![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
In view of the unstable and difficult maintenance of the Romanian SC125 large-scale CNC vertical car DC drive system, and the poor positioning accuracy of the spindle DC drive system under the milling mode, the replacement of the electric drive system and the spindle indexing system is proposed. Using CNC to control the AC servo drive system transformation plan, completed the selection of seven sets of electric servo drive system, spindle indexing system AC servo motor and feed servo system selection calculation, PLC control software design, CNC system machine parameters Matching adjustments and replacement interface signal connections and overall commissioning for seven sets of electrical servo drive systems. Positioning accuracy and error compensation are completed on the CNC system. Improve the reliability and control accuracy of the electrical system. After the transformation, the spindle indexing accuracy was improved from 11.5s to 3s, and the electric drive system was stable and reliable, achieving the intended purpose.
The structure of the 1SC125 double-column vertical car main shaft indexing system is composed of 820M/820T. There are seven working modes: setting actual value mode, manual data input/automatic machining mode, continuous jog mode, incremental feed mode, repositioning. Mode, automatic machining mode and return point mode.
Two control methods, turning and milling, can meet the requirements of various car milling operations. The PLCs of the two CNC systems work independently and coordinately to complete the sequential control of the electrical and high-voltage interface management and auxiliary equipment. The numerical control system completes the interpolation operation of the position control and has the functions of pitch error compensation.
The spindle is a fully closed-loop position control system with a 18000-line ROD800 circular encoder. There are a number of transmission gears in the position ring, the main function of which is to amplify the torque and improve the load capacity, so that the output torque converted to the final output gear is greatly improved.
2 Selection of AC servo motor in the spindle indexing system The selection of the motor is mainly considered from the aspects of output torque and maximum speed. The spindle indexing AC servo motor adopts 1FT5136-0SC71-1 type Siemens AC servo motor, which is statically turned. The moment is 110Nm, the rated speed is 2000r/min, and the output power is 23W. *M* motor shaft output torque, *Mf? friction torque (since the spindle table uses static pressure rail device, Mf is generally not too large when rotating, the total moment of inertia on the motor shaft is converted. And the rotational inertia of the spindle table rotating motion to the motor shaft. The spindle table can carry up to 400t of workpieces. In this case, the spindle indexing drive system can provide enough dynamic torque Jdx/dt It will become the most important reason for affecting the positioning accuracy. For this reason, we chose a large torque AC servo motor 20Nm larger than the original DC motor. After the transformation, the torque M2>M 2=Mf1. It can be seen that the dynamics of the system can be improved after the transformation. Acceleration dx/dt. 3 Control the speed of the spindle indexing system. Because the performance of the speed drive unit directly affects the positioning accuracy of the machine tool, the speed drive system uses the German Siemens high performance AC servo system 611A. Its connection with the outside is such : Connected to the 380V AC power supply through the reactor through the three-phase fuse and contactor, the cable is directly connected to the AC servo motor; there are two bus bars connected to the power module, the servo is accurate The ready, pulse enable, detection notification signal and control signals of the power module are connected to the I/O module of the PLC; the 611A control enable and feed command signals are connected to the CNC; the logic protection of the system is completed by the PLC.
The position measuring system consists of three parts: a circular grating encoder placed coaxially on the spindle axis; the basic working principle of the measuring system is: when the table rotates, the ROD800 rotates coaxially, generating three sets of signals, A is Sinusoidal signal, B is a cosine signal (A, B phase angles are 90 degrees out of phase), and Z is a triangular wave signal. The three sets of signals are sent to the EXE for amplification, subdivision, shaping and frequency multiplication, and three sets of square wave signals are obtained. These three sets of signals are sent to the numerical control system, and are multiplied by software as position feedback values, and are used by the CRT. Shows the position angle at which the workbench is located. The Z signal is the pulse signal used by the numerical control system to calculate the point. There is only one Z pulse per revolution, and its position is constant. It can only find the point correctly if it matches the position of the deceleration switch block.
