The numerical control system is the core of the machine tool. When selecting, it is necessary to comprehensively consider its performance, economy and maintenance service. The hardware machine tool network Jinjitong prompts to use brand-name products as much as possible. The CNC system is selected according to the structure and performance of the machine being changed and the accuracy of the parts being machined. As a large machine tool country in China, in order to improve the numerical control rate of machine tools, it is a good strategy to carry out numerical control transformation on ordinary machine tools. Some developed countries such as Germany, the United States, and Japan have attached great importance to the transformation of old machine tools, and have formed a complete transformation system combining production, study and research. Due to the continuous advancement of technology, machine tool transformation has become an eternal subject. China should increase its propaganda in this regard and embark on a road to numerical control transformation of machine tools suitable for China's national conditions.
First, the significance of CNC machine tool transformation 1. Save money. Compared with the purchase of new machine tools, the numerical control transformation of machine tools can generally save 60%~80% of the cost, especially for large and special equipment. Generally, large-scale machine tool transformation only needs to spend 1/3 of the new machine tool purchase fee. Even if the original machine tool structure is completely upgraded and upgraded, it costs only 60% of the cost of purchasing a new machine tool, and the existing foundation can be utilized.
2. The performance is stable and reliable. Due to the long-term aging of the basic parts of the original machine tool, almost no stress deformation occurs and the accuracy is affected.
3. Increase productivity. After the machine tool is modified by CNC, the machining automation can be realized, and the efficiency can be increased by 3~7 times compared with the traditional machine tool. For complex parts, the higher the difficulty, the more the power is improved. And you can use less or less tooling, which not only saves costs, but also shortens the production preparation cycle.
Second, the machine tool CNC transformation program 1. The choice of numerical control system The numerical control system is the core of the machine tool. When selecting, it is necessary to comprehensively consider its performance, economy and maintenance service. The hardware mechanical mold network Jinjitong prompts to choose famous brand products. The CNC system is selected according to the structure and performance of the machine being changed and the accuracy of the parts being machined. It is necessary to match the functions and minimize the excessive numerical control function. In this way, waste of funds can be avoided, and on the other hand, the failure rate increased due to the complexity of the numerical control system can be avoided.
At present, there are three main types of numerical control systems: open-loop system driven by stepping motor; closed-loop numerical control system of asynchronous motor or DC motor drag grating measurement feedback; and semi-closed loop numerical control system of AC/DC servo motor drag encoder feedback. The open-loop system in which the stepping motor is dragged, the servo drive device is mainly a stepping motor, a power stepping motor, an electro-hydraulic pulse motor, and the like. The displacement accuracy of the system is low, but the structure is simple, the debugging and maintenance is convenient, the quality is stable and reliable, the cost is low, the anti-interference performance is strong, the environmental room temperature requirement is not high, and the modification is successful. It is suitable for the transformation of small and medium-sized machine tools with high precision requirements. It is also the most widely used in CNC transformation. Jinjitong suggested that the closed-loop numerical control system of asynchronous motor or DC motor drag grating measurement feedback has high control precision, but it is more complicated in structure than open-loop feed system, large in workload, high in cost, difficult to debug, and generally not used. The semi-closed loop numerical control system of the AC/DC servo motor drag encoder feedback has the precision between the former two. The structure and debugging are simpler than the closed loop system, and it is suitable for the transformation of large and medium-sized machine tools with high control precision.
2. Modification of mechanical parts After the CNC transformation of the machine tool, high static and dynamic stiffness should be achieved. For this reason, the friction coefficient between the motion pairs is small, the transmission has no gap, the power is large, and it is easy to operate and maintain.
For the CNC Lathe, the guide rail should have good friction resistance and small friction resistance in addition to the original precision. At present, it is often used to bond the Teflon soft belt on the original guide rail, which can prevent climbing and has self-lubricating property, can improve the life of the guide rail, has small workload, short cycle and low cost.
The accuracy of the drive chain is affected by the drive screw and gear pair. The price of the sliding screw is low, but it is difficult to meet the processing of parts with high precision; Jinjitong suggests that when the friction loss of the ball screw is small, the transmission efficiency can be above 90%, the transmission is sensitive, the precision is high, the service life is long, and it can be reduced. The motor starting torque can meet the processing requirements of higher precision parts.
