Study on the Formation Mechanism of Surface Adhered Damage in Ball-End Milling Ti6Al4V

Ball-end cutters are widely used for machining the parts of Ti-6Al-4V, which have the problem of poor machined surface quality due to the low cutting speed near the tool tip. In this paper, through the experiments of inclined surface machining in different feed directions, it is found that the surface adhered damages will form on the machined surface under certain tool postures. It is determined that the formation of surface adhered damage is related to the material adhesion near the cutting edge and the cutting-into/out position within the tool per-rotation cycle. In order to analyze the cutting-into/out process more clearly under different tool postures, the projection models of the cutting edge and the cutter workpiece engagement on the contact plane are established; thus, the complex geometry problem of space is transformed into that of plane. Combined with the case of cutting-into/out, chip morphology, and surface morphology, the formation mechanism of surface adhered damage is analyzed. The analysis results show that the adhered damage can increase the height parameters Sku, Sz, Sp, and Sv of surface topographies. Sz, Sp, and Sv of the normal machined surface without damage (Sku ≈ 3) are about 4–6, 2–3, and 2–3 μm, while Sz, Sp, and Sv with adhered damage (Sku > 3) can reach about 8–20, 4–14, and 3–6 μm in down-milling and 10–25, 7–18, and 3–7 μm in up-milling. The feed direction should be selected along the upper left (Q2: β∈[0°, 90°]) or lower left (Q3: β∈[90°, 180°]) to avoid surface adhered damage in the down-milling process. For up-milling, the feed direction should be selected along the upper right (Q1: β∈(−90°, 0°]) or upper left (Q2: β∈[0°, 90°)).

Feed direction dependent milling dynamics of an asymmetric flexible machining system

Asymmetric flexible machining system has been widely used in NC machining. In traditional milling dynamics model, the cutter feed direction is usually defined as parallel to its vibration DOF, while the nonparallel condition and its induced milling dynamics response are not deeply considered. This paper presents a general dynamics modeling method for asymmetric flexible machining systems. Firstly, to the best of the author's knowledge, a new dimension named feed direction is proposed, which is used to establish the generalized coupling relationship between the vibration displacement and the regenerative milling force, thus improve the applicability of the milling dynamics model and reduce the experimental workload compared with the traditional modeling. Secondly, through the theoretical and experimental research, it is shown that the asymmetric flexible machining system has a significant feed direction dependent characteristics, and implied the existence of high performance machining region with higher stability and low SLE by contrast with the symmetrical milling system and the traditional model. Finally, by controlling the feed direction angle, the milling parameters in roughing and finishing operation are optimized, and the machining efficiency has been greatly improved on the premise of stable cutting and machining accuracy at last.

Actuator and Process Development for Vibration Assisted Turning of Steel

Due to continuous tool engagement, turning processes tend to form long chips when machining ductile materials. These chip shapes have a negative influence on process performance and productivity. One approach to improve chip breakage is superimposition of vibrations in feed direction of the turning process, which leads to a modulation of uncut chip thickness. In a joint industrial project with Schaeffler Technologies AG & Co. KG, Fraunhofer IWU developed an oscillating actuator for turning. The actuator converts a rotational movement of a drive motor into a translational vibration via an eccentric gear. The tool shank is mounted in solid joint assemblies. With this prototypical system, a cyclic movement of the tool in feed direction can be realized. The typical operating parameters of the actuator is within the range of 1...100 Hz with adjustable vibration amplitudes up to 0.6 mm peak-to-peak. A significant improvement in chip breaking during the machining of steel 1.0503 was shown in cutting tests.

