0 Preface
With the rapid development of railroad large-scale road maintenance machinery, it has changed the production mode, management mode and even cultural connotation of railroad people. The level of large road maintenance mechanization has become one of the important symbols to measure the degree of modernization of railroad in each country, and China has become a large country in the manufacture and use of large road maintenance machinery.
Large road maintenance machinery should not only meet the basic requirements of railroad locomotive operation, but also to achieve the main function of its own maintenance equipment. Therefore, the construction of large-scale railroad road maintenance machinery is many times more complex than the locomotive, usually using a variety of different cross-sectional metal materials by mechanical processing, welding to form the entire body and work device bearing structure, these metal materials are important components of the body structure.
Mechanical processing of metal materials is an important process in the manufacturing process of the car body, the processing of spare parts are generally more complex, processing parts, processing time is long, need to use a variety of types of machining equipment, and some of the strange shape, thin-walled, super-large parts of mechanical processing more to the manufacture of large road maintenance machinery has brought a great challenge, so the study of large road maintenance machinery spare parts processing technology, to solve the large road maintenance machinery manufacturing process. Road maintenance machinery manufacturing process of difficult problems, to ensure the quality of large road maintenance machinery, improve production efficiency is of great significance.
1 Introduction to machining
Machining is a kind of processing machinery to change the size or performance of the workpiece process. According to the temperature state of the workpiece to be processed is divided into cold processing and hot processing. Generally processed at room temperature, and does not cause chemical or physical changes in the workpiece is called cold machining. Generally, processing at higher or lower than room temperature will cause chemical or physical changes in the workpiece called thermal processing.
Thermal processing is common in heat treatment, calcination, casting and welding. Cold processing can be divided into cutting and pressure processing according to the differences in processing methods. Cutting processing is the use of cutting tools (including tools, abrasives and abrasives) to cut away the excess layer of material on the blank or workpiece to become chips, so that the workpiece to obtain the specified geometry, size and surface quality of the processing method. Usually, the mechanical processing of large road maintenance machinery parts refers to the cutting process and heat treatment.
2 large road maintenance machinery processing technology development direction and trends
In order to adapt to the rapid development of large-scale railroad road maintenance machinery to equipment efficiency, excellent performance, diversification, product series, intelligent work, operation and environmental protection, large road maintenance machinery processing technology will also make corresponding development in order to meet the needs of production and manufacturing.
2.1 Precision ultra-precision direction development
The continuous improvement of processing accuracy to improve the performance, quality and reliability of large road maintenance machinery products, improve the interchangeability of parts, improve assembly efficiency, etc. have an extremely important role. Precision and ultra-precision machining in cutting-edge technology and modern weapons manufacturing occupies a very important position, will be one of the most important directions for the development of large road maintenance machinery processing technology.
2.2 Automation direction development
Automation is one of the most important parts of advanced manufacturing technology, is the direction of development of machinery manufacturing. For large road maintenance machinery manufacturing multi-functional multi-tasking integrated processing center formation, began to gradually replace the conventional analog control technology. Because the technology is easy to control, good reliability, high precision and other advantages, will also greatly accelerate the development of large-scale road maintenance machinery.
2.3 high-speed, ultra-high-speed machining direction development
Cutting processing technology is one of the most common means of machining applications, and high-speed, ultra-high-speed is a major challenge to cutting technology, but also for the development of large-scale mechanical processing technology to provide the direction. High-speed machining technology can be used not only for processing ordinary steel, cast iron, non-ferrous materials, but also for processing a variety of high-strength steel, high-alloy steel, titanium alloy steel and fiber-reinforced composite materials and other difficult-to-machine materials.
3 large road maintenance machinery parts mechanical machining process
3.1 rotary surface processing methods
Each large road maintenance machinery rotary parts face have many processing methods, the specific choice should be based on the parts of the material, embryo type, structure shape, size, machining accuracy, roughness, technical requirements, production type and production conditions and other factors to determine, in order to ensure processing quality and reduce production costs.
(1) the requirements of the rotary surface processing technology
The technical requirements of rotary surface include: size and shape accuracy; position accuracy; surface quality.
2）Basic machining process of rotary surface
3）Typical rotary surface process scheme analysis
Large road maintenance machinery pounding series of models to lift the rail clamp thread set mechanical processing process.
Clamp thread sleeve (see Figure 2) material for 45 # steel, commonly used medium carbon tempered structural steel, with high strength and good machinability, after appropriate heat treatment can be obtained after a certain degree of toughness, plasticity and wear resistance.
Threaded sleeve processing accuracy, is the key factor to control the concentricity of the upper and lower ends of the bore and the bearing outer ring installation step plane verticality. Clamp threaded sleeve in the construction of the tamping car operation, both exposed to the harsh environment and to withstand the larger force, so the need for rough and finish machining separate, the use of CNC lathes, grinders, etc. to improve processing accuracy, while the corresponding heat treatment to improve the physical and chemical properties of the material, the specific processing process is shown in Figure 3.
3.2 Hole processing method
(1) hole processing technical requirements
The technical requirements of hole machining include: hole size and shape accuracy; hole location and surface accuracy.
(2) hole processing basic process
Hole commonly used in various methods of processing process flow (see Figure 5), the basic principles of processing process selection is shown in Table 1.
(3) typical hole plus process program analysis
DC-32 tamping car tamping frame support body hole machining process
The pounding frame (see Figure 6) is a device that assembles the pounding device and the main frame, allowing the pounding device to achieve lateral movement and vertical movement to complete the pounding function. The support body is the force-bearing part of the whole tamping device, so the accuracy of the support body hole machining directly affects the operating performance and service life of the tamping vehicle.
As the support body and tamping frame are connected by welding into one, more or less will produce welding deformation, when the support body hole machining, in order to ensure that the support body 1 and support body 2 hole center axis shape size to meet the design requirements, need to mount (see Figure 7) to find out the actual coordinates of the two holes before the next processing process. The specific processing process is shown in Figure 8.
3.3 Plane processing method
(1) The technical requirements of surface machining
The technical requirements of surface machining mainly include: shape accuracy; position accuracy, dimensional accuracy and parallelism, perpendicularity, etc.; surface quality, etc.
2）Basic process of surface machining
3）Analysis of typical planar processing scheme
High efficiency vibrating screen frame support plane machining process tooling design
High efficiency vibrating screen (see Figure 10) is designed to meet the development of clearing screen machine to high efficiency, high efficiency vibrating screen changes the traditional vibration method, while increasing the amplitude of the vibrating screen, effectively avoid resonance between the vibrating screen and the frame, thus greatly improving the efficiency of clearing screen.
In order to realize the function of the vibrating screen, it can only be machined after welding to ensure the flatness of the 4 supports of the vibrating screen frame and the symmetry of the mounting holes. However, due to the extra-long vibrating screen frame, the existing machine tool cannot process it, so it can only design special tooling (see Figure 11) and machine it after welding to ensure all the design requirements of the support plane.
4 Conclusion
Through a brief discussion of the development trend of machining and large road maintenance machinery processing, focusing on the analysis of the basic process of mechanical processing of railroad large road maintenance machinery parts and the design of typical process tooling, timely and effective solution to the large road maintenance machinery manufacturing process parts processing problems, to ensure the large road maintenance machinery drawing design requirements and production schedule requirements, played a huge role in the production.