LEPETUKHA DE Grinding of thin-walled cylinders Abstract

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Abstract of masters work

On the Theme: "Technological maintenance of abrasive processing of cylindrical thin-walled products"

Student: Lepetukha Denis Evgenyevich
Leader:: Mikhaylov Aleksandr Nikolaevich

The Theme of masters work: "Technological maintenance of abrasive processing of cylindrical thin-walled products ".

1 Introduction

Constant development of techniques at the present stage demands the usage of the details representing thin-walled shells. Now their quantity considerably increases in the bulk of the details, subjected to machining. Thin-walled products, providing high durability and density of configuration, find wide application in the most different industries and, what is especially important, in the most important areas: plane-and rocket production, cryogenic techniques and refrigerating, space and military-industrial development.
Alongside with increase in a share of thin-walled products in a bulk of processable details, technical requirements to accuracy of the sizes of thin-walled surfaces, the form and their relative positioning, the requirement to quality of a superficial layer are also raising. In especially exact (precision) mechanical engineering these requirements reach are limited by micrometers and shares of a micrometer. Because of the basic feature of thin-walled products - their small rigidity, performance of these requirements is rather difficult task.

The purposes and problems of work

As it is already known, the greatest influence on quality of the thin-walled cylinders processed by grinding renders the clamping therefore the decision of a problem of fastening of such preparations is reduced to researches in the field of industrial equipment. It is the most rational to apply device with the distributed forces of fastening to grind such preparations. Such devices are focused on uniform distribution of efforts of fastening or tending to it (plurality of points of the application). It is considered, that regular by distributed forces lead to uniform deformation of a thin-walled surface of preparations. However in practice while grinding thin-walled cylinders of precision details shape distortions were found out. It is connected with the so-called edge effect.
The primary goals are: depending on parameters of quality to define a scope of industrial application; to develop methods of definition of shape distortions at fastening of thin-walled cylindrical products; to offer constructive approaches and methods of calculation of tooling for creation of any set law of distribution of force of fastening with purpose to reduce an shape distortions of especially exact thin-walled cylinders.

The review of existing researches and development

   The problem of grinding of thin-walled cylindrical products is not widely researched that can be justified by some deficiency of the information on this question. It is first of all connected with a scope of thin-walled products, which only start to be used widely. Studying of tensely deformed condition demands application of the powerful mathematical device which in turn demands powerful computer facilities which has appeared rather recently.
   So, for example, in D.D.Yevseyev's work, Ampere-second. A. S. Tarapanov’s, professors of the Oryol state technical university About ADMISSIBLE EFFORTS of CUTTING AT TURNING PROCESSING THIN-WALLED CYLINDRICAL ENVIRONMENTS the process of turning machining as the most comprehensible is considered. It is connected with the fact that high propensity to elastic temperature deformations of thin-walled elements at their final processing by grinding causes shape distortions of elements of details and their surfaces. Usage of thin turning instead of grinding allows to exclude heading an abrasive, cracks and burnings.
   Crucial importance on operational properties of nonrigid thin-walled details renders accuracy of the shape and the sizes. During turning processing there is a difficulty in maintenance of the accuracy, caused by deformation of a processable detail by a cutter.
   In a view of the aforesaid there is a necessity of calculation of admissible forces of cutting, with the purpose of finding of optimum modes of cutting. The calculation scheme represents the cylindrical environment jammed from one end face and loaded from other end face by efforts of cutting in the form of three concentrated forces. For the description of the intense-deformed condition of shelled element Z. Vlasov’s theory of calculation of cylindrical shells is used which allows to consider not symmetric by axis load of a shelled element.

Planned practical result. Planned own results

While fulfilling of masters work tensely deformed condition of thin-walled cylindrical preparation as a result of imposing of regularly distributed loading on a surface of an environment is planned to investigate. On the basis of it development of principles, which will be a basis for designing and construction of devices for preparation fastening at grinding is planned. Definition of dependence of change of forces of cutting depending on change of depth of cutting is planned, and in its turn it will influence the size of effort of fastening that can lead to excessive deformation of thin-walled nonrigid preparation. Therefore, it is necessary to define optimum size of a removed layer to have high efficiency and demanded quality of a ready, made detail.
It is planned to study influence of the temperatures arising at grinding, on rigidity of shelled surfaces and quality of a superficial layer, and also to offer methods of struggle against heats.

Conclusion

   Technological maintenance of grinding of thin-walled cylindrical products is not a complex a theme at first sight. But as a result of its analysis a plenty of problems demanding the decision emerge.
   The problem is that details of such type possess small rigidity and the application even rather small loadings can lead to occurrence of errors, commensurable with the toleranse. Small rigidity of thin-walled cylinders excludes any point influence on a shelled surface therefore the unique way of their fastening is the application of the distributed loading.
   But imposing of regular by distributed loading is not the best variant since as a result of exposing of edge effect near the holes, cuttings, flanges, edges of preparation shape distortions are observed, commensurable for precision shelled preparations with a maximum deviation of the form.
   All this leads to necessity to develop tightening devices in which loading would be distributed not evenly, and under the demanded law, creating in demanded places additional excessive deformation, and in the some points on the contrary - influencing with smaller effort.

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