Shape Of Workpiece Research Articles

Construction of a flat workpiece for manufacturing a turn of the right helicoid

In technology, a common helical surface is a right closed helicoid (auger). It is formed by a helical movement of a horizontal segment, provided that the axis of the auger crosses at one of its ends. The formation of the surface of an open helicoid is similar but the segment must intersect the axis and be located at a constant distance from it. It is known from differential geometry that the helical surface can be transformed by bending to the surface of rotation. This fact is taken as the basis for calculating the geometric shape of a flat workpiece. The surface of the open helicoid is non-disjointed, so the shape of the workpiece must be found in such a way as to minimize plastic deformations during surface formation. Parametric equations of continuous flexion of the turn of an open helicoid into the section of a single-cavity hyperboloid of rotation have been derived. Continuous bending can be represented as a gradual deformation of the turn while reducing its step. The meridian of hyperboloid rotation is the corresponding area of hyperbola. The hyperboloid section is proposed to be approximated by the surface of the truncated cone. This approximation will be more accurate in the area of the hyperbole where it asymptotically approaches the segment of the right line. After selecting a cone, it becomes possible to determine its size and build its exact sweep since the cone is a unfolding surface. The sweep is constructed in the form of a flat ring with a cut sector and will be the desired flat workpiece to form a turn of the auger from it. Most accurately, the surface of the turn of the open helicoid can be made by stamping the workpiece of the resulting form. For small-scale production of the helical surface of an open helicoid, it is advisable to weld flat rings together and, during installation, stretch along the shaft while twisting around its axis. The accuracy of the obtained surface will depend on the accuracy of the approximation of the hyperboloid section of rotation with a truncated cone, which is the topic of this work.

Research on the Method of Reducing Dynamic Cutting Force in Aspheric Machining.

With the rapid development of photoelectric communication and other fields, the demand for high-precision aspheric mirrors has been increasing. Predicting dynamic cutting forces is vital in selecting machining parameters and also affects the surface quality of the machined surface. This study comprehensively considers the effects of different cutting parameters and workpiece shape parameters on dynamic cutting force. The actual width of cut, depth of cut, and shear angle are modelled while considering the effects of vibration. A dynamic cutting-force model considering the aforementioned factors is then established. Using experimental results, the model accurately predicts the average value of dynamic cutting force under different parameters and the range of fluctuation of dynamic cutting force, with a controlled relative error of about 15%. The influence of workpiece shape and workpiece radial size on dynamic cutting force is also considered. The experimental results show that the greater the surface slope, the more dramatic the dynamic cutting force fluctuations. This lays the foundation for subsequent writing on vibration suppression interpolation algorithms. The influence of the radius of the tool tip on dynamic cutting forces leads to the conclusion that to achieve the goal of reducing the fluctuation of cutting forces, diamond tools with different parameters should be selected for different feed rates. Finally, a new interpolation-point planning algorithm is used to optimize the position of interpolation points in the machining process. This proves the reliability and practicability of the optimization algorithm. The results of this study are of great significance to the processing of high-reflectivity spherical/aspheric surfaces.

FEATURES OF DEFORMING OF COMPOSITE INDUCTORS DURING ELECTROMAGNETIC PROCESSING OF MATERIALS

Introduction. The development of many branches of mechanical engineering at the current stage requires the development and application of new technologies that are characterized by high energy efficiency and a small amount of waste. Such technologies include those that use electromagnetic field energy. The energy of the electromagnetic field can be used to change the shape of workpieces, to connect individual structural elements (for example, by welding), to control the physical properties of the material (for example, by induction heating), etc. Carrying out calculation studies at the stage of designing and proving the appropriate technological equipment allows determining the rational values of key parameters, which ensures the achievement of the goals of the technological operation and the operability of the equipment. Purpose. When the energy of the electromagnetic field is used to exert a force on the processed workpiece, the technological equipment is equally subject to force. The purpose of the article is to create effective methods of calculating the strength of technological equipment together with the workpiece, and conducting the corresponding calculation analysis is an urgent task in the scientific and practical sense. Results. The article proposes an effective method of analyzing the elastic-plastic deformation of composite structures under the influence of an electromagnetic field. The general mathematical formulation of the coupled problem of the deformation of conductive bodies in the presence of an electromagnetic field is considered. To construct a numerical solution method, the initial problem is reduced to finding the minimum of the total energy of the system. The finite element method is used as a numerical solution method. The proposed method is applied to the analysis of the deformation of the "inductor-workpiece" system of the technological operation of magnetic pulse processing of metals. Conclusions. Some results are presented that allow making certain recommendations regarding the design and application of technological operations of a similar class.

