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High stability machine support parts description

High-speed cutting technology is one of the important development directions of cutting technology. It has taken a higher step with the development of basic skills such as CNC skills, microelectronics, new materials and new construction. Because of the speciality of mold processing and the characteristics of high-speed machining techniques, the coherent techniques and process systems (machining machine tools, numerical control systems, tools, etc.) for high-speed machining of molds are higher than traditional mold processing.
1. Highly stable machine support components
Supporting parts such as the bed of a high-speed cutting machine should have good dynamic and static stiffness, thermal stiffness and optimum damping characteristics. Orifice flowmeters Most of the machine tools use high-quality, high-rigidity and high-tensile gray cast iron as support components. Some machine tool companies also add polymer concrete with high damping characteristics to the base to increase its vibration resistance. And thermal stability, but this can ensure the accuracy of the machine tool, but also avoid the chattering of the tool during cutting. The closed bed design, the integrally cast bed, the symmetrical bed structure and the dense reinforcing ribs are also important ways to improve the stability of the machine. In the design process, some R&D departments of machine tool companies also adopted modal analysis and finite element construction calculations to optimize the structure and make the machine support components more stable and reliable.
2. Machine tool spindle
The spindle performance of high-speed machine tools is an important condition for high-speed machining. The speed of the spindle of the high-speed cutting machine tool is 10,000~100000m/min, and the spindle power is more than 15kW. The axial clearance between the shank and the main shaft is not more than 0.005 mm by the spindle shrink air or cooling system. It also requests the spindle to have the ability to speed up and speed up and stop at a specified position (ie, it has extremely high angular acceleration). Therefore, high-speed spindles often adopt hydrostatic bearing type, aerostatic bearing type, and hot pressure nitriding. Silicon (Si3N4) ceramic bearing magnetic suspension bearing type and other structural conditions. Smooth and more oil and gas, smooth and smooth techniques. Spindle cooling is individually performed by externally water cooling or air cooling of the spindle.
3. Machine tool drive system
In order to satisfy the needs of high-speed machining of the mold, the drive system of the high-speed machining machine should have the following characteristics:
(1) High feed rate. Drilling indicates that for small diameter tools, progressive speed and feed per tooth are beneficial for reducing tool wear. The current feed rate of the orifice electromagnetic flowmeter is 20~30m/min. If the large lead ball screw drive is adopted, the feed speed can reach 60m/min; the linear motor can make the feed speed reach 120m. /min.
(2) High acceleration. The high-speed machining request drive system for three-dimensional complex surface profile has good acceleration characteristics, and requests a high-speed feed driver (fast forward speed of about 40m/min, 3D contour processing speed of 10m/min), which can supply 0.4m/s2. Acceleration and acceleration to 10m/s2.
Machine tool builders mostly use small lead, full-size, high-quality ball screws or large lead multi-head screws that are fully closed-loop position servo. With the development of motor technology, advanced linear motors have been introduced and successfully used in CNC machine tools. The advanced linear motor drive eliminates the problems of mass inertia, lead, lag and vibration of the CNC machine, slows down the servo response speed, and improves the servo mastering accuracy and machine tool machining accuracy.
4. CNC system
The advanced numerical control system is the crux of the high-speed machining quality and effectiveness of the mold surface. The basic requirements for high-speed machining of the mold on the numerical control system are:
(1) High-speed digital control loop, including: 32-bit or 64-bit parallel solver and 1.5Gb or more hard disk; very short linear motor sampling time
(2) Feed forward control of speed and acceleration; Jerk control of digital drive system.
(3) Advanced interpolation method (NURBS-based spline interpolation) for good appearance quality, accurate size and high geometric accuracy.
(4) Look-ahead function. Request large buffer storage, you can browse and review multiple sequence segments afterwards (such as DMG machine can have up to 500 sequential segments, Simens system can reach 1000~2000 sequential segments), in order to be processed in appearance (curvature) When the seizure is changed, the feed rate can be changed in time to avoid overcutting.
(5) The error compensation function includes the thermal error compensation caused by the heat of the linear motor and the main shaft, the quadrant error compensation, and the error compensation of the orifice flowmeter measurement system. In addition, the high-speed machining of the mold has a high request for data transmission speed.
(6) The traditional data interface, such as the RS232 serial port transmission speed is 19.2kb, and many advanced processing centers have adopted Ethernet LAN (Ethernet) for data transmission, the speed can reach 200kb.
5. Cooling smooth
High-speed machining uses coated carbide tools to eliminate cutting fluids at high speeds and low temperatures, resulting in higher cutting efficiency. This is because: the milling spindle rotates at a high speed, and if the cutting fluid reaches the cutting zone, it must first overcome the great centripetal force; even if it defeats the centripetal force into the cutting zone, it can evaporate immediately due to the low temperature of the cutting zone, and the cooling effect is small or even No; at the same time, the cutting fluid will change the temperature of the blade edge strongly, which will easily lead to the occurrence of cracks, so it is necessary to adopt a dry dry cutting method with oil/gas cooling. This method can use a low-pressure gas to abruptly blow away the cutting of the cutting zone, thereby taking a small amount of cutting cold away, and the atomized smooth oil can cause a very thin macroscopic shielding film on the cutting edge of the tool and the workpiece. It effectively extends tool life and improves the appearance of parts.

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