Five aspects analysis and the research status of numerical control lathe in our country
Five aspects analysis and the research status of numerical control lathe in our country release time: 2016 - 08 - 18 clicks: numerical control lathe in our country from 1950 to enter the market in the early 1970 s, through the unremitting efforts of the major machine tool manufacturer, by adopting the cooperation with foreign famous machine tool manufacturers, joint venture, technology introduction, digestion, absorption, prototype makes the machine tool manufacturing level had the very big enhancement, its production occupies a large proportion in the metal cutting machine tool. At present, domestic CNC lathe more complete varieties, specifications, quality stable and reliable, and has entered the stage of practical and all-round development. 1) Lathe bed according to the relative position of the lathe bed guide rail surface with horizontal plane and lathe bed 5 kind of layout form. In general, medium and small sizes of CNC lathe with slant bed lathe bed inclined slide in the majority of the peace, only large or small precision CNC lathe CNC lathe using flat bed, bed using less. Flat bed good manufacturability, easy processing and manufacturing. Due to the tool post in horizontal, is good for improve the movement precision of the tool post, but the chip removal difficult; Head cross slide is longer, increase the width dimension of the machine tool, and affect the appearance. Flat bed inclined board structure, configuration on the tilted guide rail protective cover again, keep the flat bed already so good advantages in usability, also too won't big bed width. Peace slant bed CNC lathe bed inclined board structure is widely used in modern numerical control lathe, because this kind of layout form has the following features: (1) easy to realize mechanical and electrical integration; (2) the machine appearance is neat, beautiful, cover an area of an area small; (3) easy to set up a closed protective device; (4) easy to chip removal and installation of automatic chip removal device; (5) cut off from the workpiece accumulated hot chip not effect the precision of guide rail on the guide rail; 6. Good agreeableness, easy operation; Being easy to install manipulator to realize single machine automation. 2) Guide of CNC lathe guide can be divided into sliding guide rail and rolling guide. Slide guide has a simple structure, convenient manufacture, contact stiffness big advantages. But the traditional sliding guide rail friction resistance is big, wear fast, dynamic and static friction coefficient difference is big, easy generation when low speed crawl phenomenon. At present, the CNC lathe is not the traditional sliding guide rail, but adoption with wear-resisting stickup layer slide guide and new plastic sliding guide rail. They have good friction performance and long service life, etc. Rolling guide is the advantages of small friction coefficient, dynamic and static friction coefficient is very close, will not produce the crawling phenomenon, can use grease lubrication. According to different roller, the rolling guide can be divided into ball linear guide and roller linear guide. The latter's bearing capacity and stiffness are higher than the former, but slightly larger friction coefficient. 3) Spindle drive system of nc lathe main drive system can be divided into the hierarchical variable speed drive and stepless variable speed drive. Hierarchical variable speed drive is in a certain range can be uniform, discrete distribution with finite series of rotating speed, it is mainly used for ordinary machine tools. Stepless speed change form can be within a certain range of continuous change speed, satisfy the requirement of processing in order to get the best speed, can in the running speed, ease of automatic transmission. Numerical control lathe winners usually adopts stepless variable speed drive system. Compared with the ordinary lathe, CNC lathe, straight motor spindle speed is used in the main drive system, motor speed range, and can stepless speed regulation, make the spindle structure is greatly simplified. In order to adapt to different processing requirements of CNC lathe main drive system has three ways. 4) Tool holder system according to the different methods of tool change, numerical control lathe tool holder system mainly include rotary tool rest, rest and take knife library automatic tool change device such as a variety of forms. Platoon type CNC lathe tool rest are used for small specification, mainly processing bar or plate parts. Rotary tool carrier is the most commonly used one kind of typical for CNC lathe tool rest, through the rotation of the tool post graduated positioning to achieve the automatic tool change machine action, according to the processing requirements can be designed into four, six party head or disc type tool rest. According to head back to the bottom of shaft and installation of the relative position, divided into vertical tool rest and horizontal rotary tool slide rest two kinds. Row of knife rest and rotary tool post has certain limit to the number of the cutting tool, while the number of need more tools, should be used with knife library automatic tool change device. 5) Feed drive system of numerical control lathe feed drive system generally adopts feed servo system, according to the control methods of different systems can be divided into the open loop and closed loop system. The former position precision is low, but it has simple structure, reliable operation, low cost; The latter high control precision, fast performance is good, but it is high to the requirement of machine tool, and the cost is expensive. Closed-loop system using the position detection device are: pulse encoder, rotating transformer, inductosyn, magnetic tape, such as grating ruler and laser interferometer. The feed servo system of nc lathe is servo motor drive device. Dc servo motor and servo motor ac servo motor. The former because of its high reliability, low cost and widely used.