CS201227B1 - The way of precision electrochemical machining, especially of complex shaped workpieces - Google Patents

Abstract

The aim of the solution is to increase the shape accuracy of the machined shapes of the plates. The stated aim is achieved by a procedure, the essence of which is that during finishing machining, the tool is moved at a speed of v = (0.80 to 0.95) . v0, where v0 is the finishing machining speed when manufacturing the active surface of the tool by the reverse polarity method.

Description

The invention relates to a method for extending the life of a nitrate electrolyte used in an electrochemical process. machining.

In the electrochemical machining of chromium-containing materials, but also tungsten and wax moths, these metals pass into the electrolyte in the form of soluble compounds. After exceeding a certain concentration of these compounds, in particular chromium-containing anions, the machining process is slowed down until it is virtually complete. Anions have become a technological pollutant. At the present time, the entire working electrolyte volume must be replaced and the toxic electrolytes disposed of and discarded in this waste electrolyte; and chemicals used in the preparation of the working electrolyte, such as sodium nitrate. The direct disposal of process pollutants in the electrolyte working circuit is not carried out, since all the methods used to remove soluble chromium, tungsten and molybdenum so far introduce anionic process pollutants, most often sulphates, into the electrolyte.

This technical problem solves the method of extending the life of the nitrate electrolyte for electrochemical machining according to the invention, which is based on the addition of lead nitrate to the electrolyte.

By extending the lifetime of the electrolyte according to the invention, a new effect consists in saving the active component of the electrolyte - sodium nitrate. protraction

201 227

201 227 according to the invention also saves operating and investment costs for detoxication and disposal of waste electrolytes, because prolonging the life of the electrolyte eliminates the formation of waste electrolytes by increasing the concentration of technological pollutants.

The principle of the invention is explained in an exemplary embodiment.

Example

In a medium electrochemical machine tool, the working electrolyte is a 15% sodium nitrate solution. The working electrolyte volume is 4 m \. For machined steel *, the concentration of chromium as a technological pollutant of 0.2 kg Cr in 1 m \ is critical. Thus, after collection of the material containing 0.8 kg of chromium, the entire working electrolyte volume should be replaced and the waste electrolyte disposed of 0.8 kg of soluble toxic chromium and 600 kg of sodium nitrate used in the preparation of the electrolyte.

In order to prolong the life of the electrolyte according to the invention, after reaching a concentration of 0.1 kg Cr in 1 m m, an aqueous solution of lead nitrate containing

2.5 times the amount of analytically detected chromium. The resulting chromium lead precipitate is practically insoluble and is removed from the electrolyte when the sewage sludge is separated. Such elongation is repeated to prevent technological pollutants from reaching the critical concentration.

Claims (1)

OBJECT OF THE INVENTION Method for extending the life of a nitrate electrolyte over electrochemical machining, characterized in that lead nitrate is added to the nitrate electrolyte.