CNC machine tools generally use DC or AC spindle servo motor to achieve spindle stepless speed. AC spindle motor and AC variable frequency drive (cage induction AC motor configuration vector conversion frequency control system), because there is no brush, no spark, so long life, and performance has reached the level of DC drive system, even in the noise There are also lower. Therefore, the current application is more extensive.
The relationship between the power transmitted by the mechanical spindle or the torque and the speed. When the machine is in continuous operation, the spindle speed is in the range of 437 ~ 3500r / min, the total power of the spindle is 11kW, which is the constant power area Ⅱ (solid line) of the spindle. In this area, the maximum output torque (245N.m) of the spindle becomes smaller as the spindle speed increases. Spindle speed in the range of 35 ~ 437r / min, the spindle output torque unchanged, known as the spindle constant torque area Ⅰ (solid line). In this area, the power that the spindle can transmit decreases as the spindle speed decreases. Motor overload (allow overload 30min), constant power area and constant torque area. The overload power of the motor is 15kW and the maximum output torque of the overload is 334N.m.
CNC machine tools in the actual production, do not need the entire variable speed range are constant power. General requirements in the high-speed section for the constant power transmission, in the low-speed section for the constant torque transmission. In order to ensure that the CNC machine spindle low speed when there is a large torque and spindle speed range as large as possible, and some CNC machine tools in the AC or DC motor continuously variable speed on the basis of gear speed, making it a stepless variable speed The
Mechanical spindle maintenance
Reduce the working temperature of the bearing, the usual way is to use lubricants. Lubrication methods are, oil and gas lubrication, oil circulation lubrication two. In the use of these two ways to note the following points:
1, in the use of oil circulation lubrication, to ensure that the spindle thermostat fuel tank sufficient.
2, oil and gas lubrication and oil circulation is just the opposite, it is only filled with the bearing capacity of the space can be. In the case of
3, the advantages of circular lubrication is to meet the lubrication in the case, can reduce the friction heat, and can be part of the spindle components to absorb heat.
4, for the spindle lubrication also has two kinds of put: oil mist lubrication and injection lubrication.