SU1692779A1 - Method for electrochemical machining of inner cylindrical surfaces - Google Patents

Abstract

The invention relates to electrochemical processing, in particular to the treatment of heat exchange enhancers of power plants. The purpose of the invention is to improve the accuracy of the formation of intensifiers in the form of spherical holes on heat exchange surfaces. The processing is carried out by an electrode tool, the sweep on the plane of the working areas of which is coaxial to a ring of width A, each of which consists of an outer nonconductive ring and an inner conductive ring, and the width of 5t conductive rings is determined from the ratio (5t A ( 1- - hx: h), where h is the arrow of the segment of the hole being processed, hx d- Vr2 - x 2 - the arrow of the segment of the hole being processed with a contracting chord equal to the average radius of the corresponding ring, d is the radius of the sphere of the hole being worked, x - medium Nij radius of the ring. 3 yl. CO

Description

This invention relates to the field of ECM. in particular, to the treatment of heat exchange intensifiers of power plants.

The aim of the invention is to improve the accuracy of the formation of intensifiers in the form of spherical holes on the heat exchange surfaces.

Figure 1 shows the electrode processing tool, section; figure 2 - scan of the working area of the electrode-tool; on fig.Z - hole, geometric parameters.

The electrode tool consists of a conductive rod 1 mounted on a rod 2 onto which a front base 3 is fitted with holes for supplying electrolyte 4. A back base 5 is attached to rod 1 with holes for draining electrolyte 6. On the surface of rod 1

The working sections 7, located with a step h relative to each other along the rod, consisting of isotope-conducting 8 and non-conducting 9 zones, non-working surfaces of the rod are covered with insulation 10. The basement of the tool electrode is performed on the surface of the workpiece 11.

The conductive 8 and non-conductive 9 zones of the working sections 7 are formed by etching non-conductive zones 9 by photoexposing a pattern, followed by pouring them with epoxy glue and cleaning the entire surface of the working sections 7. The working sections of the electrode tool non-working surfaces, anterior and posterior base elements with holes for pumping electrolyte, which are swept onto the plane

is coaxial rings of equal width A, made in the form of coaxial inner conductive and outer non-conductive zones, and the width of the conductive zones is according to the formula

5t A (1-Ј),

where h is the arrow of the segment of the hole being processed;

hx r-vrr2 x2 is the arrow of the segment corresponding to the average radius of the ring in question;

g - the radius of the sphere of the hole;

x is the average radius of the considered ring.

The method is carried out as follows.

I The electrode tool is inserted into the hole being machined and fixed in the heat where the spheroidal holes should be obtained, and the location of the working sections 7 on the surface of the stitch 1 corresponds to the desired location of the holes on the surface of the workpiece 11. the electrolyte between the workpiece 11 and the rods 1, after which the working voltage is applied to them, and the electrode-tool becomes the cathode. After a period of time required for the formation of the wells, the operating voltage is removed, the supply of electrolyte is stopped. The electrode tool moves to the Raw surface area and the Process repeats. Thus, spherical wells are formed along the entire length of the billet.

Processing in this way provides regulation of the reduced current density jn, defined as

I-- 4

where j is the density of the current passing through the conductive zones of the work areas entering the area of the surface to be treated that corresponds to a specific ring. With an equal width of the rings with increasing distance from the center of the working section, the width of the conductive zone decreases according to a ratio of 5m A (1 - Tr), respectively, the width of the nonconductive zone increases. Therefore

the reduced current density, which arrives at the area of the surface to be treated, corresponding to the specific ring of the working section of the electrode-tool, decreases from the center to the edge of the working area. Accordingly, local removal on the surface of the workpiece will be reduced. This law of variation in the width of the conductive zone of the rings provides

changes in the current density, resulting in the formation of a spherical profile of the hole. The adherence of the conductive zone to the inner radius of the rings ensures the absence of removal of the material of the workpiece outside the area to be machined.

the roughness of the surface of the hole, taking into account the influence of edge effects, with increasing And the accuracy of treatment decreases, the roughness of the surface of the hole increases.

Claims (1)

Invention Formula The method of electrochemical machining of internal cylindrical surfaces with an electrode-tool consisting of working sections and non-working isolated areas and moving along the surface being treated, characterized in that, in order to improve the accuracy of forming heat-transfer intensifiers in the form of spheroidal holes, the treatment is carried out with an electrode-tool, the sweep on the plane of the working sections of which is coaxial rings of width A, each of which consists of an outer non-conductor Of ring and the inner conductive ring, and the width of the 6 conductive rings is determined from the ratio 5t-A (1-Ј), where h is the boom of the well segment; hx g - - boom of the segment of the hole being machined with a contractile chord equal to the average radius of the corresponding ring; g - the radius of the sphere of the treated hole; x is the average radius of the ring. 2 4 / 7/0 S f / b ////////// /