Velocity Effect Sensitivity Analysis of Ball-end Milling Ti-6Al-4V

Ball-end cutters are widely used in industries of dies, molds, and aerospace, which have the problem of poor machined surface quality due to the low cutting speed near the tool-tip. With the increase in the complexity of parts, it will become more and more difficult to avoid the tool-tip participating in the cutting. In this paper, the velocity effect sensitivity of ball-end cutter is analyzed, and several key positions, including the intersection points of the CWE boundaries, are selected to describe the cutting speed in three dimensions. The relationships between the cutting speed of the critical points and important variables such as: machining inclination angle and the feed direction were investigated. The optimal range of feed direction is obtained when the tool-tip engages in the contact circle. The core aim of the feed direction selection is to make the tool engagement area in a high position by changing the feed direction, to avoid surface damage caused by ploughing and improve the quality of the machined surface. Finally, an experimental study was carried out, and the results corroborate the effectiveness of the selection method. In the experiment, it was also found that cutting-out from the cutter contact position can improve the surface quality in the directions of non-optimal range, and the milling force and chips shape will vary with the change of the feed direction.

Results of selection work with grain crops in the subarctic zone of the Russian Federation

Agriculture of the Northern regions specializes in animal husbandry, in this regard an urgent problem of crop production in the conditions of the Northern regions of the Russian Federation is the creation of precocious, high-yielding varieties of grain crops for fodder purposes. The article reflects the selection achievements in grain crops over the past seven years. The presented new varieties combine high yield, increased environmental plasticity, and have the ability to reduce their productivity to a lesser extent when cultivated in the harsh conditions of the Northern region. Breeding work conducted at the laboratory of crop production of the Primorskiy filial FGBUN FICKIA RAN - ArhNIISKH in 2005-2019, in breeding semipolar rotation in accordance with the "Guidelines on the selection of barley and oats" (2014), methodology of State Commission for testing of agricultural crops (1985). The digestibility of winter rye dry matter was determined by in vitro method on an artificial stomach. Statistical processing of experimental results was performed using the AGROS version 2.07 selection and genetic software package. Results of the study. As a result of selection work, precocious productive varieties of grain crops of the feed direction were bred and included in the state register. Bereginya — new-generation winter rye variety, universal use, with a low content of water-soluble pentosans in the grain. The variety has been included in the State register of selection achievements since 2013. Variety of spring barley Tausen — feed direction, resistant to environmental stress factors, high-yielding, resistant to lodging and pathogens (dusty smut, spotting). It has been included in the State register of selection achievements since 2014. Spring barley variety Kotlassky — feed direction precocious, productive, adaptive to adverse environmental factors, for obtaining concentrated feed for livestock and poultry. It has been included in the State register of breeding achievements since 2019. Arhan spring oat variety — environmentally plastic adapted to changes in soil and climate conditions, immune to dusty smut, combines a high yield of grain and green mass. Since 2020, it has been included in the State register of selection achievements.

An Analysis of Manufacturing Precision of Involute Worms Using a Kinematical Model

The manufacturing precision of involute worms constitutes a major requirement. On the one hand, the worm constitutes the input element of the worm drive; secondly, the involute helical surface is the basic surface of an involute worm-hob. This paper presents an analytic comparison between the involute surfaces obtained using theoretical equations, kinematic simulation of the cutting and the surface charged with errors. The surface error is considered the distance along the normal direction to the theoretical surface, measured between this and the surface charged with simulated manufacturing errors. The main sources of errors are considered the center-error of the edge plane, the edge profile error and deviation of the axial feed direction from the axis of the worm. The theoretical results allow us to conclude that the influence of the edge profile error is the largest. It is followed by the parallelism error between the feed direction and the axis of the worm, and finally, the center error of the tool edge.

Workpiece Vibration in Feed Direction Assisted Electrochemical Cutting Using Tube Electrode With Inclined Holes

