Automobile various parts processing technology and tools used
Machining of hole parts：
Most of the hole machining of the parts adopts a multi-blade composite type (blade machine clamp, insert welding combination) structure, and the grinding is replaced by reaming and squeezing. In the one-time pass process, the hole is finished, the rotation speed is 3000r/min, the cutting speed is 1.5~3m/min, the precision is 5~7, the roughness Ra=0.7μm, the gun drilling speed reaches 8000r/ Min, Ra = 2 μm. The precision boring and reamer produced by Mapal in Germany is widely used in the automotive industry due to its unique structure, ultra-precise internal hole precision, excellent surface roughness and high economic efficiency. The Mapal tool is a single-edged cutting tool with a precision ground indexable insert. The blade body is inlaid with two or more support bars, and the support bar is also supported by the corresponding position at the same time as the blade enters the workpiece cutting, and absorbs the vibration and resistance caused by the cutting, and ensures the inside. The roundness and cylindricity of the hole are within 1 to 3 μm, and the hole diameter tolerance is H6. In the processing of valve tunnel holes in automobile engines, the machining accuracy and surface quality are superior to gun drilling. The cylinder hole boring adopts double-station, machine tool spindle built-in and axial reciprocating push-pull rod mechanism. The reciprocating passes are used for rough and fine boring, respectively, and the boring speed is up to 800 m/min. ?
Processing of flat parts
Most of the milling of plane parts adopts the diameter and axial two-way adjustable high-speed close-tooth face milling cutter with dense teeth, over-position and repeated clamping structure. The milling cutter has a diameter of 250 to 400 mm and an axial runout of ≤ ± 0.0025 mm. The machining of the part assembly plane is milled, with roughness Ra=0.7μm and unevenness <0.02mm. ?
The insert of the fine milling cutter can be adjusted with an eccentric screw with an adjustment accuracy of 0.002 mm. In the medium feed finishing milling process, the normal blade and the smoothing blade are arranged reasonably, and the surface roughness of the parts can be obviously improved; when the large feed finishing is finished, all the polishing blades are used to obtain the ideal surface roughness. ?
When milling aluminum alloy workpieces, various sizes of milling cutters with different pitches and large axial and radial rake angles are used. The rake face of the tool is polished, and the cutting force is small during cutting without vibration. Good quality. ?
For the machining of the main bearing cap of the crankshaft, the special tool for broaching of the inverted and arranging machine clamp is used for the razor cutting. Three types of 713 pieces of indexable carbide coating (TiCN) are installed, and the feed rate is 25m/min. 1750 pieces, the cutting allowance of broaching is 1.5~3mm. ?
In the processing of connecting rods of automobiles, the separation surface breaking process and the double-sided horizontal double-axis circular table surface grinding process are all high-quality and high-efficiency machining processes commonly used in foreign connecting rod production. ?
Machining of shaft parts
The machining of the crankshaft main journal and the connecting rod journal of the automobile is a double-station car-specific tool for broaching. The cutter head has a diameter of 700mm and the cutter disc is equipped with 40 pieces of carbide coated blades. Each 10 pieces is 1 set, the cutting speed is 150m/min, the fast forward speed is 4.6m/min, and the radial cutting allowance is 1.5. ~3mm. In addition, some parts of the shaft end of the outer cylindrical surface processing using the forming combination of external milling, reaming special tools, one pass to complete the outer circle and end face roughing, instead of single-blade turning process. ?
Cylindrical gear machining?
Most of the foreign countries use a multi-coated high-speed hob (cutting speed of 110m / min or more) and radial shaving knife roll, shaving, to shave grinding. A large number of CNC cutting equipment is used to greatly improve the processing efficiency, and the machining accuracy can be stabilized at level 7 or above. Hard tooth surface cutting with hard alloy tools has become an important research field. ?
High-speed hobbing of more than 100m/min in China is applied in some joint ventures. Dental caries, grinding teeth, and radial shaving also have different degrees of application, but most of them are poor in processing efficiency, precision and stability, and generally only achieve 8 levels of precision. ?
Straight bevel gear machining?
A large number of foreign countries use precision forging technology to retain the cutting technology in high precision requirements. At present, the domestic precision forging process has been applied, but it is rarely used in automobile production, and most of them use the cutting technology. ?
