Spindle refers to the workpiece or tool axis of rotation to drive the machine. Usually by the spindle, bearings and transmission parts (gears or pulleys) etc. spindle components. The machine is mainly used to support transmission parts such as gears, pulleys, transmits the motion CK0620 CK0620 CNC lathe spindle lathe spindle and torque, such as machine tool spindles for workpiece clamping and some, such as the mandrel. In addition planer, broaching and other main motion is linear motion outside the machine, most machines have a spindle assembly. Motion accuracy and structural rigidity spindle unit is an important factor in determining the processing quality and cutting efficiency. Performance indicators to measure the spindle assembly is mainly rotational accuracy, rigidity and speed of adaptation.
Rotation accuracy: radial and axial spindle is rotated in the direction of the machining accuracy of the beating occurred (see geometric tolerances), mainly on the manufacture and assembly of the spindle and bearing quality, dynamic and static stiffness: mainly on the spindle bending stiffness, bearing stiffness and damping. Adaptability speed: the maximum permissible speed and speed range, mainly determined by the structure and lubricated bearings.
Electro-spindle CNC machine tools in recent years in the field of emerging new technologies and the spindle spindle motor integration, it is with linear motor technology, high-speed cutting tool technology together, we will put into a new era of high-speed machining. Electric spindle is a set of components, including electric spindle itself and its accessories: electric spindle, high-frequency inverter device, oil mist lubrication, cooling system, built-in encoder, tool changer.
The integration of the electro-spindle technology: High-speed bearing technology: electric spindle usually a composite ceramic bearings, wear resistant, life is a traditional bearing several times; sometimes with electromagnetic levitation bearings or hydrostatic bearings, inner and outer rings are not in contact, in theory, Unlimited life;
High-speed motor technology: electric spindle motor and spindle together is the product of the rotating part of the motor rotor shaft is, in theory, can be seen as a high-speed electric spindle motor. The key technology is the high-speed balancing under;
Lubrication: Spindle lubrication commonly used regular quantitative oil lubrication; can also be lubricated with grease, but the corresponding speed should be discounted. The so-called timing is every certain time interval Note oil. The so-called quantitative is through a device called quantitative valve, precise control of each lubricant oil. The oil-air lubrication, referring to the lubricating oil in the compressed air by carrying, is blown into the ceramic bearings. Oil control is very important, too, would not achieve lubrication; too much, when the bearing is rotating at high speed due to the oil and heat resistance. Cooling means: In order to get back to the electro-spindle cooling high-speed operation, usually spindle coolant to circulate through the outer wall, the role of the cooling device is to maintain the temperature of the coolant. Built-in pulse coder: in order to achieve automatic tool changer and rigid tapping, spindle built a pulse encoder for accurate phase angle control and coordination with feeding.
Automatic tool changer: In order to apply to the processing center, electric spindle equipped with an automatic tool changer, including disc spring, broach cylinder etc; high-speed tool chucking way: widely familiar with BT, ISO tool has been proven not suitable for high speed machining. It appeared HSK, SKI and other high-speed cutting tool in this case. High frequency inverter device: For the electric spindle tens or even hundreds of thousands of revolutions per minute speed, must use a high-frequency inverter device to drive the internal high-speed spindle motor, the output frequency of the inverter must reach thousands or thousands of hertz . CNC machine tools generally use DC or AC servo motor for the spindle shaft CVT.
AC spindle motor and AC variable frequency drive (AC cage induction motor is disposed vector conversion frequency control system), because there is no brush, no spark, so long life, and the performance has reached the level of DC drive system, even in noise there is still decreased. Therefore, it is applied more widely.
Relationship between power or torque and rotational speed of the spindle transfer. When the machine is in continuous operation, the spindle speed is within 437 ~ 3500r / min range, transfer all power 11kW spindle motor, spindle constant power region Ⅱ (solid line). In this region, the maximum output torque of the spindle (245N.m) with the increase of the rotational speed of the spindle becomes smaller. The spindle speed is within 35 ~ 437r / min, and the output shaft torque constant, called the constant torque region Ⅰ spindle (solid line). In this region, the spindle can deliver power with lower spindle speed increases. Shown motor overload (to allow overloading 30min), the constant power and constant torque region dotted line area. Overloaded motor power is 15kW, the maximum output torque overload 334N.m.
CNC machine tools in the actual production without over the entire speed range are constant power. General requirements in the high-speed section of constant power transmission in low speed constant torque transmission. CNC machine tool spindle in order to ensure greater torque at low speed and spindle speed range the maximum extent possible, any CNC machine tools with a gear change on the basis of AC or DC motor CVT on CVT making segment .