RU2261792C2 - Method of cleaning fluid in mechanical strengthening - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: method comprises wetting the conducting granules of fluid with weak-conductive liquid and applying voltage. The value of the voltage should be higher than that required for the onset of current in the fluid-blank circuit and lower than that of the beginning of shorts in the circuit. The weak-conductive fluid is made of industrial water.

EFFECT: improved cleaning.

1 cl, 1 dwg, 1 ex

Description

The proposed method relates to the field of engineering and can be used to remove contaminants from conductive granules of the working medium during mechanical hardening of metal billets.

A known method of cleaning grinding wheels from pollution by ultrasound, which has a positive effect when applying ultrasonic vibrations to a fluid that fills the entire space between the tool and the workpiece or by supplying vibrations directly to the tool with a small mass [1].

The disadvantages of this method include the inability to carry out the hardening operation in a bath with a liquid and a significant increase in the required time for washing the working medium relative to the time between the collisions of the granules and the workpiece, which leads to a change in the surface properties of the working medium and a violation of the uniformity of hardening of the surface layer of the workpiece.

There is also a method of cleaning, combined with processing in a liquid medium [2], a method of washing granules in the process of feeding them to the workpiece in an electric field. The disadvantages of this method include the participation of an excess amount of liquid, which, depending on the distance to the surface of the workpiece, changes the impact energy and does not allow to achieve uniform hardening of the surface.

Closest to the claimed method is a method of hardening with application to the working medium in the form of a liquid and granules of electric current and periodic washing of the working medium with chemically active solutions [3]. The disadvantages of the method include the uneven removal of contaminants and only from the surface of the granules, which leads to uneven hardening of the surface with a small degree of hardening.

The invention is aimed at obtaining the required hardening and stabilizing the degree of hardening of the surface layer of metal billets. This is achieved by the fact that before hardening and periodically during the hardening process, the conductive granules of the working medium are moistened with a weakly conductive current with a liquid, for example industrial water, the voltage supplied to the working medium is maintained not lower than the beginning of the passage of current through the working medium-blank circuit and not higher than the beginning of short short circuits in the same circuit.

The drawing shows a diagram of the method.

The working medium 1 in the form of granules, for example balls, is supplied to the surface of the workpiece 2. An alternating or constant (direct polarity) current is supplied through the electrodes 3 from a current source (not shown) having an electric circuit including a voltage regulator 4 and an ammeter 5.

The method is carried out as follows: a weakly conducting liquid, such as industrial water, is supplied to the working medium 1, after which a moist conductive layer remains on the surface of the granules. The current source is turned on and the regulator 4 increases the voltage from zero at the electrodes 3 until a positive current value appears on ammeter 5. The feed is turned on to move the working medium 1 with the liquid to the workpiece 2. Due to the passage of current through the electrodes 3 and the working medium 1, a gas is formed on the surface of the liquid on the surface of the gas (at the cathode - hydrogen), which removes the processed products from the surface of the granules, amount which, according to [3], p.142 reaches several grams per minute, and the elimination of such products helps to maintain stable impact energy and the degree of hardening of the surface. The voltage regulator limits the upper voltage limit at the beginning of the breakdown of the gap between the granules and the workpiece 2, the excess of which can cause a violation of the hardening process. The onset of short circuits in the form of short-term breakdowns is visually observed by an ammeter in the form of current surges. The current can be used as unipolar, in which the working medium 1 has a negative pole, and alternating, in which the cleaning of the working medium 1 occurs during the supply of negative half-wave current to the medium 1. The removal of processing products unrelated to medium 1 occurs by periodically watering a weakly conducting liquid fluid, for example, process water, onto the working medium 1, which is subsequently purified from the processed products by one of the known methods. The presence of constantly cleaned working medium 1 without excess liquid provides the required degree of hardening over the entire surface of the workpiece.

An example of using the method.

Flat samples made of 40KhNMA steel were hardened using metal balls with a diameter of 3 mm and a frequency of 33 Hz for 1 minute on a vibration stand with a voltage supply from the generator 4.5-5 V, at which the current was 1.3-1.8 A. wetted with industrial water by spilling with a period shorter than the termination of the passage of current (about 10 seconds). After testing the microhardness of the samples, the degree of hardening of the surface layer was 18–20%.

Under the same hardening regimes using the solid and liquid phases as the working medium, as proposed in / 3 /, the degree of hardening varied from 3 to 15% with an optimum degree of hardening of 18-22%.

SOURCES OF INFORMATION

1. Electrophysical and electrochemical methods of processing materials. T.1 / Ed. V.P.Smolentseva. - M.: Higher School, 1983, 247 p.

2. Kuzovkin A.V. Combined processing with an unbound electrode. - Voronezh: Publishing House of the Voronezh State University, 2001.180 s.

3. Babichev A. P., Babichev I. A. Fundamentals of vibration technology. - Rostov-on-Don: DSTU, 1988.624 s.

Claims (2)

1. A method of cleaning the working medium in the form of conductive granules during mechanical hardening of metal billets, comprising applying an electric voltage to the working medium, characterized in that before the start of hardening and periodically during the hardening process, the conductive granules of the working medium are wetted with a weakly conductive current with liquid, while the magnitude of the electrical voltage support not lower than the beginning of the passage of current through the electric circuit "working medium-billet" and not higher than the beginning of short circuits in the same circuit. 2. The method according to claim 1, characterized in that industrial water is used as a weakly conductive fluid current.