Calibration of a circular structured light measurement system based on a multi-diameter calibrator

To solve the measurement problems of the inner shape of large-scale workpieces, such as excavators with movable arms, this paper proposes an inner shape measurement method based on circular structured light. First, the center of the circular laser stripe is extracted based on a modified Steger method. Second, a multi-diameter concentric calibration gauge design is used to calibrate the optical plane of the proposed system and address the problem of the optical plane deviation and motion error in the 1D linear stage of the traditional calibration process. Finally, the experiments are conducted. The corresponding experimental results demonstrate that the proposed measurement method facilitates a fast calibration of the camera and an efficient extraction of the center of the light stripe, resulting in a relative error of less than 0.012%. The measurement method can be further applied to deep-hole workpieces, such as steel tubes and natural gas tube lines, among others.

Multiphysics Simulation of the Shape Prediction and Material Removal Rate in Electrochemical Machining Process

ABSTRACT The electrochemical machining process involves electrical and chemical processes while removing materials from the workpiece. Electrochemical machining (ECM) lacks accurate models for predicting the shape and material removal rate during the ECM process. This limits the ability to optimise the process and predict the final product geometry, which is crucial for industrial applications. This research mainly focused on the modelling and simulation of material removal from the workpiece using COMSOL Multiphysics software. This research involves developing a mathematical model that describes ECM’s electrical, chemical, and mechanical interactions. The model is based on electrochemistry, fluid dynamics, and solid mechanics principles and will be solved using numerical simulation techniques. Various workpiece materials considered in this investigation include Aluminium, Nickel, Stainless Steel, and Tungsten, whereas copper is electrode material. The effects of the various parameters, such as workpiece materials, the voltage applied during machining, and electrolyte conductivity on the material removal rate are being investigated. In addition, the shape of the machined workpiece is also predicted. The results of this research provide a deeper understanding of the underlying physics of the ECM process and lead to the development of more accurate models for predicting the shape and material removal rate during ECM.

Prediction of Process Parameters for Ultra-Precision Optical Processing Based on Dual-Stacked LSTM

High-precision and large-aperture optical components have important applications in modern optics and optoelectronics. However, the traditional continuous polishing technology of optical components relies heavily on the processing experience of the processing personnel. The surface shape of the pitch lap is judged by frequent offline measurement of the surface shape of the processing workpiece, and then the processing personnel judges how to adjust the next process parameters through their own experience, which leads to uncertainty of processing time and low processing efficiency. In this paper, based on the historical processing data, including the surface parameters of workpieces and process parameters before and after each processing, a machine learning-based prediction method of process parameters is proposed. At first, taking the surface shape of the pitch lap as the hidden parameter of the model, a time-series mathematical model of the forward and reverse processing processes is constructed. Theoretical and experimental results show that the prediction method in this paper can effectively reduce the processing time and improve the stability of the workpiece quality.

Augmented Reality-Based System for Skill Transfer of Workpiece Fixturing in Turning Operations

For machining operations, preparation work called a “setting operation” is always required in advance. The setting operation, which affects the lead time and machining accuracy, strongly depends on the skill level of the operator. Therefore, to improve the quality of machining operations, skill transfer is necessary by extracting and generalizing the skills related to the setting operation. In addition, a variety of accidents often occur during the setting operation. This can lead to machine tool failure or a serious incident involving the operator. Thus, skill transfer to an unskilled operator is also important for work safety. On the other hand, augmented reality (AR) is a promising human-computer interaction technology to support skill transfer at the manufacturing site. An AR technology generally overlays virtual images on the real-world environment. In this study, an AR-based system is developed to demonstrate a recommended workpiece fixturing method in turning operations for assisting unskilled operators as the first step of skill transfer. In turning operations, two types of fixturing are usually assumed: outer diameter clamping and inner diameter clamping. The dimensions of the targeted product shape are detected, and the workpiece shape is obtained. The removal volume to be machined is calculated as the difference between the targeted product shape and workpiece shape. The fixturing method is determined to avoid contact between the removal volume and the assumed jaw. The results of a case study show that the developed AR-based system is effective for skill transfer of workpiece fixturing by demonstrating the recommended fixturing method using skills acquired from operators.

