(1) The data input device inputs command information and various application data into necessary devices of the numerical control system. It can be a perforated tape reader (which is rarely used), a 3.5in floppy disk drive, a CNC keyboard (general input operation), a hard disk and drive unit for the CNC system (for large data storage protection), and a tape drive (less) Use), PC, etc.
(2) CNC system The center of the CNC machine tool, which decodes and calculates all the function commands received, and then sequentially issues various required motion commands and control commands for various machine functions until the end of motion and function.
The numerical control system has a perfect self-diagnosis ability. In daily use, it is more important to pay attention to strict operation according to regulations, and daily maintenance is mainly to protect the hardware use environment and prevent system software damage.
(3) Programmable logic controller is the logical control center of various functions of the machine tool. It logically sorts the various motion and function commands from the CNC, enabling them to operate safely and in an orderly and safe manner. At the same time, it transmits various information and working status from the machine tool to the CNC, so that the CNC can issue the information in time and accurately. Further control commands thus achieve control of the entire machine.
Contemporary plc is mostly integrated in the numerical control system, which mainly refers to the integration of control software, while PLC hardware often adopts a distributed structure in large-scale systems. The integration of PLC and CNC is realized by software interface. The general system assigns various communication information between them to their fixed storage address. The system monitors the information status of all addresses in real time, according to the current status of each interface signal. The state is analyzed and judged, and further control commands are made accordingly to complete the control of the movement or function.
Different manufacturers' PLCs have different PLC languages ​​and different language expressions. Therefore, the prerequisite for familiarizing with a machine tool PLC program is to familiarize yourself with the PLC language of the machine tool.
(4) The spindle drive system accepts the drive command from the CNC, and the output drive signal is driven by the speed and torque (power) to drive the main motor to rotate, and the speed feedback is implemented to implement the speed closed loop control. It also informs the CNC of various real-world working states of the spindle through the PLC to complete the function control of the spindle.
The spindle drive system itself has many parameter settings. These parameters directly affect the rotation characteristics of the spindle. Some of them cannot be lost or changed, such as parameters indicating the specifications of the motor. Some of them can be modified according to the operating status, such as zero drift. . Usually, the spindle-related machine data is also provided in the CNC, and it has the same function as the parameters of the spindle drive system. Therefore, pay attention to the two, and do not conflict.
(5) The feed servo system accepts the speed command provided by each CNC from each motion coordinate axis, and the output drive signal is driven by the speed and current (torque) to drive the servo motor to rotate, realize the movement of the machine coordinate axis, and accept the speed feedback signal. Implement speed closed loop control. It also communicates with the CNC through the PLC to inform the current working status and accept the control of the CNC.
The correct adjustment of the feed servo system speed regulator is of the utmost importance and should be optimally adjusted under the condition of open loop position, neither rushing nor maintaining a certain hard characteristic. It is subject to the mechanical characteristics of the machine axis. Once the state of the rail and the mechanical drive chain changes, the speed loop regulator needs to be re-adjusted.
(6) Electrical hardware circuit With the continuous enhancement of PLC function, the main tasks of electrical hardware circuit are power generation and control circuit, isolation relay part and various types of executive electrical appliances (relays, contactors), and rarely relay logic circuits. exist. However, some imported machine tool cabinets also use the special combination type relays with certain logic control. Once such components fail, in addition to replacement, they can be removed and replaced by PLC logic, but this requires not only The working principle of the special electrical appliance has a clear understanding, and it is necessary to deeply grasp the PLC language and program of the machine tool.
(7) The machine tool (electrical part) includes all motors, solenoid valves, brakes, various switches, and so on. They are rapporteurs who implement the various actions of the machine and the various realities of the machine. Most of the major faults possible here are damage to the electrical device itself and disconnection or breakage of the connecting wires and cables.
(8) Speed ​​measurement is usually done by a tachometer that is housed in the main shaft and the feed motor. It matches the actual motor speed to a voltage value and sends it back to the servo drive system as a speed feedback signal, which is compared with the commanded speed voltage value to achieve precise speed control.
Here, attention should be paid to the matching connection of the speed feedback voltage, and do not disassemble the speed measuring machine. The resulting speed loss is mostly due to the reverse or disconnection of the speed feedback line.
(9) Position measurement In earlier machines, linear or circular synchronous sensors or resolvers were used, while modern machine tools mostly used grating scales and digital pulse encoders as position measuring components. They measure the actual position of the machine axis in operation directly or indirectly, and feed back the measured value to the CNC and compare it with the commanded displacement until the axis reaches the command position, thus achieving precise control of the position.
The faults that may occur in the position loop are mostly hardware failures, such as contamination of the position measuring component, wire connection failure, and the like.
(10) External devices generally refer to output devices such as PC computers and printers, and most of them do not belong to the basic configuration of machine tools. The main problem in use is the same as the input device, which is a matching problem.
Newmax Electronics Co.,Limited , https://www.advvape.com