1、 Cost performance analysis of NC transformation and renewal of machine tools
Before the old machine tools of Dongguan CNC plant are transformed into CNC, the price of CNC machine tools with the same performance in the market should be investigated. When comparing the two prices, the delivery time should also be considered. For small CNC lathe and milling machine with low price, it is suggested to purchase new machine tools instead of old ones. Because the difference between the two costs is not much, save less money, machine transformation time is about 2 months. For small CNC lathe, milling machine, machine tool manufacturers generally have stock. It is a better choice for large and expensive machine tools to carry out numerical control transformation, which can not only save more money, but also shorten the purchase time. For example, a table size is 2000 × The comparison of horizontal machining center with 1800mm, three-axis linkage and 60 cutters is as follows.
2、 To investigate the present situation of the machine tools to be reformed
Not all old machine tools in Dongguan CNC plant are suitable for CNC transformation, so we should have a comprehensive understanding of the machine tools to be transformed. The mechanical system of the machine tool should be mapped to make a correct judgment. Good mechanical performance is the basic condition for the success of the NC transformation of the machine tool. Otherwise, the best NC system can not play its due performance. Therefore, before the NC transformation of the machine tool, the mechanical accuracy of the machine tool should be tested, and the problems found can be repaired during the implementation of the machine tool transformation. If there are many problems in the mechanical system of the machine tool, such as the defects in the mechanical structure design and manufacturing of the old machine tool, the NC transformation of the machine tool will not be of great significance.
The electrical system of the old machine tool is the key work of the machine tool transformation because of the aging of the components. To understand the old machine tool CNC system manufacturer model, the number of control shafts, spindle, feed shaft drive configuration, spindle motor power, feed shaft motor torque, etc. Check whether the attached technical data are complete. Complete technical data can shorten the technical preparation time for machine tool transformation. Among them, electrical schematic diagram, PLC program, machine tool maintenance manual, hydraulic, pneumatic, lubrication schematic diagram, mechanical assembly drawing, etc. should be carefully studied. In particular, it should be noted that the contents provided in the technical data may be wrong and inconsistent with the actual machine tool. This is because some machine tool manufacturers provide general drawings of series models, and the electrical hardware changes of individual machine tools are not indicated on the electrical data, which requires us to check carefully with the actual machine tools to avoid mistakes.
3、 Determination of NC transformation scheme of machine tool
Based on the surveying and mapping of machine tools, Dongguan NC machining plant determines the overall machine tool transformation scheme according to the requirements of users.
1. Transformation scheme of numerical control system
The transformation of the machine tool, first of all, is the transformation of the numerical control system, according to the existing control level of the machine tool, workpiece processing requirements, enterprise financial situation, choose the corresponding low, medium and high-grade numerical control system. For example, FANUC and Siemens systems can be selected for foreign CNC systems, and Huazhong and Kandi systems can be selected for domestic CNC systems. It should also be consistent with the CNC system selection of other existing CNC machine tools as far as possible. The advantage of this is that it is convenient for the maintenance personnel to maintain the machine tool daily; More centralized CNC system is also easy to reduce the types of spare parts. The choice of numerical control system is based on the principle of practicality, so there is no need to waste money to pursue a higher level.
2. Transformation scheme of spindle servo system
The old CNC machine tool spindle control generally adopts DC servo or AC analog servo drive system. According to the needs of use, the original drive device and spindle motor can not be retained, and the AC digital servo drive system can be used instead or the inverter control can be used. It can also keep the original drive system, such as AC analog servo drive system in good condition; The DC servo drive system can keep the DC motor in good condition, and use the new DC servo control device to replace the old drive device.
3. Transformation scheme of feed servo system
Similar to the transformation scheme of spindle servo system, AC digital servo drive system can be used instead of the original drive device and motor according to the use demand; It can also keep the original drive system, such as AC analog servo drive system in good condition.
4. Transformation scheme of closed loop control detection device
Dongguan CNC plant can replace the inductosyn / ruler of old machine tools with round grating and grating ruler. When selecting the type, attention should be paid to the consistency of interface signal between the detection element and the system, square wave signal or voltage signal. If the grating ruler of the old current signal is retained, a conversion device from current signal to voltage signal is needed to match the new system, because most of the new systems do not support current signal.