Computer Aided Process Planning for Rough Machining Based on Machine Learning with Certainty Evaluation of Inferred Results

Process planning is well known as the key toward achieving highly efficient machining. However, it is difficult to standardize machining skills for process planning, which depend heavily on skilled operators. Hence, in a previous study, a computer aided process planning (CAPP) system using machine learning is developed to determine the operation parameters for finish machining of dies and molds. On the other hand, in rough machining, it is assumed that some machining operations are conducted sequentially using a respective tool according to the workpiece shape, which induces a much higher complexity in process planning. Therefore, in this study, machine learning is adopted to determine operation parameters for rough machining. The developed CAPP system converts the removal volume into a voxel model and infers a machining operation for each voxel. The inferred machining operation is visualized using different colors and identified corresponding to the voxel. Finally, the removal volume is classified using three different machining operations. However, machine learning is said to have a critical problem in that it is difficult to understand the reasons for the inferred results. Hence, it is necessary for the CAPP system to demonstrate the certainty level of the determined operation parameters. Thus, this study proposes a method for calculating the degree of certainty. If an artificial neural network is trained sufficiently, similar inferred results would always be obtained. Consequently, by using the Monte Carlo dropout to delete weights at random, the certainty level is defined as the variance of the inferred results. To verify the usefulness of the CAPP system, a case study is conducted by assuming rough machining of dies and molds. The results confirm that the machining operations are inferred with high accuracy, and the proposed method is effective for evaluating the certainty of the inferred results.

Justification for choice of semi-finished product shape for hammer stamping of wrench forging

The possible shapes of workpieces and the effect of the number of finite elements during mesh generation on the speed of computer calculations, on the formation of defects in the form of folds, and also on the quantitative characteristics of the studied parameters of the forging are considered. The choice of the shape and sizes of the initial workpiece and semifinished product for subsequent hammer stamping is substantiated based on the simulation results.

加工コイル設計のための電磁かしめシミュレーションの開発

Electromagnetic crimping is a crimping method for applying uniform crimping force to metal parts in a shorter forming time than conventional press crimping. It is difficult to measure and determine the crimping force acting on metal parts because the crimping force affected by the magnetic field and Lorentz force induced by current in a forming coil is invisible. Additionally, current is affected by the circuit characteristics of an electromagnetic forming instrument and the shape of a forming coil. Hence, it is difficult to design a forming coil. In this study, simulation procedures were developed for designing a forming coil. First, the circuit characteristics of an electromagnetic forming instrument were identified to predict current in a forming coil accurately. Second, electromagnetic crimping was simulated by the coupled analysis of a circuit simulation to consider the effects of circuit characteristics and the finite element method to consider shape of a forming coil. Finally, a forming coil for electromagnetic crimping was designed by using the developed simulation procedures. Required current in the designed coil was determined. The shape of the crimped workpiece in the simulation was similar to an experimentally crimped sample. These results indicate that the developed simulation procedures are useful for designing the shape of a forming coil.

A Three-Dimensional Structured Light Vision System by Using a Combination of Single-Line and Three-Line Lasers

A multi-line structured light measurement method that combines a single-line and a three-line laser, in which precision sliding rails and displacement measurement equipment are not required, is proposed in this paper. During the measurement, the single-line structured light projects onto the surface of an object and the three-line structured light remains fixed. The single-line laser is moved and intersects with the three-line laser to form three intersection points. The single-line light plane can be solved using the camera coordinates of three intersection points, thus completing the real-time calibration of the scanned light plane. The single-line laser can be scanned at any angle to determine the overall complete three-dimensional (3D) shape of the object during the process. Experimental results show that this method overcomes the difficulty of obtaining information about certain angles and locations and can effectively recover the 3D shape of the object. The measurement system's repetition error is under 0.16 mm, which is sufficient to measure the 3D shapes of complicated workpieces.

Design of Structural Steel Components According to Manufacturing Possibilities of the Robot-Guided DED-Arc Process

Additive manufacturing with the DED-arc process offers limited freedom in terms of the geometric shape of work pieces. The process and fabrication systems restrict the part geometry producible, which must be taken into account during design already. For this reason, a design process was investigated in which geometry generation is based on a self-organizing system. The aim of using a self-organizing system is the possibility to directly control the geometry-defining points. Next to load cases, the design method considers geometric boundary conditions from the production process when generating the geometry. In order to identify these geometrical constraints from production experimentally, a concept of Case Study Demonstrators was applied. This was used to investigate how path planning and production can be carried out for specific geometrical features and to identify restraints of the process and the manufacturing system, e.g., smallest producible wall thickness and overhangs. Subsequently, the obtained restraints were considered as boundary conditions for the design process and were included in the modification of an example geometry. By applying the presented design method, it was possible to maintain a minimum wall thickness throughout the structure while generating a topologically optimized geometry. In contrast to compliance with the minimum wall thickness, no satisfactory behavioral rule could be found for limiting the overhang.