4 The machine data and signals related to the feed axis used in the CNC system are adjusted in the transformation to match the machine data to match the modified servo drive system: when programming the PLC control program, the relevant feed axis is used. NC interface I/O signal. The PLC completes the power-on and power-off sequence control of the servo system and the logic control of the electrical protection. The meanings and usage of them are described below.
4.1 MD2601 Gain: Used to match the control system to the servo gain factor defined by MD2521 for accurate matching of tachogenerators.
4.2MD2681 speed setting: as the maximum voltage value of the set speed output. When the set value limit (usually 10V) is exceeded, the interpolation stops (IPOSTOP) and the alarm No. 1041.
4.3MD2801 maximum speed: can accelerate to this speed limit. The programmed G00 moves at this speed.
4.4MD2881 manual feed speed: In manual JOG mode, move at this speed at 100% magnification.
5 Technical transformation of electrical drive system The performance of CNC machine tools depends to a large extent on the performance of the servo drive system. Important indexes such as the maximum running speed, tracking accuracy and positioning accuracy of the machine tool depend on the dynamic and static characteristics of the servo drive system. Because the original Romanian SC125 large-scale CNC vertical car uses its own DC drive system, and the system performance is poor and unstable, often problems, and bring difficulties to maintenance, so decided to replace the transformation with Siemens DC drive system.
Two sets of SIMODRICE6RA27 spindle drive system are used to drive the main turning table and milling shaft. Four sets of SIMODRIVE6RA26 (V3) feed servo drive system drive the feed movement of the tool holder and milling cutter, a SIMODRIVE611A AC servo feed system and motor drive. The main table for milling. The interface control of these seven sets of devices is completed by the PLC.
Connection and commissioning of the 820T with the electric drive system Hardware connection according to the modified RC125 electrical drive design drawing. The computer with the SIMATICS5DOSPLC programming software and the PCIN transmission software is connected to the serial port of the CNC system 820M/820T, and the system can be powered on to start debugging. First, transfer various adjusted machine data, modified PLC machine control program, alarm text information, etc. to the 820M/820T, operate the machine to debug the movement function of each axis, and view the PLC control signals and current status and logic results on the programming machine. Check if the logic relationship of the servo system control interface signal is correct.
In the electrical system transformation, the electrical control cabinet was reconfigured to adjust the parameters of the servo system to make the drive system in optimal operation. The spindle drive system 6RA27 uses automatic optimization adjustment parameters on each mechanical gear position to match the torque of the spindle system and the torque of the current to the mechanical transmission characteristics. The replacement of the seven servo systems adds 25 signal lines to the PLC for control, ensuring that the servo system operates safely and reliably, and solves the problem of pressing the emergency stop button and the Y-axis point is lost. The unreasonable control action process of the original machine tool was improved, and the PLC control program was optimized.
7 Conclusion The Siemens AC feed servo system spindle is selected because of its wide speed range, excellent dynamic characteristics and high speed stability, and constant torque ensures high torque output of the motor at low speed. The control precision of the SC125 large-scale CNC vertical car spindle positioning and indexing system is guaranteed. The replacement and modification of the seven servo drive systems improved the accuracy and reliability of the electric drive control, reduced the failure rate, and achieved the expected results. The SC vertical workbench has a load capacity of 400t, the maximum machining diameter of the workpiece is 12. 5m, the right tool holder is turned, the left tool holder is boring and milling, and the whole CNC is used. These features are ideal for processing large rings in the bore of a hydroelectric forklift. It can greatly improve the processing capacity and product quality of large hydropower. In less than four months, the modified SC125 large-scale CNC vertical car has completed the processing of the outer water distribution ring, control ring and Ertan rotor bracket with indexing processing, and the precision has reached the drawing design and processing. Requirements.
(Finish)
Aluminum radiator for GENERAL MOTORS,Radiator for GENERAL MOTORS,performance fit general motors
JIANGSU KALLER AUTO PARTS THCHNOLOGY CO.,LTD , https://www.jskaller.com