日期: 2020-03-03
浏览次数: 2393

BINDE spindle development trend direction

The development trend of electric spindle technology is mainly reflected in the following aspects:

One. High speed, high stiffness

Due to the needs of high-speed cutting and practical applications, with the development of spindle bearings and their lubrication technology, precision machining technology, precision dynamic balancing technology, high-speed tools and their interface technology, the high-speed CNC spindles have become the current development. The general trend, such as electric spindle for drilling and milling, the speed of HF42 of Swiss IBAG reaches 140,000r/min, the D1733 of the PCB drilling electromechanical spindle of WestWind in the United Kingdom has reached 250,000r/min; the electric spindle of machining center, the highest of FISCHER in Switzerland The speed reached 42000r/min and the Italian CAMFIOR reached 75000r/min. In terms of the system stiffness of the electric spindle, due to the development of bearings and their lubrication technology, the system stiffness of the electric spindle is getting larger and larger, which meets the needs of high-speed, high-efficiency and precision machining development of CNC machine tools.

Second, high speed and high power. Low speed and high torque

According to the needs of actual use, most CNC machine tools need to meet the requirements of heavy cutting and high-speed cutting during low-speed roughing. Therefore, the machine tool spindle should have low-speed, high-torque, high-speed and high-power performance. For example, the electric spindles of machining centers produced by manufacturers such as CAMFIOR of Italy, Step-Tec of Switzerland, and GMN of Germany, it is not difficult to output torque to 200Nm in low speed section. The maximum torque of CNC milling machine and lathe electric spindle of CYTEC in Germany is Up to 630 N·m; in the high-speed section, the power is generally 10 to 50 kW; the maximum output power of the CYTEC electric spindle is 50 kW; the maximum power of the Swiss Step-Tec electric spindle is 65 kW (S1) for aircraft manufacturing. And mold processing; more reports that the electric spindle power reaches 80kW.

Third, further development towards high precision, high reliability and extended working life

The user puts higher and higher requirements on the precision and reliability of the CNC machine tool. As one of the core functional components of the CNC machine tool, the electric spindle requires higher precision and reliability. For example, the radial runout of the main shaft is within 0.001mm, and the axial positioning accuracy is less than or equal to 0.0005mm. At the same time, due to the use of special precision spindle bearings, advanced lubrication methods and special preload application methods, the life of the electric spindle has been extended accordingly, and its reliability is getting higher and higher. Step-Tec's electric spindle is also equipped with an acceleration sensor to reduce the vibration acceleration level of the bearing. In order to monitor and limit the vibration on the bearing, a vibration monitoring module is installed to extend the working life of the electric spindle.

Fourth, the electric spindle has built-in motor performance and form diversification

In order to meet the needs of practical applications, the performance of the electric spindle motor has been improved. For example, the ratio of constant torque high speed to constant power high speed (ie constant power speed regulation range) of the Swiss FISCHER spindle motor output has reached 1:14. In addition, the permanent magnet synchronous motor electric spindle has appeared. Compared with the asynchronous motor electric spindle of the same power, the outer diameter of the synchronous motor electric spindle is small, which is beneficial to increase the power density and realize small size and high power.

FIVE. Development towards rapid start and stop

In order to shorten the auxiliary time and improve the efficiency, it is required that the start and stop times of the CNC machine tool spindle are as short as possible, so a high start and stop plus (minus) speed is required. At present, the acceleration and start-up acceleration of the foreign machine tool electric spindle can reach more than lg, and the full-speed start and stop time is within ls.

SIX. Bearings and their preload application methods and diversification of lubrication methods

In addition to conventional steel rolling bearings, ceramic ball hybrid bearings have been widely used in recent years. Lubrication methods include grease, oil mist, oil and gas, etc., especially oil and gas lubrication methods (also known as Oil-air). The characteristics of environmental protection and energy conservation have been widely promoted and applied. The preload application method of rolling bearings is developed in addition to rigid preload (also known as positioning preload) and elastic preload (also known as constant pressure preload). An intelligent preloading method is to apply a preload to the bearing by using a hydraulic cylinder, and the preload can be controlled according to the specific working conditions of the spindle speed and load, so that the bearing performance of the bearing is more excellent. In the non-contact type bearing-supported electric spindle, such as magnetic bearing, air bearing electric spindle (Swiss IBAG, etc.), liquid floating bearing electric spindle (Ingersoll, etc.), etc., there are already a series of commodity supply markets.

Seven, the tool interface gradually tends to HSK, Capto tool holder technology

After the machine tool spindle is speeded up, due to the centrifugal force, the traditional CAT (7:24) shank structure can no longer meet the requirements of use, and it is necessary to adopt HSK (1:10) and other shank interface forms that meet the high speed requirements. HSK shanks feature outstanding static and dynamic coupling stiffness, high torque transfer capability, high tool repeatability and coupling reliability, making them ideal for high speed, high precision applications. Therefore, the HSK toolholder interface has been widely adopted for high-speed electric spindles (such as IBAG in Switzerland, CYTEC in Germany, CAMFIOR in Italy, etc.). In recent years, the Capto tool interface proposed by SANDVIK has also been applied in the machine tool industry. The basic principle is similar to the HSK interface, but the ability to transmit torque is slightly larger. The disadvantage is that the inner hole of the spindle shaft is difficult to process and the process is complicated. .

Eight, multi-functional, intelligent

In terms of multi-function, there are angular stop precise positioning (quasi-stop), C-axis drive, tool-opening air blowing, hollow-pass coolant, shaft end gas seal, low-speed torque amplification, axial positioning precision compensation, tool change automatic Dynamic balance technology, etc. In terms of intelligence, it is mainly manifested in various safety protection and fault monitoring and diagnosis measures, such as tool change interlock protection, bearing temperature monitoring, motor overload and overheat protection, bearing unloading protection when loosening the knife, spindle vibration signal monitoring and fault abnormality. Diagnostics, automatic compensation of axial position change, signal monitoring and automatic control of grinding wheel dressing process, tool wear and damage signal monitoring, etc. For example, the Step-Tec electric spindle is equipped with a diagnostic module, and the maintenance personnel can read the data through the infrared interface to identify the overload. Calculate the working life of the electric spindle.

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