Experimental Setup for Diamond Grinding Using Electrochemical InProcess Controlled Dressing (ECD) of Grinding Wheel

• Main Authors: M. A. Shavva, E. M. Zaharevich
• Format: Article
• Language: Russian
• Published: MGTU im. N.È. Baumana 2014-01-01
• Series: Nauka i Obrazovanie
• Subjects: diamond grinding; dressing of grinding wheel; electrochemical in-process controlled dressing
• Online Access: http://technomag.edu.ru/jour/article/view/542

<p>The most effective method for finish machining of hard-metals and alloys is to use the diamond grinding wheels for grinding. An application of diamond wheels significantly increases the employee output, reduces costs, and raises manufacturing efficiency with achieving the high performance properties of treated surfaces.</p><p>During grinding a working surface of diamond wheel wears out. It adversely affects the cutting capability of the diamond grains, and depending on the grinding conditions can occur through different mechanisms. Wear of diamond wheel causes distortion of its shape and reduces cutting properties. However, dressing of diamond wheels is a complicated and time-consuming operation in terms of manufacturing technique.</p><p>Methods to make dressing of diamond grinding wheel have different types of classification. Classification of dressing methods by the type of energy used is as follows: mechanical, chemical, electrophysical, electromechanical, and electrochemical. All these methods have their advantages and disadvantages.</p><p>Electrochemical method of dressing is the most productive and efficient. Electrochemical method comprises anode-mechanical dressing and electrochemical (electrolytic) one. The paper presents the electrochemical in-process dressing (ECD) and the electrolytic in-process dressing (ELID).</p><p>The source of energy, grinding a wheel with metal bond, and an electrode are necessary for providing ELID. The ELID consists of several stages. The first stage is preliminary electrolytic dressing of diamond wheel. The electrolyte is placed into the gap between the wheel and electrode. The bond of the wheel is oxidized. An insulating layer is formed. It reduces an electrical conductivity of the wheel and controls consumption of diamond grains, as well as polishes the surface of the work piece. Further, the insulating layer is destroyed. The cycle of dressing begins anew.</p><p>The ECD proceeds in the same way as ELID. However during the ECD-process there is no insulating layer formed. The oxides are washed out by electrolyte flow. The method provides a constant escape of abrasive grain. The grain escape reaches 100-120% of average diameter.</p><p>Adaptation of ECD on conventional grinding machine is performed. For this, the copper electrode is mounted to the grinding wheel. The electrolyte circulates in the gap between the wheel and electrode. The control system for the normal and tangential forces of process is also used during the adaptation.</p><p>The enterprise VNIIINSTRUMENT has designed a special experimental stand for diamond grinding. At this stand the ECD-dressing of diamond wheel with metal bond is implemented. This machine consists of a longitudinal support and a cross slide. Spindle of grinding wheel is set on the longitudinal support. A rotating speed of this spindle is about 50-3000 rev/min. A spindle of work piece is set on the cross slide. A rotating speed of this spindle is about 10-1000 rev/min.</p><p>The copper electrode is mounted on the spindle of grinding wheel. An area of electrode surface is 1/3 of the wheel area. The gap between the grinding wheel and electrode is about 0.3 mm. The electrolyte is placed in the gap.</p><p>The electrode is anode and the grinding wheel is cathode. Wheel and electrode are connected to the direct current source. When switching on the power source, the process of electrolysis begins. A bond of the wheel is oxidized and washed out. Waste of dressing is carried away with electrolyte.</p><p>The electrolyte leaves the zone of cutting. Next, the liquid gets into a special trough. Thereafter, the electrolyte enters the filter unit to have three steps of purification. The purified liquid is supplied to the pump, and then again enters the cutting zone.</p><p>ECD provides a large escape abrasive grain out of bond. It ensures that the cutting force is constant. The constant cutting force ensures the surface finish consistency, decreased surface roughness, and improved accuracy of work piece form.</p><p>Due to ECD, space for chips is formed between diamond grains. This allows the grinding wheel to avoid loading.</p><p>The stand solves the problem of electrolyte purification. This helps to avoid burn marks and defects during grinding. A maximum efficiency of process may be achieved by adjusting the modes of wheel dressing.</p><p>The ECD allows the use of nontraditional methods of grinding, including ductile mode grinding. However, for this it is necessary to apply the special kinematic scheme of grinding.</p>