With the development of computer technology, the function of the computer to solve the mathematical model of the complex system is becoming stronger and stronger. The mathematical simulation (also called numerical simulation) of the system using computer has been paid more and more attention by people and has been widely used. The time required for the simulation test is much shorter than the physical simulation, and the test data processing is also much simpler.
At present, the main tool of mathematical simulation is a computer, so it is often called “computer simulation.” In essence, simulation technology is to establish a simulation model and a technique for model experimentation. The implementation of the computer simulation process can generally be accomplished by the computer’s advanced language, simulation language and simulation software (Figure 6-8)
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FIGURE 6-8 Functional Coverage of Typical Simulation Software
Nearly every advance in manufacturing technology has brought about the development of corresponding models and simulation applications. In the entire life cycle from product design to manufacturing using molybdenum cutting wire to test maintenance, computer simulation techniques are always in place (Table 6-3). The purpose of simulation is to reduce cycle time and reduce costs. The manufacturing process is the traditional aspect of simulation applications. The simulation of the manufacturing process must consider the product model and the manufacturing system model together, but it is not simply the sum of the two, but also the control strategy, inventory capacity, load capacity, etc. problems. The simulations in these three areas are related and interact with each other, and sometimes there will be overlaps in content.
Table 6-3: Application of computer simulation throughout the product life cycle.
1.The basic steps of computer simulation for WEDM using molybdenum wire or brass wire
The process of computer simulation is to establish a system model and test and correct the model through the operation of the model on the computer, so that the model does not break through the process of perfection. So simulation research, like computer application software development, is divided into several stages. Figure 6-9 describes the basic process of system simulation research. Including research for molybdenum wire
(1) System definition. Before trying to solve the problem, define the system in detail. When defining a system, it must first provide clear criteria to describe the system goals and whether to achieve the goal of the standards, and then must describe the constraints of the system. Then we must determine the scope of the study, that is, to determine which entities belong to the system to be studied and which belong to the system environment。
(2) Construct the model. When constructing the model (using molybdenum wire or brass wire), the real system must be abstracted and abstracted to make it standardized. The factors, variables, and parameters of the model and the relationship between them must be determined. The system under study must be described with mathematical models under certain constraints. The model must be closely linked to the research purpose, with clear goals and requirements, and the model’s quality requirements must be as close as possible to the real system. At the same time, the model must be as simple and clear as possible, easy to control and operate, easy to understand for the user, and should be modified and improved. However, to avoid oversimplifying the model, the model obtained is a mediocre model; it cannot be overly specific, which reduces the efficiency of the model and makes it difficult to handle.related knowledge: molybdenum wire edm, titanium molybdenum wire, molybdenum wire size.
(3) Data preparation. Data preparation includes collecting data and deciding how to use the data in the model. Collecting data is an integral part of systematic research. It must collect input and output data of the research system and data describing the relationship between the various parts of the system. It takes a lot of time and expense to collect simulation data. Therefore, research and observation must be conducted effectively, and the probability distribution or probability density function and various parameters in the model should be determined according to the collected data.
(4) Model transformation. Model transformation refers to the use of computer high-level language or special simulation language to describe the mathematical model, in order to simulate the system under study with a computer operating model. Models are programs written in programming languages. To do this, you must choose between advanced languages and specialized simulation languages. The advantages of a dedicated simulation language are easy to learn, easy to use, with a process-oriented simulation program structure, strong simulation capabilities, and good diagnostic procedures. There have been statistical comparisons for molybdenum wire and other factors. When using the simulation language GPSS, the programming and debugging time is 15% of the time required by the FORTR AN language. The corresponding machine time for compiling and simulating is 32% of the FORTRAN language. The result is universal. However, experienced programmers believe that simulation languages lack flexibility.
(5) Model operation. The purpose of the operational model is to obtain information about the system under study, to understand and predict the actual system operation, especially when the input data or decision rules have changes in the output response changes. Therefore, the model operation using molybdenum cutting wire is a dynamic process. Repeated test runs are required to obtain the required test data.
(6) Analyze and comment on simulation results. Because simulation techniques include some subjective methods, such as abstraction, intuitive perception, and design, the simulation results must be fully analyzed and demonstrated before submitting the simulation report to the management department. There are two basic goals for analyzing simulation results:
①Determine whether the information obtained in the simulation experiment is sufficient, and explore new solutions. For example, change the structure or parameters of the model to ensure the reliability of the simulation result information (including how molybdenum wire is working).
