, 1975). During processing, rotation is reported to the cathode.

The disadvantage of this cathode is the low accuracy and low quality of the machined surface due to uneven metal removal, since areas located at a closer distance from the axis of rotation are processed faster than remote ones, due to the longer interaction time of the cathode with the treated surface.

The objective of the invention is to improve the quality of processing by achieving uniform removal of metal over the entire area of the processed surface.

The problem is solved in that in the cathode for electrochemical processing, containing a working element, the profile of which follows the shape of the workpiece, mounted on the rod and rigidly connected to it, while the axis of symmetry of the working element coincides with the axis of rotation of the rod, according to the invention, the working element in part , repeating the shape of the processed surface, made in the form of a plate, the width of which at any point corresponds to the condition: b ₁ / V ₁ = b _n / V _n = const,

where b ₁ , b _n - the width of the plate at various points,

V ₁ , V _n - linear speeds at these points.

The invention is illustrated by drawings.

Figure 1 shows the cathode for electrochemical processing of a hemispherical part in section.

Figure 2 - cathode in figure 1, a top view.

Figure 3 presents the cathode for the electrochemical processing of parts of a conical shape in section.

In Fig. 4 - cathode in Fig. 3, a top view.

Fig. 5 shows a cathode for electrochemical processing of a parabolic shaped part in section.

In Fig.6 is the cathode of Fig.5, a top view.

The cathode for electrochemical processing consists of a working element 1 and a rod 2, rigidly connected to each other (Fig.1, 3, 5). The axis of symmetry of the working element coincides with the axis of rotation of the rod. The working element is a plate, the profile of which repeats the profile of the workpiece. The width of the working part of the plate is determined from the condition b ₁ / V ₁ = b _n / V _n = const, i.e. the ratio of the width of the working part of the plate at any point to the linear velocity at this point is a constant value.

Example 1: To process the hull part of the aircraft, made in the form of a hemisphere with a radius Rd = 245 mm of aluminum alloy AMg6, a hemispherical cathode with a radius of Rk = 244 mm was used (Fig. 1). The radius of the cathode was determined as the difference between the radius of the part and the gap between the cathode and the part. The cathode material is OT-4 titanium alloy. The width of the working element - the plate was calculated based on the condition b ₁ / V ₁ = b _n / V _n = const. Knowing that the cathode during rotation will perform rotation with a given number of revolutions (2 rpm), according to the formula ω = πn / 30, we calculate the linear velocity V = ωR for arbitrary points 1, 2 of the plate through the angular velocity ω (Fig. 2) . Point 1 of the working element has a radius of rotation R ₁ = 100 mm, point 2 - R ₂ = 210 mm. The angular velocity of the working element is equal to ω = (3.14 · 2/30) = 0.21 sec ^-1 , respectively, the linear speeds of points 1, 2 are equal to V ₁ = 21 mm / s, V ₂ = 44 mm / s. We take the width of the working element at point 1 b ₁ = 5 mm, from the ratio b ₁ / V ₁ = b ₂ / V ₂ calculate b ₂

b ₂ = b ₁ · V ₂ / V ₁ = 10.47 mm. We accept b ₂ = 10 mm.

The electrochemical treatment was carried out in a 15% aqueous solution of ammonium nitrate NH ₄ NO ₃ at a current density of 12 A / cm ² . Processing time 90 min.

Example 2: For processing the hull part of the aircraft, having the shape of a hollow straight truncated cone with Rd max = 252 mm and Rd min = 150 mm from aluminum alloy AMg6 (Figs. 3, 4), a cathode was used, the working element of which has a conical shape with Rk max = 251 mm and Rk min = 149 mm. The cathode material is OT-4 titanium alloy. The part of the cathode that does not repeat the shape of the surface being machined is arbitrary and serves to ensure rigidity of the connection with the rod and symmetry of the working element relative to the axis of the rod. The calculation of the plate width is carried out analogously to example 1. The composition of the electrolyte and the processing modes are similar to example 1.

Example 3. To process the details of an aircraft having the shape of a truncated hollow paraboloid of revolution made of aluminum alloy AMg6, a cathode was used, the working element of which in the part repeating the shape of the surface being machined is made in the form of a plate, the width of which at any point corresponds to condition b ₁ / V ₁ = b _n / V _n = const. (Fig. 5, 6). The part of the cathode that does not repeat the shape of the surface being machined is arbitrary and serves to ensure the rigidity of the connection with the rod and the symmetry of the working element relative to the axis of the rod. Part dimensions Rd max = 160 mm and Rd min = 120 mm. The cathode dimensions Rk max = 159 mm and Rk min = 119 mm. The cathode material is OT-4 titanium alloy. The composition of the electrolyte and processing conditions are similar to example 1.

The results of the experimental verification of the proposed cathode, presented in the table, show that its use reduces surface roughness and deviation from the shape.

Compare devices Surface Roughness (Ra) Deviation from the form, mm The temperature of the solution (T), ° C Prototype device 2.5 0.06-0.09 20-35 Proposed device 2 0,025 20-30

Claims (1)

A cathode for electrochemical processing, containing a working element, the profile of which follows the shape of the surface being machined, mounted on the rod and rigidly connected to it, while the axis of symmetry of the working element coincides with the axis of rotation of the rod, characterized in that the working element in the part repeating the shape of the processed surface , made in the form of a plate, the width of which at any point corresponds to the condition:
b ₁ / V ₁ = b _n / V _n = const,
where b ₁ , b _n - the width of the plate at various points,
V ₁ , V _n - linear speeds at these points.

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