DRILLSTAR CARBIDE TOOLS ARE WORKING IN MANY PLACES AROUND THE WORLD
Views: 0 Author: Site Editor Publish Time: 2024-01-02 Origin: Site
According to GB/T6477-2008, the spindle of a machine tool refers to the axis that drives the rotation of the workpiece or machining tool on the machine tool. The development trend of modern machine tool spindles is gradually transitioning from traditional machine tool spindles to electric spindles. The traditional machine tool spindle is driven by a transmission device to rotate and work. The electric spindle places an electric motor inside the spindle and directly drives the spindle through a driving power source, achieving the integrated function of the electric motor and spindle. Compared with traditional machine tool spindles, electric spindles have significant advantages. The spindle is directly driven by an electric motor, eliminating intermediate variable speed transmission devices such as conveyor belts, gears, and couplings. It has the characteristics of compact structure, high efficiency, low noise, small vibration, and high accuracy. In addition, using AC frequency conversion technology, the electric spindle can achieve stepless speed change within the rated speed range to adapt to various working conditions and load changes during machine tool operation.
The electric spindle is composed of a shell less motor, spindle, bearings, spindle unit housing, drive module, and cooling device. The rotor of the electric motor is integrated with the main shaft through pressure fitting method, and the main shaft is supported by front and rear bearings. The stator of the electric motor is installed in the housing of the spindle unit through a cooling sleeve, and the speed of the spindle is controlled by the spindle drive module, while the temperature rise inside the spindle unit is limited by the cooling device. A speed and angular displacement sensor is installed at the rear end of the spindle, and the inner cone hole and end face at the front end are used to install the tool.
The electric motor of the electric spindle mostly adopts AC asynchronous induction motor. As it is used on high-speed machining machine tools, it needs to quickly increase the speed from static to tens of thousands or even hundreds of thousands of revolutions per minute when starting. The starting torque is large, so the starting current needs to exceed the rated current of ordinary motors by 5-7 times. There are two driving methods for it: frequency converter drive and vector control drive. The driving control characteristic of frequency converter drive is constant torque drive, and the output power is proportional to the torque. The latest frequency converter of machine tools adopts advanced transistor technology, which can achieve stepless speed change of the spindle. The driving control characteristics of vector control drivers are constant torque drive at the low speed end and constant power drive at the medium and high speed ends.
Electric spindle, CNC system, and feed drive are the three high-tech areas of current CNC machine tools. With the rapid development of cutting technology, numerical control technology, and information technology, more and more machine tools are constantly moving towards high speed, high precision, high efficiency, and high intelligence. Electric spindles have become the core components of machine tools to achieve the above high-performance working conditions, especially in multi axis linkage, polyhedral machining, parallel machine tool machining, and composite machining. The excellent characteristics of electric spindles are irreplaceable by mechanical spindle units.
Electric spindle is a new technology that has emerged in the field of CNC machine tools in recent years, integrating machine tool spindles with spindle motors. Along with linear motor technology and high-speed tool technology, it has pushed high-speed machining of machine tools into a new era.
The advantages of machining centers are mainly reflected in the following aspects.
1) Reducing the number of fixtures, processing complex shaped parts does not require complex fixtures. If you want to change the shape and size of the parts, you only need to modify the part processing program, which is suitable for new product development and product replacement.
2) Stable processing quality, high processing accuracy, high repeatability, and can adapt to the processing requirements of different products.
3) In the case of multi variety and small batch production, the production efficiency is higher, which can not only reduce the time for production preparation, machine tool adjustment, and process inspection, but also reduce cutting time through processing parameter optimization.
4) Suitable for difficult to machine complex surfaces and difficult to machine parts of workpieces.
At the same time, there are also shortcomings in the machining center, mainly manifested in the following two aspects.
1) The investment cost of machine tool equipment is high.
2) High skill requirements for operators and machine maintenance personnel.
3、 The processing principles of machining centers
In CNC machining centers, the determination of machining routes generally follows the following principles.
1) The same machining surface is completed in the order of rough machining, semi precision machining, and precision machining, or all machining surfaces are separated by rough machining, semi precision machining, and precision machining.
2) For parts that require both milling and boring, milling the surface first and then boring the hole can improve the machining accuracy of the hole.
3) For centralized processing at the same workstation, it is advisable to process as closely as possible to shorten the tool movement distance and reduce idle running time.
4) Some machine tool workbenches have a shorter rotation time than the tool change time. In order to reduce the number of tool changes, empty stroke, and unnecessary positioning errors without affecting accuracy, a tool concentration process can be adopted, that is, using the same tool to process the same part of the part, and then replacing it with a second tool.
5) Considering the existence of repeated positioning errors in machining, for hole systems with high coaxiality requirements, the principle of tool concentration cannot be adopted. Instead, after a single positioning, all holes in the coaxial hole system should be sequentially and continuously processed, and then other coordinate position holes should be processed to improve the coaxiality of the hole system.
6) In a positioning fixture, try to complete all the surfaces that can be machined as much as possible.
