Experimental Investigation of the Temperature and Accuracy Characteristics of Double-Sided Face Grinding Machine

Bulletin of Belgorod State Technological University Named After. V. G. Shukhov

2021

The paper presents an analysis of thermal processes in the bearing system of a double-sided face grinding machine. Experimental data on temperatures and displacements obtained when the machine is idling and when imitating the grinding process with the help of electric heaters of various powers are used for analysis. The performed studies have shown that thermal deformations of double-sided face grinding machines with an arc trajectory of workpiece feed occur in a wide range in magnitude and direction. It can violate the main requirement for the precise operation of the machine - the symmetry of processing conditions at both ends of the workpiece. From the experiments, the absolute value of the non-parallelism of the grinding wheels after three hours of operation is established; it is almost twice the value of the removed allowance. Analysis of the kinetic change in the deformations of the supporting system of the machine tool during operation under thermal load shows that as it warms up, the relative position of the grinding wheels gradually changes from the state "wider at the bottom" to the state "narrower below". This leads to a spontaneous change in the dynamic tuning of the technological system and a corresponding change in the processing accuracy. Changes in the dynamic tuning of the technological system with varying intensity continue throughout the entire operating time of the machine.

Specific Features of Thermal Processes in Double-Sided Face Grinding Machines

Bulletin of Belgorod State Technological University Named After. V. G. Shukhov

2021

Simulation of the Thermal Deformation Behavior of Double Sided Face Grinders

Bulletin of Belgorod State Technological University Named After. V. G. Shukhov

Воронин

2022

Self Cite

The paper presents the result of modeling the thermal deformation behavior of the bearing system of a double-sided face grinder. Two modes of its operation is considered: idling and working strokes. Spindle bearings, heat fluxes from coolant, and heat fluxes from motors are considered as the main heat sources. The preliminary values of heat and convective fluxes are assigned according to well-known methods used in engineering calculations of machine tools. Refinement of the values of heat and convective fluxes is carried out according to the results of experimental values of temperatures and temperature displacements. In the thermal model, convective heat transfer is assigned to 450 surfaces. Heat flows are assigned to 161 surfaces. The simulation is run in Ansys for 6 hours of machine tool operation. Ansys uses a ten-node Solid227 element as a typical finite element. The problem of thermoelasticity is solved in a related setting. The error in modeling thermal processes did not exceed 0,5 degree, the error in modeling temperature displacements did not exceed 5 microns. The results of computer simulation confirmed the relative experimental positions of the left and right grinding wheels characteristic of this range of machines. At idle, the relative position of the grinding wheels represented the state «wider at the bottom», and during the working stroke, the state «at the bottom narrower» is recorded. The illustrations of the FEM model and contour plots for the temperature field and temperature displacements of the bearing system of the machine tool for two modes of its operation are presented.

Experimental Measures to Improve Thermal Characteristics in Double-Sided Face Grinding Machines

Bulletin of Belgorod State Technological University Named After. V. G. Shukhov

Воронин

2022

Self Cite

The results of full-scale and computational experiments to improve the thermal characteristics of the machine tool are presented. This can lead to a decrease or achieve symmetry of the resulting thermal deformations. The implementation of four schemes for the redistribution of heat fluxes is considered: the heat flux of the main electric motors, directed under the protective casing of the drive pulley, and the heat flux of the belt drive are removed through special windows in the casing to the environment; jointly with the first scheme of redistribution of heat fluxes, cooling of the ends of the grinding headstocks is provided with the help of an impeller fixed on each drive pulley; jointly with the second scheme, heat flux isolation from the left and right electric motors is provided; heating the ends of the machine tool bed. The first three schemes are implemented at idling of the machine tool; the fourth scheme is implemented when the machine is operating under thermal load. The joint implementation of three schemes makes it possible to reduce the displacement of the right circle at idle by 1.5 times, the left circle practically did not move. The test of the first three circuits during the operation of the machine tool under a thermal load does not reveal significant changes in the thermal characteristics. The implementation of the fourth heat flux redistribution scheme help to compensate for thermal deformations from heating in the central part of the bed and reduce changes in the angular position of the grinding wheels.