Abstract: Cutting force is one of the most important parameters in the machining process, it significantly influenced machining precision of the workpiece, power consumed in the machining process, wear of the cutting tools and so on. There are many factors that affect the cutting force, such as the performance of the workpiece material, cutting speed, usage of the cutting fluid, etc. Single factor variable method was used in this paper, RuT450 was used as workpiece, welded cemented carbide gun drill was used as cutting force and LS-DYNA was used as simulation platform to established the cutting simulation model to analyzed the impact of the cutting speed and feed rate to the drilling force. Simulation results show that, at the low speed drilling stage, drilling force increases with the increase of the feed rate and decreases with the increase of the rotation feed, from the stress cloud it could be seen that the equivalent stress near the drill tip reached the maximum in the drilling process.
Abstract: The characteristics of cutting forces vibration and its effects to the hole quality in reaming aluminum cast alloy using a poly-crystalline diamond (PCD) step reamer in dry and wet conditions were studied. First, centrifugal force vibration model of the PCD step reamer during machining process was established and through the analysis of the model, it can be concluded that the maximum amplitude of the vibration is positively related to the angular velocity of the reamer. Then, thrust force and cutting torque were measured by a Kistler Dynamometer during reaming process and these vibration frequency and amplitude were analyzed by fast Fourier transformation (FFT). Hole quality was evaluated by hole diameter and surface roughness. Results show that, as the spindle speed increases, the stability of thrust force and cutting torque deteriorates gradually, and there was a severe vibration in the cutting force and the surface roughness when the spindle speed reached 10000 rpm in wet and 7000 rpm in dry cutting conditions. Compared the variation of hole surface roughness and vibration characteristic of cutting forces, it can be observed that the trends are very consistent, the surface roughness deteriorates when cutting forces become unstable. Therefore,the cutting forces stability was an important factor that influence the hole quality. Cutting fluid has a positive effect to stabilize the reaming process and was beneficial to improve the hole quality.
Abstract: When machining the cycloidal bevel gear on the CNC machine tool, the cutting force is gradually increased with the increase of the cutting depth when the feed speed of the cutter head is constant. The fluctuation of the cutting force is easy to cause the spindle vibration, reduce the surface quality. The off-line control is mainly used to optimize the NC code, and the cutting feed in the NC code is segmented according to the corresponding optimization algorithm and the constraint condition. When the spindle speed is 90 rpm, constant feed 40 mm/min, the cutting force of the volatility of 127.45%. When the feed rate is reduced from 50 mm/min to 26mm/min, the fluctuation rate of the cutting force is 46%. The variable feed control can effectively reduce the amplitude fluctuation of the cutting force.
Abstract: Along with the automobile lightweight development, aluminum has become the focus of its own material characteristics. The aluminum alloy products with high efficiency, high quality and low cost are the guarantee of competitive advantage. High quality die surface is directly related to the product quality, cost, production efficiency, die life and so on. In this paper, the stamping process of two kinds of aluminum alloy products was simulated by Auto Form. The method of setting blank holding force and spring back compensation was introduced. At the same time, the setting of parameters such as die fillet, friction coefficient and draw bead was described in this paper. Finally, the optimization of die surface design was achieved by simulation.
Abstract: In order to solve production defects such as shrinkage and porosity inside a certain train coupler casting in Anhui Xinhong Machinery Co.,Ltd., the main reasons of defects are found through the process of CAE simulation analysis and physical X ray detection to determine the location and morphology of casting defects and to reflect the actual situation of coupler filling and solidification process. The main reasons are found as follows: uneven thickness of casting structure, insufficient original gating and feeding system and etc. Through the process optimization and apply multidimensional vibration, then test validation, the train coupler casting which meets the technical requirements has been successfully produced, ensuring the smooth mass production of the company. ProCAST numerical simulation results have confirmed the rationality of the proposed work in optimization process measures in reducing and eliminating the shrinkage defects.
Abstract: The research analyzed the distribution of cutter position point data outputted by software CAM, based on the precision of surface milling. The model of the tool-path is established by using the piece-wise interpolation function, combining with the distribution characteristic of cutter position point. The segmentation optimization of the tool-path is also realized via the limitation and judgment of the string high error of the segmented trajectory and the optimization algorithm is integrated into the post-processing to improve the precision of the surface milling. The experiment results of surface milling show a positive effect of cutter position point optimization on surface milling accuracy.
Abstract: For path planning and program generation of multi-type holes, this paper presents a method of the path planning, by using the improved genetic algorithm based on chaos algorithm, and develops an interactive programming system for multi-type holes. Users can choose regular holes, and input the parameters and the necessary information, according to their needs. Then the system will combine holes automatically, and calculate the position coordinates of each hole. After that the path planning is carried out by using the improved genetic algorithm. Finally, the system carries out the simulation experiment of the path planning, and outputs NC program. Experiment shows the system can realize the path planning of multi-type holes by a combination of regular holes and generate the NC code after path planning. The optimization of path is better and the operation is more convenient than UG and other professional CAM software.
Abstract: Titanium alloys are widely used in modern aircraft manufacturing. The hole-making technology with high quality becomes a crucial aspect of aircraft assembly. Helical milling process has drawn much attention due to its high machining quality and efficiency. In this work, the cutting performance of small diameter tools (3mm) in helical milling Ti alloy is studied. The parameters of spindle speed, tangential feed speed and pitch (axial feed per revolution) are optimized to reduce cutting force and processing time. The evolutions of the cutting force, burr size, hole side wall roughness and diameter with increasing hole number are investigated. Results show that burr size and hole side wall roughness are much lower than the requirement of aircraft assembly under the optimized parameters of 7000r/min (spindle speeds), 0.1mm (pitch), 0.02mm/tooth (tangential feed). Due to the poor stiffness and large deflection of small diameter tools, excessive hole diameter error is the most prominent problem to be concerned in helical milling process.
Abstract: In order to study the milling process of compacted graphite iron cylinder block in practical, cutting parameters optimization experiment was conducted when cutting parameters were set as independent variable, and cutting efficiency and spindle power were set as optimization objective. The results showed that spindle power increased as the cutting speed and feed per tooth increasing, but cutting torque increased initially and then decreased as the cutting speed increasing. Feed force decreased with the increasing cutting speed and decreasing feed per teeth. Matlab software was used to optimize the cutting parameters when cutting efficiency and empirical formula of spindle power were settled as the objective functions. The most suitable parameters were abtained as V=164m/min and fz=0.28mm/z. The tool rake face mainly took place crater wear and material sticking. The main wear mechanisms for rake wear and fland wear were abrasive wear and adhesion wear.
Abstract: In order to reduce the defects of investment casting and improve its casting quality, vibration technology and casting technology are combined effectively and the effect of vibration degree of freedom, frequency and amplitude on the filling ability of liquid metal are studied by means of EDEM-FLUENT solid liquid coupling visualization. With the use of orthogonal test method, the sensitivity of the particles towards each parameter index is obtained. Optimal vibration parameters are chosen and then the best variable cell vibration casting solution is obtained.