| Popis: |
The work deals with the definition of conditions for rational use of the grinding process at the finishing operations, the thermal stress reduction due to the establishment of optimal grinding conditions and characteristics of the abrasive disk, the application of new kinematic grinding schemes and elimination of intense friction of the disk bond with the material being processed which is the main source of temperature defects on the surface being processed. A mathematical model for determining the temperature of cutting at grinding with due regard to temperature change laws in the allowance layer being removed for definite depth of heat penetration into the surface of the workpiece has been developed. A problem in cutting infinitely thin adiabatic rods (thought of as the allowance to be removed) with an abrasive disk, a new analytical dependence for determining the cutting temperature with regard to contact time of the abrasive disk with the adiabatic rod was obtained. It has been shown that a 10 times decrease in conventional cutting stress resulted in proportional maximum cutting in temperature reduction during grinding, it corresponding to the practical data. Knowing the cutting temperature change dependence on adiabatic rod heating time, cutting temperature for any grinding scheme can be determined, the contact time of the grinding wheel with the adiabatic rod can be set as well as the speed of the heat source movement speed along the adiabatic rod. Examples of cutting temperature calculation for the specific conditions of grinding have been given. It was found that in the course of time the temperature of cutting at grinding increases continuously, approaching the value of the energy balance, that is equal to the ratio of the conventional cutting stress to the specific heat multiplied by the density of the material being processed. The terms of the cutting temperature reduction at grinding have been laid out and practical recommendations have been made |
