来源：万方数据
       Improving the processing efficiency of lapping and polishing is a common concern. Because the processing time of lapping and polishing is very long, the amount of removal per unit time is very small, and the surface roughness of the previous process has a great influence on the machining allowance of the later process. In this case, the high efficiency of a single process does not guarantee the overall high efficiency of the entire process. This paper proposes a new idea to improve the efficiency of lapping and polishing. By establishing a process database, we aim to reduce the total processing time and optimize the process combination. In this paper, the strategy and implementation method of process combination optimization are given, and a typical example is analyzed. The results show that this process combination optimization method is effective.
       With the development of material science and technology, new materials have been more and more widely used in various components, and people's requirements for machining accuracy are getting higher and higher. Ultra-precision lapping and polishing technology uses the "evolutionary" machining principle to achieve ultra-smooth and perfect surfaces with high precision and close to geometry, and has a wide range of applications in modern material processing. At present, the final processing of silicon wafers, crystal oscillator substrates, lithium niobate substrates, lithium tantalate substrates and other crystal substrates of large-scale integrated circuits adopts ultra-precision plane lapping and polishing technology. With the popularization of the application of components and the continuous increase of production batches, the need to achieve high-quality and high-efficiency processing is becoming more and more urgent.
       In this research field, many scholars and experts have done a lot of research on the way of lapping and polishing, the improvement of abrasives and slurries, and the optimization of process parameters of a single process, so that the efficiency of lapping and polishing has been continuously improved. The method of lapping and polishing is used for processing, which usually includes four processes: rough lapping, fine lapping, rough polishing and fine polishing. Of course, sometimes one or two of these processes are omitted as needed, but in general, it is a multi-process process. Because the processing time of lapping and polishing is very long, the amount of removal per unit time is very small, and the more to the later process, the smaller the amount of removal per unit time, and the surface roughness of the previous process has a great influence on the machining allowance of the later process. In this case, the high efficiency of a single process cannot guarantee the overall high efficiency of the entire machining process, which has the problem of optimizing the combination of processes. Although the computer-aided process design has been widely used in the machinery manufacturing industry, and produced good results, but as far as precision lapping and polishing are concerned, for a long time, what kind of process route is selected, and the processing parameters of the specific process are judged by the experience of workers, which has caused too much dependence on experienced workers, and the process route selected according to experience, and the process parameters of the specific process also have their randomness, which is not necessarily optimized and reasonable. Therefore, with the shortest total processing time as the optimization goal, this paper uses computer technology and database technology to conduct a preliminary study on the optimization of the process combination of grinding and polishing.
       The process database is the basis for the optimization of process combinations. So far, there is no dedicated database or process manual for ultra-precision lapping and polishing in China. Only through a large number of experiments to obtain data, and then the application of mathematical statistics to the experimental data for comprehensive analysis, induction, and the relationship between ultra-precision lapping and polishing process parameters and surface roughness and removal rate as the basis for processing. In order to facilitate the storage and management of data and facilitate the application in process combination optimization, the experimental data are divided into four groups according to rough grinding, fine lapping, rough polishing and fine polishing, and are explained by classification numbers. For a processing material, each group stores 4~6 kinds of process parameters, and in terms of the base table design of the database, a process master table and a process schedule are built, in addition to the slurry schedule, the lapping disc schedule, the material schedule and the optimization history table. The type, particle size, concentration and composition of the slurry are stored in the slurry schedule, and when the process is optimized, you can first find out whether there is the same record in the optimization history table, and if so, you can use it directly. The header design of the process master table and the process schedule is shown in Table 1 and Table 2. When optimizing the process combination, it is mainly based on the process master table. Once the optimization results are obtained, the relevant parameters are obtained from the operation schedule for use in process control. In order to improve the speed of retrieval, the corresponding indexes were created according to the surface roughness and removal rate. From the point of view of economy and ease of maintenance, SQL Server 2000 is used for the back-end database.
       根据工件所要达到的粗糙度，可以确定终加工工序。根据加工所要达到的表面粗糙度数值，在数据库中搜寻终加工的工序，确定终加工工序的条件为：Rae(可达到值)<Rao(要求值)，并且去除率最高。终加工工序一旦确定，可能的工序组合也就相应的确定下来。具体如如表3所示。例如，若终加工是精抛，那么可能的工艺组合一共有八种。
       Taking the total processing time as the optimization objective function, that is, the sum of the processing time of each process, the conversion time between processes is ignored here, one is to reduce the complexity of the system establishment, and the other is to consider the actual situation of ultra-precision lapping and polishing, the processing time is much greater than the time of the rest of the auxiliary processing. Set the total processing time to T, and the processing time of each process is ti; That is, the minimum value of the whole processing time is equal to the minimum value of the sum of the processing time of each process, wherein, there are up to four processes, and at least one process, so n is an integer value between 1~4. It should be emphasized that the minimum value of the entire processing time is not equal to the sum of the minimum processing time of each process. Because of the particularity of lapping and polishing, the machining allowance of each process has a great relationship with the surface roughness achieved by the previous process, so it cannot be simplified to the sum of the minimum processing time of each process. That is, the constraint of optimization is that the sum of the machining allowances of each operation should be equal to the machining allowances required by the workpiece, and the machining allowances of the initial machining operations are determined accordingly. Let the machining allowance required by the workpiece be S, the machining allowance of each process is Si, and the machining allowance of the initial machining process is S1, then if n=1, then S1=S. Let the removal rate of the initial process be q1, and t1 can be expressed as the processing time of the initial process.
       对具体加工来说，即使确定初始加工和终加工工序，仍有可能会出现四种情况，就是工件经过一道，两道，三道，四道加工工序完成整个加工。除了初始加工工序外，以后各工序的加工余量按如下方式确定k为加工余量和初始表面粗糙度的系数比。一般认为后面的工序应去除前一工序的变质层，考虑到在表面粗糙度的测量指标中，Rt值一般为Ra值的7～8倍，再考虑到加工过程对亚表层的影响，根据经验可以取k=15～25。当表面质量要求高时，k取值大一些，反之可以取小一些。设某一工序的去除率为qi，则该工序的加工时间为ti可以表示为因此，总的加工时间丁就可以表示为若某一工序组合的总的加工时间T最小，则该工序组合为最优工序组合。工序组合优化的流程如图1所示。
       某元件的加工实验数据如表4所示。加工余量为0.1mm，要求表面粗糙度达到0．02μm。进行工艺组合优化时，取k=20。优化结果为当工序组合为1-4-6-7时，加工总时间最短，为490min。而每个阶段均采用去除率最大的工序组合为1-3-5-7，此时的加工总时间为561min，每个阶段均采用表面 粗糙度最小的工序组合为2-4-6-8，此时的加工总时间为607min。因此可知，通过工艺组合优化能够有效地提高整体加工效率。
       Due to the long processing time of lapping and polishing, the amount of removal per unit time is very small, and the surface roughness of the previous process has a great influence on the machining allowance of the subsequent process. In this case, the high efficiency of a single process does not guarantee the overall high efficiency of the entire process. In this paper, the process combination optimization is realized by establishing the process database and using the computer-aided method, and the results show that the overall processing time can be effectively shortened and the processing efficiency can be improved through the process combination optimization.