Welcome to the second chapter of basic knowledge of machine tool CNC. In the previous chapter, we introduced the basic equipment and parameter knowledge of cnc. In this chapter, we will show how the cnc machine works.
Information and data input and output control
The input information and data of CNC include processing program, function parameter, system parameter, machine tool parameter, servo control parameter, spindle control parameter, PMC parameter, tool data, Macro (macro) variable, coordinate system, special software data...these information and Data is input or output by the information input/output operation device through the corresponding data port.
1. Data input and output equipment Currently commonly used I/O equipment in CNC systems are: ⑴. Keyboard: In order to reduce the installation size, it is usually specially designed, called MDI keyboard, to input information and data to CNC for operating CNC unit . ⑵. Machine tool operation panel: various actions of the operator operating the machine tool. ⑶. PC. ⑷. Floppy disk drive (Handy file): FANUC system dedicated equipment. ⑸. Panel-i: Special equipment for FANUC system. ⑹. Flash memory card and so on. If you need more learning materials, the 373600976 group can help you
Each device has a corresponding driver and control program.
2. Data input and output port
The CNC controller is equipped with several data transmission ports for connection with external data devices. ⑴. RS-232C port: Connect to PCs, floppy disk drives and other devices with serial communication ports. ⑵. HSSB: High-speed serial data bus, used to connect with PC or Panel-i, and transmit data at high speed. ⑶. I/O Link: It is a data port based on RS-485, which is a Japanese industrial enterprise standard, and is used to transmit I/O signal information for strong point control of machine tools. ⑷. Ethernet. ⑸. On-site local network. Regarding ⑷ and ⑸, it will be specifically described below.
3. monitor
It is used to display the status and results of the operation and operation of the system, and to display the processing simulation graphics. The current FANUC system has all used LCD monitors. This kind of display is small in size, the color of the color display is rich, and the simulation of the workpiece is very realistic.
six. Centralized control of network and CNC processing
The network of the mechanical processing plant can generally be divided into three levels: the factory level network; the processing unit level network and the lower field network; the factory level and the processing unit level network currently use Ethernet. Processing site network, FANUC system can be equipped with: Profibus-DP; Device
net; FL-Net. Different networks need to be equipped with different network boards
1. ethernet
FANUC CNC-16i/18i/21i, 0i-C can be equipped with 3 Ethernet ports for different purposes: the built-in Ethernet port of the CNC main board, the network board and the network card. Among them, the network card is plug-and-play for temporary use, Such as debugging the ladder diagram; debugging the feed servo characteristics and spindle characteristics of the machine tool....
The network board is a board added to the system, and has a large-capacity semiconductor memory (up to 1GB) instead of a hard disk. It is mainly used to connect with large-capacity data equipment (such as PC) and transfer data and information in batches, such as for mold processing. The built-in Ethernet port on the motherboard can be used for unit control and connected to the unit control host.
2. Live Network
The field network is used to batch transmit I/O control signal information with other devices. For example, in an automatic production line, it communicates with information (signals) of other special processing machinery, loading/unloading machinery, material handling machinery, cleaning machinery, etc. Profibus-DP, Device-net or FL-net can be selected according to requirements or regions. FANUC produced these network boards and developed corresponding supporting software.
3. Centralized Control of CNC Machining
Modern mechanical processing factories (such as automobile engine manufacturing plants) use CNC machine tools not only to make them run alone, but also to combine multiple CNC machine tools and related special equipment such as loading/unloading devices, material conveying machinery, cleaning machines, turning machines, measuring machines, etc. Machines, special processing machines, etc. are connected into an assembly line. These machines are connected with a network, and the centralized management of production is carried out with a computer. The basis of the centralized production management of the entire factory is the centralized control of the processing units.
Processing unit controller: a host computer centrally controls the operation of multiple CNC machine tools. The host computer and CNC system are connected by Ethernet.
