CNC system transformation precision thread grinder
If the numerical control system of the machine tool uses the economical numerical control system at that time, the single-board machine is used as the main control unit, the number of I/O ports is small, and the programming is cumbersome, which cannot meet the requirements of this machine tool. If the FANUC and SIEMENS systems are used, the price is very expensive. The SKY CNC system developed by Nanjing Sikai Electronic Enterprise Co., Ltd. is implemented on a common computer platform. It uses 32-bit 80386 CPU, with 270M hard drive, 1.44M floppy drive and 14-inch color display, using a complete set of computer such as a standard keyboard as the main control unit, the number of I / O ports can also meet the needs of different program control. It can also be used as a normal computer when the machine is not working. The driving component can be a servo motor or a stepping motor. The numerical control system works on the UCDOS Chinese character operation platform, and can realize two-axis or three-axis linkage. Although its price is slightly more expensive than the ordinary economical numerical control, the performance price ratio is more than 3.5 times that of the general economical numerical control system. The SKY CNC system communicates with the outside world using the COM1 serial port or the extended serial port of the computer. The I/O communication port fully satisfies our use.
We use the F1-MR60 programmable controller and the F1-ER60 expansion unit manufactured by Mitsubishi Corporation of Japan as the controller of the machine tool. The communication between PLC and NC has 30 bits and is completed by two serial ports. The execution of the NC program is carried out under the control of the PLC program, completely accommodating the original functions and operation modes of the machine tool. In order to adapt to the operation mode and function of the original machine tool, the numerical control programming method we used is similar to the R parameter programming method. The operation mode of the original machine tool dial and key input CNC data is all changed to the Chinese character operation screen of the numerical control system. On, set/select parameters and select the operation mode. We simplifies all operations and enters the system initialization state as soon as it is turned on. The operating instructions interface or machine tool interface of the machine can be selected according to the prompts on the display. In the operation description interface, we have compiled the operation method and safe operation procedure of the SKY numerical control system for the machine tool. In the machine tool interface, we use the grinding method of the machine tool (manual / automatic, one-way grinding / two-way grinding, rough grinding / semi-finishing / fine grinding), grinding cycle times, grinding wheel dressing mode (manual / Automatic), coarse grinding, fine grinding feed rate, grinding wheel dressing times and dressing amount parameters are listed on the screen one by one, only use the ↑, ↓, ←, → cursor keys on the keyboard to select and modify. At the same time, the dynamic size of the workpiece during machining is also displayed on the screen.
The driving components of the CNC system are three stepping motors, namely: grinding wheel feed motor, grinding wheel dresser feed motor and table drive screw clearance compensation motor. The stepping motor and the transmission ball screw are meshed by a pair of gears. Among them, the driven gear is formed by a pair of 1/2 active gear tooth width gears, and the two gear springs generate a certain misalignment angle, which can automatically eliminate the meshing gap of the main and passive gears. The head frame of the machine tool rotates the DC motor to use a three-phase asynchronous motor, and uses the Japanese Mitsubishi variable frequency speed control system for AC stepless speed regulation. Since the motor and the head frame shaft are connected by a belt, according to the range of the working speed of the machine tool, the appropriate gear ratio is selected to make the motor work between 25 and 60 Hz, which ensures the good mechanical characteristics and good starting characteristics of the head frame motor. The rotation of the headstock is constant during the operation of the machine, so the speed adjustment is only adjusted by the speed potentiometer.
Due to the large difference in the size of the workpiece blanks, manual grinding is required for some of the larger working blanks, so manual grinding is retained. In manual mode, in addition to the manual grinding wheel feed, the grinding wheel dressing and the table screw clearance compensation are automatically fed according to the preset amount.
To ensure the safe operation of the machine, we have set up a safety protection system and a forced interrupt function.