Расчет сил и момента резания при фрезеровании концевыми фрезами

Handwriting: Hand–pen contact force synergies in circle drawing tasks

In this study, a novel joining method, called sacrificing-sheet linear friction welding (SSLFW), was developed and utilised to join SS400 structural carbon steel and A7075 aluminum alloy. SSLFW involves placing a centre sheet between the two side materials to be joined. The centre sheet is subjected to linear oscillating motion while side materials are pressed against it. The thermomechanical effect from each side leads to the expulsion of centre sheet from joining interface, enabling direct joining between the side materials. Furthermore, intermetallic compounds (IMCs) layer thickness at dissimilar joint interface was minimised with increase in welding pressure accompanied by increased forging speed. Consequently, joints produced at forging speeds of 40 and 50 mm/s show the highest joint strength of 425 MPa, exhibiting a joint efficiency of 88% with respect to base metal strength of SS400 steel. Furthermore, following post-weld artificial aging treatment, the joint strength was enhanced to ∼ 448 MPa, improving the joint efficiency to 93%.

Micro end milling with fine grained carbide end mills is an economical way to machine small and medium lots of micro components. Considering the sensitivity of the slender end mills which are very costly compared to conventional end mills, it is imperative that the machining parameters are chosen appropriately so as to ensure maximum tool life and minimum possible production cost without violating any of the imposed constraints. Unlike in conventional end milling operations the tool life in micro end milling operations increases with axial depth of cut till it equals the tool diameter and this makes it even difficult to ascertain the appropriate depth of cut to machine a specific component. In this paper the influence of depth of cut on tool life is illustrated and depth of cut is also considered as one of the decision variables in the optimization problem. More over in this paper Genetic Algorithms (GA) based on natural laws of evolution is used to optimize the cutting parameters. Finally a test case is presented to give a clear picture of the application of the optimization algorithm.

The continuous strength method for the design of aluminium alloy structural elements

Compared with the traditional 5083 or 6082 aluminum alloy, 5059 has better mechanical properties and corrosion resistance. The traditional fatigue class curve is no longer suitable for fatigue strength evaluation of 5059 marine aluminum alloy structures. Meanwhile, the welding structure of thin aluminum alloy has bigger initial welding defects, resulting in more obvious stress concentration effect at the corner. Large welding deformation brings great challenges to the precision evaluation of stress concentration effect and fatigue strength near corners. Therefore, in order to accurately consider the influence of welding defects, the welding temperature field and stress field of 5059 aluminum alloy structures were simulated and analyzed systematically. In addition, considering the influence of welding deformation and residual stress, the fatigue assessment of 5059 aluminum alloy welded joints based on hot spot stress was carried out, and the fatigue class curve suitable for thin plate cruciform joint of 5059 was renewed.

Three orthogonal components of the tibiofemoral and patellofemoral forces were measured simultaneously for knees with intact cruciate ligaments (nine knees), following anterior cruciate ligament resection (six knees), and subsequent posterior cruciate ligament resection (six knees). The knees were loaded using an experimental protocol that modeled static double-leg squat. The mean compressive tibial force increased with flexion angle. The mean anteroposterior tibial shear force acted posteriorly on the tibia below 50 deg flexion and anteriorly above 55 deg. Mediolateral shear forces were low compared to the other force components and tended to be directed medially on both the patella and tibia. The mean value of the ratio of the resultant tibial force divided by the quadriceps force decreased with increasing flexion angle and was between 0.6 and 0.7 above 70 deg flexion. The mean value of the ratio of the resultant tibiofemoral contact force divided by the resultant patellofemoral contact force decreased with increasing flexion and was between 0.8 and 1.0 above 55 deg flexion. Cruciate ligament resection resulted in no significant changes in the patellar contact forces. Following resection of the anterior cruciate ligament, the tibial anteroposterior shear force was directed anteriorly over all flexion angles tested. Subsequent resection of the posterior cruciate ligament resulted in an approximately 10 percent increase in the quadriceps tendon and tibial compressive force.

