Abstract Based on the actual situation of coal mines, the transformation of ordinary machine tools into economical CNC technology has the characteristics of low investment and quick results, and will have a profound impact on production development, productivity improvement, and improvement of the working environment. Keywords : machine tool, CNC system, transformation, accuracy 1. Transformation Objective Baodian Mine was originally designed with a capacity of 3 Mt/a, but has now reached 5 Mt/a. With the increase in annual output, the investment in electromechanical equipment has increased year by year, and the processing of small batches of parts has increased. Traditional ordinary machine tools can no longer meet the needs of processing capacity and processing accuracy, and the equipment must be updated. Economical CNC machine tools have basic automatic processing functions, are easy to operate and maintain, have high efficiency and high accuracy, and are less expensive than full-function CNC machine tools. If mature economical CNC technology is used to transform the equipment, the funds required for transformation will be reduced by more than half compared with the funds required for equipment replacement, which will not only improve the overall level of the equipment, but also save money. Based on the above situation, the transformation of the 0616-1 type ordinary lathe was implemented. 2. Modification Process 2.1 Modification Scheme The modification will maintain the original lathe structure, only modifying the longitudinal and transverse feed methods, replacing the tool holder with an electric tool post; adding a stroke converter and a code reader, enabling the lathe to achieve CNC automatic longitudinal and transverse feed and retraction, automatic tool changing, and other functions. 2.2 CNC System The CNC system consists of a CNC device and a servo mechanism. The former determines the system's control functions, while the latter determines the CNC system's performance indicators. The economical JWK-15T CNC system suitable for lathe modification mainly consists of a main CPU, slave CPUs, a three-row LED display, an operation keyboard, three reverse stepper motors, and corresponding drive units. The drive circuit has high and low voltage automatic switching, constant current chopping, and overcurrent protection functions; the execution program has single-segment/continuous, stop-at-any-time, overload protection, and emergency stop functions; the system has auxiliary functions such as mechanical origin setting, automatic tool setting, manual operation, and homing. The positioning accuracy of this system can generally reach ±0.01mm to 0.02mm, which can meet the accuracy requirements of machined parts. 2.3 Working Principle of JWK-15T CNC System The overall structure principle of the economical CNC lathe is shown in Figure 1. The CNC device of the JWK-15T CNC system adopts an MCS-51 microcontroller. The control program of the CNC device is the core of realizing various functions. In the part machining program, the specific machining length, movement direction, feed speed, and control program are given. With the support of the central processing unit, according to the input machining program data, after calculation and processing, the required pulse signal is issued. After being amplified by the driver, the stepper motor is driven, and the stepper motor drives the mechanical load to realize the automatic control of the machine tool. When machining threads, the configured spindle pulse generator transmits the spindle angular displacement change signal to the computer. The computer performs insertion according to the set thread pitch and controls the tool post to machine various threads. 2.4 Technical Parameters of JWK-15T CNC System The system installation is shown in Figure 2. 3. Usage Method 3.1 Programming When machining parts on a CNC machine tool, the first step is to program the machining of the parts. The programming methods include absolute dimension method and incremental dimension method. When programming, you only need to master the coordinate system and programming instructions. For example, program a simple part (as shown in Figure 3) to be machined in one go. The motion trajectory is ABCDA. 3.2 Input of Machining Program There are 37 editing keys and 8 control keys, one wave unfolding switch and one power switch, and a set of displays on the operation panel. The operation of inputting the machining program is to input the operation sequence by key according to the part machining program sheet, and the computer will work accordingly. 4. Modification Effect After the lathe was modified, the effect was significant and the expected purpose was achieved. It played an extremely important role in production, mainly in the following aspects: (1) Stable performance and high machining accuracy After the lathe was modified, its CNC system has high reliability. Each component is responsive; the positioning accuracy reaches 0.02mm and the repeatability positioning accuracy reaches 0.01mm. Since the automatic mode of the CNC lathe avoids the human operation error of the producer, the interchangeability of the same batch of machined parts is good and the machining quality is stable. (2) High production efficiency and low scrap rate. Because the spindle speed and feed rate range of CNC lathes are larger than those of ordinary lathes, the most favorable cutting parameters are selected for each process, effectively saving machining time. Moreover, when changing the workpiece, there is almost no need to readjust the machine tool, saving downtime. For the machining of shafts, holes, hemispheres, balls, cones, threads and various complex-shaped parts, the average efficiency is increased by 4 times, and all can meet the design accuracy and technical requirements. (3) Reduce the labor intensity of workers and improve the technical quality of employees. After the transformation, the operation is simple and there is no need for heavy repetitive manual operations. The labor intensity and tension can be greatly reduced, and the working conditions are also improved accordingly. At the same time, CNC lathes require operators and maintenance personnel to have a high level of technical skills. Through learning and training, the technical quality of employees can be improved. The labor intensity of workers is reduced. The physical labor type has been transformed into the "intellectual type". (4) It has played a significant role in market competition. With the rapid development of technology, new parts have more complex shapes, higher precision requirements, and shorter processing time requirements. Due to the transformation of machine tools, it has undertaken a lot of high-requirement external processing parts, which has brought higher economic benefits to coal mines. About the author: Zhao Aijing, female, 37 years old, is currently an electromechanical engineer at the Baodiandie Mine Repair Center. She graduated from Datong Coal School with a major in mechanization in 1984 and from Yankuang Group Vocational University with a major in mining electromechanical engineering in 1998. Click here to download the original text