| With the progress of machine industry and technology, according to the actual need of the production, upgrading of machine tools has become a new economic growth industries, based on whole or partial structure upgrading to existing machine, we can improve the technical performance indicators. Based on the GS30 CNC lathe of Yibin 812 factory, which used SIEMENS S3TT numerical control system and it is a kind of two-NC, two-channel control machine tool and has a pair of turret, one spindle, one vice-spindle, four-control axis, good performance, strong working ability and has been listed as a key equipment in 812 plant, upgrading to this lathe has adopted by this paper. However, the CNC lathe has been in use for nearly two decades, some aspects has been aging and wear, such as electrical,machinery,etc. and the control system is also fall behind relatively, resulting in a heavily failure rate and parking rate, it has influenced the quality and progress of nuclear power plant components in 812 factory.This CNC lathe is the main force in factory, and taking into account the complete functions, intact main features, good lubrication system, properly working hydraulic system and intact mechanical transmission system, the accuracy of machine decreased only, so the transformation to this machine is more economical and reasonable than a updated horizontal machining center which have a equal specification with the transformed machine. Under the above background, we have made the following rehabilitation programs after analyzing the original machine's technical status.(1)We selected the current advanced Siemens 840D CNC system to replace the original Siemens S3TT system to improve the machine stability after considering the electrical control features, the machining operation features, price and other factors of GS30 CNC machine tools;(2) We used the 611D CNC system AC servo drive units which is compatible with the 840D system, the 1FT6 AC servo motor which has high-precision, low inertia and high-resolution position feedback and the 1PH7 induction motors which has high-power and high-response instead of the original analog DC drive and DC motor to ensure the shaft power and torque and achieve free maintenance of motor; (3) Replacing the X, Z, U, W-axial lead screw nut to improve the precision;(4) Making a new operation station, allocating a CNC panel, CNC keyboard and control panel.First this paper discussed the problem of GS30 CNC lathe and the transformed goal, determined the overall technology program; second we selected the Siemens 840D CNC system as a control device, chosen each module's model number matching with 840D, made the machine electrical diagrams and developed PLC software program. In the end, the various parameters of the machine was set up, the lathe was checked and accepted after completing the mechanical parts and digital servo system debugging. The results show that the performance and accuracy meet or exceed the original machine, fully meet the requirement of high precision, high efficiency and high reliability to nuclear components, and the total cost is a quarter of the price of imported machine tools in the same grade. |
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