The spindle drive system of CNC machine tool is also the main drive system. Its performance directly determines the surface quality of the machined workpiece. Its structure is complex, the machine, electricity and gas are linked, and the failure rate is high. Its reliability will directly affect the CNC machine tool. Safety and productivity. Therefore, in the maintenance and maintenance of CNC machine tools, the spindle drive system is very important. According to the maintenance order, the maintenance personnel go to the site to conduct a fault inquiry investigation, determine the maintenance plan, plan the maintenance work plan, plan the man-hours and expenses; and check the related display interface and circuit schematic diagram of the CNC machine tool plc, the numerical control system and the maintenance of the inverter manual. Data, analyze the cause of the failure; use common tools and multimeters to detect and determine the fault location, quickly eliminate the fault at the machine tool site, fill in the maintenance record and hand over the acceptance.
Spindle-related knowledge The CNC machine tool spindle drive system is a high-power actuator for CNC machine tools. Its function is to accept the S code speed command of the CNC system (CNC) and the M code auxiliary function command to drive the spindle for cutting. It includes a spindle drive, a spindle motor, a spindle position detection device, a transmission mechanism, and a spindle. Usually, the spindle drive is rotated by the workpiece, and the corresponding machine is a lathe; the spindle-driven cutting tool rotates by milling, and the corresponding machine is a milling machine.
Spindle system classification and characteristics The main drive system of full-function CNC machine tools mostly uses stepless speed change. At present, the continuously variable transmission system mainly has two types of variable frequency spindle system and servo spindle system according to different control modes. Generally, a DC or AC spindle motor is used, which drives the spindle to rotate through the belt drive, or through the belt drive and the reduction gear in the spindle box ( For greater torque), the spindle rotates. In addition, according to the different spindle speed control signals, it can be divided into two types: analog-controlled spindle drive and serial digital-controlled spindle drive. The analog-controlled spindle drive unit adopts the inverter to realize the spindle motor control, and has a general-purpose inverter control general-purpose motor and a special inverter-controlled special-purpose motor. At present, most of the economical machine tools adopt the form of numerical control system analog output + inverter + induction (asynchronous) motor, which is very cost-effective. At this time, the analog spindle can also be called the variable frequency spindle. The serial spindle drive unit is generally developed and produced by various CNC companies, such as the 611 series of Siemens and the α series of Japan FANUC.
1. Ordinary cage asynchronous motor with gear transmission This is the most economical method of spindle configuration, but only achieves stepwise speed regulation. Since the motor always works at the rated speed, after the gear is decelerated, at the low speed of the spindle. The output torque is large and the heavy cutting ability is strong, which is very suitable for the requirements of roughing and semi-finishing. If the processed product is relatively simple, the spindle speed is not too high, and the configuration can also be very good on the CNC machine; its disadvantage is that the noise is relatively large, because the motor works at the power frequency, the spindle speed range is not large. It is not suitable for non-ferrous metals and machining applications that require frequent spindle speed changes.
2, ordinary cage asynchronous motor with simple inverter can achieve stepless speed regulation of the spindle, the spindle motor only works at about 500 rev / min or more to have a satisfactory torque output, otherwise, especially the lathe is easy to block In the case of two gears or belt shifting, the spindle can only work in the medium and high speed range. In addition, due to the limitation of the maximum speed of the ordinary motor, the spindle speed range is greatly limited.
This solution is suitable for applications that require stepless speed regulation but are not required for low speed and high speed, such as CNC drilling and milling machines. There are many simple inverters produced in China.
3, through cage asynchronous motor with general-purpose inverter currently imported general-purpose inverter, in addition to U / f curve adjustment, generally also has no feedback vector control function, will improve the low-speed characteristics of the motor, with two-stage gear shifting It can basically meet the processing of small machining allowance at low speed (100-200 rev / min) of lathe, but it is also limited by the maximum motor speed. This is the spindle drive system that is commonly used in economical CNC machine tools.
4, the special frequency conversion motor with general-purpose inverter generally uses feedback vector control, low speed or even zero speed can have a large torque output, and some also have the function of orientation or even indexing feed, is a very competitive product. Take the first YPC series variable frequency motor as an example, voltage: three-phase 200V, 220V, 380V, 400V optional; output power: 1.5-18.5KW; frequency conversion range 2-200Hz; (maximum speed r/min); 30min150% overload capacity ; Support V / f control, V / f + PG (encoder) control, no PG vector control, PG vector control. The manufacturers that provide general-purpose inverters are mainly foreign companies, such as: Siemens, Yaskawa, Fuji, Mitsubishi, Hitachi, etc.
The mid-range CNC machine tool mainly adopts this scheme. The two-speed shift of the spindle drive can realize the gravity cutting of the car and the milling when the speed is about 100-200r/min. Some directional functions can also be applied to CNC boring and milling machines that require fine machining. If it is applied to the machining center, it is not ideal. It must use other auxiliary mechanisms to complete the function of directional tool change, and it can not achieve rigid tapping. Claim.
Machines with electric spindles are mainly used for finishing and high-speed machining, such as high-speed precision machining centers. In addition, it is widely used in engraving machines and non-ferrous metal and non-metallic materials processing machines. These machines usually do not require spindle drives because they only require high spindle speed.
In terms of electrical control, the control of the machine tool spindle is different from the servo axis of the machine tool. In general, the control system of the machine tool spindle is the speed control system, and the control system of the machine tool servo axis is the position control system. In other words, the spindle encoder is generally not used for position feedback (and not for speed feedback), but only as a speed measuring component. The data obtained from the spindle encoder generally has two purposes. One is for the spindle speed display; the other is for the occasion where the spindle and the servo shaft work together (such as thread cutting, constant line speed machining, G95 feed, etc.).
High Voltage Laboratory Power Supplies
The LTP series laboratory high-voltage power supply is a high-voltage power supply specially designed for high-voltage laboratory applications with high precision, high stability, and low ripple output characteristics. Built in 19 inches, 2U standard chassis with designed output power at 1KW and output voltage ranges 1KV to 60KV.
After optimizing the output stability and output ripple on the basis of the 1KW high-voltage power module, the stability and ripple of the high voltage lab power supplies can reach the level at 0.1%.
The high-voltage laboratory power supply is also a constant-voltage and constant-current type high-voltage power supply. The output voltage and current can be continuously adjusted from 0 to the rated value via the added control potentiometers added to the front panel, high resolution LEDs display for output KV and mA are also added for intuitive measuring of high voltage laboratory bench.
The lab high voltage power supply is also equipped with DB9 interface as standard. Customers can apply 0-10V signals and dry contact signals to the interface according to our interface definition to achieve comprehensive control and monitoring functions on the power supply, like high voltage start / stop, output setting and reading.
The LTP series laboratory high voltage power supply is equipped with complete protection functions, which can deal with sparking, short circuit, overload, load discharge and other situations.
At present, the high-voltage laboratory power supply is mainly used in Laboratory power, High-voltage test stands, Electrostatics, Capacitor / Insulations testing and Electrophoresis applications.
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