Numerical control transformation design of ordinary lathe

According to the development of production and the need of mechanical automation, the main business should propose the transformation design scheme of 6140 lathe with microcomputer numerical control system with 8031 ​​single chip as the core, and elaborate the hardware design and working principle of the hardware control system of the single chip control system. 1 Introduction With the rapid development of social production and computer technology, the performance and quality of mechanical products are continuously improved, and the pace of product upgrading is accelerating, which not only requires high machine tool processing precision and productivity, but also requires rapid adaptation. Replacement of product parts. In this form, CNC machine tools were born and developed rapidly.

CNC machine tools can not only solve the complex shape, precision small batch of multi-variable parts processing, but also stabilize the processing quality and improve production efficiency, but the price is expensive. If a large number of ordinary machine tools are completely replaced by CNC machine tools, it will cause A lot of resources are wasted, so it is the most effective way to carry out numerical control transformation on ordinary machine tools.

CNC transformation refers to the transformation of certain parts of ordinary machine tools, coupled with numerical control devices, so that the machine tool has CNC machining capability. The hardware design and working principle of the MCU control system will be elaborated in detail. Introduce the overall plan for the economical NC transformation of 0.64, ordinary lathe.

Due to the processing accuracy requirements of economical CNC machine tools, the structure is not very simplified. cut costs. A stepper motor open loop control system can be used. The system uses a microcomputer to control the vertical and horizontal feed system; the continuous control system is selected to ensure that the economical CNC lathe after the transformation has positioning, linear interpolation, reverse interpolation, and suspension. Cyclic machining, metric thread processing, etc.; in order to achieve the required resolution of the machine tool, the stepper motor is used to reduce the speed and then drive the screw; to ensure the fixed transmission accuracy and stability, minimize the friction force, select the ball wire In order to improve the transmission rigidity and eliminate the gap, the structure with preloading is adopted. In addition, according to the requirements of the machine tool, the 10551 series 8031 ​​is also adopted, which has the characteristics of high integration, good reliability, system, easy to send, etc., and the price. Low cost, it is more common in China's numerical control transformation, the overall system of the system frame 1.

3 CNC system hardware circuit design 3.1 basic hardware components Any CNC system is composed of hardware and software. Hardware is the basis of the circuit, and its reliability directly affects the performance of the CNC system. The machine hardware circuit consists of the following parts: the central processing unit 0, the bus, including the data bus address bus and the control bus; the memory, including the program memory and the data memory interface, that is, the 10 input output interface circuit; the peripheral device. Such as keyboard display and photoelectric input machine.

Among them, 1 is the core of the numerical control system, its function is to carry out data operation processing and control the coordination of various parts of the circuit; the memory is used to store the system software application and various data required in the operation; the interface is the system exchanges information with the outside world The bridge is a link between the memory interface and other conversion circuits, and is the only way to exchange information and communication with some circuits; and the peripheral device is a window for the numerical control system to interact with humans.

3.2 system hardware design 8, 3 single-chip and expansion chip consists of the basic system mine interface chip. The single-chip microcomputer system adopts the internal clock mode and utilizes the internal oscillation circuit of the chip. The working frequency is 1212. Since the 8031 ​​chip has no on-chip ruler and 阽, the external program memory is expanded as needed when composing the control system, considering that the lathe program is more complicated. Reducing the number of chips, the 27256 versa 01 with a capacity of 321 is used as the extended external program memory; and since the 8031 ​​is only 128 bytes in the chip, it is far from meeting the needs of the system. Here, the static of 8kB capacity is selected! As the data memory; the system's extended interface circuit uses a programmable general-purpose parallel interface circuit 8155 chip. The minimum system and output interface circuit structure composed of 8031 ​​single-chip microcomputer, 23 system uses the 74143373 latch of the strip state buffer output as the address latch when the external memory expands. The system uses full address decoding, and the eight output lines of the 38 decoder 74138 respectively correspond to eight 8 to 8 address spaces. The stepping motor adopts a software ring distributor. Although the running speed is not as fast as the hardware ring distributor, the two hard ring distribution special chips can be omitted, and the circuit is relatively simple. From the mouth output of the 8155, the motor is directly driven by the power amplifier circuit of the photoelectric isolation circuit. When the automatic rotary tool holder is required to change the tool, the tool position signal is sent by the 8155, and the tool holder motor is controlled to rotate to reach the specified tool position. After the tool holder is clamped, the tool change response signal 3 is sent through 8!55, 85 Enter the computer and control the knife holder to start feeding. When the thread is machined, the photoelectric pulse generator connected to the spindle sends a thread signal and a zero thread signal, which are respectively sent to the 8031. And 8155 86. By setting different time constants to process different pitch paths ±± direction of the crossing and emergency stop signal through the door of the door 31, interrupt source 1. At the same time, it is connected to the 8031, port, adopt The method of applying for interrupt and software query by hardware, so that no matter which direction is out of bounds, it will cause an interrupt, and the method of checking by software in the interrupt service program. You can determine which direction is out of bounds. When ±± and other directions are out of bounds, the corresponding red light alarms and the external device keyboard and display connected to the MCU are the medium for man-machine dialogue. The movement of the CNC lathe can be manipulated through the keyboard to realize the processing control of various parts. The keyboard interface circuit of the system uses a special keyboard display interface chip 8279 to realize automatic scanning of the keyboard display by using 8279. And know, the key number of the closed key on the keyboard. Not only can the operation time of the keyboard be greatly reduced, the burden is reduced, and the program is simple. No misoperation, 4 CNC system software design The programming of the single-chip numerical control system adopts the block design technology, mainly by the system management program; the input and output device management program of the part processing source program; the manual control program of the machine tool; System compiler; interpolation program; servo control and switch control program; system self-test program. Control system software structure box 3.

The system management program is an indispensable component of the control system software. It receives the operator's commands from the operation control panel, completes the CNC system according to the commands, and is scattered in other programs. When the other functions are executed, the self-test is performed. The software embodying the numerical control system is the system compiler program interpolator servo control and the switch quantity control program. The part processing program is processed and processed by these several programs, and finally the target information for controlling the movement of the machine tool can be generated.

5 Conclusion After a lot of practice, the numerical control transformation of ordinary machine tools has certain economical practicability and stability. The modified economical CNC lathe single-chip numerical control system circuit described in this paper is simple and practical, and the software system is also easy to maintain and modify, which can be used for reference.

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