This study investigates the cutting force characteristics in tangential turning of 42CrMo4 alloy steel using a full factorial experimental design. The objective is to evaluate the influence of cutting speed, feed per revolution, and depth of cut on the tangential (major cutting force), axial (feed-directional force), and radial (thrust force) components, as well as on their corresponding specific cutting forces. The experimental work was conducted on a hard turning center equipped with tangential turning tooling. Cutting forces were measured using a three-component dynamometer. A total of eight experimental setups were defined based on different combinations of cutting parameters. For each setup, all three force components and their corresponding specific cutting forces were determined. Polynomial regression equations were developed to model the influence of the input parameters on the cutting forces. The results indicate that feed per revolution and depth of cut significantly increase the magnitude of all force components, whereas higher cutting speed tends to reduce the major cutting force. The specific cutting forces decrease with increasing chip cross-sectional area, indicating improved cutting efficiency. In contrast, the specific thrust force exhibits a more complex behavior, influenced by chip flow characteristics and radial tool engagement. Overall, this study contributes to a deeper understanding of cutting mechanics in tangential turning and provides a basis for optimizing high-feed machining strategies for hardened steels.

In this work, the influence of a high power diode laser surface treatment on the structure and properties of aluminium alloy has been determined. The aim of this study was to improve the mechanical and tribological properties of the surface layer of the aluminium alloy by simultaneously melting and feeding tungsten carbide particles into the molten pool. During the process was used high-power diode laser HPDL. In order to remelt the aluminium alloy surface the HPDL laser of 1.8, 2.0 and 2.2 kW laser beam power has been used. The linear laser scan rate of the beam was set 0.5 cm/s. In order to protect the liquid metal during laser treatment was used argon. As a base material was used aluminium alloy ENAC-AlMg9. To improve the surface mechanical and wear properties of the applied aluminium alloy was used biphasic tungsten carbide WC/W2C. The size of alloying powder was in the range 110-210 µm. The ceramic powder was introduced in the remelting zone by a gravity feeder at a constant rate of 8 g/m.

CVD diamond films are deposited on cobalt cemented tungsten carbide (WC-Co) endmills using hot filament chemical vapor deposition (HFCVD) method. Scanning electron microscope (SEM) and Raman spectroscopy are used to characterize the as-deposited diamond films. To evaluate the cutting performances of as-fabricated CVD diamond coated endmills, dry milling tests are conducted using aluminum alloy as the workpiece material. The uncoated WC-Co endmills are also adopted in the milling tests for the sake of comparability. The experimental results show that the build-up edge formed on the uncoated WC-Co endmills at very early stage of the cutting tests. Comparatively, CVD diamond coated endmills present an excellent anti-adhering property. The result suggests that depositing diamond coating on WC-Co endmills is a viable way to improve their cutting performances in machining of aluminum alloy materials

The deformation and strength of single lap joints having adherends of dissimilar materials were investigated both analytically and experimentally. The strain distributions under tensile shear loads of the joints of carbon steel and aluminum alloy bonded with epoxy resin were analyzed using the finite element method. The analytical result was shown to coincide approximately with the experimental one. The analyzed strength was less than the experimental one probably because the former predicted the initial cracking loads whereas the latter predicted the fracturing loads which were different from the former. Young's moduli of adherends and the adhesive length had great effect on the joint strength. The strength of joints of carbon steel and aluminum alloy had valued intermediate between the strengths of joints having carbon steel adherends and aluminum alloy adherends. The curing process of the adhesive resin improved the joint strength overcoming the difference in thermal properties of the adherends.