Electrochemical cutting using tube electrode with inclined holes is a machining method that directly and obliquely injects electrolyte into the machining gap through inclined jet-flow holes on the sidewall of a tube electrode, allowing the electrochemical cutting of a workpiece. To improve the machining efficiency and accuracy of this cutting technique, a method of workpiece vibration in feed direction assisted electrochemical cutting is proposed in which workpiece vibration along the feed direction rapidly and periodically changes the machining gap. The near-instantaneous increases in the machining gap promotes the waste electrolyte containing electrolytic products to flow down the machining gap. At the same time, the electrochemical reaction time under the non-uniform flow field caused by the inclined downward injection of electrolyte is reduced. The flow field simulation of electrolyte in machining gap indicates that the near-instantaneous increases in the machining gap can improve the flow velocity of electrolyte. Experiment demonstrates that the average feed rate can be increased by 50% and the machining efficiency is superior to that of electrochemical cutting assisted by workpiece non-vibration in feed direction. The difference between the upper and lower slit widths is reduced and the machining accuracy is improved. The effect of the vibrational amplitude and frequency on the machining result is also investigated. Finally, an array slice structure is fabricated on a stainless steel block with a cross-section of 10 mm × 10 mm at average feed rate of 6 mm/s using a vibrational amplitude and frequency of 0.1 mm and 1.5 Hz, respectively.

Wheel Setting Error Modelling and Compensation for Arc Envelope Grinding of Large-aperture Aspherical Optics

Precision grinding is the key process to meet the heavy demands of large-aperture aspherical optical elements in the fields of laser nuclear fusion devices, large-aperture astronomical telescopes and high-resolution space cameras. In this study, the arc envelope grinding process of large-aperture aspherical optics was investigated using the CM1500 precision grinding machine with a maximum machinable diameter of Φ1500 mm. The analytical form error models of aspherical workpiece induced by wheel setting errors were established for both parallel grinding and cross grinding. Result show that the form error is much more sensitive to the wheel setting error along the feed direction than that along the lateral direction. It is a bilinear function of the feed-direction wheel setting error and the distance to optical axis. Based on the above analysis, a method to determine the wheel setting error is proposed. The grinding tests were then performed with the wheel accurately aligned. By using a newly proposed partial error compensation method with an appropriate compensation factor, a form error of 3.4 µm PV for a Φ400 mm elliptical K9 glass surface was achieved.

Evaluation of the source material of winter triticale in breeding varieties of grain feed direction for the foothill zone of the Central Caucasus

The purpose of the work is to evaluate the source material of winter triticale for economically valuable traits for breeding varieties of grain and forage directions. Methods. The objects of study were winter triticale varieties of various ecological and geographical origin: Hortenso, Moderato (Poland), Prader (Switzerland), TGI 22/1, GR-16/2 (Russia), KS 88 T 142 (USA). Variety Valentin 90 was taken as a standard. Phenological observations and counts were carried out according to the method of state variety testing. The variability of winter triticale varieties was evaluated in the experiment with mowing shoots in the stalking phase at a height of 5 cm, at the test sites in triplicate. When evaluating the genotype-environment interaction, the Plant Productivity Index (PPI) was used. To assess the adaptability of genotypes to cultivation conditions, statistical methods were used to assess the plasticity and stability of varieties. Results. It was established that yields above 1 t/ha on average for three years were shown by variety varieties: Moderato (1.05 t/ha), GR 16/2 (1.14 t/ha) and Hortenso (1.19 t/ha). According to the values of the PPI, the variety specimens are highly productive: Valentin 90 (13.2), Hortenso (12.7), GR 16/2 (13.5), Moderato (11.6). In terms of ecological plasticity, the variety samples were divided into groups: the bi value is close to one – varieties well adapted to the conditions of the region (Prader, Hortenso, GR 16/2), extensive varieties – bi less than one (KS 88 T 142), intensive varieties – bi more units (Valentin 90, TGI 22/1, Moderato). According to the indicators of homeostaticity and breeding value, the variety samples were distributed in the following order, with decreasing values: Hortenso, GR-16/2, Valentin 90, Prader, TGI 22/1, Moderato, KS 88 T 142. Additional data were obtained by the method of provocative beveled plots, to determine potential productivity and regrowth. The best regenerative ability was shown by the variety samples: Hortenso, GR 16/2, Moderato, Prader. The scientific novelty lies in the fact that, for the conditions of the foothill zone of the Central Caucasus, promising winter triticale varieties were identified that can be used in breeding varieties of grain and feed direction: Hortenso, GR 16/2, Moderato, Prader.