AUTOMATIC DESIGN FEATURES OF COMPLEX SHAPE DETAILS AND TECHNOLOGY OF THEIR MANUFACTURING

The creation of modern high-performance machines often involves design of details with complex surfacese and made with high precision. At the stage of design and preparation of production, project work is carried out using automation tools and modern information and computer technologies. The process of creating a project is accompanied by the preparation of appropriate documentation, sufficient to solve all possible questions, starting with the formation of a design task and disposal of the product at the end of its operation. According to statistics, most details in mechanical engineering are simple in shape, relatively technological in production, and their surfaces are most often described in the drawings by a set of lines and circles (radius of curvature). This approach is economically justified and will ensure the reliable operation of the product during operation. Significant difficulties arise when it is necessary to design parts with surfaces of complex geometric shape, when the geometric parameters are set by coordinate points. The accuracy of surface description depends on the number of such points and the accuracy of numerical data. Typical examples include turbine impellers, parts with aerodynamic surfaces that are used, for example, in the aerospace or rocket industries. The process of manufacturing such parts is accompanied by overcoming specific difficulties in describing complex surfaces at the stages of design and technological preparation, as well as directly in the manufacture of parts on technological equipment, intermediate and final control of geometric accuracy. An option for an effective solution of such problems is to record complex smooth surfaces, predefined by a set of coordinate points, splines. Modern design automation tools make it possible to use this mathematical method for modeling complex geometric objects and use it to calculate the trajectories of the forming tool on CNC machines. On the example of parts from production, which has a complex surface, using computer-aided design systems considered options for making design and technological design decisions for production preparation, equipment design, control the accuracy of shaping when machining on CNC machines.

System for Tool-Wear Condition Monitoring in CNC Machines under Variations of Cutting Parameter Based on Fusion Stray Flux-Current Processing

The computer numerical control (CNC) machine has recently taken a fundamental role in the manufacturing industry, which is essential for the economic development of many countries. Current high quality production standards, along with the requirement for maximum economic benefits, demand the use of tool condition monitoring (TCM) systems able to monitor and diagnose cutting tool wear. Current TCM methodologies mainly rely on vibration signals, cutting force signals, and acoustic emission (AE) signals, which have the common drawback of requiring the installation of sensors near the working area, a factor that limits their application in practical terms. Moreover, as machining processes require the optimal tuning of cutting parameters, novel methodologies must be able to perform the diagnosis under a variety of cutting parameters. This paper proposes a novel non-invasive method capable of automatically diagnosing cutting tool wear in CNC machines under the variation of cutting speed and feed rate cutting parameters. The proposal relies on the sensor information fusion of spindle-motor stray flux and current signals by means of statistical and non-statistical time-domain parameters, which are then reduced by means of a linear discriminant analysis (LDA); a feed-forward neural network is then used to automatically classify the level of wear on the cutting tool. The proposal is validated with a Fanuc Oi mate Computer Numeric Control (CNC) turning machine for three different cutting tool wear levels and different cutting speed and feed rate values.

Full-factor matrix model of accuracy of dimensions performed on multi-purpose CNC machines

Introduction. One of the main reasons that modern multi-purpose CNC machines do not use the capabilities of multi-tool processing is the lack of recommendations for design in this direction and, accordingly, for adjustment schemes. The study of the possibilities of multi-tool processing on multi-purpose machines is the subject of the work. The purpose of research: The problem of developing full-factor matrix models of dimensional accuracy and its sensitivity to the machining process is considered to increase the machining efficiency while ensuring machining accuracy using the technological capabilities of multi-tool machining on modern multi-purpose CNC machines. For this purpose, full-factor matrix models of the size scattering fields performed on multi-tool double-carriage adjustments have been developed, taking into account the cases of processing parts with dimensions that differ sharply in different directions, which are often encountered in practice, and in this case, the significant influence of the turns of the workpiece on the processing error, especially in directions with sharply different overall dimensions. Results of research: The developed accuracy models make it possible to calculate not only plane-parallel displacements of the technological system for double-carriage adjustments, but also angular displacements around base points, take into account the combined effect of many factors – a complex characteristic of the subsystems of the technological system (plane-parallel matrix of compliance and angular matrix of compliance), the geometry of the cutting tool , the amount of bluntness of the tool, cutting conditions, etc. As a result, based on the developed accuracy models, it is possible to obtain several ways to control multi-tool machining, including improving the structure of multi-tool adjustments, calculating the limiting values of cutting conditions. Based on the developed full-factor matrix models, it became possible to develop recommendations for the design of adjustments and the creation of an automated design system for multi-tool machining for a group of modern multi-purpose CNC lathes. Scope of the results: The results obtained can be used to create mathematical support for the design of operations in CAD-systems provided for multi-tool multi-carriage machining performed on multi-purpose machines. Conclusions: The developed models and methodology for simulating the machining accuracy make it possible to increase the accuracy and efficiency of simultaneous machining, to predict the machining accuracy within the specified conditions.

Features of calculating the parameters of taps for cutting precise threads on NC- machining technique

The analysis of the features of the taps when cutting precise metric threads by the synchronous method on CNC machines is given. The layout of the tolerance fields of the average diameter of the tap and nut threads is constructed, which allows to ensure the accuracy, controllability and durability of the cutting tool. The formula for calculating the average diameter of the tap thread has been defined.

Minimizing the Energy Consumption of Holes Machining Integrating the Optimization of Tool Path and Cutting Parameters on CNC Machines

The application of sustainable manufacturing technologies is the new challenge faced by enterprises, industries, and researchers under the background of supporting carbon peak and carbon neutral. This paper studies how to reduce the energy consumption of holes machining through optimizing tool path and cutting parameters simultaneously. The integrated optimization methodology can further reduce the energy consumption comparing with optimizing the tool path or cutting parameters separately. Firstly, the energy model of holes machining is established based on machine tools’ energy composition, tool path planning, and process parameters. Due to tool path planning as air cutting process has big relationship with reducing energy, especially for holes group with a big proportion in the whole process. The tool path of holes processing is optimized by the improved ant colony algorithm to solve the issue considering the distance from one hole to the next hole. Based on this optimized path, a multi-objective optimization model for hole cutting parameters is established, considering the spindle speed and feed rate as the optimization variables and machining time, energy consumption, and surface roughness as the objective function. The non-dominated sorting genetic algorithm (NSGA-Ⅱ) is employed to solve the multi-objective optimization problem of holes machining. The case study with 50 holes is used to testify the application of the proposed method to provide the practical energy efficiency strategy for holes group or multi-hole parts on CNC machines assisting in achieving sustainable production in manufacturing sectors.