Analysis and Test of Conductive Shaft of Large Horizontal NC ECM Machine Tool

In order to solve the problems of serious heating and easy ablation of conductive shaft in electrochemical machining of special-shaped deep hole with large aspect ratio, the two schemes of single side copper bar and symmetrical copper bar of conductive shaft were studied by ANSYS software. And the conductive shaft scheme based on symmetrical copper bar scheme was determined. The thermoelectric coupling model of the conductive shaft was established to analyze the distribution law of temperature field and thermal deformation of conductive shaft under different working conditions. Through the machining test of special-shaped inner spiral deep hole parts with large aspect ratio, the results show that under the conditions of working current of 15 000 A, feed rate of 5 mm/min and continuous machining for 14 hours, the forming accuracy of the workpiece is ±0.15 mm and the surface roughness is better than Ra0.8 µm. The performance of the conductive shaft is stable and meets the actual processing requirements. The heat dissipation performance of the conductive shaft can be optimized by providing air flow on the upper surface and side at the same time.

Investigation on Thrust and Torque Generation During Drilling of Hybrid Laminates Composite with Different Stacking Sequences Using Multiobjective Optimization Module

This paper highlights the reinforcement of two different fibers in the manufacturing of hybrid laminate composites. The feasibility of glass and carbon fiber-based hybrid composites is proposed for various high performances due to their versatile mechanical properties. However, anisotropic and non-homogeneity nature creates several machining challenges for manufacturers. It can be regulated through the selection of proper cutting conditions during the machining test. The effect of process constraints like spindle speed (rpm), feed rate (mm/min), and stacking sequences ([Formula: see text] was evaluated for the optimum value of thrust force and Torque during the drilling test. The cost-effective method of hand layup has been used to fabricate the composites. Four different hybrid composites were developed using different layers of carbon fiber and glass fiber layers. The outcomes of variables on machining performances were analyzed by variation of feed rate and speed to acquire the precise holes in the different configurations. The application potential of the proposed composites is evaluated through the machining (drilling) efficiency. The optimal condition for the drilling procedure was investigated using the multiobjective optimization-Grey relation analysis (MOO-GRA) approach. The findings of the confirmatory test show the feasibility of the MOO-GRA module in a machining environment for online and offline quality control.

Proposal of a machining test to evaluate dynamic synchronization error of rotary and linear axes with reversal of rotation direction

The five-axis machining of a free-form surface often contains the reversal of a rotary axis' rotation direction with linear axis synchronized with it. This paper proposes a machining test to quantitatively evaluate the influence of the reversal of rotation direction on the surface geometry. In the five-axis machining, the trajectory of tool position and orientation is firstly given in the workpiece coordinate system by the CAM (Computer-aided Manufacturing) software, and the CNC (Computerized Numerical Control) system converts it to the machine coordinate system to calculate command trajectories. This paper clarifies that the tool path smoothing in the machine coordinate system can potentially cause a large contour error because of the dynamic synchronization error of rotary and linear axes. Although some academic works in the literature presented the smoothing in the workpiece coordinate system, many commercial CNC systems still employ the smoothing in the machine coordinate system, partly because machine tool users or makers do not clearly see how significant this influence can be on the machining accuracy. The proposed machining test enables a user to quantitatively evaluate it. The machining experiment shows that the geometric error of the finished test piece was as large as 0.16 mm under the conventional smoothing in a commercial CNC system, which can be significantly larger than the influence of other typical geometric errors of a five-axis machine tool. This paper shows, by numerical simulation, that the smoothing in the workpiece coordinate system can completely eliminate this contour error.

Nanocellulose Bulk Material Prepared by Steam Treatment and Hot Press Molding: Material Processing and Machining Test

Nanocellulose (NC) has been spotlighted as a new building block of future materials since it has many advantages, such as being lightweight and environment-friendly and having high mechanical properties and heat resistance. However, the use of NC requires an upscale manufacturing process to maintain its advantageous properties. Herein, the process of assembling NC into a macro-scale bulk material was developed through a combination of steam treatment and hot press molding. The steam treatment was applied to an NC paste to energize the hydroxyl groups in the cellulose, followed by two stages of hot press molding, which helped in the self-assembly of NC without adhesives. Cellulose nanocrystals were used as the NC, and circular disk shape specimens were prepared. The mechanical properties of the prepared bulk material were higher than typical engineering plastics. In addition, an end mill machining test of the NC bulk material showed its machinability. This paper showed the processing feasibility of NC bulk material, which can substitute plastics.

Influence of Contact Positioning of Pivot Support on Machining Vibration

The authors have studied support mechanisms for the machining of thin-walled workpieces. Previous studies have shown that the newly proposed pivot support has a vibration suppression effect on flat plate workpieces. This report clarifies the guideline for determining the placement interval for deploying this support on a cylindrical workpiece. Also, a machining test was conducted to compare the damping effect of pivot support with that of conventional rigid body support. As a result, it was found that the pivot support has an equivalent vibration suppression effect as the conventional support has. By using the proposed support, installation can be simplified while maintaining the damping effect.

Influence of Tool Length and Profile Errors on the Inaccuracy of Cubic-Machining Test Results

A cubic-machining test has been proposed to evaluate the geometric errors of rotary axes in five-axis machine tools using a 3 × 3 zone area in the same plane with different tool postures. However, as only the height deviation among the machining zones is detected by evaluating the test results, the machining test results are expected to be affected by some error parameters of tool sides, such as tool length and profile errors, and there is no research investigation on how the tool side error influences the cubic-machining test accuracy. In this study, machining inaccuracies caused by tool length and tool profile errors were investigated. The machining error caused by tool length error was formulated, and an intentional tool length error was introduced in the simulations and actual machining tests. As a result, the formulated and simulated influence of tool length error agreed with the actual machining results. Moreover, it was confirmed that the difference between the simulation result and the actual machining result can be explained by the influence of the tool profile error. This indicates that the accuracy of the cubic-machining test is directly affected by tool side errors.

Fabrication and evaluation of complicated microstructures on cylindrical surface

Various items of roll molds are popularly used to fabricate different kinds of optical films for optoelectronic information and other new and high-tech fields, while the fabrication and evaluation of optical microstructures on a cylindrical roller surface is more difficult than ecumenically manufactured products. In this study, the machinability of microstructures on the roll based on a fast tool servo (FTS) system is investigated. First, the flexible hinge holder for a FTS is designed and its structural parameters are optimized with finite-element analysis and fatigue reliability theory. The tool radius compensation algorithm for complicated microstructures is then deduced based on the surface fitting and bilinear interpolation algorithm of discrete data. Meanwhile, the evaluation index and method are proposed by the medium section method. Finally, a machining test of aspheric arrays on a cylindrical aluminum surface is carried out, and the high quality of the microstructure indicates that the proposed method is able to be used to fabricate optical microstructures.