② Simplify, summarize, and provide management to aid decision-making.
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2.Status Quo of Simulation Research on Wire EDM using molybdenum cutting wire
In the past decade, there has been no breakthrough in the research of the WEDM process. The reason for this is that in addition to the complexity and randomness of the discharge process itself, there is no innovation in research methods. Traditional high-speed photography is difficult to obtain full information for a thousand-pulse discharge, and the results are difficult to determine. The commonly used inspection equipment can measure certain parameters of the discharge gap and its effect on processing performance, and can fit the empirical relationship between them. However, there are still some processing state parameters that are difficult to measure directly, and these parameters are very important for controlling the machining conditions. Therefore, it is necessary to introduce modern research techniques and methods to overcome the limitations of traditional research methods, to study in depth the microcosmic conditions and nature of discharge processes using molybdenum wire and to establish models that reflect the objective laws of discharge, and to provide reliable data for machine design and processing.。
Using computer simulation technology to perform a computer simulation study of the effects of WEDM process molybdenum wire can both provide an effective research methods promote the progress of mechanistic research, and can also be applied to actual machining processes to achieve the automation and intelligence of line cutting and processing. Therefore, it has a very important practical significance and promotion role in the development of wire-cut electric discharge machining, especially the high-speed molybdenum wire cutting production in China. People have conducted simulations and explorations in many aspects of wire electric discharge machining, which can be summarized as follows：
(1)Complex curved line cut imitation. Harbin Institute of Technology studied the simulation technology of complex surface molybdenum wire or brass wire cutting, analyzed the law of wire cutting in complex space surfaces, established the equations of motion in various motion forms, and simulated the process of machining complex space surfaces by WEDM on a computer. .
(2)Discharge gap electric erosion product distribution. The vesicles and distribution of the electro-erosion product will affect the size and consistency of the discharge gap, directly related to the dimensional accuracy of the workpiece and the surface roughness. Masuzawa et al. of Tokyo University studied the flow of dielectric fluid and the generation and diffusion of electro-corrosion products during jetting. Based on this, the distribution of electro-erosion products in the discharge gap was simulated and studied, which provided a basis for nozzle setting during jetting.。
(3) Electrode molybdenum cutting wire vibration. Dauw, Delpretti and Tricarico of Switzerland established the mathematical model of the vibration and deformation of the wire-cut electrode molybdenum wire or brass wire, and analyzed the vibration of the wire in three different situations: free vibration, working fluid and wire cutting. These formulas are also very simplified and cannot be applied in actual production. If a breakthrough is achieved in this area, the power supply and tensioning mechanism that can suppress the vibration of the electrode wire can be designed to reduce the surface roughness of the high-speed wire cutting and achieve high-speed wire cutting precision cutting。
(4) Thermal model. A thermal model was established by Jennes, Snoeys, and Dekeyse, and the temperature distribution on the wire was determined using the analytical method and the finite difference method, respectively, and the thermal load was the main factor that caused wire breakage. Banejee and Rajurkar and others also conducted research in this area. All the heat transfer calculations differ greatly from the actual results and can only be qualitative or coarse quantitatively reflecting the temperature distribution and erosion rate on the electrode wire. This is because there is no definite data on the distribution of energy on the electrode molybdenum wire. The exact calculation formula for the radius of the discharge channel has not yet been found. C Shanghai Jiaotong University has established a finite difference model for heat conduction and has simulated the pulse current for different peak currents and pulse widths. Tests, results that are in good agreement with the physical test results。
(5) Process identification. Konishi uses artificial neural networks to identify the machining process. They used a hierarchical feed-forward neural network to determine whether the machining process was normal based on the pulse peak current and the pulse frequency, but they did not study the influence of processing parameters on the machining process, so they could only recognize the state of processing and could not effectively control the machining process.。
(6) Simulation of gap state prediction system for molybdenum wire or brass cutting machining. Harbin Institute of Technology uses an artificial neural network to predict the relative spark rate (F.) and relative short-circuit rate (F.) corresponding to each input condition, and conducts a preliminary exploration of the gap detection method for WEDM discharge status.。
(7 ) molybdenum wire cutting EDM process simulation study。