In order to realize the centralized control of multiple CNC machine tools, the main computer controlling the processing unit must be able to obtain various information and data of each CNC machine tool, including: ①. The operating status of the machine tool: whether it is in processing operation or standby; whether there is an alarm; Which program to process? Which program segment? Is this processing task over? --.②. The information and data of CNC and machine tools, such as: processing program stored by CNC; processing program running on the machine tool; tool information stored by CNC; tool number on the spindle; number of processed workpieces; processing time; program running time; CNC parameters; servo parameters; spindle parameters; machine parameters; PMC parameters; PMC ladder diagram; macro variables; alarm numbers and information, etc. That is to say, the main computer can monitor the operation of each CNC machine tool in real time
status, for information on performing maintenance on the machine tool.
In addition, the main computer must also: ①. Necessary and sometimes real-time control of each machine tool. For example, the pause and emergency stop of the machine tool; ②. The download of information and data, such as: processing operation instructions; the number of workpieces to be processed; processing programs; tool information; CNC parameters; servo parameters; spindle parameters; machine parameters; PMC parameters ; Ladder diagram of PMC; macro variables and so on. ③. CNC machine tool maintenance and repair guidance information.
End users can develop centralized control software (including production management, planning and scheduling, processing site monitoring, fault diagnosis, etc. software) on the main computer controlled by the unit. The basis for the development of these application software must use the CNC information library and communication software package provided by the manufacturer of the CNC system. FANUC has developed tool software FOCAS (FANUC Open CNC Application Software) for this purpose. Using the instructions provided by the software package, the user can realize the communication between the host computer and CNC, and transmit the information and data mentioned above up/down.
For the convenience of users, FANUC has also developed a cell controller - i-CELL as a commodity. The figure below is the functional block diagram of i-CELL. If the PMC used by CNC is SB7, it can also transmit and display (on the host computer) the ladder diagram of the controlled machine tool. If you need more learning materials, the 373600976 group can help you
seven. Powerful Electric Control of PMC and Machine Tools
Start and stop of machine tools; start and stop of spindle; start, end and stop of processing; start and stop of lubrication and cooling; loading and unloading control of workpiece; tool finding and changing; table exchange; start and stop of auxiliary machines , Stop, etc. These machine tool actions are all executed by contactors, relays, and valves. The control signals for instructing these actions have a certain order or timing among each other, and are interlocked with each other.
Because of the simple operation of ordinary machine tools, it is realized by hard wiring of electrical elements and components (buttons, keys, contacts, coils, etc.) according to the schematic diagram of relay logic, so it is unreliable to operate. CNC machine tools are controlled by PMC logic. PMC is actually PLC (programmable logic controller.) But because FANUC's machine tool control PLC is specially used to control machine tools, there are many special instructions in it, so it is called PMC----programmable machine tool controller. Moreover, the program format FANUC of PMC uses a ladder diagram. The display format of the ladder diagram is very similar to the relay logic diagram of the machine tool, which is intuitive and easy to understand, edit and operate.
As soon as the CNC starts, the PMC program runs. When the CNC executes the machining program, the PMC runs in parallel with the machining program. The PMC scans the input signal of the machine tool or machine operator and the execution result of the control signal of the strong electric cabinet at all times.
To perform various actions on the above machine tool, it is necessary to compile control commands in the processing program: M (miscellaneous function), T (tool change),
B (second auxiliary function).
1. Signals and their addresses
PMC divides the signal into 4 types according to its action part and action direction. If you need more learning materials, the 373600976 group can help you
X: Input from machine tool to PMC. Such as: the operator inputs the button, key and switch signal on the machine operation panel.
Y: The signal output from the PMC to the machine tool to make the machine tool power-on. Such as: forward and reverse of the spindle; lubrication and cooling
on/off signal. The PMC processes the ladder diagram program and outputs these signals to make the machine tool move.
G: Signal output from PMC to CNC (CNC input).
