C axis structure of nc vertical curve grinding machine

Nc vertical curve grinding machine of 2019 - C axis structure 03 - 19 BiHongYing ( Qiqihar second machine ( Group) A limited liability company design institute) Nc vertical curve grinding machine as a CNC grinding machine, there is a certain demand in the market, the main function is to set the machine tool parts inside and outside circular curve contour, eccentric inner hole and cylindrical grinding etc. Machine vertical layout, have three nc axes, two of them to linear feed axis, the level of feed the X axis and the vertical feed the Z axis, two axis to the cross slide rack structure, respectively drive the grinding head do feed movement in two directions, another shaft for C axis CNC axis of rotation, driven in workbench for positioning. Technical background at present, the production of many nc vertical curve grinding machine are widespread the problem of low machining accuracy, with the scientific and technological progress and development, have already can't meet the demand of many special parts processing, can not adapt to the modern industrial development demand for components and high precision and machining efficiency, in order to solve this problem for us to come to the conclusion after detailed analysis, find out the key problems: first, can rule out the precision of linear numerical control axis, because this kind of machine tool servo feed motor and applying reasonable pre-tightening force of ball screw connection directly by coupling, and the transmission with the linear guide, under normal circumstances, CNC feed X axis and Z axis positioning accuracy can reach 0. 006 mm / 1000 mm, repeat positioning accuracy can reach 0. 004 mm, can completely meet the requirements of the precision of the machine tool. In this case, the main cause of this kind of grinding machine precision is not high is the shortcomings of traditional C axis transmission mechanism, rotating the workbench positioning accuracy is low, resulting in the whole machine tool machining accuracy is not high. There are two main types of traditional C axis transmission mechanism, is a kind of worm and worm wheel pair transmission, is a kind of gear transmission. Structure of these two kinds of common defects: (1) transmission chain length, usually by the servo motor through a shaft coupling, worm gear and worm pair ( Gear pair) , the main shaft to the workbench, to cause a decline in transmission rigidity. (2) the worm gear and worm pair ( Gear pair) Lateral clearance, even with the double lead worm, use after a period of time because of the wear also can produce clearance. In this case, we design a new type nc vertical curve C axis structure of grinding machine, instead of the traditional structure of C axis, the machine tool rotary table positioning precision is improved, making the overall precision of machine tools have a fundamental improvement. Structure and working principle, 1) C axis structure as shown in the appended drawings, in the bottom of the workbench fixed connection shaft, in order to better positioning shaft, the workbench is equipped with positioning shaft axis of the position, and in positioning the upper shaft equipped with sealing cover, rotor and rotor torque motor through the rotor positioning plate connection, the axis of the upper is equipped with the turntable bearings, centering shaft in the shaft bottom fixed connections, centering in bottom through the lock nut fixed axis rotary encoder ( Circular grating) Dynamic grid, rotary encoder, Circular grating) Set of grid connected to the stator rotating disc, torque motor stator through the stator rotating disc and shaft fixed connection, shaft through a screw and a pin connection with workbench solid base. （ 2) The working principle of the C axis. In the C axis structure, output torque direct drive torque motor C axis rotation, it is a built-in type, small moment of inertia and high output torque motor, the design adopts the pulse number is 36000 / r, accuracy is & plusmn; 2″ High precision rotary encoder, as feedback device of C axis positioning accuracy, C axis to form the whole closed loop structure, the accuracy of C axis from execution to the output are the effective guarantee. The structure of C axis will be too dependent on traditional C axis structure mechanical transmission structure to ensure accuracy, change by electrical signals and numerical control system to control the accuracy. Traditional structure workbench positioning accuracy and repeat precision is more than 15 & Prime; And use after period of time, due to mechanical transmission wear and tear, precision will be significantly lower. After adopting the C axis structure, workbench positioning accuracy is 8. 5″ , repeated positioning accuracy reached 5. 2″ And the rotation of the workbench positioning accuracy stable greatly superior to the traditional structure of C axis. Conclusion this kind of C axis structure compared with the traditional C axis structure has the following advantages: (1) due to cancel the mechanical transmission vice, greatly shorten the transmission chain, driven by torque motor direct drive spindle to rotary table, make the structure simplification, integration, improve the comprehensive rigidity of transmission system. (2) because do not need the complicated mechanical driving pair, so don't need to consider its processing and manufacturing, the more there is no wear and clearance problem, eliminates the reversal of the reverse clearance, but also avoids the influence due to the problem of transmission parts machining accuracy turntable accuracy, so can improve the positioning accuracy of the rotation axis, C and has accuracy stable for a long time. (3) manufacturing and assembly process is simple, the use of long-term, stable performance, simple maintenance and convenient. This kind of C axis structure in the application of nc vertical curve grinding machine, not only improved the precision of machine tools as a whole, at the same time also make nc vertical curve grinding machining scope of much expansion, has been making nc vertical curve grinding machine has wider application. Source: the metal processing ( Cold working) 08, 2018