Nc milling machine is a kind of automatic processing equipment which is developed on the basis of general milling machine. The machining process of the two is basically the same and the structure is similar. Nc milling machine is divided into two categories: no knife and knife. The CNC milling machine with the tool bank is also called machining center.
In addition to the characteristics of normal milling machine, numerical control milling machining has the following characteristics:
1. Good adaptability and flexibility in the processing of parts, which can be used to process parts that are particularly complex or difficult to control dimensions, such as mold parts, shell parts, etc.
2. Parts that can be processed by ordinary machine tools that cannot be processed or difficult to process, such as complex curved parts described in mathematical models and three-dimensional space curved parts;
3. After being able to process the positioning of the clamping, the parts that need to be processed by multiple processes are required;
4, high machining precision and machining quality is stable and reliable, pulse equivalent of CNC equipment usually is 0.001 mm, high precision can be up to 0.1 mu m CNC system, in addition, also to avoid the numerical control processing operator error;
5. High degree of production automation can reduce the labor intensity of operators. Facilitate the automation of production management;
6, high efficiency, CNC milling machine generally do not need to use special process equipment, such as special fixture in replacing artifacts need to call a stored in the process of numerical control device, clamping tools and adjusting tool data, thus greatly shorten the production cycle. Secondly, nc milling machine has the function of milling machine, boring machine and drilling machine, which makes the process highly concentrated, which greatly improves the production efficiency. In addition, the spindle speed and speed of the CNC milling machine are infinitely variable speed, so it is advantageous to choose the best cutting amount.
The basic structure
Numerical control milling machines have various forms, different types of CNC milling machines are different in composition, but there are many similarities. This paper introduces the composition of XK5040A CNC vertical milling machine. Ⅺ saw 040 a type nc vertical milling machine is equipped with four 3 Ⅳ ma CNC system, using digital ac servo driver. The machine tool consists of 6 main parts. It is the bed part, the milling head part, the worktable part, the horizontal part, the lifting platform part, the cooling, lubricating part. The internal layout of the bed is reasonable, with good rigidity, with 4 adjusting bolts on the base, easy to adjust the machine tool, and the cutting fluid reservoir is located inside the machine tool base.
The cooling system. Cooling system of machine tool is by the cooling pump and nozzle, outlet pipe, water pipe, switch, etc, cooling pump installed in the inner cavity of the machine tool base, cooling pump liquid storage pool play within the cutting fluid from the base to the outlet pipe, and then through the nozzle, to cool the cutting zone.
2. Lubrication system and manner. The lubrication system is made up of manual - run - pump, oil separator, throttle valve, tubing and so on. The machine adopts the cycle lubrication method, and lubricates the main shaft sleeve, crossbar and three ball screw rod through the oil separator to improve the service life of the machine tool.
From the characteristics of digital control technology. The adoption of the nc machine tool servo motor, application of digital technology has realized the execution parts of nc machine tools work order and the direct control of movement displacement, the transmission of traditional machine tool structure is cancelled or partially canceled, so also greatly simplifies the mechanical structure. Numerical control also requires the mechanical system to have high transmission stiffness and no transmission gap to ensure the execution of control instructions and the realization of control quality. At the same time. Due to computer level and constantly improve the control ability, on the same machine tools allow more parts at the same time needed to perform all kinds of auxiliary functions has become possible, and mechanical structure of nc machine tools is higher than traditional machine tools have integrated functional requirements.
Look from the demands of the development of manufacturing technology, with the emergence of new materials and new technology, as well as the competition in the market demand for low-cost, metal cutting processing is moving toward cutting speed and accuracy is higher and higher, the production efficiency is higher and higher, and the direction of the system more reliable. This requires that the numerical control machine tools developed on the basis of traditional machine tools are more accurate. The driving power is more, the mechanical mechanism is more static, the thermal stiffness is better, the work is more reliable, can realize the long time with the continuous operation and as little downtime as possible.
Milling head part
The milling head consists of two parts, such as a class (or no class) gearbox and a milling head. Milling head spindle support on high - precision bearing. Ensure the spindle has high rotation accuracy and good rigidity; The spindle is equipped with a quick changing nut, and a tip cone is used for 1$0505 taper. The main shaft adopts mechanical stepless speed change, its adjustment range is wide, the transmission is stable, the operation is convenient. The brake mechanism can quickly brake the main shaft, which can save the auxiliary time, brake the brake handle by holding the stop ring to brake the main shaft immediately. When starting the main motor, the spindle brake handle should be loosened. The milling head is also equipped with servo motor, internal gear wheel, ball screw and spindle set, which form vertical direction (z direction) to drive chain, so that the main shaft is vertical and straight.
The table and the bed saddle are supported on the horizontal guide rails of the platform. The vertical feed of the workbench is driven by the servo motor mounted on the right end of the workbench. The precision ball screw is cut through the inner gear wheel, so that the workbench can get the vertical feed. The left hand side of the table is equipped with handwheel and dial for manual operation. TuRcllE B is applied to the vertical guide surface of the bed saddle, which improves the wear resistance of the guide rail, the stability of the movement and the retention of precision, and eliminates the low-speed crawling phenomenon.