Environmentally assisted cracking (EAC) of aluminum alloys in corrosive atmospheres is an important maintenance and safety issue for U.S. Department of Defense assets. EAC initiation and propagation of cracks is influenced by the complex interactions of load, environment, and alloy properties. Traditional environmental fracture testing conducted under immersion or constant humidity conditions may produce results that are different than measurements collected under thin electrolyte layers or droplets formed during atmospheric exposure. In addition, most standard methods do not provide instantaneous measures of crack velocity that can be used to identify specific environmental conditions that promote cracking. Improved assessment of EAC susceptibility and the conditions that promote cracking of aluminum alloys has been accomplished with an autonomous, in situ measurement system that can be used in accelerated corrosion test chambers and outdoor exposure sites. Continuous measurements of crack length throughout a corrosion study can be obtained using a tensile loaded notched specimen, compact load frame, and a force sensor to track load shedding with crack propagation. These measurements can be used to compare alloy performance, determine environmental conditions that promote EAC, and evaluate the effectiveness of corrosion control coatings and methods. Aluminum alloy testing with varying environmental and mechanical parameters (e.g., relative humidity, salt composition, degree of sensitization, and stress intensity) has demonstrated a strong dependence of crack velocity on cyclic relative humidity (RH). Specifically, in a number of tests, crack velocity increased to a maximum during drying (decreasing RH) at intermediate humidity. This result may be important to understanding the processes that promote EAC and indicates that high humidity and salt loading may not always be the most aggressive conditions for evaluating EAC susceptibility. Results of AA5083 alloy testing in cyclic accelerated corrosion tests, including ASTM B117, ASTM G85 A5, and GM9540P are reported. A subset of results for AA7075-T651 is also presented to demonstrate applicability of the test method for a different alloy that was not as highly sensitized to EAC.

Numerical investigation and design of perforated aluminium alloy SHS and RHS columns

Difficult-to-cut material, i.e., AISI D2 tool steel, has been widely adopted in metalworking industries to manufacture dies for piercing, blanking, drawing and thread rolling due to its excellent wear resistance and non-deforming properties. This article attempts an experimental study to determine the effect of cryogenic coolant (liquid nitrogen) on the grindability of AISI D2 tool steel as work material and its results are compared with the conventional dry and wet grinding methods. The effects of the cryogenic coolant on force components (i.e., tangential force, Ft and normal force, Fn ), specific grinding energy (u), force ratio, surface roughness parameters (Ra and Rz ) and microstructure were observed. The comparison results indicate a significant reduction in grindability indices such as 64% and 44% in Ft , 54% and 34% in Fn , 46% and 30% in Ra and 40% and 34% in Rz , respectively under cryogenic grinding at higher downfeed as followed to dry and wet grinding. The grinding performance in Ft , Fn , u and Ra was also improved with an increased delivery pressure of the liquid nitrogen (LN2). From the results, it is concluded that cryogenic coolant offers an influential method to improve grinding performance and surface integrity of AISI D2 tool steel.

1. Ultrasonic treatment of the melt along with the addition of surface-active sodium in amounts of 0.2–0.8% makes it possible to obtain antifriction aluminum alloys with a lead concentration as high as 12%. The lead inclusions are evenly distributed through the base metal. 2. The addition of sodium to aluminum alloys with lead improves the strength characteristics, with retention of fairly high ductile characteristics (elongation 15–17%). 3. The antifriction properties of aluminum alloys with 8–12% Pb are close to those of babbitt B83 and high-tin aluminum alloys widely used for bearings.

The paper presents the research results showing the positive effect of pressure on the formation of the structural properties of aluminum alloys. The processing modes have been established that create the most favourable conditions for the formation of equilibrium structures in aluminum alloys. On prototypes of aluminum alloy B95, having dimensions Ø80 × 60 mm, after processing according to the proposed technology, there are no defects in the cast structure in the entire section. A diagram of the isothermal decomposition of a supersaturated solid solution of alloying elements in aluminum is proposed, illustrating the possibility of quenching after pressing the melt under pressure and subsequent aging according to the selected mode. Using the proposed control and measuring system, the dependences of the change in the compressibility of the melt on pressure and time have been established. It is shown that obtaining high quality cast billets with a dense structure throughout the entire volume can be achieved provided that the process control is automated. A block diagram of a technological process control system has been developed, including a modern control and measuring system, automation and regulation means, which allows to control the main process parameters that have a direct impact on the formation of properties of the resulting blanks.