Nail Making Machine,Nail Production Machine,Nail Manufacturing Machine,Automatic Nail Making Machine TIANJIN LIHE TRADING CO.,LTD , https://www.lihecorp.com
As the world's largest water conservancy project - it is also the largest single-hull hydropower generating unit of the international Francis turbine, and cooperates with Alstom to manufacture 8 of the 14 units of the first phase of the left bank. The numerical control processing technology of the key components of the Three Gorges turbine, the runner blade, is of great significance to improve the level of power plant equipment manufacturing in China and to enter the ranks of the world's advanced technology. There are several types of turbines, such as mixed flow, axial flow, and cross flow. Domestic turbine blades are manufactured by sand casting for a long time. After manual shovel forming and three-dimensional model detection, in recent years, blade molding has been developed. The technology of CNC machining after re-machining and casting after compression molding.
The method of manual shoveling not only has a laborious environment, high labor intensity, low efficiency, but also poor quality of the blade profile, which reduces the efficiency of the turbine. In order to realize the numerical control machining of the blade, our factory introduced the five-axis CNC boring and milling MACHINE from Germany Wotan Company in 1987, and introduced the UKLID software from FIDIS of Switzerland. In 1996, we purchased the CNC gantry milling machine from Germany Wadelich·Kebao. The introduction of CAMAX software provides technical guarantee for CNC machining of blades. Subsequent specialties have carried out in-depth research on surface modeling, tool position calculation, tool position interference inspection, blade measurement, automatic alignment adjustment and machining program preparation, process clamping, machining mode and tool system configuration, and have five axes. Coordinated CNC machining of blade production and technical capabilities. Up to now, the processing of turbine blades such as the mixed flow Tianshengqiao, Yulin, Xinfengjiang and Three Gorges turbine blades and axial flow Mujing has been completed. The key technology and process implement the numerical control machining process of the blade CNC machining process.
Five-axis linkage CNC programming technology blade profile measurement Because the machining allowance of the casting blank distribution is inconsistent, the three-dimensional measuring machine is used to measure the three-dimensional surface of the blank, and the measurement method with high efficiency, convenient computer data acquisition processing and reference transformation is selected to reach the balance. The optimal clamping position for uniform distribution. The surface modeling creates a three-dimensional profile of the blade based on the original data, which satisfies the next step of generating a NC program. The tool path calculation calculates the tool path trajectory based on the 3D profile data after the blade shape is read, the machining profile, the cutting parameters and the tool data.
Tool path trajectory simulation and tool interference check simulate the pattern on the computer according to the tool path, and check the tool interference to ensure safe operation during real machine processing. The post processing performs post processing on the tool path to generate an NC code machining program for a specific machine tool. Processing process processing equipment purchased from Germany, CNC gantry milling machine host power 100kW, table size 4.5 × 13m, equipped with the world's most powerful CNC universal milling head, CNC system using SIEMENS840C, the machine has X, Y, Z, W , U five-axis numerical control and A, C two rotary axis CNC milling head, forming the five-axis linkage CNC machining blade equipment conditions.
The control blade of the blank quality is a cast structure and the material is martensitic stainless steel. The blades are coarsely ground to remove sand and avoid damage to the tool. Then perform UT and MT inspection and check the defect status. Because the casting quality of the blade is not good and the margin is uneven, it is required to control the machining allowance of the front and back of the blade and the peripheral margin to reduce the working hours of the CNC machining. The front and back machining allowances of the blade are measured by the theodolite, and the three positioning reference points for the front and back mark measurement and processing of the blade are attached and their coordinate values ​​are attached. The measurement data is transmitted to the next order in the form of a disk. The shape of the blade clamping blade is irregular, especially the mixed flow blade is a free curved surface without any reference. The research of the clamping method is the first problem to be solved in the implementation of programming and processing. VOITH of Germany adopts shaft outer diameter and flange positioning and vertical clamping method for axial flow vanes. The mixed flow vane adopts adjustable steering head jack positioning and vacuum suction cup clamping.
The clamping of the vacuum chuck requires pre-treatment of the adsorption site, and the system components occupy a large area. Our research proposes the use of positive and negative tire positioning, solder lap welding and screw clamping, which is economical, efficient and easy to operate. It is reported that Norwegian GE also adopts this method. The clamping positioning method has a good effect on determining the reference point of the workpiece and performing the alignment, and solving the technical difficulty of solving the misalignment of the front and back profiles of the blade. The alignment of the blade and the measurement use the numerical control machine tool milling axis to measure the coordinate values ​​of the three positioning reference points of the blade mounted on the tire, and set the reference point on the tire to perform the alignment. The RENISHAW measurement system was used to develop blade measurements for 3D curved surfaces, providing advanced inspection techniques for processed leaf shapes.