Spiral bevel gear machining?
Most of the spiral bevel gears in foreign countries use CNC milling machine to cut teeth. After heat treatment, the CNC grinding machine is used for grinding teeth. Paired fine assembly or CNC milling machine. After heat treatment, the CNC gear grinding machine is used to grind the teeth, which better corrects the heat treatment deformation. Can be paired with the assembly. Hardened surface scraping technology has certain applications in spiral bevel gear machining. ?
Both Gleason and Oerlikon have introduced the latest design, analysis and measurement software for six-axis CNC equipment, making the spiral bevel gear design, machining, and tooth profile correction an intelligent closed-loop system. ?
Adopting the gear measuring center, due to the advanced technology and automatic detection, the measurement is accurate, the precision is high, and the efficiency is high. ?
The spline tooth shape processing on several transmission shafts of the engine adopts double-station, paired configuration, squeezing and special tools for chipless machining, and reciprocating motion, and the spline tooth shape is extruded. ?
Most of the domestic spiral bevel gears are processed by ordinary milling machines, and the teeth are machined after heat treatment. The cutting precision is low, and the real function of the grinding tooth is not exerted. The heat treatment deformation of the material has poor controllability. ?
The CNC gear grinding machines of Gleason and Oerlikon, which were just introduced by FAW Group and Dongfeng Motor Co., have not been used for production. Gear inspection generally uses a weekly inspection instrument, an involute inspection instrument, a base gauge, etc., and a few manufacturers use a gear inspection center. ?
Shell parts processing
Most of these parts belong to the flat and porous thin-walled parts structure, which has poor rigidity and high precision for the hole position. Therefore, most of the foreign countries use machining centers for processing. ?
The boring of the spherical surface in the differential housing adopts the spindle built-in machine tool, and the push-pull rod reciprocates axially, which drives the boring head to move in a semi-circular trajectory in two dimensions, superimposes the rotary motion of the casing, and completes the spherical forming boring process in one pass. According to the multi-variety demand of the product market, China has formed a trend of shifting from the production line of a large number of dedicated combined machine tools to the flexible production line consisting of CNC machine tools and machining centers. The semi-automatic off-line measurement is performed by a coordinate measuring machine, and the detection precision is high, but the efficiency is not high. ?
In the plane grinding, most of the domestic large-scale high-precision grinding machines are used, the grinding roughness is Ra=0.5μm, and the grinding speed is 8.0m/s. ?
Cylindrical grinding uses high-precision CNC cylindrical grinding machines. ?
Internal grinding is carried out in China using a high-precision internal grinding machine with a grinding roughness Ra = 0.2 μm. ?
Stainless steel electrode
The future development trend is to solve the problem of precision and rigidity of domestic machine tools in the processing of cylindrical gears, solve the problem of tool materials and their life, develop high-speed hobbing and hard tooth surface processing technology; develop radial shaving and stable tooth decay process Introduce CNC gear processing machines to improve the overall processing level. In the aspect of bevel gear processing, the precision forging process is developed to process straight bevel gears in order to improve efficiency and reduce cost; for spiral bevel gears, a more perfect spiral bevel gear trial system will be gradually formed. Design, strength analysis, trial production, testing and production preparation will form a complete software and hardware environment, solve the key technology of pre-production cutting technology; have high-precision, low-noise gear development and development capabilities; effectively undertake new products Trial production and production of small-volume, high-precision special-purpose gears; refine the assembly process, determine reasonable quality inspection links and process tempo, and determine corresponding technical measures for different requirements of different gear products; gear trial production and production workshops should be equipped with Gear detection center for automatic detection and reduction of human error. In the processing of shell parts, the high-speed machining center module system will be used to process the shell parts, and the production line will match the coordinate measuring machine or the automatic measuring instrument to realize automatic or semi-automatic online detection. In the processing of various planes, the development of large plane high-speed high-precision grinding machine grinding plane with roughness of Ra=0.5μm will be developed; development of powerful grinding machine, high-precision CNC cylindrical grinding machine and point grinding process for grinding outer circle; The high-precision internal grinding machine grinds the inner circular surface with a roughness of Ra=0.2 μm.
High and low temperature bearing grease