Improving the efficiency of internal grinding based on the analysis of the rigidity of the technological system

Introduction

Internal grinding & ndash; grinding of surfaces of cylindrical, conical and shaped holes on universal and special machines.  Internal grinding is used when it is necessary to obtain high-precision holes (6...9 quality) with surface roughness (Ra = 1,6...0.16 microns). The internal grinding area covers all types of production. It is used for processing holes in bushings, bearing rings, engine cylinder liners, parts of hydraulic and pneumatic equipment, machine spindles, etc.

Internal grinding is most often used when machining precise holes in hardened parts or parts made of highly hard and difficult to process materials, precise holes with a rough surface, for example, with a recess, with keyways and slotted grooves, as well as precise holes of large diameters (over 100 mm), when the deployment can not provide the required accuracy.

1. Relevance of the topic

Internal grinding has a number of features, among which it is particularly important to highlight the high requirements for rigidity and vibration resistance of spindle devices of grinding machines associated with small machined diameters, and, in some cases, with a large length of holes. Due to the low rigidity of the spindle Assembly to obtain the necessary accuracy and quality used, as a rule, 20-30 or more double strokes nursing. In this case, the tool is pressed close to the set cutting depth, and only some individual grains of the circle plastically deform the roughness of the processing [1]. This leads to the fact that the execution time of nursing passes may exceed the execution time of working moves. Therefore, the search for solutions that ensure the accuracy and quality of holes in internal grinding operations is an urgent scientific and technical task.

2. Purpose and objectives of the study

Objective: improving the performance of internal grinding operations by reducing the number of passes Vyazovaya based on assignment of unequal values plunge feedrate to the rigidity of the technological system.

Tasks:

1. To analyze the influence of design and technological factors on the performance of the internal grinding process.

2. Conduct an experimental determination of the stiffness of the headstock and spindle internal grinding machine model 3E12.

3. To develop a model of deformation of the technological system during internal grinding under the influence of the radial component of the cutting force in the SolidWorks Simulation software environment.

4. To investigate the effect of mortise feed on the amount of elastic deformation in the contact zone of the workpiece and the tool.

5. Determine the rational distribution of the grinding allowance for each double stroke in order to obtain the minimum number of nursing passes.

6. Develop recommendations for the purpose of technological processing conditions for internal grinding operations of parts.

Conclusions

Analysis of the internal grinding process has shown that the performance of the process can be significantly improved by reducing the number of nursing passes. The number of nursing passes depends on the amount of deformation of the technological system at the time of the last working pass with a set of depth.

Reducing the number of nursing passes and, consequently, increasing the productivity of the internal grinding process is possible through the use of both design and technological solutions. Design solutions are aimed at increasing the rigidity of the technological system, especially the spindle mandrel. Technological methods should be aimed at reducing the cutting forces, especially in the last working moves carried out with a set of cutting depth.

List of sources

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4. Васин, М.П. Адаптивное управление процессом шлифования колец высокоточных подшипников / М.П. Васин, В.В. Горбунов, С.А. Игнатьев // Вестник СГТУ. – 2006. – Т. 1. – №3. – С. 129–136.