The complexity of the construction of technological processes in mechanical engineering causes various device designs and a high level of requirements for them [1, 2]. Insufficiently designed technological and structural solutions in the selection and use of machine devices lead to a significant decrease in production efficiency due to decreased productivity and machining accuracy and increased cost of implementing the technological process. Therefore, a competent choice of machine devices in the development of technological processes increases the efficiency and the technological culture of production [1-5]. When choosing machine devices, it is necessary to take into account many factors: one of the important is the machining accuracy provided by the device.
This paper considers the technological operation of grinding a sleeve made of steel 45, performed on a CNC milling machine (Pic. 1). The workpiece in process has the following dimensions: length 50 mm, outer diameter Ø50 mm, inner cylindrical hole Ø40 mm. It is required to base and fasten it on the inner cylindrical surface with an emphasis on the end and then sharpen the outer cylindrical surface into the size of Ø46h9.
The considered installation scheme can be implemented using universal devices serially manufactured by specialized enterprises. Such devices can be a three-jaw chuck, a collet chuck, and various expanding mandrels with a non-standard design. These devices have a design that causes different centering accuracy, fastening ranges, maximum fastening forces, the error caused by the fastening forces, and the cost of these devices.
The manufacturers' catalogs of machine equipment contain such technical characteristics of devices as centering accuracy, maximum and minimum fastening diameters, and the possibility of use in roughing operations with high cutting forces. However, these catalogs do not contain data on the shape accuracy provided by this equipment and, in particular, the error caused by the fastening forces. At the same time, precisely the provision of the shape error is usually the main technological problem solved in the development of technological processes. Therefore, this paper simulates the influence of the fastening forces of various types of machine devices on machining accuracy.