Research on abrasive pool machining method based on gas–solid two-phase flow

For complex curved difficult-to-machine parts, a new method based on pneumatic suspension abrasive pool bright finishing processing is proposed, using the mixing of pneumatic suspension abrasive, the workpiece surface, and fluidized abrasive to produce relative motion velocity, so that the solid particles and workpiece surface microscopic two-body abrasive wear to achieve the effect of precision machining. The experimental test material is the widely used Q235 steel plate. The experimental parameters include workpiece shape (round tube, square tube, cylindrical), abrasive particle size (24, 80, 120 mesh count), gas–solid two-phase flow pattern (dispersion fluidization state, turbulent fluidization state, spurting fluidization state), abrasive particle shape (sphere, irregular), and spindle speed (600, 900, 1200 rpm). An orthogonal test was designed according to the experimental parameters, and the degree of influence of each parameter on the processing of the abrasive cell was evaluated by the roughness of the workpiece surface together with the scanning electron microscope (SEM) micrograph of the workpiece surface, and the optimal combination of parameters was judged using the extreme difference method as well as the factor trend diagram. The results show that under the present experimental conditions, the workpiece surface roughness (Ra) can reach a minimum value of 0.4 μm. The feasibility of gas–solid two-phase flow processing is demonstrated from an experimental point of view, and the advantages of abrasive cell processing are explored.

Automated feed rate optimization with consideration of angular velocity according to workpiece shape

Selecting the proper cutting conditions for milling parts is one of the most important tasks in setting up manufacturing to achieve minimum machining times and to ensure the desired tool life. This is particularly important when machining parts made of difficult-to-cut materials. However, if the required technological conditions are not achieved due to the shape of the toolpath itself, even the conventional setting of the technological conditions will not help achieve the optimum result. It is therefore essential to ensure that the technological conditions are achieved directly at the contact point between the tool and the workpiece, which is often forgotten in automatic toolpath preparation. This paper therefore presents a specific solution for optimizing the feed rate right at the contact point between the workpiece and the tool to maintain a constant feed per tooth. The work contributes to the investigation of the relationship between the tool diameter and the shape of the machined surface when a constant feed per tooth is required as well. The achievement of feed rate is performed by tests on the machine tool and the benefits of using the optimization of feed rate are further discussed.

Electrochemical Machining of Curvilinear Surfaces of Revolution: Analysis, Modelling, and Process Control.

The paper presents the authors' model for the adaptive control of the electrochemical machining (ECM) process of machining the rotary (axisymmetric) elements of any curvilinear shape, using the results of theoretical computer simulation of this process. Computer simulations have been based on the authors' model of the ECM of rotary surfaces of any curvilinear shape. The quasi- 3D ECM model proposed facilitates an analysis of physical phenomena which occur in the interelectrode gap. Mathematical ECM modelling has been based on the application of the equation of the workpiece shape evolution and on the system of partial differential equations resulting from the principle of mass conservation, momentum and the law of conservation of energy describing a flow of the mixture of electrolyte in the interelectrode gap. A solution to the problem has been developed with analytical and numerical integration. For the rotary hemispheric surface, in a set time, the local machining of a change in the interelectrode gap thickness and characteristic physicochemical parameters were determined, especially static pressure distribution, electrolyte flow velocity, temperature and volumetric gas phase concentration as well as current density. The simulation results were experimentally verified by determining the distribution of the shape deviation (WP) calculated from the process computer simulation and after the ECM. Applying the adaptive control of the ECM process has facilitated, based on the simulations made, enhancing the process stability and avoiding the occurrence of critical states.

