Characteristics and development of the hottest hig

Analysis on the characteristics and development of high speed machining center

the research on high speed cutting can be traced back to the 1930s, which was proposed by salomons and obtained a patent from Germany. After decades of efforts and the related technology of high-speed cutting has gradually matured, so far, high-speed cutting technology is emerging rapidly as an advanced manufacturing technology, which has a far-reaching impact on the development of machinery manufacturing industry. The key technology to realize high-speed cutting is to research and develop high-speed cutting machine tools with excellent performance. Since the mid-1980s, the development of high-speed cutting machine tools has become the mainstream of the development of international machine tool industry technology. At present, high-speed machining centers and other high-speed CNC machine tools that meet the requirements of high-speed machining have become a popular trend in industrial developed countries, and China is also accelerating the development of the production, research and application of high-speed machining centers. According to preliminary statistics, in recent years, the import of high-speed machining centers has reached hundreds of millions of dollars, which has become the import hotspot of many industrial departments in China

the characteristics and development of high-speed machining center are introduced below:

high speed spindle

high speed spindle is one of the most critical components of high-speed machining center. At present, machining centers with spindle speed of 20000 ~ 40000 R/min are becoming more and more popular. The spindle speed of some European high-speed machining centers has reached 60000r/min. at the same time, the requirements for the processing technology, material selection, precision and customized service of the conduit have also been continuously improved. The ultra-high speed spindle with a speed of more than 100000 R/min is also being developed. In addition to adjusting according to the Convention, it is also under development. The speed, horsepower, dynamic balance, rigidity, taper pass and thermal deformation characteristics of high-speed machining center have a considerable impact on the rigidity and thermal stability of high-speed machining center. In this way, the spindle and motor of the high-speed machining center are required to be combined into an electric spindle to realize direct transmission without intermediate links, reduce transmission parts, and have higher reliability

the main shaft bearing is also a key component that determines the service life and load capacity of the main shaft. In order to adapt to high-speed machining, the spindle design of high-speed machining center adopts advanced lubrication and heat dissipation technology of spindle bearing. At present, three kinds of special bearings are mainly used for high-speed spindle: (1) ceramic bearings; (2) Magnetic bearing; (3) Air bearing. The lubrication of main shaft bearings plays an important role in improving the speed of main shafts. High speed main shafts are usually lubricated by oil air or oil spray

high speed feed system

improving the cutting speed is necessary to improve the machining efficiency. At present, the cutting feed speed of high-speed machining centers is generally 20-40m/min. Some vertical machining centers driven by linear motors have ultra-high positioning speed of 140m/min, and some high-speed machining centers have feed speed of 208m/min. In order to realize and accurately control such a high feed speed, new requirements are put forward for the guide rail of high-speed machining center and the ball screw HPT honeycomb based on the inherent advantages of light honeycomb structure, such as upper rod, servo system, workbench structure, etc. The mature application of linear motor makes the high-speed machining center turn a new page in efficiency, accuracy and practicality. The linear motor is a non-contact direct drive mode, with few moving parts and no distortion and deformation problems. With this technology, the machine tool manufacturing has reached a level that the traditional ball screw cannot reach. The linear motor has the characteristics of high acceleration and deceleration. The acceleration can reach 2G, which is 10-20 times that of the traditional drive device, and the feed speed is 4-5 times that of the traditional drive device

high speed CNC control system

high speed machining center requires the CNC control system to have fast data processing ability and high functionality, so as to ensure good machining performance in high-speed machining (especially when machining complex surfaces with 4-5 axis coordinate linkage). The high-speed machining center must choose appropriate CNC controllers with fast transmission speed, fast CPU operation speed, pre read single section and NURBS function, so as to give full play to the efficiency of high-speed machining. Open architecture and PC based are also a new trend of development. Combined with the development of PC in communication and network, the establishment of parameter database system, cad/cam integrated simulation system and standardized electronic control module is also a new trend in the future

there are two important indicators of the data processing capacity of the high-speed CNC system: one is the processing time of a single program segment. In order to adapt to high speed, the processing time of a single program segment is required to be short. For this reason, 32-bit CPU and 64 bit CPU are required, and multi processors are used; The second is interpolation accuracy. In order to ensure the interpolation accuracy at high speed, there should be feedforward and large number of advanced program segment processing functions. In addition, NURBS (nonlinear B-spline) interpolation, recoil acceleration, smooth interpolation, bell acceleration and deceleration and other contour control technologies can also be used. The functional characteristics of high-speed machining CNC system include: (1) addition and subtraction pre interpolation; (2) Feedforward control; (3) Precise vector compensation; (4) Optimum corner deceleration

high speed cutting tools

the developed tool materials mainly include polycrystalline diamond (PCD), polycrystalline cubic boron nitride (PCBN), hard gold coated tools, ceramic tools, etc., which can adapt to the high-speed cutting of aluminum alloy, cast iron, steel and heat-resistant alloy. Their cutting levels are as follows: aluminum alloy 2500 ~ 5000m/min (Si content ≥ 12% is 500 ~ 1500m/min), cast iron 500 ~ 1500m/min, steel 300 ~ 1000m/min, hardened steel Heat resistant alloy 100 ~ 400m/min, ferroalloy 90 ~ 200m/min. Relevant research institutions are developing new cutting tool materials to a higher cutting speed

it is necessary to carry out dynamic balance on the tool structure, especially for the tool with a long extended handle, so as to prevent the tool handle or blade with low bending strength and fracture toughness from breaking due to centrifugal force caused by high speed, which will bring danger to the high-speed machining center and the operator

the selection of tool holder system will also affect the repetition accuracy and cutting rigidity of automatic tool change. At present, the single-sided clamping tool holder system with 7:24 taper is generally selected for the tool holder system, including ISO, cat, DIN, BT, etc. the two-sided positioning tool systems include HSK, km, NC5, BIG-PLUS, WSU, absc, etc

temperature control system of high-speed machining center

the thermal characteristics of high-speed machining center refers to the characteristics that the structure of high-speed machining center produces structural deformation and affects the machining accuracy under the action of its internal heat source and external heat source. In order to improve the thermal characteristics of high-speed machining center, the former generally adopts temperature control cycle. The former needs to check 1 water (or other media) to cool the spindle motor, spindle bearing, linear motor, hydraulic oil tank and electrical cabinet, Some even cool the headstock, beam, bed and other large components. In addition, cast iron with low expansion coefficient can also be used as the spindle box of the high-speed machining center to reduce the thermal elongation of the spindle and the thermal deformation of the spindle components

other

in order to make the high-speed machining center operate normally and give full play to its efficiency, the overall structure of the high-speed machining center should also be equipped with tool magazine and tool changing device, cooling system, temperature control system, safety protection and real-time monitoring system, tool damage monitoring, laser detection device for tool length and diameter, grating ruler measurement system and chip removal device. Not introduced here