Determination of wheel life and the reason of damage

In the grinding process, due to wear of the wheel itself, constantly changing the wheel face state. With the extension of the grinding time, the ability to wheel cutting down all kinds of grinding defects continue to appear, the grinding process can not continue. In this case, you must trim wheel, grinding return to normal state. Grinding wheel in real time between the two dressing called wheel life. Wheel of life is an important factor affecting the grinding effect, especially particularly important for form grinding.

Determining wheel life:

It is generally based on various phenomena of wear after grinding wheel produced by Face, by observation and tests carried out, after the grinding wheel wear phenomena arising are: self-excited vibration grinding process, the surface of the workpiece regeneration chatter; mill cut the noise increases; the workpiece surface grinding burn occurs; grinding force sharply increases or decreases; loss of precision grinding; grinding the surface roughness increases.

Wheel wear and dressing, which affect the effective contour grinding wheel peripheral surface of the processing, which is the systematic error, especially when you want to fine-precision grinding wheel dressing, dressing program set specifically to the grinding wheel can be longer maintain accurate time within the outline.

Wheel wear causes:

A, abrasion wear

When severe abrasive wear, obvious in abrasive wear flat top surface, the flat surface of the wheel. At this time the total area of the cutting edge wear increases, increased friction, the cutting edge is difficult to cut into the workpiece surface. However, high hardness grinding wheel, resulting in not timely produce grains and broken off. If you continue to use, will make grinding force and grinding heat up to a significant increase, and significant vibration and noise can not be effectively removed material, then it must be trimmed to the wheel. This wear typically occurs at low abrasive hardness, high hardness and abrasive grinding wheel size too small, and high tensile strength of the workpiece material situation. This is the most common cause of machining in general steel under ordinary conditions of grinding wheel life ends.

B, oxidative wear

Common abrasives have oxides, carbides and nitrides. Oxide abrasive stable in air, other abrasive surface oxidation occurs at high temperatures, seventeen gradually consumed.

C, diffusion wear.

It refers to abrasive wear when the material is in contact with at a high temperature, mutual diffusion of elements diamond wheel surface causing abrasive wear and tear resulting weakening. Mutual diffusion of elements between the two materials is closely related to the chemical composition of the material due to the diffusion of carbon in the diamond abrasive dissolved iron is greater than the capacity of boron nitride abrasive elements dissolved in the diffusion capacity of iron, it is not appropriate diamond grinding wheel grinding steel material.

D, breakage by thermal stress.

Grinding process, the abrasive working surface temperature rose to the moment, at the wheel and the grinding liquid quenching effect, the same as its cold cycle frequency of the wheel speed, thereby forming a large alternating on the surface of the abrasive particles thermal stress, the abrasive surface cracking broken. Thermal stress breakage parameters depends on thermal coefficient of linear expansion and grinding fluid performance abrasives. Thermal conductivity, the lower the coefficient of linear expansion. The larger linear expansion coefficient, the better the performance grinding fluid cooling, the thermal stress, the more easy to make thermal shock cracking broken grains. All kinds of abrasive thermal conductivity of the order of good and bad, diamond, cubic boron nitride, silicon carbide, corundum.

E, plastic wear.

At high temperature grinding, abrasive wear due to plastic deformation. Plastic wear depends mainly on hot hardness of the workpiece material. When the grinding wheel if the chips in hot hardness abrasive grains on the rake face is larger than the contact area of the hot hardness is plastically abrasive wear.

Several more causes of wheel wear. Depending on the abrasive, workpiece material and ground conditions, causing the main reason for wheel wear will be different. Therefore, a reasonable choice and the accuracy of wheel dressing wheel will greatly affect the accuracy of the workpiece contour. Therefore, the need for timely to the grinding wheel for trimming. In addition, after the initial installation of the wheel needs to be trimmed, the essence of Dresser is shaping and grinding wheel dressing. Plastic is a trace grinding wheel cutting, grinding wheel to achieve the desired geometry requirements, and fine crushing abrasive tip to form sharp sharpening. The dressing is to remove the binding agent between the grains, so that between the abrasive particles have a certain chip space, and abrasive edge protruding beyond the binding agent forms a cutting edge, depending on the abrasive wheel and binding agent, take dressing different methods.

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