Chip formation processes based on orthogonal processing of polymer composite materials

This paper presents the results of the study of processes occurring in the cutting zone during the processing of polymer composite materials. The research included determining the effects of orthogonal cutting conditions, such as the cutting depth t and cutting rate v, on the tangential component Pz of the cutting force, the length lc of chips, as well as the vibration acceleration W, to clarify the results previously submitted to the scientific community and obtain new data. The study included 12 experiments for different cutting conditions with the cutting depth t varying in the range of 0.1—0.4 mm and the cutting rate — in the range of 6.7—30.2 m/min. The experimental results allowed to determine a range of cutting rates that lead to a low level of elastic deformations of reinforcing fibers. Based on the dynamics of increasing cutting forces in various cutting conditions, tool cutting edge wear, type and length of chips, as well as the vibration acceleration dynamics, we have found that reinforcing composite material fibers accumulate on the tool cutting edge, while elastic fracture of these fibers causes defect formation on the processed surface. The analysis allows giving recommendations on the need for research in the field of abrasive machining with rigid grinding wheels due to the highest hardness of the cutting tool surface, increased machining speed and the possibility of self-sharpening during tool wear.

Tool-Workpiece Interaction in the Cutting Process and Its Use

The paper analyzes the influence of natural tool wear on parameters of chip shaping and machining forces and proposes the adjustment of tool geometry based on natural shape of crater wear to extend time of machining. The contact of the cutting tool and the workpiece at actual cutting speed is a complex physical process, the result of which is a specific shape and characteristics of the machined surface and the modification of tool cutting characteristics. Due to the fact that there is no existing cutting material which would resist wear in the conditions of working high stress and temperature, it is necessary to take into account that tool cutting conditions change with cutting time. This is caused by the change in tool geometry after its functional areas become worn out. One of the practical effects of those changes is gradual modification of machined surface geometry, its fortification, formation of residual stress, character of chip formation and shaping, the development of friction temperature and deformation in the zone of the contact of the tool and workpiece. This means that the cut part changes its characteristics. It is up to date to eliminate or at least mitigate this negative influence of tool wear based on the results of cutting.

A Comparison of the Probes with a Cantilever Beam and a Double-Sided Beam in the Tool Edge Profiler for On-Machine Measurement of a Precision Cutting Tool

This paper describes a comparison of the mechanical structures (a double-sided beam and a cantilever beam) of a probe in a tool edge profiler for the measurement of a micro-cutting tool. The tool edge profiler consists of a positioning unit having a pair of one-axis DC servo motor stages and a probe unit having a laser displacement sensor and a probe composed of a stylus and a mechanical beam; on-machine measurement of a tool cutting edge can be conducted with a low contact force through measuring the deformation of the probe by the laser displacement sensor while monitoring the tool position. Meanwhile, the mechanical structure of the probe could affect the performance of measurement of the edge profile of a precision cutting tool. In this paper, the measurement principle of the tool edge profile is firstly introduced; after that, slopes and a top-flat of a cutting tool sample are measured by using a cantilever-type probe and a double-sided beam-type probe, respectively. The measurement performances of the two probes are compared through experiments and theoretical measurement uncertainty analysis.

Structural Strength of Cemented Carbides

The concept “structural strength of tool materials” got further development. The refusals of cemented carbide cutting plates, when heavy machining were analyzed. It was shown that 70…80% of refusals are the microchipping of cutting edges, tool cutting part chipping, cutting plate macrofracture. To assess cutting plate total carrying capacity and the influence of different methods of cemented carbides modification, bending tests were held. Local fracture resistance and damageability of cutting edge were assessed under its continuous scanning.

Estimation of the Frequency Response Function of the Rotational Degree of Freedom

One of the factors that influence the dynamic characteristics of machining systems is the cutting tool. Cutting tools are very diverse, and receptance coupling substructure analysis (RCSA) is essential for analyzing the dynamic characteristics of each tool. For RCSA, a full receptance matrix of the equipment and tools is essential. In this study, rotational degree-of-freedom receptance was estimated and analyzed using translational receptance. Displacement/moment receptance was analyzed according to the distance of the response point using the first-and second-order finite difference methods. The rotation/moment receptance was estimated according to the distance of the response point. Rotation/moment receptance was analyzed using Schmitz’s method and compensation strategies. The limitations of these strategies were analyzed, and the rotation/moment receptance for the beam under free-free boundary conditions was predicted using the second compensation strategy.

Features of the formation of wear of the cutting part of a single-sided cutting drill

On the basis of experiments and the theory of metal cutting, the process of processing a deep hole with a onesided drill is considered. The technique of conditional division of the cutting zone into 20 annular layers was used, for each of which the process parameters were calculated by the method of successive approximation. A formula is obtained for evaluating the wear chamfer of the cutting part, taking into account the energy expended, tool parameters and the duration of processing. Keywords: drilling, hole, cutting tool, cutting edge, power, wear, temperature. [email protected]

Comparative Study on Wood CNC Routing Methods for Transposing a Traditional Motif from Romanian Textile Heritage into Furniture Decoration

This paper presents experimental research on the Computer Numerical Control (CNC) routing of a traditional motif collected from Ţara Bârsei (Transylvania region) using two methods, namely, engraving (Engrave) and carving (V-Carve). The analysis of the CNC router processes includes the calculation of the path lengths, an assessment of the processing time and wood mass loss, and an evaluation of the tool wearing by investigating the tool cutting edge on a Stereo Microscope NIKON SMZ 18 before and after processing the ornament on wood. An aesthetic evaluation of the ornament routed on wood, using both the engraving and carving methods, is also conducted, whilst a microscopic analysis of the processed areas highlights the defects that occurred on the wood surface depending on the tool path.