Abstract: In modern production activities, people have increasingly high requirements for the precision of component structures. Therefore, precision and ultra precision machining of devices has become a hot research topic. With the development of computer technology, precision control has become a reality. The selection of grinding wheels has become a major factor limiting the development of precision and ultra precision machining. In this article, we introduce the definitions of precision and ultra precision machining, analyze the working mechanism of precision grinding machining, and based on this, study the method of selecting grinding wheels for precision machining. These studies are of great significance for the development and application of precision and ultra precision grinding, and have good practical value.
Keywords: precision machining; Grinding mechanism; grinding wheel
Introduction
With the development of the times, more and more work instruments are moving towards ultra miniaturization and high precision. To achieve the manufacturing of these instruments, it is first necessary to produce highly precise working components. Therefore, precision and ultra precision component processing are receiving increasing attention from people.
Grinding is a commonly used machining method in mechanical processing. Due to the fact that the current grinding process is mainly completed by machine tools, there is still a certain distance from precision. Therefore, it is necessary to conduct research on precision and ultra precision grinding processing.
This article aims to analyze the characteristics and mechanisms of precision and ultra precision grinding, and explore the selection criteria and methods of grinding wheels.
1. Precision and ultra precision analysis
In the 1960s, with the development of a large number of emerging technologies such as nuclear energy and large-scale integrated circuits, there was an urgent need for a processing technology that could achieve extremely high precision component processing. Precision and ultra precision machining arise from this.
After the birth of precision and ultra precision machining technology, it quickly gained widespread application in many fields such as computer science and aerospace. With years of development, precision and ultra precision machining technology has made tremendous progress. At present, the machining precision of this processing technology has reached the nanometer level and is developing towards higher precision levels.
Due to the high requirements for machining precision in precision and ultra precision machining, there are significant changes in control systems, servo systems, measurement systems, and other aspects compared to other machining technologies. Especially the application of computer control systems not only meets the requirements of micro error precision machining, but also greatly promotes the application of such intelligent control systems in other machining fields, which is of great significance for the development of the information age.
2. Analysis of Precision Grinding Mechanism
Grinding is a widely used cutting method in modern production. Due to the increasingly urgent demand for high-precision components in modern instruments, research on precision and ultra precision grinding is also becoming increasingly popular. The mechanisms of precision and ultra precision grinding are mainly divided into two aspects: micro machining and continuous machining.
2.1 Microfabrication of Device Structures
Micromachining is the foundation of precision and ultra precision grinding. In modern production activities, people generally choose a rough component first, and then use cutting and other technical means to change its external structure. In order to achieve high precision machining requirements, precision and ultra precision grinding may even have grinding thicknesses smaller than the size of device grains. This requires the grinding tool to have a relatively large cutting force.
Meanwhile, during the grinding process, the grinding tools are mostly in a high-speed running state. Under intense exercise, friction with processed components can cause a sharp increase in temperature in the local processing area. If the selected grinding tool is not appropriate, it is easy to deform at high temperatures, which can affect the machining precision.
From the above two points of analysis, we can conclude that in order to achieve micro machining of device structures, the selected grinding tool must have both high hardness and high temperature resistance characteristics. Based on the selection of existing mold materials, we believe that diamond, cubic boron nitride, and other materials should be prioritized for precision and ultra precision grinding tools.
2.2 Continuous precision grinding processing
Continuous machining is another significant feature of precision and ultra precision machining. In order to achieve precision control of processed devices, precision grinding generally adopts a "gradual approximation" machining method, which uses primary and secondary tools such as grinding tools to micro process the structure of the devices. In order to ensure the accuracy of the work, it is generally not possible to interrupt during the gradual processing. This requires high continuity in precision grinding processing.
In addition, during the continuous grinding process, the processing components and other components will undergo slight elastic deformation under the force of the grinding tool. After the system is in a stable working state, the cutting amount of grinding will be consistent with the size reduction of the processed components. Under normal circumstances, this phenomenon will be calculated within the normal error range. However, in precision and ultra precision machining, this error can greatly affect precision. Therefore, in continuous grinding, it is necessary to consider this part of the error in advance and control the tool to handle this part of the workload reasonably during processing. So, precision and ultra precision grinding require relatively high tool control.
3. Analysis of the selection of grinding wheels
In the previous text, we analyzed that the grinding tools used for precision and ultra precision machining need to have both high hardness and high temperature resistance characteristics. In the continuous working state of grinding, a relatively high tool control is required. So, there are certain considerations and methods for selecting grinding wheels for grinding processing.
3.1 Selection criteria for grinding wheels
The first thing to note is the selection of hardness for grinding wheels. The need for high hardness in molds is relative to the processing of components. If the hardness is relatively low, it cannot meet the needs of unprocessed cutting; If the hardness is too high, it may leave scratches due to the hard friction between the grinding wheel and the processing device. Therefore, the hardness selection criteria for grinding wheels are based on the hardness of the processed components as a reference. Considering that the hardness of devices that require precision machining is generally relatively low, we recommend choosing a grinding wheel with medium hardness.
In order to meet the requirements of high tool control, the particle size of the grinding wheel is also a criterion for selection. Especially in order to compensate for errors caused by elastic deformation at the beginning of grinding, the grinding wheel should maintain a relatively good micro edge.
In addition, grinding wheels also involve the issue of dressing during operation. At present, a dressing device suitable for commonly used grinding wheel materials such as diamonds has been developed, and we will not go into detail here. In practical work, workers can make reasonable choices based on their own needs.
3.2 Selection method of grinding wheel
Based on the criteria for selecting grinding wheels mentioned above, we propose the following suggestions for the selection method of grinding wheels:
Determine the properties of the processed components; Workers should first clarify the machining precision, hardness, and grain size of the processed components, and based on this, choose suitable precision machining machines, etc;
Select the hardness and particle size of abrasives and grinding wheels based on the properties of the processing devices; The hardness selection is generally based on medium hardness, and should be appropriately increased within a reasonable range. The granularity can be judged based on the selected reference map;
Choose the appropriate trimmer. Due to the fact that most of the precision and ultra precision machining molds and grinding wheels currently used are made of materials such as diamond, and the application of this material in the dressing machine is also quite extensive. So, we suggest prioritizing diamond as the abrasive material while meeting the requirements of precision and other working conditions.
Conclusion
Precision and ultra precision grinding will continue to provide services for people for a long time in the future and will play an important role in industrial production. This article analyzes the characteristics of precision and ultra precision grinding, determines the high hardness and high temperature resistance required for grinding wheels, and provides suggestions for their selection methods based on the actual situation. These studies are of great help to the development of precision and ultra precision grinding machining.
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