The manufacture of modern machine tools, no matter how high-end or precise, is inseparable from manual scraping. Manual scraping is a powerful guarantee of the perfect precision of machine tools.
There are approximately three stages in the manufacture and repair of precision machine tool guides:
1. First, plan with a wide knife on a large gantry planer.
2. Then grind on large precision gantry guide rails and ordinary guide rails.
3. Finally, perform manual scraping and grinding.
According to national standards GB /T1031-2009, GB /T1031-1995,
GB/T11336-2004.
The machine tool has very high precision and the flatness tolerance standard is Class I 0.005mm.
The precision grinding surface roughness is 0.16-0.04μm.
The surface roughness of ultra-precision grinding is 0.04-0.01 μm.
The surface roughness of mirror grinding can reach less than 0.01μm.
The straightness error of the ultra-high precision linear guide of the machine tool is 0.01 mm/m.
The precision level of the guide rail is divided into (travel parallelism, the following takes the 100mm long guide rail as an example).
Ordinary quality (C) 5μm.
High quality (H) 3μm.
Precision quality (P) 2μm.
Super precision (SP) grade 1.5 μm.
Ultra high precision (UP) quality 1 μm.
“Hand scraping” is a finishing method. The precision of the guide rail can reach 0.005-0.01 µm (1 micron is one millionth of 1 meter). Obviously, “manual scraping” is very necessary and extremely high. Precision machine tool guide rail processing is an essential processing process.
Machine tool grinding and hand scrape grinding each have advantages and limitations in terms of machining accuracy and efficiency. Machine tool grinding is often used in high-efficiency and large-scale production because it can quickly remove large quantities of materials, thereby increasing production efficiency. However, machine tools may suffer from wear and friction during the machining process, leading to a decrease in machining accuracy with the number of machining operations. Manual scraping and grinding is a meticulous manual technique that corrects machining errors by removing substances that affect mechanical precision one by one. In addition, manual scraping and grinding not only serves to improve precision, but also to improve aesthetics or lubrication conditions between sliding parts. Although manual scraping and grinding requires careful operation and exquisite craftsmanship from technicians, it can provide higher processing precision than machine tool grinding, especially in processing that requires highly personalized or complex shapes. Therefore, manual scraping and grinding may be superior to machine tool grinding in certain situations.
Manual scraping uses a scraper, a reference surface, a measuring tool and a display agent to manually grind and measure the points, while manually scraping and grinding the workpiece to achieve the size, geometry, surface roughness and the stipulations specified in the process. this requires waterproofing and other requirements. Because the tools used are simple, relatively versatile, have low machining allowances and achieve very high precision, they are widely used in the manufacturing of machines and tools and in the repair of mechanical equipment. Usually, the guide rails, carriages and smooth bearings of machine tools are finished by manual scraping. Nowadays, the guide rails of industrial machine tools that manufacture large and super-large precision machine tools are usually scraped and ground manually. The rail guides of some components on high-precision machine tools are W-shaped. For example, the two ends and the middle of the moving beam of large-scale gantry milling and large-scale vertical lathes are convex toward the top. In this case, manual scraping is the best method. Large machine tools require high-level skilled fitters, repairs, grinding and calibration (all by hand). Make the machine tool achieve the designed accuracy. The various accessories of high-precision machine tools are processed by machine tools, and the final assembly requires people to complete it. The assembly process involves a lot of manual labor. The high-precision guide rail plan is completed by “manual scraping and grinding”. “.Especially the installation of machine tool guide rails, it requires the most patience and requires a lot of testing tools. However, after the testing is completed and the problems are discovered, what can be solved is actually a shovel blade and red mud to slowly correct guide rail contact surface error.
For precision machine tools in the United States, Germany, Switzerland and Japan, the rail guides of coordinate boring machines and the joint surfaces of important and precise components are all manually ground, and it is only by manual scraping they can meet the precision requirements. The guide straightness error of these machine tools is less than 0.0025mm, and the flatness reaches more than 20 points in the range of 25mm x 25mm. If you know how to scrape or are a professional technician, you will know how difficult it is.
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