In order to ensure the transmission accuracy, the precision level of the gears used on the CNC machine tools is higher than that of the ordinary machine tools, and the gapless transmission is required. Jinjitong suggested that there are two kinds of flexible adjustment methods and rigid adjustment methods for eliminating the transmission gap of the gear pair. The flexible adjustment method has a complicated structure and low transmission rigidity; the rigidity adjustment method has high transmission rigidity and a simple structure.
Third, the machine tool numerical control transformation example analysis Now take the economical CNC lathe as an example to illustrate the transformation points.
1. Choose a digital control system. Imported CNC systems include Japan Fanue, Germany Siemens, and US MCS-8051 systems. The domestic CNC system mainly includes Huazhong CNC and Guangzhou CNC system. These systems have linear interpolation, circular interpolation, car/inch thread, tool compensation, clearance compensation, automatic tool indexing, etc. The performance is stable, the price is moderate, the operation panel is simple and intuitive, there are start button, pause button, Single/continuous switch, continuous feed button, emergency stop button, keyboard, display, etc. Not only the weak current is controlled, but also the spindle shifting, tool post indexing, spindle start and stop and commutation and other auxiliary actions can also be controlled by commands.
2. Ball screw pair modification. In order to achieve the screwless transmission of the screw, the sliding screw of the original machine tool should be changed to the ball screw pair. This item is not a mandatory item. If the accuracy of the machine tool is not high, the transmission gap can be eliminated by pre-tightening the original nut.
3. Stepper motor selection. Jinjitong reminds that the mechanical transmission mechanism should be removed when the lathe is modified in the feed transmission section. Instead, the stepper motor drives the lead screw through the gear or the timing belt and decelerates to drive the tool holder to move. The longitudinal stepping motor is fixed on the bed body, and the lateral stepping motor is fixed on the bed saddle. If the torque of the stepping motor is large enough and the structure is allowed, the deceleration drive mechanism can also be used, and the stepping motor is directly connected to the rolling screw.
4. Automatic tool holder installation. Replace the tool holder of the original lathe with the automatic indexing tool holder. The most common type of horizontal lathe automatic indexing tool holder is the spiral type four-position tool holder. After removing the small carriage, the tool holder is adjusted to the height and installed on the middle carriage. It is directly controlled by the numerical control system, with high efficiency and process performance. reliable.
5. Install the photoelectric encoder. In order to ensure that the stepper motor feed cooperates with the rotation of the spindle when machining the thread, the thread with the fixed pitch, the fixed starting point and the multi-start thread is cut. Usually, the incremental photoelectric encoder is installed at the tail of the spindle. Jinjitong reminds that when the thread is cut, the encoder rotates synchronously with the spindle, and at the same time, a pulse signal corresponding to the spindle rotation angle is issued to control the longitudinal movement of the tool holder.
6. Rail modification. In order to prevent the feed component from crawling, affecting the smoothness of the motion and the positioning accuracy, two methods can be used, one is to attach the original rail to the soft belt; the other is to change to the rolling guide. When the precision of the machine tool is not high, the rail modification is generally not done.
7. Spindle shifting mechanism. The spindle variable speed transformation generally adopts the AC asynchronous motor frequency conversion speed regulation system, and the CNC control inverter and the inverter drive the AC asynchronous motor to realize the automatic stepless speed change. In the case that the degree of automation is not high, the shifting part of the machine tool spindle can be left unchanged, which can greatly reduce the transformation cost. Http://news.chinawj.com.cn Submission:
Aluminum die casting LED light Housing parts
Why choose us:
Good high quality mould and products
Provide best service,at competitive price, Fast Delivery time
As well as engineer's specialized strong experience,professional expertise
Various surface treatments available
OEM /ODM die casting parts are welcome
Specifications
Aluminum die casting LED light Housing parts
Aluminum Structural Frame,Die Casting Mold,Housing Led Cover,Aluminum Die Light Ring
Dongguan Hongge Hardware Technology Co., Ltd , http://www.honggecasting.com