Some of these signals start a subroutine of the CNC. These subroutines are part of the CNC control software:
The strong current control function of the machine tool is designed according to the actual action of the machine tool. Such as: emergency stop (G8.4); automatic processing program start (G7.2); working mode selection (G43.0~2) other signals are PMC to notify CNC to make CNC change or execute a certain operation. Such as: FIN (G4.3)
----It is the PMC notifying the CNC that the auxiliary function M or the tool change function T has finished executing. After CNC receives the signal
It can start the execution of the next processing block; *SSTP (G29.6): the control signal for CNC to stop the spindle motor.
F: The signal output from CNC to PMC.
Some of these signals are signs reflecting the running state of the CNC, indicating that the CNC is in a certain state. like:
AL (F1.0): Alarm state. MV(F102): The feed axis is moving.
Other signals are the results of executing a certain operation after CNC responds to X (through G), and are used to notify PMC.
The PMC receives the signal and handles it appropriately depending on the specific situation.
There are also some signals that are the decoding output of the processing program instructions. Such as: M code (F10~F13); T code
(F26~F29). CNC outputs these signals to PMC for processing.
The above-mentioned signals must be assigned addresses in the ladder diagram program. The addresses of G and F signals are specified by CNC system software and are fixed. Some X signal addresses are also specified by CNC. CNC provides address table. The Y signal can be specified by the PMC designer.
The X and Y signals are connected to the CNC unit by the input/output module through the I/O Link port of the CNC. The other ends of the X and Y signals are connected to electrical components through cables.
2. Internal registers
When compiling PMC programs, in order to save data or signals, PMC uses some internal registers: R, K, D, T,
C, and A.
R: intermediate register. Can be used freely.
K: Holding register. Stored content is maintained by a backup battery. There are several memory cells already used by the PMC system.
D: data memory. Such as storage tool table; speed table of each gear for spindle speed change.
T: Timer. Store timer time.
C: Counter. Store the preset value of the counter, the count value.
A: Display information: store information characters.
3. Function instructions
To compile the PMC (PLC) control logic of a machine tool, it is first necessary to clarify the controlled (to be realized) machine tool action, and arrange the timing of each detail of the action, that is, the step-by-step sub-steps (subtle actions) that will realize the action ) List the sequence table in order, estimate the execution time of the necessary steps, consider the relationship between actions, the interlocking and unlocking conditions between actions, and understand the implementation of various subtle actions and execute PMC instruction for electrical components. PMC logic is to use PMC instructions (language) to express the execution of these subtle actions in sequence. For sequential logic programs, different system manufacturers provide different formats, commonly used are: statement list and ladder diagram. FANUC's PMC logic program uses the ladder diagram format, which is characterized by intuition, similar to the relay logic diagram of the machine tool, so it is very easy to understand.
Moreover, the PMC language uses many special-purpose instructions, called functional instructions. In this way, the logic diagram is compiled quite concisely.
There are about 50 functional instructions of FANUC PMC, but about 20 are actually commonly used, such as: timer, counter, rotation instruction, decoder, etc. The following two pictures are the functional instruction format and the functional instruction set (partial).
4. Ladder diagram
5. Execution of PMC
After the CNC is turned on, the CNC and the PMC run simultaneously. If the PMC receives the X signal from the machine operator to request the CNC to perform a certain operation, such as starting an automatic machining program, the X signal will be sent to G7.2 in the ladder diagram, and the CNC will know that it is to execute the automatic cycle Start a subroutine, that is, execute it immediately. Output F0.5 during execution to notify PMC that CNC is running the machining program.
If the CNC finds M, T and other commands in the program segment when executing the processing program, it will decode the command and send it to the PMC with the F signal address, for example: M code, send it to F10~F13. After PMC processing (decoding, sequence and interlocking), it is sent to the power cabinet through a certain Y address, and the required control actions are performed by the actuator (relay, etc.). If there is a feed axis motion command in the part processing program block where the M command is located, after the controlled axis has completed the required movement amount, it is necessary to judge whether the PMC has executed the action assigned by the CNC (command), so the PMC is required When executing commands such as M and T, a completion signal FIN must be returned. When CNC receives this signal, it can read the next block and execute the next block.
Dongguan Leda Metal Co.,Limited