The programming of the workpiece applies the aforementioned programming technique to program the processing of the front and back of the blade, the edge of the inlet and outlet, and the welding of the upper crown and the lower ring. The processing parts of the blade processed by the five-axis CNC gantry milling machine are the front and back profiles, the inlet and outlet water edges and the upper and lower welding grooves. The tools used are coarse, fine face milling cutters, spiral end mills, ball end mills, and the like. The milling method uses milling with entrainment and coolant. The feed direction selects the feed along the parameter line of the blade shape, which is advantageous for milling performance such as tool diameter and interference requirements. The determination of the milling width has an effect on the surface machining quality and the machining efficiency. Since the milling cutter is inclined in the normal direction, the surface of the workpiece is slightly concave and curved after machining. The larger the milling width per knife, the absolute value of the residual peaks and troughs of the milling. The larger the value, the greater the amount of polishing work in the next order.
Therefore, it is necessary to reasonably determine the width of the running cutter for each block. The development and application of high-efficiency CNC tooling uses CNC machining blade technology, which is expensive to process. To process a blade of a Three Gorges turbine, it takes 10 days to process one piece, and the whole processing cycle is more than 5 months. The price of CNC milling machine is about 40 million. Yuan, working hours cost thousands of yuan per hour, processing costs more than 4 million yuan, to improve processing efficiency, reduce processing costs is particularly important, research, development, application of high-efficiency CNC tools and processing methods, is one of the key technologies to be solved . The development of domestic face milling cutters and spiral end mill blades requires a face milling cutter for the machining of curved surface parts. A spiral end mill is required for access, water edge and welding groove.
The use of foreign tools is expensive, suitable for the processing of stainless steel blades. We have developed a flat-bottomed insert structure with a flat-blade clamping method, a main-angle of 75° and a double front with Harbin University of Science and Technology and Miangong Tools Factory. Angle face milling cutter; cooperated with Taiyuan Ace Tool Factory to develop a four-blade cutting machine with interchangeable head, a square blade with a blade and a four-stage spiral end mill; and a CNC tool with Harbin Gongquan CNC Tool Factory Development of the system. The test preferably uses a milling insert to solve the difficult machining problem of stainless steel. The key is the performance of the blade. The domestic blade has a considerable gap with foreign countries. The durability of foreign blades can reach 5 to 10 times that of domestic blades. According to the domestic brands of Zhuzhou, Zigong, Shanghard, Shaanxi Hard and other hard alloy manufacturers, 9 brands of blades, for foreign Sweden Sandvik, Germany Walter, the United States Kenner, Israel Iska, Hitachi, Mitsubishi and other companies A large number of tests were carried out on 10 grades of blades, and a blade with excellent cost performance was preferred. In addition, in cooperation with Harbin University of Science and Technology and Miangong Tools Factory, a new type of face milling cutter with double-edged step structure was developed to solve the problem of rough milling and empty stroke due to different machining allowances.
The milling parameters and milling methods are also optimized to achieve efficient and low-cost milling of the blades. 3 Conclusion The three-axis linkage CNC machining of turbine blades such as the Three Gorges and Tianshengqiao was successful, which marked that our factory and China's large-scale turbine manufacturing have reached the international advanced level. The innovation of blade technology has improved economic quality, improved processing efficiency, reduced tool costs and significant economic benefits. The numerical control processing of the blade makes the output efficiency of the runner increase by 3%, which has great economic benefits for the long-term operation of the unit. It is of great significance to the manufacturing quality of the Three Gorges unit and the entry of China's power generation equipment manufacturing into the international market after entering the WTO.
Five-axis linkage processing technology for Francis turbine blades
Introduction The numerical control machining technology of large turbine runner blades is one of the important signs to characterize the manufacture of turbines to the advanced level in the world. The runner blade is a key component of the turbine. Its manufacturing precision has a direct impact on the hydraulic performance such as the efficiency of the unit. The precision of the profile processing is high, and the efficiency of the turbine output is increased by one percentage point, which will bring long-term and huge benefits. The numerical control processing of the blade involves many aspects of high-tech. The foreign countries only have French Alstom, Norwegian Kwana, Canada GE, Germany Woyizi, Japan Hitachi, etc. This manufacturing process is mature. Due to the superiority of the CNC machining of the blade profile to the quality of the turbine manufacturing, it has become a key technical requirement for the ordering of the unit.