RU2268119C1 - Method for automatic control of electrically conducting binder abrasive wheel cutting capability - Google Patents

Abstract

FIELD: abrasive working, possibly electrochemical dressing of abrasive wheels on base of electrically conducting binders at grinding different materials.

SUBSTANCE: method comprises steps of electrochemically dressing wheel at working part due to automatic control of dressing process by changing intensity of electric current at dressing in range 0.2 - 0.6 A/sq.cm while changing cutting process power during grinding process.

EFFECT: possibility for controlling cutting capability of abrasive wheel with electrically conducting binder, enhanced grinding quality, lowered consumption of wheel.

2 dwg, 1 ex

Description

The invention relates to electrophysical and electrochemical processing methods, in particular, to a method for electrochemical dressing of abrasive wheels on conductive bonds during grinding of various materials.

Known methods for restoring the cutting ability of an abrasive wheel on a conductive bond by means of EDM editing.

The method of electroerosive dressing of diamond circles on metal bundles [1] is carried out in two stages (roughing and finishing dressing), at the first stage, dressing is carried out in the electric arc mode U = 41-50 B, I = 100-150 A. The process is accompanied by the formation of a build-up of erosion products on the surface of the circle, on the second - grind the resulting growth from erosion products around at U = 10-25 V, I = 10-30 A.

The disadvantage of this method is that the restoration of the cutting ability of the wheel is not carried out automatically and to complete the dressing it is necessary to interrupt the processing of the part, which leads to a significant decrease in productivity, and the process proceeds at unreasonably high dressing currents (100-150 A), which leads to a large abrasive wheel wear.

A method for controlling the cutting ability and dressing of a grinding diamond wheel on a metal bond [2], in which a control beam is fed to the working surface of the wheel and the reflected beam parameters are fixed, dressing is carried out by the electrochemical method using an additional electrode tool, and dressing modes are regulated depending on the parameters reflected beam. To prevent electrolyte from entering the light stream, jets of optically transparent gas are fed in the direction of the working surface.

The disadvantage of this method is the design complexity, which leads to the difficulty of its use, also a change in the luminous flux leads not only to a change in the state of the working surface of the circle, but also to many other factors that are difficult to foresee.

The closest method of the same purpose to the claimed method in the group of inventions according to the totality of features is a method for automatically controlling the cutting ability of the grinding wheel by the electroerosive method, in which during grinding the opening depth is controlled and the bond is periodically removed over the entire cutting surface of the wheel in accordance with the wear of abrasive grains [3].

The technical result of the invention is the provision of automatic control of the cutting ability of the abrasive wheel on a conductive bond by means of its electrochemical dressing in order to improve the quality of the treated surface and reduce the specific consumption of the wheel with a combined processing method.

The specified technical result in the implementation of the invention is achieved by the fact that in the known method for automatically controlling the cutting ability of an abrasive wheel on a conductive bond, electrochemical dressing of the circle is used. The peculiarity lies in the fact that they carry out the electrochemical dressing of the abrasive wheel, and the process of electrochemical dressing is controlled by changing the dressing current density within 0.2 ... 0.6 A / cm ² when the cutting power changes during grinding.

Figure 1 is a schematic diagram of a method for automatically controlling the cutting ability of an abrasive wheel on a conductive bond with automatic control of the process of its electrochemical dressing, figure 2 is a graph of the dependence of cutting power on the density of the dressing current.

The method is implemented as follows.

When connecting the main drive motor of the machine to the network, one of the phases is shunted. The workpiece 3 is ground with an abrasive wheel 4. As the cutting ability of the wheel worsens, the cutting power increases and, consequently, the current in the electric circuit of the engine increases. At a certain magnitude of the current strength, an electric signal is supplied to the control unit 1, including an electrochemical straightening circuit of the circle. From the source of the technological current to the interelectrode zone, circle 4 - cathode 2, voltage U = 4 ... 6 B is supplied. Electrolyte from the tank is also supplied to this zone. In this case, electrochemical processes occur in the interelectrode space at a dressing current density i _pr = 0.2 ... 0.6 A / cm ² . After dissolving the layer formed from the sludge and chips, and partially the ligament of the wheel, the cutting ability of the wheel returns to normal and, therefore, the cutting power decreases. After that, the editing chain is automatically disabled, and the process repeats.

The nominal value of the cutting power and current density of the dressing i _{pr is} set experimentally for each grade of the circle and grade of the processed material. The criterion for choosing the optimal value can be taken as the performance and specific consumption of the circle.

The method can be implemented for various types of circles on a conductive bundle. It allows you to automatically carry out the work of the circle in the self-sharpening mode, while there is no need for constant monitoring of the state of the working surface of the circle. Due to the stabilization of the cutting ability, the quality of the machined surface of the workpiece and the processing productivity with a minimum specific circle consumption increase significantly.

An example implementation of the proposed method.

The effectiveness of the method was investigated on a universal grinding machine model 3D642E, modernized for the processes of combined processing. Grinding of hard alloys T5K10, VK8, T15K6, high-speed steels R6M5, P18, alloy steel 9XC with circles АСВ 125 / 100М04-100%, АСВ125 / 100МО13-100%, АСВ125 / 100МO16 was performed. A water-based electrolyte (NaNO ₃ - 3%, NaNO ₂ - 1%, Na ₂ CO ₃ - 0.5%) was supplied to the treatment zone with a flow rate of 0.5 l / min. Studies have shown that stabilization of cutting power occurs at a dressing current density i _pr above 0.2 A / cm ² (Fig. 2), therefore, the current density of 0.2 A / cm ² corresponding to a power of N = 400-350 W is taken as a criterion while ensuring a minimum specific consumption of the circle. With an increase in the dressing current density above 0.6 A / cm ² , intensive electrochemical dissolution of the bundle of the circle occurs, which leads to a significant increase in the specific consumption of the circle.

INFORMATION SOURCES

1. Application No. 4857511/08 MKI B 23 N 7/00, 06/15/1994.

2. Application No. 4834658/08 MKI B 23 N 5/06, 04/30/1995.

3. Application No. 3778928/08 MKI B 23 H 7/00, 08/09/1995.

Claims (1)

A method of automatically controlling the cutting ability of an abrasive wheel on a conductive bond, including automatic regulation of the dressing process of the abrasive wheel, characterized in that they carry out electrochemical dressing of the wheel, and the process of electrochemical dressing is controlled by changing the dressing current density within 0.2 ... 0.6 A / cm ² when changing the cutting power during grinding.

Images