Design of X2010A Gantry Milling Machine Control System Chen Yijuan\Lu Jin2, Yan Guangli1 (1. School of Mechanical and Electrical Engineering, Shaanxi University of Science and Technology, Xianyang, Shaanxi 712081, China; 2Department of Electrical Engineering, Shaanxi Institute of Industrial Technology, Xianyang 712000, China): Introduced X2010A Gantry Milling Machine Control System The design scheme gives the PLC control program block diagram and the control schematic diagram and parameter setting result of the DC speed control drive system.
Bla:kdiagram; Planemiller is a heavy-duty machining machine for machining large parts. It is often used to mill the surface of parts. It can also be boring, drilling and other forms of machining. The movement of the original X2010A gantry milling machine is the rotation of the left and right horizontal headstocks and a vertical headstock. The spindles are driven by AC asynchronous motors and mechanically graded.
The feed motion includes the front and rear movement of the workbench. The left and right horizontal headstock moves up and down along the column. The vertical headstock moves left and right along the beam (shares a motor, uses a selection switch and an electromagnetic clutch to concentrate the drive), and the drag motor is a DC motor. The silicon controlled rectifier device is powered, and the armature voltage is steplessly adjusted.
Since the original X2010A gantry milling machine uses a large number of contact elements such as relays, contactors, and stroke switches in the entire control system, the feed drive uses a thyristor-DC motor system (SCR-D), and the trigger circuit uses separate components, resulting in the entire The reliability of the machine tool during operation is poor, the maintenance frequency is high, and the role of large machine tools cannot be fully utilized. To this end, it is necessary to redesign the X2010A gantry milling machine control system.
1 Design scheme Under the premise of maintaining the original X2010A gantry milling machine mechanical transmission system and operation mode, the programmable controller (PLC) is used as the main controller for the characteristics of the machine tool and the problems of the control system. The action between the moving parts replaces the relay-contactor control circuit and replaces the thyristor rectification system with a digital DC speed control device. The control scheme is as shown.
The main movement of the X2010A gantry milling machine consists of the lifting motion of the three spindles, the æµ -2 , and the three spindles of the feed beam. Due to the start and stop of the hydraulic pump, the selection switch of the worktable and the three spindle heads and the execution of the electromagnet have a simple control relationship, and are directly controlled by external buttons and switches, so that the input and output points of the PLC are not occupied. Each feed direction is equipped with an overtravel protection switch, the feed motion is provided with jog/continuous operation mode, and the worktable and three spindle headstocks have positive and negative feed and fast forward and reverse functions. According to the control characteristics of the original machine tool, the operation of each part of the machine tool can be selected, and the CPM1A-40DCR type PLC of OMRON company can be selected.
The design of PLC control program is mainly based on the working mode, logical cross relationship and control requirements of the original machine tool, and pay attention to the interlocking relationship between the various movements. Since all feed operations share a DC motor, the hydraulic solenoid valve is used to reverse the feed in different directions, so the feed action (including the beam lift) must be performed after the hydraulic system is working properly and the pressure relay is activated. (1) The rise and fall of the feed and the beam must be interlocked, that is, the beam must be clamped during the feed motion. (2) The interlock between the spindle and the feed. When starting, the spindle is started first, then the feed operation can be performed; when stopping, the feed is stopped first, then the spindle is stopped; when the emergency stop is reached, the control block diagram of the feed is stopped. The spindle delay stops. The block diagram of the program is as shown.
12 DC speed control drive system design, the original X2010A gantry milling machine feed system meters with thyristor-DC motor speed control system, the base speed below the pressure regulation speed, the base speed above the weak magnetic speed, rapid feed, The magnetic field is reduced by half and the speed is doubled. According to the speed regulation characteristics of the machine tool, the British Continental 590 series all-digital DC motor speed control device is adopted. The device adopts PI regulator with adaptive current loop to achieve the best dynamic performance, and the current loop has self-tuning function. Adjustable PI speed loop with integral separation function; with tachogenerator feedback, wide speed range and perfect protection function; all parameters can be set through serial port, button and display. The control principle is as shown.
The control schematic KM9 is a hydraulic pump start contactor, and the C5 end is connected in series with the KM9 contact. The purpose is to enable the enable end 5 of the DC drive to be activated after the hydraulic pump is started. The start/run of the C3 terminal is controlled by KA, and KA2, KAi is connected, the terminal is ON*, then the feed is forward, KA2 is turned on, and the B4 terminal is “ON*, then the reverse feed; fast run by C4, Q The terminal decides that KA3 is turned on, and the C4 terminal is "ON*, and the forward direction is fast, KA3 and KA4 are simultaneously turned on, and the C4 and Q terminals are simultaneously *ON*, and the shell I" is reversed quickly. Pay attention to the polarity of the tachogen generator when commissioning.
The 590 Series unit provides more than 470 parameters to adjust to different applications and different loads. These parameters are preset at the factory. Most of the parameters can be changed during use. Only individual parameters can be adjusted and Set, the parameters changed by this system are: ramp: ramp acceleration time = 5.0s ramp deceleration time = 3.0s ramp rate = 2.0s current loop: proportional gain = 24.68 integral gain excitation: excitation control mode = CURRENT (current control) = ENABLE Downtime = 7.0s Speed ​​Loop: The parameters of the proportional gain current loop are automatically adjusted by the auto-tuning function. The parameters are self-tuned according to the automatic tuning conditions and sequence to obtain the best corresponding characteristics. Other parameters are artificially adjusted according to the debugging conditions.
2 Conclusion PLC acts as the main controller to coordinate and control the movement of the whole machine. The feed motion is realized by the digital DC speed control system. Through the parameter adjustment, the feed motion is started and stopped smoothly. The operation panel is equipped with armature voltage, armature current, excitation current, and motor speed indication, which is intuitive and easy to operate. The structure of the machine control system is greatly simplified, which reduces many sources of interference and improves the anti-jamming capability of the system. The gantry milling machine control system has been running online for more than 3 years. It is safe, reliable and stable. It provides new methods and ideas for the transformation of large-scale equipment similar to the working mode of the portal milling machine, and will achieve better social and economic benefits.
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