Formation mechanism of concave and convex surface shapes in double-sided lapping

Double-sided lapping process is a key technology for obtaining high efficiency and flatness in fabricating plane-parallel workpiece surfaces, such as wafers, optical windows, seal rings, etc. However, the formation of the concave and convex surface shapes of workpieces was rarely investigated in the previous research, and the mechanism was unknown. This paper establishes a new kinematic model to clarify the formation mechanism of concave and convex surface shapes, in which the workpiece eccentricity and rotation in the planetary wheel are considered for the first time. The measurement and control method of workpiece rotational speed in the planetary wheel is proposed. The formation of the concave and convex surface shapes is validated experimentally by adjusting the rotational speed of the workpiece, and the results show a good consistency with the calculation results. A flatness error convergency method is proposed based on the surface shape formation mechanism, and flatness superior to 5 µm is achieved on Φ200 × 2 mm thin copper substrates.

Deliberate Surface Treatment of Zirconium Dioxide with Abrasive Brushing Tools

Brushing with bonded abrasives is a flexible finishing process used to reduce the roughness of technical surfaces. Although industrially widespread, especially for the finishing of metallic surfaces, insufficient knowledge of the motion, the material removal, and the wear behavior of the abrasive filaments complicates predictions of the work result. In particular, the reliable finishing of ceramics with bonded diamond grains proves difficult due to increased material removal rates, quickly leading to undesirable changes in the workpiece geometry. Based on technological investigations with abrasive brushing tools, this article provides insights into the surface finishing of zirconium dioxide with a focus on finding compromises between reduction in the surface roughness and alteration of the workpiece shape.

Modelling and simulation of the 3D surface topography in ultra-precision flycutting machining

A simulation model of the 3D surface topography in ultra-precision flycutting machining is built in this paper. The influences of the cutting parameters, the cutting interference phenomenon, the relative vibration between the tool tip and the workpiece and the workpiece shape are analysed. The formation mechanism of the stripes along the cutting direction and the feed direction is explained. The simulation model can be used to optimize the cutting process of the ultra-precision flycutting machining, which avoids time and money consuming cutting experiments, and can also provide new ideas for tracing the source of the stripes on the surface topography.

A Voxel-Based End Milling Simulation Method to Analyze the Elastic Deformation of a Workpiece

Abstract A new method to analyze the elastic deformation of a workpiece during end milling is proposed. One of the advantages of this method is the possibility of easily combining it with a voxel-based milling simulation, which is often used to predict cutting force, and to predict machining error due to workpiece deflection. With this method, the workpiece is discretely represented by voxels connected to their neighboring voxels with beam elements. Although the finite element method (FEM) is generally used for deformation analysis, it requires substantial time to analyze the deformation. In contrast, the proposed method does not require much time for remeshing, as the workpiece shape change is represented by removing voxels, and the stiffness matrix can be easily updated from the stiffness matrix obtained before the shape change. By conducting the preliminary analysis using coarse voxels and estimating the initial value of the solution, our method also reduces the number of iterations required to determine the deformation. The proposed method was integrated into the voxel-based cutting force prediction method in order to simulate the workpiece deformation caused by the cutting force. Therefore, the cutting force and the resulting workpiece deflection are seamlessly predicted using a voxel model. The results of a verification experiment showed that the analyzed workpiece deformation was in rough agreement with the measured deformation. Our future work is to predict the machining error induced by the workpiece elastic deformation based on this method and to integrate it with our previous work on the prediction of machining error induced by elastic deformation of the tool.

A robot-driven automatic scribing method via three-dimensional measurement sensor

The evaluation of the complex workpiece allowance and the scribing the datum line now extremely rely on manual operation. The manual operation is time-consuming and prone to misjudgment, and has a large blind area. To solve these problems, the robot-driven automatic scribing via three-dimensional (3D) measurement sensor method (RAS3DM) is proposed. In this study, we solve the key technology of calibrating the rigid transformation between the 3D measurement coordinate system and laser scribing coordinate system. And a fast and accurate multiple coordinate systems calibration and unification method is proposed, a fixed calibration target and a mobile calibration target are designed. Hence, a structured-light 3D shape measurement sensor driven by an industrial robot with six-degree of freedom (6-DOF) is utilized to obtain the complete 3D shape of the complex workpiece automatically, and then by comparing the 3D measurement result and the standard CAD model, the laser scribing equipment can automatically scribe the mechanical processing datum line to assist further processing. The experiment results illustrate that the proposed method is accurate and efficient: the complex workpiece allowance evaluation and scribing time is about 5 times faster than that of manual operation, and the scribing accuracy is 0.15mm, which can effectively solve various problems of manual scribing. The proposed RAS3DM can be widely applied in factories and laboratories.